bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐density lipoprotein receptors regulate microglial inflammation through c‐Jun N‐terminal kinase
Authors: Pocivavsek Ana , Burns Mark P. , Rebeck G. William
Published: September 2008

Apolipoprotein E (apoE) has been implicated in modulating the central nervous system (CNS) inflammatory response. However, the molecular mechanisms involved in apoE‐dependent immunomodulation are poorly understood. We hypothesize that apoE alters the CNS inflammatory response by signaling via low‐density lipoprotein (LDL) receptors in glia. To address this hypothesis, we used a small bioactive peptide formed from the receptor‐binding domain of apoE, apoE peptide (EP), to study LDL receptor signaling in microglia. To model glial activation, we treated primary mouse microglia and the microglial cell line BV2 with lipopolysaccharide (LPS) and studied two inflammatory responses: an increase in nitric oxide production (NO) and a decrease in apoE production. We found that treatment of primary microglia and BV2 cells with EP attenuated LPS‐induced NO accumulation and apoE reduction in a dose‐dependent manner. Using the receptor‐associated protein to block ligand binding to members of the LDL receptor family, we found that EP attenuated both of these LPS‐induced inflammatory responses via LDL receptors. We studied two intracellular signaling cascades associated with apoE: c‐Jun N‐terminal kinase (JNK) and extracellular signal‐regulated kinase (ERK). LPS induced both ERK and JNK activation, whereas EP induced ERK activation, but drastically reduced JNK activation. Inhibition of JNK with SP600125 reduced LPS‐induced NO production and apoE reduction in a dose‐dependent manner. Treatment of microglia with suboptimal EP in combination with JNK inhibitor enhanced attenuation of LPS‐induced NO production. These data suggest that microglial LDL receptors regulate JNK activation, which is necessary for apoE modulation of the inflammatory response. © 2008 Wiley‐Liss, Inc.
How does the Schwann cell lineage form tumors in NF1?
Authors: Carroll Steven L. , Ratner Nancy
Published: September 2008

Neurofibromas are benign tumors of peripheral nerve that occur sporadically or in patients with the autosomal dominant tumor predisposition syndrome neurofibromatosis type 1 (NF1). Multiple neurofibroma subtypes exist which differ in their site of occurrence, their association with NF1, and their tendency to undergo transformation to become malignant peripheral nerve sheath tumors (MPNSTs), the most common malignancy associated with NF1. Most NF1 patients carry a constitutional mutation of the NF1 tumor suppressor gene. Neurofibromas develop in these patients when an unknown cell type in the Schwann cell lineage loses its remaining functional NF1 gene and initiates a complex series of interactions with other cell types; these interactions may be influenced by aberrant expression of growth factors and growth factor receptors and the action of modifier genes. Cells within certain neurofibroma subtypes subsequently accumulate additional mutations affecting the p19ARF‐MDM2‐TP53 and p16INK4A‐Rb signaling cascades, mutations of other as yet unidentified genes, and amplification of growth factor receptor genes, resulting in their transformation into MPNSTs. These observations have been validated using a variety of transgenic and knockout mouse models that recapitulate neurofibroma and MPNST pathogenesis. A new generation of mouse models is also providing important new insights into the identity of the cell type in the Schwann cell lineage that gives rise to neurofibromas. Our improving understanding of the mechanisms underlying the pathogenesis of neurofibromas and MPNSTs raises intriguing new questions about the origin and pathogenesis of these neoplasms and establishes models for the development of new therapies targeting these neoplasms. © 2008 Wiley‐Liss, Inc.
Segmental cystic renal disease: Sonographic and CT findings
Authors: Wankhar Baphira , Batchala Prem Pradeep , Sailo Stephen
Published: September 2008

Segmental cystic renal disease is a unique benign condition that requires no treatment. It can be confused on imaging, especially on sonography, with other more common cystic renal diseases and sometimes cystic malignancy. We report a case of segmental cystic renal disease with typical imaging features on sonography and CT for which nephrectomy was avoided. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Sonographic assessment of the lateral femoral cutaneous nerve
Authors: Damarey Benjamin , Demondion Xavier , Boutry Nathalie , Kim Hee‐Jin , Wavreille Guillaume , Cotten Anne
Published: September 2008

Purpose.

To evaluate the ability of high‐frequency sonography to evaluate the lateral femoral cutaneous nerve (LFCN).

Methods.

A cadaveric study was performed on 5 cadavers to outline the normal course of the LFCN. Next, 37 LFCNs in 21 volunteers were evaluated via sonography with a 5–13‐MHz linear‐array transducer.

Results.

The LFCN was easily identified in our dissections. It always entered the thigh under the inguinal ligament and coursed superficially to the sartorius muscle. In 2/10 (20%) cases, anatomical variants were observed. Sonography revealed the LFCN in 26/37 (70%) cases. The relationships of the nerve with the deep circumflex iliac artery, the anterior superior iliac spine, and the sartorius were visualized. Neuromas were observed bilaterally in 1 volunteer.

Conclusion.

The LFCN can be seen in the groin with the aid of sonography. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Evaluation of the accuracy and reliability of two 3‐dimensional sonography methods in volume measurement of small structures: An in vitro phantom study
Authors: Kot Brian C.W. , Sin Damian M.H. , Ying Michael
Published: September 2008

Purpose.

To evaluate the accuracy and reliability of two 3‐dimensional (3D) ultrasound imaging and measurement techniques in volume measurements using custom‐made phantoms.

Methods.

A total of 20 phantoms with irregular‐shaped test objects of known volume (2–9.7 ml) were constructed. The phantoms were scanned using an automated mechanical 3D sonography technique and a free‐hand 3D sonography technique. The volumes of the test objects were measured with “parallel planes” and “rotating planes” techniques, respectively. The measured volumes were compared with the actual volumes of the test objects. To evaluate inter‐ and intraoperator measurement variability, the phantoms were scanned twice by 2 different operators.

Results.

Both the automated mechanical and the free‐hand 3D sonography techniques were accurate and reliabile. Automated mechanical 3D sonography with the parallel planes technique (accuracy, 81.5–83.4%; reproducibility, 91.1%; repeatability, 98.8–99.1%) was slightly more accurate and reliable than the free‐hand rotating planes technique (accuracy, 74.7–84.2%; reproducibility, 88.4%; repeatability, 97.3–98%), but the differences were not statistically significant.

Conclusion.

Both the automated and freehand volume measurement techniques evaluated in this study are accurate and reliable. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Transvaginal sonographic diagnosis of female urethral diverticula
Authors: Wu Yong‐Yang , Li Yong‐Zhong , Wei Qiang , Li Hong , Hang Geng‐Yu , Shen Hong
Published: September 2008

Purpose

We report our experience with transvaginal sonography (TVUS) in the diagnosis of female urethral diverticulum (UD).

Method

We reviewed the TVUS examinations of 4 patients with a clinical diagnosis of UD and correlated the sonographic findings with the operative findings, especially regarding the UD's size, content, and location.

Results

All UDs were demonstrated on TVUS. The size, content, and location of the UD correlated well with the operative findings.

Conclusion

TVUS is accurate in diagnosis and determination of the size, content, and location of female UD. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Sonographic study of the development of fetal corpus callosum in a Chinese population
Authors: Zhang Hai‐chun , Yang Jie , Chen Zhong‐ping , Ma Xiao‐yan
Published: September 2008

Purpose

The observation of fetal corpus callosum (CC) is important for the prenatal sonographic assessment of fetal central nervous system development. The aim of this study was to investigate the development of normal Chinese fetal CC.

Method

CC measurements were performed using high‐resolution transabdominal sonography on 622 Chinese fetuses between 16 and 39 weeks' gestation. The correlation between CC size and gestational age was investigated.

Results

The fetal CC length increased in a linear fashion during pregnancy. The length of the CC as a function of gestational age was expressed by the following regression equation: length (mm) = −9.567 + 1.495 × gestational age (weeks) (r = 0.932, p < 0.001).

Conclusion

Knowledge of normal CC appearance may help identify developmental anomalies and enable accurate prenatal counseling. © 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2009
Job engagement in organizations: Fad, fashion, or folderol?
Authors: Wefald Andrew J. , Downey Ronald G.
Published: September 2008

Engagement, broadly defined as involvement, satisfaction, and enthusiasm, is widely used by organizations and consultants for improving retention. However, engagement fails to meet many of the common criteria for positive organizational practice, i.e. theoretical, valid, unique, state‐like, and positive. With attention to these criteria, engagement may useful to management. Copyright © 2008 John Wiley & Sons, Ltd.
Durability and photophysical properties of surfactant‐covered porous silicon particles in aqueous suspensions
Authors: Balaguer M. , Pastor E. , Bychto L. , Atienzar P. , Miranda M. A. , Matveeva E. , Chirvony V. S.
Published: September 2008

With the aim to impart hydrophilic properties to porous silicon (PSi) containing luminescent Si nanocrystals the PSi surface has been modified by a non‐ionic surfactant (undecylenic acid) either physically (by physisorption) or chemically (through Si‐C bond). PSi luminescence spectra and reversible quenching of the luminescence by molecular oxygen have been studied as a function of time elapsed after PSi surface immersion in water. The data obtained indicate that Si nanocrystal surface oxidation, which is realized in water, is accompanied by an appearance of a new type of luminescence centres, which are quenched by molecular oxygen differently than free excitons. SiO‐related surface states are suggested to be responsible for the observed effect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Composition analysis of ternary semiconductors by combined application of conventional TEM and HRTEM
Authors: Häusler I. , Kirmse H. , Neumann W.
Published: September 2008

The chemical composition of ternary material systems can be determined by a combined analysis of dark‐field imaging and quantitative high‐resolution transmission electron microscopy (qHRTEM). This method is restricted to material systems where on the one hand chemically sensitive reflections occur and on the other hand the material surrounding the nanostructure contains only those atomic species which are also present in the nanostructure. In the developed procedure the dark‐field image intensity is calculated as a function of chemical composition. Additionally, it is taken into consideration that the strained state of the system leads to a change of the symmetry. For analysing the chemically sensitive dark‐field images the composition must be normalized by a known concentration value. The method will be demonstrated for the following system: GaSbxAs1–x quantum dots (QDs) grown by metal‐organic chemical vapour phase deposition (MOCVD) on GaAs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of Home Monitoring on the clinical status of heart failure patients: Design and rationale of the IN‐TIME study
Authors: Arya Arash , Block Michael , Kautzner Josef , Lewalter Thorsten , Mörtel Heinrich , Sack Stefan , Schumacher Burghard , Søgaard Peter , Taborsky Milos , Husser Daniela , Hindricks Gerhard ,   IN‐TIME investigators
Published: September 2008

Background:

Despite optimal drug and device therapy, frequent hospitalisations due to decompensated heart failure remain an issue. Early detection of decompensation could prevent hospitalisation in patients with congestive heart failure. The recently introduced Home Monitoring functionality of implanted devices is a promising new telecardiology technique which provides information on the status of heart failure. Home Monitoring observation of heart failure patients could lead to early detection of preclinical decompensation, enable early intervention before clinical decompensation, and thus could prevent hospitalisations.

Objective:

The IN‐TIME study is designed to assess the impact of Home Monitoring on the early detection of worsening congestive heart failure and the clinical status of heart failure patients.

Study design:

Approximately 620 patients will be prospectively randomised to patient management guided by Home Monitoring analysis or standard care and followed for 12 months. The endpoints committee will adjudicate events in a blinded fashion. The primary endpoint is a composite of all‐cause mortality, unplanned hospitalisation due to worsening heart failure, NYHA class and patient global self assessment (Packer score). The study should complete recruitment during 2009 and report in late 2010.
The tail pigmentation pattern of C57BL/6J mice affects nociception/pain quantification in the tail flick test
Authors: Wen Ting , Ansonoff Michael A. , Pintar John E.
Published: September 2008

The heat radiant tail flick test is commonly used to quantify nociception and pain levels. Likewise, the C57BL/6J strain of mice is frequently used in pain‐related studies as transgenic mice are often backcrossed onto this background. C57BL/6J mice naturally develop non‐pigmented patches of variable length on the distal part of the tail that could conceivably modify the response latency in tail flick assays. Here we find that these non‐pigmented regions, in a position‐independent manner, significantly increase the response latency in the heat radiant tail flick assay, but not the warm water immersion test. This finding demonstrates that the extent of pigmentation, and not other potential variables between pigmented and non‐pigmented skin, affects radiant heat tail flick latency, and should be considered in the design of pain‐related studies using mice with variable tail pigmentation.
Treatment with LXR agonists after focal cerebral ischemia prevents brain damage
Authors: Sironi Luigi , Mitro Nico , Cimino Mauro , Gelosa Paolo , Guerrini Uliano , Tremoli Elena , Saez Enrique
Published: September 2008

Stroke is characterized by massive inflammation in areas surrounding the injury that magnifies damage to the brain. The liver X receptors (LXRs) are nuclear receptors that regulate cholesterol, lipid, and glucose metabolism. Synthetic LXR agonists have potent anti‐inflammatory properties in a variety of settings, including neuroinflammation. However, the ability of LXR agonists to suppress stroke‐associated inflammation has not been evaluated. Here, we have used time‐lapse magnetic resonance imaging (MRI) to show that a single dose of an LXR ligand administered post‐injury dramatically reduces brain damage in a model of acute brain ischemia. Neuroprotection was associated with suppression of neuroinflammation.
Negative regulation of adiponectin receptor 1 promoter by insulin via a repressive nuclear inhibitory protein element
Authors: Sun Xiaolan , He Jing , Mao Chenqian , Han Ruijun , Wang Zhenzhen , Liu Yong , Chen Yan
Published: September 2008

Adiponectin is an adipose‐derived hormone that has anti‐diabetic and anti‐atherogenic effects through interaction with adiponectin receptors AdipoR1 and AdipoR2. We analyzed the transcriptional regulation of AdipoR1 by insulin. Insulin repressed the promoter activity of AdipoR1 in C2C12 myoblasts via PI3K and Foxo1. Deletion studies demonstrated the presence of a putative insulin‐responsive region which is composed of a nuclear inhibitory protein (NIP) binding element. Mutation of the NIP element abrogated the negative regulation of AdipoR1 promoter by insulin. Insulin treatment could induce formation of a protein complex that bound the NIP element. Collectively, our data suggest that a repressive NIP element is involved in the negative regulation of AdipoR1 promoter by insulin.
In vitro perturbation of aggregation processes in β‐amyloid peptides: A spectroscopic study
Authors: Sgarbossa Antonella , Buselli Dario , Lenci Francesco
Published: September 2008

MINT‐6742984: 1‐40 beta‐amyloid peptide (uniprotkb:P05067) and 1‐40 beta‐amyloid peptide (uniprotkb:P05067) bind (MI:0407) by circular dichroism (MI:0016)

MINT‐6743002: 1‐40 beta‐amyloid peptide (uniprotkb:P05067) and 1‐40 beta‐amyloid peptide (uniprotkb:P05067) bind (MI:0407) by light scattering (MI:0067)

MINT‐6743012: 1‐40 beta‐amyloid peptide (uniprotkb:P05067) and 1‐40 beta‐amyloid peptide (uniprotkb:P05067) bind (MI:0407) by classical fluorescence spectroscopy (MI:0017)
Ascidian sperm activating and attracting factor: Importance of sulfate groups for the activities and implication of its putative receptor
Authors: Yoshida Manabu , Shiba Kogiku , Yoshida Kaoru , Tsuchikawa Hiroshi , Ootou Ouichirou , Oishi Toru , Murata Michio
Published: September 2008

The sperm activating and attracting factor (SAAF) from the eggs of the ascidian Ciona intestinalis was identified as the sulfated polyhydroxysterol,3α,4β,7α,26‐tetrahydroxy‐5α‐cholestane‐3,26‐disulfate. We present a functional analysis of SAAF derivatives that reveals the roles of the various SAAF functional groups. Optical isomerism does not affect SAAF activities. Hydrolysis on one side, i.e. at the sulfate groups of SAAF, decreases the sperm‐activating and sperm‐attracting activities, while hydrolysis on both sides resulted in the loss of both activities. Biotinylated‐SAAF lost its sperm‐activating ability, but retained sperm‐binding and chemotactic abilities. Thus, the sulfate groups of SAAF are responsible for these activities.
Enhanced glycolysis induced by mtDNA mutations does not regulate metastasis
Authors: Ishikawa Kaori , Hashizume Osamu , Koshikawa Nobuko , Fukuda Sayaka , Nakada Kazuto , Takenaga Keizo , Hayashi Jun-Ichi
Published: September 2008

We addressed the issue of whether enhanced glycolysis caused by mtDNA mutations independently induces metastasis in tumor cells using mtDNA transfer technology. The resultant trans‐mitochondrial cybrids sharing the same nuclear background of poorly metastatic carcinoma P29 cells, P29mtA11 and P29mtΔ cybrids, possessed mtDNA with a G13997A mutation from highly metastatic carcinoma A11 cells and mtDNA with a 4696 bp deletion mutation, respectively. The P29mtΔ cybrids expressed enhanced glycolysis, but did not express ROS overproduction and high metastatic potential, whereas P29mtA11 cybrids showed enhanced glycolysis, ROS overproduction, and high metastatic potential. Thus, enhanced glycolysis alone does not induce metastasis in the cybrids.
In HspA from Helicobacter pylori vicinal disulfide bridges are a key determinant of domain B structure
Authors: Loguercio Salvatore , Dian Cyril , Flagiello Angela , Scannella Alessandra , Pucci Piero , Terradot Laurent , Zagari Adriana
Published: September 2008

Helicobacter pylori produces a heat shock protein A (HspA) that is unique to this bacteria. While the first 91 residues (domain A) of the protein are similar to GroES, the last 26 (domain B) are unique to HspA. Domain B contains eight histidines and four cysteines and was suggested to bind nickel. We have produced HspA and two mutants: Cys94Ala and Cys94Ala/Cys111Ala and identified the disulfide bridge pattern of the protein. We found that the cysteines are engaged in three disulfide bonds: Cys51/Cys53, Cys94/Cys111 and Cys95/Cys112 that result in a unique closed loop structure for the domain B.
The promiscuity of ARF interactions with the proteasome
Authors: Pollice Alessandra , Vivo Maria , Mantia Girolama La
Published: September 2008

The tumor suppressor ARF is one of the most important oncogenic stress sensors in mammalian cells. Its effect is exerted through the interaction with different cellular partners, often resulting in their functional inactivation. This review focuses on the role played by the proteasome in ARF regulation of protein turnover and the function of most of its interacting partners. Specific proteasome components appear to be involved in the regulation of ARF turnover, bringing to light a complex network of interactions between ARF and the proteasome.
Energy budgets of Atlantic hurricanes and changes from 1970
Authors: Trenberth Kevin E. , Fasullo John
Published: September 2008

On the basis of the current observational record of tropical cyclones and sea surface temperatures (SSTs) in the Atlantic, estimates are made of changes in surface sensible and latent heat fluxes and hurricane precipitation from 1970 to 2006. The best track data set of observed tropical cyclones is used to estimate the frequency that storms of a given strength occur after 1970. Empirical expressions for the surface fluxes and precipitation are based on simulations of hurricane Katrina in August 2005 with the advanced Weather and Research Forecasting (WRF) model at 4 km resolution without parameterized convection. The empirical relationships are computed for the surface fluxes and precipitation within 400 km of the eye of the storm for all categories of hurricanes based upon the maximum simulated wind and the observed sea surface temperature and saturation specific humidity. Strong trends are not linear but are better depicted as a step function increase from 1994 to 1995, and large variability reflects changes in SSTs and precipitable water, modulated by El Niño events. The environmental variables of SST and water vapor are nonetheless accompanied by clear changes in tropical cyclone activity using several metrics.
Establishing a New Animal Model for the Study of Laryngeal Biology and Disease: An Anatomic Study of the Mouse Larynx
Authors: Thomas Lisa B. , Stemple Joseph C. , Andreatta Richard D. , Andrade Francisco H.
Published: September 2008

Purpose

Animal models have contributed greatly to the study of voice, permitting the examination of laryngeal biology and the testing of surgical, medical, and behavioral interventions. Various models have been used. However, until recently, the mouse(Mus musculus) has not been used in laryngeal research, and features of the mouse larynx have not been defined. Therefore, the purpose of this study was to qualitatively describe mouse laryngeal anatomy in relation to known human anatomy.

Methods

Larynges of 7 C57BL mice were examined and photographed under stereotactic and light microscopy.

Results

The authors found that mouse laryngeal organization was similar to that of humans. The hyoid bone and epiglottal, thyroid, cricoid, and arytenoid cartilages were identified. An additional cartilage was present ventrally. Thyroarytenoid, posterior cricoarytenoid, lateral cricoarytenoid, and cricothyroid muscles were grossly positioned as in humans. Interarytenoid muscles were not present; however, a functional counterpart was identified.

Conclusions

The authors provide an initial description of mouse laryngeal anatomy. Because of its amenability to genetic engineering, the mouse is the premiere model for the study of disease and the testing of interventions. Introduction of the mouse model for laryngeal study offers a tool for the study of normal laryngeal cell biology and tissue response to disease processes.
Direct deposition of magnetite thin films on organic semiconductors
Authors: Arisi Emilia , Bergenti Ilaria , Cavallini Massimiliano , Riminucci Alberto , Ruani Giampiero , Dediu Valentin , Ghidini Massimo , Pernechele Chiara , Solzi Massimo
Published: September 2008

Technological procedures able to produce high quality electrodes from magnetic oxides in vertical organic-inorganic hybrid devices is a challenging task in the field of organic spintronics. Thin films of magnetite (Fe3O4) have been successfully grown directly on top of organic semiconductor layers, tris(8-hydroxyquinoline)aluminium(III) (Alq3), by pulsed-electron ablation technique. The films show ferromagnetic behavior and good structural quality, properties detected by magneto-optical Kerr effect, superconductor quantum interference device, micro-Raman spectroscopy, and Atomic Force Microscopy. The ferromagnetic behavior persists even for 10nm thick films. Charge injection at magnetite-organic interface has been finally demonstrated by detecting electroluminescence from Alq3.
Optical switching properties of RCo2-type alloy hydride based solid state device
Authors: Srinivas G. , Sankaranarayanan V. , Ramaprabhu S.
Published: September 2008

The optical switching properties of a solid state device based on Ho0.6Mm0.4Co2 (HMC) alloy thin film as a switching active layer, water pretreated Nafion membrane as a solid electrolyte, and a transparent conducting indium tin oxide (ITO) as a counterelectrode are investigated. The device is simple and has a reduced layer sequence of HMC/Pd/Nafion/ITO. The reversible optical switching of this device has been studied during electrochemical galvanostatic charging-discharging as well as cyclic voltammetric measurements. Further, the optical switching durability of the device has been tested by repeated electrochemical hydrogenation-dehydrogenation, and the variations in the optical switching properties are discussed. The special characteristic of the device is that it can reversibly switch between a metallic reflecting state and a semiconducting transparent state by a small reversible applied current/voltage indicating the potential substitution for conventional electrochromic devices.
Synchronization of pulse-coupled oscillators with a refractory period and frequency distribution for a wireless sensor network
Authors: Konishi Keiji , Kokame Hideki
Published: September 2008

The present paper considers the synchronization of globally pulse-coupled oscillators with a refractory period and frequency distribution. The oscillators are capable of achieving time synchronization for a practical wireless sensor network. Furthermore, as a result of the stability analysis of the synchronization, a procedure for designing the oscillators is provided: the determination of the allowable refractory period under a given frequency distribution range. These analytical results are verified by numerical examples.
Preparation of Mn-doped BaTiO3 nanoparticles and their magnetic properties
Authors: Tong Xiaoran , Lin Yuan-Hua , Zhang Songyin , Wang Yao , Nan Ce-Wen
Published: September 2008

Mn-doped BaTiO3 nanoparticles have been synthesized using a hydrothermal method. Phase composition, microstructure, and Raman spectroscopy analysis indicate that a double-phase structure containing both cubic and tetragonal structures can be obtained. Electron paramagnetic resonance and x-ray photoelectron spectroscopy measurements prove that Mn ions exist as a form of Mn2+ in these nanoparticles. Magnetization measurements reveal that a ferromagnetic behavior can be observed in the Mn-doped BaTiO3 at low temperature, and the nominal ratio of Ba/Ti has a great influence on the ferromagnetic properties. This ferromagnetic mechanism can be ascribed to the exchange coupling interaction between the Mn2+ ions and the Ti4+ vacancy.
Heat of formation of the HOSO2 radical from accurate quantum chemical calculations
Authors: Klopper Wim , Tew David P. , González-García Núria , Olzmann Matthias
Published: September 2008

The reaction HOSO2+O2→HO2+SO3 (2) is of crucial importance for sulfuric acid formation in the atmosphere, and reliable thermochemical data are required for an adequate modeling. The currently least well known thermochemical quantity of reaction (2) is the enthalpy of formation of the hydroxysulfonyl radical (HOSO2). We report on high-level quantum chemical calculations to predict the binding energy of the HO–SO2 bond and deduce a value for the enthalpy of formation of HOSO2 using the most reliable thermodynamic data of OH and SO2. On the basis of anharmonic vibrational frequencies from calculations at the fc-CCSD(T)/cc-pV(T+d)Z level of theory, the enthalpy of reaction at 0 K for the reaction OH+SO2→HOSO2 (1) was computed to be ΔRH0 K(1)=−109.4±2.0 kJ/mol and the thermal corrections result in ΔRH298 K(1)=−114.7±3.0 kJ/mol. From these values, we obtain ΔfH0 K(HOSO2)=−366.6±2.5 and ΔfH298 K(HOSO2)=−374.1±3.0 kJ/mol, respectively. Accordingly, ΔRH0 K(2)=−8.5±3.0 and ΔRH298 K(2)=−9.5±3.0 kJ/mol.
A multistep ac electrodeposition method to prepare Co nanowires with high coercivity
Authors: Wang Pangpang , Gao Lumei , Qiu Zhiyong , Song Xiaoping , Wang Liqun , Yang Sen , Murakami Ri-ichi
Published: September 2008

It is known that the ac electrodeposition method with low current density can grow compact metal nanowires, but the length of those nanowires is very short. In contrast, the ac electrodeposition method with high current density can grow long metal nanowires. However these long nanowires are not compact and contain lots of defects. In this paper, we describe a multistep ac electrodeposition method to fabricate long metal nanowires with compact structure uniformly filled upon a porous anodic aluminum oxide template. Using this method, Co nanowires with high coercivity (Hc∥) and remnant ratio (Mr/Ms) have been prepared under relatively low deposition current density. The Co nanowires exhibited obvious magnetic anisotropy with the easy axis along the axial direction of nanowires. The maximal Hc∥ (2900 Oe) and Mr/Ms (0.95) were optimal for the perpendicular magnetic recording materials. The magnetic microstructure of Co nanowires is also discussed in this paper.
Construction and experimental testing of the constant-bandwidth constant-temperature anemometer
Authors: Ligęza P.
Published: September 2008

A classical constant-temperature hot-wire anemometer enables the measurement of fast-changing flow velocity fluctuations, although its transmission bandwidth is a function of measured velocity. This may be a source of significant dynamic errors. Incorporation of an adaptive controller into the constant-temperature system results in hot-wire anemometer operating with a constant transmission bandwidth. The construction together with the results of experimental testing of a constant-bandwidth hot-wire anemometer prototype are presented in this article. During the testing, an approximately constant transmission bandwidth of the anemometer was achieved. The constant-bandwidth hot-wire anemometer can be used in measurements of high-frequency variable flows characterized by a wide range of velocity changes.
Higher-order processes of excitation energy transfer in supramolecular complexes: Liouville space analysis of bridge molecule mediated transfer and direct photon exchange
Authors: May Volkhard
Published: September 2008

Long-range electronic excitation energy transfer is studied in the framework of a generalized master equation approach, which offers a systematic account for higher-order processes. Bridge molecule mediated transfer is confronted with the direct excitation energy exchange via photon emission and absorption. It is the central aim of this paper to present a systematic study of fourth-order rates, which describe both types of transfer processes characterized by the presence of intermediate states. While such a Liouville space formulation of rates is known from bridge mediated transfer, it is new for the case of photon mediated processes. In the former case, however, a novel approach to account for intermediate state relaxation is introduced. Finally and for illustration, some estimates are offered for the length dependence of the various discussed transfer rates.
An analysis of the far-field response to external forcing of a suspension in the Stokes flow in a parallel-wall channel
Authors: Bławzdziewicz J. , Wajnryb E.
Published: September 2008

The leading-order far-field scattered flow produced by a particle in a parallel-wall channel under creeping-flow conditions has a form of the parabolic velocity field driven by a two-dimensional dipolar pressure distribution. We show that in a system of hydrodynamically interacting particles, the pressure dipoles contribute to the macroscopic suspension flow in a similar way as the induced electric dipoles contribute to the electrostatic displacement field. Using this result we derive macroscopic equations governing suspension transport under the action of a lateral force, a lateral torque, or a macroscopic pressure gradient in the channel. The matrix of linear transport coefficients in the constitutive relations linking the external forcing to the particle and fluid fluxes satisfies the Onsager reciprocal relation. The transport coefficients are evaluated for square and hexagonal periodic arrays of fixed and freely suspended particles, and a simple approximation in a Clausius–Mossotti form is proposed for the channel permeability coefficient. We also find explicit expressions for evaluating the periodic Green’s functions for the Stokes flow between two parallel walls.
On the dehydration mechanism of Mg(OH)2 by a high-energy electron beam
Authors: Su Dong , Jiang Nan , Spence John C. H. , He Feng , Petuskey William T.
Published: September 2008

The dehydration process in Mg(OH)2 induced by high-energy electron irradiation is studied by in situ electron energy loss spectroscopy. During dehydration, both the low energy-loss spectra and the Mg L23 edge show the existence of partially oxidized Mg- or O-deficient MgO in the dehydrated products, which is not seen in the thermally dehydrated MgO. This indicates that the dehydration mechanism under the electron beam may be different from the mechanism involved in a thermal process.
Surface plasmons induced extra diffraction band of cholesteric liquid crystal grating
Authors: Hung Wen-Chi , Cheng Wood-Hi , Lin Yu-Sung , Jang Der-Jun , Jiang I-Min , Tsai Ming-Shan
Published: September 2008

Diffraction behavior of cholesteric liquid crystal (CLC) grating with the surface plasmon effect was investigated. One indium tin oxide plate of the CLC grating cell was covered with silver nanoparticles. With the application of a proper voltage, a well formed phase grating was constructed in the CLC cell. The CLC grating was probed by a beam of the polarized-monochromatic light, and the wavelength range was from 450 to 700 nm. It was shown that an extra first-order diffraction band was observed around 505 nm. The physical reason of the extra diffraction band could be the surface plasma effect emerged from silver nanoparticles. The extra diffraction band due to the surface plasmon effect can offer potential applications in nano-optics, such as the optical switch function.
High resolution IR spectroscopy of acetylene-furan in ultracold helium nanodroplets
Authors: Metzelthin Anja , Birer Özgür , Sánchez-García Elsa , Havenith Martina
Published: September 2008

We have measured the IR spectrum of the acetylene-furan complex in ultracold helium nanodroplets in the region of the ν3 CHasym-stretch vibration of the acetylene (between 3240 and 3300cm−1). We have observed eight bands that can be attributed to acetylene-furan complexes. Two of these bands are assigned to two different isomers of the 1:1 acetylene-furan complex. The vibrational band at 3267.4cm−1 is assigned to the CHasym-stretch vibration of the dimer structure with the C–H of the acetylene being attached to the π-system of the furan. The peak at 3272.1cm−1 is assigned to the CHasym-stretch vibration of the dimer structure with the C–H of the acetylene being attached to the oxygen atom of the furan. These assignments are confirmed by additional measurements of the spectrum of the C13-acetylene-furan complex.
Influence of target thickness on the generation of high-density ion bunches by ultrashort circularly polarized laser pulses
Authors: Yin Yan , Yu Wei , Yu M. Y. , Lei Anle , Yang Xiaoqing , Xu Han , Senecha Vinod Kumar
Published: September 2008

Ion acceleration by ultrashort circularly polarized laser pulse in a solid-density target is investigated using two-dimensional particle-in-cell simulation. The ions are accelerated and compressed by the continuously extending space-charge field created by the evacuation and compression of the target electrons by the laser light pressure. For a sufficiently thin target, the accelerated and compressed ions can reach and exit from the rear surface as a high-density high-energy ion bunch. The peak ion energy depends on the target thickness and reaches maximum when the compressed ion layer can just reach the rear target surface. The compressed ion layer exhibits lateral striation which can be suppressed by using a sharp-rising laser pulse.
Elastic theory for strained heterostructures with in-plane anisotropy
Authors: Arimoto Keisuke , Nakagawa Kiyokazu
Published: September 2008

An analytical formulation of elastic strain in epitaxially grown crystalline film was derived. The concept of anisotropic in-plane strain was included in the method, which is applicable to the investigation of strained films with an anisotropic defect configuration or fabrication-induced anisotropic stress. The developed method applies to arbitrary crystal classes with arbitrary surface orientations.
Electrical stress effect on Josephson tunneling through ultrathin AlOx barrier in Nb/Al/AlOx/Nb junctions
Authors: Tolpygo Sergey K. , Amparo Denis
Published: September 2008

The effect of dc electrical stress and breakdown on Josephson and quasiparticle tunneling in Nb/Al/AlOx/Nb junctions with ultrathin AlOx barriers typical for applications in superconductor digital electronics has been investigated. The junctions’ conductance at room temperature and current-voltage (I-V) characteristics at 4.2 K have been measured after the consecutive stressing of the tunnel barrier at room temperature. Electrical stress was applied using current ramps with increasing amplitude ranging from 0 to ∼1000Ic corresponding to voltages across the barrier up to ∼0.65 V, where Ic is the Josephson critical current. A very soft breakdown has been observed with polarity-dependent breakdown current (voltage). As the stressing progresses, a dramatic increase in subgap conductance of the junctions, the appearance of subharmonic current steps, and a gradual increase in both the critical and the excess currents as well as a decrease in the normal-state resistance have been observed. The observed changes in superconducting tunneling suggest a model in which a progressively increasing number of defects and associated additional conduction channels [superconducting quantum point contacts (SQPCs)] are induced by electric field in the tunnel barrier. By comparing the I-V characteristics of these conduction channels with the nonstationary theory of current transport in SQPCs based on multiple Andreev reflections by Averin and Bardas, the typical transparency D of the induced SQPCs was estimated as D∼0.7. The number of induced SQPCs was found to grow with voltage across the barrier as sinh(V/V0) with V0=0.045 V, in good agreement with the proposed model of defect formation by ion electromigration. The observed polarity dependence of the breakdown current (voltage) is also consistent with the model. Based on the observed magnitude of breakdown currents, electric breakdown of AlOx barrier during plasma processing was considered to be an unlikely cause of fabrication-induced, circuit pattern-dependent nonuniformities of Josephson junctions’ critical currents in superconductor integrated circuits.
Dynamics and mechanism of the E→D, D′, β, γ, and δ nonadiabatic transitions induced in molecular iodine by collisions with CF4 and SF6 molecules
Authors: Akopyan Mikhail E. , Lukashov Sergey S. , Poretsky Sergey A. , Pravilov Anatoly M. , Torgashkova Anna S. , Buchachenko Alexei A. , Suleimanov Yury V.
Published: September 2008

Nonadiabatic transitions among the first-tier ion-pair states of the iodine molecule in collisions with CF4 and SF6 partners are investigated by detecting the luminescence following the optical-optical double resonance excitation of the E0g+-state to the vibrational levels vE=8, 13, and 19. Total and partial rate constants, as well as vibrational product state distributions, are determined. It is found that electronic energy transfer in all channels is predominantly assisted by excitation of the dipole-allowed ν3 and ν4 modes of the partner. The measurements are accompanied by quantum scattering calculations that implement a close coupling treatment for the electronic and vibrational degrees of freedom and combine diatomics-in-molecule and long-range models for diabatic potential energy surfaces and coupling matrix elements. The analysis of experimental and theoretical data shows that the transitions without excitation of the partner are due to short-range couplings, whereas the vibrational excitation of the partner in the D0u+ channel originates from the long-range coupling of two transition dipole moments: electronic of the iodine molecule and vibrational of the partner. Unexpectedly efficient excitations of the partner in the other ion-pair states, which are not coupled to the initial E0g+-state by the transition dipole, are interpreted within the postcollision mechanism. Qualitatively, this implies that during a single collision the long-range nonadiabatic transitions to D, ν3 and D, ν4 channels are followed by secondary short-range transitions without changing the state of the partner.
Effect of interparticle interaction on kinetics of geminate recombination of subdiffusing particles
Authors: Shushin A. I.
Published: September 2008

The kinetics of geminate subdiffusion-assisted reactions (SDARs) of interacting particles is analyzed in detail with the use of the non-Markovian fractional Smoluchowki equation (FSE). It is suggested that the interparticle interaction potential is of the shape of potential well and reactivity is located within the well. The reaction kinetics is studied in the limit of deep well, in which the FSE can be solved analytically. This solution enables one to obtain the kinetics in a simple analytical form. The analytical expression shows that the SDAR kinetics fairly substantially depends on the mechanism of reactivity within the well. Specific features of the kinetics are thoroughly analyzed in two models of reactivity: the subdiffusion assisted activated rate model and the first order reaction model. The theory developed is applied to the interpretation of experimental kinetics of photoluminescence decay in amorphous a-Si:H semiconductors governed by geminate recombination of electrons and holes that are recently found to undergo subdiffusive relative motion. Analysis of results demonstrates that the subdiffusion assisted activated rate mechanism of reaction is closer to reality as applied to amorphous a-Si:H semiconductors. Comparison of experimental and theoretical kinetics allowed us to obtain some kinetic parameters of the systems under study: the rate of escaping from the well and the parameter characterizing the deviation of the subdiffusive motion from the conventional one.
Metal-free quantum-based metamaterial for surface plasmon polariton guiding with amplification
Authors: Ginzburg Pavel , Orenstein Meir
Published: September 2008

We propose an artificial material, based on inclusions of low-dimensional quantum structures made of AlN/GaN semiconductor layers, in a similar setting to that of a quantum cascade amplifier. By a proper quantum-dispersion engineering, this metamaterial can be used as a nonmetallic guide of surface plasmon polaritons in the optical regime with the added benefit of amplification and modulation. Advanced dispersion engineering of this quantum system is detailed here and due to the rapid development of the epitaxial growth of such material, we expect that the full set of the required material parameters will be realized in the near future.
Shapiro steps in Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions in magnetic field
Authors: Kitamura Michihide , Irie Akinobu , Oya Gin-ichiro
Published: September 2008

Shapiro steps in Bi2Sr2CaCu2O8+δ (BSCCO) high-Tc superconductor intrinsic Josephson junctions (IJJs) embedded in the external magnetic field applied parallel to the junction surface have been numerically studied by using the unified theory including both the electric and magnetic field couplings between neighboring Josephson junctions. It has been found that (I) the effect of the electric field coupling between neighboring Josephson junctions is not so crucial in the Shapiro steps of BSCCO IJJs, (II) the overall profiles of the I-V characteristics including Shapiro steps calculated for the same external magnetic induction are fairly similar with each other even if the junction lengths differ from each other, (III) the height of the Shapiro step decreases with increasing the external magnetic field but its magnetic field dependence does not so strongly depend on the number of stacked junctions, (IV) a Shapiro step device, which is hard for the external magnetic disturbance, can be made when the value of the SRshunt product is selected to be small for BSCCO IJJs, and (V) the Shapiro step and the flux flow could be treated separately under the presence of the external magnetic field.
Temperature dependence of the IR driven cis-trans isomerization of nitrous acid (HONO)
Authors: Botan Virgiliu , Hamm Peter
Published: September 2008

With the help of ultrafast time-resolved infrared spectroscopy, we investigate the temperature dependence of the IR driven cis→trans isomerization of nitrous acid (HONO) in solid Kr. We find that the lifetime of the OH-stretch vibration, as well as the final cooling into the matrix, is affected only minimally (if at all) by temperature. Nevertheless, the quantum yield of the cis→trans isomerization reaction increases by ≈30% to a total of 50%–70% when lowering the temperature from 30 to 15 K, whereas the trans→cis back yield is reduced by ≈40%. The results are discussed in analogy to Marcus theory of nonadiabatic electron transfer for the essentially barrierless case. We present a unified view of this important prototype proton transfer reaction that can explain the high cis→trans quantum yield of close to 1.
Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 °C
Authors: Jay-Gerin Jean-Paul , Lin Mingzhang , Katsumura Yosuke , He Hui , Muroya Yusa , Meesungnoen Jintana
Published: September 2008

The optical absorption spectra of the hydrated electron (eaq−) in supercritical (heavy) water (SCW) are measured by electron pulse radiolysis techniques as a function of water density at three temperatures of 380, 390, and 400 °C, and over the density range of ∼0.2–0.65 g/cm3. In agreement with previous work, the position of the eaq− absorption maximum (EAmax) is found to shift slightly to lower energies (spectral “redshift”) with decreasing density. A comparison of the present EAmax-density data with other measurements already reported in the literature in subcritical (350 °C) and supercritical (375 °C) water reveals that at a fixed pressure, EAmax decreases monotonically with increasing temperature in passing through the phase transition at tc. By contrast, at constant density, EAmax exhibits a minimum as the water passes above the critical point into SCW. These behaviors are explained in terms of simple microscopic arguments based on the crucial role played by local density and configurational fluctuations (associated with criticality) in providing pre-existing polymeric clusters, which act as trapping sites for electrons.