bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical properties of InGaN grown by molecular beam epitaxy
Authors: Schaff William J. , Chen Xiaodong , Hao Dong , Matthews Kris , Richards Troy , Eastman Lester F. , Lu Hai , Cho Clara Ji‐Hyun , Cha Ho‐Young 
Published: April 2008

AbstractThe electrical properties of InGaN that is either undoped, or Mg doped, are compared to learn about the nature of p‐type conductivity. For In alloy fraction beyond 5% Hall measurements do not indicate p‐type polarity, even when Mg doping is employed. In contrast, hot probe measurements show that p‐polarity can be measured for the entire range of Mg‐doped In mole fractions. The conflicting polarity indications are primarily the result of surface electron accumulation. Parasitic surface electron conductivity can further be seen in p–n homojunctions at In fractions including 20% and 30%. This has an impact on structures such as solar cells. Temperature variable conductivity and PL from different layer structures provides further understanding of the nature of InGaN:Mg. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of InN thin film by metal‐organic vapor phase epitaxy (MOVPE) on different buffers
Authors: Chang P. H. , Wei Y. Y. , Chen C. W. , Peng H. C. , Ling D. C. , Chen N. C. , Chang C. A. 
Published: April 2008

AbstractSuperconductivity and transport characteristics of high‐quality wurtzite‐structured In‐ and N‐polarity InN thin film on sapphire substrate by metal‐organic vapor phase epitaxy (MOVPE) were presented in this study. Single‐crystalline InN films with various n‐typed carrier concentrations (n = 1 ∼ 6 × 1019cm–3) resulting from nitrogen vacancy (VN) were obtained by changing buffer layers. Superconductivity phase transition at Tc,onset around 3.5 K are observed in both In‐ and N‐polarity InN. This strongly suggest that the superconduc‐ tivity originate in the In‐VN(and/or VN+)‐In chain in the a‐b plane of InN thin film. Our experimental results show that the nitrogen vacancy in a‐b plane of InN thin film must play important roles for the quasi‐2D superconducting network in InN system. Temperature ‐ dependent resistance broadening of InN at T < Tc,onset(K) under zero magnetic fields was observed and can be expressed by Kosterlitz‐Thouless transition. Details were discussed in this paper. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of GaN capping on performance of InAlN/AlN/GaN MOS‐HEMT with Al2O3 gate insulation grown by CVD
Authors: Pozzovivo G. , Kuzmik J. , Golka S. , Čičo K. , Fröhlich K. , Carlin J.‐F. , Gonschorek M. , Grandjean N. , Schrenk W. , Strasser G. , Pogany D. 
Published: April 2008

AbstractWe investigate InAlN/AlN/GaN‐based MOS‐HEMTs with and without a 20 Å‐GaN capping below an Al2O3‐insulator. An excellent reduction of the leakage current, up‐to 6 orders of magnitude, is observed in MOS‐HEMT structures compared to Schottky‐based‐HEMTs, both with GaN capping. In the case of uncapped samples the reduction in the leakage current is 3 orders of magnitude. The maximal transconductance value gm,max for the GaN‐capped‐MOS‐HEMT is about 10% higher than that for the conventional Schottky‐based‐HEMT, while in the case of uncapped devices gm,max is about the same for both Schottky and MOS‐HEMT. Similarly the maximal‐drain‐current in the GaN capped MOS‐HEMT is 950mA/mm, exhibiting an increase of 180mA/mm in comparison to the corresponding conventional Schottky‐based‐HEMT. Performance improvement of MOS structure can be explained by a mobility‐dependent carrier depletion effect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High temperature sensing characteristics of a high performance Pd/AlGaN/GaN Schottky diode hydrogen sensor obtained by oxygen gettering
Authors: Akazawa M. , Hasegawa H. 
Published: April 2008

AbstractHigh temperature sensing characteristics of a Pd/AlGaN/GaN Schottky diode hydrogen sensor were investigated. By applying an oxygen gettering process, the diode showed very small leakage currents even at elevated temperatures. On exposure to 10 Torr hydrogen in an air ambient (200 Torr), the diode showed a large current change of four orders of magnitude. The observed sensing behaviour could be fitted to a theory based on the sensing mechanism involving Schottky barrier height reduction due to interface dipole formation by atomic hydrogen. The diode showed much improved characteristics at 110 °C than at room temperature. This surprising result is explained in terms of the current transport mechanism. The diode showed much better sensing characteristics than those of GaAs and InP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐pixel light emitting diodes with wavelength‐tunable output
Authors: Ng W. N. , Leung C. H. , Lai P. T. , Choi H. W. 
Published: April 2008

AbstractA novel design and implementation of a single‐chip wavelength tunable light emitting diode (LED) is introduced in this paper, with varying emission spectral characteristics ranging between 470 nm (blue) and 525 nm (green). The emission wavelength of green fluorescent microspheres (525 nm), acting as a colour conversion agent, is chosen to be efficiently excited by a GaN LED of 470 nm. It is selectively‐coated onto designated micrometer‐scaled pixels, which are interconnected via metal lines. As a result, the LED allows separate control of optical output either 470 nm, 525 nm or even a mixture of both wavelengths. Since the pixels are of micron‐scale which are non‐resolvable by the unaided human eye, the output appears optically mixed. This type of device, combining the application of micro‐light‐emitting diode and fluorescent microsphere technologies, offers a colour tunable output suitable for a wide range of applications including such as outdoor panel displays. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of AlN interlayer on the transport properties of AlGaN/GaN heterostructures grown on silicon
Authors: Elhamri S. , Mitchel W. C. , Berney R. , Ahoujja M. , Roberts J. C. , Rajagopal P. , Cook J. W. , Piner E. L. , Linthicum K. J. 
Published: April 2008

AbstractHall and Shubnikov‐de Haas effects measurements were performed to identify the impact of inserting a 1nm AlN interlayer between AlGaN and GaN. The transport properties of this AlGaN/AlN/GaN structure were compared to the conventional structure (AlGaN/GaN). Our measurements indicate the AlN interlayer resulted in improved transport in the temperature range studied (300 K‐1.2 K). However, the impact of the AlN layer was found to be much more significant at low temperatures. The improvement is believed to be the result of reduced alloy scattering arising from a stronger confinement of the 2DEG. At 300 K the carrier density and mobility for the AlGaN/AlN/GaN structure were roughly 1.00 x 1013 cm–2 and 1937 cm2/Vs. Whereas those of the conventional structure were 8.57 x 1012 cm–2 and 1523 cm2/Vs. Shubnikov‐de Haas oscillations were observed in both samples at low T. This is an indication that a high quality 2DEG is present in each structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the electronic structures and spectroscopic properties of polyyne and its derivatives
Authors: Yao Shujuan , Zhou Chenggang , Wu Jinping , Li Jiaye , Han Bo , Cheng Hansong 
Published: April 2008

AbstractWe present a theoretical study on the electronic structure and spectroscopic properties of polyyne and its derivatives using periodic density functional theory study and semiempirical ZINDO/s methods. The electronic density of states were calculated, which indicates that polyyne behaves like a semiconductor and the insertion of aromatic groups into the polymer chain gives rise to significant metallic characters in the materials. The vibrational and UV–vis spectra of polyyne and its derivatives were simulated using a monomer or oligomer model. The effects of aromatic insertion into polyyne chain on their electronic and spectroscopic properties were discussed. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Impact of short‐term regulation on hyporheic water quality in a boreal river
Authors: Nyberg Lars , Calles Olle , Greenberg Larry 
Published: April 2008

AbstractWater regulation may alter hydraulic head gradients with consequences for the exchange of water between the river and the hyporheic zone. The objective of this study was to investigate the effect of discharge on hyporheic water quality in a regulated Swedish boreal river during a 10‐day experimental period with a sequence of alternating high‐ and low‐flow episodes. A 250 m reach was instrumented with 28 piezometers placed at 150 and 300 mm below the river bed or below the mean groundwater level in the floodplain, and these piezometers were used to measure temperature, oxygen, electric conductivity and pH. High daily variation in air temperature during the first 3 days was transmitted vertically through the stream water into the hyporheic zone within hours. An oxygen saturation of 100% in the river water corresponded to 60–70% saturation at 150 mm depth and 30% at 300 mm depth. The hyporheic oxygen concentration at 150 mm depth decreased during the experimental period, falling into a range that is potentially harmful to incubating salmonid eggs. This was interpreted as a long‐term response to the overall regulation regime, rather than a response to short‐term water regulation during the experiment. Even though the effect of short‐term regulation on the quality of hyporheic water in the river bed was limited, there was a more pronounced effect on the quality of floodplain hyporheic water. Most of the driving forces for temporal variation of water quality in the river bed came vertically from the river water, rather than from the lateral exchange. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of minor alloying elements on the initial stages of oxidation of austenitic stainless steel materials
Authors: Jussila P. , Lahtonen K. , Lampimäki M. , Hirsimäki M. , Valden M. 
Published: April 2008

AbstractSurface oxidation of Fe‐19Cr‐17Ni, Fe‐19Cr‐18Ni‐1Al and TiC‐enriched Fe‐19Cr‐18Ni‐1Al alloys was investigated by photoelectron spectroscopy (PES). The experiments were conducted at 323 K in pure O2 (2.7 × 10−6 mbar). Composition and morphology of the nanoscale surface oxides were determined quantitatively by inelastic electron background analysis. Moreover, use of synchrotron radiation facilities were necessary to obtain improved sensitivity for studying minor alloying elements such as Al and Si. The results indicate oxygen‐induced segregation of Al, which significantly hinders the oxidation of the major alloying elements Fe and Cr. Ti remains in its inert carbide form. The relative concentration of Fe within the oxide layer was found to increase with the oxide‐layer thickness, indicating greater mobility of Fe relative to other alloying elements. Copyright © 2008 John Wiley & Sons, Ltd.
Information asymmetry and the dismissal of newly appointed CEOs: an empirical investigation
Authors: Zhang Yan 
Published: April 2008

AbstractWhy are some newly appointed CEOs (i.e., those with tenure of three years or less) dismissed while others are not? Drawing upon previous reseach on information asymmetry and adverse selection in CEO selection, I argue that the board of directors may make a poor selection at the time of CEO succession, and as a result, must dismiss the appointee after succession when better information about him/her is obtained. Therefore, the level of information asymmetry at the time of succession increases the likelihood of dismissal. With data on 204 newly appointed CEOs, the results of this study support this argument. After controlling for alternative explanations of CEO dismissal (e.g., firm performance and political factors), the results show that the likelihood of dismissal of newly appointed CEOs is higher in outside successions and/or if the succession follows the dismissal of the preceding CEO. Further, if at the time of succession, the firm's board has a nominating committee that is independent and/or on which outside directors have few external directorships, the likelihood of dismissal is lower. Contributions to the CEO dismissal/succession literature are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Scanning Probe Parallel Nanolithography with Multiprobe Cantilever Array Fabricated by Bulk Silicon Micromachining
Authors: Gandjar Hensy , Takagi Yuki , Matsuzuka Naoki , Isono Yoshitada 
Published: April 2008

AbstractThis work describes a scanning probe parallel nanolithography (SPNL) technique for high throughput in nanometric patterning on single‐crystal silicon (SCS) substrates. Two types of multiprobe cantilever arrays used for SPNL were fabricated by conventional micromachining. All the probes mounted on the free end of each cantilever were made of quasitrihedral pyramidal shape composed of (311) and (411) planes using the originally designed mask. Negative and positive types of nanolithography were performed on the basis of field‐enhanced anodization and self‐assembled monolayer mask techniques, respectively, and they succeeded in drawing a number of nanometric patterns of silicon dioxide (SiO2) on SCS substrates. After anisotropic wet etching of the SCS substrates using the SiO2 films as the mask material, we were also able to fabricate nanowires and nanogrooves. The effects of the applied voltage and scan time of cantilever arrays on wire and groove dimensions were systematically examined by atomic force microscopy (AFM) observations. An optimum condition for the parallel SPNL is proposed on the basis of this research. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Defecation proctography and translabial ultrasound in the investigation of defecatory disorders
Authors: Perniola G. , Shek C. , Chong C. C. W. , Chew S. , Cartmill J. , Dietz H. P. 
Published: April 2008

AbstractObjectivesDefecation proctography is the standard method used in the investigation of obstructed defecation. Translabial ultrasound has recently been shown to demonstrate rectocele, enterocele and rectal intussusception. We performed a comparative clinical study to determine agreement between the two methods.MethodsThirty‐seven women scheduled to undergo defecation proctography for obstructed defecation were recruited. Using both proctography and translabial ultrasound, we determined the anorectal angle, presence of a rectocele and rectocele depth, rectal intussusception and prolapse. Measurements were obtained by operators blinded to all other data. All patients rated discomfort on a scale of 0–10.ResultsSix women did not attend defecation proctography, leaving 31 cases for comparison. The mean age was 53 years. Patients rated discomfort at a median of 1 (range 0–10) for ultrasound and 7 (range 0–10) for defecation proctography (P < 0.001). Defecation proctography suggested rectocele and rectal intussusception/prolapse more frequently than did ultrasound. While the positive predictive value of ultrasound (considering defecation proctography to be the definitive test) was 0.82 for rectocele and 0.88 for intussusception/prolapse, negative predictive values were only 0.43 and 0.27, respectively. Cohen's kappa values were 0.26 and 0.09, respectively. There was poor agreement between ultrasound and defecation proctography measurements of anorectal angle and rectocele depth.ConclusionsTranslabial ultrasound can be used in the initial investigation of defecatory disorders. It is better tolerated than defecation proctography and also yields information on the lower urinary tract, pelvic organ prolapse and levator ani. Agreement between ultrasound and defecation proctography in the measurement of quantitative parameters was poor, but when intussusception or rectocele was diagnosed on ultrasound these results were highly predictive of findings on defecation proctography. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Acinetobacter baumanniiInfections in a Surgical Intensive Care Unit: Predictors of Multi‐drug Resistance
Authors: Katsaragakis Stilianos , Markogiannakis Haridimos , Toutouzas Konstantinos G. , Drimousis Panagiotis , Larentzakis Andreas , Theodoraki Eleni‐Maria , Theodorou Dimitrios 
Published: April 2008

AbstractObjectivesThis study was designed to evaluateAcinetobacter baumanniiinfections incidence in our Surgical Intensive Care Unit, clinical features and outcome of these patients, and multi‐resistance incidence to identify predictors of such a resistance.MethodsProspective study of all patients with ICU‐acquiredAcinetobacter baumanniiinfection from June 1, 2003 to May 31, 2005. Patients with multi‐resistant infection, susceptible exclusively to colistin, were compared with those sustaining non‐multi‐drug resistant infection.ResultsAmong 411 patients, 52 (12.6%) developed Acinetobacter infection. Their mean age was 66.3 ± 8.4 years and APACHE II 20.4 ± 7.3 (men: 51.9%). Infection sites were: bloodstream (46.2%), respiratory tract (32.7%), central venous catheter (11.5%), surgical site (7.7%), and urinary tract (1.9%). High multi‐resistance (44.2%), morbidity (63.4%), and mortality (44.2%) were identified. Colistin was the most effective antibiotic (100% susceptibility), whereas resistance against all other antibiotics was >60%. Previous septic shock (p= 0.04), previous adult respiratory distress syndrome (ARDS) (p= 0.01), number of previous antibiotics (p= 0.01), previous aminoglycoside use (p= 0.04), and reoperation (p= 0.01) were risk factors for multi‐resistance in univariate analysis. Morbidity in the multi‐resistant group was significantly higher than the non‐multi‐resistant group (82.6% vs. 48.2%,p= 0.02). Mortality in the multi‐resistant group also was higher; however, this difference did not marginally reach statistical significance (60.8% vs. 31.1%,p= 0.06). Multivariate analysis identified previous septic shock (p= 0.04; odds ratio (OR), 9.83; 95% confidence interval (CI), 1.003–96.29) and reoperation (p= 0.01; OR, 8.45; 95% CI, 1.52–46.85) as independent predictors of multi‐resistance.ConclusionAcinetobacter baumanniiinfections are frequent and associated with high morbidity, mortality, and multi‐resistance. Avoidance of unnecessary antibiotics is a high priority, and specific attention should be paid to patients with previous ARDS and, particularly, previous septic shock and reoperation. When such risk factors are identified, colistin may be the only appropriate treatment.
Breast Cancer in Chinese Women Younger than Age 40: Are They Different from Their Older Counterparts?
Authors: Kwong Ava , Cheung Polly , Chan Stephanie , Lau Silvia 
Published: April 2008

AbstractBackgroundBreast cancer in young women is uncommon, but when it does occur it has been reported to have aggressive biological characteristics. The incidence of breast cancer peaks at age 40 in Hong Kong Chinese women, earlier than in Caucasians. This study is the first to report the tumor characteristics and management of breast cancer in Chinese women younger than age 40 and a comparison with their older counterparts.Materials and methodsDemographic and clinicopathologic findings of 1,485 Chinese women with breast cancer seen during the period September 2003 to November 2006 were prospectively recorded, and comparisons were made between those who were under the age of 40 and those 40 years of age and older. These results were then compared with a reference population obtained from the Surveillance, Epidemiology and End Results (SEER) database between 2003 and 2004.Results17.6% of the women were younger than 40 years old, and age distribution was significantly different from women in the SEER database. The mean age at menarche was lower in women under age 40 (p < 0.0005), and age at first live birth was also higher (p = 0.017). The rate of first detection by screening mammography was significantly higher among women who were 40 of age and older (p = 0.002). Breast conservation surgery was more commonly performed in the younger age group of Chinese women, particularly when tumor size was less than 2 cm (p = 0.001). A significantly higher proportion of women under age 40 had breast reconstruction (p < 0.001). The majority of women presented with stage 0‐II disease, but in the Chinese groups the younger patients presented at a later stage (p = 0.04). Younger women had higher pathological grade and poorly differentiated tumors (p = 0.02), more nodal involvement (p = 0.024), and lymphovascular permeation involvement (p < 0.001). The majority of tumors were ER and PR positive in both groups, but younger women had a higher proportion of cerbB2‐positive tumors.ConclusionChinese women present with breast cancer at an earlier age. Younger women present with more advanced disease and more aggressive tumor characteristics. More ethnic‐specific screening protocols and treatment decisions may benefit this group of patients.
Fat Utilization in Healthy Subjects Consuming Diacylglycerol Oil Diet: Dietary and Whole Body Fat Oxidation
Authors: Hibi Masanobu , Takase Hideto , Yasunaga Koichi , Yamaguchi Tohru , Harada Ushio , Katsuragi Yoshihisa , Tokimitsu Ichiro 
Published: April 2008

AbstractSeveral studies in animals and humans have reported beneficial effects of diacylglycerol (DAG) on lipid and energy metabolism. We assessed the effect of DAG versus triacylglycerol (TAG) treatment on total energy expenditure (TEE), total fat oxidation (Fox) and respiratory quotient (RQ), and measured the oxidation rate of each oil using a respiratory chamber and the 13C‐stable isotope. Eleven healthy subjects participated in a double‐blind, randomized crossover study. Subjects consumed an energy maintenance diet consisting of 55% of total calories from carbohydrate, 15% from protein and 30% from fat during both the 3‐day pre‐chamber and 36‐h chamber period. Fifty percent of the fat was test oil, containing either DAG oil or TAG oil. The oxidation rate of ingested test oils was determined by monitoring 13CO2 excretion in the breath from 13C‐labeled diolein or 13C‐labeled triolein. There were no significant differences in TEE, RQ and total Fox between the DAG and TAG treatment in the overall analysis. In the subgroup analysis, DAG treatment decreased RQ significantly in subjects with a high fat ratio (HFR) compared to TAG treatment. In addition, ingested diolein oxidation in DAG treatment was significantly faster than triolein oxidation in TAG treatment in the HFR group. Enhanced fat utilization with DAG treatment and rapid oxidation of ingested DAG may, at least in part, explain the greater loss of body weight and body fat related to DAG consumption found in the weight‐loss studies.
Mitochondria, endoplasmic reticulum and actin filament behavior after PDT with chloroaluminum phthalocyanine liposomal in HeLa cells
Authors: Maftoum‐Costa Maíra , Naves Karina Teixeira , Oliveira Alexandre Lima , Tedesco Antonio Cláudio , da Silva Newton Soares , Pacheco‐Soares Cristina 
Published: April 2008

AbstractPhotodynamic therapy (PDT) for cancer is a therapeutic modality in the treatment of tumors in which visible light is used to activate a photosensitizer. Cell membranes have been identified as an important intracellular target for singlet oxygen produced during the photochemical pathway. This study analyzed the cytotoxicity in specific cellular targets of a photosensitizer used in PDT in vitro. The photosensitizing effects of chloroaluminum phthalocyanine liposomal were studied on the mitochondria, cytoskeleton and endoplasmic reticulum of HeLa cells. Cells were irradiated with a diode laser working at 670 nm, energy density of 4.5 J/cm2 and power density of 45 mW/cm2. Fluorescence microscopic analysis of the mitochondria showed changes in membrane potential. After PDT treatment, the cytoskeleton and endoplasmic reticulum presented basic alterations in distribution. The combined effect of AlPHCl liposomal and red light in the HeLa cell line induced photodamage to the mitochondria, endoplasmic reticulum and actin filaments in the cytoskeleton.