bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancing dispersion of copper nanowires in melt‐mixed polystyrene composites
Authors: Gelves Genaro A. , Lin Bin , Haber Joel A. , Sundararaj Uttandaraman 
Published: August 2008

AbstractCopper nanowire (CuNWs)/polystyrene (PS) composites were prepared by melt mixing using unfunctionalized and functionalized nanowires. Alkanethiols were utilized to modify the surface of CuNWs postsynthesis and enable their dispersion in a polymer melt. Unfunctionalized nanowires decreased the electrical resistivity of PS by nine orders of magnitude with 2.0 vol % Cu, and resulted in composites with a viscoelastic behavior dominated by polymer–polymer networks indicating that electrical percolation occurred without a transition from liquid‐like to solid‐like behavior (i.e., rheological percolation). Results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), and melt rheology characterization indicated that surface modification of CuNWs contributed to the dispersion of the nanofiller in the polymer matrix. CuNWs functionalized with 1‐octanethiol and 1‐butanethiol produced rheological percolation and a gradual decrease in the electrical resistivity of the PS nanocomposites with increasing concentration of nanowires. Polymer nanocomposites with low concentrations of functionalized nanowires showed lower complex viscosities than pure PS; this was attributed to a plasticizing effect introduced by the alkanethiols. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2064–2078, 2008
Control of the microstructure of polymer network and effects of the microstructures on light scattering properties of UV‐cured polymer‐dispersed liquid crystal films
Authors: Li Wenbo , Cao Hui , Kashima Miki , Liu Fang , Cheng Zihui , Yang Zhou , Zhu Siquan , Yang Huai 
Published: August 2008

AbstractPolymer‐dispersed liquid crystals (PDLC) films were prepared from ultraviolet (UV) irradiation‐induced polymerization of the photopolymerizable monomers in photopolymerizable monomers/nematic liquid crystal (LC) mixtures. The effects of the composition of the mixtures, the curing temperature, and the UV light intensity on the microstructure of the polymer network in the PDLC films were investigated. Furthermore, the effects of the microstructures on the light scattering properties of the PDLC films in the wavelength region of 300–2500 nm were studied experimentally and theoretically based on the combination of three kinds of classical light scattering theories: the Rayleigh‐Gans (RG) approach, the anomalous diffraction (AD) approach, and the geometrical optics (GO) approach. It was found that the sizes of LC domain in PDLC films increased with the increase of the LC content as well as the decrease of the UV curing intensity, while increased at first and then decreased with the increase of the curing temperature. Moreover, smaller LC domain sizes could exhibit strong scattering properties in a smaller VIS wavelength region and the transmittance in NIR region (especially in the wavelength range of 1300–2500 nm) obviously decreased with the increasing sizes of LC domain. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2090–2099, 2008
Glass transition and its characteristic length for thin crosslinked polystyrene shells of rodlike capsules
Authors: Sasaki Takashi , Misu Manabu , Shimada Takayuki , Teramoto Mitsuhiro 
Published: August 2008

AbstractRodlike capsules consisting of a calcium carbonate core and a crosslinked polystyrene shell were synthesized, and the glass transition temperature (Tg) and characteristic length of the glass transition ξ(Tg) for the thin outer shells were investigated by temperature‐modulated differential scanning calorimetry. The shell thickness ranged from 20 to 129 nm. The ratio of the Tg for the outer shell to the bulk Tg increases with decreasing shell thickness d. The d‐dependence of Tg is interpreted in terms of a simple two‐layer model which assumes that an immobile layer exists near the core‐shell interface. Shells of hollow capsules unexpectedly exhibit a similar d‐dependence of Tg to that for the filled capsules. This is characteristic of the crosslinked polymeric shells, and is attributed to certain spatial heterogeneity of crosslink distribution, and/or to the unstable configuration in the ultrathin shell that does not undergo relaxation due to the crosslink. The latter idea is based on the assumption that unstable configurational state is responsible for the Tg shift from the bulk value observed for nanosized polymeric materials. The ratio of the characteristic length for the shell of the filled capsule to that of the bulk ξf(Tg)/ξb(Tg) decreases with decreasing d. The results are interpreted in terms of the configurational entropy, and it is also suggested that the configurational state of network polymer chains in the shell affects the characteristic length. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2116–2125, 2008
Initial stage of fiber structure development in the continuous drawing of poly(ethylene terephthalate)
Authors: Yamaguchi Takayoshi , Kim Kyounghou , Murata Takahisa , Koide Mitsuharu , Hitoosa Shuuji , Urakawa Hiroshi , Ohkoshi Yutaka , Gotoh Yasuo , Nagura Masanobu , Kotera Masaru , Kajiwara Kanji 
Published: August 2008

AbstractThe initial stage of fiber structure development in the continuous neck‐drawing of amorphous poly(ethylene terephthalate) fibers was analyzed by in situ wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, and fiber temperature measurements. The time error of the measurements (<600 μs) was obtained by synchrotron X‐ray source and laser irradiation heating. A highly ordered fibrillar‐shaped two‐dimensional (smectic‐like) structure was found to be formed less than 1 ms after necking. By analyzing its (001′) and (002′) diffractions, the length of the structure 60–70 nm were obtained. A three‐dimensionally ordered triclinic crystal began to form with the vanishing of the structure around 1 ms after necking. The amount and size of the crystal were almost saturated within several milliseconds of necking, during which time a mainly exothermic heat of crystallization was also observed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2126–2142, 2008
Thiocarbamate‐linked peptides by chemoselective peptide ligation
Authors: Besret Soizic , Ollivier Nathalie , Blanpain Annick , Melnyk Oleg 
Published: August 2008

AbstractPeptide chemical ligation chemistries, which allow the chemoselective coupling of unprotected peptide fragments, are useful tools for synthesizing native polypeptides or unnatural peptide‐based macromolecules. We show here that the phenylthiocarbonyl group can be easily introduced into peptides on α or ε amino groups using phenylthiochloroformate and standard solid‐phase method. It reacts chemoselectively with cysteinyl peptides to give an alkylthiocarbamate bond. S,N‐shift of the alkylaminocarbonyl group from the Cys side chain to the α‐amino group did not occur. The method was used for linking two peptide chains through their N‐termini, for the synthesis of a cyclic peptide or for the synthesis of di‐ or tetravalent multiple antigenic peptides (MAPs). Thiocarbamate ligation is thus complementary to thioether, thioester or disulfide ligation methods. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Inhibition of soluble epoxide hydrolase by extracts derived from inflammation‐treating Chinese medicinal herbs
Authors: Shi Da‐Hua , Xu Chen , Guo Bin‐Xin , Wang Xiao‐Ting , Chen Yun‐Xi , Tan Ren‐Xiang 
Published: August 2008

AbstractSoluble epoxide hydrolase (sEH) has been proved to be a key enzyme involved in inflammation progression, and inhibition of sEH is therefore very helpful or crucial for the treatment of inflammation‐related diseases. In order to uncover new clues suggesting the presence of phytochemical‐based sEH inhibitors, and to rationalize the utility of the inflammation‐treating Chinese medicinal herbs, the ethanol extracts derived from 46 medicinal herbs, traditionally used for the treatment of inflammation‐associated diseases in China, were tested for sEH‐inhibition activity using a recently developed sensitive fluorescence‐based assay. Screened at 10 µg/mL, four extracts showed substantial inhibitions of sEH (inhibition rates >50%). The ethanol extract of Sophora flavescens root (Fabaceae) possessed the strongest inhibitory activity against sEH (IC50: 2.07 µg/mL). These preliminary findings highlighted the presence of sEH inhibitor(s) in the plant kingdom, and the possibility that the inflammation‐treating herbal medicines could be an untapped reservoir for sEH‐inhibition agents. Copyright © 2008 John Wiley & Sons, Ltd.
The effect of the aqueous extract of the roots of Asparagus racemosus on hepatocarcinogenesis initiated by diethylnitrosamine
Authors: Agrawal Alka , Sharma Meenakshi , Rai Santosh Kumar , Singh Bharat , Tiwari Manisha , Chandra Ramesh 
Published: August 2008

AbstractHistopathological studies of the hepatic tissues of Wistar rats treated with diethylnitrosamine (DEN) (200 mg/kg b wt, i.p.) once a week for 2 weeks, followed by treatment with DDT, a tumor promoter (0.05% in diet) for 2 weeks and kept under observation for another 18 weeks, demonstrated the development of malignancy. Pretreatment of Wistar rats with the aqueous extract of the roots of Asparagus racemosus prevented the incidence of hepatocarcinogenesis. Immunohistochemical staining of the hepatic tissues of rats treated with DEN showed the presence of p53+ foci (clusters of cells expressing the mutated p53 protein), whereas an absence of p53+ foci was observed in Wistar rats pretreated with the aqueous extract of the roots of Asparagus racemosus. The microsections of the hepatic tissue of rats treated with DEN followed by treatment with the aqueous extract of Asparagus racemosus showed an absence of p53+ foci. The results of the biochemical determinations also show that pretreatment of Wistar rats with the aqueous extract of Asparagus racemosus leads to the amelioration of oxidative stress and hepatotoxicity brought about by treatment with DEN. These results prove that the aqueous extract of the roots of Asparagus racemosus has the potential to act as an effective formulation to prevent hepatocarcinogenesis induced by treatment with DEN. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of Terminalia arjuna extract on adriamycin‐induced DNA damage
Authors: Reddy Tiyyagura Koti , Seshadri Prabhu , Reddy K. Kodanda Rami , Jagetia G. C. , Reddy C. Damodar 
Published: August 2008

AbstractThe effect of a bark extract of Terminalia arjuna (TAE) was studied on the alteration of adriamycin (ADR)‐induced micronuclei formation in cultured human peripheral blood lymphocytes. Exposure of lymphocytes to ADR resulted in a dose‐dependent increase in the micronuclei formation indicating DNA damage. Pretreatment of lymphocytes with TAE before ADR treatment resulted in a significant decline in micronuclei formation. Increasing doses of ADR caused a dose‐dependent increase in the frequency of lymphocytes bearing one, two and multiple micronuclei. Prior exposure of lymphocytes to 15 µg/mL of TAE significantly reduced the frequency of lymphocytes bearing one, two and multiple micronuclei when compared with ADR‐treated control. TAE‐inhibited the induction of •OH (hydroxyl), O2•− (superoxide), DPPH (1,1‐diphenyl‐2‐picrylhydrazyl), ABTS•+ (2,2‐azino‐bis‐3‐ethyl benzothiazoline‐6‐sulphonic acid) radicals in a dose‐dependent manner. These results demonstrate that TAE protects DNA against ADR‐induced damage. Copyright © 2008 John Wiley & Sons, Ltd.
Antioxidant activity of flavonoids in isolated mitochondria
Authors: Dorta Daniel J. , Pigoso Acácio A. , Mingatto Fábio E. , Rodrigues Tiago , Pestana Cezar R. , Uyemura Sérgio A. , Santos Antonio C. , Curti Carlos 
Published: August 2008

AbstractMitochondria are important intracellular sources and targets of reactive oxygen species (ROS), while flavonoids, a large group of secondary plant metabolites, are important antioxidants. Following our previous study on the energetics of mitochondria exposed to the flavonoids quercetin, taxifolin, catechin and galangin, the present work addressed the antioxidant activity of these compounds (1–50 µmol/L) on Fe2+/citrate‐mediated membrane lipid peroxidation (LPO) in isolated rat liver mitochondria, running in parallel studies of their antioxidant activity in non‐organelle systems. Only quercetin inhibited the respiratory chain of mitochondria and only galangin caused uncoupling. Quercetin and galangin were far more potent than taxifolin and catechin in affording protection against LPO (IC50= 1.23 ± 0.27 and 2.39 ± 0.79 µmol/L, respectively), although only quercetin was an effective scavenger of both 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and superoxide radicals. These results, together with the previous study, suggest that the 2,3‐double bond in conjugation with the 4‐oxo function in the flavonoid structure are major determinants of the antioxidant activity of flavonoids in mitochondria, the presence of ano‐di‐OH structure on the B‐ring, as occurs in quercetin, favours this activity via superoxide scavenging, while the absence of this structural feature in galangin, favours it via a decrease in membrane fluidity and/or mitochondrial uncoupling. Copyright © 2008 John Wiley & Sons, Ltd.
Antibacterial potential of Antarctic lichens against human pathogenic Gram‐positive bacteria
Authors: Paudel Babita , Bhattarai Hari Datta , Lee Jin Sung , Hong Soon Gyu , Shin Hyun Woung , Yim Joung Han 
Published: August 2008

AbstractExtracts from five Antarctic lichens (L3, Stereocaulon alpinum; L5, Ramalina terebrata; L6, Caloplaca sp.; L8, Lecanora sp.; and L17, Caloplaca regalis) were tested for antimicrobial activities against several clinically important microbes by disk diffusion. The minimum inhibitory concentration (MIC) of each extract was determined by a broth dilution method. Extracts from L3, L5, L6 and L8 were active against two Gram(+) strains. B. subtilis was more sensitive to lichen extracts (except L5) than S. aureus. The MIC of lichen extracts against B. subtilis and S. aureus was observed from 36.7 ± 0.3 to 953.8 ± 85.8 µg/mL and 68.5 ± 0.6 to >1000 µg/mL, respectively. Comparisons of MIC values of Antarctic lichen crude extracts to previously published MIC values of some reported lichen metabolites against Gram(+) bacteria indicated that Antarctic lichens might be an enriched source of effective antibacterial agents against clinically relevant Gram(+) species. Copyright © 2008 John Wiley & Sons, Ltd.
Food supplementation with an olive (Olea europaea L.) leaf extract reduces blood pressure in borderline hypertensive monozygotic twins
Authors: Perrinjaquet‐Moccetti Tania , Busjahn Andreas , Schmidlin Caesar , Schmidt Annette , Bradl Barbara , Aydogan Cem 
Published: August 2008

AbstractHypertension is a harmful disease factor that develops unnoticed over time. The treatment of hypertension is aimed at an early diagnosis followed by adequate lifestyle changes rather than pharmacological treatment. The olive leaf extract EFLA®943, having antihypertensive actions in rats, was tested as a food supplement in an open study including 40 borderline hypertensive monozygotic twins. Twins of each pair were assigned to different groups receiving 500 or 1000 mg/day EFLA®943 for 8 weeks, or advice on a favourable lifestyle. Body weight, heart rate, blood pressure, glucose and lipids were measured fortnightly. Blood pressure changed significantly within pairs, depending on the dose, with mean systolic differences of ≤6 mmHg (500 mg vs control) and ≤13 mmHg (1000 vs 500 mg), and diastolic differences of ≤5 mmHg. After 8 weeks, mean blood pressure remained unchanged from baseline in controls (systolic/diastolic: 133 ± 5/77 ± 6 vs 135 ± 11/80 ± 7 mmHg) and the low‐dose group (136 ± 7/77 ± 7 vs 133 ± 10/76 ± 7), but had significantly decreased for the high dose group (137 ± 10/80 ± 10 vs 126 ± 9/76 ± 6). Cholesterol levels decreased for all treatments with significant dose‐dependent within‐pair differences for LDL‐cholesterol. None of the other parameters showed significant changes or consistent trends. Concluding, the study confirmed the antihypertensive and cholesterol‐lowering action of EFLA®943 in humans. Copyright © 2008 John Wiley & Sons, Ltd.
Gas‐phase proton‐transfer pathways in protonated histidylglycine
Authors: MacDonald Brandon I. , Thachuk Mark 
Published: August 2008

AbstractPathways for proton transfer in the histidylglycine cation are examined in the gas‐phase environment with the goal of understanding the mechanism by which protons may become mobile in proteins with basic amino acid residues. An extensive search of the potential energy surface is performed using density functional theory (DFT) methods. After corrections for zero‐point energy are included, it is found that all the lowest energy barriers for proton transfer between the N‐terminus and the imidazole ring have heights of only a few kcal/mol, while those between the imidazole ring and the backbone amide oxygen have heights of approximately 15 kcal/mol when the proton is moving from the ring to the backbone and only a few kcal/mol when moving from the backbone to the imidazole ring. In mass spectrometric techniques employing collision‐induced dissociation to dissociate protein complex ions or to fragment peptides, these barriers can be overcome, and the protons mobilized. Copyright © 2008 John Wiley & Sons, Ltd.
Oncogenesis by retroviruses: old and new paradigms
Authors: Maeda Naoyoshi , Fan Hung , Yoshikai Yasunobu 
Published: August 2008

AbstractRetroviruses are associated with a variety of diseases including an array of malignancies, immunodeficiencies and neurological disorders. In particular, studies of oncogenic retroviruses established fundamental principles of modern molecular cancer biology. Studies of avian Rous sarcoma virus (RSV) led to the discovery of the viral oncogene src, and this was followed by the discovery of other viral oncogenes in retroviruses of mammals including rodents, cats, monkeys and so forth. Studies of the viral oncogenes in turn led to the discovery of cellular proto‐oncogenes in the host genome; cellular oncogenes have been shown to be activated in a variety of human cancers, including those with no viral involvement. Oncogenic animal retroviruses can be divided into two groups based on their mechanisms of tumourigenesis, acute transforming retroviruses and nonacute retroviruses. Acute transforming retroviruses are typically replication defective and they induce tumours rapidly due to expression of their viral oncogenes. Nonacute retroviruses are replication competent and they induce tumours with longer latencies, by activating cellular proto‐oncogenes in the tumour cells; this results from insertion of proviral DNA in the vicinity of the activated proto‐oncogene. More recently, human T‐cell leukaemia virus type I (HTLV‐I) was discovered as an etiological agent of human cancer (adult T‐cell leukaemia [ATL]); this virus also encodes regulatory genes some of which are important for its oncogenic potential. Most recently, the retroviral structural protein Envelope (Env) has been shown to be directly involved in oncogenic transformation for certain retroviruses. Env‐induced transformation is a new paradigm for retroviral oncogenesis. In this review, we will summarise research on retrovirus oncogenic transformation over the past 100 years since the first published report of an oncogenic virus with particular attention to Env‐induced transformation. Copyright © 2008 John Wiley & Sons, Ltd.
Dose‐escalation designs in oncology: ADEPT and the CRM
Authors: Shu Jianfen , O'Quigley John 
Published: August 2008

AbstractThe ADEPT software package is not a statistical method in its own right as implied by Gerke and Siedentop (Statist. Med. 2008; DOI: 10.1002/sim.3037). ADEPT implements two‐parameter CRM models as described in O'Quigley et al. (Biometrics 1990; 46(1):33–48). All of the basic ideas (use of a two‐parameter logistic model, use of a two‐dimensional prior for the unknown slope and intercept parameters, sequential estimation and subsequent patient allocation based on minimization of some loss function, flexibility to use cohorts instead of one by one inclusion) are strictly identical. The only, and quite trivial, difference arises in the setting of the prior. O'Quigley et al. (Biometrics 1990; 46(1):33–48) used priors having an analytic expression whereas Whitehead and Brunier (Statist. Med. 1995; 14:33–48) use pseudo‐data to play the role of the prior. The question of interest is whether two‐parameter CRM works as well, or better, than the one‐parameter CRM recommended in O'Quigley et al. (Biometrics 1990; 46(1):33–48). Gerke and Siedentop argue that it does. The published literature suggests otherwise. The conclusions of Gerke and Siedentop stem from three highly particular, and somewhat contrived, situations. Unlike one‐parameter CRM (Biometrika 1996; 83:395–405; J. Statist. Plann. Inference 2006; 136:1765–1780; Biometrika 2005; 92:863–873), no statistical properties appear to have been studied for two‐parameter CRM. In particular, for two‐parameter CRM, the parameter estimates are inconsistent. This ought to be a source of major concern to those proposing its use. Worse still, for finite samples the behavior of estimates can be quite wild despite having incorporated the kind of dampening priors discussed by Gerke and Siedentop. An example in which we illustrate this behavior describes a single patient included at level 1 of 6 levels and experiencing a dose limiting toxicity. The subsequent recommendation is to experiment at level 6! Such problematic behavior is not common. Even so, we show that the allocation behavior of two‐parameter CRM is very much less stable than that of one‐parameter CRM. Copyright © 2008 John Wiley & Sons, Ltd.
Multiple imputation to correct for partial verification bias revisited
Authors: de Groot J. A. H. , Janssen K. J. M. , Zwinderman A. H. , Moons K. G. M. , Reitsma J. B. 
Published: August 2008

AbstractPartial verification refers to the situation where a subset of patients is not verified by the reference (gold) standard and is excluded from the analysis. If partial verification is present, the observed (naive) measures of accuracy such as sensitivity and specificity are most likely to be biased. Recently, Harel and Zhou showed that partial verification can be considered as a missing data problem and that multiple imputation (MI) methods can be used to correct for this bias. They claim that even in simple situations where the verification is random within strata of the index test results, the so‐called Begg and Greenes (B&G) correction method underestimates sensitivity and overestimates specificity as compared with the MI method. However, we were able to demonstrate that the B&G method produces similar results as MI, and that the claimed difference has been caused by a computational error. Additional research is needed to better understand which correction methods should be preferred in more complex scenarios of missing reference test outcome in diagnostic research. Copyright © 2008 John Wiley & Sons, Ltd.
Carbon Nanotubes as Liquid Crystals
Authors: Zhang Shanju , Kumar Satish 
Published: August 2008

AbstractCarbon nanotubes are the best of known materials with a combination of excellent mechanical, electronic, and thermal properties. To fully exploit individual nanotube properties for various applications, the grand challenge is to fabricate macroscopic ordered nanotube assemblies. Liquid‐crystalline behavior of the nanotubes provides a unique opportunity toward reaching this challenge. In this Review, the recent developments in this area are critically reviewed by discussing the strategies for fabricating liquid‐crystalline phases, addressing the solution properties of liquid‐crystalline suspensions, and exploiting the practical techniques of liquid‐crystal routes to prepare macroscopic nanotube fibers and films.magnified image