RCAAP Repository

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

In this work we investigated the structural and electronic properties of the adsorption of biphenyl molecules on the Si(001) surface. We use the density functional theory with norm conserving psedopontial formalism. For the exchange-correlation energy we test both the local density and the generalized gradient approximations, where the last approach have been showed to give better results to describe the adsorpotion of a molecule on the Si surface. Our results show that the biphenyl molecule is adsorbed on the Si(001) surface in four different structures. This result is in agreement with experimental data where have been observed at least two different configurations for the biphenyl on the Si(001) surface. The binding energy for the most stable structure of the biphenyl is 2.48 eV. We observe that some molecule bonds with the Si surface are strong, while others on are not. By personating alternating dimer rows of the Si(001) surface with hydrogen atoms, our results show that the structure of the biphenyl on the Si surface keeps almost the same as that of the non-passivated surface. However there is a change of the stability: the most stable structure for the biphenyl on the saturated Si(001) surface is different from the structure of the biphenyl on the non saturated surface. With the adsorption of the biphenyl molecule on the Si(001) surface, the energy band gap suffer small changes. The presence of the biphenyl on the surface introduce energy levels inside de valence band and inside the conduction band. For non-passivated surfaces the band gap suffer very small reduction when the biphenyl is adsorbed. On the other hand for hydrogen passivated surfaces the band gap suffer an enlargement with the adsorption of the biphenyl molecule.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Study of the DNA-cisplatin system using the Density Functional Theory(DFT), compares the eficiency of the correlation and exchange functionals LDA and GGA (PBE) in the simulation of the nitrogen bases as well as the basis sets DZP and DZ. Taking DZP and LDA options and with the use of the norm-conserved pseudopotentials Ceperley-Alder, simulate the sistems; cisplatina, isolated DNA bases, pairs of bases, DNA fragment with two pairs of bases GG and on the DNA-ciplatin system attached in GG and GA bases. It presents script of execution for the gradual approach of the real structure of the DNA. Reedits for these structures facts established in scientific literature, as it presents new facts for the electronic distribution of the DNA. Argues based in the interaction of dipoles between cisplatin and DNA, the existence of a potential barrier that restricts the possibility of the bond for the case of the linking in sequence GA of the DNA.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

In this work, wecarry out theoretical study of the silicon surface reconstruction (7x7) grown in the [111] direction, denoted by Si(111) (7x7), using the Density Functional Theory formalism, within the Local Density Approximation (LDA) for the exchange correlation term. The interaction with the valence electrons and the core ion (nucleus more core electrons) was described by norm conserving, non local pseudopotential approach, compatible with the LDA. The one electron Kohn Sham equations was solved self consistently, by expanding the one electron functions in terms of linear combination of numerical atomic orbitals. All the calculations were realized using the Siesta computational code. Using the clean surface reconstruction model of Si(111) (7x7), propose by Takayanagi et al.[1, 2], we modeled the surface as a slab, in which the (7x7) unitary cell contained 200 Si atoms distributed in one adatom layer (Si atoms on the topmost layer) and the other four layers, with 49 H atoms used for saturate the dangling bonds of the most internal layer of the slab. The structural analysis of the Si(111) (7x7) reconstructed surface and the electronic structure analysis showed a good agreement with both the experimental and theoretical results disposable, reproducing correctly the band structure, the surface levels and the metallic character of this surface. The obtained energy per surface atom was 1,132 eV with respect to the bulk energy. It was performed the study of the vacancy energy formation of adatoms on this surface. We find an average value of 1,2 eV of a single vacancy formation of adatom the Si(111) (7x7) surface. The analysis of the energy bands made possible to identify the electronic states due to the adatoms dangling bonds. As a first application of the obtained results to the Si(111) (7x7) clean surface, we investigated the possible states of the physisorption of the chlorobenzene molecules on specific sites on the Si(111) (7x7) surface. This study showed that chlorobenzene molecules interact with the surface for distances around 3,0 Å from the adatoms. We also inferred that the triangular faulted subunit sites are energetically most favorable to the adsorption than the correspondent triangular unfaulted subunit sites. We plotted the adsorption energy curve of the chlorobenzene on the corner adatom at the triangular faulted unitary cell (7x7). The equilibrium distance and the adsorption energy obtained was 3,005 Å and 0,161 eV, respectively. The magnitude of this interaction corresponds to a physics adsorption of the chlorobenzene molecule on the Si(111) (7x7) surface.

This work presents the optical and morphological characterization of layer-by-layer (LBL) ultra-thin films from poly(p-phenylene vinylene) (PPV) and poly(o-methoxyaniline) (POMA). The PPV films were processed using the precursor polymer poly(xylylidene tetrahydrothiophenium chloride) (PTHT) and the sodium dodecylbenzenesulfonate (DBS). The films were deposited on glass substrate (BK7) with 2, 5, and 10 layers of POMA in esmeraldine salt form and 5, 10, 25 and 50 layers of PTHT+DBS. The PPV+DBS films on POMA layer were obtained from the thermal conversion process at 110oC and 230 oC under vacuum (10-2 atm) environment during 2 h. The optical characterizations were performed with absorbance, photoluminescence as function of the sample temperature, selective excitation, polarized absorbance and photoluminescence. The Raman spectroscopy and Atomic Force Microscopy (AFM) characterization were performed to study the structural and surface morphological properties, respectively, of LbL POMA/PPV films. The absorption experiment shows that the PPV+DBS layers are adsorbed in same ratio, independently, on the number of POMA layers and the thermal conversion temperature. The line shape of the photoluminescence (PL) is not affected with the PPV conversion reaction for all samples on POMA layer. High thermal stability of PPV was observed; witch the integrated PL decreasing only 10% when the temperature was increased from 10 to 300K. On the other hand, the PL spectra for LbL with 25 layers of PPV+DBS deposited on glass substrate decrease 80% in the same sample temperature range. The line shape of selective excitation spectra is similar of the absorbance one for LBL POMA/PPV films. The molecular order analyses through of the polarized absorbance and PL show that the POMA and PPV molecules are, preferential, oriented in the dip direction. This result was confirmed via AFM analysis. From Raman data, it was possible to identify the polymer/polymer interface region and the molecular group s interaction between POMA and PPV. Finally, a physical model was proposal based on experimental data to explain the optical properties of PPV on POMA layer.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

CAPÍTULO II:Incubation of erythrocytes in saline solutions with increasing concentrations of ethanol produces morphological and physicochemical alterations. In saline solution of 2% ethanol, erythrocytes are present in an expanded morphological state (R) and are designated as echinocytes. Between 12.52 and 16.10% ethanol in saline solution, the R state erythrocytes suffer a sigmoidal lysis transition, with a half-transition point (D50R) at 14.28% ethanol. But between 24.67 and 28.37%, erythrocytes present a stabilization transition with a half-transition point (S50) at 26.49% ethanol. In saline solution of 32% ethanol, integer erythrocytes are present, among lysed cells, in a contracted morphological state (T) and are designated as espherocytes. At 28.37% ethanol begins a sigmoidal lysis transition of the T state of the erythrocytes, with a half-transition point (D50T) at 34.76% ethanol. The stabilization transition followed but the destabilization transition by ethanol forms a hole or pocket in the lysis curve of erythrocytes by ethanol. The present work had the aim to study the effect of two osmolytes, glycerol and sorbitol, both at 1 mol.L-1, on the thermal dependence of the stabilization and destabilization of erythrocytes by ethanol in physiological saline solution. The stabilization transition was characterized by the half-transition point (S50) and by the deepness of the stabilization sigmoid (PS) of the erythrocytes, which constitutes an estimative of the stabilized population of erythrocytes. The lysis transition of the stabilized state (T) was characterized by the half-transition point (D50T) and by the deepness of the destabilization sigmoid (PD) of the erythrocytes, which constitute an estimative of the lysed population of erythrocytes. The S50 values presented statistically significant linear declines with the temperature increase in pure saline as in saline solution of glycerol and sorbitol; on the other side, the thermal dependence lines of S50 presented lower S50 values in saline solutions of glycerol or sorbitol than in a pure saline solution. This shall mean that the stabilization effect of the erythrocytes has an osmotic origin, since the temperature increase as the incorporation of glycerol or sorbitol to the solution increased the osmotic pressure of the medium. Although the PS values were not significantly changed by the temperature increase, the presence of glycerol and sorbitol produced significant thermal dependences for PS. At the lower temperatures of the interval the presence of glycerol or sorbitol decreased significantly the population of stabilized erythrocytes, but with the temperature increase there is an increase in the population of stabilized erythrocytes. This suggests that the stabilizing effect of ethanol doesn t have exclusively an osmotic origin, but also an action based on a direct interaction with the lipid bilayer of the membrane. The D50T values presented a negative and statistically significant dependence with the temperature increase in the pure saline solution as well in the saline solution of glycerol or sorbitol. Since the D50T values of the thermal dependencies lines were smaller in the presence of glycerol and sorbitol than they were in the pure saline solution, this indicates that the lysis of the T state of the erythrocytes would have an osmolar origin. The PD values presented positive and significant dependencies in pure saline solution as well as in saline solutions of glycerol and sorbitol. The smaller values of PD observed in saline solutions of glycerol and sorbitol at the lower temperatures of the thermal interval we considered are due to the smaller population of erythrocytes that were stabilized under those conditions. In summary, 1 mol.L-1 glycerol or sorbitol in physiologic saline solution and the temperature increase produce increments in the osmotic pressure of the medium and act in synergism with ethanol in the formation and in the lysis of the T state of the erythrocytes.

Universidade Federal de Uberlândia

Universidade Federal de Uberlândia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The growth of domestic animals and lactation in highly productive females are phases of life with special physiological characteristics and nutritional needs. Failure to adequately meet those needs may lead to negative effects on the animals physical development, productivity and performance. When interpreted correctly, the analysis of the biochemical serum profile of the individual animal or the herd is an effective tool for the detection of nutritional failures and imbalances, allowing for early corrective action to avoid impairing growth, productivity and performance. Its correct interpretation in animal species depends on specific regional reference values for the different phases of life, since various factors relating to both the animal and the environment may influence these values, leading to false results. In this context, the purpose of this study was to investigate the influence of age and sex on the biochemical serum profile of Postier Breton colts and on Doberman dogs in the growth phase, and the influence of the order and stages of lactation on the serum biochemistry of Saanen goats. In chapter 2, an analysis was made of 165 blood samples collected on five distinct occasions during a one-year period from 33 Postier Breton colts and fillies aged 9 days to 24 months. Greater activity of aspartate aminotransferase and creatine kinase enzymes was observed in the females, and age was found to influence the values of total proteins, albumin, globulins, A:G ratio, urea, uric acid, total cholesterol, total calcium, ionized calcium, phosphorus, Ca:P ratio, chlorides, alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyltransferase (GGT), alkaline phosphatase (ALP) and creatine kinase (CK). For the study on dogs in chapter 3, 132 blood samples were collected from 44 male and female Doberman dogs with ages ranging from 2 to 36 months. It was found that the mean values of most of the biochemical parameters of the dogs remained within the physiological intervals, and age was found to affect the serum concentrations of total proteins, albumin, globulins, A:G ratio, urea, creatinine, cholesterol, total calcium, ionized calcium, phosphorus, iron, ALT and ALP. The males presented a higher concentration of phosphorus and the females a higher Ca:P ratio. In chapter 4, an analysis was made of blood samples from 123 Saanen goats in the first, second and third period of lactation. The total proteins, glucose, triglycerides, total calcium, ionized calcium, AST and ALP values were found to be affected by both the order and the stages of lactation, while magnesium varied only between the phases of lactation. It was concluded that age influences the values of most of the biochemical serum parameters of Postier Breton colts and Doberman dogs, especially colts up to 12 months old and dogs up to 6 months old. The serum concentrations of glucose, triglycerides, total calcium, ionized calcium, magnesium, AST and ALP are effective biomarkers for the detection of energy and mineral imbalances in lactating goats. The results of this study may aid veterinary clinical pathologists in the interpretation of clinical biochemistry and in obtaining regional reference values.

Prostate cancer (PCa) has become a serious problem of public health for men. It is the second most diagnosed cancer, and even with the improvement of the clinical, histopathology and chemical techniques of detection, there is still a high mortality rate in consequence of the delayed or inefficient diagnosis of the illness. Finding more specific markers to increase the possibilities of cure and detection of the illness has been the objective of numerous researches. Several components involved on the protein synthesis in eukaryotes have been related with the oncogenic transformation. The alteration on the mRNA levels of the elongation factor 1 (EF1A) expression has been related to different types of cancer. A mutated form of this gene, PTI-1, has been associated with prostate cancer. This gene has an exclusive region of homology to Mycoplasma hyopneumoniae, 5´UTR, and a region of fusion, which contains sequences of homology to the M. hyopneumoniae and to the EF1A. It was originally described in the cellular lineage LNCaP, and its expression has been detected in tumoral cells while corresponding normal cells were negative. Our goal was to analyze the behavior of the expression of those two genes in samples of blood and of patients with PCa, benign prostatic hiperplasia (BPH) and in blood of young healthy men (control). We observed that the expression of EF1A in blood as in tissue was higher in patients of the PCa group. The groups had been subdivided in expression intervals 0.5, 0.5 1.0, 1.0 1.5 and >1.5 for better characterization. The relative levels of expression of the EF1A in tissue were estatistically correlated with the TNM staging, and presented a risk 4.6 times higher of PCa occurrence. In the BPH group, 90% of the patients presented lower mRNA expression levels. In the peripheral blood, we have observed for the interval lower than 0.5 that the probability of being PCa is 3 times higher than in the 1.5 interval, with a risk 10.56 times higher. The 5 UTR and the fusion regions, although observed in high rates in the PCa group, it has also been observed in BPH and the control groups. Its presence associated with EF1A expression level leads us to hipothetize that this gene modulates the EF1A expression in initial and final periods of the illness, determining an increase of the EF1A levels in order to guarantee the cellular proliferation and advance of the tumor confined to the organ; when the passage to metastasis phase occurs, PTI-1 seems to exert a control on the levels of EF1A as to reduce them, thus preventing the cells in the circulation come to suffer apoptosis.