Effect of cocatalysts on the character of a constrained geometry catalyst

A constrained geometry catalyst (CGC) precursor, Me₂Si(Flu)(N-t-Bu)ZrX₂ (X = Cl or NMe₂), behaved as a single site catalyst with methylaluminoxane (MAO) as cocatalyst, while it developed much diversified catalytic species with AIR₃/Ph₃CB(C₆F₅)₄ as cocatalyst. The catalytic performance was not affected if X is Cl or NMe₂.     

On the semigroup generated by the renormalized Nelson Hamiltonian

We consider the renormalized Nelson model at a fixed total momentum P: $H_{\mathrm{ren}}(P)$; the Hamiltonian $H_{\mathrm{ren}}(P)$ is defined through an infinite energy renormalization. We prove that $e^{?\beta H_{\mathrm{ren}}(P)}$ is positivity improving for all $P\in {\mathbb{R}}^3$ and $\beta >0$ in the Fock representation.     

Invariance of the White Noise for KdV

We prove the invariance of the mean 0 white noise for the periodic KdV. First, we show that the Besov-type space [^(b)]^s_p,￥{\widehat{b}^s_{p,\infty}} , sp < −1, contains the support of the white noise. Then, we prove local well-posedness in [^(b)]^s_{p, ￥}{\widehat{b}^s_{p, \infty}} for p = 2 + , s = -\frac12+{s = -\frac{1}{2}+} such that sp < −1. In establishing the local well-posedness, we use a variant of the Bourgain spaces with a weight. This provides an analytical proof of the invariance of the white noise under the flow of KdV obtained in Quastel-Valko [21].     

2α + t Cluster Structure in 11B

Structures of excited states in ¹¹B are investigated with a method of β – γ constraint antisymmetrized molecular dynamics in combination with the generator coordinate method. Various cluster structures are suggested in excited states. For negative-parity states, we suggest a band with a 2α + t cluster structure. This band starts from the ${3/2^{-}_{3}}$ state and can correspond to the experimental band observed recently. We find that the feature of the ${3/2^{-}_{3}}$ is quite similar to the ${0^{+}_{2}}$ state in ¹²C.     

Crosslinking polymerization leading to interpenetrating polymer network formation. II. Polyaddition crosslinking reactions of poly(methyl methacrylate‐co‐2‐methacryloyloxyethyl isocyanate) with various diols

As part of our continuing studies concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article explores the polyaddition crosslinking reactions of multifunctional poly(methyl methacrylate‐co‐2‐methacryloyloxyethyl isocyanate) [poly(MMA‐co‐MOI)] [MMA/MOI = 90/10] with various diols leading to PU network formation. Thus, the equimolar polyaddition crosslinking reactions of poly(MMA‐co‐MOI) with ethylene glycol (EG), 1,6‐hexane diol, and 1,10‐decane diol (DD) were carried out in N‐methyl pyrrolidone at a 0.25 mol/L isocyanate group concentration at 80 °C. The second‐order rate constants decreased from EG to DD. The deviation of the actual gel point from the theoretical one was smaller from EG to DD. The intrinsic viscosity of resulting prepolymer demonstrated almost no variation with progressing polymerization for the EG system, whereas it gradually increased with conversion for the DD system. Close to the gel point conversion it increased rather drastically for both systems. The swelling ratio of resulting gel was higher from EG to DD. These are discussed mechanistically in terms of the significant occurrence of intramolecular cyclization and intramolecular crosslinking reactions leading to shrinkage of the molecular size. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3243–3248, 2003     

Desulfurizative Titanation of Organosulfur Compounds

Desulfurizative titanation of allylic sulfides and thioacetals, and the subsequent reactions of resulting organotitanium species were studied.     

RNA Preparation of Saccharomyces cerevisiae Using the Digestion Method may Give Misleading Results

Zymolyase (lyticase) is used for cell wall digestion in yeast experiments and is needed for incubation processes under moderate experimental conditions. This has been thought to cause unfavorable effects, and many researchers are aware that the enzyme method is unsuitable for RNA preparation following several reports of stress responses to the enzyme process. However, RNA preparation with enzyme digestion continues to be used. This may be because there have been insufficient data directly comparing RNA preparation conditions with previous studies. We investigated the influence of enzyme processes in RNA preparation using a DNA microarray, and compared superoxide dismutase (SOD) activities with a non-treated control and the results of previous research. Gene expressions were commonly changed by enzyme processes, and SOD activities increased only during short-term incubation. Meanwhile, both SOD gene expressions and SOD activity during RNA preparation indicated different results than gained under conditions of long-term incubation. These results suggest that zymolyase treatment surely influences gene expressions and enzyme activity, although the effect assumed by previous studies is not necessarily in agreement with that of RNA preparation.