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In order to investigate the tensile deformation behavior of ultra-high-strength-steel BR1500HS, a series of isothermal tensile experiments were carried out in a temperature range of 1023˜1123 K and a strain rate range of 0.01˜10 s−1 on a Gleeble-3500 thermo-mechanical simulator. The results indicate that the flow stress initially increases to a peak value and then decreases gradually to a steady state. Based on the analysis of the effect of strain, temperature and strain rate on flow stress, dynamic recrystallization (DRX) type softening characteristics of the stress-strain curve with single peak were identified. The flow stress level decreases with increasing temperature and decreasing strain rate. By regression analysis for Arrhenius type equation, the hot deformation activation energy Q and material constants (n, α, β and A) were calculated. Further, the Arrhenius-type constitutive equation of flow stress was developed by considering the effect of strain on the variable coefficients (including activation energy Q, material constants n, α, and A). The validity of the developed constitutive equation incorporating the influence of strain was evaluated through comparing the experimental and predicted data. Furthermore, the predictability of the developed model was also evaluated using two standard statistical parameters, correlation coefficient (R) and average absolute relative error (AARE). And R-value and AARE-value for the model are 0.997 and 4.06% respectively, which indicates that the developed model can precisely estimate the flow behavior for BR1500HS alloy throughout the entire temperature and strain rate range.

Steviol glycosides, a natural sweetener, may perform bioactivities via steviol, their main metabolite in human digestion. The metabolising kinetics, i.e. glucuronidation kinetics and interaction between steviol glycosides or their metabolites and metabolising enzyme, are important for understanding the bioactivity and cytotoxicity. The present study investigated kinetics of steviol glucuronidation in human liver microsome and a recombinant human UDP-glucuronosyltransferases isomer, UGT2B7, along with molecular docking to analyse interaction between UGT2B7 and steviol or glucose. The active pocket of UGT2B7 is consisted of Arg352, Leu347, Lys343, Phe339, Tyr354, Lys355 and Leu353. The influence of stevioside, rebaudioside A, glucose and some chemotherapy reagents on the glucuronidation was also studied. The predicted hepatic clearence suggested that steviol could be classified as high-clearence drug. The steviol glycosides did not affect the glucuronidation of steviol notably. [ABSTRACT FROM AUTHOR]

From June, 2007 to October, 2009, a measurement with static chamber/gas chromatograph techniques was conducted on the soil CH4 flux in a typical secondary hardwood forest in Northeast China under the effects of different harvest disturbances, i. e. , uncut (control), clear cutting (including both farming and reforestation after clear cutting), 50% stand volume removed, and 25% stand volume removed. In all of the four treatments, the soil was the sink of atmospheric CH4, but cutting decreased the soil CH4 uptake flux, with the order of uncut (-85. 03 μg CH4•m-2 •h-1 ) > 50% stand volume removed (-80. 31 μg CH4 •m-2 •h-1 ) > 25% stand volume removed (-70. 97 μg CH4 •m-2h-1) > farming after clear cutting (-65. 57 μg CH4•m-2•h-1) > reforestation after clear cutting (-62. 02 μg CH4•m-2•h-1). During the study period, the seasonal patterns of the soil CH4 uptake flux in all treatments were similar, with a higher value in growth season and a lower one in winter. After the harvest disturbance, the soil temperature, humidity, and NO3 --N, and NH4 +-N contents were all increased, and the soil CH4 flux had a significant quadratic correlation with soil temperature, and a negative linear correlation with soil moisture content. It was suggested that the increase of the soil moisture, NO3 --N, and NH4 +-N contents after the forest harvest was the main cause of the decrease of the soil CH4 uptake flux. [ABSTRACT FROM AUTHOR]

The construction of quaternary carbon centers via C-C coupling protocols remains challenging. The coupling of tertiary C(sp 3 ) with secondary or tertiary C(sp 3 ) counterparts has been hindered by pronounced steric clashes and many side reactions. Herein, we have successfully developed a type of bisphosphine ligand iron complex-catalyzed coupling reactions of tertiary alkyl halides with secondary alkyl zinc reagents and efficiently realized the coupling reaction between tertiary C(sp 3 ) and secondary C(sp 3 ) with high selectivity for the initial instance, which provided an efficient method for the construction of quaternary carbon centers with high steric hindrance. The combination of an iron catalyst and directing group of the substrate makes the great challenging transformation possible.