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991.
Effect of anionic surfactant on the optical absorption spectra and redox reaction of basic fuchsin, a cationic dye, has been studied. Increase in the absorbance of the dye band at 546 nm with sodium dodecyl sulfate (SDS) is assigned to the incorporation of the dye in the surfactant micelles with critical micellar concentration (CMC) of 7.3 × 10?3 mol dm?3. At low surfactant concentration (<5 × 10?3 mol dm?3) decrease in the absorbance of the dye band at 546 nm is attributed to the formation of a dye–surfactant complex (1:1). The environment, in terms of dielectric constant, experienced by basic fuchsin inside the surfactant micelles has been estimated. The association constant (KA) for the formation of dye–SDS complex and the binding constant (KB) for the micellization of dye are determined. Stopped‐flow studies, in the premicellar region, indicated simultaneous depletion of dye absorption and formation of new band at 490 nm with a distinct isosbestic point at 520 nm and the rate constant for this region increased with increasing SDS concentration. The reaction of hydrated electron with the dye and the decay of the semireduced dye are observed to be slowed down in the presence of SDS. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 629–636, 2003 相似文献
992.
S. Chandrasekaran D. Mohan Krishna V. Ganesan P. Srinivasa Rao 《Experiments in fluids》1998,24(5-6):462-469
The main aim of the present investigation is to experimentally study the flow parameters inside a spherical combustion chamber
of an indirect injection diesel engine. For this a spherical chamber has been fitted in the cylinder head. Using a constant
temperature hot-wire anemometer, measurements have been made under non-firing condition at 400 and 500 rpm during compression
stroke. Mean velocity and turbulence intensity values are evaluated from the hot-wire signal. Measurements are made at three
axial planes, six angular locations and four radial positions. Large variations of mean velocity and turbulence intensity
have been observed within the chamber. From the measurements, the mean velocity and turbulence intensity are found to be maximum
at 30° before compression TDC and these values are found to decrease towards the centre of the pre-chamber. The mean velocity
and turbulence intensity distribution with respect to various locations and crank angles are presented and discussed.
Received: 7 November 1995/Accepted: 26 October 1997 相似文献
993.
994.
D. Sathya R. Jagan R. Padmavathy R. Mohan Kumar K. Sivakumar 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(8):904-909
In bis(2‐aminoanilinum) fumarate, 2C6H9N2+·C4H2O42−, (I), the asymmetric unit consists of two aminoanilinium cations and one fumarate dianion, whereas in 3‐methylanilinium hydrogen fumarate, C7H10N+·C4H3O4−, (II), and 4‐chloroanilinium hydrogen fumarate, C6H7ClN+·C4H3O4−, (III), the asymmetric unit contains two symmetry‐independent hydrogen fumate anions and anilinium cations with a slight difference in their geometric parameters; the two salts are isostructural. In (II) and (III), the carboxylic acid H atoms of the anions are disordered across both ends of the anion, with equal site occupancies of 0.50. Both the 4‐chloroanilinium cations of (III) are disordered over two orientations with major occupancies fixed at 0.60 in each case. The hydrogen fumarate anions of (II) and (III) form one‐dimensional anionic chains linked through O—H...O hydrogen bonds. Salts (II) and (III) form two‐dimensional supramolecular sheets built from R44(16), R44(18), R55(25) and C22(14) motifs extending parallel to the (010) plane, whereas in (I), an (010) sheet is formed built from two R43(13) motifs, two R22(9) motifs and an R44(18) motif. 相似文献
995.
Mioara Drobota Zdenka Persin Lidija Fras Zemljic Tamiselvan Mohan Karin Stana-Kleinschek Ales Doliska Matej Bracic Volker Ribitsch Valeria Harabagiu Sergiu Coseri 《Central European Journal of Chemistry》2013,11(11):1786-1798
The functionalization of poly(ethylene terephthalate) (PET) surface films by reactions with multifunctional amines such as triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) was investigated. For the functionalization of PET films surface we used a new way of treatment, a “sandwich model”. Physical-chemical properties of functionalized PET films were analysed. Qualitative and quantitative determination of the introduced amine groups were examined by means of Fourier Transform Infrared Attenuated Total Reflexion (FTIR — ATR), X-ray photoelectron spectroscopy (XPS), and potentiometric titration. Gained wetting properties were determined by using contact angle measurements and thoroughly analysed by acid-base approach. In addition, surface topography was investigated by atomic force microscopy (AFM). The amount of the introduced amino groups after TETA incorporation has been found to be two times higher as compared to TEPA. Wetting properties were significantly improved after aminolysis. Surface free energy was higher for PET — TETA treated film than that observed for PET — TEPA treated which is in accordance with titration results. The collagen immobilization onto PET treated films was evidenced by using AFM and subsequently by using XPS. 相似文献
996.
A winged achiral antiferroelectric liquid crystalline compound, 1,3-phenylene bis-[phenylene1-(biphenyldicarboxylato)-3-(4-n-tetradecyloxybenzoyl)biphenyldicarboxylate] (PBPBTB), having 1,3-phenylene [4-biphenyldicarboxylate-(4-n-tetradecyloxy benzoate)] units as wings, has been synthesized. Its mesogenic properties were characterized by thermal microscopy, differential scanning calorimetry, response time and spontaneous polarization measurements, and dielectric studies, suggesting the presence of new achiral phases. An interesting enantiotropic cyclic sequence among ferro- and antiferro-electric ordering was confirmed by the polarizing current profiles. The occurrence of re-entrant ferroelectric phenomena in the present compound was confirmed by detailed spontaneous polarization and preliminary dielectric studies. 相似文献
997.
Shalini Singh Govind S.M. Shivaprasad Mohan Lal Mukhtar A. Khan 《International journal of environmental analytical chemistry》2013,93(3):141-152
In this work, porous silicon (PS) films with varied porosity (68–82%) were formed on the p-type, boron-doped silicon wafer (100) by the electrochemical anodisation in an aqueous hydrofluoric acid and isopropyl alcohol solution at different current densities (I d) ranging from 20–70 mA cm?2, respectively. Biofunctionalisation of the PS surface was carried out by chemically modifying the surface of PS by the deposition of 3-aminopropyltriethoxysilane thermally leading to high density of amine groups covering the PS surface. This further promotes the immobilisation of immunoglobulin (human IgG and goat anti-human IgG binding) on to the PS surface. Formation of nanostructured PS and the attachment of antibody–antigen to its surface were characterised using photoluminescence (PL), Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy techniques, respectively. The possibility of using these structures as biosensors has been explored based on the significant changes in the PL spectra before and after exposing the PS optical structures to biomolecules. These experimental results open the possibility of developing optical biosensors based on the variation of the PL position of the PL spectra of PS-based devices. 相似文献
998.
Kinetics of vinyl polymerization initiated by the redox system thiourea-Mn3+ were investigated in the temperature range 30–40°C in sulfuric acid, and the rates of polymerization Rp and disappearance of Mn3+ have been measured. The effect of certain water-miscible organic solvents and anionic surfactant on the rates of polymerization was investigated. A mechanism involving the formation of a complex between Mn3+ and thiourea whose decomposition yields the initiating free radical with the polymerization terminated by mutual intraction of growing radicals is suggested. 相似文献
999.
Sreelakshmi Poola Mohan Gundluru Maheshwara Reddy Nadiveedhi Madhu Sudhana Saddala Prasada Rao P. T. S. R. K. 《Phosphorus, sulfur, and silicon and the related elements》2020,195(5):409-420
AbstractA new series of α-thiazolyl aminomethylene bisphosphonates were synthesized by a three component reaction of 4-aryl substituted thiazol-2-amine with different dialkyl/aryl phosphites and triethyl orthoformate in the presence of Ag NPs (nano particles) as a catalyst under solvent free conditions. All the synthesized target compounds were characterized by 1H, 13C, 31P, mass and elemental analysis. The target compounds were screened for their in vitro antioxidant, antibacterial and antifungal activity. Molecular docking studies were also performed. The results revealed that among the synthesized compounds tetramethyl(((4-(4-methoxyphenyl)thiazol-2-yl)amino) methylene)bis(phosphonate) (5d), tetramethyl(((4-(4-fluorophenyl)thiazol-2-yl)amino) methylene) bis(phosphonate) (5h), and tetramethyl(((4-(4-bromophenyl)thiazol-2-yl)amino)methylene) bis (phosphonate) (5j) showed remarkably higher antioxidant activity by DPPH and H2O2 than the standard ascorbic acid. Compounds tetramethyl(((4-phenyl thiazol-2-yl)amino) methylene) bis(phosphonate) (5a), 5d, 5h and tetraethyl(((4-(4-bromophenyl)thiazol-2-yl) amino)methylene)bis (phosphonate) (5k) showed good antibacterial activity. 5a, 5d, and 5h also showed rather higher antifungal activity than the standard flucanozole. Computational docking methods have been used to predict how several aminomethylene bisphosphonate derivatives compete against the inhibitor BPH-1330 at the crystal enzyme structure of the 4H3A protein active site and how R and R1 influence their binding ability. 相似文献
1000.
Amalu Mohan Devika Sasikumar Vinayak Bhat Mahesh Hariharan 《Angewandte Chemie (International ed. in English)》2020,59(8):3201-3208
The self‐assembly of chiral organic chromophores is gaining huge significance due to the abundance of supramolecular chirality found in natural systems. We report an interdigitated molecular assembly involving axially chiral octabrominated perylenediimide (OBPDI) which transfers chiral information to achiral aromatic moieties. The crystalline two‐component assemblies of OBPDI and electron‐rich aromatic units were facilitated through π‐hole???π donor–acceptor interactions, and the charge‐transfer characteristics in the ground and excited states of the OBPDI cocrystals were established through spectroscopic and theoretical techniques. The OBPDI cocrystals entail a remarkable homochiral segregation of P and M enantiomers of both molecular entities in the same crystal system, leading to twisted double‐racemic arrangements. Synergistically engendered cavities with the stored chiral information of the twisted OBPDI stabilize higher‐energy P/M enantiomers of trans‐azobenzene through non‐covalent interactions. 相似文献