Te Donors Research Articles

O USO DOS RITMOS E DANÇAS NA EDUCAÇÃO ESCOLAR

This text is an excerpt from the Master’s Dissertation that addresses THE TRIPLE BORDER OF BRAZIL, PERU AND COLOMBIA: CULTURAL DIVERSITY AS A TEACHING TOOL IN A 3RD YEAR CLASS OF PIO VEIGA STATE SCHOOL IN THE MUNICIPALITY OF ATALAIA DO NORTE. Brazil is a country made up of great cultural diversity made up of different peoples, Africans, Europeans and indigenous people, each with their own customs, values ​​and beliefs, a mixture of different cultures. Schools located on borders, for example, are schools considered to have a higher rate of cultural diversity, as they are influenced by neighboring cities/countries. It is worth highlighting that Brazil has intense borders with several South American countries. Among these intense borders, in this study we will highlight the Triple Border: Brazil, Peru and Colombia. Although the school is a favorable environment for working with cultural diversity, what has been seen in the school environment is the great difficulty teachers have in integrating these diversities into their pedagogical practices. In this way, the school must assume the role of intermediary, for the study and knowledge of existing cultures within the school environment, through meaningful pedagogical practices. Thus, this study aimed to analyze how the cultural diversity of the triple border can contribute to the student training process.

Oxidorhenium(V) and Rhenium(III) Complexes with Arylselenolato and ‐tellurolato Ligands

AbstractIn situ prepared lithium arylselenolates {LiSePh, LiSe(2,6‐Me2Ph), LiSe(2,4,6‐Me3Ph)} or ‐tellurolates {LiTePh, LiTe(2,6‐Me2Ph), LiTe(2,4,6‐Me3Ph)} react with [ReOCl3(PPh3)2] and (NBu4)Br in good yields under formation of rhenium(V) complexes of the composition (NBu4)[ReO(L)4)]. The first oxidorhenium(V) complex with four monodentate phenolato ligands, [ReO(2,6‐Me2Ph)4]−, was prepared and isolated in crystalline form. This allows a comparison of experimental and computational data of a full series of such compounds with basal O, S, Se and Te donor atoms. Similar reactions with [ReCl3(PPh3)2(CH3CN)] or [ReCl3(PMe2Ph)3] give trigonal bipyramidal rhenium(III) complexes of the compositions [Re(PPh3)(L)3(CH3CN)] or [Re(PPh3)2(L)3] depending on the chalcogenolate applied. The reported oxidorhenium(V) and rhenium(III) complexes were fully characterized by spectroscopic methods and X‐ray diffraction. The bonding situation in the rhenium(V) and rhenium(III) chalcogenolates was assessed through density functional theory calculations based on the quantum theory of atoms in molecules (QTAIM), natural bonding orbital (NBO) analysis, charge analysis, the electron localization function (ELF) maps and topological descriptors at the {3,−1} critical points such as metallicities. Expectedly, the ionicity of the rhenium‐chalcogen bonds decreases according to all three applied charge models from O to Te. Generally, the Re−Se and Re−Te bonds are more directional in the Re(III) complexes than in the oxidorhenium(V) compounds.

Near-Surface ^{125}Te^{+} Spins with Millisecond Coherence Lifetime.

Impurity spins in crystal matrices are promising components in quantum technologies, particularly if they can maintain their spin properties when close to surfaces and material interfaces. Here, we investigate an attractive candidate for microwave-domain applications, the spins of group-VI ^{125}Te^{+} donors implanted into natural Si at depths as shallow as 20nm. We show that surface band bending can be used to ionize such near-surface Te to spin-active Te^{+} state, and that optical illumination can be used further to control the Te donor charge state. We examine spin activation yield, spin linewidth, and relaxation (T_{1}) and coherence times (T_{2}) and show how a zero-field 3.5GHz "clock transition" extends spin coherence times to over 1ms, which is about an order of magnitude longer than other near-surface spin systems.

Atypical topological features of the Bi1-xSbx(0 ≤ x ≤ 0.2) nano-width bicrystaline boundaries

In this paper, we report a number of atypical features of superconductivity, weak ferromagnetism, and quantum transport observed at low temperatures at bicrystalline interfaces of the first predicted and experimentally realized three-dimensional topological insulator (3D TI) Bi1xSbx (0 ≤ x ≤ 0.2). Pure bicrystals and bicrystals slightly doped (≤0.01 at %) with Te (donor) and Sn (acceptor) impurities are used to fully satisfy the conditions of manifestation of transport quantum oscillations. These 3D TI interfaces exhibit fascinating quantum topological properties, which require extensive basic and applied research.

Degradation Mechanisms of the Detector Properties of CdTe and CdZnTe Under the Influence of Gamma Irradiation

This work is devoted to the study of the mechanisms of the influence of radiation defects, arising under the influence of gamma irradiation, on the change in resistivity ρ, lifetime of nonequilibrium electrons τn and holes τp, in CdTe:Cl and Cd0.9Zn0.1Te as well as the collection efficiency η of uncooled radiation detectors based on these materials, by computer simulation method. Radiation defects, that are corresponded by deep energy levels in the band gap, act as trapping centers of nonequilibrium charge carriers, noticeably affect the degree of compensation by changing ρ of the detector material, the recombination processes by decreasing τn and τp, what ultimately can cause degradation of the charges collection efficiency η. The specific reasons for the deterioration of the detector properties of CdTe:Cl and Cd0.9Zn0.1Te under the influence of gamma irradiation were identified, and the main factors leading to complete degradation of the recording ability of detectors based on these semiconductors during their bombardment by 60Co gamma quanta were determined. The gradual degradation of the spectroscopic performance of CdTe:Cl-based detectors during gamma irradiation occurs due to the continuous formation of cadmium vacancies VCd and acceptor complexes VCd – Cl, which continuously shift Fermi level towards valence band and decrease ρ. The complete performance degradation of CdTe detectors takes place mainly due to the capture of nonequilibrium electrons at energy level of interstitial tellurium Te(I). The invariable spectroscopic properties of CdZnTe-based sensors under gamma irradiation up to 25 kGy occur due to the mechanism of radiative self-compensation by formation of substitutional defect TeZn. At the final stage of irradiation, a sharp deterioration in the detector properties of CdZnTe occurs, mainly due to the capture and recombination of nonequilibrium charge carriers at the level of the Te(I) defect. The different radiation resistances of CdZnTe and CdTe:Cl can be explained by different behavior of Fermi level EF in these semiconductors under gamma irradiation. EF in CdZnTe under radiation exposure remains near the middle of band gap, and in CdTe it drifts to the valence band. The rate of capture and recombination through Te(I) donor level in CdTe:Cl is lower than in CdZnTe due to the larger difference between the Fermi level and the radiation defect Te(I) level in cadmium telluride. Thereby, the complete degradation of the CdTe:Cl detector occurs at a higher concentration of radiation defect Te(I), and hence after a higher irradiation dose of 50 kGy compared with a dose of 30 kGy required for degradation of CdZnTe detector properties.

INTERVENÇÕES EM CORPOS HÍDRICOS E ALTERAÇÕES NO MEIO GEOGRÁFICO: O DESASSOREAMENTO DO CANAL DO PIATÓ – ASSÚ, RIO GRANDE DO NORTE, BRASIL.

O desassoreamento é uma medida periódica que visa manter a profundidade e o curso do corpo hídrico constante, pois em períodos de baixa pluviosidade o rio pode sofrer por meios antrópicos ou naturais transformações que o torne menos profundo. A deposição de sedimentos ou objetos como lixo em seu leito, contribui para que em momentos de chuvas mais intensas a água que passa pelo canal ultrapasse os limites pré-estabelecidos pelas suas margens. Sendo assim, o presente trabalho busca compreender os impactos socioambientais causados pelo processo de desassoreamento no canal do Piató. O referido canal está sendo debatido na Câmara Municipal de Assú, sendo que o mesmo já passou por outras intervenções de desassoreamentos, segundo relato de moradores locais, porém sem sucesso. Fato ocorrido entre as décadas de 40 e 50, pelo então prefeito Edgar Borges Montenegro, nos anos entre 1948 a 1953. Tendo em vista problemas que por ventura podem ser acarretados a partir da realização do desassoreamento do canal, buscaremos compreender os impactos socioambientais decorrentes da recuperação do Canal do Piató. A equipe técnica da SEMARH (Secretaria do Meio Ambiente e Recursos Hídricos do Estado do Rio Grande do Norte), está realizando os estudos topográficos e ambientais in loco para posteriormente, iniciar a reconstrução do sangradouro do Canal do Piató. A SEMARH demonstra preocupação quanto a real possibilidade sobre o abastecimento da Lagoa do Piató pelas águas do canal em períodos chuvosos, ou não, e também qual o melhor local para o início dos trabalhos de desassoreamento dentro do canal do Piató.

Дефекты межслоевой поверхности и термоэлектрические свойства в слоистых пленках топологических изоляторов n-Bi-=SUB=-2-=/SUB=-Te-=SUB=-2.7-=/SUB=-Se-=SUB=-0.15-=/SUB=-S-=SUB=-0.15-=/SUB=-

Interlayer surface defects and thermoelectric properties in layered films of n-Bi2Te2.7Se0.15S0.15 topological insulators L. N. Lukyanova*, O. A. Usov, M. P. Volkov, V. A. Rusakov Ioffe Institute Russian academy of science, 194021 St.Petersburg, Russia *E-mail: lidia.lukyanova@mail.ioffe.ru Abstract In layered films of n-Bi2Te2.7Se0.15S0.15 topological insulators optimized for temperatures below room temperature, the morphology of the (0001) interlayer surface and thermoelectric properties were studied. On the profiles of the (0001) surface, we identified neutral impurity defects arising from the substitution of Se and S atoms for Te atoms and donor antisite defects of tellurium at bismuth sites, which affect the thermoelectric properties. The average value of thermoelectric figure of merit in n-Bi2Te2.7Se0.15S0.15 films increases to <Z> ≈ 3.0•10-3 K-1 in the range 80 – 215 K, while in bulk solid solution <Z> ≈ 2.0•10-3 K-1. An increase in the thermoelectric figure of merit in films is associated with an increase in the energy dependence of the relaxation time due to an increase in the effective scattering parameter reff. It is shown that in films the Seebeck coefficient, the density of states effective mass m/m0, and the material parameter proportional to the power factor increase, while the lattice κL and electronic thermal conductivity κe decrease, which determines the increase in thermoelectric figure of merit.

The effect of Te dopant on the optical and electrical properties of high-resistivity AlSb crystals

Aluminum antimonide (AlSb) has a great potential application in electronic devices used at high temperatures. However, the properties of available AlSb crystals were still far away from the theoretical ones due to the high density of variant defects, especially point defects. Here, an improvement in optical transmittance and resistivity of AlSb was achieved by doping the as-grown AlSb with appropriate content of Te, through which the absorption of a spin split-off-heavy-hole band transition near 1.65 μm disappeared and the resistivity was increased from 102 to 106 Ω cm. It was suggested that the residual acceptors with the binding energy EA of 37.4 meV were compensated by a Te donor with ED = 71 meV in the AlSb:Te crystal, according to the evaluation of the competing recombination (e, A0) and (Te0, A0). An energy band model was proposed to describe the recombination process and the underlying mechanism. The photo-response of the high resistance AlSb:Te crystal, illuminated by a pulsed LED light in the visible light range, revealed that the ratio of photocurrent to dark current was 128, indicating a great potential application for room-temperature photo-detection.

Te incorporation and activation as n -type dopant in self-catalyzed GaAs nanowires

Dopant atoms can be incorporated into nanowires either via the vapor-liquid-solid mechanism through the catalyst droplet or by the vapor-solid growth on the sidewalls. Si is a typical n-type dopant for GaAs, but in nanowires it often suffers from a strongly amphoteric nature in the vapor-liquid-solid process. This issue can be avoided by using Te, which is a promising but less common alternative for $n$-type doping of GaAs nanowires. Here, we present a detailed investigation of Te-doped self-catalyzed GaAs nanowires. We use several complementary experimental techniques, such as atom probe tomography, off-axis electron holography, micro-Raman spectroscopy, and single-nanowire transport characterization, to assess the Te concentration, the free-electron concentration, and the built-in potential in Te-doped GaAs nanowires. By combing the experimental results with a theoretical model, we show that Te atoms are mainly incorporated by the vapor-liquid-solid process through the Ga droplet, which leads to both axial and radial dopant gradients due to Te diffusion inside the nanowires and competition between axial elongation and radial growth of nanowires. Furthermore, by comparing the free-electron concentration from Raman spectroscopy and the Te-atom concentrations from atom probe tomography, we show that the activation of Te donor atoms is $100%$ at a doping level of $4\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$, which is a significant result in terms of future device applications.

Mechanism of free electron concentration saturation phenomenon in Te-GaSb single crystal**Project supported by the National Natural Science Foundation of China (Grant Nos. 61474104 and 61504131).

Te-doped GaSb single crystal grown by the liquid encapsulated Czochralski (LEC) method exhibits a lag of compensating progress and a maximum carrier concentration around 8×1017 cm−3. The reason for this phenomenon has been investigated by a quantity concentration evaluation of the Te donor and native acceptor. The results of glow discharge mass spectrometry (GDMS) and Hall measurement suggest that the acceptor concentration increases with the increase of Te doping concentration, resulting in the enhancement of electrical compensation and free electron concentration reduction. The acceptor concentration variation is further demonstrated by photoluminescence spectra and explained by the principle of Fermi level dependent defect formation energy.

Charge carriers modulation and thermoelectric performance of intrinsically p-type Bi2Te3 by Ge doping

Stoichiometric Bi2Te3 is p-type and narrow band gap semiconductor, but realization of hole transport is very challenging because of dominant electron donor Te vacancies and TeBi anti site defects. In the present study, we report on the effect of Ge incorporation on structural and thermoelectric properties of Bi2Te3. Carrier density (Np) of Bi2Te3 increases by one order with Ge doping, revealing formation of acceptor states, consequently improving the electrical conductivity (σ). The p-type thermopower (α) enhances providing a significant gain in power factor (α2σ) from 0.32 × 10−3 Wm−1K−2 to 2.52 × 10−3 Wm−1K−2 for Bi2Te3 to Bi1.95Ge0.05Te3, respectively. Here, Ge being tetravalent contributes an extra hole to the Bi2Te3 and leading to optimized, Np for improved thermoelectric properties. Thus, room temperature thermoelectric figure of merit ZT∼0.95 have been achieved for Bi1.95Ge0.05Te3. Additionally, the applicability of prepared Ge doped Bi2Te3 materials for segmented thermoelectric devices has been discussed.

Synthesis of Tellurabenziporphyrin and Its Pd(II) Complex.

An unprecedented tellurabenziporphyrin containing C, N, and Te donor atoms was synthesized by condensing benzitripyrrane and tellurophene diol under acid catalyzed conditions. The tellurabenziporphyrin readily forms a Pd(II) complex when treated with PdCl2 in CHCl3/CH3CN. The crystal structures of tellurabenziporphyrin and its Pd(II) complex revealed that the benzene ring hinders the π-electron delocalization. An unusual five-membered ring formed inside the macrocycle due to the strong interaction between "Te" and "N" in the Pd(II) complex.

ANÁLISES SOBRE MUDANÇAS NOS HÁBITOS ALIMENTARES DE CRIANÇAS MORADORAS DO ASSENTAMENTO PAQUEQUER, NOVA OLINDA DO NORTE- AM./ Analysis about changes in the food habits of children living in Paquequer Settlement, Nova Olinda do Norte - AM.

As informações apresentadas neste artigo resultam do trabalho de iniciação científica no PIB-H/0083/2015-CNPq, realizados no Projeto de Assentamento Paquequer, município de Nova Olinda do Norte – Amazonas, no ano de 2015. O assentamento pesquisado configura um modelo de assentamento tradicional, localizado em ecossistema amazônico de terra firme distante 13 km da sede do município. Participaram da pesquisa, crianças moradoras do assentamento, matriculadas no Ensino Fundamental II da Escola Municipal Paquequer. O objetivo da pesquisa buscou analisar como se apresentava o consumo alimentar do universo pesquisado, tanto em sua moradia quanto no ambiente escolar, verificando se nesses locais poderiam ser identificadas mudanças nos hábitos alimentares regionais. Os dados obtidos no resultado final da pesquisa confirmaram que, nos últimos anos, o consumo de alimentos ultraprocessados como refrigerantes, biscoitos recheados e embutidos é amplamente realizado pelos entrevistados dentro do assentamento, em detrimento do consumo reduzido de frutas, peixes e alimentos tradicionalmente regionais, demonstrando que cada vez mais os padrões alimentares urbanos estão sendo vivenciados no modo de vida rural.

A Roadmap for Controlled and Efficient n‐Type Doping of Self‐Assisted GaAs Nanowires Grown by Molecular Beam Epitaxy

N‐type doping of GaAs nanowires has proven to be difficult because the amphoteric character of silicon impurities is enhanced by the nanowire growth mechanism and growth conditions. The controllable growth of n‐type GaAs nanowires with carrier density as high as 1020 electron cm−3 by self‐assisted molecular beam epitaxy using Te donors is demonstrated here. Carrier density and electron mobility of highly doped nanowires are extracted through a combination of transport measurement and Kelvin probe force microscopy analysis in single‐wire field‐effect devices. Low‐temperature photoluminescence is used to characterize the Te‐doped nanowires over several orders of magnitude of the impurity concentration. The combined use of those techniques allows the precise definition of the growth conditions required for effective Te incorporation.

Telluroether and Selenoether Complexes as Single Source Reagents for Low Pressure Chemical Vapor Deposition of Crystalline Ga2Te3 and Ga2Se3 Thin Films

The neutral complexes [GaCl3(EnBu2)] (E = Se or Te), [(GaCl3)2{nBuE(CH2)nEnBu}] (E = Se, n = 2; E = Te, n = 3), and [(GaCl3)2{tBuTe(CH2)3TetBu}] are conveniently prepared by reaction of GaCl3 with the neutral EnBu2 in a 1:1 ratio or with nBuE(CH2)nEnBu or tBuTe(CH2)3TetBu in a 2:1 ratio and characterized by IR/Raman and multinuclear (1H, 71Ga, 77Se{1H}, and 125Te{1H}) NMR spectroscopy, respectively, all of which indicate distorted tetrahedral coordination at Ga. The tribromide analog, [GaBr3(SenBu2)], was prepared and characterized similarly. A crystal structure determination on [(GaCl3)2{tBuTe(CH2)3TetBu}] confirms this geometry with each pyramidal GaCl3 fragment coordinated to one Te donor atom of the bridging ditelluroether, Ga–Te = 2.6356(13) and 2.6378(14) A. The nBu-substituted ligand complexes serve as convenient and very useful single source precursors for low pressure chemical vapor deposition (LPCVD) of single phase gallium telluride and gallium selenide, Ga2E3, films onto SiO2 and TiN substrate...

PRIMEIRO ISOLAMENTO DE LENTIVÍRUS DE PEQUENOS RUMINANTES EM CAPRINO NATURALMENTE INFECTADO EM REBANHO DO RIO GRANDE DO NORTE, BRASIL

RESUMO O Vírus da Artrite Encefalite Caprina (CAEV) e Vírus Maedi-visna (MVV) pertencem ao gênero Lentivírus da família Retroviridae. São considerados geneticamente distintos, mas antigenicamente relacionados. O objetivo desde trabalho foi isolar o vírus da CAE de um animal oriundo de um rebanho do Rio Grande do Norte e positivo pelo teste de Imunodifusão em Gel de Agarose (IDGA) através do co-cultivo de leucócitos infectados do sangue periférico em Membrana Sinovial Caprina (MSC). Dezesseis caprinos da raça Saanen, com suspeitas clínicas para CAE foi testado por IDGA e Western Blotting. Para o isolamento viral, os leucócitos do sangue periférico foram isolados por co-cultivo em MSC. Monócitos/Macrófagos coletados foram inoculados em monocamadas pré-formadas em garrafas A25. O resultado do IDGA foi positivo para um animal, confirmado por Western Blotting. Após 50 dias de co-cultivo, foi realizada a coloração da monocamada com cristal de violeta a 0,1% para visualização do ECP e realizada nested-PCR do sobrenadante do co-cultivo, com confirmação do efeito citopático viral. A cepa isolada, denominada BrRN-CNPC.G1 foi considerada o primeiro isolamento do CAEV no Estado do Rio Grande do Norte. Esse estudo permitirá em breve, realizar a caracterização molecular do genoma do vírus isolado, através da análise de seus diferentes genes estruturais e comparar com outras sequencias virais isoladas para identificar a provável origem da infecção desse animal e estabelecer as possíveis divergências entre cepas padrões de Lentivírus e cepas regionais circulantes.

Hypervalent Adducts of Chalcogen-Containing peri-Substituted Naphthalenes; Reactions of Sulfur, Selenium, and Tellurium with Dihalogens

A range of structurally diverse compounds 1-15 {Nap[SPh](2).Br(4) (Nap = naphthalene-1,8-diyl); Nap[SePh][EPh].Br(4) (E = Se, S); Nap[SePh](2).I(2); Nap[SePh][EPh].3/2I(2) (E = Se, S); Nap[TePh][G].X(2) (G = SePh, SPh, Br, I; X = Br, I); and [Nap(PPh(2)OH)(SPh)](+)Br(3)(-)} formed from the reactions between peri-substituted naphthalene chalcogen donors D1-D8 {Nap[ER][E'R] (ER/E'R = SPh, SePh, TePh); Nap[TePh][X] (X = Br, I); and Nap[PPh(2)][SPh]} and dibromine and diiodine were characterized by X-ray crystallography and where possible by multinuclear NMR, IR, and MS. X-ray data for 1-15 were analyzed by naphthalene ring torsions, peri-atom displacement, splay angle magnitude, peri-distance, aromatic ring orientations, and quasi-linear three-body arrangements. The hypervalent linear moieties are considered in the context of the charge-transfer model and the 3c-4e model introduced by Pimentel and Rundle. In general, the conformation of the final products obeyed the rule based on charge-transfer that "seesaw" (X-ER(2)-X, 10-E-4) adducts arise when the halogen (X) is more electronegative than the chalcogen (E), and if the converse is true then, CT "spoke" (X-X-ER(2), 8-E-3) adducts are formed. Upon treatment with dibromine, selenium donor compounds D2 {Nap[SePh](2)} and D3 {Nap[SePh][SPh]} afford unusual tribromide salts of bromoselenyl cations containing a hypervalent X-E...E' 3c-4e type interaction. Upon treatment with diiodine, D2 and D3 form "Z-shaped", "extended spoke" adducts containing an uncommon 2:3 donor/chalcogen ratio and incorporating chains of I(2) held together by rare I...I interactions. As expected, "seesaw" 10-E-4 adducts are formed following the reaction of Te donors D4-D7 {Nap[TePh][X] (X = Br, I); Nap[TePh][EPh] (E = Se, S)} with the dihalogens. Naphthalene distortion in general is comparable between respective donor compounds and products 1-15. Ionic species 2 and 3 display a noticeable reduction in molecular distortion explained by the relief of steric strain via weak peri-interactions and the onset of 3c-4e bonding.

CONTAGEM DE CÉLULAS SOMÁTICAS, COMPOSIÇÃO E CONTAGEM BACTERIANA TOTAL DO LEITE DE PROPRIEDADES LEITEIRAS NOS MUNICÍPIOS DE MIRANDA DO NORTE, ITAPECURÚ– MIRIM E SANTA RITA, MARANHÃO

RESUMO Objetivou-se com este estudo avaliar a contagem de células somáticas (CCS), composição e contagem bacteriana total (CBT) sobre a qualidade do leite produzido em propriedades leiteiras de Miranda do Norte, Itapecurú-Mirim e Santa Rita, Estado do Maranhão. Verificou-se no período A que a média de CCS foi de 2.236.700 células/mL, 3,87 % de gordura, 3,19% de proteína, 4,36% de lactose, 12,25% de EST, 8,55% de ESD (%) e CBT de 677,90 UFC/mL, e no período B a média de CCS foi de 2.629.950 células/mL, 3,87% de gordura, 3,27% de proteína, 4,45% de lactose, 13,19% de EST, 8,74% de ESD e CBT de 8421,35 UFC/mL. Quanto à sazonalidade, as médias de CCS e CBT foram mais elevadas no período B do que no período A.

Free Carrier Scattering in Metallic n-GaAs in the Presence of Static Lattice Distortions Due to a Partial Chemical Order of Impurities

Simple electric transport versus T = 20‐400 K in metallic n-GaAs annealed single crystals with Te impurity concentration » (0.4‐1.7) £ 10 19 cm i3 , which is above the equilibrium doping limit, is reported and compared with modern theory of electron mobility in degenerated n-GaAs by Szmyd, Hanna, Majerfeld. An overcome of the equilibrium doping limit in annealed n-GaAs is manifested by a lowered electrical activation of Te donors and by an onset of … 0.1‐1 „m regions of local strain in the crystal lattice known from high resolution X-ray studies. These preliminary results of transport show that the electron mobility „(T) measured for n-GaAs with local strains is not consistent with predictions of Szmyd et al. model for any degree of compensation assumed. This surprising result indicates that electric transport in materials above the equilibrium doping limit is not well understood assuming the scattering by ionized impurities. The nature of defects responsible for an observed strong reduction of free carrier concentration (here … 80%) in annealed heavily doped n-GaAs seems not to be related with electrical compensation. We point here at the possible role of eects of free carrier scattering due to static lattice distortions (local strains) related to a chemical aggregation of impurity atoms. We also notice that transport in metallic n-GaAs with local strains shows features similar to a weak localization aexx / logT.

SURTO DE FEBRE CATARRAL MALIGNA EM BOVINOS NO ESTADO DO RIO GRANDE DO NORTE

MALIGNANT CATARRHAL FEVER IN CATTLE FROM RIO GRANDE DO NORTE, BRAZIL This study describes the clinical, epidemiological, and histopathological aspects of three cases of acute malignant catarrhal fever in cattle from a rural property in the municipality of Mossoro, Rio Grande do Norte. The main symptoms observed in the affected animals were anorexia, fever, cornea opacity, mucopurulent nasal discharge, and incoordination. Hematological analysis revealed leukopenia with relative monocytosis. Prior to these three cases, six other animals had died with similar symptoms. Postmortem findings included ulcers in oral and nasal mucosa, lesions in the tongue and palate, edema of glottis, hyperemia of esophagus and trachea mucosa, hypertrophy and congestion of lymph nodes, cerebral and cerebellar congestion. Histopathological examination showed generalized vasculitis, necrosis of vessel wall, and perivascular infiltration of mononuclear cells in several organs. A definitive diagnosis of malignant catarrhal fever was provided by the clinical and histopathological changes observed.