无铅焊膏用助焊剂研制

对助焊剂的活性组分和其他组分采用正交试验进行筛选,根据工业标准对其进行了焊料铺展面积测试,效果较好的活性剂进行复合处理,对配制出的活性剂溶液加入松香配制成助焊剂进行性能测试.结果表明:当有机酸和三乙醇胺的质量比为12:1,占助焊剂质量分数的13.68％时,溶液的pH值达到3.94,扩展率可达80.06％,钎焊后的焊点光...     

铅锌冶炼废渣和尾矿制备地聚合物的研究

以铅锌冶炼废渣、尾矿为主要硅铝原料制备了地聚合物,首先对冶炼废渣和尾矿进行预粉磨,以提高其活性,再与复合激发剂水玻璃和脱硫石膏混合后粉磨,通过压制成型工艺制得地聚合物试样。实验结果表明:当水玻璃掺量为14%,脱硫石膏掺量为8%时,所制得的地聚合物胶凝材料3d、7d和28d龄期抗压强度均最高,分别达到24.67MPa、27.69MPa、32.81MPa。SEM、XRD和FT-IR分析表明:以铅锌冶炼废渣和尾矿制得的地聚合物,其微观结构致密性好,无定形的凝胶与未反应的原料颗粒界面黏结牢固,并有针状钙矾石穿插其中,从而有助于强度的提高。     

两种不同碳链烷基吗啉分子的浮选性能对比及性能优化

烷基吗啉是一种新型氯化钠浮选剂，应用于氯化钾工业化生产中的反浮选工艺，文章根据国内氯化钾生产的实际情况，对两种常见的烷基吗啉浮选药剂的浮选性能进行对比研究。并通过添加活化剂，优化浮选药剂性能，达到降低药剂用量的目的。     

Identification of regulatory elements in the AGT1 promoter of ale and lager strains of brewer's yeast

Agt1 is an interesting α-glucoside transporter for the brewing industry, as it efficiently transports maltotriose, a sugar often remaining partly unused during beer fermentation. It has been shown that on maltose the expression level of AGT1 is much higher in ale strains than in lager strains, and that glucose represses the expression, particularly in the ale strains. In the present study the regulatory elements of the AGT1 promoter of one ale and two lager strains were identified by computational methods. Promoter regions up to 1.9 kbp upstream of the AGT1 gene were sequenced from the three brewer's yeast strains and the laboratory yeast strain CEN.PK-1D. The promoter sequence of the laboratory strain was identical to the AGT1 promoter of strain S288c of the Saccharomyces Genome Database, whereas the promoter sequences of the industrial strains diverged markedly from the S288c strain. The AGT1 promoter regions of the ale and lager strains were for the most part identical to each other, except for one 22 bp deletion and two 94 and 95 bp insertions in the ale strain. Computational analyses of promoter elements revealed that the promoter sequences contained several Mig1- and MAL-activator binding sites, as was expected. However, some of the Mig1 and MAL-activator binding sites were located on the two insertions of the ale strain, and thus offered a plausible explanation for the different expression pattern of the AGT1 gene in the ale strains. Accordingly, functional analysis of A60 ale and A15 lager strain AGT1 promoters fused to GFP (encoding the green fluorescent protein) showed a significant difference in the ability of these two promoters to drive GFP expression. Under the control of the AGT1 promoter of the ale strain the emergence of GFP was strongly induced by maltose, whereas only a low level of GFP was detected with the construct carrying the AGT1 promoter of the lager strain. Thus, the extra MAL-activator binding element, present in the AGT1 promoter of the ale strain, appears to be necessary to reach a high level of induction by maltose. Both AGT1 promoters were repressed by glucose but their derepression was different, possibly due to a distinct distribution of Mig1 elements in these two promoters.     

A new mechanism of action for skin whitening agents: binding to the peroxisome proliferator-activated receptor

Synopsis Octadecenedioic acid is known as a skin whitening agent but its activity is not mediated via a direct inhibition of tyrosinase. Based on the secondary properties of this molecule, such as its anti-inflammatory and anti-ageing effects, we postulated that octadecenedioic acid interacted with the peroxisome proliferator-activated receptor (PPAR) as this nuclear receptor also mediates these effects. Using reporter gene technology, we were indeed able to demonstrate binding of octadecenedioic acid to all three PPAR subtypes, in particular PPARgamma with an EC(50)-value of approx. 1 x 10(-6) m. Binding to PPARgamma of octadecenedioic acid or rosiglitazone, a known pharmaceutical PPARgamma agonist, led to reduced melanogenesis. Subsequently also tyrosinase mRNA (as measured by real-time polymerase chain reaction) and tyrosinase levels (as measured by Western blot) were reduced, suggesting the existence of a complete novel mechanism of skin whitening agents: binding to PPARgamma results in reduced tyrosinase mRNA expression which in turn results in less tyrosinase being formed. This in turn leads to reduced melanogenesis both in vitro and in vivo Because octadecenedioic acid binds not only to PPARgamma but also to PPARalpha and PPARdelta, other efficacies mediated via these receptors may also be expected.     

对-醋酸基苯磺酸钠对H2O2漂白的活化作用

介绍了对-醋酸基苯磺酸钠的合成及其对H2O2漂白的活化机理.采用对-醋酸基苯磺酸钠作为蔗渣浆H2O2漂白的活化剂,讨论了NaOH用量、温度、时间、活化剂用量及活化剂加入方式的影响.结果表明:活化剂用量是最主要影响因素,其次是用碱量、温度和漂白时间.漂白的适宜条件为温度55℃,NaOH用量1.5%,活化剂用量1g(对20g绝干浆),时间2h,活化剂在漂白开始90min后加入.实验证明,对-醋酸基苯磺酸钠对H2O2漂白具有显著的活化作用.     

某铅锌矿尾矿硫铁资源综合回收工艺试验研究

为了综合回收某铅锌矿尾矿中的硫、铁资源,对尾矿性质及其工艺矿物学研究分析表明,矿石中含有难选磁黄铁矿,受其影响铁精矿含硫超标;选用活化剂强化对难选磁黄铁矿捕收,采用浮选—磁选—浮选联合回收工艺,成功地获得了品位38.77％的优质硫精矿及含S 0.547％、Fe 58.04％的合格铁精矿.     

某含金精矿氰化过程中砷的氧化与金的浸出研究

某含砷金精矿含毒砂矿物较多,砷质量分数达6.12%.该精矿直接用氰化炭浆工艺处理时,金的浸出率为58.36%;经助浸剂预处理6～8h后,氰化过程中加入防膜剂及活化剂SmD,金的氰化速度加快,浸出率可达到91.2%,同时浸出时间缩短8～10h.     

都龙地区复杂铁闪锌矿强抑制后再浮选试验研究

针对文山都龙地区抑锌浮铜后被强烈抑制的铁闪锌矿难以活化,浮选回收率低的难题,采用以硫酸铜、硫酸铵和乙二胺磷酸盐组合形成的新型活化剂XYS-1强化活化,丁基黄药捕收,开展了条件试验、开路试验和闭路流程试验。在不添加石灰抑制黄铁矿、磁黄铁矿的情况下,通过一粗、两精、两扫、中矿顺序返回的浮选工艺流程进行试验。在原矿含锌品位4.48%时,获得了锌品位48.80%,选锌作业回收率92.85%的高品质锌精矿产品,尾矿中锌的品位为0.35%,锌的损失率仅为7.15%。采用以硫酸铜、硫酸铵和乙二胺磷酸盐为主要成分的新型活化剂XYS-1活化被抑制过的铁闪锌矿,获得了良好的效果,实现了铁闪锌矿的高效回收利用。