Band gap narrowing and fluorescence properties of nickel doped SnO2 nanoparticles

Nickel-doped tin oxide nanoparticles (sub-5 nm size) with intense fluorescence emission behavior have been synthesized by sol-gel route. The structural and compositional analysis has been carried out by using XRD, TEM, FESEM and EDAX. The optical absorbance spectra indicate a band gap narrowing effect and it was found to increase with the increase in nickel concentration. The band gap narrowing at low dopant concentration (<5%) can be assigned to SnO₂−SnO_2−x alloying effect and for higher doping it may be due to the formation of defect sub-bands below the conduction band.     

Scattering of electromagnetic wave from perfect electromagnetic conductor cylinders placed in un-magnetized isotropic plasma medium

The two dimensional analytical formulation of scattering of electromagnetic wave from a perfect electromagnetic conductor (PEMC) cylinder placed in un-magnetized isotropic plasma medium is presented. The extended classical scattering theory is used. The incident wave is taken as linearly polarized wave. The analytical theory is formulated for parallel polarization (TM) and also for perpendicular polarization (TE). The numerical computation results show that backscattering and forward scattering are sensitive to electron density and effective collision frequency of plasma medium. We placed different types of cylinders (PEC, PMC and PEMC) in un-magnetized plasma medium and concluded that stealth capability of plasma increases with the placement of PEMC cylinder in plasma medium.     

State selective laser photodissociation of Tl2 at 337.1 nm by optogalvanic spectroscopy

This paper reports the first time achievement of laser photolysis of thallium dimers by single photon absorption of N₂-laser light at 337.1 nm resulting in a large population inversion of thallium 7 ²S excited state with respect to 6 ²P state. The photodissociation nitrogen laser pulse is spatially and temporally overlapped with the tunable dye laser pulse that is used for confirming the production of selectively excited thallium atoms. The dye laser excites the thallium atoms from 7 ²S state to high lying Rydberg states that collisionally ionize giving an ion-current signal which is subsequently processed by a box-car average/integrator and recorded on the chart recorder. The photodissociation of Tl₂ to Tl(7 ²S ) state demonstrates the existence of the molecular dissociative state 1g that is correlated with Tl 7 ²S +6 ²P states. A complete absence of 6 ²P state population among the photolysis products indicates a 100% prompt population inversion between 7 ²S and 6 ²P atomic states.     

Oil constituents of Artemisia nilagirica var. septentrionalis growing at different altitudes

Oils of Artemisia nilagirica var. septentrionalis plants growing at different altitudes in Himachal Pradesh, India were hydro-distilled and analyzed by GC-GC/MS. The major constituents of the oil show variation with changes in altitude. At lower, middle and higher altitudes, the major constituents of the oil were caryophyllene oxide (28.6%), borneol (35.8%) and camphor (46.9%), respectively. The percentages of alpha-humulene and trans-beta-guaiene also increased, but the percentage of sabinene, trans-sabinene hydrate, 4-terpineol, caryophyllene oxide and humulene epoxide-II decreased with an increase in altitude. The characteristic compounds observed in the plants from lower altitudes were 2-hexene-1-ol, beta-thujone, thujanol, myrtenol and linalyl acetate, while the higher altitude plants were characterized by the presence of alpha-pinene, beta-pinene, limonene, linalool, gamma-gurijunene, germacrene-D and farnesol.     

Electrochemical Sensing of Ascorbic Acid,Hydrogen Peroxide and Glucose by Bimetallic (Fe,Ni)−CNTs Composite Modified Electrode

In this research, bimetallic supported CNT modified electrode ( Fe,Ni/CNTs/GCE) has been developed for sensitive, stable and highly elctroactive sensing of glucose, ascorbic acid and hydrogen peroxide. Transition metals such as Iron (Fe) and Nickel (Ni) offer high electrical and thermal conductance, high active surface‐to‐volume ratio and presence of d‐band electrons gives enhanced electrocatalytic behavior. While, CNTs provide high surface area, stability and excellent conductivity. Synthesized material is characterized by SEM, EDS, XRD and FTIR to access morphology, elemental composition and structure. This unique combination is employed for the electrochemical sensing of ascorbic acid, glucose and hydrogen peroxide and different experimental parameters are optimized. Fe,Ni/CNTs/GCE shows good sensing efficiency at pH 7.4 which is ideally suitable for variety of analytes. The modified electrode also show good reproducibility and sensitivity under optimized conditions and can be reused upto 30 cycles without compromising the efficiency. With good linearity, reproducibility and limit of detection, this material possess significant potential as non‐enzymatic biosensor for variety of analytes.     

Magneto-Priming Improved Nutraceutical Potential and Antimicrobial Activity of Momordica charantia L. Without Affecting Nutritive Value

The need for some economic strategies for increased growth and nutraceuticals of medicinal plants is well acknowledged now. It was hypothesized that external magnetic field treatment (MFT) of seeds affecting internal magnet of cells may affect growth and metabolism. In this study, seeds were subjected to pre-sowing magnetic field (50 mT at 5 mm for 5 s). At vegetative stage, the leaf growth, chlorophyll content, catalase (CAT), peroxidase (POD), amino acids, proteins, flavonoids, soluble sugars, total soluble phenolics, carotenoids, anthocyanins, phenolic profile (HPLC based), and antimicrobial activity of leaves (in terms of the minimum inhibitory concentration against Staphylococcus aureus and Pseudomonas aeruginosa) were studied. Yield was evaluated for nutritive components in fruit (peel+pulp) and peel. MFT improved germination percentage, growth, leaf chlorophyll, antimicrobial activity, peel amino acids, phenolics, and POD with negligible effect on fruit nutritive value. Moreover, photosynthetic pigments and cinnamic acid exhibited direct correlation with antimicrobial potential against both pathogens. However, sinapic acid showed positive correlation against Staphylococcus aureus only. Cinnamic acid, coumaric acid, syringic acid, and quercetin were in direct correlation against Pseudomonas aeruginosa; it was directly correlated with total flavonoids too. In conclusion, magnetic field can be used to manipulate plant cell metabolism promising improvement of growth, antimicrobial activity, and phenolics of interest.

     

Fractional dual solutions to the Maxwell equations in chiral nihility medium

Solutions which seem as the dual solutions to the original solution of the Maxwell equations for chiral nihility medium are listed. Using operators composed of fractional curl, solutions to the Maxwell equations which may be regarded as intermediate step between the original solution and dual to the original solution are determined. Dual solutions which are not valid have been pointed out.     

Mixed insoluble acidic salts of tetravalent metals VI. Crystalline mixed zirconium-titanium arsenate and hafnium-titanium arsenate

Mixed crystalline zirconium-titanium arsenates Zr_xTi(_1–x) (HAsO₄)₂·H₂O and harnium-titanium arsenates Hf_xTi(_1–x) (HAsO₄)₂ H₂O (where x=0–1) of various compositions with different Zr/Ti or Hf/Ti ratios have been prepared. The compounds have been characterized by X-ray, thermal analysis, chemical analysis, and pH-titrations. For powder X-rays, the compounds appear to be homogeneous crystalline materials with structures similar to -ZrP, -TiP or -ZrTiP. The thermograms show a loss of approximately two moles of H₂O, followed by a small loss of O₂ with probable formation of ZrO₂, As₂O₃, HfO₂, As₂O₃, ZrO₂, As₂O₅, HfO₂, As₂O₅ from which As₂O₃ and As₂O₅ are practically sublimed in two steps. The exchange capacities at r.t. are generally similar to -ZrP and -TiP but are found to be much lower in value.     

The non-crossing rule in molecular quantum mechanics

Previous mathematical proofs of the non-crossing rule concerning the potential energy curves of a diatomic molecule are examined and criticised. A new treatment is presented which is simple and mathematically rigorous.     

Expeditious implementation of two new methods for analysing the pigment composition of photosynthetic specimens

Two new methods for analysing the pigment composition of photosynthetic samples have been developed during the last few years. One, called the spectral reconstruction method, uses linear least-squares fitting, while the other, named the Gauss-peak spectra method, entails non-linear optimisation; each has some advantages over the other, but both use a large number of data points and surpass the traditional method which uses absorbance at a few wavelengths. In order to make the new methods transparent to experimentalists who are not well versed in statistical analysis, curve fitting and interpolation, simple procedures are described for implementing the methods with the aid of a spreadsheet. The problem of analysing a sample containing chlorophyll c, which is difficult to isolate in a form sufficiently pure to serve as an analytical standard, is also briefly addressed.