bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Electrical Properties, Piezoresistivity and Noise of poly-SiGe for MEMS-above-CMOS applications
Authors: Gonzalez Pilar , Lenci Silvia , Haspeslagh Luc , De Meyer Kristin , Witvrouw Ann
Published: June 2009

In this work, the electrical properties of heavily doped poly-SiGe deposited at temperatures compatible with MEMS integration on top of standard CMOS are reported. The properties studied are resistivity, temperature coefficient of resistance, noise, piezoresistivity, Hall mobility and effective carrier concentration. The obtained results prove the potential of using poly-SiGe as a sensing layer for MEMS-above-CMOS applications.
Electronic Detection and Quantification of ions in solution using an a-Si:H Field-effect Device
Authors: Costa João , Fernandes Miguel , Vieira Manuela , Lavareda G. , Carvalho C. N. , Karmali Amin
Published: June 2009

Progress in microelectronics and semiconductor technology has enable new capabilities in the field of sensor construction, particularly of pH sensors based on field-effect transistors (FETs) as transducers of chemical signal. While crystalline devices present a higher sensitivity, their amorphous counterpart present a much lower fabrication cost, thus enabling the production of cheap disposable sensors for use in the food industry. Interest in biosensors consisting of a semiconductor transducer and a functionalized surface with biomolecule receptors (BioFET) continues to grow as they hold the promise for highly selective, label-free, real-time sensing as an alternative to conventional optical detection techniques.
We have been involved in the development of a biosensor where the enzymatic activity of recombinant amidase from Escherichia coli is coupled to a semiconductor transducer for the detection of toxic amides in food and industrial effluents. The devices were fabricated on glass substrates by the PECVD technique in the top gate configuration, where the metallic gate is replaced by an electrolytic solution with an immersed Ag/AgCl reference electrode. Silicon nitride is used as gate dielectric enhancing the sensitivity and passivation layer used to avoid leakage and electrochemical reactions. In this article we report on the semiconductor unit, showing that the sensor displays the desired current-voltage characteristics. In addition we present an electrical model of the device, in agreement with the experimental data, that is sensitive to the pH of the solution.
Effects of electro-mechanical stressing on the electrical characterization of on-plastic a-Si:H thin film transistors
Authors: Chen Jian Z. , Chih-Yong Yeh , Chiu I-Chung , Cheng I-Chun , Huang Jung-Jie , Chen Yung-Pei
Published: June 2009

We analyzed the effect of electromechanical stressing on the electrical characteristics of hydrogenated amorphous silicon thin-film transistors. It had been shown that the TFTs, fabricated at 150 °C, respond to tension/compression by a rise/fall in electron mobility. In TFTs fabricated using the same process, a slight shift of threshold voltage was observed under prolonged high compressive strain and the gate leakage current slightly increases after ˜2% compressive strain. In general, the change of TFT performance due to pure mechanical straining is small in comparison to electrical gate-bias stressing. From the comparison among Maxwell stress (induced by electrical gate-bias stressing), mechanical stress (applied by bending), and drifting electrical force for passivated hydrogen atom, the most significant cause for the change of electrical characterization of a-Si:H TFTs should be the trapping charges inside the dielectric, under combined electrical and mechanical stressing. The mechanical stress does not act on Si-H bonds to drift hydrogen atoms, while it is mainly balanced by the rigid Si-Si networks in a-Si:H or a-SiNx. Therefore, mechanical stress has very little effect on the instability of low temperature processed a-Si:H TFTs.
Thin Film Silicon Solar Cells on Transparent Plastic Substrates
Authors: Fathi Ehsanollah , Sazonov Andrei
Published: June 2009

In this work, we optimized different thin film silicon layers in a single junction p-i-n solar cell at deposition temperature of 150 °C. Using the optimized doped and undoped layers, 0.5 cm2 test cells fabricated both on glass and polyethylene naphthalate (PEN) substrates. The cells show identical open circuit voltages and fill factors, whereas the short circuit current and consequently the efficiency of the cell fabricated on glass is higher than the efficiency of 3.99% of the cell fabricated on PEN substrate.
Comparative Study of MVHF and RF Deposited Large Area Multi-junction Solar Cells Incorporating Hydrogenated Nano-Crystalline Silicon
Authors: Xu Xixiang , Li Yang , Ehlert Scott , Su Tining , Beglau Dave , Bobela David , Yue Guozhen , Yan Baojie , Zhang Jinyan , Banerjee Arindam , Yang Jeff , Guha Subhendu
Published: June 2009

We report our investigations of large area multi-junction solar cells based on hydrogenated nano-crystalline silicon (nc-Si:H). We compared results from cells deposited by RF (13.56 MHz) at lower deposition rate (˜3 Å/s) and by Modified Very High Frequency (MVHF) at higher rate (≥ 10 Å/s). With optimized process conditions and cell structures, we have obtained ˜12% initial small active-area (˜0.25 cm2) efficiency for both RF and MVHF cells and 10˜11% large aperture-area (˜400 cm2) encapsulated MVHF cell efficiency for both a-Si:H/nc-Si:H double-junction and a-Si:H/nc-Si:H/nc-Si:H triple-junction structures on Ag/ZnO coated stainless steel substrate.
Low Temperature Direct Cu-Cu Immersion Bonding for 3D Integration
Authors: Agarwal Rahul , Ruythooren Wouter
Published: June 2009

High yielding and high strength Cu-Cu thermo-compression bonds have been obtained at temperatures as low as 175°C. Plated Cu bumps are used for bonding, without any surface planarization step or plasma treatment, and bonding is performed at atmospheric condition. In this work the 25μm diameter bumps are used at a bump pitch of 100μm and 40μm. Low temperature bonding is achieved by using immersion bonding in citric acid. Citric acid provides in-situ cleaning of the Cu surface during the bonding process. The daisy chain electrical bonding yield ranges from 84%-100% depending on the bonding temperature and pressure.
Development of X-ray, Gamma Ray Spectroscopic Detector Using Epitaxially Grown Single Crystal Thick CdTe Films
Authors: Niraula Madan
Published: June 2009

In this paper, we review our efforts in the spectroscopic detector development using epitaxially grown thick single crystal films of CdTe. The films were grown on GaAs and Si substrates using metalorganic vapor phase epitaxy growth technique. High crystalline quality thick single crystal CdTe films (>260 μm) were obtained where the growth rates could be varied from 10 to 70 μm/h by adjusting the precursor's flow rates, ratios and the substrate temperatures. Spectroscopic detectors were fabricated in a p-CdTe/n-CdTe/n+-GaAs or p-CdTe/n-CdTe/n+-Si heterojunction diode structure. Both types of detector were capable of detecting and resolving energy peaks from a gamma ray source. However, the spectroscopic performance of p-CdTe/n-CdTe/n+-Si detectors was better than that of the p-CdTe/n-CdTe/n+-GaAs detectors. Details on the growth characteristics, detector fabrication and the detector performance are reported. Furthermore, current challenges in this detector fabrication technique are discussed.
Modeling the Crystal Growth of Cadmium Zinc Telluride: Accomplishments and Future Challenges
Authors: Derby Jeffrey , Gasperino David , Zhang Nan , Yeckel Andrew
Published: June 2009

The availability of large, single crystals of cadmium zinc telluride (CZT) with uniform properties would lead to improved performance of gamma radiation detectors fabricated from them. However, even though CZT crystals are the central element of these systems, there remains relatively little fundamental understanding about how these crystals grow and, especially, how crystal growth conditions affect the properties of grown crystals. This paper discusses the many challenges of growing better CZT crystals and how modeling may favorably impact these challenges. Our thesis is that crystal growth modeling is a powerful tool to complement experiments and characterization. It provides an important approach to close the loop between materials discovery, device research, systems performance, and producibility. Specifically, we discuss our efforts to model gradient freeze furnaces used to grow large CZT crystals at Pacific Northwest National Laboratories and Washington State University. Model results are compared with experimental measurements, and the insight gained from modeling is discussed.
Characterizing the effects of silver alloying in chalcopyrite CIGS with junction capacitance methods
Authors: Erslev Peter , Hanket Gregory M. , Shafarman William N. , Cohen David J.
Published: June 2009

A variety of junction capacitance-based characterization methods were used to investigate alloys of Ag into Cu(In1-xGax)Se2 photovoltaic solar cells over a broad range of compositions. Alloys show encouraging trends of increasing VOC with increasing Ag content, opening the possibility of wide-gap cells for use in tandem device applications. Drive level capacitance profiling (DLCP) has shown very low free carrier concentrations for all Ag-alloyed devices, in some cases less than 1014 cm−3, which is roughly an order of magnitude lower than that of CIGS devices. Transient photocapacitance spectroscopy has revealed very steep Urbach edges, with energies between 10 meV and 20 meV, in the Ag-alloyed samples. This is in general lower than the Urbach edges measured for standard CIGS samples and suggests a significantly lower degree of structural disorder.
Theory of Recombination in Non-Crystalline Junctions
Authors: Nardone Marco , Karpov Victor G. , Shvydka Diana
Published: June 2009

A theory of non-crystalline recombination junctions is developed and compared to the experimental data. Junction transport is represented as hopping in both real and energy spaces, dominated by rare yet exponentially effective optimum channels having favorable configurations of localized states. Our work correlates the current-voltage characteristics of non-crystalline devices with material parameters and predicts large non-ideality factors increasing under light, and possible variations between nominally identical devices.
High Temperature Thermoelectric Properties of Nano-Bulk Silicon and Silicon Germanium
Authors: Bux Sabah , Fleurial Jean-Pierre , Blair Richard G. , Gogna Pawan K. , Caillat Thierry , Kaner Richard B
Published: June 2009

Point defect scattering via the formation of solid solutions to reduce the lattice thermal conductivity has been an effective method for increasing ZT in state-of-the-art thermoelectric materials such as Si-Ge, Bi2Te3-Sb2Te3 and PbTe-SnTe. However, increases in ZT are limited by a concurrent decrease in charge carrier mobility values. The search for effective methods for decoupling electronic and thermal transport led to the study of low dimensional thin film and wire structures, in particular because scattering rates for phonons and electrons can be better independently controlled. While promising results have been achieved on several material systems, integration of low dimensional structures into practical power generation devices that need to operate across large temperature differential is extremely challenging. We present achieving similar effects on the bulk scale via high pressure sintering of doped and undoped Si and Si-Ge nanoparticles. The nanoparticles are prepared via techniques that include high energy ball milling of the pure elements. The nanostructure of the materials is confirmed by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Thermal conductivity measurements on the densified pellets show a drastic 90% reduction in the lattice contribution at room temperature when compared to doped single crystal Si. Additionally, Hall effect measurements show a much more limited degradation in the carrier mobility. The combination of low thermal conductivity and high power factor in heavily doped n-type nanostructured bulk Si leads to an unprecedented increase in ZT at 1275 K by a factor of 3.5 over that of single crystalline samples. Experimental results on both n-type and p-type Si are discussed in terms of the impact of the size distribution of the nanoparticles, doping impurities and nanoparticle synthesis processes.
Syntheses of Ni-doped and Fe-doped CoSb3 Thermoelectric Nanoparticles through Modified Polyol Process
Authors: Itoh Takashi , Isogai Keisuke
Published: June 2009

Skutterudite CoSb3 compounds are of increasing interest as materials with good thermoelectric performance over the temperature range of 600 to 800 K, but the thermal conductivity of the materials is relatively high. Nanostructured materials have been shown to enhance phonon scattering and lower the thermal conductivity of the thermoelectric materials. Partial substitution of Ni or Fe on the Co site of CoSb3 is a hopeful route for improving thermoelectric performance of the CoSb3 compounds. In the present work, synthesis of Ni-doped and Fe-doped CoSb3 nanoparticles through the modified polyol process was attempted and the optimum synthesizing condition was investigated. Co(OOCH3)2·4H2O, Ni(OOCH3)2·4H2O, FeCl3·6H2O and SbCl3, were prepared as precursors. The precursors were reduced by NaBH4 in tetraethyleneglycol at 513 K in an argon atmosphere, for different reaction times (holding times). The reaction products were characterized by the X-ray diffraction, the energy dispersive X-ray spectroscopy, and transmission electron microscopy. The nanoparticles with about 20 to 30 nm in size mainly existed in the reaction products regardless of the chemical composition and the reaction time. The skutterudite phase was identified as a main phase in the sample synthesized for long reaction time, but the other phases of Sb and MSb2 (M=Co, Ni, Fe) were also detected. The lattice parameter of the synthesized skutterudite phase linearly increased with increasing the doping agent concentration, following Vegard’s law.
Output Power Characteristics of Mg2Si and the Fabrication of a Mg2Si TE Module with a Unileg Structure
Authors: Nemoto Takashi , Iida Tsutomu , Oguni Yohei , Sato Junichi , Matsumoto Atsunobu , Sakamoto Tatsuya , Miyata Takahiro , Nakajima Tadao , Taguchi Hirohisa , Nishio Keishi , Takanashi Yoshifumi
Published: June 2009

In order to restrain global warming and to realize a sustainable global energy system, further enhancements in energy efficiency are required. One reliable technology for reducing greenhouse gas emissions and the consumption of fossil fuel is thermoelectric technology, which can directly convert heat into electricity and consequently increases the energy conversion efficiency of power generation by combustion. Magnesium silicide (Mg2Si) is a promising candidate for a thermal-to-electric energy-conversion material at operating temperatures ranging from 500 to 800 K. Mg2Si exhibits many promising characteristics, such as the abundance of its constituent elements in the earth’s crust and the non-toxicity of its processing by-products, resulting in freedom from concerns regarding prospective extended restrictions on hazardous substances.
The efficiency of a thermoelectric device is characterized by the dimensionless figure of merit, ZT. It is well known that several kinds of dopants are effective in improving the thermoelectric performance of n-type Mg2Si. With Bi-doped n-type Mg2Si, we have achieved a maximum value of the dimensionless figure-of-merit ZT of ˜1.0 at ˜ 850 K. However, the correlation between the ZT values and the power generation characteristics, which is essential to understand in order to design a structure for a TE power generation module, has not been sufficiently investigated. In order to design a structure for a thermoelectric module using Mg2Si, we examined the correlation between the ZT values and the power-output of a single element using Mg2Si (ZT = 0.6) and Mg2Si doped with donor impurities such as Al and/or Bi (ZT = 0.65˜0.77). The measured single element was 2×2 mm2 in section and 10 mm long. Additionally, we developed and evaluated a new architecture based on a ‘unileg’ structure Mg2Si TE power generation module, which can improve the module lifetime and simplify its manufacture. As a starting material for the fabrication of the single element and the TE modules, pre-synthesized polycrystalline Mg2Si, fabricated by UNION MATERIAL was used. The material was sintered using a plasma-activated sintering (PAS) technique, and, at the same time, Ni electrodes were formed on the Mg2Si by employing of a monobloc PAS technique. The thermoelectric power-outputs were measured under a temperature difference, ΔT, ranging from 100-to-500 K by using UNION MATERIAL UMTE-1000M.
The observed power-output for single element of Mg2Si (ZT = 0.6), 2 at % Bi-doped Mg2Si (ZT = 0.65) and 1at % Bi + 1at % Al-doped Mg2Si (ZT = 0.77) were 23.2 mW, 13.6 mW and 19.4 mW respectively at ΔT = 500 K (between 873 K and 373 K). For the new architecture based on the unileg structure thermoelectric module, the observed value for power-output-per-unit-area was 12 mW/mm2 at ΔT = 500 K.
Enhanced thermoelectric properties in PbTe Nanocomposites
Authors: Kirby Hillary , Martin Joshua , Datta Anuja , Chen Lidong , Nolas George S.
Published: June 2009

Dimensional nanocomposites of PbTe with varying carrier concentrations were prepared from undoped and Ag doped PbTe nanocrystals synthesized utilizing an alkaline aqueous solution-phase reaction. The nanocrystals were densified by Spark Plasma Sintering (SPS) for room temperature resistivity, Hall, Seebeck coefficient, and temperature dependent thermal conductivity measurements. The nanocomposites show an enhancement in the thermoelectric properties compared to bulk PbTe with similar carrier concentrations, thus demonstrating a promising approach for enhanced thermoelectric performance.
Fabrication of Nano-Sized Tin Oxide Powder by Spray Pyrolysis Process
Authors: Yu Jaekeun , Kim Jwayeon , Han Jeoungsu
Published: June 2009

By using tin chloride solution as the raw material, a nano-sized tin oxide powder with average particle size below 50 nm is generated by spray pyrolysis reaction. This study also examines the influences of the reaction parameters such as reaction temperature and the concentration of raw material solution on the powder properties. As the reaction temperature increases from 800 to 850 ℃, the average particle size of the generated powder increases from 20 nm to 30 nm. As the reaction temperature reaches 900 ℃, the droplets are composed of nano-particles with average size of 30 nm, while the average size of individual particles increases remarkably up to 80˜100 nm. When the tin concentration reaches 75 g/L, the average particle size of the powder is below 20 nm. When the tin concentration reaches 150 g/L, the droplets are composed of nano particles with average size around 30 nm, whereas the average size of independent particles increases up to 80˜100 nm. When the concentration reaches 400 g/L, the droplets are composed of nano-particles with average size of 30 nm.
Ferromagnetism and Near-infrared Luminescence in Neodymium and Erbium Doped Gallium Nitride via Diffusion
Authors: Luen Melvyn Oliver , Nepal Neeraj , Frajtag Pavel , Zavada John , Brown Ei , Hommerich Uwe , Bedair Salah M. , El-Masry Nadia
Published: June 2009

In this study, we report on the diffusion of neodymium (Nd) and erbium (Er) into n-type and undoped GaN and subsequent measurements of the room-temperature (RT) magnetic and optical properties. The diffusion profile has been measured via secondary ion mass spectroscopy (SIMS) with rare-earth (RE) concentration yields of up to 1×1018/cm3. The ferromagnetic properties were measured using an alternating gradient magnetometer (AGM) giving a saturation magnetization (Ms) of up to 3.17emu/cm3 for the RE-diffused layer. The photoluminescence (PL) emission of the Nd-diffused and Er-diffused GaN is observable in the near-infrared (NIR) and infrared (IR) regions of the spectrum, respectively. The Nd-diffused GaN samples show NIR emission at 1064nm and 1350nm, while Er-diffused GaN samples have IR emission at 1546nm. This appears to be the first successful result of Nd diffusion doping into GaN crystals, and the first demonstration of above RT ferromagnetism involving GaN diffused with Nd. Details of our ferromagnetic and optical emission studies, related to the RE diffusion into GaN, are presented.
Temperature-Dependent Structural Disintegration of Delafossite CuFeO2
Authors: Pavunny Shojan P , Kumar Ashok , Thomas Reji , Murari Nishit M , Katiyar Ram S
Published: June 2009

Single phase delafossite p-type CuFeO2 (CFO) semiconductor was synthesized in bulk by modified solid state reaction technique. X-ray diffraction (XRD) and X-ray photo spectroscopy (XPS) studies suggest single phase CFO at room temperature. The energy dispersive X-ray spectroscopy (EDX) revealed that the atomic ratio of Cu and Fe is 1:1. The XPS spectra showed two intense Cu 2p3/2 and 2p1/2 peaks at 932.5 eV and 952 eV suggesting Cu is in +1 state. The temperature dependent Raman spectra of CFO displayed two intense modes at 349 cm-1 and 690 cm-1 at room temperature that matched with other delaffosite structures. The temperature dependent Raman spectra showed significant shift in both Raman active modes to lower frequency side. We observed the disappearance of pure CFO Raman active modes above 750 K and the appearance of new peaks related to CuO compounds, indicating disintegration of CFO starting above 750 K which almost completed above 1100 K. The temperature dependent thermo-gravimetric analysis indicates change in CFO mass above 750 K with wide range of differential thermo-gravimetric slope suggests disintegration started above 750 K and completed at 1100 K. Raman spectra, XPS, and XRD of disintegrated CFO matched well with the Raman spectra, XPS and XRD of CuO and CuFe2O4 confirmed its disintegration above 750 K in air.
Image Deconvolution - An Effective Tool of Crystal Structure and Defect Determination in High-Resolution Electron Microscopy
Authors: Li Fanghua , Tang Chunyan
Published: June 2009

Image deconvolution is introduced as an effective tool to enhance the determination of crystal structures and defects in high-resolution electron microscopy. The essence is to transform a single image that does not intuitively represent the examined crystal structure into the structure image. The principle and method of image deconvolution together with the related image contrast theory, the pseudo weak phase object approximation (pseudo WPOA), are briefly described. The method has been applied to different types of dislocations, twin boundaries, stacking faults, and one-dimensional incommensurate modulated structures. Results on the semiconducting epilayers Si0.76Ge0.24/Si and 3C-SiC/Si are given in some detail. The results on other compounds including AlSb/GaAs, GaN, Y0.6Na0.4Ba2Cu2.7Zn0.3O7-δ, Ca0.28Ba0.72Nb2O6and Bi2.31Sr1.69CuO6+δare briefly summarized. It is also shown how to recognize atoms of Si from C based on the pseudo WPOA, when the defect structures in SiC was determined at the atomic level with a 200 kV LaB6microscope.
Advanced TEM Characterization for Catalyst Nanoparticles Using Local Adaptive Threshold (LAT) Image Processing
Authors: Bele Petra , Stimming Ulrich
Published: June 2009

Metallic and non-metallic nanoparticles, usually supported on non-metallic substrates have attracted much interest concerning their application in the field of electrocatalysis. To characterize catalysts with respect to size, morphology, structure and composition (alloys or core-shell) of nanoparticles and their associated electrocatalytic activity, transmission electron microscopy (TEM) is the state of the art method. This investigation shows the advantages of advanced image processing using the local adaptive threshold (LAT) routine.
Computational Nanomechanics of Graphene Membranes
Authors: Perriot Romain , Gu Xiang , Oleynik Ivan I.
Published: June 2009

Molecular Dynamics (MD) simulations of nanoindentation on graphene membranes were performed. The 2-d Young's modulus of the graphene monolayer was determined as 243 ± 18 N/m and the breaking strength as 41 ± 3 N/m. These values agree reasonably well with recent experimental results [1]. In addition, the simulations allowed us to examine the atomic-scale dynamics of membrane breaking during the nanoindentation, involving formation of an increasing number of lattice defects until membrane is completely broken. The onset of defect appearance allowed us to determine the true elastic limit of graphene and the corresponding yield strength 29 ± 1 N/m which was not accessible experimentally. The defects consist of vacancies and Stone-Wales type defects. Long stable linear chains ofspbonded carbon atoms (carbynes) were observed under the indenter at the advanced stages of indentation. The dynamics of fracture propagation is governed by the shear stresses developed in the sample.
Shell repair in the clam Ruditapes philippinarum, affected by the Brown Ring Disease (BRD): a biochemical and serological study
Authors: Trinkler Nolwenn , Marin Frederic , Guichard Nathalie , Labonne Maylis , Bardeau Jean-François , Paillard Christine
Published: June 2009

For more than two decades, the edible clam Ruditapes philippinarum has been affected by the Brown Ring Disease (BRD), a bacterial infection characterized by the formation of a brown organic deposit in the internal side of the valves. Although this infection is often lethal, in some cases specimens can overcome it by remineralizing over the organic deposit. The goal of the present study is to compare biochemically and immunologically the shell matrices of repaired and healthy zones. Our data suggest that the repair zones exhibit certain variability, which would be the direct consequence of a modification of the secretory regime of calcifying tissues responsible of the repair process.
The Effect of Cellular Architecture on the Ductility and Strength of Metal Foams
Authors: Mangipudi K. R. , Onck Patrick R
Published: June 2009

A multiscale finite element model has been developed to study the fracture behaviour of two-dimensional random Voronoi structures. The influence of materials parameters and cellular architecture on the damage initiation and accumulation has been analyzed. The effect of the solid material’s strain hardening, relative density and architectural randomness on the ductility and fracture strength of the cellular solid are investigated. The results suggest materials-design directions in which the heat treatment, the solid material properties, its microstructure and the cellular architecture can be tuned for an optimized performance of cellular materials.
Acoustic Properties of Organic/Inorganic Composite Aerogels
Authors: Dong Winny , Faltens Tanya , Pantell Michael , Simon Diana , Thompson Travis , Dong Wayland
Published: June 2009

Composite aerogels (with varying concentrations of silica and poly-dimethylsiloxane) were developed and their acoustic absorption coefficient as a function of composition and average pores size have been measured. The polydimethylsiloxane modified the ceramic structure of the silica aerogels, decreasing the material’s rigidity while maintaining the high porosity of the aerogel structure. The composite aerogels were found to exhibit different modes
of acoustic absorption than that of typical porous absorbers such as fiberglass. At some frequencies, the composite aerogels had 40% higher absorption than that of commercial fiberglass. Physical data show that these materials have a large surface area (> 400 m2/g) and varying pore sizes (d ˜ 5 - 20 nm).
Nanoparticle Based Multilayers as Multifunctional Optical Coatings
Authors: Colodrero Silvia , Calvo Mauricio E. , Sobrado Olalla Sánchez , Míguez Hernán
Published: June 2009

Herein we introduce nanoparticle based periodic multilayers as base materials to create different types of multifunctional coatings that combine optical, mechanical and diffusion properties. The technological potential of these versatile materials is demonstrated by showing applications in the fields of sensing and photovoltaic materials. Due to the porous nature of such structures, liquids and gases can infiltrate or condensate, respectively within the interstices, causing a variation of the refractive index (R.I.)of the layers. This gives rise to clear but gradual changes of the optical responses, either when liquids or the partial pressure of vapors are infiltrated in the structure. Also, photoconducting Bragg mirrors can be built by precise control of the spatial variation of the R.I. of the layers in a pure TiO2 multilayer. Rationally placed within a Dye Sensitized Solar Cell (DSSC), that gives rise to a significant enhancement of the solar to electric power conversion efficiency through the amplification of sunlight absorption. Direct observation of both optical absorption and photocurrent resonances can be seen.
Dynamic constitutional hybrid materials-toward adaptive self-organized devices
Authors: Barboiu Mihail , Cazacu Adinela , Mihai Simona , Legrand Yves-Marie , van der Lee Arie
Published: June 2009

Dynamic constitutional hybrid materials in which the functional self-organized macrocycles are reversibly connected with the inorganic silica mesopores through hydrophobic non-covalent interactions. Supramolecular columnar self-organized architectures confined within scaffolding hydrophobic silica mesopores can be structurally determined by using X-ray diffraction techniques.
Effect of Implant Design on Initial Stability of Tapered Implants
Authors: Chong Linus , Khocht Ahmed , Suzuki Jon B. , Gaughan John
Published: June 2009

Implant design is one of the parameters for achieving successful primary stability. This study aims to examine the effect of a self-tapping blades implant design on initial stability in tapered implants. Polyurethane blocks of different densities were used to simulate different bone densities. The two different implant designs included one with self-tapping blades and one without self-tapping blades. Implants were placed at 3 different depths: apical third, middle third, and fully inserted at 3 different densities of polyurethane blocks. A resonance frequency (RF) analyzer was then used to measure stability of the implants. Repeated-measures analysis of variance was used to examine the effect of implant design, insertion depth, and block density on RF. Analysis of covariance was used to examine the strength of association between RF and the aforementioned factors. In both medium-density (P = .017) and high-density (P = .002) blocks, fully inserted non-self-tapping implants showed higher initial stability than self-tapping implants. No differences were noted between the 2 implant designs that were not fully inserted. The highest strength of association was with insertion depth (standardized beta [std β] = −0.60, P = .0001), followed by block density (std β = −0.15, P = .0002). Implant design showed a weak association (std β = −0.07, P = .09). In conclusion, fully inserted implants without self-tapping blades have higher initial stability than implants with self-tapping blades. However, the association strength between implant design and initial stability is less relevant than other factors, such as insertion depth and block density. Thus, if bone quality and quantity are optimal, they may compensate for design inadequacy.
Immediate Placement and Temporization of Implants: Three- to Five-year Retrospective Results
Authors: Avvanzo Pierluigi , Ciavarella Domenico , Avvanzo Andrea , Giannone Nicola , Carella Mauro , Lo Muzio Lorenzo
Published: June 2009

The immediate placement of dental implants in esthetic areas is a primary challenge for modern implantology. The underlying treatment goal is to preserve the natural periodontal architecture; in recent years, however, a concurrent goal has been to reduce the period between implant placement in the fresh extraction socket and delivery of the definitive restoration, but adequate long-term data are still lacking on the efficacy of this technique. A 3- to 5-year retrospective analysis of 282 dental implants immediately placed into extraction sockets, and temporized with nonoccluding provisional prostheses has been undertaken. All recorded outcomes and complications, as well as a proposed protocol for management of immediate function, are discussed.
Binswanger's disease and quantitative fractional anisotropy
Authors: Engelhardt Eliasz , Moreira Denise Madeira , Alves Gilberto Sousa , Lanna Maria Elisa Oliveira , Alves Carlos Eduardo de Oliveira , Ericeira-Valente Letice , Sudo Felipe Kenji , Laks Jerson
Published: June 2009

OBJECTIVE: To study the integrity of the white matter in Binswanger's disease (BD) patients with quantitative fractional anisotropy (DTI-FA). METHOD: Controls (12) and patients with BD (12) were included. Scans performed with MR (GE Signa Horizon/1.5T). Fazekas's score=6 with white matter hyperintensities extension >75% assessed on FLAIR scans. Standard parameters for DTI-FA were used. ROIs placed in symmetrical regions on two axial planes, data pooled in anterior (frontal) and posterior (temporo-parieto-occipital) regions. Analysis with Functool. Statistics for anterior and posterior regions comparison. RESULTS: DTI-FA showed reduction of anisotropy, reflecting axonal damage and demyelination of fibers, more prominent in anterior in relation to posterior region, in BD patients in comparison to controls. CONCLUSION: Loss of integrity of fiber tracts reflects interruption of neural networks that subserve cognitive, behavioral, and motor integration. The more severely affected frontal region is related to executive dysfunction, a characteristic feature of Binswanger's disease.
Combined instruments for the screening of dementia in older people with low Education
Authors: Bottino Cássio M.C. , Zevallos-Bustamante Sonia E. , Lopes Marcos A. , Azevedo Dionisio , Hototian Sérgio R. , Jacob-Filho Wilson , Litvoc Julio
Published: June 2009

OBJECTIVE: To determine which combination of cognitive tests and informant reports can improve the diagnostic accuracy of dementia screening in low educated older people. METHOD: Patients with mild to moderate dementia (n=34) according to ICD-10 and DSM-III-R criteria and 59 older controls were assessed with the Mini-Mental State Examination (MMSE) and the Fuld Object Memory Evaluation (FOME). Informants were assessed using the Informant Questionnaire on Cognitive Decline in the Elderly and the Bayer-Activities of Daily Living Scale. RESULTS: The 4 instruments combined with the mixed rule correctly classified 100% and the logistic regression (weighted sum) classified 95.7% of subjects. The weighted sum had a significantly larger ROC area compared to MMSE (p=0.008) and FOME (p=0.023). The specificity of the tested combinations was superior to the MMSE alone (p=0.002). CONCLUSIONS: Cognitive tests combined with informant reports can improve the screening of mild to moderate dementia in low educated older people.
Association between the DRD2-141C Insertion/Deletion polymorphism and schizophrenia
Authors: Cordeiro Quirino , Siqueira-Roberto Jacqueline , Zung Stevin , Vallada Homero
Published: June 2009

Epidemiological studies have demonstrated that the genetic component is an important risk factor for the development of schizophrenia. The genes that codify the different compounds of the dopaminergic system have created interest for molecular investigations in patients with schizophrenia because the antipsychotic drugs, especially those of first generation, act on this cerebral system. Thus the aim of the present study was to investigate the possible association between the -141 Ins/Del (rs1799732) polymorphism of the dopamine receptor type 2 (DRD2) and schizophrenia. The distribution of the alleles and genotypes of the studied polymorphism was investigated in a sample of 229 patients and 733 controls. There were statistical differences in the allelic (χ2=9.78; p=0.001) and genotypic genotypic (χ2=12.74; p=0.001) distributions between patients and controls. Thus the -141C Ins/Del polymorphism of the DRD2 gene (allele Ins) was associated to the SCZ phenotype in the investigated sample.
Effectiveness of clozapine, haloperidol and chlorpromazine in schizophrenia during a five-year period
Authors: Ravanic Dragan B. , Dejanovic Slavica M. Djukic , Janjic Vladimir , Jovic Suzana D. , Milovanovic Dragan R. , Jakovljevic Vladimir , Pantovic Vesna , Ravanic Boris , Pantovic Maja , Pantovic Mihailo M.
Published: June 2009

OBJECTIVE: The aim of our study was to evaluate the effects of low doses of clozapine in flexible regime in comparison with haloperidol and chlorpromazine in long term. METHOD: The naturalistic study was prospective, active-controlled with 325 adult outpatients of both genders (140 females), with mean year age of 34.8 (range 21-57), suffering from chronic schizophrenia. The first onset of illness was at the mean of 27.9 years (range 17-38), and subjects had the mean year age of 4.1±0.5 previous relapses. The patients were allocated to receive haloperidol (105 subjects, dose range 2-15 mg), chlorpromazine (n=105, 100-400 mg) or clozapine (n=115, 75-600 mg). The scores of psychometric instruments (GWB, PANSS, CGI) were regularly assessed during 5 year period. RESULTS: The sixty-six responders were included in per-protocol analysis: 12, 10 and 16 with positive and 7, 6 and 15 with negative schizophrenic syndrome in haloperidol, chlorpromazine and clozapine group, respectively. The statistically significant differences in all psychometric scores was found, for both schizophrenic syndromes, favoring clozapine. The distribution of eighteen different types of adverse events, which we noted, were significantly different among treatment groups ( χ2=315.7, df=34, p<0.001). Clozapine was safer and had fewer adverse effects (average of 0.9 adverse events per patient) than haloperidol (2.7) and chlorpromazine (3.2). CONCLUSIONS: Clozapine, in low doses of flexible regime, in long term (five years) showed better effectiveness in chronic schizophrenics with positive and negative symptoms than typical antipsychotics.
Is there something special about cardiovascular abnormalities and sudden unexpected death in epilepsy among patients with chronic renal insufficiency in regular hemodialysis program?
Authors: Gomes Rui A. , Kesrouani Silvana , Cruz Jenner , Silva Alexandre L. , Henriques Tânia M.G. , Albuquerque Marly de , Arida Ricardo M. , Sonoda Eliza Y.F. , Cysneiros Roberta M. , Terra Vera C. , Scorza Carla A. , Cavalheiro Esper A. , Scorza Fulvio A.
Published: June 2009

Of the many risk factors suggested for sudden unexpected death in epilepsy (SUDEP), higher frequency of seizures is a very consistent issue. Following this reasoning, it has been established that hemodialysis-associated seizure is a complication of dialysis procedure. Based on these facts, this study investigated a possible association between cardiovascular abnormalities and SUDEP among patients with chronic renal insufficiency in regular hemodialysis program. For that, a retrospective medical history of 209 patients was reviewed to investigate the occurrence of convulsive seizures and EKG abnormalities during dialytic program. Three patients presented generalized tonic-clonic seizures, one had partial seizure with secondary generalization, and one presented unclassified seizure. Any EKG abnormalities and SUDEP event were found in all patients evaluated. In conclusion, the present findings demonstrated uncommon the occurrence of seizures and also SUDEP. Probably, the main justification to not allow us to demonstrated a direct relation between SUDEP and cardiovascular diseases in hemodialysis are the reduced number of cases examined.
Vestibular rehabilitation: clinical benefits to patients with Parkinson's disease
Authors: Zeigelboim Bianca Simone , Klagenberg Karlin Fabianne , Teive Hélio A. Ghizoni , Munhoz Renato Puppi , Martins-Bassetto Jackeline
Published: June 2009

OBJECTIVE: To evaluate the effectiveness of the vestibular rehabilitation (VR) exercises by means of an assessment before and after the application of the Brazilian version of the Dizziness Handicap Inventory (DHI) questionnaire. METHOD: Twelve patients were studied, the following procedures were carried out: anamnesis, otorhinolaryngological and vestibular evaluation, and the application of the DHI before and after the VR. RESULTS: Clinically resting tremors and subjective postural instability were the motor complaints most frequently associated with complaints of vertigo in 12 cases (100%); in the vestibular exam, all the patients presented abnormalities, frequently from the uni and bilateral peripheral vestibular deficiency syndromes in 10 cases (83.3%); there was significant improvement in the physical, functional and emotional aspects of the DHI after the completion of the VR. CONCLUSION: The VR following the Cawthorne and Cooksey protocol were shown to be useful in managing subjective complaints of several aspects evaluated in this protocol.
Language and cognition in very low birth weight preterm infants with PELCDO application
Authors: Bühler Karina Elena Bernardis , Limongi Suelly Cecília Olivan , Diniz Edna Maria de Albuquerque
Published: June 2009

The performance of very low birth weight preterm infants, in terms of cognition and expressive language, was analyzed and compared with that of term infants with the Protocol for Expressive Language and Cognition Development Observation (PELCDO). The study involved 12 very low birth weight preterm infants and 20 term infants, all of whom were evaluated monthly. Sessions were videotaped, and data were analyzed according to this specific protocol. Our results suggest that cognition and expressive language develop significantly later in very low birth weight preterm infants than in the term. We found positive correlations for cognitive and expressive language development, the delay becoming more evident after 6 months of age, persisting through the sensorimotor period, and continuing into the beginning of preoperational period, indicating the importance of follow-up evaluation, defining the true needs of such infants and identifying the ideal moment for speech-language intervention.
Application of magnetic resonance spectroscopy in the differentiation of high-grade brain neoplasm and inflammatory brain lesions
Authors: Ferraz-Filho José Roberto Lopes , Santana-Netto Pedro Vieira , Rocha-Filho Jose Alves , Sgnolf Aline , Mauad Fernando , Sanches Rafael Angelo
Published: June 2009

This study aims at evaluating the application of magnetic resonance spectroscopy (MRS) in the differential diagnosis of brain tumors and inflammatory brain lesions. The examinations of 81 individuals, who performed brain MRS and were retrospectively analyzed. The patients with ages between 10 and 80 years old, were divided into two groups. Group A consisted of 42 individuals with diagnoses of cerebral toxoplasmosis and Group B was formed of 39 individuals with diagnosis of glial neoplasms. On analyzing the ROC curve, the discriminatory boundary for the Cho/Cr ratio between inflammatory lesions and tumors was 1.97 and for the NAA/Cr ratio it was 1.12. RMS is an important method useful in the distinction of inflammatory brain lesions and high-degree tumors when the Cho/Cr ratio is greater than 1.97 and the NAA/Cr ratio is less than 1.12. And so this method is important in the planning of treatment and monitoring of the therapeutic efficiency.
L4-L5-S1 human dermatomes: a clinical, electromyographical, imaging and surgical findings
Authors: Faleiros Antonio Tadeu de Souza , Resende Luiz Antonio de Lima , Zanini Marco Antonio , Castro Heloisa Amélia de Lima , Gabarra Roberto Colichio
Published: June 2009

There is substantial controversy in literature about human dermatomes. We studied L4, L5, and S1 inferior limb dermatomes by comparing clinical signs and symptoms with conduction studies, electromyographical data, neurosurgical findings, and imaging data from computerized tomography (CT) or magnetic resonance imaging (MRI). After analyzing 60 patients, we concluded that L4 is probably located in the medial aspect of the leg, L5 in the lateral aspect of the leg and foot dorsus, and S1 in the posterior aspect of the backside, tight, leg and plantar foot skin. This is the first time that these human dermatomes have been evaluated by combined analysis of clinical, electromyographical, neurosurgical, and imaging data.
Transitional lumbosacral vertebrae and low back pain: diagnostic pitfalls and management of Bertolotti's syndrome
Authors: Almeida Daniel Benzecry de , Mattei Tobias Alécio , Sória Marília Grando , Prandini Mirto Nelso , Leal André Giacomelli , Milano Jerônimo Buzzeti , Ramina Ricardo
Published: June 2009

OBJECTIVE: Bertolotti's syndrome is a spine disorder characterized by the occurrence of a congenital lumbar transverse mega-apophysis in a transitional vertebral body that usually articulates with the sacrum or the iliac bone. It has been considered a possible cause of low back pain. METHOD: We analyzed the cases of Bertolotti's syndrome that failed clinical treatment and reviewed the literature concerning this subject. RESULTS: Five patients in our series had severe low back pain due to the neo-articulation and two of them were successfully submitted to surgical resection of the transverse mega-apophysis. Taking into account the clinical and surgical experience acquired with these cases, we propose a diagnostic-therapeutic algorithm. CONCLUSION: There is still no consensus about the most appropriate therapy for Bertolotti's syndrome. In patients in whom the mega-apophysis itself may be the source of back pain, surgical resection may be a safe and effective procedure.
Spontaneous thrombosis of internal carotid artery: a natural history of giant carotid cavernous aneurysms
Authors: Vasconcellos Lucas Perez de , Flores Juan Antônio Castro , Conti Mário Luiz Marques , Veiga José Carlos Esteves , Lancellotti Carmen Lúcia Penteado
Published: June 2009

OBJECTIVE: To describe five cases of giant carotid cavernous aneurysms which evolved with spontaneous thrombosis of internal carotid artery (STICA), with emphasis at epidemiology, clinical presentation, natural history, related factors and neurological outcome. METHOD: There were 711 consecutives patients with 802 aneurysms with and without surgical treatment during a period of 19 years. We selected 35 patients with 40 carotid cavernous aneurysms (5%) of which 20 (50%) were giant aneurysms. Among those cases, 5 patients evolved with STICA (25%). Symptoms and findings at presentation were recorded and compared with those at outcome. RESULTS: Clinical presentation was commonly related to atherosclerotic factors such as elevated blood pressure (80%), diabetes mellitus (40%) and dislipidemy (40%). All patients presented with hemicranial headache, ophthalmparesy and retro bulbar pain, and after STICA all presented improvement of symptoms. After STICA, 4 patients had regression of deficit, 2 partial and 2 complete. Four patients had sensorial trigeminal neuropathy in V1 and V2 territories, also showing improvement of symptoms after STICA. CONCLUSION: STICA is a common outcome in giant carotid cavernous aneurysms, and is related with significant improvement of symptoms; however, it may be catastrophic for those patients without efficient collateral circulation.