bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural changes in the alveolar cells of rats injected with Cerastes cerastes cerastes venom
Authors: Fares Nagui Hassan , El‐Aal A. Abd 
Published: June 2010

AbstractUltrastructural changes in the alveolar tissue of rats intraperitoneally injected with the Cerastes cerastes cerastes venom were studied in 2 different experimental groups. In the first group, each rat was given 0.73 mg/Kg as a single dose and sacrificed after 24 hours. In the second group, each rat was given a daily dose of 0.42 mg/Kg for 7 days and sacrificed 24 hours after the last injection. Proliferative changes were seen in type II alveolar cells, fibroblasts, lymphocytes, and macrophages. Type II alveolar cells of the lungs developed a large number of surfactant granules. In the 24‐hour‐envenomated rats, type I alveolar cells displayed swollen nuclei and masses of dilated endoplasmic reticulum. In the 7‐day‐treated rats, several plasma cells, adjacent interstitial cells as well as alveolar brush cells, with their characteristic short microvilli, were detected. Large masses of collagen and elastic fibers were also located in the vicinity of the alveolar brush cells and type II alveolar cells. These histopathological changes may be attributed to the body‐immune response and possibly to the development of hyperplasia due to venom‐induced trauma. Nat. Toxins 5:208–221, 1997. © 1998 Wiley‐Liss, Inc.
Perforated Sheets Exhibiting Negative Poisson's Ratios
Authors: Grima Joseph N. , Gatt Ruben 
Published: June 2010

AbstractSheets made from readily available conventional materials containing diamond or star shaped perforations are shown to exhibit various Poisson's ratio values which could also be negative (auxetic). This behavior may be exhibited in both tension and compression and can be explained through models based on “rotating rigid units.” This provides an easy manner for the manufacture of auxetic or conventional systems at any scale which can be tailor made to exhibit particular values of the Poisson's ratio.
Microstructural Analysis of the Reinforced Al‐Cu5mgti/Tib2 5 wt % Alloy for Investment Casting Applications
Authors: Egizabal Pedro , García de Cortazar Maider , Douin Joël , Torregaray Amaia , Lahaye Michel , Vincent Cécil , Silvain Jean‐Frangois 
Published: June 2010

AbstractThe paper describes the influence of 5 wt % titanium diboride (TiB2) particles on the microstructure of an Al‐Cu alloy produced by plaster casting process. The elaboration route leads to a composite material with 1% of in situ TiB2 particles and 4% ex situ of TiB2 particles. The comparison of the reinforced alloy with the corresponding non‐reinforced counterpart makes clear that the presence of TiB2 particles has a large influence in the observed microstructure. The presence of TiB2 particles decreases the grain sizes and the porosity level. It is also found that TiB2 particles play an important role in the precipitation events of Al2Cu precipitates that are formed during solidification at the TiB2/aluminum matrix interfaces.
Multilayer Amorphous‐Si‐B‐C‐N/γ‐Al2O3/α‐Al2O3 Membranes for Hydrogen Purification
Authors: Prasad Ravi Mohan , Iwamoto Yuji , Riedel Ralf , Gurlo Aleksander 
Published: June 2010

AbstractThe hydrogen and carbon monoxide separation is an important step in the hydrogen production process. If H2 can be selectively removed from the product side during hydrogen production in membrane reactors, then it would be possible to achieve complete CO conversion in a single‐step under high temperature conditions. In the present work, the multilayer amorphous‐Si‐B‐C‐N/γ‐Al2O3/α‐Al2O3 membranes with gradient porosity have been realized and assessed with respect to the thermal stability, geometry of pore space and H2/CO permeance. The α‐Al2O3 support has a bimodal pore‐size distribution of about 0.64 and 0.045 µm being macroporous and the intermediate γ‐Al2O3 layer—deposited from boehmite colloidal dispersion—has an average pore‐size of 8 nm being mesoporous. The results obtained by the N2‐adsorption method indicate a decrease in the volume of micropores—0.35 vs. 0.75 cm3 g−1—and a smaller pore size −6.8 vs. 7.4 Å—in membranes with the intermediate mesoporous γ‐Al2O3 layer if compared to those without. The three times Si‐B‐C‐N coated multilayer membranes show higher H2/CO permselectivities of about 10.5 and the H2 permeance of about 1.05 × 10−8 mol m−2 s−1 Pa−1. If compared to the state of the art of microporous membranes, the multilayer Si‐B‐C‐N/γ‐Al2O3/α‐Al2O3 membranes are appeared to be interesting candidates for hydrogen separation because of their tunable nature and high‐temperature and high‐pressure stability.
Integrated batch‐to‐batch and nonlinear model predictive control for polymorphic transformation in pharmaceutical crystallization
Authors: Hermanto Martin Wijaya , Braatz Richard D. , Chiu Min‐Sen 
Published: June 2010

AbstractPolymorphism, a phenomenon in which a substance can have more than one crystal form, is a frequently encountered phenomenon in pharmaceutical compounds. Different polymorphs can have very different physical properties such as crystal shape, solubility, hardness, color, melting point, and chemical reactivity, so that it is important to ensure consistent production of the desired polymorph. In this study, an integrated batch‐to‐batch and nonlinear model predictive control (B2B‐NMPC) strategy based on a hybrid model is developed for the polymorphic transformation ofL‐glutamic acid from the metastable α‐form to the stable β‐form crystals. The hybrid model comprising of a nominal first‐principles model and a correction factor based on an updated PLS model is used to predict the process variables and final product quality. At each sampling instance during a batch, extended predictive self‐adaptive control (EPSAC) is employed as a NMPC technique to calculate the control action by using the current hybrid model as a predictor. At the end of the batch, the PLS model is updated by utilizing the measurements from the batch and the above procedure is repeated to obtain new control actions for the next batch. In a simulation study using a previously reported model for a polymorphic crystallization with experimentally determined parameters, the proposed B2B‐NMPC control strategy produces better performance, where it satisfies all the state constraints and produces faster and smoother convergence, than the standard batch‐to‐batch strategy. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Mikrotröpfchen in Mikrofluidiksystemen: eine Technik für Entdeckungen in der Chemie und Biologie
Authors: Theberge Ashleigh B. , Courtois Fabienne , Schaerli Yolanda , Fischlechner Martin , Abell Chris , Hollfelder Florian , Huck Wilhelm T. S. 
Published: June 2010

AbstractMikrotröpfchen in Mikrofluidiksystemen bieten zahlreiche Möglichkeiten für die chemische und biologische Forschung. Sie ermöglichen die isolierte Betrachtung von Spezies oder Reaktionen, sie sind monodispers und daher für quantitative Studien geeignet, sie können für Studien in extrem kleinen Volumina sowie an einzelnen Zellen oder einzelnen Molekülen eingesetzt werden, und sie sind für Hochdurchsatzexperimente geeignet. Dieser Aufsatz analysiert die Bedeutung dieser Eigenschaften im Hinblick auf neue biologische und chemische Experimente, wobei jüngste Fortschritte bei der Entwicklung von Apparaturen vorgestellt, aber auch verbleibende technologische Herausforderungen angesprochen werden. Anhand von Beispielen wird gezeigt, welche Vorteile die Kompartimentierung, die Monodispersität der Tröpfchen, die Betrachtung einzelner Moleküle und der hohe Durchsatz in Experimenten gebracht haben, die ohne den Einsatz von Mikrofluidiksystemen kaum möglich gewesen wären.
Ab Initio Thermochemistry of Solid‐State Materials
Authors: Stoffel Ralf Peter , Wessel Claudia , Lumey Marck‐Willem , Dronskowski Richard 
Published: June 2010

AbstractIn this contribution we introduce an electronic‐structure‐theory‐based approach to a quantum‐chemical thermochemistry of solids. We first deal with local and collective atomic displacements and explain how to calculate these. The fundamental importance of the phonons, their dispersion relations, their experimental determination as well as their calculation is elucidated, followed by the systematic construction of the thermodynamic potentials on this basis. Subsequently, we provide an introduction for practical computation as well as a critical analysis of the level of accuracy obtainable. We then show how different solid‐state chemistry problems can be solved using this approach. Among these are the calculation of activation energies in perovskite‐like oxides, but we also consider the use of theoretical vibrational frequencies for determining crystal structures. The pressure and temperature polymorphism of elemental tin which has often been classically described is also treated, and we energetically classify the metastable oxynitrides of tantalum. We also demonstrate, using the case of high‐temperature superconductors, that such calculations may be used for an independent evaluation of thermochemical data of unsatisfactory accuracy. Finally, we show the present limits and the future challenges of the theory.
Crystallization and melting behavior of HDPE in HDPE/teak wood flour composites and their correlation with mechanical properties
Authors: Sewda Kamini , Maiti S. N. 
Published: June 2010

AbstractThe nonisothermal crystallization behavior and melting characteristics of high‐density polyethylene (HDPE) in HDPE/teak wood flour (TWF) composites have been studied by differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) methods. Composite formulations of HDPE/TWF were prepared by varying the volume fraction (ϕf) of TWF (filler) from 0 to 0.32. Various crystallization parameters evaluated from the DSC exotherms were used to study the nonisothermal crystallization behavior. The melting temperature (Tm) and crystallization temperature (Tp) of the composites were slightly higher than those of the neat HDPE. The enthalpy of melting and crystallization (%) decrease with increase in the filler content. Because the nonpolar polymer HDPE and polar TWF are incompatible, to enhance the phase interaction maleic anhydride grafted HDPE (HDPE‐g‐MAH) was used as a coupling agent. A shift in the crystallization and melting peak temperatures toward the higher temperature side and broadening of the crystallization peak (increased crystallite size distribution) were observed whereas crystallinity of HDPE declines with increase in ϕf in both DSC and WAXD. Linear correlations were obtained between crystallization parameters and tensile and impact strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and characterization of complex gel of type I collagen and aluminosilicate containing imogolite nanofibers
Authors: Nakano Asuka , Teramoto Naozumi , Chen Guoping , Miura Yoshiko , Shibata Mitsuhiro 
Published: June 2010

AbstractComplex gel materials of Type I collagen and aluminosilicate containing imogolite nanofibers were prepared as opaque gel by mixing an acidic fine dispersion of aluminosilicate with an acidic solution of collagen. The product was stained blue by Coomassie Brilliant Blue (CBB), indicating that the gel contained collagen. A white sponge was obtained after lyophilization of the complex gel. Elemental analysis revealed that the complex contains C, H, N, Al, and Si atoms; and the compositional ratio of aluminosilicate/collagen (w/w) was calculated as 0.75 for the complex gel when aluminosilicate was mixed with an equal quantity of collagen. Transmission electron microscope (TEM) observation showed that aluminosilicate nanofibers were homogeneously distributed in the collagen matrix. The thermogravimetric analysis (TGA) curve of the complex was not a simple summation of each components, and especially, the weight loss step corresponding to detachment of the adsorbed water observed in aluminosilicate became difficult to distinguish, suggesting that the adsorbed water was removed in the complexation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A morphological view of the sodium 4,4′‐distyrylbiphenyl sulfonate fluorescent brightness distribution on regenerated cellulose fibers
Authors: Iamazaki Eduardo T. , Pereira‐Da‐Silva Marcelo A. , Carvalho Antonio J. F. , Romero Rafaelle B. , Gonçalves Maria C. , Atvars Teresa D. Z. 
Published: June 2010

AbstractEvidence of the sorption of the whitening agent sodium 4,4′‐distyrylbiphenyl sulfonate in the presence of the anionic surfactant sodium dodecylsulfate or the cationic surfactant dodecyl trimethyl ammonium chloride on regenerated cellulose fibers is given by several microscopy techniques. Scanning electron microscopy provided images of the cylindrical fibers with dimensions of 3.5 cm (length) and 13.3 μm (thickness), with empty cores of 1 μm diameter and a smooth surface. Atomic force microscopy showed a fiber surface with disoriented nanometric domains using both tapping‐mode height and phase image modes. Atomic force microscopy also showed that the whitening agent and surfactant molecules were sorbed onto the fiber surface, in agreement with the adsolubilization sorption model. Transmission electron microscopy showed fibers with nanometric parallel cylinders, surrounded by holes where the fluorescent whitening molecules accumulated. On the basis of these techniques, we conclude that the sorption process occurs preferentially on the fiber surface in contact with the water solution, and under saturated conditions, the whitening agent penetrates into the pores and are simultaneously sorbed on the pore walls bulk, forming molecular aggregates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Morphological study on the reactivity of styrene‐divinylbenzene copolymers in a chloromethylation reaction
Authors: Teixeira Viviane G. , Coutinho Fernanda M. B. 
Published: June 2010

AbstractStyrene‐divinylbenzene (S‐DVB) copolymers with different kinds of porous structures were synthesized by aqueous suspension polymerization using n‐heptane as the pore forming agent. The amount of this solvent (monomer dilution degree) and the DVB content in the organic phase were varied. The combination of three different dilution degree values and three DVB contents yielded three series of copolymers with a variety of porous structures. The three series were composed by copolymers with pore diameters (D) in the following ranges: D < 500 Å, 500 < D < 1000 Å, and D > 1000 Å, respectively. The effect of synthesis conditions on the pore size distribution and on the copolymer matrix rigidity was evaluated. These copolymers were submitted to a chloromethylation reaction with a paraformaldehyde/gaseous HCl mixture in the presence of zinc chloride as a Lewis acid catalyst and 1,2‐dichloroethane as solvent. The effect of the copolymer porosity on the chloromethylation reaction extension was evaluated. It was possible to observe that a gel copolymer with a high swelling capacity in the reaction medium achieved the same chloromethylation yield observed for a high porous copolymer. This result thus indicates that, in the case of the chloromethylation reaction studied here, the high swelling capacity of the gel copolymer can counterbalance its limited surface area, turning this type of polymer structure as reactive as a macroporous one. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Development of colorimetric analytical methods to monitor quaternary amine grafted surfaces
Authors: Ozer Ruya R. , Hill W. Cary , Rogers Martin E. , Evans Mishell 
Published: June 2010

AbstractQuick and simple colorimetric analytical techniques were developed to monitor functionalization of surfaces with quaternary amine bearing polymers as complementary qualitative tests to the traditionally used antimicrobial test protocols. First, an established antimicrobial quaternary ammonium salt (QAS) was chosen as a probe compound and an acrylol functional group was introduced (acrylol‐QAS) to facilitate its polymerization with acrylic monomers. Surface graft polymerization was carried out with methyl methacrylate (MMA) and acrylol‐QAS on cotton fabric surface. The success of graft polymerization, durability after repetitive aqueous extraction, and the effect of crosslinking agents on the durability and extent of polymerization were tested with a fluorescein spot and a bromophenol solution test. The results of these colorimetric analytical methods were in perfect agreement with those of antimicrobial tests, XPS, and SEM analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Properties of poly(ethylene glycol)‐based bioelastomers
Authors: Tao Ding , Yuanqing Xu , Huang Gu , Yurong Liang , Xiaomin Fang , Liqun Zhang 
Published: June 2010

AbstractIn this article, a series of poly(ether ester) bioelastomers, poly(PEG‐co‐CA)s (PECs), were synthesized by the melt polycondensation of citric acid (CA) and poly(ethylene glycol) (PEG) with molecular weights of 150, 200, 300, and 400. The measurements of the mechanical properties of the PEC series testified that these polymers were elastomers with a low hardness and high elongation, and the hydrolytic degradation of polymer films in a buffer of pH 7.4 at 37°C showed that the PECs had excellent degradability. The molecular weight of PEG had a strong influence on the degradation rates, water absorption rates, and mechanical performance of the PECs. The materials are expected to be useful for pressure hemostasis implementation in lacuna and other biomedical applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and properties of poly(urethane acrylate) films for ultraviolet‐curable coatings
Authors: Seo Jongchul , Jang Eui‐Sung , Song Jin‐Han , Choi Seunghyuk , Khan Sher Bahadar , Han Haksoo 
Published: June 2010

AbstractFour different UV‐curable poly(urethane acrylate)s were prepared through the reaction of two diisocyanates [i.e., toluene‐2,4‐diisocyanate (TDI) and isophorone diisocyanate (IPDI)] and two polyols [i.e., polycaprolactone triol (PCLT) and polycaprolactone diol (PCLD)], and they were characterized with Fourier transform infrared spectroscopy. The mechanical properties, thermal properties, and water sorption of the cured poly(urethane acrylate)s were also investigated with respect to the chemical structures of the polyols and diisocyanates. In comparison with linear PCLD–TDI and PCLD–IPDI, crosslinked PCLT–TDI and PCLT–IPDI with trifunctional PCLT showed relatively high thermal decomposition temperatures. The hardness and modulus of the UV‐cured poly(urethane acrylate) films, which were measured by a nanoindentation technique, were in the following increasing order: PCLD–IPDI ∼ PCLD–TDI < PCLT–IPDI ∼ PCLT–TDI. The pencil hardness was 3H for PCLT–IPDI and PCLT–TDI and HB for PCLD–IPDI and PCLD–TDI. Two urethane acrylates prepared from the trifunctional polyol showed better acid and alkali resistances than those made from the bifunctional polyol. These mechanical properties and chemical resistances may have been strongly dependent on the chain flexibility of the molecules and crosslinking density. Regardless of the functionality in the polyol, the change in the yellowness index showed a lower value in the poly(urethane acrylate) coating containing the aliphatic diisocyanate IPDI in comparison with the corresponding poly(urethane acrylate) with the aromatic diisocyanate TDI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of the organoclay preparation on the extent of intercalation/exfoliation and barrier properties of polyethylene/PA6/montmorillonite nanocomposites
Authors: Erdmann Eleonora , Acosta Delicia , Pita Victor J. R. R. , Monasterio Fernanda E. , Carrera María C. , Dias Marcos L. , Destéfanis Hugo A. 
Published: June 2010

AbstractNanocomposites of HDPE matrix and 3 wt % organoclay/PA6 discontinuous phase were prepared in a mixer chamber. These nanocomposites of organoclay, PA6, and HDPE were characterized by X‐ray diffraction, scanning electron and transmission electron microscopy (SEM and TEM). Barrier properties were determined by cyclohexane pervaporation and solubility. The results show that the degree of exfoliation and/or intercalation and the barrier properties depend on a combination of the proper chemical treatment and optimized processing in these polyethylene‐organoclays nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A new adaptive PI for bicarbonate regulation in an anaerobic digestion process
Authors: Carlos‐Hernandez Salvador 
Published: June 2010

AbstractThis paper deals with the design and validation via numerical simulations of an adaptive proportional integral (PI) controller for bicarbonate regulation in an anaerobic wastewater treatment process. The proportional and integral gains are deduced as a function of the parameters of an approximate dynamical model. First, a brief explanation of the control structure is introduced. After that, a general equation of an adaptive PI controller is proposed. Next, the controller is implemented in order to regulate bicarbonate by two control actions in a completely stirred tank reactor (CSTR): adding a base and manipulating the dilution rate. Finally, a smooth switching mechanism which allows the process to operate in open or closed loop according to the operating conditions is implemented. The performance of the process with the proposed control scheme is validated via simulations. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Conformational dynamics of active site loop in Escherichia coli phytase
Authors: Shivange Amol V. , Schwaneberg Ulrich , Roccatano Danilo 
Published: June 2010

AbstractPhytases catalyze the release of phosphate by stepwise hydrolysis of phytate, a major source of phosphate in cereal grains, legumes, and oilseeds. Phytase improves, as a feed supplement, the nutritional quality of phytate rich diets and eventually reduce environmental pollution. Recently, phytases from enterobacteriaceae family have attracted industrial interest due to their high specific activity (2500–4000 U/mg). However, only limited information is available concerning structural dynamics of this class of enzymes. In this study, 50 nanosecond molecular dynamics simulation was performed on two Escherichia coli phytase structures (closed and open active site loop) to investigate conformational dynamics of the active site loop. Cluster analysis and principal component analysis (PCA) reveal significant difference in the conformational dynamics of active site compared to reported crystal structure. Molecular dynamic studies indicated that the movement in the active site of E. coli phytase is mainly confined by the active site loop resulted in wider opening of the loop in absence of phytate. The molecular dynamics studies highlight the possible role of loop residues as prerequisite for highly active phytases. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 994–1002, 2010.
Gase als zelluläre Signalstoffe. Gasotransmitter
Authors: Hermann Anton , Sitdikova Guzel F. , Weiger Thomas M. 
Published: June 2010

AbstractDie Gase Stickoxid (NO), Kohlenmonoxid (CO) und Schwefelwasserstoff (H2S) werden aufgrund ihrer Wirkung als Signalstoffe als “Gasotransmitter” zusammengefasst. Diese Gase spielen eine wichtige Rolle als intra‐ und interzellulärer Signalstoff im Verdauungs‐, Atmungs‐ oder Urogenitalsystem, bei der Steuerung des Herzschlags oder Nervenaktivitäten. Die Forschung ist dabei, Funktionen und weitere Details der Wirkmechanismen dieser Gase und ihre Implikationen für Physiologie, Pathophysiologie und Pharmakologie zu erarbeiten. Vom bisher neuesten Kandidaten – dem H2S – gibt es Hinweise, dass er in hoher Konzentration im Gehirn und in den Hoden vorkommt und bei Lern‐/Gedächtnisprozessen sowie bei Geschlechtsfunktionen eine Rolle spielt. Durch Entwicklung von Wirksubstanzen zur Beeinflussung der H2S‐Produktion oder entsprechender Zielorte könnte sich hieraus ein interessantes pharmakologisches Potenzial entwickeln.