可溶性汞化苯乙烯－丙烯酸甲酯共聚物的合成

用自由基溶液降合方法制备一系列苯乙烯－丙烯酸甲酯线型共聚物，用核磁共振测定了苯基在共聚物中的百分比，在该共聚物的四氢呋喃溶液中，用三氟乙酸汞在共聚物的苯环上进行亲电取代反应，得到可溶性汞化共聚物，由于这类泵化共的可溶于四氢呋喃，二氯甲烷等溶剂，用重沉淀法多次提纯，得到了纯度很高，溶解性较好的含重金属二价汞的共聚物，用红外光谱仪测定共聚物上的汞基团，用原子吸收定量测试共聚中的汞的百分聚代率，结果表明     

Development of pork fat reference material for OCPs BCR-CRM 430

Summary A pork fat sample was prepared and tested as candidate reference material for 10 organochlorine pesticides and metabolites (OCPs): hexachlorobenzene, -, - and -HCH, -heptachlor epoxide, dieldrin, endrin, p,p'-DDT, p,p'-TDE and p,p'-DDE. Preparation and testing for homogeneity and stability of the OCPs in the pork fat are discussed. The coefficient of variation of pesticide determinations carried out to test the between-ampoule homogeneity ranged from 2.4–5.8% and was found to be very similar to that for the analytical method (2.5–4.9%). This means that the homogeneity is very good. Stability data over 12 months do not show any trends that suggest lack of stability.     

Spectroscopy on two coupled superconducting flux qubits

We have performed spectroscopy measurements on two coupled flux qubits. The qubits are coupled inductively, which results in a sigma(z)(1)sigma(z)(2) interaction. By applying microwave radiation, we observe resonances due to transitions from the ground state to the first two excited states. From the position of these resonances as a function of the applied magnetic field, we observe the coupling of the qubits. The coupling strength agrees with calculations of the mutual inductance.     

Axisymmetric trawl cod-ends made from netting of a generalized mesh shape

The equations governing the geometry of axisymmetric trawl cod-endsmade from netting of meshes of a particular generalized structureare derived. From this, by suitable setting of the initial meshbar lengths, the equations governing the geometry of cod-endsthat are of importance to the fishing industry can be readilydeduced. It is assumed that arbitrary membrane forces act normalto the edges of the mesh elements, that there is no shear forceacting on the edge of a mesh element and that the twine thatmakes up the netting is extensible. The case where there isslackness in the mesh bars in the circumferential directionis dealt with and it is demonstrated how the finite structureof a knot can be taken into account. The case where the membraneforces arise solely as a result of and can be expressed by theappropriate components of the tensions in the mesh bars is alsoexamined and numerical solutions are found for a range of examples.     

Development of pork fat reference material for OCPs' BCR-CRM 430

Summary Certification of the content of endogenous organochlorine pesticides and their metabolites (OCPs) in pork fat is described and the certified values are presented. The OCPs include hexachlorobenzene (HCB), -, - and -HCH, -heptachlor epoxide (-hepo), dieldrin, endrin, p,p'-DDT, p,p'-TDE and p,p'-DDE. In a previous paper [1] the preparation of pork fat as a candidate reference material has been described as well as the investigation of its homogeneity and stability. This material, when certified, may serve for the verification of the results of determinations of the above organochlorine pesticides. This paper deals with the certification of these OCPs in pork fat.Part I see [1]     

Monte-Carlo calculation for the classical F.C.C. Heisenberg ferromagnet

The equilibrium properties of the classical f.c.c. Heisenberg ferromagnet are studied by Monte- Carlo techniques for small finite systems. Using the asymptotic dependence on the system size the results are extrapolated to the infinite system. The critical temperature is found to be T_c = 3.18 ± 0.02 and the critical exponents obtained are β = 0.33 ± 0.02, γ = 1.37 ± 0.04. The specific heat appears to have a cusp with α′_s = 0.1 ± 0.03 and α_s = 0.1 ± 0.1. Remarkable agreement is found with the finite-scaling theory.     

Preparation and testing of two milk powders as reference materials for organochlorine pesticides

Summary The production of two milk powder reference materials, a spiked one and one with natural OCP levels, as well as some results of homogeneity and stability studies are presented. The materials have been produced according to common procedures used in the Dutch dairy industry. A lot of partly decreamed milk was divided into two portions. To each portion butter fat was added, of which one batch had been spiked with nine pesticides to the desired content. Each portion was mixed, pasteurized, concentrated and spraydried. The milk powder thus produced was batchwise ampouled under argon. Stability and homogeneity were determined by analyzing the pesticides and the fat content. The mean coefficients of variation in the homogeneity tests were about 4.5% for the OCPs and about 1.5% for the fat content. The figures concerning the stability over 12 months do not show any trend suggesting a lack of stability.

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Herstellung und Prüfung von zwei Milchpulver-Referenzmaterialien für Organochlor-Pesticide