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排序方式: 共有113条查询结果,搜索用时 15 毫秒
101.
H. J. Pant V. K. Sharma S. V. Naik Gursharan Singh D. B. Kalgutkar S. P. Patil N. Jayachandran V. K. P. Unni 《Journal of Radioanalytical and Nuclear Chemistry》2012,294(1):65-69
A radiotracer technique was used to investigate the leaching of an antifouling agent from different marine paint formulations with an objective to select the best paint formulation for bulk production. The antifouling agent (Diuron) itself was labeled with carbon-14 (half-life: 5,730?years, ??-energy: 156?keV) and used as a radiotracer. The different paint formulations added with radiolabeled Diuron were applied onto suitably selected substrates and measured for initial intensity of ??-radiation using a Geiger-Muller detector connected to a ratemeter. The painted substrates were subjected to shower tests for a pre-decided time and subsequently measured for ??-radiations. The comparison of intensity of ??-radiations in substrates prior and post shower tests provides information about leaching of antifouling agent Diuron from the paint formulation. The high leaching percentage of antifouling agent Diuron post shower tests indicates non-suitability of paint formulation for marine and civil structures. However, low leaching rate of Diuron will make a paint formulation more efficient and suitable. Based on the results of investigation, a paint formulation with minimum leaching rate was identified and selected for bulk production by a paint company. 相似文献
102.
103.
Zirui Liu Vishnu R. Unni Swetaprovo Chaudhuri Chung K. Law Abhishek Saha 《Proceedings of the Combustion Institute》2021,38(2):1993-2000
We, herein, report an experimental study to investigate the role of local flamefront dynamics on the propagation and acceleration of cellularly unstable premixed expanding laminar flames. Using simultaneous Mie-scattering imaging and Particle Image Velocimetry, we measured the flame edge location and its adjacent flow field, which were subsequently processed to quantify the evolution of the probability density functions (pdfs) of flow velocities, curvature, normal strain rate and tangential strain rate. We showed that appropriate normalizaton of the measured quantities can unify the data from different pressures when identified with the corresponding Peclet number, defined as the ratio of the flame radius to the flame thickness. Since the flamefront is stable and smooth at lower Peclet numbers, the flame-induced flow field and stretch rates are almost uniform over the flamefront, resulting in narrow pdfs. At higher Peclet numbers, however, the flame becomes progressively more wrinkled and hence the variations in the local quantities increase leading to wider pdfs. Furthermore, while the mean curvature was found to be inversely proportional to the mean flame radius and insensitive to the cellular structure, the mean normal strain rate was strongly influenced by the cellular structure. 相似文献
104.
Densities ρ and ultrasonic speeds u of the binary mixtures of tetrahydrofuran (THF) with 1-butanol and tert-butanol, at 30°C, over the entire composition range
were measured. From these data isentropic compressibility, K
s, intermolecular free length L
f, relative association R
A, acoustic impedance Z, molar sound speed R
m, deviations in isentropic compressibility ΔK
s, and excess volume V
E were calculated. The variation of these parameters with composition of the mixture helps us in understanding the nature and
extent of interaction between unlike molecules in the mixtures. Further, theoretical values of ultrasonic speed were evaluated
using theories and empirical relations. The relative merits of these theories and relations were discussed. 相似文献
105.
We study the rheology of semi-dilute solutions of the sodium salt of calf-thymus DNA in the linear and nonlinear regimes.
The frequency response data can be fitted very well to the hybrid model with two dominant relaxation times τ0 and τ1. The ratio (τ0/τ1) ∼5 is seen to be fairly constant on changing the temperature from 20 to 30°C. The shear rate dependence of viscosity can
be fitted to the Carreau model. 相似文献
106.
Sathyaraj G Kiruthika M Weyhermüller T Nair BU 《Dalton transactions (Cambridge, England : 2003)》2012,41(27):8460-8471
Mixed ligand complexes of ruthenium(II), [Ru(itpy)(bpy)Cl]ClO(4)1, [Ru(itpy)(phen)Cl]ClO(4)2, [Ru(bitpy)(bpy)Cl]ClO(4)3 and [Ru(bitpy)(phen)Cl]ClO(4)4 have been synthesized and characterized. Complex 3 has also been characterized crystallographically. These complexes exhibit photolability of the Ru-Cl bond. Upon irradiation at 440 nm in the presence of nucleosides and nucleotides the complexes exchange chloride for the nucleoside or nucleotide. The photolability of the Ru-Cl bond depends on the nature of the substituent in the tridentate tpy ligand. Photolysis of the complexes in the presence of a nucleoside or nucleotide also produces 8-oxoguanine due to the oxidation of guanine by the excited states of the complexes. These four complexes exhibit photonuclease properties and bring about the cleavage of plasmid DNA when irradiated at 440 nm. These complexes have been found to be toxic towards NIH 3T3 cells under photolytic conditions. 相似文献
107.
Kinetics and mechanism of the cerium(IV) oxidation of Cr(III) complexes of a series of macrocyclic (or pseudomacrocyclic) ligands with [14]-membered intraligand ring-sizes have now been investigated at I = 1.0 M (LiClO4) Temp. 30°C. The complexes of the formulation Cr(macrocycle)(X)(H2O) where X = CHCl2 and H2O, n = 0 or 1 undergo oxidation to Cr(VI) with the formation of chromium(IV) intermediates. The observed kinetic parameters for the Ce(IV) oxidation of Cr(III) macrocyclic complexes have been discussed in terms of changes brought about by the macrocyclic ligands on the Cr(III)—Cr(IV) redox potentials and in specific rates for Cr(IV)—Cr(V) conversion. On the basis of this study, it has been suggested that the trapping of Cr(IV) is easier when a macrocyclic ligand having a symmetrical intra-ligand ring size and unsaturation in the cyclic structure is coordinated equatorially. Cyclic voltammetric studies indicate the formation of Cr(IV) transient in the case of electrochemical oxidation of trans-Cr(Me4[14]tetraene)(H2O). 相似文献
108.
4-Vinyl pyridine (4-Vp) reacts with RuHClCO(PPh3)3 (I) in THF to give RuHClCO(PPh3)2(4-Vp) (II, which reacts with sodium derivatives of bidentate chelating ligands to afford substitution products, [RuH(CO)(PPh3)2(L)]. The bindentate ligands used are 2-hydroxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, trifluorothenoylacetone and 8-hydroxyquinoline. Insertion reactions of the Ru---H bond of II with activated olefins such as acrylonitrile [giving RuCl(CO)(CH3CHCN)(PPh3)2(4-Vp)], 2-vinyl pyridine, dimethyl fumarate and monobromodiethyl fumarate have been carried out to obtain chelated Ru---C bonded complexes. RuCl2(PPh3)3 reacts with an excess of 4-Vp to give an octahedral ruthenium addition complex containing two vinyl pyridine ligands. The dimer [RuClCO(CH3CHCN)(PPh3)(4-Vp)]2 is obtained by the reaction of [RuClCO(CH3CHCN)(PPh3)2]2 with an excess of 4-Vp. Stereochemical assignments have been made for these new complexes on the basis of IR and 1H NMR data. 相似文献
109.
Vijay Nair A.Unni VinodN Abhilash Rajeev S MenonV Santhi R.Luxmi VarmaS Viji Saumini MathewR Srinivas 《Tetrahedron》2003,59(51):10279-10286
The reaction of 1:1 zwitterionic intermediate generated in situ from dimethyl acetylenedicarboxylate (DMAD) and cyclohexyl isocyanide with aldehydes and quinones is described. The reaction of stoichiometric amounts of DMAD, isocyanide and aldehydes afforded 2-aminofurans in good yields, while the reaction with quinones gave iminolactones. 相似文献
110.
Vandana Tripathi Lagy T Baby PV Madhusudhana Rao SK Hui R Singh JJ Das P Sugathan N Madhavan AK Sinha 《Pramana》1999,53(3):535-539
The ground state and excited state transfer yields for the 2-neutron pickup channel in the 28Si+68Zn system have been measured explicitly. The recoil mass separator at the nuclear Science Centre, New Delhi was used for the
measurement. A NaI(T1) detector was used for detecting the deexcitation γ’s from the transfer products. The kinematic coincidence technique was employed for the transfer measurement. Simplified coupled
channels calculations show that out of all transfer channels the major contribution to the sub-barrier enhancement comes from
the ground state 2 neutron pickup channel with a ground state Q-value of+1.83 MeV. 相似文献