THEORY OF ELECTRICAL CHARACTERISTICS OF A SCHOTTKY-BARRIER HAVING EXPONENTIALLY DISTRIBUTED IMPURITY STATES AND METAL-INSULATOR METAL STRUCTURES

The metal-insulator or metal-amorphous semiconductor blocking contact is still not well understood. Here, we discuss the steady state characteristics of a non-intimate metal-insulator Schottky barrier. We consider an exponential distribution (in energy) of impurity states in addition to impurity states at a single energy level within the depletion region. We present analytical expressions for the electrical potential, field, thickness of depletion region, capacitance, and charge accumulated in the depletion region. We also discuss ln I versus V(ap) data. Finally, we compare the characteristics in three cases: (i) impurity states at only a single energy level; (ii) uniform energy distribution of impurity states; and (iii) exponential energy distribution of impurity states.In general, the electrical characteristics of Schottky barriers and metal-insulator-metal structures with Schottky barriers depend strongly on the energy distribution of impurity states.

THEORY OF NON-STEADY-STATE ELECTRICAL CHARACTERISTICS OF METAL-INSULATOR-METAL STRUCTURES WITH SCHOTTKY BARRIERS AND UNIFORMLY DISTRIBUTED INTERFACE IMPURITY STATES

The metal-insulator (or amorphous semiconductor) blocking contact is still not well understood. In the present paper, we discuss the non steady state characteristics of Metal-lnsulator-Metal Structure with non-intimate blocking contacts (i.e. Metal-Oxide-Insulator-Metal Structure). We consider a uniform distribution (in energy) of impurity states in addition to impurity states at a single energy level within the depletion region. We discuss thermal as well as isothermal characteristics and present expressions for the temperature of maximum current (T-m) and a method to calculate the density of uniformly distributed impurity states. The variation of mobility with electrical field has also been considered. Finally we plot the theoretical curves under different conditions. The present results are closing into available experimental results.

Theory of electrical characteristics for metal-oxide-insulator Schottky barrier and metal-insulator-metal structures

The metal-insulator or metal-amorphous semiconductor blocking contact is still not well understood. Here, the intimate metal-insulator and metal-oxide-insulator contact are discussed. Further, the steady-state characteristics of metal-oxide-insulator-metal structures are also discussed. Oxide is an insulator with wider energy band gap (about 50 Å thick). A uniform energetic distribution of impurities is considered in addition to impurities at a single energy level inside the surface charge region at the oxide-insulator interface. Analytical expressions are presented for electrical potential, field, thickness of the depletion region, capacitance, and charge accumulated in the surface charge region. The electrical characteristics are compared with reference to relative densities of two types of impurities. ln I is proportional to the square root of applied potential if energetically distributed impurities are relatively important. However, distribution of the electrical potential is quite complicated. In general energetically distributed impurities can considerably change the electrical characteristics of these structures.

Fresh autogenous rib cartilage graft to the malar process of rats with and without removal of the perichondrium: a histological study.

A comparison was made of autogenous grafts of rib cartilage with and without removal of the perichondrium, applied to the malar process of rats. Seventy-two male albino rats were divided into two groups according to the kind of graft received by each animal. The experimental periods were 5, 10, 20, 30, 60 and 120 postoperative days. The results showed that, in the control group, the grafts maintained their vitality for the whole experimental period and the perichondrium was biologically integrated into the host bed. Appositional growth was also observed. The treated animals showed intense resorption of the grafts and more intense bone neoformation. The newly formed bone was in intimate contact with the graft in both groups.

A generalized theory of electrical characteristics of schottky barriers for amorphous materials

In the present paper, we discuss a generalized theory of electrical characteristics for amorphous semiconductor (or insulator) Schottky barriers, considering: (i) surface states, (ii) doping impurity states at a single energy level and (iii) energetically distributed bulk impurity states. We also consider a thin oxide layer (≈10 Å) between metal and semiconductor. We develop current versus applied potential characteristics considering the variation of the Fermi level very close to contact inside the semiconductor and decrease in barrier height due to the image force effect as well as potential fall on the oxide layer. Finally, we discuss the importance of each parameter, i.e. surface states, distributed impurity states, doping impurity states, thickness of oxide layer etc. on the log I versus applied potential characteristics. The present theory is also applicable for intimate contact, i.e. metal-semiconductor contact, crystalline material structures or for Schottky barriers in insulators or polymers.

Interferentes eritrocitários e ambientais na anemia falciforme

Erythrocytes and environmental interferences on sickle cell anaemia Sickle cell anaemia runs na extremely variable clinical course At one end of spectrum, it is characterized by a crippling haemolitic anaemia, interspersed with severe exacerbations, or crises, yet it may be an extremely mild disorder, which is found only by chance on rotine haematological examination. The reasons are only partly understood for these remarkable differences in phenotypic expression of what appears to be the same genetic defect: they include the level of Hb Fetal, coinheritance of the alpha thalassaemia and of other genetic variantsthat has influence as genetic modulation in sickle cell anaemia. However, other genetics abnormalities of erythrocytes: G-6PD deficiency, spherocytosis and deficiencies of anti-oxidant enzymes(SOD, GPx and Catalase) probably interfereon the clinical course of sickle cell anaemia. The haplotypes of the chromosome (Bantu, Benin, Camaroon and Arab-Indian) bearing the sickle gene is associated with assorted haematological and clinical features that are likely, at least in part, to be mediated throgh effects on Hb Fetal concentration. Beyond these factors characterizes as erythrocytes interferents, there are the environmental interferents. Between environmental interferents become detached the socio-economic and cultural situation of each patient. These aspects have influence on the life of affected individuals including social interactions, family relations, peer interaction, intimate relationships, education, enployment, violence, spiritual attitudes and navigating complexities of the health care system, providers and their ancillary functions. As a result of this article it is proposed a protocol of laboratorial management of sickle cell syndrome with detach to sickle cell anaemia.

Violence against women in couples: Latin America and the Caribbean. A proposal for measuring its incidence and trends

Includes bibliography

Fetal-Maternal Interactions in the Synepitheliochorial Placenta Using the eGFP Cloned Cattle Model

Background: To investigate mechanisms of fetal-maternal cell interactions in the bovine placenta, we developed a model of transgenic enhanced Green Fluorescent Protein (t-eGFP) expressing bovine embryos produced by nuclear transfer (NT) to assess the distribution of fetal-derived products in the bovine placenta. In addition, we searched for male specific DNA in the blood of females carrying in vitro produced male embryos. Our hypothesis is that the bovine placenta is more permeable to fetal-derived products than described elsewhere. Methodology/Principal Findings: Samples of placentomes, chorion, endometrium, maternal peripheral blood leukocytes and blood plasma were collected during early gestation and processed for nested-PCR for eGFP and testis-specific Y-encoded protein (TSPY), western blotting and immunohistochemistry for eGFP detection, as well as transmission electron microscopy to verify the level of interaction between maternal and fetal cells. TSPY and eGFP DNA were present in the blood of cows carrying male pregnancies at day 60 of pregnancy. Protein and mRNA of eGFP were observed in the trophoblast and uterine tissues. In the placentomes, the protein expression was weak in the syncytial regions, but intense in neighboring cells on both sides of the fetal-maternal interface. Ultrastructurally, our samples from t-eGFP expressing NT pregnancies showed to be normal, such as the presence of interdigitating structures between fetal and maternal cells. In addition, channels-like structures were present in the trophoblast cells. Conclusions/Significance: Data suggested that there is a delivery of fetal contents to the maternal system on both systemic and local levels that involved nuclear acids and proteins. It not clear the mechanisms involved in the transfer of fetal-derived molecules to the maternal system. This delivery may occur through nonclassical protein secretion; throughout transtrophoblastic-like channels and/or by apoptotic processes previously described. In conclusion, the bovine synepitheliochorial placenta displays an intimate fetal-maternal interaction, similar to other placental types for instance human and mouse. © 2013 Pereira et al.

Estrutura funcional do hepatopâncreas no processo digestivo em Macrobrachium amazonicum

Pós-graduação em Aquicultura - FCAV

Cadernos íntimos diários publicados: um estudo das práticas da escrita de diários, no âmbito das práticas sociais disseminadas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A formação do tecido discursivo em A Árvore das palavras, de Teolinda Gersão, e em A Manta do soldado, de Lídia Jorge

Pós-graduação em Estudos Literários - FCLAR

Desenvolvimento e caracterização de dispersão sólida com propriedade mucoadesiva para liberação de zidovudina

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nietzsche e o problema da verdade: o papel da linguagem na constituição da verdade e da moral

Pós-graduação em Filosofia - FFC

Sutiliezas entre o interno e o externo: literatura e sociedade nos contos de Menalton Braff

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Diários íntimos e literatura: a poesia de Carolina

Pós-graduação em Letras - FCLAS