The study of oxide heteroepitaxy has been hindered by the issues of misfit strain and substrate clamping,which impede both the optimization of performance and the acquisition of a fundamental understanding of oxide sy...The study of oxide heteroepitaxy has been hindered by the issues of misfit strain and substrate clamping,which impede both the optimization of performance and the acquisition of a fundamental understanding of oxide systems.Recently,however,the development of freestanding oxide membranes has provided a plausible solution to these substrate limitations.Single-crystalline functional oxide films can be released from their substrates without incurring significant damage and can subsequently be transferred to any substrate of choice.This paper discusses recent advancements in the fabrication,adjustable physical properties,and various applications of freestanding oxide perovskite films.First,we present the primary strategies employed for the synthesis and transfer of these freestanding perovskite thin films.Second,we explore the main functionalities observed in freestanding perovskite oxide thin films,with special attention to the tunable functionalities and physical properties of these freestanding perovskite membranes under varying strain states.Next,we encapsulate three representative devices based on freestanding oxide films.Overall,this review highlights the potential of freestanding oxide films for the study of novel functionalities and flexible electronics.展开更多
Objective To study the alterations of FHIT gene and P16 gene in malignant transformed human bronchial epithelial cells induced by crystalline nickel sulfide using an immortal human bronchial epithelial cell line, and ...Objective To study the alterations of FHIT gene and P16 gene in malignant transformed human bronchial epithelial cells induced by crystalline nickel sulfide using an immortal human bronchial epithelial cell line, and to explore the molecular mechanism of nickel carcinogenesis. Methods 16HBE cells were treated 6 times with different concentrations of NiS in vitro, and the degree of malignant transformation was determined by assaying the anchorage-independent growth and tumorigenicity. Malignant transformed cells and tumorigenic cells were examined for alterations of FHIT gene and P16 gene using RT-PCR, DNA sequencing, silver staining PCR-SSCP and Western blotting. Results NiS-treated cells exhibited overlapping growth. Compared wkh that of negative control cells, soft agar colony formation efficiency of NiS-treated cells showed significant increases （P〈0.01） and dose-dependent effects. NiS-treated cells could form tumors in nude mice, and a squamous cell carcinoma was confirmed by histopathological examination. No mutation of exon 2 and exons 2-3, no abnormal expression in pl6 gene and mutation of FHIT exons 5-8 and exons 1-4 or exons 5-9 were observed in transformed cells and tumorigenic cells. However, aberrant transcripts or loss of expression of the FHIT gene and Fhit protein was observed in transformed cells and tumorigenic cells. One of the aberrant transcripts in the FHIT gene was confirmed to have a deletion of exon 6, exon 7, exon 8, and an insertion of a 36 bp sequence replacing exon 6-8. Conclusions The FHIT gene rather than the P16 gene, plays a definite role in nickel carcinogenesis. Alterations of the FHIT gene induced by crystalline NiS may be a molecular event associated with carcinogen, chromosome fragile site instability and cell malignant transformation. FHIT may be an important target gene activated by nickel and other exotic carcinogens.展开更多
To study the characteristic of liquid-liquid extraction equilibrium of lithium from brine sources, the complexes formed from tributyl phosphate （TBP） and methyl isobutyl ketone （MIBK） with lithium were investi- ga...To study the characteristic of liquid-liquid extraction equilibrium of lithium from brine sources, the complexes formed from tributyl phosphate （TBP） and methyl isobutyl ketone （MIBK） with lithium were investi- gated using FeCl3 as coextracting agent. Liquid-liquid extraction reaction mechanisms were proposed and the stoichiometry of tetrachloroferrate（III） complex with lithium was obtained by regressing the experimental data. It is found that the stoichiometry of tetrachloroferrate（III） to lithium in the complex is 1 ： 1 with either TBP or MIBK as extractant in kerosene. The stoichiometry of the complex of TBP with Li was 1 ： 1 and that of MIBK with Li was 2 ： 1. The formed complexes of TBP and MIBK with lithium are determined to be LiFeCla-TBP and LiFeC14.2MIBK, respectively, according to the rule of neutralization.展开更多
Background Rotational atherectomy （RA） could facilitate the percutaneous coronary intervention （PCI） in heavily coronary calcified patients. The effectiveness and safety of this technique needs to be further evalu...Background Rotational atherectomy （RA） could facilitate the percutaneous coronary intervention （PCI） in heavily coronary calcified patients. The effectiveness and safety of this technique needs to be further evaluated. Methods ＆ Results Eighty patients who underwent RA in our center from September 2011 to June 2014 were enrolled. The mean age was 72.4 ± 10.4 years. The left ventricular ejection frac- tion （LVEF） was average 52.3% ± 8.48% and the estimated glomerular filtration rate was 73.2 ± 3.20 mL/min per 1.73 m2. The coronary lesions were complex, with Syntax score 29.5 ± 9.86. The diameter of reference vessel was 3.4 ± 0.45 mm and the average diameter stenosis of target vessels was 80% ~ 10%. All the patients were deployed with drug eluting stents （DES） successfully aiter RA. The patients were followed up for 12-18 months. Kaplan-Meier plots estimated the survival rate was 93.4% and the cumulative incidence of major adverse cardiac and cerebral events （MACCE） was 25.4%. Bleeding and procedural-related complications were quite low. COX proportional hazards model for multivariate analysis demonstrated that diabetes, LVEF and maximum pressure of postdilatation were the predictors of MACCE. Conclusions RA followed by implantation of DES was effective and safe for heavily coronary calcified patients. Diabetes, LVEF and maximum pressure ofpostdilatation were predictive for MACCE.展开更多
Background Although radial access for drug-eluting stent （DES） combined with rotational atherectomy （RA） in patients with calcified coronary lesions may be associated with a lower risk of major bleeding complicati...Background Although radial access for drug-eluting stent （DES） combined with rotational atherectomy （RA） in patients with calcified coronary lesions may be associated with a lower risk of major bleeding complications and obtain favorable clinical results compared with femoral access, the long-term outcome data of this approach were limited in contemporary DES era. Methods ＆ Results This retrospective study sought to compare in-hospital and long-term outcomes for patients undergoing RA via the transradial （TR） and transfemoral （TF） route in 126 consecutive patients （59 radial, 67 femoral） from 2009 to 2014. TR RA procedures were performed in 44/62 （71%） by the three TR operators, compared with 15/64 （23%） by the four TF operators in the present study. Significantly smaller diameter guide catheters and burrs （1.39 ± 0.16 mm vs. 1.53 ± 0.24 mm, P = 0.001） were used in the TR group. Procedural success rates were similar in both TR and TF groups. There was a significantly less major access site bleeding complications in favor of radial artery access （2% vs. 16%, P = 0.012）. The incidence of in-hospital death or myocardial infarction was low in both groups. Although a trend of lower adverse event rate was demonstrated in the TR group compared with the TF one, no statistical significance （21% vs. 27%, P = 0.135） was detected. Conclusions Radial access, a useful alternative to femoral access for RA and DES, can be safely and successfully performed on up to 71% of the patients with heavily calcified coronary lesions needing RA by experienced TR operators.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
A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridiniu...A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridinium salt were immobilized successively. Its catalytic activity was tested for the reauction of solid potassium acetate and benzyl bromide by GC analysis. It was found that the bicentral catalyst performed higher activity than the monocentral PS-PEG-400 and PS-Py.展开更多
The thermodynamic properties of a binary self-condensing vinyl polymerization system consisting of monomers and inimers are investigated by the principle of statistical mechanics.In detail,in terms of two types of can...The thermodynamic properties of a binary self-condensing vinyl polymerization system consisting of monomers and inimers are investigated by the principle of statistical mechanics.In detail,in terms of two types of canonical partition functions constructed from different viewpoints,the equilibrium free energy,the law of mass action and the size distribution of hyperbranched polymers are obtained.As an application,the specific heat,equation of state and isothermal compressibility concerning the polymerization are given as well.To study the dimension of hyperbranched polymers in the system,a recursion formula satisfied by the(k+1)-th and k-th mean square radius of gyration is derived,and then the first,second and third radius of gyration under different solvent conditions are presented.The influences of the fraction of inimers,the conversion of vinyl groups and the solvent effect on the average dimension of hyperbranched polymers are discussed.展开更多
At the intersection between treatment and diagnosis, nanoparticles technologies are strongly impacting the development of both therapeutic and diagnostic agents.Consequently, the development of novel modalities for co...At the intersection between treatment and diagnosis, nanoparticles technologies are strongly impacting the development of both therapeutic and diagnostic agents.Consequently, the development of novel modalities for concomitant noninvasive therapy and diagnostics known as theranostics as a single platform has gained significant interests. These multifunctional theranostic platforms include carbon-based nanomaterials（e.g., carbon nanotubes）, drug conjugates, aliphatic polymers, micelles, vesicles, core-shell nanoparticles, microbubbles and dendrimers bearing different contrast agents and drugs, such as cytotoxic compounds in the oncology domain. Dendrimers emerged as a new class of highly tunable hyperbranched polymers, and have been developed as useful theranostic platforms. Magnetic resonance imaging, gamma scintigraphy, computed tomography and optical imaging are the main techniques developed with dendrimers in the theranostic domain in oncology. Different imaging agents have been used such as Gd（Ⅲ）,19F, Fe2O3（MRI）,76Br（PET）,111In,88Y,153Gd,188Re,131I（SPECT）,177Lu,gold（CT） and boronated groups, siliconnaphthalocyanines,dialkylcarbocyanines and QDs（optical imaging dyes）.展开更多
It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPM...It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPMADOX conjugate was designed. di HPMA dendritic copolymer with GFLG segments in the branches which are sensitive to the intracellular enzyme of the tumor was prepared through RAFT polymerization. DOX was attached to dendritic di HPMA polymer through a pH-sensitive hydrazone bond. The dendritic pdi HPMA-DOX conjugate self-assembled into nanoparticles with an ideal spherical shape at a mean size of 103 nm. The DOX attached to the polymeric carrier was released in an acidic environment, and the GFLG linker for synthesizing the dendritic vehicle with a high molecular weight（M_W, 220 kDa） was cleaved to release low MWsegments（〈40 kDa） in the presence of cathepsin B. The dendritic polymeric conjugate was internalized via an endocytic pathway, and then released the anticancer drug, which led to significant cytotoxicity for tumors. The blood circulation time was profoundly prolonged, resulting in high accumulation of DOX into tumors. In vivo anti-tumor experiments with 4 T1 tumor bearing mice demonstrated that the conjugate had a better antitumor efficacy in comparison with free DOX. Additionally, body weight measurements and histological examinations indicated that the conjugate showed low toxicities to normal tissues. This dendritic polymeric drug carrier in a response to intracellular enzyme and acidic pH of tumor tissue or cells holds great promise in tumor-targeted therapy.展开更多
Because glycidyl(Gly) contains an epoxy and an active hydroxyl group, the Gly unit is difficult to introduce into certain polymeric chains in a controlled manner and usually yields hyperbranched polyglycidyl. Alternat...Because glycidyl(Gly) contains an epoxy and an active hydroxyl group, the Gly unit is difficult to introduce into certain polymeric chains in a controlled manner and usually yields hyperbranched polyglycidyl. Alternatively, the monomer 1-ethoxyethyl glycidyl ether(EEGE), derived from Gly and ethyl vinyl ether, has shown potential for application in polymer chemistry, and homopolymerization of this monomer directly produces linear poly(1-ethoxyethyl glycidyl ether) and further yields linear polyglycidyl. In this review, the initiation system of the EEGE monomer is first discussed in terms of chain transfer to monomers in ring-opening polymerization of epoxides with substituent groups. Then, random copolymerization of EEGE with other epoxides is considered. In addition, because the EEGE units on polymers can be transferred to Gly units and further used to construct copolymers with complicated architectures, the applications of EEGE monomers to block, graft, and hyperbranched copolymers are reviewed. Finally, the synthesis of main chain and terminal functional polyethers by transforming the hydroxyl groups at the polymer end or on the main chain into certain functional groups are also discussed. Chemistry based on EEGE has been proved to be an efficient, versatile route to constructing copolymers containing Gly units and ultimately yielding the target properties and applications.展开更多
Controlled ecological life support systems provide food, air, water, and other basic living resources for crew members on long-duration spaceflight missions. Plants are an important basic requirement of these systems ...Controlled ecological life support systems provide food, air, water, and other basic living resources for crew members on long-duration spaceflight missions. Plants are an important basic requirement of these systems and their biological characteristics in space have very high research value. Based on experiments of spaceflight in Shenzhou 8 spacecraft and simulating microgravity effects on three-dimensional （3-D） clinostat, the biological characteristics of tomato＇s leaf cell sub-microstructure and antioxidant enzyme activities were studied and compared in this work. Results showed that leaf cell sub-microstructure of the tomato samples experiencing spaceflight had more changes than effects, and both peroxidase （POD） and superoxide dismutase （SOD） that of the samples processed by simulated microgravity activities increase obviously in both the environments.展开更多
A new self-condensing vinyl polymerization system consisting of *ABf-type inimers is studied by the principle of statistical mechanics. To obtain the relevant average properties of the system, a differential equation ...A new self-condensing vinyl polymerization system consisting of *ABf-type inimers is studied by the principle of statistical mechanics. To obtain the relevant average properties of the system, a differential equation satisfied by the polymeric moment of interest is given, and as a result the zeroth, first, second, and third polymeric moments together with the size distribution function of hyperbranched polymers(HBPs) are explicitly presented. As an application of the method of statistical mechanics, several thermodynamic quantities such as the equilibrium free energy, law of mass action, isothermal compressibility, internal energy, and the specific heat associated with the polymerization are all derived. Furthermore, the scaling behavior of asymptotic size distribution function is discussed, by which a reasonable interpretation of the polydispersity index near the end of polymerization can be made. Also, the expressions of some structural parameters such as the numbers of inimers, terminal units, chain units, branched units, and the degree of branching(DB) are calculated. It is found that a high functionality is helpful to improve the DB of the resultant HBPs. These results show that the functionality f has a significant effect on the thermodynamic quantities and structural properties of HBPs.展开更多
Biomimetic scaffolds are appealing products for the repair of bone defects using tissue engineering strategies.In the present study,novel biomimetic composite scaffolds,with similar properties to natural bone,were pre...Biomimetic scaffolds are appealing products for the repair of bone defects using tissue engineering strategies.In the present study,novel biomimetic composite scaffolds,with similar properties to natural bone,were prepared,blended and cross-linked with bioactive glass,type I collagen and phosphatidylserine.When exposed to cell culture solution in the absence of a cellular source,the composite scaffolds form crystals with octahedral structure.These crystals are similar to the products derived from MC3T3-E1 cell mineralization within the composite scaffolds,with respect to both composition and morphology.Furthermore,crystals with octahedral structure were observed to develop into plate-like hydroxyapatite.The bio-mineralization behavior of the composite scaffolds is likely influenced by inorganic components.Finally,a rabbit tibia defect model shows that the highly bioactive properties of the investigated composites result in excellent bone repair.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(WK9990000102,WK2030000035).
文摘The study of oxide heteroepitaxy has been hindered by the issues of misfit strain and substrate clamping,which impede both the optimization of performance and the acquisition of a fundamental understanding of oxide systems.Recently,however,the development of freestanding oxide membranes has provided a plausible solution to these substrate limitations.Single-crystalline functional oxide films can be released from their substrates without incurring significant damage and can subsequently be transferred to any substrate of choice.This paper discusses recent advancements in the fabrication,adjustable physical properties,and various applications of freestanding oxide perovskite films.First,we present the primary strategies employed for the synthesis and transfer of these freestanding perovskite thin films.Second,we explore the main functionalities observed in freestanding perovskite oxide thin films,with special attention to the tunable functionalities and physical properties of these freestanding perovskite membranes under varying strain states.Next,we encapsulate three representative devices based on freestanding oxide films.Overall,this review highlights the potential of freestanding oxide films for the study of novel functionalities and flexible electronics.
基金This work was supported by a grant (No. 39170651 and 30200235) from National Natural Science Foundation of China.
文摘Objective To study the alterations of FHIT gene and P16 gene in malignant transformed human bronchial epithelial cells induced by crystalline nickel sulfide using an immortal human bronchial epithelial cell line, and to explore the molecular mechanism of nickel carcinogenesis. Methods 16HBE cells were treated 6 times with different concentrations of NiS in vitro, and the degree of malignant transformation was determined by assaying the anchorage-independent growth and tumorigenicity. Malignant transformed cells and tumorigenic cells were examined for alterations of FHIT gene and P16 gene using RT-PCR, DNA sequencing, silver staining PCR-SSCP and Western blotting. Results NiS-treated cells exhibited overlapping growth. Compared wkh that of negative control cells, soft agar colony formation efficiency of NiS-treated cells showed significant increases （P〈0.01） and dose-dependent effects. NiS-treated cells could form tumors in nude mice, and a squamous cell carcinoma was confirmed by histopathological examination. No mutation of exon 2 and exons 2-3, no abnormal expression in pl6 gene and mutation of FHIT exons 5-8 and exons 1-4 or exons 5-9 were observed in transformed cells and tumorigenic cells. However, aberrant transcripts or loss of expression of the FHIT gene and Fhit protein was observed in transformed cells and tumorigenic cells. One of the aberrant transcripts in the FHIT gene was confirmed to have a deletion of exon 6, exon 7, exon 8, and an insertion of a 36 bp sequence replacing exon 6-8. Conclusions The FHIT gene rather than the P16 gene, plays a definite role in nickel carcinogenesis. Alterations of the FHIT gene induced by crystalline NiS may be a molecular event associated with carcinogen, chromosome fragile site instability and cell malignant transformation. FHIT may be an important target gene activated by nickel and other exotic carcinogens.
基金Supported by the National High Technology Research and Development Program of China (2008AA06Z111)the Qinghai Key Technology R&D Program (2011-J-154)
文摘To study the characteristic of liquid-liquid extraction equilibrium of lithium from brine sources, the complexes formed from tributyl phosphate （TBP） and methyl isobutyl ketone （MIBK） with lithium were investi- gated using FeCl3 as coextracting agent. Liquid-liquid extraction reaction mechanisms were proposed and the stoichiometry of tetrachloroferrate（III） complex with lithium was obtained by regressing the experimental data. It is found that the stoichiometry of tetrachloroferrate（III） to lithium in the complex is 1 ： 1 with either TBP or MIBK as extractant in kerosene. The stoichiometry of the complex of TBP with Li was 1 ： 1 and that of MIBK with Li was 2 ： 1. The formed complexes of TBP and MIBK with lithium are determined to be LiFeCla-TBP and LiFeC14.2MIBK, respectively, according to the rule of neutralization.
文摘Background Rotational atherectomy （RA） could facilitate the percutaneous coronary intervention （PCI） in heavily coronary calcified patients. The effectiveness and safety of this technique needs to be further evaluated. Methods ＆ Results Eighty patients who underwent RA in our center from September 2011 to June 2014 were enrolled. The mean age was 72.4 ± 10.4 years. The left ventricular ejection frac- tion （LVEF） was average 52.3% ± 8.48% and the estimated glomerular filtration rate was 73.2 ± 3.20 mL/min per 1.73 m2. The coronary lesions were complex, with Syntax score 29.5 ± 9.86. The diameter of reference vessel was 3.4 ± 0.45 mm and the average diameter stenosis of target vessels was 80% ~ 10%. All the patients were deployed with drug eluting stents （DES） successfully aiter RA. The patients were followed up for 12-18 months. Kaplan-Meier plots estimated the survival rate was 93.4% and the cumulative incidence of major adverse cardiac and cerebral events （MACCE） was 25.4%. Bleeding and procedural-related complications were quite low. COX proportional hazards model for multivariate analysis demonstrated that diabetes, LVEF and maximum pressure of postdilatation were the predictors of MACCE. Conclusions RA followed by implantation of DES was effective and safe for heavily coronary calcified patients. Diabetes, LVEF and maximum pressure ofpostdilatation were predictive for MACCE.
文摘Background Although radial access for drug-eluting stent （DES） combined with rotational atherectomy （RA） in patients with calcified coronary lesions may be associated with a lower risk of major bleeding complications and obtain favorable clinical results compared with femoral access, the long-term outcome data of this approach were limited in contemporary DES era. Methods ＆ Results This retrospective study sought to compare in-hospital and long-term outcomes for patients undergoing RA via the transradial （TR） and transfemoral （TF） route in 126 consecutive patients （59 radial, 67 femoral） from 2009 to 2014. TR RA procedures were performed in 44/62 （71%） by the three TR operators, compared with 15/64 （23%） by the four TF operators in the present study. Significantly smaller diameter guide catheters and burrs （1.39 ± 0.16 mm vs. 1.53 ± 0.24 mm, P = 0.001） were used in the TR group. Procedural success rates were similar in both TR and TF groups. There was a significantly less major access site bleeding complications in favor of radial artery access （2% vs. 16%, P = 0.012）. The incidence of in-hospital death or myocardial infarction was low in both groups. Although a trend of lower adverse event rate was demonstrated in the TR group compared with the TF one, no statistical significance （21% vs. 27%, P = 0.135） was detected. Conclusions Radial access, a useful alternative to femoral access for RA and DES, can be safely and successfully performed on up to 71% of the patients with heavily calcified coronary lesions needing RA by experienced TR operators.
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.
文摘A bicentral polymer-supported Phase transfer catalyst, polystpyne-suPPorted polyethylene glycol and Pyridinium salt (PS-Py-PEG-400),synthesized with ohloromethylated polystyrene as supporter on which PEG and Pyridinium salt were immobilized successively. Its catalytic activity was tested for the reauction of solid potassium acetate and benzyl bromide by GC analysis. It was found that the bicentral catalyst performed higher activity than the monocentral PS-PEG-400 and PS-Py.
基金supported by the National Natural Science Foundation of China (20873035)
文摘The thermodynamic properties of a binary self-condensing vinyl polymerization system consisting of monomers and inimers are investigated by the principle of statistical mechanics.In detail,in terms of two types of canonical partition functions constructed from different viewpoints,the equilibrium free energy,the law of mass action and the size distribution of hyperbranched polymers are obtained.As an application,the specific heat,equation of state and isothermal compressibility concerning the polymerization are given as well.To study the dimension of hyperbranched polymers in the system,a recursion formula satisfied by the(k+1)-th and k-th mean square radius of gyration is derived,and then the first,second and third radius of gyration under different solvent conditions are presented.The influences of the fraction of inimers,the conversion of vinyl groups and the solvent effect on the average dimension of hyperbranched polymers are discussed.
基金support of FCT-Fundacao para a Ciência e a Tecnologia(project PEst-OE/QUI/UI0674/2013,CQM,Portuguese Government funds)ARDITI through the project M1420-01-0145-FEDER-000005-Centro de Química da Madeira-CQM+(Madeira 14-20)+2 种基金the funds from Centre National de la Recherche Scientifique(CNRS,France)the support by the National Natural Science Foundation of China(21773026 and 81761148028)the Sino-French Caiyuanpei Programme
文摘At the intersection between treatment and diagnosis, nanoparticles technologies are strongly impacting the development of both therapeutic and diagnostic agents.Consequently, the development of novel modalities for concomitant noninvasive therapy and diagnostics known as theranostics as a single platform has gained significant interests. These multifunctional theranostic platforms include carbon-based nanomaterials（e.g., carbon nanotubes）, drug conjugates, aliphatic polymers, micelles, vesicles, core-shell nanoparticles, microbubbles and dendrimers bearing different contrast agents and drugs, such as cytotoxic compounds in the oncology domain. Dendrimers emerged as a new class of highly tunable hyperbranched polymers, and have been developed as useful theranostic platforms. Magnetic resonance imaging, gamma scintigraphy, computed tomography and optical imaging are the main techniques developed with dendrimers in the theranostic domain in oncology. Different imaging agents have been used such as Gd（Ⅲ）,19F, Fe2O3（MRI）,76Br（PET）,111In,88Y,153Gd,188Re,131I（SPECT）,177Lu,gold（CT） and boronated groups, siliconnaphthalocyanines,dialkylcarbocyanines and QDs（optical imaging dyes）.
基金supported by the National Natural Science Foundation of China (51673127 and 8162103)International Science and Technology Cooperation Program of China (2015DFE52780 and 81220108013)International Science and Technology Cooperation Program of Chengdu (2016-GH03-00005-HZ)
文摘It is in a great demand to design a biodegradable, tumor microenvironment-sensitive drug delivery system to achieve safe and highly efficacious treatment of cancer.Herein, a novel pH/enzyme sensitive dendritic pdi HPMADOX conjugate was designed. di HPMA dendritic copolymer with GFLG segments in the branches which are sensitive to the intracellular enzyme of the tumor was prepared through RAFT polymerization. DOX was attached to dendritic di HPMA polymer through a pH-sensitive hydrazone bond. The dendritic pdi HPMA-DOX conjugate self-assembled into nanoparticles with an ideal spherical shape at a mean size of 103 nm. The DOX attached to the polymeric carrier was released in an acidic environment, and the GFLG linker for synthesizing the dendritic vehicle with a high molecular weight（M_W, 220 kDa） was cleaved to release low MWsegments（〈40 kDa） in the presence of cathepsin B. The dendritic polymeric conjugate was internalized via an endocytic pathway, and then released the anticancer drug, which led to significant cytotoxicity for tumors. The blood circulation time was profoundly prolonged, resulting in high accumulation of DOX into tumors. In vivo anti-tumor experiments with 4 T1 tumor bearing mice demonstrated that the conjugate had a better antitumor efficacy in comparison with free DOX. Additionally, body weight measurements and histological examinations indicated that the conjugate showed low toxicities to normal tissues. This dendritic polymeric drug carrier in a response to intracellular enzyme and acidic pH of tumor tissue or cells holds great promise in tumor-targeted therapy.
基金supported by the National Natural Science Foundation of China(21274024,21004011)
文摘Because glycidyl(Gly) contains an epoxy and an active hydroxyl group, the Gly unit is difficult to introduce into certain polymeric chains in a controlled manner and usually yields hyperbranched polyglycidyl. Alternatively, the monomer 1-ethoxyethyl glycidyl ether(EEGE), derived from Gly and ethyl vinyl ether, has shown potential for application in polymer chemistry, and homopolymerization of this monomer directly produces linear poly(1-ethoxyethyl glycidyl ether) and further yields linear polyglycidyl. In this review, the initiation system of the EEGE monomer is first discussed in terms of chain transfer to monomers in ring-opening polymerization of epoxides with substituent groups. Then, random copolymerization of EEGE with other epoxides is considered. In addition, because the EEGE units on polymers can be transferred to Gly units and further used to construct copolymers with complicated architectures, the applications of EEGE monomers to block, graft, and hyperbranched copolymers are reviewed. Finally, the synthesis of main chain and terminal functional polyethers by transforming the hydroxyl groups at the polymer end or on the main chain into certain functional groups are also discussed. Chemistry based on EEGE has been proved to be an efficient, versatile route to constructing copolymers containing Gly units and ultimately yielding the target properties and applications.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2011CB710902)the National Manned Spaceflight Project of China
文摘Controlled ecological life support systems provide food, air, water, and other basic living resources for crew members on long-duration spaceflight missions. Plants are an important basic requirement of these systems and their biological characteristics in space have very high research value. Based on experiments of spaceflight in Shenzhou 8 spacecraft and simulating microgravity effects on three-dimensional （3-D） clinostat, the biological characteristics of tomato＇s leaf cell sub-microstructure and antioxidant enzyme activities were studied and compared in this work. Results showed that leaf cell sub-microstructure of the tomato samples experiencing spaceflight had more changes than effects, and both peroxidase （POD） and superoxide dismutase （SOD） that of the samples processed by simulated microgravity activities increase obviously in both the environments.
基金supported by the National Natural Science Foundation of China(21274056,21374028)Natural Science Foundation of Hebei province(B2015408007)the doctoral funds of Langfang Teachers University(LSBS201308)
文摘A new self-condensing vinyl polymerization system consisting of *ABf-type inimers is studied by the principle of statistical mechanics. To obtain the relevant average properties of the system, a differential equation satisfied by the polymeric moment of interest is given, and as a result the zeroth, first, second, and third polymeric moments together with the size distribution function of hyperbranched polymers(HBPs) are explicitly presented. As an application of the method of statistical mechanics, several thermodynamic quantities such as the equilibrium free energy, law of mass action, isothermal compressibility, internal energy, and the specific heat associated with the polymerization are all derived. Furthermore, the scaling behavior of asymptotic size distribution function is discussed, by which a reasonable interpretation of the polydispersity index near the end of polymerization can be made. Also, the expressions of some structural parameters such as the numbers of inimers, terminal units, chain units, branched units, and the degree of branching(DB) are calculated. It is found that a high functionality is helpful to improve the DB of the resultant HBPs. These results show that the functionality f has a significant effect on the thermodynamic quantities and structural properties of HBPs.
基金supported by the Science and Technology Plan Project of Fujian Department of Education,China (Grant No. JK2009021)
文摘Biomimetic scaffolds are appealing products for the repair of bone defects using tissue engineering strategies.In the present study,novel biomimetic composite scaffolds,with similar properties to natural bone,were prepared,blended and cross-linked with bioactive glass,type I collagen and phosphatidylserine.When exposed to cell culture solution in the absence of a cellular source,the composite scaffolds form crystals with octahedral structure.These crystals are similar to the products derived from MC3T3-E1 cell mineralization within the composite scaffolds,with respect to both composition and morphology.Furthermore,crystals with octahedral structure were observed to develop into plate-like hydroxyapatite.The bio-mineralization behavior of the composite scaffolds is likely influenced by inorganic components.Finally,a rabbit tibia defect model shows that the highly bioactive properties of the investigated composites result in excellent bone repair.
