bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulatory potential of ellagic acid, a natural plant polyphenol on altered lipid profile and lipid peroxidation status during alcohol‐induced toxicity: A pathohistological study
Authors: Devipriya Nagarajan , Sudheer Adluri Ram , Vishwanathan Periyaswamy , Menon Venugopal Padmanabhan
Published: April 2008

Polyphenol‐rich dietary foodstuffs, consumed as an integral part of vegetables, fruits, and beverages have attracted attention due to their antioxidant and anticancer properties. Ellagic acid (EA), a polyphenolic compound widely distributed in fruits and nuts, has been reported to scavenge free radicals and inhibit lipid peroxidation. Chronic consumption of alcohol potentially results in serious illness including hepatitis, fatty liver, hypertriglyceridemia, and cirrhosis. A little is known about the influence of EA on alcohol toxicity in vivo. Accordingly, in the present study, we have evaluated the protective effects of EA on lipid peroxidation and lipid levels during alcohol‐induced toxicity in experimental rats. Forty female albino Wistar rats, which were weighing between 150–170 g were used for the study. The toxicity was induced by administration of 20% alcohol orally (7.9 g/kg body wt.) for 45 days. Rats were treated with EA at three different doses (30, 60, and 90 mg/kg body wt.) via intragastric intubations together with alcohol. At the end of experimental duration, liver marker enzymes (i.e., aspartate transaminase, alanine transaminase), lipid peroxidative indices (i.e., thiobarbituriacid reactive substances and hydroperoxides) in plasma, and lipid levels (i.e., cholesterol, free fatty acids, triglycerides and phospholipids) in tissues were analyzed to evaluate the antiperoxidative and antilipidemic effects of EA. Liver marker enzymes, lipid peroxidative indices, and lipid levels, i.e., cholesterol, triglycerides and free fatty acids, were significantly increased whereas phospholipid levels were significantly decreased in the alcohol‐administered group. EA treatment resulted in positive modulation of marker enzymes, peroxidative indices, and lipid levels. EA at the dose of 60 mg/kg body wt. was found to be more effective when compared to the other two doses. Histological changes observed were also inconsistent with the biochemical parameters. Our study suggests that EA exerts beneficial effects at the dosage of 60 mg/kg body wt. against alcohol‐induced damage, and it can be used as a potential drug for the treatment of alcohol‐abuse ailments in the near future. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:101–112, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20226
Cloning of an alfalfa polyphenol oxidase gene and evaluation of its potential in preventing postharvest protein degradation
Authors: Sullivan Michael L , Hatfield Ronald D , Samac Deborah A
Published: April 2008

BACKGROUND: Ensiling forages often leads to degradation of protein to non‐protein nitrogen (NPN), which is poorly utilized by ruminants. Postharvest protein degradation is especially high in alfalfa (Medicago sativa L.). In contrast, red clover (Trifolium pratense L.) has up to 90% less protein loss during ensiling due to polyphenol oxidase (PPO) forming o‐quinones from endogenous o‐diphenols and subsequent binding of o‐quinones to cytoplasmic proteins. Here we determined whether an endogenous PPO might be exploited for postharvest protein protection in alfalfa.

RESULTS: We isolated an alfalfa PPO gene (MsPPO1) that shares limited sequence identity (70–72%) with red clover PPO genes. MsPPO1 is expressed primarily in flowers and developing seed pods, but not in leaves or stems. Expression of MsPPO1 from a strong constitutive promoter in transgenic alfalfa results in accumulation of PPO transcripts in leaves, but little enzyme activity is detected using a variety of o‐diphenol substrates unless assayed in the presence of sodium dodecyl sulfate (SDS). Under this SDS‐activated condition, preference of MsPPO1 for tested substrates is catechol ≥ (−)‐epicatechin > caffeic acid. PPO activity in unactivated MsPPO1‐alfalfa extracts is sufficient to inhibit proteolysis in the presence of catechol, but not caffeic acid or (−)‐epicatechin. Inhibition is less than in extracts of alfalfa expressing the red clover PPO1 gene.

CONCLUSION: Endogenous alfalfa PPO, even if expressed in appropriate target tissues, would be less effective at preventing proteolytic losses in ensiled forages than red clover PPO. Published in 2008 by John Wiley & Sons, Ltd.
Poly(ether ester amide) Microspheres for Protein Delivery: Influence of Copolymer Composition on Technological and Biological Properties
Authors: Ostacolo Luisanna , Russo Paola , De Rosa Giuseppe , La Rotonda Maria Immacolata , Maglio Giovanni , Nese Giuseppe , Spagnuolo Gianrico , Rengo Sandro , Oliva Adriana , Quaglia Fabiana
Published: April 2008

The production of PEEA microspheres with potential as carriers for protein oral delivery is described. PEEAs with different hydrophilicity were synthesized and characterized. Experiments showed that an increase in copolymer hydrophilicity gave particles less prone to cell interaction. BSA release profiles from PEEA microspheres demonstrated that an increase in polymer hydrophilicity was useful in limiting protein burst and modulating drug delivery rate by increasing PEEA degradability. These results show that fine‐tuning of the hydrophilic/hydrophobic properties of PCL is essential for the formulation protein‐loaded microspheres with specific properties.

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Novel Triaromatic Ester Mesogenic Liquid Crystalline Epoxy Resin Containing Both Methyl Substituent and Ethoxy Flexible Spacer: Synthesis and Curing
Authors: Liu Guo‐dong , Zhou Bo , Zhao Dong‐mei , Li Qing , Gao Jun‐gang
Published: April 2008

A novel triaromatic ester liquid crystalline epoxy resin (LCER) that contains both a methyl substituent and an ethoxy flexible spacer, p‐methylphenylene di{4‐[(2,3‐epoxypropoxy)ethoxy]benzoate} (MPEPEB), has been synthesized. The mesotropic property has been investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (POM). MPEPEB shows a lower melting temperature at 78.7 °C and a broad nematic mesophase temperature range of about 55 °C. Meanwhile MPEPEB shows a mesophase to −50 °C upon cooling. The curing behavior of MPEPEB with 2,6‐diamino‐3,5‐diethyltoluene (DAE) has been investigated by means of DSC and POM during isothermal and dynamic processes. Although there is little difference between the activation energies obtained from the kinetic data, a marked difference is found between the isothermal and dynamic investigation. The curing reaction in the isothermal investigation roughly obeys n‐th order kinetics, while two exothermal peaks appear in the dynamic DSC curves of MPEPEB/DAE. A comparison of the isothermal and dynamic data shows that the curing rate is not a unique function of temperature and curing degree. The cured networks have lower glass temperatures and show a mesophase at room temperature which disappears at about 86–88 °C.

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Vacuum‐Ultraviolet Photopolymerisation of Amine‐Rich Thin Films
Authors: Truica‐Marasescu Florina , Wertheimer Michael R.
Published: April 2008

Nitrogen‐rich organic thin films were deposited by VUV‐assisted photochemical polymerisation of flowing C2H4/NH3 mixtures. The fundamental reaction mechanisms of these binary gas mixtures were investigated as a function of the wavelength of two almost monochromatic VUV sources. Compositions of these “UV‐PE:N” films close to the surface were determined by XPS, and the amine concentrations and selectivities were quantified via chemical derivatisation. The UV‐PE:N films were compared with plasma polymers deposited using low‐pressure glow discharges in similar gas flow mixtures, “L‐PPE:N”; it is shown that VUV photochemistry is superior to plasma chemistry in producing almost monofunctional organic thin films.

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Linear High Molecular Weight Ladder Polymer via Fast Polycondensation of 5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethylspirobisindane with 1,4‐Dicyanotetrafluorobenzene
Authors: Du Naiying , Song Jingshe , Robertson Gilles P. , Pinnau Ingo , Guiver Michael D.
Published: April 2008

A high molecular weight ladder polymer based on 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethylspirobisindane and 1,4‐dicyanotetraflurobenzene has been synthesized by polycondensation under high‐intensity mixing conditions at about 155 °C and cyclic‐free products were obtained in high yield with low molecular weight distribution (1.7–2.3). The reaction could be completed within a few minutes. The polymer properties were characterized by GPC, 1H NMR, 13C NMR, F NMR, FT‐IR, and MALDI‐TOF MS. In addition, the mechanical properties, apparent surface areas and gas permeability are also reported. This procedure can also be used for the synthesis of other ladder polymers by irreversible polycondensations of tetraphenols with activated tetrafluoro aromatics.

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Enzyme‐Catalyzed Ring‐Opening Polymerization of Unsubstituted β‐Lactam
Authors: Schwab Leendert W. , Kroon Renee , Schouten Arend Jan , Loos Katja
Published: April 2008

The synthesis of poly(β‐alanine) by Candida antarctica lipase B immobilized as novozyme 435 catalyzed ring‐opening of 2‐azetidinone is reported. After removal of cyclic side products and low molecular weight species pure linear poly(β‐alanine) is obtained. The formation of the polymer is confirmed with 1H NMR spectroscopy and MALDI‐TOF mass spectrometry. The average degree of polymerization of the obtained polymer is limited to $\overline {DP}$ = 8 by its solubility in the reaction medium. Control experiments with β‐alanine as a substrate confirmed that the ring structure of the 2‐azetidinone is necessary to obtain the polymer.

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Fiber reinforced refractory castables for SPF toolings
Authors: Bernhart G. , Nazaret F. , Cutard T.
Published: April 2008

Fiber reinforced refractory castable (FRRC) is an emerging material solution to manufacture SPF tools for forming titanium alloy sheets. Indeed, FRRC are able to conserve good mechanical properties up to 900 °C. Fiber reinforcement allows to improve mechanical properties and to avoid a catastrophic failure. Moreover, constitutive laws can be considered to reproduce the FRRC’s mechanical behaviour when using FEM codes. As a consequence, it is now possible to proceed to a numerical design of SPF tools that are based on FRRC. Following this route, large SPF tools have been designed, manufactured and tested under industrial conditions. Successful results have been obtained in the field of forming TA6V sheets.
The suitability of dental investment materials as dies for superplastic forming of medical and dental prostheses
Authors: Curtis R.V.
Published: April 2008

Dental investment materials have long been used in the manufacture of a whole variety of customised prostheses for dental restorative procedures. The metal castings produced often have very complex shapes and unless certain protocols are followed the range of casting errors can be great. Fortunately, the dental profession has a long experience with the Lost Wax Casting procedure and such problems are rare.

More recently, the investment materials commonly used to manufacture the casting moulds have been applied to the manufacture of dies for the production of dental and maxillofacial prostheses in titanium materials, such as Ti‐6Al‐4V and SP700 alloys. A range of studies has been conducted to assess the suitability of a variety of investment material types, all of which are available commercially. This paper will focus upon the physical properties of dental investment materials that are used to manufacture dies for the superplastic forming of dental and maxillofacial prostheses. In addition to the consideration of the physical properties of the die materials, other relevant issues include the die – titanium sheet interactions and post‐forming titanium sheet properties such as contamination and biocompatibility.

Such issues will be discussed in relation to regulatory issues concerning the use of biomaterials for the restoration of bodily function.
Some examples of current diffusion bonding applications
Authors: Wilden J. , Jahn S. , Beck W.
Published: April 2008

In recent years a renaissance of diffusion bonding can be observed. Beside applications in the aerospace industry more and more industrial users take advantage of the solid state joining process. The progressive development of micro technologies results from the systematic miniaturization efforts for electrical, optical and mechanical components. A major role for this is taken by the application of scale effects. Today, micro structured‐components are already deployed in telecommunication, mechanical engineering, medicine‐ and biotechnology.

During this continuous top‐down process the performance of a component should at least be equal or rather enhanced as compared to the conventional processed part. Increasing computational power needs a safely controlled and managed heat generation and distribution in any of such components.

This is not only important for electronic devices, but also for tools used for micro injection molding. With the combination of machining or laser cutting and subsequent diffusion bonding it is possible to freely design and manufacture the required parts with an inside structure. In this paper an enhanced process chain for production of parts by a lamination technology, which is capable to solve scale restrictions, is presented as well as application examples and process specific features, Fig. 1.
Cavity growth simulation for superplastic deformation of tetragonal Zirconia polycrystal, 3Y‐TZP
Authors: Harjo S. , Kojima N. , Motohashi Y.
Published: April 2008

A simulation based on cavity number ‐ radius distribution obtained from a scanning electron microscopy analysis was made to consider cavity growth rate and its mechanism during superplastic deformation of a tetragonal zirconia polycrystal (3Y‐TZP). It is found that (1) newly formed cavities grow very rapidly in an early stage of their growth process and then the growth rate becomes gradually slow with the increase in cavity size, and (2) the cavity growth process in the 3Y‐TZP is governed by the diffusion‐controlled mechanism.
String theory and cosmic connection during super plastic flow
Authors: Muñoz‐Andrade J.D.
Published: April 2008

The objective of this work is to describe the string theory and cosmic connection during super plastic flow in spatially extended polycrystalline systems (SEPCS), where the phenomenology and mechanics of the crystalline structure of the universe in a relativistic framework at Max Planck scale plays an important role. According to string theory as the unified theory of every thing, dislocations dynamics is related in nature form with the string theory. Consequently, dislocations at Max Plank scale are the universal way of working of every thing. In this physical framework, the theoretical model of Muñoz‐Andrade allows obtained the activation energy for super plastic flow in SEPCS. Finally, the main results of this work are analyzed in the context of the unified interpretation of string theory as cosmic connection during Hubble flow, plastic flow and super plastic flow.
Novel efficient DOPO‐based flame‐retardants for PWB relevant epoxy resins with high glass transition temperatures
Authors: Ciesielski M. , Schäfer A. , Döring M.
Published: April 2008

Novel derivatives of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) were obtained by a simple synthetic route and incorporated in epoxy resins, consisting of epoxy novolac (DEN 438), dicyandiamide (DICY), and fenuron. The thermal and fire‐retardant properties of DICY‐cured DEN 438 epoxy samples containing the novel DOPO‐based additives were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the UL 94 test. The obtained results were compared to those of specimens containing commercially available phosphates as flame‐retardants. UL 94 tests showed that nitrogen‐containing substituents at the phosphorus atom increase the fire‐retardant efficiency of DOPO‐based additives. Two nitrogen‐substituted DOPO derivatives 4,4′‐Diaminodiphenylmethane (DDM)‐(DOP)2 and DDM‐(DOP)2‐S were found to be very powerful fire‐retardants in DICY‐cured DEN 438 epoxy resins. The V0 rating was achieved at approximately 1% phosphorus in the resin and the glass transition temperature (Tg) was maintained at the high level of the pure DEN 438/DICY epoxy material (Tg = 180–185°C). These novel DOPO derivatives are the first non‐reactive additives having no influence on the Tg of the epoxy material. They not only surpass the capabilities of the other additives used in this work, but also those of all commercially available flame‐retardants for epoxy resins. Therefore, DDM‐(DOP)2 and DDM‐(DOP)2‐S are expected to be qualified for high‐Tg resins commonly used in printed wiring boards (PWB) for high‐performance applications. Copyright © 2008 John Wiley & Sons, Ltd.
Nanostructured polyolefins/clay composites: role of the molecular interaction at the interface
Authors: Passaglia Elisa , Bertoldo Monica , Coiai Serena , Augier Sylvain , Savi Stefania , Ciardelli Francesco
Published: April 2008

The extent of interphase interactions between polymer phase and inorganic particles is the driving force addressing the preparation/properties design in the field of the corresponding micro‐ and nanocomposites. In the case of preparation of nanocomposites based on polyolefins (POs) and inorganic compounds as potentially nanodispersed phase, the use of a PO with proper functional groups is necessary for the interface adhesion and stabilization of the nanostructured morphology. According to this approach, ethylene/propylene copolymers with a different propylene content were used for the preparation of nanocomposites through melt mixing with organophilic montmorillonites (OMMT). By taking into account the important role of functionalities grafted onto POs, two different synthetic approaches were compared here: (1) the dispersion of the inorganic filler was obtained by using previously functionalized POs bearing carboxylate groups as matrices; (2) the nanocomposites were prepared by performing contemporaneously the functionalization of POs (by using maleic anhydride (MAH) and/or diethyl maleate (DEM)) and the dispersion of the filler in a one‐step process. The morphology of the nanocomposites as well as the variation of solubility and glass transition temperature (Tg) of the PO matrix were evaluated and tentatively discussed with reference to functionalization degrees, structure of PO, and preparation procedure. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of talc on the fire retardant properties of highly filled intumescent polypropylene composites
Authors: Duquesne S. , Samyn F. , Bourbigot S. , Amigouet P. , Jouffret F. , Shen K.
Published: April 2008

Intumescent systems have been developed since many years for a wide range of applications, even if they are mainly used in coatings nowadays. The objective of this paper is to determine if the intumescent concept can be applied to highly filled reinforced polypropylene (PP) composites containing talc. Formulations that meet the electrical industry requirements have been developed, even if it has been observed that the addition of talc into intumescent PP leads to a decrease in the fire retardancy of the systems. A thermal stabilization of the material is noted at high temperature in the presence of talc. An increase in the crystallinity of the intumescent structure is suspected to be, at least partially, responsible for the decrease in the performance. Copyright © 2008 John Wiley & Sons, Ltd.
Polychromatic light‐emitting conjugated polymer prepared by controlling its structure through active free radical addition
Authors: Zhang Jian‐Jun , Gao Ge , Dong Wei , Zhao Da‐Cheng , Liu Feng‐Qi
Published: April 2008

BACKGROUND: The HOMO–LUMO energy level width of conjugated polymers can be manipulated by controlling the conjugation length of the polymeric materials in order to adjust their properties in terms of emission of different colors and realize polychromatic displays. In the work reported in this paper azobisisobutyronitrile (AIBN) was used to control the conjugation length of poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐co‐(1,4‐phenylene vinylene)] (MEH‐PPV) by free radical addition. In this way a series of MEH‐PPV with various conjugation lengths was obtained.

RESULTS: Characterization of MEH‐PPV using 1H NMR and Fourier transform infrared spectroscopy demonstrated that the cyano groups of AIBN hydrolyzed into carboxyls. The carboxyl free radicals attacked the conjugated double bonds of MEH‐PPV, resulting in a decrease of trans‐vinylenes and in an increase of cis‐vinylenes as well as tert‐methyls on the backbone. Changing the conjugated structure of the polymer caused the peaks of UV and fluorescence spectra to shift to the blue.

CONCLUSION: The resulting MEH‐PPV derivatives can emit orange‐red, green and blue light. It is expected that they could be used to prepare PPV‐based materials that could modulate white light emission, by simply blending the PPV derivatives emitting different colors. Copyright © 2008 Society of Chemical Industry
Applied Plasma Medicine
Authors: Fridman Gregory , Friedman Gary , Gutsol Alexander , Shekhter Anatoly B. , Vasilets Victor N. , Fridman Alexander
Published: April 2008

An emerging field of plasma medicine is discussed, where non‐equilibrium plasmas are shown to be able to initiate, promote, control, and catalyze various complex behaviors and responses in biological systems. More importantly, it will be shown that plasma can be tuned to achieve the desired medical effect, especially in medical sterilization and treatment of different kind of skin diseases. Wound healing and tissue regeneration can be achieved following various types of plasma treatment in a multitude of wound pathologies. Non‐equilibrium plasmas will be shown to be non‐destructive to tissue, safe, and effective in inactivation of various parasites and foreign organisms.

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Localised attitudes matter: a study of sickness absence in Sweden
Authors: Haugen Katarina , Holm Einar , Lundevaller Erling , Westin Kerstin
Published: April 2008

The central issues explored in this article are the importance of geographical location in explaining the attitudes of individuals, and the interplay between these attitudes and overt behaviour. The context is as follows: In the late 1990's, sick‐listings in Sweden underwent a substantial increase, causing the public expenses for the general sickness insurance to soar. Moreover, the extent of the usage of the insurance was found to vary significantly across different regions within the country. This development of the sickness insurance generally, and the regional differences specifically, have since been the subject of an intense debate. Differences and/or changes in attitudes toward sick leave within the population have been proposed as possible reasons for the regional variations. Much of the discussion has, however, been based on speculative arguments rather than empirical studies. Using data from a survey conducted in 2005, this research explores whether geographical location influences individual attitudes toward sick leave, and whether these attitudes in turn influence the sickness absence of individuals. The data are analysed using factor analysis, ordinary linear regressions and logistic regressions. The results provide some support for the idea that geographical factors matter to individual attitudes, and that variation in these attitudes is in turn associated with propensity for sickness absence. Copyright © 2008 John Wiley & Sons, Ltd.
SIMS and Raman studies of Mg‐doped InN
Authors: Davydov V. Yu. , Klochikhin A. A. , Smirnov M. B. , Kitaev Yu. E. , Smirnov A. N. , Lundina E. Y. , Lu Hai , Schaff William J. , Lee H.‐M. , Lin H.‐W. , Hong Y.‐L. , Gwo S.
Published: April 2008

Raman and SIMS studies of Mg‐doped InN films with a Mg content from NMg = 3.3 × 1019 to 5.5 × 1021 cm–3 are reported. Lattice dynamics of hexagonal InN with substitutional impurities and vacancies has been investigated theoretically and calculated Raman spectra were compared with experimental ones. It is concluded that Raman spectroscopy is a good tool for quantitative characterization of Mg‐doped InN. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitonic spin relaxation in GaN
Authors: Brimont C. , Gallart M. , Crégut O. , Hönerlage B. , Gilliot P.
Published: April 2008

By performing non‐degenerate pump‐probe experiments, we study the relaxation dynamics of spin‐polarized A and B excitons in wurtzite epitaxial GaN. By analyzing the differential reflection of the two circularly polarized probe components, we extract characteristic times of the different spin relaxation processes. We show that the spin relaxation of the exciton as a whole is negligible in regard to the spin relaxation of the individual carriers. We determined Te = 15 ps for the electron in the conduction band, Thh = 5 ps, and Tlh = 1.5 ps for the heavy hole and for the light hole, respectively. The quite long HH relaxation time can be related to the band structure in which the degeneracy between different spin valence bands is lifted. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison between extended microtunnels along different crystal orientations in GaN
Authors: Wu Pei‐Lun , Huang Hsin‐Hsiung , Zeng Hung‐Yu , Liu Po‐Chun , Lai Chih‐Ming , Tsay Jeng‐Dar , Lee Wei‐I
Published: April 2008

Triangular prism‐like extended microtunnels (EMTs) can be easily formed in specially designed epitaxial lateral overgrowth GaN thick films by selective wet chemical etching in molten potassium hydroxide (KOH). In this study, extended microtunnels along the 〈1$ \bar 1 $00〉 and the 〈1$ \bar 2 $00〉 directions were fabricated and compared. If tunnels along the 〈1$ \bar 1 $00〉 direction, the {11$ {\bar 2} {\bar 2} $} planes would be the etch stop plane. While the tunnels along 〈1$ \bar 2 $00〉 direction, the etch stop plane would become to {10$ {\bar 1} {\bar 1} $} planes. The activation energies of wet chemical etch for the {11$ {\bar 2} {\bar 2} $} planes and the {10$ {\bar 1} {\bar 1} $} planes were determined to be 23.6 kcal/mol (1.02 eV) and 22.8 kcal/mol (0.99 eV) using Arrhenius plot. On the other hand, the etching depths of the tunnels along the 〈1$ \bar 1 $00〉 direction were more than twice the depths of the tunnels along the 〈1$ \bar 2 $00〉 direction during the same etching time. The highest etch rate of the tunnels along the axial direction can reach 1000 μm/hr in 〈1$ \bar 1 $00〉 direction, which is believed to be the highest etch rate of GaN ever reported. Additional crystal facet of m‐plane in GaN was also observed in the sample with extended microtunnels along the 〈1$ \bar 2 $00〉 direction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence and Raman spectroscopy of MBE‐grown InN nanocolumns
Authors: Segura‐Ruiz J. , Garro N. , Cantarero A. , Denker C. , Werner F. , Malindretos J. , Rizzi A.
Published: April 2008

InN nanocolumns grown under different conditions by plasma‐assisted molecular beam epitaxy on p‐Si (111) substrates are studied by micro‐Raman and photoluminescence (PL) spectroscopies. The nanocolumns are free of strain and have an improved crystal quality as shown by the frequency and linewidth of the nonpolar E2h mode. Uncoupled polar modes coexist with a couple LO phonon‐plasmon mode and are sensitive to the nanocolumn morphology. Variations in the growth conditions also modify the PL spectra significantly. An increase in the PL energy also involves a reduction of the integrated intensity and an increase of the PL linewidth. This overall phenomenology highlights the role of the surface accumulation layer in these nanostructures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of metallic surface coverage on material quality in III‐nitride MOVPE
Authors: Kondratyev A. V. , Talalaev R. A. , Segal A. S. , Yakovlev E. V. , Lundin W. V. , Zavarin E. E. , Sinitsyn M. A. , Tsatsulnikov A. F. , Nikolaev A.E.
Published: April 2008

Pinholes and pits are well known types of defects characteristic for nitride growth by MOVPE. This paper reports on studies of the correlation between the defect appearance and MOVPE growth conditions and discusses the ways to improve the material quality. A decrease of the ammonia flow at a constant total flow during MOVPE of GaN in a hydrogen‐ammonia atmosphere at moderate temperatures (750‐900 °C) has revealed the overgrowth of pinholes up to their almost complete disappearance. The same effect was observed by the addition of a certain amount of trimethyindium to the gas phase. In both cases the improvement in morphology was associated with an accumulation of metallic (Ga and In, respectively) atoms in the adsorption layer at the growing surface. This conclusion was supported by surface kinetics model computations. The model suggests possible strategies for the growth of pinhole‐free layers in various device structures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical properties of indium‐rich InGaN islands
Authors: Tsai Wen‐Che , Lin Hsuan , Ke Wen‐Chen , Chang Wen‐Hao , Chou Wu‐Ching , Chen Wei‐Kuo , Lee Ming‐Chih
Published: April 2008

Indium‐rich Inx Ga1‐x N islands (x ≥ 0.87) grown by metalorganic chemical vapor deposition at growth temperatures ranging from 550‐750 °C were investigated. With the increasing growth temperature, the InGaN dot size increases while the dot density decreases due to the enhanced surface migration of In/Ga adatoms at elevated temperatures. In addition, the composition of InGaN islands was also found to be varied with the growth temperature. At lower growth temperatures, a higher Ga content can be achieved due to the relatively lower migration ability of Ga adatoms. At higher growth temperatures, the deposited InGaN material tend to decompose into In‐rich islands and a thin Ga‐rich layer. Photoluminescence investigations show that these In‐rich islands exhibit a near‐infrared emission band. For samples grown at higher temperatures, a visible emission band was also observed. The visible emission band may arise from defect bands introduced during the formation of Ga‐rich InGaN layer. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐organized growth of InN‐nanocolumns on p‐Si(111) by MBE
Authors: Denker Christian , Malindretos Joerg , Werner Florian , Limbach Friederich , Schuhmann Henning , Niermann Tore , Seibt Michael , Rizzi Angela
Published: April 2008

InN‐nanocolumns are an attractive system for light harvesting applications. To understand the mechanism of self organized growth of nanocolumns in plasma assisted MBE, InN samples were produced under various conditions on p‐Si(111). Depending on the growth parameters different growth regimes for nanocolumns were identified according to their final shape. High‐resolution TEM pictures show a very good crystal quality. This is also confirmed by Raman and PL measurements. Nanocolumns with diameters of 20‐200 nm and lengths of up to 2 mm were produced. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of a novel hyperspectral detector using the III‐nitrides
Authors: Tripathi N. , Bell L. D. , Grandusky J. R. , Jindal V. , Shahedipour‐Sandvik F.
Published: April 2008

We report on the growth and characterization of a novel, III‐nitrides based, tunable hyperspectral photodetector. The proposed device structure consists of AlxGa1–xN multilayer heterostructure with Al composition of 0 < x <1 grown on a GaN/sapphire template. The AlxGa1–xN heterostructure forms a stepped triangular profile potential barrier whereby the height of the potential barrier can be tuned by varying the applied voltage. Height of the potential barrier determines the threshold energy of the photoemission current over the potential barrier and hence determines the detection wavelength of the device. Device structures with different AlGaN layer thicknesses are evaluated to understand the dependence of the dark current and the quantum efficiency of the device on the thickness of the barrier structure. Internal photoemission (IPE) measurements have been carried out to measure the potential barrier faced by the photoexcited carriers. A reduction in potential barrier by 0.65 eV is observed over an applied voltage of 1.3 V, confirming the tunability of detection wavelength. Current‐voltage (I‐V) measurements and atomic force microscopy (AFM) have been used to study and improve the device performance. IPE, I‐V and AFM results are presented along with a discussion on the principle of device operation, detection wavelength tunability range and device structure optimization parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective area heteroepitaxy of low dimensional a ‐plane and c ‐plane InGaN nanostructures using pulsed MOCVD
Authors: Jindal V. , Tripathi N. , Tungare M. , Paschos O. , Haldar P. , Shahedipour‐Sandvik F.
Published: April 2008

High density a ‐plane and c ‐plane InGaN nanostructures have been developed by nanoscale selective area epitaxial growth using pulsed MOCVD. SiO2 was used as a mask with nanopatterning through an anodic aluminum oxide template. The lateral dimensions of the pattern were controlled and varied from 30 nm to 180 nm by changing the anodization voltage and the electrolyte. Different substrates such as a ‐plane GaN on r ‐plane sapphire, r ‐plane sapphire and c ‐plane sapphire were used to develop InGaN nanostructures in a ‐ and c ‐ crystallographic directions respectively. Under identical growth conditions, InGaN nanostructures of various shapes were obtained on different substrates with differences in emission wavelength. The shape of the nanostructures on different substrates is discussed with respect to the stability and growth rates of various planes. However, the difference in emission wavelength is attributed to the In incorporation in the nanostructures. The optical properties of the nanostructures were studied by photoluminescence (PL) spectroscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation into the use of molecular hydrogen on the growth of gallium nitride via metal‐organic molecular beam epitaxy
Authors: Billingsley Daniel , Pritchett David , Henderson Walter , Carver Alexander G. , Burnham Shawn D. , Doolittle W. Alan
Published: April 2008

Molecular hydrogen (H2) has been investigated as a means to improve ammonia nitridation efficiency and attempts to reduce carbon contamination in ammonia‐based metal‐organic molecular beam epitaxy (MOMBE). A 30% improvement in crystalline quality, inferred from XRD, as well as an increase in subsequent GaN bulk growth rate was observed when bare sapphire was subject to H2 annealing before nitridation. However, the use of H2 during GaN homoepitaxy on GaN templates resulted in increased carbon contamination and decreased growth rate of GaN. The results demonstrate promise and proper uses of H2 during GaN growth under certain conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence study of hexagonal InN/InGaN quantum well structures grown on 3C‐SiC (001) substrates by molecular beam epitaxy
Authors: Hirano S. , Inoue T. , Shikata G. , Orihara M. , Hijikata Y. , Yaguchi H. , Yoshida S. , Hirabayashi Y.
Published: April 2008

We have studied photoluminescence from hexagonal InN/InGaN multiple quantum well structures grown on 3C‐SiC (001) substrates with an InGaN underlayer by plasma assisted molecular beam epitaxy. We have observed photoluminescence spectra of InN/InGaN MQWs with various well widths. The photoluminescence peak related to quantum wells was clearly observed even at room temperature and found to shift to higher energies with decreasing well width due to the quantum confinement effect. We also discuss the effect of the built‐in electric fields on the PL peak energy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Domain wall thickness variations of ferroelectric BaMgF4 single crystals in the tip fields of an atomic force microscope
Authors: Zeng H. R. , Shimamura K. , Villora E. A. G. , Takekawa S. , Kitamura K. , Li G. R. , Yin Q. R.
Published: April 2008

The ferroelectric domain wall thickness of a fluoride BaMgF4 single crystal was investigated by piezoresponse force microscopy. It was found that the domain wall thickness shows a strong spatial variation in the as‐grown crystal and the polarization reversal process. The original wall thickness is greater (about two to seven times) than that switched by the tip fields of the atomic force microscope. A significantly narrower domain wall was obtained in the higher tip‐field. The trapped defects at the domain wall play an important role in the spatial variation of the polarization width of 180° domain wall in the BaMgF4 single crystal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrodynamic simulation of the operational management of a proposed flood emergency storage area at the Middle Elbe River
Authors: Förster Saskia , Chatterjee Chandranath , Bronstert Axel
Published: April 2008

Emergency storage areas can be an effective structural flood protection measure. By their controlled flooding the risk of inundation for downstream areas with higher vulnerability can be reduced.

In the present study, the flooding and emptying process of a proposed storage area at the Middle Elbe River is simulated. The storage area has a maximum capacity of 40 million m3 and is divided into two polder basins. It is designed for the attenuation of extreme floods of 100 years or more return period.

A one‐dimensional hydrodynamic model is set up for a 20 km reach of the Elbe River, wherein the storage area is schematised by two storage cells each representing one polder basin. Flow between the storage cells and the Elbe River is controlled by adjustable gates, which operate based on the pre‐defined conditions.

Four flood scenarios which differ in flood magnitude and hydrograph shape are simulated. The scenarios are derived from analyses of a 70 years discharge record. Furthermore, for each flood scenario two gate control strategies are investigated.

The results show that during large floods the utilization of the storage area with controlled gate operations significantly reduces the Elbe River peak discharges. However, the magnitude of the attenuation depends on the steepness of the flood hydrograph and the applied control strategy with well‐timed gate operations. Copyright © 2008 John Wiley & Sons, Ltd.
Trend analysis of water quality in some rivers with different degrees of development within the São Paulo State, Brazil
Authors: Groppo Juliano Daniel , de Moraes Jorge Marcos , Beduschi Carlos Eduardo , Genovez Abel Maia , Martinelli Luiz Antonio
Published: April 2008

Time series of dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate, total phosphorus, chloride, ammonia and faecal coliforms (FC), monitored by CETESB (‘Companhia de Tecnologia de Saneamento Ambiental’), in the period from 1979 to 2001, were analysed in seven river basins located in the São Paulo State, one of the most developed regions in Brazil. The selected rivers, Piracicaba, Mogi‐Guaçu, Turvo Grande, Peixe, Aguapeí, São José dos Dourados and Alto Paranapanema have different degrees of development concerning industrial, agricultural and population growth. Trend analysis methodology was based on graphical exploratory analysis followed by confirmation through statistical tests. Results showed impoverishment of the water quality conditions in most of the studied basins, represented by the positive trends of the parameters (BOD, nitrogens, total phosphorus, clorate and FC) and negative trend of the parameter (DO). Among the analysed basins, the Piracicaba River is the most severely affected with higher variations in the magnitude followed by the basins of the Mogi‐Guaçu, Turvo Grande, Peixe and Aguapeí Rivers. On the other hand, the Alto Paranapanema and São José dos Dourados basins are the least affected. Copyright © 2008 John Wiley & Sons, Ltd.
Observation of localized optical near‐field generated by submicron two‐hole structure for novel SNOM probe
Authors: Oshikane Yasushi , Hara Seiji , Matsuda Takuya , Inoue Haruyuki , Nakano Motohiro , Kataoka Toshihiko
Published: April 2008

A novel concept for the fabrication of a submicrometer‐structured probe tip for application in scanning near‐field optical microscopy (SNOM) based on a metalized optical fiber and a focused ion beam (FIB) milling is presented and investigated experimentally. This concept has the potential to enable a novel SNOM probe having a reproducible characteristic in the generation of intense and highly localized optical near‐field at the probe tip. As the simplest case designed by the boundary element method (BEM), a fine structure, which sandwiches a small projecting portion between a pair of 100‐nm2 holes, was fabricated by FIB in a 200‐nm silver thin film on a flattened end face of the single‐mode optical fiber. This unique structure was backlit by light from an Ar+ ion laser with a wavelength of 514.5 nm, which passes along the fiber core, and combined optical and topographical measurements for detecting the localized optical near‐field around the holes. A sample scan was performed using a modified SNOM system employing a dielectric spherical probe of 500 nm in diameter, which was illuminated by the evanescent field arising from the total internal reflection of He‐Ne laser light with a wavelength of 632.8 nm. As a result, a small dimple corresponding to the two‐hole structure was observed in the topographic image and a bright spot having high locational correlation with the dimple was simultaneously recorded in the optical image. Further study is required to determine the dependence of the optical near‐field intensity and its localization on the submicrometer two‐hole structure. Copyright © 2008 John Wiley & Sons, Ltd.
A systemic framework for case‐based classroom experiential learning
Authors: Georgiou I. , Zahn C. , Meira B. J.
Published: April 2008

This paper presents the two general types of cases designed for use in the classroom. It discusses how each type implies a particular instructional approach, and outlines the learning consequences of each approach. In doing so, it shows how each instructional approach on its own proves to be educationally deficient. The paper then draws from a systems thinking epistemology to argue that when the two instructional approaches are combined, emergent educational benefits arise. A critical appreciation of Kolb's learning cycle is simultaneously offered. The paper then offers a systemic framework for case‐based classroom experiential learning. The paper concludes with a critical review of this framework which can serve to guide instructors. Copyright © 2008 John Wiley & Sons, Ltd.
Can outstanding performance also be long‐standing?
Authors: Xardel Dominique , Schulz Annegret
Published: April 2008

Best practices in the business world are often identified by benchmarking in relation to products and the processes by which those products are created and delivered. This can take place inside a specific industry, but also in other industries and different countries. There, the main challenge for global firms is to decide how and how far to adapt those practices to the local environment, which is, in most cases, very different from their domestic markets.

This article examines the performance of selected companies from various industries that have, in recent years, successfully developed and implemented new business concepts and new business processes in both their domestic and global markets while implementing their global strategy. The article also seeks to identify and evaluate the pitfalls or difficulties they had to face, as well as to compare their results with the objectives they wanted to achieve. © 2008 Wiley Periodicals, Inc.
DHL Bangladesh: Managing headquarters‐subsidiary relations. Comment on DHL Bangladesh: Managing headquarters‐subsidiary relations
Authors: Merchant Hemant , Chand Masud , Michiels Caroline
Published: April 2008

This case revolves around Nurul Rahman, a DHL Bangladesh (DHLB) manager who must recommend which of the two human resource information systems (HRISs) DHLB should adopt to alleviate the escalating workload on its human resources (HR) department. The choice between these systems is difficult: the HRIS favored by regional headquarters is significantly more expensive and likely unsuited to DHLB's unique needs, whereas the HRIS favored by DHLB—although likely effective —seems to be incapable of meeting headquarters' strong preference for streamlining human resource systems across disparate Asian subsidiaries. Rahman must carefully balance conflicting stakeholder interests and do so against the backdrop of a politically powerful headquarters that can “make or break” managerial careers. © 2008 Wiley Periodicals, Inc.
Soap‐based detergent formulations: XIX. Amphoteric alkylsuccinamide derivatives as lime soap dispersants
Authors: Micich T. J. , Linfield W. M. , Weil J. K.
Published: April 2008

Abstract and Summary

A series of amphoteric surfactants was synthesized by reaction of 1,3‐propanesultone with N‐alkyl‐N′‐(ω,ω‐dimethylaminoalkyl)succinamides. The intermediate succinamides were prepared by reacting methyl N‐alkylsuccinamates, obtained from alkylamines containing 8 to 18 carbon atoms, with N,N‐dimethyl‐1,3‐propylenediamine or N,N‐dimethylethylenediamine neat. The amphoterics were isolated as hygroscopic crystalline solids having superior lime soap dispersing ability, water solubility, and calcium ion stability. Detergency studies at 0.2% concentration (300 ppm water hardness) indicated good washing ability when used alone and excellent performance in combination with soap or in soap‐silicate formulations.
Studies of the fluorescent products of lipid oxidation in aqueous emulsion with glycine and on the surface of silica gel
Authors: Shimasaki Hiroyuki , Privett O. S. , Hara Ichiro
Published: April 2008

Abstract and Summary

The formation of fluorescent products in the reaction of methyl linoleate hydroperoxide with glycine in aqueous emulsions correlated directly with the decrease in diene conjugation and the increase in thiobarbituric acid (TBA) reactive substances. These correlations also were reflected in the course of the oxidation of methyl linoleate in aqueous emulsions with glycine and indicated that glycine reacted with products of peroxide decomposition as opposed to intermediates of autoxidation in hydroperoxide formation. Thin layer chromatography (TLC) and selective solvent extraction demonstrated that the products of the reaction contained many substances with a fluorescent spectrum similar to those of lipofuscin pigments. When methyl esters of polyunsaturated fatty acids or other polyunsaturated lipids underwent oxidation adsorbed on silica gel particles, products with similar fluorescent spectral properties were formed illustrating that fluorescent substances were formed in a variety of reactions associated with the oxidation of unsaturated lipids.
Survey of aflatoxins in California tree nuts
Authors: Fuller Glenn , Spooncer W. W. , King A. D. , Schade J. , Mackey B.
Published: April 2008

Abstract and Summary

Surveys of the California walnut and almond crops to determine incidence of aflatoxins are reported. Average proportions of contaminated nuts from the field were one in 28,250 for walnuts and one in 26,500 for almonds. It was shown that there is a high correlation of contamination with damaged nuts which are removed by standard sorting procedures. Statistical treatment of data from the surveys indicates some of the problems in sampling tree nuts for analysis.