bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunohistological classification of ionocytes in the external gills of larval Japanese black salamander, Hynobius nigrescens Stejneger
Authors: Uchiyama Minoru , Kumano Tomoko , Komiyama Makiko , Yoshizawa Hideki , Matsuda Kouhei
Published: May 2011

In this cytological and immunohistological study, we clarified the localization of the membrane transporters Na+, K+‐ATPase (NKA), vacuolar‐type H+‐ATPase (VHA), and epithelial sodium channel (ENaC) and distinguished ionocyte subtypes in the gill of the Japanese salamander (Hynobius nigrescens). In larvae (IY stages 43–65), NKA immunoreactivity was observed on the basolateral plasma membrane in more than 60% cells and less than 20% cells in the primary filaments and secondary lamellae of the external gills, respectively. VHA immunoreactivity was observed on the apical membrane of some epithelial cells in the secondary lamellae of the external gills. High ENaCα immunoreactivity was widely observed on the apical cell membrane of a population of squamous cells, presumably pavement cells (PVCs), and mitochondria‐rich cells (MRCs), in the primary filaments and secondary lamellae of the external gills. Using double immunofluorescence microscopy, epithelial cell types involved in ionic regulation were characterized and divided into three ionocyte types: NKA‐, NKA‐ and ENaC‐, and VHA‐positive cells. VHA‐immunoreactive cells as well as NKA‐positive cells were observed during IY stages 43–65 of the salamander larvae. During late stages of metamorphosis, NKA, VHA, and ENaCα immunoreactivities in the external gills decreased and finally disappeared during the completion of metamorphosis (IY stage 68). PVCs and MRCs in the external gills are probably involved in acid–base balance regulation and osmoregulation in urodele amphibian larvae. The results are discussed in relation to the ionocytes previously reported in fish gills and the frog skin epithelium. J. Morphol., 2011. © 2011Wiley‐Liss, Inc.
Bisphosphonate treatment delays stress fracture remodeling in the rat ulna
Authors: Kidd L.J. , Cowling N.R. , Wu A.C.K. , Kelly W.L. , Forwood M.R.
Published: May 2011

Because bisphosphonates (BPs) are potent inhibitors of bone resorption, we hypothesized that they would retard direct remodeling of stress fractures. The aim of this study was to determine the effect of risedronate on direct remodeling and woven bone callus formation following stress fracture formation in the rat ulna. In 135 adult female Wistar rats, cyclic loading of the ulna created stress fractures. Rats were treated daily with oral saline, or risedronate at 0.1 or 1.0 mg/kg. From each bone, histomorphometry was performed on sections stained with toluidine blue at a standard level along the fracture. The high dose of risedronate caused a significant decrease in the percentage of repaired stress fracture and bone resorption along the stress fracture line at 6 and 10 weeks after loading (p < 0.05). At this dose, intracortical resorption was significantly reduced at 10 weeks after loading and intracortical new bone area was significantly reduced at 6 and 10 weeks. Woven bone formation and consolidation phases of stress fracture repair were not affected by low or high doses of risedronate. In conclusion, high dose bisphosphonate treatment impaired healing of a large stress fracture line by reducing the volume of bone resorbed and replaced during remodeling. We also confirmed that periosteal callus formation was not adversely affected by risedronate treatment. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1827–1833, 2011
Assessment of Raman microscopy coupled with principal component analysis to examine egg yolk–pigment interaction based on the protein CH stretching region (3100–2800 cm−1)
Authors: Romero‐Pastor Julia , Cardell Carolina , Manzano Eloisa , Yebra‐Rodríguez África , Navas Natalia
Published: May 2011

This work seeks to identify the slight changes in the characteristic CH stretching region (3100–2800 cm−1) of a protein‐based binder and fatty acid esters from egg yolk, which may occur in complex paint samples due to the presence of particular pigments. To date, this protein region—where historic pigments do not show characteristic Raman bands—has not been used to identify possible interactions between painting materials, in spite of its potential due to the mentioned feature. This study is based on the investigation of pure egg yolk model samples and tempera model samples prepared by mixing this binder with some historic pigments (cinnabar, raw Sienna, lead white, gypsum, calcite, azurite, lapis lazuli and smalt) as binary samples. All samples were analyzed in this region by Raman microscopy (RM) coupled with principal component analysis (PCA) for three color groups (red, white and blue) separately. The results show relevant spectral changes in the CH stretching region of amino acids and polyunsaturated fatty acids esters of the egg yolk binder, particularly in the azurite, lead white and gypsum‐based tempera samples. Lesser interactions were discerned in the tempera samples made with smalt, as well as shift in the region of polyunsaturated fatty acid esters of the egg yolk binder in the cinnabar and raw Sienna‐based tempera paintings. No interactions were recognized between the egg yolk and the pigments calcite and lapis lazuli. The effectiveness of applying RM combined with PCA for identifying interaction processes between binders and pigments is demonstrated. Copyright © 2011 John Wiley & Sons, Ltd.
Determination of free cyanide and zinc cyanide complex by capillary electrophoresis
Authors: Langeroudi Elahe Ghasemian , Petre Catalin Florin , Azizi Abdelaaziz , Proulx Eric , Larachi Faïçal
Published: May 2011

A capillary electrophoretic (CE) protocol was developed for the separation and quantification of free cyanide and zinc cyanide complex, two key species in gold cyanidation of zinc‐bearing sulfidic ores. Several common carrier electrolytes were implemented in an indirect UV detection method. The effect of electric field strength, injection volume, concentration of electro‐osmotic flow (EOF) modifier and UV‐absorbing agent in background electrolyte (BGE) was examined while peak height, peak area and noise were considered for optimization. The best results were obtained using a BGE that contained 35 mM sodium chromate, 12 mM free cyanide and 0.45 mM hexamethonium bromide at pH 10.5. Free cyanide concentration was compared to that measured with the conventional silver nitrate titration method in solutions containing free cyanides and weak cyano‐complexes. The developed CE protocol proved very robust in capturing the concentration of free cyanides (4% error) unlike the titration method which exhibited substantial sensitivity to the interfering weak cyano‐complexes (38% error).
Analysis of abuse drugs in urine using surfactant‐assisted dispersive liquid–liquid microextraction
Authors: Moradi Morteza , Yamini Yadollah , Baheri Tahmineh
Published: May 2011

The process of surfactant‐assisted dispersive liquid–liquid microextraction (SA‐DLLME) followed by high‐performance liquid chromatography‐UV detection was successfully applied for the extraction and determination of selected cannabinoids (cannabidiol, Δ9‐tetrahydrocannabinol, and cannabinol) in urine samples. The effective parameters on the extraction efficiency were studied and optimized utilizing two different optimization methods: one variable at a time (OVAT) and face center design (FCD). Under the optimum conditions (extraction solvent and its volume, toluene, 85 μL; disperser agent and its concentration, 1.0 mL of ultra‐pure water containing 0.5 mmol/L tetradecyl tremethyl ammonium bromide (TTAB); sample pH, 2.0 and salt concentration, 11% w/v NaCl), the limits of detection of the method were in the range of 0.1–0.5 μg/L and the repeatability and reproducibility of the proposed method, expressed as relative deviation, varied between 4.1 and 8.5% and 6.7 and 11.6%, respectively. Linearity was found to be in the range of 1.0–200 μg/L and under the optimum conditions, the preconcentration factors (PFs) were between 190 and 292. This proposed method was successfully applied in the analysis of three male advocate urine samples and good recoveries were obtained.
Enthalpy–entropy compensation effect on adsorption of light hydrocarbons on monolithic stationary phases
Authors: Korolev Alexander A. , Shiryaeva Valeria E. , Popova Tamara P. , Kurganov Alexander A.
Published: May 2011

Enthalpy and entropy of adsorption of light hydrocarbons C1–C4 have been measured for three monoliths of different polarity and for five different carrier gases: helium, hydrogen, nitrogen, carbon dioxide and dinitrogen oxide. Using carrier gas helium the highest values of enthalpy and entropy were observed for monolith based on ethylenedimethacrylate and the lowest values were observed for monolith based on silica, while monolith based on divinylbenzene demonstrated intermediate values. Entropy–enthalpy correlations were observed with carrier gas helium for all thee monoliths and possess similar slope indicating similar adsorption mechanism on all monoliths studied. Comparing different carrier gases entropy–enthalpy correlations within a homological series of solutes were observed for light carrier gases (He, H2 and N2) and were not observed for heavy carrier gases (CO2 and N2O). Instead, entropy–enthalpy correlations for heavy carrier gases were observed with pressure as variable and the higher the carrier gas pressure the lower the values of enthalpy and entropy observed. The observed changes in entropy–enthalpy correlations were explained by competitive adsorption of heavy carrier gas on monoliths.
Determination of ammonium in wastewaters by capillary electrophoresis on a column‐coupling chip with conductivity detection
Authors: Luc Milan , Kruk Pavol , Masár Marián
Published: May 2011

Analytical potentialities of a chip‐based CE in determination of ammonium in wastewaters were investigated. CZE with the electric field and/or ITP sample stacking was performed on a column‐coupling (CC) chip with integrated conductivity detectors. Acetate background electrolytes (pH ∼3) including 18‐crown‐6‐ether (18‐crown‐6) and tartaric acid were developed to reach rapid (in 7–8 min) CZE and ITP‐CZE resolutions of ammonium from other cations (sodium, potassium, calcium and magnesium) present in wastewater samples. Under preferred working conditions (suppressed hydrodynamic flow (HDF) and EOF on the column‐coupling chip), both the employed methods did provide very good repeatabilities of the migration (RSD of 0.2–0.8% for the migration time) and quantitative (RSD of 0.3–4.9% for the peak area) parameters in the model and wastewater samples. Using a 900‐nL sample injection volume, LOD for ammonium were obtained at 20 and 40 μg/L concentrations in CZE and ITP‐CZE separations, respectively. Very good agreements of the CZE and ITP‐CZE determinations of ammonium in six untreated wastewater samples (only filtration and dilution) with the results obtained by a reference spectrometric method indicate a very good accuracy of both the CE methods presented.
Phosphorus and Silicon Containing Low‐Melting Organic–Inorganic Glasses Improve Flame Retardancy of Epoxy/Clay Composites
Authors: Yu Dan , Kleemeier Malte , Wu Guang Mei , Schartel Bernhard , Liu Wei Qu , Hartwig Andreas
Published: May 2011

New low‐melting organic–inorganic glassy polymers containing phosphorus and silicon are synthesized by the reaction between phenylphosphonic acid and methyltrichlorosilane or methyltriethoxysilane. They possess both low‐softening points and high onset decomposition temperatures, which are favorable for preparing flame retardant composites. Although the glass by itself is sensitive to water, the composites are not significantly affected in that way. For glass/clay/epoxy composites glass transition temperature (Tg) as well as storage modulus increase with the glass amount. The glasses improve flame retardancy significantly due to flame inhibition and the formation of fire residue working as protection layer during burning. The total heat evolved is reduced by 23–28% for using 5–15 wt.% glass and the maximum HRR even by 58–48%. The latter effect decreases with increasing glass amount due to an adulterate residue deformation. The combination of glass and clay is proposed as a possible route to enhance flame retardancy.

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The β Phase Formation Limit in Two Poly(9,9‐di‐n‐octylfluorene) based Copolymers
Authors: Bright Daniel W. , Moss Kathryn C. , Kamtekar Kiran T. , Bryce Martin R. , Monkman Andrew P.
Published: May 2011

Random copolymers of poly(9,9‐di‐n‐octylfluorene) (PF8) incorporating 0, 8, 12, 15, and 20% dibenzothiophene (DBT), and copolymers with 2, 5, 8, 12, and 15% dibenzothiophene‐S,S‐dioxide (S‐unit) were synthesised. Absorption and emission spectra of thin films indicate that the DBT system shows a linear decrease of toluene vapour induced β phase with increasing DBT content to a 20% cutoff, whilst in the S‐unit copolymers the β phase is present up to 12% co‐monomer content, and at 15% the characteristic absorption peak is absent or masked. These results demonstrate the limits, in thin films, at which the β phase can be formed in widely used PF8 copolymer systems for device applications and clearly show that it is practical to use copolymers having electron or hole transport units in the polyfluorene backbone and still be able to form efficient β phase emission sites.

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Green tea extract ameliorates reperfusion injury to rat livers after warm ischemia in a dose‐dependent manner
Authors: Liang Rui , Nickkholgh Arash , Kern Michael , Schneider Heinz , Benzing Steffen , Zorn Markus , Büchler Markus W. , Schemmer Peter
Published: May 2011

Scope: Polyphenolic constituents of green tea (Camellia sinensis) have been shown to be potent scavengers of reactive oxygen species (ROS). Thus, this study was designed to assess its effects after liver ischemia–reperfusion.

Methods and results: Fasted Sprague–Dawley rats were gavaged with different concentrations of green tea extract (GTE) 2 h before 90 min of warm ischemia of the left lateral liver lobe (30% of liver). Controls were given the same volume of Ringer's solution. A preparation of pentobarbital sodium (intraperitoneal) and ketamine (intramuscular) was used for anesthesia. After reperfusion, transaminases, liver histology, hepatic microcirculation, and both phagocytosis of latex bead particles as well as the expression of tumor necrosis alpha (TNF‐α) to index cellular activation were investigated. Furthermore, the expression of superoxide dismutase (Mn‐SOD) was assessed. After 90 min of warm ischemia aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) increased dramatically to 1946±272/3244±757 U/L, 1680±134/2080±379 U/L, and 7857±1851/2036±1193 U/L at 2/6 h, respectively. GTE (200 mg/kgbody weight) significantly prevented this increase in a dose‐dependent manner by 21–51% at 2 h and 29–34% at 6 h, respectively. Histology confirmed the protective effects while both TNF‐α expression and phagocytosis of latex beads by Kupffer cells (KCs) were significantly reduced. GTE intake significantly increased the expression of manganese superoxide dismutase. In vivo microscopy revealed improved acinar and sinusoidal perfusion after GTE.

Conclusion: Preconditioning with a single oral dose of GTE ameliorates ischemia–reperfusion injury in liver. Decreased cellular activation and improved microcirculation are the proposed mechanisms.
Green and black tea in relation to gynecologic cancers
Authors: Butler Lesley M. , Wu Anna H.
Published: May 2011

Scope: Observational studies have evaluated the relationship between green tea intake and cancers of the ovary and endometrium, but we are not aware of the published studies on green tea intake and risk of human papillomavirus (HPV)‐related cancers of the cervix, vagina, or vulva.

Methods and results: A critical review of the published literature on tea intake and risk of ovarian and endometrial cancers was conducted. In meta‐analyses, we report inverse associations for green tea intake and risk of ovarian cancer (odds ratio [OR]=0.66; 95% confidence interval [CI]: 0.54, 0.80), and for green tea and risk of endometrial cancer (OR=0.78, 95% CI: 0.62, 0.98). There was no association for black tea and ovarian cancer risk (OR=0.94, 95% CI: 0.87, 1.02) and a positive association with endometrial cancer risk (OR=1.20, 95% CI: 1.05, 1.38). We summarized the experimental evidence supporting the antiviral and immunomodulatory activities of green tea catechins, and results from randomized clinical trials that demonstrated green tea catechin efficacy on treatment of cervical lesions and external genital warts.

Conclusion: Observational data support a protective role of green tea on risk of ovarian and endometrial cancers. Observational data are needed to evaluate whether green tea reduces risk of human papillomavirus‐related cancers.
Mechanisms of proton spin dephasing in a system of magnetic particles
Authors: de Haan Hendrick W.
Published: May 2011

For protons diffusing among a system of magnetic particles, the process by which initial phase coherence is lost depends substantially on particle size. In this article, evidence for three dephasing mechanisms is presented: an incremental process at small particle sizes (motional averaging regime), a discrete process at intermediate particle sizes (visit limited regime), and a continuous process at large particle sizes (static dephasing regime). While motional averaging regime and static dephasing regime are well known, the distinct dynamics in visit limited regime are often overlooked. Revisiting earlier analytic treatments for the dynamics in this regime, Monte Carlo simulations are performed to extract the details of dephasing and to test the concept of an inner zone of rapid dephasing herein named the full dephasing zone. It is shown that the emergence of a full dephasing zone marks the transition from motional averaging regime to visit limited regime since protons can be fully dephased in a single encounter. Moving from the visit limited regime to the static dephasing regime, a crossover between a purely discrete process and a purely continuous process occurs. Developing a simple model of the dephasing process, the average dephasing time is demonstrated to be relatively constant thus giving insight into the long lasting plateau in the relaxation rate. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Functional characterization of EMSY gene amplification in human cancers
Authors: Wilkerson Paul M , Dedes Konstantin J , Wetterskog Daniel , Mackay Alan , Lambros Maryou B , Mansour Marthe , Frankum Jessica , Lord Christopher J , Natrajan Rachael , Ashworth Alan , Reis‐Filho Jorge S
Published: May 2011

The 11q13‐q14 locus is frequently amplified in human cancers, with a complex structure harbouring multiple potential oncogenic drivers. The EMSY gene has been proposed as a driver of the third core of the 11q13‐q14 amplicon. This gene encodes a protein reported to be a BRCA2‐binding partner, which when over‐expressed would lead to impairment of BRCA2 functions and could constitute a mechanism for BRCA2 inactivation in non‐hereditary breast and ovarian cancers. We hypothesized that if EMSY amplification abrogates BRCA2 functions, cells harbouring this aberration would be unable to elicit competent homologous recombination DNA repair and, therefore, may have increased sensitivity to genotoxic therapies and potent PARP inhibitors. Microarray‐based comparative genomic hybridization of cell lines from distinct tumour sites, including breast, ovary, pancreas, oesophagus, lung and the oral cavity, led to the identification of 10 cell lines with EMSY amplification and 18 without. EMSY amplification was shown to correlate with EMSY mRNA levels, although not all cell lines harbouring EMSY amplification displayed EMSY mRNA or protein over‐expression. RNA interference‐mediated silencing of EMSY did not lead to a reduction in cell viability in tumour models harbouring EMSY amplification. Cell lines with and without EMSY amplification displayed a similar ability to elicit RAD51 foci in response to DNA damaging agents, and similar sensitivity to cisplatin and olaparib. Taken together, this suggests that EMSY is unlikely to be a driver of the 11q13‐q14 amplicon and does not have a dominant role in modulating the response to agents targeting cells with defective homologous recombination. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Vertical junction Si cells for concentrating photovoltaics
Authors: Pozner Roni , Segev Gideon , Sarfaty Rona , Kribus Abraham , Rosenwaks Yossi
Published: May 2011

Vertical junction Si cell has shown a potential to operate at high concentrations, mainly the result of reduced series resistance losses due to its low‐current/high‐voltage design, but tests and analyses have so far only shown a modest efficiency of about 20%. We perform a comprehensive optimization study and show that the conversion efficiency of vertical multi‐junction (VMJ) cells can be significantly higher, close to 30% at concentrations of 1000 and higher. Reaching this efficiency requires junction dimensions that are significantly smaller than previous VMJ cells. This may require a different approach in the fabrication process, possibly by using a monolithic method rather than the wafer stacking approach. We also show that increased photoconductivity, which is usually negligible in conventional cells, produces a significant reduction in series resistance at high concentrations making it a significant contributor to the outstanding performance of the VMJ cell at high concentration. Copyright © 2011 John Wiley & Sons, Ltd.
Fabrication of dye sensitized solar cell using Cr doped CuZnSe type chalcopyrite thin film
Authors: Joseph D. Paul , Ganesan S. , Kovendhan M. , Suthanthiraraj S. Austin , Maruthamuthu P. , Venkateswaran C.
Published: May 2011

Chalcopyrites are a versatile class of semiconductors known for their potential in photovoltaic applications. Considering the well established CuInSe2 as a prototype system, a new compound of the chalcopyrite type, Cu1–xZn1–ySe2–δ, by replacing In with Zn, has been prepared (both undoped and 2% Cr doped) by the metallurgical method. Thin films have been deposited by the thermal evaporation technique using the stabilized polycrystalline compounds as charge. Structural, compositional, morphological, and optical properties of the films are analyzed and reported. Use of these films as electrodes in dye sensitized solar cell (DSSC) is demonstrated.
InGaN/GaN short‐period superlattices: synthesis, properties, applications
Authors: Tsatsulnikov A. F. , Lundin W. V. , Sakharov A. V. , Zavarin E. E. , Usov S. O. , Nikolaev A. E. , Kryzhanovskaya N. V. , Sizov V. S. , Synitsin M. A. , Yakovlev E. V. , Chernyakov A. E. , Zakgeim A. L. , Cherkashin N. A. , Hytch M.
Published: May 2011

InGaN/GaN short‐period superlattices were fabricated using method based on cycle conversion of surface InGaN layer to GaN by applying of growth interruptions in hydrogen atmosphere. SPSLs having total thickness from 12 nm to 120 nm were grown and investigated by combination of optical methods, XRD and high resolution transmission electron microscopy (HRTEM) with geometric phase analysis. Blue, deep green (540‐560 nm) and monolithic white LEDs (containing in active region green and blue InGaN QWs separated by the SPSL or GaN barrier) were grown and investigated. Deep green LEDs have maximal external quantum efficiency of 8‐16% in the range of 560‐540 nm correspondingly. Monolithic white LED structures with CCT in the range of 5000‐6000 K have maximal external quantum efficiency of more than 6%. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Origin of the “green gap”: Increasing nonradiative recombination in indium‐rich GaInN/GaN quantum well structures
Authors: Langer Torsten , Kruse Andreas , Ketzer Fedor Alexej , Schwiegel Alexander , Hoffmann Lars , Jönen Holger , Bremers Heiko , Rossow Uwe , Hangleiter Andreas
Published: May 2011

Using time‐resolved photoluminescence spectroscopy on GaInN/GaN multiple quantum well structures, we analyze the radiative and nonradiative processes contributing to the “green gap” in GaN‐based light emitting devices. We observe that it is only partly caused by a reduced oscillator strength due to the Quantum Confined Stark Effect (QCSE) which becomes stronger with increasing indium concentration and well width.

As the dominant effect we observe a reduction of nonradiative lifetimes when the indium concentration is increased. For higher indium concentrations, we find an additional nonradiative recombination path that might be attributed to an increased generation of defects like misfit dislocations, nitrogen vacancies and/or indium clusters within the optically active region. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved quantum efficiency of 350 nm LEDs grown on low dislocation density AlGaN buffer layers
Authors: Kunzer Michael , Gutt Richard , Kirste Lutz , Passow Thorsten , Forghani Kamran , Scholz Ferdinand , Köhler Klaus , Wagner Joachim
Published: May 2011

The effect of buffer layers with reduced defect density on the efficiency of AlGaN based UV LED structures has been investigated. We report on two approaches of defect reduction: Firstly, AlGaN was grown on thin GaN nucleation islands which exhibit a three‐dimensional facetted structure (3D nucleation). Secondly, AlGaN buffer layers with in‐situ SiNx nano‐masking interlayers inserted were employed. Both approaches result in reduced widths of asymmetric high‐resolution X‐ray diffraction ω‐scan peaks. Full LED structures were grown on these buffer layers and are compared to structures grown on a purely 2D grown low Al‐content AlGaN nucleation layer. The influence of the different buffer layer technologies, and hence defect density, on the quantum efficiency has been investigated by excitation‐density and temperature dependent photoluminescence. The data indicate an increase in the PL efficiency from below 5% for 2D nucleation to 15% for 3D nucleation and up to 50% for structures grown on SiNx interlayer buffers. These results are in line with electroluminescence measurements taken on‐wafer. The output power at 40 mA emitted through the substrate for the 3D nucleated LED structure is 0.3 mW which corresponds to an increase by a factor of 9 compared to similar LED structures grown in 2D mode. The same LED structure grown on an AlGaN buffer containing SiNx interlayers showed a 30× enhancement in efficiency with an output power of 0.51 mW at 20 mA, rising linearly to 1.05 mW for a current of 40 mA (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical behavior of GaN‐HEMT after fluoride plasma treatment
Authors: Dagher Gulnar , Nguyen Thi Dak Ha , Péré‐Laperne Nicolas , Mimila‐Arroyo Jaime , Lijadi Melania , Jomard François , Dupuis Christophe , Bardou Nathalie , Pelouard Jean‐Luc
Published: May 2011

Effects of fluorine‐based plasma treatment on the GaN‐based HEMTs electrical properties have been investigated. Two structures have been studied and compared, one with AlGaN alloy barrier and another one with AlN/GaN super‐lattice (SL) barrier. Firstly a large positive threshold voltage (Vth) shift in the structure with AlGaN alloy barrier is observed. Vth shift is due to the incorporation of fluorine into the barrier. As a consequence the 2D‐electron gas density is lower and Vth enlarges. Secondly a small negative Vth shift is obtained in the structure with an AlN/GaN SL barrier. It has been attributed to fluorine n‐type doping in the SL barrier (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dual temperature process for reduction in regrowth interfacial charge in AlGaN/GaN HEMTs grown on GaN substrates
Authors: Eichfeld Sarah M. , Won Dongjin , Trumbull Kathy , Labella Michael , Weng Xiaojun , Robinson Joshua , Snyder David , Redwing Joan M. , Paskova Tanya , Udwary Kevin , Mulholland Greg , Preble Ed , Evans Keith R.
Published: May 2011

The effects of growth temperature and Mg compensation doping on the structural and electrical properties of AlGaN/AlN/GaN high electron mobility transistor (HEMTs) structures grown on low threading dislocation density bulk GaN substrates by metalorganic chemical vapor deposition were investigated. The background electron concentration in the regrown GaN was found to decrease from 1.5x1018 cm‐3 to 2x1016 cm‐3 as the growth temperature was reduced from 1100 °C to 950 °C. A dual temperature process was then employed for growth of the GaN base layer and AlGaN/AlN/GaN top heterostructure in the HEMT along with Mg doping of the GaN base to compensate residual Si donors at the regrown interface. Using this approach, AlGaN/AlN/GaN HEMTs were produced that had a sheet carrier density as high as 1.1x1013 cm‐3 with a room temperature mobility of 1600 cm2/Vs. The incorporation of a thin AlN layer at the regrown interface was found to reduce the sheet carrier density of the overall structure (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of Cd2+ and Mg2+ on the electrical and thermal properties of manganese mercury thiocyanate crystals and its Lewis base adducts‐future materials for photonics device fabrication
Authors: Kumar R. Santhosh , Chandralingam S. , George Sijosh , G. Sreekanth , Augustine Michael , Joseph Ginson P.
Published: May 2011

Single crystasls of pure and doped MMTC and MMTD crystals were grown by slow evaporation technique. The TGA traces of doped crystals show a marginal increase in the thermal stability of the samples. The influence of metal substitution on the dielectric properties of the MMTC and MMTD crystals has been investigated and reported. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
White upconversion luminescence in nanocrystalline (Ho,Tm,Yb):KLu(WO4)2 phosphor
Authors: Barrera E. William , Pujol M. Cinta , Cascales Concepción , Carvajal Joan J. , Mateos X. , Aguiló Magdalena , Díaz Francesc
Published: May 2011

Highly crystalline codoped Ho3+,Tm3+,Yb3+ KLu(WO4)2 monoclinic nanocrystals with the C 2/c space group symmetry were synthesized by the modified Pechini method. Powder X‐ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. The nanocrystals belonged to the monoclinic phase, with a crystallite size of 30‐70 nm. Under 930 nm laser excitation, red, green and blue upconversion emissions were simultaneously observed, due to the energy transfer from the Yb3+ 2F5/2 excited level. The decay times of the emitting states were studied at room temperature to describe the photoluminescence dynamics. The influence of excitation power and calcination conditions on CIE chromaticity coordinates were evaluated. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mobile one‐time passwords: two‐factor authentication using mobile phones
Authors: Eldefrawy Mohamed Hamdy , Khan Muhammad Khurram , Alghathbar Khaled , Kim Tai‐Hoon , Elkamchouchi Hassan
Published: May 2011

Static password authentication has security drawbacks. In two‐factor authentication (2FA,) each user carries a device, called token, to generate passwords that are valid only one time. 2FA based on one‐time passwords (OTPs) provides improved protection because users are prompted to provide something they know (i.e., PIN) and something they have (i.e., token). Many systems have satisfied the 2FA requirements by sending an OTP through an SMS to the user's phone device. Unfortunately, international roaming, and SMS costs, delays, and security put restrictions on this system reliability. Also, time synchronous‐based solutions are not applicable for mobile phones. In this paper, we present a novel 2FA scheme whereby multiple OTPs are being produced by utilizing an initial seed and two different nested hash chains: one dedicated to seed updating and the other used for OTP production. We overcome all the restrictions that come from other techniques. We analyze our proposal from the viewpoint of security and performance compared with the other algorithms. Copyright © 2011 John Wiley & Sons, Ltd.
Quantitative analysis of an organic thin film by XPS, AFM and FT‐IR
Authors: Park Soon Mi , Yu Hyunung , Park Min Gyu , Han Sang Yun , Kang Sang Woo , Park Hyun Min , Kim Jeong Won
Published: May 2011

We report the characterization of Firpic (iridium(III)bis[4,6‐di‐fluorophenyl]‐pyridinato‐N,C2,]picolinate) organic thin film prepared by vacuum deposition to provide a systematic route to organic film quantification. To analyze the characteristics of thin Firpic films on a Si substrate, various techniques such as XPS, Fourier transform infra‐red (FT‐IR) spectrometer, and atomic force microscopy (AFM) are utilized. The Firpic films remain stable without surface morphological or compositional change during deposition and after exposure to X‐ray irradiation or atmospheric environment, for which qualities these films are believed to be an ideal platform as a pure organic thin film. The monotonic increases in FT‐IR and XPS intensities with film thickness are matching well with each other. In particular, from the XPS intensity analysis, the relative atomic sensitivity factors of the present system, electron attenuation length, and molecular density in the organic thin film can be evaluated. Copyright © 2011 John Wiley & Sons, Ltd.
Nanoscale polyoxometalate‐based inorganic/organic hybrids
Authors: Song Yu‐Fei , Long De‐Liang , Ritchie Chris , Cronin Leroy
Published: May 2011

The latest advances in the area of polyoxometalate (POM)‐based inorganic/organic hybrid materials prepared by self‐assembly, covalent modification, and supramolecular interactions are presented. This Review is composed of five sections and documents the effect of organic cations on the formation of novel POMs, surfactant encapsulated POM‐based hybrids, polymeric POM/organic hybrid materials, POMs‐containing ionic crystals, and covalently functionalized POMs. In addition to their role in the charge‐balancing, of anionic POMs, the crucial role of organic cations in the formation and functionalization of POM‐based hybrid materials is discussed. DOI 10.1002/tcr.201100002
A generalized method to determine detectability of rare and cryptic species using the ornate box turtle as a model
Authors: Refsnider Jeanine M. , Mitchell Timothy S. , Streby Henry M. , Strickland Jeramie T. , Warner Daniel A. , Janzen Fredric J.
Published: May 2011

Estimates regarding population parameters are often based on data from surveys. To ensure that such estimates are as accurate as possible, it is important to know the detectability resulting from the particular survey method used. We used radiotelemetry to measure detectability of ornate box turtles (Terrapene ornata), using visual‐encounter surveys in a sand prairie in northwestern Illinois, USA. We found that the overall detection probability of visual‐encounter surveys was 0.03, and our high frequency of nondetection was due to a failure to detect visible turtles rather than turtles being underground or hidden in dense vegetation. Despite the substantial population density at our study site, visual‐encounter surveys failed to detect box turtles on most visits, which resulted in a prohibitively high number of surveys that would be required to accurately estimate population size or to infer absence of the species from a site. Our method of using radiotelemetry to measure detection probability of a survey method could be easily applied to other small, cryptic, or rare species. However, our low detection probability and high frequency of nondetections recommend against use of visual‐encounter surveys alone in estimating population parameters for ornate box turtles. © 2011 The Wildlife Society.
Accuracy for determining sex of white‐tailed deer fetuses
Authors: Strickland Bronson K. , Demarais Stephen , Zamorano Angeline , DeYoung Randy W. , Dacus Chad M.
Published: May 2011

Explanations for variation in fetal sex ratio are needed to better understand the white‐tailed deer (Odocoileus virginianus) life‐history strategy. Sex determination in fetal white‐tailed deer is often based on external morphology and previous studies indicate that fetal sex does not become morphologically distinct until 63–69 days postconception. Until the advent of molecular techniques, there was no means to evaluate observer accuracy or to determine whether fetal sexing is feasible at <63 days postconception. We collected fetuses from wild deer in Mississippi, USA during spring 2008 (n = 55) and 2009 (n = 88) and measured fetal sex classification among 3 groups of observers with differing levels of experience: an inexperienced group (n = 31), an experienced group (n = 3), and a wildlife biologist group (n = 12). We then determined fetal sex using sex‐linked genetic markers and modeled observer accuracy using logistic regression. The inexperienced group required fetuses aged 63 days, 67 days, and 75 days old to correctly classify with 90%, 95%, and 99% accuracy, respectively. The experienced group correctly sexed fetuses at 54 days, 55 days, and 56 days old with 90%, 95%, and 99% accuracy, respectively. The wildlife biologists correctly sexed fetuses at 55 days, 57 days, and 59 days old with 90%, 95%, and 99% accuracy, respectively. Our study was the first to use known‐sex fetuses to estimate observer accuracy of fetal white‐tailed deer at various ages. Our results suggest training observers to recognize fetal tissue development can improve classification accuracy. © 2011 The Wildlife Society.
Does species composition of arctic geese recovered in prairie Canada vary by hunter residency?
Authors: Alisauskas Ray T.
Published: May 2011

Estimates of goose harvest by the National Harvest Survey (NHS) in Canada are based on the assumption that species composition of harvest by non‐Canadians that hunt in Canada is equivalent to that of Canadians. Non‐Canadian hunters are not sampled for composition of species harvested, so differences in proportions harvested per hunter could lead to biased harvest estimates; bias would increase with increasing proportions of unsampled non‐Canadians in relation to sampled Canadian hunters. My objective was to test the assumption of equality of species composition between these 2 strata of hunters for Alberta, Saskatchewan, and Manitoba using recoveries of cackling (Branta hutchinsii), Ross's (Chen rossii), lesser snow (C. caerulescens caerulescens), and greater white‐fronted (Anser albifrons) geese marked south of Queen Maud Gulf in Nunavut, Canada's Central Arctic. I used multinomial logistic regression of recoveries between Canadian and non‐Canadian hunters controlling for hunting season. Non‐Canadian hunters selected Ross's geese over white‐fronted geese compared to Canadians hunting in both Alberta and Saskatchewan, where all 4 species are harvested. Thus, harvest estimates for Ross's geese may be biased low in Alberta and Saskatchewan and those for white‐fronted geese biased high. Waterfowl species harvested by non‐Canadians could be sampled to estimate and correct biases in the NHS. © 2011 The Wildlife Society.
Probing the Metal Composition of Ternary 12–12′‐16 Nanoclusters via Electrospray Ionization Mass Spectrometry
Authors: Howarth Ashlee , Liu JiangJiang , Konermann Lars , Corrigan John F.
Published: May 2011

The reaction of [(3,5‐Me2–C5H3N)2Zn(SeSiMe3)2] with a solution of Cd(OAc)2, Se(Ph)SiMe3 and PPr3 at low temperature was used to prepare single crystals of ternary group 12–12′‐16 nanoclusters with the composition [Zn1.8Cd8.2Se4(SePh)12(PPr3)4]. A ligand exchange reaction using Na[SePh] was performed to displace the neutral PPr3 ligands. The resulting clusters were probed using electrospray ionization mass spectrometry to determine the number of zinc and cadmium atoms in the cluster and compared to the all cadmium cluster [Cd10Se4(SePh)12(PPr3)4]. The dianionic clusters [ZnxCd10–xSe4(SePh)14]2– where x = 0, 1, 2 were assigned in the mass spectra, revealing that the clusters exhibit elemental distributions that are quite narrow in these experiments.
Synthesis and Molecular Structure of Bis(ethylenediamine)acetatonickel(II)hexafluoridophosphate Complex [Ni(en)2(CH3CO2)]PF6. An Unexpected Acetylacetonato Cleavage Reaction
Authors: Martin Maria da Graça M. B. , Hörner Manfredo , Boneberger Behm Mariana , Nunes Fábio S.
Published: May 2011

The title complex was synthesized by an unusual reaction between [Ni(acac)2(H2O)2] and ethylenediamine in water solution. The crystal structure of 1 shows the nickel(II) core in a tetragonally distorted octahedral environment coordinated to two ethylenediamine molecules and one acetate ligand. This is the first example of a mononuclear bis(ethylenediamine)nickel(II) complex, where the oxygen atoms of the auxiliary ligand are in cis configuration. The compound exhibits an extensive association between the complex cation and the respective anion through classical N–H···O and N–H···F intermolecular hydrogen bonds, which generate a supramolecular 3D arrangement in the solid state.
Solvothermal Synthesis, Crystal Structure, and Photocatalytic H2 Evolution of two CuII Coordination Polymers Based on Keggin Polyoxotungstates
Authors: Sun Xianfeng , You Wansheng , Han Xuemei , Ren Li , Huang Cuiying , Liu Meiying
Published: May 2011

Two new CuII coordination polymers based on α‐Keggin polyoxotungstates, [Cu2(dpa)2(H2O)2(GeW12O40)]·0.5CH3COOH (1) and [Hdpa][Cu2(dpa)2(4,4′‐bipy)(H2O)2(PW10V2O40)] (2) (dpa = 2,2′‐dipyridylamine, 4,4′‐bipy = 4,4′‐bipyridine), were obtained by solvothermal reactions in glacial acetic acid and characterized by elemental analysis, IR spectroscopy, TG analysis, X‐ray powder diffraction, and single‐crystal X‐ray diffraction. Compound 1 exhibits a 1D two‐rowed chain constructed from [GeW12O40]4– anions coordinated with [Cu(1)(dpa)]2+ and [Cu(2)(dpa)(H2O)2]2+ fragments by four terminal oxygen atoms. Compound 2 exhibits a 2D layered structure constructed from [PW10V2O40]5– anions coordinated with [Cu(dpa)(4,4′‐bipy)0.5(H2O)]2+ fragments by four terminal oxygen atoms. Furthermore, the electrochemical properties of 1 and the photocatalytic hydrogen production of 1 and 2 were investigated.
Calculation of Some Thermodynamic Properties and Detonation Parameters of 1‐Ethyl‐3‐Methyl‐H‐Imidazolium Perchlorate, [Emim][ClO4], on the Basis of CBS‐4M and CHEETAH Computations Supplemented by VBT Estimates
Authors: Klapötke Thomas M. , Stierstorfer Jörg , Brooke Jenkins H. Donald , van Eldik Rudi , Schmeisser Matthias
Published: May 2011

This paper estimates some thermochemical (in kcal mol–1) and detonation parameters for the ionic liquid, [emim][ClO4] and its associated solid in view of its investigation as an energetic material. The thermochemical values estimated, employing CBS‐4M computational methodology and volume‐based thermodynamics (VBT) include: lattice energy, UPOT([emim][ClO4]) ≈︁ 123 ± 16 kcal·mol–1; enthalpy of formation of the gaseous cation, ΔfH°([emim]+, g) = 144.2 kcal·mol–1 and anion, ΔfH°([ClO4]–, g) = –66.1 kcal·mol–1; the enthalpy of formation of the solid salt, ΔfH°([emim][ClO4],s) ≈︁ –55 ± 16 kcal·mol–1 and for the associated ionic liquid, ΔfHo([emim][ClO4],l) = –52 ± 16 kcal·mol–1 as well as the corresponding Gibbs energy terms: ΔfG°([emim][ClO4],s) ≈︁ +29 ± 16 kcal·mol–1 and ΔfGo([emim][ClO4],l) = +24 ± 16 kcal·mol–1 and the associated standard absolute entropies, of the solid [emim][ClO4], S°298([emim][ClO4],s) = 83 ± 4 cal·K–1·mol–1. The following combustion and detonation parameters are assigned to [emim][ClO4] in its (ionic) liquid form: specific impulse (Isp) = 228 s (monopropellant), detonation velocity (VoD) = 5466 m·s–1, detonation pressure (pC–J) = 99 kbar, explosion temperature (Tex) = 2842 K.
Liver Packing During Elective Surgery: An Option that can be Considered
Authors: Allard Marc Antoine , Dondero Federica , Sommacale Daniel , Dokmak Safi , Belghiti Jacques , Farges Olivier
Published: May 2011

Background

Packing is a life‐saving procedure in patients undergoing emergency surgery for blunt hepatic trauma, especially when massive blood transfusions, acidosis, or hypothermia have resulted in coagulation disorders. The purpose of this study was to apply this concept to the setting of elective liver surgery.

Methods

Elective packing was performed in 7 patients who had sustained prolonged bleeding mainly related to partial outflow obstruction during the course of liver resection (n = 3) or transplantation (n = 4). At the time of packing, conventional methods of hemostasis had failed and surgery had lasted for 490 (range, 380–695) minutes, blood loss was 5,700 (range, 2,100–13,700) ml, and all patients had coagulation disorders (prothrombin time PT <30%, platelets <45 g/l), hypothermia (body temperature 35.4°C), acidosis (median blood pH 7.24; serum lactate 6.5 mmol/l) and required catecholamine support.

Results

Unpacking was performed after a median of 37 (range, 26–60) hours. At that time, all patients were normothermic, with platelet counts >45 g/l, PT >30%, and restored acid‐base balance. Active bleeding had stopped, and secondary fascia closure was feasible. With a minimum follow‐up of 6 months, all patients are alive without sequel.

Conclusions

Packing is a safe and efficient means to control venous bleeding when conventional methods of hemostasis have failed, knowing that commonly the reason for failure of conventional method of hemostasis is partial outflow obstruction.
Motivic invariants ofp-adic fields
Authors: Ormsby Kyle M.
Published: May 2011

We provide a complete analysis of the motivic Adams spectral sequences converging to the bigraded coefficients of the 2-complete algebraic Johnson-Wilson spectra BPGL〈n〉 overp-adic fields. These spectra interpolate between integral motivic cohomology (n= 0), a connective version of algebraicK-theory (n= 1), and the algebraic Brown-Peterson spectrum (n= ∞). We deduce that, overp-adic fields, the 2-completeBPGL〈n〉 splits over 2-complete BPGL〈0〉, implying that the slice spectral sequence forBPGLcollapses.

This is the first in a series of two papers investigating motivic invariants ofp-adic fields, and it lays the groundwork for an understanding of the motivic Adams-Novikov spectral sequence over such base fields.
Taylor bubble moving in a flowing liquid in vertical channel: transition from symmetric to asymmetric shape
Authors: FIGUEROA-ESPINOZA BERNARDO , FABRE JEAN
Published: May 2011

The velocity and shape of Taylor bubbles moving in a vertical channel in a Poiseuille liquid flow were studied for the inertial regime, characterized by large Reynolds numbers. Numerical experiments were carried out for positive (upward) and negative (downward) liquid mean velocity. Previous investigations in tube have reported that for upward flow the bubble is symmetric and its velocity follows the law of Nicklin, whereas for certain downward flow conditions the symmetry is broken and the bubble rises appreciably faster. To study the bubble motion and to identify the existence of a transition, a two-dimensional numerical code that solves the Navier–Stokes equations (through a volume of fluid implementation) was used to obtain the bubble shape and the rise velocity for different liquid mean velocities. A reference frame located at the bubble tip and an irregular grid were implemented to allow long simulation times without an excessively large numerical domain. It was observed that whenever the mean liquid velocity exceeded some critical value, bubbles adopted a symmetric final shape even though their initial shape was asymmetric. Conversely, if the mean liquid velocity was smaller than the critical value, a transition to a non-symmetric shape occurred, along with a correspondingly faster velocity. It was also found that surface tension has a stabilizing effect on the transition.