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61.
Wooster TJ Golding M Sanguansri P 《Langmuir : the ACS journal of surfaces and colloids》2008,24(22):12758-12765
The formation of stable transparent nanoemulsions poses two challenges: the ability to initially create an emulsion where the entire droplet size distribution is below 80 nm, and the subsequent stabilization of this emulsion against Ostwald ripening. The physical properties of the oil phase and the nature of the surfactant layer were found to have a considerable impact on nanoemulsion formation and stabilization. Nanoemulsions made with high viscosity oils, such as long chain triglycerides (LCT), were considerably larger ( D = 120 nm) than nanoemulsions prepared with low viscosity oils such as hexadecane ( D = 80 nm). The optimization of surfactant architecture, and differential viscosity eta D/eta C, has led to the formation of remarkably small nanoemulsions. With average sizes below 40 nm they are some of the smallest homogenized emulsions ever reported. What is more remarkable is that LCT nanoemulsions do not undergo Ostwald ripening and are physically stable for over 3 months. Ostwald ripening is prevented by the large molar volume of long chain triglyceride oils, which makes them insoluble in water thus providing a kinetic barrier to Ostwald ripening. Examination of the Ostwald ripening of mixed oil nanoemulsions found that the entropy gain associated with oil demixing provided a thermodynamic barrier to Ostwald ripening. Not only are the nanoemulsions created in this work some of the smallest reported, but they are also thermodynamically stable to Ostwald ripening when at least 50% of the oil phase is an insoluble triglyceride. 相似文献
62.
63.
We briefly review recent investigations on the transverse spin structure of the nucleon, based on the chiral quark-soliton model. We discuss the results of the tensor and anomalous tensor magnetic form factors and the corresponding transverse quark spin densities inside a nucleon. The results are compared with those of the recent lattice calculation. While their qualitative features are similar to the lattice ones, there are some discrepancies in the momentum dependence of the form factors and accordingly in the strengths of the transverse spin densities. 相似文献
64.
Tim ColletMatthias Steinhauser 《Physics letters. [Part B]》2011,704(3):163-165
The static potentials for systems of a heavy quark and anti-quark, two gluinos and a quark and a gluino are computed for all possible color configurations of a SU(Nc) gauge group. 相似文献
65.
Isothermal vapor–liquid equilibrium (VLE) and excess enthalpy (HE) data were measured for binary systems required for the design of reactive distillation processes for the methyl acetate production. The isothermal P–x data were measured with the help of a computer-operated static apparatus. A commercial isothermal flow calorimeter was used for the determination of the heats of mixing. Temperature-dependent interaction parameters for the UNIQUAC model were fitted simultaneously to the experimental data from this work and other authors. 相似文献
66.
We study the filling length function for a finite presentation of a group , and interpret this function as an optimal bound on the length of the boundary loop as a van Kampen diagram is collapsed to the basepoint using a combinatorial notion of a null-homotopy. We prove that filling length is well behaved under change of presentation of . We look at 'AD-pairs' (f,g) for a finite presentation
: that is, an isoperimetric function f and an isodiametric function g that can be realised simultaneously. We prove that the filling length admits a bound of the form [g+1][log (f+1)+1] whenever (f,g) is an AD-pair for
. Further we show that (up to multiplicative constants) if
is an isoperimetric function (
) for a finite presentation then (
) is an AD-pair. Also we prove that for all finite presentations filling length is bounded by an exponential of an isodiametric function.Partially supported by NSF grant DMS-9800158Supported by EPSRC Award No. 98001683 and Corpus Christi College, Oxford. 相似文献
67.
Hsu KF Chung DY Lal S Mrotzek A Kyratsi T Hogan T Kanatzidis MG 《Journal of the American Chemical Society》2002,124(11):2410-2411
The new materials CsPbBi(3)Te(6) and CsPb(2)Bi(3)Te(7) were discovered through reactions of CsBi(4)Te(6) with PbTe, whereas the isostructural materials CsSnBi(3)Te(6) and CsSn(2)Bi(3)Te(7) were discovered through corresponding reactions with SnTe. The compounds can also be prepared from stoichiometric mixtures of Cs(2)Te, Pb (Sn), Bi, and Te. The crystal structures show a layered architecture of NaCl-type slabs alternating with layers of Cs atoms. This group of compounds offers a new quaternary system, Cs-M-Bi-Te (M = Pb and Sn), available for thermoelectric investigations, including fine-tuning of compositions and doping. 相似文献
68.
In this paper we report on a project in which we explored with a number of officers from different charities their beliefs about charitable giving, and built explicit models of these beliefs so that they might be examined in a more systematic way than they can be when just talking about them. We discuss some of the issues and problems around creating and using explicit models of individuals' beliefs to share wisdom, and report some of the things that happened when we sought to do this. We suggest that our approach provides practical help with the problems of sharing views.OR has traditionally been geared to those organizations who are able and willing to pay for it; in this paper we report on an OR project in organizations to whom it has not usually been available. 相似文献
69.
[chemical reaction: see text]. Prior to detachment of compounds synthesized on sulfonamide based safety-catch linkers, the molecular anchor has to be activated. This is achieved by alkylation of the nitrogen atom of the N-acylsulfonamide using different established protocols. As an addition to the existing repertoire of activating reagents, we suggest the use of O,N,N'-trialkylisoureas. Besides the demonstration of the feasibility of these mild alkylating agents for this purpose, custom-tailored novel O,N,N'-trialkylisoureas prepared from electron-deficient alcohols are reported. 相似文献
70.
Vorontsov II Kovalevsky AY Chen YS Graber T Gembicky M Novozhilova IV Omary MA Coppens P 《Physical review letters》2005,94(19):193003
Time-resolved single-crystal diffraction performed with synchrotron radiation shows that the 53(1) micros phosphorescent state, generated in the crystalline phase of trimeric {[3,5-(CF3)(2)Pyrazolate]Cu}(3) molecules by exposure to 355 nm of light at 17 K, is due to the formation of an excimer rather than the shortening of the intramolecular Cu...Cu distances within the trimeric units, or the formation of a continuous chain of interacting molecules. One of the intermolecular Cu...Cu distances contracts by 0.56 Angstroms from 4.018(1) to 3.46(1) Angstroms;, whereas the interplanar spacing of the trimers is reduced by 0.65 Angstroms; from 3.952(1) to 3.33(1) Angstroms. Density-functional theory calculations support the formation of a Cu...Cu bond through the intermetallic transfer of a Cu 3d electron to a molecular orbital with a large 4p contribution on the reacting Cu atoms. 相似文献