New Generation Of Materials Research Articles

Solid waste management in Bogotá: the role of recycling associations as investigated through SWOT analysis

In emerging economies, recycling provides an opportunity for cities to increase the lifespan of sanitary landfills, to reduce the costs of solid waste management, to decrease environmental problems from waste treatment by reincorporating waste into the productive cycle and to protect and develop the livelihoods of citizens who work as informal waste pickers. However, few studies have analysed the possibilities of and strategies for integrating the formal and informal sectors in solid waste management for the benefit of both. This integration is the key, especially in developing countries, to understanding how the recycling population can develop a business despite their social and economic limitations. The aim of this study was to perform a strength, weakness, opportunity and threat (SWOT) analysis of three recycling associations in Bogota with the aim of examining and understanding the recycling situation from the perspective of members of the informal sector in their transition to becoming authorised waste providers. This issue has rarely been studied in the context of developing countries. The data used in the analysis are derived from multiple sources, including a literature review, Bogota’s recycling database, focus group meetings, governmental reports, national laws and regulations and interviews with key stakeholders. The results of this study show that as the primary stakeholders, the formal and informal waste management sectors can identify the internal and external conditions of recycling in Bogota. Several strategies were designed based on the SWOT analysis. The participation of recycling associations is important in the design and application of waste policy, the consolidation of recycling through an effective business model, promotional programmes for social inclusion and the development of new transformation processes and technologies to valorise recycling materials. In conclusion, recycling associations can become authorised waste providers through a profitable business that increases recycling rates to create a productive process from waste during the generation of new materials and to decrease environmental problems while improving the welfare and living conditions of recyclers. These findings are important for Bogota to advance and promote recycling as a key strategy for integrated sustainable waste management in the city.

Nanostructural Modification of Polytetrafluoroethylene and its Composition by Energy Influence

Supramolecular structure and performance properties of activated matrix polytetrafluoroethylene, modified fiber filler and composites based on its are investigated. Shown that the energy influence contributes to transfer of the polytetrafluoroethylene matrix structure in nanoscale state. The technology of sequential mechanical activation of the ingredients composition before their mixing by the energy influence is developed. Nanostructured matrix, fragments of carbon fibers and their interface in the formed composite determine the unique physical, mechanical and operational characteristics of composite materials. As a result of research the material of new generation with maximum physical and mechanical and tribotechnical properties is developed.

АКУСТИЧЕСКИЕ ПОЛИМЕРНЫЕ МАТЕРИАЛЫ НОВОГО ПОКОЛЕНИЯ (обзор)

АКУСТИЧЕСКИЕ ПОЛИМЕРНЫЕ МАТЕРИАЛЫ НОВОГО ПОКОЛЕНИЯ (обзор)

Prospects of application of nanostructured heterophase polyfunctional composite materials in aero-engine manufacturing

The article provides a brief overview of the features and applications of developed and investigated nanostructured superhard composite materials and coatings on their basis. The research carried out makes it possible to draw a conclusion of great prospects of using nanostructured composite materials on the basis of carbides, carbonitrides and diborides of transitional and refractory metals for aerospace objects. The use of new composite structural materials is the top priority in the area of improving technical and economic parameters of gas turbine engines. These materials are superior to traditional materials by their basic physical and mechanical properties several-fold. Numerous studies in this field indicate that the greatest progress in the development of new advanced structural composite materials can be expected on the way to creating materials based on polymeric, metallic, intermetallic, and ceramic matrices. At present, there is a distinct trend towards the creation of units and assemblies of multiple-start gas turbine engines and power plants with longer life and increased durability. Research in the area of using new-generation composite materials is carried out in almost all developed countries, primarily in the United States and Japan.

β-Functionalized Push–Pull opp-Dibenzoporphyrins

The synthesis of a series of β-functionalized push-pull dibenzoporphyrins was realized. These porphyrins display subtle push-pull effects, demonstrating the exceptional tunability of their electronic and electrochemical properties. The UV-vis spectra of these porphyrins show unique absorption patterns with shouldered Soret bands and extra absorptions in the Q-band region. Stronger electron-withdrawing groups display more significant bathochromic shifts of the Soret bands. The fluorescence spectra of these porphyrins show strong near-IR emission bands (600-850 nm). In particular, fluorescence quenching effect was observed for pyridyl carrying push-pull porphyrin 4c in the presence of an acid. TFA titration study of 4c using UV-vis and fluorescence spectroscopy reveals that the fluorescence quenching can be mainly attributed to the protonation of the pyridyl groups of 4c. The versatile synthetic methods developed in this work may open a door to access a large number of functionalized organic materials that are currently unavailable. The structure-property studies provided in this work may provide useful guidelines for the design of new generations of materials in dye-sensitized solar cells, in nonlinear optical applications, as fluorescence probes, as well as sensitizers for photodynamic therapy.

Integration of environmental aspects into R&D inter-organizational projects management: application of a life cycle-based method to the development of innovative windows

Within Research and Development programmes funded by the European Union, new generations of materials, products, systems, and processes are under development. In the present article the structure of a Research and Development publicly funded inter-organizational project with its deliverables and milestones is analysed, since it can enhance the development of real eco-innovation. In particular the technical and managerial experience gained during EU-funded FP7 project called HarWin (Harvesting solar energy with multifunctional glass-polymer windows) is reported. The project aimed at designing innovative smart windows with polymer-glass composite glazing and framing. As Life Cycle Assessment has been increasingly explicitly required in R&D projects, efforts have been dedicated to enlarge knowledge on the development of specific tailored LCA methods and tools and on the application of LCA in inter-organizational R&D projects in general. The specific method developed and systematically tested within the project to assess the environmental burden associated to the life cycle of windows at the R&D stage is reported. The specific tool that has been developed to allow environmental data gathering and direct involvement of the design team in the environmentally conscious design of the window is also described, highlighting its experienced benefits. The management of the HarWin project has been analysed and reported in order to identify strengths and weaknesses for the integration of environmental aspects and of LCA in particular. Finally, a list of recommendations for improving the planning in future calls and the execution of future projects is reported.

Tool Wear Monitoring and Alarm System Based on Pattern Recognition With Logical Analysis of Data

This paper presents a new tool wear monitoring and alarm system that is based on logical analysis of data (LAD). LAD is a data-driven combinatorial optimization technique for knowledge discovery and pattern recognition. The system is a nonintrusive online device that measures the cutting forces and relates them to tool wear through learned patterns. It is developed during turning titanium metal matrix composites (TiMMCs). These are a new generation of materials which have proven to be viable in various industrial fields such as biomedical and aerospace. Since they are quite expensive, our objective is to increase the tool life by giving an alarm at the right moment. The proposed monitoring system is tested by using the experimental results obtained under sequential different machining conditions. External and internal factors that affect the turning process are taken into consideration. The system's alarm limit is validated and is compared to the limit obtained when the statistical proportional hazards model (PHM) is used. The results show that the proposed system that is based on using LAD detects the worn patterns and gives a more accurate alarm for cutting tool replacement.

(Invited) Ultra-Wide-Bandgap Semiconductors for Power Electronics

Dramatic improvements in Size, Weight, and Power (SWaP) for power conversion systems have recently been enabled by the adoption of Silicon Carbide (SiC) and Gallium Nitride (GaN) based power switching devices. Such improvements are of high interest for both civilian and defense applications. However, despite the significant progress in these Wide-Bandgap (WBG) materials and the dramatic advantages conferred by them relative to the incumbent Silicon (Si) based technology, various challenges related to performance and reliability remain to be solved. For example, SiC MOSFETs have suffered from gate oxide reliability problems, while non-MOS SiC devices may not be normally-off; similarly, GaN-channel HEMTs are intrinsically normally-on, and normally-off operation requires complex gate stack processing that may degrade long-term device reliability. Lateral GaN HEMTs are also limited in breakdown voltage, and do not avalanche and must thus be over-designed to ensure reliable operation. Improvement in WBG material and device technology has slowed as the technology has matured and become commercially available, and fundamental material properties now limit the performance. Thus, dramatic leaps in power electronics performance require a new generation of materials, the so-called “Ultra” Wide-Bandgap (UWBG) materials with bandgaps larger than 3.4 eV. Representative materials in this category include Aluminum Nitride (AlN), Diamond, and Gallium Oxide (Ga2O3). This talk will focus on our efforts to develop the Aluminum Gallium Nitride (AlGaN) system with Al composition in the range of 30-100% into a viable material for next-generation power electronics. The basic advantages of AlGaN relative to Si, SiC, and GaN will be discussed, as evidenced by the superior unipolar Figure-of-Merit (FOM) for AlN as demonstrated in Figure 1. Here, AlN is shown to have a theoretical order-of-magnitude improvement relative to GaN; in the plot, high breakdown voltage (VB, horizontal axis) and low specific on-resistance (Ron,sp, vertical axis) are desired. This FOM is based on a number of basic material parameters such as mobility and critical electric field, which will be covered in the talk. Fundamental challenges associated with substrates, epitaxial growth, doping, and point and extended defects will be discussed. Vertical and lateral (heterostructure-based) device architectures will likewise be covered, and the advantages and limitations imposed by the properties of the UWBG AlGaN materials will be examined. In particular, it will be demonstrated that an intrinsically normally-off device that exceeds the capability of GaN (as measured by the FOM) is viable. Experimental results at both the material and device levels will be presented. This work was supported by the Laboratory Directed Research and Development (LDRD) program at Sandia. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. Figure 1

Photoelectrochemistry of Nano Zerovalent Fe Based CdFe2O4 / FexOy Produced from Cd2+ Water Remediation

Iron nanoparticles are a new generation of materials for environmental remediation. Various metallic ions including Pb2+, Cr6+, Ni2+, As3+, As5+, Cd2+, Cu2+, Zn2+ and Ba2+ had been fixated from water using this new technology.1 Nanoscale zero-valent iron (nZVI) had been studied as an alternative for decontamination processes. In nZVI reaction, metallic iron is oxidized in presence of water. During this reaction, other metal ions can be removed from the aqueous media by chemical absorption.4 In this process, iron oxides such as hematite (α-Fe2O3) are produced.5 This α-Fe2O3 have been broadly study for catalytic applications due to its highly active photochemical properties and resistance to corrosion, but the excited electrons have a short lifetime and the charge mobility is low.6 Approaches such as doping with other metals and changing the structural arrangement of the system had been employed to overcome α-Fe2O3 challenges regarding to the electron transfer processes. Previous studies from our group proves that the incorporation of cadmium (Cd) ions in the oxidized nZVI produce a changes in the structure of the system associated to iron oxides species (FexOy) and cadmium ferrite (CdFe2O4) formation. This can be done without using high temperatures to complete the preparation of the material, a common practice in the literature. Additional to these changes, cadmium species have been also studied for their photochemical applications. Regardless of all this information, there are few reports, which employ these particles as photocatalysts. nZVI particles were used in Cd2+ remediation as a proof of concept for further use at the Las Cucharillas Marsh. Our group had done experiments in Cd2+ concentrations between 1 and 6ppm. This led us to explore the effect of higher Cd2+ concentration on the nZVI. Moreover, an alternative use of the remediation nZVI product was evaluated. This led to its possible use in photoelectrochemical cells. A challenge in this device is to optimize the quantum conversion efficiency, which is affected by the electron transfer processes in the system. We used the CdFe2O4 / FexOy produced from nZVI in a photoelectrochemical cell to further understand their properties. The Cd concentration employed is similar to contaminated area with this heavy metal at Las Cucharillas Marsh, Cataño, Puerto Rico. The soil in this region is mainly acidic, i.e. between pH 2 and 5. Soil analysis, using ICP following the EPA 6010B method; have shown Cd2+ concentrations between 1 and 33ppm (mg/kg) in different regions of the marsh. The nZVI have been treated in different Cd2+ solution between 1 and 30 ppm, based on the concentrations found in the Las Cucharillas Marsh. The nZVI treated in a Cd2+ 30ppm solution were evaluated as anode materials for photoelectrochemical cells. This materials was characterized by different techniques such as XPS, XRD, electron microscopy, FT-IR, UV-Vis, cyclic voltammetry, and electrochemical impedance spectroscopy.

Developing optimized technologies for new-generation materials

We formulate a mesokinetic model of feedstock transformation into a material based on a system of devices in which the material is mechanically, thermally, or chemically modified. The idea of a frequency function that describes the rate of change of the function of particle distribution for a substance over the states in each device has been introduced. The possible application of the model to the development of technology that provides the maximum contribution of every device to the feedstock transformation to material is considered. It has been shown that, in developing the technology of the materials, it should be taken into account that, in many systems, the function of the size distribution of the particle varies according to the Fokker–Planck equation.

Tip-induced domain growth on the non-polar cuts of lithium niobate single-crystals

Currently, ferroelectric materials with designed domain structures are considered as a perspective material for new generation of photonic, data storage, and data processing devices. Application of external electric field is the most convenient way of the domain structure formation. Lots of papers are devoted to the investigation of domain kinetics on polar surface of crystals while the forward growth remains one of the most mysterious stages due to lack of experimental methods allowing to study it. Here, we performed tip-induced polarization reversal on X- and Y-non-polar cuts in single-crystal of congruent lithium niobate which allows us to study the forward growth with high spatial resolution. The revealed difference in the shape and length of domains induced on X- and Y-cuts is beyond previously developed theoretical approaches used for the theoretical consideration of the domains growth at non-polar ferroelectric surfaces. To explain experimental results, we used kinetic approach with anisotropy of screening efficiency along different crystallographic directions.

Optimal replacement times for machining tool during turning titanium metal matrix composites under variable machining conditions

Little practical results are known about the cutting tool optimal replacement time, specifically for machining of composite materials. Due to the fact that tool failure represents about 20% of machine down-time, and due to the high cost of machining, in particular when the work piece’s material is very expensive, optimization of tool replacement time is thus fundamental. Finding the optimal replacement time has also positive impact on product quality in terms of dimensions and surface finish. In this article, two new contributions to research on tool replacement are introduced. First, tool replacement mathematical models are proposed. These models are used in order to find the optimal time to tool replacement when the tool is used under variable machining conditions, namely, the cutting speed and the feed rate. Proportional hazards models are used to find an optimal replacement function. Second, this model is obtained during turning titanium metal matrix composites. These composites are a new generation of materials which have proven to be viable in various industrial fields such as biomedical and aerospace, and they are very expensive. Experimental data are obtained and used in order to develop and to validate the proportional hazards models, which are then used to find the optimal replacement conditions.

Novel pyrrolidinium-based polymeric ionic liquids with cyano counter-anions: High performance membrane materials for post-combustion CO2 separation

Polymeric ionic liquids (PILs) are blossoming as a new generation of materials at the interface of many areas leading to a renaissance of the field of ionic polymers. Although PILs are interesting membranes materials for CO2 separation, additional research is still required to realize their full potential. In this work, pyrrolidinium-based polymers containing different cyano-functionalized counter-anions were synthesized by straightforward anion exchange reactions and characterized. Their film forming ability blended with different amounts of free ionic liquid (IL) was evaluated and the CO2 and N2 permeation properties through the prepared composites were determined. The results show that increasing the IL content in the composites not only increased CO2 permeability but also boosted the CO2/N2 permselectivity, leading to improved separation performances. The best performance was achieved for the C(CN)3-based membrane containing 60wt% of IL, which overcomes the Robeson 2008 upper bound, with CO2 permeability of 439.3Barrer and CO2/N2 permselectivity of 64.4. Therefore, the pyrrolidinium-based PIL combined with the [C(CN)3]− as counter-anion has potential for efficient post-combustion CO2 separation, suggesting the preparation of high performance membranes for industrial applications.

Compact Process for the Preparation of Microfine Spherical High-Niobium-Containing TiAl Alloy Powders

High-Nb-containing TiAl alloys are a new generation of materials for high-temperature structural applications because of their superior high-temperature mechanical properties. The alloy powders can be widely used for additive manufacturing, thermal spraying, and powder metallurgy. Because of the difficulty of making microfine spherical alloy powders in quantity by conventional techniques, a compact method was proposed, which consisted of two-step ball milling of elemental powders and subsequent radio frequency (RF) argon plasma spheroidization. In comparison with conventional mechanical alloying techniques, the two-step milling process can be used to prepare alloy powders with uniform scale in a short milling time with no addition of process control agent. This makes the process effective and less contaminating. After RF argon plasma spheroidization, the powders produced exhibit good sphericity, and the number-average diameter is about 8.2 μm with a symmetric unimodal particle size distribution. The powders perform high composition homogeneity and contain predominately supersaturated α 2-Ti3Al phase. The oxygen and carbon contents of the spheroidized powder are 0.47% and 0.050%, respectively.

Mesoporous bioactive glasses: Relevance of their porous structure compared to that of classical bioglasses

AbstractIn the last decade, the development of third generation bioceramics for Bone Tissue Regeneration has experienced significant progress with the emergence of a new generation of nanostructured materials named mesoporous bioactive glasses (MBG). This new generation of materials, also known as “templated glasses”, presents chemical compositions similar to those of conventional bioactive sol–gel glasses and the added value of an ordered mesopore arrangement. This article shows an indepth comparative study of the ordered porous structures of MBGs compared to conventional glasses (melt and solgel) andhowthese properties influence the bioactivity process. Moreover, the possibility to tailor the textural and structural properties of these nanostructured materials by an exhaustive control of the different synthesis parameters is also discussed. A brief overview regarding the possibility of using these materials as controlled drug delivery systems and as starting materials for the fabrication of 3D scaffolds for bone tissue regeneration is also given.

Interphase engineering in polymer composites: Challenging the devil…

invented by the devil’ is credited to Wolfgang Pauli, Nobel Prize in Physics in 1945. The interphase is a key issue for polymer composites since it guarantees the necessary stress transfer from the ‘weak’ matrix to the ‘strong’ reinforcement. Since the interphase is the key factor of composite performance, its engineering design is being under spot of interest from both academia and industry. New impetus to interphase engineering was provided by the worldwide extensive research on polymer nanocomposites. The mechanical properties of this new generation of materials did not fully meet the expectations, which might have been exaggerated as far as the replacement of traditional reinforcements by nanoadditives is concerned. However, nanofillers and nanocomposites have recently attracted great interests as potential solutions to some acute problems with composites’ interphase. Among these problems the detection of failure/damage, their eventual healing, poor out-ofplane performance including low delamination resistance and inherently missing properties should be mentioned. Failure/damage start at the interface or in the interphase. Therefore, creating a ‘smart’ interphase the properties (e.g. electrical conductivity, piezoresistivity...) of which change with progressing damage would allow a structural health monitoring (DOI: 10.1016/j.carbon.2012.04.008). The load bearing of traditional fibers can be prominently improved when nanoscaled additives (nanotube, graphene, clay...) are deposited on their surfaces by suitable manners. The related ‘hierarchical’ fibers enhance the delamination resistance, support a more homogenous stress distribution and improve other out-of-plane properties. The encapsulation strategy of healing agent was successfully adapted for the interphase by creating and depositing submicron-size capsules onto the fiber surface (DOI: 10.1016/j.compscitech.2013.02.007). Most of the above concepts, well summarized in recent reviews (DOI: 10.1016/j.pmatsci.2015.02.003 and DOI: 10.1016/j.compscitech.2014.07.005), have been conceptually proved at a laboratory level and need to be up-scaled to in industrial praxis. New strategies to overcome deficiencies with polymer composites are still needed. However, the interphase engineering is not yet finished (the devil has his fingers still there...) – why not to play in this exciting research arena?

USE OF LOCAL NATURAL SILICEOUS RAW MATERIAL AND WASTES FOR PRODUCTION OF HEAT-INSULATING FOAMCONCRETE

The article analyzes the resource base, reserves and the use of siliceous rocks, their economic feasibility of the use for production of building materials of new generation with low-energy and other costs. Presented are the results of laboratory research and testing technology of production of insulating foam from a composition based on an aqueous solution of sodium silicate obtained from the local siliceous rocks (diatomite) and the liquid alkali component - soapstock, hardener from ferrochrome slag and waste carbonate rock able to harden at a low temperature processing ( 100-110 ° C).

A novel method for fabrication of fascinated nanofiber yarns

Potential applications of nanofibers as a new-generation of material will be realized if suitable nanofiber yarns become available. Electrospinning has been widely accepted as a feasible technique for the fabrication of continuous nanofiber yarns. However its low output limited its industrial applications. This paper presents a new processing approach to fabrication of fascinated nanofiber yarns which possess excellent properties of nanofibers while enhancing its mechanical strength by the core yarn.

Synthesis, characterization, spectroscopic and electrochemical studies of donor–acceptor ruthenium(II) polypyridine ligand derivatives with potential NLO applications

In this work we report the preparation of six new donor–metal–acceptor (D–M–A) type complexes of ruthenium(II) with the highly absorbing “chromophoric” ligand 4,4′-bis(2-(4-methoxyphenyl)styryl)-2,2′-bipyridine, (L-OCH3, donor moiety) and substituted polypyridinic ligands with electron acceptor character (NN-A). The NN-A studied ligands were pyrazino[2,3-f][1,10]phenanthroline (ppl), 11-R-dipyrido[2,3-a:2′,3′-c]phenazine (dppz-R; R is H, NO2, or CN) and 10,11-[1,4-naphtalenedione]dipyrido[3,2-a:2′,3′-c]phenazine (Aqphen). The complexes were characterized by IR, NMR, UV–Vis spectroscopy and cyclic voltammetry. The potential NLO response of the complexes was evaluated by solvatochromic studies. Although the communication between D and A exists, the effect of the change of the acceptor moiety on the properties of the complexes is small and the behavior of the complexes is governed mainly by the donor ligand. The Metal to Ligand Charge Transfer bands (MLCT) exhibited by all complexes in the visible region have dominant electronic density transfer character from the metal to the chromophoric L-OCH3 ligand. The hypsochromic shift of this low energy absorption band on going from a less polar (benzene) to a more polar solvent (acetonitrile) indicated that a redistribution of the electronic density among the metal and the donor ligand is observed. This behavior permits to predict a NLO response for these types of complexes. The combination of high molar absorptivity with intraligand charge transfer (ILCT) mixing into the MLCT bands are encouraging for the generation of new materials with interesting NLO properties.

Materials of New Generation in Nuclear Power Industry

The results providing advantages of thorium-232 as a reproducing nuclide in comparison with uranium-238 as a part of nuclear fuel of new generation reactors are presented. The explanation of the effects which were found earlier in numerical simulation of parameters of open thorium - plutonium nuclear fuel cycle is offered. Scientific and technical solutions allow considering the possibility of including thorium-232 in the fuel of nuclear reactors, which are based on existing design solutions, and beginning the design of new generation materials: a new generation of fuel rods and fuel assemblies, where the isotope uranium-238 will be completely replaced with thorium-232.