The membrane aeration biofilm reactor(MABR)represents an innovative approach to wastewater treatment,integrating gas separation membranes with biofilm process and demonstrating effectiveness in treating wastewater ric...The membrane aeration biofilm reactor(MABR)represents an innovative approach to wastewater treatment,integrating gas separation membranes with biofilm process and demonstrating effectiveness in treating wastewater rich in ammonia nitrogen.In this system,hollow fiber membranes are essential,serving as a substrate for biofilm attachment while facilitating oxygen transfer to microorganisms through aeration,hydrophobic microporous membranes are utilized in MABR applications.This study focuses on the use of poly-4-methyl-1-pentene(PMP)hollow fiber membranes,which exhibit superior oxygen permeation capabilities compared to traditional hydrophobic microporous membranes.To overcome the challenges posed by the hydrophobic nature and low bubble point of PMP microporous membranes,a hydrophilic modification was conducted using dopamine/poly(ethyleneimine)(DOPA/PEI)co-deposition to enhance microbial adhesion on the membrane surface.The composite membrane modified with DOPA/PEI exhibited an approximately 20%higher NH_(4)^(+)-N removal efficiency than the unmodified membrane.These findings suggest that the incorporation of DOPA/PEI significantly improves MABR performance,underscoring its potential for further research and development in membrane technology for MABR.展开更多
To solve the slow dynamics of catalytic oxygen reaction energy devices,a facile method was developed for the synthesis of methylene alcohol terminated poly(1,4-phenyldiimine)porphyrin cobalt(MPImPorCo),which was synth...To solve the slow dynamics of catalytic oxygen reaction energy devices,a facile method was developed for the synthesis of methylene alcohol terminated poly(1,4-phenyldiimine)porphyrin cobalt(MPImPorCo),which was synthesized by RuCl3 catalyzed redox reaction of meso-5,10,15,20-tetra(4-nitrophenyl)porphyrin cobalt(TNO2PorCo)and 1,4-phenyldimethanol.M-PImPorCo is a fully conjugated covalent organic framework(COF)with high thermal and chemical stability.COFs with different edge groups were synthesized to compare the effect of different groups(–CH_(2)–OH and–NO_(2))on catalytic bifunctional oxygen reaction activity.C=N as nitrogen-rich environment of M-PImPorCo leads to the protonation process of oxygen catalysis and reduces the energy barrier of adsorption in the oxygen intermediate.C=N and–CH_(2)–OH form an“electron pump”structure to deliver electrons to the Co–N4 site in M-PImPorCo,and theπ–πinteraction between M-PImPorCo and three-dimensional graphene(3D-G)can further enrich the electron cloud density of Co–N4 sites.M-PImPorCo/3D-G has remarkable oxygen catalytic performance,with a half-wave potential(E_(1/2))of 0.91 V vs.reversible hydrogen electrode(RHE).M-PImPorCo/3D-G has low potential(Ej=10 is 1.49 V vs.RHE)at a current density of 10 mA·cm^(-2).It exhibits a good bifunctional catalytic performance(potential difference(ΔE)=0.58 V).The smaller charge–discharge band gap of zinc-air batteries(ZABs)and flexible ZABs(F-ZABs)equipped with M-PImPorCo/3D-G suggests the potential for catalytic oxygen reaction bifunctional applications.This work provides a new idea for the synthesis of Schiff-base porphyrin-based COF catalyst and its potential application to oxygen reaction catalytic energy storage devices.展开更多
Isotactic poly（butene-1） （iPB） with spherical morphology was synthesized successfully with bulk precipitation polymerization without post-treatment of the products. The bulk precipitation polymerization process ma...Isotactic poly（butene-1） （iPB） with spherical morphology was synthesized successfully with bulk precipitation polymerization without post-treatment of the products. The bulk precipitation polymerization process made it possible for iPB to be used as general plastic due to the acceptable decreased cost compared with the solution polymerization process. The influence of catalyst residues on the aging and thermal stability of iPB synthesized by bulk precipitation polymerization method was investigated by gel permeation chromatography, mechanical performance testing, thermogravimetric analysis and infrared spectroscopic analysis. Commercial iPB and the lab-made iPB with varied catalyst residue contents were studied. The results demonstrated that the catalyst residues played an important role in the aging process of the iPB. A possible mechanism of aging promotion by catalyst residues was proposed.展开更多
Polymeric amines are being studied intensively as components of systems for gene delivery in genetic engineering and gene therapy of genetic disorders, including cancer. Despite remarkable achievements in the field, p...Polymeric amines are being studied intensively as components of systems for gene delivery in genetic engineering and gene therapy of genetic disorders, including cancer. Despite remarkable achievements in the field, polymeric amines, such as polyethyleneimine, show some disadvantages. Strong interaction between the amine-containing polymer and nucleic acid hampers the release of nucleic acid in the cell cytoplasm. Amine groups can interact with the cell membrane which results in cell death. These limitations of polymeric amines stimulated an investigation of new structures for gene delivery. Imidazole-containing polymers have attracted attention as lesser basic substances, while they are able to interact with polymeric acids. Further development of imidazole-based gene delivery agents requires knowledge about some fundamental aspects of interaction between nucleic acids, and polymeric imidazoles. In this work, we studied the complexation of poly(1-vinylimidazole) and oligomeric DNA. We found that the number of active sites capable of binding with negatively charged phosphate groups is comparable with the number of protonated imidazole units in the case of high molecular weight polymer. The increase in polymer charge by 1-bromopropane quaternizating 1%?5% imidazole units or by decreasing the pH to 6.5?7 considerably increased the ability of poly(1-vinylimidazole) to interact with oligonucleotides. The pH sensitivity of this interaction is interesting for cancer gene therapy because the tumours have a lowered intercellular pH (stable oligonucleotide complex) and a higher extracellular pH which can lead to complex dissociation. Minimal critical length for complexation of quaternized poly(1-vinylimidazole) and DNA is below eight units which corresponds to polymers with amine groups. Fluorescence-tagged poly(1-vinylimidazole) samples were obtained and their potential for monitoring the polymer and polymer-oligonucleotide complex internalization into living cells was demonstrated.展开更多
Poly（1,8-octanediol-co-citrate） （POC） represents a new promising biocompatible and biodegradable polyester that has been extensively investigated for soft tissue engineering. However, the poor mechanical performan...Poly（1,8-octanediol-co-citrate） （POC） represents a new promising biocompatible and biodegradable polyester that has been extensively investigated for soft tissue engineering. However, the poor mechanical performance and poor bioactivity limit its application in bone regeneration. In this study, a series of POC/bioactive glasses （BG） composites were developed using 45S5 Bioglass^Θ and a phytic acid- derived bioactive glass （referred as PSC）. The results indicated that calcium in BG could enhance the crosslinking of the POC/BG composites by forming calcium dicarboxylate bridges and thus improve their mechanical performances. When PSC were used, the composites exhibited significantly better mechanical properties compared to composites with 45S5 Bioglass^Θ. For example, by incorporating 70wt% PSC, the compressive strength of POC/PSC composites could be improved to approximately 50 MPa and modulus 1.3-h 0.1 GPa. Furthermore, all these POC/PSC composites showed good in vitro bioactivity and cellular biocompatibility. Histology results in femoral condyle defects of Sprague-Dawley rats indicated that the POC/PSC samples integrated well with surrounding tissues and stimulated bone regeneration. The improved mechanical properties and bioactivity of POC/PSC composites make them promising for potential application in bone regeneration.展开更多
Poly(4-methyl-1-pentene) (PMP) hollow fiber membranes were prepared by the melt-spun and cold-stretch(MSCS) method. Scanning electronic microscopy (SEM) was used to characterize the section and surface structures of t...Poly(4-methyl-1-pentene) (PMP) hollow fiber membranes were prepared by the melt-spun and cold-stretch(MSCS) method. Scanning electronic microscopy (SEM) was used to characterize the section and surface structures of themembranes with special asymmetric structure. The preliminary results of gas permeation measurements indicated that the resultant hollow fiber membranes have the potential ability for oxygen/nitrogen separation.展开更多
While WCl_6-Ph_4Sn fails to polymerize 1-phenyl-1-propyne (PP) at room temperature, highmolecular weight (M_w up to 410× 10~3) polymers are obtained in high yields (up to 80%) when thepolymerizations of PP are ca...While WCl_6-Ph_4Sn fails to polymerize 1-phenyl-1-propyne (PP) at room temperature, highmolecular weight (M_w up to 410× 10~3) polymers are obtained in high yields (up to 80%) when thepolymerizations of PP are carried out in the presence of C_(60) using the W catalyst under the same conditions.The polymers are soluble in common organic solvents such as THF, chloroform, and toluene. Molecularstructures of the polymers are characterized by FT-IR, UV, NMR, GPC and XRD, and it is found that C_(60) iscopolymerized with PP. Thus C_(60) plays the dual roles of comonomer and cocatalyst in the polymerizationreaction. C_(60) contents of the copolymers can be easily changed by varying the C_(60) amounts in the feedmixtures. The copolymers effectively limit strong 532 nm laser pulses, whose limiting performance issuperior to that of parent C_(60).展开更多
FTIR, UV-visible , fluorescence spectra and calculation of CPK model indicated that poly(1-naphthol) synthesized and assembled by horseradish peroxidase(HRP) in aqueous micelle was constructed with orderly helical co...FTIR, UV-visible , fluorescence spectra and calculation of CPK model indicated that poly(1-naphthol) synthesized and assembled by horseradish peroxidase(HRP) in aqueous micelle was constructed with orderly helical conformation, which was the lowest energy conformation of the polymer under this condition and resulted in an advanced c-conjugated system.展开更多
Crystallization in polymer systems actually is a process that transfers the entangled melts into a semi-crystalline layered structure. Whether or not a chain disentangles may result in different crystallization mechan...Crystallization in polymer systems actually is a process that transfers the entangled melts into a semi-crystalline layered structure. Whether or not a chain disentangles may result in different crystallization mechanism. When compared to the crystal thickness (d(c)), the volume occupied by the chain in the melts i.e., the radius of gyration (R-g), plays a very important role in polymer crystallization. When d(c) less than or equal to R-g, crystallization does not necessitate a chain disentangling. The entanglements are just shifted into the amorphous regions. However, as d(c)>R-g, i.e., as the crystal thickness gets larger than the radius of gyration of the chain in the melt, it becomes necessary for a chain to disentangle. Then a change of crystallization mechanism occurs. Such change has been experimentally observed in the crystallization of poly(I-butene). A change in the crystal morphologies from spherulite to quadrangle, is seen via PLM, as crystallization temperatures increase. Even more, such a change is molecular weight dependent, and shifts to lower temperature as molecular weight decreases. There exists a jump of crystal thickness and crystallinity associated with morphological change, as seen via SAXS. A change of crystallization kinetics and crystallinity is further evidenced via dilatometry. The unique feature of P1b crystallization has been discussed based on the radius of gyration of chain in the melt (R-g), and very good agreement is obtained.展开更多
Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 m...Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm^(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.展开更多
The polymerization of 1-octene initiated by methylalmnoxane （MAO）-activated Ni（II）-based-a-diimine complexes [（2,6-i-Pr）2C6H3-DAB（An）]NiBr2 was investigated. Using this catalyst, poly（1-octene）s with molecul...The polymerization of 1-octene initiated by methylalmnoxane （MAO）-activated Ni（II）-based-a-diimine complexes [（2,6-i-Pr）2C6H3-DAB（An）]NiBr2 was investigated. Using this catalyst, poly（1-octene）s with molecular weight between 100 × 10^3 and 400 ×10^3 and polydispersity （Mw/Mn） between 1.3 and 1.5 were synthesized successfully by varying reaction time at room temperature. The poly（1-octene）s were amorphous polymers and could be well soluble in tetrahydrofuran （THF）. After fractional precipitation, poly（1-octene）s with narrow molecular weight distributions （Mw/Mn 〈 1.12） were obtained. Their weight-average molecular weights were measured by gel permeation chromatography （GPC） in conjunction with online model BI-MwA multiangle laser light scattering （MALLS）, and their intrinsic viscosities were measured by Maron＇s single-point method. The k and a values in Mark-Houwink equation [η] = KM^a in THF at 40α were 0.089 mL/g and 0.61 respectively.展开更多
A new type of polymerizable ionic liquid （IL） 1-（3-aminobenzyl）-3-methylimidazolium chloride （AMIC） was synthesized to obtain a novel polymer salt poly（1-（3-aminobenzyl）-3-methylimidazolium chloride） （PAMIC...A new type of polymerizable ionic liquid （IL） 1-（3-aminobenzyl）-3-methylimidazolium chloride （AMIC） was synthesized to obtain a novel polymer salt poly（1-（3-aminobenzyl）-3-methylimidazolium chloride） （PAMIC）. The AMIC was structurally characterized by mass spectrometry and Fourier transform infrared spectrometry （FTIR）. The structure, morphology and properties of PAMIC were investigated by FTIR, ultraviolet visible absorption spectra （UV-Vis）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDX）, conductivity measurement and thermo- gravimetric analysis （TGA）. The PAMIC was spherulitic with an average diameter of about 50 nm and showed high conductivity and excellent thermal stability.展开更多
Zinc ions (Zn2+), known to be a novel intracellular second messenger related to various biological functions, have been delivered inside cells. For the intracellular Zn2+ delivery, Zn2+ has been chelated to carboxymet...Zinc ions (Zn2+), known to be a novel intracellular second messenger related to various biological functions, have been delivered inside cells. For the intracellular Zn2+ delivery, Zn2+ has been chelated to carboxymethyl poly(1-vinylimidazole) (CM-PVIm) by mixing zinc chloride (ZnCl2) or zinc acetate (Zn(OAc)2) with CM-PVIm. The resulting Zn2+-chelated CM-PVIm, that is, Zn2+/CM-PVIm complex by mixing ZnCl2 exhibited smaller particle size below 10 nm and possessed larger amount of Zn2+ ions, as compared to the Zn2+/CM-PVIm by mixing Zn(OAc)2. The both Zn2+/CM-PVIm complexes exhibited no significant cytotoxicity, leading to intracellular Zn2+ delivery. The Zn2+/CM-PVIm by mixing ZnCl2 delivered larger amount of intracellular Zn2+ ions than that by mixing Zn(OAc)2. These results suggest that the optimal Zn2+/CM-PVIm complex is a useful tool for intracellular Zn2+ delivery to control various biological functions.展开更多
Poly(ADP-ribose)polymerase-1(PARP-1)can exacerbate ischemic brain injury and lessen ischemic neuronal death,which may be associated with PARP-1 polymorphisms.The present study investigated human PARP-1 gene polymorphi...Poly(ADP-ribose)polymerase-1(PARP-1)can exacerbate ischemic brain injury and lessen ischemic neuronal death,which may be associated with PARP-1 polymorphisms.The present study investigated human PARP-1 gene polymorphisms in various Chinese nationalities,the results of which could potentially help in the treatment and prevention of neurologic diseases.Genetic polymorphisms of seven exons in the PARP-1 gene,in 898 Chinese Han,Buyi,Shui,Miao,and Zhuang subjects,were investigated by PCR-single-strand conformation polymorphism.A single-strand conformation polymorphism variant in exons 12,13,16,and 17 of the PARP-1 gene was identified in 148 people,with two stationary bands showing three degenerative single strands.Results showed that the PARP-1 gene polymorphisms exist in various nationalities,and may act as a biomarker for susceptibility to disease.展开更多
Poly(4-methyl-1-pentene)hollow fiber membranes(PMP HFMs)are commonly used in gas separation membrane and artificial lung membrane in extracorporeal membrane oxygenation(ECMO),and its porous structure and mechanical pr...Poly(4-methyl-1-pentene)hollow fiber membranes(PMP HFMs)are commonly used in gas separation membrane and artificial lung membrane in extracorporeal membrane oxygenation(ECMO),and its porous structure and mechanical properties have a significant impact on the performance of the membrane material.In our work,PMP HFMs were prepared by thermally induced phase separation method.Subsequently,through characterization analysis of powder X-ray diffraction,universal tensile machine,scanning electron microscope and other instruments,the effects of PMP concentration,diluent ratio,quenching temperature,air gap distance and winding speed on the membrane performance were systematically investigated to obtain optimal preparation conditions for PMP HFMs.The results showed that the PMP HFMs prepared under optimal conditions possessed good gas permeability with a nitrogen flux of 10.5 ml·MPa^(-1)·cm^(-2)·min^(-1),a surface dense layer,and a good tensile strength of 9.33 MPa.We believed that this work could provide useful references for the application of PMP membranes in the medical field.展开更多
In this study, the isothermal crystallization kinetics and crystalline morphology of poly（butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate）（PBAC）, which refers to a copolyester containing a non-planar rin...In this study, the isothermal crystallization kinetics and crystalline morphology of poly（butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate）（PBAC）, which refers to a copolyester containing a non-planar ring structure, were investigated by differential scanning calorimetry and polarized optical microscopy, and compared with those of neat poly（butylene 1,4-cyclohexanedicarboxylate）（PBC）. The results indicate that the introduction of butylene adipate（BA） unit into PBAC did not change the intrinsical crystallization mechanism. But, the crystallization rate and ability, and equilibrium melting temperature of PBAC copolymers were reduced. All PBC and PBAC copolymers could only form high density of nucleation from melt at given supercooling, while no Maltese cross or ring-banded spherulites could be observed. PBAC copolymers with a high amount of BA unit became amorphous after quenching with liquid nitrogen from melt, while PBC and PBAC copolymers with a low amount of BA unit could still form a large amount of nuclei under the same treatment.展开更多
In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthesized and characterized. MO-p-PPV was synthesized according to Gilch polymerization mechanism by using 4-m...In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthesized and characterized. MO-p-PPV was synthesized according to Gilch polymerization mechanism by using 4-methoxyphenol as starting material in the presence of potassium tert-butoxide (1M in THF). The product was further purified by multiple precipitations in different solvents such as methanol, tetrahydrofuran, isopropyl alcohol and hexane. The final product was dried to afford MO-p-PPV as a red solid. The resulting polymer was completely soluble in common organic solvents. The structure of monomer and optical properties of polymer were characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The UV-vis spectrum showed absorption maxima for MO-p-PPV at 491 nm. Similarly, fluorescence spectrum showed λmax emission at 540 nm.展开更多
Chemical reduction of nitrate using metal nanoparticles has received increasing interest due to over-dependence on groundwater and consequence health hazard of the nitrate ion. One major drawback of this technique is ...Chemical reduction of nitrate using metal nanoparticles has received increasing interest due to over-dependence on groundwater and consequence health hazard of the nitrate ion. One major drawback of this technique is the agglomeration of nanoparticles leading to the formation of large floes. A low cost biopolymeric material, poly [β-（1-4）-2-amino-2-deoxy-D-glucopyranose] （β-PADG） obtained from deacetylated chitin was used as stabilizer to synthesize zero valent nickel （ZVNi） nanoparticles. The β-PADG-ZVNi nanocomposite was characterized using infra red （IR）, UV-Vis spectrophotometric techniques and Scanning Electron Microscope （SEM）. The morphology of the composite showed that β-PADG stabilized-ZVNi nanoparticles were present as discrete particles. The mean particle size was estimated to be （7.76 ± 2.98） nm and surface area of 87.10 m2/g. The stabilized-ZVNi nanoparticles exhibited markedly greater reactivity for reduction of nitrate in water with 100% conversion within 2 hr contact owing to less agglomeration. Varying the β-PADG-to-ZVNi ratio and the ZVNi-to-nitrate molar ratio generally led to a faster nitrate reduction. About 3.4-fold difference in the specific reaction rate constant suggests that the application of the β-PADG-stabilizer not only increased the specific surface area of the resultant nanoparticles, but also greatly enhanced the surface reactivity of the nanoparticles per unit area.展开更多
基金supported by the National Key Research and Development Program of China(2023YFB3810502)the National Natural Science Foundation of China(22078146)the Key Research and Development program of Anhui Province(2023h11020004).
文摘The membrane aeration biofilm reactor(MABR)represents an innovative approach to wastewater treatment,integrating gas separation membranes with biofilm process and demonstrating effectiveness in treating wastewater rich in ammonia nitrogen.In this system,hollow fiber membranes are essential,serving as a substrate for biofilm attachment while facilitating oxygen transfer to microorganisms through aeration,hydrophobic microporous membranes are utilized in MABR applications.This study focuses on the use of poly-4-methyl-1-pentene(PMP)hollow fiber membranes,which exhibit superior oxygen permeation capabilities compared to traditional hydrophobic microporous membranes.To overcome the challenges posed by the hydrophobic nature and low bubble point of PMP microporous membranes,a hydrophilic modification was conducted using dopamine/poly(ethyleneimine)(DOPA/PEI)co-deposition to enhance microbial adhesion on the membrane surface.The composite membrane modified with DOPA/PEI exhibited an approximately 20%higher NH_(4)^(+)-N removal efficiency than the unmodified membrane.These findings suggest that the incorporation of DOPA/PEI significantly improves MABR performance,underscoring its potential for further research and development in membrane technology for MABR.
基金supported by the National Natural Science Foundation of China(Nos.22172093 and 21776167)the Natural Science Foundation of Shandong Province,China(No.ZR2023MB061).
文摘To solve the slow dynamics of catalytic oxygen reaction energy devices,a facile method was developed for the synthesis of methylene alcohol terminated poly(1,4-phenyldiimine)porphyrin cobalt(MPImPorCo),which was synthesized by RuCl3 catalyzed redox reaction of meso-5,10,15,20-tetra(4-nitrophenyl)porphyrin cobalt(TNO2PorCo)and 1,4-phenyldimethanol.M-PImPorCo is a fully conjugated covalent organic framework(COF)with high thermal and chemical stability.COFs with different edge groups were synthesized to compare the effect of different groups(–CH_(2)–OH and–NO_(2))on catalytic bifunctional oxygen reaction activity.C=N as nitrogen-rich environment of M-PImPorCo leads to the protonation process of oxygen catalysis and reduces the energy barrier of adsorption in the oxygen intermediate.C=N and–CH_(2)–OH form an“electron pump”structure to deliver electrons to the Co–N4 site in M-PImPorCo,and theπ–πinteraction between M-PImPorCo and three-dimensional graphene(3D-G)can further enrich the electron cloud density of Co–N4 sites.M-PImPorCo/3D-G has remarkable oxygen catalytic performance,with a half-wave potential(E_(1/2))of 0.91 V vs.reversible hydrogen electrode(RHE).M-PImPorCo/3D-G has low potential(Ej=10 is 1.49 V vs.RHE)at a current density of 10 mA·cm^(-2).It exhibits a good bifunctional catalytic performance(potential difference(ΔE)=0.58 V).The smaller charge–discharge band gap of zinc-air batteries(ZABs)and flexible ZABs(F-ZABs)equipped with M-PImPorCo/3D-G suggests the potential for catalytic oxygen reaction bifunctional applications.This work provides a new idea for the synthesis of Schiff-base porphyrin-based COF catalyst and its potential application to oxygen reaction catalytic energy storage devices.
基金financially supported by the National Key Technology R&D Program of China(No.2011BAE26B05)
文摘Isotactic poly（butene-1） （iPB） with spherical morphology was synthesized successfully with bulk precipitation polymerization without post-treatment of the products. The bulk precipitation polymerization process made it possible for iPB to be used as general plastic due to the acceptable decreased cost compared with the solution polymerization process. The influence of catalyst residues on the aging and thermal stability of iPB synthesized by bulk precipitation polymerization method was investigated by gel permeation chromatography, mechanical performance testing, thermogravimetric analysis and infrared spectroscopic analysis. Commercial iPB and the lab-made iPB with varied catalyst residue contents were studied. The results demonstrated that the catalyst residues played an important role in the aging process of the iPB. A possible mechanism of aging promotion by catalyst residues was proposed.
基金financial support from a joint grant of the Russian Science Foundation (16-45-02001)the Department of Science Technology of the Ministry of Science and Technology of the Republic of India (INT/RUS/RSF/10)
文摘Polymeric amines are being studied intensively as components of systems for gene delivery in genetic engineering and gene therapy of genetic disorders, including cancer. Despite remarkable achievements in the field, polymeric amines, such as polyethyleneimine, show some disadvantages. Strong interaction between the amine-containing polymer and nucleic acid hampers the release of nucleic acid in the cell cytoplasm. Amine groups can interact with the cell membrane which results in cell death. These limitations of polymeric amines stimulated an investigation of new structures for gene delivery. Imidazole-containing polymers have attracted attention as lesser basic substances, while they are able to interact with polymeric acids. Further development of imidazole-based gene delivery agents requires knowledge about some fundamental aspects of interaction between nucleic acids, and polymeric imidazoles. In this work, we studied the complexation of poly(1-vinylimidazole) and oligomeric DNA. We found that the number of active sites capable of binding with negatively charged phosphate groups is comparable with the number of protonated imidazole units in the case of high molecular weight polymer. The increase in polymer charge by 1-bromopropane quaternizating 1%?5% imidazole units or by decreasing the pH to 6.5?7 considerably increased the ability of poly(1-vinylimidazole) to interact with oligonucleotides. The pH sensitivity of this interaction is interesting for cancer gene therapy because the tumours have a lowered intercellular pH (stable oligonucleotide complex) and a higher extracellular pH which can lead to complex dissociation. Minimal critical length for complexation of quaternized poly(1-vinylimidazole) and DNA is below eight units which corresponds to polymers with amine groups. Fluorescence-tagged poly(1-vinylimidazole) samples were obtained and their potential for monitoring the polymer and polymer-oligonucleotide complex internalization into living cells was demonstrated.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB12020300)National Natural Science Foundation of China (No. 31370985)
文摘Poly（1,8-octanediol-co-citrate） （POC） represents a new promising biocompatible and biodegradable polyester that has been extensively investigated for soft tissue engineering. However, the poor mechanical performance and poor bioactivity limit its application in bone regeneration. In this study, a series of POC/bioactive glasses （BG） composites were developed using 45S5 Bioglass^Θ and a phytic acid- derived bioactive glass （referred as PSC）. The results indicated that calcium in BG could enhance the crosslinking of the POC/BG composites by forming calcium dicarboxylate bridges and thus improve their mechanical performances. When PSC were used, the composites exhibited significantly better mechanical properties compared to composites with 45S5 Bioglass^Θ. For example, by incorporating 70wt% PSC, the compressive strength of POC/PSC composites could be improved to approximately 50 MPa and modulus 1.3-h 0.1 GPa. Furthermore, all these POC/PSC composites showed good in vitro bioactivity and cellular biocompatibility. Histology results in femoral condyle defects of Sprague-Dawley rats indicated that the POC/PSC samples integrated well with surrounding tissues and stimulated bone regeneration. The improved mechanical properties and bioactivity of POC/PSC composites make them promising for potential application in bone regeneration.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59833120).
文摘Poly(4-methyl-1-pentene) (PMP) hollow fiber membranes were prepared by the melt-spun and cold-stretch(MSCS) method. Scanning electronic microscopy (SEM) was used to characterize the section and surface structures of themembranes with special asymmetric structure. The preliminary results of gas permeation measurements indicated that the resultant hollow fiber membranes have the potential ability for oxygen/nitrogen separation.
基金This work was in part supported by the Hong Kong Research Grants Council(HKUST6062/98P and DAG96/97 SC11).
文摘While WCl_6-Ph_4Sn fails to polymerize 1-phenyl-1-propyne (PP) at room temperature, highmolecular weight (M_w up to 410× 10~3) polymers are obtained in high yields (up to 80%) when thepolymerizations of PP are carried out in the presence of C_(60) using the W catalyst under the same conditions.The polymers are soluble in common organic solvents such as THF, chloroform, and toluene. Molecularstructures of the polymers are characterized by FT-IR, UV, NMR, GPC and XRD, and it is found that C_(60) iscopolymerized with PP. Thus C_(60) plays the dual roles of comonomer and cocatalyst in the polymerizationreaction. C_(60) contents of the copolymers can be easily changed by varying the C_(60) amounts in the feedmixtures. The copolymers effectively limit strong 532 nm laser pulses, whose limiting performance issuperior to that of parent C_(60).
文摘FTIR, UV-visible , fluorescence spectra and calculation of CPK model indicated that poly(1-naphthol) synthesized and assembled by horseradish peroxidase(HRP) in aqueous micelle was constructed with orderly helical conformation, which was the lowest energy conformation of the polymer under this condition and resulted in an advanced c-conjugated system.
基金This work was supported by the Deutsche Forschungsgemeinschall and der Chemischen Industrierate, Alexander von Humboldt Stiffeng and the China National Distinguished Young Investigator Fund (No. 29925413).
文摘Crystallization in polymer systems actually is a process that transfers the entangled melts into a semi-crystalline layered structure. Whether or not a chain disentangles may result in different crystallization mechanism. When compared to the crystal thickness (d(c)), the volume occupied by the chain in the melts i.e., the radius of gyration (R-g), plays a very important role in polymer crystallization. When d(c) less than or equal to R-g, crystallization does not necessitate a chain disentangling. The entanglements are just shifted into the amorphous regions. However, as d(c)>R-g, i.e., as the crystal thickness gets larger than the radius of gyration of the chain in the melt, it becomes necessary for a chain to disentangle. Then a change of crystallization mechanism occurs. Such change has been experimentally observed in the crystallization of poly(I-butene). A change in the crystal morphologies from spherulite to quadrangle, is seen via PLM, as crystallization temperatures increase. Even more, such a change is molecular weight dependent, and shifts to lower temperature as molecular weight decreases. There exists a jump of crystal thickness and crystallinity associated with morphological change, as seen via SAXS. A change of crystallization kinetics and crystallinity is further evidenced via dilatometry. The unique feature of P1b crystallization has been discussed based on the radius of gyration of chain in the melt (R-g), and very good agreement is obtained.
基金The project is supported by the National Natural Science Foundation of China
文摘Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm^(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.
基金supported by the program for new century excellent talents in Chinese universities and Beijing Municipal Education Commission
文摘The polymerization of 1-octene initiated by methylalmnoxane （MAO）-activated Ni（II）-based-a-diimine complexes [（2,6-i-Pr）2C6H3-DAB（An）]NiBr2 was investigated. Using this catalyst, poly（1-octene）s with molecular weight between 100 × 10^3 and 400 ×10^3 and polydispersity （Mw/Mn） between 1.3 and 1.5 were synthesized successfully by varying reaction time at room temperature. The poly（1-octene）s were amorphous polymers and could be well soluble in tetrahydrofuran （THF）. After fractional precipitation, poly（1-octene）s with narrow molecular weight distributions （Mw/Mn 〈 1.12） were obtained. Their weight-average molecular weights were measured by gel permeation chromatography （GPC） in conjunction with online model BI-MwA multiangle laser light scattering （MALLS）, and their intrinsic viscosities were measured by Maron＇s single-point method. The k and a values in Mark-Houwink equation [η] = KM^a in THF at 40α were 0.089 mL/g and 0.61 respectively.
基金financially supported by the Hunan Provincial Natural Science Foundation of China(Nos.11JJ3015 and 11JJ1009)
文摘A new type of polymerizable ionic liquid （IL） 1-（3-aminobenzyl）-3-methylimidazolium chloride （AMIC） was synthesized to obtain a novel polymer salt poly（1-（3-aminobenzyl）-3-methylimidazolium chloride） （PAMIC）. The AMIC was structurally characterized by mass spectrometry and Fourier transform infrared spectrometry （FTIR）. The structure, morphology and properties of PAMIC were investigated by FTIR, ultraviolet visible absorption spectra （UV-Vis）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDX）, conductivity measurement and thermo- gravimetric analysis （TGA）. The PAMIC was spherulitic with an average diameter of about 50 nm and showed high conductivity and excellent thermal stability.
文摘Zinc ions (Zn2+), known to be a novel intracellular second messenger related to various biological functions, have been delivered inside cells. For the intracellular Zn2+ delivery, Zn2+ has been chelated to carboxymethyl poly(1-vinylimidazole) (CM-PVIm) by mixing zinc chloride (ZnCl2) or zinc acetate (Zn(OAc)2) with CM-PVIm. The resulting Zn2+-chelated CM-PVIm, that is, Zn2+/CM-PVIm complex by mixing ZnCl2 exhibited smaller particle size below 10 nm and possessed larger amount of Zn2+ ions, as compared to the Zn2+/CM-PVIm by mixing Zn(OAc)2. The both Zn2+/CM-PVIm complexes exhibited no significant cytotoxicity, leading to intracellular Zn2+ delivery. The Zn2+/CM-PVIm by mixing ZnCl2 delivered larger amount of intracellular Zn2+ ions than that by mixing Zn(OAc)2. These results suggest that the optimal Zn2+/CM-PVIm complex is a useful tool for intracellular Zn2+ delivery to control various biological functions.
基金the National Natural Science Foundation of China,No.30972500the Natural Science Foundation of Guangdong Province,No.7301507
文摘Poly(ADP-ribose)polymerase-1(PARP-1)can exacerbate ischemic brain injury and lessen ischemic neuronal death,which may be associated with PARP-1 polymorphisms.The present study investigated human PARP-1 gene polymorphisms in various Chinese nationalities,the results of which could potentially help in the treatment and prevention of neurologic diseases.Genetic polymorphisms of seven exons in the PARP-1 gene,in 898 Chinese Han,Buyi,Shui,Miao,and Zhuang subjects,were investigated by PCR-single-strand conformation polymorphism.A single-strand conformation polymorphism variant in exons 12,13,16,and 17 of the PARP-1 gene was identified in 148 people,with two stationary bands showing three degenerative single strands.Results showed that the PARP-1 gene polymorphisms exist in various nationalities,and may act as a biomarker for susceptibility to disease.
基金support of thiswork by Science Fund of State Key Laboratory of Tribology,Tsinghua University(61012205321).
文摘Poly(4-methyl-1-pentene)hollow fiber membranes(PMP HFMs)are commonly used in gas separation membrane and artificial lung membrane in extracorporeal membrane oxygenation(ECMO),and its porous structure and mechanical properties have a significant impact on the performance of the membrane material.In our work,PMP HFMs were prepared by thermally induced phase separation method.Subsequently,through characterization analysis of powder X-ray diffraction,universal tensile machine,scanning electron microscope and other instruments,the effects of PMP concentration,diluent ratio,quenching temperature,air gap distance and winding speed on the membrane performance were systematically investigated to obtain optimal preparation conditions for PMP HFMs.The results showed that the PMP HFMs prepared under optimal conditions possessed good gas permeability with a nitrogen flux of 10.5 ml·MPa^(-1)·cm^(-2)·min^(-1),a surface dense layer,and a good tensile strength of 9.33 MPa.We believed that this work could provide useful references for the application of PMP membranes in the medical field.
基金financially supported by the National Natural Science Foundation of China(No.51503217)Zhejiang Province Public Welfare Project(No.2017C31081)+1 种基金the Open Project Program of MOE Key Laboratory of Macromolecular Synthesis and Functionalization,Zhejiang University(No.2016MSF001)Youth Innovation Promotion Association CAS(No.2017339)
文摘In this study, the isothermal crystallization kinetics and crystalline morphology of poly（butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate）（PBAC）, which refers to a copolyester containing a non-planar ring structure, were investigated by differential scanning calorimetry and polarized optical microscopy, and compared with those of neat poly（butylene 1,4-cyclohexanedicarboxylate）（PBC）. The results indicate that the introduction of butylene adipate（BA） unit into PBAC did not change the intrinsical crystallization mechanism. But, the crystallization rate and ability, and equilibrium melting temperature of PBAC copolymers were reduced. All PBC and PBAC copolymers could only form high density of nucleation from melt at given supercooling, while no Maltese cross or ring-banded spherulites could be observed. PBAC copolymers with a high amount of BA unit became amorphous after quenching with liquid nitrogen from melt, while PBC and PBAC copolymers with a low amount of BA unit could still form a large amount of nuclei under the same treatment.
文摘In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthesized and characterized. MO-p-PPV was synthesized according to Gilch polymerization mechanism by using 4-methoxyphenol as starting material in the presence of potassium tert-butoxide (1M in THF). The product was further purified by multiple precipitations in different solvents such as methanol, tetrahydrofuran, isopropyl alcohol and hexane. The final product was dried to afford MO-p-PPV as a red solid. The resulting polymer was completely soluble in common organic solvents. The structure of monomer and optical properties of polymer were characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The UV-vis spectrum showed absorption maxima for MO-p-PPV at 491 nm. Similarly, fluorescence spectrum showed λmax emission at 540 nm.
文摘Chemical reduction of nitrate using metal nanoparticles has received increasing interest due to over-dependence on groundwater and consequence health hazard of the nitrate ion. One major drawback of this technique is the agglomeration of nanoparticles leading to the formation of large floes. A low cost biopolymeric material, poly [β-（1-4）-2-amino-2-deoxy-D-glucopyranose] （β-PADG） obtained from deacetylated chitin was used as stabilizer to synthesize zero valent nickel （ZVNi） nanoparticles. The β-PADG-ZVNi nanocomposite was characterized using infra red （IR）, UV-Vis spectrophotometric techniques and Scanning Electron Microscope （SEM）. The morphology of the composite showed that β-PADG stabilized-ZVNi nanoparticles were present as discrete particles. The mean particle size was estimated to be （7.76 ± 2.98） nm and surface area of 87.10 m2/g. The stabilized-ZVNi nanoparticles exhibited markedly greater reactivity for reduction of nitrate in water with 100% conversion within 2 hr contact owing to less agglomeration. Varying the β-PADG-to-ZVNi ratio and the ZVNi-to-nitrate molar ratio generally led to a faster nitrate reduction. About 3.4-fold difference in the specific reaction rate constant suggests that the application of the β-PADG-stabilizer not only increased the specific surface area of the resultant nanoparticles, but also greatly enhanced the surface reactivity of the nanoparticles per unit area.
