bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen Diffusion in Zinc Oxide Thin Films
Authors: Beyer Wolfhard , Breuer Uwe , Hamelmann Frank , Hüpkes Jürgen , Stärk Andrea , Stiebig Helmut , Zastrow Uwe 
Published: July 2009

AbstractHydrogen diffusion in zinc oxide thin films was studied by secondary ion mass spectrometry (SIMS) measurements, investigating the spreading of implanted deuterium profiles by annealing. By effusion measurements of implanted rare gases He and Ne the microstructure of the material was characterized. While for material prepared by low pressure chemical vapour deposition an interconnected void structure and a predominant diffusion of molecular hydrogen was found, sputter-deposited ZnO films showed a more compact structure and long range diffusion of atomic hydrogen. Hydrogen diffusion energies of 1.8 – 2 eV, i.e. higher than reported in literature were found. The results are discussed in terms of a H diffusion model analogous to the model applied for hydrogen diffusion in hydrogenated amorphous and microcrystalline silicon.
Hydrogen-related defects in bulk ZnO
Authors: McCluskey Matthew D , Jokela Slade J. , Tarun Marianne C. 
Published: July 2009

AbstractZinc oxide (ZnO) has attracted resurgent interest as an active material for energy-efficient lighting applications. An optically transparent crystal, ZnO emits light in the blue-to-UV region of the spectrum. The efficiency of the emission is higher than more “conventional” materials such as GaN, making ZnO a strong candidate for solid-state white lighting. Despite its advantages, however, ZnO suffers from a major drawback: as grown, it contains a relatively high level of donors. These unwanted defects compensate acceptors or donate free electrons to the conduction band, thereby keeping the Fermi level in the upper half of the band gap. This paper reviews recent work on hydrogen donors and nitrogen-hydrogen complexes in ZnO.
Improving the High-Temperature Tensile Strength of SiTiC/TiAl Micro Composites by Interface Engineering
Authors: Suzuki Takakazu 
Published: July 2009

AbstractSiC-fiber-reinforced TiAl composites (SiC/TiAl) have attractive attention due to their potential for replacing titanium and nickel-base alloys in aerospace systems such as advanced turbine engines and hypersonic vehicles where specific strength and stiffness at high temperature are critical. The interface layers of SiC/TiAl are believed to contribute strongly to its mechanical properties. A variety of interface modification, such as C, BN, W, and/or Mo coatings has been applied to the fiber to produce composites, together with the identification of several new interface modification systems, showing promise for high-performance fibers and improved composite properties. A research from a perfect cross-sectional view to get more direct and reliable interfacial information especially about bonding around the fiber circumference, has been limited partly due to the difficulty of preparing suitably thin TEM specimen without damaging the interface layers. We report our preparation method for a perfect cross-sectional TEM specimen of SiC/TiAl and the interface characterization results.Single SiC-based Si-Ti-C-O fiber (SiTiC) ˜13 μm in diameter containing about 2% Ti to improve its thermal stability has been used as a reinforcement. Chemical or physical vapor deposition has been used to deposit C or TiAl layer. C layer has been deposited-uniformly around the fiber at a thickness of about 100 nm and TiAl coating at about 1400 nm. C layer consisted of large amounts of micro crystals of about 1-30 nm accumulated around the interface of C layer and fiber. TiAl layer consisted of crystals of about 60-360nm.The specimen has been annealed at 1173 K for 2 hrs in Ar, and prepared by sandwiching and 3mm disks obtained by ultrasonic drilling and mechanical-polishing to ∼100 μm. Those disks have been further ground by a dimpler to ∼10 μm, and argon-ion-milling to get an electron-beam-transparent foil. H-9000UHR II TEM operating at 300 kV, equipped with EDX (prove 1nm) has been used.Interfacial reaction and diffusion mainly occurred in the interface between the C layer and SiTiC fiber and the C and TiAl layers. No direct reaction or diffusion occurred between the SiTiC fiber and TiAl layer. Small amounts of needle-like compound assigned as Aluminum Titanium Carbide, (Ti3AlC)5C, propagating into the fiber has been found at the interface area. These compounds consist of C, Si, O, Ti, and Al, indicating they are reaction and diffusion products of SiTiC fiber and TiAl. Such Aluminum Titanium Carbide propagating into the fiber seems to induce new stress concentration and generate new crack in the fiber and degrade the fiber and the composite strength. Combined with the tensile testing of SiTiC/TiAl single fiber reinforced composites reported previously, we surmise that the large amounts of small crystals accumulating in the C layer contribute to resistance to interfacial reaction and diffusion between the fiber and TiAl layer.
In Vitro Human Osteoblast Responses to Titanium Oxide-Based Surfaces with Varying Topology and Composition
Authors: Collier Charles Andrew , Paillard Julien M. , Markaki Athina E. , Curran James A. , Griffiths Helen J , Clyne T William 
Published: July 2009

AbstractThe surface topology and composition of prosthetic implant materials affect cell responses and are therefore important design features. Plasma electrolytic oxidation (PEO) is a surface modification technique that can be used to produce oxidized surfaces with various surface properties. In this work, Ti-6Al-4V was PEO processed to give two surfaces with different morphologies but similar chemical composition. Surface characteristics were assessed using X ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, stylus profilometry and contact angle measurement.In vitro culture of human foetal osteoblasts (HOB) was performed on the surfaces, to examine cell responses to them. Cellular proliferation, morphology and differentiation were examined, using the AlamarBlue assay, SEM imaging and an alkaline phosphatase (ALP) activity assay respectively. Additionally, the individual effects of oxides present in the PEO processed surfaces (rutile and anatase) on the cells were examined, by binding them in powder form to produce surfaces with similar morphology, but different composition.Changes in the topology and chemistry of the surfaces affected osteoblast response. HOB proliferated more on the rougher PEO surface, and also displayed greater ALP activity. Also, cells responded differently to surfaces containing just rutile or anatase, indicating that the chemical phase of titanium oxide is of consequence for implant design.
Effect of chemical crosslinking on the free-strain recovery characteristics of amorphous shape-memory polymers
Authors: Ortega Alicia M. , Yakacki Christopher Michael , Dixon Sean A. , Greenberg Alan R. , Gall Ken 
Published: July 2009

AbstractThe goal of this study is to investigate the fundamental relationship between the extent of crosslinking and shape-memory behavior of amorphous, (meth)acrylate-based polymer networks. The polymer networks were produced by copolymerization of tert-butyl acrylate (tBA) and poly(ethylene glycol) dimethacrylates of differing molecular weights (PEGDMA). Polymer compositions were tailored via the amount (weight percent (wt%)) and molecular weight of the PEGDMA crosslinking agents added to produce four materials with varying levels of crosslinking (0, 2, 10, and 40 wt% crosslinking agent corresponding to 0, 0.6, 3.2, and 16.6 mole%) and nearly equal glass transition temperatures (Tg). The effect of crosslinking on deformation limits and free-strain recovery is evaluated. Near complete strain recovery was demonstrated by all materials; however, absolute recovery strain decreased with increasing crosslinking due to a corresponding decrease in strain-to-failure. The results provide insights regarding the link between polymer structure, deformation limits, and strain-recovery capabilities of this class of shape-memory polymers. An improved understanding of this relationship is pivotal for optimizing system response for a wide range of shape-memory applications.
Spiral Photonic Actuator
Authors: Kwang-Yong Jin , Seul-Ki Park , Ji-Hyun Jang , Koh Cheongyang , Graham Mattew J , Soo-Jin Park , Changwoon Nah , Myung-Hoon Lee , Cheng Stephen Z. D. , Thomas Edwin , Kwang-Un Jeong 
Published: July 2009

AbstractThere has been a significant effort to create spiral sensors by changing either the periodic d-spacing of the structure or the dielectric constants of the materials by combining the multi-faceted environmental responsiveness of polymer hydrogels with dielectrical structures.1 Reversible spiral switches with dimensional functionalities that respond to chemical environment were constructed. When the spiral photonic actuator was swollen in hydrophilic acetic acid, right-handed spiral structures are formed, while the spiral photonic actuator was swollen in hydrophobic hexane, left-handed spiral structures are formed. All actuators returned back to the transparent planar state after deswelling processes. These reversible spiral photonic actuators can be applied in the application of mechanical actuators, electrical devices, and optical components.
Sensing Materials for the Detection of Chlorine Gas in Embedded Piezoresistive Microcantilever Sensors
Authors: Porter Timothy L. , Vail Tim , Wooley Amanda , Venedam Richard 
Published: July 2009

AbstractEmbedded piezoresistive microcantilever (EPM) sensors provide a small, simple and robust platform for the detection of many different types of analytes. These inexpensive sensors may be deployed in battery-powered handheld units, or interfaced to small, battery-powered radio transmitter-receivers (motes), for deployment in mesh networks of many sensors. Previously, we have demonstrated the use of EPM sensors in the detection of hydrogen fluoride gas, organophosphate nerve agents, volatile organic compounds (VOC’s), chlorinated hydrocarbons in water, and others. Here, we report on the design of EPM sensors functionalized for the detection of chlorine gas, or Cl2. We have constructed EPM sensors using composite materials consisting of a polymer or hydrogel matrix loaded with agents specific for the detection of Cl2 such as NaI. These materials were tested in both controlled laboratory conditions and in outdoor releases. Stability of the sensing materials under conditions of high temperature were also studied. Results are presented for gas exposures ranging from 1000 ppm to 20 ppm.
Influence of Preconditioning and Blocking on Accuracy in Solving Markovian Models
Authors: Bylina Beata , Bylina Jarosław 
Published: July 2009

Influence of Preconditioning and Blocking on Accuracy in Solving Markovian ModelsThe article considers the effectiveness of various methods used to solve systems of linear equations (which emerge while modeling computer networks and systems with Markov chains) and the practical influence of the methods applied on accuracy. The paper considers some hybrids of both direct and iterative methods. Two varieties of the Gauss elimination will be considered as an example of direct methods: the LU factorization method and the WZ factorization method. The Gauss-Seidel iterative method will be discussed. The paper also shows preconditioning (with the use of incomplete Gauss elimination) and dividing the matrix into blocks where blocks are solved applying direct methods. The motivation for such hybrids is a very high condition number (which is bad) for coefficient matrices occuring in Markov chains and, thus, slow convergence of traditional iterative methods. Also, the blocking, preconditioning and merging of both are analysed. The paper presents the impact of linked methods on both the time and accuracy of finding vector probability. The results of an experiment are given for two groups of matrices: those derived from some very abstract Markovian models, and those from a general 2D Markov chain.
Design of the State Predictive Model Following Control System with Time-Delay
Authors: Wang Dazhong , Wu Shujing , Okubo Shigenori 
Published: July 2009

Design of the State Predictive Model Following Control System with Time-DelayTime-delay systems exist in many engineering fields such as transportation systems, communication systems, process engineering and, more recently, networked control systems. It usually results in unsatisfactory performance and is frequently a source of instability, so the control of time-delay systems is practically important. In this paper, a design of the state predictive model following control system (PMFCS) with time-delay is discussed. The bounded property of the internal states for the control is given, and the utility of this control design is guaranteed. Finally, examples are given to illustrate the effectiveness of the proposed method, and state predictive control techniques are applied to congestion control synthesis problems for a TCP/AQM network.
On Directional Change and Anti-Windup Compensation in Multivariable Control Systems
Authors: Horla Dariusz 
Published: July 2009

On Directional Change and Anti-Windup Compensation in Multivariable Control SystemsThe paper presents a novel description of the interplay between the windup phenomenon and directional change in controls for multivariable systems (including plants with an uneven number of inputs and outputs), usually omitted in the literature. The paper also proposes a new classification of anti-windup compensators with respect to the method of generating the constrained control signal.
Automatic Risk Control Based on FSA Methodology Adaptation for Safety Assessment in Intelligent Buildings
Authors: Mikulik Jerzy , Zajdel Mirosław 
Published: July 2009

Automatic Risk Control Based on FSA Methodology Adaptation for Safety Assessment in Intelligent BuildingsThe main area which Formal Safety Assessment (FSA) methodology was created for is maritime safety. Its model presents quantitative risk estimation and takes detailed information about accident characteristics into account. Nowadays, it is broadly used in shipping navigation around the world. It has already been shown that FSA can be widely used for the assessment of pilotage safety. On the basis of analysis and conclusion on the FSA approach, this paper attempts to show that the adaptation of this method to another area—risk evaluating in operating conditions of buildings—is possible and effective. It aims at building a mathematical model based on fuzzy logic risk assessment with different habitat factors included. The adopted approach lets us describe various situations and conditions that occur in creating and exploiting of buildings, allowing for automatic control of the risk connected to them.
Metric and nonmetric dental variation and the population structure of the Ainu
Authors: Hanihara Tsunehiko 
Published: July 2009

AbstractGene flow and genetic drift are important factors affecting geographic variations in human phenotypic traits. In the present study, the effects of gene flow from an outside source on the pattern of within‐ and among‐group variation of the Ainu from Sakhalin Island and three local groups of Hokkaido are examined by applying an R‐matrix approach to metric and nonmetric dental data. The comparative samples consist of their ancestral and neighboring populations, such as the Neolithic Jomon, the subsequent Epi‐Jomon/Satsumon, the Okhotsk culture people who migrated from Northeast Asia to the northeastern part of Hokkaido during a period 1600–900 years B.P., and modern non‐Ainu Japanese. The results obtained by using the census population sizes of the regional groups of the Ainu as an estimate of relative effective population size suggest the possibility of an admixture between the Okhotsk culture people and the indigenous inhabitants in Hokkaido, at least in the coastal region along the Sea of Okhotsk. Such gene flow from Northeast Asian continent may have exerted an effect on the genetic structure of the contemporary Ainu. The present findings indicate that the population structure, as represented by genetic drift and gene flow, tend to be obscured in the results obtained by standard statistical methods such as Mahalanobis' generalized distance and Smith's MMDs. The present extension of the R‐matrix approach to metric and nonmetric dental data provide results that can be interpreted in terms of a genetically, archaeologically, and prehistorically suggested pattern of gene flow and isolation. Am. J. Hum. Biol., 2010. © 2009 Wiley‐Liss, Inc.
Variation in GRIN2B contributes to weak performance in verbal short‐term memory in children with dyslexia
Authors: Ludwig Kerstin U. , Roeske Darina , Herms Stefan , Schumacher Johannes , Warnke Andreas , Plume Ellen , Neuhoff Nina , Bruder Jennifer , Remschmidt Helmut , Schulte‐Körne Gerd , Müller‐Myhsok Bertram , Nöthen Markus M. , Hoffmann Per 
Published: July 2009

AbstractA multi‐marker haplotype within GRIN2B, a gene coding for a subunit of the ionotropic glutamate receptor, has recently been found to be associated with variation in human memory performance [de Quervain and Papassotiropoulos, 2006]. The gene locus is located within a region that has been linked to a phonological memory phenotype in a recent genome scan in families with dyslexia [Brkanac et al., 2008]. These findings may indicate the involvement of GRIN2B in memory‐related aspects of human cognition. Memory performance is one of the cognitive functions observed to be disordered in dyslexia patients. We therefore investigated whether genetic variation in GRIN2B contributes to specific quantitative measures in a German dyslexia sample by genotyping 66 SNPs in its entire genomic region. We found supportive evidence that markers in intron 3 are associated with short‐term memory in dyslexia, and were able to demonstrate that this effect is even stronger when only maternal transmission is considered. These results suggest that variation within GRIN2B may contribute to the genetic background of specific cognitive processes which are correlates of the dyslexia phenotype. © 2009 Wiley‐Liss, Inc.
D10S1423 identifies a susceptibility locus for Alzheimer's disease (AD7) in a prospective, longitudinal, double‐blind study of asymptomatic individuals: Results at 14 years
Authors: Zubenko George S. , Hughes Hugh B. , Zubenko Wendy N. 
Published: July 2009

AbstractTypical forms of Alzheimer's disease (AD) appear to be influenced by multiple susceptibility loci. This report describes the prospective, longitudinal, double‐blind assessment of the age‐specific risk of AD encountered by 325 asymptomatic first‐degree relatives of AD probands who carried the D10S1423 (AD7) 234 bp allele, the APOE E4 allele, or both, after 14 years of systematic follow‐up. A total of 30 incident cases of AD were detected during the first 3752 subject‐years of surveillance. The effects of carrying either or both of the D10S1423 234 bp and APOE E4 alleles on the age‐specific risk of developing AD were determined using Kaplan–Meier survival analysis. The risk of developing AD was the greatest for individuals who carried both alleles (Mantel–Cox statistic = 16.46, df = 3, P = 0.0009; Breslow statistic = 13.38, df = 3, P = 0.004). Cox proportional hazards models were developed to estimate the risk ratios for each genotype, controlling for the potential effects of age at recruitment, sex, and years of education. Only individuals who carried both risk alleles exhibited a risk ratio that differed significantly from 1 (risk ratio = 7.5, P = 0.002, 95% CI = 2.1–27.0). Neither age at recruitment, sex, nor years of education made significant contributions to the model, although women tended to be at greater risk (P = 0.06). Recent evidence that D10S1423 resides within open reading frame C10orf112, whose predicted product resembles a low‐density lipoprotein receptor, suggests a molecular mechanism for this gene–gene interaction. © 2009 Wiley‐Liss, Inc.
Preparation and properties of Mahua oil‐based liquid crystalline pentalkyds
Authors: Tiwari Sangeeta , Tiwari Sandeep 
Published: July 2009

AbstractMedium oil length Mahua oil‐based pentalkyds are prepared with varying degree of excess hydroxyl. These alkyds are subsequently converted into liquid crystalline form by copolymerizing with p‐hydroxy benzoic acid (p‐HBA). Esterification is facilitated by dicyclohexyl carbodiimide (DCC). Graft efficiencies of copolymers are calculated and reported. Characterization of grafted alkyds is carried out using IR, DSC, and polarizing microscope techniques. A sharp melting point indicates liquid crystalline characteristic of p‐HBA grafted alkyds. DSC and polarizing microscope study results further substantiated the observation. Mechanical film properties of LC resins viz., hardness, impact resistance, and adhesion are also reported and compared with the amorphous counterparts. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Algal biofuels: What is the real potential?
Authors: Darzins Al , Garofalo Raffaello 
Published: July 2009

AbstractAlgae are gaining increasing interest as a feedstock for sustainable biofuels production — but what are the real promises and challenges for production at commercial scale? BioFPR Managing Editor Mara Staffilani interviews Al Darzins, Group Manager and Principal Researcher at the National Renewable Energy Laboratory in the USA,and Raffaello Garofalo, Secretary General of the European Biodiesel Board (EBB). To listen to the full interview please go to: http://www.biofpr.com/podcasts
Sensitive determination of protein based on the fluorescence enhancement effect of terbium (III)–epinephrine–protein–sodium dodecylsulfate system
Authors: Guo Yumei , Yang Jinghe , Wu Xia , Mao Hongzhi 
Published: July 2009

AbstractIt was found that the fluorescence of Tb3+–epinephrine (E) complex can be enhanced by both bovine serum albumin (BSA) and sodium dodecylsulfate (SDS), and stabilized by ascorbic acid (AA). It is considered that the fluorescence enhancement of the Tb3+–E–BSA–AA–SDS system originates not only from the hydrophobic microenvironment provided by BSA–SDS, but also from the energy transfer from BSA to Tb3+ in this system. Therefore, a new fluorescence method for the determination of protein concentrations as low as 1.3 × 10−9 g mL−1 BSA is established using Tb3+–epinephrine complex as probe. The method has been applied for the determination of BSA and human serum albumin in actual samples, and the results obtained are satisfactory. Compared with other fluorescence methods, this method is simpler and more sensitive for the determination of protein. The mechanism of the fluorescence enhancement of the system is studied in detail. Copyright © 2009 John Wiley & Sons, Ltd.