Self-pulsing discharge of a plasma brush operated in atmospheric-pressure argon

A plasma brush excited by DC voltage is developed with argon as working gas in the ambient air. The time evolution of the discharge current, the light emission, and the sustaining voltage are analyzed under different conditions. The self-pulsing phenomenon of the discharge is observed with oscillated voltage and intermittent current. The self-pulsing frequency ranges from several tens hertz to several hundred hertz depending on the output power and the gas flow rate. It increases with the increasing of the gas flow rate, while it decreases as the output power increases. The phenomenon is explained qualitatively based on a spatially resolved measurement about the discharge

Gender-specific physical activity-related injuries and risk factors among university students in China: a multicentre population-based cross-sectional study

Objectives Data on the problem of physical activity-related injury (PARI) in university students and the risk factors for PARI among different genders are rare. We conducted a multicentre population-based study to investigate the occurrence of PARI and to explore the gender-specific risk factors for PARI among Chinese university students.Design Cross-sectional study.Participants A total of 5341 students in grades 1–3 at eight universities in four Chinese cities were selected to complete the online questionnaires during March and April 2017. The questionnaires assessed sociodemographic characteristics, physical activity PA) involvement, sleep duration, sedentary behaviour and PARI experiences in the past 12 months.Main outcome measures PARI during the past 12 months.Results Among the 5341 participants, 1293 suffered from at least one PARI in the past 12 months, with an overall incidence rate of 24.2% (males: 26.2%, females: 23.2%) and an injury risk of 0.38 injuries/student/year (males: 0.48, females: 0.32). Over half of the injured (57.3%) experienced a withdrawal time of PA and nearly two-fifths (39.6%) required medical attention. Irrespective of gender, Shantou and Xi’an students, sports team members and those who engaged in sports and leisure-time vigorous-intensity PA (VPA) at a higher frequency were more likely to suffer from PARI. Male students who participated in sports and leisure-time VPA for long durations had a greater likelihood of sustaining PARI, while having a chronic condition and being involved in sports and leisure-time moderate-intensity PA at a higher frequency and longer duration were potential contributors to PARI among females.Conclusions The occurrence of PARI and its risk factors differed by gender, which provides a direction towards developing targeted and effective gender-specific preventative programmes to protect Chinese university students from PARI

A double‐mode planar argon plume produced by varying the distance from an atmospheric pressure plasma jet

Abstract Atmospheric pressure planar plumes are desirable for the applications of low temperature plasmas, such as rapid modification of large‐scale surfaces. Up to now, only single‐mode planar plumes with either a streamer mode or a filamentary mode have been reported in the literature. Distinctive from the single‐mode planar plumes, a double‐mode argon planar plume has been generated in this article, which operates in the streamer mode with a larger distance away from a plasma jet and transits to the filamentary mode with decreasing the distance. Discharge characteristics and plasma parameters are compared for the two modes. Results indicate that the streamer mode and the filamentary mode correspond to pulsed and humped discharges respectively. Fast photography reveals that the streamer‐mode plume is composed of stochastically branching streamers, while the filamentary‐mode plume results from a series of moving filaments similar to those in barrier discharge. In contrast to the streamer mode, the filamentary mode has lower excited electron temperature and vibrational temperature, whereas higher electron density and gas temperature. In addition, better hydrophilicity of polyethylene terephthalate surface is achieved in the filamentary mode

Ultrasound-Responsive Polymeric Micelles for Sonoporation-Assisted Site-Specific Therapeutic Action

Targeting drug delivery remains a challenge in various disease treatment including cancer. The local drug deposit could be greatly enhanced by some external stimuli-responsive systems. Here we develop pluronic P123/F127 polymeric micelles (M) encapsulating curcumin (Cur) that are permeabilized directly by focused ultrasound, in which ultrasound triggers drug release. Tumor preferential accumulation and site-specific sonochemotherapy were then evaluated. Cur-loaded P123/F127 mixed micelles (Cur-M) exhibited longer circulating time and increased cellular uptake compared to free Cur. With the assistance of focused ultrasound treatment, Cur-M showed tumor-targeting deposition in a time-dependent manner following systemic administration. This was due to enhanced permeabilization of tumor regions and increased penetration of Cur-M in irradiated tumor cells by ultrasound sonoporation. Furthermore, Cur-M self-assembly could be regulated by ultrasound irradiation. In vitro Cur release from mixed micelles was greatly dependent on ultrasound intensity but not on duration, suggesting the cavitational threshold was necessary to initiate subsequent sonochemotherapy. In vivo site-specific drug release was demonstrated in dual-tumor models, which showed spatial-temporal release of entrapped drugs following intratumoral injection. The sonoporation-assisted site-specific chemotherapy significantly inhibited tumor growth and the decrease in tumor weight was approximately 6.5-fold more than without exposure to ultrasound irradiation. In conclusion, the established ultrasound-guided nanomedicine targeting deposit and local release may represent a new strategy to improve chemotherapy efficiency

Ultrabroad Dynamic All-Solid-State Radiation Dose Detector Based on a 0D Cs₃Cu₂I₅ Perovskite-Like Single Crystal

Radiation dose detectors based on a gas-filled detecting mode play an important role in cancer radiation therapy, nuclear accident early warning, and radiation protection but still suffer from frequent air density corrections, a high working voltage, and a long stability time. Therefore, to tackle these issues, the development of high-performance all-solid-state radiation dose detectors is urgently needed. Here, we demonstrated a prototype of a highly sensitive all-solid-state radiation dose detector based on a highly efficient Cs3Cu2I5 perovskite-like single crystal and a Si photodetector with a heterojunction structure. The Cs3Cu2I5-based detector exhibits an ultrabroad dynamic range of 11.45 mGy·h–1 to 107.3 Gy·h–1, covering nearly 5 orders of magnitude for γ-ray with the upper limit being 100 times higher than that of Cs3Cu2I nanocrystal of 0.846 Gy·h–1 and the detection limit approaching the lower limit of the radiotherapy level (10 mGy·h–1). Moreover, it has an outstanding linear response with a linear correlation coefficient (R2) of 0.9999 for the X/γ-ray incident dose rate and a good repeatable response deviation of less than 0.3% for γ-rays, which is comparable to classical ionization chamber detectors. This work opens a horizon of developing ultrabroad dynamic, highly sensitive, and low-power consumption all-solid-state radiation dose detectors based on perovskite-like single-crystal scintillators