Theoretical Studies on the Coordin

Theoretical　Studies　on　the　Coordin...     

Studies on the Effects of Epimedium Extract on Erythrocytes

Epimedium, one of representatives of traditional Chinese herb, is mainly composed of flavones and polysaccharide. It is famous for its antioxidant, antineoplastic and antiaging activities and has been widely used in the field of invigorating kidney and st…     

Study on the Formation Mechanism of Oxygen-containing Groups on the Surfaces of Hypercrosslinked Polystyrenes

Davankov and Tsyurupa described a new series of hypercrosslinked polymeric networks in 19691. Owing to their high internal surface area, unique porosity, and excellent swelling feature, hypercrosslinked polymers have exhibited a good adsorption affinity t…     

Studies on the Kinetics of the FO CO Reaction

IntroductionAproposedcycleinvolvingtheFOradicalsisl:ThecontributionofthiscycletothecatalyticdestrUctionofozoneisdeterndnedbythefirststep.Thereaction(l)isalsothoughttobeapossiblesinkforatInosphericCO2.Baueretal.3gavearateconstantofl.24.lO-i3cm3/sforreaction(l),whichwasbelievedtobecorrectwithinafactorof2at9(X)-l4(X)K.Theactivationenergywasestimatedtobe46.OkJ/mol.Bedzhanyanetal.4reportedk<4xlO-"and<5xlO-l6cm3/sat3ooand55OK,respectively.Alowerbarrierofl3.8kJ/molcanbeextrapoIated.Francisco…     

Studies on the effect of surfactants on the extraction rate by laser thermal lens spectrometry

The effect of different kinds of surfactants on the extraction process of Nile Blue-I- was investigated by laser thermal lens spectrometry . It was shown that the surfactants could accelerate or decelerate the extraction rate by varying the extractive's solubility and the interfacial tension of the extraction solution. The higher the concentration of surfactants was, the more obvious the effect.     

Studies on the biosynthesis of arteannuin

In previous communications we have reported that arteannuic acid(1,Scheme1)is a common precursor of the biosynthesis of both arteannuin(2)and arteannuinB(3)by the leaf homogenate of the plant Qinghao(Artemesia annua L.).It seemsthat most likely the oxidation of allylic tertiary carbon atom,C-6,may occur early inthe biosynthetic path of 2 and 3 from 1.Natural 6-epi-deoxyarteannuin B(4)isolated     

Studies on the Synthesis of Preverecynarmin

Prev~n1,acembranopditerpenoid,wasfirstisolatedfromsoftcoral(VeretilIumcoporium)inl99(),anditSmCtUrwasehablishedas(+)-(lE,3E,7E,llE)-cembra-l,3,7,ll-tetraen6-olaeetate[l].SofarasweknOW,thetotalSynthsisof1hasnobeenrePOrtedyet.Herein.wewishtodescribethetotalpeisoftheprecursor(9),theSynthhcroutewasouthnedbelowfa)HBr.80%;b).CH3C02Na.CH3CO2H,75%,c).Se02-I-Bu00H,70%,d).CCl',PPh3,83%,e).NaSQPh.DMF.9O%,O.K=CO3.MeOH,95%,g).DHP,Ts0H.8O%,h),TBAB,5O%NaOH,aq.,5%;i).Li-Effez.M,70%;j…     

Studies on the Synthesis of Villosol

TheindoidsxillosoIandt4llosolsidewereisolatalinl985frOmPatriDiavi11osa,atradihonalChineseherbmedicineusedfortreatofconunoncoldandparohhsmUInPS.PhannacologicalstUdieshaveestablishedthattheyshowanti-inflannnatOryachvihes.BasedonspeCtraldata,chenucaltransformationsandanalysisOfCDbehaviorofthelactonering,x-illosolsideandvillosolhavebeengivensmictUresland2respeCtively.[']Itisinterestingthatthesenot-eltridoidshat,ereversedstereocheAnsto'atC5andC9junCtUreSwith5Q,9Qinsteadoftheusuall}'found5…     

Studies on the Interaction of Poly

Studies　on　the　Interaction　of　Poly...     

Theoretical studies on the substitution effect of fluorine on ethylene

The substitution effect of fluorine on ethylene is investigated by means of studyingthe properties of the charge distribution at the bond critical points with the theory of atomsin molecules.It is found that fluorine atom acts not only as a σ electron acceptor,but also asa π electron donor,and these double effects are reflected in the quantity of ellipticity,Lap-lacian and the charge density of charge distribution at the bond critical points.For C—C,C—Fbonds,the major axis of elliptical contours is perpendicular to the molecular plane,but forC—H bond,it is parallel to the molecular plane.Other effects originating from the substi-tution have also been discussed.     

Studies on the Combined Derivative Spectrophotometry

The combined derivative spectrophotometry developed in this paper is a new method, which can be used to determine multicomporent mixture simultaneously and may improve the sensitivity and accuracy of the measurement remarkably. Two practical tests were carried out to verify the correctness of the theory, and the results are satisfactory.     

Addition of γ-silyloxyallyltins on ethyl glyoxylate: evaluation of the influence of the experimental conditions on the stereochemical course of the reaction

Ethyl glyoxylate was reacted with α-substituted γ-(t-butyldimethylsilyloxy)-allyltributyltin in order to obtain selectively each diastereomer of ethyl 3-(t-butyldimethylsilyloxy)-2-hydroxyhex-4-enoate and subsequently the corresponding diols. Diastereomers syn-E, anti-E and anti-Z were obtained in good yields with good to high selectivities and the obtained results were rationalized by consideration of cyclic or open transition states in agreement with the experimental conditions and with the structure of the starting reagents.     

Theoretical studies on the structural change in the N-protonated tetraphenylporphyrin

The geometries of tetraphenylporphyrin which is a kind of important porphyrin derivatives, and its N-protonated diacid are calculated with AM1 MO method under symmetry restriction. The configurational changes and their effects on molecular aggregation are discussed by means of structure analysis, charge population analysis and frontier orbital analysis.     

Comparative Study on the Effect of NaBr on the Interaction Between Alkyltrimethylammonium Bromide and β-Cyclodextrin

The effect of NaBr on the interaction between alkyltrimethylammonium bromide (CnTAB (n = 14 for TTAB and 16 for CTAB)) and ß-CD was studied by surface tension method. The first decrease in the γ_cmc of TTAB/ß-CD in the presence of NaBr mainly due to the elongated effective chain length of the hydrophobic part of the TTAB/ß-CD complexes; while the increase in the γ_cmc of both of the TTAB/ß-CD and CTAB/ß-CD in the presence of NaBr could be attributed to the close pack of CnTAB at the air/water interface.     

Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on Society

In recent years the littering of plastics and the problems related to their persistence in the environment have become a major focus in both research and the news. Biodegradable polymers like poly(lactic acid) are seen as a suitable alternative to commodity plastics. However, poly(lactic acid) is basically non‐degradable in seawater. Similarly, the degradation rate of other biodegradable polymers also crucially depends on the environments they end up in, such as soil or marine water, or when used in biomedical devices. In this Minireview, we show that biodegradation tests carried out in artificial environments lack transferability to real conditions and, therefore, highlight the necessity of environmentally authentic and relevant field‐testing conditions. In addition, we focus on ecotoxicological implications of biodegradable polymers. We also consider the social aspects and ask how biodegradable polymers influence consumer behavior and municipal waste management. Taken together, this study is intended as a contribution towards evaluating the potential of biodegradable polymers as alternative materials to commodity plastics.     

Studies on the Catalytic Properties of Magnesia Supported on γ-Alumina

ＩｎｔｒｏｄｕｃｔｉｏｎＧｌｙｃｏｌｅｔｈｅｒｓａｒｅｉｍｐｏｒｔａｎｔｉｎｄｕｓｔｒｉａｌｄｅｒｉｖａｔｉｖｅｓｏｆｅｐｏｘｉｄｅｓ .Ｐｏｌｙｅｔｈｙｌｅｎｅ ｇｌｙｃｏｌｅｔｈｙｌｅｔｈｅｒｓａｎｄｐｏｌｙｐｒｏｐｙｌｅｎｅｇｌｙｃｏｌｅｔｈｙｌｅｔｈｅｒｓａｒｅｔｗｏｉｍｐｏｒｔａｎｔｓｅｒｉｅｓｏｆｐｒｏｄｕｃｔｓ .Ｇｌｙｃｏｌｅｔｈｅｒｓａｒｅｇｏｏｄｓｏｌｖｅｎｔｓｄｕｅｔｏｔｈｅｐｒｅｓｅｎｃｅｏｆ—Ｏ—ａｎｄ—ＯＨ ｇｒｏｕｐｓ.Ａｓａｒｅ ｓｕｌｔ ,ｔｈｅｙａｒｅｗｉｄｅｌｙｕｓｅ…     

Theoretical Studies on the N-Phenylpyrrolidine Formation Mechanism Based on the Reaction of Phenylamine with 1,4-Butanediol

The reaction mechanism of phenylamine reacting with 1,4-butanediol to give N- phenylpyrrolidine was investigated with traditional transition state theory. Based on the experimental results, two reaction channels were discussed. The geometries of their reactants, products, intermediates and transition states were optimized. The possible transition State and activation energy were determined by vibrational analysis and IRC verification. And finally, the main reaction channel was given.     

Studies on the influence of heat treatment on polyamide-1010 structure

In this work,the influence of heat treatment on Polyamide-1010 structure ofaggregation state was studied by using WAXD and SAXS techniques.The results showedthat the best crystallinity was obtained nearby T=175℃ for Polyamide-1010 samples withvarious annealing treatment.Through extrapolating method,the Tg obtained wasapproximately 58℃.Based on the one-dimensional electron density correlation function ofpartially crystalline polymers,some structural parameters of Polyamide-1010 weredetermined by SAXS.     

Studies on the Effect of Glass Transition on the Crystalline Transition in Syndiotactic Polystyrene – Solvent Complexes

Summary: Amorphous syndiotactic polystyrene (sPS) was crystallized at room temperature in Norbornadiene (bicyclo[2,2,1]-hepta-2,5-diene), Mesitylene (1,3,5- Trimethylbenzene), 3-Carene (3,7,7-trimethyl bicyclo[4,1,0]hept-3-ene) and DMN (1,4-Dimethylnaphthalene) to form the sPS-solvent complex (δ form) with respective solvent molecules. In situ HTFTIR studies showed that the δ form to γ form transformation temperature occurs well below the glass transition temperature of sPS, which is depressed due to the presence of solvent in the amorphous phase; higher the solvent content in the complex, lower the transition temperature. Glass transition temperatures determined by Modulated differential scanning calorimetry (MDSC) coincide with the transition temperatures, indicating that the δ form transforms into γ form at the glass transition temperature for these complexes. Such a behavior is very different from the behaviour of the sPS- solvent complexes formed by dichloromethane, chloroform, toluene, o-dichlorobenzene, decalin (cis-trans) etc. and for these complexes the transition occur well above the T_g. 1