Cu(II) effect on the conformation of regenerated silk fibroin in dilute aqueous solution

In nature, metal ions play a vital role in the function of protein and nucleic acid. It has been demonstrated that there are many kinds of metal ions in the gland of Bombyx mori (B. mori) silkworm, and their contents are different in different parts of silk gland[1]. These ions may promote the transition of gel to sol in the gland of silkworm when the silk fibroin (SF) goes forward to the spinneret. Many investigations have shown that K(I) and Ca(II) can induce the conformational transitio…     

Characterization of Cu（Ⅱ） Ion Adsorption Behavior of the Polyacrylic Acid-Polyvinylidene Fluoride Blended Polymer

A blended polymer adsorbent prepared using acrylic acid and polyvinylidene fluoride was used to remove copper from aqueous solutions. The polymer was prepared using thermally induced polymerization and phase inversion. The blended polymer was characterized by X-ray diffraction analysis （XRD）, environ- mental scanning electron microscopy （ESEM）, X-ray photoelectron spectroscopy （XPS）, and N2 adsorption/desorption experiments. The sorption data was fit to linearized adsorption isotherms of the Langmuir, Freundlich, and Dubinin-Radushkevich （D-R） isotherms models. The batch sorption kinetics was evaluated using pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic reaction models. △H0 is greater than 0, AGo is lower than 0, and △S0 is greater than 0, which shows that the adsorption of Cu （Ⅱ） by the blended polymer is a spontaneous, endothermic process. The adsorption isotherm fits better to the Freundlich isotherm model and the pseudo-second-order kinetics model gives a better fit to the batch sorption kinetics. The adsorption mechanism is assumed to be ion exchange between the cupric ion and the carboxylic acid functional group of the blended polymer.     

Effects of sulfide on sulfate reducing bacteria in response to Cu（Ⅱ）, Hg（Ⅱ） and Cr（VI） toxicity

Sulfate reducing bacteria (SRB) is identified as the primary organisms responsible for the treatment of heavy metal wastewater. However, most heavy metals can inhibit the growth of SRB during heavy metal treatment processes. Sulfide is a metabolic product of SRB and it can precipitate or reduce heavy metals. This study focused on the effects of sulfide on SRB resistance to Cu(II), Hg(I) and Cr(VI) toxicity. First, we considered the existence style of various heavy metals with and without sulfide addition by...     

丝素在NMMO·H2O中的溶解及溶液流变性能的研究

探讨了丝素在N-甲基吗啉-N-氧化物一水合物(NMMO.H2O)中的溶解行为,结果发现:天然蚕丝纤维脱胶后得到的丝纤维可以直接溶解在NMMO.H2O中,但是很难得到高于10%浓度的溶液,因而无法用于纺丝.而由再生丝素水溶液制得的再生丝素膜则易于溶解在NMMO.H2O中,并可以得到浓度高达25%的再生丝素/NMMO.H2O溶液,在上述研究的基础上,本文还对再生丝素/NMMO.H2O的流变行为进行了初步研究.     

温度/pH双敏感性接枝共聚物P(MAA-g-NIPAM)相行为研究

利用大分子单体技术通过自由基溶液聚合合成了不同组成的接枝共聚物聚(甲基丙烯酸-g-N-异丙基丙烯酰胺)(P(MAA-g-NIPAM)),通过UV透光率的测定和荧光探针技术对接枝共聚物在稀水溶液中的相行为进行了研究.结果表明,接枝共聚物P(MAA-g-NIPAM)具有温度和pH值的双重敏感性,不同组成的P(MAA-g-NIPAM)具有基本相同的低临界溶解温度(LCST).当溶液的pH<6时,随着pH值的降低P(MAA-g-NIPAM)的主链从较为松散的线团构象变为较为压缩的线团构象.     

凹凸棒土负载硫化纳米零价铁对水中Cu(Ⅱ)的去除机理研究

针对纳米零价铁易团聚及表面形成钝化层的缺点,本文以凹凸棒土为载体、以硫代硫酸钠为硫化试剂,制备了凹凸棒土负载硫化纳米零价铁(S-nZVI@ATP)复合材料,并考察了复合材料对水中Cu(Ⅱ)的去除效果。由SEM可观察到,经过凹凸棒土负载及硫化改性后的纳米零价铁串珠状结构变短,且被分散为单个的球形颗粒;比表面积测定结果表明,S-nZVI@ATP复合材料的BET比表面积为46.04m~2/g,与纳米零价铁相比提高了约1.35倍;由TEM观察到,经硫化的纳米零价铁颗粒界面处包裹了一层FeS,粒径由57.6nm增至118.5nm。S-nZVI@ATP复合材料去除水中Cu(Ⅱ)的机理主要是硫化纳米铁界面处的Fe~0将Cu~(2+)还原为Cu~0以及FeS转化为溶度积更小的CuS,该过程符合Langmuir-Hinshelwood吸附/还原模型和Langmuir等温吸附模型。本实验条件下,复合材料对Cu(Ⅱ)的最大吸附-还原量可达9.25mmol/g(587.8mg/g)。     

含硫席夫碱配体及其铜(II)配合物的杀菌活性研究

用圆滤纸片法和浓度稀释法测定了含硫席夫碱配体 :联苯乙酮缩氨基硫脲、乙醛酸缩氨基硫脲、安息香缩氨基硫脲及其Cu(II)配合物对大肠杆菌、产气杆菌、变形杆菌、金黄色葡萄球菌、枯草杆菌的杀菌活性 .实验发现 ,配合物的杀菌活性优于配体的杀菌活性 .     

高含量再生丝素蛋白水溶液的热性能研究

用差示扫描量热仪(DSC),对不同含量的再生丝素蛋白水溶液(质量分数为12%~42%),以及同一含量不同剪切速率(1 000 s-1和2 000 s-1)下溶液热性能的变化进行了对比研究。结果表明,随着含量的增大,再生丝素蛋白水溶液发生相转变的温度逐渐降低;同样,经剪切后的溶液发生相转变的温度均向低温漂移,且随着剪切作用的加强,向低温的漂移越明显。试验表明,丝素水溶液含量的增加和剪切作用可加速溶液从无规线团或α-螺旋向β-折叠构象的转变速度,且随着剪切速率的提高,构象转变的速度也加快。     

N-乙酰丙酮-DL-亮氨酸-水合铜(II)的合成和表征

合成了N 乙酰丙酮 DL 亮氨酸 水合铜 (II) .基于元素分析、摩尔电导、电子光谱、红外光谱和热重—差热分析进行了结构和组成分析 ,N 乙酰丙酮 DL 亮氨酸是负二价的三齿配体 ,配位原子是亚氨基氮、羧基氧和羟基氧原子     

Role of humidity on the structures and properties of regenerated silk fibers

Silk fiber was processed from highly concentrated spinning dope to solid fibers along with water removal. To understand the mechanism of water removal during silk fiber spinning process, a microfluidic chip was designed and applied to investigate the structures and mechanical properties of two kinds of regenerated silk fibroin fibers dry-spun at different relative humidity. The experimental results showed that the diameters of the fibers spun at 40% RH are always larger than the fibers spun at 50% RH due to different removal rates of water. The fibers spun at low humidity contain more β-sheet structure and lower degree of chain orientation and crystalline orientation. These results indicate that the fast phase transition of silk fibroin from sol–gel to silk fiber undergoes with rapid water removal and higher fiber orientation relates to more residue water and drawing force.     

铜(Ⅱ)-L-组氨酸络合物中咪唑环碳质子核磁弛豫速率的研究

用反转恢复法（１８０°－τ－９０°脉冲序列）测定了铜（Ⅱ）－Ｌ－组氨酸（浓度比为１：３００）体系中，咪唑环上 Ｃ（２）与 Ｃ（４）质子在不同 ｐＨ值的１Ｈ－ＮＭＲ顺磁弛豫速率Ｔ１Ｐ－１、Ｔ２Ｐ－１。实验结果指出，在所测的 ｐＨ范围内， Ｃ（２）质子比 Ｃ（４）质子有较大的弛豫速率。在ｐＨ３—４之间，它们的弛豫速率均出现极值。此现象表明，在上述ｐＨ范围内，Ｃｕ（Ⅱ）与Ｌ－组氨酸可能形成了较稳定的络合物。此外，还分别测定了金属与组氨酸浓度比为 １：３０， １：４５， １：３００， １：４５０体系中，咪唑环上 Ｃ（２）与 Ｃ（４）质子的纵向顺磁弛豫速率，可以看到，随着金属离子浓度增大，纵向弛豫速率也增大。     

Equilibrium dialysis study on the interaction between Cu(II) and HSA or BSA

The interaction of Cu(II) and human serum albumin (HSA) or bovine serum albumin (BSA) at physiological pH is studied by equilibrium dialysis. The successive stability constants are obtained by non-linear least square methods fitting Bjerrum formula. For both the Cu(II)-HSA and Cu(II)-BSA systems, the order of magnitude of K₁ and K₂ was found to be ≈10⁴ mol⁻¹· dm³. There are about twenty stoichiometry binding sites found in one HSA or BSA molecule. They can be divided into two or three sets. Results of equilibrium dialysis experiments suggest that there exists one strong metal binding site in both Cu(II)-HSA and Cu (II)-BSA. It is the imidazol group nitrogen atoms of His³ that are primarily concerned with copper binding site. After reaching dialysis equilibrium, there is the interaction among the different binding sites, the values ofK all deviate from the simple statistical effect except forK ₁ and K₂ in both Cu(II)-HSA and Cu(II)-BSA systems, and the positive cooperative effect is found.