On the Effect of Reduction and Ageing on the TWC Activity of Pt/Ce0.68Zr0.32O2 under Simulated Automotive Exhausts

The three-way activity under complex feed-streams of a series of Pt/Ce_0.68Zr_0.32O₂ catalysts, either fresh or submitted to different ageing treatments, both before and after reduction, has been studied and related to the species present on the catalysts in view of their characteristics and TPR behaviour.     

Cleaning a network with brushes

Following the decontamination metaphor for searching a graph, we introduce a cleaning process, which is related to both the chip-firing game and edge searching. Brushes (instead of chips) are placed on some vertices and, initially, all the edges are dirty. When a vertex is ‘fired’, each dirty incident edge is traversed by only one brush, cleaning it, but a brush is not allowed to traverse an already cleaned edge; consequently, a vertex may not need degree-many brushes to fire. The model presented is one where the edges are continually recontaminated, say by algae, so that cleaning is regarded as an on-going process. Ideally, the final configuration of the brushes, after all the edges have been cleaned, should be a viable starting configuration to clean the graph again. We show that this is possible with the least number of brushes if the vertices are fired sequentially but not if fired in parallel. We also present bounds for the least number of brushes required to clean graphs in general and some specific families of graphs.     

Poly(dihexadecyl-4H-cyclopenta[2,1-b:3,4-b′]dithiophene) film formation by cyclic voltammetry: dependence of the optical properties and morphology on the thickness

The voltammetric, morphologic and spectral properties of poly(dihexadecyl-4H-cyclopenta[2,1-b:3.4-b′]dithiophene), synthesised on ITO electrode in acetonitrile/dichloromethane mixed solvent by cyclic voltammetry, strongly depend on the film thickness. The polymerisation occurs through two successive steps: the electrode covering and a further growing of the film on the polymer coated electrode. The rate of the film growing is higher in acetonitrile-rich solvent and is a linear function of the monomer concentration during both the electrode covering and the subsequent growing step.     

Connection between strength of organic complex yarns and reinforced plastics based on them

Conclusions The evaluation of the quality of elementary filaments of poly-p-amidobenzimidazole from the breaking load of a complex yarn 500 mm long should be taken as unfortunate.Testing specimens 30 mm long can be recommended for evaluating the quality of untwisted complex PABI yarns.Increasing the strength of complex yarns 30 mm long leads to a proportional rise in the strength of an organoplastic. In testing specimens of organoplastic 500 mm long, increasing the strength of the complex yarns by 10% leads to only a 3–4% rise in the strength of the organoplastic.The strength of a microplastic is a natural quality criterion for twisted complex yarns.Translated from Khimicheskie Volokna, No. 1, pp. 27–29. January–February, 1989.     

工作在1341nm的LD纵向抽运腔倒空锁模Nd∶YAP激光器

报道了工作在1341 nm的激光二极管(LD)纵向抽运主被动锁模Nd∶YAP激光器。该激光器采用Nd∶YAP晶体作为增益介质,可饱和吸收体V3+∶YAG作为被动锁模器件,声光调制器作为主动锁模器件。在抽运能量50 mJ,抽运频率10 Hz的情况下获得了0.82 mJ的脉冲串输出。该脉冲串的半峰全宽为570 ns,每个脉冲间的间隔为7.7 ns,共包含约75个脉冲,单脉冲的平均能量为11μJ。采用电光晶体RbTiOPO4(RTP)作腔倒空,获得了能量为160μJ,脉宽为680 ps的单脉冲输出。采用InGaAs红外探测器测得光斑大小约为1.2 mm,激光传播因子M2约为1.5。     

超声波染色的动力学研究

以还原蓝RSN染棉的试验为例，对超声波染色动力学进行了研究。结果表明，超声波染色不但可以缩短染色时间，降低染色温度，大大提高染料的上染百分率，而且可以提高扩散系统，降低染料的活化能力。     

酵母菌发酵降低山楂汁有机酸含量的研究

山楂汁用酵母菌在溶氧25％～35％、20℃条件下进行84h发酵,采用高效液相色谱法和酸碱滴定法测定样品中的有机酸含量。结果表明,山楂汁中总酸为17.10g/L,其中柠檬酸含量为14.07g/L,苹果酸含量为1.24g/L。山楂汁发酵后总酸下降到3.52g/L,其中柠檬酸全部降解,苹果酸降解了86.6％,其它有机酸含量变化不大。柠檬酸降解速度在发酵的72h内与时间呈线性关系,苹果酸降解则发生在48～72h     

Investigations on the oxalic acid content of honey from oxalic acid treated and untreated bee colonies

Varroa destructor, an ectoparasitic mite, is one of the major pests of honeybees in many parts of the world. In order to keep bee colonies alive and productive, effective biological, biotechnical, or acaricidal control measures are necessary. Oxalic acid is one substance under discussion to replace synthetic acaricides (e.g. pyrethroids, organophosphates) to minimize the risk of residues in bee products. The application of oxalic acid based solutions (Bienenwohl or a self-prepared oxalic acid solution with sugar) to control Varroa destructor resulted in no relevant changes in the oxalic acid content of honey produced the following year, compared with honey samples from untreated colonies from the same location. The range of oxalic acid content in honey was 5–68 mg/kg in oxalic acid treated and 5–65 mg/kg in untreated colonies. The oxalic acid content of the honey was positively correlated with its electrical conductivity and thus with its original nectar or honeydew source.