bluuebunny/crossref_metadata_2025 huggingface dataset:
AN ALMOST LINEAR TIME ALGORITHM FOR A GENERAL HAPLOTYPE SOLUTION ON TREE PEDIGREES WITH NO RECOMBINATION AND ITS EXTENSIONS
Authors: LI XIN , LI JING
Published: June 2009

We study the haplotype inference problem from pedigree data under the zero recombination assumption, which is well supported by real data for tightly linked markers (i.e. single nucleotide polymorphisms (SNPs)) over a relatively large chromosome segment. We solve the problem in a rigorous mathematical manner by formulating genotype constraints as a linear system of inheritance variables. We then utilize disjoint-set structures to encode connectivity information among individuals, to detect constraints from genotypes, and to check consistency of constraints. On a tree pedigree without missing data, our algorithm can output a general solution as well as the number of total specific solutions in a nearly linear time O(mn · α(n)), where m is the number of loci, n is the number of individuals and α is the inverse Ackermann function, which is a further improvement over existing ones. We also extend the idea to looped pedigrees and pedigrees with missing data by considering existing (partial) constraints on inheritance variables. The algorithm has been implemented in C++ and will be incorporated into our PedPhase package. Experimental results show that it can correctly identify all 0-recombinant solutions with great efficiency. Comparisons with other two popular algorithms show that the proposed algorithm achieves 10 to 105-fold improvements over a variety of parameter settings. The experimental study also provides empirical evidences on the complexity bounds suggested by theoretical analysis.
Nutrition and the Lung
Authors: Bhatia Jatinder , Parish Anjali
Published: June 2009

The use of surfactant replacement, ‘kinder gentler’ modes of ventilation combined with prenatal corticosteroids have all played a role in improved survival rates of very-low-birth-weight infants but have not reduced the prevalence of chronic lung disease. The increased rates of prematurity being observed in the United States along with the increased survival makes the overall problem of treatment of infants with established disease expensive spanning neonatology, pediatric critical care and general pediatrics and involving a myriad of specialists over the life of the surviving infant. However, none of the therapies used over the years have proven to be effective or have long-term adverse effects, nor have they been accepted as methods to prevent chronic lung disease. Although intuitively an appropriate nutritional therapy may be a useful adjunct in the care of the premature sick infant, perinatal malnutrition remains a major problem. The role of nutrition therapy in health and disease as it pertains to the lung will be reviewed.
Rats Repeatedly Exposed to Toluene Diisocyanate Exhibit Immune Reactivity against Methyl Isocyanate-Protein Conjugates
Authors: Svensson-Elfsmark Linda , Koch Bo L. , Gustafsson Åsa , Bucht Anders
Published: June 2009

Background: Volatile monoisocyanates are formed through thermal degradation when products containing polyurethane are heated. Repeated exposure to diisocyanates, such as toluene diisocyanate (TDI) are a well-known cause of occupational asthma. However, although monoisocyanates are abundant in occupational settings, there are few data concerning their ability to provoke immune reactions and asthma. We compared immune reactivity and respiratory disease following single or repeated inhalation exposures to the monoisocyanates methyl isocyanate (MIC) and isocyanic acid (ICA) with the effects of TDI. Methods:Isocyanates were administrated either as single vapor exposures or as repeated intranasal instillations in rats. Adverse health effects were monitored by analyzing airway inflammation, respiratory function and weight gain. Immune reactivity caused by repeated exposures was studied by analysis of isocyanate-specific antibodies and airway infiltration of immune competent cells. Results: Repeated exposures to TDI induced airway infiltration of neutrophils and lymphocytes, while neither MIC nor ICA provoked a detectable inflammatory response. Antibodies against isocyanate-albumin conjugates were detected in serum after both exposures to TDI and MIC, but not to ICA. TDI-exposed rats also displayed IgG antibodies against MIC-albumin conjugates. Even though MIC did not induce airway inflammation, single exposure provoked an increase in airway resistance and repeated exposures caused weight loss similar to that of TDI. Conclusions: Airway exposure to TDI produces an antibody response not only against TDI but also against MIC-protein conjugates. This indicates that immune reactivity against abundant monoisocyanates in occupational environments can occur in individuals pre-sensitized with low abundance but highly sensitizing diisocyanates.
Role of Progesterone Receptor Isoforms in Female Sexual Behavior Induced by Progestins in Rats
Authors: Guerra-Araiza Christian , Gómora-Arrati Porfirio , García-Juárez Marcos , Armengual-Villegas Alejandra , Miranda-Martínez Alfredo , Lima-Hernández Francisco Javier , Camacho-Arroyo Ignacio , González-Flores Oscar
Published: June 2009

Progesterone and its ring A reduced metabolites regulate female sexual behavior through the direct or indirect activation of progesterone receptor (PR) which has two isoforms with different function and regulation: PR-A and PR-B. The contribution of each PR isoform to the regulation of lordosis in rats is unknown. We explored the role of PR isoforms in lordosis display induced by progesterone and two of its ring A reduced metabolites: 5α-pregnan-3,20-dione (5α-DHP), and 5β,3β-pregnan-20-one (5β,3β-Pgl) in adult ovariectomized rats. Two weeks after ovariectomy, the animals were injected subcutaneously with 5 μg of estradiol benzoate (EB), and 40 h later, progestins were injected intracerebroventricularly. PR-B and total PR (PR-A + PR-B) sense or antisense oligonucleotides were administered intracerebroventricularly immediately before EB injection and 24 h later. Lordosis was evaluated 30, 120 and 240 min after progestin administration. Western blot analysis of both PR isoforms was performed in the hypothalamus and preoptic area 24 h after lordosis tests. All progestins induced maximal lordosis 120 min after administration, and antisense oligonucleotides against both PR isoforms inhibited lordosis in all animals. PR-B antisense oligonucleotides also inhibited lordosis induced by progesterone and 5α-DHP although with less efficacy than total PR antisense oligonucleotides, but the former inhibited lordosis induced by 5β,3β-Pgl in a similar manner as total PR antisense oligonucleotides. In the hypothalamus and preoptic area, the content of both PR isoforms or PR-B alone was diminished by the administration of total or PR-B antisense oligonucleotides, respectively. These results suggest that the PR-B isoform is essential for the display of the lordosis behavior in rats.
Risk Assessment of Symptomatic Intracerebral Hemorrhage After Thrombolysis Using DWI-ASPECTS
Authors: Singer Oliver C. , Kurre Wiebke , Humpich Marek C. , Lorenz Matthias W. , Kastrup Andreas , Liebeskind David S. , Thomalla Goetz , Fiehler Jens , Berkefeld Joachim , Neumann-Haefelin Tobias
Published: June 2009

Background and Purpose—

Pretreatment lesion size on diffusion-weighted imaging (DWI) is a risk factor for symptomatic intracerebral hemorrhage (sICH) associated with thrombolytic treatment. Here, we investigated whether the Alberta Stroke Programme Early CT Score (ASPECTS) applied to DWI images (DWI-ASPECTS) predicts sICH risk accurately.

Methods—

In this retrospective multicenter study, prospectively collected data of 217 patients with anterior circulation stroke treated with intravenous or intraarterial thrombolysis within 6 hours after symptom onset were analyzed. Pretreatment DWI-ASPECTS scores were assessed by 2 independent investigators. For bleeding risk analysis, DWI-ASPECTS scores were either categorized into 0 to 7 (n=105) or 8 to 10 (n=112) or in 3 groups of similar sample size (DWI-ASPECTS 0 to 5 [n=69], 6 to 7 [n=70], and 8 to 10 [n=78]).

Results—

DWI-ASPECTS scores correlated well with the DWI lesion volume (
r
=0.77,
P
<0.001, Spearman Rank test). Interobserver reliability for the assessment of DWI-ASPECTS was moderate (weighted kappa 0.441 [95% CI 0.373 to 0.509]). Twenty-three (10.6%) patients developed sICH. The sICH rate was significantly higher in patients with DWI-ASPECTS scores 0 to 7 (n=21, 15.1%) as compared to patients with DWI-ASPECTS scores 8 to 10 (n=2, 2.6%,
P
=0.004). sICH risk was 20.3%, 10%, and 2.6% in the 0 to 5, 6 to 7, and 8 to 10 DWI-ASPECTS groups, respectively. DWI-ASPECTS remained an independent prognostic factor for sICH after adjustment for clinical baseline variables (age, NIHSS, time to thrombolysis).

Conclusions—

DWI-ASPECTS predicts sICH risk after thrombolysis and may be helpful to contributing to quick sICH risk assessment before thrombolytic therapy.
Successful treatment of Candida parapsilosis and Pseudomonas aeruginosa infection using medical and surgical management in an injecting drug user with mitral and aortic valve endocarditis: a case report
Authors: Daas Hanady , Abuhmaid Fadi , Zervos Marcus
Published: June 2009

Introduction

Polymicrobial endocarditis is a well-recognized problem in intravenous drug users and it accounts for 1 to 3% of endocarditis cases overall and up to 9% in other series. The most common combinations of organisms include Staphylococcus aureus and Streptococcus pneumoniae followed by Staphylococcus aureus and Pseudomonas aeruginosa. Candida parapsilosis endocarditis carries a mortality rate of 45%, and each infection with Candida or Pseudomonas endocarditis per se carries a very high mortality rate approaching 85% and 80%, respectively. The combination of P. aeruginosa and C. parapsilosis has never been encountered and there have been no earlier reports of the combination of C. parapsilosis and P. aeruginosa in adult intravenous drug users as a cause of endocarditis.

Case presentation

We present a 49-year-old man with bivalvular endocarditis with P. aeruginosa and C. parapsilosis. He had a prior bivalvular replacement in 2005 that became infected with the above microorganisms and he was treated with intravenous antibiotics. Because of ongoing intravenous drug use, a second valve replacement was denied. A few days later, the patient presented with septic shock secondary to P. aeruginosa and C. parapsilosis recurrent endocarditis. The infection was cured with a second bivalvular replacement and extended therapy with antibiotics and antifungals.

Conclusion

This is the first time a patient has presented with P. aeruginosa and C. parapsilosis endocarditis. Relapsing polymicrobial endocarditis can be cured with medical and surgical therapy.
Near fatal posterior reversible encephalopathy syndrome complicating chronic liver failure and treated by induced hypothermia and dialysis: a case report
Authors: Chawla Rashmi , Smith Daniel , Marik Paul E
Published: June 2009

Introduction

Posterior reversible encephalopathy syndrome is a clinico-neuroradiological entity characterized by headache, vomiting, altered mental status, blurred vision and seizures with neuroimaging studies demonstrating white-gray matter edema involving predominantly the posterior region of the brain.

Case presentation

We report a 47-year-old Caucasian man with liver cirrhosis who developed posterior reversible encephalopathy syndrome following an upper gastrointestinal hemorrhage and who was managed with induced hypothermia for control of intracranial hypertension and continuous veno-venous hemodiafiltration for severe hyperammonemia.

Conclusion

We believe this is the first documented case report of posterior reversible encephalopathy syndrome associated with cirrhosis as well as the first report of the use of induced hypothermia and continuous veno-venous hemodiafiltration in this setting.
Microstructure characterization of ODS-RAFM steels
Authors: Mateus R. , Carvalho P.A. , Nunes D. , Alves L.C. , Franco N. , Correia J.B. , Fernandes H. , Silva C. , Lindau R. , Alves E.
Published: June 2009

Results of the microstructural characterization of four different RAFM ODS Eurofer 97 batches are presented and discussed. Analyses and observations were performed by nuclear microprobe and scanning and transmission electron microscopy. X-ray elemental distribution maps obtained with proton beam scans showed homogeneous composition within the proton beam spatial resolution and, in particular, pointed to a uniform distribution of ODS (yttria) nanoparticles in the Eurofer 97 matrix. This was confirmed by transmission electron microscopy. Scanning electron microscopy coupled with energy dispersive spectroscopy made evident the presence of chromium carbide precipitation. Precipitates occurred preferentially along grain boundaries (GB) in three of the batches and presented a discrete distribution in the other, as a result of different thermo-mechanical routes. Additional electron backscattered diffraction experiments revealed the crystalline textures in the ferritic polycrystalline structure of the ODS steel samples.
A Surface Modification of Hastelloy X by a SiC Coating and an Ion Beam Irradiation for a Potential use for Iodine-Sulfur Cycle in Nuclear Hydrogen Production System
Authors: Park Jae-Won , Khan Zuhair S , Kim Hyung-Jin , Kim Yongwan
Published: June 2009

The materials used for the SO3 decomposer in Iodine-Sulfur (IS) cycle for Nuclear Hydrogen Production System require excellent mechanical properties as well as a high corrosion resistance in SO2/SO3 environment at an elevated temperature up to 950°C. So far, no metallic materials have been suggested to be useful in such an environment. A surface modification of Hastelloy X by a SiC coating processed by an electron beam evaporative deposition has been studied in combination with an ion beam mixing (IBM) and an ion beam hammering (IBH). The simply deposited SiC film on the Hastelloy X substrate is easily peeled-off during an annealing at a high temperature due to a huge difference in their coefficients of thermal expansion (CTE), however the SiC coating on Hastelloy X prepared with IBM is sustained above 900 °C when the heating rate is less than 10 °C/min. The process of coating and IBM consists of a thin SiC film deposition, a subsequent N ion beam bombardment, and then an additional deposition of the film to the designed thickness. IBM plays a role of fastening the SiC film on the Hastelloy X substrate until the interfacial reaction takes place. Once the reaction takes place, new phases are developed at the interface under the consumption of the film and the substrate materials, producing a buffer layer. Without IBM, the SiC film tends to be easily detached during an annealing before the interfacial reaction initiates. The SiC film prepared with IBM requires a post-deposition annealing in vacuum for the interfacial reaction. However, the sublimation of SiC film prepared by an electron beam evaporative deposition occurs at the temperature above 900 °Cdecreasing the thickness of the deposited film. The sublimation of the SiC film can be prevented by IBH in which ion beams are bombarded onto the deposited film. This may be attributed to an ion beam bombardment induced densification of the deposited film. The resultant SiC coated Hastelloy X prepared by IBM and IBH exhibits a high corrosion resistance in a sulfuric acid at 300 °C, suggesting a possible application for the IS cycle.
W-Diamond/Cu-Diamond nanostructured composites for fusion devices
Authors: Nunes D. , Livramento V. , Correia J.B. , Mateus R. , Carvalho P.A. , Shohoji N. , Fernandes H. , Silva C. , Alves E. , Hanada K. , Osawa E.
Published: June 2009

A novel material design for nuclear fusion reactors is proposed based on Cu-Diamond and W-Diamond nanocomposites. The proposed design involves the production of W/W-Diamond/CuDiamond/Cu functionally graded material. W, W-Diamond, Cu-Diamond and Cu nanostructured composite powders were produced independently by mechanical alloying and subsequently consolidated/welded through spark plasma sintering. Modulation of processing parameters allowed controlling the extent of unfavourable conversion of Diamond into tungsten carbide, as well as to overcome the Diamond intrinsically difficult bonding to copper. Microstructural features and microhardness of the as-produced materials are presented.
Effect of Precipitate Depleted Zones on Precipitation Hardening in Mg-based Alloys
Authors: Shepelev D. , Katsman A. , Edelshtein E. , Bamberger M.
Published: June 2009

The formation of precipitate depleted zones (PDZ) near grain boundaries in Mg-based alloys strengthened by precipitation hardening is deemed as detrimental to the material since wide depleted zones may affect the mechanical and corrosion properties of the alloy. Experimental investigation of PDZ evolution in Mg-Zn-Sn-alloys aged at different temperatures for different times was conducted by SEM and TEM and by measuring the microhardness of near grain boundary zones at low loads. It was found that at early stages of aging (175°C, ≤1 day) the hardening is caused by formation of MgZn2 needle- and T-like MgZn2/Mg2Sn particles. The neargrain boundary zone is harder than the grain matrix, due to large round MgZn2 and Mg2Sn particles formed at grain boundaries. Increasing the aging was found to decrease the hardening in the matrix as well as in the near-grain boundary zones due to the dissolution of MgZn2 needles and the coarsening of T-like particles. Substantial microhardness decrease in the near-grain boundary zone (from 70 to ~30 HV) found at low loads (10 gr) was connected with the formation of PDZ. This was confirmed by TEM and SEM studies. Further aging, at 225°C for 1-8 days, leads to the formation of "crusts" of enlarged T-like particles around depletion zones. As a result, the microhardness of PDZ's measured at higher loads (25 and 50 gr) increases up to ~ 60÷70 HV close to the ones measured in the grain matrix.
Fabrication of Crosslinked Block Copolymer Nanoparticles Using Cold Vulcanization
Authors: Ma Sungwon , Thio Yonathan
Published: June 2009

The aim of this study is to understand the crosslinked system of poly(styrene)-bpoly(isoprene) copolymer using cold vulcanization process as a facile method to produce anisometric nanoparticles. The morphologies of block copolymers could be controlled by the type of monomers, block junction, composition, and block size. A systematic methodology, utilizing cylindrical and lamellar morphologies of PS-b-PI copolymer, was used for producing fiber and sheet shaped nanoparticles. The cold vulcanization process was accomplished using sulfur monochloride (S2Cl2) as crosslinking agent. The microstructures and crosslinking density of crosslinked PS-b-PI copolymers were imaged and characterized. This study demonstrated the crosslinking of microphase separated block copolymer as a method to create particles with controlled size, shape, and physical properties.
Three-dimensional Anisotropic Electronic Properties of Solution Grown Organic Single Crystals Measured by Space-Charge Limited Current (SCLC)
Authors: Fraboni Beatrice , Fraleoni-Morgera Alessandro , Cavallini Anna
Published: June 2009

Organic single crystals offer the interesting and unique opportunity to investigate the intrinsic electrical behaviour of organic materials, excluding hopping phenomena due to grain boundaries and structural imperfections. Their structural asymmetry permits also to investigate the correlation between their three-dimensional order and their charge transport characteristics. Here we report on millimeter-sized, solution-grown organic single crystals, based on 4-hydroxycyanobenzene (4HCB), which exhibit three-dimensional anisotropic electrical properties along the three crystallographic axes a, b (constituting the main crystal flat face) and c (the crystal thickness), measured over several different samples. The carrier mobility was determined by means of space charge limited current (SCLC) and air-gap field effect transistors fabricated with 4HCB single crystals and the measured value well correlate with the structural packing anisotropy of the molecular crystal. A differential analysis of SCLC curves allowed to determine the distribution and the concentration of the dominant electrically active density of states within the gap.
Adsorption and Reaction Behaviors of Hf Precursor with Two Hydroxyls on Si(100): First Principles Study
Authors: Kim Dae-Hyun , Kim Dae-Hee , Hwa-Il Seo , Kim Ki-Young , Kim Yeong-Cheol
Published: June 2009

Density functional theory was used to investigate the adsorption and reaction of HfCl4 with two hydroxyls on Si (001)-2×1 surface in atomic layer deposition (ALD) process. When H2O molecules are adsorbed on Si (001) surface at room temperature, they are dissociated with hydrogens and hydroxyls. There are two dissociation pathways; inter-dimer dissociation and intra-dimer dissociation. The activation energies of these pathways can be converted to the reaction probabilities. It was approximately 2:1. We prepared a reasonable Si substrate which consisted of six inter-dimer dissociated H2O molecules and two intra-dimer dissociated H2O molecules. The HfCl4 must react with two hydroxyls to be a bulk-like structure. There were five reaction pathways where HfCl4 could react with two hydroxyls; inter-dimer, intra-dimer, cross-dimer, inter-row, and cross-row. Inter-row, inter-dimer and intra-dimer were relatively stable among the five reaction pathways based on the energy difference. The electron densities between O and Hf in these three reactions were higher than the others and they had shorter Hf-O and O-O bond lengths than the other two reaction pathways.
Structure and Luminescence of Europium-Doped Gadolinia-Based Core/Multi-Shell Scintillation Nanoparticles
Authors: Tseng Teng-Kuan , Choi Jihun , Holloway Paul H.
Published: June 2009

Scintillating nanoparticles with a SiO2 core and a Gd2O3 shell doped with Eu3+ were synthesized with a sol-gel process. Based on transmission electron microscopy (TEM) data, a ∼13 nm Gd2O3 shell was successfully coated onto ∼220 nm mono-dispersed SiO2 nanocores. Eu3+ ions at concentrations of nominally 5 at% exhibited photoluminescent (PL) emission from the SiO2/Gd2O3 nanoparticles after being calcined at 800 0C for 2 h. The SiO2 remained amorphous after calcining, while the Gd2O3 crystallized to a cubic structure. The PL emission was from the 5D0-7F2 transitions of Eu3+ at 609 and 622 nm. Photoluminescence excitation (PLE) data showed that emission from Eu3+ could result from direct excitation, but was dominated by the oxygen to europium charge-transfer band (CTB) between 250 and 280 nm for Eu3+ doped in Gd2O3. The quantum yield (QY) from thin films drop cast from a mixture of 20 mg of calcined nanoparticles in 500 μL of polymethylmethacrylate (PMMA) and excited in the CTB was 20% for SiO2/Gd2O3:Eu3+ core/shell scintillation nanoparticles. Finally, the above core/shell nanoparticles were passivated with a shell of SiO2 to create e.g. SiO2/Gd2O3:Eu3+/SiO2 nanoparticles. The QYs for this nanostructure were lower than unpassivated nanoparticles which was attributed to a weak CTB for the amorphous SiO2 shell and a higher density of interface quenching sites.
Raman scattering based strategies for quality control and process monitoring in electrodeposited CuIn(S,Se)2 solar cell technologies
Authors: Álvarez-García Jacobo , Fontané Xavier , Izquierdo-Roca Victor , Perez-Rodriguez Alejandro , Morante Joan Ramón , Saucedo Edgardo , Jaime-Ferrer Jesús Salvador , Bermúdez Verónica
Published: June 2009

This work reports the use of strategies based on Raman scattering for process monitoring of electrodeposited based S rich CuIn(S,Se)2 solar cells. Main vibrational modes in the Raman spectra are sensitive to features related to the crystalline quality, chemical composition and presence of secondary phases in the chalcopyrite layers, being all these features relevant for the optoelectronic properties of the final devices. Ex-situ and in-situ measurements during the electrochemical step allow the direct assessment on the formation of Se rich secondary phases which are related to the stoichiometry of the grown precursors. The analysis of the relative intensity of the spectral contribution from these phases allows early detection of deviations of precursor stoichiometry in relation to the optimum composition range in terms of solar cell efficiency. The applicability of the technique for the in-situ monitoring of the electrodeposition process is also discussed
Kinetic Studies of CdS Formation for a Better Understanding of Chemical Buffer Layer Deposition
Authors: Wilchelmi Krzysztof , Förster Diana , Neisser Axel , Schomäcker Reinhard
Published: June 2009

CdS is an important part of CIGS-based photovoltaics as a buffer layer between the absorber and the window layer. Chemical Bath Deposition (CBD) is the most common way of depositing CdS. Due to the nature of the CBD process CdS forms not only on the absorber layer surface but also in the bulk solution. In order to control the deposition of CdS at the surface and to avoidCdS formation in the bulk solution the kinetics of these reactions must be understood. In this work we study the formation of CdS in the chemical bath by using in situ spectroscopic extinction measurements. By monitoring the absorbance of the solution we are able to observe the bulk phase reaction (chemical formation of CdS in solution). Deposition of CdS (growth of the CdS layer at the surface) is investigated by measuring the CdS layer thickness after the reaction. The kinetics of both reactions were investigated by a systematic variation of temperature, initial reactant concentration, Reynold number as well as time. Finally the results of our study suggest a model of growth behaviour based on molecule-by-molecule deposition, which explains especially the dependency on temperature and hydrodynamics.
Solar Grade CuInS2 Thin Films Grown at 250°C
Authors: Painchaud Thomas , Barreau Nicolas , Kessler John
Published: June 2009

CuInS2 (chalcopyrite structure) thin films were synthesized at 250°C using a two-stage process consisting firstly in the co-evaporation of a large grain In2S3 (defect spinel structure) precursor layer followed by the addition of copper and sulfur. The crystalline properties of the resulting films are similar to those leading to high efficiency solar cells. An energy conversion efficiency of 6.7% has been attained with a 1.5 μm thick CuInS2 layer and a standard CdS buffer layer/ZnO window structure. Improved performances can be expected through the growth of thicker absorbers.
Direct and Indirect Effects of Filling on Electronic Structure of Skutterudites
Authors: Wee Daehyun , Kozinsky Boris , Marco Fornari , Marzari Nicola
Published: June 2009

We perform ab-initio computations to investigate the family of CoSb3 skutterudites in an attempt to develop deeper understanding of the effect of fillers. Primary focus is on Ba-filled CoSb3 systems, while Ca and Sr-filled systems are also compared for checking consistency. We analyze both global and local structural effects of filling. We show the specific deformation of Sb network introduced by the filler. Such a deformation is localized around the filler site since soft Sb rings accommodate the distortion. Rearrangement of Sb atoms affects the band structures, and we perform additional analysis to clarify the effect of volume on the band gap. Phonon dispersions are briefly discussed, and filler-dominated vibrations are identified. These modes form the first optical modes at Γ. They manifest themselves in phonon dispersion curves as flat lines, showing that they are localized, while filler vibration is strongly coupled with nearby Sb atoms.
The Effect on Thermoelectric Properties of Cd Substitution in PbTe
Authors: Ahn Kyunghan , Han Mi-Kyung , Vermeulen Derek , Moses Steven , Uher Ctirad , Kanatzidis Mercouri
Published: June 2009

A recent theoretical study suggested that the substitution of Cd in PbTe can result in a distortion in the electronic density of states (DOS) near the bottom of the conduction band in PbTe. In this study we explored the effect of Cd doping on the thermoelectric properties of PbTe in an effort to test the theoretical prediction that DOS distortion can increase the Seebeck coefficient. We present detailed investigation of structural and spectroscopic data, transmission electron microscopy, as well as transport properties of samples of PbI2 doped PbTe-x% CdTe (x = 1, 3, 5, 7, 10). All samples follow the Pisarenko relationship and no enhancement of the Seebeck coefficient was observed due to DOS distortions. A low lattice thermal conductivity was achieved by nanostructuring observed via high resolution transmission electron microscopy. A maximum ZT of ˜1.2 at ˜720 K was achieved for the 1% CdTe sample.
Effect of Modified Titanium Dioxide on Rheological Behavior of Dental Porcelain Slurries for Rapid Prototyping Applications
Authors: Zhu Dongbin , Xu Anping , Qu Yunxia , Liang Jinsheng
Published: June 2009

This study investigates bactericidal activities of dental porcelain contained silver/cerium/titania against streptococcus mutans in different irradiations, then the effect of modified titanium dioxide on rheological behavior of dental porcelain slurries is studied for rapid prototyping applications. The results show that the silver/cerium/titania has much higher antibacterial efficiency than that of pure TiO2 either in the room light or under the dark. It is potential to apply this photocatalyst in the dental materials for preventing human teeth from caries because the oral cavity is mostly under dark, partly in the visible light. The modified titanium dioxide not only has a antibacterial effect, but also can improve the rheological behavior of dental porcelain slurries for rapid prototyping applications.
Lateral Heat Spreading in Layered Samples
Authors: Fournier Daniele , Fretigny Christian , Busson Mikaël , Saïdi Elika , Aigouy Lionel , Roger Jean Paul , Bergeal Nicolas , Lesueur Jérôme
Published: June 2009

We describe two techniques dedicated to observe and study the heating of structured materials like micro and nanowires and multilayered compounds. The techniques are thermally modulated fluorescence and thermoreflectance. Thermally modulated fluorescence allows mapping the heating of devices with a sub-wavelength lateral resolution. Thermoreflectance allows deeper physical investigations and can be directly used to determine the thermal conductivity and diffusivity of layered structures. In particular, we will show that by thermally modulating a surface by a point-like source, we are able to determine such quantities for several geometries, taking into account the nature of the substrate (conductive or not) as well as the interface quality between the layers. The experimental results, measured on aluminum thin films of variable thickness and on vanadium dioxide layers are corroborated by an analytical model that analyzes both the amplitude and the phase of the lateral heat diffusion in the structure
Integration of VO2 Thin Films on Si(100) for Thermal Switching Devices Applications
Authors: Gupta Alok , Aggarwal Ravi , Narayan Jagdish
Published: June 2009

Thin films of vanadium dioxide (VO2) exhibit an interesting semiconductor to metal transition (SMT) when heated above ˜680C in which its resistivity changes by 3-4 orders of magnitude and its transmittance for IR wavelengths drops drastically. Integration of these thin films with Si (100) substrate is of immense technological importance due to its potential applications in sensor and memory based devices. Using pulsed laser deposition (PLD) we have demonstrated in this study that thin films of VO2 can be grown epitaxially on Si (100) substrate using an intermediate tetragonal Yttrium-Stabilized Zirconia (YSZ) layer without any further annealing. X-ray diffraction (XRD) and cross-section transmission electron microscopy studies were performed on the films and they are found to be of highly epitaxial nature. Electrical resistivity measurement were carried out using the four-point probe method and SMT parameters were extracted using Gaussian fit of the data. The S-M transition parameters are in close proximity with parameters obtained from vanadium oxide films deposited on oxide based substrates such as Al2O3 or TiO2.
Quantitative Investigation of the Factors Affecting the Hydrothermal Growth of Zinc Oxide Nanowires
Authors: Rachamim Aron Robert , Dalal Sharvari H. , Pfaendler Sieglinde M.-L. , Swanwick Michael E. , Flewitt Andrew , Milne William I.
Published: June 2009

Zinc oxide (ZnO) nanowires (NWs) are receiving significant industrial and academic attention for a variety of novel electronic, optoelectronic and MEMS device applications due to their unusual combination of physical properties, including being optically transparent, semiconducting and piezoelectric. Hydrothermal growth is possible at significantly lower temperatures (and hence lower thermal budgets) compared with other NW growth methods, such as chemical vapour deposition. In this context, the hydrothermal growth of ZnO NWs on seeded substrates immersed in equimolar zinc nitrate/HMTA aqueous solution was investigated. NWs were grown on polished silicon (001) substrates, and the solution concentrations, temperatures and growth times were varied. Importantly, the NW diameter was found to depend only on concentration during hydrothermal growth for times up to 4 hours. The average diameter was 14 nm in 0.005 M solution and increased up to a maximum 150 nm at 0.07 M, when the NWs formed a continuous polycrystalline film. Concentration and temperature were all found to affect the axial growth rate of NWs in the [0001] direction. The growth rate was constant up to 4 hours (200 nm hr-1) for constant conditions (81 oC, 0.025 M). The growth rate was found to increase approximately linearly with concentration at a rate of 7840 nm M-1 hr-1 up to 0.06 M (81 oC solution). The growth rate also increased linearly with temperature at a rate of 4.9 nm hr-1 K-1 (0.025 M solution). This indicates that growth takes place close to the equilibrium point, found by linear regression to be 36 oC for 0.025 M solution.
High-throughput top-down and bottom-up processes for forming single-nanotube based architectures for 3D electronics
Authors: Kaul Anupama B , Megerian Krikor G. , Allmen Paul von , Kowalczyk Robert , Baron Richard
Published: June 2009

We have developed manufacturable approaches to form single, vertically aligned carbon nanotubes, where the tubes are centered precisely, and placed within a few hundred nm of 1-1.5 m deep trenches. These wafer-scale approaches were enabled by chemically amplified resists and inductively coupled Cryo-etchers for forming the 3D nanoscale architectures. The tube growth was performed using dc plasma-enhanced chemical vapor deposition (PECVD), and the materials used for the pre-fabricated 3D architectures were chemically and structurally compatible with the high temperature (700 °C) PECVD synthesis of our tubes, in an ammonia and acetylene ambient. Tube characteristics were also engineered to some extent, by adjusting growth parameters, such as Ni catalyst thickness, pressure and plasma power during growth. Such scalable, high throughput top-down fabrication techniques, combined with bottom-up tube synthesis, should accelerate the development of PECVD tubes for applications such as interconnects, nano-electromechanical (NEMS), sensors or 3D electronics in general.
Composites of silver nanoparticles and poly(vinylidene fluoride-trifluoroethylene)copolymer: Preparation as well as structural and electrical characterization
Authors: Wegener Michael , Greco Tonino
Published: June 2009

Composites comprising of polymers and metal nanoparticles are of great interest in regard to electronic and opto-electronic applications. The preparation of such nanocomposites with homogenously dispersed particles usually cannot be solved by mixing the polymer and the desired isolated colloids due to strong agglomeration tendency of the metallic nanoparticles. Consequently, nanocomposites with colloids have been prepared by synthesis of the inorganic particles in situ, for instance in solution, and then mixed with the polymer solution.

Extensive attention has been given to the study of the plasmonic properties of noble metal nanoparticles as a result of their potential application as waveguides, photonic circuits, and sensors [1]. Surface plasmon polaritons are excited when electromagnetic radiation causes coherent oscillations of the conducting electrons of noble metal nanoparticles such as gold, silver or copper. The selective photon absorption and scattering allow the monitoring of the optical properties of the nanoparticles by conventional spectroscopic methods like UV-vis spectroscopy. Previous investigations show that the surface plasmon resonance frequency is extremely sensitive to the size, shape, and the surrounding dielectric environment of the nanoparticles [2].

In order to obtain multifunctional composites electro-active polymers (EAP) can be chosen as matrix materials. EAPs such as polyvinylidene fluoride (PVDF) and its copolymer with trifluoroethylene (P(VDF-TrFE)) show a ferroelectric polarization accompanied with piezo- and pyroelectric properties. Both polymers are suitable for composite preparation as earlier studies have shown, e.g. performed on ceramic-polymer composites in order to optimize their piezo- and pyroelectric properties and to adjust their dielectric properties, respectively. Recently, PVDF with embedded metallic nanoparticles was studied regarding the kinetics of film preparation, dispersion and resulting properties [3].

In this work, the influence of homogenously dispersed silver-nanoparticles in electro-active polymers such as PVDF and P(VDF-TrFE) has been investigated over a broad range of mass fractions of silver. For low silver nanoparticle content (up to 3wt.%) the surface plasmon polariton resonance peak can be observed in the blue spectral region. From the infrared spectra it is concluded that no significant degradation of the polymers occurs. Higher silver amounts cause the formation of fractal-like agglomerates. Thus, a high extinction cross section in the visible and infrared spectral range is found. Furthermore, the influence of the silver mass fraction to the thermal, electrical and dielectric properties of the nanocomposites is discussed in detail.

[1] S. A. Maier, H. A. Atwater, J. Appl. Phys. 2005, 98, 011101-10. [2] J. J. Mock, et al, J. Chem. Phys. 2002, 116, 6755-6759.[3] J. Compton, et al, Makromol. Symp. 2007, 247, 182-189.
On the defect induced ferromagnetic ordering above room-temperature in undoped and Mn doped ZnO thin films
Authors: Kapilashrami Mukes , Xu Jun , Ström Valter , Rao K V , Belova Lyubov
Published: June 2009

Evidence for long range ferromagnetic order above room-temperature, RTFM, in pristine ZnO, In2O3, TiO2 nanoparticles and thin films, containing no nominal magnetic elements have been reported recently. This could question the origin of RTFM in doped dilute alloys if for example the ZnO matrix itself develops a defect induced magnetic order with a significant moment per unit cell. In this presentation we report a systematic study of the film thickness dependence of RTFM in pure ZnO deposited by DC Magnetron Sputtering. We observe a maximum in the saturation magnetization, MS, value of 0.62 emu/g (0,018 μB/unit cell), for a ˜480 nm film deposited in an oxygen ambience of appropriate pressure. Above a thickness of around 1 μm the films are diamagnetic as expected. We thus see a sequential transition from ferromagnetism to para- and eventual diamagnetism as a function of film thickness in ZnO. We also find that in such a ZnO matrix with a maximum intrinsic defect induced moment, on doping with Mn the maximum enhanced MS value of 0.78 emu/g is obtained for 1at.% Mn doping. With this approach of appropriate doping in a defect tailored matrix, we routinely obtain RTFM in both undoped and Mn- doped ZnO thin films.
Four Stable Magnetization States Formed in the Single Layer of GaMnAs Ferromagnetic Film
Authors: Lee Sanghoon , Liu X. , Furdyna J. K.
Published: June 2009

A GaMnAs ferromagnetic semiconductor film under compressive strain has strong biaxial in-plane anisotropy, which generates four stable magnetization directions at a zero magnetic field. This feature results in a double switching behavior in the main loop of planar Hall resistance (PHR) spectrum. The minor scan of PHR measurement exhibited staggered asymmetric loops due to the formation of the stable muti-domain structures. We demonstrated the observed four stable PHR states can be served as quaternary logic states for spin memory device.
Electronic Structure and Magnetic Properties of Ti-doped ZnO
Authors: Lardjane Soumia , Merad Ghouti , Faraoun Houda Imane
Published: June 2009

Recent experiments suggest that Ti doped ZnO can be a promising room temperature dilute magnetic semiconductor (DMS) and a potentially useful material for spintronic devices. Furthermore, the fact that Ti doped ZnO shows ferromagnetic behaviour despite it contains no magnetic element makes this system good candidate for theoretical investigation regarding the controversies about the origin of ferromagnetic ordering in TM-doped ZnO. In this work, the density functional theory (DFT) is used to calculate the electronic and magnetic structures of Ti-doped ZnO. The obtained results are used to discuss the origin of the ferromagnetism, and the contribution of different atoms in the magnetic moment.
Multifunctional Cellular Materials
Authors: De Gliniasty Michel , Bouchet Régis
Published: June 2009

In many industrial fields, structural materials play a key role in the increase of performance, but new requirements in terms of energy saving, safety, materials economy… lead to more stringent requirements on materials properties.
The two usual strategies –microstructure optimisation and shape optimisation-, which act at two different scales, the micrometer scale and above the centimetre scale, become less and less efficient with this new strong demand for multi-functional properties. The largely unexplored millimetre scale, domain of the so called “structural materials”, is a possible answer. Structural materials benefit of an extra degree of freedom well suited for multi-functionality: they allow using combination of materials from different classes, allow geometrical optimisation, and can be naturally integrated in structures such as sandwiches and various stiffened plate geometries.
The price to pay for this extra-richness is the extraordinary wide variety of potential solutions to investigate for a given problem. Hence modelling plays a crucial role for selecting and optimising such innovative materials.
This paper is an overview of a project, named MAPO (“Materiaux Poreux”), aiming at designing high-temperature materials with acoustical and structural properties.
Caracterización florística de ambientes de la cuenca baja del Río Cucurital, afluente del Río Caroní, Estado Bolívar, Guayana Venezolana
Authors: Rodríguez Leyda , Colonnello Giuseppe
Published: June 2009

Como una contribución al conocimiento florístico de la cuenca del Río Caroní se realizaron colecciones botánicas en varios ambientes de la cuenca baja del Río Cucurital, que incluyen formaciones boscosas, tanto en penillanura como ribereñas, morichales, sabanas, arbustales y ambientes perturbados; en los bosques se hicieron colecciones en parcelas de 0,1 ha y fuera de ellas. De manera general, las familias con mayor cantidad de especies fueron Melastomataceae (46), Rubiaceae (33), Euphorbiaceae (23), Cyperaceae (19), Myrtaceae (18), Fabaceae (18), Clusiaceae (15), Arecaceae (15), Caesalpiniaceae (14), Chrysobalanaceae (14), Lauraceae (14), Poaceae (13) y Burseraceae (12), siendo las más representativas de la cuenca baja. Los géneros con mayor cantidad de especies fueron Miconia (17), Psychotria (13), Ocotea (10), Myrcia (8), Protium (7), Licania (7) y Rhynchospora (7). Melastomataceae y Rubiaceae predominaron en todos los ambientes con excepción de la sabana; Lauraceae, Burseraceae, Arecaceae, Chrysobalanaceae y Euphorbiaceae fueron las de mayor importancia en los bosques, y Myrtaceae y Cyperaceae en los bosques ribereños, esta última junto con las Poaceae predominaron en morichal y sabana. Se encontraron 19 especies restringidas a la Guayana venezolana, de las cuales 12 se conocen sólo del estado Bolívar, evidenciando que las condiciones ecológicas, topográficas y edáficas determinan la presencia de elementos florísticos particulares. Las actividades humanas son escasas, lo que se ha reflejado en poca alteración de las comunidades vegetales y en el mantenimiento del carácter prístino de los ambientes. Los escasos ambientes intervenidos han sido colonizados por especies herbáceas y arbustivas típicas de la región.
The spatial distribution of Aedes aegypti and Aedes albopictus in a transition zone, Rio de Janeiro, Brazil
Authors: Honório Nildimar Alves , Castro Márcia Gonçalves , Barros Fábio Saito Monteiro de , Magalhães Mônica de Avelar Figueiredo Mafra , Sabroza Paulo Chagastelles
Published: June 2009

Dengue fever has become the most important vector-borne viral disease in Brazil. Human facilitated transport of desiccation-resistant eggs has led to its two most important vectors, Aedes aegypti and Ae. albopictus, becoming widespread. In this paper, we report seasonal and spatial variation in larval abundances of Ae. aegypti and Ae. albopictus across a small-scale transition zone between an urban area and an urban wooded/forested area within Rio de Janeiro, Brazil. We installed 400 ovitraps across 10 sites with different human population densities and vegetation coverage. Eggs and larvae were collected for three weeks during the wet and dry seasons of 2002 and 2003. Ae. albopictus was predominantly found in the forested areas of the study site whereas in the urbanized area Ae. aegypti was more abundant. Both species peaked during the wet season. This distribution pattern, which may reflect adult flight range, may favor the co-occurrence of larvae of these species in a small-scale urban/urban forest transition zone.
Barebacking e a possibilidade de soroconversão
Authors: Silva Luís Augusto Vasconcelos da
Published: June 2009

Este artigo discute a produção de sentidos sobre a possibilidade de soroconversão nas práticas de barebacking, bem como a dinâmica do bug chasing e suas ambigüidades no contexto brasileiro. Nessa perspectiva, algumas justificativas para a realização do barebacking, de modo geral definido como o sexo anal desprotegido entre homens que fazem sexo com homens de forma intencional, serão focalizadas. Durante a minha trajetória de pesquisa, foram acompanhadas algumas comunidades e fóruns de discussão no Orkut sobre o barebacking, como também desenvolvidas entrevistas online, abertas, no MSN, com barebackers oriundos de distintos estados do país, principalmente de São Paulo e Rio de Janeiro, Brasil. A busca pela soroconversão também esteve presente nos contextos de interação online do cenário brasileiro, embora haja muito mais uma multiplicidade de interesses e modalidades de barebacking entre os diversos interlocutores online. Como será discutido neste artigo, mais do que adquirir o HIV, existe uma preocupação excessiva por acumular ou intensificar sensações.
Rational emotive behavior therapy: applications for working with parents and teachers
Authors: Terjesen Mark D. , Kurasaki Robyn
Published: June 2009

Given the high rates of reported emotional stress among parents and teachers, the Rational Emotive Behavior Therapy approach appears to be a useful strategy to promote more effective parent and teacher emotional functioning and increase child positive behaviors and learning. The Rational Emotive Behavior Therapy model may be helpful for clinicians who work with the parents and the family by identifying and subsequently changing their unhealthy ideas, enhancing emotional functioning, and increasing their ability to make effective behavior management decisions. In addition, those who work with educators in a school-based setting may wish to consider implementing Rational Emotive Behavior Therapy methodology in their consultative and therapeutic interventions. Given the data that links stress to unhealthy beliefs among educators, Rational Emotive Behavior Therapy may be an effective tool that warrants further application.