bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategy for the treatment of puerperal metritis and improvement of reproductive efficiency in cows with retained placenta
Authors: Liu Wen-Bor , Chuang Shih-Te , Shyu Ching-Lin , Chang Chao-Chin , Jack Amelia , Peh Huo-Cheng , Chan Jacky
Published: April 2011

The objective of this study was to improve the reproductive efficiency of dairy cows with puerperal metritis (PM) subsequent to retained placenta (RP) using a two-step treatment strategy. A total of 188 postpartum cows, aged from 2 to 8 years, were utilised for 2 experiments. In Experiment 1, cows affected with RP/PM were randomly assigned to two treatment groups. Cows in Group A (n = 17) were treated with 600 mg of ceftiofur intramuscularly for 3 days followed by intrauterine lavage with 0.1% chlorhexidine and infusion with 0.5% povidoneiodine, while cows in Group B (n = 16) received two intrauterine infusions, first with 5 g of oxytetracycline and then with 0.5% povidone-iodine. Cows with normal postpartum findings were regarded as the healthy control group (n = 26). Ultrasonographic examination revealed that the ovarian activities including the appearance of a dominant follicle and days to first ovulation of the cows in Group A during the early postpartum period differed from those of Group B (P < 0.05), which coincided with the results of uterine swabbing for bacteriology. In Experiment 2, cows with normal postpartum findings were allocated to Group D (n = 78), which received an ovulation protocol (GnRH - 7 d PGF2α - 48 h hCG - 24 h AI) on day 50 ± 2 postpartum. Cows affected with PM were randomly divided into two groups, Group E (n = 25) combined the treatments applied in Groups A and D, while Group F (n = 26) repeated the treatment administered in Group E except for uterine lavage. The results indicated that the pregnancy rate within 150 days postpartum and the mean days open in Group E (76.0% and 106.3 ± 4.6 days, respectively) were significantly different from those in Group F (38.5% and 137.9 ± 10.9 days, respectively) (P < 0.05). This study suggests that reproductive efficiency could be improved by using the two-step treatment to regulate uterine involution and an early resumption of ovarian function in cows with RP/PM.
Reproductive function of Hungarian Mangalica boars: Effect of seasons
Authors: Sarlós Péter , Egerszegi István , Nagy Szabolcs , Fébel Hedvig , Rátky József
Published: April 2011

Seasonal changes in testis volume, testosterone (T) productivity (GnRH test) and semen characteristics of Mangalica boars were studied. The biggest testis volume was measured in autumn and the smallest in winter. Significant differences were demonstrated between autumn-winter (P = 0.012) and autumn-spring (P = 0.015) in testis volume. The highest basic T concentration (Tb) was observed in autumn and the lowest in summer. The provoked T concentration (Tincr) was significantly higher in autumn than in spring (P = 0.0007). A strong correlation was observed between T concentrations and testis volume in spring. The highest ejaculate volume was measured in winter while the lowest in autumn. Significant differences were found in semen concentration as well as in the total number of spermatozoa per ejaculate between seasons. The highest number of abnormal sperm cells was observed in spring while the lowest in summer. It can be concluded that the ejaculate of the Mangalica breed tends to be of lower volume and higher sperm concentration as compared to most pig breeds. Seasonal differences could be observed in testicular measurements, testosterone production capacity and sperm morphological features; however, sperm motility remained constantly high during the study.
Experimental inoculation of day-old ducks with Brachyspira pilosicoli and B. alvinipulli
Authors: Thuma Ákos , Dán Ádám , Kaszanyitzky Éva , Fazekas Béla , Tóth Ádám , Glávits Róbert
Published: April 2011

Two groups of one-day-old Peking ducklings (Groups I and II, 12 birds/group) were inoculated orally withBrachyspira pilosicoliand two groups withB. alvinipulli(Groups III and IV, 12 birds/group). T-2 toxin was added to the feed of Groups II and IV in a dose of 1 mg/kg of feed. Groups V and VI served as uninfected control groups (ducks of Group VI received T-2 toxin). The body weight gain of the ducks was measured and clinical signs were monitored continuously. The birds were sacrificed and necropsied on days 7, 14, 21, and 28 post infection (PI). The liver, spleen, kidney, thymus, bursa of Fabricius, ileum, caecum and colon were examined histologically. Culturing ofBrachyspiraspp. and immunohistochemistry were performed from the sampled parts of the intestines as well. No gross pathological or histological lesions that could be associated withB. pilosicoliorB. alvinipulliwere detectable in the intestinal mucous membrane including the colonised intestinal glands. Mortality did not occur during the experimental period. Decrease in body weight gain was significant in the T-2-toxin-treated groups, and it was slight (not significant) in theBrachyspira-infected groups. Crust on the beaks, necrosis, crusting and ulceration in the mucous membrane of the oral cavity and on the skin of the feet, atrophy of the thymus and bursa of Fabricius due to the effect of T-2 toxin, accompanied by lymphocyte depletion, were observed. These lesions were most prominent on days 14 and 21 PI but were seen on day 28 PI as well. Immunohistochemical detection and reisolation ofB. pilosicoliandB. alvinipulliwere successful on days 7, 14, 21 and 28 days from different segments of the intestine of certain birds, but no significant difference was observed in the colonisation rate between the T-2-toxin-treated and the untreated groups.
Smart Systems for Enhanced Integrity of Existing and Future Structures
Authors: Boller Christian
Published: April 2011

Ageing is a general problem also applicable in engineering. Many of our engineering struc-tures are seemingly built ageless. Others were built with higher safety factors to cope with the lack of engineering knowledge at the time, where enhanced knowledge nowadays allows these structures to be used longer than initially anticipated. Consequently new design principles may allow future structures to be further built lighter weight. Much of this enhancement can result from the implementation of smart systems technologies into design. This paper will give a few examples based on integrated sensing as well as actuation principles into structures.
Magnetostriction and Crystallographic Texture in Rolled and Annealed Fe-Ga Based Alloys
Authors: Na Suok-Min , Flatau Alison B.
Published: April 2011

Results that demonstrate the selective development of {100}<001> preferred texture in polycrystalline Fe81.3Ga18.7 plus B (0.5∼1.0 at.%) and S (∼0.05 at.%) alloys using a conventional rolling and annealing processes are presented in this work. We found that boron improved ductility by enhancing grain boundary cohesion during rolling and sulfur played an important role in controlling the surface energy and formation of the selective growth of {100} grains during annealing. The as-rolled (Fe81.3Ga18.7)+0.5 at.%B+0.005 at.%S sheet had some {100}<011> and near {111}<011> texture corresponding to α-fiber texture parallel to the rolling direction. The near {100}<001> sheet texture was formed in sheet that was annealed at 1200°C for 2h (198 ppm), while the texture of sheet annealed at 1100°C for 4h (165 ppm) was closer to {110}<001>. The maximum observed magnetostriction of 220 ppm was obtained as a result of a double annealed, first at 1000°C for 6h and then at 1200°C for 1h, with the resultant texture closer to the ideal {100}<001> than the less desirable {100}<011>.
A novel fabrication technique by composite material processing: Integrated metal-insulator-semiconductor fibers and fiber devices
Authors: Bayindir Mehmet , Abouraddy Ayman F. , Shapira Ofer , Viens Jeff , Joannopoulos John D. , Fink Yoel
Published: April 2011

Fabrication of functional devices in fibers by thermal drawing requires a material identification scheme and challenging composite material processing. A macroscopic preform rod containing metallic, semiconducting and insulating constituents in a variety of geometries and close contact leads to kilometer-long novel optoelectronic, and thermal mesoscopic fiber devices. The preform-to-fiber approach yields spectrally tunable photodetectors and integrated self-monitoring fibers.
Applications of Smart Materials in the Developement of High Performance Biosensors
Authors: Cheng Z.-Y.
Published: April 2011

High performance biosensors are urgently needed from medical diagnosis, to food safety/security, to the war on bio-terrorist. The smart materials play an important role in the development of high performance sensor platform. Biosensors based on microcantilevers have very high sensitivity. The microcantilevers made of different materials, such silicon, piezoelectric and magnetostrictive materials, are discussed and compared in this paper. The magnetostrictive-based microcantilevers exhibit the best performance among all microcantilevers. A new sensor platform – magnetostrictive particles (MSPs) – is reported. The advantages of MSPs over microcantilevers are experimentally demonstrated. The MSPs are wireless/remote sensors, which makes it is possible to employ the MSP-based biosensors in different environments/media. The fabrication of MSPs in micro to nano-scale is reported. Compared with the microcantilevers, MSPs exhibit a better mass sensitivity and a higher Q value, which make the MSPs a much higher overall sensitivity.
Electrical Properties Of Electrospun Poly (Ethylene Oxide) - Polypyrrole Composite Fibers
Authors: Sundaray Bibekananda , Subramanian V. , Natarajan T. Srinivasan
Published: April 2011

Electrospinning is a simple method of obtaining polymer fibers with nanometer diameter. The increase in the ratio of surface area to volume in the case of such fibers, make them attractive in applications such as sensors, etc. It is difficult to electrospin Polypyrrole (PPy) directly to form fibers. Hence electrospinning is attempted with a composite formed with PPy and any other insulating polymer such as Polyethylene oxide (PEO), Polystyrene (PS), etc. The concentration of PPy can be varied to improve the electrical or sensing properties of the resulting composite. In the present report, the PEO-PPy composite fibers with different weight percentages (10% to 50% w/w) are prepared by electrospinning process. The fibers obtained are characterized using SEM (Scanning Electron Microscope) and TEM (Transmission Electron Microscopy). I-V Characteristics are studied for single and multiple aligned fibers obtained on gold electrodes. The variation of electrical conductivity with different concentration of PPy is discussed.
Highly Thermal Stable Lambda-Shaped Main-Chain Nonlinear Optical Polyimide
Authors: Tsai Hsieh-Chih , Kuo Wen-Jang , Hsiue Ging-Ho
Published: April 2011

In poled electro-optical (E-O) polymer systems, the relaxation of oriented chromophores is maintained by either introducing the guest chromophores into host polymers with high glass transition temperatures, or by confining the chromophores in polymer networks. Various highly stable NLO polymers have been prepared by grafting NLO-active chromophores onto aromatic polyimide backbones. The pendent chromophores of side chain polyimides can be stabilized at low temperature because they have rigid rod-like structures. However, the orientation decays quickly at elevated temperatures because the local free volumes that surround the chromophores increase. Taking advantage of the multifunctional characteristics of carbazole along with rational molecular design, a new NLO-active lambda-shape main-chain polyimide that comprises the two-dimensional carbazole chromophore was synthesized. This polyimide exhibits high thermal and temporal stability. it can endure as high as 240 °C in a transient time and maintain large SH signal at 100 °C for a long time. The high-glass transition polyimide as a matrix and embedding the two-dimensional chromophore into the polymer backbone are the major reasons that effectively restrict randomization of the oriented dipole.
Localization of 5f electrons and phase transitions in americium
Authors: Pénicaud Michel
Published: April 2011

Density-functional electronic calculations have been used to investigate the high-pressure behavior of americium.The phase transitions calculated agree with the recent sequence obtained experimentally under pressure: double hexagonal close packed → face centered cubic → face centered orthorhombic, primitive orthorhombic. In the first three phases the 5f electrons are found localized, only in the fourth phase (Am IV) the 5f electrons are found delocalized. The localization of the 5f electrons is modelled by an anti-ferromagnetic configuration which has a lower energy than the ferromagnetic ones. In this study the complex crystal structures have been fully relaxed.
Optical Absorption, Stability and Structure of NpO2+Complexes with Dicarboxylic Acids
Authors: Tian Guoxin , Rao Linfeng
Published: April 2011

Complexation of NpO2+with oxalic acid (OX), 2,2'-oxydiacetic acid (ODA), 2,2'-iminodiacetic acid (IDA) and 2,2'-thiodiacetic acid (TDA), has been studied using spectrophotometry in 1 M NaClO4. Both the position and the intensity of the absorption band of NpO2+at 980 nm are affected by the formation of NpO2+/dicarboxylate complexes, providing useful information on the complexation strength, the coordination mode and the structure of the complexes.
Development of Variable Temperature Scanning Microwave Microscope for High Throughput Materials Characterization
Authors: Okazaki Noriaki , Okazaki Sohei , Takahashi Ryota , Murakami Makoto , Ahmet Parhat , Kakiuchi Nobuyuki , Furusho Hitoshi , Nishino Taito , Furubayashi Yutaka , Fukumura Tomoteru , Matsumoto Yuji , Kawasaki Masashi , Chikyow Toyohiro , Koinuma Hideomi , Hasegawa Tetsuya
Published: April 2011

We developed a variable-temperature scanning microwave microscope (VT-SμM) that can perform high-throughput materials characterization in the temperature range between 4K and room temperature. As a sensor probe we used a high-Q coaxial cavity resonator, which was mounted on the low-temperature stage to allow variable-temperature measurements. We carried out systematic studies on the thermal degradation of the conducting polymers using the combinatorial libraries of polyaniline and polythiophene thin films, which showed rapid decrease of conductivity above 300C and 250C, respectively. The low-temperature performance of the VT-SμM was demonstrated by the measurement of composition-spread Nd1-xSrxMnO3 thin film, for which we succeeded in detecting the clear metal-insulator transition at 100K. We also propose a simple and easy method for the quantitative analysis of conductive thin films, by using the standard composition-spread thin films of Ti1-xNbxO2.
The Computational Materials Design Facility (CMDF): A powerful framework for multi-paradigm multi-scale simulations
Authors: Buehler Markus J. , Dodson Jef , van Duin Adri C.T. , Goddard III William A.
Published: April 2011

Predicting the properties and behavior of materials by computer simulation from a fundamental, ab initio perspective has long been a vision of computational material scientists. The key to achieving this goal is utilizing hierarchies of paradigms and scales that connect macrosystems to first principles quantum mechanics (QM). Here we describe a new software environment, the “Computational Materials Design Facility” (CMDF), capable of simulations of complex materials studies using a variety of simulation paradigms. The CMDF utilizes a Python scripting layer to integrate different computational tools to develop multi-scale simulation applications. We have integrated DFT QM methods, the first principles ReaxFF reactive force field, empirical all atom force fields (FFs), mesoscale and continuum methods. The central data structure Extended OpenBabel (XOB) plays a critical role as glue between applications. We demonstrate the usefulness of CMDF in examples that couple complex chemistry and mechanical properties during dynamical failure processes, as for example in a study of cracking of Ni under presence of O2.
High-throughput Studies on Photochemical Properties of Transition Metal-Doped SrTiO3 Epitaxial Thin Films
Authors: Ohsawa Takeo , Koinuma Hideomi , Matsumoto Yuji
Published: April 2011

Combinatorial pulsed laser deposition approach is suitable to study complex effects such as composition, thickness and surface structure on thin film-based photocatalysis in high-throughput manner. We fabricated composition spreads and thickness gradient films of transition metal-doped SrTiO3(001) on various oxide single crystal substrates and evaluated their photocatalytic activity by the use of photoreduction of Ag+ in AgNO3 solution. We found anomalous film thickness and substrate effects on the Ag-photodeposition in the V-doped SrTiO3 epitaxial thin films grown on the Nb:SrTiO3(001) substrate.
Investigation of Antimicrobial Peptide Salts: Efficacy and Solubility in Surfactant Solutions for Latex Systems
Authors: Wicks Douglas , Rhoades Alicyn M , Williamson John S , Miriyala Bruhaspathy
Published: April 2011

The study and application of antimicrobial peptides is a growing niche field in the areas of pharmaceutics and medicinal chemistry. As a result, the majority of testing and development is completed under in vitro conditions. The use of synthetically derived antimicrobial peptides in applications outside the medical realm is a relatively untapped field, with the significance of interactions between antimicrobial oligopeptides and the ingredients of polymer systems being largely unknown. Water-based polymer coatings systems are attractive targets for microbial invasion because of their inherent material properties. Water-based polymer latex coatings contain a number of components which aide in stabilization and coalescence of the polymer particles, such as surfactants and polymeric cellulose-derived molecules, with several types of molecular structures existing for each. Microbes are able to flourish within the water phase of the latexes while taking sustenance from these dispersion components, resulting in a loss of properties commonly known as ‘spoilage’. This work addresses the impact of formulation variables, specifically surfactant structure, on the solution and antimicrobial behavior of a model antimicrobial oligopeptides through the use of HT absorbance measurements.
Gas Sensor Materials Based on Semiconductor Nanocrystal / Polymer Composite Films
Authors: Leach Andrew M , Potyrailo Radislav A
Published: April 2011

High-throughput screening experimentation and multivariate spectral data analysis has been applied to evaluate the gas sensitivity of multi-size CdSe nanocrystals embedded in multiple polymer matrices. We have found that when CdSe nanocrystals of different size (2.8 and 5.6 nm diameter) were incorporated into polymer films, the photoluminescence (PL) response patterns upon laser excitation at 407-nm and exposure to polar and non-polar solvents were unexpectedly different. Additionally, these response patterns were dependent on the nature of polymer. We analyzed the spectral PL response from both sizes of CdSe nanocrystals using multivariate analysis tools. Results of this multivariate analysis demonstrate that a single film with different size CdSe nanocrystals serves as a selective sensor.
Macro- and Micro-Scale Probing of the Mechanical Properties of DNA-Crosslinked Gels Using Embedded Inclusions
Authors: Lin David C. , Yurke Bernard , Shreiber David I. , Chippada Uday , Jiang Xue , Watson George P. , Langrana Noshir A.
Published: April 2011

Mechanical properties of a class of self-assembling hydrogels based on DNA hybridization were studied using rigid, embedded inclusions. Because inclusions can be deflected without direct contact with a manipulator (e.g., magnet) once they are embedded within the subject material, the measurement technique is well suited for monitoring instantaneous and time-varying changes in the mechanical properties of active materials as they respond to external stimuli. In gels crosslinked with complementary strands of oligonucleotides, hybridization chemistry and strand displacement mechanisms allow reversible assembly, shape change, and large changes in compliance through the application of particular strands of DNA. In earlier work using large (diameter ∼0.8 mm) magnetic beads, the scaling behavior of the global elastic modulus with crosslink density was determined. More recently, it was shown that a threefold increase in stiffness was possible by generating prestress in the DNA-crosslinked gel network. Currently, the gels are functionalized to support cell attachment and embedded with micro-fabricated nickel bars. Through the measurement of local elastic and shear moduli as well as Poisson’s ratios, cell-substrate interactions can be used as a means of evaluating the potential of DNA-crosslinked gels as active cellular engineering substrates and tissue engineering scaffolds.
Effect of Nanostructure on the Thermal Oxidation of Atomized Iron
Authors: Kumar Mohit , Rawat Naveen , Santhanam Kalathur S
Published: April 2011

The effect of nanostructure on the thermal oxidation of atomized iron has been investigated. Above 500°C atomized iron is oxidized in the presence of air. However, when iron is compacted with multiwalled carbon nanotubes (MWCNT) this oxidation is shifted by more than 100°C. Iron is protected by the nanostructure environment A large number of compositions of atomic ratios of iron and MWCNT have been examined in this study to understand the effect in detail. The effect of nanostructure in the thermal oxidation of iron is interpreted as due to iron atom experiencing extensive overlap and confinement effect. causing spin transfer. Based on theoretical calculations reported in the literature this confinement effect of iron is suggested to produce a transformation from 3d64s2 to an effective configuration of 3d84s0 producing spintronics effect.
Relation Between Structure and Diffusion in Nanostructured Porous Solids and in Lipid Membranes
Authors: Vasenkov Sergey , Kärger Jörg
Published: April 2011

Pulsed field gradient (PFG) NMR technique has been applied to study molecular transport in two different types of nanostructured materials, viz. in fluid catalytic cracking (FCC) catalysts and in lipid membranes. Diffusion studies have been performed for a broad range of molecular displacements covering displacements that are as small as a fraction of a micron. The effective diffusivities recorded on various length scales are used to evaluate the relevance of various transport modes in the particles of FCC catalysts for the rate of molecular exchange between catalyst particles and the surrounding atmosphere. This rate is shown to be primarily related to the diffusion in the meso- and macropores of the particles under the condition of fast molecular exchange between these pores and the zeolite crystals located in the particles. Studies of lipid membranes are focused on developing fundamental understanding of the influence of various types of domains on lateral mobility of lipids. A meaningful study of this influence requires an ability of monitoring lipid diffusion for different displacements that are smaller and larger than the domain size. First PFG NMR data along this direction are presented.
The Role Played by Strain Fields, Dislocation Arrays, and Domain Boundaries During the Catalytic Synthesis of Carbon Nanotubes
Authors: Dell'Acqua-Bellavitis Ludovico Matteo , Ballard Jake D , Vajtai Robert , Ajayan Pulickel M , Siegel Richard W
Published: April 2011

Ex-situ transmission electron microscopy (TEM) was performed on catalytically-grown multi-wall carbon nanotubes (MWCNTs), leading to the identification of two types of catalyst-nanotube wall interfaces – respectively characterized by a quasi-spherical, low aspect ratio particle closer to the nanotube root and by a tapered, high aspect ratio particle farther away from it. The nanotubes exhibit two distinct types of boundaries between crystalline domains with different orientations – twist and twin boundaries in correspondence with quasi-spherical particles and tilt boundaries in correspondence with the tapered particles. TEM evidence suggests that the domain boundaries maintain a rather steady position coupled to the catalytic particles, while the carbon atoms diffuse along the nanotube axis away from the particles. From these considerations, it is possible to conclude that the relative movement of the carbon atoms with respect to the dislocation lines comprising the nanotube domain boundary located at the catalyst-wall interface is a significant mechanism for nanotube crystal growth mainly driven by surface diffusion. The results are interpreted in light of the concurrence of base- and tip- growth for the catalytic synthesis of nanotubes dominated by surface diffusion.
Growth of Silica Nanowires Catalysed by Pd Ion Implantation into Si(100)
Authors: Sekhar Parveen Kumar , Sood Dinesh Kumar , Bhansali Shekhar
Published: April 2011

Selective synthesis of silica nanowires on silicon wafers catalyzed by Pd ion implantation is reported.Nanoclusters of palladium silicide acts as seeds for nucleation of wires following a Vapor-Liquid-Solid (VLS) growth model. The consumption of silicide towards nanowire growth is confirmed through Rutherford Backscattering Spectrometry (RBS).The influence of growth time, implantation dose and heating temperature on the structure and morphology of the wires is investigated. Optimization of the these tunable parameters would be needed to facilitate controlled and directed bottom-up growth of silica nanowires.Such selective synthesis may enable a large number of applications in wide areas of future technologies such as localization of light, low dimensional waveguides for functional microphotonics, scanning near field optical microscopy (SNOM), optical interconnects, sacrificial templates, optical transmission antennae and biosensors.
Sprayed Carbon Nanotube Thin Films as Hydrogen Sensors
Authors: Sayago Isabel , Terrado Eva , Aleixandre Manuel , Horrillo Maria del Carmen , Lozano Jesus , Fernandez Maria Jesus , Lafuente Esperanza , Maser Wolfgang K , Gutierrez Javier , Martinez Maria Teresa , Benito Ana M , Munoz Edgar
Published: April 2011

We report a novel, simple, and inexpensive method for preparing efficient carbon nanotube-based hydrogen sensors. Sensor devices were fabricated by simply spraying single-walled carbon nanotube (SWNT) dispersions on alumina substrates. Pd-functionalization of the employed SWNTs enabled increasing the device sensitivity to hydrogen. The effect of aging, thermal processing, and the employed carrier gases on the sensor performance is here described. The fabricated thin film sensors exhibited good sensitivity to hydrogen at room temperature in reversible and reproducible detection processes.
Atomic and Electronic Structures of Pt Supported on Graphene
Authors: Okazaki-Maeda Kazuyuki , Morikawa Yoshitada , Tanaka Shingo , Kohyama Masanori
Published: April 2011

We examined atomic and electronic structures of Pt supported on graphene, using the first-principles calculations based on the density functional theory (DFT). First, we examined the interaction between graphene and a Pt(111) monolayer. The stable distance between graphene and the Pt-monolayer is 3.48Å and the adhesive energy is 0.09 eV/atom. The density of states (DOS) for the Pt(111)/graphene system is the same with the sum of respective DOS's of the graphene sheet and the Pt monolayer. These results indicate that the interaction between graphene and a Pt(111) monolayer is very weak. Second, we examined the interaction between graphene and a Pt atom. The Pt-C bond length is 2.31Å and the adsorption energy is 2.82 eV/adatom, which means the stronger interaction. Finally, we examined the interaction between graphene and a Pt cluster consisting of ten atoms. The distance between graphene and the bottom layer of the cluster is about 2.7Å, which is shorter than that between graphene and the Pt(111) monolayer. This shows that the interaction between the Pt10 cluster and graphene is stronger than the Pt-monolayer/graphene interaction. The center atom in the hexagonal bottom layer of the Pt cluster has the nearest distance with graphene of about 2.5Å. If there is a defect on graphene, the center atom of the hexagonal bottom layer strongly interacts with that.
Nanoparticle SnO2 films as gas sensitive membranes
Authors: Schumacher B. , Szabó Dorothee Vinga , Schlabach Sabine , Ochs Rolf , Müeller Harald , Bruns Michael
Published: April 2011

The Karlsruhe Microwave Plasma Process (KMPP), a versatile gas-phase process is applied to produce SnO2 and core shell SnO2/SiO2 nanoparticles which are, respectively, deposited in-situ on preheated Si-Substrates. These substrates are already equipped with an electrode microarray. The proof of sensor concept shows, that mechanically stable, nanoscaled and nanogranular gas sensing layers can be produced.

In a first step synthesis and deposition parameters of SnO2 are elaborated, and gas-sensitivity tests are performed. Additionally, annealing experiments are done. The morphology and struc-ture of nanoparticles is characterized by X-ray diffraction and TEM-methods. The layers are in-vestigated by SEM techniques and by XPS. The sensitivity of the nanogranular layer is deter-mined in comparison with a standard microarray equipped with sputtered layers. Particles crys-tallize in the tetragonal cassiterite structure. It is found that a precursor concentration of 3×10−6mol/l leads to particles with crystallite size in the region of 2nm, whereas a concentration of 5.5×10−4mol/l results in approximately 5nm particles. With the precursor concentration, columnar porous layers of 200nm thickness are obtained after a deposition time of 1min. This thickness is comparable to the one of sputtered layers. First sensor tests show 10 times higher sensitivity to isopropanol, compared to the standard array. The time of response is equivalent. The grain growth observed for bare and core/shell nanoparticles at 300°C is marginal.
Position Controlled Growth in Carbon Nanotubes Catalyzed by an Iron Nano-dot Array
Authors: Fujita Jun-ichi , Mukawa Takahito , Okada Satoshi , Kobayashi Ryota , Ishida Masahiko , Ichihashi Toshinari , Ochiai Yukinori , Matsui Shinji
Published: April 2011

We report a successful demonstration of a position control technique for carbon nanotube growth catalyzed by an iron nano-dot array, which was fabricated by using electron beam induced chemical vapor deposition (EB-CVD). Point irradiation of an electron beam with ferrocene source gas produced an amorphous carbon dot containing iron atoms that were uniformly dispersed into each dot, and its position could be precisely controlled. Vacuum annealing of the ferrocene based dots induced segregation of iron nano-particles, whose size was almost proportional to the beam irradiation time. After removing the carbon residue, an ethanol CVD process carried out at 800°C under 40 mmHg of ethanol vapor induced carbon nanotube growth from the dots. Many grown nanotubes were very thin, being 0.7 to 1.8 nm in diameter. These diameters were much less than that of the bottom iron particles.
Reactions of Methyl Iodide and Halopropanes with Na0 Treated and Untreated NaX and NaY Zeolites
Authors: Kanyi Charles W. , Yan Ka King , Kowenje Chrispin O , Kanyi Charles Wairagu
Published: April 2011

Products formed from reactions of methyl iodide, 1-chloropropane, 1-iodopropane and 1-bromopropane with Na0 treated and untreated NaX and NaY zeolites were studied using solid state 13C NMR and IR spectroscopy. At room temperature, methyl iodide dissociates to form framework methoxy in untreated NaX with no reaction observed in untreated NaY. Upon Na0 treatment, both NaX and NaY reacts with methyl iodide to form framework methoxy, methane and ethane. Longer carbon chain 1-iodo, bromo and chloropropane were also studied. 1-iodopropane undergoes dehalogenation to form framework propoxy while 1-chloropropane and 1-bromopropane undergoes dehalogenation/ dehydrohalogenation to form framework propoxy and propene.
N2 Detection by the Carbon nanotubes Mat and Bundle
Authors: Huang Chien-Sheng , Huang Bohr-Ran , Jang Yung-Huang , Tsai Meng-Shian , Ya Jiun-You , Jian Jia-An
Published: April 2011

Carbon nanotubes (CNTs) were synthesized by thermal chemical vapor deposition (thermal CVD) on n-type Si (100) at 700 ° under C2H2 gas flow ratio of 30 sccm. Fe catalysts were pre-deposited by RF sputtering system with RF power 150 W. Two kinds of as-grown CNTs were used to detect N2: the vertically oriented carbon nanotubes (CNTs) mat and horizontally oriented CNTs bundle. Two-terminal electrical measurements were performed at room temperature of 25 °. The electrical resistance of CNTs mat or bundle was found to increase when exposed to N2 environment, and to return back after the N2 pumping, respectively. However, the CNTs bundle had better sensitivity and possessed faster response and recovery time. This could be ascribed to that the CNTs bundle, with more effective grooves on the surface, provided more lower binding-force sites to absorb N2 molecules than the CNTs mat dose, which prominently had interstitial sites.
Epitaxial Growth of Strontium Bismuth Tantalate/Niobate on Buffered Magnesium Oxide Substrates
Authors: Thomas George H. , Morrell Jonathan S. , Aytug Tolga , Xue Ziling B. , Beach David B.
Published: April 2011

Epitaxial films of strontium bismuth tantalate (SrBi2Ta2O9, SBT) and strontium bismuth niobate (SrBi2Nb2O9, SBN) were grown using solution deposition techniques on magnesium oxide (MgO) substrates buffered with a 100 nm layer of lanthanum manganate (LaMnO3, LMO). Film structure and texture analyses were carried out using x-ray diffraction. Theta-2theta diffraction patterns were consistent with a c-axis aligned structure for both the buffer layer and the solution deposited films. Theta-2 theta scans revealed (001)SBT, SBN //(001) LMO epitaxial relationships between the solution deposited films and the buffer layer. A pole figure about the SBT, SBN (115) reflection indicated a single in-plane epitaxy. Film quality was assessed using ω and φ scans. Nuclear Magnetic Resonance (13C) was used to characterized the methoxy-ethoxide solutions used for the deposition of the SBN and SBT films.
Surface Photovoltage Spectroscopy for the Investigation of Perovskite Oxide Interfaces
Authors: Beyreuther Elke , Grafström Stefan , Thiele Christian , Dörr Kathrin , Eng Lukas M.
Published: April 2011

In the present study, we comparatively investigate the distribution of electronic interface states of three different perovskite oxide interfaces, formed by epitaxial thin films of La0.7Sr0.3MnO3 (LSMO), La0.7Ca0.3MnO3 (LCMO), and La0.7Ce0.3MnO3 (LCeMO) on SrTiO3(100) substrates, in the as-prepared state as well as after an annealing procedure. We find that annealing significantly reduces the number and density of interface trap states. Two different experimental realizations of the surface photovoltage spectroscopy (SPS) technique were employed: an approach based on X-ray photoelectron spectroscopy (XPS), as well as a capacitive method. The advantages and limitations of both methods are critically discussed.
Laser-Patterned Blue-Green SiC LED
Authors: Bet Sachin Madhukar , Quick Nathaniel R , Kar Aravinda
Published: April 2011

Laser direct writing and doping has already been successfully demonstrated for fabrication of PIN diodes, Ohmic and Schottky contacts and other optical structures in silicon carbide (SiC). Although SiC is an indirect bandgap semiconductor a SiC green light emitting diode (LED) has been recently shown to perform better than a GaN green LED. This observation is primarily due to 1) a simple device structure in SiC as opposed to the multilayered structure in GaN and other high bandgap semiconductor compounds and 2) high thermal conductivity. This initial phase focuses on the fabrication of reference SiC LED's to baseline this novel laser direct writing and doping process.

6H:SiC (n-type) wafer samples were used for fabrication of LED's. A Nd:YAG laser (1064nm wavelength) was used in continuous wave mode as well as pulsed mode for doping. Doping process iterations were carried out to obtain a uniform doped layer. Two different techniques were employed for patterning: 1) top doping where the incident laser beam assists in doping on the top surface and 2) bottom doping where the bottom surface is doped using the same top incident laser beam. Different structures were synthesized using these two doping techniques. P-type dopants such as boron (in powder form) and aluminum (metalorganic compound tri-methyl aluminum) and n-type dopant (pure nitrogen gas) were used. The doped structures were characterized for I-V characteristics, C-V characteristics and electroluminescence.

Electroluminescence (EL) spectrum of the doped samples showed the output in the range of blue to blue green for different samples and the different doped structures. The feasibility of wavelength tuning using nanostructure patterning has also been explored.
Pr-O-N Dielectrics for MIS Stacks on Silicon and Silicon Carbide Surfaces
Authors: Henkel Karsten , Torche Mohamed , Sohal Rakesh , Schwiertz Carola , Hoffmann Patrick , Schmeißer Dieter
Published: April 2011

We combine high-k dielectrics with wide band gap semiconductors for new possibilities for high frequency and high power applications. We investigate the dielectric properties of Praseodymium based oxides and silicates by preparing MIS structures consisting of metal layer (M), PrOx (praseodymium oxide) as a high-k insulating layer (I), and silicon (Si) or silicon carbide (SiC) as semiconductor substrates (S). Our approach consists both, electrical measurements and spectroscopic characterization to analyze properties of the various interfaces within the stacks.

For the electrical measurements we produce PrOx layers in the thickness range of 10nm to 240nm. We use capacitance-voltage analysis and determine permittivity values of 8 to 20 depending on physical thickness resulting in an equivalent oxide thickness (EOT) down to 5nm. These data are consistent with the formation of a Pr-silicate between Si and PrOx.

In order to prevent interface reactions and to improve the band alignment an interfacial layer is introduced into the stack between the semiconductor and the high-k material. We find aluminum oxynitride (AlON) as a suitable layer which reduces the interface state density to a mean value of 5E11cm2/Vs and the leakage current (1V above flat band) below 1E-5A/cm2.
Control of Trenching and Surface Roughness in Deep Reactive Ion Etched 4H and 6H SiC
Authors: Beheim Glenn M. , Evans Laura J.
Published: April 2011

An optimized deep reactive ion etching (DRIE) process for the fabrication of SiC microstructures has been developed. The optimized process enables the etching of 4H and 6H SiC to depths > 100 microns with the required characteristics of (1) high rate (>0.5 microns/min), (2) vertical sidewalls, (3) minimal microtrenching at the sidewall base, and (4) smooth etched surfaces. The optimized process was determined based on the results of an experiment (full factorial design) which determined how the etch characteristics are affected by four important process parameters: temperature of the wafer chuck, pressure within the chamber, and concentrations of O2 and Ar in a gas flow comprised of O2, Ar and SF6. This study is believed to be the first systematic investigation of the effect of temperature on SiC DRIE characteristics; substrate heating was found to be a key in producing the desired etch properties.
1.8 kV, 10 mOhm-cm2 4H-SiC JFETs
Authors: Scofield James D. , Ryu Sei-Hyung , Krishnaswami Sumi , Fatima Husna , Agarwal Anant
Published: April 2011

Fabrication and characteristics of high voltage, normally-on JFETs in 4H-SiC are presented. The devices were built on 5x1015 cm-3 doped, 12 μm thick n-type epilayer grown on a n+ 4H-SiC substrate. A specific on-resistance of 10 m Ω-cm2 and a blocking voltage of 1.8 kV were measured. Device characteristics were measured for temperatures up to 300oC. An increase of specific on-resistance by a factor of 5 and a decrease in transconductance were observed at 300oC, when compared to the value at room temperature. This is due to a decrease in bulk electron mobility at elevated temperature. A slight negative shift in pinch-off voltage was also observed at 300oC. The devices demonstrated robust DC characteristics for temperatures up to 300oC, and stable high temperature inverter operation in a power DC-DC converter application, using these devices, is reported in this paper.
Vertical MOSFET Devices Fabricated on 3C-SiC with High and Low Material Quality
Authors: Schoner Adolf , Bakowski Mietek , Ericsson Per , Stromberg Helena , Nagasawa Hiroyuki , Abe Masayuki
Published: April 2011

Vertical DMOSFET devices with sizes from single cell to 3x3 mm2 large devices have been fabricated on cubic 3C-SiC material. The used 3C-SiC substrates had varying material quality. The best quality had a more than 2 orders of magnitude lower density of extended crystal defects than the worst material. The processed and investigated vertical DMOSFET devices were designed for 600 V blocking voltage and had hexagonal unit cells with 2 μm channel length and aluminum implanted termination rings. The p-body was aluminum implanted and the source was phosphorus implanted. As deposited Ti/W contacts were evaluated as source and drain metallization. Single cell vertical DMOSFET devices, processed on the low defect density material quality, gave voltage blocking capabilities of more than 600 V with leakage currents of 0.1 to 10 μA. The same devices could handle currents around 5 mA in on-state at 15 V gate bias. MOSFET devices with 50 to 100 unit cells had blocking voltages of 400 to 500 V with on-state currents of 0.2 to 0.4 A at 15 V gate bias, indicating the potential of 3C-SiC for the fabrication of next generation power MOSFET devices.
Synthesis and Measurement of Magnetic Cobalt DNA-Templated Nanowire
Authors: Lin Chia-Hsin , Tong Shi-Yuan , Lin Shin-Wei , Chen Hsin-Lung , Liu Yi-Chun , Lin Hsien-Kuang , Liu Wen-Lian , Cheng Syh-Yuh , Wang Yi-Hui
Published: April 2011

Biomaterials such as DNA are currently being explored as potential application in nanotechnology. DNA templates were immobilized on crystal-violet-treated mica by spin coating as a grid-like network. The DNA templates were then activated with PdCl2, followed by reduction with dimethylamine borane (DMAB) to form seeding nanoclusters on the DNA chain. Afterward the DNA chain with deposition of zero-valence Pd nanoclusters was grew in a Co electroless plating bath. SEM/EDS analysis revealed that Co nanoparticles could be assembled on the DNA template to form magnetic nanowires with a diameter of 25nm to 250nm by a conventional electroless plating. Vibrating Sample Magnetometer analysis indicated that Co-DNA nanowires showed a paramagnetic characteristic. Grid-like networks of DNA template were effectively preserved after Co electroless plating. These characteristics indicated that DNA is an ideal template for the production of magnetic nanowires, which could be useful in the development of high-density memory storage or magnetic field sensors.
Biodegradable Nano-Material Composites for Use in an Inkjet Printing System
Authors: Levi Nicole H , McGuirt John B. , Coldren Faith M. , Carroll David L.
Published: April 2011

Biomaterials for development of resorbable, three-dimensional tissue scaffolds have been used in a modified thermal inkjet printing system to explore compatibility of materials, solvents and the printing system. The polymers included collagen (type I), sodium alginate, fibronectin, poly-lactic co-glycolic acid (PLGA), polyethylene glycol (PEG), and tetraglycol were tested. Single-walled carbon nanotubes were combined with the biopolymers to determine which systems in which they would blend well, and be able to print. Uncovering which biopolymers may be printed together offers insight into development of materials which most closely match the properties of biological tissue.
Evidence for a Structural Transition to a Superprotonic CsH2PO4 Phase Under High Pressure
Authors: Botez Cristian E. , Chianelli Russell R. , Zhang Jianzhong , Qian Jiang , Zhao Yusheng , Majzlan Juraj , Pantea Cristian
Published: April 2011

We have used synchrotron X-ray powder diffraction (SXRPD) to investigate the structural behavior of cesium dihydrogen phosphate upon heating. Temperature-resolved data collected at ambient-pressure demonstrate that a transition from the room-temperature monoclinic phase (P21/m; a=7.90Å, b=6.39Å, c=4.87Å, and β=107.64°) to a high-temperature cubic phase (Pm3m; a=4.96Å) occurs at T=237°C. The high-temperature phase is not stable under ambient-pressure conditions, even in the absence of further heating. On the other hand, SXRPD measurements carried out under high-pressure (∼1GPa) evidence a transition from monoclinic to a stable cubic phase (Pm3m, a=4.88Å) at a temperature within the 255°C-275°C range. A 1000-fold increase in the proton conductivity (indicating the transition to the superprotonic phase) was previously observed under the same non-ambient conditions. Therefore, our results represent strong evidence that the superprotonic behavior in cesium dihydrogen phosphate is associated with a monoclinic-to-cubic polymorphic structural transition and not with chemical modifications.
Surface Characterization of Silicon Carbide Following Shallow Implantation of Platinum Ions for High Temperature Hydrogen Sensing Applications
Authors: Muntele Claudiu , Budak Satilmis , Muntele Iulia , Ila Daryush
Published: April 2011

Silicon carbide is a promising wide-bandgap semiconductor intended for use in fabrication of high temperature, high power, and fast switching microelectronics components running without cooling. For hydrogen sensing applications, silicon carbide is generally used in conjunction with either palladium or platinum, both of them being good catalysts for hydrogen. Here we are reporting on the temperature-dependent depth profile modifications of tungsten electrical contacts deposited on silicon carbide substrates.
Differentiation of Bone Marrow Stem Cells on Inkjet Printed Silk Lines
Authors: Limem Skander , Calvert Paul , Kim Hyeon Joo , Kaplan David L.
Published: April 2011

Water based silk solutions were successfully inkjet printed for the first time into patterns of parallel lines onto vinyl plastic substrates. Human bone marrow stromal cells (hMSCs) were seeded on the silk printed patterns and cultured in the presence of 100 ng/ml of bone morphogenic protein (BMP-2). After one week of culture cell growth and attachment showed site specificity on the silk printed lines. Both alkaline phosphatase activity and cell morphology indicated hBMSCs differentiation into osteogenic cells along the silk printed lines. After 4 week of culture, the cellular bridging of adjacent silk printed lines took place for all interline distances lower than 1.25 mm. Therefore, commercial inkjet printing technology can produce complex viable cellular patterns with 111 ± 24 μm lateral resolution, through the deposition of bioactive materials. The results provide a first step toward cell specific control using 3D inkjet printing techniques using biocompatible gel systems to regulate cell functions.