铅酸蓄电池极板中活性物质含量的测定

采用碘量法和配位滴定法分别测定铅酸蓄电池正、负极板中活性物质PbO2、PbO的含量,借此判断电池是否合格。此方法步骤简单,易于判断终点。     

Mechanical properties of freely suspended semiconducting graphene-like layers based on MoS2

We fabricate freely suspended nanosheets of molybdenum disulphide (MoS₂) which are characterized by quantitative optical microscopy and high-resolution friction force microscopy. We study the elastic deformation of freely suspended nanosheets of MoS₂ using an atomic force microscope. The Young''s modulus and the initial pre-tension of the nanosheets are determined by performing a nanoscopic version of a bending test experiment. MoS₂ sheets show high elasticity and an extremely high Young''s modulus (0.30 TPa, 50% larger than steel). These results make them a potential alternative to graphene in applications requiring flexible semiconductor materials.PACS, 73.61.Le, other inorganic semiconductors, 68.65.Ac, multilayers, 62.20.de, elastic moduli, 81.40.Jj, elasticity and anelasticity, stress-strain relations.     

化妆品生产中抗性环境菌株的研究

对化妆品生产中的环境菌株进行菌种分离,得到了一株伯克霍尔德属类的环境菌。通过抑菌圈和挑战实验证明,该菌对以双咪唑烷基脲为主要功能成分的防腐体系具有抗性;另外通过去活性物挑战实验,证明活性物对抗性环境菌在产品中爆发性生长起关键作用。通过以上数据,更深入的了解产品微生物污染的来源和机制,对有效预防化妆品生产微生物污染,同时设计更有效的防腐体系提供依据。     

次氯酸钠对德尔卑沙门氏菌生物被膜的抑制作用及机制

目的：为控制德尔卑沙门氏菌（Salmonella Derby）在食品加工过程中的污染，研究不同体积分数次氯酸钠对S. Derby生物被膜的抑制作用及其机制。方法：采用结晶紫染色法和平板菌落计数法观察次氯酸钠对生物被膜的抑制和清除效果，进一步观察不同体积分数次氯酸钠作用下沙门氏菌泳动能力和生物被膜内细胞的代谢活性、胞外聚合物含量和微观形态的变化规律。结果：次氯酸钠的最小抑菌浓度（minimum inhibitory concentration，MIC）为0.08%（体积分数，下同），亚MIC（0.04%、0.02%、0.01%）的次氯酸钠可以抑制S. Derby生物被膜的形成，对成熟生物被膜也有一定的清除效果，且不同亚MIC次氯酸钠的作用效果差异显著（P＜0.05）；不同体积分数次氯酸钠处理能降低生物被膜内细胞代谢活性，抑制胞外多糖的合成，且不同体积分数次氯酸钠的作用效果差异显著（P＜0.05）。激光共聚焦扫描显微镜结果显示，与对照组相比，次氯酸钠处理使得生物被膜厚度减小、活菌数减少、死菌数增多、细菌由聚集状态变为分散状态。结论：不同体积分数次氯酸钠对S. Derby生物被膜的形成有明显的抑制作用，这一作用与干扰细菌生长、生物被膜内细胞代谢活性和胞外多糖的合成有关。     

供热站主厂房工艺布置和结构分析

由于工艺布置和建筑造型的需要,供热站主厂房设计变得相当复杂与繁琐,文中通过工程实例对其进行分析,表明工艺之间相互配合、在充分利用平面和竖向空间基础上、能够达到工艺顺畅和结构抗震性能良好的统一。     

Uptake of Radionuclides onto Suspended Particulate Matter in Coastal Water

Distribution coefficients K _ds of several radionuclides on suspended particulate matter (SPM) have been determined with laboratory batch experiments using samples collected in the Kinki district, Japan. Most SPM in coastal water was retained on the initial filter of four sequential filtering stages (20, 5, 1 and 0.45 μm pore size), maximum K _d also being found for the SPM retained in this first stage. When the filtrations were not performed in series, however, but were conducted from the same tracer solution in parallel, the K _d values were identical for the smaller filter sizes (5, 1 and 0.45 μm) and were greater, by ca. 150% than those derived from the 20 μm filter. The degree of association of the radionuclides with SPM was ⁸⁵Sr<¹³⁷Cs<⁶⁵Zn<⁵⁴Mn<⁶⁰Co. The particulate radioactivity fraction of the SPM in coastal water was estimated at most 0.1 for radionuclides with K _d of ca. 5 X 10⁴ ml/g, i.e. which are highly associated with the SPM (2 mg/l). The scavenging effect by SPM seemed to be, however, considerable, the settling velocity being estimated at ca. 25 cm/day for particles of the Stoke's diameter of 30 μm.     

涡流技术在降低水煤浆燃烧产物中有毒物质的应用

为了在试验台和半工业性试验时,确定水煤浆燃烧过程中释放的气体中有害气体的质量浓度,采用涡流燃烧工艺,对水煤浆燃烧时释放气体的成分进行了试验研究。结果表明:采用涡流燃烧工艺,由于化学不完全燃烧减少,气体释放物中的CO含量随燃烧室温度提高而降低,NOx含量甚至低于标准值。这主要是因为涡流燃烧室燃料燃烧温度相对不高;喷射水煤浆的颗粒在燃烧层停留时间长,可以完全燃烧。该水煤浆燃烧工艺可以减少有害物质向大气的释放。     

Adaptive back-stepping tracking control for rotor shaft tilting of active magnetically suspended momentum wheel

Two-dimensional gyroscopic torque can be produced by tilting the rotor shaft of the active magnetically suspended momentum wheel. The nonlinear magnetic torque is analyzed and then an adaptive back-stepping tracking method is proposed to deal with the nonlinearity and uncertainty. The nonlinearity of magnetic torque is represented as bounded unknown uncertainty stiffness, and an adaptive law is proposed to estimate the stiffness. Combined with back-stepping method, the proposed method can deal with the uncertainty. This method is designed by Lyapunov stability theory to ensure the stability, and its effectiveness is validated by simulations and experiments. These results indicate that this method can realize higher tracking precision and faster tracking velocity than the conventional cross feedback method to provide high precision and wide bandwidth outputting torque.     

对竹园第-污水处理厂污泥产率的分析

根据上海市竹园第一污水处理厂的运行数据，研究了该厂的污泥产率。结果表明竹园第一污水处理厂每万吨水产泥率的变化范围为0．38—1．44tSS／万M2；剩余污泥的表观产率系数（Lobs）和合成产率系数（y）分别为0．56和0．58kgVSS／kgBOD，均在正常范围以内；衰减系数（虬）为0．006d-1；惰性ss产泥率的变化范围为0．20～0．50tSS／万M2。