bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-Dimensional and Multi-Experimental Modeling of Polycrystalline Cu(In,Ga)Se2 Solar Cells
Authors: Metzger W. K. , Gloeckler M. , Ahrenkiel R. K.
Published: November 2011

We use two-dimensional simulations to explore if charged columnar grain boundaries (GBs) in Cu(In,Ga)Se2 (CIGS) solar cells increase device performance. Although the simulations confirm that charged GBs can increase photocurrent by forming minority-carrier collection channels, this generally occurs at the expense of overall efficiency. Furthermore, improvements in photocurrent require significant GB minority collection beyond a diffusion length of the space-charge region. This collection from deep within the base can be detected by quantum efficiency (QE) spectra, electron-beam-induced current (EBIC) experiments, near-field scanning optical microscopy (NSOM), and fast photoluminescence decay. Simulations of all these experiments indicate that GB charge sufficient to significantly increase photocurrent collection is generally inconsistent with actual observations.
Novel Wide-Band-Gap Ag(In1-xGax)Se2 Thin Film Solar Cells
Authors: Nakada Tokio , Yamada Keiichiro , Arai Ryota , Ishizaki Hiroki , Yamada Naoomi
Published: November 2011

Ag(In1-xGax)Se2 thin films have been deposited on Mo-coated soda-lime glass substrates by the three-stage process using a molecular beam epitaxy (MBE) system. We found a remarkable decrease in the substrate temperature during the 2nd stage in which the film composition changes to a Ag excess. A single phase chalcopyrite AIGS thin film with a slightly Ag poor composition was obtained by using the temperature monitoring composition method. The cell performance of the AIGS thin film solar cell was found to strongly depend on the Ga/(In+Ga) and Ag/(In+Ga) atomic ratios.

A high efficiency wide-gap (Eg=1.7eV) Ag(In0.2Ga0.8)Se2 thin film solar cell with a total-area efficiency of 9.3% (10.2% active area efficiency), Voc = 949mV, Jsc = 17.0 mA/cm2, FF = 0.577, and total area = 0.42 cm2 was achieved. The junction formation mechanism of AIGS devices is discussed based on electron beam induced current (EBIC) and scanning capacitance microscopy (SCM) analyses.
Electronic Properties of Modified CuGaSe2 Solar Cells
Authors: AbuShama Jehad A. , Johnston Steve W. , Young David L. , Noufi Rommel
Published: November 2011

We report on the electronic properties of the state-of the art surface-modified CuGaSe2 solar cells. We compare between the 10.2%-efficient surface-modified and the 9.53%-efficient unmodified CuGaSe2 solar cells. We examined our cells using deep level transient spectroscopy (DLTS) and drive level capacitance profiling (DLCP). The DLTS data for the modified CGS exhibits minority traps with activation energies ranging from Ec — 0.3 to Ec — 0.6 eV, whereas that for the pure CGS exhibits minority traps with activation energies ranging from Ec — 0.06 to Ec — 0.1 eV (where Ec is the energy of electrons at the conduction band minimum). While varying the filling pulse duration, we observed the gradual increase in the amplitude of the DLTS signal for these states until it apparently saturates at a pulse duration of ˜1s for the 10.2% cell, and 0.05 s for the 9.53% cell. Increasing the duration of the filling pulse also results in broadening of the DLTS signals and shifting of the maximum of these signals towards lower temperature, whereas the high-temperature sides coincide. Using a model that allows us to distinguish between bandlike states and localized ones based on the dependence of the shape of their DLTS-signal on the filling-pulse duration, we relate the electron trap to bandlike states. The DLCP data shows that the 10.2% cell has a lower carrier concentration, a more uniform defect density profile, a larger depletion width, and a higher drift collection length for photo-generated carriers as compared to our 9.53% CuGaSe2 cell. We also recorded the transient capacitance versus time and found that the 10.2% has responded differently compared with the 9.53% one. The transient capacitance decay curves for these two cells are different.
Current Transients in CdS/CdTe Solar Cells
Authors: Fahrenbruch Alan
Published: November 2011

Current transient responses to voltage and illumination steps are investigated to elucidate the mechanisms involved in carrier transport in CdS/CdTe cells. For most cells, the response to a dark, forward-bias step after a long dark soak at zero bias is a current growth curve For one such cell, the magnitude of the transient is ≈ 22% of the starting value with half of the growth occurring within ≈ 10 sec, the other half requiring 1000's of seconds. The effect is completely reversible and a mirror-image decay curve at zero bias after dark bias-on equilibration can be measured. Similarly, a complex of growth and decay curves are observed on application of illumination steps with constant bias. Similar transients have been observed by McMahon [1] and del Cueto et al. [2]. This paper is a survey of these effects in cells from 3 different fabricators.

These transients, with varying magnitudes and directions, were seen in all the cells studied. In general, the better the cell, the smaller the magnitudes of the transients. They range from changes by factors of 10 for pathological cells to subtle fast transients (1-2%) in excellent cells.

Beside the important implications these transients have for accurate measurements of cell efficiency and stability, they provide clues about the carrier transport mechanisms. One of the mechanisms proposed involves the occupation of deep donor traps with small hole cross sections, changing their recombination kinetics. The second hypothesis involves the modulation of the junction barrier profile by changing the charge on deep acceptors and donors by carrier trapping, leading to a change in the effective junction barrier height. A third involves defect mutation such as that of [Cui] donors into [VCd- Cu] acceptor complexes, depending on the position of the quasi-Fermi levels.
Detailed study of metastable effects in the Cu(InGa)Se2 alloys: Test of defect creation models
Authors: Lee JinWoo , Heath Jennifer T. , Cohen J. David , Shafarman William N.
Published: November 2011

We have investigated metastable changes to Cu(InGa)Se2 solar cells in response to infrared optical exposure and forward injection current. Using the drive level capacitance profiling and admittance spectroscopy techniques, we are able to distinguish changes in the free hole carrier concentration from those of a deeper bulk trap. For both types of treatment, changes in these concentrations clearly follow a 1:1 ratio, in agreement with recent predictions of a microscopic model proposed by Lany and Zunger. The creation kinetics follow a strongly sub-linear power law at 250K, and we demonstrate that we can account for this using rate equations in which the metastable effect is initiated by electron capture into an empty defect state. The dependence on time and light intensity is (time) 0.22± 0.03 and (intensity) 0.53± 0.06, except at high light intensities where saturation is observed.
Does CdTe Deposition Affect the Impurity Profile in Sputtered CdS Window Layers?
Authors: Emziane Mahieddine , Durose Ken , Halliday Douglas P. , Bosio Alessio , Romeo Nicola
Published: November 2011

We report a multi-element study of impurities in CdS window layers by dynamic and quantitative SIMS. Two CdS/TCO/glass samples, grown separately using nominally the same conditions, were considered. In203:F grown on soda lime glass was used as TCO followed by a sputtered CdS layer. One of the samples was subsequently used as a substrate for growth of CdTe by CSS. SIMS was carried out on both samples, and O, Na, Si, Cl, Sb, In, Zn, Sn, Pb, Cu, Te, S and Cd were depth profiled. It was shown that before CdTe growth, most of the impurity elements showed flat levels in the CdS ranging from 2-3×1020 cm-3 for Zn and O to 2-3×1017 cm-3 for Na, Cl, Sb and Te. Si was found to segregate at the CdS/TCO interface with a maximum level of 1018 cm-3. However, following CdTe growth, the impurities in the CdS layer showed higher concentrations and different profile shape compared to those before CdTe growth. Some of the impurities also showed a diffusion-like profile following the CdTe growth as compared to before. Possible explanations of these changes are discussed in terms of the purity of the starting materials and the growth environments, as well as the diffusion from the TCO and glass.
Properties of Cu(In,Ga)Se2:Fe Thin Films For Solar Cells
Authors: Sakurai Keiichiro , Shibata Hajime , Nakamura Satoshi , Yonemura Minoru , Kuwamori Shinpei , Kimura Yasuyuki , Ishizuka Shogo , Yamada Akimasa , Matsubara Koji , Nakanishi Hisayuki , Niki Shigeru
Published: November 2011

We have fabricated CIGS:Fe polycrystalline thin films using a standard three-stage method, and investigated the effects of Fe doping on cell performances. The Ga / (In+Ga) ratio was varied between 0.3 ˜ 1.0 (= CGS), and the Fe concentration was varied between 0.0 ˜ 1.2 mol%. The films were characterized by various means, including the cell performance. Increment of the grain size with higher Fe content was observed. Redshift with higher Fe content was observed in the absorbance spectra. The spectral response of the fabricated solar cells deteriorated with higher Fe content, from the long wavelength side.
Formation and characterization of the CuIn(S,Se)2/buffer layer interface in electrodeposited solar cells
Authors: Naghavi N. , Hubert C. , Roussel O. , Sapin L. , Lamirand M. , Guillemoles J. F. , Lincot D. , Kessler J. , Kerrec O.
Published: November 2011

This paper presents the influence of the solution chemistry of chemical bath deposition (pH and complexing agents) on the performance of CuIn(S,Se)2 cells after an initial CN treatment. It is shown that it is possible to modify the deposition conditions of the CdS by increasing the pH of the solution and by replacing the complexing agent (ammonia) by citrate ions. Both NH3 based and citrate based process give very homogenous and covering thin films. However, in the case of the citrate based process a decrease of open circuit voltage (Voc) and fill factor (FF) and thus of the cell efficiencies is observed. This points out that the main role of the buffer layer is not only related to the specific properties of the CdS itself but also to the near surface modifications of the CuIn(S,Se)2 caused by the presence of the complexing agent in the bath.
CdSe Thin Film Preparation by Unipolar Current Pulse Electrodeposition Technique
Authors: Jain Kiran , Karar N. , Chandra H.
Published: November 2011

CdSe thin films were prepared using unipolar current pulse electrodeposition technique on fluorine doped SnO2 coated glass plates. The electrodeposition bath consisted of aqueous solution including CdSO4, SeO2 and pH was adjusted using H2SO4. Growth of CdSe was accomplished under wide range of variables like current density, pulse on and off time in order to elucidate the effect on crystalline structure, grain size and optical properties. A low current density and increased off time favored grain orientation and crystallinity. Increased current density and on time favored grain size reduction.
Optimization of RF-Sputtered ITO Films for High NIR Transparency at Low Deposition Temperature
Authors: Zhou J. , Wu X. , Gessert T.A. , Yan Y. , Teeter G. , Moutinho H.R.
Published: November 2011

Sn-doped indium oxide (ITO) films deposited at temperatures <250°C by r.f. magnetron sputtering are investigated for use as transparent back-contact electrodes to CdS/CdTe top cells in two-junction, mechanically stacked tandem-cell designs. Results show that carrier mobility increases with substrate temperature while beneficial changes in carrier activation occurs at a substrate temperature ~230°C. Small additions of oxygen to the sputtering environment are effective at reducing near infrared (NIR) absorption. Control of these deposition parameters has produced ITO films with NIR absorption (860–1300 nm) < 10%, and electrical resistivity of <1x10-3 ohm-cm.
Optical, Structural and Electronic Properties of CuInS2 Solar Cells Deposited by Reactive Magnetron Sputtering
Authors: Unold T. , Enzenhofer T. , Ellmer K.
Published: November 2011

CuInS2 thin films have been prepared by reactive magnetron sputtering from metallic targets in an Ar/H2S atmosphere. The Cu/In ratio and substrate temperature have been varied and absorber layers were processed to solar cell devices using the HMI baseline process. Device efficiencies up to 8.8 % have been achieved. The electronic and optical properties of the solar cell devices were analyzed by Scanning Electron Microscopy, Raman, photoluminescence, current-voltage and quantum efficiency measurements. Raman measurements indicate that Cu-Au defect ordering is present in some of the films, which can be eliminated by appropriate choice of the growth parameters. Photoluminescence measurements show spectra very similar to the spectra found for cells from the two-step sequential process indicating a similar defect structure in these films. No principle obstacles to establishing a one-step reactive magnetron sputtering process for CuInS2 solar cell absorbers have been identified.
Synchrotron-based spectroscopy for the characterization of surfaces and interfaces in chalcopyrite solar cells
Authors: Lauermann Iver , Pistor Paul , Kötschau Immo , Bär Marcus
Published: November 2011

In this paper we describe synchrotron based, state-of-the-art spectroscopic methods for the analysis of surfaces and interfaces in thin film photovoltaic devices, their merits and their limitations. Using results obtained with the “CISSY” end station at the BESSY synchrotron in Berlin, Germany, we show how surface sensitive Synchrotron excitedX-rayPhotoelectronSpectroscopy(SXPS)andSoftX-rayEmissionSpectroscopy (SXES), which yields compositional and chemical depth information in the ten to hundred nm scale, have increased our knowledge of the chemistry of surfaces and buried interfaces of these systems.
A comparison of in situ As doping with ex situ CdCl2 treatment of CdTe solar cells
Authors: Barrioz Vincent , Rowlands Rachael L. , Jones Eurig W. , Irvine Stuart J. C. , Zoppi Guillaume , Durose Ken
Published: November 2011

A comparison has been made of MOCVD grown CdTe/CdS solar cells processed either by ex situ annealing with CdCl2 or doping with arsenic, in situ, together with various optional anneals. A materials comparison was made of both routes using Jsc measurements on arrays of gold contacts to the CdTe. The Jsc increased from around 1 mA cm-2 for undoped and unannealed layers to a range of 25-30 mA cm-2 for CdCl2 annealed layers. In situ arsenic doping resulted in Jsc values up to 18 mA cm-2. The annealing characteristics were very different for these films, compared with the CdCl2 annealed films, with annealing at 500°C dramatically reducing the Jsc. Only annealing under nitrogen at 400°C produced an improvement in Jsc and further evidence from SIMS analysis suggests that hydrogen passivation of the arsenic dopant may have a significant effect on the dopant activity.
Application of Advanced Microstructural and Microchemical Microscopy Techniques to Chalcopyrite Solar Cells.
Authors: Lei Changhui , Li Chun-Ming , Rockett Angus , Robertson I. M. , Shafarman W.
Published: November 2011

Analytical TEM techniques have been used to characterize the structure and chemistry of chalcopyrite solar cell devices produced by elemental evaporation using a bi-layer process at Ts=400°C and Ts=550°C. Dislocations, stacking faults, twins and voids exist in both materials but at a reduced density at the higher deposition temperature. The higher processing temperature also improved the density and structure of the grain boundaries and created a less rough surface. The CdS layer coats the surface conformally, although the roughness impacts the structure. CdS fills the grooves in the surface and infiltrates lower density grain boundaries to significant depths. The chemistry of the grain boundaries does not appear to be significantly impacted by the presence of the Cd and S.
Structural Properties of Ag-Based Chalcopyrite Compound Thin Films for Solar Cells
Authors: Ishizaki Hiroki , Yamada Keiichiro , Arai Ryouta , Kuromiya Yasuyuki , Masatsugu Yukari , Yamada Naoomi , Nakada Tokio
Published: November 2011

AgGa5Se8 and Ag(In1-xGax)Se2 thin films with different Ag/Ga atomic ratios have been deposited on the corning 1737 glass substrates by molecular beam epitaxy (MBE) system. This crystallographic property of AgGa5Se8 thin films has been investigated by x-ray diffraction and rietveld analysis. These films had the tetragonal structure with the space group of P-42m, regardless of Ag/Ga atomic ratio. The lattice parameters and the optical band gap energy decreased with an increase in the Ag/Ga atomic ratio. Thus, the structural and optical properties of these AgGa5Se8 thin films were controlled by the Ag/Ga atomic ratio.
Photostimulated Changes of Electrical Characteristics of Ag/CdTe Thin Film Structures
Authors: Dzhafarov T.D. , Caliskan M.
Published: November 2011

Electrical, optical and structural properties of Ag/CdTe structures exposed to thermal (in dark) and photoannealing (under illumination) have been studied. The effective diffusion coefficie nt of Ag in CdTe films have been estimated from resistance versus duration of annealing curves. In the range of 280-420°C the effective coefficient of thermal diffusion (Dt) and photodiffusion (Dph) are described as Dt= 1.9x105exp (-1.60/kT) and Dph =8.7x103exp(-1.36/kT). The acceleration of Ag diffusion under illumination was tentatively attributed to photoionization of Ag increasing the interstitial flux of silver. Ag/CdTe structures exposed to annealing were characterized by X-ray diffraction (XRD), I-V, C-V, conductivity-temperature and optical transmission measurements. In XRD patterns of annealed Ag/CdTe structures, besides the intensive (111) peak of cubic CdTe, the weak peaks of Ag2Te phase are also present. The temperature dependence of conductivity of annealed Ag/CdTe structures showed the energy levels 0.13 eV.
Analysis of Proton Induced Defects in Cu(In,Ga)Se2 Thin-Film Solar Cells
Authors: Kawakita Shirou , Imaizumi Mitsuru , Kibe Koichi , Yoda Shinichi , Ohshima Takeshi , Itoh Hisayoshi , Yamaguchi Masafumi
Published: November 2011

We investigated radiation-induced defects in CIGS solar cells with a solar-cell simulator to analyze the spectral response of the irradiated cells. The damage constant of the minority-carrier diffusion length of the cells irradiated with 1 MeV protons was determined to be 3.5 ×10-5. This analysis led to the relation between the defect introduction rate and proton energy, and was obtained using the same method, as was the defect annealing rate. This result agreed well with that estimated from an analysis of changes in short-circuit current degradation.
Physical Vapor Deposition Synthesis of Cu3BiS3 for Application in Thin Film Photovoltaics
Authors: Gerein Nathan J. , Haber Joel A.
Published: November 2011

The development of novel solar absorbers and device configurations that incorporate only materials which are cost effective, abundant, and non-toxic may be required for widespread deployment of photovoltaics. Cu3BiS3 (Eg=1.2 eV) has been previously reported to be a suitable solar absorber for use in thin film photovoltaic devices. We have developed a physical vapor deposition synthesis for Cu3BiS3, and will employ combinatorial methods to identify novel device configurations in an effort to produce a device exhibiting sufficient efficiency to capture the interest of the photovoltaics community.
Thin CuInS2 Films Prepared by MOMBE: Interface and Surface Properties
Authors: Pettenkofer C. , Lehmann C. , Calvet W.
Published: November 2011

CuInS2 films were prepared on Si(111) by MOMBE using standard MBE Cu and In sources and Ditertbutyldisulfide (TBDS) as an organic sulfur precursor. The films were analyzed in situ by XPS, LEED and UPS. Deposition at 250°C yields chalcopyrite films [1] with admixtures of CuSi2 and CuIn alloys. Deposition at higher temperatures up to 550°C was used to clarify the feasibility of the process. High quality LEED diffraction patterns show epitaxial growth but CuSi2 precipitations are still observed for deposition on Si(111). A buffer layer of indiumsulfide showed no considerable effect on the interface morphology. The obtained LEED pattern are in accordance with the epitaxial relation Si{111}||CuInS2{112}. Even for temperatures as high as 550°C no incorporation of Carbon or residual hydrocarbons in the film or adsorbed at the surface were detected.
Cello Measurements of CIGS and μcSi Solar Cells
Authors: Mathijssen Stefan , Carstensen Jürgen , Föll Helmut , Voorwinden Georg , Stiebig Helmut
Published: November 2011

The CELLO (solar celllocal characterization) technique, which allows to measure all parameters of a solar cell locally with high spatial resolution, is applied for the first time for thin film solar cells based on Cu(In,Ga)Se2 (CIGS) and micro-crystalline Si (μcSi). Results for local effective serial resistance, photocurrent and current/voltage at the working point will be presented, demonstrating the applicability of CELLO to thin film solar cells. Based on the measurements, quantitative predictions for the potential of these cells will be made.
Open-Circuit Voltage Decay in CdTe/CdS Solar Cells
Authors: Price Kent , Cooper Kevin , Lacy Chris
Published: November 2011

Open-Circuit Voltage Decay (OCVD) is a common technique used to characterize numerous semiconductor devices. However, to the knowledge of the authors, the technique has not previously been applied to CdTe-based solar cells. We use a simple setup consisting of a function generator, rectifying diode, and digital oscilloscope to measure the dark open circuit voltage decay as a function of time across a CdTe solar cell. We find the decay to be described by the equation v(t) = v0 + A1exp (–t/τ1) + A2exp (–t/τ2) where v is the voltage, t is time, τ1 and τ2 are characteristic decay times, and A1, A2 and v0 are constants. The two characteristic decay times are on the order of 10 μs and 500 μs. The relative contribution of the two decay times depends on the magnitude of the initial applied voltage pulse. We will describe preliminary results on the correlation between the OCVD and solar cell performance, including the effects of light-soaking on OCVD behavior.
Highly Mismatched Alloys for Intermediate Band Solar Cells
Authors: Walukiewicz W. , Yu K. M. , Wu J , Ager J. W. , Shan W. , Scrapulla M. A. , Dubon O. D. , Becla P.
Published: November 2011

It has long been recognized that the introduction of a narrow band of states in a semiconductor band gap could be used to achieve improved power conversion efficiency in semiconductor-based solar cells. The intermediate band would serve as a “stepping stone” for photons of different energy to excite electrons from the valence to the conduction band. An important advantage of this design is that it requires formation of only a single p-n junction, which is a crucial simplification in comparison to multijunction solar cells. A detailed balance analysis predicts a limiting efficiency of more than 50% for an optimized, single intermediate band solar cell. This is higher than the efficiency of an optimized two junction solar cell. Using ion beam implantation and pulsed laser melting we have synthesized Zn1-yMnyOxTe1-x alloys with x<0.03. These highly mismatched alloys have a unique electronic structure with a narrow oxygen-derived intermediate band. The width and the location of the band is described by the Band Anticrossing model and can be varied by controlling the oxygen content. This provides a unique opportunity to optimize the absorption of solar photons for best solar cell performance. We have carried out systematic studies of the effects of the intermediate band on the optical and electrical properties of Zn1-yMnyOxTe1-x alloys. We observe an extension of the photovoltaic response towards lower photon energies, which is a clear indication of optical transitions from the valence to the intermediate band.
Design of a window layer for flexible Cu(In,Ga)Se2 thin film solar cell devices
Authors: Kaufmann Christian A. , Neisser Axel , Klenk Reiner , Scheer Roland , Schock Hans-Werner
Published: November 2011

For laboratory scale devices the transfer of the Cu(In,Ga)Se2 (CIGSe) thin film technology from a rigid float glass substrate to flexible titanium foil is achieved. Here we will highlight the effect of the rough, flexible substrate on the electrical and optical characteristics of the transparent window layers of such devices. The roughness of the substrate may give rise to changes in sheet resistance of the transparent front contact and in the reflectivity of the completed device. However, the devices deposited onto the kind of titanium foil substrate used in this work are smooth enough not to affect the sheet resistance; nevertheless optical effects are enough to affect the process window for an antireflective coating. With the use of an antireflective coating, a maximum efficiency of 17.4% could be reached for 0.5 cm2 area devices on glass.
Understanding Aniline Surface Treatment of CdTe
Authors: Dobson Kevin D. , Einstein Stephanie A. , Sadowsky Daniel D. , McCandless Brian E. , Birkmire Robert W.
Published: November 2011

Surface etching of CdTe under illumination in aqueous aniline-based solutions has been investigated. Analysis of treated samples shows the formation of crystalline Te on the CdTe surface. Analysis of bath and treatment conditions indicated the presence of aniline, Cl- ions, dissolved O2, consistent illumination and careful control of pH as critical for successful surface etching. A photocatalytic mechanism is proposed for the reaction, where CdTe is etched by H2O2 or similar, generated through reduction of dissolved O2 by conduction band electrons and complemented by oxidation of aniline. The generated Te is stable in the bath and the treatment provides reproducible surfaces. CdTe/CdS devices of 12% conversion efficiency were processed with 30 min aniline treatments. The toxicity of aniline is a concern and criteria for possible substitutes are discussed.
The Effectof Multiple Vectors on Arbovirus Transmission
Authors: Lord Cynthia C.
Published: November 2011

Many mosquito-borne arboviruses have more than one competent vector. These vectors may or may not overlap in space and time, and may interact differently with vertebrate hosts. The presence of multiple vectors for a particular virus at one location over time will influence the epidemiology of the system, and could be important in the design of intervention strategies to protect particular hosts. A simulation model previously developed for West Nile and St. Louis encephalitis viruses andCulex nigripalpuswas expanded to consider two vector species. These vectors differed in their abundance through the year, but were otherwise similar. The model was used to examine the consequences of different combinations of abundance patterns on the transmission dynamics of the virus. The abundance pattern based onCx. nigripalpusdominated the system and was a key factor in generating epidemics in the wild bird population. The presence of two vectors often resulted in multiple epidemic peaks of transmission. A species which was active in the winter could enable virus persistence until another vector became active in the spring, summer, or fall. The day the virus was introduced into the system was critical in determining how many epidemic peaks were observed and when the first peak occurred. The number of epidemic peaks influenced the overall proportion of birds infected. The implications of these results for assessing the relative importance of different vector species are discussed.
Electrochemical Behavior of Titanium in Artificial Saliva: Influence of pH
Authors: Abey Savithri , Mathew Mathew T. , Lee Damian J. , Knoernschild Kent L. , Wimmer Markus A. , Sukotjo Cortino
Published: November 2011

Titanium is the most common material chosen for dental implants because it is highly corrosion resistant because it constantly reforms a protective passive film layer. The formation and composition of the passive film layer is dependent on the environmental conditions. If the stable oxide layer is damaged, the titanium surface underneath can corrode. The purpose of this study was to determine if basic corrosion of commercially pure titanium (CpTi) alloy in artificial saliva was affected by pH and to understand the corrosion kinetics/mechanisms of CpTi as a function of pH. In this study, titanium alloy discs were subjected to corrosion tests. Before the tests, all samples were cleaned and polished using standard metallographic preparation methods. Artificial saliva was used as the testing medium. The following pH values were tested: 3.0, 4.5, 6.0, 6.5, 7.5, and 9.0. Different pH values were achieved by adding lactic acid (acidic) or NaOH (basic) in appropriate amounts. Potentiodynamic curves indicated behavior change at each pH. In addition, the corrosion current density value determined from the potentiodynamic curve exhibited the poorest corrosion resistance for pH 7.5. The Nyquist plot (from the electrochemical impedance spectroscopy results) indicated that pH 7.5 had the poorest resistance. Scanning electron microscopy images indicated that pH levels of 6.5, 7.5, and 9.0 had considerable surface corrosion. The results showed that the media's pH significantly influenced the corrosion behavior of CpTi. The poor corrosion behavior at the neutral pHs invites some concerns and highlights the need for further study.
Lateral Augmentation of the Maxilla and Mandible Using Framework Technique With Allogeneic Bone Grafts
Authors: Wallowy Phillip , Dorow Andreas
Published: November 2011

This study aimed to evaluate the effectiveness of lateral ridge augmentation in 36 patients with severely atrophic alveolar ridge using allogeneic bone grafts in a framework technique. A thinned allogeneic cortical graft was screwed to the alveolar ridge, leaving a hollow space that was filled with particulated allogeneic cortical bone. Thirty-six patients who received surgical lateral block augmentation using allogeneic bone grafts were involved in this study. Implants were placed in a second session after a mean time of 6.3 months. The surgical technique and the reasons for failure of surgery in three patients are described. Additionally, properties of allogeneic bone grafts are reviewed. In 33 patients, dental implants were successfully installed and continued to be well maintained at the last follow-up (91.7% success). In three patients, dental implants could not be installed (8.3% failure) as the graft was lost because of wound dehiscence; however, repeat surgery was successfully carried out in all three. The use of allogeneic bone grafts in lateral ridge augmentation of the maxilla and mandible showed successful clinical results. It seems to be a reliable material for reconstructing a severely atrophic alveolar ridge. It presents a good alternative to autogenous bone regarding augmentation because it offers good ossification, less morbidity, unlimited availability and shorter duration of surgery, and lower costs.
Eight-Year Results of Site Retention of Anorganic Bovine Bone and Anorganic Bovine Matrix
Authors: Degidi Marco , Perrotti Vittoria , Piattelli Adriano , Iezzi Giovanna
Published: November 2011

The long-term fate of some biomaterials is still unknown, and the reports present in the literature are not conclusive as to whether these biomaterials are resorbed over time or not. Different reports can be found with regard to the resorption behavior of anorganic bovine bone (ABB). The aim of the present study was to provide a comparative histological and histomorphometrical evaluation, in the same patient, of 2 specimens retrieved from a sinus augmented with ABB and with anorganic bovine matrix added to a cell-binding peptide (PepGen P-15), respectively, after a healing period of 6 months and after 8 years of implant loading, to evaluate the resorption of both biomaterials. A unilateral sinus augmentation procedure with ABB (50%) and with PepGen P-15 (50%) was performed in a 54-year-old male patient. Two titanium dental implants with a sandblasted and acid-etched surface were inserted after 6 months. During this procedure, 2 tissue cores were retrieved from the sinus with a trephine, before implant insertion. After an additional 6 months, a fixed prosthetic restoration was fabricated. One of these implants, after a loading period of 8 years, fractured in the coronal portion and was removed. Both specimens, one retrieved after a 6-month healing period and the other after an 8-year loading period, were treated to obtain thin ground sections. In the 6-month specimen, the histomorphometry showed that the percentage of newly formed bone was 27.2% ± 3.6%, marrow spaces 35.6% ± 2.3%, residual ABB particles 25.1% ± 1.2%, and residual PepGen P-15 particles 12.1% ± 2.2%. In the 8-year specimen, the histomorphometry showed that the percentage of newly formed bone was 51.4% ± 4.8%, marrow spaces 40% ± 7.1%, residual ABB particles 6.2% ± 0.7%, and residual PepGen P-15 particles 2.4% ± 0.5%. Both biomaterials underwent significant resorption over the course of this study.
Histologic and Histomorphometric Assessment of Implants and Periapical Tissues When Placed in the Sockets of Extracted Teeth, Teeth With Periapical Lesions, and Healed Lesions: A Canine Study
Authors: Khademi Abbasali , Shadmehr Elham , Ajami Majid , Rismanchian Mansour , Razavi Seied Mohammad
Published: November 2011

Eighteen canine mandibular premolars were divided into 3 groups. In group 1, implants were inserted in periapical lesions. In group 2, implants were inserted when lesions were radiographically healed. In group 3 (control), implants were inserted immediately after extraction. There was no significant difference in average bone implant contact between the 3 groups. Considering the limitations of this study, immediate placement of dental implants in tooth sockets with periapical lesions should be proposed only under special circumstances.
Nonprocessed Adipose Tissue Graft in the Treatment of Peri-Implant Osseous Defects in the Rabbit's Tibiae: A Pilot Study
Authors: Zanicotti Diogo Godoy , Matsubara Fernanda Brugin , Zielak João César , Giovanini Allan Fernando , Urban Cícero de Andrade , Deliberador Tatiana Miranda
Published: November 2011

We hypothesized that a new technique using nonprocessed adipose tissue could regenerate bone around dental implants. Eighteen rabbits received 1 implant per tibia surrounded by a surgically created osseous defect. The defects were assigned for treatment into 3 groups: C, AT, and AB. The percentages of bone-to-implant contact were 17.64% ± 16.22% (AB), 3.54% ± 7.08% (AT), and 12.71% ± 10.11% (C) (ρ = 0.25). The use of adipose tissue around surgically created peri-implant osseous defects interferes with bone formation.
Prevalência e fatores associados ao Transtorno de Estresse Pós-Traumático (TEPT) em profissionais de emergência: uma revisão sistemática da literatura
Authors: Lima Eduardo de Paula , Assunção Ada Ávila
Published: November 2011

OBJETIVO: Identificar as prevalências de Transtorno de Estresse Pós-Traumático (TEPT) em profissionais dos serviços de emergências e conhecer os fatores associados ao desfecho. MÉTODOS: Foram consultadas sete bases de dados (MEDLINE via Pubmed, PsycINFO, LILACS, SciELO, BDENF, DISASTRES e MEDCARIB) entre os dias 10 e 25 de setembro de 2009, restringindo-se a pesquisa a artigos em português, inglês ou espanhol publicados no período de 2004 a 2009. Os descritores utilizados abarcaram termos relacionados a profissionais/serviços de emergência, transtorno de estresse pós-traumático e condições de trabalho e saúde ocupacional. Foram incluídos estudos observacionais quantitativos que investigaram a prevalência de TEPT e fatores determinantes ou associados à doença em amostras de bombeiros, profissionais de ambulância, profissionais da Cruz Vermelha e profissionais de emergência em hospitais. Foram excluídos estudos com base em amostras inadequadas para os objetivos da revisão (policiais, voluntários e filhos de profissionais de emergência) ou que não incluíram sintomas de TEPT como variável dependente em pelo menos um dos objetivos. RESULTADOS: A leitura dos títulos e resumos resultou em 30 artigos. A revisão das publicações completas permitiu a inclusão e análise de 17 artigos. Os estudos selecionados adotaram diferentes delineamentos, instrumentos, critérios diagnósticos e técnicas estatísticas de análise. A prevalência da doença variou da ausência de registro de casos à taxa de 38,5%. Características sociodemográficas, biológicas e psicológicas, morbidade, exposição a eventos traumáticos ocupacionais e não-ocupacionais, e características do trabalho e do emprego associaram-se ao TEPT em profissionais de emergência. CONCLUSÃO: Variáveis individuais e de contexto são consideradas fatores associados ou de risco para o TEPT e explicitam o caráter mutidimensional do desfecho em foco.
Impacto da sintomatologia osteomuscular na qualidade de vida de professores
Authors: Fernandes Marcos Henrique , Rocha Vera Maria da , Fagundes Ana Angelica Ribeiro
Published: November 2011

O presente estudo objetivou verificar o impacto da sintomatologia osteomuscular na qualidade de vida dos professores da rede municipal de ensino de Natal/RN. Trata-se de uma pesquisa descritiva-analítica com corte transversal, que teve como amostra 242 docentes da rede básica. Foi utilizado o Whoqol-breve para avaliação da qualidade de vida e o questionário Nórdico para os sintomas osteomusculares. Na análise dos dados foram utilizados procedimentos da estatística descritiva e o teste de Mann-Whitney, com um nível de significância de 5%. A prevalência da referida sintomatologia foi de 63,2% entre os investigados, levando-se em consideração os sete dias anteriores ao momento da coleta dos dados. Todos os domínios da qualidade de vida apresentaram-se comprometidos entre o grupo de docentes que apresentaram os sintomas osteomusculares quando comparados ao grupo sem a sintomatologia, sendo encontrado no domínio Físico valor de p < 0,001, no Psicológico p < 0,001, Relação Social p < 0,001 e Meio Ambiente p < 0,001. Dessa forma, a presença de sintomatologia osteomuscular apresentou grande correlação estatística com o comprometimento da qualidade de vida dos professores da rede básica do município de Natal, RN.
Avaliação perceptivo-auditiva e fatores associados à alteração vocal em professores
Authors: Ceballos Albanita Gomes da Costa de , Carvalho Fernando Martins , Araújo Tânia Maria de , Reis Eduardo José Farias Borges dos
Published: November 2011

O professor é um profissional que exige muito de sua voz e, consequentemente, apresenta elevado risco de desenvolver alteração vocal durante o exercício do seu trabalho. OBJETIVO: Identificar fatores associados à alteração vocal em professores. MÉTODO: Estudo exploratório do tipo corte transversal que investigou 476 professores do ensino fundamental e médio de escolas municipais da cidade de Salvador, BA. Os professores responderam a um questionário e foram submetidos à avaliação fonoaudiológica perceptivo-auditiva da voz. Para diagnóstico de alteração vocal utilizou-se a escala GRBAS. RESULTADOS: A população do estudo foi composta por 82,8% de mulheres. Os professores do estudo tinham média de idade igual a 40,7 anos, escolaridade superior (88,4%), jornada de trabalho média de 38 horas semanais, média de 11,5 anos de atuação profissional e renda média mensal de R$ 1.817,18. A prevalência de alteração vocal foi de 53,6% (255 professores). A análise bivariada evidenciou associações estatisticamente significantes entre alteração vocal e idade maior que 40 anos (RP = 1,83; IC 95%; 1,27-2,64), histórico familiar de disfonia (RP = 1,72; IC 95%; 1,06-2,80), carga horária semanal maior que 20 horas (RP = 1,66; IC 95%; 1,09-2,52) e presença de pó de giz na sala de aula (RP = 1,70; IC 95%; 1,14-2,53). CONCLUSÃO: O estudo realizado concluiu que os professores com 40 ou mais anos de idade, com histórico familiar de disfonia, com carga horária semanal maior que 20 horas e que lecionam em salas de aula com pó de giz têm maior chance de ter alteração vocal do que os demais.
Prevalência do consumo de álcool e drogas entre adolescentes: análise dos dados da Pesquisa Nacional de Saúde Escolar
Authors: Malta Deborah Carvalho , Mascarenhas Márcio Dênis Medeiros , Porto Denise Lopes , Duarte Eliane Aparecida , Sardinha Luciana Monteiro , Barreto Sandhi Maria , Morais Neto Otaliba Libânio de
Published: November 2011

OBJETIVO: Descrever a prevalência do consumo de álcool e outras drogas entre estudantes adolescentes. MÉTODO: Estudo transversal com amostra de conglomerados de 60.973 estudantes do nono ano do Ensino Fundamental de escolas públicas e privadas das capitais dos estados brasileiros e do Distrito Federal, em 2009. Foram analisadas as prevalências e os intervalos de confiança de 95% (IC95%) do consumo de álcool e drogas. RESULTADOS: Para o conjunto dos alunos entrevistados, identificou-se o seguinte: experimentação de bebida alcoólica (71,4%; IC95% 70,8-72,0); consumo regular de álcool (27,3%; IC95% 26,7-28,0); embriaguez na vida (22,1%; IC95% 21,6-22,7); preocupação da família se chegasse bêbado em casa (93,8%; IC95% 93,3-94,2); problemas com uso de álcool (9,0%; IC95% 8,6-9,4) e experimentação de outras drogas (8,7%; IC95% 8,3-9,1). CONCLUSÃO: O estudo demonstra a extensão do problema do uso de álcool e drogas entre adolescentes brasileiros, destacando a facilidade com que os jovens entrevistados tiveram acesso ao álcool em festas, bares, lojas e até em suas próprias casas.
O cerrado não é um bioma
Authors: Batalha Marco Antônio
Published: November 2011

É importante definirmos corretamente um termo, porque pode haver implicações práticas e imediatas. Dois conceitos importantes para serem definidos acuradamente são os de "cerrado" e de "bioma". Da maneira como vem sendo usado no Brasil, o conceito de bioma adquiriu erroneamente uma conotação florística. Na verdade, o conceito de bioma é similar ao de formação vegetal, mas leva em conta a associação da vegetação com a fauna e com os microrganismos. Assim, por um lado, o conceito de bioma é fisionômico e funcional, isto é, levam-se em conta a aparência geral da vegetação e aspectos como os ritmos de crescimento e reprodução; por outro, o conceito não é florístico, isto é, a afinidade taxonômica das espécies que aparecem em várias unidades de um mesmo bioma é irrelevante. Para sermos coerentes com toda a literatura internacional e usarmos o conceito de bioma acuradamente, devemos considerar o cerrado sensu lato como formado por três biomas: o campo tropical (campo limpo), a savana (campo sujo, campo cerrado e cerrado sensu stricto) e a floresta estacional (cerradão).
Mites and leaf domatia: no evidence of mutualism in Coffea arabica plants
Authors: Romero Gustavo Quevedo , Daud Rodrigo Damasco , Salomão Adriana Trevizoli , Martins Luiz Fernando , Feres Reinaldo José Fazzio , Benson Woodruff Whitman
Published: November 2011

We conducted experiments by blocking off pit-like domatia from old and new leaves of Coffea arabica L., using tiny resin drops, to investigate the role of domatia on i) mite abundance at the community level and on ii) leaf damages. More than 77% of the mites collected were predators, whereas 19 and 3.3% were omnivores and phytophages, respectively. Domatia blockage treatment had no influence either on mite abundances or leaf damages. However, predatory and omnivorous mites were more abundant on new than on the old leaves; phytophagous mites occurred at very low density and occupied only plants having open domatia. The absence of mutualism between mites and C. arabica probably occurred because the entrances of domatia were too small and did not enable the entry of fitoseid predators in these structures.
Compilação atualizada das espécies de morcegos (Chiroptera) para a Amazônia Brasileira
Authors: Bernard Enrico , Tavares Valéria da Cunha , Sampaio Erica
Published: November 2011

O Brasil abriga cerca de 15% da riqueza de morcegos do planeta, e grande parte desta riqueza está presente no bioma Amazônia. Apresentamos aqui uma compilação atualizada das espécies de morcegos da Amazônia Legal Brasileira, com registros formais de 146 espécies, distribuídas em nove famílias, e 64 gêneros. Pelo menos 46 destas espécies têm, até o momento, a ocorrência restrita ao bioma amazônico. O Pará é o estado com o maior número de espécies registradas (120), enquanto que a porção amazônica do Maranhão apresenta apenas 21 espécies. Nove espécies foram registradas em todos os estados amazônicos e 28 são conhecidas em apenas um estado. A lista de espécies de morcegos para a região não está esgotada e é bastante plausível que a Amazônia Brasileira contenha mais de 160 espécies de morcegos. Apontamos áreas prioritárias para a realização de inventários para morcegos na região, e discutimos alguns fatores que podem contribuir para o aumento do conhecimento da quiropterofauna amazônica.
Dinâmica da comunidade lenhosa de um Cerrado Típico na região Nordeste do Estado de Mato Grosso, Brasil
Authors: Mews Henrique Augusto , Marimon Beatriz Schwantes , Maracahipes Leandro , Franczak Daniel David , Marimon-Junior Ben Hur
Published: November 2011

O objetivo do trabalho foi analisar as mudanças na comunidade lenhosa em um período de quatro anos. Foram estabelecidas 50 parcelas permanentes de 10 × 10 m onde foram amostrados todos os indivíduos com diâmetro a 30 cm acima do solo (DAS 30 cm) > 5 cm em 2002 e em 2006. No inventário de janeiro de 2002, foram encontrados 945 indivíduos pertencentes a 77 espécies, 65 gêneros e 35 famílias ao passo que em janeiro de 2006 foram 1.106 indivíduos distribuídos em 80 espécies, 66 gêneros e 36 famílias. A diversidade de espécies e a estrutura diamétrica da comunidade não diferiram no período. As taxas de mortalidade (4,01% ano-1) e de perda de área basal (0,68% ano-1) foram compensadas pelas taxas de recrutamento (6,67% ano-1) e de ganho de área basal (2,26% ano-1), indicando a manutenção da comunidade como aparentemente estável. O incremento periódico anual (IPA) da comunidade foi de 0,31 cm ano-1, sendo superado pelo IPA de Euplassa inaequalis, Kielmeyera rubriflora e Byrsonima coccolobifolia (0,72, 0,49 e 0,47 cm ano-1, respectivamente), indicando o potencial de crescimento de tais espécies como importante para estratégias de recuperação de áreas degradadas. A ausência de fogo no período estudado pode ter sido o fator responsável pela dinâmica da vegetação do cerrado estudado, favorecendo o estabelecimento de algumas espécies lenhosas e proporcionando aumento em densidade e biomassa.
Morcegos (Mammalia, Chiroptera) da Reserva Rio das Pedras, Rio de Janeiro, Sudeste do Brasil
Authors: Luz Júlia Lins , Costa Luciana de Moraes , Lourenço Elizabete Captivo , Esbérard Carlos Eduardo Lustosa
Published: November 2011

Uma lista das espécies de morcegos da Reserva Rio das Pedras, Município de Mangaratiba, foi elaborada através de capturas com redes de neblina, desde setembro de 1995 até junho de 2008, totalizando 242424 h.rede de esforço de captura. O total de 30 espécies de morcegos foi registrado em 1321 capturas e recapturas. As espécies predominantes foram Carollia perspicillata e Artibeus lituratus. Seis famílias foram registradas: Emballonuridae, Noctilionidae, Phyllostomidae, Thyropteridae, Vespertilionidae e Molossidae. Comparando com seis listas de espécies disponíveis de locais distantes até 100 km, a Reserva Rio das Pedras apresentou alta riqueza, diversidade e abundância de Phyllostominae, comprovando a relevância do local para a conservação dos morcegos.