New Generation Of Materials Research Articles

IF-WS2/Nanostructured Carbon Hybrids Generation and Their Characterization

With the aim to develop a new generation of materials that combine either the known energy absorbing properties of carbon nanofibers (CNF), or the carbon-carbon bond strength of graphene sheets (G), with the shock resistance properties reported for Inorganic Fullerene type WS2 structures (IF-WS2), hybrid CNF/IF-WS2 and G/IF-WS2 were generated, characterized and tested. Experimentation revealed that in situ growth of carbon nanostructures with inorganic fullerene tungsten disulfide particulates had to be performed from particular precursors and fabrication conditions to avoid undesirable byproducts that hinder fiber growth or deter graphene generation. The novel protocols that allowed us to integrate the IF-WS2 with the carbon nanostructures, producing dispersions at the nanoscale, are reported. Resulting hybrid CNF/IF-WS2 and G/IF-WS2 products were analyzed by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and TEM (Transmission Electron Microscopy). The thermal stability of samples in air was evaluated by Thermogravimetric Analysis (TGA). CNF/IF-WS2 and G/IF-WS2 hybrids were introduced into epoxy matrices, and the mechanical properties of the resulting composites were analyzed using nanoindentation. Epoxy composite samples showed drastic improvements in the Young’s modulus and hardness values by the use of only 1% hybrid weight loadings. The carbon nanofiber inclusions seem to have a much greater impact on the mechanical properties of the composite than the graphene based counterparts.

PLEPS study of ions implanted RAFM steels

Current nuclear power plants (NPP) require radiation, heat and mechanical resistance of their structural materials with the ability to stay operational during NPP planned lifetime. Radiation damage much higher, than in the current NPP, is expected in new generations of nuclear power plants, such as Generation IV and fusion reactors. Investigation of perspective structural materials for new generations of nuclear power plants is among others focused on study of reduced activation ferritic/martensitic (RAFM) steels. These steels have good characteristics as reduced activation, good resistance to volume swelling, good radiation, and heat resistance. Our experiments were focused on the study of microstructural changes of binary Fe-Cr alloys with different chromium content after irradiation, experimentally simulated by ion implantations. Fe-Cr alloys were examined, by Pulsed Low Energy Positron System (PLEPS) at FRM II reactor in Garching (Munich), after helium ion implantations at the dose of 0.1 C/cm2. The investigation was focused on the chromium effect and the radiation defects resistivity. In particular, the vacancy type defects (monovacancies, vacancy clusters) have been studied. Based on our previous results achieved by conventional lifetime technique, the decrease of the defects size with increasing content of chromium is expected also for PLEPS measurements.

ChemInform Abstract: Self‐Assembled Selenium Monolayers: From Nanotechnology to Materials Science and Adaptive Catalysis.

AbstractReview: <100 refs.

Selection of peptides binding to metallic borides by screening M13 phage display libraries

BackgroundMetal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials.ResultsIn this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni3B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles.ConclusionsThis study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni3B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

Nanocomposites of iridium oxide and conducting polymers as electroactive phases in biological media

Much effort is currently devoted to implementing new materials in electrodes that will be used in the central nervous system, either for functional electrostimulation or for tests on nerve regeneration. Their main aim is to improve the charge capacity of the electrodes, while preventing damaging secondary reactions, such as peroxide formation, occurring while applying the electric field. Thus, hybrids may represent a new generation of materials. Two novel hybrid materials are synthesized using three known biocompatible materials tested in the neural system: polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT) and iridium oxide (IrO2). In particular, PPy–IrO2 and PEDOT–IrO2 hybrid nanocomposite materials are prepared by chemical polymerization in hydrothermal conditions, using IrO2 as oxidizing agent. The reaction yields a significant ordered new hybrid where the conducting polymer is formed around the IrO2 nanoparticles, encapsulating them. Scanning electron microscopy and backscattering techniques show the extent of the encapsulation. Both X-ray photoelectron and Fourier transform infrared spectroscopies identify the components of the phases, as well as the absence of impurities. Electrochemical properties of the final phases in powder and pellet form are evaluated by cyclic voltammetry. Biocompatibility is tested with MTT toxicity tests using primary cultures of cortical neurons grown in vitro for 6 and 9days.

НОВОЕ ПОКОЛЕНИЕ МАТЕРИАЛОВ И ТЕХНОЛОГИЙ ДЛЯ ИЗГОТОВЛЕНИЯ ЛОНЖЕРОНОВ ЛОПАСТЕЙ ВЕРТОЛЕТА

НОВОЕ ПОКОЛЕНИЕ МАТЕРИАЛОВ И ТЕХНОЛОГИЙ ДЛЯ ИЗГОТОВЛЕНИЯ ЛОНЖЕРОНОВ ЛОПАСТЕЙ ВЕРТОЛЕТА

Survival Life Analysis of the Cutting Tools During Turning Titanium Metal Matrix Composites (Ti-MMCs)

Metal matrix composites (MMCs), as a new generation of materials; have proven to be viable materials in various industrial fields such as biomedical and aerospace. In order to achieve a valuable modification in various properties of materials, metallic matrices are reinforced with additional phases based on the chemical and/or physical properties required in the in-service operating conditions. The presence of the reinforcements in MMCs improves the physical, mechanical and thermal properties of the composite; however it induces significant issues in the domain of machining, such as high tool wear and inferior surface finish. The interaction between the tool and abrasive hard reinforcing particles induces complex deformation behaviour in the MMC structure. Sever tool wear is technically the most important drawback of machining MMCs.In this study a statistical model is developed to estimate the mean residual life (MRL) of the cutting tool during machining Ti-MMCs. Initial wear, steady wear and rapid wear regions in the tool wear curve are regarded as the different states in the statistical model. Hence, the valuable information regarding the estimated total time spent in each state, called the sojourn time, and the transition times between the states are obtained from the model.In this paper the standard cutting conditions, based on the recommendation of the tool supplier, are adopted. Based on a Weibull model, the reliability and hazard functions are obtained and are utilized in order to calculate the MRL and the sojourn times.

Stress intensity factor analysis of epoxy/SWCNTs based on global-local multiscale method

Carbon nanotube (CNT) is considered as a new generation of material possessing superior mechanical, thermal, and electrical properties. In this research, a multiscale finite element analysis is proposed to study the interaction between nanotubes and matrix at the nanoscale near a crack tip. The influence of the chirality and length of single-walled CNT (SWCNTs) on the stress intensity factor of epoxy/SWCNT were studied. It was found that the chirality, length, and radius of CNT have significant effects on the stress intensity factor of nanocomposites. Multiscale simulations from macro to nano or the reverse improved specification of toughness mechanisms.

Microalgae as a Potential New Generation of Material for Various Innovative Products

Nowadays, great interest has been developed in the isolation of novel bioactive compounds from the marine world which represents the half of the global biodiversity and an untapped reservoir of natural ingredients. Among these ingredients microalgae can play a key role [1,2]. They can biosynthesize many valuable substances with potential applications in the food, feed, pharmaceutical, cosmetic and chemical industry. But the impact of microalgae on the human society is not limited only to their useful products, because of their crucial role on the biosphere through photosynthesis. Microalgae are primitive, aquatic and photosynthetic microorganisms which appeared on earth about 3.5 billion years ago. They have unicellular or simple multicellular structure and size between 0.2 to 2 nm. Moreover, they have some advantages over terrestrial plants such as higher productivity due to their reproducing by simple division one or two times per day, limited seasonal variation and no lack of raw material. It is estimated that more than 30,000 species of microalgae exist, but only a few are safe and are cultivated in industrial quantities [3,4]. Microalgae that are already commercialized and are used in biotechnology belong to the green algae (e.g. the species Chlorella, Dunaliela, Haematococcus, Tetraselmis, Isochrysis) and cyanobacteria – the intermediate blue-green colored species between plants and bacteria (e.g. Spirulina (Arthrospira), Aphanizomenon flosaquae) [3,5,6]. Microalgae can survive under harsh conditions and environmental stressors such as high or low temperature, anaerobiosis, high salinity, photo-oxidation, high osmotic pressure and ultra-violet radiation, so they can greatly modify their chemical composition [2,7]. As a result of the rapid adaptation of algae to the new environmental conditions, they synthesize and produce a great variety of secondary metabolites having structure that cannot be found in other organisms [8]. As a results marine microalgae, due to their abundant availability in the marine ecosystem are an excellent source of valuable compounds such as polyunsaturated fatty acids, proteins, tocopherols and sterols, vitamins and minerals, antioxidants and pigments [7,9]. Consequently, nowadays there are several different applications for microalgae [2,3,10-12]. They could be used in:

Self‐Assembled Selenium Monolayers: From Nanotechnology to Materials Science and Adaptive Catalysis

Self-assembled monolayers (SAMs) of selenium have emerged into a rapidly developing field of nanotechnology with several promising opportunities in materials chemistry and catalysis. Comparison between sulfur-based self-assembled monolayers and newly developed selenium-based monolayers reveal outstanding complimentary features on surface chemistry and highlighted the key role of the headgroup element. Diverse structural properties and reactivity of organosulfur and organoselenium groups on the surface provide flexible frameworks to create new generations of materials and adaptive catalysts with unprecedented selectivity. Important practical utility of adaptive catalytic systems deals with development of sustainable technologies and industrial processes based on natural resources. Independent development of nanotechnology, materials science and catalysis has led to the discovery of common fundamental principles of the surface chemistry of chalcogen compounds.

Production of Al Metal Matrix Composites by the Stir-Casting Method

It is well known that the addition of ceramic phases in an alloy e.g. aluminum, in form of fibers or particles influences its mechanical properties. This leads to a new generation of materials, which are called metal matrix composites (MMCs). They have found a lot of application during the last twenty-five years due to their low density, high strength and toughness, good fatigue and wear resistance. Aluminum matrix composites reinforced by ceramic particles are well known for their good thermophysical and mechanical properties. As a result, during the last years, there has been a considerable interest in using aluminum metal matrix composites in the automobile industry. Automobile industry use aluminum alloy matrix composites reinforced with SiC or Al2O3 particles for the production of pistons, brake rotors, calipers and liners. However, no reference could be cited in the international literature concerning aluminum reinforced with TiB particles and Fe and Cr, although these composites are very promising for improving the mechanical properties of this metal without significantly alter its corrosion behavior. Several processing techniques have been developed for the production of reinforced aluminum alloys. This paper is concerned with the study of TiB, Fe and Cr reinforced aluminum produced by the stir-casting method.

The external walls of a passive building: A classification and description of their thermal and optical properties

This paper attempts a new classification of insulating materials from the perspective of their utility in the pro-ecological passive construction industry. The main criterion is the conductivity of thermal and solar energy. Based on their ability to conduct or block fluxes of thermal and solar energy, six types of insulating walls are proposed. On the basis of this criterion there are traditional dividing walls (typical walls, wall insulating materials, windows), energy-saving building materials (Trombe walls, transparent insulation, energy-saving windows) and materials of the future. This classification will facilitate the conscious and planned development of the latter.These new-generation materials allow energy to be saved, but they also enable it to be harnessed from sunlight (transparent insulation) and to store it, for example, in phase change materials. Combining these materials in hybrid solutions will provide fresh opportunities for the energy-saving building industry.Theoretical research into these six types of insulating material has enabled their properties and building utility to be formulated.

Development of nitric oxide-eluting nanocomposite materials using nanoparticles for cardiovascular applications

Purpose: To develop nitric oxide (NO)-eluting nanocomposite biomaterials using nanoparticles conjugated with NO donors, which induce anti-thrombogenic properties in the development of cardiovascular devices. Methods: NO-releasing fumed silica nanoparticles (FSNPs) were synthesised via the reaction of S-nitrosothiol NO donors on to the surface of FSNPs. FTIR, NMR, acid titration, and Ellman's tests confirmed the attachment of NO donors on to FSNPs. NO-FSNPs were dispersed in to polyhedral oligomeric silsesquioxane-poly(carbonateurea)urethane (POSS-PCU) nanocomposite polymer at 2, 4, and 8 wt% and bypass grafts were fabricated using extrusion phase inversion techniques. NO release from grafts was measured in a physiological pulsatile flow circuit using the amperometric technique, and their biocompatibility was evaluated in whole blood as a measure of thrombogenicity. Results: The results confirmed the functionalisation of FSNPs with NO donors and release profiles that could be controlled by changing the amount of FSNPs in the polymer matrix. All FSNPs dispersed in to POSS-PCU were capable of NO elution and the optimal release profile was evident with 2 wt% NO-FSNP at physiologically relevant concentrations of ~ 8×10−10 mol cm−2 min−1 over a 7-h period. NOeluting grafts enhanced anti-thrombogenic properties when compared with controls to confirm the protective roles of NO and attenuation of thrombosis. Conclusions: This study used POSS-PCU nanocomposite, already in used in human as tracheal and lacrimal duct conduits. NO-releasing FSNPs were incorporated in to POSS-PCU, and controlled release was confirmed in vitro. NO-eluting bypass grafts with anti-thrombogenic properties represent a newgeneration ofmaterials in the development of cardiovascular devices.

Human endometrial stem cells as a useful source for cardiovascular regeneration

Purpose: To develop nitric oxide (NO)-eluting nanocomposite biomaterials using nanoparticles conjugated with NO donors, which induce anti-thrombogenic properties in the development of cardiovascular devices. Methods: NO-releasing fumed silica nanoparticles (FSNPs) were synthesised via the reaction of S-nitrosothiol NO donors on to the surface of FSNPs. FTIR, NMR, acid titration, and Ellman's tests confirmed the attachment of NO donors on to FSNPs. NO-FSNPs were dispersed in to polyhedral oligomeric silsesquioxane-poly(carbonateurea)urethane (POSS-PCU) nanocomposite polymer at 2, 4, and 8 wt% and bypass grafts were fabricated using extrusion phase inversion techniques. NO release from grafts was measured in a physiological pulsatile flow circuit using the amperometric technique, and their biocompatibility was evaluated in whole blood as a measure of thrombogenicity. Results: The results confirmed the functionalisation of FSNPs with NO donors and release profiles that could be controlled by changing the amount of FSNPs in the polymer matrix. All FSNPs dispersed in to POSS-PCU were capable of NO elution and the optimal release profile was evident with 2 wt% NO-FSNP at physiologically relevant concentrations of ~ 8×10−10 mol cm−2 min−1 over a 7-h period. NOeluting grafts enhanced anti-thrombogenic properties when compared with controls to confirm the protective roles of NO and attenuation of thrombosis. Conclusions: This study used POSS-PCU nanocomposite, already in used in human as tracheal and lacrimal duct conduits. NO-releasing FSNPs were incorporated in to POSS-PCU, and controlled release was confirmed in vitro. NO-eluting bypass grafts with anti-thrombogenic properties represent a newgeneration ofmaterials in the development of cardiovascular devices.

Harnessing Dynamic Covalent Bonds in Patchy Nanoparticles: Creating Shape-Shifting Building Blocks for Rational and Responsive Self-Assembly.

Using computational modeling, we suggest and demonstrate a novel class of building blocks for nanoparticle self-assembly, that is, shape-shifting patchy nanoparticles. These nanoparticles are designed by harnessing dynamic covalent bonds between nanoparticles and patches decorated on them. The breaking and reforming of these bonds in response to their environment allow the patches to undergo a structural rearrangement that shifts the location or number of patches. Our simulations for the assembled superstructures and kinetic pathway of two types of these building blocks demonstrate that shape-shifting patchy nanoparticles delicately meet two emerging design concepts of next generation materials: rational self-assembly and responsive matter. In this context, these nanoparticles may enable new generations of materials with reconfigurable property as well as controllable topologies in a dynamical manner.

Naturally Self-Assembled Nanosystems and Their Templated Structures for Photonic Applications

Self-assembly has the advantage of fabricating structures of complex functionalities, from molecular levels to as big as macroscopic levels. Natural self-assembly involves self-aggregation of one or more materials (organic and/or inorganic) into desired structures while templated self-assembly involves interstitial space filling of diverse nature entities into self-assembled ordered/disordered templates (both from molecular to macro levels). These artificial and engineered new-generation materials offer many advantages over their individual counterparts. This paper reviews and explores the advantages of such naturally self-assembled hybrid molecular level systems and template-assisted macro-/microstructures targeting simple and low-cost device-oriented fabrication techniques, structural flexibility, and a wide range of photonic applications.

Designing Safer Chemicals

Designing Safer Chemicals

Electrodynamic tailoring of self-assembled three-dimensional electrospun constructs

The rational design of three-dimensional electrospun constructs (3DECs) can lead to striking topographies and tailored shapes of electrospun materials. This new generation of materials is suppressing some of the current limitations of the usual 2D non-woven electrospun fiber mats, such as small pore sizes or only flat shaped constructs. Herein, we pursued an explanation for the self-assembly of 3DECs based on electrodynamic simulations and experimental validation. We concluded that the self-assembly process is driven by the establishment of attractive electrostatic forces between the positively charged aerial fibers and the already collected ones, which tend to acquire a negatively charged network oriented towards the nozzle. The in situ polarization degree is strengthened by higher amounts of clustered fibers, and therefore the initial high density fibrous regions are the preliminary motifs for the self-assembly mechanism. As such regions increase their in situ polarization electrostatic repulsive forces will appear, favoring a competitive growth of these self-assembled fibrous clusters. Highly polarized regions will evidence higher distances between consecutive micro-assembled fibers (MAFs). Different processing parameters--deposition time, electric field intensity, concentration of polymer solution, environmental temperature and relative humidity--were evaluated in an attempt to control material's design.

Some grand challenges in environmental chemistry

OVERVIEW Environmental chemistry is a very broad topic (Jardim, 1998; Ventura et al., 2009; Kubicki and Mueller, 2010; Steinbach and Hoffmann, 2010; Subramaniam, 2010; Caumul, 2011; Gao et al., 2011; Humphris, 2011; Wirth et al., 2011). This subject spans aspects of all states of matter and various phenomena including pollution, (Ashmore and Nathanail, 2008; Busca, 2009; Carls and Meador, 2009; Feldmann et al., 2009; Steinbach and Hoffmann, 2010; Gao et al., 2011; Humphris, 2011; Wirth et al., 2011) the generation of new materials, health, medicine, and energy. With ever increasing population constraints on resources demand interest in sustainable technologies and these must be green in nature. In terms of energy, there are environmental chemistry concerns regarding solar, geothermal, nuclear, fossil fuel, and other forms of energy. In the area of materials, nano-size systems are currently of tremendous interest and such systems pose environmental and health threats that are just beginning to be formulated (Ashmore and Nathanail, 2008; Gao et al., 2011; Humphris, 2011; Wirth et al., 2011). Feedstocks of all types are subject to contamination from a variety of sources. Analyzing such feedstocks and determining exact concentrations can be a challenge. Computational modeling studies are often useful in understanding such complex systems (Ventura et al., 2009; Kubicki and Mueller, 2010). Continual new regulations and protocols based on new data influence our world every day. The characterization of materials is an area that continues to improve. The chemical and physical properties of systems and their environmental effects are often challenging especially with real world samples that are not pristine and may have a multitude of components. These days composite materials or multi-component systems are being developed to solve complex problems. The synergetic effects of such composites are often not well known and the potential environmental problems associated with such composites are also not well known (He et al., 2008; Carls and Meador, 2009). The development of novel methods of analysis to study such complex systems and concomitant environmental chemistry problems is a major area of research. In situ monitoring and miniaturization of such instrumentation are some of the goals of this area. There is a continual need for basic studies of air, water, soil, and artificial/manmade materials. How all of these systems interact with various life forms is of considerable interest. Interactions of bacteria, viruses, and cells in these different environments continue to be developed. The political, legal, and social aspects of results of these studies are constantly being explored.

Tiered Protocol for Sussing Out Endocrine Disruption

Tiered Protocol for Sussing Out Endocrine Disruption