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Tailoring, fine-tuning, and controlling the luminescent behavior and the associated photo-physical properties of fluorophores have been the subject of contemporary research. Over the years, many strategies have been explored to address concerns such as short electronic absorption/luminescence wavelengths, small Stokes shift, low brightness, inapt permeability, poor stability, and low solubility. Among these, approaches involving binary/multi-component systems comprising different functional materials appear to be promising and everlasting. Working on this theme, we report the results of elaborative studies on the fluorescence (photoluminescence, PL) characteristics of several organic/hybrid composites realized by dispersing organic dyes and quantum dots (QDs) in the host columnar liquid crystal (Col LC) exhibiting excited-state intra-molecular proton-transfer (ESIPT) phenomenon. Precisely, the binary mixtures were realized by doping organic dyes such as methyl red/rubrene and carbon QDs/perovskite (CsPbBr3) QDs in fluorescent (ESIPT) Col LC, namely, phasmidic bis(N-salicylideneaniline) (PBSAN-14). The investigations were carried out in three condensed states, viz., solid, LC, and liquid states, and their solutions. The composites derived from organic dyes and Col LC refrain from light emission, implying that the PL of the host is quenched; the Stern–Volmer profiles revealed the combined dynamic and static quenching mechanism. The Col LC-QD composites exhibit intense emission that covers almost the entire visible wavelength region. The CIE chromaticity diagram shows a wide range of color tuning achieved by varying the nature of additives. Thus, this investigation provides a clear insight into the effect of organic dyes and QDs on the condensed states of fluorophores. [ABSTRACT FROM AUTHOR]

In this study, an optical sensor is developed, incorporating hydrogen-bonded photonic array dots containing poly(acrylic acid) (PAA) within a polymer cholesteric liquid crystal interpenetrating polymer network (PCLCIPN) framework, thereby effectively controlling porosity. This methodology involves the fabrication of a porous photonic film, subsequent infusion with a hydrogel (PAA), and precise UV-curing to generate patterned array dots. The sensor exhibits exceptional discriminatory capability between methanol and ethanol, accurately discerning their varying concentrations within alcohol solutions. The optical sensing performance of the film is rigorously evaluated through continuous monitoring of wavelength shifts in the transmission spectrum across various alcohol concentrations. Notably, the observed wavelength shifts demonstrate a linear correlation with the concentration of alcohol, thereby enabling precise quantitative analysis of the alcohol solutions. The sensor exhibits a sensitivity of 0.44 nm/% for ethanol concentrations ranging from 5% to 60%, increasing to 2.1 nm/% for concentrations between 60% and 80%. Similarly, for methanol, sensitivities of 0.68 nm/% (5–60%) and 2.2 nm/% (60–80%) are recorded. Remarkably, this sensitivity trend extends seamlessly to 1 : 1 ethanol/methanol ratios, with values of 0.49 nm/% (5–60%) and 2.25 nm/% (60–80%). Furthermore, these sensors demonstrate colorimetric response to different alcohols, rendering them accessible and cost-effective biosensors for visual detection, thus obviating the necessity for complex analytical instruments. [ABSTRACT FROM AUTHOR]

This research presents a novel patch antenna prototype that operates in the THz range for early detection of malignant cancerous cells. The antenna has dimensions of 100 µm × 100 µm and achieves −27.3 dB return loss at an operating frequency of 2.34 THz. The proposed sensor is optimized for a polyimide substrate with a dielectric constant of 3.5 and thickness of 15.7 µm. The prototype's sensitivity and performance are evaluated by simulating different malignant neoplasms using High-Frequency Simulation Software (HFSS) for five types of breast cancer cells. The results indicate that the variation in resonant frequency and the S21 parameter between malignant cells and healthy breast cells are the primary factors that determine the sensitivity of the prototype. The proposed patch antenna's high sensitivity and low profile make it a promising solution for the early detection and prognosis of cancerous cells. [ABSTRACT FROM AUTHOR]

In late December 2019, a novel coronavirus, COVID −19 originated in Wuhan city of China, and significant improvement in not only the air quality but also the water quality. Therefore, the current study demonstrates the changes in water quality parameters of the Ghaggar river, Punjab, India. The variations in the water quality of the Ghaggar river have been examined during the pre-, during, and post-pandemic periods. The maximum temperature of the Ghaggar river for all monitoring stations was between 28 to 37°C during the pandemic period, whereas the maximum dissolved oxygen value varied from 3 to 7 mg/L. The maximum pH obtained from the monitoring stations was reported to be 7.7 to 8.0, except chhatbir monitoring station (7.6). The maximum biochemical oxygen demand for all monitoring stations was found to be between 18–53 mg/L. Strong positive correlations were observed between total coliform and fecal coliform for pre (0.76) and during (0.89) the pandemic periods. Similar significant positive correlations were recorded between BOD and conductivity for pre (0.75) and during (0.58) pandemic periods. [ABSTRACT FROM AUTHOR]

We represent a detailed study of a dilute suspension of ferroelectric barium titanate nanoparticles (BaTiO3 NPs) in a nematic matrix by probing dielectric, electro-optical, and optical properties. The strong local surface electric field (order of ∼1010 Vm−1) of BaTiO3 produces pseudonematic domains within the matrix, which renders an enhancement in both the perpendicular and parallel components of dielectric permittivity that increases with increasing NP concentrations. Due to changes in molecular ordering, the dielectric anisotropy of pristine nematic increases by 10.7%, 24.6%, and 33.3% after the addition of 0.1, 0.3, and 0.5 wt. % BaTiO3 NPs with subsequent lowering in threshold voltage. Interestingly, the nematic-BaTiO3 blended cells showed 23.2%, 49.3% and 67.6% faster electro-optic response for 0.1, 0.3, and 0.5 wt. % of NPs, respectively. In the nematic matrix, BaTiO3 NPs act like chromophores resulting in a bathochromic shift in fluorescence spectra due to an enhanced degree of conjugation. This investigation reveals that the ferroelectric BaTiO3 NPs-nematic composites will be suitable for superior fluorescent electro-optical devices. [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic, governments in many countries worldwide, including India, imposed several restriction measures, including lockdowns, to prevent the spread of the infection. COVID-19 lockdowns led to a reduction in gaseous and particulate pollutants in ambient air. In the present study, we investigated the substantial changes in selected volatile organic compounds (VOCs) after the outbreak of the coronavirus pandemic and associations with health risk assessments in industrial areas. VOC data from 1 January 2019 to 31 December 2021 were collected from the Central Pollution Control Board (CPCB) website, to identify percentage changes in VOC levels before, during, and after COVID-19. The mean TVOC levels at all monitoring stations were 47.22 ± 30.15, 37.19 ± 37.19, and 32.81 ± 32.81 µg/m3 for 2019, 2020, and 2021, respectively. As a result, the TVOC levels gradually declined in consecutive years due to the pandemic in India. The mean TVOC levels at all monitoring stations declined from 9 to 61% during the pandemic period as compared with the pre-pandemic period. In the current study, the T/B ratio values ranged from 2.16 (PG) to 26.38 (NL), which indicated that the major pollutant contributors were traffic and non-traffic sources during the pre-pandemic period. The present findings indicated that TVOC levels had positive but low correlations with SR, BP, RF, and WD, with correlation coefficients (r) of 0.034, 0.118, 0.012, and 0.007, respectively, whereas negative correlations were observed with AT and WS, with correlation coefficients (r) of −0.168 and −0.150, respectively. The lifetime cancer risk (LCR) value for benzene was reported to be higher in children, followed by females and males, for the pre-pandemic, pandemic, and post-pandemic periods. A nationwide scale-up of this study's findings might be useful in formulating future air pollution reduction policies associated with a reduction in health risk factors. Furthermore, the present study provides baseline data for future studies on the impacts of anthropogenic activities on the air quality of a region. [ABSTRACT FROM AUTHOR]