Hydrodynamic Instability Analysis of the Axial Flow Pump in an Ethylene Polymerization Loop Reactor

The hydrodynamic instability of the axial flow pump in a loop reactor has long been a troubling issue to be solved in the polyethylene industry due to the lack of a better mechanismic understanding.Generally,the instability of an axial flow pump can be reflected by the fluctuation of the pump head.In this study,the transient computational fluid dynamics(CFD)simulation is adopted to study the hydrodynamic instability of the axial flow pump used in an ethylene polymerization loop reactor.The resul...     

Genome-Wide Association Study Identifies a Rice Panicle Blast Resistance Gene,Pb2, Encoding NLR Protein

Rice blast is one of the main diseases in rice and can occur in different rice growth stages. Due to the complicated procedure of panicle blast identification and instability of panicle blast infection influenced by the environment, most cloned rice resistance genes are associated with leaf blast. In this study, a rice panicle blast resistance gene, Pb2, was identified by genome-wide association mapping based on the panicle blast resistance phenotypes of 230 Rice Diversity Panel 1 (RDP1) accessions with 700,000 single-nucleotide polymorphism (SNP) markers. A genome-wide association study identified 18 panicle blast resistance loci (PBRL) within two years, including 9 reported loci and 2 repeated loci (PBRL2 and PBRL13, PBRL10 and PBRL18). Among them, the repeated locus (PBRL10 and PBRL18) was located in chromosome 11. By haplotype and expression analysis, one of the Nucleotide-binding domain and Leucine-rich Repeat (NLR) Pb2 genes was highly conserved in multiple resistant rice cultivars, and its expression was significantly upregulated after rice blast infection. Pb2 encodes a typical NBS-LRR protein with NB-ARC domain and LRR domain. Compared with wild type plants, the transgenic rice of Pb2 showed enhanced resistance to panicle and leaf blast with reduced lesion number. Subcellular localization of Pb2 showed that it is located on plasma membrane, and GUS tissue-staining observation found that Pb2 is highly expressed in grains, leaf tips and stem nodes. The Pb2 transgenic plants showed no difference in agronomic traits with wild type plants. It indicated that Pb2 could be useful for breeding of rice blast resistance.     

超声纵波换能器用于平测时的测距修正方法研究

研究了超声纵波换能器用于平测时的测距修正方法.首先,根据弹性波理论分析了利用平测布置代替对测布置测量波速时的实际物理意义;然后,分析了两种换能器布置方式的真实传播距离并通过设计混凝土试件切割-测量实验进行了两种布置方式的声时对比;最后,根据实验数据在对测回归直线方程的基础上提出了计算换能器平测布置修正测距的最小二乘法....     

约束型热等离子射流选择性制备单壁和套杯状多壁碳纳米管

以甲烷为碳源,Fe2O3为催化剂,常压下利用配有扰流器件(石墨碗)的约束型热等离子射流高温裂解甲烷,通过原位催化制得两类碳纳米管。运用SEM、TEM、TGA等对不同取样位置产物进行形貌和结构的表征。结果表明:在不同取样部位可获得不同形貌结构的碳纳米管。过滤管外壁处产物为单壁管,石墨碗内产物为套杯状多壁管。气体流动状态影响碳纳米管的形貌,经历层流的前驱物成为高度结晶单壁管,而经历湍流的前驱物则演变成套杯状多壁管。石墨碗腔内的局部高温可使多壁管不断增粗,有利于制备高纯度的碳纳米管。     

Studied on a novel human keratinocyte membrane delivery system in vitro

The culture of keratinocytes on flexible membranes has been proposed as a means to simplify, accelerate and improve the efficiency with which proliferating cells are delivered to full thickness or non-healing skin defects. The purpose of this article was to study the ability of chitosan-gelatin manbranes to facilitate the growth of human keratinocytes. The membranes with different chitosan contents were studied. The surface properties of chitosan-gelatin membranes were investigate by SEM, and water contact angle test. The mechanical property of the membranes was tested. Data implied that gelatin could make the membranes more flexible and hydrophilic than chitosan membranes, which may regulate the seeded cells behavior. Loading human keratinocytes on chitosan-gelatin membranes, cells attachment, spread, and growth were investigated by light microscopy, SEM, and MTT test. The results suggested that the adhesion and proliferation of keratinocytes seeded on chitosan-gelatin membranes were same as on tissue culture plate, in which gelatin could modify the interaction between keratinocytes and chitosan membranes. Therefore, chitosan-gelatin membrane is a good candidate for keratinocytes delivery system.     

中厚板矫直过程中中性层偏移动态研究

研究中性层偏移对矫直力的影响,以提高矫直力精度。通过对矫直件三维弹塑性变形进行分析,提出中性层偏移理论,利用数值模拟和实验讨论中性层偏移的动态变化规律,说明中性层偏移是影响矫直力精度的重要因素之一,并验证了理论推导公式与数值计算结果之间的误差,为建立更为准确的矫直力模型提供理论基础和数据。     

Large-scale fabrication of bioinspired fibers for directional water collection

Spider-silk inspired functional fibers with periodic spindle-knots and the ability to collect water in a directional manner are fabricated on a large scale using a fluid coating method. The fabrication process is investigated in detail, considering factors like the fiber-drawing velocity, solution viscosity, and surface tension. These bioinspired fibers are inexpensive and durable, which makes it possible to collect water from fog in a similar manner to a spider's web.     

Piezoelectric and dielectric properties of PZN-BT-PZT solid solutions

Pb(Zn_1/3Nb_2/3)O₃ ceramics with the perovskite structure can be stabilized by substituting 6–7 mol % BaTiO₃ (BT). Piezoelectric and dielectric properties of the pseudo-binary system (1–x)(0.94PZN-0.06BT) -xPb(Zr_(1–y)Ti_y)O₃ were studied, and the effects of Zr/Ti ratios and thermal annealing process on the piezoelectric and dielectric properties were also discussed. The results show that the piezoelectric properties of this ceramic system are very good when x is about 0.50 and y is about 0.47 with K_p = 70%, d₃₃=560 pC/N, _m #x2248;23,000. These ceramics are favorable to piezoelectric actuators.