CuBr(PPh3)3] for azide-alkyne cycloaddition reactions under strict Click conditions

A careful methodological study revealed a true Click catalytic system based on commercially available [CuBr(PPh(3))(3)]. This system is active at room temperature, with 0.5 mol % [Cu] (or less), in the absence of any additive, and it does not require any purification step to isolate pure triazoles.     

Radon exhalation studies in an Indian uranium tailings pile

A study was taken up to quantify the source term arising due to radon exhalation from Uranium(U) tailings pile at Singbhum shear zone in Jharkhand state of India. In-situ experiments were conducted at 40 locations of the U tailings pile in three seasons namely summer, rainy and winter to measure the radon fluxes. The fluxes were also predicted by a diffusion model using the measured parameters such as Ra-226 content, bulk density, diffusion coefficient, radon emanation factor, moisture content and temperature in the U tailings. It was observed that the predicted fluxes using the in-situ diffusion length and emanation factor were closer to measured values by accumulator technique than that predicted using empirically estimated diffusion coefficient and emanation factor. A conversion factor has been established between radon fluxes and Ra-226 content in U tailings for Jaduguda. The source term arising due to the radon exhalation from U tailings pile at Jaduguda has determined using the measured data of radon fluxes.     

Thermal—fluid modelling of an air—cooled condenser for refrigerants

A steady state thermodynamic model for an air—cooled finned—tube condenser, used in a typical deep freezer vapour compression system, operating with pure and refrigerant mixtures has been developed using finite difference method. The heat transfer aspects in the condenser are treated uniquely for superheated, two—phase and subcooled regimes and studied for various heat load, pressure, temperature, and mass flow rate. The condensation heat transfer coefficient, the tube length required for condensation, the degree of subcooling, and the temperature glide for different ambient temperatures are estimated. The simulation and the experimental results are in good agreement.     

A new method for estimating the critical current density of a superconductor from its hysteresis loop

The critical current density J_c of some of the superconducting samples, calculated on the basis of the Bean’s model, shows negative curvature for low magnetic field with a downward bending near H = 0. To avoid this problem Kim’s expression of the critical current density, J_c = k/(H₀ + H), where J_c has positive curvature for all H, has been employed by connecting the positive constants k and H₀ with the features of the hysteresis loop of a superconductor. A relation between the full penetration field H_p and the magnetic field H_min, at which the magnetization is minimum, is obtained from the Kim’s theory. Taking the value of J_c at H = H_p according to the actual loop width, as in the Bean’s theory, and at H = 0 according to an enhanced loop width due to the local internal field, values of k and H₀ are obtained in terms of the magnetization values M⁺(?H_min), M^?(H_min), M⁺(H_p) and M^?(H_p). The resulting method of estimating J_c from the hysteresis loop turns out to be as simple as the Bean’s method.     

Extraction and Fractionation of Prokinetic Phytochemicals from Chrozophora tinctoria and Their Bioactivities

Chrozophora tinctoria is an annual plant of the family Euphorbiaceae, traditionally used as a laxative, a cathartic and an emetic. A methanolic extract of Chrozophora tinctoria (MEC) whole plant and an n-butanol fraction of Chrozophora tinctoria (NBFC) were analyzed by gas chromatography–mass spectrometry (GC-MS) to detect the phytochemicals. MEC and NBFC were tested for in vitro anti acetylcholinesterase (AChE) potential. The effect of both samples on intestinal propulsive movement and spasmolytic activity in the gastrointestinal tract (GIT) was also studied. About twelve compounds in MEC and three compounds in NBFC were tentatively identified through GC-MS. Some of them are compounds with known therapeutic activity, such as toluene; imipramine; undecane; 14-methyl-pentadecanoic acid methyl ester; and hexadecanoic acid. Both NBFC and MEC samples were checked for acute toxicity and were found to be highly toxic in a dose-dependent manner, causing diarrhea and emesis at 1 g/kg concentration in pigeons, with the highest lethargy and mortality above 3 g/kg. Both the samples of Chrozophora tinctoria revealed significant (p ≤ 0.01) laxative activity against metronidazole (7 mg/kg) and loperamide hydrochloride (4 mg/kg)-induced constipation. NBFC (81.18 ± 2.5%) and MEC (68.28 ± 2.4%) significantly increased charcoal meal intestinal transit compared to distal water (41.15 ± 4.3%). NBFC exhibited a significant relaxant effect (EC₅₀ = 3.40 ± 0.20 mg/mL) in spontaneous rabbit jejunum as compared to MEC (EC₅₀ = 4.34 ± 0.68 mg/kg). Similarly, the impact of NBFC on KCl-induced contraction was more significant than that of MEC (EC₅₀ values of 7.22 ± 0.06 mg/mL and 7.47 ± 0.57 mg/mL, respectively). The present study scientifically validates the folk use of Chrozophora tinctoria in the management of gastrointestinal diseases such as constipation. Further work is needed to isolate the phytochemicals that act as diarrheal agents in Chrozophora tinctoria.     

Benchmarking PES-Learn's machine learning models predicting accurate potential energy surface for quantum scattering

Machine learning (ML) models, neural networks, and Gaussian processes have been used to predict the potential energy surface taking C₂-He (both static and dynamic scenario) and NCCN-He collision systems. The surface is restricted to ∽125 points where traditional spline becomes inefficacious. Quantum dynamics is performed by solving close-coupling equation to compute cross sections benchmarking the performance of the ML models. The current study forms a basis for any future investigation of larger molecules where conventional fitting fails due to sparser ab initio points and cuts down the computational time without compromising on the quality of the surface.     

Correction to: Non‑precious transition metal‑based counter electrodes for dye‑sensitized solar cells

Journal of Solid State Electrochemistry -     

Visible-light-switchable Chalcone-Flavylium Photochromic Systems in Aqueous Media

The chalcone-flavylium photochromic system switches in aqueous media. However, the chalcone→flavylium conversion requires detrimental ultra-violet (UV) light for the switching which deters their applications in the biological domain. To address this issue, we have synthesized strategically modified chalcone scaffolds that can be reversibly switched to the flavylium forms with visible light ranging from 456 nm (blue) to 640 nm (red).     

Nanohybrid Comprising Gold Nanoparticles – MoS2 Nanosheets for Electrochemical Sensing of Folic Acid in Serum Samples

Folic acid (FA) deficiency is associated with several clinical conditions such as megaloblastic anemia, neuropsychiatric, and pregnancy-related syndromes, this makes FA an important metabolite to be monitored. We have fabricated an electrochemical biosensor based on gold nanoparticles decorated molybdenum disulfide nanosheets (AuNPs−MoS₂NSs) nanocomposite as a transducer matrix for specific and rapid electrochemical detection of FA. Differential pulse voltammetry (DPV) studies displayed a rapid analytical response of the fabricated AuNPs−MoS₂NSs/GCE sensor probe towards FA in a wide concentration range of 0.001–100 μM with a very low detection limit of 0.72±0.03 nM. The selectivity of the fabricated sensor probe has been examined in the presence of interferents such as dopamine, uric acid, ascorbic acid, glucose, and urea. The clinical potential of the fabricated biosensor was established by monitoring FA in human serum samples. The developed AuNPs−MoS₂NSs/GCE sensor probe showed high reproducibility and stability, indicating its promise for FA detection in clinical settings.