Liposomes possess drastic capabilities for topological transformation

Morphological and topological changes of biological membranes play essential roles in cellular activities. It has been thought that these transformations are made possible through interactions with proteins. However, direct observation of giant liposomes by optical dark-field microscopy reveals that the lipid bilayer itself possesses the ability to undergo topological transformation.     

Flow and heat transfer characteristics of drag reducing surfactant solution in a helically coiled pipe

The reduction characteristic of turbulent drag and heat transfer of drag reduction surfactant solution flowing in a helically coiled pipe were experimentally investigated. The drag reduction surfactant used in the present study was the amine oxide type nonionic surfactant of oleyldihydroxyethylamineoxide (ODEAO, C₂₂H₄₅NO₃=371). The zwitterion surfactant of cetyldimethylaminoaciticacidbetaine (CDMB, C₂₀H₄₁NO₂=327) was added by 10% to the ODEAO solution in order to avoid the chemical degradation of ODEAO by ionic impurities in a test tape water. The experiments of flow drag and heat transfer reduction were carried out in the helically coiled pipe of coil to pipe diameter ratio of 37.5 and the helically coiled pipe length to pipe diameter of 1180.5 (pipe diameter of 14.4 mm) at various concentrations, temperatures and flow velocities of the ODEAO surfactant solution. The ODEAO solution showed a non-Newtonian behavior at high concentration of the ODEAO. From the experimental results, it was observed that the friction factor of the ODEAO surfactant solution flowing through the coiled pipe was decreased to a great extent in comparison with water as a Newtonian fluid in the turbulent flow region. Heat transfer measurements for water and the ODEAO solution were performed in both laminar and turbulent flow regions under the uniform heat flux boundary condition. The heat transfer coefficients for the ODEAO solution flow were the same as water flow in the laminar region. On the other hand, heat transfer reduction of the ODEAO solution flow was remarkedly reduced as compared with that of the water flow in the turbulent flow region.     

Efficient synthesis of useful heterocycles via transition metal-catalyzed cascade processes

This paper reports our recent results from synthesis of some useful heterocycles, for example oxazolidinones, indoles, and quinoxalinones, by transition metal-catalyzed cascade processes. The scope and limitations of these procedures and the reaction mechanism for formation of the heterocycles are also discussed.     

Ultraweak emission imagery of mitosing soybeans

In the single-photon counting mode, we have obtained images of germinating soybeans and other plant tissues using only the ultraweak light emitted by the specimen. The emission described here is to be distinguished from bioluminescence and is not induced by previous exposure to light, chemical agents or other means, but is a naturally occurring emission associated with normal biochemical processes. The images of germinating soybeans show that emission is strongest in areas of active mitosis, demonstrating that the technique of singlephoton counting imaging can provide useful morphological information.     

Heat capacity of vanadium-oxygen alloy

Heat capacities of vanadium-oxygen alloys with various compositions, VO_0.0834, VO_0.1127, VO_0.1245, and VO_0.1296, were measured from 320 to 920K by adiabatic scanning calorimetry. A heat capacity anomaly due to order-disorder rearrangement of oxygen atoms was observed for all the compositions. The transition temperatures from α′ to β phase were found to be 780, 791, 786, and 768K for VO_0.0839, VO_0.1127, VO_0.1245, and VO_0.1296, respectively. The transition temperatures from β′ to β were also observed to be 665 and 660K for VO_0.1245 and VO_0.1296, respectively, but they shifted to lower temperatures in repeated measurements. The excess heat capacity due to order-disorder transition was obtained by assuming that the heat capacity can be expressed as the sum of a harmonic term of lattice vibration, a dilational term, an electronic term, and an anharmonic term of lattice vibration. The entropy changes due to the transition for VO_0.0834, VO_0.1127, VO_0.1245, VO_0.1296 were determined from the excess heat capacities to be 1.90, 2.88, 2.82, and 2.88 J K^?1 mole^?1, respectively, values which were explained by calculating the entropy changes due to the order-disorder rearrangement of oxygen atoms in the superstructures of VO_x alloys. From the O/V dependence of the transition temperature and entropy change, the most stable composition of the α′ phase was thought to be V₄₈O₅.     

Nonlinear dynamics of open marine population with space-limited recruitment: The case of mortality control

In this paper we develop a nonlinear extension for the open marine population model which has been proposed by Roughgarden et al. [Ecology 66 (1985) 54-67]. To avoid the negative population density, which is a drawback of the original model, we introduce a nonlinear mechanism that the mortality rate depends on the size of area occupied by the adult population. Then we give a rigorous mathematical framework to analyse the model equation, and we show sufficient conditions for stability and instability of the steady state. Our instability result suggests, as was proposed by Roughgarden et al., that there exists a sustained oscillation of the population density.     

Hilbert-Speiser number fields for a prime p inside the p-cyclotomic field

Let p be a prime number. We say that a number field F satisfies the condition when for any cyclic extension N/F of degree p, the ring of p-integers of N has a normal integral basis over . It is known that F=Q satisfies for any p. It is also known that when p?19, any subfield F of Q(ζp) satisfies . In this paper, we prove that when p?23, an imaginary subfield F of Q(ζp) satisfies if and only if and p=43, 67 or 163 (under GRH). For a real subfield F of Q(ζp) with F≠Q, we give a corresponding but weaker assertion to the effect that it quite rarely satisfies .     

Mixing schemes in a urea-H2O system: a differential approach in solution thermodynamics

The excess partial molar enthalpies of urea (UR), H U R (E ), were experimentally determined in UR-H 2O at 25 degrees C. The H U R (E ) data were determined accurately and in small increments in the mole fraction of UR, x U R , up to x U R approximately 0.22. Hence it was possible to evaluate one more x U R -derivative graphically without resorting to any fitting function, and the model-free UR-UR enthalpic interaction, H U R- U R (E ), was calculated. Using previous data for the excess chemical potential, mu U R (E ), the entropy analogue, S U R- U R (E ), was also calculated. The x U R -dependences of both H U R- U R (E ) and S U R- U R (E ) indicate that there is a boundary at x U R approximately 0.09 at which the aggregation nature of urea changes. From the results of our earlier works, we suggest that a few UR molecules aggregate at x U R approximately 0.09, while the integrity of H 2O is retained at least up to x U R approximately 0.20. Together with the findings from our previous studies, we suggest that in the concentration range x U R < 0.22, UR or its aggregate form hydrogen bonds to the H 2O network, reducing the degree of fluctuation characteristic to liquid H 2O. However, up to at least x U R = 0.20 the hydrogen bond network remains intact. Above x U R approximately 0.22, the integrity of H 2O is likely be lost. Thus, in discussing the effect of urea on H 2O and in relating it to the structure and function of biopolymers in aqueous solutions, the concentration region in question must be specified.