一种新型阻燃抗熔滴共聚酯的合成及表征

双酚A与碳酸乙烯酯反应得到改性单体双(羟乙基)双酚A(BHEEB),BHEEB与对苯二甲酸、乙二醇及阻燃剂[(6-氧代-6H-二苯并[c,e][1,2]氧磷杂己环-6-基)甲基]丁二酸(DDP)通过无规共聚合成了一种新型阻燃共聚酯PBPET.用1H-NMR、ICP-AES对共聚酯的结构进行了表征,用热重分析(TGA)、氧指数(LOI)测定、垂直燃烧测试等对共聚酯的热稳定性、阻燃性和熔滴行为进行了研究.结果表明,BHEEB可以提高共聚酯的热稳定性,含5 mol%BHEEB与4.8 mol%DDP的共聚酯P4.8B5PET,其TGA测试中600℃下氮气氛残炭(wt6R00)可达18.0%.燃烧测试表明,P4.8B5PET的LOI值可达37.0,垂直燃烧达V-0级,并且改性单体BHEEB的引入还能有效地改善聚酯燃烧时的熔滴行为.     

Some constructions of biharmonic maps and Chen’s conjecture on biharmonic hypersurfaces

We give several construction methods and use them to produce many examples of proper biharmonic maps including biharmonic tori of any dimension in Euclidean spheres (Theorem 2.2, Corollary 2.3, Corollary 2.4 and Corollary 2.6), biharmonic maps between spheres (Theorem 2.9) and into spheres (Theorem 2.10) via orthogonal multiplications and eigenmaps. We also study biharmonic graphs of maps, derive the equation for a function whose graph is a biharmonic hypersurface in a Euclidean space, and give an equivalent formulation of Chen’s conjecture on biharmonic hypersurfaces by using the biharmonic graph equation (Theorem 4.1) which paves a way for the analytic study of the conjecture.     

Synthesis and crystal structures of two three-dimensional vanadium polyoxoanion-bridged macrocyclic metal complexes

The reactions of transition metal macrocyclic complexes [ML](ClO₄)₂ (L?=?5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, M?=?Ni, Cu) with NH₄VO₃ under hydrothermal conditions gave two coordination polymers, namely [NiL]₂[V₆O₁₇] and [CuL]₂[V₆O₁₇]. Single-crystal X-ray diffraction analyses indicated that the central Ni(II)/Cu(II) atom displays a distorted six-coordinate octahedral coordination geometry by coordination with four nitrogen atoms of L, and two oxygen atoms of [VO₄] tetrahedrons. Compounds [NiL]₂[V₆O₁₇] and [CuL]₂[V₆O₁₇] show three-dimensional structures, which are constructed through the connections of dodecanuclear [V₁₂O₃₂]^4? rings with [NiL]²⁺ in [NiL]₂[V₆O₁₇], and [V₈O₂₂] _n ^4n? chains with [CuL]²⁺ in [CuL]₂[V₆O₁₇], respectively, generating one-dimensional channels.     

Synthesis of Duloxetine Intermediate (S)-3-Chloro-1-(2-thienyl)-1-propanol with Liquid-Core Immobilized Candida pseudotropicalis 104

(S) -3-Chloro-1-(2-thienyl)-1-propanol was synthesized by the asymmetric reduction of 3-chloro-1-(2-thienyl)propanone with liquid-core immobilized Candida pseudotropicalis 104. The optimum time was 28?h for the re-cultivation of immobilized cells. The optimum film solvent for the liquid-core capsule was 0.3?% chitosan (M _w 1.0?×?10⁵). Conversion decreased with the increase of the liquid-core capsule diameter and with the addition of more substrates at the same reduction time. The immobilized cells show good reduction ability in a potassium phosphate buffer (pH 6.6~7.2). The material outside the spread speed of immobilized cells was not restricted when the shaking speed was higher than 160?r/min. Liquid-core immobilized cells can be reused 11 times. Compared with the batch reduction, the continuous reduction of 3-chloro-1-(2-thienyl)propanone in the membrane reactor with liquid-core immobilized cells as catalyst can relieve the inhibition from a high-concentration substrate. Conversion and enantiometric excess of (S)-3-chloro-1-(2-thienyl)-1-propanol reached 100?% and >99?% in a continuous reduction of 12?g/L 3-chloro-1-(2-thienyl)propanone for 10?days.     

About a nonadditivity of energy and entropy

The mathematical expression of nonadditivity X(1 ?? 2) = X(1) + X(2) + ??X(1)X(2) has been frequently used for the development of statistical physics for nonadditive system, where X is entropy or energy, and ?? is hoped to be a parameter characterising the nonadditive property of the composite system (1 ?? 2). Here we show that this relationship cannot hold exactly. In general, ?? in this expression inevitably depends on how a given system with constant X(1 ?? 2) is divided into subsystems 1 and 2. Hence mathematical problems may arise when it is used to characterise the nonadditivity of the system. Nevertheless, under some conditions, it is possible to use it as a good approximation.     

Conjugation of two complementary anti-cancer drugs confers molecular hydrogels as a co-delivery system

We reported in this communication on the first example of a molecular hydrogel system based on two complementary anti-cancer drugs for chemotherapy.     

Changes in surface morphology and work function caused by corrosion in aluminum alloys

Corrosion behavior of a material is complicated and can affect strongly its surface physical and chemical properties. In this study, the effect of corrosion on surface morphology and electron work function (EWF) of various Al alloys was comparatively investigated using a scanning electron microscopy and a scanning Kelvin probe. The experimental results showed that the change in EWF with corrosion time was not linear, but firstly increased and then decreased. The theoretical treatments demonstrated that such a change in EWF did not only depend on the surface roughness, but also correlate with oxide layers formed at the surfaces of Al alloys. The present results can also be used to reasonably explain the correlation between surface roughness and EWF reported previously.     

Statistical properties of the electrophoretic collision of a long DNA molecule with a small obstacle

We present experimental results for the collision of a single λ-DNA molecule with isolated cylindrical nanoposts whose radii range from 350 nm to 1.37 μm. The experimental apparatus was fabricated in oxidized silicon using a plasma-thinning method. The probability density for the dimensionless holdup time is described by a gamma distribution, which accurately represents the behavior of the probability density for X collisions and U/J collisions for short-lived and long-lived collisions, respectively. The shape parameter of the gamma distribution reflects the nature of the short-lived collisions, whereas the scaling parameter captures the role of the finite size of the post on the U/J collisions. When rendered in an appropriate dimensionless form, the existing models for the role of electric field gradients extend to all post sizes, indicating that 350 nm is still well above the point-sized limit. Our experiments provide insights into a regime that is very challenging for numerical simulations but highly relevant for separation processes.     

Molecular Oxygen Reduction Electrocatalyzed by meso-Substituted Cobalt Corroles Coated on Edge-Plane Pyrolytic Graphite Electrodes in Acidic Media

Five meso-substituted cobalt(III) corroles were examined as to their catalytic activity for the electoreduction of O(2) when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO(4). The investigated compounds are represented as (TpRPCor)Co(PPh(3)), where TpRPCor is the trianion of a para-substituted triphenylcorrole and R = OMe, Me, H, F, or Cl. Three electrochemical techniques, cyclic voltammetry, linear sweep voltammetry with a rotating disk electrode (RDE), and voltammetry at a rotating ring disk electrode (RRDE), were utilized to evaluate the catalytic activity of the corroles in the reduction of O(2). Cobalt corroles containing electron-withdrawing substituents were shown to be better catalysts than those having electron-donating groups on the three meso-phenyl rings of the triarylcorroles.