阳离子聚丙烯酰胺对纸板干强度的影响

本文介绍了阳离子矣丙烯酰胺干强剂的合成，性质及其在造纸工业中应用。考察了某一型号聚丙烯酰胺的分子量，添加用量等对纸板增强效果的影响。     

Cationic Amphiphilic Peptides: Synthetic Antimicrobial Agents Inspired by Nature

Antimicrobial peptides are ubiquitous in multicellular organisms and have served as defense mechanisms for their successful evolution and throughout their life cycle. These peptides are short cationic amphiphilic polypeptides of fewer than 50 amino acids containing either a few disulfide-linked cysteine residues with a characteristic β-sheet-rich structure or linear α-helical conformations with hydrophilic side chains at one side of the helix and hydrophobic side chains on the other side. Antimicrobial peptides cause bacterial cell lysis either by direct cell-surface damage via electrostatic interactions between the cationic side chains of the peptide and the negatively charged cell surface, or by indirect modulation of the host defense systems. Electrostatic interactions lead to bacterial cell membrane disruption followed by leakage of cellular components and finally bacterial cell death. Because of their unusual mechanism of cell damage, antimicrobial peptides are effective against drug-resistant bacteria and may therefore prove more effective than classical antibiotics in certain cases. Currently, around 3000 natural antimicrobial peptides from six kingdoms (bacteria, archaea, protists, fungi, plants, and animals) have been isolated and sequenced. However, only a few of them are under clinical trials and/or in the commercial development stage for the treatment of bacterial infections caused by antibiotic-resistant bacteria. Moreover, high structural complexity, poor pharmacokinetic properties, and low antibacterial activity of natural antimicrobial peptides hinder their progress in drug development. To overcome these hurdles, researchers have become increasingly interested in modification and nature-inspired synthetic antimicrobial peptides. This review discusses some of the recent studies reported on antimicrobial peptides.     

阳离子脂质体DLin-MC3-DMA合成

可电离的阳离子脂质体DLin-MC3-DMA是一种高效的siRNA运输载体,它能有效封装相应的siRNA并使其进入细胞质内,然后两者分离,siRNA发挥其功效。以价格低廉的亚油酸为起始原料,经还原、溴代、格氏和缩合等4步反应,高效合成了目标化合物DLin-MC3-DMA,不仅缩短了反应步骤,而且有效降低了成本。     

影响阳离子醚化剂结晶点的工艺条件研究

介绍了采用氯甲基环氧丙烷和三甲胺盐酸盐水相合成阳离子醚化剂(CHPTA)的工艺。考察了升温反应时间、反应温度、原料配比对产品结晶点的影响。结果表明:在低温(10±1℃)滴加氯甲基环氧丙烷,25℃反应2 h,35℃反应3 h;原料配比n(三甲胺盐酸盐)∶n(氯甲基环氧丙烷)=0.95∶1.00的条件下合成的产品结晶点可达到-18℃以下。     

非反应型阳离子助剂在一浴法无盐轧蒸染色工艺中的应用

使用自制的非反应型阳离子助剂对棉织物进行预处理,分别选用活性黄K-RN、活性艳红K-2BP、活性艳蓝KN-R进行一浴法无盐轧蒸染色试验.确定了阳离子助剂处理棉织物的最佳方式和使用的最佳浓度,并与常规有盐染色进行性能对比.结果表明,采用一浴法无盐轧蒸染色对染样的固色率、色光和牢度未产生影响.阳离子助剂的使用能够替代电解质的加入,染料利用率提高25％～40％.棉纤维阳离子化能够在相对较低的温度下进行,提高了该工艺的适用范围,最终达到节能减排的目的.     

乳液型丙烯酸树脂改性阳离子淀粉增干强剂的制备及性能

淀粉与阳离子醚化剂在碱性介质和氧化剂存在下 ,搅拌加热至 6 5～ 70℃ ,进行氧化降解和阳离子化反应 ,反应时间为 2h。再加入丙烯酸及丙烯酸酯单体于 80～ 85℃进行接枝共聚 ,m (玉米淀粉 )∶m (改性单体 ) =1 0∶0 8时 ,得到的乳液型丙烯酸树脂接枝共聚阳离子淀粉增干强剂的增强效果最好 ,对增加纸张干强度和耐撕裂度有明显效果 ,用量为绝干浆质量的 0 4%～ 0 .5 %时 ,可使纸的干强度增加 15 %以上 ,耐撕裂度提高 8%以上。并用IR、SEM、DSC等手段对这种接枝共聚物的结构与性能进行了表征     

Synthesis and Biological Studies of Dodecameric Cationic Antimicrobial Peptides Containing Tetrahydrofuran Amino Acids

We report here a concise route to synthesize various stereoisomers of tetrahydrofuran amino acids (TAAs) and the synthesis of TAA-containing linear cationic dodecapeptides. Some of these linear peptides show slightly better antimicrobial activities than their tetra- and octameric congeners, but no activity against Mycobacterium tuberculosis, for which octapeptides exhibited by far the best results; this implies that antibacterial activity is dependent on the length of these linear peptides. All the dodecapeptides described here were found to be toxic in nature against Vero cells. The study helps to delineate the optimal length of this series of linear peptides and select potential leads in the development of novel cationic peptide-based antibiotics.     

Antimicrobial Peptides and Cationic Nanoparticles: A Broad-Spectrum Weapon to Fight Multi-Drug Resistance Not Only in Bacteria

In the last few years, antibiotic resistance and, analogously, anticancer drug resistance have increased considerably, becoming one of the main public health problems. For this reason, it is crucial to find therapeutic strategies able to counteract the onset of multi-drug resistance (MDR). In this review, a critical overview of the innovative tools available today to fight MDR is reported. In this direction, the use of membrane-disruptive peptides/peptidomimetics (MDPs), such as antimicrobial peptides (AMPs), has received particular attention, due to their high selectivity and to their limited side effects. Moreover, similarities between bacteria and cancer cells are herein reported and the hypothesis of the possible use of AMPs also in anticancer therapies is discussed. However, it is important to take into account the limitations that could negatively impact clinical application and, in particular, the need for an efficient delivery system. In this regard, the use of nanoparticles (NPs) is proposed as a potential strategy to improve therapy; moreover, among polymeric NPs, cationic ones are emerging as promising tools able to fight the onset of MDR both in bacteria and in cancer cells.     

阳离子型含氟聚丙烯酸酯无皂乳液的合成 及其性能研究

以可逆加成-断裂链转移(RAFT)聚合合成的聚甲基丙烯酸N,N-二甲氨基乙酯-b-丙烯酸六氟丁酯（PDMAEMA-b-PHFBA）为稳定剂,通过无皂乳液聚合技术合成了阳离子型含氟聚丙烯酸酯无皂乳液。采用红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、透射电子显微镜(TEM)、动态光散射(DLS)对乳胶粒子和聚合物的结构进行了表征。结果表明,当PDMAEMA-b-PHFBA用量为2.4%时,乳液的稳定性好,转化率高,乳胶粒具有明显的核壳结构,且粒径分布窄。将阳离子型含氟聚丙烯酸酯无皂乳液用于皮革涂饰后,皮革表面的防水防油性得到明显提高,随着丙烯酸六氟丁酯用量的增加,涂饰后的皮革对水和二碘甲烷的接触角逐渐增加,当丙烯酸六氟丁酯用量为10%时,涂饰后的皮革对水的接触角为125?,对二碘甲烷的接触角为81.5?。     

阳离子无氟丙烯酸酯防水剂的制备及应用

以甲基丙烯酸十八烷基酯（ SMA）、甲基丙烯酰胺（ MAA）、丙烯酸羟乙酯（ HEA）和甲基丙烯酰氧乙基三甲基氯化铵（ DMC）为单体,十六烷基三甲基溴化铵（ CTAB）和聚氧乙烯醚（ AEO-20）为复合乳化剂,偶氮二异丁脒盐酸盐（ AIBA）为引发剂,采用细乳液聚合法制备无氟阳离子丙烯酸酯防水剂。分析了聚合物温度、乳化剂用量和交联剂用量（ HEA）对乳胶性能的影响。结果显示：乳化剂为 7%,HEA为 2%,反应温度为 80 ℃,反应时间为 5h,合成的乳胶性能最佳。当防水剂用量为 100 g/L时,整理后的棉织物显示了较强的疏水性能,其接触角达到 139°。经过 25次洗涤后,棉纤维仍然具有较高的接触角,说明具有优良的耐洗性能。     

阳离子醚化剂CHPTMAC的催化合成研究

以环氧氯丙烷和三甲胺为主要原科在水相条件下合成阳离子醚化剂CHPTMAC是一种经济实用的工艺路线。合成过程中的副产物对产品的应用性能影响明显,采用不同的催化剂可以降低副产物在产品中的含量,添加经过处理之后的金属氧化物可降低副产物的生成量,降低了产品纯化的难度,节约了后处理成本。     

Effects of Lipidation on a Proline-Rich Antibacterial Peptide

The emergence of multidrug-resistant bacteria is a worldwide health problem. Antimicrobial peptides have been recognized as potential alternatives to conventional antibiotics, but still require optimization. The proline-rich antimicrobial peptide Bac7(1-16) is active against only a limited number of Gram-negative bacteria. It kills bacteria by inhibiting protein synthesis after its internalization, which is mainly supported by the bacterial transporter SbmA. In this study, we tested two different lipidated forms of Bac7(1-16) with the aim of extending its activity against those bacterial species that lack SbmA. We linked a C12-alkyl chain or an ultrashort cationic lipopeptide Lp-I to the C-terminus of Bac7(1-16). Both the lipidated Bac-C12 and Bac-Lp-I forms acquired activity at low micromolar MIC values against several Gram-positive and Gram-negative bacteria. Moreover, unlike Bac7(1-16), Bac-C12, and Bac-Lp-I did not select resistant mutants in E. coli after 14 times of exposure to sub-MIC concentrations of the respective peptide. We demonstrated that the extended spectrum of activity and absence of de novo resistance are likely related to the acquired capability of the peptides to permeabilize cell membranes. These results indicate that C-terminal lipidation of a short proline-rich peptide profoundly alters its function and mode of action and provides useful insights into the design of novel broad-spectrum antibacterial agents.     

聚合物结构对阳离子含氟PUA中性施胶剂的影响

研究了阳离子含氟聚氨酯-丙烯酸酯复合乳液(PUA)中性施胶剂的制备和应用,重点分析了亲水单体、聚丙烯酸酯、含氟丙烯酸酯对阳离子含氟PUA中性施胶剂应用效果和产品稳定性的影响,并用红外光谱(FTIR)和核磁共振氟谱(19F- NMR)对其结构进行了表征.结果表明,当用量为0.8％时,纸张的施胶度大于36.70s;乳液的ξ...     

P(St/BA/DBMEA)阳离子乳液在污水净化中的应用

~~P(St/BA/DBMEA)阳离子乳液在污水净化中的应用@邹其超$湖北大学化学与材料科学学院!武汉,430062 @张金枝$湖北大学化学与材料科学学院!武汉,430062 @李小琴$湖北大学化学与材料科学学院!武汉,430062 @程时远$湖北大学化学与材料科学学院!武汉,430062~~~~~~     

新型阳离子降滤失剂PKC-3的研制与应用

将下脚料聚丙烯腈水解,用三甲胺、甲醛进行阳离子化,再用过氧化氢氧化,制得了阳离子度为10 5%的降滤失剂PKC 3。在PKC 3加量为0 5%的情况下可使膨润土基浆的API滤失量较大幅度地降低,抗盐抗污染性能良好,页岩回收率明显高于所评价的其它处理剂,探讨了其作用机理,现场应用表明,效果明显。     

Novel Cationic RAFT‐Mediated Polystyrene/Clay Nanocomposites: Synthesis,Characterization, and Thermal Stability

Two novel cationic RAFT agents, PCDBAB and DCTBAB, were anchored onto MMT clay to yield RAFT‐MMT clays. The RAFT‐MMT clays were then dispersed in styrene where thermal self‐initiation polymerization of styrene to give rise to exfoliated PS/clay nanocomposites occurred. The RAFT agents anchored onto the clay layers successfully controlled the polymerization process resulting in controlled molecular masses and narrow polydispersity indices. The nanocomposites prepared showed enhanced thermal stability, which was a function of the clay loading, clay morphology, and slightly on molecular mass.

     

阳离子聚合物固墨剂及其对喷墨记录介质性能的影响

两步法合成了二甲基二烯丙基氯化铵(DMDAAC),并将DMDAAC进行聚合,得到聚二甲基二烯丙基氯化铵(PDMDAAC),以其作为阳离子聚合物固墨剂应用于喷墨记录介质的涂层中,研究了它对几种喷墨记录性能的影响。结果表明:当颜料与亲水性聚合物的比例为90/10,阳离子聚合物固墨剂PDMDAAC的添加量为6%时,喷墨记录介质涂层的记录性能达到最佳,吸墨速度为6.2 s,清晰度为1.0015,耐水性能达到a级。     

Supramolecular Cationic Assemblies against Multidrug-Resistant Microorganisms: Activity and Mechanism of Action

The growing challenge of antimicrobial resistance to antibiotics requires novel synthetic drugs or new formulations for old drugs. Here, cationic nanostructured particles (NPs) self-assembled from cationic bilayer fragments and polyelectrolytes are tested against four multidrug-resistant (MDR) strains of clinical importance. The non-hemolytic poly(diallyldimethylammonium) chloride (PDDA) polymer as the outer NP layer shows a remarkable activity against these organisms. The mechanism of cell death involves bacterial membrane lysis as determined from the leakage of inner phosphorylated compounds and possibly disassembly of the NP with the appearance of multilayered fibers made of the NP components and the biopolymers withdrawn from the cell wall. The NPs display broad-spectrum activity against MDR microorganisms, including Gram-negative and Gram-positive bacteria and yeast.     

季铵型阳离子淀粉合成及应用

介绍了季铵型阳离子淀粉的湿法生产工艺,着重讨论了合成反应过程中催化剂用量、醚化剂用量、反应温度、反应时间等因素对取代度和反应效率的影响。淀粉用量为100kg,醚化剂CHPT用量为5,2kg,催化剂用量为2．6kg,淀粉乳浓度58％,氢氧化钠水溶液浓度50％、反应温度50℃、反应时间15h。在此条件下,取代度可达0．0268,反应效率达80％以上。     

阳离子明胶蛋白助剂在涤纶碱减量中的应用研究

将自制的阳离子明胶蛋白助剂应用于涤纶碱减量处理工艺中,探讨阳离子明胶蛋白助剂对涤纶减量率的影响以及对涤纶吸湿性的影响,同时与促进剂1227的作用效果进行比较,评价阳离子明胶蛋白助剂的处理效果。结果表明:阳离子明胶蛋白助剂对涤纶碱减量有一定促进作用,同时对涤纶有一定改性作用,能进一步改善碱减量涤纶织物的服用性能。虽然阳离子明胶蛋白助剂对涤纶碱减量的促进效果低于促进剂1227,但其对改善涤纶吸湿性、透气性、抗静电性和白度效果优于1227。