Performance evaluation of an animal drawn puddling implements under controlled soil-bin conditions

Trials were conducted to evaluate the performance of three commonly used puddling implements, i.e. animal drawn rotary puddler (I₁), 3-tine tiller (I₂) and local plough (I₃) under controlled soil bin conditions for different numbers of passes of each implement. The performance of the rotary puddler was found to be better when operated more than twice under the controlled conditions in terms of quality and quantity of puddling. It was found that the rotary puddler gave a higher puddling index and required less energy to puddle the soil. The rotary puddler provided good “puddle” with a puddling index of 50% after two passes whereas, the other two implements required more than five passes for the same quality of puddling or puddling index in sandy clay loam soil     

FragNet,a Contrastive Learning-Based Transformer Model for Clustering,Interpreting, Visualizing,and Navigating Chemical Space

The question of molecular similarity is core in cheminformatics and is usually assessed via a pairwise comparison based on vectors of properties or molecular fingerprints. We recently exploited variational autoencoders to embed 6M molecules in a chemical space, such that their (Euclidean) distance within the latent space so formed could be assessed within the framework of the entire molecular set. However, the standard objective function used did not seek to manipulate the latent space so as to cluster the molecules based on any perceived similarity. Using a set of some 160,000 molecules of biological relevance, we here bring together three modern elements of deep learning to create a novel and disentangled latent space, viz transformers, contrastive learning, and an embedded autoencoder. The effective dimensionality of the latent space was varied such that clear separation of individual types of molecules could be observed within individual dimensions of the latent space. The capacity of the network was such that many dimensions were not populated at all. As before, we assessed the utility of the representation by comparing clozapine with its near neighbors, and we also did the same for various antibiotics related to flucloxacillin. Transformers, especially when as here coupled with contrastive learning, effectively provide one-shot learning and lead to a successful and disentangled representation of molecular latent spaces that at once uses the entire training set in their construction while allowing “similar” molecules to cluster together in an effective and interpretable way.     

Bimolecular Cross-Metathesis of a Tetrasubstituted Alkene with Allylic Sulfones

Exquisite control of catalytic metathesis reactivity is possible through ligand-based variation of ruthenium carbene complexes. Sterically hindered alkenes, however, remain a generally recalcitrant class of substrates for intermolecular cross-metathesis. Allylic chalcogenides (sulfides and selenides) have emerged as “privileged” substrates that exhibit enhanced turnover rates with the commercially available second-generation ruthenium catalyst. Increased turnover rates are advantageous when competing catalyst degradation is limiting, although specific mechanisms have not been defined. Herein, we describe facile cross-metathesis of allylic sulfone reagents with sterically hindered isoprenoid alkene substrates. Furthermore, we demonstrate the first example of intermolecular cross-metathesis of ruthenium carbenes with a tetrasubstituted alkene. Computational analysis by combined coupled cluster/DFT calculations exposes a favorable energetic profile for metallacyclobutane formation from chelating ruthenium β-chalcogenide carbene intermediates. These results establish allylic sulfones as privileged reagents for a substrate-based strategy of cross-metathesis derivatization.     

Radiological and hydrological implications of dissolved radon in alluvial aquifers of western India

Journal of Radioanalytical and Nuclear Chemistry - A study was undertaken to measure the dissolved radon (222Rn) concentration in parts of western India (Southwest Punjab) in order to evaluate its...     

Walking metals: catalytic difunctionalization of alkenes at nonclassical sites

Migration of metals along a carbon chain is triggered by two of the most common organometallic elementary steps – β-hydride (β-H) elimination and alkene hydrometallation. This process heralds a new future for creating bonds at carbon sites that fall outside the tenets of the conventional wisdom for reactivity and bond formation, and provides an opportunity to leverage β-H elimination to advance the very reaction of alkene difunctionalization it is intrinsically predestined to disrupt. Almost four decades since its genesis, the early adventure for alkene difunctionalization by metal migration was sporadic, and its later development went on a hiatus primarily due to original impetus on arresting β-H elimination for vicinal alkene difunctionalization. With the recent surge on alkene difunctionalization, efforts have been gradually shifting to harnessing the process of β-H elimination to difunctionalize alkenes at sites other than the classical vicinal carbons, termed henceforth nonclassical reaction sites for pedagogical simplicity. In this review article, we extricate and examine the origin and the development of such reactions over the years. This review covers a wide range of reactions for the difunctionalization of alkenes at geminal (1,1), allylic (1,3) and remote (1,n) carbon sites with a variety of coupling partners. These reactions have enabled engineering of complex molecular frameworks with the generation of new carbon–carbon (C–C)/C–C, C–C/C–heteroatom (halogens, O, N, B) and C–B/C–B bonds. The development of these unique transformations is also presented with mechanistic hypotheses and experimental evidences put forward by researchers. Judged by the number of reports emerging recently, it is now strikingly evident that the field of alkene difunctionalization by metal migration has begun to gain momentum, which holds a great future prospect to develop into a synthetic method of enormous potential.

Alkenes can be difunctionalized at unconventional carbon sites by the migration of transition metals through β-hydride elimination and hydrometallation steps.     

Voltammetric Detection of Aqueous Glyphosate on a Copper and Poly(Pyrrole)-electromodified Activated Carbon Fiber

Aqueous glyphosate (GLYP) was voltammetrically detected using a Cu-(poly)pyrrole composite electrochemically deposited on activated carbon fiber for the first time in a single-step method. Differential pulse voltammetry indicated good linearity (R² = 0.9902) in the response over 0.02–12 mg L⁻¹ range, with a low limit of detection (0.01 mg L⁻¹). The sensor exhibited reproducibility for soil and fruit samples (RSD values = 2.41 and 3.87%, respectively). The response showed repeatability over 100 consecutive measurements. The response was also unaffected by the interfering substances containing the same functional groups as in GLYP and its metabolite. The method described in this study is facile.     

Distribution of uranium in groundwaters of Bathinda and Mansa districts of Punjab,India: inferences from an isotope hydrochemical study

This paper presents the isotope hydrochemical results of groundwaters from southwest Punjab for assessing the uranium contamination and evaluating the factors leading to elevated uranium concentration. A total of 35 samples covering shallow and deep zones were collected for hydrochemistry and isotopes. Uranium concentration ranges between 2.3 and 357 µg L^?1 and 66% of the samples are contaminated. Both shallow and deep zones show U contamination but high incidences are noticed in shallow zone. Hydrochemical correlations infer geological sources rather than anthropogenic sources responsible for U contamination. Isotopically there is no clear distinction between high and low U groundwater.     

Nitrogen content determinations in different stages of thermal treatment involved in conversion of ammonium diuranate to uranium metal

Accurate, low-level measurement of ²²⁶Ra in high volume water samples requires rapid pre-concentration and robust separation techniques prior to measurement in order to comply with discharge limits and drinking water regulations. This study characterises the behaviour of ²²⁶Ra and interfering elements on recently developed TK100 (Triskem International) extraction chromatography resin. Distribution coefficients over a range of acid concentrations are given, along with an optimised procedure that shows rapid pre-concentration and separation of ²²⁶Ra on TK100 resin is achievable for high volume (1 L) water samples without the need for sample pre-treatment.