Dating minerals by ID-TIMS geochronology at times of in situ analysis: selected case studies from the CPGeo-IGc-USP laboratory

Since 1964, the Center for Geochronological Research - CPGeo, one of the interdepartmental centers of the Instituto de Geociências (IG) of São Paulo University, has developed studies related to several geological processes associated with different rock types. Thermal Ionization Mass Spectrometry Isotopic Dilution (ID-TIMS) has been the technique widely used in the CPGeo U-Pb Laboratory. It provides reliable and accurate results in age determination of superposed events. However, the open-system behavior such as Pb-loss, the inheritance problem and metamictization processes allow and impel us to a much richer understanding of the power and limitations of U-Pb geochronology and thermochronology. In this article, we present the current methodology used at the CPGeo-IGc-USP U-Pb laboratory, the improvements on ID-TIMS method, and report high-precision U-Pb data from zircon, monazite, epidote, titanite, baddeleyite and rutile from different rock types of several domains of the Brazilian south-southeast area, Argentina and Uruguay.

Técnicas de diagnóstico de influência local na análise espacial da produtividade da soja

A modelagem da estrutura de dependência espacial pela abordagem da geoestatística é fundamental para a definição de parâmetros que definem esta estrutura, e que são utilizados na interpolação de valores em locais não amostrados pela técnica de krigagem. Entretanto, a estimação de parâmetros pode ser muito afetada pela presença de observações atípicas nos dados amostrados. O desenvolvimento deste trabalho teve por objetivo utilizar técnicas de diagnóstico de influência local em modelos espaciais lineares gaussianos, utilizados em geoestatística, para avaliar a sensibilidade dos estimadores de máxima verossimilhança e máxima verossimilhança restrita na presença de dados discrepantes. Estudos com dados experimentais mostraram que tanto a presença de valores atípicos como de valores considerados influentes, pela análise de diagnóstico, pode exercer forte influência nos mapas temáticos, alterando, assim, a estrutura de dependência espacial. As aplicações de técnicas de diagnóstico de influência local devem fazer parte de toda análise geoestatística a fim de garantir que as informações contidas nos mapas temáticos tenham maior qualidade e possam ser utilizadas com maior segurança pelo agricultor.

Photo-fenton degradation of poly(Ethyleneglycol)

Polyethyleneglycol (PEG) was photooxidized in a photo-Fenton system and results compared with the dark reaction. The products were analysed using GPC and HPLC. In the absence of light, PEG samples needed 490 min to reduce their w by 50%, whereas under UV irradiation, only 10 min were necessary. The exponential decay of w with a concomitant increase in polydispersity and number of average chain scission, characterized a random chain scission mechanism. The degradation products of PEG in both systems showed the presence of lower molecular weight products, including smaller ethyleneglycols and formic acid. The mechanism involves consecutive processes, were the larger ethyleneglycols give rise, successively, to smaller ones. This suggests that the mechanism involves successive scissions of the polymer chain. Irradiated samples decomposed faster than those kept in the dark This study proves that the foto-Fenton method associated with UV-light is a good reactant for PEG photodegradation.

The UV/H2O2 - photodegradation of poly(ethyleneglycol) and model compounds

The general mechanism for the photodegradation of polyethyleneglycol (PEG) by H2O2/UV was determined studying the photooxidation of small model molecules, like low molecular weight ethyleneglycols (tetra-, tri-, di-, and ethyleneglycol). After 30 min of irradiation the average molar mass (Mw) of the degradated PEG, analysed by GPC, fall to half of its initial value, with a concomitant increase in polydispersitivity and number of average chain scission (S), characterizing a random chain scission process yielding oligomers and smaller size ethyleneglycols. HPLC analysis of the photodegradation of the model ethyleneglycols proved that the oxidation mechanism involved consecutive reactions, where the larger ethyleneglycols gave rise, successively, to smaller ones. The photodegradation of ethyleneglycol lead to the formation of low molecular weight carboxylic acids, like glycolic, oxalic and formic acids.

The effect of using mixed initiator systems on the efficiency of photopolymerization of dental resins

A study was performed in order to determine the efficiency of the simultaneous use of the photoinitiators phenylpropanedione (PPD) and camphorquinone (CQ) in the polymerization of acrylic polymers and evaluate possible mechanisms leading to synergism or antagonism. It was found that efficiencies of both initiators taken individually are higher than that of their mixture, indicating that when both dyes are used simultaneously there will be an energy transfer from the more efficient initiator (CQ) to the less efficient one (PPD). Also, there was no proof of any reaction between the amine present in the CQ formulation and the PPD excited state.

Growth parameters and mortality rate of the Scomber japonicus peruanus (Jordán & Hubb, 1925) along the Peruvian coast, South Pacific

The growth parameters and the mortality rates of the Scomber japonicus peruanus (Chub mackerel) were studied based on monthly data of frequency of fork length classes obtained from commercial landings off the Peruvian coast from 1996 to 1998. The asymptotic body length and growth rate values obtained by the ELEFAN I (Electronic Length Frequency Analysis) ranged from 40.20 cm to 42.20 cm and from 0.38 to 0.39, respectively. The oscillation amplitude was 0.60; the Winter point values varied from 0.50 to 0.60 and the performance index from 2.79 to 2.84. The total mortality rate of the Chub mackerel obtained by the linearized catch curve oscillated between 1.68 and 3.35. The rate of fishing mortality varied from 1.16 to 2.78 and the exploitation rate from 0.68 to 0.84. The annual rate of natural mortality estimated by the Pauly's method ranged from 0.52 to 0.53. The results obtained allow us to conclude that the longevity of the Chub mackerel was slightly over seven years.

The influence of the 1992-1993 el niño on the reproductive biology of Scomber japonicus peruanus (Jordán & Hubb, 1925)

The influence of the 1992-1993 El Niño events on the reproductive behavior of the Scomber japonicus peruanus (Chub mackerel) was studied from samples collected monthly, along the Peruvian coast (3º23'S-14º00'S), from January 1990 to December 1993. The monthly variation of the gonadosomatic index and the frequency of the periods of gonad maturation evidenced that the spawning of the species occurred all year long, being more intense in summer. The values of the gonadosomatic index were higher during the occurrence of the 1992-1993 El Niño, while the body weight and gonad weight decreased. Regarding the condition factor, its values decreased in females over 35 cm in fork length.

Vertebrados da Estação Ecológica Serra Geral do Tocantins: faunística, biodiversidade e conservação no Cerrado brasileiro

Inventários e estudos faunísticos detalhados sobre vertebrados são uma das fontes mais relevantes de dados para interpretações de padrões detalhados de diversidade biológica. Dados básicos e de boa qualidade sobre faunística são ainda mais urgentes em regiões pouco estudadas e sob intensa ameaça antrópica, tais como a região do Cerrado, um dos 34 hotspots globais para a conservação da biodiversidade. Apresentamos aqui uma síntese dos resultados dos inventários de vertebrados na Estação Ecológica Serra Geral do Tocantins (~716.000 ha), a segunda maior unidade de conservação em todo o Cerrado. Foram registradas 450 espécies de vertebrados na EESGT e entorno imediato, incluindo 17 espécies ameaçadas, 50 espécies endêmicas do Cerrado e 11 espécies com distribuição potencialmente restrita. Do total de espécies amostradas, 180 são novos registros para a região do Jalapão. Ao menos 12 espécies amostradas foram consideradas potenciais espécies novas, das quais quatro foram descritas recentemente, a partir do material obtido no inventário. Os resultados evidenciam que a EESGT é uma das mais importantes áreas protegidas no Brasil central, contribuindo para a persistência de espécies ameaçadas, dependentes dos últimos grandes blocos contínuos de vegetação nativa de Cerrado. Nossos resultados indicam ainda que a conservação da EESGT e suas principais subunidades é crucial para a representatividade do sistema de áreas protegidas do Cerrado, protegendo potenciais endemismos restritos que aliam alta vulnerabilidade intrínseca e valor como indicadores de padrões e processos biogeográficos formadores da rica e cada vez mais ameaçada fauna Neotropical.

Insetos em presépios e as "formigas vestidas" de Jules Martin (1832-1906): uma curiosa manufatura paulistana do final do século XIX

Encontrados no Brasil desde os primórdios da colonização portuguesa, os presépios logo tiveram de adaptar-se à realidade local, circunstância muito propícia ao aparecimento de concepções heterodoxas e ao emprego de elementos exóticos da fauna e flora de cada região. Como registros envolvendo insetos são muito pouco comuns, chama a atenção que fêmeas de saúva, Atta sp. (Hymenoptera, Formicidae), tenham sido aproveitadas na composição de presépios no estado de São Paulo. Tendo subsistido pelo menos até a década 1960, os "presépios de formigas" existentes em cidades como Embu das Artes poderiam estar relacionados às "formigas vestidas" criadas por Jules Martin, curiosa manufatura paulistana do último quartel do século XIX.

Níveis de proteína bruta em dietas comerciais para suínos em crescimento e terminação

Avaliaram-se quatro níveis de proteína bruta (PB) em dietas consideradas comerciais fornecidas a suínos machos castrados nas fases de crescimento e terminação. Foram utilizados 48 machos castrados de mesma linhagem genética, com pesos iniciais de 30,8 ± 0,12 kg (fase de crescimento) e 61,2 ± 0,89 kg (fase de terminação), segregados no sistema de produção. Os animais foram distribuídos em delineamento experimental de blocos ao acaso, compostos de quatro tratamentos (níveis de PB) e seis repetições e dois animais por unidade experimental. Os níveis de PB testados foram 19,5; 18,0; 16,5 e 15,0% na fase crescimento e 18,0; 16,5; 15,0 e 13,5% na fase terminação. Na fase crescimento, não foram constatadas diferenças no desempenho dos machos castrados. Independentemente do nível de PB na dieta, as exigências nutricionais foram atendidas, não obstante, a dieta com 16,5% PB indicou maior viabilidade econômica, calculada como margem bruta decorrente da alimentação. Semelhante à fase de crescimento, na fase de terminação os níveis de PB da dieta não promoveram diferenças no desempenho e nas características de carcaça dos animais ao abate. Ao considerar a margem bruta atribuída à alimentação, a dieta com 15,0% PB permitiria maior retorno econômico no período correspondente ao intervalo dos 60 aos 100 kg. A variação da proteína dietética com a suplementação dos principais aminoácidos não prejudicou o desempenho de suínos machos castrados nas fases de crescimento e terminação criados em condições desejáveis de saúde, segregados, em sistema de criação comercial. Pequenas variações entre aminoácidos não prejudicam o desempenho de suínos machos castrados nas fases de crescimento e terminação, desde que as exigências de lisina digestível e dos demais aminoácidos limitantes sejam mantidas próximas às relações mínimas atualmente indicadas.

Hepatotrophic factors reduce hepatic fibrosis in rats

CONTEXT: Hepatic fibrosis occurs in response to several aggressive agents and is a predisposing factor in cirrhosis. Hepatotrophic factors were shown to stimulate liver growth and to restore the histological architecture of the liver. They also cause an improvement in liver function and accelerate the reversion of fibrosis before it progresses to cirrhosis. OBJECTIVE: To test the effects of hepatic fibrosis solution composed by amino acids, vitamins, glucose, insulin, glucagon and triiodothyronine on hepatic fibrosis in rats. METHODS: Fibrosis was induced in rats by gastric administration of dimethylnitrosamine (10 mg/kg) for 5 weeks. After liver biopsy, the rats received either hepatotrophic factors solution (40 mg/kg/day) or saline solution for 10 days by intraperitoneal injection. Blood samples and liver fragments were collected for hepatic function analysis, standard histopathology evaluation, and morphometric collagen quantification. RESULTS: Rats in the hepatotrophic factors group showed a decrease of the histopathological components of fibrosis and an increase of their hepatic mass (12.2%). There was no development of neoplasic lesions in both groups. Compared with the saline group, the hepatotrophic factors group also had a decrease of blood levels of hepatic-lesion markers (AST, ALT) and a decrease of collagen content in the portal spaces (31.6%) and perisinusoidal spaces (42.3%), as well as around the hepatic terminal vein (57.7%). Thus, hepatotrophic factors administration in the portal blood promoted a regenerative hepatic response, with an overall reduction of the volumetric density of collagen, improved hepatic function, and a general improvement in the histopathological aspects of fibrosis. CONCLUSION: Taken together, these results suggest the potential therapeutic use of this hepatotrophic factors solution to treat chronic liver diseases.

Importance of considering a material micro-failure criterion in the numerical modelling of the shot peening process applied to parabolic leaf springs

Shot peening is a cold-working mechanical process in which a shot stream is propelled against a component surface. Its purpose is to introduce compressive residual stresses on component surfaces for increasing the fatigue resistance. This process is widely applied in springs due to the cyclical loads requirements. This paper presents a numerical modelling of shot peening process using the finite element method. The results are compared with experimental measurements of the residual stresses, obtained by the X-rays diffraction technique, in leaf springs submitted to this process. Furthermore, the results are compared with empirical and numerical correlations developed by other authors.

Histometry of the sublingual gland in male and female mice (Mus musculus) infected with the RAL strain of the Chagas parasite, Trypanosoma cruzi

Trypanosoma cruzi. The aim of this work was to analyze histologically and histometrically the sublingual gland of mice infected with the RAL strain of T cruzi, according to the sex. Swiss mice (Mus musculus) were inoculated with 2 x 10(4) blood trypomastigotes of the RAL strain of T cruzi. In the peak of the parasitemia (12th day) the mice were sacrificed, and the sublingual glands were fixed in ALFAC. HE-stained histological sections were evaluated histometrically. The parasitemia was higher in females. Histopatologically, acini of the infected animals were smaller, with scanty production of secretion, and smaller striated ducts. The nuclei of the demilunes were smaller and showed amastigote nests in the cytoplasm. Karyometrically, nuclei of the acini, demilunes and striated ducts were smaller in the infected mice. Stereologically, it was observed that relative volumes of acini and ducts were smaller and, inversely, relative volumen were greater for the conjunctive tissue in the infected males. The surface densities of acini and ducts were bigger and the diameter and thickness of the wall were smaller in this group. On the other hand, relative volume of acini was smaller and those of the ducts and conjunctive tissue were bigger in the infected females. The diameter and thickness of the wall of acini were smaller, and those of the striated ducts were bigger in this group. The RAL strain of T cruzi caused general atrophy in the sublingual gland, with numerous nests of parasites in the glandular parenchyma.

Ergonomic Aspects Related to Surgeon Position in Laparoscopic Radical Prostatectomy

Purpose: The aim is to evaluate the level of inclination of the surgeon's spinal column (ISSC) while performing laparoscopic radical prostatectomy (LRP) when using one trocar on each side of the patient abdomen (""torero"" position) in two scenarios: With and without a thin head supporter adapted to the table. Materials and Methods: Based on trigonometric principles, we elaborated a formula to calculate the ISSC for a determined surgeon and surgical table while performing LRP in the torero position. The parameters considered were the width of the surgical table (m), the distance between the surgeon's anterior superior iliac spines (q), and the distance from the central point between the surgeon's anterior superior iliac spines to the surgeon's head (h). We used the formula alpha = 90 degree-cos(-1)(b/h) (where b = q/2 + m/2) in an Excel sheet to calculate the angle of inclination of the surgeon's spinal column. We applied the measures of 12 surgeons with different biotypes of our staff to calculate the ISSC with and without the thin head supporter. Results: The use of a thin head supporter reduced the mean ISCC in the torero position from 36.1 +/- 3.73 degrees (range 31.3 to 49.8 degrees) to 22.1 +/- 4.9 degrees (range 18.7 to 32.9 degrees), which corresponds to a reduction of 38.8% in the mean angle of inclination. This difference was statistically significant (P < 0.001). Conclusion: The use of a thin head supporter adapted to the surgical table objectively reduces lateral inclination of the surgeon's spinal column in the torero position, making LRP a more comfortable procedure.