bluuebunny/crossref_metadata_2025 huggingface dataset:
A Conserved Domain in the Coronavirus Membrane Protein Tail Is Important for Virus Assembly
Authors: Arndt Ariel L. , Larson Blake J. , Hogue Brenda G.
Published: August 2010

Coronavirus membrane (M) proteins play key roles in virus assembly, through M-M, M-spike (S), and M-nucleocapsid (N) protein interactions. The M carboxy-terminal endodomain contains a conserved domain (CD) following the third transmembrane (TM) domain. The importance of the CD (SWWSFNPETNNL) in mouse hepatitis virus was investigated with a panel of mutant proteins, using genetic analysis and transient-expression assays. A charge reversal for negatively charged E
121
was not tolerated. Lysine (K) and arginine (R) substitutions were replaced in recovered viruses by neutrally charged glutamine (Q) and leucine (L), respectively, after only one passage. E
121
Q and E
121
L M proteins were capable of forming virus-like particles (VLPs) when coexpressed with E, whereas E
121
R and E
121
K proteins were not. Alanine substitutions for the first four or the last four residues resulted in viruses with significantly crippled phenotypes and proteins that failed to assemble VLPs or to be rescued into the envelope. All recovered viruses with alanine substitutions in place of SWWS residues had second-site, partially compensating, changes in the first TM of M. Alanine substitution for proline had little impact on the virus. N protein coexpression with some M mutants increased VLP production. The results overall suggest that the CD is important for formation of the viral envelope by helping mediate fundamental M-M interactions and that the presence of the N protein may help stabilize M complexes during virus assembly.
The extent to which chaperone policies are used in acute hospital trusts in England
Authors: Metcalfe Neil H , Moores Karen L , Murphy Naomi P , Pring David W
Published: August 2010

Objective

To determine whether the Ayling Inquiry’s recommendations (2004) concerning chaperone policy implementation in acute hospital trusts in England has been implemented.

Methods

A quantitative questionnaire based on the Ayling Inquiry was posted to medical directors of all acute hospital trusts in England during December 2005 to March 2006 to determine whether their trusts had implemented the inquiry’s recommendations by 1 December 2005. The same questionnaire was resent between December 2007 and March 2008 to determine whether their trusts had implemented the inquiry’s recommendations by 1 December 2007.

Results

The total response rates were 59.4% and 47.7% for the first and second cohorts, respectively. The percentage of trusts having a chaperone policy increased from 41.3% in December 2005 to 56.5% in December 2007. By the end of 2007, 17.3% had accredited training for chaperones, 57.7% had a management lead and 71.2% of trusts formally investigated a breach of the chaperone policy, the latter being a fall from 88.4% in December 2005. Informing patients verbally of the policy was the most common method of distributing the information in both cohorts. By 1 December 2007, 50.0% of trusts did not use any resources towards their chaperone policy. Of the trusts without a chaperone policy by 1 December 2007, 52.5% intend to start a policy.

Conclusion

Despite a public inquiry, only a small majority of acute trusts in England have a chaperone policy in place, which may have severe medico-legal repercussions in the future. Commencing a chaperone policy is a must for acute trusts and regular auditing necessary to ensure recommendations be maintained.
Acer saccharum response to concurrent disturbances: the importance of stem layering as an adaptive trait
Authors: Holmes Stacie A. , Webster Christopher R.
Published: August 2010

For shade-tolerant saplings persisting under heavy forest shade, the probability of release by disturbance is directly related to longevity. We examined the effects of two concurrent disturbances, overstory removal and herbivory, on the regeneration dynamics and release response of Acer saccharum Marsh. within 20 artificial canopy gaps ranging in size from 50 to 450 m2. To examine the influence of herbivory, we constructed arrays of deer exclosures within each canopy gap. Five years after gap creation, A. saccharum dominated the taller sapling classes across the entire range of gap sizes examined, and evidence of stem layering in this species was common across all treatments (52%), especially in taller saplings. The presence of stem layering was significantly associated with greater postdisturbance height growth (P < 0.001), regardless of gap area or herbivory. The increase in height of layered A. saccharum on control plots was in spite of the fact that 70% of these saplings were browsed at least once following gap creation; compared with 46% of nonlayered individuals. Consequently, our results suggest that stem layering likely fosters resilience in the face of complex or interacting disturbances and may be an important trait for forecasting gap capture and succession.
Fuel treatments reduce the severity of wildfire effects in dry mixed conifer forest, Washington, USA
Authors: Prichard Susan J. , Peterson David L. , Jacobson Kyle
Published: August 2010

To address hazardous fuel accumulations, many fuel treatments are being implemented in dry forests, but there have been few opportunities to evaluate treatment efficacy in wildfires. We documented the effectiveness of thinning and prescribed burning in the 2006 Tripod Complex fires. Recent fuel treatments burned in the wildfires and offered an opportunity to evaluate if two treatments (thin only and thin and prescribed burn) mitigated fire severity. Fire severity was markedly different between the two treatments. Over 57% of trees survived in thin and prescribed burn (thinRx) units versus 19% in thin only (thin) and 14% in control units. Considering only large-diameter trees (>20 cm diameter at breast height), 73% survived in thinRx units versus 36% and 29% in thin and control units, respectively. Logistic regression modeling demonstrates significant reductions in the log-odds probability of tree death under both treatments with a much greater reduction in thinRx units. Other severity measures, including percent crown scorch and burn severity index, are significantly lower in thinRx units than in thin and control units. This study provides strong quantitative evidence that thinning alone does not reduce wildfire severity but that thinning followed by prescribed burning is effective at mitigating wildfire severity in dry western forests.
How to build a pectoral fin: functional morphology and steady swimming kinematics of the spotted ratfish (Hydrolagus colliei)
Authors: Foster K. L. , Higham T. E.
Published: August 2010

Aquatic flight is the primary locomotor mode for many animals, including penguins and other diving birds, turtles, and fishes, where labriform and rajiform swimming have been the focus of much interest. However, despite its interesting phylogenetic placement, little is known about the aquatic flight of the sister lineage to the elasmobranchs, the chimaerids. This study investigates the pectoral fin morphology of the spotted ratfish ( Hydrolagus colliei (Lay and Bennett, 1839)) as a possible factor underlying the kinematics of their steady swimming by comparing muscle mass, distribution, and abductor to adductor ratio with those of a closely related shark ( Squalus acanthias L., 1758). Despite fundamental differences in swimming mode, abductor to adductor muscle ratio did not differ between species (P = 0.49). However, the muscle ratio in the spotted ratfish was similar to the range determined in other flapping labriform swimmers. Ratfish had larger, distally placed pectoral fin muscles relative to body size than dogfish (P < 0.0001) possibly aiding in fine control. Stroke amplitude remained constant across body size (P = 0.26) and relative swimming speed (P = 0.23) in the ratfish, whereas the downstroke was significantly faster than the upstroke (P = 0.006). The similar muscle ratio, despite differences in stroke phases, may be explained by physiological or in vivo recruitment differences between abductors and adductors in the ratfish.
A NEW DIRECT ADAPTIVE REGULATOR WITH ROBUSTNESS ANALYSIS OF SYSTEMS IN BRUNOVSKY FORM
Authors: THEODORIDIS DIMITRIOS , BOUTALIS YIANNIS , CHRISTODOULOU MANOLIS
Published: August 2010

The direct adaptive regulation of unknown nonlinear dynamical systems in Brunovsky form with modeling error effects, is considered in this paper. Since the plant is considered unknown, we propose its approximation by a special form of a Brunovsky type neuro–fuzzy dynamical system (NFDS) assuming also the existence of disturbance expressed as modeling error terms depending on both input and system states plus a not-necessarily-known constant value. The development is combined with a sensitivity analysis of the closed loop and provides a comprehensive and rigorous analysis of the stability properties. The existence and boundness of the control signal is always assured by introducing a novel method of parameter hopping and incorporating it in weight updating laws. Simulations illustrate the potency of the method and its applicability is tested on well known benchmarks, as well as in a bioreactor application. It is shown that the proposed approach is superior to the case of simple recurrent high order neural networks (HONN's).
MODELING TRAFFIC JAMS IN SLOW AXONAL TRANSPORT
Authors: KUZNETSOV A. V. , AVRAMENKO A. A. , BLINOV D. G.
Published: August 2010

The purpose of this paper is to develop a model capable of simulating traffic jams in slow axonal transport. Slowing of slow axonal transport is an early sign of some neurodegenerative diseases. Axonal swellings observed near the end stage of such diseases may be an indication of traffic jams developing in axons that cause the slowing down of slow axonal transport. Traffic jams may result from misregulation of microtubule-associated proteins caused by an imbalance in intracellular signaling or by mutations of these proteins. This misregulation leads to a decay of microtubule tracks in axons, effectively reducing the number of "railway tracks" available for molecular-motor-assisted transport of intracellular organelles. In this paper, the decay of microtubule tracks is modeled by a reduction of the number density of microtubules in the central part of the axon. Simulation results indicate that the model predicts the build-up of the bell-shaped concentration wave, as the wave approaches the bottleneck (blockage) region. This increase in concentration will likely plug the bottleneck region resulting in a traffic jam that would hinder the slow axonal transport.
MULTIJOINT COORDINATION OF LOWER EXTREMITY IN TAI CHI EXERCISE
Authors: WANG LIN-HWA , LO KUO-CHENG , LIN CHIEN-JU , SU FONG-CHIN
Published: August 2010

The goal of this study was to investigate the movement coordination among the hip, knee, and ankle joints during solo performance of the Tai Chi (TC) basic movements in order to understand its dynamic postural control. Nine male community-dwelling adults with experienced TC pushing hands participated in this cross-sectional study. The Eagle®motion analysis system with eight cameras was used to collect the trajectories of all reflective markers at sampling rate 100 Hz while the subject performed the ward-off, rollback, press, and push movements. Motion among the hip, knee, and ankle joints was highly coupled. Coupled joint motion, hip flexion-knee flexion-ankle dorsiflexion or reverse, existed in ward-off, rollback, and press phases for the front leg. However, in the push phase, the hip joint angle was kept almost constant with coupled knee and ankle motions. For the rear leg, coupled motion existed between the hip and the knee joints only. The ankle joint motion differed between the front and the rear legs during the basic movements of TC (p < 0.05). Basic characteristics were documented such as the forward knee never extending further than forward toe and both legs maintaining flexion during the full exercise cycle with hip and knee of front and rear legs having synchronized movements in opposite directions. The forward and backward shifts of TC basic movements have considerable contributions to the posture control in terms of the fine coordination of three lower extremity joints. This information could improve training protocol design for TC Chuan teaching and help beginners make an efficient and less damaging movement.
Gain Anisotropy Analysis in Green Semipolar InGaN Quantum Wells with Inhomogeneous Broadening
Authors: Kojima Kazunobu , Yamaguchi Atsushi A. , Funato Mitsuru , Kawakami Yoichi , Noda Susumu
Published: August 2010

Polarization switching phenomena in semipolar (1122)-oriented InGaN quantum wells (QWs) were theoretically investigated by a newly formulated model considering the effect of In compositional fluctuation. The theoretical model successfully reproduced the reported polarization switching phenomena for both the emission wavelength and the excitation density in blue-green (1122) QWs, and this showed the importance of inhomogeneous broadening effects to understand polarization properties of semipolar quantum wells. Then, the model was applied for pure-green (1122) QWs, and we predicted that optical polarization was kept in the [1123] direction up to the carrier density high enough to create population inversion in such long-wavelength QWs. These results support the possibility for semipolar-oriented pure green InGaN laser diodes with cleaved facet cavity mirrors.
Preparation of YBa2Cu3O7-δ Micropatterns Using Metal–Organic Deposition with Electron Beam
Authors: Tanabe Daiji , Yamaguchi Iwao , Tsukada Kenichi , Manago Takashi
Published: August 2010

We investigated microfabrication using the metal–organic deposition (MOD) process with an electron beam. Metal naphthenates in the irradiated area remained after development, which indicates negative exposure characteristics. The optimized electron dose was estimated to be 3400 µC/cm2. Drawn patterns shrink after heat treatment because of the vaporation of organic components. A fine line with a width of 90 nm was successfully obtained after heat treatment. Numerous voids were observed on the surface of the large patterned film, compared with unirradiated films. Electron beam irradiation decomposed metal naphthenates, and cohesion was promoted by the annealing process. The optimization of the annealing profile is required to prepare uniform micropatterns.
Fabrication of Photoconductive Copper Oxide Thin Films by the Chemical Bath Deposition Technique
Authors: Muhibbullah Muhammad , Ichimura Masaya
Published: August 2010

Copper oxide thin films were deposited by the chemical bath deposition technique. CuSO4 and Na2SO3 were used to prepare the deposition solution, and the solution was heated to 70–80 °C. The deposited films are crystalline with a cubic crystal structure and have Cu/O ratios of 1.7–1.8. The oxygen content can be increased by bubbling oxygen gas into the solution during the deposition. It was confirmed by photo-electrochemical measurement that the films are p-type and photoconductive. Thus, the films are potentially useful for photovoltaic applications.
Correlation of Structural and Optical Properties of Sputtered FeSi2Thin Films
Authors: Milosavljević Momir , Wong Lewis , Lourenço Manon , Valizadeh Reza , Colligon John , Shao Guosheng , Homewood Kevin
Published: August 2010

Iron-disilicide films were sputter deposited on Si(100) wafers to 300–400 nm, at substrate temperatures ranging from room temperature to 700 °C. As-deposited films were amorphous at deposition temperatures up to 200 °C, and crystalline β-FeSi2at 300–700 °C. Amorphous films were heat-treated after deposition at 300–700 °C. They remained amorphous up to 400 °C, and transformed to crystalline β-FeSi2at 500–700 °C. Optical absorption measurements showed that the band gap of all films is direct in nature, ranging from 0.88 to 0.93 eV. The deposition temperature was seen to affect the crystallinity of the as-deposited films and to vary their optical properties significantly. The photoabsorption coefficient, measured at 1 eV, increased from 5.6 ×104cm-1for amorphous films to 1.2 ×105cm-1for the samples deposited at 700 °C. The films crystallized by heat-treatment had a markedly different and irregular structure, resulting in their lower optical absorption.
Surface Chemistry of Preferentially (111)- and (220)-Crystal-Oriented Microcrystalline Silicon Films by Radio-Frequency Plasma-Enhanced Chemical Vapor Deposition
Authors: Ohba Daisuke , Lai Chien-Hui , Tang Zeguo , Shirai Hajime
Published: August 2010

The surface chemistry of chlorinated hydrogenated microcrystalline silicon (µc-Si:H:Cl) films with preferred (111) and (220) crystal orientations was investigated by the radio-frequency (rf) plasma-enhanced chemical vapor deposition (PE-CVD) of a dichlorosilane (SiH2Cl2) and H2 mixture. The growing surface of the preferentially (220)-crystal-oriented µc-Si:H:Cl films included many microroughness features, voids, and dangling bonds, and was chemically active to hydrogen and argon plasma exposures. On the other hand, the growing surface with the preferential (111) crystal orientation was chemically stable relatively. These findings suggest that the sticking process of deposition precursors and/or the reconstruction of Si clusters within the subsurface region including microroughness features and dangling bonds determines the growth of the preferential (220) crystal orientation. The determining factor for the preferential crystal orientation is discussed in terms of the growth of µc-Si:H:Cl films.
Dielectric and Piezoelectric Properties of 10% KF-Doped BaTiO3 Ceramics
Authors: Akishige Yukikuni , Hiraki Yuuta , Tsukada Shinya , Xu Jun , Morito Shigekazu , Ohba Takuya , Walker Ezekiel Lee , Neogi Arup
Published: August 2010

10% KF-doped barium titanate powders, Ba0.9K0.1TiO2.9F0.1, were synthesized through a sol–gel process. The powders, calcined at 650 °C, consist of cubic crystalline particles of ∼70 nm in length; the particle size increases to ∼200 nm as the firing temperature increases to ca. 800 °C, above which F2 begins to evaporate. Dense ceramics were fabricated by the spark plasma sintering (SPS) method; the average grain size is ∼2 µm in lengths. The ceramics, well annealed at 1,000 °C in an O2 gas flow, have good dielectric and piezoelectric properties; the piezoelectric d
33 value is 230 pC/N at room temperature. At the ferroelectric Curie temperature T
C = 47 °C, the dielectric constant and loss tan
δ are 10,000 and <5% at 10 kHz, respectively. The Curie–Weiss relation holds in the fully disordered cubic and ordered rhombohedral phases, showing the second order 1:2 relation. Below 10 kHz, large dielectric dispersion caused by a domain-wall motion appears at the temperature range of -50 to 107 °C. Some discussions are made for these dielectric properties of the ceramics.
Highly Ordered Molecular Orientation in a Phthalocyanine Film Deposited on a Well-Polished Indium–Tin Oxide Substrate
Authors: Ishihara Hiroaki , Kusagaya Toyotsugu , Tanaka Senku , Hiromitsu Ichiro
Published: August 2010

Metal-free phthalocyanine (H2Pc) was deposited on an indium–tin oxide (ITO) substrate with a pentacene buffer layer, and the effect of polishing of the ITO surface on the molecular orientation of H2Pc was studied. By rubbing the ITO surface 10,000 times with a plastic eraser, the average surface roughness of ITO was decreased to 1.0 nm from its initial value of 2.0 nm, and the (313) X-ray diffraction peak of α-form H2Pc became significantly large. Rocking curves and optical absorption spectra indicated that, by polishing the ITO surface, the disorder in the orientation of the stacking axis (b-axis) of H2Pc was reduced. A Schottky barrier cell of H2Pc with a highly ordered molecular orientation showed a lower photovoltaic performance than that with a disordered orientation.
Frequency Shift of Terahertz Electromagnetic Waves Originating from Sub-Picosecond-Range Carrier Transport in Undoped GaAs/n-Type GaAs Epitaxial Layer Structures
Authors: Takeuchi Hideo , Yanagisawa Junichi , Tsuruta Syuuichi , Yamada Hisashi , Hata Masahiko , Nakayama Masaaki
Published: August 2010

We have investigated the terahertz electromagnetic waves from undoped GaAs/n-type GaAs (i-GaAs/n-GaAs) structures with various i-GaAs-layer thicknesses, focusing on the relation between the sub-picosecond-range carrier-transport processes and terahertz-wave frequency. It is observed that the intense monocycle oscillation induced by the surge current of photogenerated carriers is followed by the signal of the coherent GaAs longitudinal optical (LO) phonon. The Fourier power spectra of the terahertz waveforms reveal that an increase in the built-in electric field of the i-GaAs layer, which is controlled by the i-GaAs layer thickness, causes a high frequency shift of the band due to the surge current. Consequently, we conclude that the photogenerated carriers are accelerated by the built-in electric field in the sub-picosecond range without being affected by the intervalley scattering. This demonstrates that the frequency tunable terahertz emitters are realized. Furthermore, we find that terahertz band of the coherent LO phonon is relatively intense, compared with those from bulk crystals. This phenomenon is discussed from the viewpoint of the effects of the built-in electric field on the terahertz radiation mechanism.
Variation in Energy Spreading and Modulation Transfer Function for Birefringence Liquid Crystal Lens without Power Modulation
Authors: Ou Chung-Jen , Ou Chung-Ming , Wang Jia-Shi
Published: August 2010

Liquid crystals have been recognized as practical adaptive optical components for imaging and nonimaging applications. We have studied a liquid crystal lens without power modulation, as distinct from a focus modulating lens, and have simulated the effects of transient birefringence on the energy distribution on the focal plane. Our results indicate that owing to the particular transient spreading energy patterns on the focal plane, a focusing reversal phenomenon takes place during the operation of this lens, and the characteristic of the modulation transfer function (MTF) of this device indicates that this lens can serve as a spatial frequency filter.
Optical Properties and X-ray Absorption Fine Structure Analysis of ZnS:Cu,Cl Thin-Film Phosphors
Authors: Ichino Kunio , Kato Haruki , Sakai Yuichiro , Ohmi Koutoku , Honma Tetsuo , Itoh Jun-ichi , Sasakura Asuka
Published: August 2010

ZnS:Cu,Cl thin-film phosphors have been studied for possible application to resin-free white light-emitting diodes (LEDs). The ZnS:Cu,Cl polycrystalline films grown by a molecular-beam deposition technique at relatively high substrate temperatures exhibit strong blue-green photoluminescence (PL). The films with a relatively high (∼1%) Cu concentration exhibit an enhanced near-UV excitation band as well as strong PL, making them suitable for excitation by UV LEDs; however, the transmission in the visible spectral range decreases. The X-ray absorption fine structure analysis of the phosphor films suggests that Cu atoms substitute for Zn sites at low Cu concentrations, whereas excess Cu atoms exist in a different form, possibly as CuS-like precipitates, at high Cu concentrations. The addition of Al donors to the phosphor films enhances the PL intensity and transparency, resulting from a reduction in the amount of the precipitates.
Analysis and Compensation for Artifacts in Three-Dimensional Refractive Index Profiling by Four-Wave Mixing Microscopy
Authors: Kawasumi Takehito , Ozeki Yasuyuki , Itoh Kazuyoshi
Published: August 2010

We analyze the imaging properties of the four-wave mixing (FWM) technique, which allows high-resolution three dimensional (3D) refractive index (RI) mapping inside transparent materials using FWM microscopy. The analysis is based on a modified 3D beam propagation method. By comparing the numerical calculation results with experimental ones, we clarify that the measured RI profiles include artifacts that originate from (a) the refraction of the excitation beam by sample structures and (b) the power variation of FWM signals due to the finite numerical aperture of the collector lens. Artifact (a) can be compensated for using a heuristic method, and the amount of artifact (b) can be reduced by increasing the numerical aperture of the collector lens. These results provide important guidelines for reducing the amount of artifacts in the practical implementation of the FWM technique.
Highly Efficient Lasing Action of Nd3+- and Cr3+-Doped Yttrium Aluminum Garnet Ceramics Based on Phonon-Assisted Cross-Relaxation Using Solar Light Source
Authors: Saiki Taku , Nakatsuka Masahiro , Imasaki Kazuo
Published: August 2010

We constructed a theory to explain the mechanism of laser generation with a high optical–optical conversion efficiency for Nd3+- and Cr3+-doped yttrium aluminum ceramics when sunlight or lamplight sources are used for pumping. As a result, a unique mechanism of laser action was found where the solar or lamp-light power could be converted to laser power with a high efficiency close to 80%, which has not previously been observed. The high conversion efficiency was not only considered to be based on one-to-one photon conversion but on two-photon excitation by a single photon with phonon assistance. Thus, the mechanism of lasing action should include a process where thermal energy is converted to photon energy. The theoretical results we obtained were consistent with those of the experiments.
Temperature Dependence of Performance and Hot-Carrier Immunity in Low-Temperature Polycrystalline Silicon Thin-Film Transistors
Authors: Matsumura Mieko , Toyota Yoshiaki , Hatano Mutsuko , Ohkura Makoto
Published: August 2010

The temperature dependence of the performance and hot-carrier instability of excimer-laser-crystallized low-temperature polycrystalline silicon thin-film transistors (TFTs) is described. The dependence of the TFT's performance on temperature indicates three characteristics: 1) electron mobility decreases with decreasing temperature, whereas the hole mobility is temperature independent; 2) off-leakage current decreases with decreasing temperature; and 3) threshold voltage increases with decreasing temperature. To consider the origin of the temperature dependence of the threshold voltage, estimation using the trap state density obtained by capacitance–voltage analysis is carried out. The main origin is concluded to be the change in the density of occupied defect states owing to the temperature dependence of the Fermi level. Contrary to the mobility, current under the drain-avalanche hot-carrier stress is found to be higher in a cold environment. The more serious current degradation after the stress in a cold environment is attributable to the reduced scattering of hot carriers owing to less lattice vibration.
Multicolor Cholesteric Liquid Crystal Display in a Single-Layered Configuration using a Multi-Pitch Stabilizations
Authors: Bae Kwang-Soo , Jang Yeong-Joon , Moon Yeon-Kyu , Kang Sung-Gon , Cha Uiyeong , Yu Chang-Jae , Jang Jae Eun , Jung Jae Eun , Kim Jae-Hoon
Published: August 2010

We report a cholesteric liquid crystal (ChLC) display with multicolor in a single-layered configuration using a multi-pitch stabilization by reactive mesogen (RM). The cholesteric pitches were modulated by temperature and stabilized at room temperature by polymerization of the RMs through ultraviolet (UV) exposure. In a single-layered ChLC display without any additional layer such as a color filter, multicolor was obtained by a multi-pitch stabilization through spartially selective UV expose at several temperatures.
The Impact of Uni-axial Strain on Low Frequency Noise in Nanoscale p-Channel Metal–Oxide–Semiconductor Field Effect Transistors under Dynamic Body Biases
Authors: Yeh Kuo-Liang , Ku Chih-You , Guo Jyh-Chyurn
Published: August 2010

The impact of local strain on low frequency noise (LFN) in p-channel metal–oxide–semiconductor field effect transistor (pMOSFET) is investigated under dynamic body biases. For 60 nm pMOSFET, the uni-axial compressive strain from embedded SiGe (e-SiGe) in source/drain can contribute 75% effective mobility (µeff) enhancement and the proportional improvement in current (I
DS) as well as transconductance (G
m). However, the strained pMOSFET suffer more than 80% higher LFN (S
ID/I
D
2) compared with the control pMOSFET free from strain engineering. The measured LFN can be consistently explained by mobility fluctuation model and the increase of Hooge parameter (αH) appears as a key factor responsible for the higher LFN in strained pMOSFET. Forward body biases (FBB) is proposed as an effective method adapted to nanoscale devices for improving µeff and suppressing LFN, without resort to strain engineering.
Effects of Ultraviolet Illumination on Resistive Switching Properties of CuxO Thin Film
Authors: Liu Chih-Yi , Hsu Jing-Ming
Published: August 2010

The resistance of an Al/Cu
x
O/Cu structure can reversibly switch between the high resistance state (HRS) and the low resistance state (LRS) with dc voltage application. The use of the conducting filament model was suggested to explain this behavior. The resistive switching from the HRS to the LRS can be induced by dc voltage application, ultraviolet (UV) illumination, or thermal heating. Therefore, the formation of conducting filaments was relative to power and unnecessary with the electric field. Effects of UV illumination and voltage stress on the resistive switching were also investigated to analyze the role of the electrostatic force. The resistive switching from the HRS to the LRS induced by dc voltage application should be dominated by thermochemical reaction and was partially helped by the electrostatic force.
Band Structure Dependence of Electron Mobility in Modulation-Doped Lattice-Matched InAlAs/InGaAs/InAlAs Heterostructures
Authors: Ahn Il-Ho , Joung Hodoug
Published: August 2010

Variable-magnetic-field Hall measurements were performed on modulation-doped In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As double heterostructures to investigate the influence of channel layer thickness on the two dimensional electron gas mobility. Quantitative mobility spectrum analysis revealed that the first and second subband mobilities increased with the channel thickness. This enhancement is attributed to the decreased subband effective mass, subband carrier density, and alloy disorder scattering potential.
Prediction of Energy Loss of Ni0.58Zn0.42Fe2O4 Nanocrystalline and Fe3O4 Nanowire Arrays
Authors: Hamad Mahmoud Aly
Published: August 2010

The hysteretic differential susceptibility in both cases magnetization and demagnetization processes was modeled for Ni0.58Zn0.42Fe2O4 nanocrystalline and Fe3O4 nano wire arrays. It was formulated hysteretic loop of nanoscale magnetic materials in both magnetization and demagnetization processes. Energy loss was predicted in an expression as a result of this model. Equations of hysteretic loop of magnetic nanoscale materials were achieved for Ni0.58Zn0.42Fe2O4 nanocrystalline and Fe3O4 nanowire. A predicted energy loss per unit mass to heat per cycle of both Ni0.58Zn0.42Fe2O4 nanocrystalline and Fe3O4 nanowire array was estimated.
Growth of Millimeter-Scale Vertically Aligned Carbon Nanotubes by Microwave Plasma Chemical Vapor Deposition
Authors: Kim Yooseok , Song Wooseok , Lee Seung Youb , Shrestha Sabita , Jeon Cheolho , Choi Won Chel , Kim Minkook , Park Chong-Yun
Published: August 2010

Millimeter-scale, vertically aligned carbon nanotubes (CNTs) were grown at a relatively low temperature of 700 °C by the microwave plasma chemical vapor deposition. Oxygen and water were used to investigate their role in the growth rate and crystallinity of CNTs. Scanning electron microscopy and transmission electron microscopy were adopted to observe the height and number of walls of the CNTs, respectively. The addition of oxygen significantly increased the growth rate of CNTs (∼23 µm/min) for 70 min, which is three and two times higher than that of normal CNTs and water-assisted CNTs, respectively. Furthermore, the high growth rate was maintained for 220 min and the crystallinity of CNTs, which was evaluated by the G to D band ratio in Raman spectra, was also greatly improved only by introducing oxygen.
Field Electron Emission Devices with Oriented Carbon Nanotubes Dispersed in Aluminum Composites
Authors: Tsuruno Yusuke , Nakanishi Yusuke , Yanagi Hisao , Takizawa Katsuo , Horikawa Yuichi , Yokoyama Kazuyuki , Magario Akira , Noguchi Toru
Published: August 2010

Multiwalled carbon nanotubes (MWNTs) were homogeneously dispersed into aluminum (Al) powder by the elastomer precursor method. MWNT/Al composites were prepared by extrusion molding of the precursor powder and cut into thin plates. Each composite plate was split parallel or perpendicular to the extrusion direction, and used for field emission measurements. The perpendicular cross section exhibited excellent electron emission with a threshold electric field of 2.0 V/µm and a current density of 1.5 mA/cm2 since a considerable number of oriented MWNTs were sticking out of the cross-sectional surface. With those oriented MWNT/Al composite emitters, a flat-panel field emission lamp (FEL) was successfully fabricated by using the side-electron emission device (SEED) structure.
An Abnormal Temperature Dependence of Conductivity in Fullerene Solids
Authors: Sun Yong , Onwona-Agyeman Boateng , Miyasato Tatsuro
Published: August 2010

An abnormal temperature dependence of conductivity has been observed in some fullerene solids, C60, C70, and C60H36 within the temperature range 400–500 K. The temperature dependent conductivity measurements of these fullerene solids with various molecular diameters and moments of inertia indicate that the abnormal conductivity involves a molecular rotation effect in the fullerene solids. Conductivity measurements of the C60 solid samples prepared using various pressures indicate that the abnormal conductivity is also related to a variation of the energy band structure. We are proposing a model to explain this abnormal conductivity observed as that, a reversible annealing effect results in the releasing or trapping of holes in the deep energy levels induced by lattice defects. The contribution of these holes leads to the abnormal variation in the conductivity with temperature.
Effect of Hydrogen Termination on Surface Roughness Variation of Si(110) by Reflow Oxidation during High-Temperature Ar Annealing
Authors: Araki Koji , Isogai Hiromichi , Takeda Ryuji , Izunome Koji , Matsushita Yoshiaki , Zhao Xinwei
Published: August 2010

It is well known that a smooth surface can be realized for silicon (Si) wafers by Si surface reconstruction using high-temperature annealing. We previously reported that it is crucial to maintain a smooth reconstructed surface to restrict accidental oxidation during the unloading process (i.e., reflow oxidation) in high-temperature annealing. The surface roughnesses of both Si(100) and Si(110) were proved by suppressing the reflow oxidation. Furthermore, for suppressing the reflow oxidation, we evaluated the thickness of the reflow oxidation layer and the surface structure of the Si(110) wafer by replacing the injected Ar gas with H2 in the cooling process during high-temperature Ar annealing. The H2 atmosphere condition induced a change by etching the reconstructed surface, and the H-terminated surface on Si(110) formed SiH2, which effectively suppressed the reflow and characteristic line oxidations, resulting in a smooth terrace-and-step structure.
Characteristics of NOx Removal Combining Dielectric Barrier Discharge Plasma with Selective Catalytic Reduction by C3H6
Authors: Wang Xing-Quan , Li Yi , Chen Wei , Lv Guo-Hua , Huang Jun , Zhu Guo-Xian , Wang Xiao-Qian , Zhang Xian-Hui , Wang Da-Cheng , Feng Ke-Cheng , Yang Si-Ze
Published: August 2010

Characteristics of NO
x
removal combining dielectric barrier discharge (DBD) plasma with selective catalytic reduction (SCR) by C3H6 were investigated under the conditions of high NO
x
concentration and high space velocity at various temperatures. Experiment results show that there were no obvious removal of NO
x
and NO in the only C3H6-SCR system and only DBD system individually. But the high NO
x
removal rate was achieved in C3H6-SCR cooperating with DBD plasma system. Especially NO
x
removal rate can reach up to 88.5% at 150 °C simulating diesel engine exhaust temperature. It can be seen that when discharge comes into being, the catalystic activity was enhanced with discharge strengthened, so that the NO
x
was almost completely removed. In the course of NO
x
removal, DBD played an important role in oxidizing NO to NO2 and activating C3H6 and catalysts to reduce NO
x
.
Effects of Surface Modification by Argon Plasma on Peel Strength of Woven-Type Ultrahigh-Molecular-Weight Polyethylene
Authors: Wu Jing-Yi , Lin Sheng-Kai , Tsai Ching-Shan , Huang Chi-Yuan , Yeh Jen-Taut , Chen Ken-Nan
Published: August 2010

In this investigation, the effects of surface modification by argon plasma on peel strength of woven-type ultrahigh-molecular-weight polyethylene (WUHMWPE) fibers were studied. After plasma treatment, free radicals were generated on the WUHMWPE surface and then converted to peroxide by exposure to air. The optimum free radical content for realizing high T-peel strength was 1.27×10-9 mol/mm2 for plasma treatment at 40 W for 4 min. The plasma-treated WUHMWPE (PWUHMWPE) fiber exhibited the hydrophilic property and many anchors. Regarding bonding, the chemical bonding force significantly increased with adhesion strength between the PWUHMWPE fiber and adhesive 3M 1099. Scanning electron microscopy (SEM) images showed that the surface of the PWUHMWPE fibers contained many fibrils. These fibrils can provide peel strength during T-peel testing. Regarding surface modification by plasma treatment, the peel strength of the WUHMWPE surface with adhesive 3M 1099 was increased from 2.58 to 4.39 kgf/in.
Combinatorial Analysis of Plasma–Surface Interactions of Poly(ethylene terephthalate) with X-ray Photoelectron Spectroscopy
Authors: Takenaka Kosuke , Cho Ken , Setsuhara Yuichi , Shiratani Masaharu , Sekine Makoto , Hori Masaru
Published: August 2010

Combinatorial analysis has been demonstrated for the examination of plasma–surface interactions of poly(ethylene terephthalate) (PET) in terms of chemical bonding state, with X-ray photoelectron spectroscopy (XPS). The chemical bonding states have been investigated for PET films exposed to an argon–oxygen mixture plasma with a density gradient sustained with RF power of 88, 175, and 350 W. The XPS results obtained from three batches of experiments showed a slight increase in the bond peaks caused by the oxidation of which PET with an increase in the product of (ion saturation current) × (plasma exposure time), corresponds to ion dose.
Formation of Cobalt and Cobalt-Silicide Nanodots on Ultrathin SiO2 Induced by Remote Hydrogen Plasma
Authors: Kawanami Akira , Makihara Katsunori , Ikeda Mitsuhisa , Miyazaki Seiichi
Published: August 2010

High-density Co nanodots with an areal dot density as high as 2.6 ×1011 cm-2 were formed on thermally grown SiO2 by exposing a ∼1.2-nm-thick Co layer to a remote H2 plasma without external heating. Also, Co-silicide nanodots on SiO2 were fabricated by silicidation of pregrown Si nanocrystals on SiO2, in which self-assembling Si nanocrystals by low pressure chemical vapor deposition (LPCVD), ultrathin Co film formation, and remote H2 plasma treatment were conducted sequentially. Electrical separation among nanodots in each of the Co and Co-silicide samples was verified from the changes in surface potential after charge injection using an AFM/Kelvin probe technique. The surface potential changes due to electron charging to Co nanodots and discharging from Co-silicide nanodots occur at a tip bias of 0 V, which are attributed to the work function difference between Co nanodots and Co-silicide nanodots. From the observation by magnetic force microscopy, Co nanodots can be active elements for both spin and charge storage.
Effect of Argon/Hydrogen Plasma Cleaning on Electroless Ni Deposition on Small-Area Al Pads
Authors: Ikeda Akihiro , Kajiwara Kouhei , Watanabe Naoya , Asano Tanemasa
Published: August 2010

We investigated effect of Ar/H2 plasma cleaning on electroless Ni under-bump metallurgy (UBM) layer formation on small-area Al pads. When 5 ×5 µm2 pads are cleaned with the plasma, electroless Ni grows successfully on them, whereas no growth occurs on pads cleaned with conventional wet chemicals. In the Ni-UBM layer formation process, Zn is deposited by displacement plating on the Al pads before the electroless Ni plating. Microscopic observations, however, reveal that Zn is not successfully deposited on the wet-cleaned Al-pad surface. X-ray chemical analysis indicates that the plasma cleaning effectively removes C contaminations even for small pad sizes.
Etching Characteristics and Mechanism of ZnO and Ga-Doped ZnO Thin Films in Inductively Coupled HBr/Ar/CHF3 Plasma
Authors: Ham Yong-Hyun , Efremov Alexander , Lee Hyun-Woo , Yun Sun Jin , Min Nam Ki , Kim Kwangsoo , Kwon Kwang-Ho
Published: August 2010

The etching characteristics and mechanisms of ZnO and Ga-doped ZnO (Ga-ZnO) thin films in a HBr/Ar/CHF3 inductively coupled plasma were investigated. The etching rate of ZnO was measured as a function of the CHF3 mixing ratio in the range of 0–15% in a HBr:Ar = 5:2 plasma at a fixed gas pressure (6 mTorr), input power (700 W), bias power (200 W), and total gas flow rate (50 sccm). The plasma chemistry was analyzed by a combination of the global (zero-dimensional) plasma model, Langmuir probe diagnostics (LP) and quadrupole mass spectrometer (QMS) analysis. It was found that the densities of both HBr and Br are significantly affected by the reactions with the CHF3 dissociation products, while both the ZnO and Ga-ZnO etching rates follow the behavior of the Br atom density and flux. This suggests that the ZnO and Ga-ZnO etching processes are not limited by the ion-surface interaction kinetics and appear in the reaction-rate-limited etching regime.
Effect of Gas Mixing Ratio on Etch Behavior of Y2O3 Thin Films in Cl2/Ar and BCl3/Ar Inductively Coupled Plasmas
Authors: Kim Moonkeun , Efremov Alexander , Hong MunPyo , Min Nam Ki , Park Hyung-Ho , Baek Kyu-Ha , Kwon Kwang-Ho
Published: August 2010

This paper reports the results of a model-based analysis of the etch mechanism for the Y2O3 thin films in the Cl2/Ar and BCl3/Ar inductively coupled plasma. It was found that the BCl3/Ar plasma provides higher etch rate (except the case of pure BCl3 and Cl2 gases) as well as shows the non-monotonic dependence of the etch rate on the Ar mixing ratio. Plasma diagnostics by Langmuir probes indicated the noticeable influence of Ar mixing ratio on electron temperature and total density of positive ions. Using the model-based analysis of plasma chemistry and etch kinetics, it was demonstrated that the behavior of the Y2O3 etch rate in both gas mixtures generally corresponds to the neutral-flux-limited etch regime of the ion-assisted chemical reaction while the obtained differences cannot be explained assuming the Cl atoms to be the main chemically active species. Probably, in the BCl3-bases plasmas, the etch kinetics is significantly influenced by the BCl
x
radicals.
Large Lattice Misfit on Epitaxial Thin Film: Coincidence Site Lattice Expanded on Polar Coordinate System
Authors: Kaneko Satoru , Akiyama Kensuke , Ito Takeshi , Yasui Manabu , Soga Masayasu , Hirabayashi Yasuo , Funakubo Hiroshi , Yoshimoto Mamoru
Published: August 2010

The growth of an epitaxial film with a large lattice misfit to substrates is interpreted as domain growth with domain matching by the coincidence site lattice (CSL), in which it is assumed that (m×n) film lattice units are superimposed on (k×l) substrate lattice units. The domain matching with all combinations of two lattice units was expanded on a polar coordinate system (polar CSL figure), where the radius and angle are indicative of the domain size and the lateral angle between two superimposed lattices, respectively. The polar CSL figure enable us to visualize the domain matching of all combinations between the two lattice units (k×l) and (m×n). The cubic-on-cubic growth of magnesium oxide on a silicon substrate and the lateral rotation of bismuth cuprate oxide were taken as examples of visualization using the polar CSL figure.
Effects of Surface Coating on Cylinder Rods Prepared Using Sputtering Deposition Method with Modulated Magnetic Field
Authors: Kawasaki Hiroharu , Shibahara Katsuki , Ohshima Tamiko , Yagyu Yoshihito , Suda Yoshiaki
Published: August 2010

Tungsten (W), carbon (C), and titanium (Ti) thin films were prepared on carbide steel cylinder rods using a new magnetron sputtering deposition method to prevent their corrosion or increase their friction resistance. In this method, plasma was generated between the cylinder rod anode substrate and the cylinder pipe targets, and it moved toward the axial direction with the generation of a modulated magnetic field by a low-frequency alternating coil current. Experimental results showed that the surface morphology of the film became smooth, and the surface roughness of the film decreased. Deposition rate and film uniformity increased with the use of a modulated magnetic field, and friction coefficient increased as a result of the film preparation used.
Selective Epitaxial Growth of Silicon for Vertical Diode Application
Authors: Lee Kong-Soo , Yoo Dae-Han , Han Jae-Jong , Hyung Yong-Woo , Kim Seok-Sik , Kang Chang-Jin , Jeong Hong-Sik , Moon Joo-Tae , Park Hyunho , Jeong Hanwook , Kim Kwang-Ryul , Choi Byoungdeog
Published: August 2010

Selectivity control in silicon selective epitaxial growth (SEG) for deep contact patterns, which is one of the key processes for silicon-based stacked devices and cell switches for next generation memories, was studied. Absolute values of selectivity loss during silicon SEG using the most popular H2/dichlorosilane (DCS)/HCl gas system were evaluated using a commercialized inspection tool in 200 mm wafers with real contact patterns. It was revealed that HCl/(DCS+HCl) ratio and the contact structure played a crucial role in suppressing selectivity loss. The number of selectivity losses in an entire wafer was less than 100 when the HCl/(DCS+HCl) ratio was larger than 0.41. The vertical pn diode prepared using the silicon SEG process with elaborate selectivity control showed more remarkable electrical abilities to accommodate current flow than polycrystalline silicon (poly-Si), including the ideality factor and swing, and reverse leakage current.
Optical Emission Spectroscopy of Low-Discharge-Power Magnetron Sputtering Plasmas Using Pure Tungsten Target
Authors: Matsunaga Takeaki , Ohshima Tamiko , Kawasaki Hiroharu , Kaneko Tatsuya , Yagyu Yoshihito , Suda Yoshiaki
Published: August 2010

To study the mechanism of a tungsten oxide (WO3) thin film using an RF magnetron sputtering method, optical emission spectroscopic (OES) measurements for the RF plasma of a pure W target have been performed. We also examined the crystalline structure and atomic composition rate of the prepared thin film using X-ray photoelectron spectroscopy (XPS). Experimental results indicate that Ar I emission peak intensity slightly increased with increasing Ar gas mixture. On the other hand, W I emission peak intensity rapidly increased with increasing Ar gas mixture. The increase rates of these two emission peak intensities are different, which may be due to the difference in emission mechanism. O I emission peak intensity decreased with increasing Ar gas mixture, indicating that O I emission intensity increased with increasing O2 gas mixture. Electron density and deposition rate increased with increasing Ar gas mixture, and their dependences on Ar gas mixture were very similar to that of Ar I emission. XPS analyses indicate that the oxidation ratio of the prepared film was slightly decreased with decreasing Ar gas mixture. These results suggest that the W sources of the WO3 film on the substrate are W atoms and WO
x
molecules sputtered from the W target. The plasma phase reaction between W and O atoms and the intermediate-energy O atomic and/or O2 molecular reaction on the surface of the substrate are considered to be important for WO3 film production in low-energy magnetron sputtering deposition.