Photodegradation of Folate Sensitized by Riboflavin

Folate is shown to react with singlet-excited state of riboflavin in a diffusion controlled reaction and with triplet-excited state of riboflavin in a somewhat slower reaction with (3)k(q) = 4.8 x 10(8) L mol(-1) s(-1) in aqueous phosphate buffer at pH 7.4, ionic strength of 0.2 mol L(-1), and 25 degrees C. Singlet quenching is assigned as photo-induced reductive electron transfer from ground state folate to singlet-excited riboflavin, while triplet quenching is assigned as one-electron transfer rather than hydrogen atom transfer from folate to triplet-excited riboflavin, as the reaction quantum yield, phi = 0.32, is hardly influenced by solvent change from water to deuterium oxide, phi = 0.37. Cyclic voltammetry showed an irreversible two-electron anodic process for folate, E = 1.14 V versus NHE at a scan-rate of 50 mV s(-1), which appears to be kinetically controlled by the heterogeneous electron transfer from the substrates to the electrode. Main products of folate photooxidation sensitized by riboflavin were pterin-6-carboxylic acid and p-aminobenzoyl-L-glutamic acid as shown by liquid chromatographic ion-trap mass spectrometry (LC-IT-MS).

Perspective: LaGuardia Community College Newsletter (09 May 1974)

vol. II, no. IV; "A newsletter published periodically to keep the faculty, students, staff, and community informed about the activities taking place on the campus of LaGuardia Community College."

Porque favorecer firmas nacionais?

In this paper we offer a rationale for the existence of preferences for domestic…rms in government procurement. When the domestic…rm’s probability of completion of a government contract is larger than the foreign …rms probability of completion, the government should favor domestic…rms in order to maximize the expected net bene…tof the project. We compute the…rms’ equilibrium strategies for a lowest offer procurement auction. We also compute numerically the level of preferences that maximizes the government’s net expected bene…t under different parameter values.

Impactos de restrições sobre empresas listadas na BM&F Bovespa : um survey a partir da crise de 2008/09

Por meio de um survey, ouvimos 56 gestores financeiros e de relações com investidores de empresas listadas na BM&F Bovespa sobre o grau das restrições financeiras observadas durante a crise de 2008/09, contrapondo diferenças entre firmas que declararam ter sofrido restrições àquelas que disseram não terem sido afetadas. Nossa evidência aponta que as restritas rebaixaram os preços praticados e demitiram colaboradores em dose maior do que as irrestritas. As restritas também acusaram salto pronunciado no endividamento, enquanto as irrestritas conservaram suas fontes de financiamento, buscando preservar reputação no mercado. Cerca de 65% das firmas restritas indicam que as restrições financeiras afetaram a capacidade de aceitar projetos atrativos, e 25% dessas firmas se viram forçadas a postergar/cancelar investimentos vantajosos. Comparando a medida direta de nosso survey frente a proxies usualmente adotadas, cremos que este trabalho agrega ao espectro de ferramentas empregadas para avaliar o impacto de restrições financeiras sobre as decisões corporativas.

A note on financial regulation and the brazilian response to the 2008‐09 financial crisis

Brazil was frequently criticized for its interventionist and heavy financial regulation up until the 2008‐09 world financial crisis.  According to the neo‐liberal or pro‐market view that predominated in academic and financial circles during the early 2000s, economic development came together with financial deepening, which in its turn could only be achieved through financial liberalization and deregulation. The currency crises of the 1990s notwithstanding, by the mid‐2000s Brazil’s segmented financial market and its restrictive reserve and capital requirements were seen as a symbol of inefficiency and backwardness by most financial specialists.  To the luck of the Brazilian population, most of the advices of such specialists were ignored by the Brazilian authorities, so that, when the 2008 financial crisis hit the world economy, Brazil still had powerful and efficient instruments to deal with the problem.  The objective of this note is to present the mains aspects of the Brazilian financial regulation and how they helped the economy to deal with the consequences of 2008‐09 financial meltdown.

Remoção de óleo da água de produção por flotação em coluna utilizando tensoativos de origem vegetal

In the petroleum industry, water is always present in the reservoir formation together with petroleum and natural gas and this fact provokes the production of water with petroleum, resulting in a great environmental impact. Several methods can be applied for treatment of oily waters, such as: gravitational vases, granulated media filtration systems, flotation process, centrifugation process and the use of hydrocyclones, which can also be used in a combined way. However, the flotation process has showed a great efficiency as compared with other methods, because these methods do not remove great part of the emulsified oil. In this work was investigated the use of surfactants derived from vegetable oils, OSS and OGS, as collectors, using the flotation process in a glass column with a porous plate filter in its base for the input of the gaseous steam. For this purpose, oil/water emulsions were prepared using mechanical stirring, with concentrations around 300 ppm. The air flow rate was set at 700 cm3/min and the porous plate filter used for the generation of the air bubbles has pore size varying from 16 to 40 Pm. The column operated at constant volume (1500mL). A new methodology has been developed to collect the samples, where, instead of collecting the water phase, it was collected the oil phase removed by the process in the top of the flotation column. It has been observed that it is necessary to find an optimum surfactant concentration to achieve enhanced removal efficiency. Being for OSS 1.275 mmol/L and for OGS 0.840 mmol/L, with removal efficiencies of 93% and 99%, respectively, using synthetic solutions. For the produced water, the removal in these concentrations was 75% for OSS and 65% for OGS. It is possible to remove oil from water in a flotation process using surfactants of high HLB, fact that is against the own definition of HLB (Hydrophile-Lipophile Balance). The interfacial tension is an important factor in the oil removal process using a flotation process, because it has direct interference in the coalescence of the oil drops. The spreading of the oil of the air bubble should be considered in the process, and for the optimum surfactant concentrations it reached a maximum value. The removal kinetics for the flotation process using surfactants in the optimum concentration has been adjusted according to a first order model, for synthetic water as for the produced water.

Ecological efficiency in thermoelectric power plants

This work evaluates the environmental impact resulting from the natural gas and diesel combustion in thermoelectric power plants that utilize the combined cycle technology (CC), as regarding to Brazilian conditions according to Thermopower Priority Plan JPP). In the regions where there are not natural gas the option has been the utilization of diesel and consequentily there are more emission of pollutants. The ecological efficiency concept, which evaluates by and large the environmental impact, caused by CO2, SO2, NOx and particulate matter (PM) emissions. The combustion gases of the thermoelectric power plants working with natural gas (less pollutant) and diesel (more pollutant) cause problems to the environment, for their components harm the human being life, animals and directly the plants. The resulting pollution from natural gas and diesel combustion is analyzed, considering separately the CO2, SO2, NO2 and particulate matter gas emission and comparing them with the in use international standards regarding the air quality. It can be concluded that it is possible to calculate thermoelectric power plant quantitative and qualitative environment factor, and on the ecological standpoint, for plant with total power of 41441 kW, being 27 170 kW for the gas turbine and 14271 kW for the steam turbine. The natural gas used as fuel is better than the diesel, presenting ecological efficiency of 0.944 versus 0.914 for the latter, considering a thermal efficiency of 54% for the combined cycle. (c) 2006 Elsevier Ltd. All rights reserved.

Effect of iron on enamel demineralization and remineralization in vitro

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biocompatibility Evaluation of 3 Facial Silicone Elastomers

The failure of facial prostheses is caused by limitations in the properties of existing materials, especially the biocompatibility. This study aimed to evaluate the biocompatibility of maxillofacial silicones in subcutaneous tissue of rats. Thirty Wistar rats received subcutaneous implants of 3 maxillofacial silicone elastomers (LIM 6050, MDX 4-4210, and industrial Silastic 732 RTV). A histomorphometric evaluation was conducted to analyze the biocompatibility of the implants. Eight areas of 60.11 mm(2) from the surgical pieces were analyzed. Mesenchymal cells, eosinophils, and foreign-body giant cells were counted. Data were submitted to analysis of variance and Tukey test. Initially, all implanted materials exhibited an acceptable tissue inflammatory response, with tissue reactions varying from light to moderate. Afterward, a fibrous capsule around the silicone was observed. The silicones used in the current study presented biocompatibility and can be used for implantation in both medical and dental areas. Their prosthetic indication is conditioned to their physical properties. Solid silicone is easier to adapt and does not suffer apparent modifications inside the tissues.

Sistema reprodutivo do Ipê-Branco: Tabebuia roseo-alba (Ridley) Sandwith (Bignoniaceae)

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

Search for charge-asymmetric production of W ' bosons in t(t)over-bar + jet events from pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the Electron Charge Asymmetry in Inclusive W Production in pp Collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for pair production of first- and second-generation scalar leptoquarks in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)