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In this study, the modification of leather surface by application of TiO2-SiO2-GLYMO (3-Glycidyloxypropyltrimethoxysilane) nanocomposite coating and plasma treatment with N2 gas activation is investigated by using Small and Wide Angle X-ray scattering methods. The protective properties were tried to be developed with TEOS and HMDSO polymers’ usage in the coating process by following and controlling nano scale structural changes. The main aim was the controls of nanoscaled surface modifications and determination of the best coating process by keeping natural structure of the leathers. These scattering methods were useful to investigate the coating effects on the PTLs (Plasma Treated Leathers)’ internal structures including collagen microfibers and nanofibers which are hierarchical structures of triple helix collagen. The main purpose of the work was investigate whether the structural change in the natural form of the leather is present or not in the molecular-nanoscopic and microscopic scales after the coating and the applied physico-bio-chemical processes. On the other hand, the successful protective coatings and surface modifications were determined with SAXS analyses by controlling the shape, size and distance distributions of the appeared nanoglobular aggregations. The observations of structural changes taking place within collagen fibrils as a result of surface modification provides new insight into the nature of finishing and informs future processing developments. © 2020, © 2020 Taylor & Francis.

Exopolysaccharide producing starter cultures enable manufacturing “clean labeled” foods with improved textural and nutritional properties. The structural and technological analyses were performed on the ropy exopolysaccharides of six Lactobacillus plantarum. The incubation temperature, time and pH affected the exopolysaccharide production and high exopolysaccharide was produced in the presence of sucrose and maltose. The viscosity of exopolysaccharide was high at acidic conditions except PFC311E that showed viscous at neutral pH. Lactobacillus plantarum strains produced between 120 and 400 mg/L exopolysaccharide in which the highest was observed at L. plantarum PFC311. Exoploysaccharides were degraded over 300 °C except PFC311E that degraded at 295.7 °C. The NMR analyses revealed that the exopolysaccharides were synthesized by ?1-6, ?1-3 and ?1-4 bonds with glucose, galactose and fructose moieties. In conclusion, L. plantarum PFC311 produced ropy exopolysaccharide with different structural, rheological and thermal properties and reveals potential to be used in food industry. © 2019, The Korean Society of Food Science and Technology. 1160525 The Scientific and Technogical Research Council of Turkey (TÜBİTAK) supported this study with the Project number 1160525. We also thank to Prof. Dr. Nazım Usta for giving opportunities to do the thermal analysis of EPSs and also interpreting the results.

A nanoporous metal–organic framework material, exhibiting an IRMOF-1 type crystalline structure, was prepared by following a direct solvothermal synthesis approach, using zinc nitrate and terephthalic acid as precursors and dimethylformamide as solvent, combined with supercritical CO2 activation and vacuum outgassing procedures. A series of advanced characterization methods were employed, including scanning electron microscopy, Fourier-transform infrared radiation spectroscopy and X-ray diffraction, in order to study the morphology, surface chemistry and structure of the IRMOF-1 material directly upon its synthesis. Porosity properties, such as Brunauer–Emmet–Teller (BET) specific area (∼520 m2/g) and micropore volume (∼0.2 cm3/g), were calculated for the activated sample based on N2 gas sorption data collected at 77 K. The H2 storage performance was preliminary assessed by low-pressure (0–1 bar) H2 gas adsorption and desorption measurements at 77 K. The activated IRMOF-1 material of this study demonstrated a fully reversible H2 sorption behavior combined with an adequate gravimetric H2 uptake relative to its BET specific area, thus achieving a value of ∼1 wt.% under close-to-atmospheric pressure conditions. © 2017 Hydrogen Energy Publications LLC 42 23899 23907 23899-23907

L1521E is a dense starless core in Taurus that was found to have relatively low molecular depletion by earlier studies, thus suggesting a recent formation. We aim to characterize the chemical structure of L1521E and compare it to the more evolved L1544 pre-stellar core. We have obtained $\sim$2.5$\times$2.5 arcminute maps toward L1521E using the IRAM-30m telescope in transitions of various species. We derived abundances for the species and compared them to those obtained toward L1544. We estimated CO depletion factors. Similarly to L1544, $c$-C$_3$H$_2$ and CH$_3$OH peak at different positions. Most species peak toward the $c$-C$_3$H$_2$ peak. The CO depletion factor derived toward the $Herschel$ dust peak is 4.3$\pm$1.6, which is about a factor of three lower than that toward L1544. The abundances of sulfur-bearing molecules are higher toward L1521E than toward L1544 by factors of $\sim$2-20. The abundance of methanol is similar toward the two cores. The higher abundances of sulfur-bearing species toward L1521E than toward L1544 suggest that significant sulfur depletion takes place during the dynamical evolution of dense cores, from the starless to pre-stellar stage. The CO depletion factor measured toward L1521E suggests that CO is more depleted than previously found. Similar CH$_3$OH abundances between L1521E and L1544 hint that methanol is forming at specific physical conditions in Taurus, characterized by densities of a few $\times$10$^4$ cm$^{-3}$ and $N$(H$_2$)$\gtrsim$10$^{22}$ cm$^{-2}$, when CO starts to catastrophically freeze-out, while water can still be significantly photodissociated, so that the surfaces of dust grains become rich in solid CO and CH$_3$OH, as already found toward L1544. Methanol can thus provide selective crucial information about the transition region between dense cores and the surrounding parent cloud., Comment: Accepted for publication in A&A, abstract abridged

In the invited article, we review observations on changes in meteorite texture relevant to the early stages of formation of the Solar System based on the experimental shock wave loading of the material at the laboratory. Investigation of the physical and structural properties of high-pressure impacts on meteorites is important for few reasons, such as: Protection of the Earth from the near-Earth objects (NEOs); Study of processes that cannot yet be achieved under laboratory conditions; Understanding of conditions for asteroid mining. © 2019 IUPAC & De Gruyter. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. For more information, please visit: http://creativecommons.org/licenses/by-nc-nd/4.0/2019.

A spherical geometry shock experiment with the light-colored lithology material of the Chelyabinsk LL5 ordinary chondrite was carried out. The material was affected by shock and thermal metamorphism whose grade ranged from initial stage S3-4 to complete melting. The temperature and pressure were estimated at >2000°С and >90 GPa. The textural shock effects were studied by optical and electron microscopy. A single experimental impact has produced the whole the range of shock pressures and temperatures and, correspondingly, four zones identified by petrographic analysis: (1) a melt zone, (2) a zone of melting silicates, (3) a black ring zone, and (4) a zone of weakly shocked initial material. The following textural features of the material were identified: displacement of the metal and troilite phases from the central melt zone; the development of a zone of mixed lithology (light-colored fragments in silicate melt); the origin of a dark-colored lithology ring; and the generation of radiating shock veinlets. The experimental sample shows four textural zones that correspond to the different lithology types of the Chelyabinsk LL5 meteorite found in fragments of the meteoritic shower in the collection at the Ural Federal University. Our results prove that shock wave loading experiment can be successfully applied in modeling of space shocks and can be used to experimentally model processes at the small bodies of the solar system. © 2019, Pleiades Publishing, Ltd.

This work focused on the synthesis of new tertiary amines by varying the alkyl chain length with/without hydroxyl group in the structure. The effect of chemical structure of newly synthesized tertiary amines; 4-(dimethylamino)-2-butanol (DMAB), 4-(dipropylamino)-2-butanol (DPAB), 4-(dibutylamino)-2-butanol (DBAB), 4-((2-hydroxyethyl)(methyl)amino)-2-butanol (HEMAB) and 4-((2-hydroxyethyl)(ethyl)amino)-2-butanol (HEEAB) were evaluated based on CO2 equilibrium solubility and cyclic capacity, as well as rates and heats of CO2 absorption and regeneration. The results showed that three amines (i.e. DMAB, HEMAB and HEEAB) had the highest CO2 absorption capacity (0.88, 0.44 and 0.68 mol CO2/mol amine at 313 K temperature and 15 kPa CO2 partial pressure), and cyclic capacity (0.52, 0.26 and 0.40 at 313-353 K temperature range, 15 kPa CO2 partial pressure). These amines also had fast CO2 absorption rate (0.082, 0.111 and 0.142 mol CO2/min) and CO2 regeneration rate (0.512, 0.452 and 0.295 mol CO2/min) while maintaining low heat of CO2 absorption (-34.17, -56.21 and -69.79 kJ/mol CO2) and heat input of CO2 regeneration (39.73, 60.48 and 72.44 kJ/mol CO2). Based on these results, DMAB, HEMAB, and HEEAB can be considered to be promising amine components for blending for a post combustion CO2 capture process. 2016 Elsevier B.V. All rights reserved. The financial support from Overseas Research Experience Scholarship for Graduate Students , Graduate School at Chulalongkorn University is acknowledged. Supports from Clean Energy Technologies Research Institute - CETRI (previously known as International Test Center for CO 2 Capture - ITC) at the University of Regina are gratefully acknowledged for providing research facilities throughout this work. In addition, our team would also like to acknowledge the financial support in parts of this work provided by an NPRP Grant # 7-1154-2-433 from the Qatar National Research Fund (a member of Qatar Foundation). Scopus

The influence of crystalline microstructure and molecular topology on the strain-induced fibrillar transformation of semi-crystalline polyethylenes having various chemical structures including co-unit content and molecular weight and crystallized under various thermal treatments was studied by in situ SAXS at different draw temperatures. The long period of the nascent microfibrils, Lpf, proved to be strongly dependent on the draw temperature but non-sensitive to the initial crystallization conditions. Lpf was smaller than the initial long period. Both findings have been ascribed to the strain-induced melting-recrystallization process as generally claimed in the literature. The microfibrils diameter, Df, was shown to depend on the draw temperature and initial microstructure in a different way as Lpf. The evolution of Df was shown to correlate with the interfacial layer thickness that mainly depends on the chemical structure of the chains. It was concluded that, in contrast to Lpf, the microfibril diameter should not be directly sensitive to the strain-induced melting-recrystallization. The proposed scenario is that after the generation of the protofibrils by fragmentation of the crystalline lamellae at yielding, the diameter of the microfibril during the course of their stabilization should be governed by the chain-unfolding and subsequent aggregation of the unfolded chains onto the lateral surface of the microfibrils. The morphogenesis of the microfibrils should therefore essentially depend on the chemical structure of the polymer that governs its crystallization ability, its chain topology and subsequently its fragmentation process at yielding. This scenario is summed up in a sketch.

The microwave spectrum of the molecular complex of acetonitrile (CH3CN) with water (H2O) has been studied with a pulsed-beam Fourier Transform Microwave Spectrometer (FTMW) from a gas sample of 1% by volume of CH3CN in Ar flowed over a water sample. The frequency coverage was about 9-22 GHz for various isotopomers. The CH3CN-H2O complex exhibited a symmetric top spectrum for two tunneling components, whereby the water subunit tunnels between two equivalent forms. The molecular structure was determined with the aid of spectral studies of isotopically substituted monomers containing 13C, 15N and 18O and mono- and di-deuterated water. In the process of measuring the 13CH3CN-H2O species, we observed some nearby transitions for the Ar-13CH3CN complex. Since the molecular structure of the Ar complex in the literature was not completely determined, we also measured several isotopomers of it to improve the molecular structure. The rotational analyses provide the rotational, centrifugal distortion and nuclear quadrupole coupling constants for all of the isotopomers analyzed. � 2015, Academic Press Inc. All rights reserved.

A series of Pt/Ce x Zr 1-x O 2-δ (x = 0.4–0.6) solids were synthesized and evaluated for the SCR of NO under lean burn conditions (2.5 vol% O 2 ) using C 3 H 6 and H 2 as reducing agents. SSITKA-Mass Spectrometry, SSITKA-DRIFTS and other in situ DRIFTS experiments were conducted for the first time to gather fundamental information in explaining the remarkable H 2 /C 3 H 6 synergy effect towards steady-state selective reduction of NO into N 2 at T > 400 °C. In particular, the chemical structure of adsorbed active and inactive (spectator) NO x species formed under C 3 H 6 -SCR, H 2 -SCR and H 2 /C 3 H 6 -SCR of NO and the surface coverage and site formation of active NO x were probed. The Pt/Ce 1-x Zr x O 2-δ catalysts present significant differences in their H 2 -SCR performance (NO conversion and N 2 -selectivity) in the low-temperature range of 120–180 °C but practically the same catalytic behavior at higher temperatures. It was proved that the active NO x of the H 2 -SCR path reside within a reactive zone around each Pt nanoparticle which extends to less than one lattice constant within the support surface. The chemical structure of the active intermediate was proved to be the chelating nitrite , whereas nitrosyl, monodentate and bidentate nitrates were considered as inactive species (spectators). It was illustrated for the first time that the presence of 15 vol% H 2 O in the H 2 -SCR feed stream applied over the 0.1 wt% Pt/Ce 0.5 Zr 0.5 O 2 catalyst results in a 25% decrease in the concentration of active NO x , thus partly explaining the drop in activity observed when compared to the H 2 -SCR in the absence of H 2 O. A remarkable activity and N 2 -selectivity enhancement was observed at T > 400 °C when both H 2 and C 3 H 6 reducing agents were used compared to H 2 -SCR or C 3 H 6 -SCR alone. This synergy effect was explained to arise mainly because of the increase of θ Η by the presence of –CH x species derived from adsorbed propylene decomposition on Pt, which block sites of oxygen chemisorption, and of the increase of surface oxygen vacant sites that promote the formation of a more active chelating nitrite (NO 2 − ) species compared to the case of H 2 -SCR.

The structure of the surface polysaccharide from a hypervirulent for mice Acinetobacter baumannii strain LAC-4 was studied. The polysaccharide was built of trisaccharide repeating units containing α-l-fucosamine, α-d-glucosamine, and α-8-epi-legionaminic acid. The structure interpretation was based mostly on NMR data. Polysaccharide was obtained using a procedure of LPS O-chain preparation, although whether it is an LPS O-chain or capsular polysaccharide remained unclear. © 2014 Published by Elsevier Ltd. All rights reserved.

The microstructure and composition of diffusion layers that arise upon the spread of the liquid aluminum alloys AL5, AL9, AL852, and A7075 over the St3 steel has been investigated using optical and electron microscopy. The thermophysical conditions of the interaction of the melt with the substrate under which at the boundary of the substrate the plastic transition layer of iron-based solid solution improving quality of the coating is formed have been determined. © 2013 Pleiades Publishing, Ltd.

Carbapenem resistant Klebsiella pneumoniae (CRKP) are isolated with increasing frequency, especially from immunocompromized patients. The capsular polysaccharide (CPS) types of CPKP were not determined. Investigation of two CRKP isolates from a 2011 outbreak at the Clinical Center, the National Institutes of Health, identified a new capsular type shared by the two isolates, similar to K. pneumonia K19 and K34 but structurally different than any published K. pneumoniae CPS repeating unit: The LPS of the two isolates was found to have no O-specific polysaccharide and the chemical structure of the core oligosaccharides agreed with the published data. If this structure type will be prevalent among CPKP isolates, our findings could facilitate rapid diagnosis and help to develop new therapeutic solutions to this antibiotic resistant pathogen. © 2013 Elsevier Inc. All rights reserved.

The structure of Ge20SbxSe80-x (x = 5, 15, 20) glasses was investigated by neutron diffraction, X-ray diffraction, and extended X-ray fine structure measurements at the Ge, Sb, and Se K -edges. For each composition, large-scale structural models were obtained by fitting simultaneously the experimental data sets in the framework of the reverse Monte Carlo simulation technique. It was found that the structures of these glasses can be described mostly by the chemically ordered network model. Ge Se and Sb Se bonds are preferred; Se Se bonds in the Se -poor composition (x = 20) and M M (M = Ge, Sb) bonds in strongly Se -rich glass (x = 5) are not needed. The quality of the fits was significantly improved by introducing Ge Ge bonding, in the nearly stoichiometric composition (x = 15), showing a violation of chemical ordering. The structure of Ge(20)Sh(x)Se(80), was compared to that of several glasses from the three analogous systems. (Ge-As Se-Ge As-Te, Ge-Sb-Te), and, it was found that chemical short-range order becomes more pronounced upon substituting As with Sb and Se with Te. Ge As Se glasses behave as random covalent networks over a very broad composition range. Chemical short-range order and disorder coexist in both Te-rich and Te-poor Ge As Te glasses, whereas amorphous Ge14Sb29Te57 and Ge22Sb22Te56 are governed by strict chemical preferences.

IR and RS spectroscopy are used to study the effect of substituting barium and calcium for the sodium cation on the structure of sodium borosilicate glass with the composition 0.25Na 2 O; 0.25B 2O 3; 0.5SiO 2. Analysis of the recorded spectra showed that the substitution of the alkali-metal cations Ba 2+ and Ca 2+ for the Na+ cation results in breaking of B-O-B and Si-O-Si bridges, as a result of which the fraction of oxygen end atoms increases and the degree of polymerization of the glass decreases. © 2011 Springer Science+Business Media, Inc.

Organically-modified montmorillonite clay nanocomposites of poly(styrene-co-acrylonitrile) (SAN), poly(methyl methacrylate) (PMMA) and SAN/PMMA miscible blend are investigated. Structure characteristics at the nanoscale and microscale and thermal and tensile properties are studied as a function of polymer blend composition and filler loading fraction. Blend miscibility and Tg are unaffected by up to 10% by wt. organoclay. Thermal degradation stability increases with SAN content and exhibits an optimum value of clay loading. Stiffness shows significant improvement. Tensile strength and elongation-at-break suffer as a result of nanocomposite formation. Modulus shows a maximum enhancement of 57% (5 ± 0.06 GPa at 10 wt% filler, 20/80 SAN/PMMA) and varies linearly with clay fraction for all compositions of matrix phase. Predictions of Halpin–Tsai composite model are in excellent agreement with the experimental behavior over full range of polymer blend composition. Fundamental aspects of a polymer blend–clay nanocomposite are clarified, such as lack of additional synergy between clay platelets and matrix, and tensile ductility reduction, compared with polymer–clay system. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

This paper describes a versatile, and simple synthetic route for the preparation of a range of reduced graphene oxide (RGO)-metal/metal oxide composites and their application in water purification. The inherent reduction ability of RGO has been utilized to produce the composite structure from the respective precursor ions. Various spectroscopic and microscopic techniques were employed to characterize the as-synthesized composites. The data reveal that the RGO-composites are formed through a redox-like reaction between RGO and the metal precursor. RGO is progressively oxidized primarily to graphene oxide (GO) and the formed metal nanoparticles are anchored onto the carbon sheets. Metal ion scavenging applications of RGO-MnO2 and RGO-Ag were demonstrated by taking Hg(II) as the model pollutant. RGO and the composites give a high distribution coefficient (Kd), greater than 10Lg-1 for Hg(II) uptake. The Kd values for the composites are found to be about an order of magnitude higher compared to parent RGO and GO for this application. A methodology was developed to immobilize RGO-composites on river sand (RS) using chitosan as the binder. The as-supported composites are found to be efficient adsorbent candidates for field application. � 2010 Elsevier B.V.

cited By 3; International audience; Adsorption properties of gram-scale samples of different kind of arc discharge nanotubes were studied, namely: (A) raw collaret collected on the cathode, (B) raw soots collected on the lateral reactor wall, (C) thermally treated soot, and (D) thermally then chemically treated soot. The morphology, structure, and composition of these materials were characterized by SEM, TEM, TGA, and BET. In addition, hydrogen adsorption isotherms were recorded experimentally for A, B, and D samples over the pressure range of 0 to 55 bar at ambient temperature. Our experiments indicated a maximum - yet weak - hydrogen storage at room temperature of ∼0.13 H 2 wt% for the purified product (D). Copyright © 2007 American Scientific Publishers All rights reserved.

Differential scanning calorimetry (DSC) coupled with X-ray diffraction (XRD) and transmission electron microscopy (TEM) is used to elucidate the structural and phase transformation behaviour of electroless Ni-P and Ni-W-P alloys. Synthesis of the coatings was done using acidic electroless bath. The coatings were annealed at 300 and 600 �C for 1 h. X-ray diffraction pattern of all the coatings indicate presence of either amorphous or both amorphous and crystalline phases coexisting. The lattice disorder in the crystalline phases decreased with increasing tungsten content in the deposit. The grain size in the as-deposited crystalline deposit was found to vary from 5 to 40 nm. Annealing the coatings at 300 �C did not produce any appreciable change in grain size. But, annealing at 600 �C increased the grain size to 500 nm. � 2007 Elsevier B.V. All rights reserved.

A study to determine the structure and activity relationships of various amine based CO2 absorbents was performed in which, the absorption of pure CO2 at atmospheric pressure was measured to assess the total absorption rate and capacities. Results showed that an increase in chain length between the amine and different functional groups in the absorbent structure, result in a decrease of absorption rate whereas, the absorption capacity was increased in most absorbents.

cited By 11; International audience; The optical properties of small Cu-Ag bimetallic clusters have been experimentally and theoretically investigated in relation to their chemical structure analyzed by high resolution transmission electron microscopy (HRTEM). Cu (1-x)Agx clusters of about 5 nm in diameter are produced in a laser vaporization source with a well-defined stoichiometry (x = 0, 25, 50, 75, and 100%) and dispersed in an alumina matrix. Absorption spectra are dominated by a broad and strong surface plasmon resonance whose shape and location are dependent on both cluster composition and sample aging. Detailed modeling and systematic calculations of the optical response of pure and oxidized mixed clusters of various chemical structures have been carried out in the framework of classical and semiquantal formalisms. Optical and HRTEM measurements combined with theoretical predictions lead to the conclusion that these bimetallic clusters are not alloyed at the atomic scale but rather present a segregation of chemical phases. Most likely, they adopt a Cu@Ag core-shell configuration. Moreover, the nanoparticle oxidation process is consistent with the formation of a copper oxide layer by dragging out inner copper atoms to the cluster surface. © 2015 American Chemical Society.

Tantalum oxynitride thin films were produced by magnetron sputtering. The films were deposited usinga pure Ta target and a working atmosphere with a constant N2/O2ratio. The choice of this constant ratiolimits the study concerning the influence of each reactive gas, but allows a deeper understanding of theaspects related to the affinity of Ta to the non-metallic elements and it is economically advantageous.This work begins by analysing the data obtained directly from the film deposition stage, followed bythe analysis of the morphology, composition and structure. For a better understanding regarding theinfluence of the deposition parameters, the analyses are presented by using the following criterion: thefilms were divided into two sets, one of them produced with grounded substrate holder and the otherwith a polarization of −50 V. Each one of these sets was produced with different partial pressure of thereactive gases P(N2+ O2). All the films exhibited a O/N ratio higher than the N/O ratio in the depositionchamber atmosphere. In the case of the films produced with grounded substrate holder, a strong increaseof the O content is observed, associated to the strong decrease of the N content, when P(N2+ O2) is higherthan 0.13 Pa. The higher Ta affinity for O strongly influences the structural evolution of the films. Grazingincidence X-ray diffraction showed that the lower partial pressure films were crystalline, while X-rayreflectivity studies found out that the density of the films depended on the deposition conditions: thehigher the gas pressure, the lower the density. Firstly, a dominant -Ta structure is observed, for lowP(N2+ O2); secondly a fcc-Ta(N,O) structure, for intermediate P(N2+ O2); thirdly, the films are amorphousfor the highest partial pressures. The comparison of the characteristics of both sets of produced TaNxOyfilms are explained, with detail, in the text., This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2013. This paper was also supported by the Sectoral Operational Programme Human Resources Development (SOPHRD), ID134378 financed from the European Social Fund and by the Romanian Government.

Copper particles were incorporated and retained in elemental state in an aluminium matrix by friction stir processing thereby producing a non-equilibrium particulate composite. The processed Al-Cup composite exhibited improved strength with significantly high ductility. The composite was stable up to a temperature of more than 300uC. Thermal exposure at 350uC for more than 10 min led to diffusion of Cu atoms into the Al matrix forming a core-shell type structure in the Cu particles and thus producing an Al-Cu core-shell composite. The shell consists of multiple layers, the thickness of which was controllable. � 2015 Institute of Materials, Minerals and Mining

The formation of electrodeposited Ni-B alloy coatings using a dimethylamine borane (DMAB) modified Watt's nickel bath and evaluation of their structural characteristics, hardness and wear resistance are discussed. The boron content in the electrodeposited Ni-B alloy coating is determined by the ratio of rate of reduction of nickel and rate of decomposition of DMAB. The boron content of the electrodeposited Ni-B coating decreases as the current density increased from 0.4 to 4 A dm-2. XRD diffraction pattern of electrodeposited Ni-B coatings in their as-plated condition exhibits the presence of Ni (1 1 1), (2 0 0) and (2 2 0) reflections with (1 1 1) texture. Heat treatment at 400 �C for 1 h has resulted in the formation of nickel boride phases, which results in an increase in hardness and wear resistance. The mechanism of wear in electrodeposited Ni-B coatings is intensive plastic deformation of the coating due to the ploughing action of the hard counter disk. � 2005 Elsevier B.V. All rights reserved.

The present work aims to study the hardness and wear resistance of electroless Ni-B coatings. An alkaline bath having nickel chloride as the source of nickel and borohydride as the reducing agent was used to prepare the electroless Ni-B coatings. The structure, microhardness and wear resistance of electroless Ni-B coatings, both in as-plated and heat-treated conditions, were evaluated using X-ray diffraction (XRD), Leitz microhardness tester and a pin-on-disc wear test apparatus. XRD patterns reveal that electroless Ni-B coatings are amorphous in as-plated condition and undergo phase transformation to crystalline nickel and nickel borides upon heat-treatment. The microhardness of the electroless Ni-B coatings increases with increase in heat-treatment temperature and exhibit two maxima in the hardness vs. heat-treatment temperature curve. The specific wear rate increases with increase in applied load from 20 to 40 N and at all applied loads, the specific wear rate and coefficient of friction are less for heat-treated electroless Ni-B deposits compared to that obtained for as-plated ones. The wear process of electroless Ni-B coatings is governed by an adhesive wear mechanism. ? 2004 Elsevier B.V. All rights reserved.

This review article summarizes the last few decades of research on nickel hydroxide, an important material in physics and chemistry, that has many applications in engineering including, significantly, batteries. First, the structures of the two known polymorphs, denoted asα-Ni(OH)2andβ-Ni(OH)2, are described. The various types of disorder, which are frequently present in nickel hydroxide materials, are discussed including hydration, stacking fault disorder, mechanical stresses and the incorporation of ionic impurities. Several related materials are discussed, including intercalatedα-derivatives and basic nickel salts. Next, a number of methods to prepare, or synthesize, nickel hydroxides are summarized, including chemical precipitation, electrochemical precipitation, sol–gel synthesis, chemical ageing, hydrothermal and solvothermal synthesis, electrochemical oxidation, microwave-assisted synthesis, and sonochemical methods. Finally, the known physical properties of the nickel hydroxides are reviewed, including their magnetic, vibrational, optical, electrical and mechanical properties. The last section in this paper is intended to serve as a summary of both the potentially useful properties of these materials and the methods for the identification and characterization of ‘unknown’ nickel hydroxide-based samples.

Lactobacillus helveticus is traditionally used in dairy industry as a starter or an adjunct culture for manufacture of cheese and some types of fermented milk. Its autolysis releases intracellular enzymes which is a prerequisite for optimum cheese maturation, and is known to be strain dependent. Autolysis is caused by an enzymatic hydrolysis of the cell wall peptidoglycan (PG) by endogenous peptidoglycan hydrolases (PGHs) or autolysins. Origins of differences in autolytic properties of different strains are not fully elucidated. Regulation of autolysis possibly depends on the structure of the cell wall components other than PG, particularly polysaccharides. In the present work, we screened six L. helveticus strains with different autolytic properties: DPC4571, BROI and LH1. We established, for the first time, that cell walls (CWs) of these strains contained polysaccharides, different from their CW teichoic acids. Cell wall polysaccharides of three strains were purified, and their chemical structures were established by 2D NMR spectroscopy and methylation analysis. The structures of their repeating units are presented. © 2013 Elsevier Ltd.

International audience; Endotoxins are lipopolysaccharides (LPS), and major constituents of the outer membrane of Gram-negative bacteria. Bordetella pertussis LPS were the only major antigens, of this agent of whooping-cough, that were not yet analyzed on isolates from the pre- and post-vaccination era. We compared here the LPS structures of four clinical isolates with that of the vaccine strain BP 1414. All physico-chemical analyses, including SDS-PAGE, TLC, and different MALDI mass spectrometry approaches were convergent. They helped demonstrating that, on the contrary to some other B. pertussis major antigens, no modification occurred in the dodecasaccharide core structure, as well as in the whole LPS molecules. These results are rendering these major antigens good potential vaccine components. Molecular modeling of this conserved LPS structure also confirmed the conclusions of previous experiments leading to the production of anti-LPS monoclonal antibodies and defining the main epitopes of these major antigens.

Elucidation of the carbohydrate backbone structure of the lipopolysaccharide (LPS) from Piscirickettsia salmonis, the etiological agent of the salmonid rickettsial septicemia, is described. Structural information was established by a combination of monosaccharide and methylation analyses of LPS, and by NMR and mass spectrometries of oligosaccharides obtained through the use of various chemical degradations of the native polymer. The following structure of the backbone sugars was determined on the basis of the combined data from these experiments: Figure options Download full-size image Download as PowerPoint slide The presence of two consecutive residues of diacetylated pseudaminic acid (Pse5,7Ac, 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid) in the LPS appears to be unique among polysaccharides containing this acidic sugar. Similarly, the presence of 4-aminoarabinose (Ara4N, 4-amino-4-deoxy-l-arabinopyranose) on O-4 of the α-GlcN1P of the lipid A moiety is a unique feature of this LPS.

The structure and light-emitting properties of Si nanowires (SiNWs) fabricated by a single-step metal-assisted chemical etching (MACE) process on highly boron-doped Si were investigated after different chemical treatments. The Si nanowires that result from the etching of a highly doped p-type Si wafer by MACE are fully porous, and as a result, they show intense photoluminescence (PL) at room temperature, the characteristics of which depend on the surface passivation of the Si nanocrystals composing the nanowires. SiNWs with a hydrogen-terminated nanostructured surface resulting from a chemical treatment with a hydrofluoric acid (HF) solution show red PL, the maximum of which is blueshifted when the samples are further chemically oxidized in a piranha solution. This blueshift of PL is attributed to localized states at the Si/SiO2 interface at the shell of Si nanocrystals composing the porous SiNWs, which induce an important pinning of the electronic bandgap of the Si material and are involved in the recombination mechanism. After a sequence of HF/piranha/HF treatment, the SiNWs are almost fully dissolved in the chemical solution, which is indicative of their fully porous structure, verified also by transmission electron microscopy investigations. It was also found that a continuous porous Si layer is formed underneath the SiNWs during the MACE process, the thickness of which increases with the increase of etching time. This supports the idea that porous Si formation precedes nanowire formation. The origin of this effect is the increased etching rate at sites with high dopant concentration in the highly doped Si material.

IR spectroscopy was used to study the behavior of water in model glasses of the systems Na2O-B2O3-SiO2 and K2O-B2O3-SiO2. It was determined that hydroxyl groups and water in molecular form are present in such alkali borosilicate glasses obtained by quenching water-bearing melt. The water distribution between its forms and silicate and borate components of the glass structure depends on their chemical composition. Proton-cation exchange with the participation of non-bridge oxygen atoms and coordinated alkali-metal ions is involved in the process leading to the formation of hydroxyl groups. © 2013 Springer Science+Business Media New York.

Brucella is an animal and human pathogen that expresses several virulence factors required for host cell invasion and intracellular survival. It produces LPS with unusually low toxicity, which hampers the detection of bacteria by the host immune system and thus provides resistance against intracellular antimicrobial mechanisms of the host. By chemical and spectroscopic methods we determined the structure of the LPS core and of a non-repetitive oligosaccharide fragment at the reducing end of the O-specific polysaccharide. These data should be useful for understanding the biological role of the Brucella LPS. Crown Copyright © 2012 Published by Elsevier Ltd. All rights reserved.

Electroless nickel-phosphorus (EN) deposits with and without addition of surfactants were made on mild steel substrates. Two surfactants namely sodium dodecylsulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) were used in the study. The EN coated samples were characterised using X-ray diffraction analysis and transmission electron microscopy. The XRD pattern of all the deposits indicated the presence of crystalline and amorphous phases coexisting in the as deposited condition. Profile refinement techniques have been used to separate the crystalline nickel (111) reflection from the amorphous profile. The crystallite size of nickel was found to vary from 200 nm in the as deposited condition to 80 nm with addition of surfactant. TEM study reveals a nano crystalline structure of the deposit in as plated condition and an amorphous structure with addition of surfactants. With addition of surfactants adhesion was good. The coating thickness varied from 12.7 ?m to 32.2 ?m with addition surfactants. Copyright � 2012 Inderscience Enterprises Ltd.

A wide compositional range of Ni-Pd alloy catalysts were prepared by electrodeposition for use as anode materials for methanol oxidative fuel cells in alkaline conditions. Structural characterization of the electrocatalysts in their as-plated condition revealed that the Ni-Pd catalysts synthesized were nanocrystalline, single phase, face centered cubic materials, indicating the formation of complete solid solution in the alloy. Compositional analysis of the alloys indicated that the palladium composition of the alloy increased with decrease in current density. This change in the composition of the alloy resulted in a shift in the X-ray diffraction peaks. The percentage shift in the d-spacing calculated from X-ray diffraction is in good agreement with percentage of palladium in the alloy. The electrocatalysts prepared are active for methanol oxidation in alkaline medium. � 2007 Elsevier B.V. All rights reserved.

The much desired ? (bcc) Tantalum (Ta) thin films are grown at room temperature using a newly designed cylindrical magnetron cathode (with rotating magnets geometry) with pulsing power. The new design has facilitated oblique incidence of adatoms. The electron temperature of the plasma has been enhanced due to the pulsing frequency (100�kHz). These two factors: oblique incidence of adatoms and enhanced electron temperature are presumed to be responsible for the formation of ? phase Ta thin films at room temperature. The volume fractions of ? and ? phases have been evaluated from the X-ray data. The effect of pulsing (0-100�kHz) on the structural, electrical and mechanical properties of Ta thin films has also been studied. With the pulsing frequency, the lattice spacing in the Ta thin films increases (due to the incorporated argon) resulting in an increase in the compressive stress. Up to 75�kHz of the pulsing frequency, the Ta films formed are in the ? phase (tetragonal) with ~ 13�nm grain size. At 100�kHz pulsing, the change in the surface morphology also indicates the phase change in the film. � 2008 Elsevier B.V. All rights reserved.

The mechanism of formation and the stability of spontaneously formed vesicles upon self-assembly of a partially ground-state charge-separated, nonpolar-polar-nonpolar fullerene(C60)-didodecyloxybenzene (DDB) dyad in binary solvent mixtures requiring a critical dielectric constant of ?30 are reported. Molecular interactions giving rise to defined vesicles with in-plane bilayer packing are detailed from the predominant van der Waals and electrostatic interactions existing on the dyad's framework. The vesicles are formed with a large bending rigidity of 18kBT, which on further extraction into a polar water medium resulted in uniform spheres that corroborated well with the theoretical predictions. Furthermore, the water-extracted spherical dyad aggregates at an increased dyad concentration, leading to the formation of giant micrometer-sized fractals following diffusion-limited cluster aggregation. These dyad aggregates act as efficient quenchers of fluorescent dyes with a quenching rate of 4.6 � 10 13 M-1 s-1. � 2007 American Chemical Society.

A mathematical model developed previously is used to obtain equations for the calculation of the standard enthalpies of formation of some stoichiometric oxides and complex oxides of a variable composition in the Fe-O-Ti system. These entropies have been determined. © Nauka/Interperiodica 2007.

Results of modeling the HNF flame structure are presented. From an analysis of literature data on the thermal decomposition and combustion of HNF, it is concluded that the dissociative vaporization of HNF proceeds via the route HNFliq → (N2H4)g + (HC(NO 2)3)g. The flame structure is modeled using a detailed kinetic mechanism consisting of 47 species and 283 elementary reactions. Its constituents are the decomposition mechanisms of hydrazine (N2H4)g and trinitromethane (HC(NO 2)3)g (nitroform, NFg). The latter come from the burning surface by dissociative vaporization. The modeling was performed for different routes of NFg decomposition involving HC(NO2)2, HCNO2, and HC(O)NO2 radicals. The HNF flame structure was calculated for pressures of 0.4, 1, and 5 atm using data on the product composition on the burning surface that correspond to the developed reaction in the condensed phase and are consistent with the chemical composition and enthalpy of formation of HNF. As follows from the calculations, the heat release in the gas-phase reaction of nitroform with hydrazine (and partially with ammonia) leads to a temperature increase in the flame zone adjacent to the burning surface from its value on the surface to ≈1300 K. A further increase in the flame temperature is related to the reaction in the H2O/N2/N2O/NH 3/NO/NO2/HNO2/CO/CO2/HCNO/HCN mixture. The calculation results are compared with experimental data on the thermal and chemical structure of the HNF flame. © Springer Science+Business Media, Inc. 2006.

[reaction: see text] Ketyl radicals with lignin related structures have been generated by means of radiation chemical and photochemical techniques. In the former studies ketyl radicals are produced by reaction of alpha-carbonyl-beta-aryl ether lignin models with the solvated electron produced by pulse radiolysis of an aqueous solution at pH 6.0. The UV-vis spectra of ketyl radicals are characterized by three main absorption bands. The shape and position of these bands slightly change when the spectra are recorded in alkaline solution (pH 11.0) being now assigned to the ketyl radical anions and a pKa = 9.5 is determined for the 1-(3,4,5-trimethoxyphenyl)-2-phenoxyethanol-1-yl radical. Decay rates of ketyl radicals are found to be dose dependent and, at low doses, lie in the range (1.7-2.7) x 10(3) s(-1). In the presence of oxygen a fast decay of the ketyl radicals is observed (k2 = 1.8-2.7 x 10(9) M(-1) s(-1)) that is accompanied by the formation of stable products, i.e., the starting ketones. In the photochemical studies ketyl radicals have been produced by charge-transfer (CT) photoactivation of the electron donor-acceptor salts of methyl viologen (MV2+) with alpha-hydroxy-alpha-phenoxymethyl-aryl acetates. This process leads to the instantaneous formation of the reduced acceptor (methyl viologen radical cation, MV+*), as is clearly shown in a laser flash photolysis experiment by the two absorption bands centered at 390 and 605 nm, and an acyloxyl radical [ArC(CO2*))(OH)CH2(OC6H5)], which undergoes a very fast decarboxylation with formation of the ketyl radicals. Steady-state photoirradiation of the CT ion pairs indicates that 1-aryl-2-phenoxyethanones are formed as primary photoproducts by oxidation of ketyl radicals by MV2+ (under argon) or by molecular oxygen. Small amounts of acetophenones are formed by further photolysis of 1-aryl-2-phenoxyethanones and not by beta-fragmentation of the ketyl radicals. The high reactivity of ketyl radicals with oxygen coupled with the low rates of beta-fragmentation of the same species have an important bearing in the context of the photoyellowing of lignin containing pulps and papers.

In this paper we introduce a mean field method for simulating complex molecular systems like liquids and solutions. Using well-established theoretical principles and models, we obtained a relatively simple approach which seems to provide a reliable description of the bulk molecular behavior of liquid water. Moreover, we have applied this approach to study simple solutes in solution, like sodium and chloride ions and acetone. Comparison with standard simulations, performed with periodic boundary conditions, shows that such a mean field method can reproduce the same structural and thermodynamical properties at low computational costs and represents a valid alternative for simulating solute-solvent systems, like solutions of large biomolecules.

Three new, isostructural methylenediphosphonates of molybdenum, A[MoO2(O3PCH2PO3H)] (A = Rb (1), NH4 (2) and Tl (3)) have been synthesized by hydrothermal method and structurally characterised by X-ray diffraction and spectroscopic techniques. These compounds crystallize in monoclinic space group, P21/c with Z = 4 and consist of [MoO2(O3PCH2PO3H)]- anionic layers interleaved with A+ ions.

Six different metal-ion complexes of D-glucobenzothiazoline were synthesized and characterized by analytical and spectral techniques. Formation of different types of species (ML and ML2) were observed with Cu2+, Ag+, Cd2+, Hg2+, and Zn2+ ions. Existence of an anomeric mixture in the case of the Cu2+ complex is identified from the EPR spectra, and the results were further supported by the simulated spectra. The structures were proposed based on different studies., © Elsevier

Substitution of La3+ in the BaO plane in TlBa2CaCu2O7 system reduces the hole carrier concentration in the CuO2 plane. The system TlBa2−xLaxCaCu2O7 has been synthesised and found to exhibit superconductivity with transition temperature Tc increasing from 80K for x=0.0 and passes through a maximum of 110K for x=0.3. Superconductivity is maintained even at higher substitutional levels (upto x=0.8) in contrast to RE3+ substitution at the Ca2+ site.

Fibrous activated carbons were prepared from Kevlar® (poly (p-phenylene terephthalamide)) and Nomex® (poly (m-phenylene isophthalamide)) by carbonisation in nitrogen and subsequent activation in steam of carbon dioxide to varying burn-off s at 1123 K. The resultant chars were characterised by activation rate studies, scanning electron microscopy and, in the case of the Nomex chars, energy dispersive X-ray analysis. It was found for both the polyarylamide-derived chars that significant differences existed between the chars activated in steam and carbon dioxide. Steam reacts much faster than carbon dioxide with these chars at elevated temperatures. This may be due to its smaller molecular size, resulting in an increase in diffusion and accessibility in and out of the constricted char structure, its higher intrinsic reactivity, or to specific reactions with metallic residues. The catalytic activity of metallic residues, rather than the crystallinity differences between the two polymers, is the suggested reason why Kevlar chars are nearly three times more reactive than Nomex chars. The appearance of the external surfaces of all the chars can be related to the percentage burn-off and the activation gas used. The presence of metallic residues leads to pitting on activation, which increases with progressive burn-off. At high burn-offs, the action of metallic residues in steam and carbon dioxide results in homogeneous and localised surface pits, respectively. © 1995. 33 6 789 793 Cited By :19

A non-contact method of measuring the conductivity of pure and mixed stages of graphite-ferric chloride intercalation compounds has been outlined. This r.f. technique is insensitive to the degree of anisotropy and is found to be well suited to the measurement of in-plane conductivities in quasi-two-dimensional systems. An approximate method of estimating the percentage composition of stages in mixed stages by measuring the conductivity is described.

The alkali metal semiconductor interfaces are currently being investigated by a variety of tools. Most studies to date at half a monolayer coverage have shown preference for either a quasi-hexagonal (H) site or a long-bridge (B) site. At this coverage one-dimensional chain structure for K on Si(001) 2 × 1 have now been confirmed by scanning tunneling microscopy (STM). The data, however, is consistent with either of the two sites. STM investigations at low coverages suggested that alkali metals like K and Cs occupy a novel site, Y, which is a bridge site between two Si atoms belonging to different dimers along the dimer row [110] direction. The total energy calculations for this new Y site, discovered by STM, have shown that it is indeed a site of (local) energy minimum. The ability of the surface silicon atoms, which are not adjacent to the alkali metal atom, to buckle makes the Y site a competitive adsorption site. We deduce the nature of bonding between alkali metals and Si using the STM data. It is concluded that the bond is substantially ionic in nature.