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The increased interest in pulsed power field applications has generated the need for development of compact and remotely operated chargers driven by rechargeable batteries. With this objective, a compact and portable dc to dc Converter has been developed which has an output rating of 100kV, 0.4mA. The high voltage generation scheme uses a hybrid approach. The overall idea behind implementation of hybrid concept is to optimize voltage upliftment with suitable techniques for maximizing power delivered per unit volume. The proposed converter provides this feature and uses flyback converter in association with Cockcroft-Walton Multiplier [M. Jullian, Cockcroft-Walton Multiplier Optimum Design Guide V2.0, August 2005 (http//www.blazelabes.com)] for the generation of 100kV dc from 12V dc source, i.e., normal battery. In the first stage 12V dc is modulated/chopped into series of high frequency pulses by pulse width modulator and then increased in level up to 16kVpp by step up flyback transformer. Further by using n stage half wave series Cockcroft-Walton multiplier the voltage is stepped up to the level of 100kV. As switching device, state of the art metal-oxide-semiconductor field-effect transistor has been used. The obtained voltage multiplier cascade efficiency is 82.64%, whereas overall power conversion efficiency of the charging power supply is 85.47%. The control unit has been fiber optically isolated from high voltage unit due to safety consideration. The presented article explores complete design and development approach of compact and portable 100kV dc power supply which can be used for a variety of applications such as x-ray generation, ion implantation, charge particle acceleration, radio isotope production, etc.

Introduction Controversies remain regarding the safety of tocilizumab in the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this study, we seek to describe the infectious complications after tocilizumab in COVID patients and determine the related risk factors. Methods A single-center retrospective observational study was conducted among adult patients with SARS-CoV-2 infection admitted between 06/01/2020 and 12/31/2021 who received tocilizumab at our institution. Baseline demographics and laboratory values are obtained through reviewing electronic medical records. Risk factors of infectious complications after tocilizumab are identified through regression analysis. Statistics are performed using SPSS. P-value <0.05 is considered statistically significant. Results Out of the 52 patients identified, infectious complications after tocilizumab were documented in 30 patients (57.7%). The most common infections include pneumonia, urinary tract infections, and bacteremia of unknown sources. Overall mortality was 42.3%. Through multivariate regression analysis, age more than 65, hyperglycemia on admission, and tocilizumab administration more than 2 days after hospital admission are independent risk factors associated with developing infections. Conclusions In real-world experience, infectious complications are not uncommon in COVID patients who receive tocilizumab. Early use of tocilizumab may be of benefit. More rigorous patient selection and monitoring should be explored in future studies.

8067 Background: The defective immune system in plasma cell dyscrasia places patients at a higher risk of developing a severe infection, which is one of the leading causes of death in such patients. In an era of a global pandemic, it is essential to protect them against COVID-19, but fewer effective plasma cells lead to a suboptimal response to vaccines. There is still a lack of evidence whether the seroconversion is truly clinically relevant and if patients with plasma cell disorders would benefit from frequent boosters to maintain antibody levels. Methods: Online databases including PubMed, CINAHL, Ovid, and Cochrane were searched (January 11th, 2022), following the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. Only articles published in the English language were included. Abstracts, case reports, and case series were excluded. Out of 40 studies, 5 articles were selected for a systematic review. Results: In all 5 studies (N=654), seroconversion post-vaccination was used as a positive response to COVID-19 vaccination. Although patients with plasma cell disorders had a lower seroconversion rate compared to controls, the overall percentage was substantial and ranged between 23-95.5%. Amongst patients on active therapy, lower seroconversion rates were seen in patients on a CD-38 inhibitor, ranging from 20.2-92.1% (N=174). Also, a significantly lower percentage was recorded in patients above 65 years and those who have been treated with multiple therapies previously. Better seroconversion rates were seen in mRNA vaccines compared to J&J. Conclusions: Variable seropositive rates are seen in patients with plasma cell dyscrasias, lower rates are reported in patients on active therapy, CD-38 targeting therapy, and elderly patients. Hence, these patients should receive a 4 shot series. [Table: see text]

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