Sulfur-Containing Vinyl Monomers. XV. Kinetic Study of Radical Polymerization of Vinyl Mercaptobenzothiazole and Its Copolymerization

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (R_p) was found to be expressed by the rate equation: R_p = k[AIBN]^0.5 [VMBT]^1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.     

THERMAL NEUTRON ACTIVATION ANALYSIS—AN IMPORTANT ANALYTICAL TOOL

ABSTRACT

This review is intended to present an introduction to the use of thermal neutron activation analysis (TNAA) as an analytical technique for the determination of elements in almost all kinds of matrices. This method of analysis is generally multi-element and experimental conditions can be designed to be nondestructive to the sample. This review will focus on thermal neutron activation as this technique allows determination of approximately two-thirds of the elements on the periodic chart. There are also more and wider spread facilities in the United States that offer these services. The available facilities are located across the United States and are generally accessible to everyone. The review will also detail the advantages and disadvantages of TNAA compared to other common spectroscopic methods. An outline of the general procedure for performing the analysis of the elements using activation analysis is presented to emphasize the ease of using this technique. The outline is divided into sections that give the general procedure, how to choose the correct nuclear reaction and reaction product, and the main sources of errors that can affect the results of the study. These sources of error are subdivided into general types of errors. The general types of errors are divided into those related to pre-chemistry, problems associated with the irradiation of the samples, errors associated with the use of nuclear constants (cross sections, half-lives, transition probabilities, etc.), the choice of the correct reaction and reaction product, and those associated with the counting of the irradiated samples. The general theory of activation analysis is presented and summarizes the derivation of the equations used and the development of the comparator method of analysis. The comparator method is used to simplify the method by irradiating samples along with standards. This reduces the need for using the nuclear constants and thus reducing errors. The use of radiochemical separations to isolate analytes of choice from the radioactive matrix is also described. Some current literature is also included to give a feel for current applications of the use of thermal neutron activation analyses. The summary also describes some of the different matrices that have been used for analyses.     

Consistency of general bootstrap methods for degenerate -type and -type statistics

We provide general results on the consistency of certain bootstrap methods applied to degree-2 degenerate statistics of U-type and V-type. While it follows from well known results that the original statistic converges in distribution to a weighted sum of centred chi-squared random variables, we use a coupling idea of Dehling and Mikosch to show that the bootstrap counterpart converges to the same distribution. The result is applied to a goodness-of-fit test based on the empirical characteristic function.     

Cascade synthesis of 3-aza-bicyclo[3.1.0]hex-2-ene derivatives from N-allyl enamines

An efficient iodine-mediated cascade synthesis of 3-aza-bicyclo[3.1.0]hex-2-ene derivatives from easily prepared N-allyl enamines has been developed. The advantages of the reaction include facilitative preparation of substrates 3a–t, good functional group tolerance and transition-metal-free conditions.     

Comparing confidence limits for short-run process incapability index Cpp

Process incapability index C_pp has been proposed in the manufacturing industry to assess process incapability. In industries it is sometimes unable to get large samples, and, hence, the CAN (consistent and asymptotically normal) property of the unbiased estimator for C_pp is missing. In this paper, six bootstrap methods are applied to construct upper confidence bounds (UCBs) of C_pp for short-urn production processes where sample size is small; standard bootstrap (SB), Bayesian bootstrap (BB), bootstrap pivotal (BP), percentile bootstrap (PB), bias-corrected percentile bootstrap (BCPB), and bias-corrected and accelerated bootstrap (BCa). A numerical simulation study is conducted in order to demonstrate the performance of the six various estimation methods. We further investigate the accuracy of the six methods by calculating the relative coverage (defined as the ratio of coverage percentage to average length of UCB). Detailed discussions of simulation results for seven short-run processes are presented. Finally, one real example from Ford Company’s Windsor Casting Plant is used to illustrate the six interval estimation methods.     

托卡马克能量约束及自举电流效应的初步考虑

基于Lee等人的离子温度梯度模导致的反常热能输运系数,本文研究了辅助加热托卡马克等离子体的能量约束行为,并对自举电流的效应作了初步考虑。结果表明,计算得到的能量约束时间随等离子体电流I_p和托卡马克大半径R增大而增长,随注入功率P_t、环向场B_t以及等离子体小半径α的增大而缩短。这些结果与Kaye-Goldston的经验约束定标具有相同的趋势。自举电流的存在总是导致能量约束时间的增加,当自举电流与总电流的比值γ较小时,能量约束时间的增加率约为γ/2。此外,自举电流将造成锯齿反转半径的减小。     

Modelling and forecasting mortality in Spain

Experience shows that static life tables overestimate death probabilities. As a consequence of this overestimation the premiums for annuities, pensions and life insurance are not what they actually should be, with negative effects for insurance companies or policy-holders. The reason for this overestimation is that static life tables, through being computed for a specific period of time, cannot take into account the decreasing mortality trend over time. Dynamic life tables overcome this problem by incorporating the influence of the calendar when graduating mortality. Recent papers on the topic look for the development of new methods to deal with this dynamism.     

The uncertainties about the relationships risk–return–volatility in the Spanish stock market

The relationships between the market risk premium, its conditional variance and the risk-free rate in the Spanish stock market are studied in this paper. Using daily data, the above mentioned relations are analyzed by quasi maximum likelihood for an EGARCH-M(1,1) model with normal innovations and by nonparametric maximum likelihood for a semiparametric EGARCH-M(1,1) model with arbitrarily distributed innovations. It is worth mentioning that the conclusions differ from one model to the other.     

Bootstrapping generalizedU-processes andV-processes and their applications in projection pursuit

In this paper, we study bootstrap approximation for generalizedU-processes (GUP) indexed by a class of functions. Under mild conditions we obtain that the asymptotic distributions of bootstrapping generalizedU-processes (BGUP) are the same as those of GUP almost surely. As a result, the asymptotic properties of bootstrap approximation for PP generalizedU-processes (BPPGUP) are obtained. In addition we have derived bootstrap approximation for generalizedV-processes (GVP). Thus, we can use BGUP or bootstrapping GVP (BGVP) to simulate GUP and GVP.This project is supported by the National Natural Science Foundation of China and the Science Foundation of Educational Committee of Guizhou.     

Weber Correspondence Analysis: The One-Dimensional Case

When designing programs or software for the implementation of Monte Carlo (MC) hypothesis tests, we can save computation time by using sequential stopping boundaries. Such boundaries imply stopping resampling after relatively few replications if the early replications indicate a very large or a very small p value. We study a truncated sequential probability ratio test (SPRT) boundary and provide a tractable algorithm to implement it. We review two properties desired of any MC p value, the validity of the p value and a small resampling risk, where resampling risk is the probability that the accept/reject decision will be different than the decision from complete enumeration. We show how the algorithm can be used to calculate a valid p value and confidence intervals for any truncated SPRT boundary. We show that a class of SPRT boundaries is minimax with respect to resampling risk and recommend a truncated version of boundaries in that class by comparing their resampling risk (RR) to the RR of fixed boundaries with the same maximum resample size. We study the lack of validity of some simple estimators of p values and offer a new, simple valid p value for the recommended truncated SPRT boundary. We explore the use of these methods in a practical example and provide the MChtest R package to perform the methods.