Chemical effects induced by γ-irradiated Na2SO4 in aqueous ammonium nitrate

It is well known that paramagnetic centers are formed when Na₂SO₄ crystals are exposed to -radiation. The dissolution of such crystals in aqueous ammonium nitrate results in reduction of nitrate to nitrite. Various factors which influence the yield of nitrite are investigated. The yield of nitrite is found to vary with the amount of irradiated Na₂SO₄ added, the dose absorbed by Na₂SO₄ crystals, the storing period of the irradiated salt, photoannealing time, concentration of aqueous ammonium nitrate and particle size of the Na₂SO₄ crystals. The G(NO ₂ ^– ) value under optimum conditions of the conversion of nitrate to nitrite by irradiated Na₂SO₄ in aqueous ammonium nitrate is 0.009. The efficiency of energy transfer is 1.5%. The mechanism of reduction is based on the reactions of paramagnetic centers with nitrate ions.     

Mathematical Correction for Polyatomic Isobaric Spectral Interferences in Determination of Lanthanides by Inductively Coupled Plasma Mass Spectrometry

The determination of lanthanides by Inductively Coupled Plasma Mass Spectrometry (ICP‐MS) is complicated by several spectral overlaps from M⁺, MO⁺ or MOH⁺ ions formed in the ICP. Especially, it is essential to avoid the spectral interferences from lighter lanthanide and Ba polyatomic ions on middle or heavier lanthanides. To tackle this problem, we have developed a mathematical correction method, which reduces all the spectral overlaps from oxide species of Pr, Nd, Ce and Sm over Gd, Tb, Dy and Ho, and Gd, Tb over Yb and Lu. It can also successfully correct the oxide and hydroxide interference of Ba over Eu. The effectiveness of the proposed the mathematical correction scheme is demonstrated for the USGS Standard Rock samples AGV‐1 and G‐2. The results show that the experimental data obtained by applying the mathematical correction scheme for lanthanides is in good agreement with the reported values, using pneumatic and ultrasonic nebulisation methods, for their ICP‐MS analysis.     

Lyoluminescence of luminol in aqueous amines

Lyoluminescence of luminol induced by -irradiated NaCl has been studied in aqueous amines. The emission spectra of lyoluminescence are recorded on 400 ASA Kodak film using a Fuess spectrograph. A broad continuous emission band appears in the visible region from 390 to 500 nm. The emission band showed two peaks centered at 430 and 470 nm. The 430 nm peak is more intense in secondary amines while the 470 nm band is more intense in primary amines. The mechanism of light emission is based on the comparative study of lyoluminescence, fluorescence and chemiluminescence of luminol in aqueous amines.     

Determination of calcium and iron in silicon and uranium silicide using ion chromatography

Two separate ion chromatography methods were developed for the determination of calcium and iron in silicon and uranium silicide. A cation exchange separation with conductivity detection was developed for Ca. A reversed phase column modified with 50 mM camphor-10-sulphonic acid was used for separating Fe. Iron was detected photometrically. Linear calibrations for Ca (0.1–10 ppm) and Fe (0.5–25 ppm) were performed. Limits of detections for Ca and Fe are 0.03 and 0.2 ppm, respectively. The precision of the methods are better than 2 % for Ca at 0.2 ppm and Fe at 2 ppm.     

Efficient Synthesis of 1,4-Bis(5-aryl-1,3,4-oxadiazol-2-yl)-2,3,5,6-tetrafluorobenzenes

Russian Journal of Organic Chemistry - An efficient acid-catalyzed condensation between substituted benzohydrazides and 2,3,5,6-tetrafluoroterephthalic acid to form...     

Characterization of porosity in vapor-deposited amorphous solid water from methane adsorption

We have characterized the porosity of vapor-deposited amorphous solid water (ice) films deposited at 30-40 K using several complementary techniques such as quartz crystal microgravimetry, UV-visible interferometry, and infrared reflectance spectrometry in tandem with methane adsorption. The results, inferred from the gas adsorption isotherms, reveal the existence of microporosity in all vapor-deposited films condensed from both diffuse and collimated water vapor sources. Films deposited from a diffuse source show a step in the isotherms and much less adsorption at low pressures than films deposited from a collimated source with the difference increasing with film thickness. Ice films deposited from a collimated vapor source at 77 degrees incidence are mesoporous, in addition to having micropores. Remarkably, mesoporosity is retained upon warming to temperatures as high as 140 K where the ice crystallized. The binding energy distribution for methane adsorption in the micropores of ice films deposited from a collimated source peaks at approximately 0.083 eV for deposition at normal incidence and at approximately 0.077 eV for deposition at >45 degrees incidence. For microporous ice, the intensity of the infrared bands due to methane molecules on dangling OH bonds on pore surfaces increases linearly with methane uptake, up to saturation adsorption. This shows that the multilayer condensation of methane does not occur inside the micropores. Rather, filling of the core volume results from coating the pore walls with the first layer of methane, indicating pore widths below a few molecular diameters. For ice deposited at 77 degrees incidence, the increase in intensity of the dangling bond absorptions modified by methane adsorption departs from linearity at large uptakes.     

Comparative evaluation of three alpha-hydroxycarboxylic acids for the separation of lanthanides by dynamically modified reversed-phase high-performance liquid chromatography

The resolution for the three homologues of alpha-hydroxycarboxylic acids viz. lactic acid, alpha-hydroxyisobutyric acid (alpha-HIBA) and alpha-hydroxy-alpha-methylbutyric acid (alpha-H-alpha-MBA), was compared for the individual separation of 14 lanthanide elements under identical experimental conditions. Alpha-HIBA was found to be the best for separation of heavier lanthanides (Tb to Lu) while alpha-H-alpha-MBA led to a better separation for lighter lanthanides (La to Eu). All the 14 lanthanides were separated by gradient HPLC employing both alpha-HIBA and alpha-H-alpha-MBA so that there was reasonable resolution among all the peaks and the separation was completed in a short time.     

Two-Fluid Cosmological Models in Bianchi Type-V Space-Time

We have presented anisotropic, homogeneous two-fluid cosmological models using Bianchi type-V space-time. Here one fluid represents the matter content of the universe and another fluid is chosen to model the CMB radiation. The radiation and matter content of the universe are in interactive phase. Also we have discussed the behavior of fluid parameters and kinematical parameters.     

Bianchi Type-III Magnetized Wet Dark Fluid Cosmological Model in General Relativity

Bianchi type-III cosmological model of universe filled with dark energy from a wet dark fluid (WDF) in presence and absence of magnetic field is investigated in general theory of relativity. We assume that F ₁₂ is the only non-vanishing component of F _ij . We obtain exact solutions to the field equations using the condition that expansion is proportional to the shear scalar i.e. (B=C ⁿ ). The physical behavior of the model is discussed with and without magnetic field. We conclude that universe model do not approach isotropy through the evolution of the universe.     

Secondary ion mass spectrometry and X-ray photoelectron spectroscopy studies on TiO2 and nitrogen doped TiO2 thin films

Anatase phase TiO₂ and nitrogen (N) doped TiO₂ thin films were synthesized by an ultrasonic spray pyrolysis technique on c-Si (100) substrates in the temperature range 300-550 °C. The former used a precursor solution of titanium oxy acetylacetonate in methanol whereas the later used a titanium oxy acetylacetonate hexamine mixture in methanol. Homogeneity across the film’s thickness and the nature of the film-substrate interface were studied by dynamic depth profiling acquired using secondary ion mass spectrometry SIMS. The stoichiometry and bonding state of various species present in the films were studied using X-ray photoelectron spectroscopy (XPS). N-doping was confirmed by both SIMS and XPS. XPS studies revealed that the nitrogen content of the films synthesized at 300 °C (3.2%) is high compared to that of films made at 350 °C (1.3%).