Animesh Halder

The deteriorating water environment worldwide, mainly due to population explosion and uncontrolled direct disposal of harmful industrial and farming wastes, earnestly demands new approaches and accurate technologies to monitor water quality before consumption overcoming the shortcomings of the current methodologies. A spectroscopic water quality monitoring and early-warning instrument for evaluating acute water toxicity are the need of the hour. In this study, we have developed a prototype capable of the quantification of dissolved organic matter, dissolved chemicals, and suspended particulate matter in trace amounts dissolved in the water. The prototype estimates the water quality of the samples by measuring the absorbance, fluorescence, and scattering of the impurities simultaneously. The performance of the instrument was evaluated by detecting common water pollutants such as Benzopyrene, Crystal Violet, and Titanium di-oxide. The limit of detection values was found to be 0.50, 23.9, and 23.2 ppb (0.29 µM), respectively.

The current COVID-19 pandemic has increased the use of facial masks globally, which of late have registered their presence as a part of our civilization. The N95 mask is one of the most popular choices under the current situation. However, the available masks cannot provide breathing comfort for an extended period, which results in rebreathing of exhaled air that is CO₂ rich, and which remains in the breathing space of the respirator. Furthermore, problems like moisture settlement on the covered area of the face due to the multiple layers of fabric-like material causes significant discomfort. Hence, the need for a mask with an air-purification activity is the need of the hour. The present innovation relates to the invention of a mask that is battery-powered or solar-operated and addresses the aforementioned problems. This mask not only regulates the airflow, which is beneficial to our body in every way, but also lowers the discomfort of sweating and heating. The effect of the addition of the self-developed active respirator to the commercially available masks on the inspired CO₂ level, thermal comfort, and speech clarity has been demonstrated in this study. We have exhibited through in vitro experiments that the filtration capability of the active-respirator improvised mask, we call the Bose shield, does not deter from that of the standard N95 mask. To our understanding, the use of this novel mask can reduce the occurrence of CO₂ rebreathing in respiratory protective devices and its impact on workers who inevitably wear them for a prolonged period of time.

Regular monitoring of electrolyte balance is essential for patients suffering from chronic kidney disease (CKD), particularly those undergoing dialysis. In the context of the recent COVID-19 pandemic, more severe forms of infection are observed in elderly individuals and patients having co-morbidities like CKD. The repeated blood tests for the monitoring of electrolyte balance predispose them not only to COVID-19 but also other to hospital-acquired infections (HAI). Therefore, a non-invasive method for easy detection of essential electrolyte (K⁺ and Na⁺) levels is urgently needed. In this study, we developed an optical emission spectroscopy-based non-invasive device for simultaneous monitoring of salivary Na⁺ and K⁺ levels in a fast and reliable way. The device consisted of a closed spark chamber, micro-spectrometer, high voltage spark generator, electronic circuits, optical fiber, and an indigenously developed software based on the LabVIEW platform. The optical emission originating from the biological sample (i.e., saliva) due to recombination of ions energized by impingement of electrons returning from high voltage spark provides necessary information about the concentration of electrolytes. A small-scale clinical trial on 30 healthy human subjects shows the potential of the indigenously developed device in determining salivary Na⁺ and K⁺ concentration. The low-cost, portable, point-of-care device requires only 2 mL of sample, and can simultaneously measure 1.0–190.0 mM Na⁺, and 1.0–270.9 mM K⁺ . To our understanding, the present work will find its relevance in combating COVID-19 morbidities, along with regular CKD patient-care.

Simultaneous measurement of atmospheric moisture and temperature in the presence of airborne particulates over an extended region using a single sensor is very important for the prediction of fog in an open environment. Here, we have developed an ultrasonic technique to measure relative humidity and temperature of open-air containing suspended particulate matter in a controlled environment. We achieved an accuracy within ±0.9 K for a temperature range of 297–302 K, and within ±2.68% for relative humidity in the range of 60%–100%. We also characterized laboratory-generated fog using ultrasound and found our results to be in agreement with the conventional optical method. At higher concentrations, our technique appears to be a better means of characterizing atmospheric moisture content compared to light.

Objective: Nonthermal plasma at atmospheric condition using dielectric barrier discharge (DBD) is reported to be useful in many applications. Here, we have developed a strategy to generate nonthermal atmospheric plasma (NTAP) at ambient conditions for potential biomedical applications. Methods: We have explored the active ingredients of the nonthermal plasma using atomic emission spectroscopy. The potential mechanism of the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) from the generated plasma for therapeutic use has been demonstrated. Major results: The antimicrobial efficacy of the nonthermal plasma application to model Staphylococcus aureus and Candida albicans biofilms has been investigated. Our detailed electron microscopic studies followed by biochemical investigation reveal the mechanism of bacterial/fungal deactivation process. The nuclear magnetic resonance (NMR) studies on the live cell of C. albicans before and after NTAP treatment clearly conclude the disruption of cellular envelope leading to necrosis as evidenced by fluorescence-assisted cell sorting (FACS) studies. Conclusions: The proposed NTAP setup may find relevance in novel strategies in bacterial and fungal biofilm destruction in the future development of nonfluid hand sanitization.

Riboflavin (RF), commonly known as vitamin B-2, is an essential ingredient in any milk variety of animal origin. The photophysics of the molecule RF, including its interaction with biological macromolecules, are well studied. Here, we have investigated the possibility of the molecule as a potential biomarker of milk quality. We also found omnipresence of this molecule in milk of plant origin (soy milk). Spectroscopic studies on various animal and plant milks of different commercial origins confirmed the potential of RF for use in identifying the quality of the milk varieties. Our developed strategy involved identification or spectroscopic signature of RF by measuring optical density at 365 nm (quality factor 1) and fluorescence intensity around 520 nm (excitation at 365 nm; quality factor 2) on a very small amount of whole milk (10 mu L). We also developed a prototype device called Mil-Q-Way to be used in the real field. The required interfacing software in the LabView platform was also developed. A 2-parameter plot (quality factor 1 on the x-axis and quality factor 2 on the y-axis) called the Mil-Q-Way plot clearly differentiates the quality of milks of different commercial origins. The low-cost device based on simple spectroscopy was shown to screen for the presence of harmful adulterants in drinkable milk.