非催化条件下H_2O_2对淀粉的氧化降解行为

在非催化条件下,H2O2可以有效地对淀粉进行氧化降解。H2O2用量由2 mL增加至12 mL的过程中,淀粉的粘度下降百分率由3.49%增加至57.91%,继续增加H2O2的用量,淀粉的粘度下降百分率不再明显变化。对降解时间的研究表明,最佳反应时间为120 min,延长反应时间,淀粉的粘度反而有所增加。在18~70℃的范围内,H2O2对淀粉的氧化降解性能先增加后减弱,在60℃时达到最好,淀粉的粘度下降百分率为52.36%。在H2O2的作用下,淀粉中羟基部分被氧化为羧基或醛基,另外淀粉分子链中的1,4位的环间苷键也可能被打断,从而使淀粉的粘度下降。     

聚阴离子纤维素与羟丙基甲基纤维素复配水溶液性质的研究

研究了不同配比下,2种型号的聚阴离子纤维素(PAC)与2种型号的羟丙基甲基纤维素(HPMC)复配水溶液的性质。结果表明,复配后溶液粘度表现出了协同增效作用。经过红外与紫外分析,以及PAC、黄原胶复配产生相反现象的比较分析,证明这种协同增效作用是由于在溶液中PAC与HPMC分子间形成氢键缔合的缘故。     

芦丁水凝胶胃漂浮片制备工艺研究

单因素考察辅料,建立以亲水性凝胶材料HPMC E50(A)为40%、50%、60%,起泡剂Na_2CO_3(B)为10%、15%、20%,低密度辅料十八醇(C)为10%、15%、20%的三因素三水平正交实验,湿法制粒压片,优化得出芦丁胃漂浮片最佳成型工艺。单因素考察得最佳亲水性凝胶材料、起泡剂、低密度辅料、润滑剂分别为:HPMC E50、Na_2CO_3、十八醇、1%硬脂酸镁;正交优选出芦丁胃漂浮片最优方案为:C_2A_2B_2,即十八醇15%,HPMC E50 50%,Na_2CO_315%。本实验优选出的结果适合芦丁水凝胶胃漂浮片制备。     

甲硝唑缓释片制备与药物释放

利用湿法造粒,制备了甲硝唑羟丙基甲基纤维素(HPMC)骨架缓释片。实验结果表明,提高HPMC质量分数与使用高粘度HPMC可有效降低释药速率,但粘度4 000 mPa.s以上HPMC释药速率的降低不明显;含有粒径较大的甲硝唑原药的片剂,由于药物较强的致孔作用,药物释放速率较高;由于表面积较小的键形片上,HPMC水化凝胶层面积相对较小,甲硝唑从键形片的释放快于表面积较大的圆形片的释放。HPMC粘度、药物颗粒粒径与片形对释药速率的影响都与药物的溶解度有关。机制分析表明,药物曲线的释放符合H iguch i方程。     

生物氧化锰对水体中17β-雌二醇的氧化降解

采用锰氧化细菌生成的生物氧化锰为氧化剂,以化学氧化锰为对照,研究其对17β-雌二醇(E2)氧化降解的反应动力学,考察相关因素(如pH、氧化锰投加量等)对氧化降解的影响。结果表明,E2对生物氧化锰的氧化作用有较强的反应感受性,其被生物氧化锰降解的效果要优于化学氧化锰;在pH 7.0,E2与氧化锰的投加比为1:10条件下,60 h时E2被生物氧化锰和化学氧化锰分别降解了69.7%和39.3%,且两种反应体系均表现为复杂的反应动力学,对其4 h的反应进行1级动力学拟合,得到相关性系数分别为0.895和0.935;通过相关影响因素的研究,发现生物氧化锰对E2的氧化降解速率与氧化锰的投加量呈正相关,与pH呈负相关;此外,生物氧化锰反应体系中的雌激素总体活性降低更为明显,反应过程中检测到了1个主要产物为雌酮(E1)。     

厌氧/好氧生物过程处理高浓度HPAM污水的效果评价

部分水解聚丙烯酰胺(HPAM)被广泛的应用于油田采油过程中,它随着油田采出水进入水环境中,由于其特殊的物理和化学性质,会给环境安全带来长期的潜在威胁。在众多处理方法中,生物方法显示出越来越多的优越性,且随着不同氧环境下生物方法的不断深入研究,单一氧环境逐渐显示出了其局限性。实验中将厌氧和好氧生物过程结合起来,利用两株HPAM降解菌(PAM-2,PAM-F1)和活性污泥处理500 g·L-1HPAM模拟污水。利用淀粉碘化镉法、总有机碳(TOC)、高效液相色谱(HPLC)及扫描电镜(SEM)等多种检测方法与手段,评价其降解效果。结果表明,根据淀粉碘化镉法HPAM降解率约为86.21%;根据TOC法HPAM降解率约为32.93%;根据剪切粘度法HPAM粘度降低率约为75.75%。此外,SEM结果也佐证了随着活性污泥不断地熟化,HPAM不断发生降解。研究表明,厌氧和好氧生物过程联用可以有效的处理高浓度HPAM污水。     

缔合三元体系在油层运移过程中粘度影响因素研究

本文针对缔合聚合物三元体系在油层运移过程中剪切、吸附、稀释作用对体系粘度的影响开展室内实验研究,并与常规聚合物三元体系进行对比分析,结果表明:等粘(粘度95m Pa.s)前提下,缔合聚合物三元体系剪切前后粘度保留率可达到50%与2500万分子量聚合物粘度保留值相当。无论是等浓(聚浓度1300mg/L)还是等粘(95m Pa.s)前提下,5次吸附后碱与表活剂浓度均显著降低,缔合三元体系粘度下降的幅度均高于2500万分子量三元体系粘度下降的幅度。同时稀释聚合物、碱与表活剂至初始浓度的50%,2500万三元体系粘度下降70%,缔合三元体系粘度下降83%。目的点浓度相同前提下,缔合三元体系粘度大于2500万三元体系。建议现场配制过程中提高三元体系中碱、表浓度或者增加前置碱段塞。     

联合阴极电Fenton和阳极氧化降解高相对分子质量聚丙烯酰胺

采用浸渍-高温煅烧法制备了Fe3O4/石墨毡复合电极,联合阴极电Fenton和阳极氧化法降解聚丙烯酰胺(PAM)。以CODCr和溶液的相对粘度为指标,分别比较阴极电Fenton法、阳极氧化法及联合法对PAM的降解性能。与单一方法相比,联合法对PAM表现出强化降解效果,降解后溶液的CODCr降低了45.6%,相对粘度由2.19降低到1.04。采用凝胶渗透色谱(GPC)、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱分析(XPS)对PAM的降解产物进行表征分析。结果表明,在降解过程中PAM的碳主链缩短,侧链基团大量脱落,并有醚键生成。据此推测PAM在电催化氧化中的降解机理为碳主链的断裂与重新缩合的过程,因此,PAM降解产物中仍存在部分高分子聚合物。所生成的聚合物具有较强的可生化降解性,可被好氧活性污泥进一步降解。     

聚驱近井地带粘损机理室内模拟研究

为探索聚合物溶液注入过程中在近井地带油层的粘度损失机理,开展了一系列相关室内实验,其中首次应用20m超长填砂岩心进行了岩心流动实验,系统地研究了热降解、化学降解、机械降解以及滞留对聚合物溶液粘度损失的影响。研究结果表明:热降解和化学降解对聚合物溶液的粘度损失影响较小,分别仅为10%、5%左右;拉伸降解是孔喉中聚合物溶液机械降解的主控机理,并且机械降解引起的粘损随聚合物溶液注入速度的增大而增大,达到临界速度5m/d后,该部分粘损稳定在30%左右;滞留粘损在近井地带存在临界饱和点,在滞留非饱和区滞留粘损初期可达50%～60%,随注入量增加呈线性关系减小,达到饱和点4PV后滞留粘损下降为0。     

无机粒子的有机高分子化及其对PVC填充改性的研究

本文研究了几种无机 有机复合粒子与聚氯乙烯共混复合材料力学性能的变化规律。结果表明 :SiO2 /HPMC PMMA(SiO2 经SDS预处理 )和HPMC g PMMA使材料力学性能下降 ,而SiO2 /HPMC PMMA(未经SDS处理 )、TiO2 /HPMC PMMA、ZnO/HPMC PMMA复合粒子使材料的力学性能有所提高。经柔性设计后的SiO2 /HPMC PBA/PMMA和ZnO/HPMC PBA/PMMA使材料的冲击强度提高的幅度更大。SEM提供的证据也表明 :ZnO复合粒子使材料出现较好的塑性变形 ;经柔性设计的SiO2 复合粒子比未经柔性设计的SiO2 复合粒子使材料的塑性变形也更加显著     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution

Shrinkage reducing admixtures (SRA) have been developed to combat shrinkage cracking in concrete elements. While SRA has been shown to have significant benefits in reducing the magnitude of drying and autogenous shrinkage, it has been reported that SRA may cause a negative side effect as it reduces the rate of cement hydration and strength development in concrete. To examine the influence of SRA on cement hydration, this study explores the interactions between SRA and cement paste's pore solution. It is described that SRA is mainly composed of amphiphilic (i.e., surfactant) molecules that when added to an aqueous solution, accumulate at the solution-air interface and can significantly reduce the interfacial tension. However, these surfactants can also self-aggregate in the bulk solution (i.e., micellation) and this may limit the surface tension reduction capacity of SRA. In synthetic pore solutions, SRA is observed to form an oil-water-surfactant emulsion that may or may not be stable. Specifically, at concentrations above a critical threshold, the mixture of SRA and pore fluid is unstable and can separate into two distinct phases (an SRA-rich phase and an SRA-dilute phase). Further, chemical analysis of extracted pore solutions shows that addition of SRA to the mixing water depresses the dissolution of alkalis in the pore fluid. This results in a pore fluid with lower alkalinity which causes a reduction in the rate of cement hydration. This may explain why concrete containing SRA shows a delayed setting and a slower strength development.     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

2-(2'-咪唑偶氮)萘酚-4-磺酸的合成及其分析性质的研究

合成了新显色剂咪唑偶氮－２－萘酚－４－磺酸（ＩＡＮ－４Ｓ）,研究了试剂的离解常数及其与金属离子的显色反应。     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

Comparison between surface and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete

The effectiveness of bulk hydrophobic treatment against corrosion of galvanized steel reinforcement in concrete specimens with w/c = 0.45 and w/c = 0.75 was compared with that of surface treatment, even in the presence of cracks 0.5 and 1 mm wide in the concrete cover. In this case surface hydrophobic treatments were applied both before and after cracking as a preventive and a restorative method against reinforced concrete deterioration, respectively. The obtained results in terms of water absorption, electrochemical measurements, chlorides penetration, and visual observations carried out on reinforced concrete specimens during the exposure to wet–dry cycles in 10% NaCl solution showed that bulk hydrophobization is the most effective treatment in improving the corrosion resistance of galvanized steel reinforcements in concrete also in the presence of cracks. Surface hydrophobization is very effective just in the first few exposure cycles to the aggressive environment and when used as a restorative method which is able to cancel the deleterious effect of cracks only 0.5 mm wide.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.