A drop falling from a faucet is a common example of a mass fissioning into two or more pieces. The shape of the liquid in this situation has been investigated by both experiment and computer simulation. As the viscosity of the liquid is varied, the shape of the drop changes dramatically. Near the point of breakup, viscous drops develop long necks that then spawn a series of smaller necks with ever thinner diameters. Simulations indicate that this repeated formation of necks can proceed ad infinitum whenever a small but finite amount of noise is present in the experiment. In this situation, the dynamical singularity occurring when a drop fissions is characterized by a rough interface.

In this paper we address the shape of a low-viscosity fluid interface near the breaking point. Experiments show that the shape varies dramatically as a function of fluid viscosity. At low viscosities, the interface develops a region with an extremely sharp slope, with the steepness of the slope diverging with vanishing viscosity. Numerical simulations demonstrate that this tip forms as a result of a convective instability in the fluid; in the absence of viscosity this instability results in a finite time singularity of the interface far before rupture (in which the interfacial curvature diverges). The dynamics before the instability roughly follow the scaling laws consistent with predictions based on dimensional analysis, though these scaling laws are violated at the instability. Since the dynamics after rupture is completely determined by the shape at the breaking point, the time dependences of recoiling do not follow a simple scaling law. In the process of demonstrating these results, we present detailed comparisons between numerical simulations and experimental drop shapes with excellent agreement.

We report the studies of the elasticity of C6o single crystals. For sublimed fee crystals, Young's modulus has an 8% jump at the first-order transition at 260 K. At -160 K there is a frequencydependent elastic anomaly resulting from time-dependent stress relaxation. Comparison with rotation rates seen in NMR suggests that the dynamics below 260 K is more complex than jumps between equivalent molecular configurations. Solvent grown monoclinic crystals have a second-order transition at 242 K, while the 160-K glass transition remains unchanged.PACS numbers: 62.20. Dc, 61.65.+d, 62.80.+f, 64.70.Kb The success in efficiently synthesizing C6o [1,2] has generated much interest in the physical properties of this new class of molecular crystals. Spectroscopic studies on C6o crystals using techniques such as x-ray, NMR, and neutron diffraction have revealed that an orientationalordering-induced face-centered-cubic (fee) to simplecubic (sc) transition occurs at temperatures around 260 K and rotational motions of C6o molecules persist to much lower temperatures [3-6], In this paper we present the first elastic constant measurement on C6o single crystals which confirms the first-order nature of the 260-K transition, and shows a dramatic discontinuous change (an 8% stiffening) in the moduli at the transition temperature. Moreover, a frequency-dependent elastic anomaly at 160 K demonstrates that stress relaxation is related to rotational motions of the C6o molecules in the orientationally ordered phase. This necessitates a more complex dynamics than envisioned in the NMR experiments with the C6o molecules jumping between inequivalent configurations or undergoing collective rotations at low temperatures.In Fig. 1 we show the temperature dependences of the sound velocity and attenuation in one sublimation-grown C6o crystal. The samples, shaped as platelets with typical dimensions of 0.6 mm x0.3 mm x0.2 mm, were grown from slow vaporization of solid C6o over a temperature gradient [7]. Their room-temperature structure is pure fee [81. We used a modified vibrating-reed technique [9,10] to measure the Young's sound velocity and attenuation. Because of the small physical dimensions of the fee samples, metal blocks were clamped on the platelet ends. The Young's modulus of the crystal provides the restoring force for the resonance of the block mass. The resonant frequency is proportional to the Young's sound velocity, so that relative changes of the velocity with varying temperatures can be directly measured, but the absolute value depends sensitively on the geometries.Around room temperature, the sound velocity shows a small maximum at -290 K. The most dramatic feature

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An onion-phase (multilamellar vesicular phase or Lalpha-phase) was prepared from salt-free zero-charged cationic and anionic (catanionic) surfactant mixtures of tetradecyltrimethylammonium hydroxide (TTAOH)/lauric acid (LA)/H2O. The H+ and OH- counterions form water (TTAOH + LA --> TTAL + H2O), leaving the solution salt free. The onion-phase solution has novel properties including low conductivity, low osmotic pressure and unscreened electrostatic repulsions between cationic and anionic surfactants because of the absence of salt. The spherical multilamellar vesicles have an average 250 nm radius as measured by freeze-fracture transmission electron microscopy (FF-TEM) and the maximum interlayer distance, i.e., the thickness of the hydrophobic bilayer and the water layer, was calculated to be around 52 nm by small-angle X-ray scattering (SAXS). Extremely hydrophobic C60 fullerene can be solubilized in this salt-free zero-charged aqueous onion-phase. As a typical result, 0.588 mg.mL(-1) (approximately 0.82 mmol.L(-1)) C60 has been successfully solubilized into a 50 mmol.L(-1) catanionic surfactant onion-phase aqueous solution. The weight ratio of fullerene to TTAL is calculated to be around 1:40. Solubilization of C60 in the salt-free catanionic onion-phase solution was investigated by using different sample preparation routes, and a variety of techniques were used to characterize these vesicular systems with or without encapsulated C60. The onion-phase solution changed color from slightly bluish to yellow or brown after C60 was solubilized. 1H and 13C NMR measurements indicated that the C60 molecules are located in the hydrophobic layers, i.e., in the central positions [omega-CH3 and delta-(CH2)x] of the hydrophobic layers of the TTAL onion-phase. Salt-free zero-charged catanionic vesicular aqueous solutions are good candidates for enhancing the solubility of C60 in aqueous solutions and may broaden the functionality of fullerenes to new potential applications in biology, medicine, and materials. Hopefully, our method can also be extended to solubilize functionalized carbon nanotubes in aqueous solutions.

Solar radiation causes cutaneous photodamage characterized by alterations in the quantity and structure of the extracellular matrix. We determined the direct and cytokine-mediated effects of UV irradiation on mRNA levels for two matrix elements, tropoelastin and fibrillin 1. (i) Comparison of normal versus end-stage photodamaged skin failed to reveal differences in these message levels. (ii) Acutely irradiated skin showed suppression of both tropoelastin and fibrillin mRNAs. (iii) UVB irradiation (50 mJ) of cultured skin fibroblasts suppressed fibrillin mRNA by 50%, consistent with a direct effect of radiation. Addition to the cultured fibroblasts of several cytokines upregulated by UVB showed that IL-1alpha had no effect on fibrillin mRNA in unirradiated cells, but in irradiated cells, this cytokine enhanced the suppression of fibrillin mRNA. There were no changes in the message stability, suggesting altered gene transcription. In contrast, UVB had no effect on tropoelastin mRNA levels in cultured fibroblasts, indicating the absence of a direct effect of radiation. IL-1alpha stimulated tropoelastin mRNA 2.8-fold in unirradiated cells, and this stimulation was entirely blocked by UVB. Overall, our results indicate acute suppression of matrix genes by UVB in vivo. The suppression of fibrillin message was a direct effect of UVB on fibroblasts and was augmented by IL-1alpha. Suppression of tropoelastin message by UVB occurred in vitro only in IL-1alpha-stimulated cells. We conclude that UVB substantially alters the pattern of cellular response to cytokines. The interplay between UVB and cytokines is essential to explain the acute responses of matrix genes to UVB in vivo.

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Male-released sex pheromone constituents of the longhorn beetle Anaglyptus subfasciatus (Coleoptera: Cerambycidae) are identified by GC-MS and GC-Fourier transform infrared as a 7:1 molar mixture of 3-hydroxy-2-hexanone and 3-hydroxy-2-octanone. These two compounds undergo thermal isomerization during GC analyses to give the corresponding 2-hydroxy-3-alkanones. Comparison of GC retention times of the natural products with those of synthesized enantiomerically pure compounds revealed that both semiochemicals have (R)-stereochemistry. These absolute configurations were confirmed by comparisons of the (R)-methoxy(trifluoromethyl)phenylacetic acid esters of insectderived and synthetic samples.Since the milestone identification of bombykol more than three decades ago, increasingly sophisticated analytical techniques combined with a great deal of research effort has led to the identification of hundreds of insect sex pheromones (1). While our knowledge of pheromonal communication in some groups, such as the Lepidoptera, is substantial, very little is known about chemical communication in many other groups of insects, including many of economic interest, such the longhorn beetles (Cerambycidae). Only recently has a femalereleased long-range sex pheromone for this group been identified (2) as an interesting and unusual semiochemical; this finding encouraged us to extend our study of longhorn beetle chemical communication.The cryptomeria twig borer Anaglyptus subfasciatus PIC is one of the most harmful insect pests of the Japanese cedar Cryptomeria japonica and the Japanese cypress Chamaecyparis obtusa, the most abundant tree species of forest plantations in Japan. Larvae of the beetle bore from dead twigs into the trunk and feed on sapwood, inducing discoloration of the heartwood and decreasing its commercial value. Since forest plantations are usually located near riverheads, spraying insecticides for the control of beetles must be avoided to prevent contamination of groundwater; alternative methods of control are, therefore, badly needed.It has been shown that A. subfasciatus females are attracted to males in a wind tunnel and that a male-specific cuticular structure in the pronotum seems to be involved in pheromone secretion (3). We have confirmed that reproductive behavior in A. subfasciatus utilizes male-released sex pheromones, which are now fully characterized as 3-(R)-hydroxy-2-hexanone and 3-(R)-hydroxy-2-octanone. MATERIALS AND METHODS