Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving t...Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving this kind of polymers,yet with linear microstructures.Ringopening metathesis polymerization(ROMP)offers another promising avenue for affording functionalized polyolefins.This method exhibits high polar group tolerance and the ability to precisely regulate polymer branches.In this study,we report the method for producing mechanochromic branched polyethylenes via ROMP.By employing the terpolymerization of a well-designed monomer containing the mechanochromic group,NB-ABF,with cyclooctene(COE)and long-chain 5-hexylcyclooctene(COE-C6),following by hydrogenation process,we synthesized a range of functionalized branched polyethylenes characterized by varied branching density and polar monomer incorporation.These polymers bear a structural resemblance to functionalized ethylene-octene copolymers.After crosslinking,mechanochromophores are generated,and mechanochromism is achieved in uniaxial tensile testing.A comprehensive assessment reveals that both the incorporation of polar monomers and variations in branching density significantly influence their mechanical properties.Notably,upon stretching,these materials display pronounced visible color change,confirming the successful development of mechanochromic branched polyethylenes.展开更多
Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branch...Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distributionwas also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four differentpolyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single sitecatalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with meltingtemperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethyleneand the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used tocalculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branchcontent were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branchcontent polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient wasnecessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling tobelow ambient because the calibration data were not performed in this way.展开更多
Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyeth...Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and (M) over bar(w)/(M) over bar(n). This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.展开更多
The molecular structure of polyethylene (PE) samples with various comonomers including propylene, I-butane and 1-hexene was investigated by DSC and C-13-NMR techniques. The density of the samples varies from 0.948 g/c...The molecular structure of polyethylene (PE) samples with various comonomers including propylene, I-butane and 1-hexene was investigated by DSC and C-13-NMR techniques. The density of the samples varies from 0.948 g/cm(3) to 0.917 g/cm(3), and the molecular weight determined by the GPC method is in the range of 1 similar to2 x 10(5). The branch paint content of the samples was determined by C-13-NMR measurements and was found to be less than 20 per 1000 C atoms along the main chain. Crystallization segregation DSC technique (CSDSC) was used to characterize the branch point distribution or the segment length distribution of PEs. The crystallization segregation was performed in a successive annealing process at decreasing temperatures. The interval of two successive annealing temperatures was 6 K, and the time length of each annealing step was 2.5 h. The CSDSC results clearly indicate that all the PE samples used, including some metallocene PEs, more or less exhibit their non-uniformity in segment length distribution, and bimodal or multimodal CSDSC curves were usually observed. For quantitative characterization of the CSDSC curves and the segment length distribution two parameters, the average melting point, T-mAV, and the root-mean-square deviation of melting temperature, (DeltaT(m)(AV)(2))(1/2), were proposed. TmAV is corresponding to the average segment length due to branching and (DeltaT(m)(AV)(2))(1/2) gives information about the: width of the segment length distribution. Experimental results show that both the degree of average melting temperature depression and the width of the distribution seem to increase with increasing the branching content and are dependent on the type of comonomers. Very good reproducibility and additivity of the CSDSC method were evidenced experimentally. It was concluded that the CSDSC technique is a sensitive and convenient method for characterizing the segment length distribution of branched polyethylenes and will be of great interest in structure-property relationship studies of crystalline polymers.展开更多
A series of hydroxyl-terminated polyethylenes(HTPE)bearing various functional side groups(e.g.carboxyl,ester and butane groups)were synthesized by the combination of ring opening metathesis polymerization(ROMP)and vis...A series of hydroxyl-terminated polyethylenes(HTPE)bearing various functional side groups(e.g.carboxyl,ester and butane groups)were synthesized by the combination of ring opening metathesis polymerization(ROMP)and visible light photocatalytic thiol-ene reaction.The products are named as a,w-dihydroxyl-polyllpropionyloxythio)methinetrimethylene](HTPECarboxy),a,w dihydroxy-poly(methylpropionatethio)methinetrimethylene](HTPEeser)and a,wdihydroxyl-poly[(butylthio)methinetrimethylene](HTPEbutane)respectively.The investigation of ROMP indicated that the molecular weight of resultant hydroxy-terminated polybutadiene(HTPB)can be tailored by varying the feed ratios of monomer to chain transfer agent(CTA).The exploration of the photocatalytic thiol-ene reaction between HTPB precursor and methyl-3-mercaptopropionate revealed that blue light as well as oxygen accelerated the reaction.1H-NMR and 13C-NMR results verified all the double bonds in HTPB can be modified,and the main chain of resultant polymer can be considered as polyethylene.Subsequently,relationship between the structure of side groups and the thermal properties of functional PEs was studied.And the results suggested that the Tg was in the order of HTPEbuane<HTPEester<HTPEarboxy+.Greater interaction between side groups resulted in higher Tg.Moreover,all the functional PE samples exhibited poor thermostability as compared to HTPB.Finally,the promising applications for functional PEs were explored.HTPEcarboxy1 can be utilized as a smart material with pH-responsive properties due to its pH-dependent ionization of carboxyl side groups.HTPEbutane can be employed as a macro-initiator for building the triblock copolymer due to the presence of active hydroxyl end groups.HTPEester can serve as a plasticizer for PVC which can enhance the ductilityt of PVC without obviously sacrificing strength.展开更多
Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,red...Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.展开更多
The series of 2-（1-（2,4-dibenzhydrylnaphthylimino）ethyl）-6-（1-（arylimino）ethyl）pyridine derivatives and their cobalt chlorides （Col-Co5） were synthesized and fully characterized. The representative complexes...The series of 2-（1-（2,4-dibenzhydrylnaphthylimino）ethyl）-6-（1-（arylimino）ethyl）pyridine derivatives and their cobalt chlorides （Col-Co5） were synthesized and fully characterized. The representative complexes Co2 and Co3 were confirmed by single crystal X-ray diffraction analyses, indicating pseudo-square-pyramidal geometry around the cobalt centre. All cobalt complexes, activated with either methylaluminoxane （MAO） or modified methylaluminoxane （MMAO）, exhibited high activities towards ethylene polymerization, and produced polyethylenes with high molecular weight and highly linear feature as well as unimodal distribution.展开更多
Aiming at accessing polyethylene-bearing in-chain degradable functionality,copolymerization of carbon dioxide(CO_(2))with ethylene has long been recognized as a significant but highly challenging transformation.Nevert...Aiming at accessing polyethylene-bearing in-chain degradable functionality,copolymerization of carbon dioxide(CO_(2))with ethylene has long been recognized as a significant but highly challenging transformation.Nevertheless,most trials have resulted in ethylene homopolymerization because of the endothermic property and high energy barriers of CO_(2)insertion during polymer chain propagation.Here we report an unprecedented tandem reaction protocol for the synthesis of polyethylenes with in-chain carbonyls from CO_(2)and ethylene by the combination of photocatalytic CO_(2)reduction and palladium-catalyzed coordination/insertion polymerization.This protocol provides an easy way to adjust the carbonyl content(from 0.13 to 12 mol%)and insertion selectivity(up to 99%isolated carbonyls)of the polyethylene copolymers,which enables the polymers tomaintain the main properties of highdensity polyethylene and simultaneously endows them with good photodegradability.In addition,besides apolar polyethylene copolymers,polar-functionalized polyethylenes with in-chain isolated carbonyls can also be synthesized from CO_(2),ethylene and a polar monomer using the same protocol.We believe our present work sheds new light on the synthesis of degradable polyethylenes by employing CO_(2)as a green carbonyl source.展开更多
Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene g...Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves.We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor recovery.Furthermore,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles.In this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve.Young adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of PEG.Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site.The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively.At 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase.PEG-fusion repair reestablished axonal continuity.Compared to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal areas.Unexpectedly,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair.This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair,supporting the use of this novel repair methodology over currently available treatments.展开更多
To enhance the hydrophilicity and antistatic properties of the polyethylene terephthalate(PET)fabric,the lawsone dye was employed in dyeing the PET fabric.It was dissolved in ethanol/deionized water mixture and deioni...To enhance the hydrophilicity and antistatic properties of the polyethylene terephthalate(PET)fabric,the lawsone dye was employed in dyeing the PET fabric.It was dissolved in ethanol/deionized water mixture and deionized water separately,forming different lawsone dye solutions(LDSs).The study investigated how the compounds in the LDS improve the surface properties and color durability of the PET fabric,resulting in increased dye uptake.An infrared dyeing machine was utilized to expedite the reactions between the lawsone dye and the PET fabric.Additionally,the chemical composition of the dyed PET fabric was verified using techniques such as Fourier transform infrared(FTIR)spectroscopy,X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and ultraviolet-visible(UV-Vis)spectrophotometry.The K/S value was measured to assess color durability.After dyeing,the PET fabric exhibited high hydrophilicity which improved the hygroscopicity of the PET fabric and thus the conductivity of the PET fabric surface increased,thereby providing an antistatic effect.展开更多
With the wide application of electromagnetic wave,a high performance electromagnetic shielding material is urgently needed to solve the harm caused by electromagnetic wave.Complete cross-linking strategy is adopted in...With the wide application of electromagnetic wave,a high performance electromagnetic shielding material is urgently needed to solve the harm caused by electromagnetic wave.Complete cross-linking strategy is adopted in this paper.Polyacrylamide(PAM)was synthesized by in-situ polymerization of acrylamide(AM)monomer.The obtained PAM was blended with polyethylene glycol(PEG)to prepare PAM/PEG hydrogels and form rigid support structures.Subsequently,the modified carbon nanotubes(S-CNTs)were incorpor-ated into sodium alginate(SA)and PAM/PEG.Finally,Na+was used to trigger SA self-assembly,which significantly improved the mechanical properties and electrical conductivity of the hydrogels,and prepared PAM/PEG/SA/S-CNTs-Na hydrogels with high tough-ness and strong electromagnetic interference(EMI)shielding efficiency(SE).The results showed that the compressive strength of PAM/PEG/SA/S-CNTs-Na hydrogel was 19.05 MPa,which was 7.69%higher than that of PAM/PEG hydrogel(17.69 MPa).More en-couraging,the average EMI SE of PAM/PEG/SA/S-CNTs-Na hydrogels at a thickness of only 3 mm and a CNTs content of 16.53wt%was 32.92 dB,which is 113.21%higher than that of PAM/PEG hydrogels(15.44 dB).展开更多
Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripher...Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.展开更多
Successful polyethylene glycol fusion(PEG-fusion)of severed axons following peripheral nerve injuries for PEG-fused axons has been reported to:(1)rapidly restore electrophysiological continuity;(2)prevent distal Walle...Successful polyethylene glycol fusion(PEG-fusion)of severed axons following peripheral nerve injuries for PEG-fused axons has been reported to:(1)rapidly restore electrophysiological continuity;(2)prevent distal Wallerian Degeneration and maintain their myelin sheaths;(3)promote primarily motor,voluntary behavioral recoveries as assessed by the Sciatic Functional Index;and,(4)rapidly produce correct and incorrect connections in many possible combinations that produce rapid and extensive recovery of functional peripheral nervous system/central nervous system connections and reflex(e.g.,toe twitch)or voluntary behaviors.The preceding companion paper describes sensory terminal field reo rganization following PEG-fusion repair of sciatic nerve transections or ablations;howeve r,sensory behavioral recovery has not been explicitly explored following PEG-fusion repair.In the current study,we confirmed the success of PEG-fusion surgeries according to criteria(1-3)above and more extensively investigated whether PEG-fusion enhanced mechanical nociceptive recovery following sciatic transection in male and female outbred Sprague-Dawley and inbred Lewis rats.Mechanical nociceptive responses were assessed by measuring withdrawal thresholds using von Frey filaments on the dorsal and midplantar regions of the hindpaws.Dorsal von Frey filament tests were a more reliable method than plantar von Frey filament tests to assess mechanical nociceptive sensitivity following sciatic nerve transections.Baseline withdrawal thresholds of the sciatic-mediated lateral dorsal region differed significantly across strain but not sex.Withdrawal thresholds did not change significantly from baseline in chronic Unoperated and Sham-operated rats.Following sciatic transection,all rats exhibited severe hyposensitivity to stimuli at the lateral dorsal region of the hindpaw ipsilateral to the injury.However,PEG-fused rats exhibited significantly earlier return to baseline withdrawal thresholds than Negative Control rats.Furthermore,PEG-fused rats with significantly improved Sciatic Functional Index scores at or after 4 weeks postoperatively exhibited yet-earlier von Frey filament recove ry compared with those without Sciatic Functional Index recovery,suggesting a correlation between successful PEG-fusion and both motor-dominant and sensory-dominant behavioral recoveries.This correlation was independent of the sex or strain of the rat.Furthermore,our data showed that the acceleration of von Frey filament sensory recovery to baseline was solely due to the PEG-fused sciatic nerve and not saphenous nerve collateral outgrowths.No chronic hypersensitivity developed in any rat up to 12 weeks.All these data suggest that PEG-fusion repair of transection peripheral nerve injuries co uld have important clinical benefits.展开更多
With the aim to effectively depolymerize polyethylene terephthalate(PET)under mild reaction conditions,PET methanolysis and dimethyl terephthalate(DMT)hydrolysis are integrated in a catalyst system.Firstly,methanolysi...With the aim to effectively depolymerize polyethylene terephthalate(PET)under mild reaction conditions,PET methanolysis and dimethyl terephthalate(DMT)hydrolysis are integrated in a catalyst system.Firstly,methanolysis of PET to DMT is achieved over Cu-Mg-Al oxide catalyst.Next,terephthalic acid(TPA)is prepared by DMT hydrolysis.It is found that hydrolysis of DMT to TPA can be promoted by introducing trace amount of water in this catalyst system.CuO-MgO-4.5Al_2O_(3)catalyst demonstrates the excellent catalytic performance for the depolymerization of PET with high conversion rate and TPA yield(100%and 99.5%,respectively)after reaction at 160℃for 6 h,which provides a new idea for the depolymerization of PET.展开更多
In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypro...In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.展开更多
This work proposed a strategy to improve the caking index of polyethylene terephthalate(PET)waste,in which low-temperature pyrolysis treatment(LTPT)was used to depolymerize PET waste.The mechanism of G modification wa...This work proposed a strategy to improve the caking index of polyethylene terephthalate(PET)waste,in which low-temperature pyrolysis treatment(LTPT)was used to depolymerize PET waste.The mechanism of G modification was revealed combining thermogravimetric(TG)analysis,Fourier transform infrared spectroscopy,pyrolysis-gas chromatography with mass spectrometric detection,and solid-state 13C nuclear magnetic resonance spectroscopy.Furthermore,crucible coking experiments were also conducted using industrial coal mixture and treated PET with the optimum G(PET300)or raw PET to evaluate the applicability of PET waste in coal-blending coking.According to characterization results of coke reactivity(CR),coke strength after reaction(CSR)indices,TG-related curves,pore volumes,and Raman spectra of the resultant cokes,LTPT could greatly increase the G of PET,and the optimum temperature was 300℃.Specifically,compared with the coke obtained from the blend with PET,the CR of the coke produced from the blend with PET300 decreased by 4.9%,whereas the CSR of the increased by 7.4%,suggesting that LTPT could increase the proportion of PET used for coal-blending coking.The improvement in G is attributed to the changes in C-O/C=O ratio,aliphatic H and aromaticity caused by LTPT.展开更多
A nanomicelle(denoted as TPGS/Ppa)was fabricated via the coassembly of the amphiphilic D-α-tocopheryl polyethylene glycol 1000 succinate(TPGS)and the hydrophobic photosensitizer pyropheophorbide a(Ppa)for photodynami...A nanomicelle(denoted as TPGS/Ppa)was fabricated via the coassembly of the amphiphilic D-α-tocopheryl polyethylene glycol 1000 succinate(TPGS)and the hydrophobic photosensitizer pyropheophorbide a(Ppa)for photodynamic therapy(PDT).The obtained nanomicelle possessed a spherical structure with a diameter of(18.0±2.2)nm and a zeta potential of approximately -18 mV.Besides,the nanomicelle exhibited excellent photostability,biocompatibility,and phototoxicity,and could effectively reach the tumor region via the enhanced permeability and retention effect.Additionally,it could be found that the TPGS/Ppa nanomicelle exhibited higher phototoxicity against 4T1 murine mammary cancer cells than free Ppa.In the 4T1 tumor-bearing mouse model,the nanomicelle showed an excellent antitumor therapeutic effect.This study develops a new type of photodynamic nanomicelle TPGS/Ppa,which can increase the accumulation of drugs and prolong their tumor retention time,providing a feasible strategy for realizing the delivery of small-molecule hydrophobic drugs and tumor PDT.展开更多
This paper presents findings of a study on solid wastes conversion into fuels through pyrolysis of plastic materials, presenting an alternative renewable approach for waste management. Investigations were conducted on...This paper presents findings of a study on solid wastes conversion into fuels through pyrolysis of plastic materials, presenting an alternative renewable approach for waste management. Investigations were conducted on conversion of polypropylene (PP), low-density polyethylene (LDPE) and high-density polyethylene (HDPE) under normal and catalyst mediated process conditions. Plastic wastes were collected from various dumpsites in Nairobi and segregated using plastic resin codes to various classes. Samples were cleaned, dried and shredded to 2 mm and fed into a pyrolysis reactor. The pyrolysis process was conducted at between 220˚C and 420˚C. Pyrolysis gases were condensed in a shell and coil condenser and the incondensable gases were stored in gasbags. Liquid fuels were analysed using Gas chromatograph with a mass spectroscopic detector and Fourier Transform Infrared Spectrometry. The results revealed that the most optimal process conditions were a temperature range of 220˚C - 420˚C at a heating rate of 10˚C per minute. Under these conditions, the oil yields were 53.72% for PP, 62.10% for LDPE, and 64.14% for HDPE. As the heating rate increased from 10˚C/min to 20˚C/min, gas yields increased, rising from 28.05% to 31.12% in PP, 14.96% to 30.62% in LDPE, and 18.51% to 29.49% in HDPE. The introduction of Fe2O3 and Al2O3 catalyst significantly enhanced gas production during pyrolysis, increasing yields from 18% to 61% and 47% respectively.展开更多
Electrocatalytic CO_(2)reduction(CO_(2)RR)is spurring intensive research interest,where many attentions have been paid to catalyst design and mechanism study.Electrode near-surface microenvironment matters fundamental...Electrocatalytic CO_(2)reduction(CO_(2)RR)is spurring intensive research interest,where many attentions have been paid to catalyst design and mechanism study.Electrode near-surface microenvironment matters fundamentally for reactant mass transfer,water molecule interference,catalyst exposure,and others,yet it has been rarely investigated.In the latest issue of Angew.Chem.Int.Ed.,Han,Kang and coauthors reported a method to regulate the microenvironment on the catalyst surface by adding polyethylene glycol,which remarkably improves the yield of multicarbon products.This strategy of controlling multiple proton-electron coupling processes through molecular chemistry-driven microenvironmental regulation is thought to inspire new idea for addressing the low efficiency challenge of CO_(2)RR.展开更多
Polyethylene terephthalate(PET)fibers are the largest category of chemical fibers and are widely used.However,the dyeing of PET fibers requires high temperature and pressure(130℃and 0.2 MPa),and the dyeing process co...Polyethylene terephthalate(PET)fibers are the largest category of chemical fibers and are widely used.However,the dyeing of PET fibers requires high temperature and pressure(130℃and 0.2 MPa),and the dyeing process consumes huge amounts of energy.Existing studies have shown that the dyeing ability of PET is directly related to the size of the amorphous region,which determines the external conditions for dyeing.In this research,we synthesized a series of low-temperature easydyeing masterbatches,PET-co-polyethylene glycol(PETEG),using polyethylene glycol(PEG)with different number-average molecular masses Mn and additive amounts.The phase domain size of the amorphous region of PET fibers was regulated via the masterbatch method.The relationship between the phase domain size and dyeing performance was explored from three perspectives:the amount of masterbatch,type of masterbatch,and PEG relative molecular mass.The results indicate that the fiber sample with PEG(Mn=2000 g/mol)at a mass fraction of 20%modified masterbatch has a smaller crystalline lamellar thickness(5.59 nm)and a larger interlamellar amorphous layer thickness(6.43 nm).The increase in the long period and lamellar inclination angle results in a looser structure,allowing small molecule dyes to diffuse into the fibers more easily.The dye-uptake increases from 63.21%to 92.66%at 100℃with the addition of the masterbatch.Additionally,the dye-uptake of the modified fibers increases with the relative molecular mass of PEG and the mass fraction of the masterbatch.All modified fibers achieve a staining color fastness of grade 4 or higher.This research demonstrates a simple masterbatch method that enables atmospheric pressure dyeing and provides a practical solution for efficient,low-temperature,and low-energy dyeing of PET fibers.展开更多
基金supported by the National Natural Science Foundation of China(No.U23B6011)the Jilin Provincial Science and Technology Department Program(No.20230101347JC)。
文摘Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving this kind of polymers,yet with linear microstructures.Ringopening metathesis polymerization(ROMP)offers another promising avenue for affording functionalized polyolefins.This method exhibits high polar group tolerance and the ability to precisely regulate polymer branches.In this study,we report the method for producing mechanochromic branched polyethylenes via ROMP.By employing the terpolymerization of a well-designed monomer containing the mechanochromic group,NB-ABF,with cyclooctene(COE)and long-chain 5-hexylcyclooctene(COE-C6),following by hydrogenation process,we synthesized a range of functionalized branched polyethylenes characterized by varied branching density and polar monomer incorporation.These polymers bear a structural resemblance to functionalized ethylene-octene copolymers.After crosslinking,mechanochromophores are generated,and mechanochromism is achieved in uniaxial tensile testing.A comprehensive assessment reveals that both the incorporation of polar monomers and variations in branching density significantly influence their mechanical properties.Notably,upon stretching,these materials display pronounced visible color change,confirming the successful development of mechanochromic branched polyethylenes.
文摘Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distributionwas also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four differentpolyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single sitecatalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with meltingtemperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethyleneand the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used tocalculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branchcontent were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branchcontent polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient wasnecessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling tobelow ambient because the calibration data were not performed in this way.
文摘Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and (M) over bar(w)/(M) over bar(n). This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.
基金This work was supported by the Science Foundation of Polymer Physics Laboratory, Chinese Academy of Sciences.
文摘The molecular structure of polyethylene (PE) samples with various comonomers including propylene, I-butane and 1-hexene was investigated by DSC and C-13-NMR techniques. The density of the samples varies from 0.948 g/cm(3) to 0.917 g/cm(3), and the molecular weight determined by the GPC method is in the range of 1 similar to2 x 10(5). The branch paint content of the samples was determined by C-13-NMR measurements and was found to be less than 20 per 1000 C atoms along the main chain. Crystallization segregation DSC technique (CSDSC) was used to characterize the branch point distribution or the segment length distribution of PEs. The crystallization segregation was performed in a successive annealing process at decreasing temperatures. The interval of two successive annealing temperatures was 6 K, and the time length of each annealing step was 2.5 h. The CSDSC results clearly indicate that all the PE samples used, including some metallocene PEs, more or less exhibit their non-uniformity in segment length distribution, and bimodal or multimodal CSDSC curves were usually observed. For quantitative characterization of the CSDSC curves and the segment length distribution two parameters, the average melting point, T-mAV, and the root-mean-square deviation of melting temperature, (DeltaT(m)(AV)(2))(1/2), were proposed. TmAV is corresponding to the average segment length due to branching and (DeltaT(m)(AV)(2))(1/2) gives information about the: width of the segment length distribution. Experimental results show that both the degree of average melting temperature depression and the width of the distribution seem to increase with increasing the branching content and are dependent on the type of comonomers. Very good reproducibility and additivity of the CSDSC method were evidenced experimentally. It was concluded that the CSDSC technique is a sensitive and convenient method for characterizing the segment length distribution of branched polyethylenes and will be of great interest in structure-property relationship studies of crystalline polymers.
基金the financial support from the National Natural Science Foundation of China(Nos.51803111,31670596 and 11904220)the Natural Science Foundation of Shaanxi province(Nos.2019JQ-786 and 2020GY-232).
文摘A series of hydroxyl-terminated polyethylenes(HTPE)bearing various functional side groups(e.g.carboxyl,ester and butane groups)were synthesized by the combination of ring opening metathesis polymerization(ROMP)and visible light photocatalytic thiol-ene reaction.The products are named as a,w-dihydroxyl-polyllpropionyloxythio)methinetrimethylene](HTPECarboxy),a,w dihydroxy-poly(methylpropionatethio)methinetrimethylene](HTPEeser)and a,wdihydroxyl-poly[(butylthio)methinetrimethylene](HTPEbutane)respectively.The investigation of ROMP indicated that the molecular weight of resultant hydroxy-terminated polybutadiene(HTPB)can be tailored by varying the feed ratios of monomer to chain transfer agent(CTA).The exploration of the photocatalytic thiol-ene reaction between HTPB precursor and methyl-3-mercaptopropionate revealed that blue light as well as oxygen accelerated the reaction.1H-NMR and 13C-NMR results verified all the double bonds in HTPB can be modified,and the main chain of resultant polymer can be considered as polyethylene.Subsequently,relationship between the structure of side groups and the thermal properties of functional PEs was studied.And the results suggested that the Tg was in the order of HTPEbuane<HTPEester<HTPEarboxy+.Greater interaction between side groups resulted in higher Tg.Moreover,all the functional PE samples exhibited poor thermostability as compared to HTPB.Finally,the promising applications for functional PEs were explored.HTPEcarboxy1 can be utilized as a smart material with pH-responsive properties due to its pH-dependent ionization of carboxyl side groups.HTPEbutane can be employed as a macro-initiator for building the triblock copolymer due to the presence of active hydroxyl end groups.HTPEester can serve as a plasticizer for PVC which can enhance the ductilityt of PVC without obviously sacrificing strength.
文摘Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.
基金supported by the National Natural Science Foundation of China (U1362204, 51473170, 21572085)
文摘The series of 2-（1-（2,4-dibenzhydrylnaphthylimino）ethyl）-6-（1-（arylimino）ethyl）pyridine derivatives and their cobalt chlorides （Col-Co5） were synthesized and fully characterized. The representative complexes Co2 and Co3 were confirmed by single crystal X-ray diffraction analyses, indicating pseudo-square-pyramidal geometry around the cobalt centre. All cobalt complexes, activated with either methylaluminoxane （MAO） or modified methylaluminoxane （MMAO）, exhibited high activities towards ethylene polymerization, and produced polyethylenes with high molecular weight and highly linear feature as well as unimodal distribution.
基金supported by the National Natural Science Foundation of China(grant nos.21890730,21890733,and 22231007)the Program for Basic Research of Shanghai Science and Technology Commission(grant no.19JC1410400)+2 种基金the Fundamental Research Funds for the Central Universities(grant no.23X010301599)the Shanghai Pujiang Program(grant no.21PJ1406500)the China Postdoctoral Science Foundation(grant no.2022M722073).
文摘Aiming at accessing polyethylene-bearing in-chain degradable functionality,copolymerization of carbon dioxide(CO_(2))with ethylene has long been recognized as a significant but highly challenging transformation.Nevertheless,most trials have resulted in ethylene homopolymerization because of the endothermic property and high energy barriers of CO_(2)insertion during polymer chain propagation.Here we report an unprecedented tandem reaction protocol for the synthesis of polyethylenes with in-chain carbonyls from CO_(2)and ethylene by the combination of photocatalytic CO_(2)reduction and palladium-catalyzed coordination/insertion polymerization.This protocol provides an easy way to adjust the carbonyl content(from 0.13 to 12 mol%)and insertion selectivity(up to 99%isolated carbonyls)of the polyethylene copolymers,which enables the polymers tomaintain the main properties of highdensity polyethylene and simultaneously endows them with good photodegradability.In addition,besides apolar polyethylene copolymers,polar-functionalized polyethylenes with in-chain isolated carbonyls can also be synthesized from CO_(2),ethylene and a polar monomer using the same protocol.We believe our present work sheds new light on the synthesis of degradable polyethylenes by employing CO_(2)as a green carbonyl source.
基金supported by the Department of Defense AFIRMⅢW81XWH-20-2-0029 grant subcontractLone Star Paralysis gift,UT POC19-1774-13 grant+1 种基金Neuraptive Therapeutics Inc.26-7724-56 grantNational Institutes of Health R01-NS128086(all to GDB)。
文摘Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves.We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor recovery.Furthermore,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles.In this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve.Young adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of PEG.Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site.The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively.At 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase.PEG-fusion repair reestablished axonal continuity.Compared to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal areas.Unexpectedly,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair.This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair,supporting the use of this novel repair methodology over currently available treatments.
文摘To enhance the hydrophilicity and antistatic properties of the polyethylene terephthalate(PET)fabric,the lawsone dye was employed in dyeing the PET fabric.It was dissolved in ethanol/deionized water mixture and deionized water separately,forming different lawsone dye solutions(LDSs).The study investigated how the compounds in the LDS improve the surface properties and color durability of the PET fabric,resulting in increased dye uptake.An infrared dyeing machine was utilized to expedite the reactions between the lawsone dye and the PET fabric.Additionally,the chemical composition of the dyed PET fabric was verified using techniques such as Fourier transform infrared(FTIR)spectroscopy,X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)and ultraviolet-visible(UV-Vis)spectrophotometry.The K/S value was measured to assess color durability.After dyeing,the PET fabric exhibited high hydrophilicity which improved the hygroscopicity of the PET fabric and thus the conductivity of the PET fabric surface increased,thereby providing an antistatic effect.
基金supported by the National Natural Science Foundation of China(No.52163001)the Guizhou Provincial Science and Technology Program Project Grant,China(Qiankehe Platform Talents-CXTD[2021]005,Qiankehe Platform Talents-GCC[2022]010-1,Qiankehe Fuqi[2023]001,Qiankehe Platform Talents-GCC[2023]035,and Qiankehe Platform Talents-CXTD[2023]003)+3 种基金the Guizhou Minzu University Research Platform Grant,China(No.GZMUGCZX[2021]01)the Central Guided Local Science and Technology Development Funds Project,China(Qiankehe Zhong Yindi[2023]035)the Green Chemistry and Resource Environment Innovation Team of Guizhou Higher Education Institutions,China(Guizhou Education and Technology[2022]No.13)the Doctor Startup Fund of Guizhou Minzu University,China(No.GZMUZK[2024]QD77).
文摘With the wide application of electromagnetic wave,a high performance electromagnetic shielding material is urgently needed to solve the harm caused by electromagnetic wave.Complete cross-linking strategy is adopted in this paper.Polyacrylamide(PAM)was synthesized by in-situ polymerization of acrylamide(AM)monomer.The obtained PAM was blended with polyethylene glycol(PEG)to prepare PAM/PEG hydrogels and form rigid support structures.Subsequently,the modified carbon nanotubes(S-CNTs)were incorpor-ated into sodium alginate(SA)and PAM/PEG.Finally,Na+was used to trigger SA self-assembly,which significantly improved the mechanical properties and electrical conductivity of the hydrogels,and prepared PAM/PEG/SA/S-CNTs-Na hydrogels with high tough-ness and strong electromagnetic interference(EMI)shielding efficiency(SE).The results showed that the compressive strength of PAM/PEG/SA/S-CNTs-Na hydrogel was 19.05 MPa,which was 7.69%higher than that of PAM/PEG hydrogel(17.69 MPa).More en-couraging,the average EMI SE of PAM/PEG/SA/S-CNTs-Na hydrogels at a thickness of only 3 mm and a CNTs content of 16.53wt%was 32.92 dB,which is 113.21%higher than that of PAM/PEG hydrogels(15.44 dB).
基金supported by grants from the Lone Star Paralysis Foundation,NIH R01NS081063Department of Defense award W81XWH-19-2-0054 to GDB+2 种基金supported by University of Wyoming Startup funds,Department of Defense grant W81XWH-17-1-0402the University of Wyoming Sensory Biology COBRE under National Institutes of Health(NIH)award number 5P20GM121310-02the National Institute of General Medical Sciences of the NIH under award number P20GM103432 to JSB。
文摘Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.
基金supported by DOD AFIRMⅢW81XWH-20-2-0029 subcontract,UT POC19-1774-13Neuraptive Therapeutics Inc.26-7724-56+1 种基金NIH R01-NS128086 grantsLone Star Paralysis gift(to GDB)。
文摘Successful polyethylene glycol fusion(PEG-fusion)of severed axons following peripheral nerve injuries for PEG-fused axons has been reported to:(1)rapidly restore electrophysiological continuity;(2)prevent distal Wallerian Degeneration and maintain their myelin sheaths;(3)promote primarily motor,voluntary behavioral recoveries as assessed by the Sciatic Functional Index;and,(4)rapidly produce correct and incorrect connections in many possible combinations that produce rapid and extensive recovery of functional peripheral nervous system/central nervous system connections and reflex(e.g.,toe twitch)or voluntary behaviors.The preceding companion paper describes sensory terminal field reo rganization following PEG-fusion repair of sciatic nerve transections or ablations;howeve r,sensory behavioral recovery has not been explicitly explored following PEG-fusion repair.In the current study,we confirmed the success of PEG-fusion surgeries according to criteria(1-3)above and more extensively investigated whether PEG-fusion enhanced mechanical nociceptive recovery following sciatic transection in male and female outbred Sprague-Dawley and inbred Lewis rats.Mechanical nociceptive responses were assessed by measuring withdrawal thresholds using von Frey filaments on the dorsal and midplantar regions of the hindpaws.Dorsal von Frey filament tests were a more reliable method than plantar von Frey filament tests to assess mechanical nociceptive sensitivity following sciatic nerve transections.Baseline withdrawal thresholds of the sciatic-mediated lateral dorsal region differed significantly across strain but not sex.Withdrawal thresholds did not change significantly from baseline in chronic Unoperated and Sham-operated rats.Following sciatic transection,all rats exhibited severe hyposensitivity to stimuli at the lateral dorsal region of the hindpaw ipsilateral to the injury.However,PEG-fused rats exhibited significantly earlier return to baseline withdrawal thresholds than Negative Control rats.Furthermore,PEG-fused rats with significantly improved Sciatic Functional Index scores at or after 4 weeks postoperatively exhibited yet-earlier von Frey filament recove ry compared with those without Sciatic Functional Index recovery,suggesting a correlation between successful PEG-fusion and both motor-dominant and sensory-dominant behavioral recoveries.This correlation was independent of the sex or strain of the rat.Furthermore,our data showed that the acceleration of von Frey filament sensory recovery to baseline was solely due to the PEG-fused sciatic nerve and not saphenous nerve collateral outgrowths.No chronic hypersensitivity developed in any rat up to 12 weeks.All these data suggest that PEG-fusion repair of transection peripheral nerve injuries co uld have important clinical benefits.
文摘With the aim to effectively depolymerize polyethylene terephthalate(PET)under mild reaction conditions,PET methanolysis and dimethyl terephthalate(DMT)hydrolysis are integrated in a catalyst system.Firstly,methanolysis of PET to DMT is achieved over Cu-Mg-Al oxide catalyst.Next,terephthalic acid(TPA)is prepared by DMT hydrolysis.It is found that hydrolysis of DMT to TPA can be promoted by introducing trace amount of water in this catalyst system.CuO-MgO-4.5Al_2O_(3)catalyst demonstrates the excellent catalytic performance for the depolymerization of PET with high conversion rate and TPA yield(100%and 99.5%,respectively)after reaction at 160℃for 6 h,which provides a new idea for the depolymerization of PET.
文摘In order to explore the mechanism of improving the surface wettability of low-energy polytetrafluoroethylene(PTFE)by new extended surfactants,five kinds of extended anionic surfactants with different numbers of oxypropylene(PO)and oxyethylene(EO),octadecyl-(PO)_(m)-(EO)_(n)-sodium carboxylate(C_(18)PO_(m)EO_(n)C,m=5,10,15,n=5,10,15),were studied.The surface tension and contact angle of C_(18)PO_(m)EO_(n)C solution with different concentrations were measured,and the adhesion tension,PTFE-water interfacial tension,and adhesion work were calculated.It was found that the extended surfactant molecules adsorb on the surface of the solution and the PTFE-liquid interface simultaneously when the concentration is lower than the critical micelle concentration(cmc),and there was a linear relationship between surface tension and adhesion tension.The adsorption amount of C_(18)PO_(m)EO_(n)C at the PTFE-water interface was significantly lower than that on the surface of the solution.As the concentration increases above cmc,semi-micelle aggregates on the surface of PTFE are formed by C_(18)PO_(m)EO_(n)C molecules through hydrophobic interaction,and the hydrophilic group faces the solution to modify the surface of PTFE with high efficiency.
基金supported by the National Natural Science Foundation of China(22308006,22278001)the Natural Science Foundation of Anhui Provincial Education Department(KJ2021A0407).
文摘This work proposed a strategy to improve the caking index of polyethylene terephthalate(PET)waste,in which low-temperature pyrolysis treatment(LTPT)was used to depolymerize PET waste.The mechanism of G modification was revealed combining thermogravimetric(TG)analysis,Fourier transform infrared spectroscopy,pyrolysis-gas chromatography with mass spectrometric detection,and solid-state 13C nuclear magnetic resonance spectroscopy.Furthermore,crucible coking experiments were also conducted using industrial coal mixture and treated PET with the optimum G(PET300)or raw PET to evaluate the applicability of PET waste in coal-blending coking.According to characterization results of coke reactivity(CR),coke strength after reaction(CSR)indices,TG-related curves,pore volumes,and Raman spectra of the resultant cokes,LTPT could greatly increase the G of PET,and the optimum temperature was 300℃.Specifically,compared with the coke obtained from the blend with PET,the CR of the coke produced from the blend with PET300 decreased by 4.9%,whereas the CSR of the increased by 7.4%,suggesting that LTPT could increase the proportion of PET used for coal-blending coking.The improvement in G is attributed to the changes in C-O/C=O ratio,aliphatic H and aromaticity caused by LTPT.
文摘A nanomicelle(denoted as TPGS/Ppa)was fabricated via the coassembly of the amphiphilic D-α-tocopheryl polyethylene glycol 1000 succinate(TPGS)and the hydrophobic photosensitizer pyropheophorbide a(Ppa)for photodynamic therapy(PDT).The obtained nanomicelle possessed a spherical structure with a diameter of(18.0±2.2)nm and a zeta potential of approximately -18 mV.Besides,the nanomicelle exhibited excellent photostability,biocompatibility,and phototoxicity,and could effectively reach the tumor region via the enhanced permeability and retention effect.Additionally,it could be found that the TPGS/Ppa nanomicelle exhibited higher phototoxicity against 4T1 murine mammary cancer cells than free Ppa.In the 4T1 tumor-bearing mouse model,the nanomicelle showed an excellent antitumor therapeutic effect.This study develops a new type of photodynamic nanomicelle TPGS/Ppa,which can increase the accumulation of drugs and prolong their tumor retention time,providing a feasible strategy for realizing the delivery of small-molecule hydrophobic drugs and tumor PDT.
文摘This paper presents findings of a study on solid wastes conversion into fuels through pyrolysis of plastic materials, presenting an alternative renewable approach for waste management. Investigations were conducted on conversion of polypropylene (PP), low-density polyethylene (LDPE) and high-density polyethylene (HDPE) under normal and catalyst mediated process conditions. Plastic wastes were collected from various dumpsites in Nairobi and segregated using plastic resin codes to various classes. Samples were cleaned, dried and shredded to 2 mm and fed into a pyrolysis reactor. The pyrolysis process was conducted at between 220˚C and 420˚C. Pyrolysis gases were condensed in a shell and coil condenser and the incondensable gases were stored in gasbags. Liquid fuels were analysed using Gas chromatograph with a mass spectroscopic detector and Fourier Transform Infrared Spectrometry. The results revealed that the most optimal process conditions were a temperature range of 220˚C - 420˚C at a heating rate of 10˚C per minute. Under these conditions, the oil yields were 53.72% for PP, 62.10% for LDPE, and 64.14% for HDPE. As the heating rate increased from 10˚C/min to 20˚C/min, gas yields increased, rising from 28.05% to 31.12% in PP, 14.96% to 30.62% in LDPE, and 18.51% to 29.49% in HDPE. The introduction of Fe2O3 and Al2O3 catalyst significantly enhanced gas production during pyrolysis, increasing yields from 18% to 61% and 47% respectively.
基金supported by the National Natural Science Foundation of China(22393961,U23A20132,22209007)the Beijing Natural Science Foundation(2232016)+1 种基金the Beijing Nova Program(20240484611)the Fundamental Research Funds for the Central Universities,China(buctrc202029,buctrc202129).
文摘Electrocatalytic CO_(2)reduction(CO_(2)RR)is spurring intensive research interest,where many attentions have been paid to catalyst design and mechanism study.Electrode near-surface microenvironment matters fundamentally for reactant mass transfer,water molecule interference,catalyst exposure,and others,yet it has been rarely investigated.In the latest issue of Angew.Chem.Int.Ed.,Han,Kang and coauthors reported a method to regulate the microenvironment on the catalyst surface by adding polyethylene glycol,which remarkably improves the yield of multicarbon products.This strategy of controlling multiple proton-electron coupling processes through molecular chemistry-driven microenvironmental regulation is thought to inspire new idea for addressing the low efficiency challenge of CO_(2)RR.
基金Key R&D Program of the Xinjiang Uygur Autonomous Region,China(No.2024B01011)。
文摘Polyethylene terephthalate(PET)fibers are the largest category of chemical fibers and are widely used.However,the dyeing of PET fibers requires high temperature and pressure(130℃and 0.2 MPa),and the dyeing process consumes huge amounts of energy.Existing studies have shown that the dyeing ability of PET is directly related to the size of the amorphous region,which determines the external conditions for dyeing.In this research,we synthesized a series of low-temperature easydyeing masterbatches,PET-co-polyethylene glycol(PETEG),using polyethylene glycol(PEG)with different number-average molecular masses Mn and additive amounts.The phase domain size of the amorphous region of PET fibers was regulated via the masterbatch method.The relationship between the phase domain size and dyeing performance was explored from three perspectives:the amount of masterbatch,type of masterbatch,and PEG relative molecular mass.The results indicate that the fiber sample with PEG(Mn=2000 g/mol)at a mass fraction of 20%modified masterbatch has a smaller crystalline lamellar thickness(5.59 nm)and a larger interlamellar amorphous layer thickness(6.43 nm).The increase in the long period and lamellar inclination angle results in a looser structure,allowing small molecule dyes to diffuse into the fibers more easily.The dye-uptake increases from 63.21%to 92.66%at 100℃with the addition of the masterbatch.Additionally,the dye-uptake of the modified fibers increases with the relative molecular mass of PEG and the mass fraction of the masterbatch.All modified fibers achieve a staining color fastness of grade 4 or higher.This research demonstrates a simple masterbatch method that enables atmospheric pressure dyeing and provides a practical solution for efficient,low-temperature,and low-energy dyeing of PET fibers.
