标记性理论是语言学研究领域非常广泛的一个理论成果,有语言学家将之应用在人称代词的分析上,但从系统功能语法中语域三要素之一的基调为审视角度的尚为数不多,文章尝试在基调中权势量和共聚量的框架下研究第一人称复数代词在实际语料...标记性理论是语言学研究领域非常广泛的一个理论成果,有语言学家将之应用在人称代词的分析上,但从系统功能语法中语域三要素之一的基调为审视角度的尚为数不多,文章尝试在基调中权势量和共聚量的框架下研究第一人称复数代词在实际语料———英文原著Moment in Peking中标记性地使用为单数的情况,并指出了标记性用法在反映谈话者关系及传递交流目的上所起的特殊作用。展开更多
Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning cal...Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry(DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10 T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope(POM) and X-ray diffraction(XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10 T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10 T, the crystallization rate was increased with the addition of the sebacic acid comonomer.展开更多
In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can oc...In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly.展开更多
The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV...The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV/Vis regime as well as the linear polarizabiliti y and nonlinear hyperpolarizability are calculated by using quantum chemical ab initio and semiempirical methods. The relationship of its optical property to el ectric field is obtained. Some physical mechanism of electric field effect on mo lecular optical property is discussed by means of electron distribution and intr amolecular charge transfer.展开更多
In a recent letter [H.F. Wang, X. Ji, and S. Zhang, Phys. Lett. A 358 (2006) 11], an improvement of the multiparty quantum secret splitting and quantum state sharing protocol [F.G. Deng, et al., Phys. Lett. A 354 (...In a recent letter [H.F. Wang, X. Ji, and S. Zhang, Phys. Lett. A 358 (2006) 11], an improvement of the multiparty quantum secret splitting and quantum state sharing protocol [F.G. Deng, et al., Phys. Lett. A 354 (2006) 190.] was presented. We study the security of the improved protocol and find that two or more dishonest participants may recover the secret from the dealer. Hence we further modify the improved protocol, which make it stand against this kind of attack.展开更多
In this investigation we report on the synthesis and characterisation of certain polyester elastomers namely as Poly(Sorbitol succinate-co-ethylene glycol succinate) (PSSEG), Poly(sorbitol succinate-co-butane dio...In this investigation we report on the synthesis and characterisation of certain polyester elastomers namely as Poly(Sorbitol succinate-co-ethylene glycol succinate) (PSSEG), Poly(sorbitol succinate-co-butane diol succinate) (PSSBD) and Poly(sorbitol succinate-co-hexane diol succinate) (PSSHD) by carrying out catalyst free melt polycondensation.. The synthesised polyesters were characterised by solubility, FT-IR, -H NMR and 13C NMR spectral methods. The thermal properties were analysed by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties evaluated for the polyester films in the tensile mode shows that the polymer has characteristics of elastomers and stiff thermosets. We demonstrate that the chemical structure, physical integrity and mechanical property of synthesized copolyester can be controlled by simply changing the monomers and suit them for the requirements of various biomedical and soft tissue engineering applications.展开更多
A series of novel copolymers were successfully synthesized by ring-opening polymerization (ROP) of 3 (S)-methyl-morpholine-2,5-dione (MMD) and 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) using stan- no...A series of novel copolymers were successfully synthesized by ring-opening polymerization (ROP) of 3 (S)-methyl-morpholine-2,5-dione (MMD) and 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) using stan- nous octoate as catalyst. The copolymers were characterized by means of ~H-NMR and FT-IR spectroscopy. Gel permeation chromatography (GPC) test shows that the average-number relative molecular mass and average-weight rela- tive molecular mass slightly increase with the increase of MBC content in feed. The results of differential scanning calorimetry (DSC) demonstrate that the glass transition temperature of copolymers increases with the increase of MBC content in copolymers. The copolymers of MMD and MBC are amorphous copolymers, as indicated by DSC results, while the homopolymer of MMD is semicrystalline.展开更多
Polypropylene(PP)with different contents of the second generation hyperbranched polyester(HBP)is prepared by melt blending method.The non-isothermal crystallization kinetics of PP and PP/HBP blends is investigated und...Polypropylene(PP)with different contents of the second generation hyperbranched polyester(HBP)is prepared by melt blending method.The non-isothermal crystallization kinetics of PP and PP/HBP blends is investigated under differential scanning calorimetry(DSC).The Mo equation is used to analyze the DSC data.The results show that the Mo theory is suitable for crystallization kinetics of the blends.Fast cooling rate is not good for crystallizing and nucleating.The values of half crystallization time(t1/2),crystallization enthalpy(ΔHc)and temperature range(ΔT)of PP/HBP blends decrease when HBP is added.The required cooling rate of PP is higher than that of PP/HBP blends in order to reach the same relative crystallinity.Crystallization rate increases with the addition of HBP.The crystallization rate reaches a maximum when the content of HBP is 5%.In addition,the activation energies of PP and PP/HBP blends are calculated by Kissinger equation,revealing that the content of HBP has a little effect on the crystallization activation energy.展开更多
Plant growth-promoting rhizobacteria (PGPR) are considered to be the most promising agents for cash crop production via increasing crop yields and decreasing disease occurrence. The Bacillus amyloliquefaciens strain...Plant growth-promoting rhizobacteria (PGPR) are considered to be the most promising agents for cash crop production via increasing crop yields and decreasing disease occurrence. The Bacillus amyloliquefaciens strain W19 can produce secondary metabolites (iturin and bacillomycin D) effectively against Fusarium oxysporum f. sp. cubense (FOC). In this study, the ability of a bio-organic fertilizer (BIO) containing strain W19 to promote plant growth and suppress the Fusarium wilt of banana was evaluated in both pot and field experiments. The results showed that application of BIO significantly promoted the growth and fruit yield of banana while suppressing the banana Fusariurn wilt disease. To further determine the beneficial mechanisms of the strain, the colonization of green fluorescent protein-tagged strain W19 on banana roots was observed using confocal laser scanning microscopy and scanning electron microscopy. The effect of banana root exudates on the formation of biofilm of strain W19 indicated that the banana root exudates may enhance colonization. In addition, the strain W19 was able to produce indole-3-acetic acid (IAA), a plant growth-promoting hormone. The results of these experiments revealed that the application of strain W19-enriched BIO improved the banana root colonization of strain W19 and growth of banana and suppressed the Fusarium wilt. The PGPR strain W19 can be a useful biocontrol agent for the production of banana under field conditions.展开更多
Impact polypropylene copolymer (IPC), named polypropylene catalloy, not only possesses excellent impact property, but also presents good rigidity. Its superior performances result from the complicated composition and ...Impact polypropylene copolymer (IPC), named polypropylene catalloy, not only possesses excellent impact property, but also presents good rigidity. Its superior performances result from the complicated composition and microstructure. In the present article, recent progress in the studies on microstructure, morphology, crystallization and rheological behavior of IPC is summarized, and findings of the authors and their collaborators are reported. In general, IPC is divided into three components, i.e., ethylene-propylene random copolymer (EPR), a series of different segment lengths ethylene-propylene copolymer (EbP) and propylene homopolymer. The reasonable macromolecular structures of EbP and a multilayered core-shell model of dispersed phase structure in IPC were proposed, in which the dispersed phase consists of an outer EbP shell, an inner EPR layer and an EbP core. It is found that the annealing at melt-state may lead to an abnormal phase inversion, and the phase inversion disappears when temperature cools down to room temperature. The cause of phase inversion is ascribed to the existence of EbP component, which results in the stronger activity of the dispersed phase. The crystalline structure and morphologic results confirm the formation of β-iPP in IPC. Furthermore, it is found that the ethylene content in IPC and cooling rate of the samples have an important influence on the formation of β-iPP. Based on the crystallization kinetics analyzed by Lauritzen-Hoffman theory, crystallization behavior of different IPC samples is discussed and it is proposed that the dilution effect of ethylene propylene copolymer has a more remarkable influence on surface nucleation than on crystal growth. In addition, annealing at high temperature can result in the changes of chain structure for IPC, and this instability is ascribed to the oxidative degradation and crosslink reaction mainly in iPP component.展开更多
A kind of amphiphilic rod-coil diblock copolymer consisting both of tetraaniline(TAni)and polyethylene glycol(PEG)blocks,TAni-b-PEG,was synthesized.The diblock copolymer shows excellent electrochromic properties,espec...A kind of amphiphilic rod-coil diblock copolymer consisting both of tetraaniline(TAni)and polyethylene glycol(PEG)blocks,TAni-b-PEG,was synthesized.The diblock copolymer shows excellent electrochromic properties,especially,in switching time and coloration efficiency compared with tetraaniline.TAni-b-PEG is able to self-assemble into spherical structure,which is attributed to the formation of conducting channels and increase of ion-exchange capacity of TAni-b-PEG,implying that a block copolymer with electrochromic block and high ionic conductive block simultaneously possesses improving electrochromic properties.展开更多
The transition-metal-catalyzed copolymerization of olefins with polar comonomers is a direct strategy to access polar-functionalized polyolefins in an economical manner.Due to the intrinsic poisoning effect of polar g...The transition-metal-catalyzed copolymerization of olefins with polar comonomers is a direct strategy to access polar-functionalized polyolefins in an economical manner.Due to the intrinsic poisoning effect of polar groups towards Lewis acidic metal centers and the drastic reactivity differences of polar comonomers versus non-polar olefins,it is challenging to develop catalysts that provide the desired polymer molecular weight,comonomer incorporation,and activity.In this contribution,we tackle this issue from a comonomer perspective using 5,6-disubstituted norbornenes,which are highly versatile,easily accessible,inexpensive,and capable of introducing two functional groups in a single insertion.More importantly,they are only mildly poisoning due to the presence of long spacers between double bonds and polar groups,and are not prone to b-hydride elimination due to their cyclic structures.As strong pdonors,they can competitively bind to metal centers versus olefins.Indeed,phosphine-sulfonate palladium catalysts can catalyze the copolymerization of ethylene with 5,6-disubstituted norbornenes and simultaneously achieve a high polymerization activity,copolymer molecular weight,and comonomer incorporation.The practicality of this system was demonstrated by studying the properties of the resulting polymers,copolymerization in hydrocarbon solvents or in bulk,recovery/utilization of unreacted comonomer,molecular weight modulation,and large-scale synthesis.展开更多
The charge-doping effect on the geometric and the electronic structures of organosilicon oligomers nSix(C=C)+y has been studied using density functional theory. Charge-doping can significantly lower the excitation ene...The charge-doping effect on the geometric and the electronic structures of organosilicon oligomers nSix(C=C)+y has been studied using density functional theory. Charge-doping can significantly lower the excitation energies. Interchain hole hopping mainly occurs between the π-conjugated units. A doped nSix(C=C)+y oligomer can undergo a structural rearrangement. The simulated UV/vis absorption peak of the rearranged structure is located at higher energy than the non-rearranged one. The hole transfer rate is significantly decreased if a doped molecule undergoes a rearrangement. These results offer a basis to explain previously observed experimental phenomena.展开更多
Ion-induced charge-transfer states in conjugated polyelectrolytes were experimentally investigated by Justin M.Hodgkiss and his co-workers [J Am Chem Soc,2009,131(25):8913].In this work,charged and neutral conjugated ...Ion-induced charge-transfer states in conjugated polyelectrolytes were experimentally investigated by Justin M.Hodgkiss and his co-workers [J Am Chem Soc,2009,131(25):8913].In this work,charged and neutral conjugated polyelectrolytes were further studied with quantum chemistry methods.The calculation result shows that the absorption spectra are roughly in visible and ultraviolet light regions,and the two absorption peaks are located in the wavelength span 300-400 nm for charged polyelectrolytes.However,in neutral conjugated polyelectrolytes,the peaks of the absorption spectra showed a blue shift compared with those of the charged polyelectrolytes.Charge transfer (CT) properties of the studied compounds were also investigated with both the three-dimensional real-space analysis method of transition and charge difference densities,and the two-dimensional real-space analysis method of transition density matrices based on the simulated absorption spectra.The calculation results revealed the charge transfer in conjugated polyelectrolytes on the excitation states.展开更多
文摘标记性理论是语言学研究领域非常广泛的一个理论成果,有语言学家将之应用在人称代词的分析上,但从系统功能语法中语域三要素之一的基调为审视角度的尚为数不多,文章尝试在基调中权势量和共聚量的框架下研究第一人称复数代词在实际语料———英文原著Moment in Peking中标记性地使用为单数的情况,并指出了标记性用法在反映谈话者关系及传递交流目的上所起的特殊作用。
基金Supported by the National Science and Technology Support Program of China(No.2013BAE02B01)the Special Project on the Integration of Industry,Education and Research of Guangdong Province(No.2013B090500003)the Commissioner Workstation Project of Guangdong Province(No.2014A090906002)
文摘Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry(DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10 T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope(POM) and X-ray diffraction(XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10 T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10 T, the crystallization rate was increased with the addition of the sebacic acid comonomer.
基金Supported in part by National Natural Science Foundation of China under Grant Nos.10275029 and 10675054
文摘In the framework of relativistic mean field theory, the condensations of K^- and K^0 in neutron star matter including baryon octet and △ quartet are studied. We find that in this case K^- and K^0 condensations can occur at relative shallow optical potential depth of K^ from -80 MeV to -160 MeV. Both K^- and K^0 condensations favor the appearances of △ resonances. With K^- condensations all the △ quartet can appear well inside the maximum mass stars. The appearances of △ resonances change the composition and distribution of particles at high densities. The populations of △ resonances can enhance K^- condensation. It is found that in the core of massive neutron stars, neutron star matter includes rich particle species, such as antikaons, baryon octet, and △ quartet. In the presence of △ resonances and K^- condensation, the EOS becomes softer and results in smaller maximum mass stars. Furthermore the impact of antikaon condensations, hyperons, and △ resonances on direct Urca process with nucleons is also discussed briefly.
基金Natural Science Foundation from Shandong Province of China (Y2002A06)
文摘The organic π-conjugate d polymers are of major interest materials for the use in electro-optical and no nlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV/Vis regime as well as the linear polarizabiliti y and nonlinear hyperpolarizability are calculated by using quantum chemical ab initio and semiempirical methods. The relationship of its optical property to el ectric field is obtained. Some physical mechanism of electric field effect on mo lecular optical property is discussed by means of electron distribution and intr amolecular charge transfer.
基金Supported by National Natural Science Foundation of China under Grant No.60903152National Laboratory for Modern Communications Science Foundation of China under Grant No.9140C1101010601+3 种基金the Beijing Natural Science Foundation under Grant No.4072020a Key Project of Fujian Provincial Universities - Information Technology Research Based on Mathematics the Fujian Province Natural Science Foundation under Grant No.2008J0013the Foundation of Fujian Education Bureau under Grant No.JA08044
文摘In a recent letter [H.F. Wang, X. Ji, and S. Zhang, Phys. Lett. A 358 (2006) 11], an improvement of the multiparty quantum secret splitting and quantum state sharing protocol [F.G. Deng, et al., Phys. Lett. A 354 (2006) 190.] was presented. We study the security of the improved protocol and find that two or more dishonest participants may recover the secret from the dealer. Hence we further modify the improved protocol, which make it stand against this kind of attack.
文摘In this investigation we report on the synthesis and characterisation of certain polyester elastomers namely as Poly(Sorbitol succinate-co-ethylene glycol succinate) (PSSEG), Poly(sorbitol succinate-co-butane diol succinate) (PSSBD) and Poly(sorbitol succinate-co-hexane diol succinate) (PSSHD) by carrying out catalyst free melt polycondensation.. The synthesised polyesters were characterised by solubility, FT-IR, -H NMR and 13C NMR spectral methods. The thermal properties were analysed by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties evaluated for the polyester films in the tensile mode shows that the polymer has characteristics of elastomers and stiff thermosets. We demonstrate that the chemical structure, physical integrity and mechanical property of synthesized copolyester can be controlled by simply changing the monomers and suit them for the requirements of various biomedical and soft tissue engineering applications.
基金Supported by Chinese Program for New Century Excellent Talents in University "NCET",Ministry of Education of P.R. China(No.2008DFA51170)
文摘A series of novel copolymers were successfully synthesized by ring-opening polymerization (ROP) of 3 (S)-methyl-morpholine-2,5-dione (MMD) and 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) using stan- nous octoate as catalyst. The copolymers were characterized by means of ~H-NMR and FT-IR spectroscopy. Gel permeation chromatography (GPC) test shows that the average-number relative molecular mass and average-weight rela- tive molecular mass slightly increase with the increase of MBC content in feed. The results of differential scanning calorimetry (DSC) demonstrate that the glass transition temperature of copolymers increases with the increase of MBC content in copolymers. The copolymers of MMD and MBC are amorphous copolymers, as indicated by DSC results, while the homopolymer of MMD is semicrystalline.
基金Supported by the Youths Foundation of Wuhan Institute of Technology(Q200902)the Graduate Innovative Fund of Wuhan Institute of Technology(CX201101)
文摘Polypropylene(PP)with different contents of the second generation hyperbranched polyester(HBP)is prepared by melt blending method.The non-isothermal crystallization kinetics of PP and PP/HBP blends is investigated under differential scanning calorimetry(DSC).The Mo equation is used to analyze the DSC data.The results show that the Mo theory is suitable for crystallization kinetics of the blends.Fast cooling rate is not good for crystallizing and nucleating.The values of half crystallization time(t1/2),crystallization enthalpy(ΔHc)and temperature range(ΔT)of PP/HBP blends decrease when HBP is added.The required cooling rate of PP is higher than that of PP/HBP blends in order to reach the same relative crystallinity.Crystallization rate increases with the addition of HBP.The crystallization rate reaches a maximum when the content of HBP is 5%.In addition,the activation energies of PP and PP/HBP blends are calculated by Kissinger equation,revealing that the content of HBP has a little effect on the crystallization activation energy.
基金supported by the National Natural Science Foundation of China (Nos. 31572212 and 31372142)the National Key Basic Research Program of China (No. 2015CB150503)+5 种基金the Chinese Ministry of Science and Technology (No. 2013AA102802)the Natural Science Foundation of Jiangsu Province, China (No. BK20150059)the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions of Chinathe 111 Project of China (No. B12009)the National Training Program of Innovation and Entrepreneurship for Undergraduates of China (No. 201410307089)the "Qing Lan" Project of China
文摘Plant growth-promoting rhizobacteria (PGPR) are considered to be the most promising agents for cash crop production via increasing crop yields and decreasing disease occurrence. The Bacillus amyloliquefaciens strain W19 can produce secondary metabolites (iturin and bacillomycin D) effectively against Fusarium oxysporum f. sp. cubense (FOC). In this study, the ability of a bio-organic fertilizer (BIO) containing strain W19 to promote plant growth and suppress the Fusarium wilt of banana was evaluated in both pot and field experiments. The results showed that application of BIO significantly promoted the growth and fruit yield of banana while suppressing the banana Fusariurn wilt disease. To further determine the beneficial mechanisms of the strain, the colonization of green fluorescent protein-tagged strain W19 on banana roots was observed using confocal laser scanning microscopy and scanning electron microscopy. The effect of banana root exudates on the formation of biofilm of strain W19 indicated that the banana root exudates may enhance colonization. In addition, the strain W19 was able to produce indole-3-acetic acid (IAA), a plant growth-promoting hormone. The results of these experiments revealed that the application of strain W19-enriched BIO improved the banana root colonization of strain W19 and growth of banana and suppressed the Fusarium wilt. The PGPR strain W19 can be a useful biocontrol agent for the production of banana under field conditions.
基金supported by the National Basic Research Program of China (2005CB623800)National Natural Science Foundation of China (51173157)Natural Science Foundation of Zhejiang Province (Y4100314)
文摘Impact polypropylene copolymer (IPC), named polypropylene catalloy, not only possesses excellent impact property, but also presents good rigidity. Its superior performances result from the complicated composition and microstructure. In the present article, recent progress in the studies on microstructure, morphology, crystallization and rheological behavior of IPC is summarized, and findings of the authors and their collaborators are reported. In general, IPC is divided into three components, i.e., ethylene-propylene random copolymer (EPR), a series of different segment lengths ethylene-propylene copolymer (EbP) and propylene homopolymer. The reasonable macromolecular structures of EbP and a multilayered core-shell model of dispersed phase structure in IPC were proposed, in which the dispersed phase consists of an outer EbP shell, an inner EPR layer and an EbP core. It is found that the annealing at melt-state may lead to an abnormal phase inversion, and the phase inversion disappears when temperature cools down to room temperature. The cause of phase inversion is ascribed to the existence of EbP component, which results in the stronger activity of the dispersed phase. The crystalline structure and morphologic results confirm the formation of β-iPP in IPC. Furthermore, it is found that the ethylene content in IPC and cooling rate of the samples have an important influence on the formation of β-iPP. Based on the crystallization kinetics analyzed by Lauritzen-Hoffman theory, crystallization behavior of different IPC samples is discussed and it is proposed that the dilution effect of ethylene propylene copolymer has a more remarkable influence on surface nucleation than on crystal growth. In addition, annealing at high temperature can result in the changes of chain structure for IPC, and this instability is ascribed to the oxidative degradation and crosslink reaction mainly in iPP component.
基金the National Natural Science Foundation of China(21174009,21574003)
文摘A kind of amphiphilic rod-coil diblock copolymer consisting both of tetraaniline(TAni)and polyethylene glycol(PEG)blocks,TAni-b-PEG,was synthesized.The diblock copolymer shows excellent electrochromic properties,especially,in switching time and coloration efficiency compared with tetraaniline.TAni-b-PEG is able to self-assemble into spherical structure,which is attributed to the formation of conducting channels and increase of ion-exchange capacity of TAni-b-PEG,implying that a block copolymer with electrochromic block and high ionic conductive block simultaneously possesses improving electrochromic properties.
基金the National Natural Science Foundation of China(52025031,21690071,U19B6001,and U1904212)K.C.Wong Education Foundation。
文摘The transition-metal-catalyzed copolymerization of olefins with polar comonomers is a direct strategy to access polar-functionalized polyolefins in an economical manner.Due to the intrinsic poisoning effect of polar groups towards Lewis acidic metal centers and the drastic reactivity differences of polar comonomers versus non-polar olefins,it is challenging to develop catalysts that provide the desired polymer molecular weight,comonomer incorporation,and activity.In this contribution,we tackle this issue from a comonomer perspective using 5,6-disubstituted norbornenes,which are highly versatile,easily accessible,inexpensive,and capable of introducing two functional groups in a single insertion.More importantly,they are only mildly poisoning due to the presence of long spacers between double bonds and polar groups,and are not prone to b-hydride elimination due to their cyclic structures.As strong pdonors,they can competitively bind to metal centers versus olefins.Indeed,phosphine-sulfonate palladium catalysts can catalyze the copolymerization of ethylene with 5,6-disubstituted norbornenes and simultaneously achieve a high polymerization activity,copolymer molecular weight,and comonomer incorporation.The practicality of this system was demonstrated by studying the properties of the resulting polymers,copolymerization in hydrocarbon solvents or in bulk,recovery/utilization of unreacted comonomer,molecular weight modulation,and large-scale synthesis.
基金supported by the National Natural Science Foundation of China (51073048)the Science Foundation for Leading Experts in Academy of Harbin City of China (2010RFJGG016)+1 种基金the Science Foundation of Heilongjiang Postdoctoral Grant of China (LBHQ07058)the Science Foundation for Elitists of Harbin University of Science and Technology
文摘The charge-doping effect on the geometric and the electronic structures of organosilicon oligomers nSix(C=C)+y has been studied using density functional theory. Charge-doping can significantly lower the excitation energies. Interchain hole hopping mainly occurs between the π-conjugated units. A doped nSix(C=C)+y oligomer can undergo a structural rearrangement. The simulated UV/vis absorption peak of the rearranged structure is located at higher energy than the non-rearranged one. The hole transfer rate is significantly decreased if a doped molecule undergoes a rearrangement. These results offer a basis to explain previously observed experimental phenomena.
基金supported by the National Natural Science Foundation of China (Grant Nos.11074210 and 20703032)the National Basic Research Project of China (Grant No.2009CB930703)
文摘Ion-induced charge-transfer states in conjugated polyelectrolytes were experimentally investigated by Justin M.Hodgkiss and his co-workers [J Am Chem Soc,2009,131(25):8913].In this work,charged and neutral conjugated polyelectrolytes were further studied with quantum chemistry methods.The calculation result shows that the absorption spectra are roughly in visible and ultraviolet light regions,and the two absorption peaks are located in the wavelength span 300-400 nm for charged polyelectrolytes.However,in neutral conjugated polyelectrolytes,the peaks of the absorption spectra showed a blue shift compared with those of the charged polyelectrolytes.Charge transfer (CT) properties of the studied compounds were also investigated with both the three-dimensional real-space analysis method of transition and charge difference densities,and the two-dimensional real-space analysis method of transition density matrices based on the simulated absorption spectra.The calculation results revealed the charge transfer in conjugated polyelectrolytes on the excitation states.