电解铝液生产高品质6061铝合金圆铸锭工艺研究与实践

探讨了用电解铝液直接生产高品质6061铝合金圆铸锭工艺技术,主要在熔体处理、炉内精炼、晶粒细化、炉外在线净化、均匀化处理和生产设备等方面采取了相应的技术措施.结果表明,优化后的生产工艺制度能够满足高品质6061铝合金圆铸锭的质量要求,在均匀化过程中适宜的均匀化工艺为560℃×8h.     

Effect of graphite intercalation compounds in the interfacial zone on the mechanical and thermal properties of unidirectional carbon fiber reinforced spodumene composite

The interface in unidirectional carbon-fiber-reinforced β-spodumene matrix composite (UD-Cf/β-spodumene) significantly affected the thermal conductivity characteristics and mechanical properties due to the presence of a multi-layer interface. The mechanical and thermal properties of UD-Cf/β-spodumene composites with and without a multi-layer interface have been studied. The measured thermal conductivities, flexural strength and fracture toughness of composites with a multi-layer interface were much better than those composites with a clear interface. Interfacial layers with a multi-layer morphology originated from the diffusion of lithium from the β-spodumene matrix to the surface of the carbon fiber, which led to the formation of graphite intercalation compounds. The mechanical properties and thermal conductivity of UD-Cf/β-spodumene hot pressed at 1350 and 1400 °C were enhanced due to the textured interfacial microstructure and high thermal conductivity of graphite intercalation compounds. The textured interface decomposed at 1450 °C, resulting in the formation of a “strong” interface. Inevitably, the mechanical properties and thermal conductivity decreased.     

广东省乙烯行业能耗现状及节能对策分析

乙烯是高耗能产业,"十二五"是广东省乙烯工业快速发展时期,将推动广东的能源消耗总量进一步上升。文章分析了广东省乙烯能耗现状,结合"十二五"乙烯工业发展规划,提出了广东乙烯节能的主要途径和对策。     

低游离甲醛脲醛树脂合成工艺研究

脲醛(UF)树脂是一种广泛应用于木材加工业的胶黏剂,文章采用碱-酸-碱合成工艺,探讨了甲醛与尿素的摩尔比、pH、反应温度及尿素加料方式等因素对UF树脂黏度及游离甲醛含量的影响,发展了制备低毒(游离甲醛含量0.13%)UF树脂的新工艺,并用IR对UF树脂进行了确证。     

A Chiral Salen-type Schiff Base Cu<Superscript>2+</Superscript> Complex for the Vinylic-type Polymerization of Norbornene

Abstract  

The chiral Salen-type Schiff base ligand H ₂ L (H ₂ L = (s)-(+)2,2′-bis(2-hydroxy-3-methoxybenzylideneamino)-1,1′-binaphthyl), was selected to obtain the new chiral Cu²⁺ complex CuL (1), which was found to catalyze the polymerization of norbornene (NBE). The complex shows the distinctively distorted geometry from a square-planar reactive center, this feature being suggested to account for the efficient catalysis on the vinylic-type polymerization of NBE, with moderate molecular weights and narrow molecular weight distributions.     

Enhancement of Polyunsaturated Fatty Acid Production by Selenium Treatment in Polyunsaturated Fatty Acid-Producing Fungus

The effect of selenium (Se) treatment on the content of intracellular polyunsaturated fatty acids (PUFA) was investigated. Selenium treatment could effectively increase the yields of arachidonic acid (AA) and linoleic acid (LA). When AA-producing Diasporangium jonesianum recombinant strain D-A1 was cultured in a medium containing 90 μg mL⁻¹ Se, the growth of D. jonesianum recombinant strain D-A1 was constrained, but the content of AA in the total fatty acids reached 9.3%, 1.7-fold higher than the control. The content of LA was also increased from 25.9 to 37.7%. Under various culture conditions, Se treatment (90 μg mL⁻¹) was generally beneficial to the yields of LA and AA. However, there was no significant increase in the contents of eicosapentaenoic acid (EPA) and γ-linolenic acid. Therefore, the use of Se is advantageous for regulating the content of intracellular PUFA in D. jonesianum recombinant strain D-A1, and could be good enhancer in the yields of AA and LA.     

双重密封坐便器的设计原理与特点

双重密封坐便器结构新颖独特,在系统中采用双重密封的方式,达到了既节约用水又保证密封效果的目的。通过详细介绍双重密封坐便器的设计原理与技术特色,并给出装配说明,阐述了其技术创新的意义。     

Structure-property relations of 55 nm particle-toughened epoxy

55-nm rubber particles significantly toughened two epoxy systems without loss of Young’s modulus, tensile strength and glass transition temperature. Transmission Electron Microscopy (TEM) showed that the nanoparticles are uniformly dispersed in matrix and have blurred interface with epoxy. 5 wt% rubber nanoparticles increased the critical strain energy release rate (G_1c) of Jeffamine D230 (J230)-cured epoxy from 175 J/m² to 1710 J/m², while the 10 wt% increased G_1c of diaminodiphenyl sulfone (DDS)-cured epoxy from 73 J/m² to 696 J/m². This is explained by comparing the surface-surface interparticle distance and total particle surface of nanocomposites with those of composites. The higher the matrix stiffness, the more nanoparticles needed for toughening. Although the 10 wt% J230-cured nanocomposite showed a 50% larger size of stress-whitened zone than the 5 wt% J230-cured nanocomposite, the 5 wt% nanocomposite showed a higher toughness. These nanoparticles were found to pose barriers to the vibration of crosslinked matrix molecules, leading to higher glass transition temperatures. While the matrix shear banding caused by nanoparticle expansion and growth is the major toughening mechanism for the J230-cured nanocomposites, the matrix plastic void growth and deformation are most probably the major mechanisms for the DDS-cured system. Under tensile loading, the nanoparticles in the DDS-cured epoxy created fibrils of 100-200 nm in diameter and 3-5 μm in length. TEM analysis in front of a subcritically propagated crack tip showed a number of voids of 30-500 nm in diameter in the vicinity of the crack, implying that rubber nanoparticles expanded, grew and deformed under loading. Unlike conventional epoxy/rubber composites in which all of the rubber particles in the crack front cavitated under loading, only a portion of the nanoparticles in this study expanded to create voids. Huang and Kinloch’s model developed from composites was found not fit well into these nanocomposites.     

Permissive Modulation of Sphingosine-1-Phosphate-Enhanced Intracellular Calcium on BKCa Channel of Chromaffin Cells

Sphingosine-1-phosphate (S1P), is a signaling sphingolipid which acts as a bioactive lipid mediator. We assessed whether S1P had multiplex effects in regulating the large-conductance Ca²⁺-activated K⁺ channel (BK_Ca) in catecholamine-secreting chromaffin cells. Using multiple patch-clamp modes, Ca²⁺ imaging, and computational modeling, we evaluated the effects of S1P on the Ca²⁺-activated K⁺ currents (I_K(Ca)) in bovine adrenal chromaffin cells and in a pheochromocytoma cell line (PC12). In outside-out patches, the open probability of BK_Ca channel was reduced with a mean-closed time increment, but without a conductance change in response to a low-concentration S1P (1 µM). The intracellular Ca²⁺ concentration (Ca_i) was elevated in response to a high-dose (10 µM) but not low-dose of S1P. The single-channel activity of BK_Ca was also enhanced by S1P (10 µM) in the cell-attached recording of chromaffin cells. In the whole-cell voltage-clamp, a low-dose S1P (1 µM) suppressed I_K(Ca), whereas a high-dose S1P (10 µM) produced a biphasic response in the amplitude of I_K(Ca), i.e., an initial decrease followed by a sustained increase. The S1P-induced I_K(Ca) enhancement was abolished by BAPTA. Current-clamp studies showed that S1P (1 µM) increased the action potential (AP) firing. Simulation data revealed that the decreased BK_Ca conductance leads to increased AP firings in a modeling chromaffin cell. Over a similar dosage range, S1P (1 µM) inhibited I_K(Ca) and the permissive role of S1P on the BK_Ca activity was also effectively observed in the PC12 cell system. The S1P-mediated I_K(Ca) stimulation may result from the elevated Ca_i, whereas the inhibition of BK_Ca activity by S1P appears to be direct. By the differentiated tailoring BK_Ca channel function, S1P can modulate stimulus-secretion coupling in chromaffin cells.     

The T Cell Repertoires from Nickel Sensitized Joint Implant Failure Patients

Nickel (Ni²⁺) is one of the most common allergens, affecting around 10–15% of the general population. As the demand for orthopedic implant surgery rises, the number of surgical revisions due to joint implant failure also increases. There is evidence that some patients develop joint failure due to an immune response to a component of the implant, and we have found that Ni²⁺ is an especially important cause. Hence, understanding the mechanisms by which Ni²⁺ allergy induces joint implant failure becomes a critical research question. The structural basis of Ni²⁺ activation of pathogenic T cells is still not clear. The purpose of this study was to characterize Ni²⁺-reactive T cell repertoires derived from the peripheral blood of joint failure patients due to Ni²⁺ sensitization using single-cell sequencing techniques. We stimulated the proliferation of Ni²⁺ -reactive T cells from two implant failure patients in vitro, and sorted them for single-cell VDJ sequencing (10× genomics). We identified 2650 productive V-J spanning pairs. Both TCR α chains and β chains were enriched. TRBV18 usage is the highest in the P7 CD4+ population (18.1%), and TRBV5-1 usage is the highest in the P7 CD8+ population (12.1%). TRBV19 and TRBV20-1 segments are present in a high percentage of both P7 and P9 sequenced T cells. Remarkably, the alpha and beta chain combination of TRAV41-TRBV18 accounts for 13.5% of the CD4+ population of P7 patient. Compared to current Ni specific T cell repertoire studies of contact dermatitis, the Vα and Vβ usages of these joint implant failure patients were different. This could be due to the different availability of self-peptides in these two different tissues. However, TRBV19 (Vβ17) was among frequently used TCR β chains, which are common in previous reports. This implies that some pathogenic T cells could be similar in Ni²⁺ hypersensitivities in skin and joints. The alignment of the TCR CDR3β sequences showed a conserved glutamic acid (Glu) that could potentially interact with Ni²⁺. The study of these Ni²⁺ specific TCRs may shed light on the molecular mechanism of T cell activation by low molecular weight chemical haptens.