Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
Center for Physical Sciences and Technology, Lithuania
Zhou Bing Chen
The Hong Kong Polytechnic University, China
California State University of Northridge, United States
University of Lodz, Poland
Ronald R. Willey
Willey Optical, Consultants, Charlevoix, MI, USA
Pao Ter Teo
Universiti Malaysia Kelantan (UMK), Malaysia
Budapest University of Technology and Economics, Hungary
Tokyo University of Science, Japan
University of Mississippi, USA
University of Reims Champagne Ardenne, France
Brenda Mbouamba Yankam
University of Nigeria, Nigeria
Emmanuel Péres de Araújo
Military Institute of Engineering, Brazil
bA. Galkin Donetsk Institute for Physics and Engineering, Ukraine
Mario Nogueira Barbosa Junior
Pontifical Catholic University of Rio de Janeiro, Brazil
Madhuri Chandrashekhar Deshpande
Vishwakarma Institute of Technology, India
Cornell University, Ithaca, New York, USA
Linyi people's hospital, China
Pontificia Universidad Católica de Chile, Chile
Jesus Anselmo Tabares
Universidad del Valle, Colombia
Chungnam National University, South Korea
Beijing Institute of Technology, China
Hamadan University of Medical Sciences, Iran
Maria Fortuño Morte
Jaume I University, Spain
National Institute for Environmental Studies, Japan
Shiv Nadar University, Uttar Pradesh, India
Korea University of Technology and Education, South Korea
Md Salah Uddin
University of Texas Permian Basin, United States
CNRS University of Rouen UMR 6634 GPM laboratory, France
Swapan K Saha
Indian Institute of Astrophysics, India
ITMO University, Russia
Pablo Fuentealba Castro
University of Chile, Chile
Institute of Metal Research Chinese Academy of Sciences, China
Research Institute of Technology, Shougang Group Co., Ltd., China
Breno Rabelo Coutinho Saraiva
Federal University of Ceará, Brazil
University Carlos III of Madrid, Spain
Pedro Paulo Medeiros Ribeiro
UFRJ Federal University of Rio de Janeiro, Brazil
University of Murcia, Spain
Jung Hyun Kim
Yonsei University, South Korea
Jawaharlal Nehru Technological University Hyderabad, India
Vincenzo De Leo
University of Bari Aldo Moro, Italy
María Francisca Gómez-Rico Núñez De Arenas
University of Alicante, Spain
Valencia Polytechnic University, Spain
Polytechnic University of Valencia, Spain
Akdeniz Pe-Tur A.S., Turkey
Interdisciplinary Science and Engineering Laboratory, University of Delaware, United States
Ana M.O. Azevedo University of Porto, Portugal
Protein discrimination using erythrosin B-based GUMBOS
In the past years, sensors have attracted increased attention as a facile and cost-effective approach for protein detection and discrimination. Different scaffolds have been employed for construction of sensors, including polymers, substituted porphyrins, and oligopeptide-functionalized resins 1. GUMBOS (Group of Uniform Materials Based on Organic Salts) have emerged as a promising class of materials for accurate identification of protein analytes. These compounds share similar features to those of ionic liquids, but have wide applicability potential due to their melting point range (25-250 ºC) 2. In this context, the usefulness of four novel erythrosin B (EB)-based GUMBOS as recognition elements for proteins with distinct molecular weights and isoelectric points was assessed. GUMBOS were synthesized using a simple metathesis reaction between the anionic dye (EB) and several phosphonium and ammonium cations. The effect of pH and incubation time on the discriminatory power was studied, being the assays performed in aqueous media at pH 3.0, 4.5, and 6.0 for 5, 10, and 15 minutes. Upon exposure to proteins, each sensor generated distinct absorbance response patterns that were analyzed using partial least squares discriminant analysis (PLSDA). The proposed sensing approach offers an interesting alternative to conventional analytical methods since it is simple (label-free) and rapid (only five minutes of equilibration time are required). Moreover, at pH = 6.0, EB-based GUMBOS allowed discrimination of five serum and non-serum proteins with 100% accuracy. The ability of GUMBOS to detect and discriminate between four distinct protein mixtures containing albumin and myoglobin was also studied. These binary mixtures were distinguished from each other with nearly 90% accuracy.
Marcelo Machado Viana Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
Polydimethylsiloxanes-modified TiO 2 coatings: The role of structural, morphological and optical characteristics in a self-cleaning surface
The surface modification of TiO 2 thin films with hydrophobic agents has been a good strategy
to modulate the surface energy of this material, allowing it to be compatible with a wider
range of applications . This is a promising approach in the search for self-cleaning
properties, since it is expected that the modified films will exhibit photocatalytic and
superhydrophobic properties. In this work, the synthesis and characterization of TiO 2 thin
films modified with two different types of polydimethylsiloxane (PDMS): hydroxy (AHH)
and vinyl-terminated (AHV) were carried out. PDMS modification of TiO 2 thin films
occurred on two different routes. Route 1 was obtained from the deposition and subsequent
thermal treatment of neat TiO 2 thin films (anatase phase), followed by a surface
functionalization with a solution of PDMS in toluene. Route 2 is based on the preparation and
deposition of a sol-gel solution containing both TiO 2 and PDMS precursors. The thin films
prepared were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM),
X-ray photoelectron spectroscopy (XPS), diffuse reflectance and wettability tests. Vinylic
coatings showed a hydrophobic behavior, while hydroxy coatings proved to be hydrophilics.
PDMS-modification occurred by a covalent functionalization with the formation of Ti–O–Si
bonds to the AHH and Ti–O–C bonds to AHV hydrophobic agent. The wettability test
evidenced significant differences in the contact angle between a water drop and the sample
surfaces and, in the roughness, as evidenced by AFM. This study contributed to a better
understanding of a heterogeneous functionalization of TiO 2 thin films using a non-fluorinated
polymer as a hydrophobic agent and using a faster and environmentally friendlier procedure
for improved the self-cleaning coatings design.
Steponas Ašmontas Center for Physical Sciences and Technology, Lithuania
Impact of cesium concentration on optoelectronic properties of metal halide perovskites
Metal halide perovskites attract considerable attention due to their superior properties having potential applications in optoelectronic devices such as solar cells, photodetectors, light emitting diodes. In solar cells, metal halide perovskites are atractive for their high absorption coefficient allowing to use a thin film, high defect tolerance, high carrier mobility, and long carrier diffusion length. Excellent band gap tunability allows using perovskite layer as a top sub-cell on any bottom cell. Currently, the best solar cells use a mixture of formamidinium (FA) and methylammonium (MA) as the monovalent cations. Addition of cesium makes the triple cation perovskite compositions more thermally stable as they have less phase impurities and are less sensitive to processing conditions.
The triple cation perovskite layers were formed by a one-step deposition method from the produced precursor solution. Anhydrous N,N-dimethylformamide/dimethylsulfoxide (DMF / DMSO), 4:1 by volume, was used as a solvent. Material concentrations of the prepared solution were: 1 M of formamidinium iodide FAI, 1.1-1.3 M of PbI2, 0.2 M of methylammonium bromide MABr, 0.2 M of PbBr. Then CsI solution (1.5 M of CsI in DMSO) was added to the prepared precursor, and CsI concentration was varied from 0 to 50%. The prepared precursor solution was used to form a perovskite compound Csx(MA0.17FA0.83)(100-x)Pb (I0.83Br0.17)3. The layers were deposited by means of programmable centrifuge. FTO glass covered with thin TiO2 film was used as a substrate. The perovskite layers were annealed for 60 min in an inert atmosphere at 100°C temperature.
In this communication, we present experimental study of optical properties of perovskite layers with different cesium concentration as well as photoelectric properties of solar cells fabricated on their base.
Zhou Bing Chen The Hong Kong Polytechnic University, China
Mechanisms for suppressing discontinuous precipitation and improving mechanical properties of NiAl-strengthened steels through nanoscale Cu partitioning
High-strength low-carbon steels are of considerable technological importance in engineering applications such as automotive, shipbuilding, and energy industries. Precipitation strengthening is an effective method for strengthening low-carbon steels. Among various potential precipitates used for precipitation strengthening, NiAl is one of the most effective phases to achieve high strength, and the precipitation of which occurs either continuously or discontinuously. Control of discontinuous and continuous precipitation is crucial for tailoring the microstructure and mechanical properties of NiAl-strengthened steels. In this talk, we will report that Cu is effective in not only promoting the nano-scale continuous NiAl precipitation but also in suppressing the coarse-scale discontinuous NiAl precipitation at grain boundaries, which results in the development of new NiAl-strengthened steels with high yield strength (1400 MPa) and good ductility (10%). Our analyses indicate that the mechanisms for suppressing discontinuous NiAl precipitation are twofold. The main one is the acceleration of continuous NiAl precipitation through Cu partitioning, which swiftly reduces the matrix supersaturation, thereby decreasing the driving force for the growth of discontinuous precipitation. The other is the reduction of grain boundary energy through Cu segregation, which is likely to decrease the nucleation rate of discontinuous precipitation. Consequently, Cu increases the number density of NiAl nanoparticles by more than fivefold, which leads to a twofold enhancement in the strengthening and an improvement in the over-aging resistance of NiAl-strengthened steels.
Anna Bezryadina California State University of Northridge, United States
Nonlinear self-trapping and guiding of light in biological suspensions
The study of nonlinear processes in biological samples is crucial for developing new methods for fabrication of new bio-photonics devices and for developing low-loss transmission for deep-tissue imaging. In the last decade, significant work was to study deep-penetration of light and formation of optical waveguides in dielectric and metallic colloidal suspensions with tunable polarizability. In this work, we discuss formation of waveguide structures in biological suspensions for a range of wavelengths. Specifically, several centimeters long biological waveguides, with no significant photodamage of the cells, have been successfully demonstrated in colloidal suspensions of cyanobacteria, E. coli, and red blood cells (RBCs).
According to the forward-scattering theoretical model, cells in colloidal suspensions get attracted toward the center of the beam due to the optical gradient force, and simultaneously move along the laser beam due to the scattering force. Since living cells usually have a slightly higher index of refraction than the surrounding media, the optical force-induced nonlinearity leads to a self-lensing effect along the beam path, which allows for the formation of a biological "fiber".
Biological samples often have various absorption bands that need to be either targeted or avoided in opto-fluidic micromanipulation or biomedical imaging. However, sometimes the preferred wavelengths may not be suitable to exhibit nonlinear self-guiding and waveguide formation. To overcome this challenge, we implement a pump/probe-type nonlinear coupling, where formed biological waveguides provide effective guidance for a weaker laser beam. Finally, we investigate the conservation of polarization and orbital angular momentum through these scattering bio-soft-matter suspensions. We expect that these studies will help in developing alternative solutions to transmit energy and information through scattering media, as needed in communications, deep-tissue imaging, treatment and diagnostics.
Magdalena Małecka University of Lodz, Poland
The analysis of Hirshfeld surface as a tool supporting the prediction of new compounds with desired physicochemical properties
Searching for the new materials used in various fields e.g. in pharmacology, biology and material science is very important and attracts more and more attention from researchers. Undoubtedly, crystallographic studies that confirmed the molecular structure of newly designed and invented materials help in these studies. Crystallographer answers not only the question what the molecular structure is, but also gives the information about the arrangement of the molecules in the crystal lattice and intermolecular interactions.
The analysis of Hihrshfeld surface has become an invaluable tool for crystallographers and crystal engineers alike. The new tool, Crystal Explorer program, which uses Hirshfeld Surface approach calculates interaction energies and visualizes the topology of intermolecular interactions are central to modern first-principle approaches to the prediction and designing the molecule with desired properties. This tool was used in our studies in the following cases:
1. the attempt to correlate cytotoxic properties and non-covalent interaction for 14 compounds with experimentally proved cytotoxic potential against cancer cell lines, and for others biologically active compounds,
2. the attempt to find the relation between fluorescence and crystal packing and self-assembly for promising luminescent material,
3. the attempt to discover relationships between lattice energy calculations and energy framework visualization and global reactivity descriptors,
4. quantitative analysis of hierarchy of intermolecular interactions.
The above approach has following outcome: provide useful descriptors for structure-activity relationship studies and give the quantitative analysis of the hierarchy of intermolecular interactions, which could be helpful in the modelling both the cytotoxic activity and luminescence properties.
Ronald R. Willey Willey Optical, Consultants, Charlevoix, MI, USA
Variation of Indices of Refraction of Nano-Thickness Metal Layers with Thickness, Materials, and Simulation Models
Optical thin film layers of silver and other materials on the order of 10 nm effective optical thickness can vary significantly in index of refraction, n and k. These properties vary with the materials which interface with the thin silver layers and with the processes and post processing used to deposit and treat those layers. Once a given combination of materials and processes have been characterized over a range of thicknesses from 2 to 50 nm, this data can be used to design coatings to most nearly provide the percent reflectance and transmittance versus wavelength desired. Various procedures to extract the n and k of a film from spectrophotometric measurements are provided. Cautions to minimize errors in the procedures are given, and processes to confirm the accuracy of the obtained results are described. Fitting of %T and %R spectral data are often used successfully but tend to provide less than satisfactory results in the presence of large absorptance. In cases of metal films where high absorptance is present, piecewise fitting is beneficial. However, in some cases, there are multiple solutions (similar to the case of a square root), and the proper solution depends upon having starting values for n and k which are close to the real values. A technique for obtaining good starting values is discussed. How well the measured data can be fitted with functions that allow simulation in the design process depends on the models used in the fitting process.
Pao Ter Teo Universiti Malaysia Kelantan (UMK), Malaysia
From ‘Waste’ to ‘Wealth’: Recycling of Food, Agricultural, and Industrial Wastes as Pore Forming Agents for Sustainable Porous Ceramic Production
Utilizing various wastes in ceramic production has been growing worldwide. This work provides an extensive literature review on the utilization of food, agricultural, and industrial wastes as pore-forming agents (PFAs) in sustainable porous ceramic production. The literature conducted since 2010 indicates that waste-based porous ceramics has versatile properties with excellent performances. Determination of waste material and clay properties as well as processing conditions such as material composition, sintering temperature, and compaction pressure, which influence pore formation in ceramics, has been comprehensively provided. These factors significantly influence the properties of the resulting porous ceramics, including physical, mechanical, and toxicity properties. Recycling food, agricultural, and industrial wastes for increased energy saving and green ceramic production can be realized as an economical and practical approach to sustainable waste management, which align well with achieving sustainability in a circular economy and the UNESCO’s Sustainability Development Goals (SDG). Achieving zero food, agricultural, and industrial wastes can eliminate environmental burdens and pave the way for closed-loop production. In overall, the waste-based porous ceramics can pave the way for sustainable environments, expanding the economic sector, particularly alternative building materials.
Róbert Várdai Budapest University of Technology and Economics, Hungary
Improvement of the impact resistance of three-component hybrid PP composites with polymeric fibers
The demand of the industry for newer and better materials increases continuously resulting in constant research and development efforts to satisfy this demand. For structural and automotive applications, the impact resistance, stiffness and strength of composite parts are crucial factors. The requirement is often large stiffness, but good impact resistance at the same time. Glass and carbon fiber reinforced polymers have been used for decades, but increasing environmental awareness and also some economical aspects created much interest for natural fibers and reinforcements. Natural reinforcements have many advantages, they come from renewable resources, they are lighter than glass, cheap and they have positive environmental impact, but there are some drawbacks as well. The quality depends on the origin of the crop, the fibers are sensitive to heat during processing, their adhesion to the polymer matrix is often poor, they absorb moisture, etc. The proper selection of the matrix polymer, the fiber and composition may lead to the required strength and stiffness for most applications. In this study polypropylene (PP) hybrid composites were prepared by the combination of traditional reinforcements (wood, glass, carbon, talc) and polyvinyl alcohol (PVA) fibers. Impact resistance is improved because the presence of the flexible polymeric fibers increases the number of potential energy absorbing mechanisms in the composites. Interfacial adhesion was regulated with the use of maleated PP (MAPP). The aim of this study was the determination of the effect of polymeric fibers on the impact resistance of three-component hybrid PP materials and the identification of the deformation and failure mechanisms occurring during deformation. The results obtained proved that impact modification with polymer fibers works for all reinforcements. The overall properties of the hybrid composites prepared are acceptable, sufficiently large stiffness and impact resistance being achieved for a large number of structural applications.
Shin Aoki Tokyo University of Science, Japan
Combinatorial synthesis of metallosupramolecular phosphatases formed by the self-assembly of functionalized building blocks
Design and synthesis of artificial catalysts that mimic the natural enzymes such as hydrolases and phosphatases remain a great task in the fields of supramolecular chemistry. It is described that artificial enzyme mimics have some disadvantages such as i) lack of long-range interactions between catalysts and substrate and/or between functional groups in their active sites, ii) the requirement of time-consuming synthesis, and iii) being active mostly only in organic solvents. These drawbacks could be overcome by supramolecular methods utilizing the self-assembly of functionalized artificial molecular units.
Herein, we report on the construction of various metallosupermolecular complexes by the self-assembly of bis(zinc(II)-cyclen) complex containing a 2,2’-bipyridyl (bpy) linker, functionalized barbital units and Cu(II) ion as model compounds of alkaline phosphatase that catalyzes the hydrolysis of phosphate monoesters such as mono(4-nitrophenyl)phosphate (MNP).1-3 The formation of these supermolecules and their hydrolysis activity in a single aqueous phase1 and in two-phase solvent system2,3 was studied. It was found that these supramolecular complexes accelerate the MNP hydrolysis in a catalytic manner with the catalytic turnover number (CTN) of 3-4. It was also found that the hydrolysis obeys Michalis-Menten kinetics. In this presentation, these results will be presented.
Arunachalam Rajendran University of Mississippi, USA
Computational modeling of fiber composites under impact loading
In this paper, computational modeling of the response of fiber reinforced composite (FRC) or glass fiber
reinforced plastics (GRP) due to impact loading is considered using two different approaches. The first
approach employs a material point method (MPM) based in-house code to explicitly model the
fiber/matrix architecture (Fig. 1) with the constituents modeled as linear elastic solid and maximum
tensile strain failure criterion1. It appears that the orientation of mesoscopic structure with given fiber
geometry and property in FRC, instead of the matrix material, governs the impact response. The matrix
material failure could be either brittle or ductile with a trivial effect on the impact response. The second
approach employs the Arbitrary-Lagrangian-Eulerian (ALE3D) code along with a hyperelastic
constitutive model to describe the continuum response of the GRP. The shock wave experimental data
for GRP provides an opportunity for the model developers to analyze damage evolutions using advanced
finite element codes in conjunction with appropriate damage models2.
Both approaches modeled the same plate impact configurations described in reference 2. Plate impact
simulations of a metallic flyer impacting a woven glass-fiber reinforced plastic (GRP) at various
velocities are performed using both the MPM and ALE3D codes. GRP VISAR data from a series of onedimensional
strain-based shock wave experiments were utilized in the calibration of a continuum damage
mechanics (CDM) model. The experimental data included D7 Tool Steel and 7075-T6 aluminum flyer
plates and two different GRP thicknesses (6.8 mm or 13.6 mm) at various impact velocities from 8.5 m/s
to 418 m/s. The damage model realistically captured several salient features of the experimental wave
profiles in terms of the shock rise time and the shape of the non-linear portions beyond the Hugoniot
Elastic Limit (HEL) as shown in fig. 2.
Jean Ebothe University of Reims Champagne Ardenne, France
Geometrical impact on Magnetic Properties of Mesoscopic Scale thick Nickel thin films
A real material thin film never exhibits a perfect or ideal geometrical shape, regardless of its
formation conditions. This is mainly depicted by its unavoidable bulk usually represented by
its thickness (d≠0) and its surface irregularities commonly considered in term of surface
roughness (σ≠0), both film characteristics being closely interconnected. Their individual
morphology and microstructure engender different behavior under a particular physical field
(E) effect. Any related film’s property (p) always results from their combined contributions.
The study of p evolution is commonly investigated through its dependence on d as mainly
encountered for macroscopic scale thick samples. However, configuration of real nano-films
and nanostructured thin films is specific most of the time. Consequently, the study of their p
evolution requires an adapted approach reflecting that specificity.
In the present work, our original proposal is illustrated by the study of nanostructured nickel
electrodeposits for which evolution of coercivity (Hc) and magnetic domain size (w) are
precisely investigated. It is then clearly demonstrated that only a new film geometrical
characteristic (τ) defined as τ = (d/σ) can consistently lead to the announced objective.
The study of these properties evolution using the normalization model indicates a
discontinuity in the magnetism of the investigated samples. Bloch magnetic domains (MD)B
are associated with mixed domain walls (DWN + DWB) below a critical position (τ0
-1) ≈ 0.35,
while Néel domain walls (DWN) coexist with mixed magnetic domains (MDB + MDN) beyond that position.
Brenda Mbouamba Yankam University of Nigeria, Nigeria
Robustness of orthogonal uniform composite designs against missing data
Missing data can hardly be prevented in most experiments due to setbacks that occur during
the data entry process, and may grossly affect the estimation of the regression coefficients. The effects of
missing data may be extremely significant if the design is almost saturated, saturated or fully saturated. It
is of practical significance to identify designs that are least affected by missing data. In this paper, new
orthogonal uniform minimax loss (OUCM) designs are constructed. These designs are more robust to one
missing design point than the original orthogonal uniform composite designs (OUCDs) of Zhang et al.
(2020). The proposed designs are compared with central composite design (CCDs), small composite
designs (SCDs), orthogonal array composite designs (OACDs), orthogonal array composite minimax loss
designs (OACMs), and orthogonal uniform composite designs (OUCDs) based on the D-efficiency and Aefficiency
for estimating the parameters of the second-order model. These designs perform better in term
of losses and also have higher D-efficiency and A-efficiency.
Emmanuel Péres de Araújo Military Institute of Engineering, Brazil
Laboratory scale production method of composite fuels for hybrid propulsion
Fuel formulation is one of the chief strategies in hybrid propulsion studies1. In this context,
polyethylenes-paraffins compositions have been suggested as a trade-off solution to attain
both mechanical quality and ballistic performance2,3. In parallel, mixed hybrids have proven
their capacity to enhance regression rates of thermoset polymers in mixture-modelled
experiments4. Ammonium perchlorate replacement by ammonium nitrate could turn mixed
hybrids into environmentally benign materials5. Meanwhile, the preparation of fuels based on
paraffins6,7 and thermoplastic polymers8 could benefit from an application-oriented approach,
capable to generate macroscopically homogeneous and symmetrical samples, compatible
with both instrumental and ballistic measurements. Therefore, a laboratory scale batch
method for the preparation of composite fuels for hybrid propulsion comprising low density
polyethylene (LDPE), paraffin and ammonium nitrate was successfully developed, yielding a
protocol consisting of two major steps, i.e., vigorous mixing at high temperature and natural
cooling centrifugal casting. This method allowed the repetitive production of single circular
port cylindrical grains (Figure), with a volumetric contraction in the 7% - 18% range, prone
to be used both in static firings and in instrumental analysis9. TGA and DSC results suggested
that the attained partial miscibility level between LDPE and paraffin, yielding a
crystallization enthalpy in the -320 J/g range, was enough to provide a good compositional
uniformity in the radial axis of the grains and a crystallization behavior compatible with the
inexistence of major cracks. Under the overall experimental conditions adopted, the
volumetric contraction of pure paraffin, i.e., 9.9%, was found to be lower than literature data,
as well as crystallization enthalpy results suggested a synergistic interaction between LDPE
and macrocrystalline paraffin, away from the additive rule9. The devised preparation method
and its macroscopic and microstructural findings are expected to be useful in hybrid
propulsion studies, regarding particularly the proper definition of novel LDPEmacrocrystalline
paraffin-NH4NO3 composite fuels’ formulations.
Vladimir Shapovalov bA. Galkin Donetsk Institute for Physics and Engineering, Ukraine
Analysis of the properties of coordination materials by the ESR method
Studies of organometallic substances with Fe3+ iron nanoprobes have been carried out. Maltofer  has been researched. X-ray structural analysis showed the presence of reflections of the crystalline phase (Fig. 1), the nanocomplexes of which contain the Fe3 + ions under study. Electron Spin Resonance Spectrum (ESR) was studied in the temperature range 4.2K – 300K on a spectrometer with a frequency of 10 GHz. The ESR spectrum consists of: lines 1 and 2 of the spectrum of Fe3+, lines 3–8 of the spectrum of Mn2+, and line 9 of the spectrum of the radical (Fig. 2). The Mn2+ and radical ions found in the compound are unexpected and unacceptable . The change in the intensities of lines 1 and 2 of the ESR spectrum of iron Fe3+ was analyzed in the temperature range 4.2К–300K. The mutual transformation of the intensities of these lines was studied, which was used to determine the dynamic characteristic of the nearest environment of the iron ion in the complex - the activation energy or the height of the crystal field barrier
Mario Nogueira Barbosa Junior Pontifical Catholic University of Rio de Janeiro, Brazil
Mechanical Properties analysis of a pigment free epoxy novolac reduced graphene oxide composite coating through TD-NMR technique
Industrially, carbon steel is the most used among metallic materials, and, consequently, the one that suffers the most from corrosion processes. About half of the metallic failures that have occurred have been attributed to the corrosion phenomenon, encouraging the search for new solutions to its reduction . The degradation of metallic materials by corrosion is a problem for the industry due to forced production stops, and as a consequence, loss or waste of valuable sources and resources, loss or contamination of products, less efficiency in industrial processes, and additional costs in process maintenance. The use of protective coatings on carbon steel is one of the main techniques for the prevention of corrosion. Epoxy resins are one of the most commercialized coatings in industry, given their thermal and chemical resistances, compatibility with a large number of materials, good adhesion and others. Graphene has been widely explored in scientific studies as a nanofiller in polymer-based composites, to increase the efficiency of coatings in anti-corrosive action. For a better understanding of the results obtained in the corrosion tests of the work of M.N.B. Junior and coworkers , mechanical tests were performed on the neat polymeric material and nanocomposites with graphene. TD-NMR experiments, through the OW4 pulse sequence, were performed on the samples both prior and after the mechanical deformations. The pulse sequence employed can discriminate molecular dynamics of intermediate mobility, thus revealing changes occurring inside the relevant scale of polymer chains conformation. The results showed clear changes in molecular dynamics, clearly correlated with the presence and concentration of the graphene filler. The graphene sheets increase the molecular mobility (mainly for the EP0.5GL sample) of the samples, suggesting that the bulk of the sheets can be located in the semirigid (of intermediate mobility) fraction of the polymer chains.
Madhuri Chandrashekhar Deshpande Vishwakarma Institute of Technology, India
Processing and Characterization of Carbon Fiber Reinforced Aluminium7075
Aluminium metal matrix composites are potential materials for aerospace applications due wear resistance, fatigue resistance, good strength to weight ratio and light weight. Apart from this another emerging application of this materials is in thermal management as heat sinks or electronic packaging materials. In this work composites were manufactured by vacuum hot pressing using uncoated and nickel coated milled pitch-based carbon fibers and graphite flakes as reinforcing materials and AA7075 as matrix. Composites were made with different volume contents of carbon fibers and graphite flakes. Effects of contents of reinforcing materials on mechanical, thermal, electrical properties of composites were studied. Effect of T7 treatment was studied. Corrosion behavior of these composites was also studied. Metallographic examination was carried out using optical microscope, scanning electron microscope, energy dispersive spectroscopy, transmission electron microscopy and X-ray diffraction.
Results indicated that as volume content of fibers increased mechanical properties dropped. Improvement in electrical conductivity was observed after T7 treatment. Highest 47.9% increase in thermal conductivity with respect to vacuum hot pressed pure AA7075 was observed in In-plane direction at 100°C for composite with 20 vol.% carbon fibers. Graphite flake composites show better thermal properties than carbon fiber composites. These composites containing 10, 20 and 30 vol.% graphite flakes show 38.46 %, 82.69% and 108.65% increase in thermal conductivity (In-plane direction) respectively. Co-efficient of thermal expansion decreased with increase in carbon fiber content in In- plane direction but showed increase in Out-of-plane direction. For composite with 30 vol.% graphite flakes as reinforcement showed very low co-efficient of thermal expansion, 3.8 X 10-6 /K in In-plane direction. Composites with flake as reinforcement exhibited better thermal properties than fiber reinforced composites. Corrosion rate increased as the amount of carbon fiber content increased.
Ludi Miao Cornell University, Ithaca, New York, USA
Two-dimensional magnetic monopole gas in an oxide heterostructure
Magnetic monopoles have been proposed as emergent quasiparticles in pyrochlore spin ice compounds. However, unlike semiconductors and two-dimensional electron gases where the charge degree of freedom can be actively controlled by chemical doping, interface modulation, and electrostatic gating, there is as of yet no analogue of these effects for emergent magnetic monopoles. To date, all experimental investigations have been limited to large ensembles comprised of equal numbers of monopoles and antimonopoles in bulk crystals. Here, inspired by the recent theoretical works on spin ice thin films [1,2], as well as the two dimensional electron gas (2DEG) at LaAlO3/SrTiO3 which emerge as a result of the polar discontinuity , we propose the formation of an analogous two-dimensional magnetic monopole gas (2DMG) with a net magnetic charge, confined at the interface between a spin ice and an isostructural antiferromagnetic pyrochlore iridate and whose monopole density can be controlled by an external field . Our proposal is based on Monte Carlo simulations of the thermodynamic and transport properties. This proposed 2DMG should enable experiments and devices which can be performed on magnetic monopoles, akin to two-dimensional electron gases in semiconductor or oxide heterostructures.
Fengyuan Che Linyi people's hospital, China
Preparation and application of a novel self-healing polyelectrolyte hydrogel dressing
The development of high-loading hydrogel dressings is of great significance for improving the therapeutic effect of wounds and protecting human life and health. However, conventional loading methods cannot effectively control the loading channels, resulting in limited loading capacity of polyelectrolyte hydrogel dressings. In this study, the structural transformation during the "damage/self-healing" process of the material was used to control the drug loading channel and enhancing the loading potential of the polyelectrolyte hydrogel dressing. Based on the layer-by-layer assembly technology, using the multiple reversible interactions between the assembly elements, the selected polyelectrolytes were precisely assembled on the template to construct a self-healing polyelectrolyte hydrogel dressing; The changes of morphology and structure during the "damage/healing" process of the polyelectrolyte hydrogel dressing were investigated to reveal the regulation rules of the structural transformation of the polyelectrolyte hydrogel dressing. Then the polyelectrolyte hydrogel dressing was damaged to the target scale to open the drug loading channel and load the drug. After loading the drug, the polyelectrolyte hydrogel dressing was stimulated to healing the damage, the drug leakage channel was closed, and the drug was encapsulated. This research has important theoretical significance and application value for the design, preparation and performance control of new drug delivery materials.
Felipe Matamala-Troncoso Pontificia Universidad Católica de Chile, Chile
Synthesis of the Cu2O/TiO2 heterojunction on FTO electrodes for photoelectrocatalytic nitrate reduction
Copper (I) oxide (Cu2O) is an attractive p-type semiconductor for its optoelectronic properties
that can form a heterojunction with titanium oxide (TiO2), an n-type semiconductor widely
used for its photocatalytic properties. In this work, we propose using a Cu2O/TiO2/FTO
electrode to perform the photoelectroreduction of nitrate. A low-cost synthesis of copper (I)
oxide (Cu2O) by electrochemical deposition (ECD) of Cu2O molecules on TiO2 nanoparticles
previously sintered on a fluorine-doped thin oxide coated glass electrode (FTO) is presented.
The photoelectrochemical properties of the Cu2O/TiO2/FTO electrode were studied by FESEM-
EDX microscopy, Raman and UV-vis diffuse reflectance spectroscopy, followed by
electrochemical analysis. The nitrate reduction is performed using the Cu2O/TiO2/FTO
electrode under 1 sun bias illumination and applying a more positive overpotential at -0.5 V
RHE. The conversion of nitrate to nitrite is evaluated using the Griess reagent, reaching 22%,
14%, and 11% when applying a potential of -0.05 V, 0.1 V, and 0.3V RHE, respectively. Our
study presents an alternative to the conventional electrochemical nitrate reduction with
promising results for future Cu2O/TiO2 heterojunction applications in environmental and energy issues.
Jesus Anselmo Tabares Universidad del Valle, Colombia
Optimized route for the fabrication of MnAlC permanent magnets by arc melting
The τ-MnAlC is a face-centered tetragonal structure of the near equiatomic MnAl alloy, stabilized with a very low concentration of C which is currently considered a very promising candidate for permanent magnet applications due to its high anisotropy field (~ 4 T), relatively high saturation magnetization (MS = 96 Am2/kg) and Curie temperature (TC = 380 °C) [1-3], besides being a low-cost and rare-earth-free alloy. This ferromagnetic τ-MnAlC phase is usually obtained from a quenched high-temperature hcp ε-phase (ε-MnAlC) which is then annealed at temperatures between 500 and 700 °C [1,2]. Throughout the fabrication process of the metastable τ-MnAlC phase, some equilibrium phases (β-Mn and γ2-Al8Mn5 phases ) can appear, deteriorating its magnetic properties. In this work, we present a simple fabrication route that allows obtaining magnetically enhanced bulk τ-MnAlC magnet. In the fabrication process, an electric arc-melting method is carried out to melt ingots of Mn54.3Al44C1.7 alloys. A two-step heat treatment at 1200 and 1100 °C allowed us getting a very high concentration ε-MnAlC alloy after performing the quenching process in room temperature water. By reducing the formation of secondary phases, we allowed obtaining a bulk τ-MnAlC alloy with improved magnetic properties. Room-temperature hysteresis loops showed that our bulk τ-MnAlC alloy exhibits values of saturation magnetization, remanence magnetization and coercive field higher than those reported in previous works [4,5]. Experimental evidences demostrate that the two-step heat treatment to homogenize the ε-MnAlC plays an important role in the suppression of undesirable phases that deteriorate the permanent magnet properties of the τ-MnAlC. In addition, TEM-based magnetic imaging techniques were performed to locally inspect the magnetic microstructure of the improved MnAlC permanent magnet.
Soon-Gil Yoon Chungnam National University, South Korea
Unprecedented Flexibility of In-Situ Layer-by-Layer Stacked Graphene with Ultralow Sheet Resistance
Although graphene has been extensively studied as a candidate transparent conducting electrode (TCE) material for next-generation flexible devices, transferred large-scale graphene inevitably suffers from wrinkles, ripples, and metallic residues, which significantly lowers its quality by increasing its resistance and reducing its flexibility under tensile strain. As a result, many studies have looked to decrease the sheet resistance and increase the flexibility of graphene, but the complicated fabrication processes and high costs involved are barriers to commercialization. In the present study, 4-inch scale monolayered graphene and layer-by-layer stacked graphene that do not require a transfer process were designed to exhibit high flexibility and ultra-low sheet resistance. Three-layered stacked graphene film grown in situ on a polyethylene terephthalate substrate had an ultra-low sheet resistance of ~ 16 sq-1 at an optical transmittance of ~93% and superior flexibility for 104 cycles under a tensile strain of 5%. However, the plastic deformation of the PET substrate considerably reduced the flexibility of the monolayered graphene. In contrast, monolayered graphene on polydimethylsiloxane, which did not undergo plastic deformation, exhibited unprecedented flexibility at a static tensile strain of 15% (radius of curvature: 0.6 mm) and for 3104 bending cycles under a tensile strain of 11% (radius of curvature: 0.9 mm). This study provides an effective approach for the fabrication of TCEs for use in foldable electronic devices.
Pengfei Ji Beijing Institute of Technology, China
Ab Initio Calculation of Electron Heat Capacity and Electron-Phonon Coupling Factor under Electron Excitation State
As an advanced and promising approach to fabricate nanoparticles from the femtosecond laser ablation of metals, the electron heat capacity and electron-phonon coupling factor are two critical important parameters in the femtosecond laser ablation process. Therefore, the ab initio calculation of electron heat capacity and electron-phonon coupling factor under electron excitation state is performed. The impacts of electron density of states and Fermi-Dirac distribution function on these two parameters are to be shown in this talk, which provides quantitative information on describing the femtosecond laser-induced electron heating and the electron-phonon coupled energy transportation.
Shabnam Pourmoslemi Hamadan University of Medical Sciences, Iran
Enhanced antibacterial activity of Ag doped ZnS nanoparticles synthesized by a microwave assisted polyol method
The capacity to overcome the worldwide incidence of infectious diseases lies in the ability to prevent, detect and effectively treat these infections. Therefore, finding new antibacterial agents is of great importance especially when new classes of effective antimicrobials are rarely developed. Among the various classes of antibacterial agents, nano-sized inorganic materials have gained considerable attention in recent years. Their unique antimicrobial activity is raised from special characteristics such as small size and large surface area and they can be used in a wide range of applications such as wound dressing, tissue engineering, artificial organs, dentistry, photocatalytic antimicrobials and so on.
In this study silver doped zinc sulfide nanoparticles were synthesized by a microwave assisted polyol method. Characterization of nanoparticles was performed using XRD and FESEM-EDX to investigate chemical structure, crystalline phase, particle size and surface morphology. Antibacterial properties of synthesized nanoparticles were investigated by determining their MIC and MBC values and kinetic of bactericidal activity against Staphylococcus aureus and Escherichia coli.
Results of the study showed formation of single phase of hexagonal wurtzite ZnS structure with Ag+ substitution at 1.6% Zn/Ag molar ratio. MIC values were determined as 250 and 500 μg/ml against Staphylococcus aureus and Escherichia coli, respectively and time kill profiles showed efficient and rapid bactericidal activity of the synthesized Ag doped ZnS nanoparticles. Comparing the time kill profile of Ag doped ZnS nanoparticles with that of equivalent amounts of Ag or ZnS nanoparticles suggest a synergistic increase in antibacterial activity of ZnS nanoparticles after embedding small amount of Ag in their crystalline structure.
This study suggests a synthesis strategy for Ag doped ZnS nanoparticles with potent and broad-spectrum antibacterial activity. Doping Ag in ZnS nanostructures provided a cost-effective way to improve ZnS properties for prospective applications.
Maria Fortuño Morte Jaume I University, Spain
Novel reddish ‘cool pigments’ based on AFeO3 (A = Ln, Y)
Cool pigments have emerged as a powerful strategy to reduce the global impact caused by climate change and the associated higher ambient temperatures that urban areas and people are increasingly suffering. These materials have high solar reflectance and infrared emission so they can be used as roof coatings to control the temperature within the buildings. For that purpose, this study focuses on environment-friendly pigments based on AFeO3 (A = La, Pr, Nd, Sm, Gd, Tb, Y or Yb) with high near-infrared (NIR) reflectance which were synthesized by a coprecipitation method at 1200ºC. The orthorhombic perovskite with the Pbnm space group was observed in all samples without any secondary phase. Absorption and reflectance measurements in the UV-Vis range confirmed that these pigments present a reddish colour. Furthermore, good stability of pigments in a siloxane paint and two ceramic enamel was obtained. On comparing coatings of all the coloured paint, it is found that mixes containing GdFeO3, TbFeO3 and YFeO3 powders possess the highest NIR solar reflectance, reaching values of R = 43%, 48% and 47%, respectively. Therefore, they could be considered good cool pigments. The variation in the interior temperature of a foam building (5.5 x 5.5 x 7.5 cm, thickness of 0.7 cm) after application of two coats of paint, with commercial reddish pigment and TbFeO3 powder, reaches 3.2ºC, the lowest temperature being achieved by the building with the coating of TbFeO3 powder paint mixture. Moreover, the CIEL*a*b* and CIEL*C*H* parameters indicate that the mixtures of ceramic enamel with the three pigments mentioned above also present the reddest tone. Thus, the synthesized compounds are good candidates for use as reddish pigment in enamels for ceramic tiles and also as cool roofing materials.
Kazuo Yamada National Institute for Environmental Studies, Japan
The outline and the background of “Recommendation of RILEM TC 258-AAA: RILEM AAR-13: application of alkali-wrapping for concrete prism testing to assess the expansion potential of alkali-silica reaction”
Various test methods and models have been developed to evaluate the alkali reactivity of aggregates and to estimate the long-term expansion behavior of concrete, and the test results have been compared with the behavior in the field. Since the expansion of ASR is caused by the formation of expansive reaction products of reactive silica in the aggregate and alkali in the pore fluid, the most essential points required for the test method are the alkali content and moisture content. Of course, apart from the properties of the aggregate itself, there are many other factors related to ASR expansion, such as water-to-cement ratio, mixing ratio of reactive and non-reactive aggregates, SCMs, aggregate size, temperature, age of the evaluation, humidity, etc., which result in different micro-textures of cracks, different reaction products, and different pore fluid compositions, and then resulting in different expansion dynamics and deformation characteristics of the structure. In order to investigate these factors and develop models to estimate the performance of structures, the most basic and important point is to first perform tests under controlled conditions of alkali content and moisture supply.
As an example of the influence of alkali leaching, which is considered to be one of the important influencing factors, the influence of specimen size will be explained: cylinders of Φ10 cm and blocks of 40 × 60 × 60 cm were made of the same concrete mixture and placed in different climatic locations in Japan. It was observed that the smaller cylinders showed less expansion. Analysis showed alkali leaching over several centimeters from the surface, which may have been the cause of the reduced expansion. When the same mixtures were tested in the laboratory with RILEM AAR-3 or 4, significant alkali leaching from the specimens and mass loss due to limited moisture supply were also detected.
A vast amount of data has been accumulated in ASR studies so far, but unfortunately, due to this circumstance explained above, it is questionable how reliable the data can be in terms of lab-field correlation. If the test method has a strictly defined procedure and reproducibility has been confirmed, any test method can be used, as long as the purpose of the test is limited to the determination of the harmlessness of aggregate or specific concrete in a certain area, since the criteria for determination are based on engineering experience. However, when trying to scientifically examine the influence of various factors, an appropriate test method is necessary. In order to realize the requirements of keeping the alkali content constant and supplying sufficient water, the authors proposed alkali-wrapping for concrete prism testing, currently published as RILEM AAR-13: application of alkali-wrapping for concrete prism testing to assess the expansion potential of alkali-silica reaction.
Bulk and surface electronic properties of stable β phase of tungsten
The β phase of tungsten (W) is one of the potential candidates in Spintronic, due to the finding of a giant Spin-Hall Effect and large Spin-Orbit Torque [1-3]. This would be also effective for use in magnetic random access memory and spin logic devices . But it is a metastable phase of W, which gets stabilized in the presence of oxygen [1, 4-6]. There are several studies have been done on the β phase of W, but the role of oxygen in stabilization is not clear. The corresponding electronic structure is also not enlightened, which is one of the important properties to consider the material for an application, especially in spin-based devices. Though ideally, it has some massive Dirac Fermions near the Fermi level (EF) with the considering of spin-orbit coupling in the calculation , however, the presence of oxygen has some impact on the bands in real practice. The phase formation and oxygen concentration were recognized by using grazing incidence X-ray diffraction (GIXRD) and Electron Dispersive X-ray spectroscopy (EDX), respectively, of electron beam grown W films. The results from our ab initio calculation supported the experimental findings. Moreover, we have calculated the density of states (DOS) and band structures with considering oxygen in it. There is a gain in energy of approximately 5.03 eV by doping of one oxygen in a unit cell of β-W. We found a certain amount of oxygen (~16 at %) can stabilize the β phase. The topologically protected nontrivial surface states connecting these massive Dirac fermions are modified with the presence of oxygen. Further, there is structural disorder, O-inhomogeneity, and higher density-of-states in O-doped β-W at EF compared with pure α-W are found.
Arnaud Caron Korea University of Technology and Education, South Korea
How do surface oxides affect the friction and wear of metallic glasses?
Due to their high resilience, high fracture strength, and ability to be near net-shaped in their undercooled liquid region, metallic glasses are good candidates for application in micro-electromechanical systems, and in systems involving parts in reciprocal motion . While the friction and wear of different metallic glass systems has been studied, published results are not univocal and hint at the complexity of the mechanisms involved.
More recently, the individual mechanisms involved in friction and wear of metallic glass surfaces have been investigated in single nanoscopic asperity contact in various environment from ultra-high vacuum to chemically aggressive environment. While results in ultra-high vacuum are scarce, studies in ambient and under chemically aggressive conditions show how important surface oxides are for the friction and wear of metallic glasses.
In this work, we demonstrate how surface oxides grown either in acidic solutions or by thermal oxidation in air contribute to the suppression of abrasive wear and the extension of the adhesive friction regime of metallic glasses.
Md Salah Uddin University of Texas Permian Basin, United States
Molecular dynamics simulations and experimental characterization of chitosan hydrogel with different crosslinking agents for targeted drug delivery
Chitosan is a water-soluble, non-toxic, biodegradable, cationic, linear polysaccharide that is widely used in targeted drug delivery. In this study, two major cross-linkers Genipin and Disulfide have been selected to crosslink linear chains and investigate their effect on drug distribution with molecular dynamics simulations and loading/releasing rate with experimental characterization. Genipin is a small molecule, acts as a nontoxic linker, and can undergo self-polymerization whereas Disulfide crosslinking is a polymer-polymer crosslinking where the reaction takes place under neutral conditions and provide mucoadhesion. The cross-linking process is heavily impacted by the temperature and the pH conditions. To investigate the drug loading and releasing rate, Thymoquinone, Gefitinib, and Erlotinib have been selected for the linear chitosan along with two other cross-linked systems conducted in Phosphate buffer solution. This experiment guides to observing the drug loading and releasing efficiency of the linear chitosan and the cross-linked chitosans depending upon the amount of cross-linking used. The swelling ratio for the polymeric system is also observed and it is found to be improved with genipin and disulfide crosslinking. A previous study has been conducted to investigate the drug distributions with molecular dynamics simulations. Chitosan hydrogel network is constructed using three different crosslinking agents, soaked with water, and thermal cycles are applied to estimate the critical temperatures. Subsequently, three different drug molecules are incorporated into the models separately and the distributions are observed by analyzing the trajectories of the drug molecules obtained from the simulations performed with canonical ensembles, as the distributions will affect the drug discharge.
Allisson Saiter-Fourcin CNRS University of Rouen UMR 6634 GPM laboratory, France
What about new knowledges on the physical aging process?
Knowing the physical aging process is essential for predicting the time-dependent behavior of glass-forming liquids. The way by which a glass reaches (or not) its equilibrium state after a certain time is still matter of debate in the scientific community 1. Recently, it has been proven that this way is clearly dependent of the gap between the glass transition temperature Tg and the aging temperature Ta in different glass-forming liquids: polymeric systems 2, metallic glasses 3, and chalcogenide glasses 4. When Ta is close to Tg, the kinetics of the enthalpy of recovery occur in one step, whereas for Ta far from Tg, multiple steps can appear.
Recently, the use of the fast scanning calorimetry (FSC) has generated many studies 5-7 proving that the physical aging can accelerate the ability to crystallize by forming nuclei after reaching of the equilibrium state. This phenomenon known from a theoretical point of view is difficult to evidence experimentally because it appears after the complete structural relaxation, but we highlighted it through the study of a Selenium glass.
Swapan K Saha Indian Institute of Astrophysics, India
Image Processing of Stellar Objects by Interferometry
Single aperture speckle interferometry deciphers diffraction limited spatial Fourier spectrum and image features
of stellar objects by counteracting blurring effect caused by the atmospheric turbulence. It has made impacts in
several important fields in astrophysics. In the last few decades, adaptive optics (AO) systems at various large
telescopes have yielded spectacular results. One remarkable result came from measurements of the motion of
stars in a region called Sagittarius~A$^\star$ (Sgr~A$^\star$; considered to be a supermassive black hole) of the
Milky Way, for which two astronomers jointly received a share of the Nobel Prize in Physics~2020. However,
the limited aperture of any given telescope limits its resolving capacity. Success in synthesizing images obtained
at two independent telescopes on a North-South configuration in the mid-1970s impelled astronomers to venture
into developing ground based very large arrays. Such arrays are expected to provide images, spectra of quasar
host galaxies, and exo-planets. Another fundamental problem that can be addressed using interferometry and AO
is in the study of origin and evolution of galaxies. Several interferometers are producing results from the area of
stellar angular diameters with implications for emergent fluxes and effective temperatures. A novel technique,
called `hypertelescope imaging, which can be viewed as a modification of the classical Fizeau interferometer by
employing pupil densification, has a vast potential. A major challenge for building such a system is the
development of adaptive phasing systems. Modified wave sensing techniques such as dispersed speckle analysis
are proposed to be used with these systems. But development and installation of such advanced methods are not
available at present. In such a scenario, speckle mode observations with hypertelescope becomes a viable
alternative. After a brief presentation on the single aperture speckle interferometry, the current trend and the path
to future progress in optical interferometry will be discussed.
Sadykov Dinislam ITMO University, Russia
The effect of increasing plasticity in high-strength ultrafine-grained Al-Cu-Zr alloy
Ultrafine-grained (UFG) structures achieved by severe straining are capable to significantly improve the strength of Al alloys, which is very important for their potential for advanced applications. However, such strengthening of Al alloys is often accompanied by significantly reduced plasticity. In this report we demonstrate for the first time the effect of a substantial increase in plasticity in the ultrafine -grained (UFG) triple alloy Al-1.47Cu-0.34Zr (wt.%) structured by high-pressure torsion (HPT), while keeping high strength (more than two times exceeding the strength of the coarse grain state).
The HPT-processed alloy had a small grain size of ~ 285 nm and exhibited high strength (the ultimate tensile strength σUTS ~ 575 MPa), but low plasticity (δ ≤5%). Based on the approach suggested in [1,2] for UFG Al, a short-term annealing at low temperature with subsequent additional small deformation of the UFG alloy was performed. As a result, the plasticity increased to 11%, while maintaining a high level of strength (σUTS ~466 MPa) and practically unchanged grain size (~315 nm). The microstructure data suggest that the reason for this increase in plasticity is the introduction of an additional dislocation density into the relaxed (as a result of short-term annealing) structure of high-angle grain boundaries, as well as the effect of segregation parameters on the emission of dislocations from grain-boundaries.
Pablo Fuentealba Castro University of Chile, Chile
White Light Emission: from Coordination Compounds to Luminescent Flexible Materials
Lanthanide coordination chemistry has been a main focus of research due to its proven applications and intriguing properties. Optical properties have been used for LASER, LED, modern electronic devices, such as smart phones or screens, bioimaging or thermometry, among others. The generation of white light is of interest in order to decrease the energy consumption by using new materials with efficient properties. In most of the applications the lanthanide species are immersed in different matrices that can optimize their use and often increase the optical properties, due to the decrease in intermolecular interactions that induce quenching effects. During the last years our group has been focused in the synthesis and characterization of new ligands, and the corresponding coordination compounds with lanthanide(III) cations along with the relation of their optical properties. Novel ligands, such has tripodal species with phenoxo and pyridine donor atoms, Schiff base hexaaza macrocycles and ligands derived from triazoles, will be analyzed together with the corresponding yttrium, dysprosium, europium and terbium complexes. The optical properties of the complexes will be analyzed in relation with the excited states of the ligand and the energy levels of the lanthanide(III) species. With the aim to generate white light the obtained complexes have been dispersed in thermoplastic polyurethane (TPU). The TPU flexible films were obtained by a slow evaporation method, with concentrations of the lanthanide species ranging from 1 to 10%, obtaining homogeneous films with luminescent properties. The interaction of the lanthanide species with the matrix will be also analyzed, as the presence of voluminous chelating ligands has been shown to induce a detrimental effect on the interactions with the TPU matrix. Thus, both luminescent and physical properties of the materials will be presents and analyzed.
Long Hao Institute of Metal Research Chinese Academy of Sciences, China
Effect of surface oxide films on the corrosion evolution of Pb-free Sn solder alloys
The presence of an oxides film on Pb-free Sn solder joint surface is inevitable and its structure could be influenced by subsequent high-temperature aging due to heat release of electronic device itself during application. In this work, the oxides films formed under high-temperature chemical oxidation mechanism and under electrochemical oxidation mechanism in humid atmosphere have been characterized. Results indicate that the oxides film formed in high-temperature environment is mainly composed of SnO2 and SnO, but the film formed humid atmosphere is mainly composed of Sn(OH)4 and SnO. The film initially grows with time as a parameter and then shows a stabilizing tendency under both conditions. Although the initial aging time contributes to an enhanced corrosion resistance of the film, an extending aging time always leads to a deterioration in the film corrosion resistance. Moreover, the corrosion effect by Ag addition to Sn solder has been explored with consideration of the formed surface oxides film. Results indicate that the oxides film on Sn-Ag solder maintains a much shorter duration to NaCl electrolyte attack than that on pure Sn solder. The film thickness variation among phases of Ag3Sn and β-Sn and the defects especially at boundaries facilitate Cl- preferential adsorption. After the oxides film deterioration, galvanic effect between Ag3Sn and β-Sn comes into play for further corrosion. This observed evolution behavior provides a practical perspective to corrosion of Ag-alloyed Sn solder with an oxides film covering.
Rensheng Chu Research Institute of Technology, Shougang Group Co., Ltd., China
Effect of soft reduction process on segregation of thick high-alloy steel slab
During the solidification of high-alloy steel(0.4C-1.5Mn-2Cr-0.35Mo-1.5Ni), the high temperature gradient of solidified shell as well as the columnar crystal developmentwould contribute to the centre segregation and cracking due to the high carbon and alloy contents. The effect of soft reduction process on the segregation of a 400 mm thick high-alloy steel slab was analysed. Industrialtrials in a steel mill were performed combining with segregation analysis. The innerquality of the high-alloy steel slab,produced throughthe optimised soft reduction procedures,had a significant improvement in centre segregation.The reduction amount is increased from 20% of solid phase fraction, to avoid the segregation due to the long liquid core, andthe reduction rate is deceased from 1.35 to 0.88 mm/m as well. This operation would contribute to the symmetrical distribution of solute element and decrease the segregation to avoid the cracking. An obvious improvement in centre segregation to mainly 1.0 class of high-alloy slab after procedure optimization was achieved. The quality improvement of slab would ensure the quality of downstream forging.
Breno Rabelo Coutinho Saraiva Federal University of Ceará, Brazil
Microstructural changes in additively manufactured Co-Cr-Mo alloy under cyclic loading
Cobalt-Chromium-Molybdenum (CoCrMo) alloys are used in applications that require high strength and wear resistance. Examples in biomedical are include artificial hip and knee joints implants which are subjected to repetitive loads during the service. The cyclic loading implies high fatigue strength as a fundamental mechanical property, besides those already pointed out. In this regard, it is crucial to understand the mechanism associated with the crack propagation under cyclic loading, which is subject of the present work.
Tensile test specimens were fabricated using laser powder bed fusion (LPBF) additive manufacturing technique and examined in the as-build condition. Then, the samples were subjected to cycling loading with tension load applied above the yield strength and subsequent tension release. Microstructural changes occurred were followed using EBSD technique. Hence, it was possible to trace deformation-induced phase transformation from face-centered cubic (γ) to hexagonal close-packed (ε) structure. Our investigation revealed that cracks nucleated at grain boundaries. In addition, it was observed that the crack tip was deflected when encountered a grain boundary unfavorably oriented to the crack propagation. Then the crack tip propagated further at the ε phase. Therefore, γ→ε deformation-induced martensitic phase transformation serves as a preferential path to crack propagation when the crack tip encounters a barrier such as grain boundary.
Ana Kramar University Carlos III of Madrid, Spain
Double-layer hydrophobic/hydrophilic film of cellulose acetate prepared using solution blow spinning
Cellulose-based biodegradable and biocompatible materials, have recently gained increasing interest as an alternative to non-biodegradable plastics in food packaging industry1,2. Cellulose acetate, a derivative of cellulose, is less hydrophilic than pure cellulose, but still considered wettable, being reported water contact angles on its films3 usually around 60°-70°. Frequently used procedure for film preparation of these materials is solvent casting method, whereby resulting films have good transparency, slightly reduced wettability and good mechanical properties3,4. However, this method does not seem to be optimal when preparing nanocomposites with uniform dispersion of fillers and when fibrous morphologies are required, for instance. Here we report the preparation of cellulose acetate film using solution blow spinning technique. Prior spinning, cellulose acetate was dissolved in a solvent mixture containing acetone/dimethylformamide, whereby different solvent ratios were used. Increasing the content of acetone in a mixture, from 70% to 90%, influenced the resulting morphology of the material, whereby using 90 % acetone produced fibrous membrane, but with not enough integrity to be used as film. Therefore, usable film was prepared by subsequent deposition of two layers of CA from different mixtures. Resulting properties of the double-layered film (thickness, morphology, wettability) were evaluated and compared with those of each layer produced individually. It was found that resulting double-layered film exhibits hydrophobic behavior on one side (contact angle > 90°) and hydrophilic on other side (CA~ 65°).
Pedro Paulo Medeiros Ribeiro UFRJ Federal University of Rio de Janeiro, Brazil
Nickel and cobalt extraction from laterite ores
Nickel is mostly extracted from sulfide ores, however, laterite ores account for over 2/3 of all nickel resources in the world, and despite its predominance, there is no well-established process to extract nickel from such ores. Cobalt is also present in laterite ores. Nickel and cobalt in laterites are hosted in many different compounds such as oxides, hydroxides, and silicates minerals. The sulfation-roasting-leaching process has the potential to change this scenario once it can be applied to all kinds of nickel laterite ores. In this study, it will be presented the results of the experiments conducted using the sulfation-roasting-leaching process for four different laterites ore samples. X-ray diffraction, scanning electron microscopy coupled to energy dispersive spectroscopy, and chemical analyses by atomic absorption spectrometry were the techniques employed to characterize ore samples and leaching solid residues. Phase quantification was carried out by the Rietveld method. Under favorable conditions, nickel and cobalt recoveries were higher than 80 (wt.%) while the iron recovery was only 5.5 (wt.%).
David Curiel University of Murcia, Spain
Hydrogen-bonding strategy for the design of organic semiconductors.
Organic semiconductors have become a promising alternative for the development of future generations of electronic devices.1 Nevertheless, the semiconducting materials based on conjugated organic molecules still present some drawbacks, mainly related to the lower stability and charge mobility, when compared to their inorganic counterparts. Given the conjugated structure of organic semiconductors, π-π interactions govern the solid state arrangement of these molecular solids. The weakness of these intermolecular interactions leads to solid thin films which are inherently disordered.2 Therefore, strategies that can improve the nanostructuration of organic semiconductors are desired.3 To this end, we have explored the possibility of integrating hydrogen bond donor and hydrogen bond acceptor sites into the conjugated system itself. By exploiting the higher energy and directionality of hydrogen bonding we aim at inducing certain control on the molecular arrangement of conjugated systems. Different molecular materials that incorporate the 7-azaindole building block have been synthesized.4 We have observed that the prevalence of hydrogen bond interactions controls the solid state packing of the different materials. Moreover, in some cases, the self-assembled semiconductors have shown a remarkable robustness when used in the fabrication of optoelectronic devices, such as OFETs and solar cells.5 In turn, these devices have displayed a noticeable enhancement in their stability. Therefore, supramolecular self-assembly could become a useful strategy for the development of novel organic semiconductors.
Jung Hyun Kim Yonsei University, South Korea
Design of intrinsically stretchable and highly conductive polymers for fully stretchable electrochromic devices
Stretchable materials are essential for next generation wearable and stretchable electronic devices. Intrinsically stretchable and highly conductive polymers (termed ISHCP ) are designed with semi interpenetrating polymer networks (semi-IPN) that enable polymers to be simultaneously applied to transparent electrodes and electrochromic materials. Through a facile method of acid-catalyzed polymer condensation reaction, optimized ISHCP films show the highest electrical conductivity, 1406 S/cm, at a 20% stretched state. Without the blending of any other elastomeric matrix, ISHCP maintains its initial electrical properties under a cyclic stretch-release of over 50% strain. A fully stretchable electrochromic device based on ISHCP is fabricated and shows a performance of 47.7% ΔT and high coloration efficiency of 434.1 cm2/C at 590 nm. The device remains at 45.2% ΔT after 50% strain stretching. A simple patterned electrolyte layer on a stretchable electrochromic device is also realized. The fabricated device, consisting of all-plastic, can be applied by a solution process for large scale production. The ISHCP reveals its potential application in stretchable electrochromic devices and satisfies the requirements for next-generation stretchable electronics.
K.Prasanna Lakshmi Jawaharlal Nehru Technological University Hyderabad, India
Evaluation of Mechanical and Wear Properties of Aluminium 7075 Hybrid Nanocomposites with the additions of SiC/Graphite
The impact of graphite on Al 7075-SiC-Graphite hybrid composite's wear performance were investigated. The analysis demonstrates the effectiveness of graphite’s presence in the matrix to minimize wear . The hybrid metal matrix Nano composites were manufactured via Powder metallurgy process by reinforcing graphite at different weight fractions (0 percent, 5 percent and 10 percent) with 7075 aluminium alloy, the addition of Silicon Carbide (SiC) is fixed at 5 percent [1-2]. In the experimental investigation, it was observed that reinforcing particles are uniformly dispersed throughout the matrix alloy as perfect grain boundaries in aluminium solid solutions. The density and toughness of the reinforced composites have been improved with the incorporation of the reinforcement when compared to a monolithic alloy. The significant increasing trend in mechanical properties and wear performance of aluminium hybrid composites was accomplished by the addition of solid lubricant (Gr) and strong ceramic reinforcing particles (SiC) in the matrix alloy.
Development of hybrid nano composites of homogeneous distribution of reinforcing particulates through the method of powder metallurgy were validated with Scanning electron microscope (SEM) and optical microscope morphological images and wear findings . As the percentage of graphite in hybrid composites increases, the density and hardness values decrease. The wear losses of the composites improve as addition of graphite improves until 5 percent Gr, then decreases to a lesser value of 10 percent Gr. Hybrid nano composite material's wear resistance were better than that of the base metal. Worn surfaces analysis indicated that wear was delaminated including some oxidation wear mechanism by an influential wear mechanism for unreinforced Al 7075 base metal . Wore debris will decrease as addition of graphite tends to increase. The lubrication layer appears to be a major factor in regulating such hybrid nano composite’s wear behaviour analysis.
It introduces a new direction for the design of super lightweight materials incorporated in different industrial and engineering fields.
Vincenzo De Leo University of Bari Aldo Moro, Italy
LIPOSOME@PDA MICROSPHERES FOR FAST AND HIGHLY EFFICIENT WATER REMEDIATION
Mussel-inspired chemistry was usefully exploited to develop an environmentally friendly and high-efficiency material for water remediation. A micro-structured material based on polydopamine (PDA) was obtained by using liposomes as templating agents. Prepared Liposome@PDA microspheres were used for the first time as an adsorbent material for the removal of methylene blue (MB), a cationic dye widely used in textile and paper industries, from aqueous solutions. Liposomes were prepared through the extrusion method using membranes with a porosity of 200 nm. Then, vesicles were coated with PDA by inducing the self-polymerization of the dopamine into the liposome suspension. Liposome@PDA microspheres were fully characterized by DLS, Zeta potential analysis, TEM microscopy, and FTIR spectroscopy. Then, the capability of our systems to remove MB from the water was evaluated in terms of adsorption capacity (qt) by changing the process parameters. It is known that the adsorption process involves mainly electrostatic and π-π stacking interactions, so it was first investigated the effect of the pH on the process. Then effects, temperature, MB concentration, amount of Liposome@PDA, and contact time on the adsorption process were also investigated. Results showed that the highest qt was obtained in weakly alkaline conditions (pH = 8.0), where the electrostatic interactions between the compounds are maximized, and that it could reach up to 395.4 mg g-1 at 298 K. Removal efficiency was high, up to 96% and with a very high adsorption rate. Results show that the data well fit a pseudo-second order kinetic model and the Langmuir isotherm model. Moreover, the process seems to be spontaneous and endothermic in the realized experimental conditions (ΔG0 = -12.55 kJ mol-1, ΔH0 = 13.37 kJ mol-1) in the investigated experimental conditions. The applicability of Liposome@PDA microspheres to tap water, NaCl 0.1 M and model wastewater was demonstrated. Finally, the regeneration of the Liposome@PDA microspheres after the adsorption process was carried out using methanol. Results showed excellent reusability performances after three cycles.
María Francisca Gómez-Rico Núñez De Arenas University of Alicante, Spain
Valorization alternatives for plastic waste
Products traditionally made of glass or metal as packages or car parts have increasingly been produced of plastic. That means a lower weight and a lower fuel consumption in their transport or their functioning, respectively. Thus, disposed polymers in municipal solid waste have increased in recent years, but the problem is that they are hardly degradable. One fraction of these plastic wastes is recovered by recycling, as plastic or into other chemicals, or by energetic valorization. However, there is still an important amount that is landfilled.
In this work, a simple recycling process for this waste compatible with energetic valorization and obtaining high-added value products (carbon nanofilaments) is proposed. Carbon nanofilaments are crystalline materials with graphitic structure whose use and value are increasing in several sectors due to its extraordinary mechanical and electrical properties. Carbon nanofilaments were produced by catalytic chemical vapor deposition without the need of prior catalyst reduction from the effluent gases from pyrolysis of a mixture of polymers. The mixture was composed by polyethylene, polypropylene, polyethylene terephthalate and polyamide 6.6, in order to consider a representative plastic waste composition. The influence of pyrolysis and filament growth temperatures was studied. This economical and environmentally friendly method could be extrapolated to large-scale continuous production.
Special attention must be paid to plastics coming from electrical and electronic equipment waste, such as polyvinyl chloride (PVC) from electrical wires, due to their halogen content that can cause pollution problems during its energetic valorization. Hazardous polychlorinated dioxins and furans (PCDD/Fs) can be formed during combustion. The PCDD/F inhibition by prior addition of N-containing compounds was examined. For this purpose, good results were obtained when using other types of problematic waste such as polyurethane foam mattresses and sewage sludge, through the gases obtained from its oxidative pyrolysis and its direct mixing, respectively.
Safa Jemai Valencia Polytechnic University, Spain
Crystal growth and design of various shapes of PbS micro and nanocrystals from a hydrothermal process
This paper reports on a systematic study highlighting dramatic morphological changes during the preparation of Lead Sulfide (PbS) by a hydrothermal process. PbS micro/nanostructures having different shapes and sizes were prepared via a simple hydrothermal reaction between lead acetate and a sulfur precursor (Thiourea (Tu) or Na2S). We show that the shapes of the PbS micro/nanostructures can be tuned by varying the process parameters, for instance the concentration of the precursors (lead acetate and Thiourea), the reaction time and the reaction temperature. The hydrothermal – based PbS structures were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High-Resolution TEM (HRTEM) and X-Ray Diffraction (XRD). We succeeded synthesizing PbS crystallites having symmetric six- and eight-arms starfish-shaped dendrites by using Thiourea (Tu) as anionic precursor. The decrease of Tu concentration as low as 0.05 M switches the crystal morphology to irregular flower- and cubic – like shapes, while the increase of the reaction time up to 6 hours leads to the formation of mono-arms dendrites. The addition of Triethylamine (TEA) to Tu in the initial reaction blocks the growth of the six-arm starfish shaped PbS crystals and leads to the formation of octahedral and sub-spherical crystals. A morphological change from starfish dendrites to crystalline nanoparticles occurs by replacing Tu by Na2S as a sulfur precursor; this transition from dendrites to nanoparticles was attributed to the nature of the anionic precursor.
Imen Harabi Polytechnic University of Valencia, Spain
InP Injection Synthesis of Indium Phosphide Quantum Dots, Optical and Morphological Properties
A promising alternative to traditional QD materials which contain toxic heavy elements such as lead and cadmium, sheds light on indium phosphide quantum dots (InP QDs) Owing to improve the quantum yields of photoluminescence and other properties. Indium Phosphide (InP) and Indium Phosphide doped with Vanadium (InP:V) Quantum Dots (QDs) with Vanadium concentrations varying from 5% to 10% were synthetized by the hot injection method. The optical and structural properties of InP and InP:V QDs have being considered by several techniques such as X-ray diffraction, transmission electron microscopy, optical spectroscopy, and photoluminescence intensity. The average diameter of InP QDs and InP:V QDs was varying between 4 nm and 10 nm. This experience revealed that the surface morphology of the Quantum Dots has a more regular spherical form. Without doping, the emission peak of colloidal InP Quantum Dots was around 630 nm, while in InP:V 5% the emission peak is displayed and located at 495nm. whilst for InP: V10% is placed at 498nm. Add the XRD information FWHM of the principal peak of InP QDs was 63 nm, while for
InP:V was 82nm. Furthermore it is clear that 1.88 eV precise the band gap of pure InP QDs whereas the band gap value of InP:V varies between 2.73 eV and 3.05 eV corresponding to InP:V 5% and InP:V 10% respectively. These results revealed that Vanadium doping has an interesting effect on the bandgap value of InP and in the dopant concentration of 10% which has improved properties.
Meryem Uzun-Per Akdeniz Pe-Tur A.S., Turkey
Automated Image Analysis Methodologies to Compute Bioink Printability
The lack of suitable bioinks in bioprinting is a major limitation in tissue engineering and regenerative medicine. The reasons are multifaceted but can primarily be attributed to the contradictory requirements for bioinks to demonstrate desirable bioactivity while exhibiting high printability. Herein, methods are proposed and tools are provided to automatically quantitate the performance of bioinks using image analysis methods and differential geometry. Several artifact structures are used including a crosshatch to evaluate filament fusion, five‐layer tube to evaluate stacked arc accuracy, overhang to test filament collapse, and a novel four‐angled pattern to evaluate turn accuracy. Automatic measurements are 95.8% accurate in delineating pores of a crosshatch pattern, 96.5%, 86.0%, 80.3%, and 80.5% accuracy for each angle of a four‐angled pattern, 98.9% and 97.9% accuracy for the external and internal radii of a five‐layer tube, and 90.6% and 99.0% accuracy for the height and width of a five‐layer tube. This automation reduces the time and effort required to analyze a structure and also provides a standardized set of tools to compare different bioinks.
Deb Jaisi Interdisciplinary Science and Engineering Laboratory, University of Delaware, United States
A novel approach for enhancing solubility through structural substitution of ions of a slow-release fertilizer
Modern agriculture has arrived at the crossroad of conflicting problems of keeping up the supplant food production and yet protecting water quality. Slow and controlled release fertilizers are developed towards minimizing the usage of natural resources and maximizing plant uptake. Research efforts on developing next generations of nanofertilizers are aimed to control the rate of release of nutrients and track transfer and transformation in soils and waters. Specifically, two approaches of tuning nanofertilizer are being investigated: altering crystal chemistry via substitution of cations and anions in structural sites in apatite and amorphous calcium phosphate and changing their surface properties including size, shape, and surface morphology. The structural incorporations of soluble ions and carbonate are found to enhance phosphorus release kinetics. Crystal defects created from altering the structural reorganization of a unit cell are likely dominating factors. The changes made in surface properties have counteracting effects. Inability to limit the number of variables among products complicates discrimination of the role of each parameter. Nonetheless, the current success made in optimizing the properties has aided in tuning the temporal need of phosphorus for plants.