常用防腐剂对西式火腿肠主要腐败菌抑菌作用的研究

目的:测定常用食品防腐剂对西式火腿主要腐败菌的抑制作用。方法:采用微量稀释法测定不同防腐剂对木糖葡萄球菌、地衣芽孢杆菌和雷氏普罗威登菌的最小抑菌浓度(MIC)。结果:对于木糖葡萄球菌(G+),抑菌效果最好的是Nisin和ε-聚赖氨酸,MIC均为12.5μg/mL;对于地衣芽孢杆菌(G+),抑菌效果最好的是D-异抗坏血酸钠、丙酸钙、柠檬酸和柠檬醛,MIC均为12.5μg/mL;对于雷氏普罗威登菌(G-),抑菌效果最好的是过氧化氢和柠檬酸,MIC均为25μg/mL。结论:不同防腐剂对西式火腿肠主要腐败菌的抑制效果有所差异,应复配使用。     

浅谈乙炔提浓装置中聚合物含量的控制

通过对天然气部分氧化制乙炔工艺中提浓装置聚合物形成机理的分析,找出引起该装置聚合物升高的原因,提出降低聚合物的方法,实现了该装置在高负荷长周期、安全、稳定运行。     

高浓度聚合物驱提高采收率方法实验研究

为探索一种新的提高原油采收率的方法,在外形尺寸为4.5 cm×4.5 cm×30 cm、气测渗透率0.9~1.0μm2、变异系数为0.72的二维纵向非均质人造岩心上,模拟大庆油田油藏流体性质及温度条件,研究了高浓度聚合物(HPAM)驱注入时机、聚合物相对分子质量、聚合物段塞体积及段塞组合对驱油效果的影响。通过注入大分子量、高浓度聚合物,结合合理的注入方式,在化学剂成本与三元复合驱相当的情况下,采收率比水驱提高20个百分点以上,接近或超过三元复合驱的水平。实验表明,采用高浓度聚合物驱油是一种较好的提高原油采收率的方法。     

Experimental and theoretical study of density jumps on smooth and rough beds

Hydraulic jumps in density currents are technically referred to density jumps. These jumps significantly influence the dynamic and quality characteristics of the gravity currents. The density jump is studied theoretically and experimentally in this study by considering the bed roughness. Experiments were performed in a rectangular laboratory flume (0.4 m width; 0.9 m depth; 8.3 m length). Four rough beds comprised of closely packed gravel particles glued onto the horizontal part of the bed were examined. For both smooth and rough beds, a simple relationship was obtained for estimating the conjugate depth ratio as a function of the relative roughness and the upstream densimetric Froude number. The conjugate depth ratio was found to decrease with increasing relative roughness. The results also indicated that, if the entrainment ratio is specified, the minimum value of the upstream densimetric Froude number increases with increasing relative bed roughness. An equation for calculating the maximum possible value of the relative roughness was also determined. The spatial development of the density current for smooth beds was analysed in both super‐critical and sub‐critical flow regimes. Good similarity collapses of velocity and concentration profiles were obtained for the super‐critical section just upstream of the jump. The concentration distributions located just downstream of the jump, however, exhibited a large scattering of measured data, especially near the bed. It was found that this scattering decreases with the distance from the end of the jump. The results of the experimental runs also indicated that, at a distance about nine times the post‐jump current thickness from the end of the jump, the non‐dimensional vertical profile of mean velocity has a shape similar to that at the pre‐jump section. A new reliable relationship was also proposed for calculating the local velocity inside both the wall and jet regions.     

基于粒子群优化和支持向量机的花粉浓度预测模型

为了提高花粉浓度预报的准确率，解决现有花粉浓度预报准确率不高的问题，提出了一种基于粒子群优化（PSO）算法和支持向量机（SVM）的花粉浓度预报模型。首先，综合考虑气温、气温日较差、相对湿度、降水量、风力、日照时数等多种气象要素，选择与花粉浓度相关性较强的气象要素构成特征向量；其次，利用特征向量与花粉浓度数据建立SVM预测模型，并使用PSO算法找出最优参数；然后利用最优参数优化花粉浓度预测模型；最后，使用优化后的模型对花粉未来24 h浓度进行预测，并与未优化的SVM、多元线性回归法（MLR）、反向神经网络（BPNN）作对比。此外使用优化后的模型对某市南郊观象台和密云两个站点进行逐日花粉浓度预测。实验结果表明，相比其他预报方法，所提方法能有效提高花粉浓度未来24 h预测精度，并具有较高的泛化能力。     

高氯离子废水中低COD测定方法的探讨

对国标法重铬酸钾法、低浓度氧化剂法、反应器消解法3种方法测定高氯离子废水中低浓度有机物进行比较,并进行精密度、准确度分析。结果表明,低浓度氧化剂法、反应器消解法测定结果准确性高,重现性好,是实验室及污水处理厂等企业测定高氯离子废水中CODCr浓度的可行方法。     

Synthesis of biodegradable poly(trans-4-hydroxy-N-benzyloxycarbonyl-l-proline)-block-poly(ε-caprolactone) copolymers and micellar characterizations

A series of novel types of diblock poly(trans-4-hydroxy-N-benzyloxycarbonyl-l-proline)-block-poly(ε-caprolactone) (PHpr10-b-PCL) copolymers were synthesized by ring-opening polymerization from macroinitiator poly(trans-4-hydroxy-N-benzyloxycarbonyl-l-proline) (PHpr10) and ε-caprolactone (ε-CL) in the presence of organocatalyst dl-lactic acid (dl-LA). The M_n of the copolymers increased from 3370 to 19,040 g mol⁻¹ with the molar ratio (10-100) of ε-CL to PHpr10. These products were characterized by differential scanning calorimetry (DSC), ¹H NMR, and gel permeation chromatography. According to DSC, the glass-transition temperature (T_g) of the diblock copolymers depend on the molar ratio of monomer/initiator that were added. The hydrolytic degradation behavior of PHpr-b-PCLs was evaluated from weight-loss measurements and the change of M_n and M_w/M_n. With higher PCL contents resulted in a slower weight loss, while having a higher molecular weight loss percentage. Their micellar characteristics in an aqueous phase were investigated by fluorescence spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (CMCs) in the range of 1.33-4.22 mg L⁻¹. The micelles exhibited a spindly shape and showed a narrow monodisperse size distribution. The obtained micelles have a relatively high drug-loading of about 26% when the feed weight ratio of amitriptyline hydrochloride (AM) to polymer was 1/1. An increase of molecular weight and hydrophobic components in copolymers produced a higher CMC value and greater loading efficiencies were observed.     

永定新河河口潮流动力及泥沙特征初步分析

依据永定新河河口１９９７年潮汐观测资料及河道１９９０～１９９７年潮汐观测资料，通过实测资料的整理分析，初步揭示了永定新河河口潮流动力及泥沙特征，为河道的治理规划提供了科学的依据。     

就地γ谱仪测量某坑道内222Rn-220Rn子体剂量比

为了解某坑道内222Rn-220Rn子体α潜能浓度比及剂量比的变化,使用就地HPGeγ谱仪分别在坑道内密闭环境和通风两种状态下进行测量,使用相对效率法和α潜能浓度法对测量结果进行分析。结果表明:测量期间,密闭坑道内222Rn-220Rn子体α潜能浓度比平均为3.6,子体剂量比平均为10.8;通风8小时内,坑道中222Rn-220Rn子体α潜能浓度比平均为1.2,子体剂量比平均为3.6;通风约14小时后,坑道内222Rn-220Rn子体α潜能浓度比平均为0.2,子体剂量比平均为0.6,220Rn子体剂量占222Rn-220Rn子体总剂量份额的62%。使用就地HPGeγ谱仪可快速、连续得到坑道内222Rn-220Rn子体α潜能浓度比及剂量比,在未来的222Rn-220Rn剂量研究中有着广阔的应用前景。     

微波等离子体化学气相沉积金刚石光谱分析

采用等离子体光谱分析微波等离子体化学气相(MPCVD)沉积金刚石过程中基团的空间分布及甲烷浓度变化时基团浓度的变化情况.实验过程中分别测量了氢原子的Hα(656.19 nm)、Hβ(486.71 nm)和Hγ(434.56 nm)谱线,以及基团CH(431.31 nm)、C2(515.63 nm)谱线.结果表明:氢原子和基团CH、C2的浓度沿等离子体柱的径向先增加再减小.随着甲烷浓度逐步增加,氢原子及基团CH、C2的浓度相应增加,其中C2基团所受影响最大.