Search

Background: The association among coronary heart disease, ischemic stroke, and hydrocephalus remains ambiguous. Objectives: There is a need for a Mendelian randomization study to evaluate the underlying causality between coronary heart disease, ischemic stroke, and hydrocephalus. Methods: The data source utilized genome‐wide association studies, employing a threshold of p < 5 × 10−8 to identify single nucleotide polymorphisms strongly linked to ischemic stroke and coronary heart disease as instrumental variables (IVs). Five methods—inverse variance weighted (IVW), Mendelian randomization (MR) Egger, Weighted Median, Weighted mode, and Simple mode—utilized the selected IVs to estimate the causality between ischemic stroke, coronary heart disease, and hydrocephalus. Results: The IVW demonstrated that ischemic stroke and coronary heart disease serve as risk factors for hydrocephalus (odds ratio [OR] = 1.650, 95% CI: 1.066–2.554, p = 0.025; OR = 1.307, 95% CI: 1.023–1.668, p = 0.032). Both the MR‐Egger intercept test and Cochran's Q test affirmed the relative reliability of the IVW analysis results. However, no evidence of a reverse causation was observed between hydrocephalus and coronary heart disease or ischemic stroke. Conclusions: Coronary heart disease and Ischemic stroke may increase the risk of hydrocephalus. [ABSTRACT FROM AUTHOR]

Fog processing has a significant impact on sulfur chemistry in the atmosphere. This study analyzed three winter fog events in Hong Kong using single‐particle aerosol mass spectrometry (SPAMS) and a Monitor for AeRosols and GAses in ambient air (MARGA). Black carbon (BC)‐related carbonaceous particles with substantial sulfate amounts comprised the largest particle number fraction (56.7%). Sulfate mass concentration decreased during fog due to the cloud's effective scavenging, but fog processing notably promoted sulfate formation at the single‐particle level (average peak area increases of 31.2%). Hydroxymethanesulfonate (HMS), an important S(IV) compound and fog tracer, was identified accounting for up to 12% by particle number fraction. Although pH showed a positive correlation (r = 0.53–0.69) with HMS particles in each fog scenario, a negative overall correlation (r = −0.51) was observed. Further analysis revealed that the higher aerosol acidity (pH 0.65–3.11), promoted Fe dissolution, leading to 49% of HMS particles being mixed with Fe, which potentially facilitated sulfate formation via the Fenton reaction. Additionally, around 40% of HMS‐Fe particles are mixed with oxalate, thereby warranting further attention for their potential to cause more intricate sulfur oxidation processes. This study reveals the initial identification of a high mixed‐state of HMS‐Fe, which could potentially serve as a crucial avenue for the formation of sulfate on individual particulate matter. Considering the persistent augmentation of aerosol acidity in the Asian region, this phenomenon necessitates further investigation and attention. Plain Language Summary: Cloud and fog processes are crucial for atmospheric chemistry and important pathways in sulfate formation. However, current models often underestimate sulfate production in the atmosphere. While several potential pathways have been proposed, the influence of organic compounds on hydroxymethanesulfonate (HMS) formation and its subsequent sulfate generation is yet to be fully explored. This study, utilizing a single‐particle perspective, reveals that higher aerosol acidity in coastal areas can lead to the dissolution of iron (Fe) in coastal aerosols, thereby promoting the formation of HMS‐Fe. Additionally, as a transition metal, Fe has the potential to catalyze the conversion of HMS to sulfates. This finding challenges the prevailing notion that HMS hinders sulfate production by being less susceptible to oxidation by hydrogen peroxide (H2O2) and other radicals. The significance of this process is particularly pronounced in coastal or remote marine atmospheres, where cloud and fog processes exhibit higher aerosol acidity and limited ammonia sources. Furthermore, considering the current global scenario of increased aerosol acidity, the impact of transition metals on sulfate formation in HMS is likely to be more prominent. Consequently, this phenomenon necessitates further investigation and attention. [ABSTRACT FROM AUTHOR]

Smoke aerosols from wildfires play a vital role in marine ecosystems and the ocean carbon cycle. This study analyzed a severe wildfires incident occurred in the Indo‐China Peninsula on 26 March 2019, and assessed its impact on ocean carbon sink. The satellite observations showed that the wildfires covered an area of about 56% of the entire peninsula, burning an area of 1.17 × 106 km2. Consequently, the wildfires discharged about 0.43 × 109 kg carbon. Moreover, a substantial amount of smoke released by severe wildfires was carried downstream by the wind and reached the western Pacific Ocean within 2 days. These smoke aerosols contribute to the ocean carbon sink through the mechanisms of the biological pump and their own carbon deposition. Model simulation results showed smoke aerosols contribute 6.44 × 104 kg black carbon to surface ocean by their own carbon deposition. Moreover, during the period of smoke aerosol's deposition, the flourishing growth of phytoplankton resulted in an increased carbon export of 0.25 ± 0.09 × 109 kg carbon (the biological pump mechanism), which represented approximately 57.97% ± 20.30% of the carbon emissions originating from the wildfire‐affected source region. Our research showed a positive impact of large wildfires on the ocean carbon sink, indicating the potential of smoke aerosols to alleviate the climate pressures resulting from carbon dioxide released by wildfires through improving the capacity of ocean carbon sink. Plain Language Summary: Wildfires emit substantial amounts of carbon dioxide into the atmosphere within a short timeframe. The ocean can mitigate the environmental impact of these wildfire events by fixing carbon. As one of the world's fire hotspot and the most significant burning area in the whole of Asia, it is necessary to understand the contribution of smoke aerosols emitted from the Indo‐China Peninsula to the Pacific Ocean carbon sink. We found that the source area of wildfires emitted 0.43 × 109 kg of carbon on 26 March 2019, and the smoke aerosols emitted by wildfires were carried by winds to the western Pacific Ocean within two days, and inputted 6.44 × 104 kg of black carbon. The increased ocean carbon export during the deposition of the smoke aerosol was 0.25 ± 0.09 × 109 kg, which is about half of the carbon emissions caused by wildfires. The results of this study suggest that smoke aerosols can contribute to the oceanic carbon sink, thereby alleviating the pressure on carbon emissions caused by wildfires. Key Points: A severe fire incident which account for 56% of the land area of the Indo‐China Peninsula has been researchedContribution of smoke aerosols to surface ocean carbon sink is primarily attributed by biological pump rather than carbon self‐depositionThe ocean assimilates around 57.97% ± 20.30% of the carbon emissions released by wildfires [ABSTRACT FROM AUTHOR]

Polar stratospheric clouds (PSCs) play a key role in Arctic amplification and stratospheric ozone destruction in polar regions. In this paper, we used the CALIPSO data to analyze the spatiotemporal distribution of Arctic PSCs from 2006 to 2021. We found that Arctic PSCs mainly appear in December, peak in late December and early January, disappearing in late February and early March. PSCs can extend from heights near the tropopause to over 25 km. However, there is the lowest fraction of PSCs in the 2014/2015 winter. This study found that the temperature in the 2014/2015 winter was warmer than the 15‐year average temperature, with the lowest temperature slightly below the PSCs formation temperature of about 5 K. The formation of the Ural blocking high accompanied by the poleward propagation of the planetary wave caused a sudden stratospheric warming (SSW) event on 3 January 2015, during which the warm air entered the polar vortex and divided it into two lobes. Additionally, a reduction in SO2 column mass density before the SSW event resulted PSCs occurring with a frequency of only 0.148 and dissipating rapidly in December. Moreover, the concentration of H2O and HNO3 in the gravitational settling process of PSCs decreased by 20–50%, the reduction of condensation nuclei made PSCs with the highest frequency of 0.074 in February appear briefly and then disappear. The chemical and dynamic analysis of PSCs formation is needed to further understand the spatiotemporal distribution of Arctic PSCs and to better predict future Arctic amplification and ozone destruction. Plain Language Summary: Polar stratospheric clouds (PSCs) influence polar ozone depletion by providing a reaction interface and also influencing surface temperature changes through longwave radiation effects. Previous studies on polar stratospheric clouds mainly focus on the Antarctic, and few studies on the temporal and spatial distribution characteristics of Arctic PSCs over long timescales. Therefore, by studying the spatial and temporal distribution of PSCs in the Arctic, we found that the spatial and temporal distribution of PSCs in the Arctic has obvious interannual variation compared with that in the Antarctic. The stratospheric sudden warming (SSW) events that occur almost every 2 years in the Arctic cause great interannual variations of the Arctic polar vortex and thus affect the distribution of Arctic PSCs. Moreover, there is the least and almost none occurrence of PSCs in the 2014/2015 winter, the chemical and dynamic analysis found that SSW, decrease of SO2, H2O, and HNO3 concentration are not conducive to the formation of PSCs. It is of great significance to study the influencing factors of Arctic PSCs formation and provide a new basis for further prediction of Arctic amplification and ozone destruction. Key Points: The fraction of Arctic polar stratospheric clouds (PSCs) during 2014/2015 winter was the lowest observed in the past 15 yearsThe splitting of polar vortex and the rise in temperature caused by sudden stratospheric warming (SSW) inhibited the formation of PSCsThe decrease in stratospheric sulfur dioxide, nitric acid, and water was unfavorable for the formation of PSCs before and after the SSW [ABSTRACT FROM AUTHOR]

The development of a single polymer chain with the dual functions of self‐healing and degradation is challenging. Herein, we report the synthesis of self‐healing and degradable polymers (SDP) via the integration of hierarchical hydrogen bonding groups and degradable polycaprolactone (PCL) segments. The dynamic reconstruction of hierarchical hydrogen bonding endowed the as‐prepared polymers with excellent self‐healing properties. The degradation properties were regulated via the proportion of PCL in the soft segments. The incorporation of PCL segments resulted in better degradability and improved the tensile strength of the polymer from 9.2 to 28.3 MPa. The as‐prepared polymers could recover their mechanical properties after self‐healing. The temperature‐dependent Fourier‐transform infrared spectra (FT‐IR) indicated that the hierarchical hydrogen bonding was capable of dissociation and re‐association with a variation in the temperature. The as‐synthesized sustainable polymers, which exhibit self‐healing properties and degradability, are expected to be useful in future energy and environmental applications. [ABSTRACT FROM AUTHOR]

The crystallization age of the Sunjiafen Formation volcanic rocks is 253.9 ± 1.1 Ma. Geochemical data show that these volcanic rocks belong to the shoshonitic and metaluminous series and have high Sr and low Y contents (461–582 and 5.60–6.74 ppm, respectively), MgO = 1.32–2.65 wt%, and Na2O/K2O = 0.81–1.40. In MgO−SiO2, Cr−SiO2, Sr/Y−Y and (La/Yb)N−YbN diagrams, data for the samples plot in the adakite and "adakite related to thickened lower crust" fields. As such, we suggest that the Sunjiafen Formation C−type adakitic andesites formed in a compressional tectonic setting. The youngest age (youngest peak age) of two sandstone samples from the Linxi Formation are 251 Ma (257 Ma) and 237 Ma (254 Ma). Detrital zircons with ages of >1500 Ma have εHf(t) values of −5.87 to +6.31. A comparison of the age spectra and εHf(t) values of the detrital zircons in the Linxi Formation with those of igneous zircons from the Central Asian Orogenic Belt and North China Craton indicates the formation was derived from both the belt and the craton. We identified "Jura–type Folds" that formed in peripheral foreland basin in the Linxi Formation, and along with plant fossil fragments (Paracalamites frigidus). These and previously published results indicate the Paleo–Asian Ocean closed along the Xar Moron–Changchun Suture zone during the Late Permian. The study area was in a continuous compressional setting during the Late Permian and formed a peripheral foreland basin that was related to continent–continent collision. [ABSTRACT FROM AUTHOR]

SUMMARY: Simple telomeric repeats composed of six to seven iterating nucleotide units are important sequences typically found at the ends of chromosomes. Here we analyzed their abundance and homogeneity in 42 gymnosperm (29 newly sequenced), 29 angiosperm (one newly sequenced), and eight bryophytes using bioinformatics, conventional cytogenetic and molecular biology approaches to explore their diversity across land plants. We found more than 10 000‐fold variation in the amounts of telomeric repeats among the investigated taxa. Repeat abundance was positively correlated with increasing intragenomic sequence heterogeneity and occurrence at non‐telomeric positions, but there was no correlation with genome size. The highest abundance/heterogeneity was found in the gymnosperm genus Cycas (Cycadaceae), in which megabase‐sized blocks of telomeric repeats (i.e., billions of copies) were identified. Fluorescent in situ hybridization experiments using variant‐specific probes revealed canonical Arabidopsis‐type telomeric TTTAGGG repeats at chromosome ends, while pericentromeric blocks comprised at least four major telomeric variants with decreasing abundance: TTTAGGG>TTCAGGG >TTTAAGG>TTCAAGG. Such a diversity of repeats was not found in the sister cycad family Zamiaceae or in any other species analyzed. Using immunocytochemistry, we showed that the pericentromeric blocks of telomeric repeats overlapped with histone H3 serine 10 phosphorylation signals. We show that species of Cycas have amplified their telomeric repeats in centromeric and telomeric positions on telocentric chromosomes to extraordinary high levels. The ancestral chromosome number reconstruction suggests their occurrence is unlikely to be the product of ancient Robertsonian chromosome fusions. We speculate as to how the observed chromosome dynamics may be associated with the diversification of cycads. [ABSTRACT FROM AUTHOR]

The interfacial interactions between ultra‐high molecular weight polyethylene (UHMWPE) fiber and polymer determine the overall performance and service life of the fiber reinforced composite materials. In this article, polyaniline (PANI) layer is uniformly deposited on the surface of the UHMWPE fiber after plasma treatment to enhance the interfacial adhesion between UHMWPE fiber and rubber. At the same time, the PANI layer can also form a conductive path at the interface to monitor the damage of the composites in real time. Compared with the untreated UHMWPE fiber, the H pull‐out force of the PANI‐deposited UHMWPE fiber with rubber is increased by 67.9%, which is due to good mechanical interlocking and chemical bond between the fiber and the matrix. Moreover, the electrical resistance change during the fiber pull‐out process has a good correlation with the pull‐out force curve, which provides a new idea for in‐situ monitoring of the damage of composites. [ABSTRACT FROM AUTHOR]

In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, a simple and facile method of aramid nanofiber (ANF) coating is demonstrated in this article. Tannic acid (TA) and polyethyleneimine (PEI) are polymerized in an alkaline solution to form a thin TA/PEI (TP) layer that is deposited on the surface of AF to introduce functional groups such as hydroxyl and amino groups. Then, the ANF coating is utilized to construct nanostructures on the surface of AF to improve the interfacial adhesion between the fiber and the rubber. Through hydrogen bonding and/or π‐π stacking between the TP layer and the ANF, the ANF coating is firmly attached to the surface of AF. Compared with the untreated fiber, the interfacial adhesion of AF coated with ANF after 1, 3, 5, 7, 9 deposition cycles is increased by 27.8%, 29.1%, 31.5%, 43.1%, and 30.3%, and the mechanical properties of the fibers remain almost unchanged. This method shows its advantages of simple, facile, and time‐effective, which is of great significance for industrial applications. [ABSTRACT FROM AUTHOR]

The migration and blooming of antioxidant molecules in the field of anti‐aging rubber is a challenge, where developing novel nanocarriers loaded with antioxidant molecules can solve the above problem. In this article, the surface thiol functionalized mesoporous silica nanorods loaded with antioxidant N‐(1,3‐dimethyl)butyl‐N′‐phenyl‐p‐phenylenediamine (MSN‐SH‐4020) was synthesized to avoid the blooming of antioxidants and then to improve the anti‐aging performance of styrene‐butadiene rubber (SBR). The migration of antioxidant molecules could be limited by encapsulating antioxidant in the pore of mesoporous silica nanorods, and the contend of antioxidant in the SBR reaches up to 1.33 wt%. The sustained release of antioxidant molecules from the pore increases the effective time of action of the antioxidant. After 168 hours of thermal oxidative aging test at 100°C, styrene‐butadiene rubber with 10 wt % surface thiol functionalized mesoporous silica nanorods loaded with 4020 (MSN‐SH‐4020) shows preservation of mechanical properties without blooming. This approach is highly perspective in many applications, such as long‐life sealing rubber and conveyor belts. [ABSTRACT FROM AUTHOR]

In renewable energy generation systems, the DC–DC converter with high voltage gain is indispensable, which is used to convert the low output voltage of photovoltaic (PV) cells and fuel cells to the high DC bus voltage. In this study, a cost-effective clamping capacitor boost (CCB) converter with high voltage gain is proposed. In the basis of the conventional boost converter, a clamping capacitor cell with two capacitors and two diodes is embedded. Then, the voltage gain of the proposed CCB converter can be doubled compared with the conventional boost converter. Further, unlike the switched capacitor high voltage gain converter, there is no large current spikes on the capacitors in the proposed CCB converter, which can reduce the current stresses and the costs of capacitors a lot. The operation principles and characteristics of the proposed CCB converter are analysed in detail and verified by simulation. Finally, a 450 W prototype is implemented to validate the performances and advantages of the proposed CCB converter. The proposed CCB converter provides a cost-effective choice for high voltage gain converters in the renewable energy generation system with PV cells. [ABSTRACT FROM AUTHOR]

The abundant dust particles from widespread deserts in East Asia play a significant role in regional climate and air quality. In this study, we provide a comprehensive evaluation of the widely used Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue (DB) aerosol retrievals in desert regions of East Asia using ground-based observations over eight sites of the China Aerosol Remote Sensing Network (CARSNET). Different from their well-characterized performance in urban and cropland areas around the globe, DB aerosol optical depth (AOD) retrievals exhibit underestimation across the deserts in East Asia. We found that 38%-96% of satellite values fall out of an expected-error envelope of ±(0.05 + 20%AODCARSNET), with the worst performance in Taklimakan Desert. In particular, DB retrievals erroneously give a nearly constant low values of 0.05 in Taklimakan Desert when AOD is below 0.5, which does not match with variation of moderate dust plumes. Comparison with Multi-angle Imaging SpectroRadiometer AOD shows that a similar underestimation is prevalent over the extensive deserts. Inversion of sky light measurements show that single scattering albedos of the yellow dust in East Asia are mostly below 0.9 at 440 nm, much lower than the 'whiter' and 'redder' dust models applied in the DB algorithm. On the other hand, overestimation of surface reflectance dominantly contributes to the significant low constant AOD values in MODIS DB retrievals in Taklimakan Desert. These large biases, however, can be substantially reduced by considering unique characteristics of aerosols and surface over the arid regions in East Asia. [ABSTRACT FROM AUTHOR]

Isocitrate dehydrogenase (IDH) is a key enzyme in the tricarboxylate (TCA) cycle, which may play an important role in the virulence of pathogenic bacteria. Here, two structurally different IDHs from a plant pathogen Xanthomonas campestris pv. campestris 8004 (XccIDH1 and XccIDH2) were characterized in detail. The recombinant XccIDH1 forms homodimer in solution, while the recombinant XccIDH2 is a typical monomer. Phylogenetic analysis showed that XccIDH1 belongs to the type I IDH subfamily and XccIDH2 groups into the monomeric IDH clade. Kinetic characterization demonstrated that XccIDH1's specificity towards NAD+ was 110-fold greater than NADP+, while XccIDH2's specificity towards NADP+ was 353-fold greater than NAD+. The putative coenzyme discriminating amino acids (Asp268, Ile269 and Ala275 for XccIDH1, and Lys589, His590 and Arg601 for XccIDH2) were studied by site-directed mutagenesis. The coenzyme specificities of the two mutants, mXccIDH1 and mXccIDH2, were completely reversed from NAD+ to NADP+, and NADP+ to NAD+, respectively. Furthermore, Ser80 of XccIDH1, and Lys256 and Tyr421 of XccIDH2, were the determinants for the substrate binding. The detailed biochemical properties, such as optimal pH and temperature, thermostability, and metal ion effects, of XccIDH1 and XccIDH2 were further investigated. The possibility of taking the two IDHs into consideration as the targets for drug development to control the plant diseases caused by Xcc 8004 were described and discussed thoroughly. [ABSTRACT FROM AUTHOR]

ABSTRACT Bio-based elastomers used in industry have attracted much attention. We prepared bio-based engineering polyester elastomer (BEE) nanocomposites by mixing bio-based engineering polyester elastomers with carbon (CB). The CB/BEE nanocomposites were exposed to an artificial weathering environment for different time periods. Both its aging behavior changes and aging mechanism were investigated in this article. The tensile strength retention rates were each above 90% after aging at 100°C and 125°C for 72 h. CB/BEE nanocomposites exhibited good anti-aging properties. Furthermore, the chemical changes were detected by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crosslink density changes during aging of BEE were determined as well. A plausible aging mechanism of BEE was proposed. It can be concluded that the thermal oxidation process gives priority to further crosslinking in the initial period of aging. As the aging time increases, chain scission becomes the dominant element in the subsequent thermal oxidation process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40862. [ABSTRACT FROM AUTHOR]

Surface modified fibrillar silicate (FS) was prepared by dopamine oxide polymerization and self-assembly of poly(dopamine) (PDA) on the FS surface, presynthesized silver nanoparticles subsequently adhered to the PDA functionalized FS (FS-PDA) surface by simply dipping FS-PDA in silver nanoparticles solution, owing to the metal-binding ability of catechol and nitrogen-containing groups on the PDA coating on the surface of FS. The chemical composition of the modified FS surface was determined by X-ray photoelectron spectroscopy. Surface morphological changes of the FS nanofibers were observed by transmission electron microscopy. The results indicated that the in situ spontaneous oxidative polymerization of dopamine on the FS surface and the immobilization of Ag nanoparticles on the surface of FS were successful. The FS-PDA/Ag demonstrated a significant enhancement in antibacterial properties compared to the pristine FS by using Escherichia coli as model strain. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39859. [ABSTRACT FROM AUTHOR]

A spray drying approach has been used to prepare polyurethane/multiwalled carbon nanotube (PU/MWCNT) composites. By using this method, the MWCNTs can be dispersed homogeneously in the PU matrix in an attempt to improve the mechanical properties of the nanocomposites. The morphology of the resulting PU/MWCNT composites was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM observations illustrate that the MWCNTs are dispersed finely and uniformly in the PU matrix. X-ray diffraction results indicate that the microphase separation structure of the PU is slightly affected by the presence of the MWCNTs. The mechanical properties such as tensile strength, tensile modulus, elongation at break, and hardness of the nanocomposites were studied. The electrical and the thermal conductivity of the nanocomposites were also evaluated. The results show that both the electrical and the thermal conductivity increase with the increase of MWCNT loading. In addition, the percolation threshold value of the PU composites is significantly reduced to about 5 wt % because of the high aspect ratio of carbon nanotubes and exclusive effect of latex particles of PU emulsion in dispersion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The thermoplastic polyurethane/multiwalled carbon nanotube (TPU/CNT) nanocomposites with high conductivity and low percolation threshold value were prepared by melting blending and annealing treatment. The effect of annealing process on the microphase structure and the properties of TPU/CNT nanocomposites was studied. It has been shown that CNT flocculation can occur in TPU/CNT nanocomposites during the annealing process. At a critical CNT content, which defined the percolation threshold, CNTs could form conductivity network. The conductive percolation threshold value of TPU/CNT nanocomposites was decreased from 10 to 4% after annealing process, and the conductivity of TPU/CNT nanocomposites with 10 vol % of CNT could reach 1.1 S/m after an annealing time of 1 h. The significant enhancement of electrical conductivity was influenced by the annealing time and the content of CNTs. The formation of CNT networks was also verified by dynamic viscoelastic characterization. The results of X-ray diffraction and differential scanning calorimetry indicated that annealing process reinforced the microphase separation of the nanocomposites. Mechanical properties test showed that the annealing treatment was in favor of improving the mechanical properties; however, further increase in the annealing time has negative effect on the mechanical properties. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

A novel method for the preparation of electrical conductive surface silvered acrylonitrile-butadiene rubber (NBR) was developed. Dopamine was spontaneously oxide polymerized and deposited onto the surface of NBR. Electroless plating of silver was carried out on the poly(dopamine) (PDA)-functionalized NBR surface. The composition of the NBR surface was studied by X-ray photoelectron spectroscopy (XPS). XPS results showed that PDA was successfully deposited onto the NBR surface. The morphology of the NBR surface was observed by scanning electron microscopy (SEM). The SEM images showed that PDA had formed a distinctive layer ready for electroless deposition of silver. The catechol/quinone groups on the PDA molecular structure can be used as binding sites for silver ions. The silvered NBR showed high surface conductivity of 1.4 Ω. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Surface functionalization of the plasma-pretreated polycarbonate (PC) track-etched membranes via plasma-induced thermally graft copolymerization of acrylic acid (AAc) was carried out. The resulting PC membranes with grafted AAc side chains were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis. The morphology of the PC membranes was studied by scanning electron microscopy (SEM). The results showed that the grafted PAAc polymers were formed uniformly inside the pores throughout the entire membrane thickness. With increase in the pore-filling ratio, the pore diameters of PAAc-grafted membranes became smaller. The PC-g-PAAc membranes exhibit rapid and reversible response of the flux to the environmental pH as pH is switched between 3 and 9. Between pH 3.5 and 5.5, the membranes demonstrate a pH-valve function as the carboxyl group changes from neutral to charged with a corresponding variation in chain configuration. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To resist the plastic deformation of polymer particles during hot press molding, high molecular weights, and moduli are required for composites with segregated structures, thus the prepared composites exhibit poor flexibility. Also, larger particle sizes can bring lower percolation thresholds while the ensuing greater deformation destroys the conductive network. Moreover, segregated composites still face preparation complexities. Herein, a facile method for developing flexible composites with large‐size segregated structures is proposed. First, silver‐coated polydopamine‐modified reduced graphene oxide (Ag@PrGO), as conductive fillers, is prepared by electroless plating. Next, polydimethylsiloxane (PDMS)‐coated polyolefin elastomer (POE) beads are put into a bag containing the fillers. After a simple shaking, the fillers are adhered to the POE surface as the cohesive property of cured PDMS. Finally, flexible composites with large‐size segregated structures are obtained via hot pressing. Benefiting from the 2D structure of the Ag@PrGO and the ability to slip, the conductive networks possess adaptable deformability. The prepared composites exhibit excellent electrical conductivity (203.55 S cm−1) at filler volume fractions of 3.4 vol%. The EMI shielding effectiveness can reach 70 dB in the X‐band at a thickness of 1.9 mm and remains stable after bending and rubbing damage. This work paves the way for constructing large‐size segregated structures. [ABSTRACT FROM AUTHOR]

Ultrahigh molecular weight polyethylene (UHMWPE) fibers possess excellent mechanical properties, yet their applications are severely limited by surface inertness and low melting points. To enhance surface activity and temperature resistance, soluble polyimide (PI) is applied to the surface of UHMWPE fibers. A mussel‐inspired biomimetic polycatechol/polyamine (PA) coating is initially constructed on the UHMWPE fiber surface by oxidative self‐polymerization, serving as a secondary reaction platform. Subsequently, multifunctional UHMWPE‐PA‐PI fibers are prepared by depositing soluble PI on the fiber surface via impregnation. The PA and PI layers are firmly bonded by hydrogen bonding interactions and physical adhesion. The results show that the PI‐coated UHMWPE fiber surface exhibits enhanced chemical activity, hydrophilicity, and thermal stability, with an increased thermal decomposition temperature of approximately 30 °C. Compared to pristine UHMWPE, the breaking force of UHMWPE‐PA‐PI fibers increases by 14.9%, and the interfacial adhesion strength between the fiber and rubber improves by 65.5%. The PI coatings also provide thermal insulation, acid resistance, and erasability functionalities. This modification strategy is highly efficient, simple, and less damaging, offering a novel solution to address UHMWPE fibers' surface inertness and temperature intolerance. [ABSTRACT FROM AUTHOR]

Nitrile rubber (NBR)/sliding graft copolymer (SGC) composites with significantly improved strength and damping property are successfully prepared. SGC is a novel kind of supramolecular material with sliding crosslink junctions. The micromorphology analyses of NBR/SGC composites indicate that the SGC phase with particle size less than 500 nm is fairly uniformly dispersed in the NBR matrix. As SGC content increases, the loss factors (tan δ) of NBR/SGC composites increase gradually. Specifically, the tan δ of NBR/SGC (100/40) is about 1.2 times higher than that of pristine NBR rubber. The tensile strength and elongation at break of NBR/SGC composites are unexpectedly improved after the addition of SGC. The significantly improved damping performance and tensile strength can be ascribed to the pulley effect of SGC and the strong interfacial hydrogen bonds between SGC and NBR. The high damping performance and good mechanical strength make the NBR/SGC composite a promising high‐performance damping material. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47188. [ABSTRACT FROM AUTHOR]