Gas gangrene is usually manifested as myonecrosis and subcutaneous gas accumulation, but rarely manifested as arterial occlusion or pneumatosis in the right ventricle and the pulmonary artery. In the ...presence of gas gangrene, special care must be taken to prevent against the formation of circulatory air embolism. The gas gangrene-induced gangrene in the limb of this patient might be attributed to the combined action of infection and arterial occlusion. MDT (Multidisciplinary team)-Green Channel mode is conductive to treatment success of gas gangrene.
Coaxial electrospun membranes with thermal energy storage and shape memory functions for simultaneous thermal/moisture management in personal cooling textiles.
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•The PU/PEG coaxial ...electrospun fibers have been prepared.•The membrane exhibits high enthalpy of 60.4 J/g and robust mechanical property.•The membrane sample exhibit good shape memory effect.•The membrane samples show adaptive permeability with temperature.
Developing textiles with simultaneous thermal regulation capability and adaptive moisture permeability is of great significance for not only reducing energy consumption but also enhancing personal comfort. To meet the above requirements, coaxial electrospun microfibers based on polyurethane (PU) and polyethylene glycol (PEG) were fabricated, in which PU worked as a supporting shell and PEG worked as an energy-storage core. The coaxial electrospinning technique made PEG to be uniformly encapsulated inside the microfibers to form a ‘core-shell’-like structure, imparting the membranes with a high phase change enthalpy (60.4 J/g), good encapsulation effect, thermal energy storage property and robust mechanical property (sustaining 125 times mass of load). Furthermore, the PU/PEG porous membranes exhibit excellent thermal-actuated shape memory effect, which enables macroscopic shape deformation and adaptive micropore geometry upon heating. The PU/PEG membranes with both thermal regulation capability and temperature-sensitive moisture permeability can generate excellent cooling and drying performances (7.6 °C cooler and better breathability than commercial cotton textile). Therefore, our work may provide a new strategy to design smart textiles with dynamic thermal and moisture management functions for improving the comfort of wearers under hot situations.
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•The ‘core–shell’-like BaTiO3@PPy particles were deposited on the GO platelets.•GO-tailored BaTiO3@PPy particles dispersion were achieved in the PVDF composites.•PVDF/BaTiO3@PPy-GO ...composites had low dielectric loss and high breakdown strength.•The mechanism was attributed to the GO-induced aggregation of BaTiO3@PPy particles.
Dielectric composites with low dielectric loss recently attract increasing concerns of researchers due to the great potential applications in microelectronic devices. In this work, novel hybrid particles, which were composed of barium titanate (BaTiO3), polypyrrole (PPy) and graphene oxide (GO), were prepared through the in situ polymerization of PPy on the surface of BaTiO3 particles and the deposition of BaTiO3@PPy particles on the surface of the GO platelets. Morphology and microstructure characterizations showed that the ‘core–shell’-like BaTiO3@PPy particles were prepared and these particles exhibited homogeneous dispersion on the GO platelets. Then, two kinds of poly(vinylidene fluoride) (PVDF)-based composites, including PVDF/BaTiO3@PPy and PVDF/BaTiO3@PPy-GO, were fabricated. Different from the relatively homogenous dispersion of BaTiO3@PPy particles in the whole PVDF/BaTiO3@PPy composites, the BaTiO3@PPy-GO particles exhibited slight aggregation in the PVDF/BaTiO3@PPy-GO composites due to the GO-induced local aggregation of BaTiO3@PPy particles. The two kinds of particles exhibited good nucleation effect and mainly promoted the crystallization of α-form PVDF. Electrical conductivity and dielectric property measurements showed that the PVDF/BaTiO3@PPy-GO composites had lower electrical conductivity, smaller dielectric loss but higher breakdown strength compared with the PVDF/BaTiO3@PPy composites. The mechanism was mainly attributed to the presence of GO platelets, which restricted the formation of the conductive path in the composites.
•A novel humidity sensor based on polysquraine microspheres doped by gold nanoparticles has been prepared.•The optimized humidity sensor is of a response/recovery time as short as 1/4 s, a hysteresis ...less than 5% and impedance variation >105.•A prototype portable machine are manufactured to demonstrate its applicablity in real-time breath monitoring.
Various conjugated polymer materials have been successfully applied in humidity sensors, but their response/recovery time are not satisfactory for breath humidity monitoring. In this research, a rapid and stable humidity sensor was fabricated from a polysquaraine, poly(1-phenylpyrrole-2-ylsquaraine) (PPPS) sample decorated by Au nanoparticles. Uniform PPPS microspheres in diameter were synthesized and loaded by gold nanoparticles (30 nm in diameter), and the structure was confirmed by X-ray photoelectron spectra and elemental mapping. Relative humidity (RH) values within the range of 11–95% were determined by testing the impedance response of the sensor at room temperature. The PPPS-2 sensor loaded with Au nanoparticles with 10% weight ratio to squaric acid offered the best humidity-sensing performance: the working range spreads from 11% to 95% RH; the response/recovery time is <1/4 s; its impedance variation reaches five orders of magnitude; the maximum hysteresis is 5%. Such a performance is attributed to electrical loading by gold and hydronium transportation. A portable device was fabricated for remote monitoring of breath humidity. Our results demonstrated that surface-engineered polysquaraines are of practical application in humidity measurement, and in particular, in breathing humidity monitoring.
Form-stable phase change materials (PCMs) are widely used for thermal management. However, the strong rigidity and the weak photoabsorption ability have hindered their practical applications. Herein, ...we report a flexible PCM based on paraffin wax (PW) and polydopamine-coated melamine foam (MF@PDA) for the seamlessly combined light-actuated shape memory and light-to-thermal energy storage capability. The MF@PDA foams with different PDA contents, which act as supporting scaffolds to adsorb PW, are successfully obtained by varying the immersion times and the dopamine concentrations. The low density and high porosity of MF@PDA foams allow for high weight fraction of PW to be incorporated, making the PCMs show high latent heat and encapsulation ability. Simultaneously, the elastic MF@PDA foams impart the PCMs with good shape memory property by triggering the phase transition of PW. More importantly, due to the efficient photothermal effect of PDA coating, the PCMs exhibit excellent light-actuated shape memory effect (shape recovery ratio ∼ 100%, shape recovery speed ∼ 100 s) and solar-to-thermal energy storage efficiency (80.8%). The light-actuated shape recovery rates and the solar-to-thermal transfer rates are increased with the augmented amount of PDA coating. Besides, the PCMs exhibit quite stable shape memory cyclic performance and thermal reliability. This study provides a new strategy to design flexible and light-responsive PCMs with the potential to be used in advanced solar energy storage systems.
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•The ternary composites containing PLLA, PBAT and CNFs were prepared.•PBAT and CNFs assembled into the “mutton kebab”-like structure during processing.•CNFs induced the epitaxial ...crystallization of PLLA on the surface of CNFs.•Highly-toughened, high heat resistant and self-healing properties were achieved.
Biodegradable poly(L-lactic acid) (PLLA) based blend composites with excellent toughness exhibit comprehensive applications and they can be substitute for the common polyolefin and polyester based composites. To date, various strategies have been developed to enhance the toughness of the PLLA based blends or composites. Here, carbon nanofibers (CNFs) incorporated PLLA/poly(butylene adipate-co-butylene terephthalate) (PBAT) blend composites were investigated. The crystallinity of the PLLA matrix were precisely tailored through annealing treatment. Interestingly, CNFs and PBAT particles self-assembled into the “mutton kebab”-like structure during processing. In addition, the annealing treatment facilitated the epitaxial crystallization of PLLA on the surface of CNFs that were not covered by PBAT due to the excellent heterogeneous nucleation effect of CNFs. Consequently, with the addition of 1 wt% CNFs and tailoring the blend composite with the PLLA crystallinity of about 32.6%, the impact strength of the composite was increased by 270% from 10.0 kJ/m2 to 37.0 kJ/m2. The toughening mechanisms were mainly connected with the greatly strengthened interfacial interaction between PLLA matrix and PBAT particles by CNFs through CNFs bridging effect and CNFs inducing PLLA crystallization, facilitating the transfer of stress under the load condition, especially at high PLLA crystallinity. Furthermore, it was found that CNFs exhibited outstanding photothermal conversion effect, which could endow the blend composites with mechanical-damage-healing ability. This work not only reveals the role of crystalline structure in toughening of the PLLA-based blend composites but also paves an effective way to prepare super-toughened, biodegradable, heat resistant and mechanical-damage-healing PLLA-based composites via tailoring the crystalline structure of the matrix.
Stroke is a leading cause of disability and death worldwide. Currently, there is a lack of clinically effective treatments for the brain damage following ischemic stroke. Catalpol is a bioactive ...compound derived from the traditional Chinese medicine Rehmannia glutinosa and shown to be protective in various neurological diseases. However, the potential roles of catalpol against ischemic stroke are still not completely clear.
This study aimed to further elucidate the protective effects of catalpol against ischemic stroke.
A rat permanent middle cerebral artery occlusion (pMCAO) and oxygen–glucose deprivation (OGD) model was established to assess the effect of catalpol in vivo and in vitro, respectively. Behavioral tests were used to examine the effects of catalpol on neurological function of ischemic rats. Immunostaining was performed to evaluate the proliferation, migration and differentiation of neural stem cells (NSCs) as well as the angiogenesis in each group. The protein level of related molecules was detected by western–blot. The effects of catalpol on cultured NSCs as well as brain microvascular endothelial cells (BMECs) subjected to OGD in vitro were also examined by similar methods.
Catalpol attenuated the neurological deficits and improved neurological function of ischemic rats. It stimulated the proliferation of NSCs in the subventricular zone (SVZ), promoted their migration to the ischemic cortex and differentiation into neurons or glial cells. At the same time, catalpol increased the cerebral vessels density and the number of proliferating cerebrovascular endothelial cells in the infracted cortex of ischemic rats. The level of SDF–1α and CXCR4 in the ischemic cortex was found to be enhanced by catalpol treatment. Catalpol was also shown to promote the proliferation and migration of cultured NSCs as well as the proliferation of BMECs subjected to OGD insult in vitro. Interestingly, the impact of catalpol on cultured cells was inhibited by CXCR4 inhibitor AMD3100. Moreover, the culture medium of BMECs containing catalpol promoted the proliferation of NSCs, which was also suppressed by AMD3100.
Our data demonstrate that catalpol exerts neuroprotective effects by promoting neurogenesis and angiogenesis via the SDF–1α/CXCR4 pathway, suggesting the therapeutic potential of catalpol in treating cerebral ischemia.
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Solid-liquid organic phase change materials (OPCMs) appeal tremendous attention in thermal energy storage and management for their various merits. However, low thermal conductivity (TC), inferior ...encapsulation ability and fatal fire hazard significantly impair the application accessibility of the OPCMs. This work designed and fabricated a new three-dimensional (3D) melamine foam (MF)/phosphorous cellulose (PC)/graphite nanoplatelets (GNPs) (MF/PC/GNP) network to compound with the OPCMs with all these problems simultaneously sovled. With the assistance of MF-modified ice-templated method and PC, the GNPs form a dense network to efficiently enhance the TC of the composite PCMs to 1.08 W/(m·K) at a relatively low content of 2.39 wt%, while the electric conductivity (EC) reaches 0.690 S/cm. In addition, the peak of heat release rate (PHRR) of the composite PCMs decreases from 725.62 kW/m2 of pure PEG to 624.04 kW/m2. Besides, the MF/PC/GNP network also endows the composite PCMs with multiple energy-transition aiblities.
Xianfeng lignite (XL) was subjected to sequential thermal dissolution (TD) in cyclohexane at 200–320°C. The yields of soluble portions (SPs) decreased with raising temperature from 200 to 260°C, but ...then increased with further raising the temperature. The SPs were analyzed with a Fourier transform infrared spectrometer, gas chromatograph/mass spectrometer, and atmospheric pressure solid analysis probe/time-of-flight mass spectrometer (ASAP/TOF-MS). The results show that cyclohexane is effective for thermally extracting inherent hydrocarbons in XL without breaking the covalent bonds. Intermolecular interactions such as hydrogen bonds, π–hydrogen bonds, and π–π interactions can be destroyed at higher temperatures and thereby release arenes and arenols trapped in the capsule structure of XL. According to ASAP/TOF-MS analysis, the molecular mass of organic species in the SPs is smaller than 550 u and SPs from different TD temperatures have different molecular mass distributions. The organic species detected with ASAP/TOF-MS have double bond equivalent values ranging from 0 to 11 and carbon numbers from 3 to 35. A series of arenes and alkylarenols were also confirmed by ASAP/TOF-MS analysis.
•TDT has a great effect on the yields and compositions of the soluble portions.•TD in cyclohexane is effective for extracting hydrocarbons from Xianfeng lignite.•Intermolecular interactions and capsule structure were easily destroyed at high TDTs.
Polymer dielectric composites have widespread applications in many fields ranging from energy storage, microelectronic devices, and sensors to power driven systems, etc. and attract much attention of ...researchers. However, it is still challenging to prepare advanced polymer dielectric composites with a high dielectric constant (ϵ′), low dielectric loss (tan δ) and simultaneously high breakdown strength (Ebd). In this work, conductive polypyrrole (PPy) nanoparticles were in situ synthesized in a reaction system containing the common barium titanate (BaTiO3, BT) or hydroxylated BaTiO3 (BTOH) particles, and then the PPy@BT and PPy@BTOH composite particles were incorporated into poly(vinylidene fluoride) (PVDF) to prepare the composites. The morphologies and microstructures of the PPy@BT and PPy@BTOH composite particles and the corresponding PVDF composites were comparatively investigated. The results showed that the PPy@BTOH composite particles had a ‘mulberry’-like morphology with a rough surface and the self-assembled structure could be maintained in the PVDF composites, which was apparently different from the PVDF/PPy@BT composites, in which most of the PPy nanoparticles dissociatively dispersed in the PVDF matrix. Electrical conductivity measurements showed that at high particle content (≥20 wt%), the PPy@BTOH composite particles endowed the composites with lower electrical conductivity compared with the PPy@BT composite particles. Dielectric property measurements showed that the ‘mulberry’-like PPy@BTOH composite particles endowed the PVDF composites with extremely high ϵ′, ultralow tan δ and high Ebd compared with the PVDF/PPy@BT composites with dissociatively dispersed PPy nanoparticles and BaTiO3 particles. The polarization and loss mechanisms of the composites were then proposed based on the morphologies and the microstructures of the composites. This work provides an alternative way to fabricate functional dielectric particles through trace functional groups inducing in situ polymerization of conductive polymers, and these particles can be used to fabricate advanced dielectric composites.
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