bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamics of T‐cell receptor–peptide/MHC interactions: progress and opportunities
Authors: Armstrong Kathryn M. , Insaidoo Francis K. , Baker Brian M.
Published: May 2008

αβ T‐cell receptors (TCRs) recognize peptide antigens presented by class I or class II major histocompatibility complex molecules (pMHC). Here we review the use of thermodynamic measurements in the study of TCR–pMHC interactions, with attention to the diversity in binding thermodynamics and how this is related to the variation in TCR–pMHC interfaces. We show that there is no enthalpic or entropic signature for TCR binding; rather, enthalpy and entropy changes vary in a compensatory manner that reflects a narrow free energy window for the interactions that have been characterized. Binding enthalpy and entropy changes do not correlate with structural features such as buried surface area or the number of hydrogen bonds within TCR–pMHC interfaces, possibly reflecting the myriad of contributors to binding thermodynamics, but likely also reflecting a reliance on van't Hoff over calorimetric measurements and the unaccounted influence of equilibria linked to binding. TCR–pMHC binding heat capacity changes likewise vary considerably. In some cases, the heat capacity changes are consistent with conformational differences between bound and free receptors, but there is little data indicating these conformational differences represent the need to organize disordered CDR loops. In this regard, we discuss how thermodynamics may provide additional insight into conformational changes occurring upon TCR binding. Finally, we highlight opportunities for the further use of thermodynamic measurements in the study of TCR–pMHC interactions, not only for understanding TCR binding in general, but also for understanding specifics of individual interactions and the engineering of TCRs with desired molecular recognition properties. Copyright © 2008 John Wiley & Sons, Ltd.
Chemical composition and insecticidal properties of Origanum glandulosum (Desf.) essential oil from Algeria
Authors: Khalfi Ouassila , Sahraoui Naima , Bentahar Fatiha , Boutekedjiret Chahrazed
Published: May 2008

BACKGROUND: To find natural compounds with insecticidal properties which could be an alternative to synthetic insecticides, oregano essential oil was tested against the insect Rhizopertha dominica devastating stored cereals.

RESULTS: Oregano oils were isolated by steam distillation, analysed by gas chromatography and gas chromatography–mass spectrometry and investigated for their insecticidal activities against Rhizopertha dominica. Contact and fumigant toxicities of global oil and three of its fractions recovered respectively after 2 h and after 0–2.5, 2.5–5 and 5–10 min of extraction were tested using the filter paper method. Eighteen components, representing 92.6% of the oil, were identified. The major components were thymol (38.8%), carvacrol (32.9%), p‐cymene (7.9%) and γ‐terpinene (5.1%). Toxicity tests showed that insect mortality increases with the concentration used (0.39%, 0.78%, 1.56%, 3.12% and 6.24%V). For all concentrations, the contact effect of global oil and fraction F2 was better than the fumigant effect. Whereas fractions F1 and F3 were more toxic by fumigation for concentrations lower or equal to 1.56%, their contact effect was more significant for concentrations higher than 1.56%.

CONCLUSION: These results suggest that oregano oil has important insecticidal properties and may be useful as a natural grain protectant against Rhizopertha dominica to replace synthetic insecticides. Copyright © 2008 Society of Chemical Industry
Characterizing diversity in composition and pasting properties of tuber flour in yam germplasm (Dioscorea spp.) from Southern Ethiopia
Authors: Tamiru Muluneh , Maass Brigitte L , Pawelzik Elke
Published: May 2008

BACKGROUND: Studies on composition and functional properties in germplasm collections are important in determining their diversity and suitability for food and non‐food applications. The diversity in 65 yam accessions collected from Southern Ethiopia and belonging largely to a yet unknown species and to Dioscorea bulbifera L. (aerial yam) was analyzed based on protein, starch and amylose contents, and pasting properties of tuber flour, applying descriptive and multivariate statistics.

RESULT: Starch content varied from 65.2% to 76.6% dry matter, while the protein content range was 6.4–13.4% dry matter. Amylose represented between 7.1% and 30.6% of the starch fraction, and was negatively correlated (P < 0.01) with starch content. UPGMA clustering and principal component analysis clearly distinguished aerial yam from those accessions with underground tubers. The first four principal components accounted for 78% of the total variability, and were highly correlated with pasting parameters.

CONCLUSION: The extent of diversity detected among accessions studied showed scope for improving the crop through selection of landraces with desirable characteristics. Similar investigations on tubers grown under different environmental conditions and additional data on physicochemical properties of isolated starch will be useful in evaluating the potential of yam for food and non‐food applications. Copyright © 2008 Society of Chemical Industry
Time‐ and Temperature‐Dependent Fracture Mechanics of Polymers: General Aspects at Monotonic Quasi‐Static and Impact Loading Conditions
Authors: Lach Ralf , Grellmann Wolfgang
Published: May 2008

Well‐defined correlations exist between the maxima in mechanical loss factor and the local maxima in temperature‐ or loading‐speed‐dependent fracture toughness. The non‐linear viscoelastic fracture processes and small‐strain deformations are characterised by the same Arrhenius‐type activation enthalpies. The local increase in toughness is linearly correlated with the relaxation strength of molecular relaxation processes. Stable crack propagation can be understood as a three‐phase process resulting in steady‐state stable crack growth. The normalised steady‐state crack‐tip‐opening displacement is independent of matrix material, temperature and loading speed.

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A Defect‐Free Ring Polymer: Size‐Controlled Cyclic Poly(tetrahydrofuran) Consisting Exclusively of the Monomer Unit
Authors: Tezuka Yasuyuki , Ohtsuka Tatsuroh , Adachi Kaoru , Komiya Ryota , Ohno Noriyoshi , Okui Norimasa
Published: May 2008

A series of size‐controlled, cyclic poly(tetrahydrofuran)s ($\overline M _{{\rm n,NMR}}$ of 4 400–8 600) that consist exclusively of the monomer, i.e., oxytetramethylene, unit (I) have been prepared in high yield through the metathesis polymer cyclization of a telechelic precursor having allyl groups, 1, in the presence of a Grubbs catalyst, and the subsequent hydrogenation of the linking, i.e., 2‐butenoxy, unit in the presence of an Adams' catalyst (PtO2). A remarkable topology effect has subsequently been observed upon the isothermal crystallization of these two model polymers, showing distinctive spherulite growth rates and spherulite morphologies in comparison with the relevant linear poly(tetrahydrofuran) counterpart that has ethoxy end groups (II).

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A pilot study to determine the short‐term effects of a low glycemic load diet on hormonal markers of acne: A nonrandomized, parallel, controlled feeding trial
Authors: Smith Robyn , Mann Neil , Mäkeläinen Henna , Roper Jessica , Braue Anna , Varigos George
Published: May 2008

Observational evidence suggests that dietary glycemic load may be one environmental factor contributing to the variation in acne prevalence worldwide. To investigate the effect of a low glycemic load (LGL) diet on endocrine aspects of acne vulgaris, 12 male acne sufferers (17.0 ± 0.4 years) completed a parallel, controlled feeding trial involving a 7‐day admission to a housing facility. Subjects consumed either an LGL diet (n = 7; 25% energy from protein and 45% from carbohydrates) or a high glycemic load (HGL) diet (n = 5; 15% energy from protein, 55% energy from carbohydrate). Study outcomes included changes in the homeostasis model assessment of insulin resistance (HOMA‐IR), sex hormone binding globulin (SHBG), free androgen index (FAI), insulin‐like growth factor‐I (IGF‐I), and its binding proteins (IGFBP‐I and IGFBP‐3). Changes in HOMA‐IR were significantly different between groups at day 7 (–0.57 for LGL vs. 0.14 for HGL, p = 0.03). SHBG levels decreased significantly from baseline in the HGL group (p = 0.03), while IGFBP‐I and IGFBP‐3 significantly increased (p = 0.03 and 0.03, respectively) in the LGL group. These results suggest that increases in dietary glycemic load may augment the biological activity of sex hormones and IGF‐I, suggesting that these diets may aggravate potential factors involved in acne development.
Apple polyphenols inhibit plasma CETP activity and reduce the ratio of non‐HDL to HDL cholesterol
Authors: Lam Cheuk Kai , Zhang Zesheng , Yu Hongjian , Tsang Suk‐Ying , Huang Yu , Chen Zhen Yu
Published: May 2008

Previous reports demonstrated that hypocholesterolemic activity of apple was associated with its pectin and fiber. This report was to investigate the effect of apple polyphenols (AP) on blood cholesterol level and gene expression of cholesterol‐regulating enzymes in Golden Syrian hamsters maintained on a 0.1% cholesterol diet. It was found that dietary supplementation of 0.3 or 0.6% of AP did not affect plasma total cholesterol (TC), but it increased HDL cholesterol (HDL‐C) and decreased non‐HDL‐C, thus leading to a lower ratio of non‐HDL‐C to HDL‐C. Plasma total triacylglycerol (TG) level was also significantly reduced when hamsters were fed a diet supplemented with 0.6% AP. Western blot analysis did not find any effect of AP on sterol regulatory element‐binding protein 2 (SREBP‐2), LDL receptor (LDLR), 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase (HMGR), and cholesterol‐7α‐hydroxylase (CYP7A). Most interesting was that supplementation of AP had no effect on protein abundance of plasma cholesteryl ester transport protein (CETP), but it suppressed plasma CETP activity. A series ofin vitroassays confirmed that AP inhibited CETP in a dose dependent manner. It was concluded that AP favorably improved distribution of cholesterol in lipoproteins, most likely, by its inhibition on CETP activity.
Wogonin, a bioactive flavonoid in herbal tea, inhibits inflammatory cyclooxygenase‐2 gene expression in human lung epithelial cancer cells
Authors: Chen Lih‐Geeng , Hung Liang‐Yi , Tsai Kun‐Wei , Pan Ying‐Shia , Tsai Yi‐Da , Li Yi‐Zhen , Liu Yi‐Wen
Published: May 2008

Wogonin, a naturally occurring plant flavonoid, is isolated from Chinese herbal plantsScutellaria baicalensisGeorgi andS. barbataD. Don. The extract ofS. baicalensisGeorgi has been added to an assortment of health drinks or food supplements. Wogonin has been reported to exhibit anticancer and anti‐inflammatory properties. Cyclooxygenase‐2 (COX‐2) is a key enzyme in the production of prostaglandins in inflammatory conditions. In this study, the effect of wogonin on phorbol 12‐myristate 13‐acetate (PMA)‐induced COX‐2 expression was investigated. It showed that wogonin inhibited PMA‐induced COX‐2 protein and mRNA levels in human lung epithelial cancer cells, and the mechanism of this inhibition was at the transcriptional level by using COX‐2 gene promoter assay. Among various signal inhibitors, the mitogen‐activated protein kinase kinase 1/2 (MEK1/2) inhibitor U0126 also inhibited PMA‐induced COX‐2 expression and COX‐2 promoter activation. The activity of AP‐1‐driven promoter, but not nuclear factor‐kappa B (NF‐κB), was inhibited by U0126. The data indicated that MEK1/2‐AP‐1 is very important for PMA‐induced COX‐2 expression. Wogonin also inhibited PMA‐induced AP‐1 activation and the expression of c‐Jun, a key component of AP‐1. Taken together, it is suggested that wogonin inhibits PMA‐induced COX‐2 gene expression by inhibiting c‐Jun expression and AP‐1 activation in A549 cells.
Analysis of Saccharomyces cerevisiae null allele strains identifies a larger role for DNA damage versus oxidative stress pathways in growth inhibition by selenium
Authors: Seitomer Eden , Balar Bharvi , He Dongming , Copeland Paul R. , Kinzy Terri Goss
Published: May 2008

Selenium toxicity is a growing environmental concern due to widespread availability of high‐dose selenium supplements and the development of high‐selenium agricultural drainage basins. To begin to analyze the effects of selenium toxicity at the genetic level, we have systematically determined which genes are involved in responding to high environmental selenium using a collection of viable haploid null allele strains of Saccharomyces cerevisiae representing three major stress pathways: the RAD9‐dependent DNA repair pathway, the RAD6/RAD18 DNA damage tolerance pathway, and the oxidative stress pathway. A total of 53 null allele strains were tested for growth defects in the presence of a range of sodium selenite and selenomethionine (SeMet) concentrations. Our results show that ∼︁64–72% of the strains lacking RAD9‐dependent DNA repair or RAD6/RAD18 DNA damage tolerance pathway genes show reduced growth in sodium selenite versus ∼︁28–36% in SeMet. Interestingly both compounds reduced growth in ∼︁21–25% of the strains lacking oxidative stress genes. These data suggest that both selenite and SeMet are likely inducing DNA damage by generating reactive species. The anticipated effects of loss of components of the oxidative stress pathway were not observed, likely due to apparent redundancies in these gene products that may keep the damaging effects in check.
The Role of Allylanisole in Metallocene‐Catalyzed Propylene Polymerization and Synthesis of End‐Capped Oligomers
Authors: Atiqullah Muhammad , Akhtar Muhammad N. , Tinkl Michael , Ahmed Neaz
Published: May 2008

Propylene was copolymerized with allylanisole (AA) using Me2Si(Ind)2ZrCl2 and Et(Ind)2ZrCl2, and the methylaluminoxane MAO cocatalyst at 70 °C and a cocatalyst to catalyst (Al:Zr) molar ratio of 1 000. It was fed at 8.5 bar(g). The weight‐average molecular weight, $\overline M _{\rm w}$, for both metallocenes decreased as the AA feed concentration increased. Therefore, allylanisole acted as an in situ chain transfer agent. The chain transfer constants, ktr/kp, of AA for Et(Ind)2ZrCl2 and Me2Si(Ind)2ZrCl2 turned out to be 0.33 and 0.40, respectively. The characterization of the resulting products by 1H NMR demonstrated that AA end‐capped the isotactic poly(propylene) chains which showed to be low molecular weight oligomers; 4.96 × 103 ≤ $\overline M _{\rm w}$ ≤ 9.80 × 103. An appropriate chain transfer mechanism for AA has been proposed.

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Excellent anti‐bacterial activity and surface properties of polyamide‐6 films modified with argon‐plasma and methyl diallyl ammonium salt‐graft
Authors: Yao Wei‐Hua , Chen Jui‐Chin , Chen Cheng‐Chi
Published: May 2008

In this study, the effect of argon‐plasma treatment on the grafting of methyl diallyl ammonium salt (MDAA) onto polyamide‐6 film and the anti‐bacterial and surface properties of the plasma‐ and graft‐treated film were investigated. The grafting amounts of MDAA caused by argon‐plasma treatment increased with the increase in the plasma exposure time and plasma power. The analyses of Fourier transform infrared (FT‐IR) spectroscopy and electron spectroscopy for chemical analysis (ESCA) spectra revealed that the epoxy and vinyl groups of MDAA could be grafted on the argon‐plasma treated polyamide‐6 film. The survey spectra of ESCA, the patterns of atomic force microscopy (AFM), and the spectra from scanning electron microscopy (SEM) were employed to certify the surface modification of argon‐plasma treated and the argon‐plasma treated/MDAA grafted polyamide‐6 films. Argon‐plasma treatment could generate the functional group and increase the roughness on the surface of polyamide‐6 film. This phenomenon could enhance the grafting effect of MDAA. The anti‐bacterial property of argon‐plasma treated/MDAA grafted polyamide‐6 film was excellent. This argon‐plasma treated/MDAA grafted polyamide‐6 film was expected to be applied on the field of packing. Copyright © 2008 John Wiley & Sons, Ltd.
Fabrication and properties of mineralized collagen‐chitosan/hydroxyapatite scaffolds
Authors: Zhao Haiguang , Ma Lie , Gao Changyou , Shen Jiacong
Published: May 2008

A hydroxyapatite (HAp)/biopolymer composite scaffold was fabricated by mineralizing a crosslinked collagen/chitosan, which was pre‐mineralized with Ca2+ and phosphate salts, in simulated body fluid (SBF) for only 24 hr. A self‐organized structure similar to bone is expected. Microstructures of the crosslinked collagen/chitosan scaffold, the pre‐mineralized collagen–chitosan scaffold (CCS), and the mineralized collagen‐chitosan/HAp scaffolds (MCCHS) were characterized by scanning electron microscopy (SEM), revealing non‐alteration of the porous structure and formation of the HAp particles. X‐ray diffractometer (XRD) confirmed the crystalline structure of the HAp. Thermal gravimetric analysis found that more HAp particles were formed when the CCSs were pre‐mineralized in a higher concentration of Ca2+. Water‐uptake ratio of the crosslinked CCS was ∼160, decreased to ∼120 after incubating in Ca2+ solution, and further decreased to ∼20 after mineralization. Mechanical strength of the CCS was improved significantly after the in situ mineralization too. The method introduced here may be potentially applied to obtain other biopolymer/HAp composite in a short period. Copyright © 2008 John Wiley & Sons, Ltd.
Characterization and physical properties of CoCl2 filled polyethyl‐methacrylate films
Authors: Abdelrazek E.M. , Elashmawi I.S.
Published: May 2008

Pure polyethyl‐methacrylate (PEMA) and PEMA filled with CoCl2 films were prepared by casting method. The structure and characterization of these film composites were investigated using Fourier transform infrared analysis (FTIR), optical spectra (UV), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and DC electrical conductivity. FTIR was used to identify the structural variations due to changing CoCl2 concentration. The assigned conjugated double bonds suggested the presence of polarons and bipolarons in the polymeric matrix. The shift of some bands manifested the specific interaction in PEMA matrixes and the filler. XRD reveals the presence of some crystalline phase in PEMA matrixes. The degree of crystallinity increase with increasing CoCl2 and there is no significant change on the halos center but it has become less obvious. Optical absorption measurements reveal that CoCl2 filler influences the optical energy gap. TGA data clarified that addition of CoCl2 to PEMA films enhances the thermal stability of PEMA. The activation energy decreases with increase in CoCl2 content. The electrical properties were studied using DC electrical conductivity. The electrical measurements revealed a nearly monotonic behavior of electrical conductivity as CoCl2 content increased. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Preparation and characterization of biodegradable waterabsorbent PAN/SS nanocomposite
Authors: Samal Bijayashree , Rana Pradeep Kumar , Sahoo Prafulla Kumar
Published: May 2008

Polyacrylonitrile (PAN)/sodium silicate (SS) nanocomposite was prepared via nonconventional emulsion method using an in situ developed transition metal complex Cu(II)/glycine taking ammonium persulfate (APS) as initiator, with a novel motive of converting hydrophobic homopolymer PAN into hydrophilic nano material via nanotechnology by the inclusion of SS to the homopolymer. UV–visible spectral analysis was carried out which revealed various interactions between the in situ developed complex with other reaction components. The formation of the PAN/SS nanocomposite was confirmed by infrared spectra (IR). Furthermore, as evidenced by transmission electron microscopy (TEM), the composite so obtained was found to have nano scale structure. X‐ray diffraction (XRD) was carried out suggesting that the silicate layers were exfoliated during the polymerization process. An increase in the thermal stability for the developed nanocomposite was recorded by thermogravimetric analysis (TGA). Surprisingly, it was also found that the PAN/SS nanocomposite showed considerable amount of waterabsorbency and was biodegradable as tested by activated sludge and cultured media and further confirmed by scanning electron microscopy (SEM). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Synthesis and characterization of montmorillonite/polypyrrole nanocomposite
Authors: Han Yongqin
Published: May 2008

A novel montmorillonite (MMT)/polypyrrole (PPy) nanocomposite (MPN) with high electrical conductivity and thermal stability has been synthesized via in‐situ polymerization. The surface morphology, characterization, thermal stability, and electrical conductivity have been tested by scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and four‐probe methods, respectively. SEM results show that the antenna‐like PPy deposits on the layer surface of MMT. FTIR and XRD analyses show that there is interaction between MMT and PPy. The nanocomposite has high electrical conductivity (4 S/cm), eight orders of magnitude higher than that of pristine MMT. The thermal stability of MPN is higher than the pure PPy as well as the mixture of MMT and PPy (MMP). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Numerical modeling of the impact response of fiber–metal laminates
Authors: Guan Z.W. , Cantwell W.J. , Abdullah R.
Published: May 2008

This article models the impact response of fiber–metal laminates (FMLs) based on a polypropylene (PP) fiber/PP matrix composite and two types of aluminum alloy. Here, a finite element analysis is used to model the impact behavior of FMLs at velocities up to 150 m/s. The PP‐based composite was modeled as an isotropic material with a specified tensile cut‐off stress to allow for the automatic removal of failed elements. The aluminum was modeled as an elasto‐plastic material with a specified shear failure strain and a tensile failure cut‐off stress. The deformed response of the structures and the resulting failure modes were compared with the experimental data. The variation of the maximum permanent displacement versus normalized impact energy was also predicted and compared with the impact test data and good agreement was observed. Finally, the decay of the kinetic energy of the projectile with time was determined for each of the targets and used to characterize their impact resistance. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Recurrent pulmonary alveolar proteinosis secondary to agammaglobulinemia
Authors: Patiroglu Türkan , Akyıldız Başak , Patiroglu Tahir E. , Gulmez Inci Y.
Published: May 2008

Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of surfactant derived material in the lung of patients. PAP is rare in children. The patient presented with respiratory failure. In the history she was diagnosed with agammaglobulinemia at 8 months of age and has been treated by IVIG once in a month. She had two pulmonary alveolary proteinosis attacks before. Chest X‐ray showed bilateral diffuse infiltrates. Initial diagnosis were pneumonia, ARDS, and lung edema. Whole‐lung lavage revealed lipoproteinaceous material similar to surfactant. This findings and high level of LDH was as evaluated pulmonary alveolary proteinosis. She discharged from the hospital without any respiratory complication on the ninth day. This is the first case report recurrent PAP associated with agammaglobulinemia. Pediatr Pulmonol. 2008; 43:710–713. © 2008 Wiley‐Liss, Inc.
Theoretical study of the optical response of the adsorption of Sb on the GaAs(110) surface
Authors: Mendoza Bernardo S. , Arzate N. , Vázquez‐Nava R. A.
Published: May 2008

A theoretical study of the optical response of the adsorption of Sb atoms on the clean GaAs(110) surface is presented. The reflectance anisotropy spectroscopy (RAS) spectrum is calculated and analysed as a function of Sbcoverage. To capture some of the possible dynamical processes of Sb sub‐monolayer growth, a 1 × 3 unit cell is considered whose equilibrium geometry has been obtained by performing an ab‐initio pseudopotential calculation with the use of density functional theory within the local density approximation. The RAS is calculated via the ab‐initio scheme and also by using a semiempirical tight binding formalism. Some trends in the RAS spectra are identified as the clean surface is partially covered by Sb until the one monolayer coverage is achieved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab‐initio optical spectra of complex systems
Authors: Cannuccia E. , Pulci O. , Palummo M. , Garbuio V. , Sole R. Del
Published: May 2008

We review the theoretical framework of ab‐initio excited state properties calculations showing the application of these methods to systems of different dimensionality. Many body perturbation theory within the GW approximation of the self energy for the calculation of electronic band structures is presented and applied to liquid water. The Bethe Salpeter equation for the computation of optical properties is illustrated and used for the case of surfaces and liquid water. An alternativemethod for the calculation of optical properties, the Time Dependent Density Functional Theory, is also briefly illustrated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atomistic structure of Si atoms agglomerated nearby a stacking fault in a commercial GaAs:Si
Authors: Ohno Y. , Taishi T. , Yonenaga I. , Takeda S.
Published: May 2008

Point defects nearby a Frank‐type stacking fault in a commercial GaAs:Si wafer (with the Si concentration of about 1018 cm–3) were examined by ultrahigh‐vacuum cross‐sectional scanning tunneling microscopy (UHVXSTM). The defects were identified as pairs of a Si donor and a Ga vacancy. Even though the pairs were electrically neutral, the Si donors in the pairs might be active when they were in the bulk crystal, since the Ga vacancies in the pairs were considered to be introduced after the UHV‐XSTM specimen preparation. The Si donors might be agglomerated towards the stacking fault, since the Si concentration nearby the stacking fault was rather high in comparison with the surrounding region. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interactions between coherent optical phonons and excitonic quantum beats in GaAs/AlAs multiple quantum wells: strategy for enhancement of terahertz radiation from coherent optical phonons
Authors: Nakayama M. , Mizoguchi K.
Published: May 2008

We have investigated the dynamical properties of coherent longitudinal optical (LO) phonons and excitonic quantum beats in GaAs/AlAs multiple quantum wells with various layer thicknesses, utilizing a reflection‐type pump‐probe technique and an optical gating method with a photoconductive dipole antenna. It is found that the pump‐probe signal of the coherent GaAs‐like LO phonon is markedly enhanced under the energy‐resonance condition of the LO phonon and the quantum beat due to the fundamental heavy‐hole and light‐hole excitons. This enhancement is caused by the coupling between the coherent LO phonon and excitonic quantum beat via the longitudinal polarization; namely, the quantum beat acts as a driving force for the coherent LO phonon. On the basis of this finding, we have demonstrated that the terahertz radiation from the coherent LO phonon is considerably intensified at room temperature by the longitudinal polarization coupling described above. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electromodulated optical properties of the silver/pentacene/ITO thin film structure
Authors: Lu C. R. , Shih R. C. , Hsu H. K. , Chou W. Y. , Mai Y. S. , Chu S. W. , Lin S. Y.
Published: May 2008

Electromodulated optical responses of the silver/pentacene/ITO thin film structures were characterized at various biases and temperatures. The optical transitions were perturbed by the energy shifts of the electronic states due to Stark effect induced by the modulation electric field. The modulated spectrum is strongly enhanced in the spectral regions involving the fundamental transitions and composed of the first derivatives of the unmodulated lineshapes. The field‐induced change of the transmission increases with the increasing modulation voltage. The transition energies of the silver/pentacene/ITO system can be derived from the peak positions in the electromodulated spectrum. As the temperature is increased from 25 K, the modulated transmission signal is also increased, and becomes non‐monotonous as the temperature is further increased. The transition energies involving the pentacene molecular states remain almost constant as the temperature varies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electro‐modulation enhancement in the InGaNAs/GaAs quantum well structures
Authors: Lee J. R. , Lu C. R. , Liu H. L. , Lin H. H. , Sun L. W.
Published: May 2008

Electrooptical properties of InGaNAs/GaAs quantum well structures were investigated by photoreflectance spectroscopy. The MBE grown structures consist of a central InGaNAs well, GaAs barriers, and GaAsN strain compensating buffer layers of different thickness. More quantum states and extended wave functions in the system with strain relief GaAsN barriers due to broader and lower confinement profile. Particular electro‐modulated spectral features corresponding to excitonic interband transitions are enhanced. Compared with the numerically calculated quantum state energies and wave functions, the electromodulation enhanced transitions were those involving quantum states with wave functions distribute in wider regions and extend more from the InGaNAs well into the space charge region near interfaces. It was the internal electric field near the heterointerfaces strongly enhanced the electro‐modulation efficiency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication and characteristics of a Pt/MgxZn1–xO Schottky photodiode on a ZnO single crystal
Authors: Endo H. , Sugibuchi M. , Takahashi K. , Goto S. , Hane K. , Kashiwaba Y.
Published: May 2008

The photoresponse of a Pt/MgxZn1–xO Schottky photodiode using a (0001) ZnO single crystal substrate grown by the hydrothermal growth method is described in this report. MgxZn1–xO thin films were prepared by a reactive RF magnetron sputtering method on the Zn‐face of the ZnO single crystal substrate. The prepared MgxZn1–xO thin films had a band gap of 4.1 eV. The fabricated Schottky photodiode had high responsivity of 0.034 A/W at the wavelength of 250 nm, and the responsivity ratio at wavelength of 250 nm and 550 nm was of the order of 4. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
QSAR Study on Piperidinecarboxamides as Antiretroviral Agents: An Insight Into the Structural Basis for HIV Coreceptor Antagonist Activity
Authors: Dessalew Nigus
Published: May 2008

Chemokines receptors have emerged as important drug targets for the development of agents against the Human Immunodeficiency Virus (HIV)/AIDS pandemic. With the purpose of designing new chemical entities with enhanced antiretroviral potencies, the Quantitative Structure–Activity Relationships (QSAR) study carried out on 122 novel piperidin‐4‐carboxamide derivatives as antagonists of HIV Chemokine Receptor 5 (CCR5) coreceptor binding is presented. The developed model was validated by standard QSAR parameters and through a detailed structural investigation on how it explains and reproduces the quantitative differences observed in the experimentally known activity data. The model showed a good correlative and predictive ability having a cross‐validated correlation coefficient (r2cv) of 0.794 and the conventional correlation coefficient (r2) was found to be 0.830. The study revealed that the CCR5 antagonistic activity exhibited by the series is largely explained by lipophilicity and steric bulkiness of substituents and that substituents with higher lipophilicity and steric superiority are required to make favorable antagonist–CCR5 interaction chemistry. A detailed investigation was made on the structural basis for the antiretroviral activity and the insights gleaned from the study could be usefully employed to design antagonists with a much more enhanced potency and selectivity.
Race and Wealth
Authors: Oliver Melvin L. , Shapiro Thomas M.
Published: May 2008

One of the most heated scholarly controversies in the area of racial equality and social justice in the 1980s has been the dispute over the nature, cause, and meaning of economic changes occurring within the black community. Although this debate has important public policy consequences, most of the research on which the debate is based is concerned with income. We argue that a broader interpretation of life chances should include an examination of wealth as well as income. Using the 1984 Survey of Income and Program Participation (SIPP), we examine black and white patterns of wealth inequality. Our analysis uncovers a depth of inequality beyond that which is found when income alone is considered. Furthermore, we find that both race and class are important in determining patterns of racial inequalities in wealth.
Factors Influencing the use of the Hospital Emergency Room among Black Americans
Authors: Thornton Michael C. , White-Means Shelly I.
Published: May 2008

Sociodemographic correlates of the use of emergency rooms for nonemergency health conditions were examined among black adults, using data from the National Medical Care Utilization and Expenditure Survey. Multivariate analysis revealed that marital status, the emergency room as a usual source of care, and health condition were determinants of choosing the emergency room as a source of medical care. The use of multivariate analysis extends previous work in this area. Implications for future research on determinants of emergency room use are discussed.
Technical new feature
Authors: Kozempel M. F. , Stabile R. L. , Craig J. C. , Sinnamon H. I. , Aceto N. C.
Published: May 2008

A continuous process for the commercial production of isopropenyl stearate (IPS) from triple pressed stearic acid and a stabilized form of propyne has been developed. Cost estimates, including capital costs, operating costs, and profitability, for commercial scale plant production which show the process to be economically feasible are presented. This potentially profitable process offers the advantages of reliable raw material sources, minimal external thermal requirements, and usable process waste streams. For a plant producing 5 million pounds of IPS per year, the selling price range is 80 to 107 cents/lb IPS, corresponding to a raw material cost range of 27 to 54 cents/lb of IPS. For a 20 million pound per year plant, the selling price range is 58 to 85 cents/lb IPS. The selling prices include a 20% annual return on fixed capital investment. Fixed capital requirement ranges from 2.7 to 10.9 million dollars (3rd quarter, 1975) for plants ranging in size from 5 to 50 million pounds of IPS per year, respectively.
Direct analysis of trivernolin by high‐performance liquid chromatography
Authors: Plattner R. D. , Wade K. , Kleiman R.
Published: May 2008

A rapid liquid chromatographic method for the quantitation of trivernolin in epoxy seed oils has been developed. A weighed sample of the oil is dissolved in chloroform (∼100–300 mg/ml), and a 1–20µl portion of the oil is chromatographed on a 2 ft×1/4 in. OD C18µ‐Bondapak column with acetonitrile‐acetone (2:1, v/v). The area of the trivernolin peak from the differential refractometer recorder tracing is converted toµg trivernolin by use of a calibration curve of peak area vs. trivernolin weight.
Factors affecting product specificity of peanut lipoxygenase
Authors: Singleton J. A. , Pattee H. E. , Nelson M. S.
Published: May 2008

Product specificity of peanut lipoxygenase with linoleic acid as the substrate was determined under different conditions. Extraction solvent, extraction temperature, and reaction temperature only slightly affected the isomeric hydroperoxide ratio. A more pronounced effect was reflected in the total amount of hydroperoxide produced and extracted. CHCℓ3:CH3OH was the most thorough solvent, and extraction temperature of 25 C increased the total amount of hydroperoxides recovered. Lower reaction temperatures produced greater quantities of total hydroperoxides. Oxygen tension and pH value markedly affected changes in the hydroperoxide isomeric ratio and the total amount of hydroperoxides produced. Isomerization of the isolated hydroperoxides occurred very rapidly at 25 C, and a linear isomerization rate was observed at 4 C. At −20 C isolated hydroperoxides isomerized only slightly. Concentration of isolated hydroperoxides affected isomerization of the isomeric hydroperoxides; storing hydroperoxides in dilute solutions was most effective in preventing isomerization.
A solvent‐free synthesis of sucrose polyesters
Authors: Rizzi George P. , Taylor Harry M.
Published: May 2008

A solvent‐free reaction system is described for making sucrose polyesters (SPE) by interesterification of sucrose and long chain fatty acid methyl esters. The process avoids the usual toxic solvents by using a novel two‐stage reaction sequence. In the first stage a 3:1 mole ratio of methyl esters to sucrose is reacted in the presence of potassium soaps to form a one phase melt containing mainly lower esters of sucrose. In the second stage more methyl esters are added and reacted to produce SPE in yields up to 90% based on sucrose. Sucrate ion generated in situ with alkali metal hydrides or Na‐K alloy proved to be a superior catalyst for formation of sucrose esters during both stages.
Use of carrier‐bound lipid substrates in enzymatic work
Authors: Tiru Mandayam , Tiru Maj‐Britt , Juhlin Rolf
Published: May 2008

A procedure has been developed for the adsorption of oily or solid substrates of low water solubility onto inert carriers having large specific surface areas. This technique improves the handling characteristics of such substrates, enhances the standardization of enzymes, and facilitates separation of a carrier‐bound substrate/product from the reaction mixture.
Civiliser en grèce ancienne adoucir la nature et naturaliser la force
Authors: Darbo-Peschanski Catherine
Published: May 2008

Les Grecs anciens n'ont pas unifié l'idée de civilisation en un concept ni sous un mot uniques. Envisagée comme un processus depuis les origines, elle se présente comme une série d'acquisitions ou de pertes au terme desquelles s'est forgée une condition humaine fortement ambivalente. Conçue comme un état, elle se rencontre à l'intersection de trois axes: celui d'un régime et d'une éducation qui apprivoisent la nature; celui d'un régime politique respectueux de la loi; celui d'une politique extérieure respectueuse de la justice. Mais en grec, régime politique et hégémonie portent le même nom (archê). En naturalisant et en légitimant la domination romaine Denys d'Halicarnasse en fait une force de civilisation.
Culture versus civilisation la genèse d'une opposition
Authors: Remaud Olivier
Published: May 2008

Étroitement lié au concept d'histoire, celui de culture devient un «collectifsingulier » à partir du dernier tiers du XVIIIe siècle. L'idée allemande de culture ne s'est pas immédiatement opposée au concept de civilisation et les deux termes ont longtemps gardé une signification presque identique. Que révèle donc l'orientation polémique du concept allemand de culture à partir des années 1880-1890? D'abord, la chute du modèle idéaliste néo-kantien d'un individu cultivé qui se détermine lui-même comme une fin (la Selbstbildung); ensuite, la montée en puissance d'une condamnation morale de l'esprit vide de l'époque. Ce double processus atteint son apogée haineuse durant la Première Guerre mondiale.
cAMP regulates respiration and oxidative stress during rehydration in Anabaena sp. PCC 7120
Authors: Higo Akiyoshi , Ikeuchi Masahiko , Ohmori Masayuki
Published: May 2008

Cellular cAMP level increased dramatically upon rehydration following dehydration for 24 h in Anabaena sp. PCC 7120, but not in disruptant of an adenylate cyclase gene, cyaC. Oxygen consumption in the cyaC disruptant upon rehydration was higher than that in wild‐type strain. Determination of lipid peroxidation and protein carbonylation of the cells revealed greater oxidative stress in the cyaC disruptant than in the wild‐type strain during rehydration. Addition of cAMP or KCN to the cyaC disruptant decreased cellular oxygen consumption upon rehydration and oxidative damage. These results suggest that respiration upon rehydration is regulated by cAMP and that the higher respiration activity results in more oxidative damage in cyaC disruptant.
Decision analytic models for Alzheimer's disease: State of the art and future directions
Authors: Cohen Joshua T. , Neumann Peter J.
Published: May 2008

Decision analytic policy models for Alzheimer's disease (AD) enable researchers and policy makers to investigate questions about the costs and benefits of a wide range of existing and potential screening, testing, and treatment strategies. Such models permit analysts to compare existing alternatives, explore hypothetical scenarios, and test the strength of underlying assumptions in an explicit, quantitative, and systematic way. Decision analytic models can best be viewed as complementing clinical trials both by filling knowledge gaps not readily addressed by empirical research and by extrapolating beyond the surrogate markers recorded in a trial. We identified and critiqued 13 distinct AD decision analytic policy models published since 1997. Although existing models provide useful insights, they also have a variety of limitations. (1) They generally characterize disease progression in terms of cognitive function and do not account for other distinguishing features, such as behavioral symptoms, functional performance, and the emotional well‐being of AD patients and caregivers. (2) Many describe disease progression in terms of a limited number of discrete states, thus constraining the level of detail that can be used to characterize both changes in patient status and the relationships between disease progression and other factors, such as residential status, that influence outcomes of interest. (3) They have focused almost exclusively on evaluating drug treatments, thus neglecting other disease management strategies and combinations of pharmacologic and nonpharmacologic interventions. Future AD models should facilitate more realistic and compelling evaluations of various interventions to address the disease. An improved model will allow decision makers to better characterize the disease, to better assess the costs and benefits of a wide range of potential interventions, and to better evaluate the incremental costs and benefits of specific interventions used in conjunction with other disease management strategies.
Energy and moment of the Earth’s rotation elastic field
Authors: Vikulin A.V.
Published: May 2008

The problem of an elastic stress field in a rotating medium is formulated and solved analytically within the limits of the classical theory of elasticity with a symmetrical stress tensor. This is a rotation elastic field of action at a distance. There are two specific types of elastic waves with a moment in rotating media: solitons and excitons, or rotation waves. The soliton solutions to the wave equation represent waves of global earthquake migration (slow tectonic waves) which are no faster than ∼1 cm/s, i.e., approach the migration velocity of large and great earthquakes (M > 7.5). The exciton solutions correspond to waves of local migration of foreshocks and aftershocks in earthquake sources (fast tectonic waves) and have their maximum velocity comparable to faulting rate and/or to S-wave velocities.
Three Bioethical Debates in Sweden
Authors: HANSSON SVEN OVE
Published: May 2008

Three of the bioethical issues recently discussed in Sweden appear to be particularly interesting also to an international audience. A new law allowing restrictive use of preimplantation genetic diagnosis (PGD)/human leukocyte antigen (HLA) (“savior siblings”) has been implemented, a new recommendation for the cessation of life-sustaining treatment has been issued, and the scope of individual responsibility for medical mistakes has been rather thoroughly discussed.
Islam and Informed Consent: Notes from Doha
Authors: DEL POZO PABLO RODRÍGUEZ , FINS JOSEPH J.
Published: May 2008

Informed consent is a perennial topic in bioethics. It has given the field a place in clinical practice and the law and is often the starting point for introductory instruction in medical ethics. One would think that nearly everything has been said and done on this well-worn topic.
CQ Sources/Bibliography
Authors: ANTON BETTE
Published: May 2008

These CQ Sources were compiled by Bette Anton.
The Case against Conscription of Cadaveric Organs for Transplantation
Authors: GLANNON WALTER
Published: May 2008

In a recent set of papers, Aaron Spital has proposed conscription or routine recovery of cadaveric organs without consent as a way of ameliorating the severe shortage of organs for transplantation. Under the existing consent requirement, organs can be taken from the bodies of the deceased if they expressed a wish and intention to donate while alive. Organs may also be taken when families or other substitute decisionmakers decide on behalf of the deceased to allow organ procurement for the purpose of transplantation. When patients or families do not consent to organ procurement, many transplantable organs are lost. This is a tragic yet avoidable situation. The dead are beyond any benefit or harm, and their organs could be used to prevent harm by saving and improving the lives of many people suffering and dying from end-stage organ failure.
The Relationship Between Unwillingness-to-Communicate and Students’ Facebook Use
Authors: Sheldon Pavica
Published: May 2008

A survey with 172 students was conducted at a large southern research university to examine how unwillingness-to-communicate in interpersonal communication influences gratifications sought and gratifications obtained from Facebook use. The study investigated the relationship between two dimensions of unwillingness-to-communicate (approach-avoidance and reward) and different motives of Facebook use. In addition, it examined the relationship between unwillingness-to-communicate and the behavioral and attitudinal outcomes of Facebook use (e.g., the number of hours spent on Facebook, duration of use, the number of Facebook friends, satisfaction with Facebook). Results of multiple regression analysis revealed that respondents who felt anxiety and fears in their face-to-face communication used Facebook to pass time and feel less lonely more than other respondents, but they had fewer Facebook friends. Overall, this paper finds evidence that people who are involved in online relationships are those who are willing to communicate in real life, rather than the opposite. Such results seem to justify the rich-get-richer hypothesis, which states that the internet primarily benefits extraverted individuals. Our results are in contrast to findings that socially anxious individuals are more likely to form relationships online.
Language Policies and In-group Favoritism
Authors: Gabriel Ute
Published: May 2008

This study investigates the influence of sex of respondent, context valence, and type of generic on the naming of female personalities in Norway where the feminine suffixing has dropped away in reaction to the problem of linguistic sexism. A total of 162 participants were asked to name either their most- or least-liked personalities. The survey employed either the generic form only or the generic form together with the obsolete feminine forms. Adding the feminine forms led to a significant increase in the number of female personalities named, suggesting that the Norwegian policy of gender neutralization has not (yet) been successful. Furthermore, the sex of respondent was positively related to the naming of same-sex personalities in the positive but not in the negative valence condition, thus documenting malleability in the interpretation of generics.