THEORY OF ELASTICITY OF THE ABRIKOSOV FLUX-LINE LATTICE FOR UNIAXIAL SUPERCONDUCTORS - PARALLEL FLUX LINES

In this paper, we consider the extension of the Brandt theory of elasticity of the Abrikosov flux-line lattice for a uniaxial superconductor for the case of parallel flux lines. The results show that the effect of the anisotropy is to rescale the components of the wave vector k and the magnetic field and order-parameter wave vector cut off by a geometrical parameter previously introduced by Kogan.

EPIDERMAL GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-ALPHA CHARACTERISTICS OF HUMAN ORAL-CARCINOMA CELL-LINES

This study examined the expression of epidermal growth factor (EGF) cell-surface receptors, the response to exogenous ligand and the autocrine production of transforming growth factor a (TGF-a) in normal and carcinoma-derived human oral keratinocytes. One of eight malignant cell lines overexpressed EGF receptors, while the remainder expressed receptor numbers similar to normal cells. Exogenous EGF stimulated incorporation of tritiated thymidine in a dose-dependent manner. In keratinocytes expressing normal numbers of EGF receptors, the cellular response to exogenous EGF correlated positively with total EGF receptor number. SCC-derived keratinocytes produced more TGF-a than normal cells. There was no statistical correlation between the autocrine production of TGF-a, EGF cell-surface receptor expression and cellular response to exogenous EGF. While the growth-stimulatory effects of exogenous TGF-cl were inhibited by the addition of a neutralising antibody, the presence of this antibody in conditioned medium failed to produce a similar decrease in growth. The results indicate that overexpression of EGF receptors is not an invariable characteristic of human oral squamous carcinoma-derived cell lines. Further, the contribution of TGF-a to the growth of normal and carcinoma-derived human oral keratinocytes in vitro may be less significant than previously documented.

Characterization of the reversible photoinduced optical changes in Sb-based glasses

Changes occurring in absorption coefficients when glasses in the SbPO4-WO3 binary system were irradiated by light, at the edge of the absorption band, were measured in real time. These glasses present good thermal and optical properties and photoinduced changes in the absorption coefficients are reversible by heat treatment around 150 degrees C. Subsequent recording/erasing cycles could be made without sample degradation. The sensitivity of the induced optical changes was studied for different wavelengths, light powers and energy of light dose exposures, and for different compositions of the glasses. The changes in the absorption coefficients of the glass samples were accompanied by a color change from yellow to blue, and were also characterized by visible spectroscopy. The color changes occurred through the entire volume of the glass (similar to 2 mm thickness) for the Ar-ion laser lines at the edge of the absorption band. (c) 2006 Elsevier B.V. All rights reserved.

Effects of leucine supplemented diet on intestinal absorption in tumor bearing pregnant rats

Background: It is known that amino acid oxidation is increased in tumor-bearing rat muscles and that leucine is an important ketogenic amino acid that provides energy to the skeletal muscle.Methods: To evaluate the effects of a leucine supplemented diet on the intestinal absorption alterations produced by Walker 256, growing pregnant rats were distributed into six groups. Three pregnant groups received a normal protein diet (18% protein):pregnant (N), tumor-bearing (WN), pair-fed rats (Np). Three other pregnant groups were fed a diet supplemented with 3% leucine (15% protein plus 3% leucine):leucine (L), tumor-bearing (WL) and pair-fed with leucine (Lp). Non pregnant rats (C), which received a normal protein diet, were used as a control group. After 20 days, the animals were submitted to intestinal perfusion to measure leucine, methionine and glucose absorption.Results: Tumor-bearing pregnant rats showed impairment in food intake, body weight gain and muscle protein content, which were less accentuated in WL than in WN rats. These metabolic changes led to reduction in both fetal and tumor development. Leucine absorption slightly increased in WN group. In spite of having a significant decrease in leucine and methionine absorption compared to L, the WL group has shown a higher absorption rate of methionine than WN group, probably due to the ingestion of the leucine supplemented diet inducing this amino acid uptake. Glucose absorption was reduced in both tumor-bearing groups.Conclusions: Leucine supplementation during pregnancy in tumor-bearing rats promoted high leucine absorption, increasing the availability of the amino acid for neoplasic cells and, mainly, for fetus and host utilization. This may have contributed to the better preservation of body weight gain, food intake and muscle protein observed in the supplemented rats in relation to the non-supplemented ones.

Vertical marginal discrepancy of ceramic copings with different ceramic materials finish lines and luting agents: An in vitro evaluation

Statement of problem. Prosthetic restorations that fit poorly may affect periodontal health and occlusion. Studies that have evaluated the accuracy of fit of ceramic restorations before and after cementation assessed primarily intracoronal restorations.Purpose. This in vitro study evaluated the effect of different finish lines, ceramic manufacturing techniques, and luting agents on the vertical discrepancy of ceramic copings.Material and methods. Two stainless steel molars were prepared for complete crowns with 2 different finish lines (heavy chamfer and rounded shoulder); each molar was duplicated to fabricate 90 copings. A total of 180 copings generated 18 groups (n=10 for each finish line-coping material-luting agent combination). Luting agents tested included zinc phosphate, resin-modified glass ionomer (Fuji Plus), and resin composite cements (Panavia F). A metal frame was developed on which to screw the stainless steel model and a ceramic coping; the distance (mum) between 2 predetermined points was measured before and after cementation by a profile projector under a torquing force. A 4-way ANOVA with repeated measurements was performed to assess the influence of each factor in the vertical marginal discrepancy: 3 between-coping factors (finish line-coping material-luting agent) and 1 within-coping factor (before and after cementation) (alpha=.05).Results. Procera copings presented the lowest mean values (P<.05) of vertical marginal discrepancy before and after cementation (25/44 mum) when compared to Empress 2 (68/110 mum) and InCeram Alumina copings (57/117 mum), regardless of any combinations among all finish lines and luting agents tested.Conclusion. Considering each factor separately, the ceramic manufacturing technique appeared to be the most important factor tested for the definitive vertical discrepancy of all-ceramic copings, with lower mean values for Procera copings.

Local order around tungsten atoms in tungstate fluorophosphate glasses by X-ray absorption spectroscopy

X-ray absorption spectroscopy was used to study the local environment of tungsten atoms in NaPO3-BaF2,-WO3 glasses and the results were compared with crystalline references Na2WO4 and WO3. XANES measurements at the W-L-1 edge allowed to determine a distorted octahedral environment of tungsten atoms in these glasses similar to the local order of tungsten in monoclinic WO3. Extended X-ray absorption fine structure (EXAFS) has been used as a local probe to monitor the effect of WO3 concentration on the tungsten environment. Based on an analysis of the EXAFS data, we proposed a three-shell model of oxygen atoms around tungsten as in monoclinic WO3. With increasing WO3 concentration, it was found that R-2 decreases from 1.96 to 1.92 angstrom whereas R-3 increases from 2.07 to 2.12 angstrom. (c) 2005 Elsevier B.V. All rights reserved.

Evaluation of Bi as internal standard to minimize matrix effects on the direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry using Ru permanent modifier with co-injection of Pd/Mg(NO3)(2)

Bismuth was evaluated as an internal standard for the direct determination of Pb in vinegar by graphite furnace atomic absorption spectrometry using Ru as a permanent modifier with co-injection of Pd/Mg(NO3)(2). The correlation coefficient of the graph plotted from the non-nalized absorbance signals of Bi versus Pb was r=0.989. Matrix effects were evaluated by analyzing the slope ratios between the analytical curve, and analytical curves obtained from Pb additions in red and white wine vinegar obtained from reference solutions prepared in 0.2% (v/v) HNO3, samples. The calculated ratios were around 1.04 and 1.02 for analytical curves established applying an internal standard and 1.3 and 1.5 for analvtical curves without. Analytical curves in the 2.5-15 pg L-1 Pb concentration interval were established using the ratio Pb absorbance to Bi absorbance versus analvte concentration, and typical linear correlations of r=0.999 were obtained. The proposed method was applied for direct determination of Pb in 18 commercial vinegar samples and the Pb concentration varied from 2.6 to 31 pg L-1. Results were in agreement at a 95% confidence level (paired t-test) with those obtained for digested samples. Recoveries of Pb added to vinegars varied from 96 to 108% with and from 72 to 86% without an internal standard. Two water standard reference materials diluted in vinegar sample were also analyzed and results were in agreement with certified values at a 95% confidence level. The characteristic mass was 40 pg Pb and the useful lifetime of the tube was around 1600 firings. The limit of detection was 0.3 mu g L-1 and the relative standard deviation was <= 3.8% and <= 8.3% (n = 12) for a sample containing, 10 mu L-1 Pb with and without internal standard, respectively. (C) 2007 Elsevier B.V. All rights reserved.

Influence of moisture absorption on mechanical behaviour of composites

Because of their application that normally demands high mechanical strength combined with low weight, the fibre/matrix interface became an important parameter concerning structural life. The problem of moisture absorption in materials has received attention in experimental studies on a composite systems as well as from a theorical point of view. The fibre/matrix interface plays an important role in the structural behaviour of composites due to the fact that load transfer from matrix to reinforce occurs at the interface. In this case the study of compatibility of fibre/matrix/environmental is essential to ensure a product that attend structural objectives, many times without failure possibilities. The composite used in this investigation is the carbon fibre/matrix epoxy composite, which was immersed in sea water standard during 94 days at 60 degrees C, submitted to tensile and compressive tests to study the influence of moisture absorption on mechanical behaviour. The interface was investigated through fracture surface analysis by SEM and a strong interface and a good adhesion fibre/matrix was observed.

Optically pumped submillimeter laser lines from CD2Cl2 using a large tunability CW CO2 laser

Twenty-five new laser lines have been obtained is the wavelength region from 155 to 830 mu m by optically pumping the CD2Cl2 (deuterated dichloromethane) molecule with a CW CO3 laser having a tunability range of 300 MHz. The wavelength, polarization relative to that of CO2 pumping radiation, and offset relative to the CO2 center frequency were determined for all of the new lines and some other already known laser emissions. For all of them we give also the relative intensity and the optimum pressure of operation.

POTASSIUM FERTILIZATION, ROOT MORPHOLOGY AND POTASSIUM ABSORPTION BY SOYBEAN

A greenhouse experiment studied the effect of potassium fertilization on soybean (Glycine max L. Merrill) root morphology and on K absorption by six soybean cultivars of different maturation groups and growth habits. The Plants were grown up to 70 days after plant emergence, in pots containing 6.0 kg of soil. In the absence of K, no significant difference in K absorption was observed among the cultivars or in root length and surface, but root mean radius was correlated to K absorption. Differences in K absorption were not associated with root characteristics in the presence of K fertilization. Physiological adjustments in K uptake, as well as K availability in the soil, were more important in soybean nutrition than were morphological adjustments in the root system. The results were not associated with plant growth habit or with maturation group.

Maximum number of flux lines inside columnar defects

We set new limits for the maximum number of fluxons trapped inside columnar defects, for both cases of metallic and insulated cores. We show that the saturation limit predicted by the Mkrtchyan and Shmidt theory is just a first approximation to our results, because it does not consider the presence of the remaining flux lines exterior to the defects.

Small-angle X-ray scattering and X-ray absorption near-edge structure study of iron-doped siloxane-polyoxyethylene nanocomposites

The local and medium-range structures of siloxane-POE hybrids doped with Fe(III) ions and prepared by the sol-gel process were investigated by X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) and small-angle X-ray scattering (SAXS), respectively. The experimental results show that the structure of these composites depends on the doping level. EXAFS data reveal that, for low doping levels ([O]/[Fe] > 40, oxygens being of the ether-type of the POE chains), Fe(III) ions are surrounded essentially by a shell of chlorine atoms, suggesting the formation of FeCl4- anions. At high doping levels ([O]/[Fe] < 20), Fe(III) ions interacts mainly with oxygen atoms and form FeOx species. The relative proportion of FeOx species increases with iron concentration, this result being consistent with the results of SAXS measurements showing that increasing iron doping induces the formation of iron-rich nanodomains embedded in the polymer matrix.

Triiodothyronine mimics the effects of estrogen in breast cancer cell lines

MCF-7 (estrogen receptor positive - ER(+)) and MDA-MB-231 (estrogen receptor negative - ER(-)) are human breast cancer cell lines which express functional thyroid hormone receptors (c-erb A alpha 1 and c-erb beta 1) as indicated by stimulation of mitochondrial alpha-glycerophosphate dehydrogenase. In MCF-7, mimicking E(2), T-3 stimulated growth in a dose-dependent (10(10) M-10(-8) M) manner, induced the expression of progesterone receptor and growth factor TGF alpha mRNAs and inhibited that of TGF beta mRNA; T-3 also increased progesterone binding and LDH5 isozyme activities. None of these effects were observed in (ER(-)) MDA-MB-231 cells. 10(-6) M tamoxifen (TAM) reverted growth stimulation, suppressed progesterone receptor and TGF alpha mRNA induction and restored TGF beta mRNA to control levels in T-3-treated MCF-7 cells. That T-3 is acting in MCF-7 cells via its binding to ER is suggested by the immunoprecipitation of pre-bound I-125-T-3 from MCF-7 nuclear extracts by an ER-specific monoclonal antibody and by the displacement of H-3-estradiol binding to ER by radioinert T-3. Copyright (C) 1996 Elsevier B.V. Ltd.