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Carbanion of fluorene can promote single electron transfer under photochemical conditions which generates multiple species to trigger a cascade of electron transfers, overall amplifying the rate.

Dihydrophenazine upon deprotonation behaves as an initiator to steer cross-coupling reactions under visible-light conditions. The single electron transfer is driven by the aromaticity gained during the process.

The formazan ligands have been investigated as redox-noninnocent backbones for a long time. Despite their well-established behaviour as redox reservoirs, the demonstration of catalytic efficiency governed by redox noninnocence remains elusive. We report an iron-formazanate molecule for efficiently preparing α-keto amides, where a crucial reductive cleavage of the substrate molecule is tightly regulated by the electron donation from the formazanate, in a reversible manner.

Alkenyl boronate esters are important synthons for various pharmaceuticals, agrochemicals, natural products, and material science. Direct alkene sp2 C-H bond borylation is highly valued for its synthesis. However, the drawbacks associated with chemo-, regio- and stereoselectivity, using late transition metal catalysts, and the need for sacrificial hydrogen scavengers impeded its practicability and sustainability. Herein, we utilized a 3d metal complex as a catalyst for synthesizing alkenyl boronate esters via the dehydrogenative coupling of styrenes and pinacolborane. Hydrogen gas is produced as the sole byproduct without needing an acceptor, making the process green and atom-economical. The methodology depicted excellent selectivity towards dehydrogenative borylation over direct hydroboration. Borylation of aromatic alkenes over aliphatic ones was also noticed. Derivatives of natural products and bioactive molecules underwent successful diversification. The product alkenyl boronate esters could be employed for synthesizing several drugs and potential anticancer agents. Thorough experimental and high-level computational studies were performed to delineate the reaction pathway. The hemilability and metal-ligand bifunctionality of the ligand backbone was found to be crucial for successful catalytic turnover.

Herein we report the synthesis of primary and secondary amines by nitrile hydrogenation, employing a borrowing hydrogenation strategy. A class of phosphine-free manganese(I) complexes bearing sulfu...

A well-defined, bench-stable nickel catalyst is presented here, that can facilitate double alkylation of a methyl ketone to realize a wide variety of cycloalkanes. The performance of the catalyst depends on the ligand redox process comprising an azo-hydrazo couple. The source of the bis electrophile in this double alkylation is a 1,n-diol, so that (n+1)-membered cycloalkanes can be furnished in a stereoselective manner. The reaction follows a cascade of dehydrogenation/hydrogenation reactions and adopts a borrowing hydrogen (BH) method. A thorough mechanistic analysis including the interception of key radical intermediates and DFT calculations supports the ligand radical-mediated dehydrogenation and hydrogenation reactions, which is quite rare in BH chemistry. In particular, this radical-promoted hydrogenation is distinctly different from conventional hydrogenations involving a metal hydride and complementary to the ubiquitous two-electron driven dehydrogenation/hydrogenation reactions.

SUMMARYWe analyse P-wave receiver functions across the Kumaon Himalaya and adjoining area to constrain crustal thickness, intracrustal structures and seismic velocity characteristics to address the role of the underlying structure on seismogenesis and geodynamic evolution of the region. The three-component waveforms of teleseismic earthquakes recorded by a seismological network consisting of 18 broad-band seismological stations have been used for receiver function analysis. The common conversion point (CCP) depth migrated receiver function image and shear wave velocity models obtained through inversion show a variation of crustal thickness from ∼38 km in the Indo-Gangetic Plain to ∼42 km near the Vaikrita Thrust. A ramp (∼20°) structure on the Main Himalayan Thrust (MHT) is revealed beneath the Chiplakot Crystalline Belt (CCB) that facilitates the exhumation of the CCB. The geometry of the MHT observed from the receiver function image is consistent with the geometry revealed by a geological balanced cross-section. A cluster of seismicity at shallow to mid-crustal depths is detected near the MHT ramp. The spatial and depth distribution of seismicity pattern beneath the CCB and presence of steep dipping imbricate faults inferred from focal mechanism solutions suggest a Lesser Himalayan Duplex structure in the CCB above the MHT ramp. The study reveals a low-velocity zone (LVZ) with a high Poisson's ratio (σ ∼0.28–0.30) at lower crustal depth beneath the CCB. The high value of Poisson's ratio in the lower crust suggests the presence of fluid/partial melt. The shear heating in the ductile regime and/or decompression and cooling associated with the exhumation of the CCB plausibly created favorable conditions for partial melting in the lower crustal LVZ.

A hydrolytic transformation study was conducted in water of pH 4.0, 7.0 and 9.2 to evaluate the effect of pH on persistence of a new readymix formulation of fomesafen and quizalofop-ethyl. The water samples were fortified at 0.5 and 1 µg mL−1 levels and analysed at 0 (2 h), 1, 3, 7, 15, 30, 60, 90, 120, 150 days interval. Both the analytical methods were validated following SANTE guideline and found accurate based on average recovery of 80–100%, Relative standard deviation (RSD)

Herein, we report the stereoselective synthesis of (1 + n)-membered cycloalkane from methyl ketone and 1,n-diol. A manganese(I) complex bearing a phosphine-free ligand catalyzed the reaction, which...

Background: Although India is an important producer of litchi fruit, there is hardly any validated method available for its pesticide residue analysis. This strongly warrants the need to standardize a simple multiresidue analytical method for efficient analysis of multiclass pesticides with specificity, sensitivity, and accuracy in a single chromatographic run in combination with MS determination. Objective: The aim of this study was to develop and validate a rapid ethyl-acetate-based sample preparation method for a simultaneous determination of 86 pesticides in litchi fruit by using GC–tandem MS. Methods: The method involved ethyl acetate as an extracting solvent and a combined salt system comprising sodium chloride and sodium sulphate for the organic layer separation. To obtain satisfactory recovery percentage of each pesticide studied here, this combination was selected for further validation based on selectivity, sensitivity, linearity, precision, and accuracy values. Results: The correlation coefficient (r2) of studied pesticides ranged between 0.97 and 0.99 at six concentration levels from 5 to 250 ng/mL. Furthermore, the average recovery values were within 70 and 120%, with repeatability relative SD below 20% for all 86 pesticides at the LOQ level and with an appreciable Horwitz ratio distribution that ranged between 0.5 and 2. Conclusions: All data demonstrate that the proposed method is adequately linear, accurate, and repeatable. Therefore, it can be widely used in commercial laboratories for analyzing pesticide residues for both domestic and export purposes. The method is in support of protecting consumer health. Highlights: A large-scale multiresidue method is reported for simultaneous analysis of a wide range of pesticides in litchi. The method complies with the regulatory requirements in terms of sensitivity for maximum residue limit compliance. The performance of the method complied with the SANTE guidelines of analytical QC.

Herein we report a homogeneous, phosphine free, inexpensive nickel catalyst that forms a wide variety of benzazoles from alcohol and diamines by a reaction sequence of alcohol oxidation, imine formation, ring cyclization and dehydrogenative aromatization. A reversible azo/hydrazo couple, that is part of the ligand architecture steers both the alcohol oxidation and dehydrogenation of the annulated amine under fairly mild reaction conditions. Interestingly, both the alcohol oxidation and amine dehydrogenation steps are directly mediated by hydrogen atom transfer (HAT), which is greatly facilitated by the reduced ligand backbone. The kH/kD for the amine dehydrogenation step, measured at 60 °C is 5.9, fully consistent with HAT as the rate determining factor during this step. This is a unique scenario where two consecutive oxidation steps towards benzazole formation undergo HAT, which has been substantiated via kinetic studies, KIE determination and intermediate isolation.

Herein we introduce a transition-metal-free protocol that involves a commercially available, inexpensive pyrazole molecule to conduct C-C cross-coupling reactions at room temperature via a radical pathway. Using this method, an aryldiazonium salt has been coupled to a wide range of arenes and heteroarenes including benzene, mesitylene, thiophene, furan, benzoxazole to result the corresponding biaryl products. The full reaction mechanism is elucidated along with the crystallographic probation of an active initiator species. A potassium-stabilized deprotonated pyrazole steers single-electron transfer to the substrate and behaves as an initiator for the reaction.

A well-defined, bench-stable nickel catalyst is presented here, that can facilitate double alkylation of a methyl ketone to realize a wide variety of cycloalkanes. The performance of the catalyst depends on the ligand redox process comprising an azo-hydrazo couple. The source of the bis electrophile in this double alkylation is a 1,n-diol, so that (n+1)-membered cycloalkanes can be furnished in a stereoselective manner. The reaction follows a cascade of dehydrogenation/hydrogenation reactions and adopts a borrowing hydrogen (BH) method. A thorough mechanistic analysis including the interception of key radical intermediates and DFT calculations supports the ligand radical-mediated dehydrogenation and hydrogenation reactions, which is quite rare in BH chemistry. In particular, this radical-promoted hydrogenation is distinctly different from conventional hydrogenations involving a metal hydride and complementary to the ubiquitous two-electron driven dehydrogenation/hydrogenation reactions., A homogeneous nickel catalyst is described that forms (n+1)-membered cycloalkane rings from ketones and 1,n-diols following a radical-promoted pathway.

We solve the Euler equations in one and two dimensions using a central compact scheme coupled with an AUSM+ algorithm. The compact scheme is used in the form of a cell-face interpolation scheme to create the left- and right-states of the primitive variables required by the AUSM+ based solver. We invoke a TVD limiter to locally apply smaller stencil low-order dissipative formulae near shocks. No extra high-order artificial dissipation is added to stabilize the computation. A number of one and two dimensional test cases has been solved to show the effectiveness of this approach.

We report herein a well-defined and bench-stable azo-phenolate ligand-coordinated nickel catalyst which can efficiently execute N-alkylation of a variety of anilines by alcohol. We demonstrate that the redox-active azo ligand can store hydrogen generated during alcohol oxidation and redelivers the same to an in-situ-generated imine bond to result in N-alkylation of amines. The reaction has wide scope, and a large array of alcohols can directly couple to a variety of anilines. Mechanistic studies including deuterium labeling to the substrate establishes the borrowing hydrogen method from alcohols and pinpoints the crucial role of the redox-active azo moiety present on the ligand backbone. Isolation of the ketyl intermediate in its trapped form with a radical quencher and higher kH/kD for the alcohol oxidation step suggest altogether a hydrogen-atom transfer (HAT) to the reduced azo backbone to pave alcohol oxidation as opposed to the conventional metal–ligand bifunctional mechanism. This example clearly de...

Crustal thickness and Poisson's ratios were estimated at 13 broadband seismological stations established in a profile along the Kali river valley, Kumaon (Central) Himalaya. The seismological profile extends from the Indo-Gangetic plain (IGP) in the south to the Higher Himalaya in the north, passing through the Sub and Lesser Himalaya. The Receiver Function (RF) method has been adopted to investigate the crustal structure beneath the profile. Time domain iterative deconvolution method has been adopted for RF computation. The H-k stacking method has been adopted to analyze the RFs for obtaining average crustal thickness and Poisson’s ratio (σ) of the crust beneath each station. The study reveals that the crustal thickness beneath the IGP is ∼38 km which gradually increases up to ∼41 km at the northernmost station located in the Higher Himalaya. The values of σ vary from 0.23 to 0.28. The value of σ is low in the Sub-Himalaya and outer Lesser Himalaya suggesting more of a felsic composition of crust. A Significantly high value of σ (∼0.28) is observed in the Dharchula region of the Chiplakot Crystalline belt which is coincident with a large number of micro-to-moderate magnitude earthquakes forming a cluster at shallow to mid-crustal depths. The high Poisson’s ratio is possibly due to the presence of fluids/partial melts at mid-crustal depth. The presence of fluids influences the rheological property and controls the mechanical and shear strength of crustal rocks producing a cluster of seismicity observed beneath the Dharchula region.

A comprehensive research has been undertaken to explore the shift of primary metabolic flux with phenolic acid profile during transition of mature green to ripe stage of tomato(Solanum lycopersicum) high pigment (hp-1, hp-2dg and ogc) and non-ripening (rin) mutants. High pigment mutants revealed higher response for the amino acids like phenylalanine, tryptophane, proline, lysine, glutamicacid, serine, gamma aminobutyric acid, glutamine, aspartic acid, glycine, alanine, leucine and threonine compared to ‘Ailsa Craig’ along with the induced response in terms of organic acids viz. oxoglutaric acid, acetic acid, maleic acid, succinic acid,phosphoric acid, fumaric acid,ascorbic acid, tartaric acid, cis-aconitic acid, lactic acid, malic acid and methyl maleic acid. Cell wall sugars were lower in induced shelf-life mutant of hp-2dg and rin. Amongst phenolic acids chlorogenic acid, protocatechuic acid, caffeic acid, ellagic acid, gallic acid, 4-hydroxybenzoic acid showed increased response for high pigment mutants. Total phenol content was lower in high pigment mutants with no significant change for flavonoids. High pigment tomato mutants are metabolically explored for first time through Gas Chromatography Mass Spectrometry and Ultra Performance Liquid Chromatography. Fruit tissue specific primary metabolic shifts along with phenolic acids profile during ripening of tomato high pigment and non-ripening mutants has also been established for the first time. This metabolite kinetics may provide the foundation for utilizing these natural high pigment and non-ripening mutants for marker assisted breeding and metabolite engineering in future.

Weeds are the major limiting factor for optimum soybean production in India. The herbicide mixture of fomesafen and quizalofop-ethyl provides effective control of a broad spectrum of weeds, but its fate in the tropical soybean ecosystem is unknown and also the risks involved to the consumer and the environment are still unexplored. Hence, a supervised field trial was conducted following the post-emergence application of fomesafen 12% + quizalofop-ethyl 3% in two consecutive seasons. The dissipation of fomesafen followed biphasic double first order in parallel kinetics, whereas quizalofop-ethyl dissipation followed first order kinetics. A significant difference in the persistence of fomesafen was observed due to seasonal variation of meteorological parameters. However, the variation was significant only in plant, but non-significant in soil, in case of quizalofop-ethyl. The overall shorter persistence of both fomesafen and quizalofop-ethyl was recorded in warmer climatic conditions of Season I than Season II. The results thus indicated that care must be taken during application of this herbicide mixture in cold climatic regions, since both the herbicides may exhibit higher stability. The absence of end-point residues at harvest concluded that the formulation is safe for application in tropical agroclimate. The low chronic dietary toxicity and low soil ecological toxicity indicated that the herbicide mixture will offer no threat against consumer health and soil ecosystem. However, there was a concern about the toxicity against soil algal population which needs to be reconfirmed by further studies.

Controlled cooling rate is essential in steel production in order to obtain the desired grades for specific mechanical properties. Optimal control of cooling process parameters is important to obtain the desired cooling rate. The system level uncertainty around the cooling process, the model form error around the generative model for the cooling process as well as the measurement noise make the problem of optimal cooling even more challenging. Machine learning approaches have been used in the recent past to solve optimization and optimal control problems. The present study sets out to design an optimal and robust cooling rate controller using a data-driven approach within a machine learning framework which accounts for the uncertainties inherent in the system. A Gaussian process regression model is developed to predict the cooling rate using temperate-time data and two simulated latent parameters with a suitable confidence interval. The experiments have been undertaken on a laboratory scale Run Out Table setup. The results show the suitability of the proposed approach to obtain a robust response surface of the cooling rate with the process parameters.

The research portrays the fate of a new herbicide mixture of fomesafen and quizalofop-ethyl. The soil samples viz. red lateritic soil (A), coastal saline soil (B) and black soil (C) were fortified separately for fomesafen and quizalofop-ethyl at 0.5 (T1) and 1.0 mg kg−1 (T2) doses and incubated at 20, 30 and 40°C. A satisfactory mean recovery, precision and linearity proved that the methods were accurate. Both the herbicides followed first + first order kinetics. Higher persistence of fomesafen was observed in Soil C than Soil B and Soil A with 22.38–53.75 days half-life, whereas quizalofop-ethyl showed higher stability in Soil A than Soils B and C with half-life of 0.93–12.07 days. Both compounds showed faster rates of dissipation at increased temperature, irrespective of soil type. The current study will help to predict the effect of temperature on the dissipation of herbicides in different soil under real field scenario.

A computational fluid dynamic method has been applied to simulate the pressure blast from a cannon and to investigate the pressure distribution on a wall located in front of the cannon. By solving this problem, peak value of pressure on wall has been calculated for different pressure ratio of driver and driven section in the cannon. By taking the maximum value of pressure at a particular pressure ratio as factor of safety, we have to invent a blast wave resisting jacket which will be helpful for blast wave explosion. The Advection Upstream Splitting Method (AUSM) scheme with third-order Monotone Upstream centered Scheme for Conservation Laws (MUSCL) approach were used for solving the unsteady, axisymmetric Navier–Stokes equation. Density-based solver was selected for present simulation due to its high-speed compressibility. The standard K-epsilon model with standard wall function is used for this simulation which is highly suitable for wall phenomenon problems. At the initial condition of this problem, the driver section of cannon is given to high pressure and driven section is at atmospheric pressure. After firing from cannon, flow of air take place from driver section to driven section and at advance time air flows out from the cannon. At exit of the cannon blast wave formation takes place which move in forward direction and after some time it strikes to the wall and move in backward direction. The computational result indicated that on increasing the pressure ratio in cannon causes the multiple fluctuations in pressure on the wall. The increase in pressure ratio also increases the peak pressure on wall.

Structural health monitoring for lightweight complex composite structures is being investigated in this paper with a data-driven deep learning approach to facilitate automated learning of the map of transformed signal features to damage classes. Towards this, a series of acoustic emission (AE) based laboratory experiments have been carried out on a composite sample using a piezoelectric AE sensor network. The registered time-domain AE signals from the assigned sensor networks on the composite panel are processed with the continuous wavelet transform to extract time-frequency scalograms. A convolutional neural network based deep learning architecture is proposed to automatically extract the discrete damage features from the scalogram images and use them to classify damage-source regions in the composite panel. The proposed deep-learning approach has shown an effective damage monitoring potential with high training, validation and test accuracy for unseen datasets as well as for entirely new neighboring damage datasets. Further, the proposed network is trained, validated and tested only for the peak-signal data extracted from the raw AE data. The application of peak-signal scalogram data has shown a significant improvement in damage-source classification performance with high training, validation and test accuracy.

A novel probabilistic robust design optimization framework is presented here using a Bayesian inference framework. The objective of the proposed study is to obtain probabilistic descriptors of the system parameters conditioned on the user-prescribed target probability distributions of the output quantities of interest or figures of merit of a system. A criterion-based identification of a reduced important parameter space is performed from the typically high number of parameters modelling the stochastically parametrized physical system. The criterion can be based on sensitivity indices, design constraints or expert opinion or a combination of these. The posterior probabilities on the reduced or important parameters conditioned on prescribed target distributions of the output quantities of interest is derived using the Bayesian inference framework. The probabilistic optimal design proposed here offers the distinct advantage of prescribing probability bounds of the system performance functions around the optimal design points such that robust operation is ensured. The proposed method has been demonstrated with two numerical examples including the optimal design of a structural dynamic system based on user-prescribed target distribution for the resonance frequency of the system.