Characteristics of electron cyclotron resonance plasma formed by lower hybrid current drive grill antenna

A 3.7 GHz system, which is meant for LHCD experiments on ADITYA tokamak, is used for producing ECR discharge. The ECR discharge is produced by setting the appropriate resonance magnetic field of 0.13 T, with hydrogen at a fill pressure of about 5 × 10⁻⁵ Torr. The RF power, up to 10 kW (of which ∼50% is reflected back), with a typical pulse length of 50 ms, is injected into the vacuum chamber of the ADITYA tokamak by a LHCD grill antenna and is used for plasma formation. The average coupled RF power density (the RF power/a typical volume of the plasma) is estimated to be ∼5 kW/m³. When the ECR appears inside the tokamak chamber for the given pumping frequency (f = 3.7 GHz) a plasma with a density (n _e) ∼ 4 × 10¹⁶ m⁻³ and electron temperature ∼8 eV is produced. The density and temperature during the RF pulse are measured by sets of Langmuir probes, located toroidally, on either side of the antenna. H_α signals are also monitored to detect ionization. An estimate of density and temperature based on simple theoretical calculation agrees well with our experimental measurements. The plasma produced by the above mechanism is further used to characterize the ECR-assisted low voltage Ohmic start-up discharges. During this part of the experiments, Ohmic plasma is formed using capacitor banks. The plasma loop voltage is gradually decreased, till the discharge ceases to form. The same is repeated in the presence of ECR-formed plasma (RF pre-ionization), formed 10 ms prior to the loop voltage. We have observed that (with LHCD-induced) ECR-assisted Ohmic start-up discharges is reliably and repeatedly obtained with reduced loop voltage requirement and breakdown time decreases substantially. The current ramp-up rates also decrease with reduced loop voltage operation. These studies established that ECR plasma formed with LHCD system exhibits similar characteristics as reported earlier by dedicated ECR systems. This experiment also addresses the issue of whether ECR plasma formed with grill antenna exhibits similar behavior as that formed by single waveguide ECR antenna. Our experimental observations suggest that the characteristics of (LHCD system-induced) ECR-assisted Ohmic start-up discharges show similar properties, reported earlier with normal ECR-assisted Ohmic start-up discharges and hence LHCD system may be used as ECR system at reduced toroidal magnetic field for other applications like wall conditioning.      

Biological Components and Bioelectronic Interfaces of Water Splitting Photoelectrodes for Solar Hydrogen Production

Artificial photosynthesis (AP) is inspired by photosynthesis in nature. In AP, solar hydrogen can be produced by water splitting in photoelectrochemical cells (PEC). The necessary photoelectrodes are inorganic semiconductors. Light‐harvesting proteins and biocatalysts can be coupled with these photoelectrodes and thus form bioelectronic interfaces. We expand this concept toward PEC devices with vital bio‐organic components and interfaces, and their integration into the built environment.     

An ambient temperature Sonogashira cross-coupling protocol using 4-aminobenzoic acid as promoter under copper and amine free conditions

A new methodology has been developed based on Pd(OAc)₂ and 4-aminobenzoic acid catalytic system for the Sonogashira cross-coupling reaction at ambient temperature under copper and amine free conditions. The newly developed catalytic system is conveniently applicable to the aryl iodides and terminal acetylenes. The catalytic system is much efficient because of the use of easily available and low cost additive.     

Portraying the selectivity of GSK-3 inhibitors towards CDK-2 by 3D similarity and molecular docking

Structural Chemistry - The striking structural resemblance between adenosine triphosphate (ATP) binding sites of glycogen synthase kinase-3 (GSK-3) and cyclin-dependent kinase-2 (CDK-2) raises...     

The Role of Sulphonamides and N-Sulphonyl Ketimines/Aldimines as Directing Groups in the Field of C−H Activation

Sulphonamides and N-sulphonyl ketimines/aldimines have turned out to be versatile motifs in the field of synthetic and medicinal chemistry. The field of C−H activation/functionalization flourished remarkably due to their synthetic applicability and directing group plays a remarkable role to achieve regioselectivity in these reactions. The current review summarizes recent tactics by utilizing sulphonamides and N-sulphonyl ketimines/aldimines as directing groups for C−H activation or functionalization. As a directing group, they also facilitate site selectivity and late-stage functionalization of drug molecules in order to construct complex scaffolds of therapeutic importance by C−H activation.     

Structural, thermal and spectroscopic properties of supramolecular coordination solids

Molecules in metal isonicotinate tetrahydrates, M(NC₅H₄-p-CO₂)₂.4H₂O with M = Mn, Fe, Co, Ni, Cu, Zn, consisting of the hexacoordinate complexestrans-[M(NC₅H₄-p-CO₂)(OH₂)₄], participate in exhaustive hydrogen-bond formation among themselves to lead to a robust 3D supramolecular network in the solid state. Solid-state diffuse reflectance UV-Vis-NIR spectra of the complexes have been assigned to ligand field and charge transfer transitions. Sharp weight loss due to dehydration, as shown by TGA of Cu(NC₅H₄-p-CO₂)₂.4H₂O, suggests the suitability of this complex for the gravimetric estimation of copper.     

Composition of Essential Oil from the Aerial Part of Aster peduncularis

Chemistry of Natural Compounds -     

Photocatalytic decolouration,degradation and disinfection capability of Ag2CO3/ZnO in natural sunlight

In this study, a series of hybrid Ag₂CO₃/ZnO composites were synthesised via a simple precipitation route and investigated for discolouration-degradation of Methylene Blue and disinfection of Escherichia coli in natural sunlight. It was observed that the photonic efficiency of discolouration was more than 6 times that of the conventionally popular TiO₂, under experimental conditions; 100% Total Organic Carbon reduction was observed in 30 ?min and 32% disinfection in an hour. This upswing in the performance is attributed to favourable modulation of the dynamics of charge transfer. The photocatalysts were characterized by X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Brunauer, Emmett and Teller and Ultraviolet–Visible-Near-InfraRed Spectroscopy. An equitable photocatalyst functional mechanism has also been proposed on the basis of Tauc plot and scavenging experiments. The effect of influencing parameters has also been investigated and reported in terms of photonic efficiency. Since the entire study is carried out in direct sunlight, it inherently supports realizable solar energy applications in wastewater treatment.     

Synthesis and Crystal Structure Determination of Dimeric Co(II) and Ni(II) with Pyridine 2,6-Dicarboxylic Acid

Abstract  

Two new dimeric complexes of Ni and Co with pyridine 2,6-dicarboxylic acid were synthesized, the structure of both these complexes were determined by single crystal X-ray crystallography and was characterized spectrally with the help of IR and UV spectrometers and the magnetic moments of both the reported complexes were recorded. Both of these complexes crystallize in the monoclinic space group P 2₁/c1. For the dimeric cobalt complex, formula C₁₄ H₂₁ Co₂ N₂ O₁₅; a = 8.3950(3) ?; α = 90°, b = 27.3702(8) ?; β = 98.211(2)°, c = 9.6235(3) ?; γ = 90° and Z = 3. For the dimeric Nickel complex, formula C₁₄ H₂₁ Ni₂ N₂ O₁₅, a = 8.330(10) A; α = 90°, b = 27.266(5) A; β = 98.61(10)^o, c = 9.653(10) A; γ = 90° and Z = 4. Both the dimeric complexes were observed to be hexa-coordinated with two different types of donor atoms (nitrogen and oxygen). Details of the synthesis, structures and spectroscopic properties have been discussed.