COPOLYMERIZATION OF ETHYLENE WITH 1-OCTENE USING Et(Ind)_2ZrCl_2/MAO CATALYST

Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)_2ZrCl_2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalystsystem. The effect of temperature and zirconium aluminum mole ratio of the catalyst onthe copolymerization was also investigated. The results of ^(13)C NMR determination of thecopolymer showed that the 1-octene units in the copolymer are principally isolated.

^(13)C-NMR STUDY OF ETHYLENE-1-OCTENE COPOLYMERS

A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On the basis of the sequence distributions, the ethylene-1-octenecopolymerization mechanism was studied. It was found that the observed sequence distributions inethylene-1-octene copolymers are satisfactorily predicted by the two-site model M/M,in whichthe copolymerization proceeds according to first-order Markovian statistics at the two differentsites.

The HY5 transcription factor negatively regulates ethylene production by inhibiting ACS1 expression under blue light conditions in pear

Ethylene is the main factor controlling fruit ripening of pear(Pyrus ussuriensis).Ethylene production rate is negatively correlated with fruit shelf life;therefore,it is important to decrease the ethylene levels for optimal fruit storage.Here,we observed that blue light treatment could inhibit ethylene production and promote the expression of ELONGATED HYPOCOTYL 5(PuHY5),a basic leucine zipper domain(bZIP)transcription factor.The following studies showed that PuHY5 could bind to the promoter of ACC synthase 1(PuACS1),a rate-limiting enzyme in ethylene biosynthesis,and inhibit its expression.For pears in which Pu HY5 was silenced,the ethylene production and PuACS1 expression were much higher than those in the control fruit.These results demonstrated that blue light inhibited ethylene production through the induction of Pu HY5 in pear.Our finding provides a new method for prolonging fruit shelf life.

Effect of Internal Ethylene and 1-Methylcyclopropene on Ethylene Metabolism and Membrane Lipid Peroxidation in Papaya Fruit

[Objective] This study was conducted to evaluate the effect of 1-methylcy- clopropene （1-MCP） on fruit firmness, and the activity of the enzymes involved in ethylene metabolism and membrane lipid peroxidation. [Method] The nearly ripe fruits of the papaya cultivar Risheng were randomly assigned to one of four groups. Two groups were treated under hypobaric and hypoxic （HH） atmosphere condition for six hours, and immediately soaked in deionized water （HH alone）, or fumigated with 2.0 mg/L 1-MCP （HH＋I-MCP） for 24 h. The other two groups untreated under HH condition were also soaked in deionized water （negative control）, or fumigated with 2.0 mg/L 1-MCP （1-MCP alone） for 24 h. After that, the fruits of all the four treatments were stored at room temperature （23＋1） ℃. Cell membrane permeability, fruit firmness, respiration rate, ethylene release rate, SOD activity, POD activity, CAT activity, MAD content and LOX activity were measured once every three days during storage. [Result] Treatment with 1-MCP delayed the occurrence of the peaks of respiration rate and ethylene release rate, significantly reduced the accumulation of malondialdehyde （MDA）, and inhibited the decrease in papaya fruit firmness. Compared with the control, 1-MCP treatment significantly increased the SOD （su- peroxide dismutase）, POD （peroxidase） and CAT （catalase） activity, reduced the ac- tivity of lipoxygenase （LOX）, a product of lipid peroxidatlon in membranes, and in- hibited ethylene biosynthesis, thus delaying the aging process and prolonging the storage life of papaya fruits. [Conclusion] The results will provide a theoretical basis for analvzina the key factors controllinq postharvest maturity and aging of papaya fruits.

Effects of 1-MCP on Ethylene Synthesis and Metabolismof Apple During Storage

Red Fuji apple(Malus domestica Borkh var. Red Fuji)fruits were used to study the effect of 1-MCP on ethylene biosynthesis metabolism during storage. The results showed that 1-MCP maintained the firmness and inhibited the respiration rate, LOX activity and ethylene production rate of fruits. Further study indicated that 1-MCP inhibited ACS(ACC synthase)activity from the 15th day, increased ACC accumulation, and delayed the appearance of ACO(ACC oxidase)activity peak. The increase of protein kinase activity was also inhibited by 1-MCP during fruit ethylene climacteric time.

Ethylene-inhibiting compound 1-MCP delays leaf senescence in cotton plants under abiotic stress conditions

Cotton （Gossypium hirsutum L.） plants produce more ethylene when subjected to abiotic stresses, such as high temperatures and drought, which result in premature leaf senescence, reduced photosynthetic efficiency, and thus decreased yield. This study was conducted to test the hypothesis that the ethylene-inhibiting compound 1-methylcyclopropene （I-MCP） treatment of cotton plants can delay leaf senescence under high temperature, drought, and the aging process in controlled environ- mental conditions. Potted cotton plants were exposed to 1-MCP treatment at the early square stage of development. The protective effect of 1-MCP against membrane damage was found on older compared to younger leaves, indicating 1-MCP could lower the stress level caused by aging. Application of 1-MCP resulted in reduction of lipid peroxidation, membrane leakage, soluble sugar content, and increased chlorophyll content, in contrast to the untreated plants under heat stress, suggesting that 1-MCP treatment of cotton plants may also have the potential to reduce the effect of heat stress in terms of delayed senescence. Application of 1-MCP caused reductions of lipid peroxidation, membrane leakage, and soluble sugar content, together with increases in water use efficiency （WUE）, water potential, chlorophyll content, and fluorescence quantum efficiency, compared to the untreated plants under drought, suggesting that 1-MCP treatment of cotton plants may also have the ability to reduce the level of stress under drought conditions. In conclusion, 1-MCP treatment of cotton should have the potential to delay senescence under heat and drought stress, and the aging process. Additionally, 1-MCP is more effective under stress than under non-stress conditions.

Relationships of Ethylene Evolution Rate and 1-Aminocylopropane-1-Carboxylic Acid Concentration in Grains during Filling Period with Appearance Quality of Rice

To elucidate the relationship between ethylene evolution from the grains and the appearance quality of rice, ten different rice genotypes were used to determine the ethylene evolution rate, 1-aminocylopropane-1-carboxylic acid （ACC） concentration in grains during grain filling and the appearance quality of rice, and the effects of chemical regulators on concentrations of ethylene and ACC in the grains during grain filling were also investigated to verify the roles of ethylene in the rice quality formation. The ethylene evolution rates and ACC concentrations in grains during the mid and late grain filling stages were very significantly and positively correlated with chalky kernel percentage and chalkiness. The cultivars with a low ACC concentration in grains exhibited a close amyloplast arrangement and small space between starch granules, whereas those with a high ACC concentration in grains showed a loose arrangement and wide space between the granules. Application of 1 μmol/L ACC to panicles at mid and late grain filling stages significantly loosened amyloplast arrangement and increased chalky kernel percentage, chalky area and chalkiness, and the results were reversed when 1 μmol/L amino-ethoxyvinylglycine, an inhibitor of ACC synthesis enzyme, was applied to panicles. A practice of moderate dry-wet alternate irrigation reduced ethylene evolution and ACC concentration in grains and thereby reduced chalkiness. The results suggested that ethylene and ACC in grains play an important role in the endosperm structure and appearance quality of rice, and the appearance quality would be improved by reducing ethylene evolution and ACC in grains through either variety breeding and selection, or chemical regulations or cultivation techniques.

Three New Zn(Ⅱ)/Cd(Ⅱ) Coordination Polymers Constructed with 2-Mercaptonicotinic Acid and 1,2-Di(4-pyridyl)ethylene: Syntheses and Structure Analysis

Three new Zn（Ⅱ）/Cd（Ⅱ） coordination polymers based on 2-mercaptonicotinic acid （H2mna） with 1,2-di（4-pyridyl）ethylene （dpe） introduced as a bridging ligand have been synthesized via hydrothermal method and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. As reported in this paper, [Zn2（dpe）0.5（mna）2] （1） can be classified as a two-dimensional layer structure in which the 1D chain composed of Zn（Ⅱ） and mna ligands is bridged by dpe ligands, while the complex named [Zn4（dpe）4（mna）4] （2） is a tetra-nuclear cluster compound. These two compounds are further extended to three-dimensional structures by hydrogen bonds along with C–H…π and π…π interactions. Compound 3 with general formular [Cd2（dpe）0.5（mna）2]·H2O belongs to a three-dimensional porous structure in which the 2D metal layers formed by the coordination of Cd（Ⅱ） and mna ligands are connected with the bridging of dpe ligands.

乙烯和1-甲基环丙烯对椪柑采后浮皮及白皮层细胞壁代谢的影响

【目的】浮皮是宽皮柑橘Citrus reticulata果实在成熟后期或采后储藏过程中普遍发生的一种生理性障碍。椪柑C.reticulata‘Ponkan’在采后储藏中极易发生浮皮,严重影响商品价值。通过采后处理,为椪柑果实采后浮皮的防范、储藏保鲜技术提供理论依据。【方法】利用乙烯和1-甲基环丙烯(1-MCP)处理椪柑采后果实,测定椪柑在储藏期间果实主要品质指标及浮皮指数的变化,分析果皮白皮层细胞形态和生理变化特征。【结果】①乙烯处理促进了储藏期果实可溶性固形物质量分数的提高;加速了果皮白皮层细胞密度、纤维素质量分数、果胶质量分数的下降,促使木质素质量分数及细胞壁降解酶(纤维素酶、果胶酯酶、多聚半乳糖醛酸酶)活性上升。②1-MCP处理减缓了果皮白皮层细胞密度及纤维素质量分数下降;延缓了木质素质量分数及细胞壁降解酶(纤维素酶、果胶酯酶、多聚半乳糖醛酸酶)活性上升;减缓了椪柑果实浮皮指数的上升。【结论】乙烯处理可加速椪柑果实采后生理代谢水平,加重果实浮皮的发生。1-MCP处理可抑制储藏期果皮的生理代谢水平,减轻浮皮障碍的发生。生产中可通过乙烯和1-MCP处理来控制椪柑果实剥皮的难易程度。

黑莓1-氨基环丙烷-1-羧酸氧化酶基因RuACO 1a和RuACO 1b的克隆及功能鉴定

基于前期黑莓(Rubus spp.)品种‘Navaho’果实转录组测序结果,通过反转录PCR克隆获得2个1-氨基环丙烷-1-羧酸氧化酶(ACO)基因,命名为RuACO 1a和RuACO 1b。结果表明:RuACO 1a和RuACO 1b的开放阅读框(ORF)长度分别为939和918 bp,分别含有4和3个外显子。系统进化分析结果显示RuACO1a和RuACO1b与月季(Rosa chinensis Jacq.)、蕨麻〔Argentina anserina(Linn.)Rydb.〕和野草莓(Fragaria vesca Linn.)ACO1蛋白的亲缘关系均较近,且分别属于蔷薇科(Rosaceae)植物中2类ACO1蛋白。RuACO 1a在果实着色后28 d响应乙烯利诱导,其相对表达量急剧升高,而RuACO 1b在果实着色后21 d响应乙烯利诱导,早于RuACO 1a。脱落酸处理后,RuACO 1a和RuACO 1b的相对表达量在果实着色后14和28 d较高。RuACO 1a和RuACO 1b具有组织表达特异性,RuACO 1a在幼果、花蕾和花中的相对表达量较高,RuACO 1b在幼果和幼根中的相对表达量较高。与野生型相比,RuACO 1a和RuACO 1b过量表达转基因拟南芥〔Arabidopsis thaliana(Linn.)Heynh.〕植株均表现为叶片中叶绿素相对含量和氮含量升高、开花和角果成熟提前、ACO含量升高。综上所述,黑莓RuACO 1a和RuACO 1b基因均促进拟南芥角果提前成熟。

Molecular Cloning and Characterization of Carnation EBF1 Gene During Flower Senescence and upon Ethylene Exposure and Sugar

A cDNA clone encoding a putative EBF-like protein （DCEBF1）was obtained from total RNA isolated from senescing carnation （Dianthus caryophyllus L.） petals using reverse transcription PCR and rapid-amplification of cDNA ends techniques. The cDNA contained an open reading frame of l 878 bp corresponding to 625 amino acids. Results of Northern blot indicated DCEBFI expression was enhanced by endogenous and exogenous ethylene, and was inhibited by STS in petals and ovaries. Upon wounding treatment, DCEBF1 showed a quick increase in mRNA accumulation which was positively correlated with the increase in ethylene production. The levels of DCEBF1 mRNA increased in both petals and ovaries by sucrose treatment compared with the control.

Synthesis of 1-Octene Oligomer by Rare Earth Coordination Catalyst

The polymerization of 1-octene with Nd(P_(204))_3-AlEt_3 catalyst has been successfully carried out for the first time.Some features of polymerization of 1-octene are described.The 1-octene oligomer prepared has an average molecular weight of about 10~3 with molecular weight distribution of about 2.It has a terminal double bond,which can be transferred into terminal carboxy group by direct oxidation with KMnO_4 in acidic solution, and then can be esterified with polyglycol.

Revealing the roles of components in glucose selective hydrogenation into 1,2-propanediol and ethylene glycol over Ni-MnO_x-ZnO catalysts

MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the roles of nickel, ZnO and MnOx were investigated. The results show that nickel provided a new pathway of glucose to sorbitol and played an important role in the hydrogenation of C3 intermediates to 1,2-propanediol(1,2-PDO). The high yield of 1, 2-PDO was attributed to effective C–C bond cleavage performance of ZnO support promoted by MnOx. ZnO and MnOx contribute to the conversion of glycerol to lactic acid(LA) and LA to 1, 2-PDO, respectively. A concise pathway for hydrogenation of glucose over Ni-based catalyst was proposed.

Strong influences of polymerization temperature on ethylene/1-hexene copolymerization catalyzed by (2-PhInd)_2ZrCl_2/methyl aluminoxane

Ethylene/1-hexene was copolymerized by an unbridged zirconocene, (2-PhInd)2ZrCl2/MAO (methyl aluminoxane) at 0 °C and 50 °C respectively. High copolymerization activity and 1-hexene incorporation were observed at 0 °C, with the co- polymer formed having random sequence distribution and narrow molecular weight distribution. Ethylene polymerization at 50 °C showed high activity, but copolymerization at 50 °C showed much lower activity, which decreased sharply with increasing 1-hexene concentration in the monomer feed. Copolymer formed at 50 °C showed blocky sequence distribution and broad mo- lecular weight distribution. A mechanism model based on ligand rotation hindered by the propagation chain has been proposed to qualitatively explain the observed phenomena.

Reaction of 1,1-Di-p-methoxyphenyl-2,2-dinitroethylene and 1,1-Di-O-methoxyphenyl-2,2-dinitroethylene with 1-Benzyl-1,4-dihydroni-cotinamide:Evidence for Concerted Electron-hydrogen Atom Trans-fer Mechanism

Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronico- tinamide (BNAH) in deaerated acetonitrile to give 1, 1-di-p-methoxyphenyl-2, 2-dinitroethane, while 1, 1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism.

COPOLYMERIZATION OF 1-OCTENE WITH STYRENE BY RARE EARTH COORDINATION CATALYSTS

The copolymerization of l-octene with styrene catalyzed by rare earth coordination catalysts has been studied for the first time. Some features and kinetic behavior are described. The overall activation energy of the copolymerization was 22.2 KJ/mol and the copolymerization rate could be expressed as R_p=K_p [Nd] [M]~2. (=1.68×10^(-3) L^2/mol^2. S, 50℃, [Oct]/[St]=1). The catalytic activity of various rare earth elements in Ln (naph)_3 for the copolymerization was compared and shows the following sequence: Dy, Y, Yb>Ho>Sm, Gd, Nd>Pr>Ce>La>Tm. Both monomers of l-octene and styrene in the copolymerization by Nd (naph)_3-AlEt_3 have the tendency of constant proportion copolymerization. The structure of the copolymers was studied by ~1H-NMR.

Thermoregulated Organic Biphasic Hydrogenation of 1-Octene Catalyzed by Ru/PETPP Complex

Thermoregulated organic biphasic system composed of triethylene glycol monomethyl ether （TGME） and n-heptane was first applied to the hydrogenation of 1-octene. Under the optimal conditions： P（H2）=5.0MPa, T=80℃, t=3h, 1-octene/Ru=1000 （molar ratio）, the yield of n-octane reached up to 99.6%. Furthermore, the simply decanted catalyst could be reused for 10 times without apparent loss of catalytic activity.

STUDY ON THE MECHANISM OF 1-OCTENE ZIEGLER-NATTA POLYMERIZATION BASED ON THE NUMBER OF ACTIVE CENTERS

The number of active centers (C_p)-t and k_p-t profiles of Solvay type TiCl_3 - AlR_3 (R=C_2H_5, i-C_4H_9) or Stauffer AA TiCl_3-Al (C_2H_5)_3 catalyzed 1-octene polymerization were determined by using an acetyl chloride quenching method as well as kinetic data. The results show that in the studied systems k_p decreases when C_p increases, indicating the presence of two or more types of different active centers. The C_(p^(-t)) plots of the Solvay TiCl_3-AlR_3 systems show the presence of both stable active centers and unstable centers which decay in the polymerization process. The phenomena are explained based on a model of active center plurality. The increases of C_p in the induction periods are also discussed.

High Temperature and the Ethylene Antagonist 1-Methylcyclopropene Alter Ethylene Evolution Patterns,Antioxidant Responses,and Boll Growth in Gossypium hirsutum

The cotton (Gossypium hirsutum L.) crop experiences high temperatures during flowering and boll development, but information regarding the impact of ethylene inhibition and high temperature on early boll development is limited. The objective of this study was to determine the effects of high temperature and the anti-ethylene compound 1-methylcy-cloprone (1-MCP) on G. hirsutum boll development. Treatments consisted of temperature regime (38/20?C and 30/ 20?C), 1-MCP treatment, and days past anthesis (DPA). High temperature decreased ethylene synthesis by 61% at 2 DPA, and 1-MCP caused a 40% decrease in ethylene production at 1 DPA. Glutathione reductase activity increased under high temperature, whereas superoxide dismutase activity (SOD) and membrane peroxidation (malondialdehyde content) remained unchanged. 1-MCP treatment did not affect GR activity in developing bolls. High temperature and 1-MCP treatment increased the weight of cotton bolls collected 8 DPA with an increase of 0.7 and 1 g, respectively. We propose that increased GR activity in bolls exposed to high temperature may mitigate oxidative damage. Additionally, we conclude that ethylene inhibition (either high temperature or 1-MCP-induced) immediately after flowering (1 or 2 DPA) could potentially have positive impacts on early boll growth.

^(13)C NMR Study of Ethylene/propylene/octene-1 Terpolymers Synthesized with TiCl_4/MgCl_2/ i -Bu_3Al as the Catalyst

The theory of chemical shift effect of substituent was applied to the assignment of the 13 C NMR spectra of the ethylene/propylene and ethylene/octene 1 copolymers. Using the parameters derived above and the DEPT technique, we then entirely assigned the 13 C NMR spectra of the ethylene/propylene/octene 1 terpolymers synthesized in the presence of the same heterogeneous supported Ziegler Natta catalyst, TiCl 4/MgCl 2/ i Bu 3Al. The present paper also covers the terpolymer composition and the monomer sequence distributions of a series of ethylene/propylene/octene 1 terpolymers.