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101.
Synthesis and photophysical studies of a simple and efficient dansyl-styrylquinoline conjugate (DansSQ) which shows excellent selectivity toward Fe2+ over other transition metal ions including Fe3+ are described. The fluorescent emission of DansSQ at 450 nm was enhanced upon addition of Fe2+ in the presence of common interfering metal ions in background. These studies suggest that DansSQ could be used as fluorescent sensor for Fe2+. 相似文献
102.
Choorikkat Ranjith K.K. Vijayan Vakayil K. Praveen N.S. Saleesh Kumar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(5):1610-1616
In the present work an array of novel substituted 2H-chromen-2-one (coumarin) derivatives has been subjected to photophysical analysis. Though the influence of the electron-donating groups such as amino, substituted amino, hydroxyl, alkoxy groups, etc. at position 7 of the coumarin ring system has been extensively studied, the luminescent properties of the coumarin moieties with an acetoxy substituent have not been explored. Herein it is attempted to study the variation of fluorescence behavior of substituted coumarin derivatives with change of nature and position of the substituents on the 2H-chromen-2-one skeleton. Effect of a methyl substituent at position 4 which imposes abnormal photophysical behavior to the chromenone unit has also been briefly described. 相似文献
103.
Molly Megraw Praveen Sethupathy Kiranmai Gumireddy Shane T. Jensen Qihong Huang Artemis G. Hatzigeorgiou 《Theoretical chemistry accounts》2010,125(3-6):593-598
In this study, we investigate whether miRNAs located within “host” protein-coding genes may regulate the expression of their host genes. We find that 43 of 174 miRNAs encoded within RefSeq genes are predicted to target their host genes. Statistical analysis of this phenomenon suggests that gene auto-regulation via miRNAs may be under positive selective pressure. Our analysis also indicates that several of the 43 miRNAs have a much lower expectation of targeting their host genes by chance than others. Among these examples, we identify miR-128b:ARPP-21 (cyclic AMP-regulated phosphoprotein, 21 kD) as a case in which both the miRNA and the target site are also evolutionarily conserved. We provide experimental support for this miRNA:target interaction via reporter silencing assays, and present evidence that this isoform-specific gene auto-regulation has been preserved in vertebrate species in order to prevent detrimental consequences of ARPP-21 over-expression in brain. 相似文献
104.
K.L.N. Deepak R. Kuladeep V. Praveen Kumar S. Venugopal Rao D. Narayana Rao 《Optics Communications》2011,284(12):3074-9305
We report microfabrication of structures in bulk and thin films of polystyrene (PS) using femtosecond (fs) laser pulses. For the first time to our knowledge, we report emission from the fs laser modified regions of bulk and thin films of PS when excited at 458, 488, and 514 nm. Moreover, we report the existence of peroxide type free radicals, for the first time, in fs laser irradiated bulk PS. We observed the suppression of Raman modes in case of structures fabricated at higher energies and the same effect was noticed in central portion of the structures fabricated. No appreciable broadening was observed in the case of structures fabricated at low energies. Possible applications resulting from such structures are discussed briefly. 相似文献
105.
We investigate the effect of temperature on structure and dynamics of a colloidal glass created by tethering polymers to the surface of inorganic nanoparticles. Contrary to the conventional assumption, an increase in temperature slows down glassy dynamics of the material, yet causes no change in its static structure factor. We show that these findings can be explained within the soft glassy rheology framework if the noise temperature X of the glass phase is correlated with thermodynamic temperature. 相似文献
106.
Molybdenyl(VI) acetylacetonate is an effective catalyst for the deprotection of acetals into the corresponding aldehydes and ketones, in good yields. 相似文献
107.
S. Lakshmi Reddy G. Udayabashkar Reddy R. Ramasubba Reddy G. Siva Reddy Ray L. Frost Tamio Endo 《Particuology》2013,11(3):340-345
The microwave synthesis of MnC2O4·2H2O nanoparticles was performed through the thermal double decomposition of oxalic acid dihydrate (C2H2O4·2H2O) and Mn(OAc)2·4H2O solutions using a CATA-2R microwave reactor. Structural characterization was performed using X-ray diffraction (XRD), particle size and shape were analyzed using transmission electron microscopy (TEM). The chemical in the structures was investigated using electron paramagnetic resonance (EPR) as well as optical absorption spectra and near-infrared (NIR) spectroscopies. The nanocrystals produced with this method were pure and had a distorted rhombic octahedral structure. 相似文献
108.
J Santhanalakshmi G Shantha Lakshmi V K Aswal P S Goyal 《Journal of Chemical Sciences》2001,113(1):55-62
Small angle neutron scattering (SANS) measurements of D2O solutions (0.1 M) of sodium cholate (NaC) and sodium deoxycholate (NaDC) were carried out atT= 298 K. Under compositions very much above the critical micelle concentration (CMC), the bile salt micelle size growths were
monitored by adopting Hayter-Penfold type analysis of the scattering data. NaC and NaDC solutions show presence of correlation
peaks atQ = 0.12 and 0.1 ?-1 respectively. Monodisperse ellipsoids of the micelles produce best fits. For NaC and NaDC systems, aggregation number (9.0,
16.0), fraction of the free counterions per micelle (0.79, 0.62), semi-minor (8.0 ?) and semi-major axes (18.4, 31.7 ?) values
for the micelles were deduced. Extent of micellar growth was studied using ESR correlation time measurements on a suitable
probe incorporating NaC and NaDC micelles. The growth parameter (axial ratio) values were found to be 2.3 and 4.0 for NaC
and NaDC systems respectively. The values agree with those of SANS. 相似文献
109.
110.
Methods to generate triplets of organic molecules within zeolites have been established by employing the Zimmerman rearrangement of barrelenes, oxa-di-π-methane rearrangement of β,γ-unsaturated ketones and photodimerization of acenaphthylene as probe reactions. The two methods, heavy cation effect and triplet sensitization, are well established solution techniques and these work well within zeolites. The Zimmerman rearrangement of dibenzobarrelene is enhanced even within Li+ and Na+ exchanged zeolites and these are believed to be the result of slowing of the rearrangement to dibenzocyclooctatetraene from S1 through cation-π interaction. The methods described here provide an opportunity to explore the control afforded by the zeolite environment on triplet reactions. 相似文献