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Due to global warming and shortage of fossil fuels, the grid-connected solar photovoltaic (PV) system has gained significant popularity all over the world. The modular multilevel cascaded (MMC) inverter is the natural choice for step-up transformer and line filter less direct medium voltage grid integration of solar PV systems. However, power quality and loss are the important issues while connecting the PV system to the medium voltage grid through MMC inverter. Modulation technique is the key to maintain output power quality, e.g., total harmonic distortion (THD) and to ensure low switching and conduction losses. In this paper, an advanced modulation technique named “triangle saturated common mode pulse width modulation (TSCMPWM)” control is proposed for a 3-phase 5-level MMC inverter-based grid-tied PV system. Compared to traditional modulation techniques, the proposed TSCMPWM control offers the lowest voltage THD as well as lower inverter power losses. Performance of the proposed modulation technique is evaluated in MATLAB/Simulink environment and tested with a reduced scale prototype test platform. Both simulation and experimental results show the effectiveness of the proposed modulation technique.

AbstractBackgroundDengue, the world's fastest‐growing vector‐borne disease, has skyrocketed in the 21st century. Dengue has harmed human health since its first known cases among Spanish soldiers in the Philippines to its 21st‐century outbreaks in Southeast Asia, the Pacific, and the Americas. In light of the current circumstances, it is imperative to investigate its origin and prevalence, enabling the implementation of effective interventions to curb the upsurge.MethodsOur study examines the history of dengue outbreaks, and evolving impact on public health, aiming to offer valuable insights for a more resilient public health response worldwide. In this comprehensive review, we incorporated data from renowned databases such as PubMed, Google Scholar, and Scopus to provide a thorough analysis of dengue outbreaks.ResultsRecent dengue outbreaks are associated with rapid urbanization, international travel, climatic change, and socioeconomic factors. Rapid urbanization and poor urban design and sanitation have created mosquito breeding places for dengue vectors. Also, international travel and trade have spread the pathogen. Climate change in the past two decades has favored mosquito habitats and outbreaks. Socioeconomic differences have also amplified the impact of dengue outbreaks on vulnerable communities. Dengue mitigation requires vector control, community engagement, healthcare strengthening, and international cooperation.ConclusionClimate change adaptation and urban planning are crucial. Although problems remain, a comprehensive vector control and community involvement plan may reduce dengue epidemics and improve public health in our interconnected world.

This paper highlights the preparation and characterization of MgCo2O4 and Cr-doped MgCo 2O4 nanoparticles grown using a solid-state reaction route. The crystallinity and crystallographic phase structure have been investigated by the X-ray diffraction (XRD), which evidences the cubic crystal structure of MgCo2O4 with space group Fd3m. The crystallites of pristine MgCo2O4 have an average size of 18.88 nm, as determined by Scherrer’s formula. It exhibits an increment of crystallite size from 18.88 nm to 21.60 nm with Cr ions substitution in the MgCo2O4 matrix. Halder–Wagner (H–W) technique reveals the parallel results of crystallite size followed by the inversed behavior of dislocation density and lattice strain. The study of FESEM illustrates the aggregation of spherical nanostructures with well-dispersed grains. UV–Vis spectroscopy depicts an enhancement in absorption accompanied by blue shift and increase in Egfrom 4.22 eV to 4.85 eV after Cr addition. Dielectric measurements have revealed that the dielectric constant is noticed to reduce with the introduction of Cr into the MgCo2O4 crystal framework. The electrical resistivity reduces after Cr impurity is incorporated into MgCo2O4 and has been found to decrease with increasing temperature. Impedance analysis has been carried out on MgCo2O4 and Cr-doped MgCo2O4, and it is observed that Cr doping improves the impedance.

Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.

Abstract The present work demonstrated the preparation of sodium oxide impregnated on carbon nanotubes (CNTs) and its application as a heterogeneous catalyst for transesterification of waste cooking oil. The catalyst was prepared by impregnation of metal oxide such as sodium oxide, Na2O on the CNTs by calcination at 500 °C for 3 h. It was assumed that the positive metal ion which is Na+ (cations) possess Lewis acidity, whereby, high negativity of oxygen ions can acts as the Bronsted bases, which could enhance the activity of the catalyst. The characterization of synthesized Na2O impregnated-CNTs nanocatalyst was performed using Temperature-programmed desorption of carbon dioxide (TPD-CO2), X-ray diffraction (XRD), infrared spectroscopy and Field emission scanning electron microscope (FESEM). Herein, the mechanism of the transesterification process assisted by the Lewis acidic metal oxide on carbon support was proposed and explained. Series of reactions were carried out to determine the performance of the catalyst. It was found that the prepared Na2O(20 wt%)/CNTs catalysts yielded above 97% of FAME yield at 65 °C assisted by 3 wt% of catalyst amount and 20:1 of methanol-to-oil molar ratio in 3 h of reaction time. Moreover, the results on catalyst’s reusability indicated that the catalyst could last for 3 subsequent reaction cycles due to deactivation of the catalyst caused by leaching of metal oxides and poisioning effect on the active sites. It can be concluded that the prepared Lewis acidic carbon catalyst has a potential to catalyse the production of biodiesel from waste cooking oil (WCO).

Nanofluid is considered to be a new generation heat transfer medium which has attracted significant attention from the research community for the past two decades due to its reported high effectiveness in various heat transfer applications. Dispersed solid nanoparticles with enhanced thermal conductivity in base fluid possess substantial competence in augmenting thermal performance at the expense of moderate pumping power. This inclusive study elaborates the impact of nanofluids on thermo-hydraulic performance of thermal devices in order to ensure the appropriate selection and implementation of nanofluids in various engineering thermal devices. Inclusion of nanofluid as heat transfer fluid in various systems requiring high heat transfer rate e.g. solar thermal conversion systems, HVAC systems, electronic equipment, heat exchangers, nuclear reactors have imparted greater role in reducing negative impacts of climate change. The influence of size, concentration, type and shape of nanoparticles, working temperature, compound passive techniques and magnetic field effect on heat transfer and pressure drop performance of nanofluids are extensively discussed along with the drawbacks of nanofluids such as formation of fouling on heat transfer surfaces. This comprehensive review will be beneficial for engineers, researchers, and academics to commend the significance of various nanofluids and comprehend their remarkable impact on various heat transfer applications.