Two new structural variants of Marfey's reagent (1-fluoro-2,4-dinitrophenyl-5-l-alaninamide, FDNP-l-Ala-NH2) were synthesized by nucleophilic substitution of one fluorine atom in 1,5-difluoro-2,4-dinitrobenzene (DFDNB) by l-methioninamide or d-phenylglycinamide. The new variants FDNP-l-Met-NH2 and FDNP-d-Phg-NH2 were characterized and used for derivatization of twenty-six α-amino acids. The resulting diastereomeric derivatives were separated on a reversed-phase C18 HPLC column using a linear gradient of acetonitrile and aqueous trifluoroacetic acid (TFA) and the results were compared with those obtained by use of Marfey's reagent. To determine and establish the efficiency of both the new variants, separation results were compared for diastereomers of five representative amino acids (Ala, Phe, Ser, Asp, and Asn) prepared with MR, FDNP-l-Phe-NH2, FDNP-l-Val-NH2, FDNP-l-Leu-NH2, and FDNP-l-Pro-NH2, experiments being performed under identical conditions. Both the new chiral reagents enabled better separation of the diastereomers than Marfey's reagent for most of the amino acids. The reagent FDNP-d-Phg-NH2 enabled excellent separation for serine and asparagine whereas other reagents failed or provided poor results.
Authors:Rajneesh Kumar, Pankaj Sharma, and V. S. Rangra
Bulk samples of Se92Te8−xSnx glassy alloys are obtained by melt quenching technique. Differential scanning calorimetry (DSC) technique (under non-isothermal conditions) has been applied to determine the thermal properties of Se-rich glassy alloys at different heating rates. Results of glass transition temperature, enthalpy released, fragility and specific heat of Se92Te8−xSnx (x = 0, 1, 2, 3, 4 and 5) chalcogenide glasses have been reported and discussed. The glass transition temperature (Tg), activation energy of glass transition and fragility are found to increase with increase in Sn content. The glass transition temperature (by Gibbs–Dimarzio equation) also has been calculated. Both values of Tg (experimental as well as theoretical) are found to be in good agreement at a heating rate of 10 K min−1. It has been observed that the value of specific heat (Cp) below glass transition and difference in the value of Cp before and after glass transition (ΔCp) is highly compositional dependent. The enthalpy release is related to the metastability of the glasses, and the least stable glasses are supposed to have maximum ΔHc.
Extraction behavior of137Cs was studied from nitric acid medium using dibenzo 18 crown 6 (DB18C6), 4,4'(5')di-acetylbenzo 18 crown 6 (DAB18C6), 4,
4'(5')di-hexanoylbenzo 18 crown 6 (DHB18C6), 4,4'(5')di-nonanoylbenzo 18 crown 6 (DNB18C6) and 4,4'(5')di-t-butylbenzo 18
crown 6 (DTBB18C6) in nitrobenzene medium. The stoichiometry of the species extracted with dibenzo 18 crown 6 (L) conformed
to ML+. NO3− TheDCs values were found not to be affected by the presence of aluminium nitrate in the aqueous phase. The separation behavior of
fission products obtained from an irradiated natural uranium target was also studied. Presence of 0.004M phosphotungstic acid
found to enhance theDCs values at lower acidities.
C.V. Raman is being acknowledged by worldwide physics community for his classic works. The present study has made an effort
to analyze how much impact in number of citation receiving for his publications. Of course, there was a lack of tools for
such a study some years back. The study has limited to the database Science Citation Index for the period 1982–2005. The noteworthy
results are: One third of his research papers have been cited at least once; The research papers published during 1918–1940
could make remarkable impact; Three of his papers have shown an upward growth in number of citations receiving; The total
citations to papers of age 46 and 54 as on the year 1982 accounted for more than 50 per cent of the total citations received;
Research works in the ‘Acoustics’ area have been cited more than any other area of his works; Eponymal citations are to be
explored and analysed to understand the real impact of his works.
A field experiment was carried out to investigate the establishment of phosphate-dissolving strains of Azotobacter chroococcum, including soil isolates (wild type) and their mutants, in the rhizosphere and their effect on the growth attributes and root biomass of three genetically divergent wheat cultivars (Triticum aestivum L.). Four fertilizer doses were applied: 90 kg N ha—1, 90 kg N + 60 kg P2O5ha—1, 120 kg N ha—1and 120 kg N + 60 kg P2O5ha—1, besides a control plot without fertilizers or bioinoculants. Phosphate-solubilizing and phytohormone-producing parent soil isolates and mutant strains of A. chroococcum were isolated and selected following the enrichment method. On an overall basis the mutant strains performed better than the soil isolates for in vitro phosphate solubilization (11–14%) and growth hormone production (11.35%). Seed inoculation of wheat varieties with phosphate-solubilizing and phytohormone-producing A. chroococcum showed a better response over the control. Mutant strains of A. chroococcum showed a higher increase in grain (15.30%) and straw (15.10%) yield over the control and better survival (12–14%) in the rhizosphere as compared to their parent soil isolate (P4). Mutant strain M15 performed better in all three varieties in terms of increase in grain yield (20.8%) and root biomass (20.6%) over the control.
Ahmed Hassan Zewail, the Nobel laureate (1999) in chemistry have collaborated with 103 colleagues and has published 246 papers during 1976 to 1994 in: femtochemistry (62), reaction rates and IVR (56), general reviews (49), coherence and optical dephasing phenomena (27), solids: magnetic resonance and optical studies (13), liquids and biological systems (9), local modes in large molecules (9), molecular structure from rotational coherence (8), solar energy concentrators (7), and other studies (6). This authorship pattern included: three authored papers (87) followed by two authored (78), four authored (38), one authored (30), five authored (8), and six authored (5). Highest collaborations were with P. M. Felker (39), M. Dantus (19), and L. R. Khundkar (16). The core journals publishing his papers were: J. Chem. Phys. (77), Chem. Phys. Lett. (53), J. Phys. Chem. (33), and Nature(6) out of the 33 journal channels and 32 chapters in books.
Authors:Y. Gautam, S. Sharma, A. Sharma, V. Kumar, J. Kumar, A. Kumar, A. Hegde, and P. Sarkar
Guidelines for the assessment of internal doses from monitoring suggest default measurement of uncertainties (i.e. lognormal
scattering factor, SF) to be used for different types of monitoring data. In this paper, SF values have been evaluated for
internal contamination due to 60Co in two cases using whole body counting data. SF values of 1.04 and 1.03 were obtained for case I and II, respectively while
SF value of 1.03 was obtained using bioassay data for case I. SF evaluated is in good agreement with the default values given
by IDEAS guidelines. The present study also presents the follow up study of a case I of 60Co internal contamination using whole body counting and bioassay analysis. The effect of medical intervention applied on the
subject is studied. Medical intervention of d-Penicillamine (250 mg × 4 daily) was orally administered from 13th day of initial exposure for about a fortnight, which showed
reduction of activity present by 33.4% through urine.
Authors:Sanjiv Kumar, J. V. Ramana, S. Vikram Kumar, and V. S. Raju
The determination of atomic composition and thickness of zirconium oxide layers on zirconium based alloys is of practical interest in nuclear industry. This paper describes the application of backscattering spectrometry for the non-destructive determination of composition and thickness of zirconium oxide layers on autoclaved zircaloy coupons. The spectrometry used here is the Rutherford backscattering spectrometry (RBS) with 2.5 MeV α-particles, 3.05 MeV 16O(α,α)16O resonance scattering and 16O(p,p)16O elastic scattering with 2.5 MeV proton beam. Proton backscattering is found to be the most suitable technique for the overall compositional analysis of the layers whereas 3.05 MeV 16O(α,α)16O resonance scattering, for depth profiling of oxygen. The former technique is simple and provides rapid measurements. The lower stopping cross sections of protons and enhanced scattering cross section for oxygen over a wide range of proton energy enable the analysis of oxide layers of larger thicknesses. The thicknesses of these layers determined by backscattering are in good agreement with cross-sectional micrographs taken by scanning electron microscope (SEM).
Authors:Y. Gautam, A. Sharma, S. Sharma, K. Rao, J. Kumar, V. Kumar, B. Singh, A. Kumar, and A. Hedge
Atmospheric tritium activity is measured regularly around Narora Atomic Power Station (NAPS) since gaseous waste, which contains
tritium, is being released through a 145 m high stack at NAPS site. Atmospheric data collected during 2004–2008 shows a large
variation of 3H concentration in air, fluctuating in the range of ≤0.2–91.6 Bq m−3. Significantly, higher tritium levels were measured in samples near the site boundary (1.6 km) of NAPS compared to off-site
locations. The atmospheric dilution factor was found to be in the range of 1.1 × 10−7–7.3 × 10−7 s m−3. The scavenging ratio of NAPS site was found to be varying from 0.2 × 104 to 14.1 × 104 (Bq m−3 rain water per Bq m−3 air). The inhalation dose to a member of general public at different distances (1.6–30 km) from NAPS site was found to be
ranged from 0.08–0.21 μSv year−1.
Authors:A. Kumar, Y. Gautam, V. Kumar, K. Rao, S. Sharma, A. Sharma, and A. Hegde
Knowledge of the dynamics of HTO in leafy plant–soil system is required to verify models, such as the NORMTRI code, which
predict environmental tritium following its release. Tritium concentrations in plants has been evaluated using the code NORMTRI
and experimentally by collection of samples of different plants and their soils samples. In the present study, major seasonal
crop plants i.e. wheat, mustard, sugar cane, coriander, spinach, potato, were collected beyond Narora Atomic Power Station
site boundary and gular, arandi, neem, ashok, amaltas, csuarina leaf samples within NAPS site boundary for analysis of HTO
content. Data analysis indicated that HTO in leaf is strongly influenced by atmospheric relative humidity and type of the