All-Cause Mortality in Type 2 Diabetes Patients Hospitalized for COVID-19 and Treated with Corticosteroids: A Single Center Cross-Sectional Study

Objective: This study aims to compare all-cause mortality and other hospital outcomes of hospitalized coronavirusdisease of 2019 patients using corticosteroids. Materials and methods: A comparative cross-sectional study was performed over three months by collecting data from patients’ medical charts. Results: The sample included 129 patients with type 2 diabetes (T2D) and 293 patients without diabetes, with more men than women in both groups. Patients withT2D were older, namely, those aged more than 70 years (54.3%) with the majority having abnormal glucose levels on admission (76.1%) and at discharge (76.9%). As a primary outcome, higher all-cause mortality was reported among patients without diabetes having more than two comorbidities (38.2%) compared to those with two or single comorbidities (21.0% and 13.9% respectively; p = 0.009). It significantly increased if patients without diabetes had abnormal glucose levels at admission (51.7%; p < 0.001) and discharge (44.7%; p < 0.001) compared to those with normal levels. Critical cases had higher all-cause mortality compared to less severe cases in patients with T2D (58.8%; p < 0.001) and without diabetes (61.0%; p < 0.001). Among secondary outcomes, a higher length of stay in the hospital was noted among patients with T2D (8.4 vs. 7.3 days; p = 0.015), in addition to a significantly higher number of ventilator-free days (2.7 vs. 1.6 days; p = 0.039). Conclusions: Although the treatment with corticosteroids was comparable between patients with and without T2D, hospital outcomes varied between the groups. Findings from this study can help provide additional clinical support for patients with T2D to allow better in-hospital management of COVID-19 cases

Evaluation of the Anticancer, Anti-Inflammatory, and Antioxidant Properties of Various Extracts of Annona Squamosa L.

Background: Screening medicinal plants for their biological activities and phytochemicals is important for finding safe and potent new compounds for therapeutic use. The current investigation was conducted in extracts of Lebanese A. squamosa (leaves and bark) to evaluate the antioxidant, anticancer, and anti-inflammatory activities. Methods: Seven extracts were prepared by ultrasound-assisted extraction (UAE) or microwave-assisted extraction (MAE), and using various solvents. The evaluation of antioxidant activity was done using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the anticancer activity assessed on the colon cancer HCT116 cell line was determined by water-soluble tetrazolium-1 (WST-1) viability assay. Finally, the anti-inflammatory activity was investigated by measuring the secreted amounts of prostaglandin E2 (PGE2) and interleukin 6 (IL-6) using. Results: The total phenolic contents were in the range between 27.3 to 179.5 mg GAE/g of plant extract, while total flavonoid contents were between 8.3 to 150.8 mg RE/g of plant extract. DPPH assay showed high antioxidant activity for the methanolic extracts obtained by UAE in both natural dried leaves and bark with IC50 values of 9.3 and 12.6 μg.mL-1, respectively. For WST-1 assay, methanolic extracts obtained by UAE showed a potent anti-proliferative effect against the HCT116 cell line with IC50 values ranged from 0.18 to 0.88 μg.mL-1. Also, the western blot assay suggested that these extracts may inhibit the proliferation of the HCT 116 cell line by causing cell cycle arrest through activation of the p21 pathway. Significant anti-inflammatory activity was observed due to the decrease in the secretion of IL-6 in lipopolysaccharide (LPS)-stimulated THP-1 cells. Conclusion: Therefore, the present study revealed that the dried leaves and bark of Lebanese A. squamosa methanolic extracts obtained by UAE possess effective bioactivities, and thus hold the potential application in the pharmacological field

Robust sliding mode controller for buck DC converter in off-grid applications

This paper presents a robust sliding mode controller of DC-DC buck converter for renewable energy applications, such as photovoltaic systems in off-grid configurations. Photovoltaic systems in off-grid configuration are exposed to significant variations in input voltage and power loads. The proposed sliding mode controller presents a simple and efficient method of continuously updating the duty cycle of a pulse width modulation unit (PWM) of a buck converter. The PWM unit is operated at constant switching frequency of 10 kHz carrier signal and varying duty cycle. The differences in input voltage and power load are treated as two bounded uncertainties, thus eliminating the need for input voltage sensor and output current sensors leaving the system with a single sensor required to measure the converter output voltage. That is, measured output voltage is compared with the reference voltage to continuously update the average duty cycle value of PWM unit. Adjustment of PWM duty cycle is performed while maintaining the sliding condition always fulfilled. The simulation results of the proposed controller showed robustness and accuracy against power load fluctuation, changes in desired output voltage, and variations in the input supply voltage that may result from the varying level of irradiance and temperature

Grid-Connected PV System with Reactive Power Management and an Optimized SRF-PLL Using Genetic Algorithm

This paper presents a two-stage grid-connected PV system with reactive power management capability. The proposed model can send phase-shifted current to the grid during a low-voltage ride through (LVRT) to recover the voltage levels of the grid’s feeders. The novelty of the proposed algorithm, unlike the common methods, is that it does not need to disable the maximum power point tracking (MPPT) state while managing active and reactive power injection simultaneously. Moreover, the new method promotes a safety factor by offering overcurrent protection to the PV inverter. The phase-locked loop based on the synchronous reference frame (SRF-PLL) is optimized using a genetic algorithm (GA). The settling time of SRF-PLL’s step response is minimized, and the frequency dynamics are improved to enhance synchronization during LVRT. The system’s performance is tested and verified using MATLAB/Simulink simulations. The obtained results prove the effectiveness of the proposed control algorithm in managing reactive power interventions. The optimized phase-locked loop shows robust performance and is compared to the conventional low-gain PLL to spot the enhancement

Modified phase locked loop for grid connected single phase inverter

Connecting a single-phase or three-phase inverter to the grid in distributed generation applications requires synchronization with the grid. Synchronization of an inverter-connected distributed generation units in its basic form necessitates accurate information about the frequency and phase angle of the utility grid. Phase Locked Loop (PLL) circuit is usually used for the purpose of synchronization. However, deviation in the grid frequency from nominal value will cause errors in the PLL estimated outputs, and that’s a major drawback. Moreover, if the grid is heavily distorted with low order harmonics the estimation of the grid phase angle deteriorates resulting in higher oscillations (errors) appearing in the synchronization voltage signals. This paper proposes a modified time delay PLL (MTDPLL) technique that continuously updates a variable time delay unit to keep track of the variation in the grid frequency. The MTDPLL is implemented along a Multi-Harmonic Decoupling Cell (MHDC) to overcome the effects of distortion caused by gird lower order harmonics. The performance of the proposed MTDPLL is verified by simulation and compared in terms of performance and accuracy with recent PLL techniques

Motor fault detection using sound signature and wavelet transform

The use of induction machines has gained fast popularity in many aspects of today’s energy applications and industrial productions. However, just as with any other machine, failure is expected due to a variety of faults in component and system levels. Therefore, it is necessary to improve machine reliability by performing preventive maintenance and exploring faulty indications in advance to avoid future failures. In normal operation, a distinct machine sound signature can be identify. Therefore, at any faulty operation, diagnosis of potential error can be defined based on output signature sound data analysis. Yet, this process of monitoring induction machine sounds and vibration can be hectic and extensive in terms of collecting data and compiling analysis. That is, a huge number of data samples need to be collected and stored in order to define abnormality operation. Therefore, in this work, wavelet-based algorithms were developed as an analysis process to analyze collected data and identify abnormality, with much fewer data samples and compiling process, as special prosperity of wavelet transform. As a result, MATLAB codes were implemented to analyze data based on sound signature technique and wavelet transform algorithms to show a significant improvement in identifying potential error and abnormality conditions

Direct control of active and reactive power for a grid-connected single-phase photovoltaic inverter

This paper presents a single-phase grid-connected photovoltaic system with direct control of active and reactive power through a power management system of a Photovoltaic inverter. The proposed control algorithm is designed to allow maximum utilization of the inverter’s available KVA capacity while maintaining grid power factor and current total harmonic distortion (THD) requirements within the grid standards. To reduce the complexity and improve the efficiency of the system, two independent PI controllers are implemented to control single-phase unipolar PWM voltage source inverter. One controller is used to control the power angle, and hence the active power flow, while the other controller is used to control the reactive power, and consequently the power factor by adjusting the voltage modulation index of the inverter. The proposed system is modelled and simulated using MATLAB/Simulink. The PV inverter has been examined while being simultaneously connected to grid and local load. Results obtained showed the ability of the PV inverter to manage the active and reactive power flow at, and below rated levels of solar irradiances; resulting in an increased inverter utilization factor, and enhanced power quality. The proposed system, was capable of operating at power factors in the range of 0.9 lead or lag for reactive power compensation purposes and delivered its power at a wide range of solar irradiance variations