2.3 Wood pulp manufacturing and quality characteristics

Cellulose acetate being important in the fiber and textile industries is usually prepared from high quality cellulose such as cotton linters and wood pulps with an alpha cellulose content of more than 95%. In this section, therefore, wood pulps and cotton linters appropriate for cellulose acetate production were discussed in their chemical and physical properties so as to use them judiciously as natural raw materials for cellulose acetate production.     

长链脂肪酸魔芋葡甘聚糖酯的制备及乳化性能研究

采用非均相酰化法制备了四个系列的长链脂肪酸魔芋葡甘聚糖酯（ＫＧＭＥ）．ＤＴＡ图显示了葡甘聚糖酯的晶态结构变化,Ｘ 射线衍射分析表明了不同长度的酰链对葡甘聚糖酯晶态结构的影响．初步研究了葡甘聚糖酯在芳香烃及环烷烃两种水包油（Ｏ／Ｗ）乳液体系中其取代度与乳化力的关系．实验证明在水包油乳液体系中,取代度在某一范围的葡甘聚糖酯显示出较好的乳化能力,且在高盐浓度和酸性情况下,仍给出好的乳化作用．丁香油 水（Ｏ／Ｗ）乳液体系在室温下静置四个星期未发现破乳分离现象     

利用氧化和希夫碱反应制备具有手性分离功能的滤纸

纸色谱具有微量、快速、高效和灵活程度高等特点。以滤纸为原料用高碘酸钠氧化法合成了二醛基滤纸,通过希夫碱反应接枝手性氨基酸,合成了一种具有手性分离功能的新型纸色谱材料。通过单因素试验和正交试验确定滤纸氧化的最佳合成条件为：高碘酸钠的质量分数为4%, pH值为2,反应温度45℃和反应时间4 h,该条件下氧化滤纸醛基含量为57.93%（物质的量分数）。氧化滤纸与L-谷氨酸通过微波合成得到具有手性分离功能的色谱用纸。利用该种手性滤纸分离外消旋酒石酸,展开剂配方为100 mL 50%正丁醇,50 mL乙酸和0.1000 g溴酚绿。结果显示,L-酒石酸比移值（R_f）为0.52, D-酒石酸R_f为0.40。该方法不需要使用大型设备,适合一般的教学、研究及工业应用。     

A study of cationic glucomannan as a paper strength agent

In this paper, konjac glucomannan was cationized by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (a kind of cationic reagent) as a paper strength agent. The effects of dosage of cationic reagent, cationization time, cationization temperature and the pH of papermaking on paper properties were analyzed. The results showed that when 1% cationic glucomannan (the cationization temperature was 70°C, dosage of cationic reagent was 20% and cationization time was 5 h) was added, tensile index, burst index and folding endurance of the paper were improved by 11.0%, 13.2%, 72.0%, respectively, compared with the control. The results of SEM analysis, FTIR analysis, and elemental analysis illustrated that the addition of paper strengthening agent make fibers combined more closely, and further lead to the increase of paper strength properties.     

An efficient preparation and some reactions of 2-dimethylaminomethylene-1,3-bis(dimethylimonio)propane diperchlorate

An alternative preparation of 2-dimethylaminomethylene-1,3-bis(dimethylimonio)propane diperchlorate from malonic acid is described along with its application to the synthesis of 2,4,6-trisubstituted phenols and 2-(N-(2,2-diformylethenyl)amino)pyridine.     

Polydopamine/dialdehyde starch/chitosan composite coating for in-tube solid-phase microextraction and in-situ derivation to analysis of two liver cancer biomarkers in human blood

In order to highly enrich two liver cancer biomarkers (hexanal and 2-butanone) in human blood, in this study, natural nontoxic polydopamine/dialdehyde starch/chitosan (PD/DAS/CHI) coating material was synthesized and immobilized on the inner wall of polytetrafluoro-ethlyene (PTFE) tube. It was used to develop the method based on in-tube solid-phase microextraction (IT-SPME) with in-situ derivatization (ISD) coupled to high performance liquid chromatography for the determination of the above mentioned two liver cancer biomarkers in human blood. The simple, rapid and sensitive IT-SPME-ISD method can be finished within 11 min. Under optimum conditions, the limits of detection (LODs) were 1.4 and 1.6 nmol L⁻¹ for hexanal and 2-butanone, respectively. The relative recoveries from real human blood samples were in the range from 70% to 91% with the intra- and inter-day precisions less than 7.2%. Furthermore, this method was successfully applied for the analysis of hexanal and 2-butanone in blood samples from healthy people with 0.42 ± 0.05 and 0.34 ± 0.04 μmol L⁻¹, while liver cancer patients with 1.90 ± 0.07  μmol L⁻¹ and 0.91 ± 0.07 μmol L⁻¹, respectively. The t-test's results showed there is a statistically significant difference between the data from healthy persons and liver cancer patients. Hence, the developed method might be applied in the screening of suspected liver cancer patients.     

魔芋多糖固定化肌红蛋白的直接电化学与电催化

用魔芋多糖(KGM)和N,N-二甲基甲酰胺(DMF)的加合物,将肌红蛋白(Mb)固定在玻碳电极(GCE)上,制备了稳定的Mb-KGM-DMF/GCE修饰电极,并研究了Mb在修饰电极上的直接电化学行为和电催化性能。该电极在pH=7.0的磷酸盐缓冲溶液(PBS)中,-0.38 V(E0′)处有一对氧化还原峰,峰电位差ΔEp=70 mV,该峰正是Mb中血红素辅基FeⅢ/FeⅡ电对的氧化还原特征峰。在0.2~9.0 V/s扫速的范围内,氧化还原峰峰电流大小和扫描速率成正比,呈现出表面控制行为。在pH为5.0~12.0的范围内,式电位和pH值呈线性关系,表明电子传递过程伴随着质子转移。同时,Mb-KGM-DMF/GCE修饰电极表现出良好的电催化性能,对氧、H2O2有显著的催化作用。在4.70~75.0μmol/L的范围内,其催化峰电流大小与H2O2的浓度有良好的线性关系,其线性回归方程i=0.127 0.093C,r=0.9989,表观米氏常数为80.8μmol/L。     

Biodegradable packing materials based on waste collagen hydrolysate cured with dialdehyde starch

Hydrogels of collagen hydrolysate (H) of mean M _w 15–30 kDa obtained from waste collagen from meat casings manufacture, cross-linked with 15% (based on H) polymeric dialdehyde starch (DAS), have a marked tendency to ageing, which shows in hydrogel gradually increasing rigidity and decreasing thermo-reversibility. Methods of thermal analysis (DSC, TG) proved that ageing of hydrogels is not related with a non-equilibrium state of the cross-linking reaction but is rather given by increasing density of inter-chain hydrogen bonds between polypeptide segments of H. Plasticizing effect of DAS on H is not too pronounced but the difference between glass transition temperature of dry xerogel T _g = 189.5±2.5°C and temperature of starting degradation (DAS component) 241.4±12.7°C offers certain space for processing these xerogels into biodegradable (edible) packaging material by usual plastics technologies. Films obtained from the reaction mixture by casting and drying at room temperature after thermal processing (105°C for 4 h) dissolve at room temperature only after 350 h. This effect can be employed for time-controlled releasing of active substances from such biodegradable (edible) packages.     

以Pb-(BrO_3~-/Br~-)为媒介间接电氧化合成双醛淀粉

应用间接氧化法,以Pb为阳极,BrO3-/Br-为氧化媒介,电氧化淀粉制备双醛淀粉.研究了温度、硫酸与淀粉浓度对电合成过程的影响.在35℃,阳极液WNaBr=2%,CH2SO4=0.05 mol/L,W淀粉=10%,电流密度15 mA/cm2的实验条件下,电流效率为50%.     

Two-dimensional model of intramolecular hydrogen bond

One- and two-dimensional vibrational problems were solved to determine the states of H and D in the intramolecular hydrogen bond of malonic dialdehyde. Within the one-dimensional approach the model potential (barrier height 51 kJ/mol) satisfied with the IR and microwave spectroscopy data. For the two-dimensional problem an approach to evaluation of eigenvalues with high accuracy based on the Ritz method was developed. Within the two-dimensional approximation the barrier height was taken to be 57 kJ/mol. An introduction of the second dimension was found to give rise to the vibrational non-adiabatic effects.