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11.
Wu S Shi L Garfield LB Tabor RF Striolo A Grady BP 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):6091-6098
The influence of surface roughness on surfactant adsorption was studied using a quartz crystal microbalance with dissipation (QCM-D). The sensors employed had root-mean-square (R) roughness values of 2.3, 3.1, and 5.8 nm, corresponding to fractal-calculated surface area ratios (actual/nominal) of 1.13, 1.73, and 2.53, respectively. Adsorption isotherms measured at 25 °C showed that adsorbed mass of cetyltrimethylammonium bromide per unit of actual surface area below 0.8 cmc, or above 1.2 cmc, decreases as the surface roughness increases. At the cmc, both the measured adsorbed amount and the measured dissipation increased dramatically on the rougher surfaces. These results are consistent with the presence of impurities, suggesting that roughness exacerbates well-known phenomena reported in the literature of peak impurity-related adsorption at the cmc. The magnitude of the increase, especially in dissipation, suggests that changes in adsorbed amount may not be the only reason for the observed results, as aggregates at the cmc on rougher surfaces are more flexible and likely contain larger amounts of solvent. Differences in adsorption kinetics were also found as a function of surface roughness, with data showing a second, slower adsorption rate after rapid initial adsorption. A two-rate Langmuir model was used to further examine this effect. Although adsorption completes faster on the smoother surfaces, initial adsorption at zero surface coverage is faster on the rougher surfaces, suggesting the presence of more high-energy sites on the rougher surfaces. 相似文献
12.
K. G. O’Grady 《Geometric And Functional Analysis》2005,15(6):1223-1274
A K3 surface with an ample divisor of self-intersection 2 is a double cover of the plane branched over a sextic curve. We conjecture
that similar statement holds for the generic couple (X, H) with X a deformation of (K3)[n] and H an ample divisor of square 2 for Beauville’s quadratic form. If n = 2 then according to the conjecture X is a double cover of a singular) sextic 4-fold in
It follows from the conjecture that a deformation of (K3)[n] carrying a divisor (not necessarily ample) of degree 2 has an anti-symplectic birational involution. We test the conjecture.
In doing so we bump into some interesting geometry: examples of two antisymplectic involutions generating an interesting dynamical
system, a case Strange duality and what is probably an involution on the moduli space degree-2 quasi-polarized (X, H) where X is a deformation of (K3)[2].
Received: June 2004 Revision: December 2004 Accepted: January 2005 相似文献
13.
Grady D. Carney 《Chemical physics》1980,54(1):103-107
Previous ab initio studies of deuterated H+3 molecular ions are extended to include rotational modes for the zero-point states of vibration. Rotation energies are obtained using direct numerical diagonalization of vibration—rotation hamiltonian matrices, and nuclear wavefunctions as superpositions of mode-coupled anharmonic rotationless vibrators and related prolate symmetric top eigenfunctions. Relevance to recent searches for interstellar H2D+ is noted. 相似文献
14.
Annals of Combinatorics - For a poset whose Hasse diagram is a rooted plane forest F, we consider the corresponding tree descent polynomial $$A_F(q)$$, which is a generating function of the number... 相似文献
15.
Grady T. Phillips 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(10):1875-1885
The dependence of pressure broadening upon hyperfine component in the P(10) and P(70) lines of the (17,1) band of the I2 X1Σ(0g+)→B3Π(0u+) has been studied using laser saturation spectroscopy. By limiting absorption to the zero velocity group, Doppler broadening is removed, lineshapes with widths (FWHM) <9 MHz are detectable, and collision-induced broadening is measured at pressures of 0.2-1.2 Torr. The rates for broadening by argon are 8.3±0.3 and 10.7±0.4 MHz/Torr for the P(70) and P(10) lines, respectively. No significant variation in broadening rates is observed for the 15 hyperfine components of these even rotational lines. The effects of velocity cross-relaxation introduce a broad baseline into the spectra, which is strongly dependent on rotational state, pressure, and laser modulation frequency. The observed broadening rates correlate well with prior measurements and the polarizability of the collision partner. 相似文献
16.
A. Carter L.E. Fernandez-Outon Y. Inaba S.J. Greaves H. Muraoka K. O’Grady 《Journal of magnetism and magnetic materials》2008
The distribution of easy axis orientation in perpendicular media is of technological importance because it affects the value of S* (see Fig. 1), which quantifies the switching field distribution (SFD) and hence partially determines the data density achievable on a given medium. The distribution is controlled by the crystallographic orientation of grains and factors such as intergranular exchange and dipolar coupling. Due to strong demagnetising fields in the perpendicular orientation, traditional measurements of remanence as a function of angle are difficult to interpret and have required the use of large-scale computational models. In this work we have utilised the variation of coercivity HC with angle, which has the advantage that at HC the global demagnetising field is zero. Additionally, since such materials follow essentially the Stoner–Wohlfarth mode of reversal, the variation of HC with angle, HC(θ), is much greater than that for the remanence. We find that for (CoCrPt)1−x(SiO2)x, where the level of exchange coupling is controlled, the distribution of magnetic easy axes is narrower when the exchange coupling is reduced, but dipolar coupling between the grains is strong and affects the magnetisation reversal significantly. 相似文献
17.
A critical review of recent developments in the use of chemometric experimental design based optimization techniques in capillary
electrophoresis applications is presented. Current advances have led to enhanced separation capabilities of a wide range of
analytes in such areas as biological, environmental, food technology, pharmaceutical, and medical analysis. Significant developments
in design, detection methodology and applications from the last 5 years (2002–2007) are reported. Furthermore, future perspectives
in the use of chemometric methodology in capillary electrophoresis are considered. 相似文献
18.
Anatoly N. Nikitin Michael C. Grady Georgios A. Kalfas Robin A. Hutchinson 《大分子反应工程》2008,2(5):422-435
Batch experiments were carried out to investigate the kinetics of catalytic chain transfer copolymerization of methyl methacrylate and n‐butyl methacrylate. The Predici® model developed to represent the system describes the numerous experimental data measured at high concentrations of Co(II ) catalyst, taking into account the chain‐length dependencies of termination, propagation and catalytic chain transfer. The constants for catalytic chain transfer are determined as 2.3 × 104 for both methyl methacrylate and n‐butyl methacrylate from fitting the experimental data. Two inhibition mechanisms are shown to describe the decrease of the polymerization rate in the presence of catalyst equally well, with an unknown impurity dissolved in initiator introduced to explain experimental profiles measured at high initiator concentrations.
19.
The development of iodide-based methods for batch and on-line determinations of phosphite in aqueous samples 总被引:2,自引:0,他引:2
Recent developments in the field of microbiology and research on the origin of life have suggested a possible significant role for reduced, inorganic forms of phosphorus (P) such as phosphite [HPO32−, P(+III)] and hypophosphite [H2PO2−, P(+I)] in the biogeochemical cycling of P. New, robust methods are required for the detection of reduced P compounds in order to confirm the importance of these species in the overall cycling of P in the environment. To this end, we have developed new batch and flow injection (FI) methods for the determination of P(+III) in aqueous solutions. The batch method is based on the reaction of P(+III) with a mixed-iodide solution containing tri-iodide (I3−) and penta-iodide (I5−). The oxidation of P(+III) consumes free I3− and I5− in solution. The remaining I3− and I5− subunits are then allowed to react with the amylose content in starch to form a blue complex, which has a λmax of 580 nm. The measurement of this blue complex is directly correlated with the concentration of P(+III). The on-line FI method employs the same reaction between P(+III) and mixed-iodide producing phosphate [P(+V)] that is determined spectrophotometrically by the molybdenum blue method employing ascorbic acid at a λmax of 710 nm. The linear range for both the batch and FI determination of P(+III) was 1.0–50 μM with detection limits of 0.70 and 0.36 μM, respectively. Interference studies for the batch method show that arsenite [As(+III)] and sulfite [S(+IV)] can also be determined by this technique; however, these interferences can be circumvented by oxidizing As(+III) and S(+IV) using KMnO4 which is an ineffective oxidant for P(+III). Both methods were applied to P(+III) determinations in ultra-pure water and simulated creek water. Results and analytical figures of merit are reported and future work is considered. 相似文献
20.
Marquez M Patel K Carswell AD Schmidtke DW Grady BP 《Langmuir : the ACS journal of surfaces and colloids》2006,22(19):8010-8016
A novel method for the formation of nanometer-scale polymer structures via template assisted admicellar polymerization (TAAP) is described. Admicellar polymerization uses a surfactant layer adsorbed on a surface to localize monomer to the surface prior to polymerization of the monomer. Nanostructures are formed by restricting adsorption to the uncovered sites of an already-templated surface, in this case to the interstitial sites between adsorbed latex spheres. Unlike most other process that form polymer nanostructures, polymer dimensions can be significantly smaller than the interstitial size because of sphere-surfactant interactions. Protein adsorption in the interstitial sites of colloidal arrays was also studied for three different proteins, and the results were compared with those obtained via admicellar polymerization. 相似文献