DFT study on the water-assisted mechanism for the reaction between VO+ and NH3 to yield VNH+ and H2O

On the basis of DFT calculations, an understanding on the catalytic effect of water in the dehydration reaction between VO+ and NH3 to yield VNH+ and H2O has been obtained. The Gibbs free energy profiles point out that the global process involves two consecutive hydrogen shifts from the nitrogen to the oxygen atom. The catalytic role is achieved by a water assisted mechanism in which water acts as proton donor and acceptor, via transition structures corresponding to a six-membered rings. The corresponding stationary points lie below both the entrance VO+ + NH3, and VNH+ + H2O, channels. (c) 2006 Elsevier B... All rights reserved.

IDENTIFICATION OF A PUTATIVE MEMBRANE-INSERTED SEGMENT IN THE ALPHA-TOXIN OF STAPHYLOCOCCUS-AUREUS

To gain a fuller understanding of the regions of the Staphylococcus aureus alpha-toxin important in pore formation, we have used Forster dipole-dipole energy transfer to demonstrate that a central glycine-rich region of alpha-toxin (the so-called ''hinge'' region) inserts deeply into the bilayer on association of toxin with liposomes. Mutant alpha-toxins with unique cysteine (C) residues at positions 69 and 130 [Palmer, M., et al. (1993) J. Biol. Chem. 268, 11959) were reacted with the C-specific fluorophore acrylodan, which acted as an energy donor. The chosen acceptor was N-(7-nitrobenz-2-oxa-13-diazol-4-yl)-1,2-bis(hexadecanoyl) -sn-glycero-3-phosphoethanolamine (NBD-PE). Measurement of the degree of donor quenching with increasing NBD-PE in the inner bilayer leaflet enables the distance of closest approach between donor and acceptor to be estimated. For toxin labeled with acrylodan at position 130 (in the hinge region), this distance is approximately 5 +/- 2 Angstrom, showing that the probe is close to the inner surface of the liposomes. A second probe labeled at position 69 (in the N-terminal domain) shows negligible energy transfer, indicating a distance of closest approach >40 Angstrom. This implies that this N-terminal region remains ''outside'' the liposome. We propose a model in which the central region of the alpha-toxin inserts into the membrane and possibly participates in forming the wall of the pore.

Comparison of embryo yield and pregnancy rate between in vivo and in vitro methods in the same Nelore (Bos indicus) donor cows

To investigate why the preferred means to produce bovine embryos in Brazil has changed from in vivo to in vitro, we compared these two approaches in the same Nelore cows (n = 30) and assessed total embryo production and pregnancy rates. Without a specific schedule, all cows were subjected to ultrasound-guided ovum pick up (OPU)/in vitro production (IVP) and MOET, with intervals ranging from 15 to 45 d between procedures, respectively. To produce in vivo embryos, cows were superovulated and embryos were recovered nonsurgically from 1 to 3 times (1.4 +/- 0.6). whereas OPU/IVP was repeated from 1 to 5 times (3.2 +/- 1.2) in each donor cow during a 12-mo interval. Embryos obtained from both methods were transferred to crossbred heifers. on average. 25.6 +/- 15.3 immature oocytes were collected per OPU attempt. The average number of embryos produced by OPU/IVP (9.4 +/- 5.3) was higher (P < 0.05) than the MOET method (6.7 +/- 3.7). However, pregnancy rates were lower (P < 0.05) following transfer of IVP (33.5%) versus in vivo-derived embryos (41.5%) embryos. Embryonic losses between Days 30 and 60 and fetal sex ratio were similar (P > 0.05) between in vivo and in vitro-derived embryos. We concluded that in Nelore cows, with an interval of 15 d between OPU procedures, it was possible to produce more embryos and pregnancies compared to conventional MOET. (C) 2009 Elsevier B.V. All rights reserved.

Energy States of Phosphorous Donor in Silicon in Fields up to 18 T

The evolution of the energy states of the phosphorous donor in silicon with magnetic field has been the subject of previous experimental and theoretical studies to fields of 10 T. We now present experimental optical absorption data to 18 T in combination with theoretical data to the same field. We observe features that are not revealed in the earlier work, including additional interactions and anti-crossings between the different final states. For example, according to the theory, for the "1s -> 2p (+)" transition, there are anti-crossings at about 5, 10, 14, 16, and 18 T. In the experiments, we resolve at least the 5, 10, and 14 T anti-crossings, and our data at 16 and 18 T are consistent with the calculations.

Effects of timing of induced luteolysis in embryo donor mares on reproductive performance and pregnancy rate in recipient mares

The objective was to evaluate the effects of giving prostaglandin F(2 alpha) (PGF) to donor mares 48 h prior to embryo collection. Non-lactating donor mares (n = 20 estrous cycles in 10 mares), ranging from 2.5 to 10 y of age and 400 to 500 kg of body weight were used from September 2004 to February 2005 in the southern hemisphere (Brazil). Donor mares were randomly assigned in a cross-over design study. During a Treated cycle, 7.5 mg PGF was given 48 h prior to embryo collection, whereas in the Control cycle, 7.5 mg PGF was given at embryo collection. In Treated Cycles, serum progesterone concentrations decreased between the day of PGF treatment and the day of embryo collection (13.9 +/- 5.4 and 0.5 +/- 0.3 ng/mL, respectively; P < 0.05). In Treated versus Control cycles, the interovulatory interval was shorter (14.9 +/- 0.9 vs 17.5 +/- 1.1 d, P < 0.05). However, there was no significant difference between these groups for the interval from PGF to ovulation (average, 9.8 d), embryo recovery rate (average, 75%), embryo quality, uterine protein concentration, and pregnancy rate in recipient mares (average, 87% at 15 d after ovulation, with no pregnancy loss detected by 60 d). In conclusion, giving donor mares PGF 48 h prior to embryo collection reduced the average interovulatory interval by approximately 2.5 d, thereby potentially increasing the numbers of embryos that could be collected during a breeding season, with no deleterious effects on embryo recovery rate, embryo quality, or pregnancy rate in recipient mares. (c) 2011 Elsevier B.V. All rights reserved.

Exploring the binding mechanism of Guaijaverin to human serum albumin: Fluorescence spectroscopy and computational approach

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Kidney transplants from living nonrelated donors: An analysis of 87 cases, including 20 cases with specific blood transfusions from the donor

The aim of this paper is to analyze 87 cases of kidney transplants obtained from nonrelated donors; in 20 of these, a donor-specific transfusion procedure4 was added to the pretreatment protocol of each recipient.

Room-temperature photoluminescence in amorphous SrTiO3-The influence of acceptor-type dopants

Room-temperature photoluminescence (PL) was observed in undoped and 2 mol% Cr-, Al- and Y-doped amorphous SrTiO3 thin films. Doping increased the PL, and in the case of Cr significantly reduced the associated PL wavelength. The optical bandgaps, calculated by means of UV-vis absorption spectra, increased with crystallinity and decreased with the doping level. It was considered that yttrium and aluminum substituted Sr2+, whereas chromium replaced Ti4+. It is believed that luminescence centers are oxygen-deficient BO6 complexes, or the same centers with some other defects, such as oxygen or strontium vacancies, or BO6 complexes with some other defects placed in their neighborhood. The character of excitation and the competition for negatively charged non-bridging oxygen (NBO) among numerous types of BO6 defect complexes in doped SrTiO3 results in various broadband luminescence peak positions. The results herein reported are an indicative that amorphous titanates are sensitive to doping, which is important for the control of the electro-optic properties of these materials. The probable incorporation of Cr into the Ti site suggests that the existence of a double network former can lead to materials displaying a more intense photoluminescence.

Microstructure of doped barium titanate prepared from polymeric precursors

Barium titanate is used extensively as a dielectric in ceramic capacitors, particularly due to its high dielectric constant and low dielectric loss characteristics. It can be made semiconducting by addition of certain dopants and by proper modification of grains and grain boundary properties obtaining very interesting characteristics for various applications. The synthesis method and sintering regime have a strong influence on properties of obtained barium titanate ceramics. Doped barium titanate was prepared with Nb+5 and Y+3 ions as donor dopants, and with Mn+2 ions as acceptor dopant by polymeric precursors method. By this procedure nanosized powders were obtained after calcination. Sintering was performed in the temperature range of 1290°C to 1380°C The microstructure of doped BaTiO3 was performed using scanning electron microscopy. The influence of dopants and sintering temperature on grain size was analysed.

Spectrophotometric flow-injection determination of sulphite in white wines involving gas diffusion through a concentric tubular membrane

A flow-injection system is proposed for the spectrophotometric determination of sulphite in white wines. The method involves analyte conversion to SO2, gas diffusion through a Teflon® semi-permeable membrane, collection into an alkaline stream (pH 8), reaction with Malachite green (MG) and monitoring at 620 nm. With a concentric tubular membrane, the system design was simplified. Influence of reagent concentrations, pH of donor and acceptor streams, temperature, timing, surfactant addition and presence of potential interfering species of the wine matrix were investigated. A pronounced (ca. 100%) enhancement in sensitivity was noted by adding cetylpyridinium chloride (CPC). The proposed system is robust and baseline drift is not observed during 4 h operating periods. Only 400 μL of sample and 0.32 mg MG are required per determination. The system handles 30 samples per hour, yielding precise results (r.s.d. < 0.015 for 1.0 - 20.0 mg L-1 SO2) in agreement with those obtained by an alternative procedure.

Structure study of donor doped barium titanate prepared from citrate solutions

Barium titanates doped with Nb5+, and Y3+, were prepared. The starting powders were synthesized from citrate solutions by the Pechini process and partial Pechini process in two steps. Sintering was performed in the range from 1310° up to 1380°C for 2 hours in air atmosphere. The structural study concerning the incorporation of Nb and Y ions in the barium titanate crystal lattice was performed by XRD, XANES and EXAFS techniques. The dielectric properties were analyzed and the relationship between properties and structure of doped barium titanate was established.

Crystal and molecular structure of dinuclear palladium(II) complex containing nitrogen and phosphorus donor ligands, [Pd2(N3)4(PPh3)2(μ-ted)]

The dinuclear azido-palladium(II) complex [Pd2(N3)4(PPh3)2(μ-ted)], where PPh3 = triphenylphosphine and ted = triethylenediamine, was synthesized and characterized by single-crystal X-ray diffraction. The title compound was crystallized in a triclinic system, space group P1 with a = 11.5875(2)Å, b = 13.0817(3)Å, c = 15.2618(3)Å, α = 93.306(2)°, β =110.040(1)°, γ = 98.486(1)°, V = 2134.95(8)Å3, Z = 2. Each Pd(II) center displays a distorted squareplanar coordination environment formed by two N atoms from two trans terminally coordinated azido groups, one P atom from the phosphine and one N atom from the bridging ted ligand. 2008 © The Japan Society for Analytical Chemistry.

Re-conceptualizing the international aid structure: recipient donor interactions and the rudiments of a feedback mechanism

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Autogenous bone combined with anorganic bovine bone for maxillary sinus augmentation: Analysis of the osteogenic potential of cells derived from the donor and the grafted sites

Objectives: This study aimed to comparatively evaluate the in vitro osteogenic potential of cells obtained from the mandibular ramus (MR, autogenous bone donor site) and from the maxillary sinus (MS) bone grafted with a mixture of anorganic bovine bone (ABB) and MR prior to titanium implant placement (MS, grafted implant site). Material and methods: Cells were obtained from three patients subjected to MS floor augmentation with a 1: 1 mixture of ABB (GenOx Inorg®) and MR. At the time of the sinus lift procedure and after 8 months, prior to implant placement, bone fragments were taken from MR and MS, respectively, and subjected to trypsin-collagenase digestion for primary cell culturing. Subcultured cells were grown under osteogenic condition for up to 21 days and assayed for proliferation/viability, osteoblast marker mRNA levels, alkaline phosphatase (ALP) activity and calcium content/Alizarin red staining. ALP activity was also determined in primary explant cultures exposed to GenOx Inorg® (1: 1 with MR) for 7 days. Data were compared using either the Mann-Whitney U-test or the Kruskal-Wallis test. Results: MS cultures exhibited a significantly lower osteogenic potential compared with MR cultures, with a progressive increase in cell proliferation together with a decrease in osteoblast markers, reduced ALP activity and calcium content. Exposure of MR-derived primary cultures to GenOx Inorg® inhibited ALP activity. Conclusion: These results suggest that the use of GenOx Inorg® in combination with MR fragments for MS floor augmentation inhibits the osteoblast cell differentiation at the implant site in the long term. © 2013 John Wiley & Sons A/S.