Discusses the effects of welding flux,sand mould,single-use crucible and additional process on the welding joint quality.It is pointed out that the composition,temperature and purity of thermit steel liquid,feeding capacity of sand mould,the kind of gating system and the structure of self-fluxing are the basic factors which affect the quality of the thermit welding.Heat treatment and pressure thermit weld can significantly increased the mechanical properties of welding.According to the quality defects,the paper puts forward some effective way of solving these problems.
Rhubarb is a common herb used in traditional Chinese medicine. However, few publications exist about its pharmacokinetic profiles in animals or healthy volunteers. Whether retention enema administration of rhubarb extract affects its pharmacokinetics as well as its tolerability is unknown. Therefore, we set out to compare the pharmacokinetic parameters of rhein administered by retention enemas with those of conventional oral dosing of rhubarb extract. Eight healthy male volunteers were enrolled in a prospective crossover study. All subjects received a single dose of rhubarb extract (50 mg·kg -1 ) on two separate occasions, once orally, once by a retention enema. Rhein plasma concentration was measured by HPLC. The C max , AUC 0-∞ , AUMC were significantly higher in oral administration than those in retention enema administration ( p < 0.05), while V d of rhein after oral administration of rhubarb extract was significantly lower ( p < 0.05) than that after retention enema administration. However, no statistically significant differences between the two treatments were observed for any of the other pharmacokinetic parameters ( T max , t 1/2 , MRT 0-∞ , CL ). Dosage adjustment is advisable for retention enema administration of rhubarb extract in patients.
This study has mainly focused on ecological issues of Section Heterobalanus, which contains about nine sclerophyllous alpine species and occurs mainly in the China Mountains. To investigate the population history and demography of an endemic oak species (Quercus aquigolioides, Fagaceae) from the Himalaya-Hengduan Mountains region, and elucidate how the unique climatic conditions and heterogeneous topography resulted the uplift of the QTP shaped the genetic diversity and evolutionary history of the species.We sequenced and analyzed a total 1406 base pairs from chloroplast DNA (cpDNA) trnT-L sequences for 296 individuals from 19 populations across the species’ geographic range. Based on these data, we constructed the genealogical relationships and coalescent analysis was used to test demographic hypotheses. 38 haplotypes were identified based on cpDNA variation, and of overall 38 haplotypes, 33 hyplotypes are restricted to single population. High levels of haplotype diversity (Hd=0.948) and low levels of nucleotide diversity (π=0.1976) were detected within the whole species, and a great amount of variation occurred among populations within groups (57.3%). The phylogenetic result demonstrated that Q. aquifolioides cpDNA hyplotypes have three main genetic lineages with distinct distribution. And these genetic lineages resulted by two main bottlenecks in the species took place at 9.37Ma and 8.41Ma, and they have undergone several genetic bottlenecks for a time span of ca. 9 million years. Significant interpopulation differentiation and phylogeopgraphic structure were also detected (GST=0.629, NST= 0.946, NST>GST, P<0.01), and the mismatch distribution analyses indicated a demographic equilibrium for Q. aquifolioides. But as a result of its complex topography, the overall network gave no clear indication regarding demographic process. Together with fossil evidence, the results strongly suggested that multiple microrefugia of Q. aquifolioides existing and the microrefugia were scattered throughout the present geographical range before the Last Glacial Maximum (LGM). Although this species seems to have post-glacial expansion, Q. aquifolioides did not undergo marked changes in population sizes from the late Miocene. And the uplift of the QTP contributed to the phylogeny of cpDNA hyplotypes and differentiation among the population by heterogeneous topographies and climatic change formed the uplift. The two main genetic bottlenecks at ca. 9Ma could contribute to the uplift of eastern and southern QTP at 13-8Ma and strengthen of Asian Summer monsoon at same time causing by the uplift. And several genetic differentiations at ca. 3Ma could confirm with the uplift of the QTP since 3.6Ma. It was reasonable to conclude that the Mio-Pliocene growth of the QTP and the accompanied climatic changes could account for the modern pattern of Q. aquifolioides phylogenetic structure in the HHMs region: first, the center and northern QTP drought and the different evaluation in south and east margin at 13-8Ma made the three main different lineages (NW group and other all). Then the asynchronous and heterogeneous uplifting of QTP in different regions during 9-0.7 Ma resulted to the difference time of the bottleneck in the different lineages. These findings have wide implications for understanding plant species’ responses to the uplift of QTP and climatic change with it.
To study the pharmacokinetics of rhein in 12 healthy volunteers after oral administration of rhubarb extract.The blood sample were obtained at 0,0.083,0.5,1,1.5,2,3,4,5,7,10 h after a single dose oral administration of rhubarb (50 mg x kg(-1)). The plasma rhein concentration was determined by HPLC. The pharmacokinetics of rhein were analysed by 3P97 program.The absorption of rhein was very fastafter oral administration of rhubarb extract in the healthy volunteers. The main pharmacokinetic parameters of rhein were C(max) (3.20 +/- 1.08) microg x mL(-1); t(max) (1.03 +/- 0.41) h; t(1/2alpha) (0.21 +/- 0.02) h; t(1/2beta) (2.68 +/- 1.09) h; MRT(5.31 +/- 1.78) h; AUC(0-infinity) (1 573.08 +/- 366.48) microg x mL(-1) min(-1), respectively.Rhein could be absorbed rapidly and its pharmacokinetics was consistent with two-compartment model.
Objective To study the content difference of aole-emodin between rhubarb decoctions with different drug processing methods.It will provide scientific evidence for clinical usage of rhubarb.Methods The contents of aole-emodin in rhubarb decoctions were determined by RP-HPLC.Results and Conclusion The content of aole-emodin were the highest in crude rhubarb decoction.Drug processing methods have significant effect on the contents of aole-emodin in rhubarb decoctions.This could explain drug processing methods in Chinese traditional medicine with both scientific merits and intrinsic reasoning.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
