Improvement in the determination of traces of uranium in aqueous medium having high dissolved organic carbon and chloride ion by alpha-spectrometry

During this work the determination of uranium in the range of μg·L⁻¹ to tens of μg·L⁻¹ was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH₄)₂SO₄ as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH₄)₂SO₄ and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry (AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having dissolved organic carbon (DOC) more than 15 mg·L⁻¹ and Cl⁻ concentration is in the range of 40,000 μ·g⁻¹. In the case of spike experiments with ²³²U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl⁻ and DOC as indicated above.     

Visible spectrum of titanium dioxide

The electronic spectrum in the region 17?500 cm(-1) to 18?850 cm(-1) of a cold molecular beam of TiO(2) has been investigated using laser induced fluorescence (LIF) and mass-resolved resonance enhanced multi-photoionization (REMPI) spectroscopy. Bands at 18?412 cm(-1), 18?470 cm(-1) and 18?655 cm(-1) were recorded at a resolution of 35 MHz, rotationally analyzed, and assigned as the ?(1)B(2) (0,1,2) ←X[combining tilde](1)A(1) (0,0,0), ?(1)B(2) (1,0,0) ←X[combining tilde](1)A(1) (0,0,0) and ?(1)B(2) (1,1,0) ←X[combining tilde](1)A(1) (0,0,0) transitions. The dispersed fluorescence from the ?(1)B(2) (0,1,2) and ?(1)B(2) (1,0,0) levels were combined with previous results to produce an improved set of vibrational parameters for the X[combining tilde](1)A(1) state. The optical Stark effect in the ?(1)B(2) (0,1,2) ←X[combining tilde](1)A(1) (0,0,0) and ?(1)B(2) (1,0,0) ←X[combining tilde](1)A(1) (0,0,0) bands were recorded and combined with earlier results for ?(1)B(2) (1,1,0) ←X[combining tilde](1)A(1) (0,0,0) to determine the permanent electric dipole moment for these states. The origin and harmonic vibrational constants for the ?(1)B(2) state are determined to be: T(000) = 17?593(5) cm(-1), ω(1) = 876(3) cm(-1), ω(2) = 184(1) cm(-1), and ω(3) = 316(2) cm(-1). A normal coordinate analysis was performed and Franck-Condon factors calculated.     

Recognition of adenosine monophosphate and H2PO4- using zinc ensemble of new hexaphenylbenzene derivative: potential bioprobe and multichannel keypad system

Zinc ensemble of hexaphenylbenzene derivative 3 exhibits sensitive response toward adenosine monophosphate (AMP) and H(2)PO(4)(-) ions. Further, the application of derivative 3 as a multichannel molecular keypad could be realized in the presence of inputs of Zn(2+) ions, H(2)PO(4)(-) ions, and AMP.     

Electron beam induced green luminescence and degradation study of CaS:Ce nanocrystalline phosphors for FED applications

Green luminescence and degradation of Ce³⁺ doped CaS nanocrystalline phosphors were studied with a 2 keV, 10 μA electron beam in an O₂ environment. The nanophosphors were synthesized by the co-precipitation method. The samples were characterized using X-ray diffraction, Transmission electron microscopy, Scanning electron microscopy/electron dispersive X-ray spectroscopy and Photoluminescence (PL) spectroscopy. Cubic CaS with an average particle size of 42 ± 2 nm was obtained. PL emission was observed at 507 nm and a shoulder at 560 nm with an excitation wavelength of 460 nm. Auger electron spectroscopy and Cathodoluminescence (CL) were used to monitor the changes in the surface composition of the CaS:Ce³⁺ nanocrystalline phosphors during electron bombardment in an O₂ environment. The effect of different oxygen pressures ranging from 1 × 10⁻⁸ to 1 × 10⁻⁶ Torr on the CL intensity was also investigated. A CaSO₄ layer was observed on the surface after the electron beam degradation. The CL intensity was found to decrease up to 30% of its original intensity at 1 × 10⁻⁶ Torr oxygen pressure after an electron dose of 50 C/cm². The formation of oxygen defects during electron bombardment may also be responsible for the decrease in CL intensity.     

Lithium perchlorate-induced electrophilic activation: one-pot synthesis of 3-aryl-2-thioxotetrahydropyrimidin-4-one derivatives from aryl isothiocyanates

A novel methodology for the synthesis of N-substituted-3-aryl-2-thioxotetrahydropyrimidin-4(1H)-one derivatives had been developed by the condensation of aryl isothiocyanates with β-amino esters using lithium perchlorate as a catalyst and triethylamine as a base. This strategy not only overcomes the disadvantages of the reported methods but also provides high yield of the product in short span of time by an easily workable procedure.     

Experimental investigation of the performance of an indirect-mode natural convection solar dryer for drying fenugreek leaves

The main objectives of the present work are firstly to study and compare the thin layer drying characteristics of fenugreek leaves by open sun and solar drying methods, and secondly to select a mathematical model for describing the drying process under open sun and solar drying of fenugreek leaves using thin layer drying models available in the literature. Eight thin layer drying models, which are empirical or semi-empirical, are tested to validate the experimental data. A non-linear regression analysis using a statistical computer programme is used to evaluate the constants of the models. The performance of the models was investigated by comparing the coefficient of correlation (R ²), sum of squares error (SSE), mean squared error (MSE) and root mean square error (RMSE) between observed and predicted moisture ratios. According to results, Wang and Singh model gives the highest value of R ² and the lowest values of SSE, MSE and RMSE. Therefore, Wang and Singh model is the best for explaining drying behaviour of fenugreek leaves in both the trays inside the solar dryer and in the tray under open sun.     

A Convenient Synthesis of 3-Behzyl, 3-Benzyl-4-Substituted Coumarins and Their Benzo Derivatives

It is reported in the literature that alkylation of simple (unsubstituted) phosphorane with alkyl halide in ethyl acetate leads to equimolar mixture of alkylated phosphorane and salt of the unsubstituted phosphorane. Here we report exclusive formation of alkylated phosphorane from its salt from benzyl bromide in chloroform. This alkylated phosphorane (2) on reaction with 2-hydroxy carbony1 compounds (1a-1) provide E-ethyl Oc-benzyl cinnamates in high yields which on thermal cyclisation gave 3-benzylf 3-benzyl-4-substituted and benzocoumarins. Thus this method can be used conveniently to synthesise above compounds in good yields.     

Novel Copolymers of Styrene. 6. Some Oxy Ring-Disubstituted Butyl 2-Cyano-3-Phenyl-2-Propenoates

Novel trisubstituted ethylenes, oxy ring-disubstituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO₂C₄H₉ (where R is 4-methoxy-2-methyl, 4-methoxy-3-methyl, 3-ethoxy-4-methoxy, 4-ethoxy-3-methoxy, 3,4-dibenzyloxy, 2-benzyloxy-3-methoxy, and 3-benzyloxy-4-methoxy) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR.

Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500°C range with residue (2-17 % wt.), which then decomposed in the 500-800°C range.     

Multi-instrument characterization of HiPIMS and DC magnetron sputtered tungsten and copper films

In this work, copper and tungsten were sputtered onto silicon wafers by direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). The resulting films were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and X-ray diffraction (XRD). By EDX and XPS, all the sputtered films showed only the expected metal peaks. By XPS, the surfaces sputtered by DCMS were richer in oxygen than those produced by HiPIMS. By AFM, the surfaces were quite smooth. The root mean square (RMS) roughness values are as follows: 0.83 nm (W, HiPIMS), 1.10 nm (W, DCMS), 0.85 nm (Cu, HiPIMS), and 1.78 nm (Cu, DCMS). By SEM, the HiPIMS films exhibited smaller grain sizes, which was confirmed by XRD. The crystallite sizes estimated by XRD are as follows: 4 nm (W, body-centered cubic, HiPIMS), 13 nm (W, body-centered cubic, DCMS), 7 nm (W, cubic, HiPIMS), 14 nm (W, cubic, DCMS), 25 nm (Cu, HiPIMS), and 35 nm (Cu, DCMS). By SE, the HiPIMS surfaces showed higher refractive indices, which suggested that they were denser and less oxidized than the DCMS surfaces.