On the Prediction of Grain Refinement Mechanism in Direct Chill Casting of Aluminum and Its Alloys Under Low Degree Mechanical Forced Convection

Deepak Patel,Prasenjit Biswas,Anil Kumar,Hiren R. Kotadia,Archana Mallik,Sanjeev Das 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The present investigation focuses on grain refinement in pure aluminum and its alloy under mechanical stirring with a verylow degree of forced convection of 800 rpm as compared to reported values of up to 8000 rpm during direct chill castingprocess (DC). Commercially pure aluminum (99.7%) and Al6082 alloy billets were fabricated in an in-house designed DCcasting simulator. Mechanical forced convection (MFC) was applied to the melt during casting by a common four-bladedimpeller. The microstructural properties of the as-cast billets have been analysed to study the effect of MFC during casting andsolidification. The structure of both Al and its alloy is found to be refined in presence of MFC as compared to conventionalDC. A combination of simulation, experimental and theoretical approaches has been used to determine the effect of MFCin melt-temperature distribution to propose the mechanism of grain refinement. It has been observed that MFC prominentlyreduces the temperature gradient and extends undercooling time, resulting in fine grain structure.

C2 Superior Facetal Osteotomy: A Novel Technique in Complex Craniovertebral Junction Surgery for C1 Lateral Mass Screw Placement

Deepak Kumar Singh,Shankar Diwakar,Vipin Kumar Chand,Singh Rakesh Kumar,Singh Neha 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.6

Complex craniovertebral junction (CVJ) defects account for a considerable proportion of CVJ diseases. Given the heavily assimilated C1, an unfavorable C1–C2 joint orientation, an overriding C2 superior facet, a low-hanging occiput, and an abnormal vertebral artery course with a high-riding vertebral artery, placement of C1 lateral mass screws might be difficult. To address this, a novel technique for placing C1 lateral mass screws that avoid vertebral artery injury, low-hanging occiput, and overriding C2 superior facet was developed in this study. This approach enables firm fixation of C1–C2 even in difficult situations where the placement of the C1 lateral mass is challenging.

Ruptured mirror DACA aneurysm: A rare case report and review of literature

Deepak Kumar Singh,Prevesh Kumar Sharma,Arun Kumar Singh,Vipin Kumar Chand 대한뇌혈관외과학회 2023 Journal of Cerebrovascular and Endovascular Neuros Vol.25 No.3

Bilateral distal anterior cerebral artery (DACA) aneurysms also called “kissing aneurysms” or “mirror aneurysm” are extremely rare, accounting for only 0.2% of all intracranial aneurysms. There have only been a few examples of mirror DACA aneurysms reported in the literature. Here, we report a rare case of mirror DACA aneurysm in a middle aged female with its successful clipping. Patient was admitted with severe headache and altered sensorium. Computed tomography (CT) head was suggestive of anterior inter-hemispheric hematoma. Digital subtraction angiography (DSA) was done which was suggestive of two distal anterior cerebral artery aneurysms located at same anatomical position. It was treated through microsurgical clipping. Mirror image DACA aneurysms are rare occurrence. All patients with ruptured DACA aneurysms should have angiography with 3D reconstruction studies. This aids in determining the aneurysm’s morphology and planning treatment accordingly.

Green and proficient process for industrial-scale preparation of Gymnema sylvestre standardized-extract enriched with Gymnemic acids through polymer-matrix-adsorption to reduce hyperglycemia

Deepak Kumar,Vipin Kumar Singh,Narayan Prasad Yadav,Sudeep Tandon,Karuna Shanker,Chandan Singh Chanotiya,Narendra Kumar,Puja Khare,Anirban Pal,Debabrata Chanda,Dharmendra Saikia,Yusuf Hussain,Abha Mee 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.116 No.-

Gymnema sylvestre is an important medicinal plant, but a method for preparing standardized extractenriched with biomarkers is not available. The practiced crude hydro-alcoholic extracts of G. sylvestrecontained a few percentage of gymnemic acids (GAs). The enrichment of GAs in preprared extracts isessential from a pharmacology point of view. Presently, a scale-up process has been developed forpreparing G. sylvestre standardized extract (Gym-EEXT). Crude extract (Gym-Crude) was prepared in10-kg batches to obtain a yield of 268.1 mg/g, but GAs was merely 9 mg/g (GA-IV 6.7 mg/g, and GAXVII2.3 mg/g) in 30 % ethanol–water solvent at 50 C in 5 h. Further, Gym-Crude was processed throughpolymer-matrix-adsorption techniques for getting Gym-EEXT (150.9 mg/g) with improved percentage ofGAs (>10 %) comprised of deacylgymnemic acid (DGA: 8.9 mg/g), gymnemagenin (2.3 mg/g), GA-IV(78.6 mg/g), and GA-XVII (10.2 mg/g). For safety aspects, the pesticide residues, solvent residues, heavymetal, aflatoxins, and mutagenicity in Gym-EEXT were below the detection limits. Hence, Gym-EEXT wasenriched with GAs, and fully safe with compliance according to USP-561. An insignificant effect of Gym-EEXT on vitals of experimental mice was observed in acute and sub-acute oral-toxicityexperiments. Gym-EEXT significantly improved the blood glucose metabolism, and hence, it potentiallyreduces hyperglycaemia. Unique chromatographic protocols were developed for the isolation of biomarkerson a 1-kg scale from Gym-Crude with yield of gymnemagenin (5.5 %), and DGA (4.6 %). Finally, a novel,scientifically validated, and the scale-up process has been developed for the preparation of Gym-EEXTalong with an exclusive protocol for isolating its biomarkers.

Application of Adaptive Neuro-Fuzzy Inference System for Evaluating Compressive Strength of Concrete

Deepak Kumar Sinha,Rupali Satavalekar,Senthil Kasilingam 한국지능시스템학회 2021 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.21 No.2

The objectives of this study are to develop a model for predicting the compressive strength of concrete using an adaptive neuro-fuzzy inference system (ANFIS) and validate the mix proportion using artificial neural networks (ANNs) and by experimentation. A model was developed, and the compressive strength was predicted using the ANFIS (with the subtractive clustering method of the fuzzy inference system) by MATLAB programming. In the present study, two ANFIS models were considered: ANFIS models-1 and -2. ANFIS model-1 was developed to predict the 3-day compressive strength, whereas ANFIS model-2 predicts the 28-day compressive strength by considering the 3-day compressive strength data obtained using ANFIS model-1. It was observed that the errors in the 3- and 28-day compressive strengths were 6.33%, and 17.07%, respectively. Furthermore, experiments were performed for selective mixes-M40, M50, and M60-to verify the compressive strength obtained using the ANFIS model. The model results were verified against the experimental ones based on the mixes selected from the model, and the results were found to agree with the predicted ones, with a maximum deviation of 18%. Furthermore, an ANN model was developed to predict the compressive strength to verify the accuracy of the ANFIS model. The results predicted by the ANFIS and the ANN were compared with the original results available in the literature. A significant deviation was found between the ANN model results and the original results, however, the ANN model results presented the same trend as the original results. It was concluded that the ANFIS model results were highly consistent with the original results.

Synthesis, Antioxidant and Molecular Docking Studies of (-)-Catechin Derivatives

Kumar, Deepak,Kumar, Raj,Ramajayam, R.,Lee, Keun Woo,Shin, Dong-Soo Korean Chemical Society 2021 대한화학회지 Vol.65 No.2

12 kinds of (-)-catechin derivatives were designed and synthesized. The catechin derivatives were evaluated their antioxidant activities using DPPH method. Most of them showed good antioxidant activity, particularly compounds 1d, 1e and 1j exhibited more activity than butylated hydroxytoluene (BHT). Molecular docking studies for compounds 1d, 1e and 1j with STAT1 showed not only sufficent characteristics binding cavity but also agreement with the observed biological activity. Acording to docking results, the compounds showed greater than hydrogen bonding, hydrophobic interactions, electrostatic interactions, and Van der Waals interactions as compared to the reference compound. They formed hydrogen bonds with important residues such as Lys566, His568, Leu570, and Phe644. The compounds showed a novel hydrogen bonding interaction with Arg649, which was not reported previously. Our results might suggest the compounds could serve as a novel anti-oxidant agent.

A Finite Element Modeling of Low Velocity Impact in Laminated Composite Using Continuum Shell element

Deepak Kumar,Jin-Hwe Kweon,Jin-Ho Choi 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

Low velocity impact is considered potentially dangerous for a composite structure mainly because, the damage in the form of delamination and matrix cracking. To be able to assess the critical nature of the induced damage, a thorough study of damage mechanism is needed. The main challenge is to predict damage initiation and propagation of low velocity impact-induced damage by the use of damage mechanism. For the damage evolution law, stress and fracture mechanics based failure criteria is applied. Damage model is implemented in FEM code ABAQUS. The results show good agreement with the existing experimental results.

Effect of Parasitic Capacitance on RF MEMS Switch OFF/ON Ratio

Deepak Bansal,Khushbu Mehta,Anuroop Bajpai,Amit Kumar,Prem Kumar,Kamaljit Rangra 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

Radio frequency micro-electro-mechanical system (RF MEMS) switch is basic component for transponders used in communication system. Switch “OFF/ON” capacitance ratio plays major role in controlling signal to noise ratio. Theoretically,with high dielectric constant material or fl oating metal concept, capacitance ratio can be improved up to 2000 or even more. Whereas, in most of the practical cases, measured ratio is less than 200. In present paper, RF MEMS capacitive switch LCR parameters are extracted considering parasitic capacitance to explain the mismatch of measured results. Parasitic capacitance is independent from device overlap area. Parasitic capacitance is function of switch geometry and directly proportional to dielectric constant of the substrate material.

MHD Pulsatile Flow and Heat Transfer of Two Immiscible Couple Stress Fluids Between Permeable Beds

Kumar, Deepak,Agarwal, Manju Department of Mathematics 2021 Kyungpook mathematical journal Vol.61 No.2

The present paper addresses magnetohydrodynamic pulsating flow and heat transfer of two immiscible, incompressible, and conducting couple stress fluids between two permeable beds. The flow between the permeable beds is assumed to be governed by Stokes' [28] couple stress fluid flow equations, whereas the dynamics of permeable beds is determined by Darcy's law. In this study, matching conditions were used at the fluid-fluid interface, whereas the B-J slip boundary condition was employed at the fluid-porous interface. The governing equations were solved analytically, and the expressions for velocity, temperature, mass flux, skin friction, and rate of heat transfer were obtained. The analytical expressions were numerically evaluated, and the results are presented through graphs and tables.

Diversity and Abundance of Pollinators Affecting Seed Production in Radish (Raphanus sativa)

Deepak Kumar Sharma,Dharam Pal Abrol 한국양봉학회 2023 韓國養蜂學會誌 Vol.38 No.4

Investigations were conducted to determine the impact of insect pollinators affecting seed production in Radish. Observations revealed that honey bees Apis cerana, A. mellifera, A. dorsata, A. florea were the important flower visitors and comprised more than 83 per cent of the flower visiting insects. Of all the honeybees, A. cerana was the most abundant followed by A. mellifera>A. dorsata>A. florea. The activity of honeybees increased with temperature and sunshine and decreased with relative humidity, wind speed, rainfall and evaporation. The influence of flowering seasonality had significant effect on population dynamics of bees as maximum population of all the bee species were observed after 12 days of flowering. Open pollination was found to be superior to both hand pollination and self pollination treatments. The number of siliquae produced, 1000 seed weight, seed yield per plant, and seed germination (%) was significantly higher in bee pollinated plots compared to open pollination and self pollination. Open pollination and hand pollination resulted in 118 and 76 per cent enhanced seed yield in radish as compared to control.