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Optical microcavities and waveguides coupled to diamond are needed to enable efficient communication between quantum systems such as nitrogen-vacancy centers which are known already to have long electron spin coherence lifetimes. This paper describes recent progress in realizing microcavities with low loss and small mode volume in two hybrid systems: silica microdisks coupled to diamond nanoparticles, and gallium phosphide microdisks coupled to single-crystal diamond. A theoretical proposal for a gallium phosphide nanowire photonic crystal cavity coupled to diamond is also discussed. Comparing the two material systems, silica microdisks are easier to fabricate and test. However, at low temperature, nitrogen-vacancy centers in bulk diamond are spectrally more stable, and we expect that in the long term the bulk diamond approach will be better suited for on-chip integration of a photonic network.

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To determine the molecular mechanisms for cold cataract formation in the nucleus of the young mammalian lens, we have investigated the thermally reversible opacification of -crystallin solutions isolated from calf lens. Coexistence curves (plots of opacification temperature Tc versus protein concentration) were determined for the individual y-crystallin fractions II, III, and IV as well as for the unfractionated -crystallin mixtures isolated from the nucleus and cortex. The coexistence curve of yIV-crystallin is remarkably elevated above those of y4I-and yIII-crystallin and the -crystallin mixtures. The yIV-crystallin fraction is the major determinant of the opacification temperature within the whole lens or isolated cytoplasm. Quasielastic light-scattering spectroscopy of yIV-crystallin solutions indicates that above Tc there are two populations of protein aggregates of distinctly different mean size. As the temperature is lowered towards Tc, both populations increase in size. Opacification occurs when the population of large scatterers, which is composed of <0.1% protein by weight, reaches an average radius of about 20,000 A.The cytoplasm in eye lens cells contains a highly concentrated solution of lens-specific proteins, the crystallins. Their concentration increases from =250 to 400 g/liter going from cortex to nucleus, thus establishing the refractive index gradient required for proper focusing of incident light (1). The cytoplasm is normally transparent because of short-range ordering of the crystallins (2, 3). Mammalian lenses contain primarily a-crystallins (Mr 700,000-1,200,000), l3-crystallins (Mr 50,000-300,000) and -crystallins (Mr 20,000) (1,4,5). Their relative proportions vary with age and location within the lens as a result of both differential synthesis during development and selective degradation and insolubilization with aging (4-15). The lens nucleus is highly enriched in -crystallins, which are monomeric, basic proteins rich in sulfhydryl groups (8,(16)(17)(18)(19). The majority of human cataracts represent an irreversible opacification of the lens nucleus that progresses with age, a condition that is accompanied by oxidation of sulfhydryl groups, aggregation, and insolubilization of the various crystallins (4,8,13,(20)(21)(22)(23).The cold cataract phenomenon observed in most young mammalian lenses (e.g., calf, rat, and rabbit) is a convenient model system to study the relationship between nuclear opacification and -crystallin aggregation. A temperaturedependent reversible opacification can be induced in the nucleus of these young lenses (24)(25)(26)(27)(28). This behavior appears to be an intrinsic property of the concentrated mixture of crystallins, since it also can be induced in purified, membranefree cytoplasmic extracts of lens nucleus (27,(29)(30)(31)(32). Cold cataract has been modeled as a reversible phase-separation phenomenon (26)(27)(28)(29)(30)(31)(32). Upon lowering the temperature below a critical value Tc, the cytoplasm separates into protein-rich and protein-poor d...

A study of the evaporation of polystyrene sphere−H2O suspensions placed on nonwetting surfaces was conducted using a video camera and computer-imaging interface. The height, diameter, contact angle, and mass were measured as functions of time for a range of sessile drop sizes, polystyrene sphere diameters, and initial suspension concentrations. For initial concentrations of polystyrene spheres greater than approximately 8%, the drop diameter changed by less than 5%, and universal trends, independent of the sphere and droplet size, in the time dependence of the height, mass, and contact angle were observed. Those situations for which the polystyrene sphere concentration was less than approximately 8% showed a larger variation of diameter with time. For the case where the diameter remained constant, a theoretical model, which is analogous to the Landau theory of phase transitions, successfully predicts the experimental height and mass data over the entire evaporation range.

We have used light scattering techniques to measure the size and flexibility of grown sodium dodecyl sulfate (SDS) micelles in aqueous NaCl solutions as a function of temperature, surfactant concentration, and salt concentration. The mean hydrodynamic radius (R̄h) was determined using quasielastic light scattering, and the mean radius of gyration (R̄g) was measured using static light scattering. A theory of flexible rod-like objects is compared to the data. This theory predicts that for flexible rod-like micelles R̄g/R̄h will depend not only on R̄h but also on the persistence length, a measure of micellar flexibility. The data are found to be consistent with flexible rod-like micelles whose mean persistence length (〈l〉) depends weakly on SDS concentration and strongly on temperature and NaCl concentration. In the temperature range from 20–37 °C in 0.8 M NaCl and 30–50 °C in 1 M NaCl solution we find 〈l〉∝exp(−w/kBT) with w=4.7±0.5×10−12 erg.

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The temperature dependence of the orientational order parameters 〈P_{2}(cosβ)〉 and 〈P_{4}(cosβ)〉 in the nematic (N) and twist-bend nematic (N_{tb}) phases of the liquid crystal dimer CB7CB have been measured using x-ray and polarized Raman scattering. The 〈P_{2}(cosβ)〉 obtained from both techniques are the same, while 〈P_{4}(cosβ)〉, determined by Raman scattering is, as expected, systematically larger than its x-ray value. Both order parameters increase in the N phase with decreasing temperature, drop across the N-N_{tb} transition, and continue to decrease. In the N_{tb} phase, the x-ray value of 〈P_{4}(cosβ)〉 eventually becomes negative, providing a direct and independent confirmation of a conical molecular orientational distribution. The heliconical tilt angle α, determined from orientational distribution functions in the N_{tb} phase, increases to ∼24^{∘} at ∼15 K below the transition. In the N_{tb} phase, α(T)∝(T^{*}-T)^{λ}, with λ=0.19±0.03. The transition supercools by 1.7 K, consistent with its weakly first-order nature. The value of λ is close to 0.25 indicating close proximity to a tricritical point.