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Mesophase formation behavior in petroleum residues
Subhash Kumar,Manoj Srivastava 한국탄소학회 2015 Carbon Letters Vol.16 No.3
Mesophase pitch is an important starting material for making a wide spectrum of industrial and advanced carbon products. It is produced by pyrolysis of petroleum residues. In this work, mesophase formation behavior in petroleum residues was studied to prepare environmentally-benign mesophase pitches, and the composition of petroleum residues and its influence on the mesophase formation was investigated. Two petroleum residues, i.e., clarified oils (CLO-1, CLO-2) obtained from fluid catalytic cracking units of different Indian petroleum refineries, were taken as feed stocks. A third petroleum residue, aromatic extract (AE), was produced by extraction of one of the CLO-1 by using N-methyl pyrrolidone solvent. These petroleum residues were thermally treated at 380°C to examine their mesophase formation behavior. Mesophase pitches produced as a result of thermal treatment were characterized physico-chemically, as well as by instrumental techniques such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction and thermogravimetry/derivative thermogravimetry. Thermal treatment of these petroleum residues led to formation of a liquid-crystalline phase (mesophase). The mesophase formation behavior in the petroleum residues was analyzed by optical microscopy. Mesophase pitch prepared from CLO-2 exhibited the highest mesophase content (53 vol%) as compared to other mesophase pitches prepared from CLO-1 and AE.
Subhash Kumar,Manoj Srivastava 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.48 No.-
The aim of this work is to study melioration in mesophase formation behaviour by deasphalting ofpetroleum residues. Pitches prepared from VRs have undesirable high values of physico-chemicalproperties as compared to their corresponding DAOs pitches. This is due to presence of high molecularweight asphaltenes molecules in VRs. The optical microscopic images of VR-390-1 and VR-390-2 pitchesshowed that they have small sized, distorted and agglomerated types of mesophase having mesophasecontents (MC) 25 vol% and 22 vol% respectively but deasphalting of these VRs improve the growth andoptical texture of mesophase in DAO-390-1 (29 vol%) and DAO-390-2 (35 vol%).
Agrobacterium tumefaciens-Mediated Genetic Transformation: Mechanism and Factors
Kumar, Nitish,Vijayanand, K.G.,Reddy, Myppala P.,Singh, Amritpal S.,Naraynan, Subhash Institute of Forest Science 2009 Journal of Forest Science Vol.25 No.3
Agrobacterium-mediated genetic transformation has been widely used for the production of genetically modified transgenic plants to obtain specific desired traits. Most of the molecular mechanisms that underlie the transformation steps have been well elucidated over the years. However, a few steps, such as nuclear targeting, T-DNA integration, and Agrobacterium-plant proteins involved remain largely obscure and are still under extensive studies. This review describes the major steps involved in the molecular mechanism of Agrobacterium-mediated transformation and provides insight in the recent developments in studies on the Agrobacterium-mediated genetic transformation system. Some factors affecting the transformation efficiency are also briefly discussed.
Kumar, Nitish,Singh, Amritpal S.,Modi, Arpan R.,Patel, Armi R.,Gajera, Bhavesh B.,Subhash, Narayanan Institute of Forest Science 2010 Journal of Forest Science Vol.26 No.1
Sixteen microsatellite markers (simple sequence repeat (SSR) markers) were employed to examine the genetic stability of 27 randomly chosen date palm (Phoenix dactylifera L.) plants produced through somatic embryogenesis with upto forty two in vitro subcultures. No microsatellite DNA variation was observed among all micropropagated plants. Our results indicate that the micropropagation protocol used for rapid in vitro multiplication is appropriate and suitable for clonal propagation of date palm and corroborated that somatic embryogenesis can also be used as one of the safe modes for production of true-to-type plants of date palm. This is the first report on the use of microsatellite DNA markers to establish the genetic stability in micropropagated date palm plants.
Optimization of ferrochrome slag as coarse aggregate in concretes
Subhash C. Yaragal,B. Chethan Kumar,Krishna Mate 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.6
The alarming rate of depletion of natural stone based coarse aggregates is a cause of great concern. The coarse aggregates occupy nearly 60-70% by volume of concrete being produced. Research efforts are on to look for alternatives to stone based coarse aggregates from sustainability point of view. Response surface methodology (RSM) is adopted to study and address the effect of ferrochrome slag (FCS) replacement to coarse aggregate replacement in the ordinary Portland cement (OPC) based concretes. RSM involves three different factors (ground granulated blast furnace slag (GGBS) as binder, flyash (FA) as binder, and FCS as coarse aggregate), with three different levels (GGBS (0, 15, and 30%), FA (0, 15, and 30%) and FCS (0, 50, and 100%)). Experiments were carried out to measure the responses like, workability, density, and compressive strength of FCS based concretes. In order to optimize FCS replacement in the OPC based concretes, three different traditional optimization techniques were used (grey relational analysis (GRA), technique for order of preference by similarity (TOPSIS), and desirability function approach (DFA)). Traditional optimization techniques were accompanied with principal component analysis (PCA) to calculate the weightage of responses measured to arrive at the final ranking of replacement levels of GGBS, FA, and FCS in OPC based concretes. Hybrid combination of PCA-TOPSIS technique is found to be significant when compared to other techniques used. 30% GGBS and 50% FCS replacement in OPC based concrete was arrived at, to be optimal.
Nitish Kumar,Amritpal S. Singh,Arpan R. Modi,Armi R. Patel,Bhavesh B. Gajera,Narayanan Subhash 강원대학교 산림과학연구소 2010 Journal of Forest Science Vol.26 No.1
Sixteen microsatellite markers (simple sequence repeat (SSR) markers) were employed to examine the genetic stability of 27 randomly chosen date palm (Phoenix dactylifera L.) plants produced through somatic embryogenesis with upto forty two in vitro subcultures. No microsatellite DNA variation was observed among all micropropagated plants. Our results indicate that the micropropagation protocol used for rapid in vitro multiplication is appropriate and suitable for clonal propagation of date palm and corroborated that somatic embryogenesis can also be used as one of the safe modes for production of true-to-type plants of date palm. This is the first report on the use of microsatellite DNA markers to establish the genetic stability in micropropagated date palm plants.
Structural, Electrical and Red Emission Properties of Pd/n-ZnO/p-Si/Al Heterostructures
Rajender Kumar,Subhash Chand 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.6
The ZnO thin films were grown on p-type silicon by pulsed laser deposition method for fabrication of ZnO/p-Si heterojunction. X-ray diffraction patterns were used to study the grain size and morphology of the ZnO thin film. Optical properties of ZnO thin film were studied by UV-visible, photoluminescence spectroscopy and atomic force microscopy. Experimental observations confirmed that the deposited ZnO thin films have potential for sharp emission in the visible region. High purity (99.999%) vacuum evaporated palladium and aluminium metals were used to make contacts to the n-ZnO and p-Si, respectively. The current-voltage characteristics of the Pd/n-ZnO/p-Si(100)/Al heterostructure measured over the temperature range 80 - 300 K, were studied on the basis of the thermionic emission-diffusion mechanism. The equivalent Schottky barrier height and ideality factor were determined by fitting measured current-voltage data to the thermionic emission-diffusion current equation. It was observed that the barrier height decreased and the ideality factor increased with decreasing temperature and that the activation energy plot was non-linear at low temperature. These characteristics were attributed to the Gaussian distribution of barrier heights. The capacitance-voltage characteristics of the Pd/n-ZnO/p- Si(100)/Al heterojunction diode were studied over a wide temperature range. From the measured capacitance-voltage data the impurity concentration in deposited n-type ZnO films was estimated.
Primary pyomyositis in North India: a clinical, microbiological, and outcome study
( Susheel Kumar ),( Ashish Bhalla ),( Rajveer Singh ),( Navneet Sharma ),( Aman Sharma ),( Vikas Gautam ),( Surjit Singh ),( Subhash Varma ) 대한내과학회 2018 The Korean Journal of Internal Medicine Vol.33 No.2
Background/Aims: Pyomyositis is an infective condition with primary involvement of the skeletal muscles. There is sparse recent literature on patients with pyomyositis. Methods: This study was carried out at emergency services of a tertiary care center located in subtropical area of Indian subcontinent. Results: Sixty-two patients of primary pyomyositis formed the study cohort. Mean age of occurrence was 29.9 ± 14.8 years. There were 54 men. Twelve patients had underlying medical diseases. Muscle pain was seen in all 62 patients. Forty-eight patients (77.4%) had the fever. Most common site of involvement was thigh muscles (n = 29, 46.8%). Forty-nine patients (79%) presented in the suppurative stage of illness. Patients with comorbidities were older (age: median 36 years [interquartile range (IQR), 25 to 47] vs. 24 years [IQR, 16 to 35], p = 0.024), had higher culture positivity with gram-negative organisms (8/9 [88.89%] vs. 6/29 [20.69%], p = 0.001). Importantly, higher number of these patients received inappropriate antibiotics initially. Patients with positive pus culture result had higher complication rate (32/38 [84.21%] vs. 10/18 [55.56%], p = 0.044). Six patients (9.7%) had in-hospital mortality. Lower first-day serum albumin, initial inappropriate antibiotic therapy, and advanced form of the disease at presentation were associated with increased in-hospital mortality. Conclusions: Primary pyomyositis is not an uncommon disease entity. Patients with comorbidities were more likely to receive initial inappropriate antibiotic therapy. Patients with positive pus culture report had the higher rate of complications. Lower first-day serum albumin, initial inappropriate antibiotic therapy and advanced form of the disease at presentation were associated with increased in-hospital mortality.