糠醇聚合物的制备研究

文章对糠醇(FA)聚合物的制备进行了研究。研究结果表明:糠醇的聚合反应受到反应时间、温度和催化剂量的较大影响。延长反应时间、提高反应温度或增大催化剂用量,均可增大糠醇聚合物的分子量,使其粘度增大。同时,对甲苯磺酸对糠醇(FA)聚合物具有较好的固化效果。     

Efficient enzymatic synthesis of ampicillin using mutant Penicillin G acylase with bio-based solvent glycerol

To fulfill the industry demand of ampicillin enzymatic synthesis, immobilized mutant Penicillin G acylase and bio-based solvent glycerol were employed at high substrate concentration and low acyl donor/nucleophile ratio. After process optimization, good yield and low operation costs were achieved.     

Adsorption of a silicone‐based surfactant on polyethylene and polypropylene surfaces and its tribologic performance

Aqueous silicone‐based surfactants are widely used in the processing of synthetic fibers in textile industries since they enhance a number of functional and processing properties. In this paper the interactions between silicone‐based surfactants and textile‐relevant surfaces (polyethylene and polypropylene) were investigated by quartz crystal microbalance with dissipation and the tribologic performance was evaluated by lateral force microscopy. Our results showed that the more hydrophobic polypropylene surface had higher affinity with silicone‐based lubricants than polyethylene surface. These adsorbed layers provided lubricity in textile materials when subject to shear forces and offered protection to wear and abrasion. This is explained by the fact that the hydrophobic groups in the surfactant molecules interact more effectively with the polypropylene surface via hydrophobic forces. This information will ultimately help to further our understanding on lubrication phenomena in fiber processing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40838.     

A viewpoint on the gastrointestinal fate of cellulose nanocrystals

BackgroundCellulose nanocrystalline (CNC) particles possess unique functional properties such as vastly modifiable surface, considerable mechanical strength and acid resistance, as well as, high aspect ratio. CNCs have received great attention for application in diverse fields of technology including (composite) hydrogels fabrication for the gastric protection and enteral delivery of drugs and nutraceuticals.Scope and approachThe orogastrointestinal digestibility and absorbability of the orally administered CNCs is overviewed in the current article. At first, some surface charge-related characteristics of acid-isolated CNCs are communicated. Then, the biocompatibility and biodegradability of CNCs and CNC-reinforced hydrogels are reviewed, followed by presenting credible digestion and absorption scenarios. Finally, the post-absorption metabolism of CNCs is briefly debated.Key findings and conclusionsBacterial cellulose shows good biocompatibility and hemocompatibility. CNC oxidation provides biologically beneficial impacts; for instance, the TEMPO- and periodate-oxidized CNCs have been shown to regulate some blood metabolic variables and improve the degradability in simulated human blood plasma, respectively. Spherical and carboxyl-bearing cellulose nanoparticles can be isolated through ammonium persulfate digestion. The sphericity of particles results in faster cellular uptake. Negatively-charged CNCs are non-mucoadhesive and thus upon ingestion can penetrate into the buccal and intestinal mucosa. One may augment the absorption of CNCs by targeted receptor-mediated endocytosis. It was postulated that sodium bicarbonate secretion into the duodenum can alter CNCs surface chemistry and influence CNC interaction with gut microbiota.     

Effect of acid hydrolysis in the presence of anhydrous alcohols on the structure,thermal and pasting properties of normal,waxy and high‐amylose maize starches

Maize starches with different amylose contents (0%, 23% and 55%) were treated in anhydrous methanol, ethanol, 2‐propanol, 1‐butanol with 0.36% HCl at 25 °C for 5 days. Results showed that the extent of change in physicochemical properties increased from methanol to butanol. Treated waxy maize starch showed higher than 65% solubility at above 75 °C. The diffraction peak at 2θ = 5.3° of amylomaize V starch disappeared after treatment in ethanol, 2‐propanol and 1‐butanol. Acid–alcohol treatment decreased the gelatinisation temperature of normal (from 64.5 to 61.9 °C) and waxy maize (from 68.1 to 61.1 °C) starches, while it increased that of amylomaize V (from 68.7 to 72.3 °C) starch. The extent of the decrease in the pasting viscosity followed the following order: amylomaize V < normal maize < waxy maize. This study indicated that acid–alcohol treatment degraded preferentially the amorphous regions and the different changes depended on the crystal structure and amylose content of starch.     

关于有效解决多组分沉积物问题的研究

纸厂中的沉积物通常含有多种组分,其主要来源于机械浆、回用纤维、涂布损纸以及过程添加剂等多种原料.通常这些沉积物中某一组分可作为沉积作用的主要引发剂,同时也可作为其他原料之间的粘合剂,因此对这种引发剂进行鉴定和处理对减少胶粘物的沉积具有重要意义.另一方面,在胶粘物沉积现象严重的过程中,其还可以帮助有效地鉴别二次胶粘物.然而,要准确鉴别这种引发剂还有一定的难度.作者对纸厂胶粘物的沉积、浆料、沉积机理以及沉积物本身的组成等进行了研究,以期建立一种可靠的方法,有效地鉴别目前以及将来引发沉积物沉积的引发剂.     

纳米二氧化钛胶体对脱墨浆中DCS絮聚去除的GC-MS研究

采用GC-MS表征絮聚前后DCS组分变化的方法研究了纳米TiO2胶体对脱墨浆中DCS絮聚去除的机理.结果表明,该脱墨浆中DCS可硅烷化主要组分为树脂酸、脂肪酸、苯二甲酸酯类物质、2,2-双（4-羟苯基）丙烷和甾醇类等物质;纳米Ti O2胶体对上述多数组分有较强的絮聚去除能力,去除机理主要为“桥连絮聚”作用,且去除效果随组分分子极性增大而增强,随分子结构的位阻屏蔽作用增强而减弱.     

造纸法烟草薄片废水混凝预处理研究

以聚合氯化铝(PAC)和聚合硫酸铁(PFS)为混凝剂,4种不同类型的聚丙烯酰胺(PAM)为助凝剂,对造纸法烟草薄片废水进行混凝处理,分别考察了 pH值、混凝剂用量、助凝剂用量对混凝效果的影响.结果表明,PAC与PFS对COD、氨氮和悬浮物(SS)去除率效果相当,但PAC的脱色效果更佳.相对分子质量700万、离子化度为15％的阳离子聚丙烯酰胺(PAM4)与PAC的复配体系具有最佳的混凝效果,在pH值为6 5、PAC用量为500mg/L、PAM4用量为5mg/L的优化工艺条件下,COD、氨氮、色度和SS去除率分别为70.8％、84.8％、72.3％和98.5％.废水的铝含量分析表明,该体系非但没有产生残留铝,而目大幅去除了原水中的铝.处理后废水的紫外吸收光谱表明,有机物含量降低.     

纳米TiO2胶体与改性淀粉双元体系的助留助滤效果

利用动态滤水(DDJ)实验,通过细小纤维单程留着率和滤水时间对纳米TiO2胶体与改性淀粉双元体系的助留助滤效果进行考察。研究该双元体系复配对纸张强度的影响及对白水循环中溶解和胶体物质(DCS)的除去与控制。结果表明,与阳离子淀粉(CS)相比,两性淀粉(AmS)与纳米TiO2双元体系有更好的协同作用,当淀粉用量不同、纳米TiO2用量约为0.4%时,细小组分单程留着率可增加5～12个百分点;纳米TiO2对AmS有正面的影响;AmS与纳米TiO2胶体复配对DCS的去除效果明显。