钨酸钠溶液Na2S除钼工艺的改进

研究了对钨酸钠体系采用三硫化钼沉淀法除钼的工艺,以及硫化、调酸过程对除钼的影响,改进了除钼方法.结果表明,该改进方法能处理含钼0.1～1.5 g/L的钨酸钠溶液,且具有除钼稳定、快速、钨损失较小等优点,所生产的APT可达到APT-0标准.     

Tailoring effect of Y2O3 on water resistance of Na2O-ZnO-Al2O3-B2O3 glasses

To explore the improving effect of Y₂O₃ on the water resistance of xY₂O₃-(100-x)(0.05 Al₂O₃-0.15 ZnO-0.15 Na₂O-0.65 B₂O₃)(x=0,0.7 mol%,1.4 mol%,2.1 mol%,2.8 mol%) glasses,glass structure and ion migration characteristics were respectively characterized by an infrared spectrometer and an electrochemical workstation.X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive Xray spect...     

PbS-Sb2S3-FeS三元系在水蒸气气氛下的铅锑分离

在1073K下通过测定三硫化锑和硫化铅的挥发速度,研究了PbS-Sb_2S_3-FeS三元系在水蒸气气氛下的铅锑分离规律。X-射线衍射结果表明,焙砂由PbS、Fe_3O_4、FePb_4Sb_6S_(14)、Pb_5Sb_4S_(11)和FeSb_2O_4组成。当试样中FeS含量在5％～7％时,铅锑分离效果最好。当试样中FeS的含量≥10％时,铅锑分离效果较差,这时过量的FeS会与Sb_2S_3和PbS形成复杂的硫化物(FePb_4Sb_6S_(14)、Pb_5Sb_4S_(11))或被氧化成F4Sb_2O_4,使锑的挥发变得困难,导致残留在焙砂中的锑含量升高。     

Raman studies of the phase separation mechanism of CaO-Al2O3-SiO2 glasses in an electric field

The effects of an electric field on phase separation in CaO-Al₂O₃-SiO₂ (CAS) has been studied by Raman spectroscopy. It was discovered that an electric field can promote the process of phase separation in CAS glasses. The droplet phase is the enriched section for Ti⁴⁺ and Ca²⁺ ions. The continuous matrix is the enriched section for Si⁴⁺. The results of Raman spectroscopy indicate that the electric-field treatment can increase the concentrations of Q^[2] and Q^[4] in CAS glasses and that increase in concentration near the cathode is higher than that near the anode. The increase in Q^[2] and Q^[4] units is due to the increase of the concentration of O_f and O_b. On the basis of experimental results, the mechanism of phase separation of CAS glass in an electric field has been proposed.     

Na2S2O3碘量法测定铅及铅合金中的铜

采用硝酸溶解试样,加入过量的硫酸沉淀分离Pb2+,用溴水挥发除去砷 锑的干扰,用氟化氢铵掩蔽铁,在弱酸性溶液中,加入KI,Cu2+与I-作用生成CuI沉淀,并析出等当量的碘,以淀粉为指示剂,用Na2S2O3标准溶液滴定法测定Cu2+.该方法对铜含量在1.0％ ～ 10.0％范围内的铅及铅合金中铜含量的测定准确度高,测定结果的相对偏差为0.8％ ～ 2.0％,铜的回收率大于99.70％.     

PbS-Sb2S3二元系在水蒸气气氛下的铅锑分离研究

通过测定锑和铅的挥发率,研究了PbS Sb2S3二元系在水蒸气、空气及氩气气氛下的铅锑分离。X—射线衍射结果表明,在水蒸气气氛中,PbS Sb2S3二元系与水蒸气反应后焙砂主要由PbS组成,同时还含有少量的Sb2O3,铅锑分离效果很好。在氩气气氛中,熔体中的PbS和Sb2S3单纯依靠各自的蒸气压的差别,铅锑分离不彻底。在空气气氛中,熔体中会形成一些复杂的铅锑氧化合物,抑制了锑的挥发,铅锑分离的效果很差。水蒸气能把Sb2S3氧化成Sb2O3而PbS不被氧化是铅锑分离的关键。     

Role of the S3 stalk segment in the thapsigargin concentration dependence of sarco-endoplasmic reticulum Ca2+ ATPase inhibition

The sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) is specifically inhibited by thapsigargin (TG), whereas the Na+,K+-ATPase is not. Large chimeric exchanges between Ca2+ and Na+,K+-ATPases (Norregaard, A., Vilsen, B., and Andersen, J. P. (1994) J. Biol. Chem. 269, 26598-26601), as well as photolabeling with a TG azido derivative (Hua, S., and Inesi, G. (1997) Biochemistry 36, 11865-11872), suggest that the S3-M3 (stalk and membrane-bound) region of the Ca2+ ATPase is involved in TG binding. We produced small site-directed changes in the S3 stalk segment of the Ca2+ ATPase and found that mutation of five amino acids to the corresponding Na+,K+-ATPase residues increases by 3 orders of magnitude the TG concentration required for inhibition of Ca2+ ATPase and coupled Ca2+ transport. A single mutation in the S3 stalk segment (Gly257 --> Ile) is sufficient to increase by 1 order of magnitude the TG concentration required to produce 50% inhibition. By comparison, mutations yielding a nine-amino acid homology in the M3 transmembrane segment, or a 25-amino acid homology in the S4 stalk segment, do not affect the ATPase sensitivity to TG. We suggest that specific binding of TG to the S3 stalk segment, in addition to stacking of the TG ring structure at the membrane interface, determines the high affinity of the ATPase for the inhibitor.     

Discussion of “thermodynamic activity of Na2O in Na2O-CaO-SiO2, Na2O-MgO-SiO2, and Na2O-CaO-SiO2-Al2O3 melts at 1400 ‡C≓

D.N. REGO, G.K. SIGWORTH, and W.O. PHILBROOK: Metall. Trans. B, 1988, vol. 19B, pp. 655-61.