Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLD...Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLDPEs)with comparable molecular weights but different short-chain branch(SCB)contents(ranging of 5-66 per 1000 carbon atoms)were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145℃ and 50 r/min for 30 min.The influence of SCB content on the processability and structure of the resulting products was systematically investigated.All modified products exhibited good melt processability with melt flow rates(MFR)ranging from 0.46 g/10min to 1.07 g/10min.Products derived from low-SCB LLDPEs showed a lower MFR,higher cross-linking content,a larger number of long-chain branches,and a higher degree of benzoyl grafting.In contrast,those produced from high-SCB LLDPEs exhibited improved processability,reduced cross-linking,fewer long-chain branches,and lower benzoyl grafting levels.A detailed structural investigation of the soluble and insoluble fractions,which were separated using trichlorobenzene fractionation,was conducted to analyze the structural features of various modified products and demonstrate that the SCB content(i.e.,tertiary carbon density)significantly influences radical coupling during dynamic modification.Elevated tertiary carbon density,by introducing greater steric hindrance,suppresses radical coupling during dynamic modification,thereby reducing the efficiency of both crosslinking and peroxide fragment grafting.These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.展开更多
Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic ...Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic deformation in seawater.In this study,we performed a comparative analysis of the UHMWPE dynamics under seawater and water conditions to investigate the plastic deformation of UHMWPE induced by seawater.The results show that the plastic deformation of UHMWPE is amplified in seawater relative to the water conditions.Under thin fluid conditions,frictional interfaces exhibit a higher interfacial friction force and interaction energy in seawater than in water.Compared to freely diffused water molecules,hydrated ions occupy larger interchain spaces within polyethylene.Furthermore,the diffusion of hydrated ions weakens the interchain interactions,promoting more severe polyethylene chain rearrangement and accelerating seawater-induced plastic deformation in UHMWPE during friction.Furthermore,the diffused seawater accelerated the disentangling of the polyethylene chains and enhanced the orderly orientation distribution of polyethylene.Compared to free water molecules,the water molecules of hydrated ions exhibit enhanced attraction to free-flowing water molecules,thereby accelerating seawater flow across submerged UHMWPE surfaces.This flow enhancement promotes surface polyethylene chain mobility in seawater.展开更多
Conventional polyethylene(PE)fibers face limitations in large-scale industrial applications due to their poor thermal stability and inherent hydrophobicity,which restrict processing temperatures and dyeability,especia...Conventional polyethylene(PE)fibers face limitations in large-scale industrial applications due to their poor thermal stability and inherent hydrophobicity,which restrict processing temperatures and dyeability,especially in blended fabric production.In this research,a one-step ultraviolet(UV)irradiation technology was employed to modify medium molecular weight PE fibers through simultaneous crosslinking and grafting modifications,aiming to enhance their thermal stability and hydrophilicity.The modification employed a cost-effective,UV-initiated crosslinking system consisting of benzophenone(BP)as the photoinitiator and triallyl isocyanurate(TAIC)as the cocrosslinker.Acrylic acid(AA)was selected as the grafting monomer.These modifiers were thoroughly mixed with the PE matrix in a liquid-phase environment,and the mixture was melt-spun into fibers.The resulting fibers were then subjected to UV irradiation,which triggered the crosslinking and grafting reactions.The effects of the mass fraction of each component and irradiation parameters on modification efficacy were systematically investigated,followed by a comprehensive characterization of the modified PE fibers.The modified PE fibers achieved optimal thermal stability under the following conditions:2.0%mass fractions for both BP and TAIC,a UV irradiation intensity of 2000 mW/cm^(2),and an equivalent irradiation time of 60 s.This synergistic modification approach enables the fibers to maintain superior morphological integrity and mechanical performance when exposed to elevated temperatures ranging from 130 to 150℃.Meanwhile,an AA grafting mass fraction of 2.0%maximizes hydrophilicity with minimal impact on other properties,as evidenced by a dramatic reduction in the water contact angle(WCA)from 105.0°(hydrophobic)to 48.4°(hydrophilic).These improvements confirm the effectiveness of the modification strategy in synergistically enhancing both thermal stability and hydrophilicity of PE fibers.展开更多
UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechani...UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.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
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
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
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
Most plastics are released into the environment once they are discarded,resulting in microplastics(<5 mm)being found in every part of the world.To better understand their toxicity,we exposed four generations of the...Most plastics are released into the environment once they are discarded,resulting in microplastics(<5 mm)being found in every part of the world.To better understand their toxicity,we exposed four generations of the fruit fly,Drosophila melanogaster,to high-density polyethylene(HDPE)microplastics(<38μm)and monitored their reproductive performance.We found that the eclosion fraction of pupae was 5.7%higher(p<0.05)in the stream of flies that were fed 100 mg/kg HDPE across all generations when compared to those fed control food.Several fourth-generation treatment flies expressed malformed salivary glands and scutella.No toxicity was observed in the number of pupae and flies that emerged from the eggs laid in each generation or their mean pupation and eclosion time.Moreover,no toxicity was observed in the development of larvae into adult flies(0.1−10000 mg/kg HDPE)and various sublethal end points(100 mg/kg HDPE)such as larva and adult fly locomotion and the mass of female and male flies.These results,obtained with realistic weathered microplastics,indicate that HDPE microplastics at the concentrations evaluated are unlikely to be lethal in Drosophila melanogaster;however malformations are still possible despite little-to-no observable internalization of the microplastics.展开更多
BACKGROUND Excipients may improve the palatability of polyethylene glycol(PEG),the firstline treatment for childhood functional constipation(FC),leading to good compliance and improved treatment outcomes.AIM To compar...BACKGROUND Excipients may improve the palatability of polyethylene glycol(PEG),the firstline treatment for childhood functional constipation(FC),leading to good compliance and improved treatment outcomes.AIM To compare the developed PEG-based formula(PEG-Chula)to the commercial formula for treating childhood FC.METHODS In this randomized controlled trial,we enrolled children aged<18 years with FC diagnosed by the Rome Ⅳ criteria to receive PEG-Chula[four flavors:(1)Strawberry;(2)Lychee;(3)Apple;and(4)Lychee-rose]or Forlax(orange-grapefruit flavor)for eight weeks.The primary outcomes included changes in stool frequency and consistency measured by the Bristol Stool scale.The secondary outcomes were constipation-related symptom improvement,adverse events,and palatability measured by the facial hedonic scale.RESULTS Fifty-two children diagnosed with FC[median age:4.21(2.33,7.88)years;35(67.31%)females]were enrolled.After the 8-week treatment,the mean weekly stool frequency increased in both groups,the mean change was 4.02(95%CI:3.09-4.95)in PEG-Chula and 3.78(95%CI:2.79-4.78)in commercial PEG compared to baseline(P<0.001).The extent of stool consistency improvement did not differ significantly.The most preferred PEG-Chula flavor was rated more palatable than the commercial PEG.Treatment compliance correlated with medication palatability(r=0.34,P=0.013).No significant differences in adverse events were found.CONCLUSION Both PEG-based formulas are effective and safe for managing pediatric FC.展开更多
Cross-linking byproducts in the cross-linked polyethylene(XLPE)cable insulation material significantly affect the insulation properties of XLPE,and the non-destructive detection method for cross-linking byproducts dur...Cross-linking byproducts in the cross-linked polyethylene(XLPE)cable insulation material significantly affect the insulation properties of XLPE,and the non-destructive detection method for cross-linking byproducts during cable degassing process still faces great challenges.This work develops an extra-low frequency(ELF)dielectric analysis method based on time-dependent polarisation current for non-destructive detection of byproducts in XLPE.The effects of single byproduct of acetophenone and cumyl alcohol on the ELF dielectric properties of XLPE are studied separately.The ELF associated static permittivity and the dielectric loss of XLPE rise as the content of the single byproduct increases,and theαrelaxation(10−4-10−3 Hz)andβrelaxation(10−3-10−2 Hz)of XLPE are observed.Ionisation of acetophenone occurs above electric field strength of 20 kV,whereas ionisation tends to saturate above 50 kV.The optimal field strength for ELF dielectric testing of XLPE is determined to be 20-50 kV.Furthermore,the degassing factor is proposed to accurately determine the removal of byproducts.Based on these,the non-destructive detection of degassing of XLPE cable is achieved.The proposed ELF dielectric analysis method enables the non-destructive detection of byproducts in cables,opening a new avenue for cable degassing effect evaluation.展开更多
Incorporating a low density of ester units into the backbone of polyethylene materials enhances their sustainability and recyclability while maintaining the main material properties of polyethylenes.Here we report a n...Incorporating a low density of ester units into the backbone of polyethylene materials enhances their sustainability and recyclability while maintaining the main material properties of polyethylenes.Here we report a new way to access degradable polyethylene materials with a low content of in-chain ester units via mechanochemical backbone editing.Initially,ester groups are incorporated as side groups through catalytic copolymerization of ethylene with a cyclobutene-fused lactone monomer(CBL),yielding polyethylene materials with high molecular weights and adjustable thermomechanical properties.Subsequent solid-state ball-milling treatment selectively introduces side-chain ester groups into the main chain of the polyethylene materials via force-induced cycloreversion of the cyclobutane units.Under acidic conditions,hydrolysis of the resultant polyethylene materials with in-chain ester units facilitates further degradation into oligomers.展开更多
In rotationally extruded fittings,high-density polyethylene(HDPE)pipes prepared using conventional processing methods often suffer from poor pressure resistance and low toughness.This study introduces an innovative ro...In rotationally extruded fittings,high-density polyethylene(HDPE)pipes prepared using conventional processing methods often suffer from poor pressure resistance and low toughness.This study introduces an innovative rotary shear system(RSS)to address these deficiencies through controlled mandrel rotation and cooling rates.We successfully prepared self-reinforced HDPE pipes with a three-layer structure combining spherical and shish-kebab crystals.Rotational processing aligned the molecular chains in the ring direction and formed shish-kebab crystals.As a result,the annular tensile strength of the rotationally processed three-layer shish-kebab structure(TSK)pipe increased from 26.7 MPa to 76.3 MPa,an enhancement of 185.8%.Notably,while maintaining excellent tensile strength(73.4 MPa),the elongation at break of the spherulite shishkebab spherulite(SKS)tubes was improved to 50.1%,as compared to 33.8%in the case of shish-kebab spherulite shish-kebab(KSK)tubes.This improvement can be attributed to the changes in the micro-morphology and polymer structure within the SKS tubes,specifically due to the formation of small-sized shish-kebab crystals and the low degrees of interlocking.In addition,2D-SAXS analysis revealed that KSK tubes have higher tensile strength due to smaller crystal sizes and larger shish dimensions,forming dense interlocking structures.In contrast,the SKS and TSK tubes had thicker amorphous regions and smaller shish sizes,resulting in reduced interlocking and mechanical performance.展开更多
It has been widely recognized that the mixing process has significant impacts on the performance of low-density polyethylene(LDPE)reactors due to the rapid radical polymerization occurred in the reactors,but how the m...It has been widely recognized that the mixing process has significant impacts on the performance of low-density polyethylene(LDPE)reactors due to the rapid radical polymerization occurred in the reactors,but how the macro-and micro-mixing affect the reactor performance was still controversial in publications.In this work,a cold-flow LDPE autoclave with multi-feedings was scaled down(1/2)from an industrial reactor and built to systematically investigate the macro-and micro-mixing characteristics of fluid by experiments.Furthermore,the effects of macro-and micro-mixing on the polymerization were comprehensively analyzed.The results showed that according to the delay time t_(d) and macro-mixing times tM calculated from residence time distribution(RTD)curves,the macro-mixing states are significantly different at various axial positions(h/H),especially at lower agitation Reynolds number Re.But with the increase of Re,since the circulation flow in the reactor is strengthened,the t_(d) for each feed gradually decreases to 0,and the t_(M) at different axial positions tend to be identical.For micro-mixing,the qualities of micro-mixing at different axial positions are similar,and the average micro-mixing time t_(m) in the reactor decreases exponentially with the increase of Re.Moreover,a fitting model was established.Through the comparison of the characteristic times of macro-mixing(t_(d),t_(M)),micro-mixing(t_(m))and elementary reactions within the industrial range of Re,it can be concluded that the properties of LDPE products are dominated by the macro-mixing behavior,and the consumption of initiators is affected by both the macro-and micro-mixing behaviors.This conclusion is of great significance for the design,optimization and operation of LDPE reactors.展开更多
BACKGROUND In the field of clinical intestinal preparation,compound polyethylene glycol electrolyte solution(SF-PEG)is a commonly used intestinal cleaner.However,practice has shown that using only a single polyethylen...BACKGROUND In the field of clinical intestinal preparation,compound polyethylene glycol electrolyte solution(SF-PEG)is a commonly used intestinal cleaner.However,practice has shown that using only a single polyethylene glycol formulation often fails to achieve the desired intestinal preparation effect.Linalotide has a unique mechanism of action,which can effectively enhance the secretion of small intestinal fluid and promote intestinal peristalsis.The combination of linaclotide and SF-PEG may provide a better solution for intestinal preparation and improve the quality of intestinal cleaning.Therefore,exploring the application value and clinical efficacy of linaclotide capsules combined with SF-PEG in intestinal preparation is of great clinical significance.AIM To explore the effects of the combination of linaclotide capsules and SF-PEG,including its efficacy in intestinal preparation and patient tolerance.METHODS To investigate the differences in the effectiveness of different bowel preparation plans in colonoscopy,this article conducted a comprehensive and detailed retrospective analysis of the medical records of patients who underwent colonoscopy from January 2023 to December 2023.In this study,116 patients were accurately divided into three groups based on the different intestinal preparation drugs used before colonoscopy.Among them,group A consisted of 29 patients who underwent intestinal preparation using 3 liters of SF-PEG combined with linaclotide;group B consists of 50 patients who underwent intestinal preparation using 3 liters of SF-PEG;group C consisted of 37 patients who underwent intestinal preparation using a combination of 2-liter SF-PEC and linaclotide.Subsequently,this article evaluated the quality of intestinal preparation in these three groups of patients,using the Boston bowel preparation scale(BBPS)as a quantitative indicator,while comparing multiple indicators such as intestinal preparation completion rate and detection of positive lesions,providing a strong basis for optimizing clinical intestinal preparation plans.RESULTS No statistically significant differences were found in BBPS scores(7.75±1.23,7.69±1.14,and 7.66±1.31;P=0.240),bowel preparation completion rates(96.55%,90.00%,and 97.30%;P=0.293),adenoma detection rates(20.69%,38.00%,and 32.43%;P=0.281),polyp detection rates(34.48%,50.00%,37.84%;P=0.326),insertion time(6.03±4.34,6.12±3.60,and 5.33±2.42;P=0.584),and patient satisfaction rates(89.66%,84.00%,and 97.30%;P=0.398)among the three groups.However,statistically significant differences were observed in withdrawal time(7.45±2.91,9.02±3.54,and 6.86±2.66;P=0.027)and adverse reaction rates(6.90%,20.00%,and 2.70%;P=0.029)among the three groups.Multiple comparisons showed that group C had significantly lower withdrawal time and adverse reaction rates than group B(P=0.013,P=0.016).CONCLUSION Linaclotide capsules show a trend in improving bowel preparation quality and reducing the dosage of SF-PEG.展开更多
Single-step ethylene polymerization over a binary catalyst,including zirconocene precatalysts of various designs,has been studied to obtain polymer compositions based on ultrahigh-molecular-weight polyethylene(UHMWPE)...Single-step ethylene polymerization over a binary catalyst,including zirconocene precatalysts of various designs,has been studied to obtain polymer compositions based on ultrahigh-molecular-weight polyethylene(UHMWPE)and low-molecular-weight HDPE(LMWPE)directly in synthesis.Zirconocenes rac-(CH_(3))_(2)Silnd_(2)ZrCl_(2)(Zr-1)and rac-(C_(6)H_(10))CplndZrCl_(2)(Zr-2)activated with methylaluminoxane(MAO)were used as the components of the binary catalyst.It has been shown that the use of Zr-1/MAO and Zr-2/MAO in ethylene polymerization at 30℃leads to the production of UHMWPE with Mw=1000 kg-mol^(-1)and LMWPE with Mw=18 kg·mol^(-1),respectively.Reactor polymer compositions(RPC)with LMWPE fraction contents ranging from 9 wt%to 42 wt%were obtained when a molar fraction of Zr-2 in the binary catalyst(Zr-1+Zr-2)/MAO va ried in the range from 0.3 to 0.85.A study of the molecular weight characteristics of RPC showed that it has a wide bimodal molecular weight distribution(MWD)and includes UHMWPE(Mw=1000 kg·mol^(-1))and LMWPE(Mw=18 kg·mol^(-1))fractions.The degree of crystallinity of the polymer products was determined using the DSC method.The tensile properties and melt indices of the materials were studied depending on the LMWPE fraction content in the polymer composition.UHMWPE/LMWPE compositions with high tensile properties and fluidity at a load of 5 kg were obtained.展开更多
Flexible polymer-based foam sensors have significant potential for application in wearable electronics and motion monitoring.However,these prospects are hindered by the complex and unenvironmentally friendly manufactu...Flexible polymer-based foam sensors have significant potential for application in wearable electronics and motion monitoring.However,these prospects are hindered by the complex and unenvironmentally friendly manufacturing processes.In this study,we employed melt blending and supercritical carbon dioxide foaming to fabricate an ethylene-vinyl acetate copolymer(EVA)/low-density polyethylene(LDPE)/carbon nanotube(CNT)piezoresistive foam sensor.The cross-linking agent bis(tert-butyldioxyisopropyl)benzene and the conductive filler CNT were incorporated into the EVA/LDPE composite,successfully achieving a chemically cross-linked and physically entangled composite structure that significantly enhanced the storage modulus and complex viscosity.Additionally,the compressive strength of EVA/LDPE/CNT foam with 10 parts per hundred rubber(phr)CNT reached 1.37 MPa at 50%compression,marking a 340%increase compared to the 0.31 MPa of the CNT-free sample.Furthermore,the EVA/LDPE/CNT composite foams,which incorporated 10 phr CNT,were prepared under specific foaming conditions,resulting in an ultra-low density of 0.11 g/cm^(3) and a higher sensitivity,with a gauge factor of–2.3.The piezoresistive foam sensors developed in this work could accurately detect human motion,thereby expanding their applications in the field of piezoresistive foam sensors and providing an effective strategy for the advancement of high-performance piezoresistive foam sensors.展开更多
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
基金financially supported by the Science and Technology Project of PetroChina Company Limited,China(No.2022DJ6314)the National Natural Science Foundation of China(No.52173056)。
文摘Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLDPEs)with comparable molecular weights but different short-chain branch(SCB)contents(ranging of 5-66 per 1000 carbon atoms)were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145℃ and 50 r/min for 30 min.The influence of SCB content on the processability and structure of the resulting products was systematically investigated.All modified products exhibited good melt processability with melt flow rates(MFR)ranging from 0.46 g/10min to 1.07 g/10min.Products derived from low-SCB LLDPEs showed a lower MFR,higher cross-linking content,a larger number of long-chain branches,and a higher degree of benzoyl grafting.In contrast,those produced from high-SCB LLDPEs exhibited improved processability,reduced cross-linking,fewer long-chain branches,and lower benzoyl grafting levels.A detailed structural investigation of the soluble and insoluble fractions,which were separated using trichlorobenzene fractionation,was conducted to analyze the structural features of various modified products and demonstrate that the SCB content(i.e.,tertiary carbon density)significantly influences radical coupling during dynamic modification.Elevated tertiary carbon density,by introducing greater steric hindrance,suppresses radical coupling during dynamic modification,thereby reducing the efficiency of both crosslinking and peroxide fragment grafting.These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.
基金financially supported by the National Natural Science Foundation of China(Nos.51909023 and 51775077)the Natural Science Foundation of Liaoning Province(No.2021-MS-140)the Fundamental Research Funds for the Central Universities(No.3132025114)。
文摘Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic deformation in seawater.In this study,we performed a comparative analysis of the UHMWPE dynamics under seawater and water conditions to investigate the plastic deformation of UHMWPE induced by seawater.The results show that the plastic deformation of UHMWPE is amplified in seawater relative to the water conditions.Under thin fluid conditions,frictional interfaces exhibit a higher interfacial friction force and interaction energy in seawater than in water.Compared to freely diffused water molecules,hydrated ions occupy larger interchain spaces within polyethylene.Furthermore,the diffusion of hydrated ions weakens the interchain interactions,promoting more severe polyethylene chain rearrangement and accelerating seawater-induced plastic deformation in UHMWPE during friction.Furthermore,the diffused seawater accelerated the disentangling of the polyethylene chains and enhanced the orderly orientation distribution of polyethylene.Compared to free water molecules,the water molecules of hydrated ions exhibit enhanced attraction to free-flowing water molecules,thereby accelerating seawater flow across submerged UHMWPE surfaces.This flow enhancement promotes surface polyethylene chain mobility in seawater.
文摘Conventional polyethylene(PE)fibers face limitations in large-scale industrial applications due to their poor thermal stability and inherent hydrophobicity,which restrict processing temperatures and dyeability,especially in blended fabric production.In this research,a one-step ultraviolet(UV)irradiation technology was employed to modify medium molecular weight PE fibers through simultaneous crosslinking and grafting modifications,aiming to enhance their thermal stability and hydrophilicity.The modification employed a cost-effective,UV-initiated crosslinking system consisting of benzophenone(BP)as the photoinitiator and triallyl isocyanurate(TAIC)as the cocrosslinker.Acrylic acid(AA)was selected as the grafting monomer.These modifiers were thoroughly mixed with the PE matrix in a liquid-phase environment,and the mixture was melt-spun into fibers.The resulting fibers were then subjected to UV irradiation,which triggered the crosslinking and grafting reactions.The effects of the mass fraction of each component and irradiation parameters on modification efficacy were systematically investigated,followed by a comprehensive characterization of the modified PE fibers.The modified PE fibers achieved optimal thermal stability under the following conditions:2.0%mass fractions for both BP and TAIC,a UV irradiation intensity of 2000 mW/cm^(2),and an equivalent irradiation time of 60 s.This synergistic modification approach enables the fibers to maintain superior morphological integrity and mechanical performance when exposed to elevated temperatures ranging from 130 to 150℃.Meanwhile,an AA grafting mass fraction of 2.0%maximizes hydrophilicity with minimal impact on other properties,as evidenced by a dramatic reduction in the water contact angle(WCA)from 105.0°(hydrophobic)to 48.4°(hydrophilic).These improvements confirm the effectiveness of the modification strategy in synergistically enhancing both thermal stability and hydrophilicity of PE fibers.
基金financially supported by the National Natural Science Foundation of China(Nos.52303298 and 52233002)。
文摘UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.
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.
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 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.
基金support from the Natural Sciences and Engineering Research Council of Canada(NSERC)for the Discovery,Strategic,and PURE CREATE programs,the Canada Research Chairs Program,the Killam Research Fellowship,the Canada Foundation for Innovation,the FRQNT.S.Chahal acknowledges NSERC for a PGS D scholarship,McGill University for a MEDA fellowship,the support of the EUL fund in the Department of Chemical EngineeringEcotoQ.J.-R.M acknowledges NSERC and FRQNT for a Postdoctoral Fellowship.
文摘Most plastics are released into the environment once they are discarded,resulting in microplastics(<5 mm)being found in every part of the world.To better understand their toxicity,we exposed four generations of the fruit fly,Drosophila melanogaster,to high-density polyethylene(HDPE)microplastics(<38μm)and monitored their reproductive performance.We found that the eclosion fraction of pupae was 5.7%higher(p<0.05)in the stream of flies that were fed 100 mg/kg HDPE across all generations when compared to those fed control food.Several fourth-generation treatment flies expressed malformed salivary glands and scutella.No toxicity was observed in the number of pupae and flies that emerged from the eggs laid in each generation or their mean pupation and eclosion time.Moreover,no toxicity was observed in the development of larvae into adult flies(0.1−10000 mg/kg HDPE)and various sublethal end points(100 mg/kg HDPE)such as larva and adult fly locomotion and the mass of female and male flies.These results,obtained with realistic weathered microplastics,indicate that HDPE microplastics at the concentrations evaluated are unlikely to be lethal in Drosophila melanogaster;however malformations are still possible despite little-to-no observable internalization of the microplastics.
基金Supported by the 90th Anniversary of Chulalongkorn University Fund(Ratchadapiseksomphot Endowment Fund)Ratchadapiseksompotch Funds,Graduate Affairs,Faculty of Medicine,Chulalongkorn University,Bangkok,Thailand,No.GA68/028.
文摘BACKGROUND Excipients may improve the palatability of polyethylene glycol(PEG),the firstline treatment for childhood functional constipation(FC),leading to good compliance and improved treatment outcomes.AIM To compare the developed PEG-based formula(PEG-Chula)to the commercial formula for treating childhood FC.METHODS In this randomized controlled trial,we enrolled children aged<18 years with FC diagnosed by the Rome Ⅳ criteria to receive PEG-Chula[four flavors:(1)Strawberry;(2)Lychee;(3)Apple;and(4)Lychee-rose]or Forlax(orange-grapefruit flavor)for eight weeks.The primary outcomes included changes in stool frequency and consistency measured by the Bristol Stool scale.The secondary outcomes were constipation-related symptom improvement,adverse events,and palatability measured by the facial hedonic scale.RESULTS Fifty-two children diagnosed with FC[median age:4.21(2.33,7.88)years;35(67.31%)females]were enrolled.After the 8-week treatment,the mean weekly stool frequency increased in both groups,the mean change was 4.02(95%CI:3.09-4.95)in PEG-Chula and 3.78(95%CI:2.79-4.78)in commercial PEG compared to baseline(P<0.001).The extent of stool consistency improvement did not differ significantly.The most preferred PEG-Chula flavor was rated more palatable than the commercial PEG.Treatment compliance correlated with medication palatability(r=0.34,P=0.013).No significant differences in adverse events were found.CONCLUSION Both PEG-based formulas are effective and safe for managing pediatric FC.
基金supported by Project of Science and Technology of State Grid Corporation of China(Grant 5500-202458116A-1-1-ZN).
文摘Cross-linking byproducts in the cross-linked polyethylene(XLPE)cable insulation material significantly affect the insulation properties of XLPE,and the non-destructive detection method for cross-linking byproducts during cable degassing process still faces great challenges.This work develops an extra-low frequency(ELF)dielectric analysis method based on time-dependent polarisation current for non-destructive detection of byproducts in XLPE.The effects of single byproduct of acetophenone and cumyl alcohol on the ELF dielectric properties of XLPE are studied separately.The ELF associated static permittivity and the dielectric loss of XLPE rise as the content of the single byproduct increases,and theαrelaxation(10−4-10−3 Hz)andβrelaxation(10−3-10−2 Hz)of XLPE are observed.Ionisation of acetophenone occurs above electric field strength of 20 kV,whereas ionisation tends to saturate above 50 kV.The optimal field strength for ELF dielectric testing of XLPE is determined to be 20-50 kV.Furthermore,the degassing factor is proposed to accurately determine the removal of byproducts.Based on these,the non-destructive detection of degassing of XLPE cable is achieved.The proposed ELF dielectric analysis method enables the non-destructive detection of byproducts in cables,opening a new avenue for cable degassing effect evaluation.
基金financially supported by the National Natural Science Foundation of China(No.52473097)the Fundamental Research Funds for the Central Universities(No.24X010301678)Shanghai Jiao Tong University 2030 Initiative(No.WH510363002/002)。
文摘Incorporating a low density of ester units into the backbone of polyethylene materials enhances their sustainability and recyclability while maintaining the main material properties of polyethylenes.Here we report a new way to access degradable polyethylene materials with a low content of in-chain ester units via mechanochemical backbone editing.Initially,ester groups are incorporated as side groups through catalytic copolymerization of ethylene with a cyclobutene-fused lactone monomer(CBL),yielding polyethylene materials with high molecular weights and adjustable thermomechanical properties.Subsequent solid-state ball-milling treatment selectively introduces side-chain ester groups into the main chain of the polyethylene materials via force-induced cycloreversion of the cyclobutane units.Under acidic conditions,hydrolysis of the resultant polyethylene materials with in-chain ester units facilitates further degradation into oligomers.
基金supported by the National Natural Science Foundation of China(Nos.52373045 and 52033005).
文摘In rotationally extruded fittings,high-density polyethylene(HDPE)pipes prepared using conventional processing methods often suffer from poor pressure resistance and low toughness.This study introduces an innovative rotary shear system(RSS)to address these deficiencies through controlled mandrel rotation and cooling rates.We successfully prepared self-reinforced HDPE pipes with a three-layer structure combining spherical and shish-kebab crystals.Rotational processing aligned the molecular chains in the ring direction and formed shish-kebab crystals.As a result,the annular tensile strength of the rotationally processed three-layer shish-kebab structure(TSK)pipe increased from 26.7 MPa to 76.3 MPa,an enhancement of 185.8%.Notably,while maintaining excellent tensile strength(73.4 MPa),the elongation at break of the spherulite shishkebab spherulite(SKS)tubes was improved to 50.1%,as compared to 33.8%in the case of shish-kebab spherulite shish-kebab(KSK)tubes.This improvement can be attributed to the changes in the micro-morphology and polymer structure within the SKS tubes,specifically due to the formation of small-sized shish-kebab crystals and the low degrees of interlocking.In addition,2D-SAXS analysis revealed that KSK tubes have higher tensile strength due to smaller crystal sizes and larger shish dimensions,forming dense interlocking structures.In contrast,the SKS and TSK tubes had thicker amorphous regions and smaller shish sizes,resulting in reduced interlocking and mechanical performance.
基金the support and encouragement of the Key Projects of the Ministry of Industry and Information Technology of China(TC220A04W-3,188)。
文摘It has been widely recognized that the mixing process has significant impacts on the performance of low-density polyethylene(LDPE)reactors due to the rapid radical polymerization occurred in the reactors,but how the macro-and micro-mixing affect the reactor performance was still controversial in publications.In this work,a cold-flow LDPE autoclave with multi-feedings was scaled down(1/2)from an industrial reactor and built to systematically investigate the macro-and micro-mixing characteristics of fluid by experiments.Furthermore,the effects of macro-and micro-mixing on the polymerization were comprehensively analyzed.The results showed that according to the delay time t_(d) and macro-mixing times tM calculated from residence time distribution(RTD)curves,the macro-mixing states are significantly different at various axial positions(h/H),especially at lower agitation Reynolds number Re.But with the increase of Re,since the circulation flow in the reactor is strengthened,the t_(d) for each feed gradually decreases to 0,and the t_(M) at different axial positions tend to be identical.For micro-mixing,the qualities of micro-mixing at different axial positions are similar,and the average micro-mixing time t_(m) in the reactor decreases exponentially with the increase of Re.Moreover,a fitting model was established.Through the comparison of the characteristic times of macro-mixing(t_(d),t_(M)),micro-mixing(t_(m))and elementary reactions within the industrial range of Re,it can be concluded that the properties of LDPE products are dominated by the macro-mixing behavior,and the consumption of initiators is affected by both the macro-and micro-mixing behaviors.This conclusion is of great significance for the design,optimization and operation of LDPE reactors.
基金Supported by the Science and Technology Program of Rui’an,No.MS2023030.
文摘BACKGROUND In the field of clinical intestinal preparation,compound polyethylene glycol electrolyte solution(SF-PEG)is a commonly used intestinal cleaner.However,practice has shown that using only a single polyethylene glycol formulation often fails to achieve the desired intestinal preparation effect.Linalotide has a unique mechanism of action,which can effectively enhance the secretion of small intestinal fluid and promote intestinal peristalsis.The combination of linaclotide and SF-PEG may provide a better solution for intestinal preparation and improve the quality of intestinal cleaning.Therefore,exploring the application value and clinical efficacy of linaclotide capsules combined with SF-PEG in intestinal preparation is of great clinical significance.AIM To explore the effects of the combination of linaclotide capsules and SF-PEG,including its efficacy in intestinal preparation and patient tolerance.METHODS To investigate the differences in the effectiveness of different bowel preparation plans in colonoscopy,this article conducted a comprehensive and detailed retrospective analysis of the medical records of patients who underwent colonoscopy from January 2023 to December 2023.In this study,116 patients were accurately divided into three groups based on the different intestinal preparation drugs used before colonoscopy.Among them,group A consisted of 29 patients who underwent intestinal preparation using 3 liters of SF-PEG combined with linaclotide;group B consists of 50 patients who underwent intestinal preparation using 3 liters of SF-PEG;group C consisted of 37 patients who underwent intestinal preparation using a combination of 2-liter SF-PEC and linaclotide.Subsequently,this article evaluated the quality of intestinal preparation in these three groups of patients,using the Boston bowel preparation scale(BBPS)as a quantitative indicator,while comparing multiple indicators such as intestinal preparation completion rate and detection of positive lesions,providing a strong basis for optimizing clinical intestinal preparation plans.RESULTS No statistically significant differences were found in BBPS scores(7.75±1.23,7.69±1.14,and 7.66±1.31;P=0.240),bowel preparation completion rates(96.55%,90.00%,and 97.30%;P=0.293),adenoma detection rates(20.69%,38.00%,and 32.43%;P=0.281),polyp detection rates(34.48%,50.00%,37.84%;P=0.326),insertion time(6.03±4.34,6.12±3.60,and 5.33±2.42;P=0.584),and patient satisfaction rates(89.66%,84.00%,and 97.30%;P=0.398)among the three groups.However,statistically significant differences were observed in withdrawal time(7.45±2.91,9.02±3.54,and 6.86±2.66;P=0.027)and adverse reaction rates(6.90%,20.00%,and 2.70%;P=0.029)among the three groups.Multiple comparisons showed that group C had significantly lower withdrawal time and adverse reaction rates than group B(P=0.013,P=0.016).CONCLUSION Linaclotide capsules show a trend in improving bowel preparation quality and reducing the dosage of SF-PEG.
基金financially supported by the Fundamental Research Program of the Russian Academy of Sciences for the Semenov Research Center of Chemical Physics,Russian Academy of Sciences。
文摘Single-step ethylene polymerization over a binary catalyst,including zirconocene precatalysts of various designs,has been studied to obtain polymer compositions based on ultrahigh-molecular-weight polyethylene(UHMWPE)and low-molecular-weight HDPE(LMWPE)directly in synthesis.Zirconocenes rac-(CH_(3))_(2)Silnd_(2)ZrCl_(2)(Zr-1)and rac-(C_(6)H_(10))CplndZrCl_(2)(Zr-2)activated with methylaluminoxane(MAO)were used as the components of the binary catalyst.It has been shown that the use of Zr-1/MAO and Zr-2/MAO in ethylene polymerization at 30℃leads to the production of UHMWPE with Mw=1000 kg-mol^(-1)and LMWPE with Mw=18 kg·mol^(-1),respectively.Reactor polymer compositions(RPC)with LMWPE fraction contents ranging from 9 wt%to 42 wt%were obtained when a molar fraction of Zr-2 in the binary catalyst(Zr-1+Zr-2)/MAO va ried in the range from 0.3 to 0.85.A study of the molecular weight characteristics of RPC showed that it has a wide bimodal molecular weight distribution(MWD)and includes UHMWPE(Mw=1000 kg·mol^(-1))and LMWPE(Mw=18 kg·mol^(-1))fractions.The degree of crystallinity of the polymer products was determined using the DSC method.The tensile properties and melt indices of the materials were studied depending on the LMWPE fraction content in the polymer composition.UHMWPE/LMWPE compositions with high tensile properties and fluidity at a load of 5 kg were obtained.
基金supported by the National Natural Science Foundation of China(No.52473026)。
文摘Flexible polymer-based foam sensors have significant potential for application in wearable electronics and motion monitoring.However,these prospects are hindered by the complex and unenvironmentally friendly manufacturing processes.In this study,we employed melt blending and supercritical carbon dioxide foaming to fabricate an ethylene-vinyl acetate copolymer(EVA)/low-density polyethylene(LDPE)/carbon nanotube(CNT)piezoresistive foam sensor.The cross-linking agent bis(tert-butyldioxyisopropyl)benzene and the conductive filler CNT were incorporated into the EVA/LDPE composite,successfully achieving a chemically cross-linked and physically entangled composite structure that significantly enhanced the storage modulus and complex viscosity.Additionally,the compressive strength of EVA/LDPE/CNT foam with 10 parts per hundred rubber(phr)CNT reached 1.37 MPa at 50%compression,marking a 340%increase compared to the 0.31 MPa of the CNT-free sample.Furthermore,the EVA/LDPE/CNT composite foams,which incorporated 10 phr CNT,were prepared under specific foaming conditions,resulting in an ultra-low density of 0.11 g/cm^(3) and a higher sensitivity,with a gauge factor of–2.3.The piezoresistive foam sensors developed in this work could accurately detect human motion,thereby expanding their applications in the field of piezoresistive foam sensors and providing an effective strategy for the advancement of high-performance piezoresistive foam sensors.
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.
