In Vitro Effect of Crude Extract from Traganum Nudatum on Glucose-Uptake in Liver Slices Isolated from Westar Rats

Background: Diabetes mellitus is a metabolic disorder characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action, or both. There are many classes of drugs used for treatment, and these include insulin sensitizers, insulin secretagogues, and agents that delay the absorption of carbohydrates from the bowel. This study intends to investigate the effect of crude extract from a plant from South Algeria Traganum nudatum (Chenopodiaceae) on glucose uptake in liver slices isolated from  Wistar rats. Methods: The liver slices were incubated for 90 min at 37° in normoglycaemic (1g/l of glucose)  and hyperglycaemic (3g/l of glucose) KRBA Krebs Ringer Bicarbonate Albumin 4% media using  24 well-polyethylene plates. In each, well different concentrations of insulin (10, 50 and 100µU/ml)  and hydromethanolic crude extract (100, 200 and 500µg/ml) were added. After every 30 minutes, aliquots of the culture media were assayed for the determination of glucose left. Results: Tests showed that the glucose left after 90 minutes in the media which contained insulin at 100µg/ml was the lowest (0.44 and 1.41 )g/l in the normo and hyperglycaemic media respectively, which reflect that insulin at this concentration was the most effective on the stimulation of glucose uptake. The extract had the highest effect at 500µg/ml, the concentrations of glucose left after 90 minutes of incubation were found to be (0.38 and 1.31)g/l in the normoglycaemic and hyperglycaemic media respectively. Conclusion: From the obtained results, it can be concluded that our extract seems to have an insulin-like effect on glucose uptake in liver slices isolated from Wistar rats

Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions

We report a combined experimental and theoretical study of the melting curve and the structural behavior of vanadium under extreme pressure and temperature. We performed powder x-ray diffraction experiments up to 120 GPa and 4000 K, determining the phase boundary of the bcc-to-rhombohedral transition and melting temperatures at different pressures. Melting temperatures have also been established from the observation of temperature plateaus during laser heating, and the results from the density-functional theory calculations. Results obtained from our experiments and calculations are fully consistent and lead to an accurate determination of the melting curve of vanadium. These results are discussed in comparison with previous studies. The melting temperatures determined in this study are higher than those previously obtained using the speckle method, but also considerably lower than those obtained from shock-wave experiments and linear muffin-tin orbital calculations. Finally, a high-pressure high-temperature equation of state up to 120 GPa and 2800 K has also been determined

X-ray diffraction measurements of Mo melting to 119 GPa and the high pressure phase diagram

In this paper, we report angle-dispersive X-ray diffraction data of molybdenum melting, measured in a double-sided laser-heated diamond-anvil cell up to a pressure of 119 GPa and temperatures up to 3400 K. The new melting temperatures are in excellent agreement with earlier measurements up to 90 GPa that relied on optical observations of melting and in strong contrast to most theoretical estimates. The X-ray measurements show that the solid melts from the bcc structure throughout the reported pressure range and provide no evidence for a high temperature transition from bcc to a close-packed structure, or to any other crystalline structure. This observation contradicts earlier interpretations of shock data arguing for such a transition. Instead, the values for the Poisson ratios of shock compressed Mo, obtained from the sound speed measurements, and the present X-ray evidence of loss of long-range order suggest that the 210 GPa ( ∼ 4100 K) transition in the shock experiment is from the bcc structure to a new, highly viscous, structured [email protected]

Pressure dependence of the silicon carbide synthesis temperature

The starting temperature for SiC synthesis from elemental silicon, carbon black, and graphite powders was determined for pressures ranging from 0.8 to 11 GPa by in situ X-ray diffraction experiments. The synthesized SiC corresponds to the cubic 3C phase with the presence of stacking faults along the [111] direction. The lowest density of the stacking faults is achieved when black carbon is used instead of graphite. The minimum temperature to start the Si + C → SiC reaction slightly decreases when the pressure is increased up to 6 GPa and the reaction begins before silicon melts. For pressures higher than 8 GPa, the starting temperature increases, and the formation of SiC from the SiII phase requires the complete melting of silicon. Bulk modulus Bo= 236(14) GPa was obtained for the synthesized SiC phase.Fil: Limandri, Silvina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Garbarino, G.. European Synchrotron Radiation; FranciaFil: Sifre, D.. European Synchrotron Radiation; FranciaFil: Mezouar, M.. European Synchrotron Radiation; FranciaFil: Galván Josa, Víctor Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin

Absence of a structural transition up to 40 Gpa in MgB2 and the relevance of magnesium non-stoichiometry

We report measurements on MgB2 up to ~40GPa. Increasing pressure yields a monotonous decrease of the lattice parameters and of the c/a ratio, but no structural transition down to parameters smaller than those of AlB2. The transition superconducting temperature also decreases with temperature in a sample dependent way. The results are explained by an increase of the filling of the 2D pxy bands with pressure, the Mg stoichiometry determining the starting position of the Fermi level. Our measurements indicate that these hole bands are the relevant ones for superconductivity.Comment: submitted March 9th 2001, PRB accepte

An Integrated Method for Accurate Determination of Melting in High-Pressure Laser Heating Experiments

We present an integrated approach for melting determination by monitoring several criteria simultaneously. In particular we combine x-ray diffraction observations with the detection of discontinuities in the optical properties by spectroradiometric measurements. This approach significantly increases the confidence of melt identification, especially with low-Z samples. We demonstrate the method with observations of melt in oxygen at 47 and 55 gigapascals

Deep carbon cycle constrained by carbonate solubility.

Earth's deep carbon cycle affects atmospheric CO2, climate, and habitability. Owing to the extreme solubility of CaCO3, aqueous fluids released from the subducting slab could extract all carbon from the slab. However, recycling efficiency is estimated at only around 40%. Data from carbonate inclusions, petrology, and Mg isotope systematics indicate Ca2+ in carbonates is replaced by Mg2+ and other cations during subduction. Here we determined the solubility of dolomite [CaMg(CO3)2] and rhodochrosite (MnCO3), and put an upper limit on that of magnesite (MgCO3) under subduction zone conditions. Solubility decreases at least two orders of magnitude as carbonates become Mg-rich. This decreased solubility, coupled with heterogeneity of carbon and water subduction, may explain discrepancies in carbon recycling estimates. Over a range of slab settings, we find aqueous dissolution responsible for mobilizing 10 to 92% of slab carbon. Globally, aqueous fluids mobilise [Formula: see text]% ([Formula: see text] Mt/yr) of subducted carbon from subducting slabs