bluuebunny/crossref_metadata_2025 huggingface dataset:
Playing Soldiers at the Edge of Imagination. Hotel Modern and the Representation of the Unrepresentable
Authors: Bleeker Maaike
Published: April 2011

With their performances The Great War (life in the trenches during the First World War), and Kamp (Auschwitz), as well as their short video History of the World Part Eleven, the Dutch theatre company Hotel Modern raises important questions concerning the core of the claims that some events cannot be adequately represented, or should not be represented at all. Hotel Modern uses theatre as a critical vision machine, in order to undermine seemingly self-evident modes of looking; they confront us, their audience, with the way we are implicated in what we believe we see. Hence they suggest that resistance to representation might in fact be a manifestation of what Alain Badiou has called the ‘passion for the real’.
On the Charge of Memory. Auschwitz, Trauma and Representation
Authors: Turim Maureen
Published: April 2011

What does a field of dogs, arranged like seagulls watching the ocean, suggest about the representation of trauma and Auschwitz? The question, posed in homage to Andrzej Munk's film Pasazerka (The Passenger, 1963), has a long answer. The answer developed here has philosophical and theoretical implications that take us deep into the structure of trauma as understood in the aesthetics of films of consequence. Munk's film provides a particularly forceful example of what representation might mean, as it links Jewish trauma to that of political resistance, yet tells this tale with consummate and poignant irony through the eyes of a Nazi who reexamines her subjective memory, and the testimony she made in bad faith. This makes the movie into a particularly complex example of Holocaust fiction; as one of the most hauntingly composed films of the twentieth century, it underscores a maxim of progressive modernist art: form embodies meaning.
Mourning as Method. William Kentridge's Black Box/Chambre Noir
Authors: Ståhl Kristina Hagström
Published: April 2011

William Kentridge's 2005 work Black Box/Chambre Noire was created as an “afterthought” to his production of Mozart's The Magic Flute. In Black Box/Chambre Noire, Kentridge examines the dark side of the Enlightenment ideals that informed The Magic Flute, as well as early twentieth-century European colonial endeavours. Tracing the history of Germany's genocide of the Herero population in Namibia, Black Box/Chambre Noire posits processes of historiographic erasure as constitutive of Europe's relationship to its own colonial legacy in Southern Africa. Kentridge's strategies for representing trauma, loss, and memory suggest that his incorporation of Trauerarbeit into the artwork shapes not only its content but also its form, technique, and method.
The severity of pseudohyperkalaemia is not dependent upon the stage of chronic kidney disease: a prospective study
Authors: Imran Muhammad , Davison Andrew S. , Howse Matthew , Williams Peter , Kemp Graham J. , Roberts Norman B.
Published: April 2011

Background: Pseudohyperkalaemia may result from delay in centrifugation and storage at 4°C. We investigated whether the stage of chronic kidney disease (CKD), its aetiology or medications influence this.

Methods: Seventy-seven patients with CKD were recruited. Lithium heparin plasma samples were analysed for sodium, potassium, urea and creatinine, chloride, bicarbonate, magnesium, calcium and inorganic phosphate at 0 h and after storage of whole blood at 4°C for 6 h and 20 h. K-EDTA and fluoride-EDTA samples were analysed for full blood count and glucose at 0 h. CKD stage was determined by standard criteria.

Results: K+ increased on average by 1.0 and 3.6 mmol/L after 6 and 20 h storage of whole blood at 4°C, independent of cause or stage of CKD. K+ increase at 6 h was correlated with haemoglobin but not with white blood cell count, platelet count or glucose. Patients taking ACE inhibitors and/or angiotensin receptor blockers (ARBs) had slightly higher K+ at 0 h and increased K+ after storage for 6 h. Na+ decreased on average by 3.8 mmol/L at 20 h and was independent of CKD stage, and correlated with K+ increase.

Conclusions: K+ increased significantly with time in samples stored at 4°C in all stages of CKD. This was greater in some patients on ACE inhibitors and ARBs, and increased with haemoglobin, but was not related to the stage of CKD, white blood cell count or platelet count for the samples used in this study.
Mode I critical stress intensity factor of wood and medium-density fiberboard measured by compact tension test
Authors: Yoshihara Hiroshi , Usuki Ami
Published: April 2011

The critical stress intensity factor of mode I (K
Ic) obtained by compact tension (CT) tests of wood and medium-density fiberboard (MDF) was experimentally and numerically analyzed. A double cantilever beam (DCB) test was also conducted and the results were compared with those of the CT tests. Similar to the results of single-edge-notched bending (SENB) and single-edge-notched tension (SENT) tests previously conducted, the value of K
Ic was obtained properly from the CT test when an additional crack length was taken into account.
The Hog1 Mitogen-Activated Protein Kinase Mediates a Hypoxic Response inSaccharomyces cerevisiae
Authors: Hickman Mark J , Spatt Dan , Winston Fred
Published: April 2011

We have studied hypoxic induction of transcription by studying the seripauperin (PAU) genes of Saccharomyces cerevisiae. Previous studies showed that PAU induction requires the depletion of heme and is dependent upon the transcription factor Upc2. We have now identified additional factors required for PAU induction during hypoxia, including Hog1, a mitogen-activated protein kinase (MAPK) whose signaling pathway originates at the membrane. Our results have led to a model in which heme and ergosterol depletion alters membrane fluidity, thereby activating Hog1 for hypoxic induction. Hypoxic activation of Hog1 is distinct from its previously characterized response to osmotic stress, as the two conditions cause different transcriptional consequences. Furthermore, Hog1-dependent hypoxic activation is independent of the S. cerevisiae general stress response. In addition to Hog1, specific components of the SAGA coactivator complex, including Spt20 and Sgf73, are also required for PAU induction. Interestingly, the mammalian ortholog of Spt20, p38IP, has been previously shown to interact with the mammalian ortholog of Hog1, p38. Taken together, our results have uncovered a previously unknown hypoxic-response pathway that may be conserved throughout eukaryotes.
Wheat Hybridization and Polyploidization Results in Deregulation of Small RNAs
Authors: Kenan-Eichler Michal , Leshkowitz Dena , Tal Lior , Noor Elad , Melamed-Bessudo Cathy , Feldman Moshe , Levy Avraham A
Published: April 2011

Speciation via interspecific or intergeneric hybridization and polyploidization triggers genomic responses involving genetic and epigenetic alterations. Such modifications may be induced by small RNAs, which affect key cellular processes, including gene expression, chromatin structure, cytosine methylation and transposable element (TE) activity. To date, the role of small RNAs in the context of wide hybridization and polyploidization has received little attention. In this work, we performed high-throughput sequencing of small RNAs of parental, intergeneric hybrid, and allopolyploid plants that mimic the genomic changes occurring during bread wheat speciation. We found that the percentage of small RNAs corresponding to miRNAs increased with ploidy level, while the percentage of siRNAs corresponding to TEs decreased. The abundance of most miRNA species was similar to midparent values in the hybrid, with some deviations, as seen in overrepresentation of miR168, in the allopolyploid. In contrast, the number of siRNAs corresponding to TEs strongly decreased upon allopolyploidization, but not upon hybridization. The reduction in corresponding siRNAs, together with decreased CpG methylation, as shown here for the Veju element, represent hallmarks of TE activation. TE-siRNA downregulation in the allopolyploid may contribute to genome destabilization at the initial stages of speciation. This phenomenon is reminiscent of hybrid dysgenesis in Drosophila.
Effects of prolactin receptor genotype on the litter size of Mangalica
Authors: Tempfli Károly , Farkas Gergely , Simon Zsolt , Bali Papp Ágnes
Published: April 2011

The aim of this study was to detect different alleles of the prolactin receptor (PRLR) gene and to examine their effects on the litter size of the indigenous Hungarian pig, the Mangalica. G1789A single nucleotide polymorphism (SNP) was investigated as a candidate for litter size. Samples from 80 purebred Mangalica sows and data of their 335 litters were provided by Olmos & Tóth Ltd. Hair follicles were used to isolate the required DNA. Allelic discrimination was performed by means of the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method using the AluI restriction enzyme and agarose gel electrophoresis. In the population examined, the A allele was found to be preferable in the Mangalica breed group. The most advantageous AA genotype was the least prevalent (8.75%), while the frequencies of AB and BB were 40% and 51.25%, respectively. Remarkably, the average number of piglets born alive per litter was 1.11 ± 0.39 higher in sows with AA as compared to those with BB genotype. By raising the frequency of the AA genotype, the litter size is likely to increase. However, the effect of PRLR genotypes can differ among pig breeds and even lines. Further studies may be required to observe and estimate possible pleiotropic effects of this polymorphism on other traits.
Determination of Elastic Modulus of Piezoelectric Aluminum Nitride Coating
Authors: Perooly Soma S , Garg Varun , Rahman Md. H. , Rosenberger L. W. , Shreve Gina S. , Gibson Ronald F. , Auner G. W.
Published: April 2011

Aluminum Nitride (AlN) is a technologically important wide band gap semiconductor and a potential piezo-electric material for Biosensor application [1]. It is a clear candidate for the integration of surface acoustic wave (SAW) devices on chips with silicon-based electronics [2]. AlN may also prove to be useful for the integration of mechanical devices and also in the field of packaging of Bio-MEMS devices because of its superior thermal conductivity 130-140 (W/mK, room temp-100 deg C) and nontoxicity. In the current work an attempt has been made to determine the elastic modulus of AlN coated on Si-microcantilevers, employing the concept of symmetrically laminated beam theory for the first time at the micro level thus avoiding the coupling effects. So far the earlier studies have been done only using simple beam theory. Modal vibration frequencies for microcantilevers without and with the AlN coating were used, along with analytical models and knowledge of the Si modulus, to “back out” the modulus of AlN [3].
Magnetostrictive Vibration Sensor based on Iron-Gallium Alloy
Authors: Datta Supratik , Flatau Alison B.
Published: April 2011

This work characterizes magnetostrictive single crystal Fe84Ga16 (Galfenol) as static and dynamic sensor in bending mode. Galfenol patch bonded to a cantilevered aluminum beam was characterized for static and dynamic loading of the beam. A figure of merit has been defined and sensor parameters have been obtained for different stress conditions and Galfenol patch thickness. Issues related to application in static and dynamic sensing have been discussed.
Energy-based constitutive Model for Magnetostrictive Materials and its Application to Iron-Gallium Alloys
Authors: Atulasimha Jayasimha , Flatau Alison B.
Published: April 2011

An energy-based constitutive model that can simulate the performance of magnetostrictive actuators and sensors along any of the crystallographic orientations was developed. This model was validated by comparing its predictions with experimental actuator characteristics (λ-H and B-H curves) along the <100> and <110> directions as well as sensor characteristics (B-σ curves) along the <100> direction of single crystal FeGa samples with ∼18-19 at. % Ga. These experimental characteristics were obtained using 6.35 mm (1/4 inch) diameter and 25.4 mm (1 inch) long, oriented single crystal rods grown using the Bridgman method by the DOE Ames Lab.
Nonlinear Optical Dynamics During Phase Transition in Vanadium Dioxide
Authors: Lysenko Sergiy , Zhang Guangjun , Vikhnin Valentin , Rua Armando , Fernandez Felix , Liu Huimin
Published: April 2011

Insulator-to-metal phase transition (PT) and relaxation dynamics in VO2 were studied with ultrafast transient reflection spectroscopy and degenerate four wave mixing technique. Optical pumping of free carriers in VO2 initiates PT on a femtosecond time scale. The relaxation dynamics is strongly dependent on pump energy. Spectral reflectivity behaviour at PT due to thermal heating and upon laser excitation of VO2 demonstrates close proximity in the relative change. PT induced by light was interpreted by exciton-controlled mechanism. Excited state dynamics of metallic VO2 is assigned to formations of electronic and hole polaronic states.
Bending of Iron-Gallium (Galfenol) Alloys for Sensor Applications
Authors: Downey Patrick R. , Flatau Alison B.
Published: April 2011

This project investigates the magnetomechanical sensing behavior of iron-gallium alloys in response to applied bending loads to identify the relevant design criteria for novel magnetostrictive sensor applications. A series of experiments are conducted on the magnetic induction response of cantilevered beams to dynamic bending loads. Analytic models of the system are formulated from both the constitutive magnetostriction equations and a free energy derivation. Both the experimental and analytical results show a change of as much as 0.3 T of induction can be measured in the samples in response to relatively small applied forces, with the output magnetic signal appearing at twice the frequency of beam vibration.
The Load Capability of Piezoelectric Single Crystal Actuators
Authors: Xu Tian-Bing , Su Ji , Jiang Xiaoning , Rehrig Paul W. , Hackenberger Wesley S.
Published: April 2011

Piezoelectric lead magnesium niobate-lead titanate (PMN-PT) single crystal is one of the most promising materials for electromechanical device applications due to its high electrical field induced strain and high electromechanical coupling factor. PMN-PT single crystal-based multilayer stack actuators and multilayer stack-based flextensional actuators have exhibited high stroke and high displacement-voltage ratios. The actuation capabilities of these two actuators were evaluated using a newly developed method based upon a laser vibrometer system under various loading conditions. The measured displacements as a function of mechanical loads at different driving voltages indicate that the displacement response of the actuators is approximately constant under broad ranges of mechanical load. The load capabilities of these PMN-PT single crystal-based actuators and the advantages of the capability for applications will be discussed.
An Investigation of Energy Harvesting Using Electrostrictive Polymers
Authors: Ren Kailiang , Liu Yiming , Hofmann Heath F , Zhang Qiming
Published: April 2011

Owing to their low acoustic impedance, high elastic energy density, and relatively high electromechanical conversion efficiency, the electroactive polymers have begun to show the potential for energy harvesting or mechanical to electrical energy conversion. In addition, due to the electromechanical coupling in these materials the electric and mechanical properties of these polymers will depend on the imposed electrical and mechanical conditions. This paper discusses how to utilizing this unique property to maximum the energy conversion efficiency and the harvested electrical energy density in the electrostrictive polymers. As an example, we demonstrate that when a properly phased and externally applied electric AC field is superimposed on the mechanical cycle, an output electrical energy density of 39mJ/cm3 and mechanical-to-electrical conversion efficiency of about 10% can be obtained from the electrostrictive P(VDF-TrFE) based polymers.
Relativistic Effects on the Equation-of-State of the Light Actinides
Authors: Landa Alexander , Söderlind Per
Published: April 2011

The effect of the relativistic spin-orbit (SO)interaction on the bonding in the early actinides has been investigated by means of electronic-structure calculations. Specifically, the equation of state (EOS) for the face-centered cubic (fcc) model systems of these metals has been calculated from the first-principles density-functional (DFT) theory. Traditionally, the SO interaction in electronic-structure methods is implemented as a perturbation to the Hamiltonian that is solved for basis functions that explicitly do not depend on SO coupling. Here this approximation is shown to compare well with the fully relativistic Dirac treatment. It is further shown that SO coupling has a gradually increasing effect on the EOS as one proceeds through the actinides and the effect is diminished as density increases.
Crystal Structure of Uranyl Carboxylates
Authors: Giesting Paul , Burns Peter , Porter Nathan
Published: April 2011

Uranyl-organic complexation in geologic fluids can have a profound impact upon uranium solubility and transport. Studies of uranyl organometallic crystal structures provide a basis for understanding complexation of the uranyl ion in solution.

The crystal structures of several novel uranyl oxalates, synthesized under mild hydrothermal conditions, have been determined. These structures demonstrate new features little seen or not previously known in this chemical system, in particular polymerization into infinite sheets and direct linkage of uranyl polyhedra. Further work on the chemistry of this and other systems of hexavalent uranium and low molecular weight carboxylic acids, especially formic acid, is likely to turn up new insights.

Although a hierarchical scheme exists for classifying inorganic uranyl compounds [1], no similar work has been done for organic compounds. Such a hierarchy would have practical benefits, in particular making structural information more accessible and understandable to workers studying related problems such as the environmental transport of hexavalent uranium as dissolved organic complexes. We offer a simple scheme that classifies uranyl oxalate structures by analyzing the long-range structural features and the coordination environments of uranyl ions, which leads to a structural symbol that can be used to easily identify uranyl oxalates with common structural features. This system is equally applicable to other carboxylate complexes with the uranyl ion, and could be extended to apply to any organic complex of the uranyl ion.
Photoluminescence Properties of Mn-doped Zinc Silicates Synthesized by Combinatorial Sputtering Technique
Authors: Wang Lih-Ping , Chao Wen-Hsuan , Wang Shu-Huei , Huang Tien-Heng , Wu Ren-Jye
Published: April 2011

The photoluminescence (PL) properties of Mn-doped zinc silicates were studied by combinatorial synthesis and characterization technique associated with various process parameters. The material libraries were prepared with composition spreading in Zn and Mn concentration. The PL emission was green or orange, and depended strongly on the stoichiometry of the zinc silicates and the annealing temperature. The orange emission was observed in Mn-doped zinc silicates annealed at 800°C, which attributed to the increase of crystal field in a highly non-stoichiometric α-Zn2SiO phase ((Zn+Mn)/Si <1).
Microstructure and Composition of Au-Sn Eutectic Solder Electroplated from a Single Solution
Authors: Jeong G. H. , Kim J. H. , Lee Duhyun , Suh S. J.
Published: April 2011

In this study, we produced Au-Sn alloy electroplated from a single solution and optimized the composition. The composition of electroplated Au-Sn alloy was Au-31.02 at.% Sn at the condition of 6 ms on - 4 ms off pulse current, 50 °C and 10 mA/cm2. Results in XRD analysis showed that Au-Sn alloy electroplated at DC 10 mA/cm2 had AuSn phase (δ) only and Au5Sn phase (d) appeared with decreasing the pulsed current on time. Also micro-patterned Au-Sn solder bump was produced by photolithography. Though it’s composition of Au-35.98 at.% Sn was not optimum, we tried to bond between Au-Sn solder bump and Si wafer that was coated with Ti (100 nm)/Au (300 nm).
Laser Thin Film Processing of Biopolymers: Mussel Adhesive Protein Analog
Authors: Doraiswamy Anand , Narayan R J , Dinu C Z , Cristescu R , Messersmith P B , Stafslien S , Chrisey D B
Published: April 2011

Mussel adhesive protein analogs are biologically-derived materials that possess unique adhesion properties. We have demonstrated thin film growth of DOPA modified- PEG block copolymer mussel adhesive protein analogs using a novel laser processing technique known as matrix assisted pulsed laser evaporation (MAPLE). The main functional groups of the mussel adhesive protein analog are present in the MAPLE-transferred film. These novel polymer thin films have numerous medical, electronic, and marine applications.
Dielectric and Optical Properties of Polymer Confined in Random Porous Matrices
Authors: Aliev Fouad
Published: April 2011

We report the results of the investigations of the influence of confinement on the glass transition and dynamics of the a-relaxation processes in poly(octylmethacrylate) (POMA) by dielectric spectroscopy. The polymer was synthesized directly in pores of the porous glass matrix with interconnected and randomly oriented pores with an average pore size of 100 nm by free radical polymerization of the monomer. We found that confinement is resulted in the reduction of the glass transition temperature Tg of the polymer. This change in Tg was mainly due to the existence of a developed pore wall-polymer interface and difference in the dynamic behavior of polymer in the surface layers compared to that in the bulk. Complementary light scattering experiments show that in 100 nm matrices containing the polymer an anomalous change in light scattering, which switches the composite from the opaque state to the transparent, in a narrow temperature range around T = 60 °C. These changes could be explained by assuming that at low temperatures (opaque state) the orientational order of the relatively long linear aliphatic side groups is induced by the inner pore surface. The assumption of the formation of the orientationally ordered regions at the pore wall in confined POMA is in agreement with the molecular structures of the polymer and the surface of silica.
Effect of Zinc Oxide Nanocrystals in Media Containing E. coli and C. xerosis Bacteria
Authors: Merced Triana , Santos Stephanie , Rivera Omayra , Villalba Nicole , Baez Yahira , Gaudier José , Avalos Javier , Perales Oscar , Tomar M. S. , Parra-Palomino A. , Avalos Javier
Published: April 2011

The present investigation is centered on the study of the growth curves of E. coli and C. xerosis bacteria in the presence of nanosize particles of Zinc Oxide. Previous works demonstrated the sensitivity of the bacteria, when these were reproduced in media that contain nanoparticles of luminescent silicon and Cobalt Ferrite. Doped ZnO nanocrystals were synthesized by conventional precipitation in ethanol solutions as reported by Spanhel and Anderson for bare ZnO. In our case, the syntheses were carried out under room-temperature conditions.

The experimental results of E. coli bacteria in contact with a stable suspension of nanoparticles of Zinc Oxide, shows a growth curve without adaptation period. Moreover a short and slowly logarithmic stage has been observed, reaching the stationary stage after approximately four hours compared with one in absence of the nanoparticles (standard curve). During the observations, a change in the lifetime of the bacteria (metabolism) with particulate was noticed,as well as the beginning of the mortality stage. However, different results were recorded for silicon and ferrite. For the case of the bacteria C. xerosis, the curve with particles is above its standard curve, for all times with none of the oscillations which occured in the nanometer silicon. For these bacteria the beginning of the mortality stage is observed when they have particles. For both bacteria with Zinc Oxide nanoparticles this occurs approximately after nine hours.
Tin-Doped Hematite Nanoparticles for Gas-Sensing Applications
Authors: Sorescu Monica , Diamandescu Lucian , Tarabasanu-Mihaila Doina
Published: April 2011

Structural and morphological characteristics of (1-x)α-Fe2O3-xSnO2 (x=0.0-1.0) nanoparticles obtained under hydrothermal conditions have been investigated by X-ray diffraction (XRD) and Mössbauer spectroscopy. On the basis of the Rietveld structure refinements of the XRD spectra at low tin content, it was found that Sn4+ partially substitutes for Fe3+ at the octahedral sites. The mean particle dimension decreases from 70 to 6 nm as the molar fraction x increases. The estimated solubility limits in the system of tin-doped hematite nanoparticles synthesized under hydrothermal conditions are x<0.2 for Sn4+ in α-Fe2O3 and x>0.7 for Fe3+ in SnO2.
Combining Sol-Gel Chemistry and Extrusion Process Toward Generating First Vanadium Oxide Macroscopic Fibers
Authors: Biette L. , Serier H. , Carn Florent , Achard Marie-France , Steunou Nathalie , Livage Jacques , Backov R.
Published: April 2011

Upon extrusion process, first vanadium oxide macroscopic fibers have been obtained. They are associated to longitudinal Young modulus from 15 to 25 GPa and depict strong high scale textural anisotropy as observed through cross-polarized microscopy. TEM observations and SAXS experiments reveal that those macroscopic fibers are made of nanoscopic ribbons associated to preferential orientation parallel to the macroscopic fiber main axis, while XRD and NMR investigations reveal a microstructure close to the V2O5.1.8H2O xerogels. These fibers can detect down to 0.1 ppm of ethanol within 16 seconds at 40°C.
Single Stranded DNA Decorated Carbon Nanotube Transistors for Chemical Sensing
Authors: Staii Cristian , Chen Michelle , Gelperin Alan , Johnson Alan T.
Published: April 2011

We demonstrate that single walled carbon nanotube field effect transistors (swCN-FET) decorated with single stranded DNA (ss-DNA) form a new, versatile, and highly sensitive class of nanoscale chemical sensors. These sensors are based on ss-DNA as the chemical recognition site and swCN-FET as the electronic read-out component. The ss-DNA decorated swCN-FETs are sensitive to chemical species (odors) that do not cause a detectable response in bare, as-fabricated swCN-FETs. Furthermore, odor responses ss-DNA decorated FETs differ in sign and magnitude for different odors, and the response characteristics depend on the base sequence of the ss-DNA used to decorate the swCN. The sensor surface is self-regenerating: samples maintain a constant response with no need for sensor refreshing through at least several dozens gas exposure cycles. These remarkable attributes suggest that DNA-decorated swCN-FET sensors could be created with sensitivity to a large variety of compounds, as required for “electronic-nose” and “electronic tongue” applications in medicine and homeland security.
Dielectric Property Controls Using Crystal Structure Anisotropy In Bismuth Layer-Structured Dielectrics
Authors: Suzuki Muneyasu , Takahashi Kenji , Watanabe Takayuki , Takenaka Tadashi , Funakubo Hiroshi
Published: April 2011

Temperature dependency of the dielectric property of c-axis-oriented SrBi4Ti4O15 films was investigated in a temperature range from 80 to 400 K. c-axis-oriented epitaxial films with the film thickness of 30 and 140 nm were grown on (100)cSrRuO3//(100)SrTiO3 substrates by metal organic chemical vapor deposition (MOCVD). Increasing lattice distortions along the a- and c-axes with decreasing film thickness was ascertained by XRD reciprocal space mapping. However, capacitance change normalized by the capacitance data at 300 K for with temperature was independent of the film thickness; it increased from 80 to 230 K and contrary decreased with increasing the temperature. Especially, the temperature coefficient of capacitance from 230 to 330 K was almost the same. It indicates that dielectric characteristics of these films for the temperature are independent of the film thickness in the actual use. Moreover, the same mesurement for the 120 nm-thick fiber-textured c-axis-oriented SrBi4Ti4O15 film deposited on the (100)cLaNiO3/(111)Pt/TiO2/SiO2/(100)Si substrate was also investigated. Resultant capacitance change with the temperature was basically the same with that of the epitaxial one, even though the temperature at maximum capacitance value was slightly shifted to lower temperature of 200 K. These data suggest that of capacitance change with the temperature was almost independent of the film thickness and the in-plane orientation.
Effect of Composition on Ferroelectric Response of Bi4-xSmxTi3O12 Thin Films
Authors: Dussan Sandra , Tomar Maharaj , Melgarejo Ricardo , Katiyar Ram
Published: April 2011

Bismuth titanate (Bi4Ti3O12) is an electroceramic within the Aurivillius phase material with week ferroelectric memory. However, the partial substitution of Bi ion by a trivalent rare earth resulted in improved ferroelectric polarization. We synthesized Bi4-xSmxTi3O12 by a solution chemistry route and thin films were deposited by spin coating on Pt (Pt/TiO2/SiO2/Si) substrate. X-ray diffraction studies of the films showed a stoichiometric solid solution for the composition x ≤0.85. The films showed fatigue free ferroelectric polarization (Pr = 19.8 µC/cm2) for the composition x = 0.70. The films showed low leakage current at room temperature, showing the possibility of lead free ferroelectric devices.
Structural dynamics of PZT thin films at the nanoscale
Authors: Grigoriev Alexei , Do Dal-Hyun , Kim Dong Min , Eom Chang-Beom , Adams Bernhard , Dufresne Eric M. , Evans Paul G.
Published: April 2011

When an electric field is applied to a ferroelectric the crystal lattice spacing changes as a result of the converse piezoelectric effect. Although the piezoelectric effect and polarization switching have been investigated for decades there has been no direct nanosecond-scale visualization of these phenomena in solid crystalline ferroelectrics. Synchrotron x-rays allow the polarization switching and the crystal lattice distortion to be visualized in space and time on scales of hundreds of nanometers and hundreds of picoseconds using ultrafast x-ray microdiffraction. Here we report the polarization switching visualization and polarization domain wall velocities for Pb(Zr0.45Ti0.55)O3 thin film ferroelectric capacitors studied by time-resolved x-ray microdiffraction.
The Formation of Smooth, Defect-free, Stoichiometric Silicon Carbide Films from a Polymeric Precursor
Authors: Pitcher Michael , Bianconi Patricia
Published: April 2011

Silicon carbide (SiC) materials, which are used in a variety of applications, are often produced using powder processing, sintering or bulk crystal growing techniques. The formation of silicon carbide films or shaped products, via these methods, is often extremely difficult and/or requires high temperatures. Here we report the synthesis and characterization of a polymeric precursor, Polymethylsilyne (PMSy), and it subsequent conversion to â-SiC. The polymer is simple to synthesize and is easily manipulated in air. The ceramic produced from PMSy is extremely pure, stoichiometric SiC and is produced in high yields (up to 85%). The ceramic films that can be produced from PMSy on a variety of substrates, from ceramics to metals, are again stoichiometric SiC and are smooth, continuous and defect free; possibly enabling the use of these films in electronic applications.
Novel Method for High Speed SiC Vapor Growth
Authors: Wang Xiaolin , Dang Cai , Zhang Hui , Dudley Michael
Published: April 2011

Silicon carbide is a promising semiconductor material for electrical and optoelectronic applications in the area of high power, high temperature, high frequency and intense radiation. Many groups have worked on growing SiC bulk crystals by sublimation from SiC powder source at a temperature above 2000 oC under an argon environment. They have also worked on improving the crystal growth rate. Traditional approach is to increase furnace temperature to enhance the growth rate. However, high cost of inert crucible at high temperature and impurity caused by crucible degradation set limit on the maximum growth rate which can be achieved. Current existing crucible and other components in the furnace are no longer passive at high temperature. Also understanding of vapor transport during powder sublimation and the interplay between vapor transport and powder sublimation is important for the optimization of the sublimation growth process. A comprehensive numerical model combining heat transfer, sublimation, species transport, and powder porosity evolution of SiC sublimation growth process is developed in this paper. The mechanism of vapor transport is described, in which a driving force is introduced to explain vapor transport. A new method to increase crystal growth rate is proposed based on the model. The new method includes changing the initial powder porosity and creating a hole in the packed powder. Simulation results for the case with a central hole and without hole are presented. The results show that the powder sublimation rate increases by creating a hole, and it is also validated by experiments. The results also reveal that the mass of the as-grown crystal increases if the powder sublimation rate increases. Finally, the powder geometry is optimized using numerical simulations.
Recent Results From Epitaxial Growth on Step Free 4H-SiC Mesas
Authors: Neudeck Philip G. , Trunek Andrew J. , Spry David J. , Powell J. Anthony , Du Hui , Skowronski Marek , Bassim Nabil D. , Mastro Michael A. , Twigg Mark E. , Holm Ronald T. , Henry Richard L. , Eddy Charles R.
Published: April 2011

This paper updates recent progress made in growth, characterization, and understanding of high quality homoepitaxial and heteroepitaxial films grown on step-free 4H-SiC mesas. First, we report initial achievement of step-free 4H-SiC surfaces with carbon-face surface polarity. Next, we will describe further observations of how step-free 4H-SiC thin lateral cantilever evolution is significantly impacted by crystal faceting behavior that imposes non-uniform film thickness on cantilever undersides. Finally, recent investigations of in-plane lattice constant mismatch strain relief mechanisms observed for heteroepitaxial growth of 3C-SiC as well as 2H-AlN/GaN heterofilms on step-free 4H-SiC mesas will be reviewed. In both cases, the complete elimination of atomic heterointerface steps on the mesa structure enables uniquely well-ordered misfit dislocation arrays to form near the heterointerfaces with remarkable lack of dislocations threading vertically into the heteroepilayers. In the case of 3C-SiC heterofilms, it has been proposed that dislocation half-loops nucleate at mesa edges and glide laterally along the step-free 3C/4H interfaces. In contrast, 3C-SiC and 2H-AlN/GaN heterofilms grown on 4H-SiC mesas with steps exhibit highly disordered interface misfit dislocation structure coupled with 100X greater density of dislocations threading through the thickness of the heteroepilayers. These results indicate that the presence of steps at the heteroepitaxial interface (i.e., on the initial heteroepitaxial nucleation surface) plays a highly important role in the defect structure, quality, and relaxation mechanisms of single-crystal heteroepitaxial films.
Epitaxial Growth and Characterization of SiC on Different Orientations
Authors: Rowland Larry B. , Li Canhua , Dunne Greg T. , Fronheiser Jody A.
Published: April 2011

Background doping as well as intentional doping using nitrogen and trimethylaluminum have been investigated for 4H-SiC epitaxy on offcut Si face, C face, and a-axis substrates over a wide range of C:Si ratio. Smooth morphology can be obtained at a C:Si ratio of 2.0 on a-axis substrates but not on Si or C face material. Background doping levels of <1 × 1015 cm-3 were achieved on a-axis and Si face material. Nitrogen incorporated much more efficiently on C face and a-axis as compared to Si face. Aluminum incorporated most efficiently on Si face and least efficiently on C face. Both of the above dopant incorporation trends were most pronounced at high C:Si ratios and were small or virtually absent at low C:Si ratios.
Comparison of Parameter Extraction Techniques for SiC Schottky Diodes
Authors: Weng Ming Hung , Horsfall Alton B. , Wright Nick G. , Vassilevski Konstantin V. , Nikitina Irina P.
Published: April 2011

Schottky barrier diodes fabricated on Silicon carbide have been demonstrated as gas sensors for deployment in extreme environments. It has been shown that the interfacial layer formed at the Metal – Semiconductor junction, determines both the sensitivity and the reliability of the device. Hence, accurate knowledge of the thickness and interfacial trap density of this layer is required to make predictions of the behaviour of the sensor in the environment under investigation and to predict its variation with time. Diode parameters, such as the ideality factor, barrier height and series resistance have been extracted from experimental measurements on Palladium Schottky Barrier diodes on 4H SiC, over a range of temperatures. The comparison of the parameters extracted from modified Norde function, Cheung's method and Thermonic Emission model has been performed. The variation in the barrier height obtained is quite marked between the different techniques. The reverse I-V characteristics have been used to extract thickness of the interfacial layer, by fitting to the experimental data using the TEBIL model to extract the value of Dit from ä and the ideality factor, assuming the interfacial layer is stoichiometric SiO2 . This allows a comparison between the effective interfacial layer behaviour for the different parameter extraction techniques and demonstrates that knowledge of this interfacial layer is influenced by the technique selected.
Ink-Jet Printing of Encapsulated Bacteria
Authors: Coldren Faith Marie , McGuirt John B. , Levi Nicole , Palavecino Elizabeth , Carroll David L.
Published: April 2011

Even though viability for printed bacteria has been demonstrated, the effect of thermal ink-jet printing on cellular ultrastructures is unknown. Retention of viability is useful when colony growth is desired. However, when bacteria are isolated from a human infection they often exhibit characteristics that can be lost when grown in standard laboratory cultures. Ideally, individual bacteria from an infection could be printed and studied without extensive culturing or processing.

We have investigated the gram-positive organism Staphylococcus aureus and the extracellular polymeric ultrastructure that encapsulates the bacterial cell. The capsule is composed of cell-wall associated polysaccharides. Our goal was to use ink-jet printing to spatially control the placement of S. aureus, without affecting the extracellular ultrastructure. Observation by scanning electron microscopy comparing the integrity and uniformity of encapsulated S. aureus before and after thermal ink-jet printing suggests that the capsule is disrupted, possibly completely removed, during printing.
Dynamical Fracture Instabilities Due to Local Hyperelasticity at Crack Tips
Authors: Buehler Markus J. , Gao Huajian
Published: April 2011

When materials break and cracks propagate, bonds between atoms are broken generating two new material surfaces. Most existing theories of fracture assume a linear elastic stress-strain law. However, the relation between stress and strain in real solids is strongly nonlinear due to large deformation near a moving crack tip, a phenomenon referred to as hyperelasticity or nonlinear elasticity. Cracks moving at low speeds create atomically flat mirror-like surfaces, whereas cracks at higher speeds leave misty and hackly fracture surfaces. This change in fracture surface morphology is a universal phenomenon found in a wide range of different brittle materials, but the underlying physical reason has been debated over an extensive period. Using massively parallel large-scale atomistic simulations employing a new, simple atomistic material model allowing a systematic transition from linear elastic to strongly nonlinear material behaviors, we show that hyperelasticity can play a governing role in dynamical crack tip instabilities in fracture of brittle materials. We report a generalized model that treats the instability problem as a competition between different mechanisms controlled by local stress field and local energy flow near the crack tip. Our results indicate that the fracture instabilities do not only appear in defected materials, but instead are an intrinsic phenomenon of dynamical fracture. Our findings help to explain controversial experimental and computational results, including experimental observation of crack propagation at speeds beyond the shear wave speed in rubber-like materials.
Effect of MeV Si Ion Bombardment on Thermoelectric Characteristics of Sequentially Deposited SiO2/AuxSiO2(1-x) Nanolayers
Authors: Budak S. , Zheng B. , Muntele C. , Xiao Z. , Muntele I. , Chhay B. , Zimmerman R. L. , Holland R. L. , Ila D.
Published: April 2011

We made 50 and 100 periodic nano-layers of electro-cooling system consisting of SiO2/AuxSiO2(1−x) super lattice with Au layer deposited on both side as metal contact using Ion Beam Assisted Deposition (IBAD) system. The deposited multi-layer films have a periodic structure consisting of alternating layers where each layer is between 1-10 nm thick. The ultimate objective of this research is to tailor the figure of merit of layered structures used as thermoelectric generators. The super lattices were then bombarded by 5 MeV Si ion at different four fluences to form nano-cluster structure. The film thickness and stoichiometry were monitored by Rutherford Backscattering Spectrometry (RBS) before and after MeV bombardments. We measured the thermoelectric efficiency of the fabricated device before and after MeV bombardments. To accomplish this we measured the cross plane thermal conductivity by 3rd harmonic method, measured cross plane Seebeck coefficient, and measured electric conductivity using Van Der Pauw method before and after 5 MeV Si Bombardments. As predicted the electronic energy deposited due to ionization by MeV Si beam in its track produces nano-scale structures which disrupt and confine phonon transmission therefore reducing thermal conductivity, increasing electron density of state so as to increase Seebeck coefficient, and electric conductivity, thus increasing figure of merit. We will present our findings during the meeting.

* Research sponsored by the Center for Irradiation of Materials, Alabama A&M University and by the AAMURI Center for Advanced Propulsion Materials under the contract number NAG8-1933 from NASA, and by National Science Foundation under Grant No. EPS-0447675.
Solar Effects on Tensile and Optical Properties of Hubble Space Telescope Silver-Teflon Insulation
Authors: de Groh Kim K. , Dever Joyce A. , Snyder Aaron , Kaminski Sharon , McCarthy Catherine E. , Rapoport Allison L. , Rucker Rochelle N.
Published: April 2011

During the fourth servicing mission of the Hubble Space Telescope (HST), the second set of solar arrays (SA-II) was replaced with a third set and the SA-II was brought back to Earth. A section of the retrieved SA-II solar array drive arm (SADA) multilayer insulation (MLI), which experienced 8.25 years of space exposure, was provided to NASA Glenn Research Center for environmental durability analyses of the top layer of silver-Teflon fluorinated ethylene propylene (Ag-FEP). Because the SADA MLI had solar and anti-solar facing surfaces and was exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on environmental degradation of Ag-FEP, a commonly used spacecraft thermal control material. Therefore, the objective of this research was to characterize the degradation of retrieved HST SADA Ag-FEP with particular emphasis on solar radiation effects. Data obtained included tensile properties, solar absorptance, surface morphology and chemistry. The solar facing surface of the SADA was found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing indicated that the solar facing surface lost 60% of its mechanical strength and 90% of its elasticity while the anti-solar facing surface had ductility similar to pristine FEP. The solar absorptance of both the solar facing surface (0.155 ± 0.032) and the anti-solar facing surface (0.208 ± 0.012) were found to be greater than pristine Ag-FEP (0.074). Solar facing and anti-solar facing surfaces were microscopically textured, and locations of isolated contamination were present on the anti-solar surface resulting in increased localized texturing. Yet, the overall texture was significantly more pronounced on the solar facing surface indicating a synergistic effect of combined solar exposure and increased heating with atomic oxygen erosion. The results indicate a very strong dependence of degradation, particularly embrittlement, upon solar exposure with orbital thermal cycling having a significant effect.
High Density Addressable Protein and Cell Patterning via Switchable Superhydrophobic Microarrays
Authors: Shiu Jau-Ye , Chen Peilin
Published: April 2011

There have been increasing research interests in the development of novel nano or micro-patterning techniques to create arrays of functional biomolecules for miniaturized assays, which could be used in various biomedical applications such as biosensors, proteomic, immunoassays or drug screening. Several techniques have been demonstrated capable of writing or printing biomolecules with very high degree of spatial control including dip-pen lithography, nanopipet, inkjet printing, photolithography, micro contact printing etc. The serial writing techniques provide the individual addressability whereas the parallel printing processes offer easy and fast protein patterning. However, it remains difficult to create complex patterns, such as functional multicomponent protein arrays, in parallel with individual addressability. Here we describe a novel approach to fabricate functional multicomponent protein and cell arrays where the electrowetting effect was employed to convert a water-repellent superhydrophobic surface into a wettable one allowing fast and high density addressable protein and cell deposition on the otherwise protein- and cell-resistant superhydrophobic surface. It has been shown that each element on the switchable superhydrophobic microarray could be addressed individually and different types of functional biomolecules could be selectively deposited on the microarray. Such protein patterning technique offers several advantages over other techniques including parallel protein deposition with individual addressability, possibility for large-scale patterning and easy integration with microfluidic system. The facts that the superhydrophobic surfaces can be fabricated from many hydrophobic materials and the electrowetting works for most dielectric materials allow great flexibility in the selection of the surface materials for protein deposition.
Silicon Nanocrystals Fabricated by a Novel Plasma Enhanced Hydrogenation Technique Suitable for Light Emitting Devices
Authors: Jamei Mehdi , Karbassian Farshid , Mohajerzadeh Shams , Abdi Yaser , Hashemi Pouya , Robertson Michael , Yuill Sandra
Published: April 2011

The preparation of nano-crystalline silicon suitable for optoelectronic purposes by plasma-enhanced hydrogenation is reported. The method is compatible with mature ULSI technology because of its low temperature and non-wet processing environment. Visible light emission with peak wavelengths ranging from blue to red has been observed and could be tuned by varying the processing conditions. While the blue light emission may be due to surface defects present in the oxide layer, the green and red light emissions are believed to be due excitonic emission within the nano-crystalline grains as a result of quantum confinement effects. The layers were studied by SEM, TEM, CL and FTIR. A LED was fabricated and electroluminescence demonstrated.