Fluid inclusions evidence for differential exhumation of ultrahigh pressure metamorphic rocks in the Sulu terrane

Since the discovery of coesite and diamond inclusions in eclogites from the Dabie-Sulu orogen, east-central China[1―3], this largest ultrahigh pressure (UHP) metamor- phic terrane in the world has attracted extensive scientific interests. A number of hydrous minerals such as zoisite, phengite, magnesite and talc have been found in the UHP rocks, showing that fluids have played an important role in this type of extreme metamorphic evolution[4―8]. Sev-eral techniques have been applied to th…     

Atomic stick-slip friction between commensurate self-assembled monolayers

The classical molecular dynamics simulations have been used to examine the compression and friction between commensurate self-assembled monolayers (SAMs) on Au (111). The friction force changes in a period corresponding to the geometric structure of sliding surfaces. The simulations reveal an ordered atomic stick-slip motion and discontinuous movements of diverse monomers, mainly head and tail groups. All of the head groups of the static film have 2～3 metastable positions (MPs). They oscillate around one of the MPs in stick phases and jump simultaneously to a new MP in slip phases. The tail groups of the sliding film are pulled forward together with opposite ones while sticking and jump forward half of the lattice constant relative to opposite ones while slipping. A complete vision of the motion of SAM chains is thereby built up and compared with the molecule behavior predicted by the Tomlinson model.     

Preparation of polypropylene/montmorillonite nanocomposites by intercalative polymerization： Effect of in situ polymer matrix functionalization on the stability of the nanocomposite structure

The copolymerization of propylene and 5-hexenyl-9-borabicyclo[3.3.1]nonane (5-hexenyl-9-BBN) has been conducted with an MgCl2/TiCl4 catalyst intercalated in an organically modified montmorillonite (OMMT) with triethylaluminum (AlEt3) cocatalyst and diphenyldimethoxysilane (DDS) external donor. This polymerization process simultaneously results in both the exfoliation of MMT layers to realize the preparation of polypropylene (PP)/MMT nanocomposites and the implantation of reactive borane groups in the formed PP matrix. The polymer-borne borane groups have been able to undergo an effi-cient hydrolysis process under very mild reaction conditions (40℃, 3 h, in THF), introducing hydroxy groups into PP without sacrificing the polymerization-formed nanocomposite structure (the exfoliation of MMT). The resultant hydroxyl-functionalized PP/MMT nanocomposites exhibit enhanced structural stability against processing compared with those based on unfunctionalized PP matrix.     

Novel Hyperbranched Polyurethane Brushes for Biomedical Applications

1 Results The objective was to make hyperbranched (HB) polyurethane brushes with reactive end groups, to coat biomedical devices and to enable the introduction of various functionalities that are needed to fulfill biomedical tasks.Biomedical materials should fulfill at least three requirements: (1) good mechanical properties, (2) good biocompatibility and (3) provided with functionalities to perform the required tasks. Since polyurethanes are able to fulfill the first 2 requirements we focused in this work on the introduction of functionalities. We have developed a simple concept to make a new family of AB2 monomers[1-3], which enabled us to make in one step HB polyurethanes with reactive blocked isocyanates (BI) at the end of each polymer chain. The reactions as depicted in Fig.1 proceeded in very high yields, thanks to the high selectivity of carbonyl biscaprolactam (CBC). Primary amines substitute only one caprolactam group in CBC, whereas secondary amines remain totally unaffected. The corresponding polymers have at the end of each chain reactive blocked isocyanate (BI) groups that have been functionalized with bioactive groups, whereas the secondary amine in the focal point remained available for further modification. Thanks to many BI groups this technology allows introducing much functionality, which is needed for various biomedical tasks in applications.     

A rare lobopod with well-preserved eyes from Chengjiang Lagerst(?)tte and its implications for origin of arthropods

The origin of arthropods has long been one ofthe most hotly-debated subjects. Arthropods used to bethought closely related with annelids, but the two groups arenow believed to be separated into two major realms withinProtostomia on the basis of new molecular data. Although itis generally held by paleontologists that arthropods should berooted in the early lobopods--a kind of worm-like creaturewith non-segmented legs, no intermediate forms have beenfound to bridge them. Here we report an organism with amixture of characters, including features characteristic ofarthropods (e.g., primary cephalization with paired eyes,paired antennae, and preliminary tagmosis) and of lobopods(e.g., worm-like body design, the dorsal spines, andnon-segmented Iimbs or lobe-like legs). The discovery of therare transitional form may throw new light on the origin ofarthropods and suggests that the most primitive arthropodsbegan with paired uniramous legs and the biramous onesevolved later.     

A rare lobopod with well-preserved eyes from Chengjiang Lagerstātte and its implications for origin of arthropods

The origin of arthropods has long been one ofthe most hotly-debated subjects. Arthropods used to bethought closely related with annelids, but the two groups arenow believed to be separated into two major realms withinProtostomia on the basis of new molecular data. Although itis generally held by paleontologists that arthropods should berooted in the early lobopods-.a kind of worm-like creaturewith non-segmented legs, no intermediate forms have beenfound to bridge them. Here we report an organism with amixture of characters, including features characteristic ofarthropods (e.g., primary cephalization with paired eyes,paired antennae, and preliminary tagmosis) and of lobopods(e.g., worm-like body design, the dorsal spines, andnon-segmented limbs or lobe-like legs). The discovery of therare transitional form may throw new light on the origin ofarthropods and suggests that the most primitive arthropodsbegan with paired uniramous legs and the biramous onesevolved later.     

Progress in the synthesis and reactivity studies of metallabenzenes

Metallabenzenes are metallacyclohexatriene complexes that are derived by replacement of one of the CH groups in benzene with a transition-metal fragment. Their synthesis and aromatic properties have recently attracted considerable attention. This paper summarizes the progress in the synthesis, aromatic property, and reactivity studies of metallabenzenes. We will describe the synthesis and reactivity of typical metallabenzenes with various metals (e.g. osmium, iridium, and ruthenium, etc.), the synthesis and structure of a recent reported example of metallanaphthalene and several rare examples of novel and stable metallabenzynes. Finally, the possible future developments in this field have also been suggested.     

Synthesis and Thermal Property of the Poly（silpheny-lenesiloxane）s with Functional Groups

1 Introduction Silicon-containing polymers have been intensively studied in the past half-century, and a great number of papers, patents and books have been published on the synthesis, properties and applications. Silicon-containing polymers, especially polymers containing silicon atoms in the backbone, including some major species as polysiloxane, polysilane, polysilazane, etc. have chains constructed of alternately arranged silicon and oxygen atoms with organic groups attached to the silicon…     

Temperature Control System for Biochemical Reactions in Microchip-Based Devices

IntroductionIn recent years,the development of miniaturizedsystems for chemical and biochemical reactions hasrapidly progressed[1] .Most of the microdevices forconducting these reactions are made of silicon orglass using conventional microfabrication methodsused in the microelectronic industry or bymodifying the processing technologies for microelectromechanical systems ( MEMS) . Severalresearch groups have developed polymerase chainreactions ( PCR) chips with various features toperform sim…     

新型铁系催化剂催化制备高相对分子质量宽/双峰聚乙烯

合成了配合物3([2,6-R2-C6H3N=C(CH3)C5H3N(CH3)C=N(3,5-R2)C6H2-CH2-(3,5-R2)C6H2N=C(CH3)C5H3N(CH3)C=N(2,6-R2)C6H3][FeCl2]2(R=i-C3H7)).经甲基铝氧烷(MAO)或三乙基铝(AlEt3)活化,配合物3对乙烯聚合表现出较高的催化活性,得到高相对分子质量的宽/双峰聚乙烯,且聚乙烯中高相对分子质量部分占优势.此外,所得聚乙烯具有较高的熔点和结晶度.13C NMR核磁共振表征显示,所得聚合物为线性聚乙烯.     

Bimodal PE prepared with combined iron (II) and nickel (II) olefin polymerization catalysts

Iron (II) and nickel (II) complexes based on bis (imine) ligands are typical late-transition olefin poly- merization catalysts. As usual, nickel (II) catalysts can produce branched polyethylene (PE) even super branched PE of narrow molecular weight distri…     

2-（4-Pyridyl）imino nitroxide-tetraphenylporphyrin zinc（II）： A chemosensing ensemble for nicotine

2-(4-Pyridyl)imino nitroxide and tetraphenylporphyrin zinc(Ⅱ) formed a stable complex by noncovalent bonding in a nonpolar solution.Nicotine displaced 2-(4-pyridyl)imino nitroxide when it was added to a solution of 2-(4-pyridyl)imino nitrox-ide-tetraphenylporphyrin zinc(Ⅱ).The fluorescence intensity of tetraphenylporphyrin zinc(Ⅱ) was altered by sequentially addition of 2-(4-pyridyl)imino nitroxide and nicotine.This was used to develop a new method for detection of nicotine.     

铁(Ⅱ)-邻二氮菲络合物催化的苯乙烯原子转移自由基聚合

以铁(Ⅱ)-邻二氮菲络合物(Fe(Ⅱ)/phen)为催化体系,以苄氯为引发剂,对苯乙烯的原子转移自由基聚合及苯乙烯与甲基丙烯酸丁酯的嵌段共聚进行了研究.发现本体系可有效地控制聚合物的相对分子质量分布(1.2     

Preparation of long-branched polyethylene byin situ polymerization using late transition metal and metallocene catalysts

An in situ polymerization method was investigated to prepare long-branched polyethylene (LBPE) with ethylene alone and a single cocatalyst, methylalumoxane (MAO), by using a dual functional catalytic system containing late transition metal oligomerization catalyst and metallocene copolymerization catalyst. The obtained long-branched polyethylene has the characteristics of low melting point, high activity and well-dispersed sequence distribution.     

乙酸分子印迹聚合物的制备及其在针式萃取技术中的应用

选用乙酸为模板分子,4-乙烯基吡啶为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用本体聚合方法合成了具有高选择性的分子印迹聚合物.以该聚合物作为填充吸附介质,开发了针式萃取装置,并与气相色谱联用分析了气体中的痕量乙酸.实验考察了主要反应条件参数对聚合物吸附性能的影响.结果表明:使用丙酮为溶剂,预聚合时间为5h,模板分子、...     

一种钯离子印迹聚合物的制备优化研究

采用沉淀聚合法, 以PdCl₄²⁻为模板, 以4-乙烯基吡啶(4-VP)、2-烯丙巯基烟酸(ANA)、2-乙酸胺基丙烯酸(AAA)为功能单体, 加入交联剂二甲基丙烯酸乙二醇酯(EGDMA)、引发剂偶氮二异丁腈(AIBN)和致孔剂甲醇, 制备钯离子印迹聚合物。通过添加不同种类、用量的功能单体和不同用量的交联剂, 探究不同制备条件对钯离子印迹聚合物制备效果的影响。优化结果表明, 与ANA和AAA功能单体对比, 4-VP和PdCl₄^2–能形成4:1的稳定配合物, 结合常数最大, 印迹效果最好, 是 3 种功能单体中用于制备钯离子印迹聚合物的最佳选择。吸附试验结果进一步表明, 按照模板、功能单体、交联剂用量比例为1:4:40制备的钯离子印迹聚合物对Pd(II)的吸附量最大, 为5.042 mg/g。     

聚对苯二甲酸乙二酯的酰氯法固态聚合

用酰氯-固态缩聚法合成了不含金属盐催化剂的聚对苯二甲酸乙二酯(PET),其中含有不同量的二甘醇链结构,含量从0～16mol%。本文还对聚合物的链结构、分子量分布和聚合动力学作了初步探讨。     

Preparation of PE/MMT nanocomposite by monomer intercalation and in situ copolymerization

The catalyst {[(2-ArN == C(Me)(2C5H3N]FeCl2} (Ar = 2-C6H4(i-Pr)) with methylaluminoxane (MAO) as cocatalyst was intercalated between layers of montmorillonite (MMT) for ethylene oligomerization. Metallocene catalyst Me2Si(Ind)2ZrCl2 and MAO was then added to form a dual functional catalytic system. A PE/MMT nanocomposite was prepared by copolymerization of ethylene with α-olefins produced in situ from ethylene over the dual functional catalytic system. The catalytic system was of high polymeric activity. The resultant PE/MMT nanocomposites were stable and got increases in tensile strength and temperature of maximum weight loss (Tonset).     

Synthesis of well-defined functional PE graft copolymers via ATRP process

Polyethylene (PE) is one of the most important polymeric materials. It has excellent physical mechanical properties and thus a widespread range of applications. However, due to the lack of polar functional groups on its polymer chain, PE usually suffers from poor adhesion to and incompatibility with other polymers or materials, which has significantly limited many of its end uses. To resolve this problem, one of the established approaches is to introduce a second functional polymeric component as side chains to synthesize PE graft copolymers that not only provide a large quantity of functional groups to impart polarity to PE but also preserve the original desired PE properties, such as crystallinity, melting point,