Synthesis of Co(II), Ni(II) and Cu(II) Complexes from Schiff base Ligand and Reactivity Studies with Thermosetting Epoxy Resin

B. Lakshmi,Krishna Reddy K. Rama,Gouda Avaji Prakash,K. N. Shivananda,K. N. Mahendra 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

A hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) containing Co(II), Ni(II) and Cu(II) ions was prepared by curing N-MPGE and tetradentate Schiff base Co(II),Ni(II) and Cu(II) complexes. The curing polymerization reaction of N-MPGE with metal complexes as curing agents was studied. The cured samples were studied for thermal stability, chemical (acid/alkali/solvent) and water absorption resistance and homogeneity of the cured systems. The tetradentate Schiff base, 3-[(Z)-2-piperazin-1-yl-ethylimino]-1,3-dihydro indol-2-one was synthesized by the condensation of Isatin (Indole-2, 3-dione) with 1-(2-aminoethyl)piperazine (AEP). Its complexes with Co(II), Ni(II) and Cu(II) have been synthesized and characterized by microanalysis, conductivity, Uv-Visible, FT-IR, TGA and magnetic susceptibility measurements. The spectral data revealed that the ligand acts as a neutral tetradentate Schiff base and coordinating through the azomethine nitrogen, two piperazine nitrogen atoms and carbonyl oxygen

Synthesis of Co(II), Ni(II) and Cu(II) Complexes from Schiff base Ligand and Reactivity Studies with Thermosetting Epoxy Resin

Lakshmi, B.,Shivananda, K.N.,Prakash, Gouda Avaji,Rama, Krishna Reddy K.,Mahendra, K.N. Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

A hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) containing Co(II), Ni(II) and Cu(II) ions was prepared by curing N-MPGE and tetradentate Schiff base Co(II), Ni(II) and Cu(II) complexes. The curing polymerization reaction of N-MPGE with metal complexes as curing agents was studied. The cured samples were studied for thermal stability, chemical (acid/alkali/solvent) and water absorption resistance and homogeneity of the cured systems. The tetradentate Schiff base, 3-[(Z)-2-piperazin-1-yl-ethylimino]-1,3-dihydro indol-2-one was synthesized by the condensation of Isatin (Indole-2, 3-dione) with 1-(2-aminoethyl)piperazine (AEP). Its complexes with Co(II), Ni(II) and Cu(II) have been synthesized and characterized by microanalysis, conductivity, Uv-Visible, FT-IR, TGA and magnetic susceptibility measurements. The spectral data revealed that the ligand acts as a neutral tetradentate Schiff base and coordinating through the azomethine nitrogen, two piperazine nitrogen atoms and carbonyl oxygen.

MULTIPLIERS FOR OPERATOR-VALUED BESSEL SEQUENCES AND GENERALIZED HILBERT-SCHMIDT CLASSES

KRISHNA, K. MAHESH,JOHNSON, P. SAM,MOHAPATRA, R.N. The Korean Society for Computational and Applied M 2022 Journal of applied mathematics & informatics Vol.40 No.1-2

In 1960, Schatten studied operators of the form $\sum_{n=1}^{{\infty}}\;{\lambda}_n(x_n{\otimes}{\bar{y_n}})$, where {x_n}n and {y_n}_n are orthonormal sequences in a Hilbert space, and {λ_n}n ∈ ℓ^∞(ℕ). Balazs generalized some of the results of Schatten in 2007. In this paper, we further generalize results of Balazs by studying the operators of the form $\sum_{n=1}^{{\infty}}\;{\lambda}_n(A^*_nx_n{\otimes}{\bar{B^*_ny_n}})$, where {A_n}n and {B_n}_n are operator-valued Bessel sequences, {x_n}_n and {y_n}_n are sequences in the Hilbert space such that {║x_n║║y_n║}_n ∈ ℓ^∞(ℕ). We also generalize the class of Hilbert-Schmidt operators studied by Balazs.

Facile, Morphology-Controlled and Mass Production of 0D-Ag/2D-g-C3N4/3D-TiO2 Nano-Composite Materials: Effect of Silver Morphology and Loading on the Electrochemical Performance

R. Ranjithkumar,P. Lakshmanan,N. Palanisami,P. Devendran,N. Nallamuthu,S. Sudhahar,M. Krishna Kumar 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.2

The 0D-Ag/2D-g-C3N4/3D-TiO2 nano-composite materials were fabricated by simple and mass production method. It involvesthe combination of incipient wetness impregnation and thermal spreading techniques. By changing the order of impregnationand thermal spreading, silver nanoparticles with “on-top” and “embedded” morphologies could be selectively controlled. Thethermal spreading followed by impregnation (TS-IM) leads to the “on-top” structure [Ag/g-C3N4/TiO2] while, the reverseorder (IM-TS) produces the embedded silver nanoparticles [g-C3N4/Ag/TiO2]. The 16%Ag/g-C3N4/TiO2 (TS-IM) sampleexhibited the best performance due to the presence of very small and highly dispersed silver nanoparticles over g-C3N4/TiO2 sample. The loading of silver not only doubled the specific capacitance but also stabilized the recycling performanceagainst deactivation. This study reveals easy and performance tunable synthesis of Ag/g-C3N4/TiO2 nano-composite materialstowards energy-storage applications.

Complete Relaxation and Conformational Exchange Matrix (CORCEMA) Analysis of Saturation Transfer Difference (STD) NMR Spectra of Ligand-Protein Complexes

N. Rama Krishna,V. Jayalakshmi 한국자기공명학회 2002 Journal of the Korean Magnetic Resonance Society Vol.6 No.2

An interesting recent application of intermolecular NOE experiment is the saturation transfer difference NMR (STD-NMR) method that is useful in screening compound libraries to identify bio-active ligands. This technique also identifies the group epitopes of the bound ligand in a reversibly forming protein-ligand complex. We present here a complete relaxation and conformational exchange matrix (CORCEMA) theory (Moseley et al., J. Magn. Reson. B, 108, 243-261 (1995)) applicable for the STD-NMR experiment. Using some ideal model systems we have analyzed the factors that influence the STD intensity changes in the ligand proton NMR spectrum when the resonances from some protons on the receptor protein are saturated. These factors will be discussed and some examples of its application in some model systems will be presented. This CORCEMA theory for STD-NMR and the associated algorithm are useful in a quantitative interpretation of the STD-NMR effects, and are likely to be useful in structure-based drug design efforts. They are also useful in a quantitative characterization of protein-protein (or protein-nucleic acid) contact surfaces from an intermolecular cross-saturation NMR experiment 영어논문

Complete Relaxation and Conformational Exchange Matrix (CORCEMA) Analysis of Saturation Transfer Difference (STD) NMR Spectra of Ligand-Protein Complexes

Krishna, N.Rama,Jayalakshmi, V. Korean Magnetic Resonance Society 2002 Journal of the Korean Magnetic Resonance Society Vol.6 No.2

An interesting recent application of intermolecular NOE experiment is the saturation transfer difference NMR(STD-NMR) method that is useful in screening compound libraries to identify bio-active ligands. This technique also identifies the group epitopes of the bound ligand in a reversibly forming protein-ligand complex. We present here a complete relaxation and conformational exchange matrix (CORCEMA) theory (Moseley et al., J. Magn. Reson. B, 108, 243-261 (1995)) applicable for the STD-NMR experiment. Using some ideal model systems we have analyzed the factors that influence the STD intensity changes in the ligand proton NMR spectrum when the resonances from some protons on the receptor protein are saturated. These factors will be discussed and some examples of its application in some model systems will be presented. This CORCEMA theory for STD-NMR and the associated algorithm are useful in a quantitative interpretation of the STD-NMR effects, and are likely to be useful in structure-based drug design efforts. They are also useful in a quantitative characterization of protein-protein (or protein-nucleic acid) contact surfaces from an intermolecular cross-saturation NMR experiment.

Graphene and metal hybridized terahertz metasurfaces toward tunable plasmon-induced transparency effects

Krishna K. N. Indu,Devi K. Monika,Roy Chowdhury Dibakar 한국물리학회 2022 Current Applied Physics Vol.39 No.-

Tunable metasurfaces have attracted much attention recently, owing to their capability of actively controlling electromagnetic waves. Here, we propose tunable graphene-metal hybridized terahertz (THz) metasurfaces exhibiting plasmon induced transparency (PIT) effects, driven alternately by metal and graphene resonators. The proposed meta-molecule comprises a central metal (graphene) strip placed orthogonally to two side graphene (metal) strips. Then, near-field coupling between the strips is probed by translating the central strip along the length of the side strips and the evolution of the PIT effect is investigated for orthogonal polarizations of probing THz. The coupled oscillator-based analytical model explains the coupling mechanism in these metasystems. We observe the strongest coupling and the most prominent PIT effect for edge-to-edge coupling (threshold position) between the central and side strips. Further, active PIT response is achieved by altering graphene’s Fermi energy. These metasurfaces can contribute in designing compact and active metasurface-based hybrid devices for THz domain.

Novel pre-peroral endoscopic myotomy preparation for esophageal clearance: Simple yet effective!

Pankaj N. Desai,Chintan N. Patel,Mayank V. Kabrawala,Rajiv M. Mehta,Subhash K. Nandwani,Ritesh M. Prajapati,Nisharg B. Patel,Krishna K. Parekh 소화기인터벤션의학회 2021 International journal of gastrointestinal interven Vol.10 No.1

Background: Having a clean esophagus is an integral part of the peroral endoscopic myotomy (POEM) procedure for ensuring safety and success. Conventional preparation is a tricky, because there is no defined definite timeline of fasting for the different types of achalasia. The present study introduces a simple yet effective preparation of esophageal clearance. Methods: All patients who underwent POEM were included. Patients were stratified in novel and conventional preparation groups by a random selection. In the novel preparation, the cases were maintained on lukewarm water and carbonated drink followed by nil per oral (NPO) prior to the procedure. In conventional preparation, the controls were maintained on clear liquid followed by NPO. Success rate of preparation and procedure related outcomes were compared using independent t tests and chi-squared tests. Results: A total of 150 patients (male 54.0%; mean age 41.2 ± 15.5 years) were included in the study. Known baseline and clinical factors which could affect esophageal clearance were evenly distributed between the two groups. Novel preparation had provided absolute esophageal clearance (97.3%) without the requirement of pre-POEM endoscopic cleaning. Moreover, Novel preparation demonstrates several advantages over the conventional preparation: decreased anesthesia aspiration risk (P < 0.0001), reduced preoperative hospitalization (P < 0.0001), and hospital stays (P < 0.005). Conclusion: Evidently, the novel preparation is very simple, efficient, safe and appropriate for all types of achalasia. Moreover, novel preparation provides absolute esophageal clearance without requiring prolonged period of liquid diet, fasting and pre-POEM endoscopic cleaning.

Long Range and High Axial Load Capacity Nanopositioner Using Single Piezoelectric Actuator and Translating Supports

Bala Krishna Juluri,Wu Lin,Lennie E N Lim 한국정밀공학회 2007 International Journal of Precision Engineering and Vol.8 No.4

Existing long range piezoelectric motors with friction based transmission mechanisms are limited by the axial load capacity. To overcome this problem. a new linear piezoelectric motor using one piezoelectric actuator combined with a novel stepping mechanism is reported in this paper. To obtain both long range and fine accuracy, dual positioning control strategy consisting of coarse positioning and fine positioning is used. Coarse positioning is used for long travel range by accumulating motion steps obtained by piezoelectric actuator. This is followed by fine positioning where required accuracy is obtained by fine motion displacement of piezoelectric actuator. This prototype is able to provide resolution of 20 nanometers and withstand a maximum axial load of 300N. At maximum load condition, the positioner can move forward to a travel distance of 5mm at a maximum speed of 0.4 mm/sec. This design of nanopositioner can be used in applications for ultra precision positioning and grinding operations where high axial force capacity is required.

Foreign bodies in common bile duct in post cholecystectomy status—case series of 8 cases—A single center experience in western India

Pankaj N. Desai,Chintan N. Patel,Mayank V. Kabrawala,Subhash K. Nandwani,Rajiv M. Mehta,Parika Kalra,Ritesh Prajapati,Nisharg Patel,Krishna K. Parekh 소화기인터벤션의학회 2021 International journal of gastrointestinal interven Vol.10 No.2

Foreign bodies in common bile duct (CBD) are rare. Obstructive jaundice in patients who have undergone cholecystectomy may be due to a variety of causes. Common causes of obstruction in these cases are residual stones, inflammatory or ischaemic strictures following CBD injury during cholecystectomy or malignant strictures. Foreign bodies in the bile duct in these post cholecystectomy patients are known but reported very rarely. Clinical features and biochemistry of these patients are no different than those due to other causes mentioned above. Imaging studies will show obstruction due to stones or sludge or narrowing but may not give conclusive diagnosis of a foreign body. Endoscopic ultrasound is helpful in these cases as it shows a hyperechoic foreign body within the stone if the substance is a metallic clip. In our current case series, we are presenting eight such cases with post cholecystectomy foreign bodies, in the form of materials used for ligating or clipping the cystic duct before transection during cholecystectomy, or a mistakenly left behind gauze piece, migrating into the bile duct and forming a nidus for stone formation and causing CBD obstruction. To conclude, if a patient presents with biliary obstruction with a history of cholecystectomy, the possibility of foreign body in the CBD must be considered as a possible differential diagnosis.