Development of Zinc Oxide Sensors for Detecting Ammonia Gas in the Ambient Air: A Critical Short Review

Ammonia (NH₃) is emitted into the atmosphere by various industries and other sources and causes environmental pollution. Considering the hazards of ammonia, detecting leakage from vessels and pipes demands the use of sensors. Therefore, the development of NH₃ gas sensors assumes considerable importance to researchers and regulators and to industry, businesses, and facilities that make, store, or use ammonia. The use of metal oxide sensors (MOS) for detecting NH₃ gas, such as zinc oxide (ZnO), has been a topic of interest to researchers seeking methods to detect NH₃ gas, even at low concentrations. In this article, an attempt has been made to review the research thus far published on the synthesis of ZnO‐based NH₃ gas sensor materials, their characterization, and analyses of their performance. Finally, we make several recommendations regarding the scope of future research. For example, the kinetics of the sensor materials should be determined. Furthermore, extensive studies of gas–solid (NH₃–ZnO) adsorption are proposed to ascertain the exact adsorption mechanism in terms of isotherm, kinetics, and diffusive mass transport, and to determine “reversibility” and “recovery” of sensor materials so they can continue sensing and activating alarms when necessary for practical applications.     

The viral phoenix: enhanced infectivity and immunity evasion of SARS-CoV-2 variants

SARS-CoV-2 pandemic continues with emergence of new variants of concerns. These variants are fueling the third and fourth waves of pandemic across many nations. Here we describe the new emerging variants of SARS-CoV-2 and why they have enhanced infectivity and possess the ability to evade immunity.

     

Microplastic pollution,a threat to marine ecosystem and human health: a short review

Human populations are using oceans as their household dustbins, and microplastic is one of the components which are not only polluting shorelines but also freshwater bodies globally. Microplastics are generally referred to particles with a size lower than 5 mm. These microplastics are tiny plastic granules and used as scrubbers in cosmetics, hand cleansers, air-blasting. These contaminants are omnipresent within almost all marine environments at present. The durability of plastics makes it highly resistant to degradation and through indiscriminate disposal they enter in the aquatic environment. Today, it is an issue of increasing scientific concern because these microparticles due to their small size are easily accessible to a wide range of aquatic organisms and ultimately transferred along food web. The chronic biological effects in marine organisms results due to accumulation of microplastics in their cells and tissues. The potential hazardous effects on humans by alternate ingestion of microparticles can cause alteration in chromosomes which lead to infertility, obesity, and cancer. Because of the recent threat of microplastics to marine biota as well as on human health, it is important to control excessive use of plastic additives and to introduce certain legislations and policies to regulate the sources of plastic litter. By setup various plastic recycling process or promoting plastic awareness programmes through different social and information media, we will be able to clean our sea dustbin in future.     

Isolation and characterization of a profenofos degrading bacterium

Profenofos, a well known organophosphate pesticide, has been in agricultural use over the last two decades for controllingLepidopteron pests of cotton and tobacco crops. In this study, a bacterial strain, OW, was isolated from a long term profenofos exposedsoil by an enrichment technique, and its ability to degrade profenofos was determined using gas chromatography. The isolated strainOW was identified as Pseudomonas aeruginosa according to its physiological and biochemical properties, and the analysis of its 16SrRNA gene sequence. The strain grew well at pH 5.5–7.2 with a broad temperature profile. Bioremediation of profenofos-contaminatedsoil was examined using soil treated with 200 g/g profenofos, which resulted in a higher degradation rate than control soils withoutinoculation. In a mineral salt medium (FTW), removal in the level of profenofos of 86.81% was obtained within 48 h of incubation.The intermediates of profenofos metabolism indicated that the degradation occurred through a hydrolysis mechanism, and one of themetabolites was found to be 4 bromo-2-cholorophenol (BCP) which in turn was also mineralized by the strain. The results of this studyhighlighted the potentiality of P. aeruginosa as a biodegrader which could be used for the bioremediation of profenofos contaminatedsoil.     

Low concentration of HgCl2 drives rat hepatocytes to autophagy/apoptosis/necroptosis in a time-dependent manner

Mercury (Hg) is known to produce hepatotoxicity driving cells towards apoptosis. It was recently reported that low concentrations of Hg (5 μM) initiate autophagy in vitro within 30 min of incubation modulated by several autophagy-related gene proteins, and co-regulators through ubiquitination. The present study aimed to elucidate in vitro mode of cytotoxic responses including programed cell death in 5-μM Hg-treated rat hepatocytes. Autophagy proceeded from 30 min to 4 hr mediated by crosstalk between specific regulating factors of cell-death-signaling mechanisms. It was noted that after 4-hr incubation with 5 μM HgCl₂, cells were driven towards apoptosis followed by necroptosis within 6.5 hr. Receptor-interacting serine-threonine protein 3 (RIP3) and caspase-8 played a significant role in interlinking function. The positive role of caspase-8 with RIP3 significantly triggered caspase-3 via extrinsic apoptotic pathway. A shift from apoptosis to necroptosis occurred after 6 hr via tumor necrosis factor α-RIP3-caspase-8 pathway. No alteration in caspase-3 expression and presence of high-mobility group box 1 protein in nucleus indicated absence of apoptosis and necrosis in rat hepatocytes between 6.5 and 8 hr. Data indicated that cellular homeostasis is regulated by modulating different proteins and driving hepatocytes through autophagy to apoptosis to necroptosis in a time-dependent manner.