The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries (LIBs). Therefore, it is crucial to develop novel nanofibrous membranes with enhanced mechanical strength and thermal stability. In this work, the fluorinated polyimide (FPI) was synthesized and blended with polyvinylidene fluoride (PVDF) to fabricate composite nanofibrous membranes (CNMs) via electrospinning method. Benefiting from the introduction of aromatic FPI, the prepared PVDF/FPI nanofibrous membranes were endowed with enhanced mechanical strength and thermal stability. When the FPI content increased from 0 to 30 wt%, the tensile strength of composite nanofibrous membranes enhanced from 1.57 to 2.30 MPa. Moreover, there are almost no dimensional shrinkage for the CNM-30 containing 30 wt% FPI after heat treatment at 160 °C for 1 h. Furthermore, the prepared CNMs show improved electrochemical performances in comparison with neat PVDF and commercial Celgard membranes. The electrolyte uptake and ionic conductivity of the CNMs could reach to 522.4% and 1.14 ms•cm −1 , respectively. The prepared CNMs could provide an innovative and promising approach for the development and design of high-performance separators.
Wearable electronic skins have aroused extensive interest in health detection, human–computer interaction, and robotics. However, it remains a great challenge to realize the multifunctional electronic skin with a wide detection range, high sensitivity, multi‐stimulus response, and wearable comfort on a single device. Here, a flexible porous thermoplastic polyurethane (TPU)/carbon black (CB) multimodal sensor that perceives multiple stimuli of pressure, strain, and humidity is prepared by the water vapor‐induced phase separation method. The as‐prepared device exhibits a wide pressure detection range (up to 49 kPa), excellent sensitivity (0.21 kPa−1), fast response (150 ms), and recovery time (120 ms). Furthermore, as a strain sensor, it is not only highly stretchable (730%), but also can operate over a strain range of 0–240% with a sensitivity of up to 1485.2 and excellent durability. Moreover, the designed sensor can detect humidity changes from 35% to 90% and has a fast response time (1.2 s), while enabling non‐contact sensing of a fingertip. Importantly, the porous TPU/CB film presents excellent breathability, enabling it to achieve a high level of comfort. Therefore, the perfect integration of these features ensures the potential applications of porous TPU/CB sensors in human activity detection, exhale monitoring, and breathable wearable devices.
Objective The accuracy of colposcopy-guided biopsy is key to the success of colposcopic triage in cervical cancer screening programs. However, there is no widely adopted biopsy guideline up to date. Our study aimed to determine whether multi-quadrants biopsy improves the yield of cervical lesions. Methods Eleven population-based cervical cancer screening studies were conducted in China. Cytology, high-risk human papillomavirus (hrHPV) testing and visual inspection were performed for primary screening. Females positive on one or more tests were referred for colposcopy and biopsy. The proportion of detected cervical intraepithelial neoplasia (CIN)2+ and yields by quadrant lesion-targeted biopsy or 4-quadrant random biopsy were compared. Results Among 4,923 females included, 1,606 had quadrant lesion-targeted biopsy, and 3,317 had 4-quadrant random biopsy. The cumulative CIN2+ yield increased from 0.10 for only one quadrant-targeted biopsy to 0.21, 0.34, and 0.58 for at most two, three and four quadrants targeted biopsies. Among hrHPV positive females with high-grade squamous intraepithelial lesion (HSIL)+ cytology, the cumulative CIN2+ yield of a second targeted biopsy in another quadrant was significantly increased (P<0.05). Among hrHPV-negative females, the yield of 4-quadrant random biopsies was 0.005, and the yield by lesion-targeted biopsies was 0.017. For hrHPV positive females who had 4-quadrant random biopsy, the additional CIN2+ yield for HSIL+, low-grade squamous intraepithelial lesion (LSIL) cytology, or abnormal visual inspection via acetic acid and Lugol’s iodine (VIA/VILI) were 0.46, 0.11, 0.14. Conclusions A 4-quadrant random biopsy is recommended only for hrHPV positive females with HSIL cytology, and is acceptable if hrHPV positive with LSIL cytology or with abnormal VIA/VILI. Our findings add evidences for an objective and practical biopsy standard to guide colposcopy in cervical cancer screening programs in low- and middle-income countries.
Trapped space charges in epoxy composite distort the electric field, which will induce the failure of the insulation system, and nano graphene oxide may inhibit the curing behavior of epoxy resin matrix. This paper analyzes how the two interfaces affect the electron traps of epoxy resin/graphene oxide systems with different nanofiller contents. The electron affinity energy of epoxy resin matrix and nano filler molecules in the epoxy resin/graphene oxide system is calculated based on quantum chemistry. It is found that nano graphene oxide has a strong electron affinity energy and is easier to capture electrons. Then the influence of the interface formed by the epoxy resin matrix and the nano graphene oxide on the electron transfer ability is calculated. The epoxy resin matrix contains the electron transfer ability of interfaces formed by nano graphene oxide and the molecular chain is different from that of unreacted molecules. The results can provide a reference for the modification of epoxy resin/graphene oxide nanocomposites.
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