幽门螺杆菌感染与胃肠道微生态的关系

幽门螺杆菌(Helicobacter pylori,H.pylori)是人体中普遍存在的一种细菌,全球自然人群的感染率超过50%.在未提供适当治疗的情况下,H.pylori将持续存在.H.pylori感染导致胃肠道菌群发生改变,并与胃肠及胃肠外多种疾病相关.近年来,肠道微生态成为研究热点,H.pylori感染与肠道微生态的关系逐渐引起人们的关注.H.pylori根除疗法会导致肠道菌群短期改变,其长期影响尚不明确.益生菌的使用可能会为H.pylori根除疗法带来积极影响.

Deformation Temperature and Lamellar Thickness Dependency of FormⅠto Form Ⅲ Phase Transition in Syndiotactic Polypropylene during Tensile Stretching

Phase transition from form Ⅰ to form Ⅲ in syndiotactic polypropylene crystallized at different conditions during tensile deformation at different temperatures was investigated by using in situ synchrotron wide angle X-ray diffraction technique. In all cases, the occurrence of this phase transition was observed. The onset strain of this transition was found to be crystalline thickness decided by crystallization temperature and drawing temperature dependent. The effect of drawing temperature on this phase transition is understood by the changes in mechanical properties with temperature. Moreover, crystalline thickness dependency of the phase transition reveals that this form Ⅰ to from Ⅲ phase transition occurs first in those lamellae with their normal along the stretching direction which have not experienced stress induced melting and recrystallization.

Rhodium catalyzed asymmetric synthesis of Chiraphos derivatives

Herein,we report a highly efficient versatile synthetic route to Chiraphos derivatives through Rh/Ph-bod catalyzed asymmetric addition of aryl boronic acids to phosphinyl dienes.Various substituted phosphinyl dienes,both on the parent skeleton and the phosphine atoms,were well tolerated with this method and provided chiral phosphine oxides in satisfied yield and up to 95%ee.The corresponding Chiraphos derivative displayed an advantage over Chiraphos in the representative Pd-catalyzed asymmetric 1,4-addition reaction.

Advantage of Preserving Bi-orientation Structure of Isotactic Polypropylene through Die Drawing

The isotactic polypropylene(iPP) usually shows a unique parent-daughter lamellae structure in which the parent and daughter lamellae are against each other with a near perpendicular angle(80° or 100°). Inducing a high fraction of oriented cross-hatched structure in iPP during processing is desirable for designing the bi-oriented iPP products. We processed a commercial iPP via tensile-stretching and die-drawing to evaluate the structural evolution of oriented parent-daughter lamellae. It turned out that the die-drawing process had an advantage in attaining a high fraction of oriented cross-hatched structure of iPP, as compared to the free tensile stretching. Besides, the presence of α-nucleating agents affected the formation of oriented parent-daughter lamellae in the die-drawn samples whereas such influence diminished in the free stretched ones. It was found that the confined deformation inside the die led to the well-preserved oriented cross-hatched structure in the die-drawn iPP.

Laboratory simulation and CO_(2) flooding efficiency of oil-water transition zones in a low permeability reservoir in the Jilin Oilfield

Geological reserves of oil-water transition zone(OWTZ)in low-permeability reservoirs have been considered as uneconomical resources because of high water cut and low abundance.Though the OWTZ may account for 30%-50%of a reservoir,it has not been paid more attentions yet.The average oil saturation of the OWTZ is about 35%,which is equal to that of a reservoir after water flooding.Currently,CO_(2) flooding is an effective technique for residual oil recovery after water flooding,which could reduce the residual oil saturation greatly.Therefore,it is of significance for the EOR of the low-permeability reservoir if the CO_(2) flooding could be successfully applied in the OWTZ.In this study,a method based on a long core to simulate distribution of oil saturation in OWTZs is set up in the laboratory using bidirectional saturation.In order to investigate CO_(2) flooding characteristics in OWTZs,experiments are carried out on 3 sets of initial oil saturation,and the recoverable reserves of the OWTZ and its contribution to the EOR are calculated based on the WJ reservoir in the Jilin Oilfield,China.