bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rhodium‐based Schottky contacts on n‐doped gallium nitride
Authors: Tian F. , Chor E. F. 
Published: April 2008

AbstractElectrical characteristics and thermal stability of Rhodium (Rh)‐based Schottky contacts on n‐GaN, including Rh/Au and Ni/Rh/Au, have been investigated and compared with those of the Ni/Au contact. Although the maximum Schottky barrier height (SBH) of the Rh/Au contact is slightly lower than that of Ni/Au, the inclusion of a thin Ni layer to yield the Ni/Rh/Au contact has led to a maximum SBH of 0.80 eV, surpassing that of Ni/Au by 0.07 eV and leading to a reduced reverse leakage current at ‐1 V by 1 order of magnitude com‐ pared to that of Ni/Au. The good performance of the Ni/Rh/Au contact can be attributed to the co‐existence of Rh and a thin layer of Ni, which leads to limited adverse reaction of Ni with the GaN substrate, and formation of NiO and reduced interfacial defects at the metal/GaN interface. In addition, thermal stability studies have shown that Rh‐based contacts exhibit better morphological stability than Ni/Au, and the Ni/Rh/Au contact has improved thermal stability over Rh/Au and Ni/Au contacts. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sublimation growth of 2 inch diameter bulk AlN crystals
Authors: Chemekova T. Yu. , Avdeev O. V. , Barash I. S. , Mokhov E. N. , Nagalyuk S. S. , Roenkov A. D. , Segal A. S. , Makarov Yu. N. , Ramm M. G. , Davis S. , Huminic G. , Helava H. 
Published: April 2008

AbstractThe technology of sublimation growth of 15 mm diameter bulk single AlN crystals is scaled to grow similar 2‐inch diameter crystals. The best results are currently achieved with the two‐stage technique including 1) seeding and initial growth of 2‐3 mm thick single‐crystal AlN layers on 2‐inch diameter 6H‐SiC wafers in pre‐carbonized Ta crucibles in graphite equipment and 2) growth of bulk AlN crystals on the above AlN layers in tungsten crucibles and equipment. The initial AlN layers prove of good crystallographic quality but may contain up to 6 at.% of Si impurities. The eventual bulk AlN crystals consist of about 40 mm diameter round single‐crystal core and polycrystalline rim. No impurities in concentration higher than 0.01 at.% are found in the bulk crystals. The bulk AlN crystal may be separated from the initial AlN layer to use the latter repeatedly for growth of a new crystal. Such “secondary” crystals were found to be semi‐insulating. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitride photocatalyst to generate hydrogen gas from water
Authors: Iwaki Yasuhiro , Ono Masato , Yamaguchi Kazuki , Kusakabe Kazuhide , Fujii Katsushi , Ohkawa Kazuhiro 
Published: April 2008

AbstractWe propose a new nitride photocatalyst of an n‐n+‐GaN structure to increase H2 gas generation. This structure consists of a thin lightly‐doped n‐type layer on a heavily‐doped n+‐type layer to realize an optimized depletion layer for optical absorption and highly conductive region, respectively. An optimized n‐n+‐GaN structure could generate much more H2 gas rather than a single n‐GaN layer structure by about 1.4 times. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication and optical properties of nano‐structured semipolar InGaN/GaN quantum wells on c‐plane GaN template
Authors: Yu Hongbo , Jung Taeil , Ku P. C. 
Published: April 2008

AbstractHigh density self‐assembled nanostructured semipolar (NSSP) GaN pyramids are fabricated based on c‐plane GaN template by in situ silane treatment followed by high temperature treatment. Semipolar InGaN/GaN multiple quantum wells (MQWs) were subsequently grown on the NSSP GaN. Optical properties of the MQWs were studied by temperature‐ dependent and excitation density varied photoluminescence. It was found that the internal electric field in the NSSP MQWs were remarkably reduced in comparison with planar c‐plane MQWs. The internal quantum efficiency of the NSSP MQWs was measured to be > 30% which showed potential applications in III‐nitride light emitters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties and optical absorption in InN:In structures
Authors: Komissarova T. A. , Plotnikov D. S. , Jmerik V. N. , Shubina T. V. , Mizerov A. M. , Semenov A. N. , Ivanov S. V. , Ryabova L. I. , Khokhlov D. R. 
Published: April 2008

AbstractElectrophysical and optical absorption measurements have been performed for conventional InN epilayers and InN:In composite structures grown by plasma‐assisted molecular beam epitaxy. It is shown that intentional periodical introduction of In metallic inclusions into InN layers results in formation of inhomogeneous arrays of clusters. Their presence modifies the shape of absorption spectra. At the same time, significant amount of indium (up to 1/3 of a thickness) in these structures does not influence noticeably the carrier concentration and mobility. These parameters fall in the range of published data for the conventional InN layers. These finding can indicate that formation of In clusters in InN is a more frequent event than it is currently accepted. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Degradation of III‐nitride laser diodes grown by molecular beam epitaxy
Authors: Xiu H. , Thrush E. J. , Kauer M. , Smeeton T. M. , Hooper S. E. , Heffernan J. , Humphreys C. J. 
Published: April 2008

AbstractThe defects found in electrically degraded GaN‐based lasers have been characterised by transmission electron microscopy. In a laser that had been operated until failure, defects containing contact metals were observed. Combined with data from the laser's current‐voltage characteristics, this suggests that the catastrophic failure may have been caused by local heating. In partially degraded lasers, four different types of defects were observed: cracks, stacking faults, inversion domains and dislocations. Cracks, stacking faults and inversion domains were present before and after the laser failure. The dislocation network, however, was only observed in the active region of a failed laser and may have resulted from recombination enhanced defect migration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of GaN‐based lateral polarity heterostructures
Authors: Lorenz P. , Lebedev V. , Niebelschütz F. , Hauguth S. , Ambacher O. , Schaefer J. A. , Krischok S. 
Published: April 2008

AbstractGaN‐based lateral polarity heterostructures (LPH) were grown on sapphire substrates using molecular beam epitaxy. The LPH samples consist of periodical N‐face (000‐1) (grown directly on Al2O3) and Ga‐face (0001) (grown on a AlN bufferlayer) GaN stripes. The GaN‐based LPH have been characterized using surface sensitive techniques. The GaN‐based LPH consist of smooth Ga‐face (0.4 nm RMS) and N‐face regions of higher roughness (7 nm RMS) with small (<70 nm as measured by atomic force microscopy) and well‐defined inversion domain boundary regions (IDBR). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth mechanism of catalyst‐ and template‐free InN nanorods
Authors: Won Yong Sun , Kim Young Seok , Kryliouk Olga , Anderson Tim 
Published: April 2008

AbstractA feasible mechanism for catalyst‐ and template‐free InN nanorod growth was proposed, consisting of the random nanoparticle nucleation from stable gas phase oligomers and the subsequent directional growth along the c‐axis. A combined study of equilibrium analysis and computational thermochemistry was used to determine the optimal growth conditions – growth temperature and Cl/In ratio – for InN nano‐rod growth based on the proposed mechanism, and the computationally determined values showed a good agreement with reported experimental results. The involvement of InCl3 as a key species in the proposed mechanism required the Cl/In ratio to be ∼ 3 by stoichiometry. The growth zone of InN nanorods by HVPE was demonstrated to lie in the vicinity of the growth‐etch transition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of mass spectra of peptides in different matrices using matrix‐assisted laser desorption/ionization and a multi‐turn time‐of‐flight mass spectrometer, MULTUM‐IMG
Authors: Hazama Hisanao , Nagao Hirofumi , Suzuki Ren , Toyoda Michisato , Masuda Katsuyoshi , Naito Yasuhide , Awazu Kunio 
Published: April 2008

AbstractThe mass spectra of peptides obtained with different matrices were compared using a matrix‐assisted laser desorption/ionization (MALDI) ion source and a multi‐turn time‐of‐flight (TOF) mass spectrometer, MULTUM‐IMG, which has been developed at Osaka University. Two types of solid matrices, α‐cyano‐4‐hydroxycinnamic acid (CHCA) and 2,5‐dihydroxybenzoic acid (DHB), and a liquid matrix made from a mixture of 3‐aminoquinoline and CHCA were used. When measuring the peak signal intensity of human angiotensin II [M+H]+ from a fixed sample position, the liquid matrix produced a stable signal over 1000 laser shots, while the signal obtained with CHCA and DHB decayed after about 300 and 100 shots, respectively. Significant differences in the mass resolving power were not observed between the spectra obtained with the three matrices. Signal peak areas were measured as a function of the cycle number in a multi‐turn ion trajectory, i.e., the total flight time over a millisecond time scale. For both [M+H]+ of human angiotensin II and bovine insulin, the decay of the signal peak area was the most significant with CHCA, while that measured with DHB was the smallest. The results of the mean initial ion velocity measurements suggested that the extent of metastable decomposition of the analyte ions increased in order of DHB, the liquid matrix, and CHCA, which is consistent with the difference in the decay of the signal peak area as the total flight time increased. Copyright © 2008 John Wiley & Sons, Ltd.
Constructing cultural relevance in science: A case study of two elementary teachers
Authors: Patchen Terri , Cox‐Petersen Anne 
Published: April 2008

AbstractClassrooms across the United States increasingly find White teachers paired with ethnic minority students, but few of these teachers are prepared for the disparities such cultural integration presents. This is particularly true vis‐à‐vis science education. While classrooms have diversified, science instruction has not necessarily followed suit. Two theories, constructivism and culturally relevant pedagogy, have been identified as mechanisms to diminish the disparities in science education. Yet culturally relevant pedagogy has not had the same impact as constructivism, even though it has been posited as a crucial means to better assure ethnic minority access to education. A case study of two classroom teachers investigates whether and how constructivism can be leveraged to develop culturally relevant pedagogy in science instruction. Identifying practical possibilities for culturally relevant pedagogy in science education is important for students, teachers, and the future of the U.S. workforce because it provides a means of increasing marginalized students' access to science and technological fields. © 2008 Wiley Periodicals, Inc. Sci Ed 92:994–1014, 2008
The recency of technological inputs and financial performance
Authors: Heeley Michael B. , Jacobson Robert 
Published: April 2008

AbstractInventions differ in terms of the age of the knowledge base they build upon. We examine what effects differences in the recency of knowledge inputs have on financial performance. Using threshold regression analysis, we isolate three regimes that exhibit different associations between recency and stock return. We find that for firms whose new patents use inputs in the mid‐range of the technological recency distribution, the relationship is positive; higher recency leads to higher stock return. However, for firms whose new patents make use of either nascent or very mature technological inputs, the effects are negative; higher recency leads to lower stock return. These findings indicate that it is not firms utilizing the most recent technological inputs that experience the highest returns to their inventive activity. Indeed, firms operating at the technological input frontier have market returns significantly below the mean. Rather, it is firms whose new patents utilize medial‐aged technological inputs (i.e., firms using inputs slightly behind the technology frontier) that tend to experience the highest returns. Copyright © 2008 John Wiley & Sons, Ltd.
Research Trends for Mechanical Characterization of MEMS Materials in Korea: Research Needs and New Developments
Authors: Kim Jae‐Hyun , Lee Hak‐Joo , Choa Sung‐Hoon 
Published: April 2008

AbstractThe mechanical properties of microelectromechanical system (MEMS) materials are the basic parameters for designing MEMS devices and evaluating their reliability. The methods used to measure them, however, are not yet well established, and several unresolved issues require further investigation. In this paper, we introduce recent work on the mechanical characterization of MEMS materials in Korea with an emphasis on research needs and new developments. After a description of the research needs of MEMS industries, research activities on tensile and fatigue tests are introduced. Because of a strong interest in simpler test methods in Korea, their concepts and technical issues are described, especially for indentation, strip‐bending, and pillar compression tests. Some techniques based on atomic force microscope (AFM) are also introduced as new research activities. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Extraction of Alpha Activities from an EEG Obtained During Gum Chewing
Authors: Sakata Osamu , Kohyama Kaoru , Satake Takaaki , Saito Yoichi 
Published: April 2008

AbstractWe propose a method for extracting alpha activities from electroencephalogram (EEG) recordings contaminated by noise from sources such as electromyograms (EMGs), electro‐oculograms (EOGs), or blinking, using independent component analysis (ICA) with simple preprocessing. In the preprocessing, Gaussian signals are connected to the back and front of the original EEG data. Then waveforms of the original EEG are not subjected to any change in shape. In this paper, we extract alpha activities from an EEG recorded while a subject chews gum. As a result, the ICA separation accuracy is often improved, and alpha activities during gum chewing can be successfully extracted. Furthermore, we investigate whether or not the extracted signals satisfy the general characteristics of an alpha rhythm. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Dependence of the LC Parameter on the Temperature Rise of a Resonant Circuit for Hyperthermia Implant
Authors: Kunisaki Junichi , Takano Azusa , Yamada Tsutomu , Takemura Yasushi 
Published: April 2008

AbstractHyperthermia is a therapeutic procedure for raising the body temperature in cancer patients. A resonant circuit is expected to be used as the heating source for hyperthermia, because the circuit can be heated by an applied AC magnetic field. In order to miniaturize the resonant circuit, optimal design of the circuit parameters is essential. In this paper, the characteristics of resonant circuits consisting of various combinations of the inductor and the capacitor are studied. The measurements of temperature rise and the impedance of the circuits determine the optimum circuit parameters. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Color M‐mode propagation velocity, but not its ratio to early diastolic inflow velocity, changes throughout gestation in normal human fetuses
Authors: Moon‐Grady A. J. , Taylor D. , Bennett S. H. , Hornberger L. K. , Tacy T. A. 
Published: April 2008

AbstractObjectivesColor M‐mode propagation velocity (Vp) is a measure of diastolic function in adults and, when combined with early diastolic inflow velocity (E), the ratio E/Vp reflects ventricular filling pressure. Early detection of diastolic compromise may benefit fetal patients at risk for developing heart failure. The objectives of this study were to measure values for Vp and inflow peak E in a group of normal fetuses, to analyze age‐dependent alterations in these measurements, and to evaluate the interobserver and intraobserver variability of the measurements.MethodsThirty‐two normal fetuses at between 20 and 35 weeks' gestation underwent echocardiography. Color M‐mode Vp was measured from the four‐chamber view for the right (RV) and left (LV) ventricles, and mitral and tricuspid inflow velocities were determined by pulsed‐wave Doppler ultrasound. The values obtained were compared with previously reported findings in adults.ResultsAdequate tracings were obtainable in 23 patients for the RV and 29 for the LV. Mean Vp values for the RV (15.3 ± 3.2 cm/s) and LV (20.8 ± 5.6 cm/s) were lower than normal adult values, and Vp values were significantly lower for the RV than the LV (P < 0.001). Applying Bazett's heart rate correction, values for RV (23.4 ± 4.8 cm/s) and LV (31.9 ± 8.7 cm/s) remained lower than normal adult values. There was a linear correlation of Vp with gestational age for the RV (R = 0.69, P < 0.001), and the ratio of E/Vp corrected for heart rate for the RV (1.51 ± 0.26) remained constant throughout gestation. Interobserver bias was high but intraobserver bias low, at 19 and 1.1%, respectively.ConclusionsVp is lower in fetal than in adult life. Vp for the RV changes in a manner indicative of improving diastolic function throughout normal gestation, providing insight into the alterations in diastolic function with gestation that contribute to increases in cardiac output. The use of Vp to assess diastolic function disturbance in fetuses is feasible, but high interobserver variability is problematic. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Risk Factors for Wound Infection After Surgery for Colorectal Cancer
Authors: Nakamura Takatoshi , Mitomi Hiroyuki , Ihara Atsushi , Onozato Wataru , Sato Takeo , Ozawa Heita , Hatade Kazuhiko , Watanabe Masahiko 
Published: April 2008

AbstractBackgroundAmong complications after surgery for colorectal cancer, wound infections may prolong hospitalization and increase healthcare costs. This study was designed to clarify the incidence, risk factors, and pathogens responsible for wound infections after surgery for colorectal cancer.MethodsThe study group comprised 144 patients (94 men and 50 women) with colorectal cancer in whom the same surgeon at Kitasato University Hospital performed resection from January 2004 through December 2005. Their mean age was 67.1 years (range = 38–90). To identify risk factors for surgical wound infections, we examined the following 11 variables: gender, age (>65 vs. ≤65 years), body‐mass index (>25 vs. ≤25 kg/m2), the presence or absence of diabetes mellitus, physical status according to the American Society of Anesthesiologists classification (ASA score), stage of cancer according to the TNM staging system, surgical procedure (laparoscopic colectomy vs. open colectomy), procedure type (right colectomy vs. left colectomy vs. anterior resection), operation time (>180 vs. ≤180 min), intraoperative bleeding volume (>120 vs. ≤120 ml), and the presence or absence of intraoperative transfusion. Tissue specimens of infected wounds were cultured to identify pathogens.ResultsPostoperative wound infections occurred in 12% (17/144) of the patients. In univariate analyses, the incidence of wound infection was 26% (11/43) in patients who underwent open colectomy compared with 6% (6/101) in those who underwent laparoscopic colectomy. This difference was significant (P = 0.001). In multivariate analyses, only surgical procedure was identified as an independent risk factor for wound infection. The odds ratio for open colectomy compared with laparoscopic colectomy was 3.322 (P = 0.021). Pus from infected wounds was cultured in 7 of the 17 patients and cultures were positive for pathogens in 5 patients: 1 laparoscopic colectomy and 4 open colectomy. Bacteroides species were the most common pathogen.ConclusionTo prevent wound infections after surgery for colorectal cancer, laparoscopic surgery should be performed when indicated.
Transglutaminase 2 activity promotes membrane resealing after mechanical damage in the lung cancer cell line A549
Authors: Kawai Yoshiki , Wada Fumitaka , Sugimura Yoshiaki , Maki Masatoshi , Hitomi Kiyotaka 
Published: April 2008

AbstractTransglutaminase is a Ca2+‐dependent enzyme catalyzing protein cross‐linking reactions. We investigated the contribution of this enzyme to the resealing of the injured plasma membrane in animal cells, using a lung cancer‐derived cell line, A549. After mechanical injury by razor‐scratching, the level of membrane resealing was estimated by differential incorporation of dextrans labeled with two distinct fluorescent dyes. The recovery level was decreased in the presence of excess primary amine, as a competitive inhibitor of transglutaminase. We established a cell line that stably expresses shRNA (short hairpin RNA) to specifically inhibit the expression of TGase 2 (tissue‐type isozyme of transglutaminase) and confirmed the suppressed resealing level in the cell. Furthermore, additional expression of TGase 2 rescued the ability for membrane resealing. These results show that, after mechanical damage, this enzyme appeared to contribute to membrane resealing.
Proliferation, multipotency and neuronal differentiation of cryopreserved neural progenitor cells derived from the olfactory neuroepithelium of the adult rat
Authors: Xue Tao , Qiao Li , Qiu Jianhua , Lu Lianjun , Zha Dingjun , Wei Li 
Published: April 2008

AbstractThe use of olfactory neuroepithelium neural progenitor cells for transplantation has attracted attention in the treatment of many neurological disorders, which require efficient recovery methods and cryopreservation procedures. The purpose of this study was to evaluate different cryopreservation techniques for neural progenitor cells derived from the olfactory neuroepithelium (ONe NPCs) in adult rats. Initially, we compared the survival rates of cryopreserved ONe NPCs treated with six different cryoprotectants: dimethylsulfoxide (DMSO), ethylene glycol (EG) and glycerol, each with or without 10% FBS and with two different storage periods in liquid nitrogen (−196 °C), specifically 3 days short‐term storage and 3 months long‐term storage. We assessed the recovery efficiency of ONe NPCs after freezing and thawing by viability testing and colony‐forming assay as well as immunocytochemistry under different conditions. No significant difference in the survival rate was observed among these different cryoprotectants. With these protocols, ONe NPCs retained their multipotency and differentiated into glial (GFAP‐positive), neuronal (NeuN‐positive) and oligodendroglia (Galc‐positive) cells. Collectively, our results imply that, under optimal conditions, ONe NPCs might be cryopreserved for periods of >3 months without losing their proliferative and multipotency activities.