Patterns of Allozymic Variation and Alcohol Tolerance in Indian Populations of Drosophila Bipectinata

, Ravi,Manju Sharma,Sharma, Suman 한국유전학회 1994 Genes & Genomics Vol.16 No.4

Six Indian geographical populations of D. bipectinata were analysed electrophoretically for allozymic variation at nine loci as well as for ethanol tolerance potential. Allelic frequency changes at Adh, Odh and Est-5 loci correlated significantly with increase in latitude. On the basis of F_(ST) values, Adh, Odh, Mdh and α-Gpdh loci depicted modest amounts of genetic differentiation. Thus, the occurrence of significant genotypic as well as allelic frequency heterogeneity, genic differentiation and clinal variation at polymorphic loci suggest evidence of natural selection maintaining such genic differentiation in D. bipectinata populations from the Indian sub-continent. The Indian populations of D. bipectinata revealed genetic differentiation in term of ethanol indices such as LT_(50) hrs(72 to 96 hrs), adult ethanol threshold concentration(2.5 to 4.0'%), LC_(50) thanol concentration(2.7 to 4.2%). The parallel occurrence of latitudinal variation at Adh locus as well as ethanol tolerance in Indian geographical populations of D. bipectinata could be maintained by balancing natural selection varying spatially along the north south axis of the Indian sub-continent.

Kinetics, thermodynamic and equilibrium study of Cr(VI) adsorption from aqueous solutions by NCL coal dust

Ravi Shankar Singh,Monoj Kumar Mondal 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.12

The waste material NCL coal dust was used as adsorbent for removal of Cr(VI) from aqueous solutions under batch adsorption experiments. The maximum removal of 99.97% was recorded at pH 2. The time required to attain equilibrium was found to be 60 min. Adsorption kinetics was described by the Lagergren equation. The value of the rate constant of adsorption was found to be 0.0615 min−1 at 16 mg dm−3 initial concentration and 298 K. The applicability of the Langmuir and Freundlich equations for the present system was also tested at different temperatures:298, 313, and 328 K. Both thermodynamic parameters and temperature dependence indicated the endothermic nature of Cr(VI) adsorption on coal dust. The results showed that NCL coal dust is a promising adsorbent for the removal of Cr(VI) from aqueous solutions.

EDTA-functionalized KCC-1 and KIT-6 mesoporous silicas for Nd³⁺ ion recovery from aqueous solutions

Ravi, Seenu,Zhang, Siqian,Lee, Yu-Ri,Kang, Kyoung-Ku,Kim, Ji-Man,Ahn, Ji-Whan,Ahn, Wha-Seung Elsevier 2018 Journal of industrial and engineering chemistry Vol.67 No.-

<P><B>Abstract</B></P> <P>Ethylenediaminetetraacetic acid (EDTA)-functionalized KIT-6 and KCC-1 mesoporous silicas were prepared via post-synthesis grafting and examined for their ability to promote the recovery of rare earth metal ions such as Nd<SUP>3+</SUP> from an aqueous medium. The obtained adsorption isotherms were fitted to the Langmuir model, which gave a maximum adsorption of Nd<SUP>3+</SUP> ions of 109.8 and 96.5mg/g for KIT-6-EDTA and KCC-1-EDTA, respectively, at 25°C and pH 6. The adsorption kinetic profile of KIT-6 was faster than KCC-1. KIT-6 was also proved to be more stable against desorption under acidic regeneration conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ethylenediaminetetraacetic acid (EDTA) grafted KIT-6 and KCC-1 was prepared. </LI> <LI> KIT-6-EDTA showed high adsorption capacities for Nd<SUP>3+</SUP> ions in water. </LI> <LI> Adsorption equilibrium, isotherm, and kinetics were investigated. </LI> <LI> KIT-6-EDTA reused for 5 cycles without deterioration in adsorption capacities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Cycloaddition of CO₂ and epoxides over a porous covalent triazine-based polymer incorporated with Fe₃O₄

Ravi, Seenu,Puthiaraj, Pillaiyar,Park, Dong-Wha,Ahn, Wha-Seung The Royal Society of Chemistry 2018 New journal of chemistry Vol.42 No.15

<P>A highly porous quaterphenyl-containing covalent triazine polymer (QP-CTP) incorporated with iron oxide nanoparticles (Fe3O4@QP-CTP) was synthesized and applied as a catalyst for the cycloaddition of CO2 and epoxides under mild conditions. The synthesized materials were characterized using X-ray powder diffraction, N2 adsorption-desorption isotherm, X-ray photoelectron spectroscopy, transmission electron microscopy, and elemental analysis. The Fe3O4@QP-CTP composite in the presence of tetrabutylammonium bromide showed 95% conversion of epoxides with high selectivity to cyclic carbonates at 50 °C, 0.1 MPa CO2 in 12 h. The reaction kinetics was further improved upon increasing the temperature to 80 °C. The catalyst was easily recovered using a magnet, and its stability was confirmed using a recycle test, which showed that the catalyst could be re-used for a minimum of eight consecutive runs without a noticeable decline in catalytic activity. A plausible mechanistic pathway of the cycloaddition reaction over Fe3O4@QP-CTP was also proposed.</P>

Porous Covalent Organic Polymers Comprising a Phosphite Skeleton for Aqueous Nd(III) Capture

Ravi, Seenu,Puthiaraj, Pillaiyar,Yu, Kwangsun,Ahn, Wha-Seung American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.12

<P>In order to meet the ever-increasing industrial demand for rare-earth elements (REEs), it is desirable to separate and recycle them at low concentrations from various sources including industrial and urban wastes. Here, we introduced phosphorus binding sites on the hydrophobic surface of a robust and high-surface area porous polymer backbone for environmentally benign and selective recovery of REEs via adsorption. For this purpose, two porous covalent organic polymer (COP) materials incorporated with in-built phosphite functionality (P-COP-1 and P-COP-2) were synthesized and applied for the adsorptive separation of Nd(III) ions from aqueous solution. A strategy to develop a series of P-COPs via a simple Friedel-Crafts reaction was introduced, and their application to the selective adsorption of REEs was explored for the first time. The newly synthesized P-COPs were amorphous and/or weakly crystalline and showed excellent chemical stability and large specific surface area with sufficient mesoporosity for enhanced diffusion of REE ions. P-COP-1 exhibited an exceptionally high Nd(III) adsorption capacity of 321.0 mg/g, corresponding to the stoichiometric ratio of P/Nd(III) = 1:0.7 and high selectivity of >86% over other competing transition and alkaline earth metal ions, whereas P-COP-2 gave a Nd(III) adsorption capacity of 175.6 mg/g at 25 °C and pH 5. Moreover, P-COP-1 showed a distribution coefficient value of 5.45 × 10<SUP>5</SUP> mL/g, which is superior to other benchmark adsorbent materials reported so far. Finally, the P-COPs were reusable for a minimum of 10 cycles without deterioration in adsorption capacities.</P> [FIG OMISSION]</BR>

Integrative Thinking as a Hallmark of Business Education

Ravi Chinta,Venessa Funches Funches,Hamed Esmaeilioghaz Esmaeilioghaz 국제융합경영학회 2016 융합경영연구 Vol.4 No.4

In this paper we expand on the notion of “integration” in terms of the variety of ways in which it would manifest itself in business education. Our main argument is that “integration” is multidimensional and has been manifest in pedagogy, research and service dimensions of university programs for a long time. However, assessments of “integration” efforts have been spotty thus far and only recently are being formalized. We present several examples in business curriculum and with increased focus on formal assessments of “integration” efforts, business education will become more pragmatic. The goal of this paper is to unpack the broad construct of “integration,” and discuss its historical and current manifestations in business education. Ultimately, we conclude that while the process of integrative thinking is well underway for a long time in business education, the assessment of outcomes of integrative thinking is just taking root through formal ETS tests. We believe that integrative thinking in business education is an ultimate indicator of the effectiveness of the business curriculum, as students skilled in this area will be best prepared for the real-life jobs in the market place.

Characterization of green ceramic-aluminum composites developed from waste recycling

Ravi Kumar Singh,Ali Algahtani,Tawfiq Al-Mughanam,Intezar Mahdi,Vineet Tirth 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

Green composites were prepared by recycling waste Aluminum and ceramic debris of marble and granite stones obtainedduring stone cutting at building construction sites. The composites were developed using the most economical stir castingprocess under ambient conditions with five weight percent of white marble powder and black granite powders. Themicrostructure characterization was done with my optical and SEM micrography as well as XRD. The microstructure showsfair particle distribution and improved hardness by 22-25% than the base matrix. The tensile strength and elastic modulusalso improved. The density remained stagnant due to porosity. A decline in elongation and impact strength was observed. Thestudy recommends using waste Aluminum and waste ceramic powders to develop green composites for non-critical industrialapplications such as structures, furniture, stationary machine parts, and automobile chassis.

Strategies for Stimulating Customer Relationship: A Study of Some Public and Private Sector Banks

Ravi Kiran,Ridhima Sharma 한국유통과학회 2013 유통과학연구 Vol.11 No.3

Purpose - The present research has been undertaken to examine the Customer Relationship Management (CRM) strategies adopted by public and private sector banks in India. The initial part of research helps to identify the factors of overall satisfaction of customers. The study also tries to identify the key determinants of CRM of Indian banking. Research design, data, methodology - The present research uses a self-structured questionnaire having a reliability score of 0.817 to elicit responses from customers in New Delhi and surrounding areas in India to examine the CRM used by public and private sector banks for enhancing customer satisfaction. The scale had 32 questions covering customer perceptions related to overall satisfaction and factors contributing to CRM. Results - The results highlight that overall satisfaction comprises of two factors namely personalised Services; and reliability and dependability. The determinants of CRM as identified through survey are: Speed, safety and security; Employee CRM; on time services; customer targeting; and friendly and helpful staff. The results also highlight that safety and security was preferred to other factors by the respondents. Conclusions - The findings of this study show that in terms of performance private sector banks fared better in providing CRM services than public sector banks.

Investigation on Bonding Strength and Tribological Performances of Ceramic Laminated AA6063 Composite Developed by Friction Stir Additive Manufacturing

Ravi Prajapati,Suryank Dwivedi,Deepak Kumar,Ashish Kumar Srivastava,Amit Rai Dixit 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.1

The demand for novel laminated sheets encouraged using newer technologies to produce tailored materials for multipurpose applications. An inventive solid-state joining method: friction stir additive manufacturing, which offers several advantages over traditional lamination processes. In this study, the Al2O3 powder is used as reinforcement during AA6063/Al2O3/AA6063 composites fabrication. The fabricated specimen was characterized by bonding features such as thickness reduction, metallography, mechanical properties, and tribological performances and compared with sheet lamination and base metal. The optical microscope and scanning electron microscopic images showed that the Al2O3 powder is distributed within the composites. The structural analysis at the interface of the fabricated composite was conducted through X-ray diffraction, confirming the compounds like Mg2SiO4, Mg2Al4, and Al2O3 in the crystallographic planes. The microstructural and morphological results of the laminated composite showed the refined and equiaxed grains and also depicted the dispersion of the Al2O3 powder near the stir zone. The microhardness properties were enhanced and obtained as 91.2 HV and 77.5 HV with and without reinforcement, respectively. Further, the ultimate tensile strength with and without reinforcement is improved by 36.9% and 24.7% compared to the base metal. Furthermore, the tribological analysis was performed at variable process parameters. Taguchi's L9 orthogonal array and variance analysis (ANOVA) were done to analyze the effect of individual parameters and their significance. The obtained results showed that load and frequency are significant parameters during the tribology test. The laminated composite's specific wear rate, wear depth, and COF values are less than the sheet lamination and align with ANOVA test results. Furthermore, the wear mechanism was observed, and it was found that sheet lamination has high wear at increased load when compared to laminated composite parts. Therefore, the obtained results dictate that the addition of Al2O3 powder can significantly enhance the bonding strength, mechanical and tribological properties of the fabricated composites.

Modeling and Control of Exhaust Recompression HCCI: Split Fuel Injection for Cylinder-Individual Combustion Control

Ravi, N.,Hsien-Hsin Liao,Jungkunz, A. F.,Han Ho Song,Gerdes, J. C. IEEE 2012 IEEE control systems magazine Vol.32 No.4

<P>The 21st century has brought with it a strong push in the automotive industry to develop energy technologies that can better address the global challenges posed by the depletion of finite fossil fuel resources and the pollution caused by using these fossil fuels as an energy resource. The two key words dominating automotive powertrain research today, therefore, are efficiency and emissions-There is a strong push for cars that burn less fuel and emit fewer pollutants. Some of the technologies in the spotlight include fuel cells, batteries, hybrid powertrains, and advanced IC engine strategies. Though fuel cells and battery technologies are very promising in the long-term future, they are currently more expensive and less practical than hybrid and advanced combustion engine strategies and are expected to remain so in the near future. In addition, technological advances that have made electronic control systems ubiquitous in todays automobiles have enabled combustion strategies that would not have been possible even a decade ago. One such advanced engine strategy that presents significant opportunities for reduced emissions and higher efficiencies is homogeneous charge compression ignition (HCCI).</P>