The stir-frying can reduce hepatorenal toxicity of Fructus Tribuli by inactivating β-glucosidase and inhibiting the conversion of furostanol saponins to spirostanol saponins

The purpose of this study was to illustrate the mechanism of “enzyme inactivation and toxicity reduction” of Fructus Tribuli (FT) after being heating processed. Ultra-high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) was used to quantitatively analyze the contents of four steroidal saponins in crude Fructus Tribuli (CFT) and stir-fried Fructus Tribuli (SFT) under different storage times at room temperature. The enzyme activity of β-D-glucosidase in CFT and SFT were determined and calculated by ultraviolet–visible spectrometry (UV-VIS spectrometry). In addition, the enzyme hydrolysates of FOT and tribuluside A were qualitatively analyzed by ultra-high-performance liquid chromatography coupled with quadruple-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS). The hepatorenal toxicity of spirostanol saponins in FT were further confirmed by in vivo and in vitro experiment. This study confirmed that “enzyme inactivation and toxicity reduction” was one of the reasons why the stir-frying can reduce hepatorenal toxicity of FT, and further enriched the exploration on the mechanism of processing toxicity reduction.     

Low sputter damage of metal single crystalline surfaces investigated with medium energy ion scattering spectroscopy

It was observed clearly that the sputter damage due to Ar⁺ ion bombardment on metal single crystalline surfaces is extremely low and the local surface atomic structure is preserved, which is totally different from semiconductor single crystalline surfaces. Medium energy ion scattering spectroscopy (MEIS) shows that there is little irradiation damage on the metal single crystalline surfaces such as Pt(111), Pt(100), and Cu(111), in contrast to the semiconductor Si(100) surfaces, for the ion energy of 3–7 keV even above 10¹⁶–10¹⁷ ions/cm² ion doses at room temperature. However, low energy electron diffraction (LEED) spots became blurred after bombardment. Transmission Electron Microscopy (TEM) studies of a Pt polycrystalline thin film showed formation of dislocations after sputtering. Complementary MEIS, LEED and TEM data show that on sputtered single-crystal metal surfaces, metal atoms recrystallize at room temperature after each ion impact. After repeated ion impacts, local defects accumulate to degrade long range orders.     

Modelling of ligand–receptor interactions: ab-initio and DFT calculations of solvent reaction field effects on methylated ammonium–π and –acetate complexes

Interaction energies of increasingly methylated ammonium ions with aromatics (benzene, phenol, indole) and with acetate were calculated in vacuo and under the influence of polar media in order to model the binding of ammonium group containing ligands to receptors that offer either carboxylic or aromatic amino acid side chains as ligand anchoring alternatives. Semiempirical, ab-initio and DFT methods were applied to in vacuo calculations while the latter was used at the B3LYP6-31G(d) level in connection with the SCRF procedure of Miertu et al. [Chem. Phys. 55 (1981) 117] to simulate the free energies of transfer from the aqueous (=78.3) to the proteinaceous medium (=20). The in vacuo absolute interaction energies decrease with increasing methylation but the opposite becomes true under the influence of SCRF; only in the example of the tetramethylammonium ion the free energy stays negative. Concerning the interaction of the latter with acetate, it is only slightly more favourable than the binding of tetramethylammonium to indole. This result indicates that aromatic side chains are thermodynamically comparable to the carboxylic ones in the recognition process of the respective receptors for acetylcholine type ligands.     

Stability of viscous flow in a rotating porous medium in the form of an annulus: The small-gap problem

The paper deals with the linear stability analysis of laminar flow of a viscous fluid in a rotating porous medium in the form of an annulus bounded by two concentric circular impermeable cylinders. The usual no-slip condition is imposed at both the boundaries. The resulting sixth order boundary value, eigenvalue problem has been solved numerically for the small-gap case by the Runge-Kutta-Gill method, assuming that the marginal state is stationary. The results of computation reveal that the critical Taylor number increases with decreasing permeability of the medium. The problem is found to reduce to the case of ordinary viscous flow in the annulus obtained by Chandrasekhar,¹ when the permeability parameter tends to zero.     

Methylthiolate-induced reconstruction of Ag(1 1 1): A medium energy ion scattering study

Medium energy ion scattering (MEIS), using 100 keV H⁺ incident ions, has been used to investigate the structure of the Ag(1 1 1)(√7 × √7)R19° -CH₃S surface phase. The results provide the first direct evidence that this structure does involve substantial reconstruction of the Ag surface layer. The measured absolute scattered ion yields and blocking curves are in generally good agreement with a specific structural model of the surface based on a reconstructed layer containing 3/7 ML Ag atoms, previously suggested on the basis of scanning tunnelling microscopy (STM) and normal incidence X-ray standing wave (NIXSW) studies. However, the MEIS data indicate that any rumpling of the thiolate layer, is small, and probably ?0.2 Å. This value is smaller than the amplitude suggested in the STM and NIXSW studies, but could be entirely consistent with the earlier experimental data.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

痕量锗的HG-ICP测定及介质对其测定的影响的研究

采用氢化物发生-电感耦合等离子体原子发射光谱法测定痕量锗的方法,系统地考察了不同酸介质、NaBH₄浓度及共存元素的影响,确定了最佳测定条件。方法的检出限为0.2 ng·mL-1,精密度为0.9%。用环境标准物质进行对照,其测定值均在给定的标准范围之内。并且针对反应介质对锗测定的影响,进行了详尽的研究。     

Pseudomonas stutzeri 1317合成中长链聚羟基脂肪酸酯的组成分析模型

Pseudomonasstutzeri 1317可以在不同碳源上生长,合成不同共聚单体单元组成的中长链聚羟基脂肪酸酯(mclPHAs).本文在已知的代谢途径的基础上,提出了关于mclPHAs组成的数学模型,结果表明,mclPHAs的共聚单体单元组成主要取决于前体生成途径,以及该途径和聚合途径酶对不同碳原子数前体的选择性.实验结果与文献报道结果均验证了该模型.代谢控制分析的结果表明,碳数为8～10的前体的聚合效率最高.通过调制前体生成途径,可以有效调节PHA的单体单元组成.     

A Short and Versatile Synthesis of 3-Substituted 2-Aminoquinolines

A short and versatile synthesis of a series of 3-substituted -2-aminoquinolines was accomplished in good yields starting from 2-nitrobenzaldehide. Organic phosphonates were used as key synthetic intermediates and in some cases aminoacids as readily available starting materials. The finals two key steps of the sequence involving a reduction and ring closure that led to the 2-aminoquinoline skeleton were carried out in a “one pot” procedure using SnCl₂.2H₂O.     

Mass and energy flow management in the sector of surface treatment

Vehicle refinishing body shops are concerned by the environmental policy against photochemical air pollution caused by VOC emissions. For supporting these small enterprises the mass and energy flow model IMPROVE has been developed. Based on an LCA-approach, the process steps of vehicle refinishing are modelled. The model IMPROVE helps to disseminate the consequences of product substitution in comparison to so far used products and techniques in the body shop. For the dissemination of experiences practical guidelines have been developed. Moreover, a comprehensible tool for the Solvent Balance is being offered. Thus, various means are available for consulting and also for strategic production planning for the SME in the sector.