Ayurveda and other Indian system of medicine use metals, but their use is also amply described in Chinese and Egyptian civilization in 2500 B.C. Bhasma are unique ayurvedic metallic/minerals preparation, treated with herbal juice or decoction and exposed for Ayurveda, which are known in Indian subcontinent since 7th century A.D. and widely recommended for treatment of a variety of chronic ailments. Animal's derivative such as horns, shells, feathers, metallic, nonmetallic and herbals are normally administered as Bhasma. A Bhasma means an ash obtained through incineration; the starter material undergoes an elaborate process of purification and this process is followed by the reaction phase, which involves incorporation of some other minerals and/or herbal extract. There are various importance of Bhasma like maintaining optimum alkalinity for optimum health, neutralizing harmful acids that lead to illness; because Bhasma do not get metabolized so they don’t produce any harmful metabolite, rather it breakdowns heavy metals in the body. Methods including for Bhasma preparation are parpati, rasayoga, sindora, etc., Bhasma which contain Fe, Cu, S or other manufacturing process plays a specific role in the final product(s). Particle size (1-2 μ) reduced significantly, which may facilitate absorption and assimilation of the drug into the body system. Standardization of Bhasma is utmost necessary to confirm its identity and to determine its quality, purity safety, effectiveness and acceptability of the product. But the most important challenges faced by these formulations are the lack of complete standardization by physiochemical parameters.

With the depletion of conventional oil reservoirs and concerns about the increasing carbon footprint of coal, natural gas is poised to play a much bigger role in sustainable economic growth. Gas hydrates being an abundant source of clean methane have created great interest among academia and industry. Its demographic occurrence in shallow depths has motivated industry and academia to explore its abundance and exploitation potential. Despite being shallow, offshore gas hydrate exploration and drilling is a deepwater endeavor, which was considered expensive and risky as a result of its narrow thermodynamic stability and lack of exploitation experience. However, with recent advancement in technology and long-term field trials, it has been universally accepted that methane production from marine hydrate reservoirs is achievable with innovative drilling techniques and proper well design pertaining to the appropriate location and layout of wells, efficient well orientation, competent casing and tubing design, and completion design requirements for long operating life and reliability of the well. Much has been discussed about exploration and production, but very little has been addressed about the drilling technologies that have the potential for safe and effective exploitation of this resource in commercial quantities. The objective of this review is to enlighten the readers with exploration techniques used to locate gas hydrate reservoirs and discuss drilling tools and techniques that have the potential to avoid premature hydrate dissociation around the wellbore and enhance production life of the well with minimum interventions. The techniques discussed are mostly the learnings from the international drilling projects on different types of gas hydrate reservoirs. This review also focuses on different drilling fluids, pressurized coring systems, and well logs suitable for hydrate reservoirs. We believe that this review will provide a scientific reference material to engineers for safe exploration and drilling and stimulate upcoming exploration and drilling activities in the field of gas hydrates.

The performance of double hybrid density functionals (DHDFs) has been assessed by studying the spectroscopic properties and potential energy curves of OCS-C2H4 (carbonyl sulfide-ethylene) and OCS-C4H6 (carbonyl sulfide-dimethylacetylene) van der Waals complexes. Both dispersion corrected and uncorrected DHDF theories have been applied to study the intermolecular interaction energies, stability, spectroscopic parameters, rigidity, and binding energies or depths of the potential well of the weakly bound complexes and also to explore the possibility of formation of three isomers of each complex. The correlation consistent valence triple zeta quality basis set is used to investigate the complexes. The calculated results provide insight into the computational methods applied to the weakly bound complexes. The double hybrid density functional B2PLYP and mPW2PLYP methods with dispersion corrections (B2PLYP-D2, B2PLYP-D3 and mPW2PLYP-D2, mPW2PLYP-D3) performed better over the B2PLYP and mPW2PLYP density functional methods without dispersion correction to deal with the weak dispersion interaction that prevails in these complexes. The results obtained by the dispersion-corrected density functional mPW2PLYP-D2 and mPW2PLYP-D3 methods agree very well with the earlier experimental values wherever available. The contributing components of the interaction energy have been analyzed by the symmetry-adapted perturbation theory (SAPT, here, SAPT0) to get insight into the interaction energy.

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