排序方式: 共有24条查询结果,搜索用时 15 毫秒
1.
M. M. Charyulu K. Venugopal Chetty D. G. Phal Veena Sagar SagarD. M. Sagar S. M. Pawar R. Swarup V. V. Ramakrishna V. Venugopal 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(1):153-154
Recovery of americium from nitric acid solutions was studied by co-precipitation as hydroxide with various ions like calcium, ferric, nickel using sodium hydroxide and ammonium hydroxide. Studies were also carried out to recover americium using lanthanum fluoride and bismuth phosphate co-precipitation. All the methods are able to co-precipitate Am quantitatively. However, co-precipitation of Am with optimum concentration iron using ammonia is found to be better from nitric acid solutions containing large concentrations of calcium ions. Approximately 2 g of Am was recovered from 150 litres of solution batch wise using iron. 相似文献
2.
M. M. Charyulu D. G. Phal D. M. Noronha V. V. Ramakrishna V. Venugopal 《Journal of Radioanalytical and Nuclear Chemistry》2001,247(3):553-555
The extraction of Am(III) from nitric, hydrochloric, oxalic, phosphoric and hydrofluoric acids was studied using 0.4F di-2-ethyl hexyl phosphoric acid (HDEHP) containing 0.1M phosphorous pentoxide (P2O5) in dodecane/xylene. The extraction with pure 0.4F HDEHP was found to be negligible from all the media studied. However, the presence of a small amount of P2O5 in it increased the extraction substantially. The distribution ratios of Am(III) obtained for HDEHP - P2O5 mixture 3M nitric acid containing different concentrations of oxalic acid/phosphoric acid/hydrofluoric acid are in the order of 200-250. The same for 3M hydrochloric acid is very high (800). These distribution ratios are sufficiently high for the quantitative extraction of Am(III) from all the acid media studied. Different reagents such as ammonium oxalate, sodium oxalate, oxalic acid, hydrofluoric acid, sodium carbonate and potassium sulphate were explored for the back extraction of Am(III) from 0.4F HDEHP + 0.1M P2O5 in dodecane/xylene. Of these, 0.35M ammonium oxalate and 1M sodium carbonate were found to be most suitable. The back extraction of Am(III) was also attempted with water and 1M H2SO4, HNO3, HClO4 and HCl solutions after allowing the extracted organics to degrade on its own. It was found that more than 90% of Am could be back extracted with these acids. Using this method more than 90% of Am(III) was recovered from nitric acid solutions containing calcium and fluoride ions. 相似文献
3.
K.C. Devarayapalli S.V. Prabhakar Vattikuti T.V.M. Sreekanth Ki Soo Yoo P.C. Nagajyothi Jaesool Shim 《应用有机金属化学》2020,34(3):e5376
Herein, cobalt (Co)-based metal–organic zeolitic imidazole frameworks (ZIF-67) coupled with g-C3N4 nanosheets synthesized via a simple microwave irradiation method. SEM, TEM and HR-TEM results showed that ZIF-67 were uniformly dispersed on g-C3N4 surfaces and had a rhombic dodecahedron shape. The photocatalytic properties of g-C3N4/ZIF-67 nanocomposite were evaluated by photocatalytic dye degradation of crystal violet (CV), 4-chlorophenol (4-CP) and photocatalytic hydrogen (H2) production. In presence of visible light illumination, the photocatalytic dye results showed that 95% CV degradation and 53% 4-CP degradation within 80 min. The H2 production of the g-C3N4/ZIF-67 composite was 2084 μmol g−1, which is 3.84 folds greater than that of bare g-C3N4 (541 μmol g−1). 相似文献
4.
Kamakshaiah S. Rau R. S. N. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1977,5(3):164-170
The firing characteristics of the simple triggered vacuum gap (TVG) using lead zirconate titanate as dielectric material in the triggered gap are described. This TVG has a long life of about 2000 firings without appreciable deterioration of the electrical properties for main discharge currents upto 3 kA and is much superior to these made with Supramica (Mycalex Corporation of America) and silicon carbide as used in our earlier investigations. The effects of the variation of trigger voltage, trigger curcit, trigger pulse duration, trigger pulse energy, main gap voltage, main gap separation and main circuit energy on the firing characteristics have been studied. Trigger resistance progressively decreases with the number of firings of the trigger gap and as well as of the main gap. This decrease in the trigger resistance is more pronounced for main discharge currents exceeding 10 kA. The minimum trigger current required for reliable firing decreases with increase of trigger voltage upto a threshold value of 1.2 kV and there-onwards saturates at 3.0 A. This value is less than that obtained with Supramica as dielectric material. One hundred percent firing probability of the TVG at main gap voltages as low as 50 V is possible and this low voltage breakdown of the main gap appears to be similar to the breakdown at low pressures between moving plasma by other workers. and the cold electrodes immersed in it, as reported 相似文献
5.
6.
Kamisetty NK Pack SP Nonogawa M Devarayapalli KC Kodaki T Makino K 《Analytical and bioanalytical chemistry》2006,386(6):1649-1655
Aminosilane-treated molecular layers on glass surfaces are frequently used as functional platforms for biosensor preparation.
All the amino groups present on the surface are not available in reactive forms, because surface amino groups interact with
remaining unreacted surface silanol groups. Such nonspecific interactions might reduce the efficiency of chemical immobilization
of biomolecules such as DNA, enzymes, antibodies, etc., in biosensor fabrication. To improve immobilization efficiency we
have used additional surface silanization with alkylsilane (capping) to convert the remaining silanol groups into Si–O–Si
linkages, thereby liberating the amino groups from nonspecific interaction with the silanol groups. We prepared different
types of capped amine surface and evaluated the effect of capping on immobilization efficiency by investigating the fluorescence
intensity of Cy3-NHS (N-hydroxysuccinimide) dye that reacted with amino groups. The results indicate that most of the capped amine surfaces resulted
in enhanced efficiency of immobilization of Cy3-NHS compared with the untreated control amine surface. We found a trend that
trialkoxysilanes had greater capping effects on immobilization efficiency than monoalkoxysilanes. It was also found that the
aliphatic chain of alkylsilane, which does not participate in the capping of the silanol, had an important function in enhancing
immobilization efficiency. These results would be useful for preparation of an amine-modified surface platform, with enhanced
immobilization efficiency, which is essential for developing many kinds of biosensors on a silica matrix.
Enhancement of amine funtionality by capping with alkylsilane 相似文献
7.
Kamisetty NK Pack SP Nonogawa M Devarayapalli KC Watanabe S Kodaki T Makino K 《Analytical and bioanalytical chemistry》2007,387(6):2027-2035
Amine-modified oligodeoxynucleotides (AMO) are commonly used probe oligodeoxynucleotides for DNA microarray preparation. Two
methods are currently used for AMO preparation—use of amine phosphoramidites protected by acid-labile monomethoxytrityl (MMT)
groups or alkali-labile trifluoroacetyl (TFA) groups. Because conventional AMO preparation procedures have defects, for example
stringent acidic conditions are required for deprotection of MMT and hydrophobic purification cannot be used for TFA-protected
amino groups, conventional preparation of AMO is unlikely to result in the expected outcome. In this paper a method of AMO
synthesis using modified H-phosphonate chemistry is suggested. An aliphatic diamine is coupled with a phosphonate group forming
a phosphoramidate linkage to the last internucleotide phosphate of oligodeoxynucleotides. In this method dimethoxytrityl (DMT)
purification steps are used and stringent acid deprotection is not required to obtain the AMO. Although the method could lead
to formation of AMO diastereomers, melting-temperature and CD analysis showed for two AMO that DNA duplex formation was the
same as when normal oligodeoxynucleotides were used. Also, when these AMO were used as probes for DNA microarrays the immobilization
efficiency was similar to that for AMO probes prepared by conventional means using an amino-modifier unit. The hybridization
performance of these AMO was better than for those prepared conventionally. The procedures suggested would be useful for preparation
of efficient AMO for fabrication of DNA microarrays and DNA-based nanoparticle systems.
Nagendra Kumar Kamisetty and Seung Pil Pack have equally contributed to this work. 相似文献
8.
Rao KS Rani SU Charyulu DK Kumar KN Lee BK Lee HY Kawai T 《Analytica chimica acta》2006,576(2):177-183
A novel approach for immobilization of probe oligonucleotides that uses zirconium phosphate modified silica nanoparticles is proposed. The surface modification of nanoparticles was carried out in two stages. Initially binding of Zr4+ to the surface of silica nanoparticles and later treated with phosphoric acid for terminal phosphate groups. Oligonucleotide probes modified with amine group at 5'-end were strongly binds to the phosphate terminated silica nanoparticles with imidazole in presence of 0.1 mol L(-1) EDC [N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide], as phosphate groups are more reactive towards amine group. Various studies, i.e., synthesis of silica nanoparticles, their surface modification, probe immobilization, measurement of hybridization and effect of bovine serum albumin (BSA) were carried out during optimization of reaction conditions. The significant reduction in the background signal was observed by treating the probe modified silica nanoparticles with bovine serum albumin prior to hybridization. The probe modified silica nanoparticles were retained their properties and the hybridization was induced by exposure of single-stranded DNA (ssDNA) containing silica nanoparticles to the complementary DNA in solution. The decrease in the fluorescence signal for one mismatch and three mismatch was observed upon hybridization of probe with target DNAs, while there was no response for the random target ssDNA under the same experimental conditions. The intensity of fluorescence signal was linear to the concentration of target DNA ranging from 3.9 x 10(-9) to 3.0 x 10(-6)mol L(-1). A detection limit of 1.22 x 10(-9) mol L(-1) of oligonucleotides can be estimated. The proposed hybridization assay is simple and possesses good analytical characteristics and it can provide an effective and efficient route in the development of DNA biosensors and biochips. 相似文献
9.
G. V. Rathaiah J. Krishnama Charyulu M. C. Eshwar 《Journal of Radioanalytical and Nuclear Chemistry》1986,99(2):337-344
Uranium(VI) reacts with 1-(2-thiazolylazo)-2-naphthol to form a red-coloured chelate in the pH range 5.3–7.2, maintained by 0.04 M acetate buffer. Absorbance of the sparingly soluble complex, solubilized and stabilized by Triton X-100, is measured after 30 min and it is stable for at least 16 hours. The complex exhibits maximum absorbance at 575 and 625–630 nm, but absorbance at longer wavelengths is not stable. The 12 complex obeys Beer's law over the concentration range 0.4–6.4 g of uranium(VI) per cm3, has molar absorptivity 3.36·104 dm3·mol–1·cm–1, Sandell sensitivity 7.0 ng·cm–2, formation constant (log K) 9.32 and coefficient of variation ±0.77%. Effect of 60 ions has been studied and selectivity improved considerably in presence of CDTA. The method has been applied for determination of uranium content in a rock sample. 相似文献
10.
I. C. Pius M. M. Charyulu C. K. Sivaramakrishnan S. K. Patil 《Journal of Radioanalytical and Nuclear Chemistry》1994,186(5):385-392
The extraction of Pu(IV) from oxalic acid-nitric acid mixtures has been investigated using a liquid anion exchanger, Aliquat-336, in xylene. The presence of oxalic acid is known to have adverse effects on the extraction of Pu(IV) by Aliquat-336. The use of cations, Al(III), Fe(III) or Zr(IV) was explored to overcome the effect of oxalic acid on Pu(IV) extraction. The data obtained reveal that Pu(IV) is quantitatively extracted by Aliquat-336, even in the presence of oxalic acid, when Al(III), Fe(III) or Zr(IV) is added. The extracted Pu(IV) can be back-extracted using aqueous ammonium carbonate. 相似文献