Photolysis of dinotefuran in aqueous solution: Kinetics, influencing factors and photodegradation mechanism.

The environmental behaviour of neonicotinoid insecticides (NNIs) is of momentous concern due to their frequent detection in aquatic environment and their biotoxicity for non-target organisms. Phototransformation is one of the most significant transformation processes, which is directly related to NNIs exposure and environmental risks. In this study, the photodegradation of dinotefuran (DIN, 1-Methyl-2-nitro-3-(tetrahydro-3-furanylmethyl)-guanidine), one of the most promising NNIs, was conducted under irritated light in the presence of Cl-, DOM along with the effect of pH and initial concentration. The findings demonstrated that in ultra-pure (UP) water, the photolysis rate constants (k) of DIN rose with increasing initial concentration. Whereas, in tap water, at varied pH levels, and in the presence of Cl-, the outcomes were reversed. At the same time, lower concentration of DOM promoted DIN photolysis processes due to the production of reactive oxygen species, while higher concentrations of DOM inhibited the photolysis by the predominance of light shielding effects. The singlet oxygen (1O2) was produced in the photolysis processes of DIN with Cl- and DOM, which was confirmed by electron spin resonance (EPR) analysis. Four main photolysis products and three intermediates were identified by UPLC-Q-Exactive Orbitrap MS analysis. The possible photodegradation pathways of DIN were proposed including the oxidation by 1O2, reduction and hydrolysis after the removal of nitro group from parent compounds. This study expanding our understanding of transformation behavior and fate of NNIs in the aquatic environment, which is essential for estimating their environmental risks.

Phototransformation of halobenzoquinones in aqueous solution under the simulate sunlight: Kinetics, mechanism and products.

Halobenzoquinones (HBQs) are a novel family of unregulated disinfection byproducts (DBPs). Little is known about their phototransformation activities in natural water. Here, five HBQs with various halogenated substituent types, numbers, and structures positions were selected to investigate the kinetics of degradation in aqueous solutions at various concentrations and in the presence of common environmental variables (Cl-, NO2-, and humic acid). The results indicated that dichloride and dibromo-substituted HBQs were photolyzed, whereas tetrachloro-substituted HBQs showed little degradation. The photolysis rate constant (k) of HBQs decreased with increasing initial concentration. The presence of NO2- and Cl- promoted the degradation of HBQs mainly through the formation of hydroxyl radical (•OH), which were confirmed by electron paramagnetic resonance (EPR). In contrast, humic acid played a negative role on HBQs transformation due to the adsorption and quenching reactions. Possible conversion pathways for HBQs were proposed based on the identification of two major photodegradation products, hydroxylated HBQs and halogenated-benzenetriol, as well as reactive free radicals. This study provided meaningful insights into the environmental fates and risk assessments of HBQs in natural aquatic system.

SARS-CoV-2 testing and its role in understanding the evolving landscape of the pandemic in Bangladesh.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is readily transmitted from person to person. We evaluated the emerging landscape of SARS-CoV-2 variants in Bangladesh from a retrospective study of nasopharyngeal swabs collected from 130 SARS-CoV-2-positive cases randomly selected over 6 months. Mutation analysis of whole-genome sequencing of 130 SARS-CoV-2 variants revealed 528 unique coding mutations, of which 102 were deletions, 6 were premature stop codons, and the remaining were substitutions. The most common mutation in the cohort was ORF1b:P314L, with a frequency of 98.5%. A total of 132 unique coding mutations were observed in the spike protein gene. Fourteen mutations were mapped to the spike protein receptor binding domain (RBD). These mutations increase the affinity between the spike protein and its human receptor, angiotensin converting enzyme 2 (ACE2), thereby increasing SARS-CoV-2 transmissibility. This study will help understand the SARS-CoV-2 virus and ultimately aid in monitoring and combatting the COVID-19 pandemic by furthering research on appropriate therapies. Analysis of age revealed closer association of the Delta variant with older populations and of the Omicron variant with younger populations. This may have important implications on how we monitor infections, distribute vaccines, and treat patients based on their ages.

Identifying and comparing the injury severity risk factors on rural freeways in different states in the United States.

This study identifies and compares those risk factors affecting crash injuries and fatalities on rural freeways in Montana and West Virginia in the United States using the mixed logit model. Three-year crashes on rural freeway segments in both states are used. Higher annual average daily traffic (AADT) was associated with a reduction in injuries/fatalities in both states, with higher reduction in West Virginia (40%) than in Montana (25%). In both states, the impact of adverse road surface conditions (i.e., snowy/icy) was associated with a reduction in injuries/fatalities. The results show that separate injury severity models for individual states are suggested instead of lumping all crashes in one model. Enforcement of trucks' risky maneuvers (e.g., illegal traveling in the leftmost lane) and more education for older drivers are suggested in West Virginia. In Montana, it is recommended to monitor rural freeway segments with high sport utility vehicle (SUV) crash history.

Synthesis of a multichannel lattice-form optical delay-line circuit with ring waveguides.

This paper presents a one-input M -output (1 x M) circuit configuration and a synthesis algorithm for realizing an optical infinite impulse response (IIR) lattice filter having M -output channels (M > or =2) .The circuit configuration has a multilayer structure consisting of multiple Mach-Zehnder interferometers with delay time difference of Deltatau. It is a natural extension of the conventional two-port optical IIR lattice circuit (M =2) . Synthesis algorithm is derived to obtain all unknown circuit parameters. The proposed synthesis algorithm is based on factorizations of the paraunitary total transfer matrix. Simulation result demonstrates the effectiveness of the proposed multichannel IIR design scheme. The synthesis algorithm for M - channel IIR filter is considered lossless in this paper, which implies that the filter must be power complementary.