铅黄铜水平连铸棒材熔铸工艺的试验研究

在工业生产条件下，对影响HPb59－1水平连铸律材热轧开裂的熔铸工艺进行了试验研究．取三个熔铸工艺因素：铸造速度、冷却水压力、冷却水温度．试验结果表明；铸造速度对热轧开裂影响极为显著，使其控制在410mm／min左右可获得较为理想的效果．     

Two mechanisms for the recapture of extracellular GM2 activator protein: evidence for a major secretory form of the protein

The GM2 activator protein is a small monomeric protein containing a single site for Asn-linked glycosylation. Its only proven in vivo function is to act as a substrate specific cofactor for the hydrolysis of GM2 ganglioside by lysosomal beta-hexosaminidase A. However, we and others have shown it can act as a general glycolipid transporter at neutral pH in vitro. Any other possible in vivo functions would require that some of the newly synthesized activator molecules not be targeted to the lysosome. The lysosomal targeting mechanism for the activator has not been conclusively identified. While earlier reports suggested that it is likely through the mannose-6-phosphate receptor, another more recent report demonstrated that deficient human cells could recapture nonglycosylated, bacterially produced activator, suggesting its use of an alternate targeting pathway. Here, we demonstrate that the mannose-6-phosphate pathway is likely the major intracellular, biosynthetic route to the lysosome, as well as a high affinity recapture pathway for the endocytosis of activator protein from extracellular fluids. Additionally, we show that there exists a second lower affinity recapture pathway that requires its native protein structure, is carbohydrate independent, and likely does not involve its ability to bind glycosphingolipids in the plasma membrane. Finally, we document that the pool of newly synthesized precursor activator protein contains a majority of molecules with a complex-type oligosaccharide, which cannot contain a functional mannose-6-phosphate targeting signal. These molecules makeup the secreted forms of the protein in normal human fibroblasts.     

Accurate estimation of environment parameters from ultrasonic data

This paper describes a robust and accurate ultrasonic sensing system for a mobile robot. The system continuously updates a local map of the environment in which obstacles are represented by straight lines or points in a robot centered coordinate frame. The presented algorithms use a Kalman filter for the reduction of the noise in the ultrasonic data and use a systematical error correction (‘bundle correction’) to reduce the uncertainty in obstacle direction. Experiments are carried out in simulation and with a real mobile robot system. Results show that the accuracy with which line parameters can be estimated is in the order of 1 degree for the orientation and about 2 cm for the position. The effect of the bundle correction is significant and maximal when the robot approaches walls under a small angle.     

TiO_2载体表面酸性的研究

利用NH_3吸附和吡啶吸附红外技术研究TiO_2的制备条件对其表面酸性的影响。结果表明,用NH_3水中和TiCl_4溶液方法制备的TiO_2(A)表面有较强的L酸中心,中和条件对表面酸性中心数目和强度有显著影响。由TiOSO_4水解方法制备的TiO_2(B)表面具有较强的L酸中心和较弱的B酸中心,引入不同添加剂可有效地调变TiO_2载体表面的酸性。     

Independent modulation of horse airway smooth muscle by epithelium and prostanoids

The effects of epithelial removal and cyclooxygenase inhibition on contractions induced by exogenous acetylcholine (ACh) and electrical field stimulation (EFS) were evaluated in horse tracheal strips and bronchial rings. Epithelial removal potentiated the response to ACh but had no influence on the response to EFS. The effect of epithelial removal was not altered by pretreating the tissues with meclofenamate, a cyclooxygenase inhibitor. In trachealis strips, meclofenamate augmented contractions induced by EFS but not by ACh. In bronchial rings, meclofenamate augmented EFS-induced contraction to a greater extent than ACh-induced contraction. These effects of meclofenamate were epithelium-independent. We conclude that horse airway epithelium produces a relaxant factor that is not a prostanoid. Endogenous prostanoids originating from non-epithelial sites inhibit only cholinergic nerves in the trachea but both parasympathetic nerves and smooth muscle in the bronchi.     

The effects of retinol on in vitro immunoglobulin synthesis by cord blood and adult peripheral blood mononuclear cells

In this study we examined the effects of retinol (ROH), a metabolic precursor of retinoic acid (RA), on Staphylococcus aureus Cowan I (SAC)-induced immunoglobulin synthesis of cord blood mononuclear cells (CBMC) and adult peripheral blood mononuclear cells (PBMC). ROH augmented SAC-induced IgM synthesis of CBMC by 5.9 +/- 1.5-fold (n = 7, mean +/- s.d.), and IgG synthesis of adult PBMC by 16.3 +/- 5.1-fold (n = 3) at optimal concentrations of 10(-6) M and 10(-11) M, respectively. No augmenting effects could be demonstrated for the other immunoglobulin isotypes. Time-course studies showed that the synthesis of IgM by CBMC was accelerated with detectable immunoglobulin in supernatant fluids starting on day 3. ROH augmented immunoglobulin synthesis of CBMC stimulated by Epstein-Barr virus (EBV), a T cell-independent polyclonal activator, and of EBV-transformed B cell clones (2.5 +/- 0.2 and 4.1 +/- 1.5-fold increase, respectively), which suggests that ROH can act directly on B cells to enhance immunoglobulin synthesis. In contrast, when ROH was preincubated with cord blood T cells, washed and added to the B cell-enriched fraction with SAC, no increase (0.9-1.8-fold) in IgM synthesis was obtained. Thus, the principal mechanism(s) by which ROH augments immunoglobulin synthesis is by acting on B cells. This is in contrast to the immunoglobulin-enhancing effects of RA which is mediated by T cells, or T cell products, e.g. cytokine. Our studies suggest that RA and ROH may have different pathways of immunoglobulin-enhancing effects, perhaps mediated by different retinoid binding proteins resulting in gene activation and immunoglobulin synthesis.     

含淀粉聚乙烯膜的时控光降解研究

使用复合光降解剂，得到了可光降解的生物降解膜。对膜的光降解进行了考察，并对影响光降解的因素进行了讨论，结果表明，我们所制得的膜是一种较好的时控光降解膜。     

Hierarchical intelligent control with flexible AC transmission systems application

A novel hierarchical intelligent controller configuration is proposed using an artificial neural network as a control-mode classifier in the supervisory level and a set of pre-designed controllers in the lower level. Controller outputs are modified nonlinearly by the classifying signals in a structure resembling one artificial neuron with adaptively changed weights. The lower-level local controllers are implemented using neural networks. An illustrative example of this approach is based on the transient stabilization of a single-machine infinite-bus system studied in Flexible AC Transmission Systems (FACTS) research.