Heterogeneous Catalysis in Biodiesel Production: The Influence of Leaching

The catalytic performances of several solid catalysts in the transesterification of vegetable oils with methanol were studied in small steel vials. The eventual presence of an homogeneous contribution to the catalysis—due to the leaching of the active phase—was also investigated. The behaviour of one of the more promising catalyst (TiO₂ supported on SiO₂) was further deepened in batch and continuous reactors by using the catalysts in pellets, to evaluate the possibility of developing an industrial process based on this catalyst. The catalyst life-time run, in a continuous tubular reactor, was determinant for this evaluation.     

Structure-activity relationship study of 16 a-thiocamptothecins: an integrated in vitro and in silico approach

The instability of the hydroxylactone E ring represents a critical drawback of camptothecins, because the lactone ring is recognized to be essential for stabilization of topoisomerase I‐mediated DNA cleavage. In an attempt to investigate the effect of the thiopyridone pharmacophofore on the molecular and pharmacological features of the drug, we prepared a series of novel 16 a‐thiocamptothecin analogues. Due to the sulfur atom, a destabilization of the hydrogen bond between the hydroxy group in position 17 of the opened E ring and the carbonyl of the pyridone moiety is predicted, thus shifting the equilibrium toward the closed lactone form and increasing the lipophilic properties of the compounds. This feature was associated with superior antiproliferative potency, with reduced interaction with the human serum albumin and with substantial increase of the persistence of the topoisomerase I–DNA cleavable complex. These effects were prominent for thio‐SN38, the most active compound of the series. The favorable interactions at the molecular and cellular level of the reported thiocamptothecins confer promising features, and these compounds warrant preclinical development.     

myo-Inositol trispyrophosphate: a novel allosteric effector of hemoglobin with high permeation selectivity across the red blood cell plasma membrane

myo‐Inositol trispyrophosphate (ITPP), a novel membrane‐permeant allosteric effector of hemoglobin (Hb), enhances the regulated oxygen release capacity of red blood cells, thus counteracting the effects of hypoxia in diseases such as cancer and cardiovascular ailments. ITPP‐induced shifting of the oxygen–hemoglobin equilibrium curve in red blood cells (RBCs) was inhibited by DIDS and NAP‐taurine, indicating that band 3 protein, an anion transporter mainly localized on the RBC membrane, allows ITPP entry into RBCs. The maximum intracellular concentration of ITPP, determined by ion chromatography, was 5.5×10^?3 M , whereas a drop in concentration to the limit of detection was observed in NAP‐taurine‐treated RBCs. The dissociation constant of ITPP binding to RBC ghosts was found to be 1.72×10^?5 M . All data obtained indicate that ITPP uptake is mediated by band 3 protein and is thus highly tissue‐selective towards RBCs, a feature of major importance for its potential therapeutic use.     

某硅钙质胶磷矿双反浮选工艺的研究

针对贵州某中低品位硅钙质胶磷矿硅含量较多的特点,采用双反浮选的方法,达到降低硅含量的目的。最终获得了P2O5品位30.84%、回收率85.77%、MgO质量分数1.37%、SiO2质量分数10.26%的磷精矿,实现了胶磷矿与硅质脉石的有效分离。     

低引燃倾向(LIP)卷烟纸热失重和热裂解产物的研究

采用热重分析法研究了低引燃倾向(LIP)卷烟纸的热失重行为。将LIP卷烟纸分别在300,600,900℃的空气环境下进行热裂解,并与对照卷烟纸的裂解产物进行对比。结果表明:①由于阻燃剂吸收部分热量,LIP卷烟纸起始裂解温度向低温方向偏移;②LIP卷烟纸的裂解产物和对照卷烟纸相比,物质和含量不同,但产物种类相同,主要是酮类、酯类、醛类、酸类物质,在LIP卷烟纸中还检测到21种致香成分,明显多于对照卷烟纸的7种,且致香成分的含量随裂解温度的升高而降低。     

表面活性剂在石油化工设备清洗中的应用

简述了表面活性剂的结构特点、性质特征及石化装置中的污垢状况及特征,并列举了表面活性剂在化工设备清洗中的大量工业应用实例,指出了化工设备清洗剂中表面活性剂的应用特点及今后表面活性剂的发展方向。     

Comparison of Microstructure and Residual Stress Between TIG and MAG Welding Using Low Transformation Temperature Welding Filler

A Cr–Ni type of low transformation temperature(LTT) welding filler was devised in the present study. The LTT weld microstructures of the tungsten inert gas(TIG) and metal active gas(MAG) weldings were investigated by using electron-backscattered diffraction and orientation imaging microscopy. The results showed that the LTT weld microstructures prepared by TIG and MAG weldings were primarily martensite with 17.5% and 8.0% retained austenite,respectively. The LTT weld metal using TIG welding had larger grain size than using MAG. In addition, based on the Taylor factor calculation, the weld metal using MAG welding was more competent in repressing fatigue crack initiation.Meanwhile, the high angle and coincidence site lattice grain boundaries were dominant in the LTT weld metal using MAG welding. Moreover, the hardness of the LTT weld metal using MAG welding was higher than that of using TIG. Based on heat input and phase transformation, finite element method was applied to analyzing the tensile residual stress(RS)reduction in welded joints prepared by both conventional and LTT welding fillers, respectively. The corresponding outcome confirmed that the LTT weld metal using MAG welding was more beneficial to tensile RS reduction.     

Influence of Dew Point on the Selective Oxidation,Microstructure and Mechanical Properties of a High-Al Low-Si Dual Phase Steel during Hot-Dip Galvanizing Process

The effect of dew point on the selective oxidation behavior, microstructure and mechanical properties of a high-Al low-Si dual phase steel is elucidated. The results showed that as dew point is increased from–30°C to +5°C, internal oxidation of alloying elements occurs, and consequently the mass of external oxides decreases, which improves the galvanisability of steel sheets. It was also observed that the dew point had an impact on the microstructure and mechanical properties of the experimental steel. With the increase of dew point, the decarburization layer on the surface was increased, leading to inferior mechanical properties. Compared with the industrial steel, the high-Al-low-Si DP steel exhibited excellent galvanisability under identical annealing conditions.

     

Effect of B4C on the Microstructure and Mechanical Properties of As-Cast TiB＋TiC/TC4 Composites

Different additions of B4C were introduced into TC4 to alter the microstructure and mechanical properties.The morphologies of reinforcements are related to the solidification paths.The refinement of lamellar spacing k is based on the precipitation pattern of b-phases.Microhardness,compression elastic modulus(Ec),and elastic modulus of the matrix(Em)appear non-linear relationships with B4C additions.Due to the refinement of lamellar spacing with Hall–Petch-type relationships,and the solution strengthening of C on the a + b matrix,the effect of reinforcements on the mechanical properties will be more efficient when the additions of B4C are no more than 0.19 wt%.When the additions of B4C are more than 0.19 wt%,the efficiency will decrease.