Assist Prof - Unesp - College of Science and Technology, Brazil
Beijing Institute of Technology, China
Shanghai Institute of Technology, China
Felipe Wasem Klein
Charles Coulomb Laboratory (L2C), CNRS, University of Montpellier, France
KELENN Technology, France
Jagadish Chandra Mahato
University of Porto, Assistant Professor of Physics Dep.
Prof. Anatoliy Zavdoveev
National Academy of Sciences of Ukraine, Ukraine
Friedrich Schiller University in Jena, Germany
Edla Maria Bezerra Lima
Brazilian Agricultural Research Corporation, Embrapa Food Technolology Unit , Brazil
Henrique José da Silva
UNIFRAN - University of Franca, Brazil
University of Arkansas for Medical Sciences (UAMS), Little Rock, Arkansas, USA, India
Marcelo Machado Viana
Federal University of Minas Gerais, Brazil
National Cheng-Kung University, Taiwan
University of Nebraska-Lincoln, United States
Center for Physical Sciences and Technology , Lithuania
Zhou Bing Chen
The Hong Kong Polytechnic University, China
Israel Institute of Technology, Israel
Amity University, India
Ana Paula Domínguez Rubio
University of Buenos Aires, Argentina
Athlone Institute of Technology, Ireland
Francesca Lionetto University of Salento, Italy
Production and characterization of polyethylene terephthalate nanoparticles
Plastic and mainly microplastic (MP) pollution in oceans represents one of the biggest
environmental problems further exacerbated by the continuous degradation in marine environment
of plastics to MPs and to nanoplastics (NPs). Growing concerns related to MPs adsorption of toxic
chemicals can lead to increased bioavailability and impact on organisms of MPs and NPs through
the release of these chemicals that, entering the food chain, shift the potential risk from environment
to human health. However, due to the complexity of the problem, full knowledge of the negative
effects of MPs/NPs on the environment and human health is still missing. It is very hard to carry out
reproducible studies due both to the extreme difficulty of collecting NPs from the sea in quantities
useful for research and to the great variability of NPs type, size and morphology. Most of the
available toxicity studies use commercial polystyrene nanospheres with results not easily correlated
with real conditions. It is thus imperative the availability of environmentally relevant nanoparticles
for toxicological studies on different organisms and ecosystems.
In this work, a reliable method has been set up to produce polyethylene terephthalate (PET)
nanoparticles which are relevant for environmental impact studies. Starting from PET pellets, using
a procedure based on dry grinding by rotor mill and several steps of wet grinding by planetary mill,
aqueous dispersions of PET nanoparticles have been obtained. The size, morphology and chemicalphysical
properties of these latter have been characterized laser diffraction, scanning electron
microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) in order
to optimize the process parameters and to evaluate their potential to be used as a model NPs for
studies on biological tissues.
Ana Maria Pires Assist Prof - Unesp - College of Science and Technology, Brazil
DESIGNE OF CORE@SHELL LUMINESCENT NANOPARTICLES FOR SENSOR AND IMAGING APPLICATIONS
LLuMeS - Laboratory of Luminescence of Materials and Sensors - has been dedicated over the
years to the development and design of luminescent inorganic-organic hybrids applicable in
multifunctional devices or in bioimaging. To this end, efforts have been devoted to the in-depth
study of inorganic matrices, such as Y2O3 or LaAlO3, suitable for hosting lanthanide ions and use
them in the formulation of core@shell hybrid systems. Different routes were investigated, such as
modified Pechini, homogeneous precipitation and sol-gel methods. Among the systems explored, it
stands out the enhancement of the downshifting and the upconversion emission of
,Er3+,Yb3+ phosphor drove by sorbitol instead of the classic ethylene glycol used as
polymerizing agent in the Pechini’s synthesis1
. In this case, the phosphor emission color may be
tuned from the green towards the red spectral region, which is an interesting feature for applications
in optical devices.
Xian Wei Beijing Institute of Technology, China
Improvement on corrosion resistance and biocompability of ZK60 magnesium alloy by carboxyl ion implantation
Because of their mechanical and biocompatible properties, magnesium alloys are promising materials for applications in medical fields. Mg alloys can provide effectively mechanical support for the injured tissue during healing period and can be completely biodegraded in the human body after being cured without a removal surgery. Therefore, magnesium alloys have been considered to be potential biodegradable metallic materials. However, the rapid and uncontrollable corrosion rate has restricted their applications in biomedical field. The fast corrosion rate may lead to the failure of mechanical support, excessive corrosion products, and formation of local alkaline environment. In order to improve the anti-corrosion of Mg alloys, various methods have been proposed, including alloying, coating, and surface treatment, such as anodization, physical/chemical vapor deposition. In this paper, we introduce a method of carboxyl ion (COOH+) implantation to reduce the degradation of ZK60 Mg alloy and improve its functionality in physiological environment. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) experiments show the formation of a smooth layer containing carbaxylic group, carbonate, metal oxides and hydroxides on the ion implanted alloy surface. Corrosion experiments and in vitro cytotoxicity tests demonstrate that the ion implantation treatment can both reduce the corrosion rate and improve the biocompatibility of the alloy. The promising results indicate that organic functional group ion implantation may be a practical method of improving the biological and corrosion properties of magnesium alloys. Although this is only a preliminary study on the grafting of carboxyl into magnesium alloys, this study provides a perspective of employing the organic functional groups implantation techniques to improve the biodegradable magnesium alloys
Yanshan Huang Shanghai Institute of Technology, China
Flexible phosphorus-poped graphene/metal-organic framework-derived porous Fe2O3 anode for lithium-ion battery
Porous metal oxides and heteroatomic doping of carbon materials were extensively studied in
lithium-ion batteries (LIBs). We designed assembly of porous Fe2O3 nano framework into threedimensional P-doped graphene framework (PGF@pFe2O3NF) via using Metal-organic frameworks
as the precursor of porous Fe2O3 and thermal treatment to obtain P doped graphene (Fig.1). The
hierarchical structure with flexible macroporous P-doped graphene network and Fe2O3 nanoporous
framework can effectively promote lithium diffusion. The flexible PGF@pFe2O3NF is directly
compressed as binder-free LIB anode. It exhibited excellent capacity (1106 mAh g−1
performance (410 mAh g−1
at 4000 mA g−1
), and super long cycling performance of 88.2% capacity
retention. Moreover, the PGF@pFe2O3NF-based LIB full cell is also with the high energy of 350.8
(Fig. 1). We offered a strategy to develop advanced porous Fe2O3 -based anode for highpracticability LIBs.
Felipe Wasem Klein Charles Coulomb Laboratory (L2C), CNRS, University of Montpellier, France
Covalent and Non-Covalent Functionalization of Carbon Nanotubes by Aniline-Appended P3HT copolymers
The synthesis of a copolymer derived from poly(3-hexylthiophene), one of the monomers bearing an aniline group, is described. Like the homopolymer, this copolymer is able to functionalize carbon nanotubes by π-stacking of the thiophene units onto the hexagonal network of the nanotubes. Moreover, this copolymer can also covalently bind to the carbon nanotubes through a diazonium reaction, without the need for an intermediate step. Contrary to the non-covalently functionalized carbon nanotubes, whose dispersion in THF is stable for a few hours only, the covalently grafted ones lead to stable dispersions in THF. The spectroscopic characterization of both hybrids show that the copolymer chains organized differently in both types of nanohybrids, confirming the effectiveness of the functionalization.
Mahfoudh Raissi KELENN Technology, France
Silver Nanowires Digital Printing for Inverted Flexible Semi-Transparent Solar Cells
Transparent flexible organic solar cells have been attracting increasing attention as an essential constituent for constructing smart window technologies and integrated photovoltaics. However, silver nanowire electrodes with negligible sheet resistance, good transmittance, and low costs are especially appealing in the design of flexible organic solar cells that require similar power conversion efficiency (PCE) values and superior flexibility compared to devices based on ITO electrodes [1-5]. In this study, we used the new digital printing technology of Digital Materials Deposition to print the PEDOT: PSS as a hole transport layer and silver nanowires as top and bottom electrodes for transparent flexible organic solar cells with an active layer as P3HT: PCBM. All other thin layers were deposited on the PET substrate by the conventional process. The photovoltaic performance of the devices under inverted structure PET/AgNWs/ZnO/P3HT: PCBM/PEDOT/AgNWs is short circuit current density (Jsc) = 9.8 mA/cm2, open circuit voltage (Voc) = 0.53 V, fill factor (FF) = 0.60, power conversion efficiency (PCE) = 2.9% with Visible Light-Transparency = 45%
Fig.1: UV−visible transmittance spectra vs wavelength of transparent electrode AgNWs (green), and the devices AgNWs/ZnO/P3HT-PCBM/PEDOT/AgNWs (blue-bottom side) and (red- top side). J-V curves of semitransparent solar cells illuminated through Top and Bottom Electrode.
Jagadish Chandra Mahato University of Porto, Assistant Professor of Physics Dep.
Self-organized endotaxial cobalt disilicides nanowires on Si(110) surfaces: Fabrication and aspect ratio tunning of the nanowires
Self-organized growth of well-ordered endotaxial silicide nanowires (NWs) on clean Si(110) surfaces has been investigated by in-situ scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). Co deposition on clean Si(110) reconstructed surfaces at ~ 600°C produces unidirectional CoSi2 NWs by reaction of cobalt with the hot silicon substrate. STM investigations reveal four types of distinct NWs, all growing along [1-10] in-plane direction except one type growing along in-plane  direction. There are also some nanodots. The cross-sectional TEM measurements show that the unidirectional NWs are of two types, namely flat-top and ridged. The NWs grow not only on the substrate but also into the substrate. CoSi2 in flat top NWs are in the same crystallographic orientation as the substrate Si and the buried interfaces between CoSi2 and Si are A-type. In the ridged NWs CoSi2 and Si are in different crystallographic orientations and the interfaces are B-type. The ridged NWs are in general wider and grow deeper into the substrate.1 The influence of post deposition annealing on the aspect ratio of these self-organized cobalt silicide nanowireson clean Si(110) surfaces has also been investigated by in situ scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) as well as by scanning electron microscopy (SEM). Half a monolayer of cobalt was deposited on the Si(110) surfaces at ∼600°C substrate temperature. Following cobalt deposition, the substrates have been annealed for different durations. Cobalt forms aligned cobalt disilicide nanowires upon reaction with the silicon substrate, following the twofold substrate symmetry. With increasing duration of annealing, the NWs have been found to grow with larger aspect ratio (length/width), eventually producing narrower NWs. These self-organized unidirectional NWs of sub-hundred nanometer width and ∼4–7 nm height produce a Schottky barrier with the silicon substrate and are expected to find applications in nano electronic devices.
Prof. Anatoliy Zavdoveev National Academy of Sciences of Ukraine, Ukraine
The effect of technological operations temperature on the mechanical properties and structure of high-strength steels grade S460M and S355J2
The use of high-strength steels with a yield strength in the range 350-460 MPa allows reducing the metal consumption of structures made for various purposes. These steels are used in bridge construction and other constructions in general, in the manufacture of oil & gas offshore platforms, supports of wind generators, ships, high pressure vessels, as well as in the manufacture of steel rail freight. Considering that the new generation of steels is obtained due to the integrated use of both microalloying and thermo-mechanical control process (TMCP), the properties obtained can be lost as a result of softening during the thermal treatment of steel. The purpose of the present work is to study the effect of high-temperature isothermal heating on the mechanical properties and structure of rolled sheets and simulated heat affected zone metal of micro-alloyed S355J2 and S460M steels obtained using normalization and thermomechanical treatment, respectively. It is shown that at a temperature T≤630 C, characteristic for treatment associated with the welding stress relieving, the mechanical properties of the investigated steels are stable within the limits of error. S460M steel, obtained by TMCP, can be used in the manufacture of welded steel structures that do not require hot straightening and stamping operations. Heating is allowed not higher than Ac1 (714 С), for relieving welding stresses. Steel S355J2 obtained through normalizing may be used in the manufacture of welded steel involving the operation of a temperature of up to 950 C
Falk Eilenberger Friedrich Schiller University in Jena, Germany
Scalable Functionalization of Exposed-Core Fibers with CVD-Grown Monolayer Transition Metal Dichalcogenides
Monolayer transition-metal dichalcogenides  (TMDs) are a new and highly interesting material for optics and photonics due to their rich photophysics, their strong interaction with light, and large optical nonlinearities . However, their application is limited by the sub-nanometer interaction length, imposed by their atomic thickness; the enhancement of which is essential for future applications. Recently, we have demonstrated a novel type of scalable functionalization technique for exposed-cored optical fibers (ECF) , where MoS2 and WS2 crystals are directly grown on the fiber’s core, based on a one-pot chemical vapour deposition CVD-growth process. We show that by adjusting the growing condition, the density of TMDs monolayers can be tuned. The TMDs interact with the guided light by the evanescent field of the ECF’s guided mode, leading to the exciton formation, photoluminescence (PL) emission, and enhanced nonlinear interaction. The incident light was launched into one facet of the fiber and the PL or nonlinearity generated light was collected from the other face. It exhibits exciton peaks at 678 nm and 622 nm for MoS2 and WS2, as well as enhanced third harmonic generation. Other forms of enhanced nonlinear effects will be discussed in the presentation, as well. We expect that our work may lead to tunable light sources and fiber-based sensors.
Edla Maria Bezerra Lima Brazilian Agricultural Research Corporation, Embrapa Food Technolology Unit , Brazil
Influence of the microstructure on the resistance of PLA biocomposites to food packaging using eco–friendly materials such as mango seed and organo montmorillonite minerals
Biocomposites based on PLA (matrix), organoclays and mango seed as loaded material has been developed by Casting in the present research group since 2015. The ongoing research modified the integument and the kernel of the mango seed by grinding it in a ball mill, reducing the particle size of the mango kernel six times (6X) compared to the original experiment, and fifty times (50x) the mango integument. This process eliminated the effect of elongated shape that the fibers present, increasing the specific surface in contact with the PLA. The samples were characterized in terms of physical-chemical properties (Laser Particle Size, SEM, XRD, Texturometer, FTIR), thermal properties and biodegradability. The SEM results showed that the chloroform output during drying process created bubbles/channels in the biopolymer matrix, which facilitated the access to fluids; weakened the material; and helped the process of biodegradability and decreased mechanical resistance to compression of biocomposites: PLA/integument, PLA/kernel, and PLA/integument/kernel, respectively in 79%, 86% and 84%. In addition, the biodegradability in water and soil was accentuated for the PLA/kernel biocomposite (since 1 week), followed by PLA/integument/kernel biocomposites (5 weeks) and PLA/integument (14 weeks) in a 19-week experiment. These experiments demonstrated that both, the increase in the specific load/matrix contact surface and the creation of bubbles/channels by purging gases during the Casting process, are efficient in accelerating the degradation of these biocomposites in nature and making them highly mechanically fragile. The addition of Bofe and Chocolate organoclay’s accelerated the degradation process of PLA, likely due to the presence of the hydroxyl groups belonging to the silicate layers surface and/or to their organic modifier. The biodegradation of PLA/kernel/integument/Bofe organoclay in water was higher than it was in soil. Furthermore, the materials added to the PLA matrix increased the crystallinity degree and the resistance of the obtained biocomposites.
Henrique José da Silva UNIFRAN - University of Franca, Brazil
Efficiency improvement of photovoltaic cells by coating the protection glass with a silica matrix co-doped with Er3+/Yb3+
This work concerns the power efficiency improvement of polycrystalline silicon photovoltaic cells, by coating the glass which protects the cells, using thin films. The films were obtained by the Sol-Gel process, with a silica matrix co-doped with Er3+/Yb3+ lanthanide ions, that promotes upconversion from infrared to visible light. In this work the films coat the glass instead the cells, like was done in previous studies1, because the films were treated at 300°C and it is easier to work with the coated glass. The voltage, current and electrical power were analysed, for seven different samples: only the photovoltaic cell; the cell protected with a 4 mm common cleaned glass; the cell with a similar glass coated by one and two layers of thin film, submitted at 200ºC and 300ºC and with two different codoped concentrations of Er3+/Yb3+. The commercial squared cells with dimensions 156 X 156 mm and glasses as same dimensions were used. Firstly, the coated glass was submitted to excitation at 980 nm at 300, 720 and 1090 mW laser power. Typical Er3+ emission bands emerged in the green region (2H11/2 to 4I15/2 and 4S3/2 to 4I15/2) and red regions (4F9/2 to 4I15/2). These results is an indication that the films are present covering the glass substrate, and the upconversion occurs. After that, the glasses were placed over the photovoltaic cell and exposed directly to the sun light. Experimental results showed the efficiency improvement when the glass is coated with the thin film. This improvement is higher with two layers and with a thermal treatment of 300°C. In conclusion, the photovoltaic cells efficiency is low due to several factors such as, temperature and non-use of infrared radiation; the solution can be the use of thin films with system to convert the infrared radiation in visible light.
Bikram Gautam University of Arkansas for Medical Sciences (UAMS), Little Rock, Arkansas, USA, India
Assessment of Bacterial Load in Polyethylene Terephthalate (PET) Bottled Water
Reuse of polyethylene terephthalate (PET) bottles have been done to conserve nature, but due to increasing microbial load in the same reused bottle has been cause of many morbidity across the globe. The aim of this study is to determine any associations between bacterial load and the physical condition of the water bottle. For this study, parameters like pH, electrical conductivity (EC), total dissolved solids (TDS), heterotrophic plate count (HPC), total coliform count, and Pseudomonas spp were assessed as per the American Public Health Association, 2005. For the extent of polymer degradation the base of the same PET bottle was subjected to FTIR analysis. The pH value of water samples tested ranged from 5.2 to 6.8. The majority of samples (96%) were found to contain pH values that were unacceptable as per the Department of Food Technology and Quality Control (DFTQC) guideline. Value of electrical conductivity (EC) ranged from 5 to 199 μS/cm. HPC revealed that, out of 100 samples, 48 (48%) samples were found to be acceptable as per the DFTQC guideline value (<25 cfu/mL). Among 100 samples, Pseudomonas spp. was found to be present in 23% of bottled water. Acidic pH and elevated concentrations of TDS and EC may lead to the survival of extremophiles present in HPC which may lead to degradation of PET. FTIR analysis shows that the degradation is under process but has not occurred yet. Microorganisms survive in bottled water as they have many nutrients required for the microorganism in ionic form. The bacteria that survive in bottled water for a long time rely on several survival mechanisms including evolutionary development (evo-devo) and can solely survive on complex polymers like PET.
Marcelo Machado Viana Federal University of Minas Gerais, 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.
Wen-Shi Lee National Cheng-Kung University, Taiwan
Improvement on Conductivity for Thick Film Al Electrode Using Ag-Al Core-Shell by Galvanic Replacement Reaction
Producing high conductivity material with high thermal resilience appears to be interesting particularly in inexpensive way. The aluminum modification with silver coating powder prepared by chemical replacement reaction is promising resolution technology. Replacement process laid on the different value of standard potential of aluminum and silver. The reaction between aluminum powder in silver salt produce silver layer surround aluminum particles. To ensure that there is no oxide layer which can be an obstacle for the reaction to happen, 15% sulfuric acid bath was done for the onset. The prepared powder then pressed into bulk and sintered at 400oC, 450oC, 500oC,550oC, and 600oC. The properties observation also done with 3%, 6%, 9% glass frit addition. Aluminum-silver powder was successfully synthesized and that provides an easy and cheap method to prepare metallic core-shell. The prepared powder demonstrates excellent conductivity even used for paste form compared to pure aluminum powder. Furthermore, synthesizing aluminum-silver by replacement reaction has the promising opportunity to be used in wide application.
Robert Streubel University of Nebraska-Lincoln, United States
Chiral Spin Textures in Amorphous Iron–Germanium Thick Films
Single-crystals and multilayer heterostructures with global inversion symmetry breaking can promote the formation of topological solitary vector fields owing to a vector spin exchange known as the Dzyaloshinskii-Moriya interaction (DMI). - And so can short-range order. - In this talk, I will present experimental evidence of 3D chiral spin textures, i.e., helical spins and skyrmions with different chirality and topological charge, stabilized in amorphous Fe–Ge thick films. Harnessing Lorentz microscopy with exit wave reconstruction, we observe both isotropic Bloch skyrmions (N = 1), previously found in B20 single-crystals, and anisotropic solitons, i.e., antiskyrmions (N = −1) and N = 2 skyrmions. X-ray magnetic circular dichroism (XMCD) spectroscopy suggests a short-range order similar to B20 FeGe single-crystals despite lacking a global broken chiral symmetry. Our results demonstrate that structurally and chemically disordered materials with a random DMI can resemble inversion symmetry broken systems with similar magnetic properties, moments, and states. Yet, disordered systems are distinct by their degenerate spin chirality that allows for forming isotropic and anisotropic topological spin textures at remanence while offering greater flexibility in materials synthesis, voltage and strain manipulation, and an enhanced spin-orbit coupling relevant to prospective microelectronics applications.
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.
Yizhaq Engelberg Israel Institute of Technology, Israel
Functional helical fibrils of the human antimicrobial peptide LL37(17-29) present novel architecture and thermal stability
Antimicrobial peptides (AMPs) are canonical part of the innate immune system of many organisms in all kingdoms of life. Interestingly, certain AMPs assemble into well-ordered fibrils that resemble amyloids, which are proteins associated with neurodegenerative and systemic diseases and which bear unique material properties. LL-37 is an AMP which is expressed by various mammalian cells and is considered to play an important role in the first line of defense against pathogens. hLL-37 is cleaved in-vivo into many active derivatives which show a diverse array of selectivity against microbial strains, and additional functions within the immune system. The hLL-3717-29 13-residue derivative was suggested to serve as the active core of hLL-37. Using X-ray micro-crystallography and electron microscopy techniques, we revealed the supra-helical, fibril structure of hLL-3717-29, and correlated between its self-assembly and antibiotic activity. We also determined the high stability of the fibril’s upon heating, and based on these findings, we are working towards the design novel fibril-forming AMPs with improved shelf life and stability. In addition, we are developing an approach to allow the control over their activity and selectivity upon demand.
Madhumita Mukhopadhyay Amity University, India
Interaction of Macrocyclic Zn (II) Schiff Base cationic Surfactant: A Study using Photometric and Theoretical Approach
A 48 membered macrocyclic tetranuclear Zn (II) complex is reported to be a complex dual anion sensor for fluoride and acetate in aqueous methanolic solution by change in absorption as well as by fluorescence enhancement. In this context, study on the interaction of such Schiff base viz. tetranuclear complex cation [Zn4(LH3)(NO3)5]2+ with a bio-mimicking surfactant is an interesting approach for pursuing detailed study on medicinal industry owing to their antibacterial, antifungal, antiviral activities. A widely used bio mimicking membrane like cetyl trimethyl ammonium bromide (CTAB) is undertaken by the present researchers to study the respective interactions with the functional Zn (II) complex. Steady state absorption and emission studies have been pursued to investigate the course of deciphering the photophysical behaviour of the complex. The extent and mode of binding of the Schiff base with CTAB is analysed using the binding constant magnitude. The extent of interaction among the experimental complex and the biomimicking surfactant is also studied using frontier molecular approach upon engaging ab initio quantum calculations. Hence, analysing the mode of interaction with CTAB, further study is designed for such Schiff base with a suitable bio protein for necessary application in future.
Ana Paula Domínguez Rubio University of Buenos Aires, Argentina
Bacillus subtilis extracellular vesicles can be transported through an in vitro intestinal epithelial cell model
Bacterial Extracellular Vesicles (EVs) have been related to inter-kingdom communication between probiotic/pathogenic bacteria and their hosts. The gastrointestinal tract (GIT) mucosal surface is the primary interface between gut bacteria and internal host tissues. A vital communication between kingdoms in the mammalian GIT is supposed to occur through an exchange of EVs that may interact in a triangular way between gut bacteria and the host. Our aim was to investigate the transcytosis process of B. subtilis EVs using an in vitro intestinal epithelial cell model. In this study, using Confocal Laser Scanning Microscopy, we report that uptake and internalization of CFSE-labeled B. subtilis EVs (115 nm ± 27 nm) by Caco-2 cells are time-dependent. To study the transcytosis process we used a transwell system and EVs were quantified in the lower chamber by Fluorescence and Nanoparticle Tracking Analysis measurements. Intact EVs are transported across a polarized cell monolayer at 60–120 min and increased after 240 min with an estimated average uptake efficiency of 30% and this process is dose-dependent. EVs movement into intestinal epithelial cells was mainly through Z axis and scarcely on X and Y axis. This work demonstrates that bacterial EVs could be transported across the gastrointestinal epithelium. Our findings suggest that this mechanism could be the first step allowing EVs to reach the bloodstream for further delivery up to extraintestinal tissues and organs. The expression and further encapsulation of bioactive molecules into these natural nanoparticles produced by probiotic bacteria EVs of GRAS (Generally Recognized as Safe) bacteria could have practical implications in food, nutraceuticals and clinical therapies.
Yuanyuan Chen Athlone Institute of Technology, Ireland
Eggshell extract embedded in thermoplastic starch packaging for preserving fresh-cut fruits
Calcium chloride (CaCl2) has been widely used to maintain the quality of fresh-cut fruits and vegetables, because it stabilizes and strengthens the membrane system against fungal attacks. It is mainly applied via spray coating and dip coating techniques. This study explored a method of incorporating calcium chloride extracted from eggshells in a packaging material, thermoplastic starch (TPS), via hot-melt extrusion process. The composites were characterized by FTIR, DSC and tensile testing. FTIR confirmed the chemical reactions between CaCl2 and TPS. DSC results indicated a rise in the heat of fusion by increasing the CaCl2 content in TPS. The addition of 10wt% CaCl2 to TPS did not significantly affect the Young module of the composite (p = 0.968). Physiochemical analysis of fresh-cut apple slices was assessed. Samples placed on the surface of the TPS/CaCl2 composites displayed less pH reduction, reduced antioxidant activity, more weight loss and increased reducing sugar, compared to the samples placed on the surface of virgin TPS films. CaCl2 released from the TPS/CaCl2 films was measured and their antimicrobial activity was confirmed by bacterial inhibitory growth assessment (Figure 1). Fungal growth was observed on apple slices placed on virgin TPS film by day 21 while apple slices placed on TPS/CaCl2 20wt% composites did not support any fugal growth for 28 days. In summary, TPS and eggshell-extracted CaCl2 showed the ability to maintain the quality of fresh-cut apples, and TPS / CaCl2 Composite 10wt% could be a good option as a packaging material for fresh-cut fruits due to active antimicrobial activity and maintained mechanical properties.