Optimization of Reaction Conditions for High Yield Synthesis of Carbon Nanotube Bundles by Low-Temperature Solvothermal Process and Study of their H₂ Storage Capacity

Krishnamurthy, G.,Agarwal, Sarika Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.10

Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of $180^{\circ}C$. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based $N_2$ gas adsorption studies have been made to obtain BET surface area and $H_2$ storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

Optimization of Reaction Conditions for High Yield Synthesis of Carbon Nanotube Bundles by Low-Temperature Solvothermal Process and Study of their H2 Storage Capacity

G. Krishnamurthy,Sarika Agarwal 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.10

Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of 180 °C. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based N2 gas adsorption studies have been made to obtain BET surface area and H2 storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

Highly stable hetero-structured green-emitting cesium lead bromide nanocrystals <i>via</i> ligand-mediated phase control

Grandhi, G. Krishnamurthy,Viswanath, N. S. M.,Cho, Han Bin,Kim, Seong Min,Im, Won Bin Royal Society of Chemistry 2019 Nanoscale Vol.11 No.44

<P>Green-emissive Cs4PbBr6 shows promise for light-emitting diode devices superior to that of CsPbBr3 NCs owing to their stability and high photoluminescence efficiency. Nevertheless, there is still no consensus regarding the basis of their green emission, which decelerates their advance in light-emitting applications. Herein, a systematic investigation on the concentration of capping ligands (oleylamine and oleic acid), which determines the predominant phase between CsPbBr3 and Cs4PbBr6 for a given Cs to Pb feed ratio, is conducted. This study deduces that oleylamine to oleic acid ratio plays a crucial role in obtaining either green-emissive or non-emissive Cs4PbBr6 NCs. Scrutiny of Cs4PbBr6 microscopic and optical data in addition to their emission quenching study with a hole-withdrawing molecule reveals that the green emission originates from the CsPbBr3 impurity phase. Furthermore, stable green emission is observed for CsPbBr3/Cs4PbBr6 nanocrystals when CsPbBr3 particles are well protected by the Cs4PbBr6 matrix. These CsPbBr3/Cs4PbBr6 films remained highly luminescent even after UV exposure for hours or annealing at ∼150 °C for days in addition to their long-term stability under an ambient atmosphere, which are the desirable properties for various practical applications.</P>

Strategies for improving luminescence efficiencies of blue-emitting metal halide perovskites

Grandhi G. Krishnamurthy,김하준,Viswanath N. S. M.,조한빈,한주형,김성민,Im Won Bin 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.1

Lead halide perovskites (LHPs) are suitable as the emissive layers in light-emitting diodes (LEDs). The external quantum effi ciency of green LEDs based on LHPs is now over 20%. Nevertheless, the blue LHP LEDs lag behind the green ones in terms of effi ciency. Photoluminescence (PL) quantum yield (QY) and stability of the NCs under various operating conditions are two major factors that infl uence the LED performance. Therefore, to promote the eff orts towards achieving improved LED effi ciencies, herein, we summarize several synthetic methods that produce blue-emitting LHP NC, followed by several approaches devised to boost their PL QYs up to near unity. Light-induced anion segregation is one of the limitations of using blue-emitting mixed-halide LHPs, which triggers the attention to single halide, quantum-confi ned LHP nanoplatelets (NPLs). Syntheses, structure, and luminescent properties of organic–inorganic and all-inorganic blue-emitting LHP NPLs are discussed elaborately. In the last portion, the luminescent properties of lead-free metal halides, which are of current interest, are discussed, followed by an outlook and future directions. In conclusion, our review discusses various literature attempts to obtain stable blue-emitting LHP NCs, which can be helpful in a better design of the blue-emitting LHP NCs towards various light-emitting applications.

Significance of cyclic loading parameters on the flexural response of the GFRP composites

T. G. Loganathan,R. Krishnamurthy,K. Chandrasekaran 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7

Automotive design calls for weight reduction, considering fuel consumption and vehicle dynamics as well. Application of composite materials for suspensions and other structural members is in that direction. Owing to their high specific strength and inherent structural damping qualities, composites can be an alternative to metallic materials, especially with the suspension-springs. Further, epoxy composites can resist environmental influences, facilitating easier maintenance. In this study, we assessed the flexure response of GFRP composite exposed to pre flexure cyclic loading. This was to simulate the loading environment of an automobile leaf spring. Experiments were conducted with Taguchi’s DOE using L9 orthogonal array with two factors and three levels. The test specimens were prepared by hand lay-up technique with four layers of (0/0/0/0, 0/30/60/0, 0/90/90/0 and 0/45/0/-45) orientation. Constant peak amplitude cyclic loading was imposed on the specimen by an eccentric disc in a radial drilling machine. The flexural modulus of the cyclic loaded specimen was obtained by three point bend test as per ASTM D790. Assessment of the test results by ANOVA, S/N ratio and regression analysis indicated that the flexural modulus of the pre flexural cyclic loaded composite is significantly influenced by the loading parameters (loading cycle and frequency), and the flexural modulus can be enhanced with reduced fiber orientation interactions within the lay-up at critical operating conditions. The damage pattern influenced by fibre orientation in the lay-up sequence is ascertained by SEM images.

Assessment of Cyclic Load Induced Energy Dissipation and Damping on GFRP Composite Laminate

T. G. Loganathan,K. Vinoth Kumar,R. Krishnamurthy 한국섬유공학회 2020 Fibers and polymers Vol.21 No.9

Polymeric composites exhibit load sensitive stiffness unlike the case of homogeneous metallic material. Composites are widely used in dynamic loading environment and hence it is necessary to study their response in terms ofstructural properties. Behavioural changes of glass epoxy composite laminate on exposure to cyclic loading has been assessedin terms of energy dissipation (Ed) and Damping factor (DF) by hysteresis loop. GFRP composite specimens (UD-0, 0/30/60/0, 0/45/0/-45, 0/90/90/0, and 0/90/0/90) are exposed to low velocity constant amplitude cyclic loading using a laboratoryarrangement (by an eccentric disc) at 4.6 Hz and 8.6 Hz frequencies. In fibre-reinforced composites apart from the fibrevolume fraction, the fibre interaction angle significantly influences their dynamic properties on loading. Unidirectional (UD-0) laminate exhibits low damping/energy dissipation, while 0/90/0/90 laminate with large fibre interaction angle showshighest damping/energy dissipation. Whereas, symmetric cross ply (0/90/90/0) laminate acts as a performance demarcationamong the chosen laminates. Thus, optimum Ed/DF properties of GFRP laminate in dynamic environment is attributed tosymmetric lay-up, smaller fibre orientation interaction angle in the lay-up sequence and 0 fibre layer at the boundary.

Biotechnological Approach of Threatened Species Strychnos Nux-vomica L. to Standardized Nursery Techniques

O. P. Chaubey,G. Krishnamurthy 보안공학연구지원센터 2015 International Journal of Bio-Science and Bio-Techn Vol.7 No.6

Strychnos nux-vomica belonging to family Loganiaceae. Carbohydrate, protein, oil, steroid, alkaloid, resin, strychnine and brucine were detected in phytochemical screening. It is anticipated that lipid peroxidation may provide scientific rationale for the use of S. nux-vomica as an antidiabetic plant. There is a need to develop bio-technological approach for raising nursery plants of S. nux-vomica as per International Union for Conservation of Nature and Natural Resources (IUCN) criteria. Different concentration of growth hormones to break seed dormancy, four pre treatments, different size of polythene bags, root trainer, and impact of potting mixture on the growth were adopted to determine the best treatments. The results indicated that the seed dormancy was broken when seeds were treated with 40 ppm concentration of GA3 or 100 ppm concentration of IBA hormones and soaking with warm water, the best size of polythene bag was used as medium size of polythene (25x11 cm), the best size of root trainer was used as medium cup root trainer (187 cm3), and the best potting mixture was found to be farm yard manure (FYM) with soil and sand in ratio of 1:1:1. Statistical analysis was also adopted to determine of significance levels.

Identification and expression profiling of a new β-amyrin synthase gene (GmBAS3) from soybean

Ali, M. M.,Krishnamurthy, P.,El-Hadary, M. H.,Kim, J. M.,Nawaz, M. A.,Yang, S. H.,Chung, G. Pleiades Publishing 2016 Russian journal of plant physiology: a comprehensi Vol.63 No.3

Body Composition Predicts Survival in Patients with Hepatocellular Carcinoma Treated with Transarterial Chemoembolization

Neehar D. Parikh,Peng Zhang,Amit G. Singal,Brian A. Derstine,Venkat Krishnamurthy,Pranab Barman,Akbar K. Waljee,Grace L. Su 대한암학회 2018 Cancer Research and Treatment Vol.50 No.2

Purpose The prognosis of patients with hepatocellular carcinoma (HCC) undergoing transarterial chemoembolization (TACE) is often uncertain. We aimed to utilize analytic morphomics, a high-throughput imaging analysis, to assess if body composition is predictive of post-TACE survival. Materials and Methods We included patients from a single center (Ann Arbor VA) who had TACE as the primary treatment for HCC and had a pre-treatment computed tomography scans. Univariate analysis and multivariate conditional inference tree analysis were utilized to identify the morphomic characteristics predictive of 1-year survival. Results were validated in an external cohort (University of Michigan Health System) of HCC patients who underwent TACE as their primary treatment. Results In the 75 patients in the derivation cohort, median survival was 439 (interquartile range, 377 to 685) days from receipt of TACE, with 1-year survival of 61%. Visceral fat density (VFD) was the only morphomic factor predictive of overall and 1-year survival (p < 0.001). Patients with VFD above the 56th percentile had a 1-year survival of 39% versus 78% for those below the 56th percentile. VFD also correlated with 1-year survival in the external validation cohort (44% vs. 72%, p < 0.001). In a secondary analysis, patients with higher VFD were significantly more likely to experience hepatic decompensation after TACE (p < 0.001). Conclusion VFD served as an objective predictor of mortality in patients undergoing TACE, possibly through its ability to predict hepatic decompensation. VFD may serve as a radiographic biomarker in predicting TACE outcomes.

Plant Diversity, Edaphic Status and Population Structure in Different Forest Types of Madhya Pradesh and Chhattisgarh States in India

O.P. Chaubey,Archana Sharma,G. Krishnamurthy 보안공학연구지원센터 2015 International Journal of Bio-Science and Bio-Techn Vol.7 No.2

The present paper deals with the plant diversity, physico-chemical status of soil and population structure in different forest types/sub types of Madhya Pradesh and Chhattisgarh. The paper described the dominant and co-dominant status of tree, herbs, shrubs, climbers, and grasses species along with density, basal area, and population structure and biodiversity index in different forest types / sub types. Differences in the species composition from site to site could be attributed to climate change. The population structure in different forest types/sub types followed three categories viz; Greater proportion of individuals in the lower girth classes in forest types; Gap phase type, having absence of individuals in certain girth classes in forest type; More individuals in sapling stage and absence in higher classes in a forest type. There is a need to develop climate resilient forest management towards balancing the population structure of different species in different forest types / sub types for increasing the forest productivity.