In this study,we prepared a series of tung oil phenolic foams(TPF)by a one-pot method.The FT-IR and 1H NMR spectra confirm the successful Friedel-Crafts grafting of phenol to the long-chain alkyl group in tung oil.Mod...In this study,we prepared a series of tung oil phenolic foams(TPF)by a one-pot method.The FT-IR and 1H NMR spectra confirm the successful Friedel-Crafts grafting of phenol to the long-chain alkyl group in tung oil.Modified TPFs exhibit enhanced mechanical properties,including compressive and flexural strengths of up to 0.278±0.036 MPa and 0.450±0.017 MPa,respectively,which represent increases of 68.75%and 86.72%over those of pure phenolic foam(PF).SEM spectra reveal the TPF microstructure to have uniform hexagonal cell morphology,narrower cell size distribution,and smaller mean cell size,suggesting enhanced mechanical properties.The TPF total smoke release decreased by 74.23%,indicating that the long alkyl chain significantly improves smoke suppression of the combusting foam.However,due to the flammability of the alkyl chains,the TPF limiting oxygen index decreases with increasing tung oil content.Moreover,TPF exhibits reduced thermal stability and high-temperature charring rate,elevated peak and mean heat release rates,and higher total heat release compared with pure PF.Therefore,future research will focus on the use of tung oil modified flame retardant to provide more robust phenolic foams.展开更多
Phenolic foams(PFs)as thermal insulation material with outstanding flame retardancy are required to match society’s ever-expanding safety expectations;however,a trade-off exists between flame retardancy and toughness...Phenolic foams(PFs)as thermal insulation material with outstanding flame retardancy are required to match society’s ever-expanding safety expectations;however,a trade-off exists between flame retardancy and toughness.Here,for the first time,we synthesized a novel reactive phosphorus-containing tung-oil-based derivative and used it to toughen PF,resulting in PFs with a combination of excellent mechanical properties and flame retardancy.Compared with pure PF,the modified PFs exhibit enhanced mechanical properties,with specific compressive and flexural strengths as high as 5.67 MPa and 12.46 MPa,which represent increases of 90.67%and 178.7%over those of pure PF,respectively.Meanwhile,the limiting oxygen index(LOI)values of the modified PFs are improved as much as 40.83%.Scanning electron microscopy micrographs show that the microstructure of the modified PFs is better than that of pure PF,with a more uniform cell morphology,a narrower pore size distribution range,and a smaller average pore size,all of which are beneficial to the foam’s mechanical properties.This study provides a scientific paradigm for the development of advanced PFs based on renewable biological resources.展开更多
The present work,in which cellulose isolated from formic acid fractionation(FAC)is decorated with polyetherimide(PEI)to attain highly efficient cellulose-derived PdAgbimetallic catalyst(PdAg-PEI-FAC),has been investig...The present work,in which cellulose isolated from formic acid fractionation(FAC)is decorated with polyetherimide(PEI)to attain highly efficient cellulose-derived PdAgbimetallic catalyst(PdAg-PEI-FAC),has been investigated,and the catalyst properties are characterized by XRD,XPS,BET,ICP-AES and HAADF-STEM.The as-obtained Pd_(3.75)Ag_(3.75)-PEI-FAC exhibits excellent catalytic performance for H_(2)evolution from a sodium formate-free formic acid(FA)aqueous medium at ambient temperature and the turnover frequency(TOF)reaches a high value of 2875 h^(-1)which is superior to most of the previously reported Pd-based heterogeneous catalysts supported on a carbon matrix in the literature.The remarkable catalytic activities of PdAg-PEI-FAC result from high dispersion Pd and synergistic effects between the PdAg bimetallic system.Furthermore,the amide(-NH)group in PEI coated on cellulose acting as a proton scavenger efficiently improves the catalytic property of catalyst.In addition,the critical factors affecting H;release,such as FA concentration,reaction temperature,PdAg compositions and support matrix type,are also evaluated.Based on the experimental results,the probable three-step mechanism of H_(2)evolution from FA over Pd_(3.75)Ag_(3.75)-PEI-FAC is proposed.In the end,the activation energy(Ea)of Pd_(3.75)Ag_(3.75)-PEI-FAC catalyst is calculated to 53.97 kJ mol^(-1),and this catalyst shows unique robustness and satisfactory re-usability with no loss of catalytic activity after five recycles.The findings in this work provide a novel routine from lignocellulose fractionation towards cellulose-derived catalyst for H_(2)evolution.展开更多
Chondroitin sulfate proteoglycans （CSPGs） which are produced by mature oligodendrocytes and reactive astrocytes can be upregulated after spinal cord injury and contribute to regenerative failure. Chondroitinase ABC ...Chondroitin sulfate proteoglycans （CSPGs） which are produced by mature oligodendrocytes and reactive astrocytes can be upregulated after spinal cord injury and contribute to regenerative failure. Chondroitinase ABC （ChABC） digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. However, many current studies have used an incomplete spinal cord injury model, and examined results after 8-12 weeks of ChABC treatment. In this study, a complete rat spinal cord transection injury model was used to study the long-term effects of ChABC treatment by subarachnoid catheter. Pathology of spinal cord regeneration was compared with control 24 weeks following ChABC treatment using immunohistochemistry and axon tracing techniques. At 24 weeks after injury, neurofilament 200 expression was significantly greater in the ChABC treatment group compared with the transection group. In the ChABC treatment group, axonal growth was demonstrated by a large number of biotinylated dextran amine positive axons caudal to, or past, the epicenter of injury. Biotinylated dextran amine-labeled fibers were found in the proximal end of the spinal cord in the transection alone group. These results confirm that ChABC can promote axon growth, neural regeneration, and repair after spinal cord injury in rats long after the initial injury.展开更多
Genome instability has been identified as one of the enabling hallmarks in cancer.DNA damage response(DDR)network is responsible for maintenance of genome integrity in cells.As cancer cells frequently carry DDR gene d...Genome instability has been identified as one of the enabling hallmarks in cancer.DNA damage response(DDR)network is responsible for maintenance of genome integrity in cells.As cancer cells frequently carry DDR gene deficiencies or suffer from replicative stress,targeting DDR processes could induce excessive DNA damages(or unrepaired DNA)that eventually lead to cell death.Poly(ADP-ribose)polymerase(PARP)inhibitors have brought impressive benefit to patients with breast cancer gene(BRCA)mutation or homologous recombination deficiency(HRD),which proves the concept of synthetic lethality in cancer treatment.Moreover,the other two scenarios of DDR inhibitor application,replication stress and combination with chemo-or radio-therapy,are under active clinical exploration.In this review,we revisited the progress of DDR targeting therapy beyond the launched firstgeneration PARP inhibitors.Next generation PARP1 selective inhibitors,which could maintain the efficacy while mitigating side effects,may diversify the application scenarios of PARP inhibitor in clinic.Albeit with unavoidable on-mechanism toxicities,several small molecules targeting DNA damage checkpoints(gatekeepers)have shown great promise in preliminary clinical results,which may warrant further evaluations.In addition,inhibitors for other DNA repair pathways(caretakers)are also under active preclinical or clinical development.With these progresses and efforts,we envision that a new wave of innovations within DDR has come of age.展开更多
Aberrant activation of NLRP3 inflammasome in colonic macrophages strongly associates with the occurrence and progression of ulcerative colitis.Although targeting NLRP3 inflammasome has been considered to be a potentia...Aberrant activation of NLRP3 inflammasome in colonic macrophages strongly associates with the occurrence and progression of ulcerative colitis.Although targeting NLRP3 inflammasome has been considered to be a potential therapy,the underlying mechanism through which pathway the intestinal inflammation is modulated remains controversial.By focusing on the flavonoid lonicerin,one of the most abundant constituents existed in a long historical anti-inflammatory and anti-infectious herb Lonicera japonica Thunb.,here we report its therapeutic effect on intestinal inflammation by binding directly to enhancer of zeste homolog 2(EZH2)histone methyltransferase.EZH2-mediated modification of H3 K27 me3 promotes the expression of autophagy-related protein 5,which in turn leads to enhanced autophagy and accelerates autolysosome-mediated NLRP3 degradation.Mutations of EZH2 residues(His 129 and Arg685)indicated by the dynamic simulation study have found to greatly diminish the protective effect of lonicerin.More importantly,in vivo studies verify that lonicerin dose-dependently disrupts the NLRP3-ASC-pro-caspase-1 complex assembly and alleviates colitis,which is compromised by administration of EZH2 overexpression plasmid.Thus,these findings together put forth the stage for further considering lonicerin as an anti-inflammatory epigenetic agent and suggesting EZH2/ATG5/NLRP3 axis may serve as a novel strategy to prevent ulcerative colitis as well as other inflammatory diseases.展开更多
Divergent synthesis of medium-sized rings with controllable ring sizes represents a longstanding challenge in organic synthesis.Herein,we developed a transition-metal-catalyzed switchable divergent cycloaddition of pa...Divergent synthesis of medium-sized rings with controllable ring sizes represents a longstanding challenge in organic synthesis.Herein,we developed a transition-metal-catalyzed switchable divergent cycloaddition of para-quinone methides and vinylethylene carbonates by controlling the steric hindrance of substituent.Different from reported alkoxide-triggered annulations,this process undergoes a regiodivergent allylation of para-quinone methides followed by 1,6-addition reaction,providing a new route to selectively synthesize seven-to ten-membered nitrogen-containing heterocycles in high yields with excellent regioselectivities.This protocol features a broad substrate scope,wide functional group tolerance as well as operational simplicity.The reaction mechanism was investigated by conducting a series of control experiments as well as DFT calculations and the origins of the regioselectivities of the cycloaddition process were rationalized.展开更多
基金the financial support from the Fundamental Research Funds for the Central Non-profit Research Institution of CAF(No.CAFYBB2018MA001)the National Natural Science Foundation of China(Grant No.31700499).
文摘In this study,we prepared a series of tung oil phenolic foams(TPF)by a one-pot method.The FT-IR and 1H NMR spectra confirm the successful Friedel-Crafts grafting of phenol to the long-chain alkyl group in tung oil.Modified TPFs exhibit enhanced mechanical properties,including compressive and flexural strengths of up to 0.278±0.036 MPa and 0.450±0.017 MPa,respectively,which represent increases of 68.75%and 86.72%over those of pure phenolic foam(PF).SEM spectra reveal the TPF microstructure to have uniform hexagonal cell morphology,narrower cell size distribution,and smaller mean cell size,suggesting enhanced mechanical properties.The TPF total smoke release decreased by 74.23%,indicating that the long alkyl chain significantly improves smoke suppression of the combusting foam.However,due to the flammability of the alkyl chains,the TPF limiting oxygen index decreases with increasing tung oil content.Moreover,TPF exhibits reduced thermal stability and high-temperature charring rate,elevated peak and mean heat release rates,and higher total heat release compared with pure PF.Therefore,future research will focus on the use of tung oil modified flame retardant to provide more robust phenolic foams.
基金from the Fundamental Research Funds for the Central Non-profit Research Institution of CAF(No.CAFYBB2018MA001).
文摘Phenolic foams(PFs)as thermal insulation material with outstanding flame retardancy are required to match society’s ever-expanding safety expectations;however,a trade-off exists between flame retardancy and toughness.Here,for the first time,we synthesized a novel reactive phosphorus-containing tung-oil-based derivative and used it to toughen PF,resulting in PFs with a combination of excellent mechanical properties and flame retardancy.Compared with pure PF,the modified PFs exhibit enhanced mechanical properties,with specific compressive and flexural strengths as high as 5.67 MPa and 12.46 MPa,which represent increases of 90.67%and 178.7%over those of pure PF,respectively.Meanwhile,the limiting oxygen index(LOI)values of the modified PFs are improved as much as 40.83%.Scanning electron microscopy micrographs show that the microstructure of the modified PFs is better than that of pure PF,with a more uniform cell morphology,a narrower pore size distribution range,and a smaller average pore size,all of which are beneficial to the foam’s mechanical properties.This study provides a scientific paradigm for the development of advanced PFs based on renewable biological resources.
基金financially funded by the National Natural Science Foundation of China(NSFC,21476016,21776009)Fundamental Research Funds for the Central Universitiesthe special project for the construction of innovative province in Hunan Province of China(2019NK2031-3)
文摘The present work,in which cellulose isolated from formic acid fractionation(FAC)is decorated with polyetherimide(PEI)to attain highly efficient cellulose-derived PdAgbimetallic catalyst(PdAg-PEI-FAC),has been investigated,and the catalyst properties are characterized by XRD,XPS,BET,ICP-AES and HAADF-STEM.The as-obtained Pd_(3.75)Ag_(3.75)-PEI-FAC exhibits excellent catalytic performance for H_(2)evolution from a sodium formate-free formic acid(FA)aqueous medium at ambient temperature and the turnover frequency(TOF)reaches a high value of 2875 h^(-1)which is superior to most of the previously reported Pd-based heterogeneous catalysts supported on a carbon matrix in the literature.The remarkable catalytic activities of PdAg-PEI-FAC result from high dispersion Pd and synergistic effects between the PdAg bimetallic system.Furthermore,the amide(-NH)group in PEI coated on cellulose acting as a proton scavenger efficiently improves the catalytic property of catalyst.In addition,the critical factors affecting H;release,such as FA concentration,reaction temperature,PdAg compositions and support matrix type,are also evaluated.Based on the experimental results,the probable three-step mechanism of H_(2)evolution from FA over Pd_(3.75)Ag_(3.75)-PEI-FAC is proposed.In the end,the activation energy(Ea)of Pd_(3.75)Ag_(3.75)-PEI-FAC catalyst is calculated to 53.97 kJ mol^(-1),and this catalyst shows unique robustness and satisfactory re-usability with no loss of catalytic activity after five recycles.The findings in this work provide a novel routine from lignocellulose fractionation towards cellulose-derived catalyst for H_(2)evolution.
基金the National Natural Science Foundation of China,No.30471759
文摘Chondroitin sulfate proteoglycans （CSPGs） which are produced by mature oligodendrocytes and reactive astrocytes can be upregulated after spinal cord injury and contribute to regenerative failure. Chondroitinase ABC （ChABC） digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. However, many current studies have used an incomplete spinal cord injury model, and examined results after 8-12 weeks of ChABC treatment. In this study, a complete rat spinal cord transection injury model was used to study the long-term effects of ChABC treatment by subarachnoid catheter. Pathology of spinal cord regeneration was compared with control 24 weeks following ChABC treatment using immunohistochemistry and axon tracing techniques. At 24 weeks after injury, neurofilament 200 expression was significantly greater in the ChABC treatment group compared with the transection group. In the ChABC treatment group, axonal growth was demonstrated by a large number of biotinylated dextran amine positive axons caudal to, or past, the epicenter of injury. Biotinylated dextran amine-labeled fibers were found in the proximal end of the spinal cord in the transection alone group. These results confirm that ChABC can promote axon growth, neural regeneration, and repair after spinal cord injury in rats long after the initial injury.
文摘Genome instability has been identified as one of the enabling hallmarks in cancer.DNA damage response(DDR)network is responsible for maintenance of genome integrity in cells.As cancer cells frequently carry DDR gene deficiencies or suffer from replicative stress,targeting DDR processes could induce excessive DNA damages(or unrepaired DNA)that eventually lead to cell death.Poly(ADP-ribose)polymerase(PARP)inhibitors have brought impressive benefit to patients with breast cancer gene(BRCA)mutation or homologous recombination deficiency(HRD),which proves the concept of synthetic lethality in cancer treatment.Moreover,the other two scenarios of DDR inhibitor application,replication stress and combination with chemo-or radio-therapy,are under active clinical exploration.In this review,we revisited the progress of DDR targeting therapy beyond the launched firstgeneration PARP inhibitors.Next generation PARP1 selective inhibitors,which could maintain the efficacy while mitigating side effects,may diversify the application scenarios of PARP inhibitor in clinic.Albeit with unavoidable on-mechanism toxicities,several small molecules targeting DNA damage checkpoints(gatekeepers)have shown great promise in preliminary clinical results,which may warrant further evaluations.In addition,inhibitors for other DNA repair pathways(caretakers)are also under active preclinical or clinical development.With these progresses and efforts,we envision that a new wave of innovations within DDR has come of age.
基金supported by the Program of the National Natural Science Foundation of China(No.81903885,Qi LvNo.21877062,Yinan Zhang+2 种基金No.82073719,Lihong Hu)the program of the Jiangsu“Shuang Chuang”team(No.20182036,Lihong Hu and Yinan Zhang,China)the key research projects of Jiangsu Higher Education(No.18KJA360010,Yinan Zhang,China)
文摘Aberrant activation of NLRP3 inflammasome in colonic macrophages strongly associates with the occurrence and progression of ulcerative colitis.Although targeting NLRP3 inflammasome has been considered to be a potential therapy,the underlying mechanism through which pathway the intestinal inflammation is modulated remains controversial.By focusing on the flavonoid lonicerin,one of the most abundant constituents existed in a long historical anti-inflammatory and anti-infectious herb Lonicera japonica Thunb.,here we report its therapeutic effect on intestinal inflammation by binding directly to enhancer of zeste homolog 2(EZH2)histone methyltransferase.EZH2-mediated modification of H3 K27 me3 promotes the expression of autophagy-related protein 5,which in turn leads to enhanced autophagy and accelerates autolysosome-mediated NLRP3 degradation.Mutations of EZH2 residues(His 129 and Arg685)indicated by the dynamic simulation study have found to greatly diminish the protective effect of lonicerin.More importantly,in vivo studies verify that lonicerin dose-dependently disrupts the NLRP3-ASC-pro-caspase-1 complex assembly and alleviates colitis,which is compromised by administration of EZH2 overexpression plasmid.Thus,these findings together put forth the stage for further considering lonicerin as an anti-inflammatory epigenetic agent and suggesting EZH2/ATG5/NLRP3 axis may serve as a novel strategy to prevent ulcerative colitis as well as other inflammatory diseases.
基金supportedbythe National Natural Science Foundation of China(Nos.82173664,81803342)“Shuang Chuang”Research Team of jiangsu Province(No.20182036).
文摘Divergent synthesis of medium-sized rings with controllable ring sizes represents a longstanding challenge in organic synthesis.Herein,we developed a transition-metal-catalyzed switchable divergent cycloaddition of para-quinone methides and vinylethylene carbonates by controlling the steric hindrance of substituent.Different from reported alkoxide-triggered annulations,this process undergoes a regiodivergent allylation of para-quinone methides followed by 1,6-addition reaction,providing a new route to selectively synthesize seven-to ten-membered nitrogen-containing heterocycles in high yields with excellent regioselectivities.This protocol features a broad substrate scope,wide functional group tolerance as well as operational simplicity.The reaction mechanism was investigated by conducting a series of control experiments as well as DFT calculations and the origins of the regioselectivities of the cycloaddition process were rationalized.
