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1.
The laser Raman spectrum of tere-phthalaldehyde powder has been recorded on a Jobin Yvonhg 2S spectrophotometer with a~100 mW Argon-Ion laser. The infrared spectrum of the solid substance has been recorded on a Perkin-Elmer
621 spectrophotometer in the region 300–4000 cm-1 using KBr and nujol mull techniques. The observed frequencies have been assigned in terms of the fundamentals, overtones
and combinations assumingD
2h point-group symmetry. 相似文献
2.
Sharma Ajitkumar L. Singh Ibopishak O. Singh Manihar A. Singh Hemakumar R. Kadam Ramakant M. Bhide Madhusudan K. Sastry Medury D. 《Transition Metal Chemistry》2001,26(4-5):532-537
E.p.r. and optical absorption studies have been conducted on dichloromono(1-phenylamidino-o-alkylurea)copper(II) complexes (Alkyl = Me, Et, Pr, Bu or Pe). The e.p.r. spectra of solids, recorded at 300 K, confirmed the square-planar geometry with the unpaired electron in the dx
2–y
2 orbital of copper. Magnetic field-induced partial molecular alignment has been observed in some of the polycrystalline samples when cooled in a magnetic field of 1 T at 77 K. E.p.r. spectra at 77 K in pyridine and DMF has shown axial ligation of solvent molecules (pyridine and DMF), whereas in MeOH and DMSO at least three structurally different CuII species have been identified. These features are consistent with differences in electronic absorption spectra in the powder and in solution. 相似文献
3.
Pradhan S Yadav R Mishra VN Aurangabadkar K Sawlani V 《Magnetic resonance imaging》2006,24(2):173-179
OBJECTIVE: To evaluate the role of magnetic resonance imaging (MRI) in the early diagnosis of amyotrophic lateral sclerosis (ALS) with predominant upper motor neuron (UMN) signs in the initial stage of the disease. PATIENTS AND METHOD: Two patients with ALS were found to have spastic quadriparesis with no wasting or fasciculation in the limbs in the early stage of the disease. Both were subjected to MRI of the head and cervical spine to look for any specific diagnostic feature. Both of them were followed with clinical evaluation and electroneuromyography (ENMG) for the definitive diagnosis of ALS. RESULTS: Magnetic resonance imaging showed selective degeneration of the pyramidal tracts in the contiguous axial cuts from subcortical white matter to cerebral peduncles. The finding was more visible in the coronal section. In addition, there was T1 hyperintensity visible along the anterior aspect of the spinal cord in the cervical region. These findings were suggestive of ALS, the diagnosis that was subsequently confirmed by serial clinical follow-up and ENMG. CONCLUSION: It is difficult to diagnose ALS in the early stage of the disease especially if the pyramidal signs predominate over the lower motor neuron (LMN) signs; MRI might be useful in such cases. 相似文献
4.
Three new mono–di–trinuclear cobalt complexes of three different Schiff bases have been synthesised. In all the three complexes psuedohalides (NCO− and N3−) have been incorporated to generate structural variation. Of the three Schiff bases, HL1 and HL2 were obtained by selective condensation of two different 1,3-diamines with 2-hydroxyacetophenone and H2L3 resulted from non-selective condensation of 1,3-diamine with 2-hydroxyacetophenone. Only one –NH2 functionality of 1,3-diaminopropane and 1,3-diaminopentane was selectively condensed with 2-hydroxyacetophenone to generate Schiff bases HL1 and HL2, respectively. H2L3 was obtained by condensing both the amine functionality of 1,3-diaminopropane with 2-hydroxyacetophenone. Therefore HL1 and HL2 behave as a N2O donors, whereas H2L3 provides a N2O2 donor coordination environment for the cobalt ions in the respective complexes. In [Co(L1)2]2 [Co(NCO)4] (1) the asymmetric unit comprises of five mononuclear cobalt centers, [Co2(μ–N3)2(L2)2(N3)2] (2) is a dinuclear and [(H2O)2Co(μ–N3)2(μ–L3)2Co2(N3)1.25(CH3O)0.75] · H2O (3) is a trinuclear cobalt species. The three complexes have been characterised using IR, UV–Vis spectroscopy and cyclic voltammetry. Structural aspects of 1, 2 and 3 have been described by performing single crystal X-ray analysis. EPR analyses of 1 and 3, and DNA binding abilities of all three cobalt complexes have been studied in detail. 相似文献
5.
Farheen N. Sayed Srungarpu N. Achary Sudhanshu·K. Deshpande Balasubhramanian Rajeswari Ramakant M. Kadam Sandhya Dwebedi Arun K. Nigam Avesh K. Tyagi 《无机化学与普通化学杂志》2014,640(10):1907-1921
Polycrystalline samples of La2MMnO6 (M = Co and Mg) were prepared by a combined gel‐combustion and high temperature reaction method. The samples were annealed in different oxygen partial pressure (pO2) and characterized by powder XRD, SQUID magnetometry, ac impedance spectroscopy, and electron paramagnetic resonance techniques. Monoclinic (P21/n) and rhombohedral (R$\bar{3}$ ) lattices were observed for La2CoMnO6 and La2MgMnO6, respectively. On annealing in inert atmosphere, La2MgMnO6 partially converted to monoclinic La2CoMnO6 type structure, whereas no structural change was observed in La2CoMnO6. Dielectric studies of La2CoMnO6 indicated relaxor like behavior with polaronic conduction, which systematically decreased with the increase in pO2 of the annealing atmosphere. Magnetic studies indicated multiple ferromagnetic phase transitions in La2CoMnO6 and a spin‐glass like phase transition in La2MgMnO6. The fraction of ferromagnetic phases of La2CoMnO6 was significantly dependent on the annealing environments. The variations of magnetic and dielectric properties of samples were related to the fluctuation of oxidation state of transition metal ions and oxygen vacancies in the samples. 相似文献
6.
C. H. Brito Cruz H. L Fragnito R. Francalacci M. A. F. Scarparo Ramakant Srivastava 《Optical and Quantum Electronics》1983,15(6):487-496
We use a rate equation model to analyse a technique for the generation of picosecond duration laser pulses in argon pumped dye lasers. The system is based on passive mode-locking of the Ar+ laser by saturable absorption of the dye which is inserted in the Ar+ laser cavity. Simultaneously, the dye is forced to oscillate in a regime of synchronously pumped mode-locking. The system is relatively simple, does not require the use of an acousto-optical light modulator and can be easily implemented in commercially available lasers. Pulses shorter than 100 ps and having an average power of 20 mW were obtained at a repetition rate of 110 MHz. Good agreement between the model and experimental results was also obtained. 相似文献
7.
8.
Sharma LA Singh OI Singh AK Singh RK Kadam RM Bhide MK Dhobale AR Sastry MD 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(7):1593-1600
Electron paramagnetic resonance (EPR) investigations were conducted on [Cu(II) (1-phenylamidino-O-n-butylurea) en (H2O)]2(2+) (1) and [Cu(II) sulphato-mono (1-phenylamidino-O-methylurea)]2 (2) respectively, in the temperature range 300-77K. Fine structure characteristics of S = 1 system, was observed in both complexes with zero field splitting of 0.0525 and 0.0225 cm(-1), respectively, suggesting the formation of dimeric complexes. The presence of the half-field signal (DeltaMs= +/-2), in the complex 1, further confirmed the formation of dimer. The temperature dependence of EPR signal intensity has given evidence for the ferromagnetic (FM) coupling between the two Cu2+ ions. The isotropic exchange interaction constants J, were evaluated from this and were found out to be approximately 57 and approximately 27 cm(-1), respectively, for the complexes 1 and 2. The photoacoustic spectra of these complexes had shown a band around 26,400 cm(-1) characteristic of metal-metal bonding giving an independent support for the existence of dimeric Cu2+ species. The high magnetic moment values at room temperature for complex 1 (2.68 microB) and complex 2 (2.00 microB), obtained from the magnetic susceptibility measurements, support the formation of ferromagnetically coupled Cu2+ dimers. 相似文献
9.
A simple, sensitive and fast ion chromatographic (IC) method with suppressed conductivity detection is described for the determination of traces of nitrogen in uranium based fuel materials. Initially a method was developed to determine nitrogen as NH4+ using cation exchange column after matrix separation by Kjeldahl distillation. The method was then improved by eliminating this distillation. Matrix separation after sample dissolution was done by hydrolyzing and filtering off the polyvalent cations. This had helped in reducing both the sample size and analysis time. Optimization of dissolution conditions for various kinds of uranium based samples was done to keep acid content minimum; a prerequisite chromatographic condition. The calibration plot for nitrogen was linear in the concentration range of 0.02-1 mg L−1 with regression coefficient of 0.9999. The relative standard deviation (R.S.D.) obtained in this method (100 μL injected) was 3% and 2% in 9 replicates at nitrogen level of 28 and 55 ng g−1, respectively. Detection limit based on S/N = 3 (100 μL injected) as well as three times of variation in blank value was 4 ng g−1. The developed method was authenticated by comparison with certified uranium-alloy standard as well as with independent indophenol photometry method. The developed method was applied to uranium-alloy, uranium-metal, sintered UO2 pellets and sintered UO2 microspheres samples. 相似文献
10.
Amzad H. Laskar Naveen Gandhi Kaustubh Thirumalai Madhusudan G. Yadava Rengaswamy Ramesh Ramakant R. Mahajan 《Isotopes in environmental and health studies》2014,50(2):156-168
We present a comparative study of two offline methods, a newly developed method and an existing one, for the measurement of the stable carbon isotopic composition (δ13C) of dissolved inorganic carbon (DIC; δ13CDIC) in natural waters. The measured δ13CDIC values of different water samples, prepared from laboratory Na2CO3, ground and oceanic waters, and a laboratory carbonate isotope standard, are found to be accurate and reproducible to within 0.5 ‰\ (1σ). The extraction of CO2 from water samples by these methods does not require pre-treatment or sample poisoning and can be applied to a variety of natural waters to address carbon cycling in the hydrosphere. In addition, we present a simple method (based on a two-end-member mixing model) to estimate the silicate-weathering contribution to DIC in a river system by using the concentration of DIC and its δ13C. This approach is tested with data from the Krishna River system as a case study, thereby quantifying the contribution of silicate and carbonate weathering to DIC, particularly during peak discharge. 相似文献