超声波对大豆水化油脚-磷脂酶A2反应体系的影响

大豆磷脂酶改性可以明显改善其O／W乳化性能，磷脂酶改性反应时间一般需要7h，而超声波处理则可明显缩短反应时间。以大豆水化油脚为原料，研究了超声波处理对磷脂酶A2制备酶改性大豆磷脂的影响。结果表明，在pH7．5，55℃反应条件下，采用超声波辅助反应40min后，所制备的溶血磷脂HLB值达到8。与未采用超声波溶血磷脂HLB值相同。超声波促进磷脂酶改性效果明显。     

THE ATTACHMENT OF BREWING YEAST TO GLASS

The secondary conditioning of cask and bottled beer with live yeast is normally facilitated by ensuring the sedimentation of the yeast to the base of the package prior to dispense. Here we examine the resistance of yeast sediment to disruption in bottled conditioned beer by investigating the attachment of brewing yeast to glass. An attachment assay is described which, when applied to brewing yeast, demonstrated that these yeasts are not naturally adhesive. However, yeast may be encouraged to form an attached mat by the physiological manipulation of starvation. The significance of this observation is discussed in relation to the effect of beer composition on yeast attachment.     

滞后响应模型在黄河内蒙古河段的应用

通过黄河内蒙古河段巴颜高勒站和三湖河口站实测水沙资料分析表明,巴颜高勒站平滩流量的调整与包括当年在内的前期10年的水沙条件相关,三湖河口站则与包括当年在内的前期14年的水沙条件相关.将滞后响应模型应用于黄河内蒙古河段平滩流量的计算,得到了适用于巴颜高勒站和三湖河口站平滩流量的计算方法.计算结果表明,滞后响应模型能够很好的描述该河段的平滩流量调整规律,计算精度较高.分析认为滑动平均计算方法可以看作是滞后响应模型的一种简化形式,针对巴颜高勒站和三湖河口站平滩流量的滑动平均计算方法也可得到较高的精度.     

海泥电池Fe_3O_4/PANI复合阳极制备及电化学性能

由FeCl2、FeCl3、樟脑磺酸及苯胺合成Fe3O4/PANI,将Fe3O4/PANI粉末与碳粉按1∶1混合均匀,同聚四氟乙烯乳液调和后,压涂在石磨电极表面,制成Fe3O4/PANI复合阳极并测试其电化学性能。结果表明,改性后阳极表面细菌附着数量提高2倍多,有利于细菌附着。复合阳极抗极化性能明显提高,动力学活性明显增强,电流密度增加,最大功率密度提高到300 mW/m2。该复合阳极可望用于海泥电池的应用开发研究。     

阳离子聚丙烯酰胺对甜高梁混合汁中泥沙的絮凝效果研究

以阳离子型聚丙烯酰胺（CPAM）为澄清剂,对甜高粱混合汁中的泥沙进行絮凝处理。实验结果表明,CPAM对水样的絮凝效果良好,糖分损失很小,且在投加量为1．5mg／L时,絮凝效果达到最佳,絮凝率达到78．54％;CPAM最佳投药量处水样的吸光度值随着泥沙含量的升高而变大;甜高粱混合汁中含糖量越低,CPAM的除泥沙效果越好;沉降时间对CPAM的絮凝效果无明显影响;pH对CPAM除泥沙效果有较大的影响,且在pH为5时絮凝效果达到最佳,絮凝率达到85．86％。     

溶解氧对底泥中氨氮释放的影响

本次实验通过自制的柱状底泥模拟实验装置,研究了溶解氧对城市内河底泥中氨氮的转化规律。结果表明：（1）溶解氧是影响底泥中氮转化的主要因素,好氧环境条件下氨氮的转化率较厌氧条件下高;（2）不同的溶解氧浓度对氨氮的转化时间和程度不同,较高的溶解氧水平使氨氮发生转化的时间少于较低溶解氧水平的。基于本次研究结果,为治理城市内河污染提供科学依据,对保护内河水环境和生态系统有较大的实际意义。     

Analysis of adhesively-bonded T-joints by experimentation and cohesive zone models

Within the scope of adhesively-bonded joints, one of the joint types having industrial application is the T-joint, for example, in marine applications (joining of panels to the hull and connecting the glass-fibre composite hull with anti-flood panels) and aeronautical applications (wing panels, fuselage sections). This work aims to experimentally and numerically study, by cohesive zone models (CZM), the behaviour of T-joints under peel loads. The experimentally evaluated adhesives are the Araldite^® AV138 (high ultimate strength but brittle) and Araldite^® 2015 (less stress to failure but ductile and more flexible). The joint strength is evaluated with different L-shaped adherends’ thickness (t_P2). With the numerical analysis, the stress distributions, damage evolution and strength are studied. Additionally, a purely numerical study compared joints with or without adhesive filling at the curvature of the L-shaped adherends, and an extremely ductile adhesive (Sikaforce^® 7752) was additionally evaluated. The experimental tests validated the numerical results and showed that CZM is an accurate technique for the study of T-joints. It was also shown that the geometry of the L-parts, the presence of filler adhesive and the type of adhesive have a direct influence on the joint strength. In fact, in this particular joint configuration, the ductile but with lower ultimate strength adhesive Sikaforce^® 7752 clearly outperforms the two adhesives with higher mechanical properties but less ductility.     

Direct determination of a new mode-dependent cohesive zone model to simulate metal-to-metal adhesive joints

In this paper, a new mode-dependent cohesive zone model for the simulation of metal to metal adhesive joints is directly determined. Three consecutive steps have been taken into account for this end. First, double cantilever beam (DCB) and end-notched flexure (ENF) specimens are utilized for the direct experimental extraction of the traction-separation laws (TSLs) for adhesive bonded joints subjected to pure mode I and mode II, respectively. Next, the results are implemented to obtain the relative cohesive zone parameters for defining the simplified Park-Paulino-Roesler cohesive zone model (S-PPR CZM). Finally, mixed-mode characteristics parameters are derived for an arbitrary mode-mixity ratio based on pure mode TSLs. The model is further implemented in ABAQUS® commercial software to be verified against the experimental results of pure mode loadings which leads to the direct extraction of TSLs. The experiments conducted on the strength of single lap joint (SLJ) and scarf joint (SJ) specimens, commonly tested for mixed-mode loading, confirm the accuracy of the developed mixed-mode S-PPR model for different mode-mixity conditions.     

Mangrove Oyster (Crassostrea belcheri) as a Biomonitor Species for Bioavailability of Polycyclic Aromatic Hydrocarbons (PAHs) from Sediment of the West Coast of Peninsular Malaysia

ABSTRACT

Rapid industrialization and urbanization in the west coast of Peninsular Malaysia has caused increasing pollution particularly of petroleum and petroleum by-products. Surface sediment and mangrove oyster (Crassostrea belcheri) were collected from five mangrove ecosystems in the west coast of Peninsular Malaysia and investigated for bioavailability of polycyclic aromatic hydrocarbons (PAHs). Sampling locations were selected from both remote areas with few or no previous records of petroleum pollution such as Pulau Merambong and polluted areas that are under international attention such as Klang mangrove ecosystem. PAH fractions were obtained through soxhlet extraction and two-step column chromatography and the fractions were injected to gas chromatography-mass spectrometry (GC-MS) for analysis. The concentrations of PAHs ranged from 151 to 4973 ng g^?1 dw in the sediments, while from 309 to 2225 ng g^?1 dw in the oysters. When tested for diagnostic ratios, a predominance of pyrogenic source PAHs was detected in the sediments, whereas PAHs in the oysters had mixed petrogenic and pyrogenic sources. A significant correlation (p < 0.05) was found between high molecular weight (HMW) PAHs in the sediments and oysters and biota accumulation factors (BAFs) of PAHs were approaching or exceeding unity indicating the ability of mangrove oyster in bioaccumulation of PAHs. Overall, this study indicates that mangrove oyster (C. belcheri) can be used as a biomonitor species for PAHs in an aquatic environment.