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Fundamental knowledge of the isotopic fractionation between the hydration water and the mother solution and whether the primary information recorded in hydration water can be preserved or not in deposits or mines have long been unclear. In order to calculate the accurate hydrogen and oxygen isotopic fractionation factors between gypsum hydration water and its mother solution with new methods, to understand the mechanism of fractionation and synthetically assess the record-keeping abilities of the isotopic composition of hydration water during the process of diagenesis after deposition, experiments on the hydrogen and oxygen isotopic compositions of gypsum hydration water and its mother solution at different isothermal temperatures from 5 to 50°C were systematically conducted. In addition, samples from two typical gypsum deposits formed in different environmental conditions were also determined. Results show that during gypsum crystallisation, both hydrogen and oxygen isotopes show significant fractionation between the hydration water and the mother solution. The calculated hydrogen isotopic fractionation factors are <1, while the oxygen isotopic fractionation factors are >1 at temperatures from 5 to 50°C. The fractionation factors show no functional relationships with temperature. Isotopic compositions of gypsum hydration water in arid lake sediments can be used to trace the source of water and primary deposit environmental information. However, the isotopic composition of the gypsum hydration water can easily be altered by dissolution and secondary precipitation of gypsum during later diagenesis, particularly in areas with humid climate and abundant groundwater. A very careful assessment on record-keeping abilities of the primary isotopic composition of hydration water in gypsum during later diagenesis must be considered before application. [ABSTRACT FROM AUTHOR]

This article proposes a thermal fatigue life prediction model for particle reinforced composites. First, a three-phase model was used to determine the effective eigen strain of a two-phase element formed by an ellipsoidal matrix shell surrounding an ellipsoidal particle, and then the disturbance strain in the two-phase element caused by thermal inconsistency was obtained. If the average stress in the effective medium was considered as vanished, the thermal stress field in the matrix and particles was obtained by considering random orientation of two-phase elements. Second, based on the interface cracks propagating around the ellipsoidal particles, the strain energy release rate was examined. When the strain energy release rate reached the critical value of the matrix, the debonding stress was determined. The subtending angle and initiation crack length were available. Finally, according to the low cycle fatigue crack growth rate formation, the thermal fatigue life was computed. The results show that the bigger the thermal stress is, the smaller the thermal fatigue life is, indicating that thermal fatigue life is an exponential function of crack initiation length and critical length. [ABSTRACT FROM AUTHOR]

Drilling fluid with the high density has been successfully used in many kinds of special formations such as gypsum salt bed, salt aquifer, or compound salt formation. Some problems with this kind of the fluid, however, still have to be considered, for example the high temperature resistance in some complicated deep wells, rheological properties control, and the influence of solid content to rheological properties. The authors introduce, based on the research about some important elements such as rheological properties and the quality of sedimentation stability, a drilling fluid with the high density of 2.45 g/cm³ that has good rheological properties, excellent qualities of sedimentation stability, low water loss, well antisloughing, and small lubrication coefficient, and which can be perfectly used in the deep slim-hole well with the high pressure salt aquifer. In addition, this drilling fluid system with the density of 2.45 g/cm³,no matter in the laboratory test or in the field case (No. 3 well of Jeddah), both performs excellently and controls well the salt crystallization, reducing the rate of the crystallization and preventing sticking, jets blocking, or torque increasing. Finally, with the successful application, this drilling fluid can be regarded as a good example for other deep wells or ultradeep wells with the complicated formation in Fergana Valley, Uzbekistan. [ABSTRACT FROM AUTHOR]

1. The objective of this study was to investigate the effects of diammonium glycyrrhizinate on the pharmacokinetics of aconitine in rats and the potential mechanism. 2. After oral administration of diammonium glycyrrhizinate (50 mg kg−1), the peak plasma concentration ( Cmax), area under the plasma concentration–time curve from zero to time τ (AUC0–τ), and absolute bioavailability of aconitine (0.2 mg kg−1) significantly increased 1.64-, 1.63- and 1.85-fold, respectively, but there was no significant change in half life ( t1/2) or clearance (CL). In the other two routes of administration via the tail vein and hepatic portal vein, diammonium glycyrrhizinate (15 mg kg−1) did not affect any of the pharmacokinetic parameters of aconitine (0.02 mg kg−1). Thus, diammonium glycyrrhizinate can enhance the absorption of aconitine, leading to higher oral bioavailability and plasma levels, but it does not influence its elimination. 3. Moreover, an in vitro everted gut sac model and Ussing chamber model were used to investigate the potential mechanism. Results from bidirectional transport and inhibition studies demonstrated that P-glycoprotein was the main efflux transporter involved in the absorption of aconitine in rats. The absorption enhancement effect of diammonium glycyrrhizinate should be mainly attributed to inhibiting the activity of P-glycoprotein rather than to the influence on the paracellular or transcellular transport. [ABSTRACT FROM AUTHOR]

The crystalline structure and dielectric properties of nominal Sm1.75Sr0.25NiO4 ceramics are presented. Three phases, Sm1.70Sr0.30NiO4, Sm2O3 and NiO, are found in the present ceramics, and the abundances are 77.7(1.1) wt%, 19.2(3) wt% and 6.1(2) wt%, respectively. The temperature-stable giant dielectric constant over 60 000 even up to 5 MHz is observed in a broad temperature range. The modulus plots show that the giant dielectric constant should be originated from the contribution of the grain interior instead of grain boundary. Compared with the other giant dielectric constant materials, the present materials have the great potentiality in the practical application, especially for the high frequency application. [ABSTRACT FROM AUTHOR]

A new tannin-related compound named bistortaside A ( 1 ) and a known compound have been isolated from the rhizome of Polygonum bistorta L. A new compound was elucidated as 3-methyl-gallic acid 4- O -β-d-(6′- O -3″-methyl-galloyl)-glucopyranoside and a known compound was quercetin-3′- O -β-d-glucopyranoside ( 2 ) on the basis of spectroscopic analysis. [ABSTRACT FROM AUTHOR]