An organo-photocatalyzed visible-light-driven multi-component approach for carbothioaryl/alkylation of activated alkenes via C(sp3)-H bond functionalization.

A visible-light-driven organophotocatalyzed multi-component approach for carbothiolation of activated alkenes is demonstrated under environmentally benign and redox-neutral conditions, involving direct C(sp3)-H functionalization followed by electrophilic alkyl/arylthiolation. The three-component difunctionalization reaction is a complete transition-metal and peroxide-free process conducted under milder conditions. In this composite reaction, by employing bench-stable reagents, the formation of two new C(sp3)-C(sp3) and C(sp3)-S bonds is achieved for a wide variety of substrates, showcasing the excellent functional group tolerance and chemoselectivity of the methodology. Furthermore, the scalability and utilization of natural sunlight instead of artificial blue LEDs, along with the use of an inexpensive and easy-to-prepare pyrylium salt as an organo-photocatalyst, make this protocol greener and more energy efficient.

Prevalence and associated factors of diabetic retinopathy among people with diabetes screened using fundus photography at a community diabetic retinopathy screening program in Nepal.

BACKGROUND: This study aimed to assess the prevalence and associated factors of diabetic retinopathy (DR) and vision threatening DR (VTDR) among people with diabetes screened using fundus photography in Nepal. METHODS: This is a retrospective study among people with diabetes presented for DR screening using fundus photography from 2013 to 2019. Detailed demographics, duration of diabetes, medical history, visual acuity, and grading of DR on fundus photography were analyzed. Fundus camera used in the study were;Topcon digital fundus camera 900 CXR and digital portable fundus cameras (Nidek-10 portable non-mydriatric fundus camera; Versacam & Trade & Alpha, France), and a Zeiss portable fundus camera (Zeiss Visucout 100). Macula centred and disc centred 45 degree two images were taken from each eye. Pupil were dilated in cases where there was media haze in un-dilated cases. DR was graded using early treatment diabetic retinopathy study criteria. The images were graded by fellowship trained retina specialist. DR prevalence included any DR changes in one or both eyes. RESULTS: Total of 25,196 patients with diabetes were enrolled. Mean age was 54.2 years with Standard Deviation (S.D):12.9 years, ranging from 6 years to 97 years. Type 1 and type 2 diabetes comprised of 451 people (1.79%) and 24,747 (98.21%) respectively. Overall, 1.8% of the images were un-gradable. DR prevalence was 19.3% (95% Confidence Interval (CI): 18.8 - 19.7%). DR prevalence in type 1 and type 2 diabetes was 15.5% (95% CI: 12.5 - 18.6%) and 19.3% (CI: 18.8 - 19.8%) respectively. Clinically significant macular edema (CSME) was found in 5.9% (95% CI: 5.6-6.2%) and VTDR in 7.9% (95% CI: 7.7-8.3%). In multivariate analysis, our study revealed strong evidence to suggest that there is meaningful association between DR and VTDR with duration of diabetes, diabetic foot, diabetic neuropathy, agriculture occupation, those under oral hypoglycaemic agents or insulin or both as compared to those under diet only, and presenting visual acuity > 0.3LogMAR. CONCLUSION: Prevalence and associated factors for DR and VTDR were similar to other DR screening programs in the region. Emphasis on wider coverage of DR screening could help for timely detection and treatment of STDR to avoid irreversible blindness.

Bilateral sixth nerve palsy with subdural hematoma: a unique presentation of B12 deficiency.

Vitamin B12 is inextricably associated with the development and maintenance of neuronal functions. It is classically associated with subacute combined degeneration and peripheral neuropathy; however, cranial neuropathy is uncommon. We observed the rarest neurological manifestation of B12 deficiency. A 12 months infant had history of lethargy, irritability, anorexia, paleness, vomiting, and neurodevelopmental delay for 2 months. He also developed inattention and altered sleep pattern. His mother noticed bilateral inward rotation of both eyes. On examination, the infant had bilateral lateral rectus palsy. The infant was found to have anemia (7.7g/dL) and severe B12 deficiency (74pg/mL). On MRI, there was cerebral atrophy, subdural hematoma (SDH) and wide cisternal spaces and sulci. On supplementation with cobalamin, he improved clinically though mild restriction of lateral gaze on the left side persists. Follow up MRI showed significant improvement in cerebral atrophy with resolution of SDH. To date, such clinical presentation of B12 deficiency has never been reported. The authors suggest B12 supplementation for at risk population esp at antenatal stage and lactating mothers in national programs. The treatment of this condition should be initiated early to prevent long term sequelae.

Influence of gender and oral health knowledge on DMFT index: a cross sectional study among school children in Kaski District, Nepal.

BACKGROUND: Oral health problems are highly prevalent among school children in Nepal. Poor oral health condition may be influenced by various factors. However, little is known about the sociodemographic and awareness related factors on oral health problems among school children in Nepal. Therefore, this study aimed to assess the association of gender and knowledge on DMFT index among school children. METHODS: A cross-sectional study was conducted among school children of Grade Seven in 12 schools of Kaski district in Nepal. Schools were randomly selected from the urban and semi-urban areas in the district. Data were collected covering oral health knowledge, socio-demographic characteristics, oral health condition and practices. The factors of poor oral health condition and practices were examined using t-test, one-way ANOVA, and multiple linear regression. RESULTS: Of the total participants (n = 669), 54.9% were females and their mean DMFT score was 1.82 (SD = 1.07). Total decayed score was higher among those who did not have knowledge that fluoride prevents decay compared to those who had knowledge about it (Being aware of fluoride prevents decay: Mean = 1.21 (SD = 1.54) versus not being aware of that: mean = 2.13 (SD = 2.13); p = 0.029). Females were more likely to have higher DMFT scores compared to males (ß-coefficient = 0.43, 95% CI 0.13, 0.73, p = 0.005). In addition, higher knowledge score was negatively associated with higher DMFT score (ß-coefficient = - 0.09, 95% CI - 0.20, -0.01, p = 0.047). CONCLUSION: Being female students and those having lower level of knowledge on oral health attributed to higher DMFT index. Periodic dental check-up coupled with oral health education on regular brushing, use of fluoridated paste, tongue cleaning and care of gum diseases are recommended in schools.

Visible light photocatalytic degradation of methylene blue and rhodamine B over silver-doped titanium dioxide nanocomposites supported on Fuller's earth.

Silver-doped-titanium dioxide nanoparticles supported on Fuller's earth, prepared by the sol-gel method, were characterized with XRD, TGA, zeta potential, SEM, EDX, TEM, XPS, photoluminescence and UV-DRS measurements. The material, Ag-TiO2-Fuller's earth (AgTF), was tested for photocatalytic activity concerning the degradation of rhodamine B (RhB) and methylene blue (MB) in aqueous solution under visible light irradiation with pH, catalyst dosage, and dye concentration as the process variables. The degradation kinetics indicated pseudo-first-order kinetics with rate constant of (i) 0.55 min-1with 0.12 gL-1AgTF loading, 10-5 M MB at pH 9, and (ii) 0.53 min-1 with 0.08 g L-1 AgTF loading, 5 × 10-5 M RhB at pH 8. The methylene blue degradation was maximum (98.66%) for AgTF loading of 0.12 g L-1 while the maximum RhB degradation (96.34%) was attained with AgTF loading of 0.08 g L-1. With 5 × 10-6M MB concentration, the degradation achieved was 98% in 45 min and 100% in 60 min. One hundred per cent degradation of the dye, RhB (1 × 10-6 M) could be achieved in 30 min with 0.08 g L-1 AgTF at pH 8. The use of Fuller's earth, a cheap, abundant and large surface area support, increases the adsorbability of the dye on the catalyst surface and hence promotes the degradation. The catalyst could be removed easily from the reaction mixture and reused for up to five cycles without any significant decrease in activity. Scavengers such as triethanolamine (TEOA), p-benzoquinone (BQ) and isopropyl alcohol (IPA) were utilized to get some insight into the photocatalysis mechanism.

Pathogenesis of Aeromonas caviae in Clariasmagur.

Aeromonas spp. is a pathogenic bacteria that potentially cause infection in farmed fish, including Catfishes. In the present study, dominant bacteria were isolated from diseased Clarias magur and tentatively named BLBM-05. Based on morphological, physiological, and biochemical features as well as 16S rRNA gene sequence and gyrB gene sequences (Gen Bank accession number: MT973994.1 and MZ398017.1), the bacteria in the isolate was found to be Aeromonas caviae. Further, the isolate was screened for five known virulence genes, namely ß-hemolysin, lafA, exu, ompA1 and ascV. Among them, three virulence genes related to pathogenicity, including aerolysin (aer), outer membrane protein (ompA1), lateral flagella (lafA), were identified in the A. caviae isolate. The median lethal dosage (LD50) of the BLBM-05 isolate for magur was determined as 1.53x106 CFU/mL. The histopathological analysis showed that the BLBM-05 isolate induced considerable histological lesions in the magur fish, including necrosis, hemolysis of erythrocytes, myolysis, hemorrhage, and desquamation in the intestinal tissue, tissue loosening, and infiltration of inflammatory cells. Drug sensitivity test showed that the isolate was susceptible to Gentamicin, Ceftazidine, Ceftrioxone, Amikacin, Tetracycline, Meropener and Oxytetracycline. The present results provide a scientific basis to identify A. caviae further, a line of treatment for magur infected by this pathogen.

Visible-Light-Driven Organophotocatalyzed Multicomponent Approach for Tandem C(sp3)-H Activation and Alkylation Followed by Trifluoromethylthiolation.

A visible-light-driven organophotocatalyzed multicomponent approach has been developed for tandem direct C(sp3)-H activation and alkylation followed by trifluoromethylthiolation in a one-pot operation. We report a completely metal-free, tandem, three-component approach for the difunctionalization of activated alkenes via the photoinduced radical pathway. This protocol allows the formation of two new C(sp3)-C(sp3) and C(sp3)-SCF3 bonds using a bench-stable, easy-to-handle trifluoromethylthiolating reagent under mild reaction conditions. The generosity of this reaction is shown with a library of C(sp3)-H donors and alkenes derivatives. The reaction conditions can tolerate a wide variety of functional groups. Gram-scale synthesis using environmentally benign and straightforward conditions highlights the synthetic advancement of the methodology. Further functionalization of the final product is also successfully demonstrated.

Appraising the potency of small molecule inhibitors and their graphene surface-mediated organizational attributes on uric acid-melamine clusters.

Uric acid (UA) and melamine (MM) crystallization in humans is associated with adverse medical conditions, including the germination of kidney stones, because of their low solubility. The growth of kidney stones, usually formed on renal papillary facades, is accomplished on the matrix-coated surface by the aggregation of preformed crystals or secondary crystal nucleation. Therefore, the effects of inhibitors such as theobromine (TB) and allopurinol (AP) on MM-UA aggregation are investigated by employing classical molecular dynamics simulations on a graphene surface. This impersonates the exact essence of the precipitation of kidney stones. The interaction between MM-UA is very intense and, thus, large clusters are formed on the surface. The presence of TB and AP will, however, substantially inhibit their aggregation. TB and AP significantly impede UA aggregation in particular. Therefore, lower order UA clusters are formed. These smaller UA clusters then pull a lower number of MM towards themselves, resulting in a smaller order UA-MM cluster. MM and UA aggregation on a 2D graphene surface is found to be spontaneous. There is no difference in these molecules' adsorption with a change in the force field parameters (i.e., GAFF and OPLS-AA) for graphene. Moreover, the greater the surface area of graphene, the more molecules are absorbed. The solute-surface van der Waals interaction energy plays a driving force in the adsorption of solute molecules on the surface. In addition, interactions like hydrogen bonding and π-stacking over the graphene surface involve binding all like molecules. These aggregated solute molecules strongly attract more like molecules until all solute molecules are adsorbed on the graphene surface, as estimated by enhanced sampling. The molecular origin of graphene exfoliation by MM is also described here. The present work helps to design novel kidney stone inhibitors.

Effect of strontium doping on the electrochemical pseudocapacitance of Y1-xSrxMnO3-δ perovskites.

Grid-scale bulk energy storage solutions are needed to utilize the full potential of renewable energy technologies. Pseudocapacitive electrochemical energy storage can play a vital role in developing efficient energy storage solutions. The use of perovskites as anion intercalation-type pseudocapacitor electrodes has received significant attention in recent years. In this study, Sr-doped YMnO3i.e. Y1-xSrxMnO3-δ perovskite was prepared by the solid-state ceramic route and studied for electrochemical pseudocapacitance in aqueous KOH electrolyte. Microstructures, morphologies, and electrochemical properties of these materials were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance method. The formation of the mostly cubic phase, with 50% strontium doped YMnO3 (YSMO-50) provides an equivalent three-dimensional network and superior conductivity due to Mn3+-O2--Mn4+ hopping conduction. YSMO-50 exhibited low intrinsic resistance, 1.45 Ω cm-2, and the highest specific capacity, 259.83 F g-1 at a current density of 1 A g-1 in 2 M KOH aqueous electrolyte. Redox-mediated interconversion of oxide to hydroxide (M2+O2- + H2O + e- ↔ M+OH- + OH-) in aqueous media is shown to be the reason behind the high capacitance of YSMO-50. The excellent electrochemical performance of YSMOs was attributed to the reversible interconversion of oxide-ion into hydroxide ion coupled with surface redox reaction of Mn2+/Mn3+ and Mn3+/Mn4+ occurring during the charge-discharge process. The maximum energy density of 65.13 W h kg-1 was achieved at a power density of 0.45 kW kg-1 for an asymmetric mode, in which YSMO serves as a negative electrode and Activated carbon (AC) as a positive electrode in the PVA-KOH gel electrolyte. Our study reveals that the doping of low valence atom (Sr) at the A-site in perovskite manganites (YMnO3) may be an effective tool to enhance the pseudocapacitive performance of perovskite-based electrodes.

Effect of Dietary Lipid Level on Growth Performance, Body Composition, and Physiometabolic Responses of Genetically Improved Farmed Tilapia (GIFT) Juveniles Reared in Inland Ground Saline Water.

A 60-day feeding trial was carried out to determine the effect of dietary lipid levels on growth and physiometabolic responses to optimize the dietary lipid requirement for maximizing the growth of Genetically Improved FarmedTilapia (GIFT) juveniles reared in inland ground saline water (IGSW) of medium salinity (15 ppt). Formulation and preparation of seven heterocaloric (389.56-449.02 Kcal digestible energy/100 g), heterolipidic (40-160 g/kg), and isonitrogenous (410 g/kg crude protein) purified diets were done for conducting the feeding trial. Random distribution of 315 acclimatized fish (mean weight 1.90 ± 0.01 g) was made in seven experimental groups such as CL4 (40 g/kg lipid), CL6 (60 g/kg lipid), CL8 (80 g/kg lipid), CL10 (100 g/kg lipid), CL12 (120 g/kg lipid), CP14 (140 g/kg lipid), and CL16 (160 g/kg lipid) with 15 fish per triplicate tank (fish density, 0.21 kg/m3). Respective diets were used for feeding the fish at satiation level three times daily. Results indicated that weight gain percentage (WG%), specific growth rate (SGR), protein efficiency ratio, and protease activity significantly increased up to 100 g lipid/kg fed group, and then the values significantly decreased. Muscle ribonucleic acid (RNA) content and lipase activity were highest in 120 g/kg lipid-fed group. RNA/DNA (deoxyribonucleic acid) and serum high-density lipoproteins levels of 100 g/kg lipid-fed group were significantly higher than 140, and 160 g/kg lipid-fed groups. The lowest feed conversion ratio was found in the 100 g/kg lipid-fed group. The amylase activity was significantly higher in 40 and 60 g lipid/kg fed groups. The whole-body lipid level was increased with increasing the dietary lipid levels, whereas, there was no significant difference in whole-body moisture, crude protein, and crude ash contents of all groups. Highest serum glucose, total protein and albumin, and albumin to globulin ratio and lowest low-density lipoproteins level were found in 140 and 160 g/kg lipid-fed groups. Serum osmolality and osmoregulatory capacity did not vary significantly, whereas carnitine palmitoyltransferase-I and glucose-6-phosphate dehydrogenase showed an increased and decreased trend, respectively, with the increasing dietary lipid levels. According to second-order polynomial regression analysis based on WG% and SGR, the optimum dietary lipid for GIFT juveniles in IGSW of 15 ppt salinity was found to be 99.1 and 100.1 g/kg, respectively.

Underlying Mechanisms of Allopurinol in Eliminating Renal Toxicity Induced by Melamine-Uric Acid Complex Formation: A Computational Study.

Using molecular dynamics, we address uric acid (UA) replacement by a model small-molecule inhibitor, allopurinol (AP), from its aggregated cluster in a columnar fashion. Experimentally it has been affirmed that AP is efficient in preventing UA-mediated renal stone formation. However, no study has presented the underlying mechanisms yet. Hence, a theoretical approach is presented for mapping the AP, which binds to melamine (MM) and UA clusters. In AP's presence, the higher-order cluster of UA molecules turns into a lower-order cluster, which "drags" fewer MM to them. Consequently, the MM-UA composite structure gets reduced. It is worth noting that UA-AP and AP-MM hydrogen-bonding interactions often play an essential role in reducing the UA-MM cluster size. Interestingly, an AP around UA makes a pillar-like structure, confirmed by defining the point-plane distribution function. The decomposition of the preferential interaction by Kirkwood-Buff integral into different angles like 0°-30°, 30°-60°, and 60°-90° firmly establishes the phenomenon mentioned above. However, the structural order for such π-stacking interactions between AP and UA molecules is not hierarchical but rather more spontaneous. The driving force behind UA-AP-MM composite formation is the favorable complexation energy that can be inferred by computing pairwise binding free energies for all possible combinations. Performing enhanced sampling and quantum calculations further confirms the evidence for UA degradation.

Role of Hydrotropes in Sparingly Soluble Drug Solubilization: Insight from a Molecular Dynamics Simulation and Experimental Perspectives.

Drug molecules' therapeutic efficacy depends on their bioavailability and solubility. But more than 70% of the formulated drug molecules show limited effectiveness due to low water solubility. Thus, the water solubility enhancement technique of drug molecules becomes the need of time. One such way is hydrotropy. The solubilizing agent of a hydrophobic molecule is generally referred to as a hydrotrope, and this phenomenon is termed hydrotropy. This method has high industrial demand, as hydrotropes are noninflammable, readily available, environmentally friendly, quickly recovered, cost-effective, and not involved in solid emulsification. The endless importance of hydrotropes in industry (especially in the pharmaceutical industry) motivated us to prepare a feature article with a clear introduction, detailed mechanistic insights into the hydrotropic solubilization of drug molecules, applications in pharma industries, and some future directions of this technique. Thus, we believe that this feature article will become an adequate manual for the pharmaceutical researchers who want to explore all of the past perspectives of the hydrotropic action of hydrotropes in pharmaceutics.

Visible-Light-Driven Organophotocatalyzed Mono-, Di-, and Tri-C(sp3)-H Alkylation of Phosphoramides.

A photocatalytic metal-free, visible-light-driven, highly atom-economic, direct multiple α-C(sp3)-H alkylation of phosphoramides and thiophosphoramides is demonstrated under environmentally benign conditions. Economically viable and commercially available Eosin-Y is used as an HAT photocatalyst for mono-α-C(sp3)-H alkylation of phosphoramide derivatives. Remarkably, di- and tri-C(sp3)-H alkylation of phosphoramides and thiophosphoramides using an acridinium photocatalyst is reported with good yield and selectivity. Mechanistic studies reveal that monoalkylation of phosphoramides by Eosin-Y follows the HAT mechanism, whereas di- and tri-C(sp3)-H alkylation by the acridinium photocatalyst follows the SET mechanism.

The miscibility and solubility of uric acid and vitamin C in the solution phase and their structural alignment in the solid-liquid interface.

The crystallization of uric acid (UA) in humans is correlated with unpropitious medical predicaments, including gout and kidney stone germination. Its comparatively low solubility in physiological solutions is a significant contributory factor to UA biomineralization. The inhibition of UA aggregation is investigated as a reasonable approach for reducing kidney and gout-related problems. Therefore, we examine the role of vitamin C (Vit-C), a water-soluble vitamin, in the aggregation of UA, and its potency in solubilizing UA has been confirmed experimentally. We notice that Vit-C encapsulates the aggregated UA. Moreover, it can dismantle the assemblies of UA. We have proffered comprehensive molecular mechanisms of the interplay between the aggregated UA and Vit-C. Vit-C molecules are interspersed in solution due to its non-aggregating nature. We perceive that, through hydrogen bonding and aromatic stacking interactions, Vit-C molecules interact with UA molecules. The determination of the Flory-Huggins interaction parameters suggests that the presence of Vit-C enhances the solubility of UA aggregates. In addition, UA molecules are conformed on a monolayer graphene sheet, where they are assembled to create a 2D self-assembly. Vit-C, however, encapsulates and disseminates itself within the aggregated UA molecules on the surface. Therefore, the molecular mechanisms of the impact of Vit-C on UA aggregation can provide relevant insights into drug design against chronic diseases.

Tracing land use and land cover change in peri-urban Delhi, India, over 1973-2017 period.

Land use and land cover changes over 1973-2017 period in peripheral Delhi were mapped based on digital classification of satellite data and their driving forces ascertained. Urban area expanded and agricultural area diminished at annual rates of 38.6% and 2.1%, respectively, during the 1973-2017 period. Urban expansion occurred more in scrub and sparse vegetation areas than in cultivated lands or ponds. Loss of cultivated land happened mostly due to abandonment of cropping and tree planting in farmhouses developed by the urban elites. Improvement in the state of forests in terms of their expansion as well as densification offsets their loss due to urbanisation, encroachment and logging. The increment in the green cover was due to strict enforcement of compensatory afforestation/forest conservation law, growing demand of ecotourism, emergence of tree-clad farmhouses and increased environmental awareness and surveillance. This research will help in comprehending policies favouring sustainable urban development.

Antibacterial and antioomycete activities of a novel designed RY12WY peptide against fish pathogens.

In the present study, we have designed and synthesized a short compositionally simple peptide RY12WY having potent antimicrobial activity. The molecular docking study results showed that peptide has a strong affinity towards two protein targets of A. sobria; aerolysin and outer membrane protein (OMP). The MIC values ranged from 0.98 to 500 µM and MBC values ranged from 4 to 650 µM against the selected bacterial and fungal pathogens. The intense antimicrobial activity of RY12WY is reported against A. sobria, A. hydrophila, E. tarda, S. aureus, V. parahaemolyticus, P. aeruginosa and E.coli at low concentration.The peptide also showed good activity against A. salmonicida and S. parasitica zoospores. The peptide retained its antimicrobial activity at higher temperatures. Besides, it was active in the presence of physiological salts and serum.The peptide showed negligible haemolytic activity at 125 µM and HC50 was found to be 1437.10 µM. The DNA binding assay indicated that peptide can bind with the genetic material of the bacteria and may inhibit its replication. The bacterial viability assay reported that the peptide interferes with bacterial membrane integrity. To conclude, the results suggest that RY12WY could be a promising therapeutic agent in aquaculture and has possible application in food processing industry which warrants higher temperatures.

Switching of Self-Assembly to Solvent-Assisted Assembly of Molecular Motor: Unveiling the Mechanisms of Dynamic Control on Solvent Exchange.

Natural biological molecular motors are capable of performing several biological functions, such as fuel production, mobility, transport, and many other dynamic features. Inspired by these biological motors, scientists effectively synthesized artificial molecular motors to mimic several biological functionalities. Several molecular systems, from sensitive materials to molecular motors, are essential for controlling dynamic processes in larger assemblies. In this work, we discuss the self-assembly of molecular motors in water and how this self-assembly switches to the solvent-assisted assembly as solvent changes to a water-THF (tetrahydrofuran) mixture. We present an elaborate description of the morphological changes of molecular motor assemblies from pure water to a water-THF mixture to pure THF. Under the influence of THF solvent, molecular motors form an assembled structure by taking a sufficient number of THF molecules in between themselves, resulting in an assembled molecular motor with a softened core. So, molecular motor assembly swells in the water-THF mixture, and in pure water, it shrinks. This solvent-assisted assembled structure has a specific shape. We have confirmed this assembly as a solvent-assisted assembly with the help of molecular dynamics simulation and quantum chemical analysis. Molecular motor-THF and THF-THF interactions are the main responsible interactions for solvent-assisted assembly over self-assembly. This work is a perfect example of conversion between self-assembly (shrinking) and solvent-assisted assembly (swelling) of molecular motors by adding THF into water or vice versa. A spectacular check on the shrinking and swelling by merely altering solvents illustrates so many intriguing possibilities for an alteration of dynamic processes at the nanoscale.

Ammonium Chloride-Mediated Trifluoromethylthiolation of p-Quinone Methides.

Ammonium chloride-mediated trifluoromethylthiolation of p-quinone methides is reported using inexpensive and bench stable AgSCF3 as a nucleophilic trifluoromethylthiolating (-SCF3) reagent. This method is an efficient strategy for the construction of the benzylic C(sp3)-SCF3 bond to synthesize trifluoromethylthio-diarylmethane derivatives by 1,6-conjugate addition/aromatization under mild reaction conditions without any metal catalyst, oxidants, or additives. This is the first report of trifluoromethylthiolation of p-quinone methides. In addition, di-trifluoromethylthiolation of δ-chloro-p-quinone methide and scalability are demonstrated.

Investigation on the Mechanisms of Synchronous Interaction of K3Cit with Melamine and Uric Acid That Avoids the Formation of Large Clusters.

Uric acid (UA) has an enormous competence to aggregate over melamine (Mel), producing large UA clusters that "drag" Mel toward them. Such a combination of donor-acceptor pairs provides a robust Mel-UA composite, thereby denoting a high complexity. Thus, a straightforward but pragmatic methodology might indeed require either destruction of the aggregation of UA or impediment of the hydrogen-bonded cluster of Mel and UA. Here, potassium citrate (K3Cit) is used as a potent inhibitor for a significant decrease of large UA-Mel clusters. The underlying mechanisms of synchronous interactions between K3Cit and the Mel-UA pair are examined by the classical molecular dynamics simulation coupled with the enhanced sampling method. K3Cit binds to the Mel-UA pair profoundly to produce a Mel-UA-K3Cit complex with favorable complexation energy (as indicated by the reckoning of pairwise ΔGbind° employing the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method). The strength of interaction follows the order UA-K3Cit > Mel-K3Cit > Mel-UA, thus clearly demonstrating the instability caused by upsetting the π-stacking of UA and hydrogen bonding of Mel-UA simultaneously. The comprehensive, strategically designed "direct approach" and "indirect approach" cluster structure analysis shows that K3Cit reduces the direct approach Mel-UA cluster size significantly irrespective of ensemble variation. Furthermore, the estimation of potentials of mean force (PMFs) reveals that the (UA)decamer-Mel interaction prevails over (UA)tetramer-Mel. The dynamic property (dimer existence autocorrelation functions) proves the essence of dimerization between Mel and UA in the absence and presence of K3Cit. Moreover, the calculation of the preferential interaction parameter provides the concentration at which Mel-K3Cit and UA-K3Cit interactions are predominant over the interaction of Mel and UA.

Short-term exposure to ambient air quality of the most polluted Indian cities due to lockdown amid SARS-CoV-2.

Air pollution has happened to be one of the mounting alarms to be concerned with in many Indian cities. COVID-19 epidemic endow with a unique opportunity to report the degree of air quality improvement due to the nationwide lockdown in 10 most polluted cities across the country. National Air Quality Index (NAQI) based on continuous monitoring records of seven criteria pollutants (i.e. common air pollutants with known health impacts e.g. PM10, PM2.5, CO, NO2, SO2, NH3 and O3) for a total of 59 stations across the cities, satellite image derived Aerosol Optical Depth (AOD) and few statistical tools are employed to derive the outcomes. NAQI results convey that 8 cities out of the 10 air quality restored to good to satisfactory category during the lockdown period. Within week+1 of the lockdown period, PM10 and PM2.5 concentrations have suppressed below the permissible limit in all cities. CO and NO2 have reduced to about -30% and -57% respectively during the lockdown period. Diurnal concentrations of PM10 and PM2.5 have dropped drastically on the very 4th day of lockdown and become consistent with minor hourly vacillation. In April 2020 the AOD amount was reduced to about 36% and 18% in contrast to April 2018 and April 2019 respectively. This add-on reporting of the possible recovery extent in air quality may help to guide alternative policy intervention in form of short term lockdown so as to testify whether this type of unconventional policy decisions may be put forward to attain a green environment. Because, despite numerous restoration plans, air pollution levels have risen unabated in these cities. However, detailed inventory needs to be focused on identifying the localized pollution hotspots (i.e. source contribution).