排序方式: 共有80条查询结果,搜索用时 31 毫秒
61.
K. Marimuthu R.T. Karunakaran S. Surendra Babu G. Muralidharan S. Arumugam C.K. Jayasankar 《Solid State Sciences》2009,11(7):1297-1302
Eu3+-doped alkali fluoroborate glasses B2O3–XCO3–NaF–Eu2O3 (where X = Li2, Na2, K2, and Ca, Mg) have been prepared using the conventional melting technique and their structural and optical properties have been evaluated. The XRD pattern of the glasses confirmed the amorphous nature and the FTIR spectra reveal the presence of BO3 and BO4 units as their local structures along with the strong OH? groups. From the absorption spectra the bonding parameters have been calculated and confirmed that the Eu–O bonds in the studied glasses are of covalent nature. Judd–Ofelt (JO) analysis has been carried out from the emission spectra. The JO parameters have been used to calculate transition probabilities (A), lifetime (τR) and branching ratios (βR) and peak stimulated emission cross-section (σPE) for the 5D0 → 7FJ (J = 1, 2, 3 and 4) transitions of the Eu3+ ions. The decay from the 5D0 level of Eu3+ ions in the title glasses has been measured and analysed. The lifetime of the 5D0 level is found to be shorter than the reported glasses which may be due to the presence of OH? groups. 相似文献
62.
Jayabharathi J Thanikachalam V Srinivasan N Jayamorthy K Perumal MV 《Journal of fluorescence》2011,21(4):1813-1823
A series of substituted imidazoles have been synthesized in very good yield under solvent free condition by grinding 1,2-diketone,
aromatic aldehyde and ammonium acetate in the presence of molecular iodine as the catalyst. The short reaction time, good
yield and easy workup make this protocol practically and economically attractive and characterized by NMR spectra, X-ray,
mass and CHN analysis. An excited state intramolecular proton transfer (ESIPT) process in hydroxy imidazoles (dpip and dptip)
have been studied using emission spectroscopy and it was detected that the two distinct ground state rotamers are responsible
for the normal and the tautomer emissions. DFT calculations on energy, dipole moment, charge distribution of the rotamers
in the ground and excited states of the imidazole derivatives were performed and discussed. DFT analysis about HOMO, HOMO-1,
LUMO and LUMO + 1 were carried out and discussed. PES calculation indicates that the energy barrier for the interconversion
of two rotamers is too high in the excited state than the ground state. 相似文献
63.
Jayabharathi J Thanikachalam V Srinivasan N Perumal MV 《Journal of fluorescence》2011,21(4):1585-1597
The synthesis, structure and photophysical properties of series of new luminescent cyclometalated Iridium (III) complexes
are reported. The cyclometalated ligand used here is 2-aryl imidazole and the auxiliary ligand is acetyl acetone (acac). The
crystal structure of the complex (dmdpi)2Ir(acac) (5) show that the Iridium(III) ion resides in a distorted octahedral environment. All complexes exhibit bright photoluminescence
(PL) at room temperature and (fpdmdmpi)2Ir(acac) 4 has a high solution PL quantum efficiency of 0.56. The role played by electron releasing and electron withdrawing substituents
of the 2-arylimidazole ligands towards the stability of HOMO and how the substituent influences the luminescent behaviour
are discussed. Furthermore those substituents have effect on the contribution to mixing between 3(π-π*) and 3(MLCT) for the lowest excited states. 相似文献
64.
The mutual interaction of imidazole derivative (PIPP) with bovine serum albumin (BSA) was investigated using photoluminescent
studies. The fluorescence quenching mechanism of BSA by PIPP was analyzed and the binding constant was calculated. The binding
distance between PIPP and BSA was obtained based on the theory of Forester’s non-radiation energy transfer. Displacement experiments
were performed by using ibuprofen to identify PIPP binding site in BSA. The effect of some common ions on the binding constant
between PIPP and BSA was also examined. 相似文献
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66.
Triphenylphosphonium perchlorate (TPP) is found to be an efficient catalyst for the mono- and bis-intramolecular imino Diels-Alder (IMIDA) reaction of aldimines derived from aromatic amines and O-allyl derivatives of salicylaldehydes to afford the corresponding tetrahydrochromano[4,3-b]quinolines in excellent yields and short reaction times under mild conditions. 相似文献
67.
68.
Saraswathi Marimuthu Somasundaram Uma Subbaraya Sharmila Gayatri Durairajan Soundaryan Rajendran Jithu Gopalakrishnan Bahrudeen Shahul Hameed Durai Palani Backiyarani Suthanthiram 《Electrophoresis》2019,40(9):1265-1272
Inter simple sequence repeat markers were employed for the genotyping of 16 plantain ecotypes. Two different electrophoretic systems namely conventional gel electrophoresis (CVGE) and fully automated high‐resolution CGE were used to evaluate the genetic diversity. Comparative analysis indicated that all parameters related to marker informativeness were higher in CGE except polymorphic information content. But genetic diversity parameters like effective number of alleles, Nei's gene diversity (1973) and Shannon's information index showed higher values (1.52 ± 0.12, 0.34 ± 0.05 and 0.52 ± 0.05, respectively) in CVGE as against CGE (1.29 ± 0.04, 0.22 ± 0.02 and 0.38 ± 0.03, respectively) system. The unweighed pair group method with arithmetic averages was used to obtain the dendrogram for both analyses. The results of dendrogram and principal component analysis were found to be consistent in both systems except for some minor disagreements. The clone‐specific bands could be used in the identification and development of SCAR markers. Inter simple sequence repeat markers used in this study provided sufficient polymorphism and reproducible banding pattern for evaluating the genetic diversity of different plantain ecotypes. Lack of accuracy and consistency of the CVGE warrants the employment of high‐throughput CGE for diversity analysis as it provided better separation of bands with higher resolution. 相似文献
69.
Chandan Karmakar Radhagayathri Udhayakumar Marimuthu Palaniswami 《Entropy (Basel, Switzerland)》2020,22(12)
Entropy profiling is a recently introduced approach that reduces parametric dependence in traditional Kolmogorov-Sinai (KS) entropy measurement algorithms. The choice of the threshold parameter r of vector distances in traditional entropy computations is crucial in deciding the accuracy of signal irregularity information retrieved by these methods. In addition to making parametric choices completely data-driven, entropy profiling generates a complete profile of entropy information as against a single entropy estimate (seen in traditional algorithms). The benefits of using “profiling” instead of “estimation” are: (a) precursory methods such as approximate and sample entropy that have had the limitation of handling short-term signals (less than 1000 samples) are now made capable of the same; (b) the entropy measure can capture complexity information from short and long-term signals without multi-scaling; and (c) this new approach facilitates enhanced information retrieval from short-term HRV signals. The novel concept of entropy profiling has greatly equipped traditional algorithms to overcome existing limitations and broaden applicability in the field of short-term signal analysis. In this work, we present a review of KS-entropy methods and their limitations in the context of short-term heart rate variability analysis and elucidate the benefits of using entropy profiling as an alternative for the same. 相似文献
70.
Antony Rajendran Marimuthu Rajendiran Zhi‐Fen Yang Hong‐Xia Fan Tian‐You Cui Ya‐Gang Zhang Wen‐Ying Li 《Chemical record (New York, N.Y.)》2020,20(6):513-540
Heterogeneous catalysis plays a key role in promoting green chemistry through many routes. The functionalizable reactive silanols highlight silica as a beguiling support for the preparation of heterogeneous catalysts. Metal active sites anchored on functionalized silica (FS) usually demonstrate the better dispersion and stability due to their firm chemical interaction with FSs. Having certain functional groups in structure, FSs can act as the useful catalysts for few organic reactions even without the need of metal active sites which are termed as the covetous reusable organocatalysts. Magnetic FSs have laid the platform where the effortless recovery of catalysts is realized just using an external magnet, resulting in the simplified reaction procedure. Using FSs of multiple functional groups, we can envisage the shortened reaction pathway and, reduced chemical uses and chemical wastes. Unstable bio‐molecules like enzymes have been stabilized when they get chemically anchored on FSs. The resultant solid bio‐catalysts exhibited very good reusability in many catalytic reactions. Getting provoked from the green chemistry aspects and benefits of FS‐based catalysts, we confer the recent literature and progress focusing on the significance of FSs in heterogeneous catalysis. This review covers the preparative methods, types and catalytic applications of FSs. A special emphasis is given to the metal‐free FS catalysts, multiple FS‐based catalysts and magnetic FSs. Through this review, we presume that the contribution of FSs to green chemistry can be well understood. The future perspective of FSs and the improvements still required for implementing FS‐based catalysts in practical applications have been narrated at the end of this review. 相似文献