Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated P...Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated PET materials with high crystallinity remain insufficient.Here,we endeavored to improve the degradation capability of a WCCG mutant of leaf-branch compost cutinase(LCC)on a unpretreated PET substrate(crystallinity>40%)by employing iterative saturation mutagenesis.Using this method,we developed a high-throughput screening strategy appropriate for unpretreated substrates.Through extensive screening of residues around the substrate-binding groove,two variants,WCCG-sup1 and WCCG-sup2,showed good depolymerization capabilities with both high-(42%)and low-crystallinity(9%)substrates.The WCCG-sup1 variant completely depolymerized a commercial unpretreated PET product in 36 h at 72℃.In addition to enzyme thermostability and catalytic efficiency,the adsorption of enzymes onto substrates plays an important role in PET degradation.This study provides valuable insights into the structure-function relationship of LCC.展开更多
The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy ...The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy UV light,while the corresponding[2+2]polymerization in solution has proved to be inefficient due to the lack of preassembly of the monomers.Herein,we demonstrate that the[2+2]polymerization of p-phenylenediacrylate monomers can be achieved in solution under visible light by employing energy transfer catalysis with 2,2'-methoxythioxanthone as a photocatalyst.Because no preassembly is required,this solution polymerization is applicable to p-phenylenediacrylate monomers with different ester groups,affording a series of cyclobutane-imbedded full-carbon chain polymers with high thermal stability,good solubility,and processibility.In addition,by virtue of the reversibility of the photo[2+2]cycloaddition,this[2+2]photopolymerization product can also undergo depolymerization to lower molecular weight polymers,suggesting the potential of this class of photopolymerization in the development of closed-loop chemical recyclable polymers.展开更多
Calcium carbide,a bulky and cheap raw chemical,is traditionally depolymerized by water to release acetylene,allowing the downstream organic transformation.In this study,hydrogen sulfide(H_(2)S),an industrial waste gas...Calcium carbide,a bulky and cheap raw chemical,is traditionally depolymerized by water to release acetylene,allowing the downstream organic transformation.In this study,hydrogen sulfide(H_(2)S),an industrial waste gas,has been exploited to depolymerize calcium carbide,which represents a strategy for the comprehensive utilization of both hydrogen sulfide and calcium carbide.As a proof of concept,a three-component condensation reaction was established to prepare thioamides directly from hydrogen sulfide and calcium carbide in high yields.Leveraging the unique properties of thioamides that possess both nucleophilic sulfur and electrophilic carbon sites,a series of novel tandem reactions were further developed to construct structurally diverse heterocyclic compounds.Our strategy not only provides a new chemical pathway for calcium carbide depolymerization,but also offers a solution for the utilization of hazardous hydrogen sulfide gas.More importantly,this approach facilitates the comprehensive and sustainable utilization of the calcium carbide resource.展开更多
Chain-growth radical polymerization of vinyl monomers is essential for producing a wide range of materials with properties tailored to specific applications.However,the inherent resistance of the polymer's C―C ba...Chain-growth radical polymerization of vinyl monomers is essential for producing a wide range of materials with properties tailored to specific applications.However,the inherent resistance of the polymer's C―C backbone to degradation raises significant concerns regarding long-term environmental persistence,which also limits their potential in biomedical applications.To address these challenges,researchers have developed strategies to either degrade preexisting vinyl polymers or incorporate cleavable units into the backbone to modify them with enhanced degradability.This review explores the various approaches aimed at achieving backbone degradability in chain-growth radical polymerization of vinyl monomers,while also highlighting future research directions for the development of application-driven degradable vinyl polymers.展开更多
The enzymatic depolymerization of polyethylene terephthalate(PET)offers a sustainable approach for the recycling of PET waste.Great efforts have been devoted to engineering PET depolymerases on the substrate binding c...The enzymatic depolymerization of polyethylene terephthalate(PET)offers a sustainable approach for the recycling of PET waste.Great efforts have been devoted to engineering PET depolymerases on the substrate binding cleft and the surrounding loops/α-helices on the surface.Here,we report the systematic engineering of whole β-sheet regions in the core of IsPETase(a PETase from Ideonella sakaiensis)via a fluorescent high-throughput screening assay.Twenty-one beneficial substitutions were obtained and iteratively recombined.The best variant,DepoPETase β,with an increase in the melting temperatures(T_(m))of 22.9℃,exhibited superior depolymerization performance and enabled complete depolymerization of100.5 g of untreated post-consumer PET(pc-PET;0.26% W_(enzyme)/W_(PET) enzyme loading)in liter-scale bioreactor at 50℃within 4 d.Crystallization and molecular dynamics simulations revealed that the improved activity and thermostability of DepoPETase β were due to enhanced hydrogen bonds and salt bridges in the β-sheet region,a more tightly packed structure of the core sheets and the surrounding helix,and improved binding of PET to the active sites.This study not only demonstrates the importance of engineering strategy in theβ-sheet region of PET hydrolases but also provides a potential PET depolymerase for large-scale PET recycling.展开更多
Green and atom-economic depolymerization of lignin remains a great challenge due toits complex non-repetitive structure and the inert property for chemo-digestion. A redoxneutrallignin depolymerization system without ...Green and atom-economic depolymerization of lignin remains a great challenge due toits complex non-repetitive structure and the inert property for chemo-digestion. A redoxneutrallignin depolymerization system without the use of extra oxidant and/or reductantover a Co-NC catalyst has been developed in this work, providing the first non-noble metalheterogeneous catalytic system for redox-neutral valorization of lignin. Mechanistic studiesbased on control reactions and deuterium labeling experiments suggest that the reactionproceeds via ametal-catalyzed dehydrogenation of C_(α)-OH to afford a carbonyl intermediate,followed by C_(β)-O bond cleavage (via hydrogenolysis) to afford monophenols and aromaticketone products. The hydrogen used for the cleavage of the C_(β)-O bond originates from thealcoholmoiety in the substrate, and the cascade dehydrogenation and hydrogenolysis stepsare highly coupled, rendering it an efficient and atom-economic process.展开更多
Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and ...Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals.However,studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored.In this review,we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics,especially for poly(phenylene sulfide)(PPS),poly(aryl ether)s including poly(ether ether ketone)(PEEK),polysulfone(PSU),polyphenylsulfone(PPSU)and polyethersulfone(PES).We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.展开更多
Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5,...Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5, HY, and MCM-22 catalysts, and the HZSM-5 catalyst showed the highest carbon yield of BTX. The reaction condition, including temperature, the gas flow rate, and the catalyst/lignin ratio, was also investigated. The carbon yield of BTX reached about 25.3 C-mol% over HZSM-5 catalyst under T=550℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2.展开更多
OBJECTIVE:To investigate the effect of manipulation treatment on knee osteoarthritis rats and the effect on Rho-associated protein kinase(ROCK)/LIM-kinase1(LIMK1)/Cofilin signaling pathway.METHOD:Fifty Specific pathog...OBJECTIVE:To investigate the effect of manipulation treatment on knee osteoarthritis rats and the effect on Rho-associated protein kinase(ROCK)/LIM-kinase1(LIMK1)/Cofilin signaling pathway.METHOD:Fifty Specific pathogen Free Sprague-Dawley rats were randomly divided into five groups(n=8 each):blank group,model group,manipulation group,celecoxib group,and manipulation combined with celecoxib group(MC group).The osteoarthritis model was established by injecting 0.2 m L 4%papain into the articular disc of the rats.After successfully establishing the model,we treated the manipulation group with pushing manipulation using one-finger-meditation to the Neixiyan(EX-LE4),Waixiyan(EX-LE5),Xuehai(SP10),Liangqiu(ST34),and Zusanli(ST36)acupoints for 10 min each time.Also,the celecoxib group was gavaged with 24 mg·kg^(-1)·d^(-1 )celecoxib,while the MC group was treated using both of these two methods.After four weeks,the cartilage of the right femur was removed for hematoxylin-eosin staining of the cartilage tissue.The expressions of interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)in serum were observed using the enzyme-linked immunosorbent assay.Besides,we detected the expressions of ROCK,LIMK1,Phospho-LIM-kinase1(Phospho-LIMK1),Cofilin,and Phospho-Cofilin by Western blot.RESULTS:Compared to the model group,the manipulation group,celecoxib group,and MC group all exhibited superior results concerning pathological morphologic changes of cartilage,as observed by hematoxylin-eosin staining and calculated using the Mankin score.Besides,in contrast to the blank group,the model group exhibited elevated serum levels of IL-1βand TNF-α(P<0.01),while the expression of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage were all higher(P<0.01).Also,the serum levels of IL-1βand TNF-αin each treatment group were lower(P<0.01)than in the model group.Moreover,there were lower expressions of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage in the manipulation group and the MC group(P<0.01).Compared with the model group,the expression of ROCK,LIMK1,PhosphoLIMK1,Cofilin,and Phospho-Cofilin in cartilage in the celecoxib group were not statistically different(P>0.05).CONCLUSION:In this study,we established that manipulation has a better curative effect than celecoxib.Manipulation inhibits the development of cytoskeleton damage in cartilage and slows articular degeneration by regulating the expression of related proteins in the cytoskeletal signaling pathway.展开更多
Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression i...Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression in cotton could be induced by PEG6000.GhADF1-RNAi transgenic cotton showed increased tolerance to drought stress during seed germination and seedling development as well as at the reproductive stage.In contrast,overexpression of GhADF1 led to a drought-sensitive phenotype in transgenic plants.GhADF1-RNAi plants produced an enlarged root system with longer primary roots,more lateral roots,increased root dry biomass,and increased cell size.In leaves of GhADF1-RNAi cotton,proline content and activities of reactive oxygen species-scavenging enzymes were increased following drought stress compared with those in wild type.GhADF1-RNAi lines showed higher water-use efficiency than the wild type,accompanied by reduced leaf stomatal density and conductance.GhADF1-RNAi cotton produced higher fiber yield in the field under both normal and drought conditions.Transcriptomic analyses identified 124 differentially expressed genes in leaves of GhADF1-RNAi lines compared with the wild type following drought treatment.Upregulated genes included those encoding transcription factors,protein kinases,heat shock proteins,and other proteins known to be involved in stress responses.We conclude that GhADF1 reduces the expression of abiotic stress-associated genes in cotton response to drought stress and may be a promising candidate gene for crop improvement by genetic manipulation.展开更多
Konjac glucomannan（KGM） is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM（DKGM）, has attracted attention because of its l...Konjac glucomannan（KGM） is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM（DKGM）, has attracted attention because of its low viscosity, improved hydrophily, and favorable physiological functions. In this review, we describe the preparation of DKGM and its prebiotic effects. Other health benefits of DKGM, covering antioxidant and immune activity, are also discussed, as well as its safety. DKGM could be a candidate for use as a tool for the treatment of various diseases, including intestinal flora imbalance, and oxidative-and immune-related disorders.展开更多
Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the ...Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the water-soluble agar polysaccharide （WSAP3） was collected. The anti-tumor activity of the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 reached 48.7% at a dose of 64mg kg^-1 after 15 days treatment. WSAP3 enhanced the aetivities of superoxide dismutase and catalase, which suggests that WSAP3 was effective in promoting the antioxidation ability and eliminating danger from free radicals. The result of flow cytometry showed that the WSAP3 had no activities of cell cycle inhibition or apoptosis-inducing activities. The anti-oxidation of WSAP3 was further confirmed by test in vitro, which might play an important role in anti-tumor activity. The immunological regulation of WSAP3, especially its effect on the phagocytosis ratio and phagocytosis index of rophage was also assayed in test in vivo.展开更多
As one of the three major components of woody biomass,lignin is a kind of natural organic polymer and the only abundant natural renewable resource with aromatic nucleus.Chemical catalysis induced depolymerization is a...As one of the three major components of woody biomass,lignin is a kind of natural organic polymer and the only abundant natural renewable resource with aromatic nucleus.Chemical catalysis induced depolymerization is an important and effective approach for lignin utilization.In particular,photocatalysis and electrocatalysis show great potential in accurately activating C-O/C-C bonds,which is a critical point of selective cleavage of lignin.In this contribution,we focus on radical and(photo)electron transfer induced reaction mechanisms of the photo(electro)catalytic depolymerization of lignin.Primarily,the general situation of Carbon-centered radicals and active oxygen species mediated lignin conversion has been discussed.Then the mechanisms for(photo)electron transfer mediated lignin depolymerization have been summarized.At the end of this review,the challenges and opportunities of photo(electro)catalysis in the applications of lignin valorization have been forecasted.展开更多
As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4...As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.展开更多
Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove...Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove the major hemicelluloses content in the solid feedstocks. Afterward, two sulfur-free pulping processes(soda and organosolv) were applied to extract the largest fraction of lignin. The extracted lignin contained in the liquors was isolated using selective precipitation methods to design a tailor-made technique for obtaining high-purity lignin(in all cases more 90% of purity was reached). Soda process allowed the extraction of more lignin(around 40%–47%) than organosolv process(lower than 20%) regardless of the lignocellulosic source employed.Once the different lignin samples were isolated and characterized, they were depolymerized for the obtaining of small phenolic compounds. Three main streams were produced after the reaction: phenolic enriched oil, residual lignin and coke. After the purification of these fractions, their quantifications and characterization were conducted.The most abundant product of the reaction was residual lignin generated by the undesirable repolymerization of the initial lignin with yields around 30%–45%. The yield of the stream enriched in phenolic oil was higher than 20%. Coke, the lowest added-value product, presented a yield lower than 12% in all the cases. Lignin from organosolv presented higher phenolic oil yields, mainly due to their lower molecular size. This parameter was, thus, considered a key factor to obtain higher yields.展开更多
A new method for regulating the synthesis of Ni Mg Fe hydrotalcites(NMF LDHs) with the addition of hydroxyl compounds was proposed. A series of NMF LDHs were prepared by the above method, and then were calcined to obt...A new method for regulating the synthesis of Ni Mg Fe hydrotalcites(NMF LDHs) with the addition of hydroxyl compounds was proposed. A series of NMF LDHs were prepared by the above method, and then were calcined to obtain the Ni Mg FeOx(NMFOx) samples. The NMFOxsamples were characterized by XRD,SEM, TG-DTG, XPS and CO2-TPD, respectively. The catalytic performance of NMFOxfor depolymerizing calcium lignosulfonate(CLS) was evaluated by hydrothermal reaction. The results showed that the addition of hydroxyl compounds favored reducing the particle sizes of NMF LDHs. For the depolymerization of CSL, the yield of liquid product increased from 45% to 75.8% with the addition of NMFOx-ethanol(NMFOxET). The liquid products were mainly phenolics, aromatics, ketones and esters. The total selectivity of oxy-containing compounds was over 90.6%, among them, the phenolics were approximately 35.2%. The valence of Ni and Fe, crystalline phase and basicity almost remained unchanged. The NMFOx-ET samples were recycled for the depolymerization of CLS, moreover, the NMFOx-ET samples had high activity and stability after 4 cycles.展开更多
The depolymerization of poly（bisphenol A carbonate）（PC） in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature （570-63...The depolymerization of poly（bisphenol A carbonate）（PC） in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature （570-633 K）, pressure （4.0-7.0 MPa）, reaction time （5-60 min）, and toluene to PC weight ratio （3.0-11.0）, were investigated, and the reaction products were determined by CrC, GC/MS and FT-IR spectrometer. It was found that the main product of the depolymerization reaction was bisphenol A（BPA）. BPA accounted for over 55.7% of the depolymerization products at reaction temperature 613 K, pressure 5.0-6.0 MPa, reaction time 15 min and toluene/PC weight ratio of around 7.0.展开更多
Synthesis and characterization of the copolymers （PAG） of α-methyl styrene （AMS） and glycidyl methacrylate （GMA） are presented. The copolymers of PAG were characterized by gel permeation chromatography （GPC）,...Synthesis and characterization of the copolymers （PAG） of α-methyl styrene （AMS） and glycidyl methacrylate （GMA） are presented. The copolymers of PAG were characterized by gel permeation chromatography （GPC）, Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （^1H-NMR） and thermogravimetery （TG）. Based on the copolymer compositions determined by ^1H-NMR, the reactivity ratios of AMS and GMA were found to be 0.105 ± 0.012 and 0.883 ± 0.046 respectively by Kelen-Tudos method. TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures. Under heating, the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions.展开更多
The depolymerization and upgrading of lignin from raw biomass,while keeping cellulose intact is important in biorefinery and various metal-based catalysts have been used in reductive catalytic fractionation,a key meth...The depolymerization and upgrading of lignin from raw biomass,while keeping cellulose intact is important in biorefinery and various metal-based catalysts have been used in reductive catalytic fractionation,a key method in"lignin-first"strategy,Recently,we found that a core-shell structured Co@CoO catalyst with CoO shell as the real active site had excellent performance in the hydrogenolysis of 5-hydromethylfurfural to 2,5-dimethylfuran due to its unique ability to dissociate H_(2)and yield active H^(δ-)species(Xiang et al.,2022).In this work,we report a one-pot depolymerization and upgrading of lignocellulose to alkylcyclohexanols,a flavour precursor,with intact cellulose over this unique core-shell structured catalyst,Co@CoO.Lignin model compounds(β-O-4,4-O-5,α-O-4)were first used to clarify the activity of Co@CoO catalyst.Then,the one-pot conversion of various organosolv lignin(birch,pine and poplar)to alkylcyclohexanols was realized with the mass yield of alkylcyclohexanols up to25.8 wt%from birch lignin under the reaction condition of 210℃,1 MPa H_(2),16 h.Finally,the corresponding woody sawdusts were used as feedstocks and found that the Co@CoO catalyst indeed preferentially depolymerized and upgraded the lignin part and obtained the same alkylcyclohexanols products with the retention of cellulose-rich pulp.The collected alkylcyclohexanols were further esterified to obtain valueadded esters,which can be used as flavors.This work will inspire the design of new efficient metal oxide catalysts in lignin fractionation and depolymerization to high-value-added chemicals with intact cellulose.展开更多
The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of ...The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of sodium arsenate in the slag and flue gas phases were approximately 30%and 70%,respectively.The addition of sodium arsenate depolymerized the fayalite structure and changed it from a crystalline state to an amorphous state.The fayalite structural changes indicated that the[AsO_(4)]tetrahedron in sodium arsenate combined with the[SiO_(4)]tetrahedron and[FeO_(4)]tetrahedron through bridging oxygen to form a silicate glass structure.The TCLP test results of the samples before and after the high temperature reaction of fayalite and sodium arsenate showed that after high temperature reaction,fayalite could effectively reduce the leaching toxicity of sodium arsenate,reducing the leaching concentration of arsenic from 3025.52 to 12.8 mg/L before and after reaction,respectively.展开更多
文摘Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated PET materials with high crystallinity remain insufficient.Here,we endeavored to improve the degradation capability of a WCCG mutant of leaf-branch compost cutinase(LCC)on a unpretreated PET substrate(crystallinity>40%)by employing iterative saturation mutagenesis.Using this method,we developed a high-throughput screening strategy appropriate for unpretreated substrates.Through extensive screening of residues around the substrate-binding groove,two variants,WCCG-sup1 and WCCG-sup2,showed good depolymerization capabilities with both high-(42%)and low-crystallinity(9%)substrates.The WCCG-sup1 variant completely depolymerized a commercial unpretreated PET product in 36 h at 72℃.In addition to enzyme thermostability and catalytic efficiency,the adsorption of enzymes onto substrates plays an important role in PET degradation.This study provides valuable insights into the structure-function relationship of LCC.
基金financially supported by the National Natural Science Foundation of China(Nos.22371240 and 22361132535)Xiamen University for the financial support。
文摘The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy UV light,while the corresponding[2+2]polymerization in solution has proved to be inefficient due to the lack of preassembly of the monomers.Herein,we demonstrate that the[2+2]polymerization of p-phenylenediacrylate monomers can be achieved in solution under visible light by employing energy transfer catalysis with 2,2'-methoxythioxanthone as a photocatalyst.Because no preassembly is required,this solution polymerization is applicable to p-phenylenediacrylate monomers with different ester groups,affording a series of cyclobutane-imbedded full-carbon chain polymers with high thermal stability,good solubility,and processibility.In addition,by virtue of the reversibility of the photo[2+2]cycloaddition,this[2+2]photopolymerization product can also undergo depolymerization to lower molecular weight polymers,suggesting the potential of this class of photopolymerization in the development of closed-loop chemical recyclable polymers.
基金the National Natural Science Foundation of China(Nos.22379075,22471114,U23A20528)the Group Project of Developing Inner Mongolia through Talents from the Talents Work Leading Group under the CPC Inner Mongolia Autonomous Regional Committee(No.2025TEL04)+2 种基金Natural Science Foundation of Inner Mongolia Autonomous Region(No.2024LHMS02011)the Innovative Research Team in Universities of Inner Mongolia Autonomous Region(No.NMGIRT2212)Basic Scientific Research Funds of Universities directly under the Inner Mongolia Autonomous Region(Nos.ZTY2025013 and JY20240076)for financial support。
文摘Calcium carbide,a bulky and cheap raw chemical,is traditionally depolymerized by water to release acetylene,allowing the downstream organic transformation.In this study,hydrogen sulfide(H_(2)S),an industrial waste gas,has been exploited to depolymerize calcium carbide,which represents a strategy for the comprehensive utilization of both hydrogen sulfide and calcium carbide.As a proof of concept,a three-component condensation reaction was established to prepare thioamides directly from hydrogen sulfide and calcium carbide in high yields.Leveraging the unique properties of thioamides that possess both nucleophilic sulfur and electrophilic carbon sites,a series of novel tandem reactions were further developed to construct structurally diverse heterocyclic compounds.Our strategy not only provides a new chemical pathway for calcium carbide depolymerization,but also offers a solution for the utilization of hazardous hydrogen sulfide gas.More importantly,this approach facilitates the comprehensive and sustainable utilization of the calcium carbide resource.
基金funding from the National Natural Science Foundation of China(No.22401037)funding from JST CREST(No.JPMJCR23L1)。
文摘Chain-growth radical polymerization of vinyl monomers is essential for producing a wide range of materials with properties tailored to specific applications.However,the inherent resistance of the polymer's C―C backbone to degradation raises significant concerns regarding long-term environmental persistence,which also limits their potential in biomedical applications.To address these challenges,researchers have developed strategies to either degrade preexisting vinyl polymers or incorporate cleavable units into the backbone to modify them with enhanced degradability.This review explores the various approaches aimed at achieving backbone degradability in chain-growth radical polymerization of vinyl monomers,while also highlighting future research directions for the development of application-driven degradable vinyl polymers.
基金funded by the National Key Research and Development Program of China(2023YFC3903300)the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIPIJCP-003,TSBICIP-KJGG-009-0203,and TSBICIP-BRFI-005)the Innovation Fund of Haihe Laboratory of Synthetic Biology(22HHSWSS00018)。
文摘The enzymatic depolymerization of polyethylene terephthalate(PET)offers a sustainable approach for the recycling of PET waste.Great efforts have been devoted to engineering PET depolymerases on the substrate binding cleft and the surrounding loops/α-helices on the surface.Here,we report the systematic engineering of whole β-sheet regions in the core of IsPETase(a PETase from Ideonella sakaiensis)via a fluorescent high-throughput screening assay.Twenty-one beneficial substitutions were obtained and iteratively recombined.The best variant,DepoPETase β,with an increase in the melting temperatures(T_(m))of 22.9℃,exhibited superior depolymerization performance and enabled complete depolymerization of100.5 g of untreated post-consumer PET(pc-PET;0.26% W_(enzyme)/W_(PET) enzyme loading)in liter-scale bioreactor at 50℃within 4 d.Crystallization and molecular dynamics simulations revealed that the improved activity and thermostability of DepoPETase β were due to enhanced hydrogen bonds and salt bridges in the β-sheet region,a more tightly packed structure of the core sheets and the surrounding helix,and improved binding of PET to the active sites.This study not only demonstrates the importance of engineering strategy in theβ-sheet region of PET hydrolases but also provides a potential PET depolymerase for large-scale PET recycling.
基金supported by the National Key R&D Program of China(No.2023YFA1507902)the Science and Technology Bureau of Dalian City(No.2021RT04)+3 种基金the Shaanxi Provincial Science and Technology Department(Nos.2024JC-YBQN-0100 and QCYRCXM-2023-079)the Youth innovation team project of Shaanxi Province Education Department(No.23JP199)the Science and Technology Plan Project of Yulin Government(No.2023-CXY-137)the Initial Scientific Research Fund of High Level Talents in Yulin University(No.2023GK44).
文摘Green and atom-economic depolymerization of lignin remains a great challenge due toits complex non-repetitive structure and the inert property for chemo-digestion. A redoxneutrallignin depolymerization system without the use of extra oxidant and/or reductantover a Co-NC catalyst has been developed in this work, providing the first non-noble metalheterogeneous catalytic system for redox-neutral valorization of lignin. Mechanistic studiesbased on control reactions and deuterium labeling experiments suggest that the reactionproceeds via ametal-catalyzed dehydrogenation of C_(α)-OH to afford a carbonyl intermediate,followed by C_(β)-O bond cleavage (via hydrogenolysis) to afford monophenols and aromaticketone products. The hydrogen used for the cleavage of the C_(β)-O bond originates from thealcoholmoiety in the substrate, and the cascade dehydrogenation and hydrogenolysis stepsare highly coupled, rendering it an efficient and atom-economic process.
基金supported by the National Natural Science Foundation of China(Nos.22125103 and 22301077)STCSM(22JC140100)Shanghai Pujiang Program(No.22PJ1403200)。
文摘Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals.However,studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored.In this review,we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics,especially for poly(phenylene sulfide)(PPS),poly(aryl ether)s including poly(ether ether ketone)(PEEK),polysulfone(PSU),polyphenylsulfone(PPSU)and polyethersulfone(PES).We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.
基金ACKNOWLEDGMENTS This work was supported by the National Key Basic Program of China （No.2013CB228105） and the National Natural Science Foundation of China （No.51161140331）.
文摘Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5, HY, and MCM-22 catalysts, and the HZSM-5 catalyst showed the highest carbon yield of BTX. The reaction condition, including temperature, the gas flow rate, and the catalyst/lignin ratio, was also investigated. The carbon yield of BTX reached about 25.3 C-mol% over HZSM-5 catalyst under T=550℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2.
基金Supported by the National Natural Science Foundation of China(No.81273870)Chongqing Municipal Health and Family Planning Commission and Chongqing Municipal Science and Technology Commission Jointly Funded Key Research Projects in Traditional Chinese Medicine(No.ZY201801007)Beibei District Chongqing Basic Research and Frontier Exploration Project(No.2019-6)。
文摘OBJECTIVE:To investigate the effect of manipulation treatment on knee osteoarthritis rats and the effect on Rho-associated protein kinase(ROCK)/LIM-kinase1(LIMK1)/Cofilin signaling pathway.METHOD:Fifty Specific pathogen Free Sprague-Dawley rats were randomly divided into five groups(n=8 each):blank group,model group,manipulation group,celecoxib group,and manipulation combined with celecoxib group(MC group).The osteoarthritis model was established by injecting 0.2 m L 4%papain into the articular disc of the rats.After successfully establishing the model,we treated the manipulation group with pushing manipulation using one-finger-meditation to the Neixiyan(EX-LE4),Waixiyan(EX-LE5),Xuehai(SP10),Liangqiu(ST34),and Zusanli(ST36)acupoints for 10 min each time.Also,the celecoxib group was gavaged with 24 mg·kg^(-1)·d^(-1 )celecoxib,while the MC group was treated using both of these two methods.After four weeks,the cartilage of the right femur was removed for hematoxylin-eosin staining of the cartilage tissue.The expressions of interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)in serum were observed using the enzyme-linked immunosorbent assay.Besides,we detected the expressions of ROCK,LIMK1,Phospho-LIM-kinase1(Phospho-LIMK1),Cofilin,and Phospho-Cofilin by Western blot.RESULTS:Compared to the model group,the manipulation group,celecoxib group,and MC group all exhibited superior results concerning pathological morphologic changes of cartilage,as observed by hematoxylin-eosin staining and calculated using the Mankin score.Besides,in contrast to the blank group,the model group exhibited elevated serum levels of IL-1βand TNF-α(P<0.01),while the expression of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage were all higher(P<0.01).Also,the serum levels of IL-1βand TNF-αin each treatment group were lower(P<0.01)than in the model group.Moreover,there were lower expressions of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage in the manipulation group and the MC group(P<0.01).Compared with the model group,the expression of ROCK,LIMK1,PhosphoLIMK1,Cofilin,and Phospho-Cofilin in cartilage in the celecoxib group were not statistically different(P>0.05).CONCLUSION:In this study,we established that manipulation has a better curative effect than celecoxib.Manipulation inhibits the development of cytoskeleton damage in cartilage and slows articular degeneration by regulating the expression of related proteins in the cytoskeletal signaling pathway.
基金supported by the National Natural Science Foundation of China(31601350)the Project of Transgenic Research from the Ministry of Science and Technology of China(2016ZX08005-004-007)+1 种基金the Fundamental Research Project of Shanxi Province(20210302123381)the Science and Technology Innovation Project of Higher Education Institutions of Shanxi Province(2021L115).
文摘Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression in cotton could be induced by PEG6000.GhADF1-RNAi transgenic cotton showed increased tolerance to drought stress during seed germination and seedling development as well as at the reproductive stage.In contrast,overexpression of GhADF1 led to a drought-sensitive phenotype in transgenic plants.GhADF1-RNAi plants produced an enlarged root system with longer primary roots,more lateral roots,increased root dry biomass,and increased cell size.In leaves of GhADF1-RNAi cotton,proline content and activities of reactive oxygen species-scavenging enzymes were increased following drought stress compared with those in wild type.GhADF1-RNAi lines showed higher water-use efficiency than the wild type,accompanied by reduced leaf stomatal density and conductance.GhADF1-RNAi cotton produced higher fiber yield in the field under both normal and drought conditions.Transcriptomic analyses identified 124 differentially expressed genes in leaves of GhADF1-RNAi lines compared with the wild type following drought treatment.Upregulated genes included those encoding transcription factors,protein kinases,heat shock proteins,and other proteins known to be involved in stress responses.We conclude that GhADF1 reduces the expression of abiotic stress-associated genes in cotton response to drought stress and may be a promising candidate gene for crop improvement by genetic manipulation.
基金Project supported by the National First-Class Discipline Program of Light Industry Technology and Engineering(Nos.LITE2018-18 and LITE2018-11) of Chinathe Transformation Project for Major Scientific and Technological Achievements in Jiangsu Province(No.BA2015006)+1 种基金the Industry-Academia Cooperation Innovation Fund Project of Jiangsu Province(No.BY2016022-19)the National Key Technologies R&D Program of China for the 12th Five-year Plan(No.2012BAD33B06)
文摘Konjac glucomannan（KGM） is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM（DKGM）, has attracted attention because of its low viscosity, improved hydrophily, and favorable physiological functions. In this review, we describe the preparation of DKGM and its prebiotic effects. Other health benefits of DKGM, covering antioxidant and immune activity, are also discussed, as well as its safety. DKGM could be a candidate for use as a tool for the treatment of various diseases, including intestinal flora imbalance, and oxidative-and immune-related disorders.
文摘Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the water-soluble agar polysaccharide （WSAP3） was collected. The anti-tumor activity of the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 reached 48.7% at a dose of 64mg kg^-1 after 15 days treatment. WSAP3 enhanced the aetivities of superoxide dismutase and catalase, which suggests that WSAP3 was effective in promoting the antioxidation ability and eliminating danger from free radicals. The result of flow cytometry showed that the WSAP3 had no activities of cell cycle inhibition or apoptosis-inducing activities. The anti-oxidation of WSAP3 was further confirmed by test in vitro, which might play an important role in anti-tumor activity. The immunological regulation of WSAP3, especially its effect on the phagocytosis ratio and phagocytosis index of rophage was also assayed in test in vivo.
基金financial support of the National Natural Science Foundation of China,China(Grant No.21736003,21975082)the Guangdong Basic and Applied Basic Research Foundation(Grant Number:2019A1515011472)the Science and Technology Program of Guangzhou(Grant Number:202102080479)。
文摘As one of the three major components of woody biomass,lignin is a kind of natural organic polymer and the only abundant natural renewable resource with aromatic nucleus.Chemical catalysis induced depolymerization is an important and effective approach for lignin utilization.In particular,photocatalysis and electrocatalysis show great potential in accurately activating C-O/C-C bonds,which is a critical point of selective cleavage of lignin.In this contribution,we focus on radical and(photo)electron transfer induced reaction mechanisms of the photo(electro)catalytic depolymerization of lignin.Primarily,the general situation of Carbon-centered radicals and active oxygen species mediated lignin conversion has been discussed.Then the mechanisms for(photo)electron transfer mediated lignin depolymerization have been summarized.At the end of this review,the challenges and opportunities of photo(electro)catalysis in the applications of lignin valorization have been forecasted.
文摘As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.
基金the Spanish Ministry of Economy and Competitiveness(CTQ2013-41246-R)the Department of Education of the Basque Government(project IT1008-16)the University of the Basque Country(postdoctoral fellowship no.ESPDOC15/044)for financially supporting this work
文摘Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove the major hemicelluloses content in the solid feedstocks. Afterward, two sulfur-free pulping processes(soda and organosolv) were applied to extract the largest fraction of lignin. The extracted lignin contained in the liquors was isolated using selective precipitation methods to design a tailor-made technique for obtaining high-purity lignin(in all cases more 90% of purity was reached). Soda process allowed the extraction of more lignin(around 40%–47%) than organosolv process(lower than 20%) regardless of the lignocellulosic source employed.Once the different lignin samples were isolated and characterized, they were depolymerized for the obtaining of small phenolic compounds. Three main streams were produced after the reaction: phenolic enriched oil, residual lignin and coke. After the purification of these fractions, their quantifications and characterization were conducted.The most abundant product of the reaction was residual lignin generated by the undesirable repolymerization of the initial lignin with yields around 30%–45%. The yield of the stream enriched in phenolic oil was higher than 20%. Coke, the lowest added-value product, presented a yield lower than 12% in all the cases. Lignin from organosolv presented higher phenolic oil yields, mainly due to their lower molecular size. This parameter was, thus, considered a key factor to obtain higher yields.
基金Supported by the Program for National Natural Science Foundation of China(No.51674089)Excellent Youth Foundation of Heilongjiang Province of China(No.JC2018002)+2 种基金Postdoctoral Scientific Research Development Fund of Heilongjiang Province of China(No.LBH-Q16037)the Youth Fund of Northeast Petroleum University(No.2018QNL-17)the Postgraduate Innovative Research Projects of Northeast Petroleum University(No.YJSCX2017-014NEPU)
文摘A new method for regulating the synthesis of Ni Mg Fe hydrotalcites(NMF LDHs) with the addition of hydroxyl compounds was proposed. A series of NMF LDHs were prepared by the above method, and then were calcined to obtain the Ni Mg FeOx(NMFOx) samples. The NMFOxsamples were characterized by XRD,SEM, TG-DTG, XPS and CO2-TPD, respectively. The catalytic performance of NMFOxfor depolymerizing calcium lignosulfonate(CLS) was evaluated by hydrothermal reaction. The results showed that the addition of hydroxyl compounds favored reducing the particle sizes of NMF LDHs. For the depolymerization of CSL, the yield of liquid product increased from 45% to 75.8% with the addition of NMFOx-ethanol(NMFOxET). The liquid products were mainly phenolics, aromatics, ketones and esters. The total selectivity of oxy-containing compounds was over 90.6%, among them, the phenolics were approximately 35.2%. The valence of Ni and Fe, crystalline phase and basicity almost remained unchanged. The NMFOx-ET samples were recycled for the depolymerization of CLS, moreover, the NMFOx-ET samples had high activity and stability after 4 cycles.
文摘The depolymerization of poly（bisphenol A carbonate）（PC） in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature （570-633 K）, pressure （4.0-7.0 MPa）, reaction time （5-60 min）, and toluene to PC weight ratio （3.0-11.0）, were investigated, and the reaction products were determined by CrC, GC/MS and FT-IR spectrometer. It was found that the main product of the depolymerization reaction was bisphenol A（BPA）. BPA accounted for over 55.7% of the depolymerization products at reaction temperature 613 K, pressure 5.0-6.0 MPa, reaction time 15 min and toluene/PC weight ratio of around 7.0.
文摘Synthesis and characterization of the copolymers （PAG） of α-methyl styrene （AMS） and glycidyl methacrylate （GMA） are presented. The copolymers of PAG were characterized by gel permeation chromatography （GPC）, Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （^1H-NMR） and thermogravimetery （TG）. Based on the copolymer compositions determined by ^1H-NMR, the reactivity ratios of AMS and GMA were found to be 0.105 ± 0.012 and 0.883 ± 0.046 respectively by Kelen-Tudos method. TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures. Under heating, the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions.
基金supported financially by the National Natural Science Foundation of China(Nos.21832002,21808063,22002043,21872050)。
文摘The depolymerization and upgrading of lignin from raw biomass,while keeping cellulose intact is important in biorefinery and various metal-based catalysts have been used in reductive catalytic fractionation,a key method in"lignin-first"strategy,Recently,we found that a core-shell structured Co@CoO catalyst with CoO shell as the real active site had excellent performance in the hydrogenolysis of 5-hydromethylfurfural to 2,5-dimethylfuran due to its unique ability to dissociate H_(2)and yield active H^(δ-)species(Xiang et al.,2022).In this work,we report a one-pot depolymerization and upgrading of lignocellulose to alkylcyclohexanols,a flavour precursor,with intact cellulose over this unique core-shell structured catalyst,Co@CoO.Lignin model compounds(β-O-4,4-O-5,α-O-4)were first used to clarify the activity of Co@CoO catalyst.Then,the one-pot conversion of various organosolv lignin(birch,pine and poplar)to alkylcyclohexanols was realized with the mass yield of alkylcyclohexanols up to25.8 wt%from birch lignin under the reaction condition of 210℃,1 MPa H_(2),16 h.Finally,the corresponding woody sawdusts were used as feedstocks and found that the Co@CoO catalyst indeed preferentially depolymerized and upgraded the lignin part and obtained the same alkylcyclohexanols products with the retention of cellulose-rich pulp.The collected alkylcyclohexanols were further esterified to obtain valueadded esters,which can be used as flavors.This work will inspire the design of new efficient metal oxide catalysts in lignin fractionation and depolymerization to high-value-added chemicals with intact cellulose.
基金the financial supports from the National Natural Science Foundation of China(No.51634010)National Key R&D Program of China(No.2018YFC1900300).
文摘The interaction mechanism between sodium arsenate and fayalite-type copper slag at 1200℃was investigated through XRD,XPS,HRTEM,TCLP and other technical means and methods.The results indicated that the proportions of sodium arsenate in the slag and flue gas phases were approximately 30%and 70%,respectively.The addition of sodium arsenate depolymerized the fayalite structure and changed it from a crystalline state to an amorphous state.The fayalite structural changes indicated that the[AsO_(4)]tetrahedron in sodium arsenate combined with the[SiO_(4)]tetrahedron and[FeO_(4)]tetrahedron through bridging oxygen to form a silicate glass structure.The TCLP test results of the samples before and after the high temperature reaction of fayalite and sodium arsenate showed that after high temperature reaction,fayalite could effectively reduce the leaching toxicity of sodium arsenate,reducing the leaching concentration of arsenic from 3025.52 to 12.8 mg/L before and after reaction,respectively.
