浅述田径教学与训练中准备活动内容的“组合性”和“聚合性”结构

笔者通过大量的田径教学训练与实践的经验，对田径运动中准备活动进行详细论述，说明了组合性结构的合理性和应用要求，阐述了聚合性结构的先进性和应用方法。并通过实践经验阐述了应用时机和应用类型。结论为：组合性活动规律性强，便于组织，聚合性准备活动伸缩性大，但不易控制量和强度。

试论消散性量变的概念与机理

【正】 事物的实际量变过程,其复杂性较之教科书所讲的纯粹形态无疑要丰富深刻得多。这里拟就其中的消散性量变及聚合性量变问题加以论析,以求教于学界同仁。言量变范畴,并非脱离开质变范畴。恰相反,所谓研究量变的复杂性,正是研究量变通向质变的复杂性。量变,就是事物在一定范围内量的变化。在此范围内,量的变化即数量的增减和场所的变动,并不影响某物之为某物。超出此范围,即超出度的范围,量的变化就过渡为质的变化,这就归属于质变范畴了。量变,可以是连续的也可以是间断的。

Synthesis of Multishell Carbon Nanotube Composites via Template Method

Multishell nanotubes of polyaniline and carbon were synthesized via a template approach. A thin layer of MnO2 coated on carbon nanotubes acts as a reactive template for the consequent formation of the polyaniline coating. The polyaniline-carbon nanotubes show enhanced dispersibility in water and can be possibly used as a functional material of electrochemical capacitors with improved performance. The general method operates by coating carbon nanotubes on functional materials such as poly （3,4-ethylenedioxythiophene）, polypyrrole, silica, and carbon.

Ethylene Polymerization with Palygorskite Supported Nickel-Diimine Catalyst

A nickel-diimine catalyst [N, N'-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1, 3-butadiene nickel dibromide, DMN] was supported on palygorskite clay for ethylene slurry polymerization. The effect of supporting methods on the catalyst impregnation was studied and compared. Pretreatment of the support with methylalumi-noxane (MAO) followed by DMN impregnation gave higher catalyst loading and catalytic activity than the direct impregnation of DMN. Catalyst activity as high as 5.42×105g PE·molNi-1·h-1 was achieved at ethylene pressure of 6.87×105 Pa and polymerization temperature of 20℃. In particular, the morphological change of the support during MAO treatment was characterized and analyzed. It was found that nano-fiber clusters formed during the support pretreatment, which increased the surface area of the support and favored the impregnation of the catalyst. The investigation of polymerization behavior of supported catalyst revealed that the polymerization rate could be kept at a relatively high level for a long time, different from the homogeneous catalyst. By analyzing the SEM photographs of the polymer produced by the supported catalyst, the morphological evolution of polymer particles was preliminarily studied.

Syntheses, Structures and Magnetic Properties of Two Co(II) Coordination Polymers with 2,5-Pyridine Dicarboxylic Acid

The hydro(solvo)thermal reactions of cobalt powder or its chloride with 2,5- pyridine dicarboxylic acid (H2PYDC) yielded two new complexes: [Co(II)2(PYDC)2(H2O)2- (H2O)4]n 1 and {Co(II)[NH2(CH3)2]2(PYDC)2}n 2. It is observed that the reactive solvents result in different connectivity modes of ligand and diverse dimensional extension of crystal structures. The correlation between structure and magnetic property will be discussed in this paper. Crystal data for 1: space group P1, a = 7.0419(17), b = 8.937(2), c = 9.6182(19) ?, α = 91.532(4), β = 99.869(10), γ = 107.889(11)o, V = 565.5(2) ?3, Z = 1, Dc = 1.845 g/cm3, μ = 1.56 mm-1, F(000) = 322 , R = 0.0505 and wR = 0.1580; and those for 2: space group C2/c, a = 14.9075(6), b = 8.2523(3), c = 16.9643(2) ?, β = 100.982(2)o, V = 2048.75(11) ?3, Z = 4, Dc = 1.560 g/cm3, μ = 0.892 mm-1, F(000) = 996, R = 0.0443 and wR = 0.1134.

Rolonged-Release Nitrogen Fertilizers for Reducing Global Environmental Pollution

Nitrogenous fertilizers of prolonged action were developed on the basis of carbamide （urea）. Technological schemes and parameters are offered to obtain restructured carbamide. Possible versions of degradation of different structure prolonged action fertilizers are considered. It was shown that the most favorable conditions for degradation of polymer molecules are created when molar ratio of the initial carbamide and aldehyde is within 1：1-1.3, correspondingly. At such terms the linear structure molecules with rare cross-links are formed. Such structure is more accessible for penetration of ureasive ferments into polymer molecules.

Mutational analysis of the PTEN gene in soft tissue sarcomas

Objective： This study was to investigate whether PTEN mutations play a role in the carcinogenesis of soft tissue sarcomas （STS）. Methods： Polymerase chain reaction-single strand conformation polymorphism （PCR-SSCP） was used to amplify 4 exons of PTEN and to analyze the conformation polymorphism, then DNA sequencing methods was used to detect point mutation of PTEN gene four exons of abnormal single strand conformation in soft tissue sarcomas. Results： Two of 86 cases showed 130th condon G→A missense mutation in the exon 8 of PTEN gene, and this mutation made Arg to change to Gin in PTEN protein structure 334th condon A→T missense mutation in the exon 8 of PTEN gene, and this mutation made Asn to change to Lys in PI-EN protein structure. Conclusion： These data indicated the existence of PTEN mutation in soft tissue sarcomas, but PTEN gene mutation rate is very low. PTEN mutation may prays an less important role in the development and malignant transformation of soft tissue sarcomas.

Molecular dynamics study on the relationships of modeling,structural and energy properties with sensitivity for RDX-based PBXs

In this paper,a primary model is established for MD(molecular dynamics) simulation for the PBXs(polymer-bonded explosives) with RDX(cyclotrimethylene trinitramine) as base explosive and PS as polymer binder.A series of results from the MD simulation are compared between two PBX models,which are represented by PBX1 and PBX2,respectively,including one PS molecular chain having 46 repeating units and two PS molecular chains with each having 23 repeating units.It has been found that their structural,interaction energy and mechanical properties are basically consistent between the two models.A systematic MD study for the PBX2 is performed under NPT conditions at five different temperatures,i.e.,195 K,245 K,295 K,345 K,and 395 K.We have found that with the temperature increase,the maximum bond length(L max) of RDX N N trigger bond increases,and the interaction energy(E N-N) between two N atoms of the N-N trigger bond and the cohesive energy density(CED) decrease.These phenomena agree with the experimental fact that the PBX becomes more sensitive as the temperature increases.Therefore,we propose to use the maximum bond length L max of the trigger bond of the easily decomposed and exploded component and the interaction energy E N-N of the two relevant atoms as theoretical criteria to judge or predict the relative degree of heat and impact sensitivity for the energetic composites such as PBXs and solid propellants.

Structure evolution of thiophene-containing conjugated polymer photocatalysts for high-efficiency photocatalytic hydrogen production

Conjugated polymer photocatalysts have received extensive attention in the field of photocatalytic hydrogen evolution owing to their tunable molecular structures and electronic properties.Herein,we developed three donoracceptor(D-A)type thiophene-containing narrow-band-gap conjugated polymers with pyrene as a donor and different fused-thiophene derivatives as acceptors via direct C-H arylation coupling polymerization.It was found that the band gap of the polymers can be tuned by adjusting the number of the fused-thiophene rings.The visible light absorption range can be extended by increasing the number of the thiophene rings,the planar molecular structure for both donor and acceptor units facilitates the charge transmission along the polymer skeleton,and the D-A type polymer structure promotes the dissociation of photo-induced electrons and holes.As a result,a high photocatalytic hydrogen evolution rate of 33.07 mmol h^(−1)g^(−1) was obtained by PyTP-2 with an optimized molecular structure under visible light irradiation(λ>420 nm)without the aid of Pt co-catalyst.In addition,PyTP-2 also shows a photocatalytic activity for oxygen evolution with an average oxygen evolution rate of 58.37µmol h^(−1)g^(−1).

Flexible fabric gas sensors based on PANI/WO3 p−n heterojunction for high performance NH3 detection at room temperature

A PANI/WO3@cotton thread-based flexible sensor that is capable of detecting NH3 at room temperature is developed here.A layer of WO3 with PANI nanoparticles can be deposited by in-situ polymerization.The morphology and structure of the specimens were investigated by utilizing TEM,SEM,XRD and FTIR.The sensing performance of the PANI/WO3@cotton sensors with different WO3 molar ratios to NH3 at room temperature was examined.The results show that the optimal sensor(10 mol%WO3)has a response of 6.0 to 100 ppm NH3,which is significantly higher than that of the sensors based on pristine PANI and other composites.The PANI/WO3@cotton sensor also displays excellent selectivity,gas response,and flexibility even at room temperature.The unique fiber structure,p-n heterojunction,and the increased protonation of PANI in the composites contribute to the enhanced sensing property.

Self-assembly of conjugated polymers for anisotropic nanostructures

As their potential applications in various electronic devices increase, the preparation of anisotropic conjugated polymer nanostructures are highly desirable. This paper presents a review of the literature and our recent results on the self-assembly of one-, two- and three-dimensional anisotropic nanostructures using conjugated polymers as building blocks, including the formation of one-dimensional (1D) nanofibers and nanotubes, two-dimensional (2D) nanoribbons and nanosheets, and three-dimensional (3D) superstructures. The mechanisms guiding the formation of various nanostructures are analyzed by a cooperative effect of - stacking interaction and other noncovalent interactions.

Hybrid π-conjugated polymers from dibenzo pentacyclic centers：precursor design,electrosynthesis and electrochromics

π-Conjugated polymers(CPs)represent one of the quite important and rapidly growing branches of flexible electrochromic materials.Electrosynthesized hybrid CPs employing dibenzo pentacycles(fluorenes,carbazoles,dibenzothiophenes,and dibenzofuran)as the backbones have received considerable attention owing to their special structures and interesting electrochromic performances.Recent studies show that polymers from these structures exhibit decent contrast ratios,favorable coloration efficiencies,low switching voltages,fast response time,excellent stability,and color persistence.Intrinsically,their electrochromic properties significantly depend on fine-tailoring of precursor monomer structures,and polymerization techniques and conditions.This review devotes to showing a clear picture of the research progress of dibenzo pentacycle-centered CPs via electrochemical polymerization,including fluorenes,carbazoles,dibenzothiophenes,and dibenzofuran-based hybrid electrochromic polymers.Critical influences of the tailored precursor structures on their electropolymerization and resultant polymer performances are highlighted,aiming at providing an insight for the development of novel fused ring-based polymer electrochromic materials.

A second-order nonlinear optical dendronized hyperbranched polymer containing isolation chromophores： achieving good optical nonlinearity and stability simultaneously

Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept of "isolation chromophore", "isolation group" and dendritic structure, a dendritic molecule D-NS and a dendronized hyperbranched polymer DHP-NS are prepared to investigate their structure-property relationship. For the small dendritic molecule D-NS, it exhibits a high d33 value of 140 pm/V.But this value can be easily dropped when the temperature is higher than 50 °C, which extremely limits its real application. After introducing D-NS into a dendronized hyperbranched polymer chains, the obtained DHP-NS also shows a high d33 value of101 pm/V, but much better stability than D-NS. Even when its thin film was heated to 120 °C, no obvious decay can be observed in the d33 value of DHP-NS. This work demonstrates an effective strategy to realize both large NLO effect and good stability simultaneously.

Three new Cu(Ⅱ)-Ln(Ⅲ) heterometallic coordination polymers constructed from quinolinic acid and nicotinic acid: Synthesis, structures, and magnetic properties

Three new Cu（Ⅱ）-Ln（Ⅲ） heterometallic coordination polymers based on two N-heterocyclic carboxylic ligands, {[LnCu（LI）2（L2）（H2O）2]· mH20},, （Ln = La（1）, Nd（2）, Gd（3）, m = 2 （for 1）, 1 （for 2, 3）, H2L1 = quinolinic acid, HE2 = nico- tinic acid）, have been synthesized and characterized. 1 has a two-dimensional （2D） layer structure with a Schlifli symbol of （44.62）, while complexes 2 and 3 are isostructural and have three-dimensional （3D） structures with a Schlafli symbol of （3.4.5）2（32.42.52.6]4.74.83.9）（32.63.7） of 3-nodal net. Magnetic investigations suggest that antiferromagnetic coupling exists be- tween NdIn and Cun in 2, while weak ferromagnetic coupling between GdⅢ and CuⅡ in 3. The difference of magnetic properties between 2 and 3 has been discussed.

Nonlinear optical material of a low-dimensional coordination polymer:Synthesis,structure,NLO and fluorescence properties

Employing unsymmetrical 2-mercapto-5-methyl-1,3,4-thiadiazole and 2,2′-bipyridine as mixed ligands, a new low-dimensional coordination polymer [Zn(MMTA) 2 (2,2′-bipy)] n (MMTA = 2-mercapto-5-methyl-1,3,4-thiadiazole, 2,2′-bipy = 2,2′-bipyridine), has been synthesized under solvothermal condition and characterized by single crystal X-ray diffraction. This compound crys- tallizes in the noncentrosymmetric space group Cc, with cell parameters: a = 8.291(4) , b = 15.483(9) , c = 15.620(6) , = 96.00(5)°, V = 1994.1(2) 3 , and Z = 4. The mixed ligands link the zinc center into a mononuclear unit, which is futher linked by weak C-H···N and C-H···S hydrogen bonds into a three-dimensional noncentrosymmetric framework. The compound exhibits intense photoluminescence and distinct NLO properties at room temperature. The intensity of the green light produced by the powder sample of the compound is about 3.2 times that produced by KDP powder. On the basis of the results of TG analysis, the structure is thermally stable up to ～260 °C.