bluuebunny/crossref_metadata_2025 huggingface dataset:
Genotype-specific interactions of insulin resistance, steatosis, and fibrosis in chronic hepatitis C
Authors: Cua Ian Homer Y. , Hui Jason M. , Kench James G. , George Jacob
Published: May 2008

The interaction between insulin resistance (IR), steatosis and genotype to fibrosis in chronic hepatitis C virus (HCV) infection has not been comprehensively assessed. We hypothesized that IR is a key mediator for the development of both steatosis and fibrosis in 346 untreated, nondiabetic patients solely infected with either genotype 1 or 3. We examined for genotype-specific interactions between IR, steatosis and fibrosis by performing subgroup analyses. Because cirrhosis is known to cause IR, we repeated the analysis in a cohort of 313 noncirrhotic HCV-infected patients. We confirmed the impact of IR on fibrosis by analysis of 153 lean subjects in whom any effect of steatosis would be minimized. In HCV genotype 3 patients, increased steatosis was linked to high viral load (

P

= 0.001), and was not associated with fibrosis (

P

= 0.1). In contrast, body mass index (

P

= 0.04) and homeostasis model assessment of insulin resistance (HOMA-IR) (

P

= 0.01) contributed directly to steatosis in HCV genotype 1. HOMA-IR rather than steatosis was independently associated with fibrosis for both HCV genotype 1 (OR, 3.22;

P

= 0.02) and genotype 3 (OR, 3.17;

P

= 0.04). Exclusion of cirrhotic subjects did not alter the findings with respect to the greater contribution of IR compared to hepatic steatosis, as a predictor of fibrosis (

P

= 0.02). Genotype-specific subgroup analyses did not alter this finding. The extent of HOMA-IR remained significantly associated with fibrosis in lean patients, independent of the confounding effect of body mass index on IR (OR, 8.02;

P

= 0.003).

Conclusion:

IR is a major independent determinant of fibrosis in chronic HCV infection, regardless of the genotype and the severity of liver damage. (Hepatology 2008.)
Pathogenic role of natural killer T and natural killer cells in acetaminophen-induced liver injury in mice is dependent on the presence of dimethyl sulfoxide
Authors: Masson Mary Jane , Carpenter Leah D. , Graf Mary L. , Pohl Lance R.
Published: May 2008

Dimethyl sulfoxide (DMSO) is commonly used in biological studies to dissolve drugs and enzyme inhibitors with low solubility. Although DMSO is generally thought of as being relatively inert, it can induce biological effects that are often overlooked. An example that highlights this potential problem is found in a recent report demonstrating a pathogenic role for natural killer T (NKT) and natural killer (NK) cells in acetaminophen-induced liver injury (AILI) in C57Bl/6 mice in which DMSO was used to facilitate acetaminophen (APAP) dissolution. We report that NKT and NK cells do not play a pathologic role in AILI in C57Bl/6 mice in the absence of DMSO. Although AILI was significantly attenuated in mice depleted of NKT and NK cells prior to APAP treatment in the presence of DMSO, no such effect was observed when APAP was dissolved in saline. Because of this unexpected finding, the effects of DMSO on hepatic NKT and NK cells were subsequently investigated. When given alone, DMSO activated hepatic NKT and NK cells

in vivo

as evidenced by increased NKT cell numbers and higher intracellular levels of the cytotoxic effector molecules interferon-γ (IFN-γ) and granzyme B in both cell types. Similarly, when used as a solvent for APAP, DMSO again increased NKT cell numbers and induced IFN-γ and granzyme B expression in both cell types.

Conclusion:

These data demonstrate a previously unappreciated effect of DMSO on hepatic NKT and NK cells, suggesting that DMSO should be used cautiously in experiments involving these cells. (Hepatology 2008.)
Decompositions of highly connected graphs into paths of length 3
Authors: Thomassen Carsten
Published: May 2008

We prove that a 171‐edge‐connected graph has an edge‐decomposition into paths of length 3 if and only its size is divisible by 3. It is a long‐standing problem whether 2‐edge‐connectedness is sufficient for planar triangle‐free graphs, and whether 3‐edge‐connectedness suffices for graphs in general. © 2008 Wiley Periodicals, Inc. J Graph Theory 58: 286–292, 2008
Dynamic mechanical and dielectric relaxation characteristics of microcellular rubber composites
Authors: Mahapatra S. P. , Sridhar V. , Tripathy D. K. , Kim J. K. , Kwak H.
Published: May 2008

An in‐depth study of the surface characteristics of novel conductive carbon black Ensaco 350G has been carried out using XPS and high‐resolution vacuum FTIR. Both methods showed the existence of oxygen containing surface groups like carboxyls, carbonyls, etc. Dynamic mechanical analysis and dielectric relaxation spectra of conductive carbon black (Ensaco 350G) reinforced microcellular EPDM composites were used to study the relaxation behavior as a function of temperature (−90 to +100°C) and frequency (100–106 Hz). The effect of filler and blowing agent loadings on dynamic mechanical and dielectric relaxation characteristics has been investigated. The effect of filler and blowing agent loadings on glass transition temperature was marginal for all the composites (Tg value was in the range of −37 to −32°C), which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. The variation in the real and imaginary parts of the complex impedance with frequency has been studied as a function of filler and blowing agent loading. Additionally, an in‐depth study of the surface characteristics of the filler using XPS, high‐resolution vacuum FTIR and Raman spectra is also reported. Copyright © 2008 John Wiley & Sons, Ltd.
Microwave step‐growth polymerization of 5‐(4‐methyl‐2‐phthalimidylpentanoylamino)isophthalic acid with different diisocyanates
Authors: Mallakpour Shadpour , Dinari Mohammad
Published: May 2008

The utilization of microwave energy in polymer synthesis is a fast growing field of research leading to a more rapid and cleaner polymerization process. In order to synthesize novel optically active monomer 5‐(4‐methyl‐2‐phthalimidylpentanoylamino)isophthalic acid (6), the reaction of phthalic anhydride with l‐leucine was carried out in an acetic acid solution and 4‐methyl‐2‐phthalimidylpentanoic acid as an imide acid was obtained in good yield. Then, it was converted to 4‐methyl‐2‐phthalimidylpentanoyl chloride by treatment with thionyl chloride. This acid chloride was reacted with 5‐aminoisophthalic acid and the novel bulky aromatic amide‐imide chiral monomer 6 was obtained in high yield and was characterized with spectroscopy techniques as well as specific rotation and elemental analysis. Polycondensation of monomer 6 with different diisocyanates such as 4,4′‐methylenebis(phenyl isocyanate), toluene‐2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate was performed by two different methods: microwave irradiation and classical heating polymerization techniques in the presence of various catalysts and without a catalyst. The microwave polymerization technique provides a new way for the production of polymers at high rates. The resulting novel optically active polyamides have inherent viscosities in the range of 0.25–0.63 dl/g. They show good thermal stability and are soluble in amide‐type solvents. The obtained polyamides were characterized by FT‐IR, 1H‐NMR spectroscopy, elemental analyses, specific rotation, and thermal analyses methods. Copyright © 2008 John Wiley & Sons, Ltd.
Proteomic response to iron deficiency in tomato root
Authors: Li Jie , Wu Xu‐Dong , Hao Shan‐Ting , Wang Xiu‐Jie , Ling Hong‐Qing
Published: May 2008

To know the root adjustment in response to iron deficiency, differentially displayed proteins in tomato roots of wild type and its iron uptake inefficient mutant T3238fer were analyzed by 2‐DE and MALDI‐TOF MS‐based proteomic method under iron sufficiency and deficiency. Ninety‐seven proteins were identified, 63 of them were classified in various metabolic pathways. About 40 proteins involved in starch degradation, TCA and ascorbate cycles were upregulated under iron deficiency and grouped in a network together with glycolysis, whereas proteins for fructose metabolism were decreased. Proteins involved in methionine synthesis, cell wall synthesis, mitochondria ATP synthesis, vacuole ATPase, HSP70/90, etc. also revealed enhanced expression under iron deficiency, while proteins about redox homeostasis, transcription factors, kinases, etc. showed diversified changes. The responses are closely associated with energy metabolism, organic acid formation, root morphological change, redox and sulfur homeostasis, and signal transduction, which enhance iron uptake, reutilization and other adaptive changes. Most of the proteins affected by iron deficiency and fer mutation showed similar effect on individual proteins or pathways, but the independent function of FER to iron deficiency were statistically indicated.
Biocompost from sugar distillery effluent: effect on metribuzin degradation, sorption and mobility
Authors: Singh Neera
Published: May 2008

BACKGROUND: Metribuzin (4‐amino‐6‐tert‐butyl‐4,5‐dihydro‐3‐methylthio‐1,2,4‐triazin‐5‐one) is weakly sorbed in soils and therefore leaches easily to lower soil profiles and results in loss of activity. Soil amendments play an important role in the management of runoff and leaching losses of pesticides from agricultural fields. Therefore, the effect of biocompost from sugarcane distillery effluent on metribuzin degradation and mobility was studied in a sandy loam soil.

RESULTS: Metribuzin was more persistent in biocompost‐unamended (T‐0) flooded soil (t1/2 − 41.2 days) than in non‐flooded (t1/2 − 33.4 days) soil. Biocompost application at the rate of 2.5 and 5.0% (T‐1 and T‐2) in non‐flooded soils increased metribuzin persistence, but no significant effect was observed on persistence in flooded soils. Freundlich adsorption constants (Kf) for treatments T‐0, T‐1 and T‐2 were 0.43, 0.64 and 1.13 respectively, suggesting that biocompost application caused increased metribuzin sorption. Leaching studies in packed soil columns indicated that biocompost application affected both metribuzin breakthrough time and maximum concentration in the leachate. Leaching losses of metribuzin were drastically reduced from 93% in control soil (T‐0) to 65% (T‐1) and 31% (T‐2) in biocompost‐amended soils.

CONCLUSION: Biocompost from sugarcane distillery effluent can be used effectively to reduce downward mobility of metribuzin in low‐organic‐matter sandy loam soil. Copyright © 2008 Society of Chemical Industry
Relationship between grain‐boundary capacitance and bulk shallow donors in SnO2 polycrystalline semiconductor
Authors: Bueno P. R. , Santos M. A. , Ramírez M. A. , Tararam R. , Longo E. , Varela J. A.
Published: May 2008

The relationship between grain‐boundary capacitance and extrinsic shallow donors caused by Nb addition to SnO2·CoO binary polycrystalline system has been investigated by means of combined techniques such as I –V characteristic response, complex impedance and capacitance analysis and electrostatic force microscopy. The estimated role of the Nb doping is to increase the concentration of shallow donors that are capable of enhancing the electronic donation to grain‐boundary acceptors. This effect leads to the formation of potential barriers at grain boundaries with a simultaneous increase of grain‐boundary capacitance and non‐Ohmic features of the polycrystalline device doped with Nb atoms. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Visible cathodoluminescence from carbon nanotubes: the role of impurities
Authors: Barberio M. , Barone P. , Bonanno A. , Camarca M. , Oliva A. , Pingitore V. , Xu F.
Published: May 2008

Luminescence spectra obtained by electron bombardment (cathodoluminescence, CL) on bundles of pristine single walled (SWCNT) and multi walled carbon nanotubes (MWCNT) show several common peaks at 1.76, 1.94, 2.06, and 2.22 eV which disappear after heating the samples up to 1300 K. We show that these transitions are extrinsic to nanotubes and originate from nickel oxide impurities, residual catalyst material used in the growth processes. Our conclusions are confirmed by X‐ray photoelectron spectroscopy (XPS) and energy dispersed X‐ray analysis measurements. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐sustained current oscillations in a multi‐quantum‐well spin polarized structure with normal contacts
Authors: Escobedo R. , Carretero M. , Bonilla L. L. , Platero G.
Published: May 2008

Self‐sustained current oscillations (SSCO) are found in a nonlinear electron spin dynamics model of a n‐doped dc voltage biased semiconductor II–VI multi‐quantum well structure (MQWS) having one or more of its wells doped with Mn. Provided one well is doped with magnetic impurities, spin polarized current can be obtained even if normal contacts have been attached to this nanostructure. Under certain conditions, the system exhibits static electric field domains and stationary current or moving domains and time‐dependent oscillatory current. We have found SSCO for nanostructures with four or more QWs. The presence of SSCO depends on the spin‐splitting induced by both, the exchange interaction and the external magnetic field. We also calculate the minimal doping density needed to have SSCO, and a bound above which SSCO disappear. This range is crucial to design a device behaving as a spin polarized current oscillator. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation and characterization of a nanostructured dental composite
Authors: Nicola Oana , Andronescu Ecaterina , Ghitulica Cristina , Birsan Mihaela , Dinu Elena
Published: May 2008

One of the major objectives of dental medicine that should be mentioned is the use of increasingly powerful materials of coronary restoration, as regards to their biomechanical, biofunctional and bio‐prophylactic characteristics. Nanotechnologies often provide the techniques used in the field of filler particles. Solutions to obtain a first generation of composite material with nanoparticles with dimensions between 5–75 nm have been successfully tested. It has been important to also obtain conglomerates with dimensions between 0.2–0.6 mm, that should be present. The present paper describes the preparation through sol–gel methods and aims to characterize ceramic nanoparticles used as filling inorganic materials for dental composites for esthetical restorations. We have obtained nanometric powders of silica and zirconia/silica. Thermal treatments were conducted at temperatures between 700 °C and 1200 °C for 2 hours. The powders had been analyzed as regards to their mineralogical composition, granulometric distribution and microstructure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic field‐dependence study of the magnetocaloric properties of a superparamagnetic nanoparticle system: a Monte Carlo simulation
Authors: Serantes D. , Baldomir D. , Pereiro M. , Rivas J. , Vázquez‐Vázquez C. , Buján‐Núñez M. C. , Arias J. E.
Published: May 2008

The influence of the applied magnetic field on the magnetocaloric properties of a fine magnetic particle system has been studied using a Monte Carlo technique. By simulating zero field cooling (ZFC) curves under different strengths of the applied magnetic field, we have analyzed the variation of the entropy for temperatures above the maximum of the ZFC curves, where the process is reversible. The entropy curves have been observed to behave in a different fashion at low values of the magnetic field, where the peak only slightly shifts to higher temperatures with increasing fields. For larger fields, the peak rapidly shifts to higher temperatures, while the overall shape of the curve broadens over a wide temperature range. It is also observed that the blocking temperature as a function of the magnetic field shows the feature of a change from a bell‐like shape to a monotonically decreasing function, resembling what is found experimentally for intermediate values of the sample concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gas chromatographic equivalent chain lengths of fatty acid methyl esters on a silar 10C glass capillary column
Authors: Scholfield C. R.
Published: May 2008

Gas chromatographic equivalent chain lengths have been determined for a number of fatty acid methyl ester isomers on a Silar 10C glass capillary column at 170 C. The results are comparable with others published for polycyanopropylsiloxane columns.
Separation of methyl malvalate from methyl sterculate
Authors: Pawlowski N. E. , Loveland P. M. , Sinnhuber R. O.
Published: May 2008

Methyl malvalate and sterculate, labile and differing by a single methylene, are difficult to separate completely. They have been separated in our laboratory by high vacuum spinning band distillation. Each of these fatty esters has been prepared completely free of the other.
Improved procedure for titrating cyclopropene esters with hydrogen bromide
Authors: Feuge R. O. , Codifer L. P. , Zeringue H. J.
Published: May 2008

The titration of cyclopropenes in cottonseed and other oils with hydrogen bromide was improved by changes in the preparation of the sample and the titration. Methanolysis of the oil under selected conditions with a large excess of alkaline catalyst (sodium methoxide or tetramethylammonium hydroxide) yielded methyl esters free of oxidation products and partial glycerides and eliminated the need for treatment with a large amount of activated alumina, which disproportionates methyl esters. The color indicator, 4‐phenylazodi‐phenylamine, exhibited great sensitivity in toluene at 25 C. The best procedure consisted of titrating methyl esters with hydrogen bromide at 60–65 C to just past the end‐point, cooling to about 25 C, and back‐titrating with aniline in toluene. With 10‐ to 2‐g samples containing less than 1% cyclopropenes, reproducibility usually was within ±0.003% of the average value.
Making homogeneous and fine droplet O/W emulsions using nonionic surfactants
Authors: Sagitani Hiromichi
Published: May 2008

In many emulsion systems, creaming occurs during the first stage of emulsion breakdown. To reduce the rate of creaming, emulsions having small and uniform droplets are desirable. In this work, types and HLB of nonionic surfactants, emulsification methods, and combinations of oils and nonionic surfactants were investigated in order to make stable and homogeneous emulsions. Emulsification was attained by dissolving the surfactants in the oil phases. The addition speed and volume of water to the oil phases were important factors affecting the emulsion droplet size. The change of the solute state in the process of emulsification was observed stage by stage, and the mechanism of emulsification was elucidated. Homogeneous emulsions were formed in the HLB region, showing liquid crystalline and gel phases in the emulsifying process. The addition speed of water to the oil phase was very important in forming the liquid crystalline and gel phases. Polyoxyethylene(n)sorbitan monostearate could emulsify three kinds of oils (hydrocarbon, fatty acid ester and triglyceride). Polyoxyethylene(n)alkyl ether could emulsify hydrocarbon and fatty acid ester. Polyoxyethylene(n)‐monostearate could emulsify only hydrocarbon. Surfactants with proper HLB which were soluble in the oil phase and in the presence of a very small amount of water formed a stable emulsion. The solubility state of oil and surfactant was the key to making a fine emulsion.
Impact of the Degree of Liver Resection on Survival for Patients with Multiple Liver Metastases from Colorectal Cancer
Authors: Tanaka Kuniya , Shimada Hiroshi , Matsumoto Chizuru , Matsuo Kenichi , Takeda Kazuhisa , Nagano Yasuhiko , Togo Shinji
Published: May 2008

Background

Although the degree of hepatic resection has been found to be a key aspect of tumor stimulation, the differences in clinical outcome between a massive liver resection and a less extensive resection for multiple colorectal metastases have not been well studied. The purpose of this study was to clarify the impact of the extent of liver resection on survival outcome.

Methods

Clinicopathologic data were available for 85 patients who were surgically treated for four or more liver metastases. Forty‐nine patients who underwent a major hepatic resection were compared with patients who underwent minor hepatic resections (n = 36).

Results

As the patients undergoing major resection were more likely to have multiple (p = 0.014) and large tumors (p = 0.021) compared to the minor‐resection patients, their overall survival was worse (p = 0.046) and the disease‐free rate tended to be poorer. By multivariate analysis of the cohorts, the only independent factor affecting survival was the number of liver tumors (≤5 or ≥6; relative risk [RR] = 0.427; p = 0.014). When patients with six or more metastases were selected and analyzed, the overall survival of patients who had a major resection was significantly poorer than those who had minor resections (p = 0.028), although the clinical characteristics were comparable between the two groups.

Conclusion

Although the extent of hepatectomy was not an independent prognosticator, minor resections for multiple colorectal metastases may offer a long‐term survival advantage compared to a major resection.
CSF monoamine metabolites and neuropeptides in depressed patients before and after electroconvulsive therapy
Authors: Nikisch Georg , Mathé Aleksander A.
Published: May 2008

Antidepressant drugs affect monoamines and neuropeptides in human cerebrospinal fluid (CSF) and in rodent brain. The purpose of this study was to investigate if also electroconvulsive therapy (ECT) affects these compounds in a similar manner in the CSF of depressed patients. Homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and corticotropin-releasing hormone (CRH)-like immunoreactivity (-LI) and neuropeptide Y (NPY)-LI were determined in CSF in six drug resistant patients with major depression. Lumbar puncture was performed at baseline and after completion of eight ECTs. ECT was associated with an increase in NPY-LI (p = 0.009) and a decrease in CRH-LI (p ≤ 0.001). HVA (p = 0.003) and 5-HIAA (p = 0.002) were significantly increased after the ECT. Findings of NPY increase and CRH decrease were similar to those following chronic treatment with citalopram, indicating that these changes might constitute one of the common underpinnings of antidepressant treatment modalities.
Association between age at onset and clinical features of schizophrenia: The Northern Finland 1966 birth cohort study
Authors: Luoma Suvi , Hakko Helinä , Ollinen Taru , Järvelin Marjo-Riitta , Lindeman Sari
Published: May 2008

Purpose

To study the association between age at onset and the clinical picture of schizophrenia in an unselected young birth cohort.

Subjects and methods

The study sample consists of 98 (64 males and 34 females) individuals with DSM-III-R schizophrenia collected from the Northern Finland 1966 birth cohort. Firstly, subjects were divided into very early- and young-onset subgroups by using the median age at onset (22 years in males and 20 in females), as a cut-off point. Secondly, we used age at onset as a continuous variable. Clinical features of schizophrenia were assessed using the Operational Criteria Checklist for Psychotic Illnesses (OCCPI).

Results

Inappropriate affect, positive thought disorder and deterioration from premorbid level of function associate with very early-onset schizophrenia, while slowed activity and dysphoria relate to young-onset. These symptoms correlate significantly with the age at onset.

Discussion

Differences in the clinical picture associating to the age at onset of schizophrenia are seen early.

Conclusion

These findings indicate that certain symptoms of schizophrenia are dependent on the age at onset, and schizophrenia occurring initially in early life has some typical features. Using the age at onset as a continuous variable is independent of arbitrary cut-off points and produces more explicable results.
Theological determinism and the problem of evil
Authors: JUDISCH NEAL
Published: May 2008

I argue that the free-will defence need not presuppose a libertarian conception of freedom and therefore need not beg the question against compatibilists. I present three versions of theological determinism, each of which is inconsistent with freedom on compatibilist-friendly principles, and then argue that what generates the inconsistency – viz, that (1) God intentionally necessitates all human actions, and (2) no human has it within her power to influence causally God's will – is entailed by any version of theological determinism. Contrary to widespread opinion, therefore, the viability of the free-will defence does not depend upon the viability of libertarianism per se but on the falsity of theological determinism.
Quiet time equatorial F region vertical plasma drift model derived from ROCSAT‐1 observations
Authors: Fejer Bela G. , Jensen John W. , Su Shin‐Yi
Published: May 2008

We have used five years of measurements on board the ROCSAT‐1 satellite to develop a detailed quiet time global empirical model for equatorial F region vertical plasma drifts. This model describes the local time, seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions. The model results are in excellent agreement with measurements from the Jicamarca radar and also from other ground‐based and in situ probes. We show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier, especially during December and June solstice. The late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons, the morning and afternoon December solstice drifts have significantly different longitudinal dependence, and the daytime upward drifts have strong wave number‐four signatures during equinox and June solstice. The largest evening upward drifts occur during equinox and December solstice near the American sector. The longitudinal variations of the evening prereversal velocity peaks during December and June solstice are anti‐correlated, which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere.
Energetic electron distributions fitted with a relativistic kappa‐type function at geosynchronous orbit
Authors: Xiao Fuliang , Shen Chenglong , Wang Yuming , Zheng Huinan , Wang Shui
Published: May 2008

In this study, we utilize a recently introduced relativistic kappa‐type (KT) distribution function to model the omnidirectional differential flux of energetic electrons observed by the SOPA instrument on board the 1989–046 and LANL‐01A satellites at geosynchronous orbit. We derive a useful correlation between the differential flux and the distribution of particles which can directly offer those best fitting parameters (e.g., the number density N, the thermal characteristic speed θ and the spectral index κ) strongly associated with evaluation of the electromagnetic wave instability. We adopt the assumption of a nearly isotropic pitch angle distribution (PAD) and the typical LMFIT function in the program IDL to perform a non‐linear least squared fitting, and find that the new KT distribution fits well with the observed data during different universal times both in the lower and higher energies. We also carry out the direct comparisons with the generalized Lorentzian (kappa) distribution and find that kappa distribution fits well with observational data at the relatively lower energies but display deviations at higher energies, typically above hundreds of keV. Furthermore, the fitting spectral index κ basically takes 4, 5 or 6 while the fitting parameters N and θ are quite different due to different differential fluxes of electrons at different universal times. These results, which are applied to the case of a nearly isotropic PAD, demonstrate that the particle flux satisfies the power law not only at the lower energies but also at the relativistic energies, and the new KT distribution may present valuable insights into the dynamical features in those space plasmas (e.g., the Earth's outer radiation belts and the inner Jovian magnetosphere) where highly energetic particles exist.
How a silver dendritic mesocrystal converts to a single crystal
Authors: Fang Jixiang , Ding Bingjun , Song Xiaoping , Han Yong
Published: May 2008

In this paper, we demonstrate how a silver dendrite transforms from mesocrystal into single crystal and the stability for a dendritic silver mesocrystal within a Sn∕AgNO3 galvanic replacement reaction. Our findings provide the direct evidence and visible picture of the transformation from mesocrystal to single crystalline structure and further confirm the particle-mediated crystallization mechanism. At the initial stage of the transformation, there is a crystallographic fusion process, dominated by oriented attachment mechanism. Ostwald ripening also plays an important role in forming smooth surface and regular shape of the final nanocrystal.
Analysis of the interband optical transitions: Characterization of synthetic DNA band structure
Authors: Díaz Elena
Published: May 2008

We analyze the band structure and interband optical transitions in a dangling backbone ladder DNA model. Using this model, semiconducting synthetic poly(G)-poly(C) DNA is studied by means of a tight-binding model traditionally used for transport studies. Numerical calculations for optical absorption spectra are also presented. By studying the eigenstates’ symmetries in uniform and nonuniform DNA chains, we conclude that, in both cases, the transitions are almost vertical in K space. The optical gap turns out larger than the electronic one, and an indirect band gap electronic structure for this DNA model is revealed. The effects of the environment, which are relevant for the wet form of DNA, are taken into account by introducing disorder in the backbone levels. We demonstrate that they affect more the spectra in the case of parallel polarization of the incoming light (with respect to the molecule axis). In such a case, the closure of the gap appears for a large enough disorder. We also consider the natural helix DNA conformation and find unusual selection rules for interband optical transitions. We propose that a comparison between the obtained spectra and the experiments can provide an insight into the electronic band structure of DNA.
Influence of structure characteristics on room temperature ferromagnetism of Ni-doped ZnO thin films
Authors: Yu W. , Yang L. H. , Teng X. Y. , Zhang J. C. , Zhang Z. C. , Zhang L. , Fu G. S.
Published: May 2008

The influence of structure characteristics on the ferromagnetism of Ni-doped ZnO (ZnO:Ni) thin films prepared by pulsed laser deposition has been investigated by magnetization and resistivity measurements. Structural and optical absorption analyses revealed that Ni has been incorporated into ZnO lattice as Ni2+ substituting for Zn2+ ions and the microstructure of the films becomes more inhomogeneous with increasing Ni content. The room temperature ferromagnetic (FM) behavior only occurs when Ni content is not high and the saturation magnetic moment per Ni atom decreases with increasing Ni content. No FM signal was detected for the film with 7at.% Ni content. Interestingly, the carrier density decreases with the increase of Ni doping from 1to5at.%, whereas an increase of carrier density is observed for 7at.% doped film, which indicates that carrier density alone cannot account for the FM property in ZnO:Ni films. All the results demonstrated that the microstructure of ZnO:Ni films gets more deteriorated with increasing Ni content and it is unfavorable for the long-range FM order in the ZnO:Ni films.
Influence of stress on the structural and dielectric properties of rf magnetron sputtered zinc oxide thin film
Authors: Menon Rashmi , Sreenivas K. , Gupta Vinay
Published: May 2008

Highly c axis oriented zinc oxide (ZnO) thin films have been prepared on 1737 Corning glass substrate by planar rf magnetron sputtering under varying pressure (10–50mTorr) and different oxygen percentage (40%–100%) in reactive gas mixtures. The as-grown ZnO thin films were found to have stress over a wide range from −6×1010to−9×107dynes∕cm2. The presence of stress depends strongly on processing conditions, and films become almost stress free under a unique combination of sputtering pressure and reactive gas composition. The studies show a correlation of stress with structural and electrical properties of the ZnO thin film. The stressed films possess high electrical conductivity and exhibits strong dielectric dispersion over a wide frequency (1kHz–1MHz). The dielectric constant ε′(ω) of stress free ZnO film was almost frequency independent and was close to the bulk value. The measured value of dc conductivity, σdc(ω) and ac conductivity σac(ω) of stress free ZnO film was 1.3×10−9 and 6.8×10−5Ω−1cm−1, respectively. The observed variation in the structural and electrical properties of ZnO thin film with stress has been analyzed in the light of growth kinetics.
The effect of lithium surface coatings on plasma performance in the National Spherical Torus Experiment
Authors: Kugel H. W. , Bell M. G. , Ahn J.-W. , Allain J. P. , Bell R. , Boedo J. , Bush C. , Gates D. , Gray T. , Kaye S. , Kaita R. , LeBlanc B. , Maingi R. , Majeski R. , Mansfield D. , Menard J. , Mueller D. , Ono M. , Paul S. , Raman R. , Roquemore A. L. , Ross P. W. , Sabbagh S. , Schneider H. , Skinner C. H. , Soukhanovskii V. , Stevenson T. , Timberlake J. , Wampler W. R. , Zakharov L.
Published: May 2008

National Spherical Torus Experiment [which M. Ono et al., Nucl. Fusion 40, 557 (2000)] high-power divertor plasma experiments have shown, for the first time, that benefits from lithium coatings applied to plasma facing components found previously in limited plasmas can occur also in high-power diverted configurations. Lithium coatings were applied with pellets injected into helium discharges, and also with an oven that directed a collimated stream of lithium vapor toward the graphite tiles of the lower center stack and divertor. Lithium oven depositions from a few milligrams to 1g have been applied between discharges. Benefits from the lithium coatings were sometimes, but not always, seen. These benefits sometimes included decreases in plasma density, inductive flux consumption, and edge-localized mode occurrence, and increases in electron temperature, ion temperature, energy confinement, and periods of edge and magnetohydrodynamic quiescence. In addition, reductions in lower divertor D, C, and O luminosity were measured.
In situ scanning tunneling microscopy studies of zinc(II) octaethylporphyrin arrays self-assembled on graphite and Au(111) surfaces in organic solution
Authors: Zou Zhi-Qiang , Chen Feng
Published: May 2008

We have prepared ordered adlayers of Zn(II) octaethylporphyrin (ZnOEP) molecules on highly oriented pyrolytic graphite (HOPG) and Au(111) surfaces in 1,2-dichlorobenzene solution. Packing structures and even internal structure of the molecules on these two substrates have been investigated in situ by scanning tunneling microscopy with the tip being immersed in the organic solution. The ZnOEP molecules have been found to adsorb on the HOPG surface with two pairs of ethyl groups curling down and the other two pairs curling up. This shape is consistent with the molecular geometry in the ZnOEP crystal. Compared to the HOPG substrate, the ZnOEP molecules adsorbed on the Au(111) substrate exhibit a lower resolution, and the order of the molecular adlayer is not as good as that on the HOPG surface due to the strong molecule-substrate interaction.
Molecular effects on turbulent diffusion and energy in a low speed closed flow
Authors: Akpovo Charlemagne C. , Johnson Joseph A. , Chabi Orou Jean B.
Published: May 2008

The coefficient of turbulent diffusion and the total turbulent energy are determined during the compression phase of a motored internal combustion engine with varying flow conditions and using intake gases with varying molecular weights. These turbulent parameters change with time and with intake gas molecular weight. However, under all flow conditions, both parameters first increase and then decrease with increasing molecular weight. In addition, a direct correlation is observed between the average values of the coefficient of turbulent diffusion and the average values of the total turbulent energy, irrespective of the molecular weight.
A virtual vibrational self-consistent-field method for efficient calculation of molecular vibrational partition functions and thermal effects on molecular properties
Authors: Hansen Mikkel Bo , Christiansen Ove , Toffoli Daniele , Kongsted Jacob
Published: May 2008

A new method is described for the calculation of molecular vibrational partition functions and thermal effects on molecular properties including an explicit account of anharmonicity. The approach is based on the vibrational self-consistent-field method. Partition functions and thermal averages of the energies calculated with the new method are generally in good agreement with the result of more accurate methods. At lower temperatures the method gives in addition good results for thermal averages of dipole moments and polarizabilities. The new method is much more efficient than explicit sum-over-states approaches previously used for calculation of thermal averages. Unlike the standard sum-over-states approach, the newly developed method is feasible for larger systems despite the formal exponential increase in the number of states with the size of the system. Thus, it is presently the only practical way for including an explicit treatment of anharmonicity in vibrational wave function based calculations of molecular vibrational partition functions and thermally averaged properties of larger molecules.
Theoretical analysis of adsorption-induced microcantilever bending
Authors: Zhang Ji-Qiao , Yu Shou-Wen , Feng Xi-Qiao , Wang Gang-Feng
Published: May 2008

Microcantilever-based techniques can be used to explore the autonomy and property of biomolecules (e.g., DNA and single actin filaments) which, in measurement, are adsorbed on the cantilever surface. Here, an energy method is presented to predict the cantilever deflection induced by adsorbed atoms/molecules. The cantilever is modeled as a sandwich beam containing two surface layers of a finite thickness and a bulk layer between them. The adsorptions of O atoms on Si(100) and Hg atoms on Au(100) are taken as two representative examples. We demonstrate that physisorption can induce distinctly different deformation behaviors of cantilevers, which depend not only on the adatoms but also on the substrate material. These results are consistent with relevant experimental observations. This study is helpful for optimal design of microcantilever-based measurement techniques.
Ru doping induced quantum paraelectricity in ferroelectric Sr0.9Ba0.1TiO3
Authors: Wei T. , Guo Y. J. , Wang P. W. , Yu D. P. , Wang K. F. , Lu C. L. , Liu J.-M.
Published: May 2008

We investigate the effect of Ru doping on the dielectric and ferroelectric behaviors of polycrystalline Sr0.9Ba0.1TiO3. It is observed that the Ru doping significantly suppresses the ferroelectric mode, as evidenced by the Raman spectroscopy at various temperatures. The enhanced quantum fluctuation associated with the incorporation of Ru4+ at B site is demonstrated, which transforms Sr0.9Ba0.1TiO3 from the ferroelectric state into a typical quantum paraelectric state.
Ring-breaking electron attachment to uracil: Following bond dissociations via evolving resonances
Authors: Gianturco Franco A. , Sebastianelli F. , Lucchese R. R. , Baccarelli I. , Sanna N.
Published: May 2008

Calculations are carried out at various distinct energies to obtain both elastic cross sections and S-matrix resonance indicators (poles) from a quantum treatment of the electron scattering from gas-phase uracil. The low-energy region confirms the presence of π* resonances as revealed by earlier calculations and experiments which are compared with the present findings. They turn out to be little affected by bond deformation, while the transient negative ions (TNIs) associated with σ* resonances in the higher energy region (∼8eV) indeed show that ring deformations which allow vibrational redistribution of the excess electron energy into the molecular target strongly affect these shape resonances: They therefore evolve along different dissociative pathways and stabilize different fragment anions. The calculations further show that the occurrence of conical intersections between σ* and π*-type potential energy surfaces (real parts) is a very likely mechanism responsible for energy transfers between different TNIs. The excess electron wavefunctions for such scattering states, once mapped over the molecular space, provide nanoscopic reasons for the selective breaking of different bonds in the ring region.
Swelling and shrinking kinetics of a lamellar gel phase
Authors: Fairhurst David J. , Baker Mark E. , Shaw Neil , Egelhaaf Stefan U.
Published: May 2008

We investigate the swelling and shrinking of Lβ lamellar gel phases composed of surfactant and fatty alcohol after contact with aqueous poly(ethyleneglycol) solutions. The height change Δh(t) is diffusionlike with a swelling coefficient S: Δh=St. On increasing polymer concentration, we observe sequentially slower swelling, absence of swelling, and finally shrinking of the lamellar phase. This behavior is summarized in a nonequilibrium diagram and the composition dependence of S quantitatively described by a generic model. We find a diffusion coefficient, the only free parameter, consistent with previous measurements.
Low-voltage, high-efficiency blue phosphorescent organic light-emitting devices
Authors: Lee Meng-Ting , Lin Jin-Sheng , Chu Miao-Tsai , Tseng Mei-Rurng
Published: May 2008

Low-voltage, high-efficiency blue phosphorescent organic light-emitting devices based on a composite emitter, including a wide-band-gap host, a carrier-transporting material, and an organometallic iridium dopant, have been demonstrated. The devices exhibit an external quantum efficiency of 12%, a power efficiency of 17lm∕W and a low voltage of 4.8V at a practical brightness of 1000cd∕m2 with a CIEx,y of (0.16, 0.35), which was twofold higher than that of using the typical emitter composed of host and dopant only. The dramatic enhancement in performance can be attributed to the transport of carriers into the wide-band-gap host, which can be promoted through doping a carrier-transporting material in emitter for increasing carrier recombination.
Near-field light emission from dark states excitonic occupations
Authors: Pistone G. , Savasta S. , Di Stefano O. , Martino G. , Girlanda R. , Portolan S.
Published: May 2008

We theoretically analyze the carrier capture and distribution among the available energy levels of a symmetric semiconductor quantum dot under continuous-wave excitation resonant with the barrier energy levels. At low temperature, all the dot level occupations but one monotonically decrease with energy. The uncovered exception, corresponding to the second (dark) energy level, displays a carrier density exceeding that of the lowest level by more than a factor two. The root cause is not radiative recombination before relaxation, but instead, carrier trapping due to the symmetry-induced suppression of radiative recombination. Such a behavior can be observed by collection-mode near-field optical microscopy.
Electron effective mean free path and thermal conductivity predictions of metallic thin films
Authors: Jin Jae Sik , Lee Joon Sik , Kwon Ohmyoung
Published: May 2008

A simple model of the electron effective mean free path (MFP) in thin metal films is proposed, and the thermal conductivities of aluminum and copper thin films are calculated by solving the Boltzmann transport equation (BTE). In the modeling of the electron effective MFP, the combined contributions of the bulk MFP and the film MFP are taken into account. The proposed effective electron MFP model is incorporated with the gray version of BTE through the “transport” relaxation time. The present model is verified against the experimental thermal conductivity data as a function of the film thickness.
177
fs
erbium-doped fiber laser mode locked with a cellulose polymer film containing single-wall carbon nanotubes
Authors: Tausenev A. V. , Obraztsova E. D. , Lobach A. S. , Chernov A. I. , Konov V. I. , Kryukov P. G. , Konyashchenko A. V. , Dianov E. M.
Published: May 2008

A mode-locked soliton erbium-doped fiber laser generating 177fs pulses is demonstrated. The laser pumped by a 85mW, 980nm laser diode emits 7mW at 1.56μm at a pulse repetition rate of 50MHz. Passive mode locking is achieved with a saturable absorber made of a high-optical quality film based on cellulose derivative with dispersed carbon single-wall nanotubes. The film is prepared with the original technique by using carbon nanotubes synthesized by the arc-discharge method.
Large cryogenic magnetocaloric effect of DyCo2 nanoparticles without encapsulation
Authors: Ma S. , Cui W. B. , Li D. , Sun N. K. , Geng D. Y. , Jiang X. , Zhang Z. D.
Published: May 2008

The structure and formation of nanoparticles without encapsulation of the intermetallic compound DyCo2 were investigated by using x-ray diffraction and high-resolution transmission electron microscopy. The DyCo2 nanoparticles are stable in air without any shell protection. A large magnetic-entropy change of 13.2Jkg−1K−1 was found at 7.5K in an applied-field change from 1to7T, which is ascribed to the large magnetic moment density and the weak interaction energy in the nanoparticles. Such oxidation-resistant rare-earth transition-metal compound nanoparticles with large cryogenic magnetocaloric effect are useful for refrigeration applications at low temperatures.
Boron diffusion in amorphous silicon-germanium alloys
Authors: Edelman L. A. , Phen M. S. , Jones K. S. , Elliman R. G. , Rubin L. M.
Published: May 2008

The effect of Ge alloying on B diffusion in amorphous Si1−xGex alloys is reported for x=0−0.24. The diffusivity was not observed to exhibit any transient decay. The diffusivity decreases with increasing Ge concentration. The activation energy for B diffusion appears to increase from 2.8eV for amorphous Si to 3.6eV for amorphous Si0.76Ge0.24. It is suggested that, in these alloys, Ge distorts the amorphous Si network thereby increasing B trapping by Si.
Spin confinement in the superlattices of graphene ribbons
Authors: Topsakal M. , Sevinçli H. , Ciraci S.
Published: May 2008

Based on first-principles calculations, we showed that repeated heterostructures of zigzag graphene nanoribbons of different widths form multiple quantum well structures. Edge states of specific spin directions can be confined in these wells. The electronic and magnetic state of the ribbon can be modulated in real space. In specific geometries, the absence of reflection symmetry causes the magnetic ground state of whole heterostructure to change from antiferromagnetic to ferrimagnetic. These quantum structures of different geometries provide unique features for spintronic applications.
Atomic force microscopy measurement of the Young’s modulus and hardness of single LaB6 nanowires
Authors: Zhang Han , Tang Jie , Zhang Lin , An Bai , Qin Lu-Chang
Published: May 2008

We have employed the atomic force microscopy based (a) three-point bending and (b) nanoindentation methods to obtain the Young’s modulus and hardness of single LaB6 nanowires. The Young’s modulus, E=467.1±15.8GPa, is the same as that of the LaB6 single crystals but larger than the sintered polycrystalline LaB6 samples. The nanoindentation hardness of the LaB6 nanowire is H=70.6±2.1GPa at an indent depth of 4.6nm, which is higher than that of the LaB6 single crystals, LaB6 polycrystals, and W metals. A superior resistance against thermal vibration, field modification, and ion bombardment is expected for the LaB6 nanowires as a field-emission point electron source.