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731.
The study describes the preparation of Cu(II)‐immobilized copolymer(CIC) under optimum conditions for the effective removal of urea. The copolymeric hydrogels, synthesized by free‐radical aqueous copolymerization of monomers acrylamide and sodium acrylate, have been analyzed for their Cu(II) uptake behavior. The sorption of Cu(II) into polymer follows a Langmuir–type pattern and amount sorbed depends upon the composition of copolymeric gels, presence of other co‐ions in the solution, pH of the solution, initial concentration of sorbate, degree of crosslinking of the copolymeric hydrogel, temperature of the solution etc. In the preliminary study, the Cu(II) immobilized co‐polymer(CIC) sorbent demonstrated a fair tendency to remove urea from aqueous solutions. 相似文献
732.
Chhavi?AgarwalEmail author P.?C.?Kalsi D.?R.?Prabhu P.?N.?Pathak V.?K.?Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):749-752
The estimation of low level alpha activity is difficult in waste samples containing large concentration of salts and beta–gamma
activity. In the present study, the feasibility of gross alpha-activity measurement for simulated high level waste (SHLW)
in solution medium by alpha-track registration technique has been attempted. The results showed that it is possible to use
this technique for gross alpha-activity estimation of ~200 Bq/mL in solution medium with a precision and accuracy of ~30%.
The importance of measuring 200 Bq/mL alpha activity in SHLW solutions is that this value corresponds to about 4,000 Bq/g
activity in the solid medium which is the safe disposable limit. The advantage of this method over other methods is that it
is not sensitive to beta–gamma emitters and salts and is very simple and inexpensive. 相似文献
733.
R. B. Gujar S. A. Ansari A. Bhattacharyya P. K. Mohapatra A. S. Kanekar P. N. Pathak V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(2):621-627
The radiolytic stability of a branched diglycolamide extractant, namely N,N,N′,N′-tetra-2-ethylhexyl diglycolamide (T2EHDGA) dissolved in n-dodecane containing several phase modifiers, viz. N,N-dihexyloctanamide (DHOA), tri-n-butyl phosphate (TBP), 1-decanol and iso-decanol has been investigated. The distribution ratio of Am(III) decreased with
increased radiation dose studied up to 1000 kGy. Nevertheless, all the composition of extractants showed satisfactory results
up to 500 kGy, beyond which the extractants degraded drastically. The stripping behaviour of Am(III) with 0.2 M HNO3 was found to be unaffected even with the ligand solution irradiated up to 1000 kGy. Extraction of fission product and structural
elements was also investigated using the irradiated solvents and was found to be not significantly affected with increasing
absorbed dose with the exception of Mo which showed sharp rise in the distribution coefficient values. Loading of Nd in the
organic phase decreased with the irradiated solvent due to degradation of the carrier. The effect of the absorbed dose on
physical parameters such as density, viscosity and interfacial tension of the solvents has also been investigated. 相似文献
734.
P. N. Pathak D. R. Prabhu M. Bindu S. C. Tripathi V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):137-142
The primary purpose of this study was to understand the alpha radiolytic degradation behavior of N,N-dihexyl octanamide (DHOA) vis a vis tributyl phosphate (TBP) solutions in n-dodecane under plutonium loading conditions. These studies were carried out as a function of dose on different Pu loaded
samples (containing 0.002-10 g/L Pu) from 4 M HNO3 medium. These Pu loaded solutions were evaluated for stripping behavior by contacting with 0.5 M NH2OH at 0.5 M HNO3 solutions. Organic phase analysis was carried out by gas chromatography (GC) and by visible spectrophotometry. These studies
clearly indicated that Pu stripping becomes difficult with increased dose in the case of TBP system. On the other hand, no
such problem was observed in DHOA system during stripping of plutonium, thereby indicating that DHOA is a promising candidate
for the reprocessing of high burn up Pu rich spent fuels. 相似文献
735.
The response of liquid crystals to light is very important for applications of liquid crystals in display and memory devices.
Recently experiments have been carried out on liquid crystals doped with photoactive azo compounds. It is seen that UV rays
incident on such systems can lower the nematic isotropic transition temperature T
NI . Also, in some mixtures, a photo-induced smectic phase is observed. This is attributed to the change in the trans (longer)
isomer to cis (shorter) isomer of the photoactive dopant. We have earlier developed a molecular mean-field model assuming
the medium to consist of inter-converting anti-parallel and parallel pairs to explain the molecular origin of “two lengths”. The model was used to explain double re-entrance, the effect of electric
field on T
NI , etc. This model is modified to include the change of trans to cis isomer which is equivalent to an increase of fraction
of parallel (shorter) pairs. The calculated phase diagram with respect to incident UV radiation energy shows an induced smectic phase. This is in qualitative
agreement with experimental trends. 相似文献
736.
We derive an expression for the lower bound of the phase-space beam quality factor M(2) of an ultrashort pulse. We show that the condition M(2)>or=1 does not, in general, hold for such pulsed beams. Rather, the minimum value of M(2) depends on the pulse spectrum. We also show that M(2) attains minimum only for pulsed beams whose spot size varies with frequency as omega(-1/2), and that the radial intensity profile of the best-quality pulsed beam can be non-Gaussian. 相似文献
737.
Arjun K. Pathak Prakash Basnyat Shane Stadler 《Journal of magnetism and magnetic materials》2010,322(6):692-697
We have studied the magnetic, magnetocaloric, and magnetostriction properties of LaFe11.4Si1.6 and La(Fe0.99Z0.01)11.4Si1.6 (Z=Ni, Cu, Cr, V) compounds using magnetization and strain gauge techniques. It was found that substitution of 1% of the Fe by Z-elements results in an increase in the Curie temperature (TC), and affects the magnetostriction and magnetocaloric properties of the parent compound, LaFe11.4Si1.6. A maximum shift in TC of about 11 K, and significantly smaller hysteresis losses in the vicinity of TC compared with those of the base compound, were found for Z=V. The maximum magnetovolume coupling constant was estimated to be ndd≈2.7×10−3 (μB/Fe atom)−2 for the parent compound. The changes in the volume magnetostriction, the magnetovolume coupling constant, and the magnetocaloric properties are strongly correlated with composition. The relative effects of the variation in cell parameters and electron concentration on the magnetostriction, TC, and the magnetocaloric properties are discussed. 相似文献
738.
A unified approach valid for any wavenumber q, frequency ω, and temperature T is presented for uniform ideal quantum gases allowing for a comprehensive study of number density and particle-current density response functions. Exact analytical expressions are obtained for spectral functions in terms of polylogarithms. Also, particle-number and particle-current static susceptibilities are presented which, for fugacity less than unity, additionally involve Kummer functions. The q- and T-dependent transverse-current static susceptibility is used to show explicitly that current correlations are of long range in a Bose-condensed uniform ideal gas but for bosons at T>Tc and for Fermi and Boltzmann gases at all temperatures these correlations are of short range. Contact repulsive interactions for systems of neutral quantum particles are considered within the random phase approximation. The expressions for particle-number and transverse-current susceptibilities are utilized to discuss the existence or nonexistence of superfluidity in the systems under consideration. 相似文献
739.
Netaji K. Desai Prasad G. Mahajan Sawanta S. Mali Govind B. Kolekar Shivajirao R. Patil 《Journal of fluorescence》2018,28(4):897-903
The present work reports on the preparation of thin films of pyrene luminophors doped by varying amounts of perylene by spin coating technique. The structural, morphological, and photophysical properties of pyrene thin films have been investigated as a function of perylene contents. X-ray diffraction studies of doped thin films show well-defined peaks, and estimated crystallite size decreases with increasing perylene content, due to the formation of closed packed crystal structure. SEM images of pure pyrene revealed smooth, and compact and separated crystals with amounts of perylene. The result of absorption spectra showed decrease in intensity with perylene content. However, the fluorescence spectra of pyrene containing higher amounts of perylene showed broad and structureless exciplex emission at 510 nm. The emission colour of pyrene luminophors tuned from blue to green by controlling the concentration of perylene. The phenomenon of change in colour was seen due to efficient excitation energy transfer from pyrene to perylene in thin films. It also found that the intensity of exciplex emission increases with increasing concentration of perylene is of high demand in fluorescent lamp as well as green organic light emitting diodes. 相似文献
740.