CtpB Facilitates Mycobacterium tuberculosis Growth in Copper-Limited Niches

Copper is required for aerobic respiration by Mycobacterium tuberculosis and its human host, but this essential element is toxic in abundance. Copper nutritional immunity refers to host processes that modulate levels of free copper to alternately starve and intoxicate invading microbes. Bacteria engulfed by macrophages are initially contained within copper-limited phagosomes, which fuse with ATP7A vesicles that pump in toxic levels of copper. In this report, we examine how CtpB, a P-type ATPase in M. tuberculosis, aids in response to nutritional immunity. In vitro, the induced expression of ctpB in copper-replete medium inhibited mycobacterial growth, while deletion of the gene impaired growth only in copper-starved medium and within copper-limited host cells, suggesting a role for CtpB in copper acquisition or export to the copper-dependent respiration supercomplex. Unexpectedly, the absence of ctpB resulted in hypervirulence in the DBA/2 mouse infection model. As ctpB null strains exhibit diminished growth only in copper-starved conditions, reduced copper transport may have enabled the mutant to acquire a “Goldilocks” amount of the metal during transit through copper-intoxicating environments within this model system. This work reveals CtpB as a component of the M. tuberculosis toolkit to counter host nutritional immunity and underscores the importance of elucidating copper-uptake mechanisms in pathogenic mycobacteria.     

高冰镍浸出渣还原浸出工艺研究

以湿法冶炼高冰镍过程中产生的高冰镍浸出渣为研究对象,采用二氧化硫对高冰镍渣加压还原浸出,考察了初始硫酸浓度、液固比、通气方式、浸出温度和浸出时间对高冰镍渣还原浸出过程铜、铁行为的影响;对还原浸出液采用置换沉淀和冷冻结晶的方法,对还原浸出中铜和铁进行分离回收。结果表明：在初始硫酸浓度100 g/L、液固比6 mL/g、反应时间3 h、反应温度90℃、二氧化硫分压0.15 MPa的条件下,铁和铜的浸出率分别为99.35%、77.46%,浸出液中铁几乎全部为亚铁离子;在硫酸含量20～30 g/L、温度70℃、铁粉加入量5.7 g/L、反应时间40 min的条件下,对还原浸出液进行置换沉铜,沉铜率达到了99.70%,渣含铜为67.91%。在温度—10℃、保温时间20～30 min、初始硫酸浓度100 g/L的条件下,对沉铜后液进行冷冻结晶制备硫酸亚铁,铁沉淀率达到了72.6%,七水硫酸亚铁纯度达到了92.93%。     

双余度无刷直流电动机驱动电流非均衡状况的研究

双余度无刷直流电动机由于具有较高的安全性和容错性,已广泛应用于电力作动器等关键电力系统中.由于器件以及电机制造上的各种因素,两个电气余度的参数不会完全一致,电流出现不均衡的情况,将导致电机铜损的剧增、散热条件的恶化以及输出转矩的较大波动,影响到双余度电机性能的发挥.通过对双余度无刷直流电动机铜损以及转矩波动的分析,得出了电流不均衡情况下电机铜损变化规律和转矩波动规律,并通过样机验证了理论分析结论.     

Ta/Ta2O5/Cu结构制备及应用性能研究

介绍了以Ta/Ta₂O₅/Cu为结构的平板MIM电容器的制备方法和性能测试,探究金属Cu直接作为钽电解电容器阴极层的可行性。通过阳极氧化法在钽箔表面制备非晶态的Ta₂O₅薄膜,以化学镀铜、磁控溅射镀铜两种镀铜工艺制备Ta/Ta₂O₅/Cu结构,并对所得结构进行结构表征和性能测试。实验结果表明：不同镀铜方式制备的Ta/Ta₂O₅/Cu结构在电学性能测试过程中都没有表现出电容特性,正负极之间的电阻仅有0.7Ω;以金属Cu直接作为钽电容器的阴极层会导致金属铜在测试过程中被氧化成铜离子从而进入Ta₂O₅介质层中,进而导致Ta₂O₅的击穿,因此金属铜不适合直接作为钽电容的阴极层。     

含能催化复合纳米材料的制备研究

亚铬酸铜是促进复合固体推进剂中高氯酸铵分解的一种很好的催化剂,但由于以往制备的亚铬酸铜及高氯酸铵超细微粒易发生团聚,不能有效地对高氯酸铵的分解起催化作用。本文使用高能球磨法,使纳米级亚铬酸铜嵌入或粘附于高氯酸铵晶体表面而形成复合粒子,因而大大地提高了对高氯酸铵的催化效果,使高氯酸铵的热分解反应温度区间明显前移,热分解反应的激烈程度大大提高     

PVA生产装置中铜塔的腐蚀与防护

简述了国内聚乙烯醇装置中铜塔的腐蚀状况,并分析判断了铜塔的腐蚀原因,提出了铜塔的防护措施和选材意见.     

新型芳香二胺的合成及其聚酰亚胺的应用研究

首先通过双酚A和碳酸钾反应得到酚钾盐,与间-二硝基苯反应合成2,2-双[4-(3-硝基苯氧基)苯基]丙烷(3-BNPP),再用水合肼还原得到新型芳香二胺单体2,2-双[4-(3-氨基苯氧基)苯基]丙烷(3-BAPP)。用3-BAPP与多种二酐合成出多种聚酰亚胺,并在二层法挠性覆铜板(2L-FCCL)的应用方面做了一些研究。研究表明其相应的2L-FCCL具有良好的耐锡焊性能和较低的吸水率。     

含铜和镍电镀污泥还原氨浸工艺及反应动力学分析

采用还原氨浸工艺实现电镀污泥中铜、镍的浸出。在20%(质量分数)氨水+0.3 mol/L (NH₄)₂CO₃+0.4 mol/L Na₂SO₃的浸出体系中,当固液比为1∶15,在70℃下浸出3h,铜、镍的浸出率别为95.84%和90.12%。反应动力学分析表明,氨-碳酸铵-亚硫酸钠体系浸出电镀污泥中铜、镍受界面传质和固体膜层扩散共同控制。     

Effects of Chloride Ion on the Texture of Copper and Cu-ZrB2 Coatings Electrodeposited from Copper Nitrate Solution in Different Plating Modes

For the first time, the texture of copper and Cu-ZrB2 coatings produced from copper nitrate solution was studied. Chloride ion shows different effects on the deposit texture under direct current （DC） and pulse current （PC） conditions. Copper deposits are strongly 〈220〉 textured in DC plating with and without chloride ion. While in PC condition, the predominant texture shifts from 〈220〉 to 〈200〉 as the chloride ion concentration exceeds 20 mg/l. The addition of ZrB2 particles enhances the cathodic polarization of copper deposition, which improves the growth of （111） plane. However, this improvement can be eliminated by further addition of chloride ion.     

Use of mesophilic and thermophilic bacteria for the improvement of copper extraction from a low-grade ore

Bioleaching was examined for copper extraction from a low grade ore using mesophilic and moderate thermophilic bacteria. Five equal size columns were used for the leaching of the ore. Sulfuric acid solution with a flow rate of 3.12 L.m-2.h-1 and pH 1.5 passed through each column continuously for 90 d. In the first and the second column, bioleaching was performed without agglomeration of the ore and on the agglomerated ore, respectively. 28wt% of the copper was extracted in the first column after 40 d, while this figure was 38wt% in the second column. After 90 d, however, the overall extractions were almost the same for both of them. Bioleaching with mesophilic bacteria was performed in the third column without agglomeration of the ore and in the fourth column on the agglomerated ore. After 40 d, copper extractions in the third and the fourth columns were 62wt% and 70wt%, respectively. Copper extractions were 75wt% for both the columns after 90 d. For the last column, bioleaching was performed with moderate thermophilic bacteria and agglomerated ore. Copper extractions were 80wt% and 85wt% after 40 and 90 d, respectively. It was concluded that crushing and agglomeration of the ore using bacteria could enhance the copper extraction considerably.