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171.
Delacotte J Montel L Restagno F Scheid B Dollet B Stone HA Langevin D Rio E 《Langmuir : the ACS journal of surfaces and colloids》2012,28(8):3821-3830
We present a large range of experimental data concerning the influence of surfactants on the well-known Landau-Levich-Derjaguin experiment where a liquid film is generated by pulling a plate out of a bath. The thickness h of the film was measured as a function of the pulling velocity V for different kinds of surfactants (C(12)E(6), which is a nonionic surfactant, and DeTAB and DTAB, which are ionic) and at various concentrations near and above the critical micellar concentration (cmc). We report the thickening factor α = h/h(LLD), where h(LLD) is the film thickness obtained without a surfactant effect, i.e., as for a pure fluid but with the same viscosity and surface tension as the surfactant solution, over a wide range of capillary numbers (Ca = ηV/γ, with η being the surfactant solution viscosity and γ its surface tension) and identify three regimes: (i) at small Ca α is large due to confinement and surface elasticity (or Marangoni) effects, (ii) for increasing Ca there is an intermediate regime where α decreases as Ca increases, and (iii) at larger (but still small) Ca α is slightly higher than unity due to surface viscosity effects. In the case of nonionic surfactants, the second regime begins at a fixed Ca, independent of the surfactant concentration, while for ionic surfactants the transition depends on the concentration, which we suggest is probably due to the existence of an electrostatic barrier to surface adsorption. Control of the physical chemistry at the interface allowed us to elucidate the nature of the three regimes in terms of surface rheological properties. 相似文献
172.
T Ohtsubo NJ Stone JR Stone IS Towner CR Bingham C Gaulard U Köster S Muto J Nikolov K Nishimura GS Simpson G Soti M Veskovic WB Walters F Wauters 《Physical review letters》2012,109(3):032504
The nucleus ^{49}Sc, having a single f_{7/2} proton outside doubly magic ^{48}Ca (Z=20, N=28), is one of the very few isotopes which makes possible testing of the fundamental theory of nuclear magnetism. The magnetic moment has been measured by online β NMR of nuclei oriented at milli-Kelvin temperatures to be (+)5.616(25) μ_{N}. The result is discussed in terms of a detailed theory of the structure of the magnetic moment operator, showing excellent agreement with calculated departure from the f_{7/2} Schmidt limit extreme single-particle value. The measurement completes the sequence of moments of Sc isotopes with even numbers of f_{7/2} neutrons: the first such isotopic chain between two major shells for which a full set of moment measurements exists. The result further completes the isotonic sequence of ground-state moments of nuclei with an odd number of f_{7/2} protons coupled to a closed subshell of f_{7/2} neutrons. Comparison with a recent shell-model calculation of the latter sequence is made. 相似文献
173.
P. Sullivan J. Moate B. Stone J. D. Atkinson Z. Hashisho M. J. Rood 《Adsorption》2012,18(3-4):265-274
A recently developed carbon material, electrospun Activated Carbon nanoFiber (ACnF), exhibits strong potential for use as an adsorbent for toxic industrial chemicals (TICs). As-prepared ACnF contains as much as 9.6?wt% nitrogen, creating a basic surface that enhances acid-gas adsorption. ACnF shows 4–20 times greater HCN adsorption capacities and 2–5 times greater SO2 adsorption capacities in dry nitrogen, compared to commercially available activated carbon fiber cloth (ACFC) and Calgon BPL? granular activated carbon, which are considered here as reference adsorbents. ACnF has 50?% of the micropore volume (0.30?cm3/g) of these reference adsorbents, which limits its adsorption capacity at high concentrations for volatile organic compounds (>500?ppmv). However, at low concentrations (<500?ppmv), ACnF has a similar capacity to ACFC and about three times the VOC adsorption capacity of Calgon BPL?. ACnF’s small fiber diameters (0.2–1.5?μm) allow for higher mass transfer coefficients, resulting in adsorption kinetics nearly twice as fast as ACFC and eight times as fast as Calgon BPL?. ACnF drawbacks include hydrophilicity and reduced structural strength. The rapid adsorption kinetics and high capacity for acidic TICs warrant further investigation of ACnF as an adsorbent in respiratory protection and indoor air quality applications. 相似文献
174.
Background
Taste receptor cells are responsible for transducing chemical stimuli into electrical signals that lead to the sense of taste. An important second messenger in taste transduction is IP3, which is involved in both bitter and sweet transduction pathways. Several components of the bitter transduction pathway have been identified, including the T2R/TRB taste receptors, phospholipase C β2, and the G protein subunits α-gustducin, β3, and γ13. However, the identity of the IP3 receptor subtype in this pathway is not known. In the present study we used immunocytochemistry on rodent taste tissue to identify the IP3 receptors expressed in taste cells and to examine taste bud expression patterns for IP3R3. 相似文献175.
Supercritical fluid extraction was coupled on-line with reversed-phase high-performance liquid chromatography (HPLC). An open-tubular column with a 95% methyl-5% phenyl stationary phase was utilized as an interface between the two systems. This phase allowed for good analyte focusing onto the packed analytical column and exhibited low reactivity. Due to the non-polar nature of this phase there was a low tendency for analytes to be prematurely rinsed off the interface by condensed modifier. Using this approach, it was possible to transfer the extracted analytes quantitatively to the HPLC column in the presence of as much as 10% (v/v) methanol. By placing a 10 m guard column at the head of the interface, the same could be accomplished with ethanol as the modifier: allowing the extraction to be conducted entirely with non-toxic fluids. The method also allowed the use of very practical extraction parameters in terms of amount extracted, extraction flow-rate, extraction vessel volume, and extraction time. 相似文献
176.
Sean A.C. McDowell C. Ruth Le Sueur A. David Buckingham Anthony J. Stone 《Molecular physics》2013,111(5):823-835
The integrated intensities of vibrational transitions depend on the magnitude of the derivatives of the dipole with respect to nuclear motion. Normally, the only reliable way to compute such derivatives is by tedious and expensive ab initio calculations. In this paper, we present a simplification for weakly bound complexes based on distributed schemes for describing the charge densities and polarizabilities of the monomers. Formulations based on both Cartesian and spherical harmonics are presented. The results for both these schemes agree exactly with each other, and qualitatively with full ab initio calculations for the hydrogen fluoride dimer, (HF)2. 相似文献
177.
M. R. Menlyadiev J. A. Stone G. A. Eiceman 《International Journal for Ion Mobility Spectrometry》2012,15(3):123-130
A tandem ion mobility spectrometer with two sequential differential mobility spectrometry (DMS) drift tubes and with detectors at ambient pressure is described and modes of operation are demonstrated. Separate but coordinated electronic control for each drift tube allows several modes of operation including: all ions passing; compensation voltage (CV) scanning; and ion selection over a narrow CV range. Any of these modes can be applied to each drift tube allowing several combinations of analytical measurements, analogous to tandem mass spectrometry, with ions entered into a gas atmosphere containing reagents between the mobility regions. Ions may be changed by cluster or displacement reactions and characterized in the second DMS analyzer. Proton bound dimers of compounds appearing near 0?V CV in DMS1 were isolated in DMS1, introduced into 1?% isopropanol vapors, and resolved at characteristic CV values in the DMS2. This is achieved with analyzer dimensions little greater than a single DMS instrument. 相似文献
178.
R. Zeisler S. F. Stone R. P. Viscidi E. H. Cerny 《Journal of Radioanalytical and Nuclear Chemistry》1993,167(2):445-452
The feasibility of performing immunoassays with colloidal gold labels and detection of198Au by neutron activation has been demonstrated with measurements of human immunoglobulin and of serum antibodies to human immunodeficiency virus type 1. The detection sensitivity achieved after activation in a high flux reactor or with a water moderated252Cf source, by gamma-counting or by autoradiography, is similar to the sensitivity obtained with absorbance measurements in the more common enzyme immunoassays. The reactor based neutron activation assay allows detection of 10–16 mol of analyte in routine operation with possible extension to 10–20 mol. The sensitivity with the 1.3 Ci252Cf source is limited to about 10–15 mol. The practical limitations of the assay's sensitivity at this point are due to background signals from reagents and/or nonspecific binding of the gold labeled reagent. 相似文献
179.
R. Eder C. J. Ashworth I. Berkes D. E. Brown U. Daemmrich I. S. Grant A. G. Griffiths E. Hagn R. Hassani P. Herzog S. Ohya M. Massaq C. Richard-Serre J. Rikovska K. Schloesser N. Severijns N. J. Stone W. Vanderpoorten J. Vanhaverbeke L. Vanneste T. Woelfle E. Zech Isolde Collaboration 《Hyperfine Interactions》1988,43(1-4):469-472
Nuclear orientation and nuclear magnetic resonance experiments were performed on185, 187, 189Pt isotopes oriented in Fe and single crystal Zn at temperatures down to about 6 mK. The hyperfine splitting frequencies of185Pt and187Pt in iron were determined to be 164.9(2) and 261.1(2) MHz, respectively. With the hyperfine field of −126.1(2.5) T, the g-factors
are deduced to be |g(185Pt)|=0.172(3) and |g(187Pt)|=0.272(5).
The spectroscopic quadrupole moment of187Pt was found to be negative with magnitude similar to that of189Pt, indicating a predominantly oblate ground state deformation for both isotopes. The spectroscopic quadrupole moment of185Pt was found to be positive, with the ratio Q(185Pt)/Q(189Pt)=−3.6(9), clearly indicating a change to prolate ground state deformation. 相似文献
180.
G. White J. Rikovska N. J. Stone J. Copnell I. S. Towner A. M. Oros K. Heyde B. Fogelberg L. Jacobsson F. Gustavsson 《Nuclear Physics A》1998,640(3-4):322-336
On-line low temperature nuclear orientation (OLNO) experiments have been performed on the odd-A Te isotopes 131Te and 133Te using the technique of nuclear magnetic resonance on oriented nuclei (NMR/ON). The magnetic moments of the isomeric 11/2− states have been measured extending the known data on these states in the Te isotopes up to the neutron shell closure at N = 82. The contribution to the 11/2− magnetic moment in 133Te due to core polarisation is calculated using an RPA shell model as well as corrections to the magnetic dipole operator caused by mesonic exchange currents. The neutron number dependence of the magnetic moments of the 11/2− isomers in heavy Te isotopes is discussed in terms of particle-core coupling model (PCM) calculations. 相似文献