GMR in Ni/Cu multilayers: an electronic structure study

Ab initio self-consistent semi-relativistic spin-polarized TB-LMTO energy band calculations have been carried out on Ni/Cu(100) multilayers, to study the in-plane as well as perpendicular to plane giant magnetoresistance (GMR) effects. The magnetic interaction energies, evaluated as a function of layer thickness, indicate that the antiferromagnetic ordering is a possible ground state for manifestation of GMR. Using the density of states at Fermi level and the Fermi velocity, GMR has been estimated as a function of the Cu spacer thickness.     

Object‐oriented wrappers for the Linux kernel

Linux is an open‐source operating system, which has increased in its popularity and size since its birth. Various studies have been conducted in literature on the evolution of the Linux kernel, which have shown that there are considerable maintenance problems arising out of the coupling issues in the Linux kernel and this may hamper the evolution of the kernel in future. We propose an object‐oriented (OO) wrapper‐based approach to Linux kernel to provide OO abstractions to external modules. As the major growth of the size of the Linux kernel is in device drivers, our approach provides substantial benefits in terms of developing the device drivers in C++, although the kernel is in C. Providing reusability and extensibility features to device drivers improves the maintainability of the kernel. The OO wrappers provide several benefits to module developers in terms of understandability, development ease, support for OO modules, etc. The design and implementation of C++ wrappers for Linux kernel and the performance of a device driver re‐engineered in C++ are presented in this paper. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and characterization of aniline-doped mixed copolymer resins. II

Copolymer resins were synthesized by the mixed condensation of resorcinol–CH₂O, resorcinol–aniline–CH₂O, resorcinol–aniline–thiourea–CH₂O, and resorcinol–aniline–urea–thiourea–CH₂O with a view to develop synthetic resins having improved properties and performance like toughness, mechanical properties, thermal resistance, chemical inertness, and adhesion. The resins were characterized by IR and TG analyses. The thermal analysis showed that the mixed copolymer resins have significantly better thermal stability than that of the simple phenol–CH₂O, aniline–CH₂O, urea–CH₂O, and thiourea–CH₂O resins. At 600°C, only a 50% weight loss is observed, and even at 800°C, the weight loss is about 70%. The resins are insoluble in most of the organic solvents including DMSO-d₆. They too are unaffected by diluted HNO₃, but dissolve in concentrated HNO₃. © 1996 John Wiley & Sons, Inc.     

Isolierung und Charakterisierung der Endospermproteine des Weizens: Ein Beitrag zur Erkl?rung der Kleberbildung

Zusammenfassung Mit Hilfe der Sedimentationstechnik gelingt es, einen Teil des Endospermproteins in etwa 95% iger Reinheit als sog. Freies Protein zu isolieren. Der wasserlösliche Anteil beträgt bis zu 50% und besteht aus Proteinen und Polypeptiden mit Molekulargewichten ab 700; sie zeigen im Disk-Elektropherogramm etwa 12 Banden.Andererseits wird ein Teil des Endospermproteins als Stärkekornprotein abgetrennt, dessen Träger die Stärkekörner sind. Der wasserlösliche Anteil beträgt bis zu 40%, jedoch sind hier Substanzen mit Molekulargewichten unter 700 zu finden. Stärkekornprotein ist säulenchromato-graphisch am Kationenaustauscher in mindestens 20 Komponenten differenzierbar. Freies Protein kann also nicht identisch sein mit Stärkekornprotein, was darüber hinaus auch die Aminosäurenanalyse und die Bestimmung der SH-Gruppen und der Disulfidbindungen bestätigt. Stärkekornprotein besitzt gegenüber Freiem Protein einen auffallend hohen Anteil an SH-Gruppen.Die löslichen Eiweißkomponenten des Freien Proteins und die des Stärkekornproteins setzen sich im Sinne einer Fällungsreaktion um. Nur geringe Anteile des Stärkekornproteins genügen, um mehr als 50% des löslichen Freien Proteins auszufällen. Diese Reaktion läuft ab, wenn Weizenmehl mit Wasser behandelt wird (z. B. beim Kneten), läßt sich aber auch beim Zusammengeben wäßriger Extrakte aus Freiem Protein und Stärkekornprotein zeigen. Durch Säulenchromatographie und PAA-Elektrophorese ist nachgewiesen worden, daß dabei nur bestimmte Protein-komponenten beteiligt sind. Der entstehende Niederschlag besitzt kleberähnliche Eigenschaften; seine Aminosäurenzusammensetzung ähnelt der des Freien Proteins und der des Klebers.

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Isolation and characterization of endosperm protein of wheat: A contribution to the formation of gluten.

Summary It is possible to isolate part of the endosperm protein as so-called free protein in a highly pure form (95% protein content) by a modified sedimentation technique of Hess. The water solubility amounts to about 50% and the extract contains proteins and polypeptides of molecular weights 700 onwards. About twelve electrophoresis bands have been observed.On the other hand using the same technique, part of the endosperm protein can be separated as starch granule protein, which adheres to the starch granules. The water solubility of the adhering nitrogen containing substances amounts to about 40%. The molecular weight of these soluble substances lies below 700. They could be differentiated by column chromatography on cation exchange resin and separated in at least 20 components.Hence the free protein and the starch granule protein cannot be identical substances. Beyond that the amino acid analysis and the determination of SH-groups and disulfide bonds show obvious differences between them. The starch granule protein contains more sulfhydryl groups than the free protein.By adding only little portions of water soluble starch granule protein to a solution of free protein, more than 50% of the latter can be precipitated (protein precipitate). The same reaction also takes place when wheat flour is mixed with water (dough mixing). This result can be supported by column chromatography and discelectrophoresis by which it has been shown that only definite components of the water soluble free protein take part in this reaction. The isolated protein precipitate shows the properties of gluten. In addition to that the amino acid composition is very similar to that of free protein and gluten.

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Diese Arbeit wurde mit finanzieller Unterstützung des Bundesministers für Wirtschaft und Finanzen, über den Forschungskreis der Ernährungsindustrie e. V., Hannover, durchgeführt, wofür wir an dieser Stelle unseren Dank aussprechen.

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ab 1. 1. 1972: 8 München 23, Leopoldstraße 175     

Processable aromatic polyesters based on bisphenol derived from cashew nut shell liquid: synthesis and characterization

The miscibility of chitosan/poly(ethylene oxide) (CS/PEO) blends was investigated by a combination of experiment and molecular simulation. Results from X-ray diffraction (WAXD) and thermal analysis (DSC) suggest that the maximum miscibility was seen at the PEO weight fraction (w _PEO) =0.2; the optimum stoichiometric ratio for CS and PEO functional groups. The change in vibrational frequencies from infrared spectra was attributed to the specific interaction between PEO ether oxygen with the amino and hydroxyl groups of CS. Radial distribution functions (RDF) from MD simulation suggest that all CS functional groups (NH₂, C3-OH, and C6-OH) can interact with PEO ether groups for which NH₂ has the highest activity. For CS hydroxyl groups, a more significant contribution of C6-OH rather than C3-OH groups that interact with PEO ether oxygen was observed. The interaction parameter (χ) determined from MD simulation was in good agreement with that of the DSC experiment (χ_CS-PEO?=?-0.21). Based on a comparison between χ and χ _critical , CS/PEO blend was predicted to be miscible for w _PEO <0.58 with a maximum at w _PEO =0.2. In addition, the order parameter from the mesoscale simulation was employed to monitor the phase separation in these blends. From MesoDyn simulation, the miscibility was decreased with increasing PEO content, and miscible CS/PEO blends were obtained only with w _PEO <0.58, in good agreement with MD simulation and experiment.     

Rapid biological synthesis of silver nanoparticles using Kalopanax pictus plant extract and their antimicrobial activity

Silver nanoparticles (AgNPs) have promising potential in biomedicine, energy science, optics, and health care applications. We synthesized AgNPs using plant, Kalopanax pictus leaf extract. UV-visible spectrophotometric study showed the characteristic peak for AgNPs at wavelength 430 nm. The optical density at 430 nm increased after addition of plant leaf extract, indicating increase in formation of nanoparticles. Comparative time course analyses for AgNP synthesis carried out at different reaction temperatures (20, 60, and 90 °C) revealed higher reaction rate for K. pictus than Magnolia kobus plant leaf extract, which showed highest AgNP synthesis rate in the previous report. Electron microscopy analyses confirmed the presence of well dispersed AgNPs, predominantly with spherical shapes. In transmission electron microscopy, the particle size decreased with increase in temperature. Electron dispersive X-ray spectroscopy analyses indicated that Ag content increased with increase in reaction temperature. Fourier transform-infrared spectroscopy studies revealed capping of bioorganics from plant to the synthesized AgNPs. The antimicrobial activity of the synthesized AgNPs against Escherichia coli increased with increase in reaction temperature. The observations in this study will prove beneficial in approaching rapid synthesis of AgNPs and their antimicrobial application.     

Lignocellulosic and marine biomass as resource for production of polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs) are considered as sustainable ‘green/bio plastics’ because they have potential to replace their depleting petroleum-based competitors in the recent future. To reach this goal, PHAs must be able to compete with the established petroleum-based plastics in both technical and economic aspects. The current PHA production is based on high-priced substrates of high nutritional value and simple carbon sources such as glucose, sucrose, starch, or vegetable oils. Non-food based carbon-rich complex polysaccharides of lignocellulosic and marine biomass can be used as alternative and suitable feedstock through consolidated bioprocessing (CBP). CBP is a promising strategy that involves the production of lytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products in a single process step. CBP offers very large cost reductions if microorganisms possessing the abilities are found or microbial processes are developed to utilize substrate and simultaneously produce products. This review focuses on possible available complex polysaccharides of lignocellulosic and marine biomass that can be used as resources to produce PHAs in biorefineries, including CBP.     

Growth of n-type γ-CuCl with improved carrier concentration by pulsed DC sputtering: Structural, electronic and UV emission properties

γ Copper (I) chloride is naturally a direct band gap, zincblende and p-type semiconductor material with much potential in linear and non-linear optical applications owing to its large free excitonic binding energy. In order to fabricate an efficient electrically pumped emitter, a combination of both p-type and n-type semiconductor materials will be required. In this study, we report on the growth of n-type γ-CuCl with improved carrier concentration by pulsed DC magnetron sputtering of CuCl/Zn target. An improvement of carrier concentration up to an order of ~ 9.8 × 10¹⁸ cm^− 3, which is much higher than the previously reported (~ 10¹⁶ cm^− 3), has been achieved. An enhancement in crystallinity of CuCl along the (111) orientation and its consistency with the morphological studies have also been investigated as an effect of doping. Influence of Zn wt.% in the sputtering target on the Hall mobility and resistivity of the doped films is explored. The strong ultraviolet emission of doped films is confirmed using room temperature and low temperature photoluminescence studies.     

Effect of grain hardness on bioavailability of iron in wheat as determined using the coupled invitro digestion/Caco-2 model

The impact of grain hardness on iron bioavailability from a set of wheat genotypes with varying hardness indices was determined. This may help us to consider grain hardness as an important parameter along with other established parameters for selecting food crops for future biofortification programs to combat iron deficiency linked to global health problem. The bioavailability and dialysability of iron were determined using the coupled in vitro digestion/Caco-2 model. The grain hardness and its molecular basis along with grain iron, phytate and inorganic phosphorous (Pi) contents were also evaluated. The data indicated that iron concentration in the genotypes ranged from 21 to 50 μg/g of dry matter. The hardness indices varied from as low as 28 for the derivative BTC17 to as high as 92 for the landrace IITR 26, almost similar to that of WL711, a wild type cultivar considered as control in this study. Low variability was however observed for the phytate and Pi contents. A significant negative correlation was observed between grain hardness vs. dialysability (r = −0.73) and bioavailability (r = −0.75) of iron. The results suggest that the hardness index which profoundly affects milling process, particle size of flour, milling yield and end-use also influences dialysability and bioavailability of iron from wheat.