采用高电流密度生产优质电积铜

塞洛维德（Cerro Verde）于1977年4月投产。原电积车间设计能力为年产阴极铜33000t，采用184A／m^2的电流密度，电流效率为84.5％。1994年该矿山并着手进行扩产，以增加产能至年产阴极铜48000t，采用250A／m^2的电流密度，电流效率为90％。到1997年，通过工艺的革新优化，并提高电流密度，使阴极铜的产量超过了该设计能力。2002年继续通过提高电流密度增加产量，电流密度达到370A／m^2。本文围绕着如何通过改进电解液的流量、成分和温度、电极几何尺寸、电解槽、添加剂、电解周期及操作实践以实现在提高阴极铜质量的同时达到较高生产能力进行讨论。     

采用高电流密度生产优质电积铜

塞洛维德(Cerro Verde)于1977年4月投产。原电积车间设计能力为年产阴极铜33 000 t,采用184 A/m2的电流密度,电流效率为84.5%。1994年该矿山并着手进行扩产,以增加产能至年产阴极铜48 000 t,采用250 A/m2的电流密度,电流效率为90%。到1997年,通过工艺的革新优化,并提高电流密度,使阴极铜的产量超过了该设计能力。2002年继续通过提高电流密度增加产量,电流密度达到370 A/m2。本文围绕着如何通过改进电解液的流量、成分和温度、电极几何尺寸、电解槽、添加剂、电解周期及操作实践以实现在提高阴极铜质量的同时达到较高生产能力进行讨论。     

Astrocytes regulate amino acid receptor current densities in embryonic rat hippocampal neurons

Embryonic rat hippocampal neurons were cultured in a serum-free defined medium (MEM/N3) either directly on poly-D-lysine (PDL) or on a confluent monolayer of postnatal cortical astrocytes, C6 glioma cells, or Rat2 fibroblasts. Neurons on PDL were grown in MEM/N3 or in MEM/N3 conditioned for 24 h by astrocytes or C6 cells. Membrane capacitance (Cm) and gamma-aminobutyric acid (GABA)-, glycine-, kainate-, and N-methyl-D-aspartate (NMDA)-induced currents were quantified using whole-cell patch-clamp recordings. Cm as well as the amplitude and the density of these currents in neurons cultured on astrocytes were significantly greater than those in neurons grown on PDL after 24 and 48 h. C6 cells mimicked astrocytes in promoting Cm and GABA-, glycine-, and NMDA-evoked, but not kainate-evoked, currents. Cm and currents in neurons grown on Rat2 cells were comparable to those in neurons on PDL. Astrocytes maintained in culture for 3 months were noticeably less effective than freshly prepared ones just grown to confluence. Suppression of spontaneous cytoplasmic Ca2+ (Ca[c]2+) elevations in astrocytes by 1,2-bis(2-aminophenoxy) ehane-N, N, N, N-tetraacetic acid acetoxymethyl ester (BAPTA-AM) loaded intracellularly blocked the observed modulatory effects. Medium conditioned by either astrocytes or C6 cells mimicked the effects of direct coculture of neurons on these cells in promoting Cm and amino acid-evoked currents. Inclusion of antagonists at GABA and glutamate receptors in coculture experiments blocked the observed effects. Thus, diffusible substances synthesized and/ or secreted by astrocytes in a Ca(c)2+-dependent manner can regulate neuronal growth and aminoacid receptor function, and these effects may involve neuronal GABA and glutamate receptors.