Background The thermal stability of viruses in gelatin liquid formulations for medical research and application is poorly understood and this study aimed to examine the thermal stability of 4 enveloped and nonenveloped DNA and RNA viruses in hydrolyzed gelatin liquid formulations. Methods Bovine herpesvirus (BHV) was used as a model virus to examine the molecular weight (MW), concentration and gelatin type and to optimize virus stability in liquid formulations at 25 °C and 4 °C. Using the model virus liquid formulation, the stability of multiple enveloped and nonenveloped RNA and DNA viruses, including parainfluenza virus, reovirus (RV), BHV, and adenovirus (AdV), was monitored over up to a 30-week storage period. Results The BHV model virus was considered stable after 3 weeks in hydrolyzed gelatin (MW: 4000) with a 0.8 LRV (log10 reduction value) at 25 °C or a 0.2 LRV at 4 °C, compared to the stabilities observed in higher MW gelatin (60,000 and 160,000) with an LRV above 1. Based on the gelatin type, BHV in alkaline-treated hydrolyzed gelatin samples were unexpectantly more stable than in acid-treated hydrolyzed gelatin sample. All four viruses exhibited stability at 4 °C for at least 8 weeks, BHV or AdV remained stable for over 30 weeks of storage, and at 25 °C, AdV and RV remained stable for 8 weeks. Conclusion The results demonstrated that 5% of 4000 MW hydrolyzed gelatin formulation can act as a relevant stabilizer for the thermal stability of viruses in medical research and application.

The thermal stability of relevant viruses in gelatin liquid formulations for medical research and application is poorly understood. Bovine herpesvirus (BHV) was used as a model virus to examine the molecular weight (MW), concentration and gelatin type and to optimize virus stability in liquid formulations at 25 °C and 4 °C. Using the model virus stable liquid formulation, the stability of multiple enveloped and nonenveloped RNA and DNA viruses, including parainfluenza virus (PIV), reovirus (RV), BHV, and adenovirus (AdV), was monitored over up to a 30-week storage period. The BHV model virus was considered stable after 3 weeks in hydrolyzed gelatin (MW: 4000) with a 0.8 LRV (log10 reduction value) at 25 °C or a 0.2 LRV at 4 °C, compared to the stabilities observed in higher MW gelatin (60000 and 160000) with an LRV above 1. Based on the gelatin type, BHV in B-type gelatin samples were unexpectantly more stable than in A-type gelatin sample. All four viruses exhibited stability at 4 °C for at least 8 weeks, BHV or AdV remained stable for over 30 weeks of storage, and at 25 °C, AdV and RV remained stable for 8 weeks. The results demonstrated that 5% hydrolyzed gelatin can act as a relevant stabilizer for the thermal stability of viruses in medical research and application.

A Power Conditioning System (PCS) for a PV power generation system obtains the maximum power from a photovoltaic (PV) array by Maximum Power Point Tracking (MPPT), but losses in the inverter are a factor in lowering the power obtained by the MPPT. The generation of harmonic currents is also a problem for PCS. This paper proposes the application of the Peak Current Control Switching (PCCS) method in PCS for PV Generation System using a half bridge inverter. The half bridge inverter improves efficiency by reducing the number of switching elements and further suppresses harmonic currents by controlling them using the PCCS method. In this paper, a comparative simulation of the conventional Hysteresis Current Control (HCC) method and the proposed PCCS method is performed using a half bridge inverter. The results of harmonic analysis and comparative simulation of total harmonic distortion (THD) show that the PCCS method generates harmonic components near the switching frequency, and that the proposed PCCS method always has a lower distortion rate than the conventional HCC method.