Improved Performance of All-Solid-State Flexible Supercapacitor Based on the Stress-Compensation Effect

This work presents a facile strategy to develop a flexible polyaniline (PANI)-based supercapacitor (SC) with both high energy density and good capacitance retention. An electrode with a symmetrical sandwich-structured configuration (PANI/flexible porous support/PANI) is used as both working and counter electrodes for this supercapacitor. For a conventional electrode with PANI depositing on single side of the support (PANI/flexible support), the flexible support bends severely during the PANI electrodeposition process, which results in poor PANI deposition. On the contrary, for the symmetrical sandwich-structured electrode, due to the stress-compensation effect induced by this configuration, the support bending is significantly suppressed and thus PANI films with a good uniformity are realized. Moreover, the stress-compensation effect involved in the symmetrical sandwichstructured electrode can also effectively balance the stress caused by PANI expansion/shrinkage during its electrochemical charge/discharge operation, thus improving the mechanical stability. The symmetrical sandwich-structured electrode has larger PANI mass loading, better PANI morphologies and stronger mechanical stability than those of the conventional electrode. Consequently, the SC constructed by the symmetrical sandwich-structured electrode displays better electrochemical performance in terms of its larger specific areal capacitance (369.2 mF·cm^-2 at a current density of 0.25 mA·cm^-2), higher energy density (0.031 mWh·cm^-2 at a power density of 1.21 mW·cm^-2) and better cycling retention (93.2% of the retained capacity over 6000 cycles) than the SC constructed by the conventional electrode.

[Clinical application effect of modified nasopharyngeal swab sampling for 2019 novel coronavirus nucleic acid detection]

Objective: To study the clinical application effect of modified nasopharyngeal swab sampling for 2019 novel coronavirus nucleic acid detection. Methods: This study covered the period from January 14 to March 1, 2020.The supine position method and the protective face screen were used to collect nasopharyngeal swabs from February 24 onwards, before which, the nasopharyngeal swabs were collected by sitting position method. All the patients who were diagnosed with suspected/confirmed 2019 novel coronavirus infection were admitted from February 19 with the nasopharyngeal swabs collected outside the hospital before admission. (1) Thirty-four swabbing operators meeting the inclusion criteria of the study were recruited in this retrospective cohort study. They were grouped according to the collection method of nasopharyngeal swabs. Sixteen operators of Wuhan Taikang Tongji Hospital who applied the supine position method and the protective face screen were included in supine position method+ protective face screen group (15 males and 1 female, aged 34-49 years); 18 operators (12 from the First Affiliated Hospital of Army Medical University (the Third Military Medical University), 1 from Wuhan Jiangxia Mobile Cabin Hospital, 5 from the East District of People's Hospital of Wuhan University) who applied the traditional sitting position method were included in sitting position method group (2 males and 16 females, aged 25-49 years). In supine position method+ protective face screen group, when collecting sample, the patient lay flat and wore a special protective face screen for nasopharyngeal swab sampling, with neck slightly extending and face turning to the opposite side of the operator about 10°. The self-designed questionnaire was used to investigate the cooperation, the incidence of nausea, coughing, sneezing, and struggling of patients evaluated by the operators, the operation time for a single swab sample, the fear of operation and the perceived exposure risk of operators in the two groups. (2) Sixty-five patients (22 males and 43 females, aged 25-91 years) admitted to Wuhan Taikang Tongji Hospital who successively received the sitting position method and supine position method+ protective face screen for nasopharyngeal swabs sampling and with complete nucleic acid detection results were included. The positive rates of nucleic acid detection by the two sampling methods of nasopharyngeal swabs of the patients were statistically analyzed. (3) Forty-one patients who could express their feelings accurately were selected out of those 65 patients (12 males and 29 females, aged 27-83 years). The comfort of patients in the process of sampling by the two methods was investigated. (4) Thirty-four patients (10 males and 24 females, aged 25-83 years) with two or more consecutive negative results of nucleic acid detection of nasopharyngeal swabs by sitting position method were selected from the above 65 patients. The positive rate of nucleic acid detection of nasopharyngeal swab of patients by supine position method+ protective face screen, i. e. negative to positive rate was statistically analyzed. Data were statistically analyzed with t test, Wilcoxon signed rank test, and chi-square test. Results: (1) Compared with those of sitting position method group, the cooperation score of patients evaluated by the operators in supine position method+ protective face screen group was significantly higher (Z=-4.928, P<0.01), the incidence of nausea, choking cough, sneezing, and struggling of patients evaluated by the operators, and the fear of operation score and the perceived exposure risk score of operators in supine position method+ protective face screen group were significantly lower (Z=-5.071, -5.046, -4.095, -4.397, -4.174, -5.049, P<0.01), and the operation time for a single swab sample in supine position method+ protective face screen group was significantly longer (t=223.17, P<0.01). (2) The positive rate of nucleic acid detection of nasopharyngeal swabs by supine position method+ protective face screen was 60.00% (39/65), which was obviously higher than 41.54% (27/65) by sitting position method (χ(2)=4.432, P<0.05). (3) The comfort score of the 41 patients during nasopharyngeal swabs sampling by supine position method+ protective face screen was significantly higher than that by sitting position method (Z=-5.319, P<0.01). (4) Of the 34 patients with two or more consecutive negative results of nucleic acid detection of nasopharyngeal swabs by sitting position method, the rate of negative to positive of nucleic acid detection was 26.47% (9/34) after sampling by supine position method+ protective face screen. Conclusions: Compared with the traditional sitting position method, detection of 2019 novel coronavirus nucleic acids of nasopharyngeal swabs collected by supine method combined with protective face screen is worth promoting, because of its better comfort of patients, low exposure risk for operators, in addition to reducing in the false negative result to some extent, which may help reduce false recurrence of discharged patients.

Optical fiber in-line Mach-Zehnder interferometer based on dual internal mirrors formed by a hollow sphere pair

We demonstrate a fiber in-line Mach-Zehnder interferometer based on dual internal mirrors formed by a hollow sphere pair and fabricated by femtosecond laser micromachining together with the fusion splicing technique. The hollow sphere surface adjacent to the fiber core can reflect part of the incident light beam to the air-cladding interface, where the light beam is reflected again before returning to the fiber core by another hollow sphere surface and recombining with the light beam remaining in the fiber core. Such an interferometer is miniature and robust, and is sensitive to environmental variations and allows simultaneous surrounding refractive index, temperature, and curvature measurement.

Miniaturized fiber in-line Mach-Zehnder interferometer based on inner air cavity for high-temperature sensing

We demonstrate a miniaturized fiber in-line Mach-Zehnder interferometer based on an inner air cavity adjacent to the fiber core for high-temperature sensing. The inner air cavity is fabricated by femtosecond laser micromachining and the fusion splicing technique. Such a device is robust and insensitive to ambient refractive index change, and has high temperature sensitivity of ∼43.2  pm/°C, up to 1000°C, and low cross sensitivity to strain.

Optical fiber Fabry-Perot interferometer cavity fabricated by femtosecond laser micromachining and fusion splicing for refractive index sensing

We demonstrate a fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement. The interferometer cavity is formed by drilling a micro-hole at the cleaved fiber end facet, followed by fusion splicing. A micro-channel is inscribed by femtosecond laser micromachining to vertically cross the cavity to allow liquid to flow in. The refractive index sensitivity obtained is ~994 nm/RIU (refractive index unit). Such a device is simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity of ~4.8 × 10(-6) RIU/°C.