再生除铅剂精炼除铅的工业试验

进行了再生除铅剂精炼除铅的工业试验。试验表明，锑火法精炼中再生除铅剂的除铅效果与普通除铅剂基本相同，可替代普通除铅剂使用。     

粗锑火法精炼除铅新方法

本文针对粗锑火法精炼除铅的难题，试图寻求一种经济合理、效果显著的除铅新方法．在研究中发现，有一种ＡＸ物质具有良好的除铅作用，通过小型试验和工业试验，找出了一种粗锑火法精炼除铅的新方法。     

铜精炼阳极炉除铅的生产实践

简述了铜电解精炼过程中高铅阳极的危害，分析了影响铜精炼阳极炉除铅效果的因素，介绍了操作实践.     

废杂铜火法精炼除铅研究

分别将石英砂、磷酸钠和自制除铅剂用于废杂铜火法精炼除铅。采用直读光谱仪和ICP对炉前样品和炉渣进行铅含量检测,研究3种添加剂对铜熔体和炉渣的影响。结果表明,自制除铅剂的除铅效果优于石英砂和磷酸钠,其能够使铜熔体中铅含量降低59%,并且炉渣蓬松含铜低。     

铜精炼阳极炉除铅的生产实践

简述了铜电解精炼过程中高铅阳极的危害,分析了影响铜精炼阳极炉除铅效果的因素,介绍了操作实践.     

粗锡精炼除铅铋方法述评

本文详细介绍了当前国内外粗锡精炼各种除铅、铋方法的基本情况，论述了各种除铅、铋方法的优缺点及我国研制开发的粗锡精炼除铅、铋的新工艺，新设备对世界炼锡工业所作的贡献。     

粗锡精炼除铅铋方法述评

本文详细介绍了当前国内外粗锡精炼各种除铅、铋方法的基本情况，论述了各种除铅、铋方法的优缺点及我国研制开发的粗锡精炼除铅、铋的新工艺，新设备对世界炼锡工业所作的贡献．     

粗锑火法精炼无烟高效除铅剂研究

介绍了粗锑火法精炼用的一种无烟除铅剂,该试剂能够快速脱除粗锑中的铅等杂质,且在反应过程中不产生有害烟雾。文章揭示了无烟除铅剂的除杂原理、无烟机理,探讨了除杂过程中反应时间、温度与除杂效果的关系。     

粗锑火法精炼除铅

小型和工业试验均表明，采用ＡＸ除铅剂，反应时间短，金属直收率高，可将含铅０．５％的高铅锑除至０．２％以下，ＡＸ生产方便，价格低廉，本方法经济效益显著。     

试论粗铅的初精炼除铜

本文介绍了粗铅电解精炼前火法初精炼除铜的三种工艺流程,即熔析法、熔析—加硫及熔析—松香法除铜,并就这三种方法进行了比较。     

Urinary non-precipitable lead in lead workers

Sixty-six workers engaged in lead-glazing pottery with a presumed moderate exposure to lead were studied. The group comprised 20 men with long-term exposure to lead and positive laboratory signs of increased lead absorption (Group A); 22 with long-term exposure and negative laboratory signs (Group B); 11 with short-term exposure and positive laboratory signs (Group C); and 13 with short-term exposure and negative laboratory signs (Group D). In addition, 14 workers employed in casting the kelmet alloys with presumed heavy exposure to lead (Group E) and seven healthy individuals (Group F) were included. Urine samples from all the subjects were analysed to determine, first, the total lead using the ashing technique, and then the precipitable lead using the coprecipitation technique of Cholak, Hubbard, and Burkey (1948), but modified slightly by us. Thus, the non-precipitable lead fraction in urine was the difference between the two measurements and this was also expressed as a percentage of the total lead. The mean total lead and the mean proportion of non-precipitable lead were 0.62 mumol/l and 48.7%, 0.35 mumol/l and 44.9%, 0.40 mumol/l and 48.9%, 0.17 mumol/l and 24.6%, 1.43 mumol/l and 44.3%, 0.14 mumol/l and 18.8% for Groups A, B, C, D, E, and F respectively, showing that a large part of urinary lead was eliminated as precipitable lead in Groups D and F who had normal lead excretion, while about half was eliminated as non-precipitable lead in the other four groups who had excessive lead excretion. No essential difference in the proportion of non-precipitable lead among Groups A, B and C excluded the possibility that the proportion might be directly related to the period of exposure to lead and to the laboratory findings of excessive lead absorption. The mean proportion of non-precipitable lead for the physiological (up to 0.240 mumol/l), intermediate (0.241 to 0.721 mumol/l), and excessive (above 0.722 mumol/l) total lead levels was 26.7, 41.3, and 52.3% respectively, in the lead workers comprising Groups A, B, C, and E each showing increased lead excretion when grouped together. these data suggested that, when urinary lead is within the normal range, it is excreted largely as precipitable lead even in individuals exposed to lead, and that the principal conditions determining the excretion of non-precipitable lead would be the current or recent degree of lead absorption. The excretory mechanisms and the biological significance of the non-precipitable lead are also discussed.     

论铅业的废铅资源

采用废铅指数(S)作为衡量废铅资源状况的指标,简明地分析了铅产量变化、废铅回收状况与S值之间的关系。结果表明,铅产量增长,会造成废铅资源短缺;反之,产量下降,废铅资源将比较充足;产量不变,废铅资源状况介于以上二者之间。废铅实得率愈高,废铅资源愈充足。根据统计数据,估算了1990～2000年间中国、瑞典、美国的S值,讨论了这三个国家S值不同的原因及其今后可能发生的变化。     

Electroextraction of lead from a lead trilonate solution

Laboratory studies of the cathode process of the electroextraction of zinc from the trilonate electrolyte obtained after the purification of solutions after leaching lead cakes of zinc production are performed. The potential scan rate is determined by recording potentiodynamic curves; the optimal electrolyte acidity, the composition, and the temperature are established. Values of activation energy confirming the concentration nature of process polarization are found.     

Plasma and blood lead concentrations, lead absorption, and lead excretion in nonhuman primates

The effects of pH, temperature, block of energy production, calcium/calmodulin, protein phosphorylation, and cytoskeleton-disrupting agents (cytochalasin D, nocodazole) on the integrity of the membrane skeleton were studied in polarized MDCK cells. The intracellular distributions of alpha-fodrin, actin, and ankyrin were monitored by immunofluorescence microscopy. The membrane skeleton, once assembled, seemed to be quite stable; the only factors releasing alpha-fodrin from the lateral walls were the acidification of the cytoplasm and the depletion of extracellular calcium ions. Upon cellular acidification, some actin was also released from its normal location along the lateral walls and was seen in colocalization with alpha-fodrin in the cytoplasm, whereas ankyrin remained associated with the lateral walls. No accumulation of plasma membrane lipids was observed in the cytoplasm of acidified cells, as visualized by TMA-DPH. These results suggest that the linkages between the fodrin-actin complex and its membrane association sites are broken upon acidification. The pH-induced change in alpha-fodrin localization was reversible upon restoring the normal pH. Reassembly of the membrane skeleton, however, required temperatures above +20 degrees C, normal energy production, proper cell-cell contacts, and polymerized actin. Release of alpha-fodrin from the lateral walls to the cytoplasm was also observed upon depletion of extracellular calcium ions. This change was accompanied by the disruption of cell-cell contacts, supporting the role of proper cell-cell contacts in the maintenance of the membrane skeleton polarity. These results suggest that local alterations of the cytoplasmic pH and calcium ion concentration may be important in regulating the integrity of the membrane skeleton.     

Survey of lead exposure around a closed lead smelter

OBJECTIVE: To test the hypothesis that elevated lead in soil is positively correlated with blood lead (BPb) levels in children in an urban population surrounding a closed lead smelter, a US Environmental Protection Agency Superfund clean-up site was surveyed. METHOD: A total of 827 volunteers including 490 children under 6 years of age participated. A questionnaire was administered. Blood lead was determined as was lead content of samples of house dust, soil, paint, and water of the participants' homes. RESULTS: The arithmetic mean venous BPb in 490 children between 6 and 72 months of age was 6.9 micrograms/dL (0.33 mumol/L) range 0.7 to 40.2 micrograms/dL (0.03 to 1.94 mumol/L). The BPb of 78 (16%) children in this group was > or = 10 micrograms/dL (0.48 mumol/L). Based on multiple regression modeling, lead in house dust accounted for 18% of the variance in BPb. Lead in paint together with the condition of the house were the main contributors to the dust lead variance (26%) with soil lead accounting for an additional 6%. Lead in paint alone accounted for 3% of the BPb variance. Lead in paint together with the condition of the house accounted for 12% of BPb variance, and lead in soil accounted for an additional 3%. Factors other than environmental lead such as education of parents, household income, and behavior were associated with BPb levels. CONCLUSIONS: The mean BPb in children was below the present level of concern of the Centers for Disease Control and Prevention. Children with BPb of > or = 10 micrograms/L (0.48 mumol/L) tended to live in poorly maintained older houses. Based on these findings lead in soil and paint in well-maintained homes contributed little to the lead exposure of children.     

Changes in pacing lead impedance over time predict lead failure

It has been suggested that a decrease in lead impedance may predict pacing lead failure, but there is limited prospective data about the relation of changes in lead impedance over time to lead performance. We monitored changes in lead impedance through implantable pulse generators with real-time telemetry data capability in 105 patients with Medtronic 4012 leads (n = 38) and Medtronic 4004 leads (n = 67). Pacing lead failure was documented by serial ambulatory electrocardiographic monitoring or intensified pacemaker clinic surveillance. A significant decrease in lead impedance was observed in patients with Medtronic 4012 and Medtronic 4004 leads with documented lead failure, whereas lead impedance remained stable over time in patients without documented lead failure. The sensitivity and specificity of a lead impedance decrease of > or =15% to predict lead failure were 69% and 70%, respectively. The sensitivity and specificity of a lead impedance decrease of > or =30% to predict lead failure were 36% and 90%, respectively. The positive and negative predictive values for a lead impedance decrease of > or =15% were 54% and 81%, respectively, and for a lead impedance decrease of > or = 30% were 65% and 73%, respectively. Thus, small decreases in lead impedance may identify failing leads. Serial measurement of pacing lead impedance over time is a useful tool to monitor pacing lead performance.     

Reduction of lead in the lead sulfide-molten sodium hydroxide system

Based on thermodynamic investigations of the reduction of lead from its sulfide compounds using the electron-donating properties of sulfur of its sulfide, we studied the effect of various factors on the reduction of lead (“metallization”) in molten sodium hydroxide. In the range of temperatures of smelting PbS with the alkali (470–510°C), there occurs a “burst” metallization reaching 95% at T = 550°C; at T = 650°C, the process is completed in 15 min; at 650–500°C, the reduction of the metal occurs in the diffusion region. The NaOH: PbS weight ratio (α) exerts a direct effect on the yield of the compact metal (‘lens’). At α = 1.8?0.8, the yield of the compact metal is 96–98%. It has been confirmed experimentally that the chemism of the utilization of elementary sulfur is related to a disproportionation of the latter with the accumulation of S^2? and SO ₄ ^2? ions and the possible formation of polysulfide sulfur S _n ^2? .