Carbon-based materials applied to the development of chemically modified sensors: Trends to environmental applications**

Nowadays, carbon-based materials applied to the development of chemically modified sensors have been highlighted once they can generate methods with high sensitivity, stability, conductivity, accuracy and low cost. Hence, these sensors have been used in environmental monitoring in aneco-friendlyy, sensitive, fast, efficient, inexpensive and robust way. In this review, firstly we described about carbon-based materials and their derivatives, followed by the chemically modified carbon-based sensors manufacturing overview and their applications in environmental analytical chemistry related to inorganic and organic compounds determinations. Future perspectives on trends of the carbon-based materials applications in the sensor modifications are also described.     

The role of atomic scale investigation in the development of nanoscale materials for information storage applications.

It is well established that the response of devices based on the giant magnetoresistance (GMR) effect depends critically on film microstructure, with parameters such as interfacial abruptness, the roughness and waviness of the layers, and grain size being crucial. Such devices have applications in information storage systems, and are therefore of great technological interest as well as being of fundamental scientific interest. The layers must be studied at high spatial resolution if the microstructural parameters are to be characterized with sufficient detail to enable the effects of fabrication conditions on properties to be understood, and the techniques of high resolution electron microscopy, transmission electron microscopy chemical mapping, and atom probe microanalysis are ideally suited. This article describes the application of these techniques to a range of materials including spin valves, spin tunnel junctions, and GMR multilayers.     

Trends in the development of nucleic acid biosensors for medical diagnostics

Some of the recent advances in the field of biosensors for nucleic acid analysis in medical diagnostic applications are highlighted. Particular attention is paid in this review to the progress made in two key areas of development: (i) enhancements achieved in device selectivity, and (ii) enhancements achieved in device sensitivity.     

Rational design of biomimetic molecularly imprinted materials: theoretical and computational strategies for guiding nanoscale structured polymer development

In principle, molecularly imprinted polymer science and technology provides a means for ready access to nano-structured polymeric materials of predetermined selectivity. The versatility of the technique has brought it to the attention of many working with the development of nanomaterials with biological or biomimetic properties for use as therapeutics or in medical devices. Nonetheless, the further evolution of the field necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. The rapid growth in computer power and software over the past decade has opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers.     

Recent trends in noble-metals based composite materials for supercapacitors: A comprehensive and development review

Supercapacitors are high energy density and power density materials in the electronics industry. Noble metals and their composites have been the most successfully applied in supercapacitors. This review is focused on noble metal-based materials that have been used to improve electrochemical supercapacitors over the last decade. This review describes the role of various noble metals, binary composites with transition metals, binary composites with carbon-based materials, and ternary composites containing both transition metals and carbon-based materials as supercapacitor electrode materials. The effects of the electrode material, growth tactics, structure, size and morphology of the nanostructured materials on device performance are discussed.     

Synthesis and characterization of tin telluride inorganic/organic composite materials with nanoscale periodicity through solution-phase self-assembly: a new class of composite materials based on Zintl cluster self-oligomerization

In this work, we demonstrate the synthesis of semiconducting tin telluride inorganic/organic composite materials with nanoscale periodicity prepared using solution phase self-assembly. Oligomerization of anionic SnTe ₄ ^4? clusters by halogen-mediated tellurium elimination in the presence of surfactant leads to the formation of a meosotructured composite. The composites initially forms as a mixture of mesophases, usually some combination of a layered phase and a phase based on cylindrical building blocks. Post synthetic treatment leads to a solid-state structural change which converts the composites to a single mesophase architecture with a hexagonal honeycomb (p6mm) morphology on the nanometer length scale. A by product of this reaction, however, is bulk tellurium. Changes in the electronic structure of the materials during synthesis and solid-state restructuring are probed using electron spin resonance (ESR) spectroscopy.     

Nitridosilicates and oxonitridosilicates: from ceramic materials to structural and functional diversity

Silicates are one of the most important classes of compounds on this planet, and more than 1000 silicates have been identified in the mineral kingdom. Additionally, several hundreds of artificial silicates have been synthesized. The substitution of oxygen by nitrogen leads to the structurally diverse and manifold class of nitridosilicates. Silicon nitride, one of the most important non-oxidic ceramic materials, is the binary parent compound of nitridosilicates, and it symbolizes the inherent material properties of these refractory compounds. However, prior to the last decades, a broad systematic investigation of nitridosilicates had not been accomplished. In the meantime, these and related compounds have reached a remarkable level of industrial application. This review illustrates recent progress in synthesis and structure-property relationships and also applications of nitridosilicates, oxonitridosilicates, and related SiAlONs.     

Catalytic pyrolysis of propane-butane hydrocarbon mixture on the composite ceramic materials in an open system

Catalytic pyrolysis of propane-butane hydrocarbon mixture on the composite ceramic materials with the surface modified with zinc-, cadmium- phosphorus- and silicon-containing compounds in an open system was studied in the temperature range 500–850°C, at the rate of the gas mixture flow 20–200 ml min⁻¹, contact duration 0.75–155 s, and the values of the heterogeneity factor 2.0 to 2.9×10⁵ cm⁻¹. The catalytic activity of the systems under similar conditions was compared, the influence of various factors on the yield of ethylene and propylene was investigated and the sooting was estimated.     

Mesostructured materials for optical applications: from low-k dielectrics to sensors and lasers

Recent advances on the use of mesoporous and mesostructured materials for electronic and optical applications are reported. The focus is on materials which are processed by block-copolymer templating of silica under weakly acidic conditions and by employing dip- and spin-coating as well as soft lithographic methods to bring them into a well-defined macroscopic shape. Several chemical strategies allow the mesostructure architecture to be used for electronic/optical applications: Removal of the block-copolymers results in highly porous, mechanically and thermally robust materials which are promising candidates for low dielectric constant materials. Since the pores are easily accessible, these structures are also ideal hosts for optical sensors, when suitable are incorporated during synthesis. For example, a fast response optical pH sensor was implemented on this principle. As-synthesized mesostructured silica/block-copolymer composites, on the other hand, are excellently suited as host systems for laser dyes and photochromic molecules. Laser dyes like rhodamine 6G can be incorporated during synthesis in high concentrations with reduced dimerization. This leads to very-low-threshold laser materials which also show a good photostability of the occluded dye. In the case of photochromic molecules, the inorganic-organic nanoseparation enables a fast switching between the colorless and colored form of a spirooxazine molecule, attributed to a partitioning of the dye between the block-copolymer chains. The spectroscopic properties of these dye-doped nanocomposite materials suggest a silica/block-copolymer/dye co-assembly process, whereby the block-copolymers help to highly disperse the organic dye molecules.     

Polymer materials of medical purpose and materials for dentistry

A wide range of polymer materials for medical purposes based on polysiloxane developed at the State Research Institute of Building Structures is presented. The properties of compositions cured by both end hydroxyl groups and the reaction of hydroxylation are considered and examples of their applications are presented.     

Current drawbacks of proton-conducting ceramic materials: How to overcome them for real electrochemical purposes

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Organic-inorganic composite cation-exchanger: poly-o-toluidine Zr(IV) phosphate-based ion-selective membrane electrode for the potentiometric determination of mercury

A new heterogeneous precipitate of an organic-inorganic composite cation-exchanger poly-o-toluidine Zr(IV) phosphate was utilized for the preparation of a Hg(II) ion-sensitive membrane electrode for the determination of Hg(II) ions in real aqueous as well as in real samples. The electrode showed good potentiometric response characteristics, and displayed a linear log[Hg(2+)] versus EMF response over a wide concentration range of 1 x 10(-1) - 1 x 10(-6) M with a Nernstian slope of 30 mV per decade change in concentration with a detection limit of 1 x 10(-6). The membrane electrode showed a very fast response time of 5 s and could be operated well in the pH range 2 - 8. The selectivity coefficients were determined by the mixed-solution method, and revealed that the electrode was selective in the presence of interfering cations; however most of these did not show significant interference in the concentration range of 1 x 10(-1) - 1 x 10(-4) M. The lifetime of the membrane electrode was observed to be 120 days. The analytical utility of this electrode was established by employing it as an indicator electrode in the potentiometric titrations of Hg(2+) ions from a synthetic mixture as well as drain water.     

Characterization of metallic and ceramic high-temperature materials for energy systems

For the development of metallic and ceramic high temperature materials used, for example, in heat exchanger components, in turbine blades for stationary gas turbines, in ceramic industrial products and fusion reactor components, modern physico-chemical characterization methods are required. The formation stability of naturally formed protective scales is of prime importance in the successful application of metallic materials at high temperatures in aggressive atmospheres. For the characterization and investigation of the growth mechanisms of such surface scales, the main emphasis is placed on such modern spectroscopical methods as SIMS, SNMS, GDOS, EPMA and RBS. The morphology and composition of oxide scales have been investigated by imaging and diffraction techniques. The thermal and mechanical damage behaviour of high-temperature materials for application in fusion reactor components is of importance. Damage behaviour has been simulated by electron beam and laser irradiation experiments, especially by means of in situ techniques in a scanning electron microscope. By such techniques the material erosion, crack formation and crack propagation were studied for ceramic high temperature materials as a function of load parameters. The erosion and the crack formation processes are superim-posed by a redeposition of vaporized material and by thermally activated creep of the binder phases. The application potential for all methods discussed is outlined and available results are presented.     

3D printing to innovate biopolymer materials for demanding applications: A review

Biopolymers are widely available, low-/nontoxic, biodegradable, biocompatible, chemically versatile, and inherently functional, making them highly potential for a broad range of applications such as biomedicine, food, textile, and cosmetics. 3D printing (3DP) is capable of fabricating some customized, complex material structures composed of single or multiple material constituents that cannot be achieved by conventional methodologies (e.g. internal structures design); thus, 3DP can greatly expand the application of biopolymer materials. This review presents a comprehensive survey of the latest literature in 3DP technology for materials from biopolymers such as polysaccharides and proteins. The most commonly used 3DP techniques (i.e. inkjet printing, extrusion-based printing, stereolithography, selective laser sintering, and binder jetting) in biomedical and food fields are discussed. Critical factors affecting the quality and accuracy of 3D-printed constructs, including rheological characteristics, printing parameters (e.g. printing rate, and nozzle diameter, movement rate, and height), and post-printing processes (e.g. baking, drying, and crosslinking) are analyzed. The properties and the emerging applications of 3D-printed biopolymer materials in biomedical, food, and even wider applications (e.g. wastewater treatment and sensing) are summarized and evaluated. Finally, challenges and future perspectives are discussed. This review can provide insights into the development of new biopolymer-based inks and new biopolymer-based 3D-printed materials with enhanced properties and functionality.     

Applications of nanoscale carbon-based materials in heavy metal sensing and detection

This article reviews applications of nanoscale carbon-based materials in heavy metal sensing and detection. These materials, including single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers among others, have unique and tunable properties enabling applications in various fields spanning from health, electronics and the environment sector. Specifically, we highlight the unique properties of these materials that enable their applications in the sorption and preconcentration of heavy metals ions prior to detection by spectroscopic, chromatographic and electrochemical techniques. We also discuss their distinct properties that enable them to be used as novel electrode materials in sensing and detection. The fabrication and modification of these electrodes is discussed in detail and their applications in various electrochemical techniques such as voltammetric stripping analysis, potentiometric stripping analysis, field effect transistor-based devices and electrical impedance are critically reviewed. Perspectives and futures trends in the use of these materials in heavy metal sensing and detection will also be highlighted.     

Trends in the science and applications of pectins

The literature on the chemistry and application of pectins is reviewed. The principal themes are the search for nontraditional sources of pectins with novel structural elements and the deeper understanding of the structure and physicochemical properties of well studied pectins from traditional sources (apple, beet, citrus). Custom preparation of pectins with a desired set of properties that have practical application in medicine, biology and the food industry has been demonstrated. Chemical modification of pectins is a promising trend.Institute of Polymer Chemistry and Physics, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (998-71)-144-26-61. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 3–11, January–February, 2000.     

Chemical routes for production of transition-metal phosphides on the nanoscale: implications for advanced magnetic and catalytic materials

Nanoparticulate transition-metal phosphides remain an unexplored, though emerging area of interest on the materials landscape, due principally to their promising magnetic and catalytic properties. This review describes synthetic strategies for the formation of both supported and unsupported transition-metal phosphide nanoparticles, provides a summary of their relevant magnetic and catalytic properties, and indicates new directions for exploration.