bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability of nc-ZnO Embedded ZrHfO High-kNonvolatile Memory Devices Stressed at High Temperatures
Authors: Yang Chia-Han , Kuo Yue , Lin Chen-Han , Kuo Way
Published: June 2009

The nanocrystalline ZnO embedded Zr-doped HfO2high-kdielectric has been made into MOS capacitors for nonvolatile memory studies. The device shows a large charge storage density, a large memory window, and a long charge retention time. In this paper, authors investigated the temperature effect on the reliability of this kind of device in the range of 25°C to 175°C. In addition to the trap-assisted conduction, the memory window and the breakdown strength decreased with the increase of the temperature. The high-k film's conductivity increased and the nc-ZnO's charge retention capability decreased with the increase of temperature. The nc-ZnO retained the trapped charges even after the high-k film broke down and eventually lost the charges at a higher voltage. The difference between these two voltages decreased with the increase of the temperature.
Charge Storage Properties of Nickel Silicide Nanocrystal Layer Embedded in Silicon Dioxide
Authors: Jang Yoo-Sung , Yoon Jong-Hwan
Published: June 2009

Memory properties of nickel silicide nanocrystal monolayers embedded in silicon dioxide have been investigated. The nanocrystal layers were produced by thermal annealing of a sandwich structure comprised of ultrathin Ni film (0.2 nm) sandwiched between two silicon-rich oxide (SiO1.57) layers. Average diameter and areal density is about 2.9 nm and 1.3×1012 cm-2, respectively. Capacitance-voltage (C-V) measurements are shown to have C-V characteristics suitable for nonvolatile memory applications, including large memory window (∼ 10 V), long retention time ( > 107 s), and excellent endurance ( > 106 program/erase cycles).
Photonic Thermal Conductance in Multi-layer Photonic Crystals
Authors: Lau Wah Tung , Shen Jung-Tsung , Fan Shanhui
Published: June 2009

Photonic thermal conductance of a multi-layer photonic crystal, when normalized with the corresponding thermal conductance of vacuum at each temperature, can be significantly below unity. The minimum of this normalized thermal conductance occurs at the high-temperature limit, and the conductance value at this limit is independent of the layer thicknesses. We give an analytic theory to explain such independence, and show that it is related to the ergodic nature of the distribution of photonic bands in frequency space.
Effects of CuIn0,5Ga0,5Se2 growth by isothermal and bithermal Cu-Poor/Rich/Poor sequence on solar cells properties
Authors: Marko Hakim , Hultqvist Adam , Platzer-Björkman Charlotte , Noël Sébastien , Kessler John
Published: June 2009

Co-evaporated CuIn0,5Ga0,5Se2 thin film solar cells were grown using a sequential Cu-Poor/Rich/Poor process (CUPRO). During the growth process, the substrate temperature was either kept constant at 570 °C (iso-CUPRO) or decreased during the first step to either 360 or 430 or 500 °C (bi-CUPRO). According to atomic force microscopy (AFM) measurements, the lower the temperature is in the first step the smoother the final CIGS surface becomes. By decreasing the first step temperature, cross-section scanning electron microscopy (SEM) and θ-2θ x-ray diffraction (XRD) do not reveal clearly any important changes of morphology and crystallographic preferred orientation. SLG/Mo/CIGS/Buffer layer/i-ZnO/ZnO:Al/grid(Ni/Al/Ni) solar cells with either a chemical bath deposited CdS or an atomic layer deposited Zn(O,S) buffer layer were fabricated. For both buffer layers, the bi-CUPRO processes lead to higher efficiencies. Besides, using Zn(O,S), the electronic collection was improved for the infrared spectrum as well as for the ultraviolet spectrum. This resulted in efficiencies close to 14,5% for the Zn(O,S) cells.
Mechanical Properties and Adhesion of CdTe/CdS Thin Film Solar Cells Deposited on Flexible Foil Substrates
Authors: Hodges Deidra Ranel , Palekis Vasilios , Bhandaru Shweta , Singh Kartikay , Morel Don L , Stefanakos Lee
Published: June 2009

Cadmium telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal band gap of 1.45 eV, its high optical absorption coefficient and availability of various device fabrication methods. Superstrate CdTe solar cells fabricated on glass have to-date exhibited efficiencies of 16.5%. Work on substrate devices has been limited due to difficulties associated with the formation of an ohmic contact with CdTe. Foil substrate curvature, flaking, delamination and adhesion as a result of compressive strain due to the coefficient of thermal expansion (CTE) mismatch between the flexible foil substrate and the solar cell films has been studied. Thin films have been characterized by AFM, XRD, SEM, ASTM D3359-08 tape test, and solar cells have been characterized using J-V and spectral measurements. Adhesion improves by minimizing the mismatch of the CTE . A CdCl2 treatment is important for high efficiency solar cells. The treatment influences the microstructure and interface properties of the layers. The effect of the current CdCl2 chemical treatment increases flaking and has to be optimized for the CdTe substrate cell on foil. We have also fabricated solar cells on tantalum, molybdenum and tungsten foils, all with lower CTEs than SS430. We are currently producing solar cells with a VOC of 630mV, a 50% fill factor and over 6.0% efficiency.
Improvement in the FF over 0.700 by Controlling the Interface Quality
Authors: Kushiya Katsumi , Tanaka Y. , Hakuma H. , Kijima S. , Aramoto T. , Fujiwara Y. , Chiba Y. , Sugimoto H. , Kawaguchi Y. , Kakegawa K.
Published: June 2009

In this study, the pn hetero-interface between Zn(O,S,OH)x buffer and Cu(InGa)(SSe)2 (CIGSS) surface layers is discussed in order to achieve the fill factor (FF) over 0.73 and the circuit efficiency of 16 % on aperture area of over 800 cm2. Two resistances, i.e. shunt resistance (Rsh) and series resistance (Rs), in the circuits are employed as a yardstick to evaluate the interface quality. Since there are no realistic yardsticks on the Rs, the difference between Voc and optimum-power voltage (Vop) (i.e. Voc-Vop [V/cell]) is applied as a simple tool to evaluate the Rs. It is emphasized that it is important to reduce the Rs mainly correlated to the buffer deposition process and, as a result, the interface quality. We consider the Rs is dependent on the remaining Zn(OH)2 concentration in the Zn(O,S,OH)x buffer deposited by a chemical-bath deposition (CBD) technique. As an approach to make the Rs minimize and the Rsh maximize simultaneously, adjusting the thickness of a CBD-Zn(O,S,OH)x buffer layer and a non-doped ZnO layer deposited by a metal-organic chemical vapor deposition (MOCVD) technique has been effective to reduce the remaining Zn(OH)2 concentration. Determining the optimized deposition procedure to achieve the FF over 0.700 consistently, the circuit efficiency of 15.3 % with aperture area of 856 cm2 and the FF of 0.717 has been achieved.
Suitability of Atmospheric-pressure MOCVD CdTe Solar Cells for Inline Production Scale
Authors: Barrioz Vincent , Lamb Dan A , Jones Eurig W. , Irvine Stuart
Published: June 2009

CdTe, with a direct band gap of 1.45 eV is well suited to the terrestrial AM1.5 solar irradiance and currently makes up half of the thin film (TF) photovoltaic (PV) market. There are 4 main factors that determine final cost of PV modules: the conversion efficiency, materials amount per unit area of module, production yield, and the economy of scale. It is therefore valuable to investigate alternative and/or innovative deposition techniques and processes which have the potential to impact on these factors. Metal organic chemical vapour deposition (MOCVD) is a powerful technique offering increased process repeatability, achieving a high level of control of materials characteristics. Recent improvements in CdTe devices using atmospheric–pressure (AP) MOCVD have led to efficiencies of 13.3 % using 2 μm absorber layers and 11 % with a 1 μm absorber layer [11, 12]. These results were achieved: by extending the optical band gap of the window layer, using a ternary alloy (Cd0.9Zn0.1S), with intentional p-type doping of the CdTe layers with As, and the use of an in situ (dry) deposited CdCl2 layer and anneal. All layers, except the front and back contact, are grown by a sequential MOCVD process. Furthermore this is a dry process without the need for any etch treatment. The inherent design of the horizontal MOCVD laboratory chambers do not lend themselves well to large scale production. However, the CSER group has designed and built an experimental inline reaction chamber to evaluate AP-MOCVD as an inline production process. Discussion is made based on kinetically limited growth and molar supply models to assess the suitability of the MOCVD process to deposit fast enough for an inline process. The AP-MOCVD inline reactor uses a showerhead to deliver the precursors onto a moving 5 × 7.5 cm2 substrate and preliminary results for deposited layers are given. From these preliminary results it has been extrapolated that a 1 μm thick CdTe layer can be deposited on substrates moving at 60 cm/min.
Enhancement of the Thermoelectric Figure of Merit in Gated Bismuth Telluride Nanowires
Authors: Bejenari Igor , Kantser Valeriu , Balandin Alexander
Published: June 2009

We theoretically studied how the electric filed effect can modify thermoelectric properties of intrinsic bismuth telluride nanowires, which are grown along [110] direction. The electronic structure and wave functions were calculated by solving the self-consistent system of the Schrodinger and Poisson equations by means of both the Thomas-Fermi approximation and the spectral element method. The thermoelectric parameters were determined using a constant relaxation-time approximation. The external electric field can increase the Seebeck coefficient of a nanowire with 7 - 15 nm lateral dimensions by nearly a factor of two, and enhance the figure of merit by an order of magnitude.
Melt-Textured Growth of Grain Aligned Bulk Oxide Thermoelectrics
Authors: Selvamanickam Venkat , Zhang Bo
Published: June 2009

A new process, based on melt processing has been investigated with oxide thermoelectrics to achieve long-range grain alignment for low resistivity as well as to embed secondary phase precipitates and associated crystal defects for low thermal conductivity. Melt-processing of Bi2Sr2Co2Ox and CaMnO3 has been studied. A high degree of (00l) grain alignment has been achieved by melt processing. Good values of Seebeck coefficient of nearly -250 μV/K were measured in the melt-processed CaMnO3. Secondary phases of Ca4Mn3O10 and CaMn2O4 are found to be trapped between the aligned grains which led to high electrical resistivity values and limited the figure of merit in our initial samples.
Expanded 3D Electrode Architecture for Low Temperature Direct Liquid Fuel Cells
Authors: Urian Richard Craig
Published: June 2009

The US Navy continues to pursue electrochemical power sources with high energy density for low rate, long endurance undersea applications. The direct electro-oxidation and electro-reduction of sodium borohydride and hydrogen peroxide are being investigated to meet these goals. In an effort to minimize polarization losses and increase power density, a novel carbon microfiber array (CMA) electrode is being investigated.

The CMA is composed of 750 micron long, 10 micron diameter graphite fibers that protrude from a current collector like blades of grass. The CMA was developed for the direct reaction of peroxide in the Mg-H2O2 semi fuel cell. [1] There, the high surface area of the microfiber cathode reduces peroxide concentration polarization, resulting in increased power and energy density. For this work the CMA architecture was adapted into a novel membrane electrode assembly and evaluated in the direct BH4- / H2O2 fuel cell. The unique feature of this architecture vs. traditional membrane electrode assemblies (MEAs) is how all three components of the triple boundary interface are optimized: electrical connectivity, ionic connectivity and mass transport. The current iteration of this electrode architecture utilizes a carbon cloth that has been hot pressed into N115 membrane. This component is then placed over the CMFA electrode. The carbon microfibers of the CMFA protrude up into the carbon cloth matrix forming a 3-dimewnsional, interdigitated electrode architecture. The result of this modification is improved electrolyte flow through the CMFA and improved utilization of the surface area afforded by the carbon microfibers that was not observed in the non modified CMFA.
Half cell polarization measurements were obtained simultaneously with the fuel cell polarization. Initial results using this modified CMFA electrode architecture show that the polarization losses observed for both the reduction of hydrogen peroxide and for the oxidation of borohydride were 5.2 times lower than for the non-modified CMAs electrode (0.014 ohms vs. 0.074 ohms). Comparing these results to those calculated from the literature [2, 3], where traditional membrane electrode assemblies were used for borohydride oxidation, 5 and 2.6 time improvements were obtained (0.07 ohms and 0.037 ohms were the effective resistive losses seen in the anode half cell polarizations).
Design of 3-dimensional Textured Organic Solar Cells
Authors: Nalwa Kanwar Singh , Chaudhary Sumit
Published: June 2009

Organic materials are attractive for photovoltaics primarily because of the prospect of high throughput solution-processible manufacturing using roll-to-roll or spray deposition. In the formation of polymer based photovoltaic devices, the aspect that limits the power conversion efficiency is the bottleneck between short diffusion lengths of the excited states (excitons) in polymers, in the range of 10-20 nm. Optical absorption length, which is in the range of 50-200 nm and much larger than the exciton diffusion length, poses the limit on charge generation and collection. It is important to achieve complete optical absorption in active layers much thinner than optical absorption length to minimize losses due to recombination of charge carriers. Previously, light trapping techniques have been coupled with organic solar cell but without significant success. In this paper, three-dimensional sub micron grating structure is analyzed using finite element method (FEM) simulations for finding the optical absorption in different layers of solar cell to optimize the photonic concentrator effect of the grating structure. The energy dissipation of electromagnetic field in the active layer is studied as a function of active layer thickness, grating pitch and height. The superiority of grating structure in terms of light trapping feature as compared to planar geometry is clearly demonstrated by simulation results.
Deformation Mapping in Micro- and Nanoscale Fibers
Authors: Garman Christina , Bindert Natalie , Sunkara Adhira , Paliulis Leocadia , Ebenstein Donna M
Published: June 2009

Small-scale natural fibers are among the biological materials being studied by researchers seeking innovative methods to create new high performance materials. For example, spider dragline silk fibers are being studied because of their unique combination of high strength-to-weight ratio and high extensibility, which leads to a tough and lightweight fiber. Biomimetic fibers based on spider silk have been a focus of research for the past decade. However, there are still many unanswered questions about the mechanisms by which silk achieves its unique mechanical properties, as well as challenges in mechanical testing of biomimetic silk fibers (which is often hindered by both small diameters and limited material availability). A method to characterize local mechanical behavior in small diameter fibers was developed to both improve understanding of structure-property relationships in natural fibers and provide a method for comparing mechanical behavior in natural and biomimetic fibers. The deformation mapping technique described in this paper, which utilizes a piezoelectric micromanipulator with pulled glass tips, an inverted microscope with attached camera, and an image processing MATLAB program, is also applicable to the characterization of other micro- and nanoscale fibers where local deformation mechanisms may be of interest (e.g., for mechanical characterization of electrospun fibers).
Nano-meter scale plasticity in KBr studied by nanoindenter and force microscopy
Authors: Manimunda Praveena , Filleter Tobin , Egberts Philip , Jayaram Vikram , Biswas Sanjay Kumar , Bennewitz Roland
Published: June 2009

The early stages of plasticity in KBr single crystals have been studied by means of nanometer-scale indentation in complementary experiments using both a nanoindenter and an atomic force microscope. Nanoindentation experiments precisely correlate indentation depth and forces, while force microscopy provides high-resolution force measurements and images of the surface revealing dislocation activity. The two methods provide very similar results for the onset of plasticity in KBr. Upon loading we observe yield of the surface in atomic layer units which we attribute to the nucleation of single dislocations. Unloading is accompanied by plastic recovery as evident from a non-linear force distance unloading curve and delayed discrete plasticity events.
Nacre Evolution : A Proteomic Approach
Authors: Marie Benjamin , Le Roy Nathalie , Marie Arul , Dubost Lionel , Milet Christian , Bedouet Laurent , Becchi Michel , Zanella-Cléon Isabelle , Jackson Daniel , Degnan Bernard , Luquet Gilles , Marin Frederic
Published: June 2009

From an evolutionary viewpoint, the molluscan nacre constitutes a fascinating object. This microstructure appeared early, in the Lower Cambrian period, about 530 million years ago, and since then, has been kept unchanged until today. Nacre is restricted to the conchiferan mollusks, where it occurs in t least three main classes, bivalves, gastropods and cephalopods. The aim of the present study is to investigate whether all nacres are built from the same “macromolecular tools”, proteins of the nacre matrix. To this end, we studied three new nacre models, the freshwater bivalveUnio pictorum, the cephalopodNautilus macromphalus, and the gastropodHaliotis asinina, to which we applied a combined biochemical and proteomic characterization of their respective nacre matrices. The results of our approach, that can be defined as “shellomics” (proteomics applied to shell proteins) shed a new light on the macroevolution of nacre matrix proteins and on the in vitro design of nacre-like biomaterials.
Circumferential Arc-Shaped Microcracks in Haversian Bone: Lead-Uranyl Acetate Staining for Micro-CT Imaging
Authors: Ebacher Vincent , Wang Rizhi
Published: June 2009

Despite much progress in recent years, the nature of microcracking in bone at the nano-meter scale is still not well understood. This is partly due to the complexity of bone's hierarchical structure, but also to the difficulty of detecting cracks at very fine scales. Bone microcracking is typically detected using fluorescent dye staining techniques followed by optical or laser microscopy examinations. However, fluorescence-based methods are limited to sub-micron resolution and do not fit three-dimensional imaging such as micro-CT or high resolution imaging such as electron microscopy. This pilot study explores the potential of a heavy metal staining technique to label nano-sized cracks in bone that could be detected by electron microscopy and, albeit at a larger scale, by micro-computed tomography. Upon further development, the method described here may lead to the nano-meter scale characterization of bone microcracking.
A New Multilayered Composite Bioceramic for Bone Graft
Authors: Arias JoséIgnacio , Neira-Carrillo Andrónico , Yazdani-Pedram Mehrdad , Fernandez Maria Soledad , Arias Jose
Published: June 2009

Bone grafts need to comply with some criteria of biocompatibility, including favoring neovascularization, new bone formation, and discourage inflammatory response and graft rejection. It is also expected that these materials should have mechanical properties similar to those of natural bone, that is, having enough pores to permit osteoprogenitor cells and vascular endothelium penetration but maintaining strength and flexibility.

Here, a new resistant and flexible tridimensional multilayered bioceramic composite was obtained by using chitosan and hydroxyapatite in combination with cells and their associated growth factors from the bone marrow tissue, allowing the development of a biocompatible bone graft.

This multilayered graft made out of chitosan functionalized with phosphate groups and mineralized with calcium phosphate (hydroxyapatite) was analyzed with scanning electron microscopy (SEM), X ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR) to assess the degree of phosphorylation and the amount of hydroxyapatite present in the graft. The composite was further characterized by mechanical testing (Vicker's microhardness test), in vitro osteoblasts culture citotoxicity tests.

The results showed that this multilayered graft has mechanical properties comparable to that of trabecular bone and it was capable to keed osteogenic cells alive.
Mechanical Properties of Sintered and Non Sintered Stainless Steel Wools: Experimental Investigation and Modelling
Authors: Masse Jean-Philippe , Bouaziz Olivier , Bréchet Yves , Salvo Luc
Published: June 2009

Entangled fibrous materials have a common point with cellular solids: the architecture is at the millimetric scale. However, they present one extra degree of freedom which is the connectivity on the constituents: while compressing a fibrous structure, the number of contacts between fibers is variable, by contrast to cellular solids where the building lock is the cell. In this respect, fibrous entangled solids can span a whole range of mechanical behavior depending on the possibility offered to fibers to create new contacts: from the felt where they are totally free, to the fully sintered wool where their relative motion is constrained by irreversible contacts.
The purpose of this paper is to investigate the mechanical properties of this class of materials, based on micro tomography observations for the number of contacts, and on a physically based model for fiber bending and collective reorganization. The material studied is a stainless steel wool. The properties investigated are the loading curves for sintered and non sintered wools. Qualitative differences introduced by sintering motivate a modification of the classical Toll model, which will be presented together with the experimental results.
Anisotropic Clay Aerogel Composite Materials
Authors: Gawryla Matthew D , Schiraldi David A.
Published: June 2009

Clay aerogel composites have been around for over 50 years but still they represent a relatively under studied class of materials. Clay aerogel composites have been made in our labs that have low densities, 0.05-0.1g/cm3, provide good thermal insulation, k 0.02W/mK, and are created through an environmentally benign process. The mechanical properties of the composites resemble those of typical foamed polymers such as expanded polystyrene and polyurethane, with compressive moduli ranging from 0.5MPa to 40MPa depending on composition. Aqueous solutions of clay and polymer are frozen in cylindrical molds and freezedried to create these foam-like materials. Typically there is no particular orientation to the often layered structure that results, however if frozen in a unidirectional manner, anisotropic materials can be made. In this paper we will discuss the effects of molecular weight on mechanical properties of various composites as well as discussing the orientated layered structure within the anisotropic materials.
Lab-on-Glass System for DNA Analysis using Thin and Thick Film Technologies
Authors: Caputo Domenico , Ceccarelli Matteo , de Cesare Giampiero , Nascetti Augusto , Scipinotti Riccardo
Published: June 2009

In this paper, we present a compact lab-on-chip system suited for label-free DNA analysis. The system can be fabricated on a conventional microscope glass slide using thin-film and thick-film technologies. It integrates a heating chamber, an electrowetting-based droplet handling system and a hydrogenated amorphous silicon (a-Si:H) photosensor array for DNA detection. At this stage of research we have designed and tested the individual functional units. The heating chamber incorporates a thin metal film heater optimized for uniform temperature distribution on a 1cm2area. A forward-biased a-Si:H p-i-n junction is used for temperature monitoring, achieving a linear temperature dependence with -3.3 mV/K sensitivity. The droplet-handling unit, relying on the electrowetting method, is designed to move the sample from the heating chamber to the sensor array. The unit includes a set of metal pads beneath a layer of PDMS that provides both the electric insulation of the electrodes and the hydrophobic surface needed by the electrowetting technique. The UV sensor array allows measuring the DNA absorbance variation at 254nm related to the hybridization between probe-molecules contained in the sample and reference target molecules immobilized on the sensor surface. A preliminary test to detect the hybridization between a 25-mer single-stranded oligonucleotides and denaturated pBR 322 4162-mer single-stranded oligonucleotides has been carried out successfully.
Resonant Microcavities Coupled to a Photonic Crystal Waveguide for Multi-channel Biodetection
Authors: Guillermain Elisa , Fauchet Philippe M.
Published: June 2009

Miniaturized and highly sensitive bio-sensors are attractive in various applications, such as medicine or food safety. Photonic crystal (PhC) microcavities present multiple advantages for rapid and accurate label-free optical detection. But their principle of operation (i.e. observation of a peak in transmission) makes their integration in serial arrays difficult. We present in this paper a multi-channel sensor consisting of several resonant PhC microcavities coupled to the same waveguide. The transmission spectrum shows as many dips as there are cavities, and each of the microcavities can act as an independent sensor. Preliminary results show the fabrication and characterization of a double-channel structure with small defects used as a solvent sensor.
Experimental Formation of Periodontal Structure Around Titanium Implants Utilizing Bone Marrow Mesenchymal Stem Cells: A Pilot Study
Authors: Marei Mona K. , Saad Manal M. , El-Ashwah Adham M. , El-Backly Rania M. , Al-Khodary Mohammed A.
Published: June 2009

Tissue engineering in the head and neck area, presents numerous advantages. One of the most remarkable advantages is that regeneration of only a small amount of tissue can be highly beneficial to the patient, particularly in the field of periodontal tissue regeneration. For decades, successful osseointegration has provided thousands of restorations that maintain normal function. With the increasing need to utilize dental implants for growing patients and enhance their function to simulate normal tooth physiology and proprioception, there appears to be an urgent need for the concept of periodontal tissue regeneration around dental implants. In the present work, 5 goats were used for immediate implant placement post canine teeth extraction. Each goat received 2 implant fixtures; the control side received a porous hollow root-form poly (DL-Lactide-co-Glycolide) scaffold around the titanium fixture, and the experimental side received the same scaffold but seeded with autogenous bone marrow–derived mesenchymal stem cells. One animal was killed 10 days postoperatively, and the others were killed after 1 month. The results showed that on the experimental side, periodontal-like tissue with newly formed bone was demonstrated both at 10 days and after 1 month, while the control specimens showed early signs of connective tissue regeneration around the titanium fixture at 10 days, but was not shown in the 1 month specimens. It can be concluded that undifferentiated mesenchymal stem cells were capable of differentiating to provide the 3 critical tissues required for periodontal tissue regeneration: cementum, bone, and periodontal ligament. This work may provide a new approach for periodontal tissue regeneration.
Implant Rehabilitation for a Patient With Hallerman-Streiff Syndrome: A Case Report
Authors: Abadi Behruz J. , Van Sickels Joseph E. , McConnell Thomas A. , Kluemper G. Thomas
Published: June 2009

Hallermann-Streiff syndrome is a rare genetic disorder characterized by craniofacial malformations, sparse hair, eye abnormalities, dental defects, degenerative skin changes, and short stature. The syndrome has many implications for dental treatment. Patients typically present with multiple missing and poorly formed teeth. The purpose of this case report is to discuss the overall management of a patient with Hallermann-Streiff syndrome by oral maxillofacial surgery, orthodontic treatment, and prosthodontic reconstruction.
Clinical characteristics in subcortical ischemic white matter disease
Authors: Alves Gilberto Sousa , Alves Carlos Eduardo de Oliveira , Lanna Maria Elisa de Oliveira , Ericeira-Valente Letice , Sudo Felipe Kenji , Moreira Denise , Engelhardt Eliasz , Laks Jerson
Published: June 2009

BACKGROUND: Vascular white matter lesions (WML) represent one of the main neuroimage findings in individuals older than 65 years and its clinical significance is still partially understood. OBJECTIVE: To describe and analyze the clinical profile of a high severity sample with WML focusing on the frontal executive control. METHOD: Outpatients (n=20) with high severity WML evaluated with magnetic resonance imaging were selected using the Fazekas scale. RESULTS: Most patients (n=17; 85%) presented an altered Trail Making Test ratio (section B/section A); on verbal fluency, 15 individuals (75%) performed below the cutoff score. Apathy (5.9 ± 4.65) and depression (3.05±3.67) were frequent as assessed by the Neuropsychiatric Inventory. The impairment in functional activities strongly correlated with apathy (r=0.814, p<0.001) and verbal fluency (r=0.744, p<0.001). CONCLUSION: Executive dysfunction, apathy, and ratio depression were the main characteristics found. Extension of WML may have distinct impact on the clinical picture, but further studies with methodological adjustments are necessary to provide more definitive conclusions.
Depressive symptoms and perception of quality of life in Parkinson's disease
Authors: Scalzo Paula , Kummer Arthur , Cardoso Francisco , Teixeira Antonio Lucio
Published: June 2009

BACKGROUND: Depression has been proposed as a major contributor to poor quality of life (QoL) in Parkinson's disease (PD). OBJECTIVE: To evaluate the relationship between depressive symptoms and QoL in subjects with PD. METHOD: Beck Depression Inventary (BDI) was used to evaluate depressive symptoms and Parkinson's Disease Quality of Life Questionnaire (PDQ-39) to assess the perception of the QoL. RESULTS: Thirty seven patients (19 male/ 18 female) with a typical onset PD and mean disease duration of 7.7 years were studied. Higher scores on BDI correlated with poorer perception of the QoL. This association occurred at the expense of the following PDQ39 domains: mobility, activities of daily living, social support, cognition and emotional well-being dimensions. PD severity also correlated with QoL. CONCLUSION: Our study corroborates the assumption that depressive symptoms contributed significantly to QoL in PD.
Effects of a cognitive modulator in the theta and alpha asymmetry during a typewriting task: a sensorimotor integration perspective
Authors: Cunha Marlo , Machado Sergio , Miana Luiz Cláudio , Machado Dionis , Bastos Victor Hugo , Velasques Bruna , Cagy Maurício , Basile Luis F. , Piedade Roberto , Ribeiro Pedro
Published: June 2009

This study aimed to elucidate cortical mechanisms and to identify the areas where occur such mechanisms due to interaction between bromazepam and motor learning. The sample was composed of 45 healthy subjects randomly distributed in 3 groups: placebo (n=15), bromazepam 3 mg (n=15) or bromazepam 6 mg (n=15). To perform the experimental task, subjects sat comfortably at a distance of approximately 20 cm from the typewriter. The typewriter keyboard was covered with a wooden box to avoid visual information about the hands' position. The typewriting task was performed concomitantly with EEG recording. ANOVA two-way results indicated a decreased asymmetry in sensorimotor areas in the experimental groups. Our interpretation is that moderate doses of bromazepam may improve performance on tasks with predictable elements to promote stability of psychomotor functions, but may also impair performance on tasks executed in unpredictable environments.
Performance of normal adults on Rey Auditory Learning Test: a pilot study
Authors: Teruya Leila Cardoso , Ortiz Karin Zazo , Minett Thaís Soares Cianciarullo
Published: June 2009

The present study aimed to assess the performance of healthy Brazilian adults on the Rey Auditory Verbal Learning Test (RAVLT), a test devised for assessing memory, and to investigate the influence of the variables age, sex and education on the performance obtained, and finally to suggest scores which may be adopted for assessing memory with this instrument. The performance of 130 individuals, subdivided into groups according to age and education, was assessed. Overall performance decreased with age. Schooling presented a strong and positive relationship with scores on all subitems analyzed except learning, for which no influence was found. Mean scores of subitems analyzed did not differ significantly between men and women, except for the delayed recall subitem. This manuscript describes RAVLT scores according to age and education. In summary, this is a pilot study that presents a profile of Brazilian adults on A1, A7, recognition and LOT subitem.
Potential risk factors for multiple sclerosis in Rio de Janeiro: a case-control study
Authors: Silva Kátia Regina Penha da , Alvarenga Regina Maria Papais , Fernandez y Fernandez Oscar , Alvarenga Hélcio , Thuler Luiz Claudio Santos
Published: June 2009

PURPOSE: To evaluate potential risk factors for the development of multiple sclerosis in Brazilian patients. METHOD: A case control study was carried out in 81 patients enrolled at the Department of Neurology of the Hospital da Lagoa in Rio de Janeiro, and 81 paired controls. A standardized questionnaire on demographic, social and cultural variables, and medical and family history was used. Statistical analysis was performed using descriptive statistics and conditional logistic regression models with the SPSS for Windows software program. RESULTS: Having standard vaccinations (vaccinations specified by the Brazilian government) (OR=16.2; 95% CI=2.3-115.2), smoking (OR=7.6; 95% CI=2.1-28.2), being single (OR=4.7; 95% CI=1.4-15.6) and eating animal brain (OR=3.4; 95% CI=1.2-9.8) increased the risk of developing MS. CONCLUSIONS: RESULTS of this study may contribute towards better awareness of the epidemiological characteristics of Brazilian patients with multiple sclerosis.
Predictive factors for neuromotor abnormalities at the corrected age of 12 months in very low birth weight premature infants
Authors: Mello Rosane Reis de , Silva Kátia Silveira da , Rodrigues Maura Calixto Cecherelli de , Chalfun Geórgia , Ferreira Rachel Carvalho , Delamônica Juliana Verçosa Rocha
Published: June 2009

BACKGROUND: The increase in survival of premature newborns has sparked growing interest in the prediction of their long-term neurodevelopment. OBJECTIVE: To estimate the incidence of neuromotor abnormalities at the corrected age of 12 months and to identify the predictive factors associated with altered neuromotor development in very low birth weight premature infants. METHOD: Cohort study. The sample included 100 premature infants. The outcome was neuromotor development at 12 months classified by Bayley Scale (PDI) and neurological assessment (tonus, reflexes, posture). A multivariate logistic regression model was constructed. Neonatal variables and neuromotor abnormalities up to 6 months of corrected age were selected by bivariate analysis. RESULTS: Mean birth weight was 1126g (SD: 240). Abnormal neuromotor development was presented in 60 children at 12 months corrected age. CONCLUSION: According to the model, patients with a diagnosis including bronchopulmonary dysplasia, hypertonia of lower extremities, truncal hypotonia showed a 94.0% probability of neuromotor involvement at 12 months.
Proton magnetic resonance spectroscopy in children with fetal alcohol spectrum disorders
Authors: Gonçalves Rita de Cássia Ferreira , Vasconcelos Marcio Moacyr , Faleiros Letícia Oliveira , Cruz Jr. Luiz Celso Hygino da , Domingues Romeu Cortes , Brito Adriana Rocha , Werner Jr. Jairo , Herdy Gesmar Volga Haddad
Published: June 2009

OBJECTIVE: To analyze the metabolic constitution of brain areas through proton magnetic resonance spectroscopy in children affected with fetal alcohol spectrum disorder compared with normal children. METHOD: The sample of this case-control study included eight boys with epidemiologic history of in utero exposure to alcohol (median age 13.6±3.8 years) who were diagnosed with fetal alcohol spectrum disorder, and eight controls (median age 12.1±3,4 years). An 8 cm³ single voxel approach was used, with echo time 30 ms, repetition time 1500 ms, and 128 acquisitions in a 1.5T scanner, and four brain areas were analyzed: anterior cingulate, left frontal lobe, left striatum, and left cerebellar hemisphere. Peaks and ratios of metabolites N-acetylaspartate, choline, creatine, and myo-inositol were measured. RESULTS: Children with fetal alcohol spectrum disorder showed a decrease in choline/creatine ratio (p=0.020) in left striatum and an increase in myo-inositol/creatine ratio (p=0.048) in left cerebellum compared with controls. There was no statistically significant difference in all peaks and ratios from the anterior cingulate and frontal lobe between the two groups. CONCLUSION: This study found evidence that the left striatum and left cerebellum are affected by intrauterine exposure to alcohol. Additional studies with larger samples are necessary to expand our knowledge of the effects of fetal exposure to alcohol.
C5 and C6 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. In this work, C5 and C6 superior limb dermatomes were studied. The method consisted of comparing clinical signs and symptoms with conduction studies, electromyographical data, neurosurgical findings, and imaging findings obtained by computerized tomography (CT) or magnetic resonance imaging (MRI), for each patient. Data analysis from superior members in 18 patients suggests that C5 is located in the lateral aspect of the shoulder and arm, and C6 in the lateral aspect of the forearm and 1st, 2nd, and 3rd fingers. To our knowledge this is the first time that C5 and C6 human dermatomes have been studied by all the following methods together: clinical, electromyographical, CT and MR imaging, and surgical findings.
Early shunt complications in 46 children with hydrocephalus
Authors: Braga Moisés Heleno Vieira , Carvalho Gervásio Teles C. de , Brandão Rafael Augusto Castro Santiago , Lima Franklin Bernardes Faraj de , Costa Bruno Silva
Published: June 2009

OBJECTIVE: To determine the causes of early shunt complications in 46 children with hydrocephalus. METHOD: A retrospective study was conducted on 46 children submitted to ventriculoperitoneal shunt surgery between February 2005 and February 2007. RESULTS: Thirteen (28%) patients presented complications, which were due to infection in 9 (69%) and to malfunction of the shunt system in 4 (31%).The mean number of surgical procedures performed on patients who presented complications was 2.8 per patient, with a total of 46 surgeries in this group. All patients with infectious complications were identified during their hospital stay. CONCLUSIONS: Infection was the most common complication. The infection rate was proportional to the length of hospital stay. All patients with hydrocephalus due to tumors or myelomeningocele presented complications. A higher incidence of infections was observed in children older than 2 years.
Konstantin N. Tretiakoff in Brazil a historical perspective and discussion of his contribution to brazilian neuroscience
Authors: Andrade Luiz Augusto F. , Selikhova Marianna , Lees Andrew J.
Published: June 2009

The Hospício de Juquery, near the city of São Paulo (Brazil) was founded in 1896 and after few years it was decided that the institution should have the best possible facilities to study neuropathology. In 1921, a young psychiatrist, Antonio Carlos Pacheco e Silva was sent to the Hôpital de la Salpêtrière (Paris) to study neuropathology. There, Pacheco e Silva (later Prof.Pacheco e Silva) befriended Konstantin N. Tretiakoff accepted an invitation to become the first Chairman of the newly created neuropathology department of the Hospício de Juquery. During his stay in this institution, from 1922 to 1924 or early 1925, he worked very hardly and produced many publications. Here we present and comment some of the papers he published in a Journal (Memórias do Hospício de Juquery - "Memoirs de l'Hôspice de Juquery"), which had been recently created and present some information of this poorly known period of his life.
Pituitary tumor apoplexy
Authors: Chang Claudia V. , Felicio Andre C. , Toscanini Andrea Cecilia , Teixeira Manoel Jacobsen , Cunha-Neto Malebranche Berardo Carneiro da
Published: June 2009

Pituitary tumor apoplexy is a medical emergency due to acute infarction or hemorrhage in the pituitary gland. In this review, the authors discuss the sellar anatomy, the pituitary gland and adenomas' vascularization and the general aspects of the syndrome such as its ethiopatogenesis, predisposing factors, clinical features, treatment and prognosis.
Detecção de HPV na mucosa oral e genital pela técnica PCR em mulheres com diagnóstico histopatológico positivo para HPV genital
Authors: Castro Therezita M. Peixoto Patury Galvão , Bussoloti Filho Ivo , Nascimento Velber Xavier , Xavier Sandra Doria
Published: June 2009

A infecção do papilomavírus humano (HPV) é uma das mais freqüentes doenças sexualmente transmissíveis em todo o mundo. A relação entre o HPV genital e oral permanece incerta, assim como o seu papel na carcinogênese oral. O objetivo deste estudo foi verificar a presença do DNA do HPV na mucosa oral e genital de mulheres com infecção genital por HPV, pela técnica de reação em cadeia de polimerase (PCR). FORMA DE ESTUDO: Coorte transversal. MATERIAL E MÉTODO: Trata-se de um estudo piloto, prospectivo, com 30 mulheres, idade de 14 a 51 anos, portadoras de infecção genital por HPV confirmada pelo exame de histopatológico. Todas as pacientes foram submetidas a exame e coleta por raspagem da cavidade oral e genital para pesquisa do DNA do HPV pela técnica PCR. RESULTADOS: Nenhuma das amostras da cavidade oral foi positiva para HPV, enquanto no genital, o HPV foi detectado em 17 (57%) das 30 pacientes, principalmente o HPV 6b e 16. CONCLUSÃO: Os resultados mostraram maior porcentagem do HPV genital em relação à cavidade oral, e sugerem que o HPV genital não parece ser fator predisponente para a infecção oral no mesmo paciente.
Avaliação crítica de 33 pacientes com bócio mergulhante tratados cirurgicamente por cervicotomia
Authors: Neves Murilo Catafesta Das , Rosano Marcello , Hojaij Flávio Carneiro , Abrahão Márcio , Cervantes Onivaldo , Andreoni Danielle Macellaro
Published: June 2009

A possibilidade de ser necessário um acesso combinado, com uma incisão cervical e outra torácica, torna o tratamento do bócio mergulhante um desafio tanto no pré quanto no intra-operatório. Discutimos uma padronização da técnica cirúrgica para minimizar a necessidade da abordagem torácica, tornando o bócio mergulhante uma patologia tratável cirurgicamente, por uma única incisão cervical, e com baixos índices de complicações. OBJETIVO: Avaliar a abordagem cirúrgica do bócio mergulhante por cervicotomia e analisar as complicações cirúrgicas. MATERIAL E MÉTODOS: Foi realizada uma coorte histórica com corte transversal por análise retrospectiva dos prontuários de pacientes submetidos à tireoidectomia no período de maio de 2002 a julho de 2007. Um total de 316 pacientes foi submetido à tireoidectomia sendo 33 (10,4%) por bócio mergulhante. RESULTADOS: Todos os 33 pacientes foram tratados cirurgicamente por via cervical sem necessidade de esternotomia. Não foram observadas lesões definitivas de nervo laríngeo inferior ou hipoparatireoidismo definitivo. Apenas 2 pacientes apresentaram paresia de nervo recorrente e 2 pacientes foram reabordados por hematoma cervical. CONCLUSÃO: Pacientes com bócio mergulhante podem ser tratados cirurgicamente por uma única incisão cervical com segurança e baixos índices de complicação.
Alterações dos potenciais evocados auditivos do tronco encefálico em pacientes com esclerose múltipla
Authors: Lima Tania Mara Assis , Crato Aline Nascimento , Mancini Patrícia Cotta , Simões Lília Correa , Gonçalves Denise Utsch
Published: June 2009

A presença de alterações nos potenciais evocados auditivos do tronco encefálico (PEATE) em indivíduos com doenças desmielinizantes sugere lesão do tronco encefálico. OBJETIVOS: O objetivo do presente estudo foi avaliar a incidência de alterações auditivas e dos PEATE em indivíduos com esclerose múltipla (EM). MATERIAL E MÉTODO: Participaram do estudo 16 pacientes do sexo feminino e 9 do sexo masculino com diagnóstico definido de EM. Testes audiométricos e pesquisa dos PEATE foram realizados em todos os indivíduos. Para a classificação dos PEATE utilizou-se a classificação proposta por Jerger (1986) na análise da morfologia das ondas. FORMA DE ESTUDO: Estudo de coorte contemporânea com corte transversal. RESULTADOS: Dos 50 PEATE realizados, 70% foram classificados como tipo I (resposta normal) pela classificação de Jerger. Considerando-se como alterados os PEATE dos tipos II, III, IV ou V da classificação de Jerger em pelo menos um dos lados, encontrou-se 31,25% de alterações no sexo feminino e 44,44% no masculino, totalizando 36%. CONCLUSÕES: Estes achados enfatizam a relevância do estudo dos PEATE em casos de suspeita clínica de doenças desmielinizantes e naqueles com diagnóstico definido de EM.
Uso de manometria computadorizada para estudo do espasmo do segmento faringoesofágico em pacientes com voz traqueoesofágica inadequada antes e após aplicação de toxina botulínica
Authors: Chone Carlos T. , Seixas Vinícius Oliveira , Andreollo Nelson A. , Quagliato Elizabeth , Barcelos Irene H. K. , Spina Ana L. , Crespo Agrício N.
Published: June 2009

Voz traqueoesofágica (VTE) com prótese fonatória (PF) é método eficaz e reproduzível na reabilitação vocal após laringectomia total (LT), impedida pelo espasmo do segmento faringoesofágico (SFE). A manometria computadorizada (MC) é novo método objetivo e direto de avaliação do SFE. OBJETIVO: Análise objetiva do espasmo do SFE, com MC, antes e após aplicação de toxina botulínica (TB). DESENHO DO ESTUDO: Prospectivo clínico. MATERIAL E MÉTODOS: Análise de oito pacientes consecutivos submetidos à LT com VTE e PF, sem emissão vocal, com espasmo do SFE à videofluoroscopia, considerado padrão ouro para detecção de espasmo. Todos trataram o espasmo com injeção de 100 unidades de TB no SFE. Avaliação constituiu-se de videofluoroscopia e MC do SFE, antes e após aplicação de TB. RESULTADOS: Houve diminuição na pressão do SFE à MC, após injeção de TB em todos. A média de pressão do SFE à MC, nos oito pacientes, antes da aplicação de TB foi de 25.36 mmHg e após foi de 14.31 mmHg (p=0,004). Houve emissão vocal sem esforço e melhora do espasmo do SFE à videofluoroscopia após o uso da TB. CONCLUSÃO: Foi observada diminuição na pressão do SFE após injeção da TB à MC em todos os pacientes, com melhora do espasmo à videofluoroscopia.