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BackgroundThe high voltage power supply is an important part of the neutral beam injection heating system, which determines the beam energy and the quality of the extraction beam current. With the gradual increase of voltage level, the pulse step modulation (PSM) high voltage power supply cannot meet the experimental requirements.PurposeThis study aims to design an inverter high voltage power supply based on super capacitor energy storage to achieve fast switching of injected power for neutral beam modulation.MethodsSuper capacitor energy storage was adopted to reduce the required grid capacity and minimize the impact on the grid. The DC-DC resonant converter structure with soft-switching technology was used to improve the response speed of the power supply and reduce the switching loss of the switching devices. After the design of power module circuit topology,system modeling and calculation based on power supply performance specifications, the charging circuit and main loop PSIM simulation model were established, and the power supply performance indexes were simulated and verified. Finally, a test prototype of inverter power supply module was built to conduct the test of relevant performance indexes. [Results and Conclusions] After simulation and experimental verification, the power module is able to achieve a stable output of 1 600 V/50 A, which meets the design requirements of 6 MW/120 kV.

The limited availability of human heart tissue and its complex cell composition are major limiting factors for the reliable testing of drug efficacy and toxicity. Recently, we developed functional human and pig heart slice biomimetic culture systems that preserve the viability and functionality of 300 μm heart slices for up to 6 days. Here, we tested the reliability of this culture system for testing the cardiotoxicity of anti-cancer drugs. We tested three anti-cancer drugs (doxorubicin, trastuzumab, and sunitinib) with known different mechanisms of cardiotoxicity at three concentrations and assessed the effect of these drugs on heart slice viability, structure, function and gene expression. Slices incubated with any of these drugs for 48 h showed diminished in viability as well as loss of cardiomyocyte structure and function. Mechanistically, RNA sequencing of doxorubicin-treated tissues demonstrated a significant downregulation of cardiac genes and upregulation of oxidative stress responses. Trastuzumab treatment downregulated cardiac muscle contraction-related genes consistent with its clinically known effect on cardiomyocytes. Interestingly, sunitinib treatment resulted in significant downregulation of angiogenesis-related genes, in line with its mechanism of action. Similar to hiPS-derived-cardiomyocytes, heart slices recapitulated the expected toxicity of doxorubicin and trastuzumab, however, slices were superior in detecting sunitinib cardiotoxicity and mechanism in the clinically relevant concentration range of 0.1-1 μM. These results indicate that heart slice culture models have the potential to become a reliable platform for testing and elucidating mechanisms of drug cardiotoxicity.

Background and purposeShelter-in-place (SIP) orders implemented to mitigate severe acute respiratory syndrome coronavirus 2 spread may inadvertently discourage patient care-seeking behavior for critical conditions like acute ischemic stroke. We aimed to compare temporal trends in volume of acute stroke alerts, patient characteristics, telestroke care, and short-term outcomes pre- and post-SIP orders.MethodsWe conducted a cohort study in 21 stroke centers of an integrated healthcare system serving 4.4+ million members across Northern California. We included adult patients who presented with suspected acute stroke and were evaluated by telestroke between January 1, 2019, and May 9, 2020. SIP orders announced the week of March 15, 2020, created pre (January 1, 2019, to March 14, 2020) and post (March 15, 2020, to May 9, 2020) cohort for comparison. Main outcomes were stroke alert volumes and inpatient mortality for stroke.ResultsStroke alert weekly volume post-SIP (mean, 98 [95% CI, 92-104]) decreased significantly compared with pre-SIP (mean, 132 [95% CI, 130-136]; P

This work aims to measure the scattered radiation energy spectrum and radiation dose at different positions during radiological diagnosis through the Monte Carlo simulation and experiment. The results show that the average energy of the scattered radiation energy spectrum increases with the increase of the tube voltage and decreases with the increase of the scattering angle, but it changes very little with the measuring distance. It is not unified for the scattered radiation distribution in the space around the water phantom at the same tube voltage, and the exposure to scattered radiation is greater on the side closer to the water phantom or the X-ray tube. This indicates that the radiation exposure is not unified for medical staff in the scattered radiation field. The scattering energy spectrum and dose distribution are helpful to evaluate the scattered radiation exposure and enhance the self-protection awareness of medical staff in practice.

Objective To investigate the effect of balanophora polysaccharide (BPS) on neuro-autophagy and its therapeutic effect on spinal cord injury. Methods The rats were randomly divided into sham operation group(sham, n=10),model group(SCI, n=15,which were established according to the Allen's weight-striking method), and the BPS treatment group(BPS, n=45),which were given intra-gastrically with low, medium and high dose of BPS solution for 14 days). The BBB scores were measured to evaluate motor function. Hematoxylin-Eosin and Nissl staining was used to observe the morphological changes. The expression of autophagy markers of Beclin 1, LC3-Ⅱ and p62 was detected by Western blot. Results Compared with the sham operation group,the curve of BBB score-time in SCI group was significantly lower and the injury was severer(P＜0.05). In SCI group, the dorsal white matter and central gray matter of spinal cord were seriously injured with obvious cavity. Further observation showed that the number of neurons in SCI group was significantly decreased; the structure of cell body was incomplete. The result of Western bolt showed that the relative change of LC3 Ⅱ /Ⅰ and p62 was up-regulated on day 1,7 and 14, the highest expression of both protein was found on day 7(P＜0.05). At the same time,Beclin 1 was decreased after injury with lowest expression on day 7(P＜0.05). The BBB scores of BPS group were increased with a dose-dependent manner as compared with SCI group. The cavity of dorsal white matter and central gray matter shrinked. The number of neurons was increased with intact morphology. The expression of Beclin 1 and LC3 Ⅱ/Ⅰ was increased significantly in BPS group, while p62 decreased as compared to SCI group(P＜0.05). Conclusions BPS has a well-demonstrated neuron-protective effect and the underlying mechanism might be related to the protection of injured nerve cells.