Highly hydrophobically modified polyelectrolytes: Field variables to control emulsion type

Highly hydrophobically modified (with n-dodecylamide chain) linear poly(acrylic acid)s (HHMPAAH) and poly(sodium acrylate)s (HHMPAANa) with various degrees of grafting (τ) were synthesized and used as emulsifiers of the n-dodecane/water system. The type of emulsion, oil in water (O/W) or water in oil (W/O), was investigated as a function of the polymer chemical structure (τ, salt or acid form of the copolymer) and aqueous phase electrolyte concentration (NaNO₃). Increasing τ and/or salt concentration was found to favor the formation of inverse emulsions. Direct liquid–liquid dispersions are more likely to form with poly(sodium acrylate)s than with poly(acrylic acid)s. Hence, field variables such as τ, pH and ionic strength are relevant parameters to control emulsion type. Moreover, a balanced polyelectrolyte neither soluble in oil nor in water was synthesized for the first time. With this original emulsifier, the dispersion type was found to change from O/W to W/O with polymer salting out. The work provides convenient model system for fundamental studies of polymer conformation at liquid–liquid interfaces. Received: 31 March 1998 Accepted: 30 April 1998     

The intermolecular potential function of Smith–Thakkar type for C60

The intermolecular potential function of Smith–Thakkar type for C₆₀ has been proposed, and its expression is as follows

The unit of u(r) is J/mol, r is the distance between two C₆₀ molecules center and the unit is nm. Some properties of C₆₀ in the gas and crystal have been studied using the interaction potential of Smith–Thakkar type, such as stability of C₆₀ crystals, virial coefficient and lattice dynamics.     

磷酸酯甜菜碱两性表面活性剂的合成与性能

磷酸酯甜菜碱从皮肤溶出的氨基酸量少,脱脂低,毒性和刺激性低,易降解,是一类性能优良两性表面活性剂[1,2]。它的合成大多以长链卤烷或胺为原料,成本较高。本文以高级脂肪醇、氯乙醇以及二甲胺为原料、P2O5为磷酸化剂,合成了C12H25OCH2CH(OOCCH3)CH2N+(CH3)2CH2CH2OP(O)(O )(OH)磷酸酯甜菜碱。测定了表面张力、泡沫性能、钙皂分散力及增溶能力。1　合成十二烷基缩水甘油醚(Ⅰ)[2]　在500ml三颈烧瓶中加入月桂醇0 2mol,正已烷200ml和四丁基溴化铵0 01mol;在室温和强烈搅拌下加入50%的NaOH水溶液48g,滴加环氧氯丙烷0 4mol后升…     

氮杂冠醚研究Ⅶ、双仲胺型氮杂冠醚对过渡金属离子的选择性萃取作用

合成了五种新型双仲胺型氦杂冠醚，研究了它们对过渡金属离子进行液—液萃取，并用原子吸收法测定其浓度。实验结果表明：这类冠醚对Ａｇ￣＋、Ｐｄ￣（２＋）、和Ｐｔ￣（４＋）等贵金属离子有较强的选择配位性能，对选择性分离这些金属离子有重要的意义。     

Study on the nature of interaction of BrCl with HF,H2O,and NH3

By counterpoise‐corrected optimization method, the interactions of BrCl with the first‐row hydrides (HF, H₂O, NH₃) have been investigated at the MP2/6–311++G(3d,3p) level. To understand that the X? Br‐type (X = F, O, N) structure is more stable than the corresponding hydrogen‐bonded structure in these complexes, the electronic properties were also investigated. Symmetry‐adapted perturbation theory (SAPT) analysis has been carried out to understand the nature of the weak hydrogen bond and X? Br‐type interactions. On the other hand, for the weak hydrogen‐bonded complexes and the X? Br‐type complexes charges transfer is well correlated with the total induction energies. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Improved synthesis of a [4.4]-spirolactam β-turn mimetic as surrogate of the didemnin side chain dipeptide Pro-N-Me-d-Leu

An efficient synthesis of [4.4]-spirolactam restricted derivatives of the didemnin side chain dipeptide l-Pro-N-Me-d-Leu is described. This methodology involves: (a) peptide coupling of N-Boc-2-allylproline with d-Leu-OBn; (b) OsO₄/NaIO₄ mediated allyl oxidation and intramolecular cyclization to the corresponding cyclic hemiaminals; and (c) NaBH₄ mediated reduction of an intermediate N-acyliminium ion. This synthetic strategy gave significant better results than the previously reported strategies for the synthesis of [4.4]-spirolactam β-turn mimetics.     

Superoxes,high temperature universal phases in (GC)2

Most of the common classes of organic compounds chromatograph normally on Superoxes. There is no tailing or adverse effect from excessively different activity different activity coefficients. Superoxes are therefore universal phases for gas chromatography. This is also expressed by a wide useful temperature range from ～50° to ～300°. High MW Superox-4 has a MAOT about 20° higher than the lower MW Superox-0.1. Several applications illustrating the versatility of Superox phases in (GC)² are presented.     

有限型的首次返回例外集的测度和维数北大核心CSCD

设M=(m_(ij))是一个b×b阶矩阵且m_(ij)∈{0,1},∑_(M)是矩阵M=(m_(ij))诱导产生的有限型,σ是其上左推移算子.本文主要研究的是有限型动力系统(∑_(M),σ)上的首次返回速度问题.令τ_(k)(x)是点x∈∑_(M)首次返回到包含x的k阶柱集时间,且E_(α,β)={x∈∑_(M):lim inf_(k→∞)(logτ_(k)(x))/k=α,lim sup_(k→∞)(logτ_(k)(x))/k=β}.我们证明了:当M是不可约矩阵时,对任意0≤α≤β≤+∞,集合E_(α,β)的Markov测度要么等于0要么等于1并且具有满的Hausdorff维数.     

含有陡峭势阱和凹凸非线性项的Kirchhoff型问题的多重正解*

在这篇文章中, 作者研究涉及凹凸非线性项的Kirchhoff型问题-(a + b ∫R3|▽u|²dx) Δu + λV (x)u = μf(x)|u|^q?2u + |u|^p?2u, x ∈ R³,u ∈ H¹(R³),其中a,b > 0 是常数, λ, μ > 0 是参数, 1 < q < 2, 4 < p < 6 且 V 是一个非负连续位势. 在f(x) 和 V 的合适条件下,此问题正解的存在性和集中性能够通过Nehari 流形和Ekeland 变分原理得到.     

Existence and asymptotic results for a system of integro-partial differential equations

A non-Fourier phase field model is considered. A global existence result for a Dirichlet, or generalized Neumann, initial-boundary value problem is obtained, followed by a discussion of the regularity and asymptotic properties of solutions ast.This research was supported in part by the National Science Foundation under Grant DMS 91-11794 and in part by the Italian M.U.R.S.T. project Problemi non lineari...Part of this author's work was done while visiting Ohio University.