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Management of the plastic industry is a momentous challenge, one that pits enormous societal benefits against an accumulating reservoir of nearly indestructible waste. A promising strategy for recycling polyethylene (PE) and isotactic polypropylene (iPP), constituting roughly half the plastic produced annually worldwide, is melt blending for reformulation into useful products. Unfortunately, such blends are generally brittle and useless due to phase separation and mechanically weak domain interfaces. Recent studies have shown that addition of small amounts of semicrystalline PE-iPP block copolymers (ca. 1 wt%) to mixtures of these polyolefins results in ductility comparable to the pure materials. However, current methods for producing such additives rely on expensive reagents, prohibitively impacting the cost of recycling these inexpensive commodity plastics. Here, we describe an alternative strategy that exploits anionic polymerization of butadiene into block copolymers, with subsequent catalytic hydrogenation, yielding E and X blocks that are individually melt miscible with PE and iPP, where E and X are poly(ethylene-ran-ethylethylene) random copolymers with 6 wt% and 90 wt% ethylethylene repeat units, respectively. Cooling melt blended mixtures of PE and iPP containing 1 wt% of the triblock copolymer EXE of appropriate molecular weight, results in mechanical properties competitive with the component plastics. Blend toughness is obtained through interfacial topological entanglements of the amorphous X polymer and semicrystalline iPP, along with anchoring of the E blocks through cocrystallization with the PE homopolymer. Significantly, EXE can be inexpensively produced using currently practiced industrial scale polymerization methods, offering a practical approach to recycling the world's top two plastics.
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Block polymer self-assembly affords a versatile bottom-up strategy to develop materials with the desired properties dictated by specific symmetries and dimensions. Owing to distinct properties compared with linear counterparts, bottlebrush block polymers with side chains densely grafted on a backbone have attracted extensive attention. However, the morphologies found in bottlebrush block polymers so far are limited, and only lamellar and cylindrical ordered phases have been reported in diblock bottlebrushes. The absence of complex morphologies, such as networks, might originate from the intrinsically stiff backbone architecture. We experimentally investigated the morphologies of nonfrustrated ABC bottlebrush block terpolymers, based on two chemistries, poly(ethylene-alt-propylene)-b-polystyrene-b-poly(dl-lactic acid) (PEP-PS-PLA) and PEP-b-PS-b-poly(ethylene oxide) (PEP-PS-PEO), synthesized by ring-opening metathesis polymerization of norbornene-terminated macromonomers. Structural characterization based on small-angle X-ray scattering and transmission electron microscopy measurements revealed an unprecedented cylinders-in-undulating-lamellae (CUL) morphology with p2 symmetry for both systems. Additionally, automated liquid chromatography was employed to fractionate the PEP-PS-PLA bottlebrush polymer, leading to fractions with a spectrum of morphologies, including the CUL. These findings underscore the significance of macromolecular dispersity in nominally narrow dispersity bottlebrush polymers while demonstrating the power of this fractionation technique.
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OBJECTIVES: The focus of this research was to explore any potential link between nocturia and the risk of suicidal ideation. METHODS: Drawing from the National Health and Nutrition Survey, data relating to 25 241 participants was scrutinized. This included 13 421 individuals identifying as male and 11 820 individuals identifying as female. Participants provided information on nocturia and suicidal ideation via self-completed questionnaires. To determine if nocturia was independently related to suicidal ideation, a multivariable logistic regression analysis was employed. Analyses were also undertaken separately for adult males and females. RESULTS: It was found that around 3.5% of participants had experienced suicidal ideation. The results indicated that nocturia increased the risk for suicidal ideation in all adult groups (odds ratio [OR] = 1.67, 95% confidence interval[CI]: 1.37-2.03, p < 0.0001), including both males (OR = 1.91, 95% CI: 1.38-2.65, p < 0.001) and females (OR = 1.48, 95% CI: 1.158-1.90, p = 0.002). The risk for suicidal ideation increased with the severity of nocturia, with significant trends observed in adult males (p for trend = 0.04) and adult females (p for trend = 0.01). Additionally, subgroup examination showed a significant interaction between nocturia and educational level in adult males (p for interaction = 0.03). Among adult females, a noteworthy interaction was observed between nocturia and body mass index (p for interaction = 0.02). CONCLUSION: The research uncovered a connection between nocturia and an elevated risk of suicidal ideation.
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Block polymer self-assembly provides a versatile platform for creating useful materials endowed with three-dimensional periodic network morphologies that support orthogonal physical properties such as high ionic conductivity and a high elastic modulus. However, coil configurations limit conventional linear block polymers to finite ordered network dimensions, which are further restricted by slow self-assembly kinetics at high molecular weights. A bottlebrush architecture can circumvent both shortcomings owing to extended backbone configurations due to side chain crowding and molecular dynamics substantially free of chain entanglements. However, until now, network morphologies have not been reported in AB bottlebrush block copolymers, notwithstanding favorable mean-field predictions. We explored the phase behavior by small-angle X-ray scattering of 133 poly(ethylene-alt-propylene)-b-polystyrene (PEP-PS) diblock and PEP-PS-PEO triblock bottlebrush copolymers prepared by ring-opening metathesis polymerization (ROMP) of norbornene-functionalized poly(ethylene-alt-propylene) (PEP), poly(styrene) (PS), and poly(ethylene oxide) (PEO) macromonomers with total backbone degrees of polymerization Nbb between 20 and 40. The PEP-PS diblocks exhibited only cylindrical and lamellar morphologies over the composition range of ca. 30-70%. However, addition of variable-length bottlebrush PEO blocks to diblocks containing 30-50% PS led to the formation of a substantial core-shell double gyroid (GYR) phase window containing 20 bottlebrush triblock specimens, which is the focus of this report. Encouragingly, the GYR unit cell dimensions increased as d â¼ Nbb0.92, portending the ability to access larger network dimensions than previously obtained with linear AB or ABC block polymers. This work highlights extraordinary opportunities associated with applying facile ROMP chemistry to multiblock bottlebrush polymers.
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BACKGROUND: Pesticides are extensively applied globally. Pesticide residues induce calamitous effects on the environment and untargeted organisms. Public concerns for the safety of freshwater organisms and the challenges posed by aquatic contaminants remain high. In the present study, the acute toxicity of avermectins (AVMs) to the crayfish, Procambarus clarkii was evaluated. We also evaluated the potential effects of AVM on the biochemical and transcriptomic status of the hepatopancreas and gastrointestinal tract in P. clarkii. RESULTS: The 24, 48, 72, 96 h median lethal concentrations (LC50 ) of AVM on crayfish were 2.626, 1.162, 0.723, 0.566 mg L-1 , respectively. The crayfish were then exposed to 0.65 mg L-1 of AVM for 96 h. AVM significantly altered biochemical parameters including AChE and CAT activities in the hepatopancreas, and AChE, SOD and Na + -K + -ATPase activities in the gastrointestinal tract at several time points. Furthermore, transcriptomic analysis identified 953 and 1851 differentially-expressed genes (DEGs) in the hepatopancreas and gastrointestinal tract, respectively. KEGG enrichment showed that the gene expression profiles of the hepatopancreas and gastrointestinal tract were distinct from each other. The DEGs in the hepatopancreas were mostly enriched with stress-response pathways, while the majority of the DEGs in the gastrointestinal tract belonged to metabolism-related pathways. CONCLUSION: We demonstrated that the AVM induced acute toxicity, oxidative stress, osmoregulation disturbance, neurotoxicity and transcriptome imbalance in crayfish. These findings unraveled the detrimental effects of AVMs exposure on crayfish. © 2022 Society of Chemical Industry.
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Here, low-energy poly(ethylene terephthalate) (PET) chemical recycling in water: PET copolymers with diethyl 2,5-dihydroxyterephthalate (DHTE) undergo selective hydrolysis at DHTE sites, autocatalyzed by neighboring group participation, is demonstrated. Liberated oligomeric subchains further hydrolyze until only small molecules remain. Poly(ethylene terephthalate-stat-2,5-dihydroxyterephthalate) copolymers were synthesized via melt polycondensation and then hydrolyzed in 150-200 °C water with 0-1 wt% ZnCl2 , or alternatively in simulated sea water. Degradation progress follows pseudo-first order kinetics. With increasing DHTE loading, the rate constant increases monotonically while the thermal activation barrier decreases. The depolymerization products are ethylene glycol, terephthalic acid, 2,5-dihydroxyterephthalic acid, and bis(2-hydroxyethyl) terephthalate dimer, which could be used to regenerate virgin polymer. Composition-optimized copolymers show a decrease of nearly 50% in the Arrhenius activation energy, suggesting a 6-order reduction in depolymerization time under ambient conditions compared to that of PET homopolymer. This study provides new insight to the design of polymers for end-of-life while maintaining key properties like service temperature and mechanical properties. Moreover, this chemical recycling procedure is more environmentally friendly compared to traditional approaches since water is the only needed material, which is green, sustainable, and cheap.
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Thin passivating surface oxide layers on metal alloys form a dissipation horizon between dissimilar phases, hence harbour an inherent free energy and composition gradient. We exploit this gradient to drive order and selective surface separation (speciation), enabling redox-driven enrichment of the core by selective conversion of low standard reduction potential (E°) components into oxides. Coupling this oxide growth to volumetric changes during solidification allows us to create oxide crystallites trapped in a metal ('ship-in-a-bottle') or extrusion of metal fingerlings on the heavily oxidized particle. We confirm the underlying mechanism through high temperature X-ray diffraction and characterization of solidification-trapped particle states. We demonstrate that engineering the passivating surface oxide can lead to purification via selective dealloying with concomitant enrichment of the core, leading to disparate particle morphologies.
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Aleaciones , Óxidos , Oxidación-Reducción , Difracción de Rayos XRESUMEN
Here we report microphase-separated poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) as a reinforcing filler in PDMS thermosets that overcomes the long-standing problem of aging in the processing of silica-reinforced silicone. Surprisingly, PS-b-PDMS reinforced composites display comparable mechanical performance to silica-modified analogs, even though the modulus of PS is much smaller than that of silica and there is no evidence of percolation with respect to the rigid PS domains. We have found that a few unique characteristics contribute to the reinforcing performance of PS-b-PDMS. The strong self-assembly behavior promotes batch-to-batch repeatability by having well-dispersed fillers. The structure and size of the fillers depend on the loading and characteristics of both filler and matrix, along with the shear effect. The reinforcing effect of PS-b-PDMS is mostly brought by the entanglements between the corona layer of the filler and the matrix, rather than the hydrodynamic reinforcement of the PS phase.
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OBJECTIVE: Jinniu capsules, comprised of herbs and marine product extracts, are traditionally used in Chinese medicine. In this randomized multicenter clinical trial we evaluated the efficacy and safety of Jinniu capsules used to treat the symptoms of heroin withdrawal, as compared with lofexidine. METHODS: Two hundred and twelve patients with heroin dependence were randomly assigned to the Jinniu capsule or lofexidine treatment groups during a 10-day double-blind clinical trial. The severity of their opiate withdrawal symptoms was measured daily for 10 days. Anxiety was measured on days 0, 5, and 10. Safety assessment of the drugs included measurement of vital signs and side effects, as well as laboratory tests. RESULTS: Withdrawal symptom and anxiety scores decreased gradually over the treatment period, and no significant differences were found between two groups. No severe adverse events occurred during the treatment. CONCLUSION: Jinniu capsules may be an effective and safe agent in the management of opiate withdrawal.
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Clonidina/análogos & derivados , Medicamentos Herbarios Chinos/uso terapéutico , Antagonistas de Narcóticos/uso terapéutico , Síndrome de Abstinencia a Sustancias/tratamiento farmacológico , Adulto , Clonidina/efectos adversos , Clonidina/uso terapéutico , Método Doble Ciego , Medicamentos Herbarios Chinos/efectos adversos , Femenino , Dependencia de Heroína/rehabilitación , Humanos , Masculino , Antagonistas de Narcóticos/efectos adversos , Índice de Severidad de la Enfermedad , Factores de Tiempo , Resultado del Tratamiento , Adulto JovenRESUMEN
STUDY DESIGN: Cross-cultural adaptation and cross-sectional psychometric testing in a convenience sample of patients with low back pain. OBJECTIVE: The aim of this study was to translate and adapt the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) into a simplified Chinese version, and assess its reliability and validity. SUMMARY OF BACKGROUND DATA: No simplified Chinese version of the JOABPEQ was previously available. METHODS: We translated and culturally adapted the original English JOABPEQ to develop a Chinese version, based on cross-cultural adaptation guidelines. Principal component analysis with varimax rotation was used to confirm the factor structure of each subscale. Internal consistency was evaluated with Cronbach alpha. Test-retest reliability was examined in stable patients, who completed the questionnaire again at 4 days to 2 weeks from baseline. The validity of the translated Chinese version was assessed by examining the relationship between the JOABPEQ and Chinese versions of the Roland-Morris Disability Questionnaire (RMDQ), the Oswestry Disability Index (ODI), the Short Form Health Survey (SF-36), and the Numerical Pain Rating Scale. Ceiling and floor effects were considered present if more than 15% of respondents achieved the lowest or highest possible total score. RESULTS: The JOABPEQ showed excellent internal consistency (αâ=â0.886). The test-retest reliability (intraclass correlation coefficients) ranged from 0.951 to 0.977. The convergent validity of the Chinese version was supported by its high correlation with other physical functional status measures (RMDQ, ODI, and SF-36 Physical Function; r values from -0.645 to -0.726), and moderate correlation with other measures (SF-36 Bodily pain and Social functioning subscales; r values 0.426-0.546). Q5 Mental health was highly correlated with SF-36 items (r values 0.337-0.640). There was a floor effect in Q1 low back pain (38, 20.65%). CONCLUSION: The results indicate that the simplified Chinese version of the JOABPEQ is a reliable and valid instrument to measure the multidimensional status in patients with low back pain. LEVEL OF EVIDENCE: 4.