Preparation and pharmacological evaluation of 4-(1,4-benzoquinon-2-yl)-4-phenylbutanamides as potential cerebral protective agents.

A new series of 4-(1,4-benzoquinon-2-yl)-4-phenylbutanamides (2) were synthesized for evaluation of their pharmacological activities. All these compounds synthesized showed significant antilipidperoxidation (ALP) activities with brain homogenate in rats and some of them possessed a protective effect against hypobaric hypoxia in mice. Especially, a thiomorpholine derivative (2l, SUN-4757) showed a wide efficacy spectrum to a variety of experimental screening assays designed for cerebral protective agents, and it had a high LD50 value.     

Anomalous diffusion of fatty acid vesicles driven by adhesion gradients

The motion of fatty acid vesicles driven by adhesion gradients of a liquid substrate (Langmuir monolayer) has been investigated. Trajectories of the vesicle motion reveal not only heterogeneity among vesicles in different regions of the monolayer but also heterogeneity within single-vesicle trajectories. Trajectories often exhibit complex behaviors such as circular and oscillating ones. Some vesicles exhibit intermittent dynamics that results in jump diffusion trajectories. In many vesicles their mean square displacements and effective diffusion coefficients exhibit a wide range of behaviors: (i) simple Brownian, (ii) subdiffusive, (iii) superdiffusive, and (iv) their combined motions. Even in the resting regime that the vesicle does not move substantially it exhibits active fluctuations due to spatio-temporal variations of the adhesion gradients of the monolayer. The results are compared with those in motor protein-driven transport of micrometer-sized particles bound to the cytoskeletal network and polymerization motor transport in the cell previously reported.     

Division and fusion, extension, adhesion, and retraction of vesicles created through Langmuir monolayer collapse: cell-like behavior

The motion of vesicles created through Langmuir monolayer collapse has been investigated. The vesicles grow only in a narrow molecular area range, and they exhibit remarkable, various biological cell-like behaviors such as division (cell division in cell biology, cytokinesis) and self-propulsion (motility). The vesicle division includes some dynamic modes: (i) an expulsion of a single satellite vesicle from an initial vesicle, (ii) a hierarchical and a sequential expulsion of a satellite vesicle, and (iii) a successive expulsion of two satellite vesicles from an initial vesicle. Two neighboring vesicles often show alternate fusion and division between them. Strong shape fluctuations dominate through vesicle division. The vesicles created exhibit distinct motions depending on the molecular area. At a large molecular area where most initial vesicles are created, they show a continuous, random motion on a few tens of micrometers length scale with a strong shape fluctuation and a constant velocity fluctuation profile. At a small molecular area they cease to move and shape fluctuations also become suppressed. At an intermediate molecular area there coexist vesicles with different dynamic modes: some vesicles show random motion similar to that at a large molecular area, but in a less fluctuating manner, while others exhibit a directional motion with an intermittent velocity jump. The directional motion is characterized by three distinct steps, i.e., extension, adhesion, and retraction. The characteristic motion is discussed from the viewpoint of haptotaxis, or the motion driven by adhesion gradients on the monolayer created by the local transfer of charged surfactant molecules between the vesicle and the monolayer, which the vesicle adheres to.     

Numerical simulation of convective heat transfer to a radial free surface jet impinging on a hot solid

The convective heat transfer between a circular free surface impinging jet and a solid surface has been studied numerically. The thin liquid film formed on the surface has been assumed to be in non-turbulent free surface flow. The effects of surface tension, viscosity, gravity and heat transfer between the film flow and the solid surface have been taken into account. The flow structure on a non-heated surface has been investigated first. Next, the steady-state flow structure in the liquid film as well as the heat transfer has been examined. The predicted results have been compared with experimental data for the purpose of validating the analysis. The hydrodynamics of the liquid film and the heat transfer processes have been investigated numerically to understand the physics of the phenomena. Received on 5 October 1998     

A simple integrated ratiometric wavelength monitor based on a directional coupler

A simple integrated ratiometric wavelength-monitoring device based on a single directional coupler (DC) is proposed and designed. To meet the desired spectral response, a computationally fast method is proposed to optimize the separation distance between two waveguides and the interaction length of the DC based on the local supermodes solution. The wavelength discrimination of the designed structure is demonstrated numerically.     

A molecular dynamics study of the lateral free energy profile of a pair of cholesterol molecules as a function of their distance in phospholipid bilayers

Free energy profile of a pair of cholesterol molecules in a leaflet of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) bilayers in the liquid-crystalline phase has been calculated as a function of their lateral distance using a combination of NPT-constant atomistic molecular dynamics calculations (P = 1 atm and T = 310.15 K) and the thermodynamic integration method. The calculated free energy clearly shows that the two cholesterol molecules form a dimer separated by a distance of 1.0-1.5 nm in POPC bilayers. Well depth of the free energy profile is about 3.5 kJ/mol, which is comparable to the thermal energy k(B)T at 310.15 K. This indicates that the aggregation of cholesterol molecules in the bilayers depends on the temperature as well as the concentration of the system. The free energy function obtained here may be used as a reference when coarse grained potential model is investigated for this two-component system. Local structure of POPC molecules around two cholesterol molecules has also been investigated.     

Finite element analysis of edge lamination during hot rolling process of aluminium alloy

Summary The rigid-plastic finite element method is applied to the analysis of the three-dimensional deformation behaviour, in particular the forming of edge lamination during the multi-pass hot roughing process of aluminium. the calculation is carried out for various rolling conditions and reduction schedules, and their influence on the edge lamination is examined. The results suggest that the crop loss due to the edge lamination can be reduced by increasing the roll diameter, the reduction per pass and the initial width of the slab.     

Efficient use of the surface plasmon polariton resonance in light scattering from adsorbates

Efficient collection of the scattered light from adsorbates on silver in the attenuated total reflection configuration is demonstrated with a so-called Weierstrass prism. The Raman signal from carbon contamination on silver films is enhanced by two orders of magnitude with respect to the simple external backscattering configuration.     

Infrared absorption enhancement of monolayer species on thin evaporated Ag films by use of a Kretschmann configuration: Evidence for two types of enhanced surface electric fields

Infrared absorption enhancement of m- and p-nitrobenzoic acid deposited on thin-evaporated silver films has been investigated using the Kretschmann's ATR coupling method. The absorption spectra provide direct evidence that enhancement is prominent only for vibrations of the first monolayer adsorbed on the Ag surface. It is shown that all of the vibrational modes observed obey the normal dipole selection rule. Moreover, it was found that there exist two types of absorption enhancement; the first is enhanced (300) by both p- and s-polarized radiation, and the second is enhanced (60) by p-polarized radiation alone. The Ag film thickness optimum is about 50 Å in the former case and about 200 Å in the latter. The enhancement insensitive to the polarization state of radiation can well be explained by the excitation of the transverse collective electron resonance of the Ag islands, whereas that obtained by p-polarized radiation may be due to the excitation of delocalized surface plasmons modified by surface roughness. The image-dipole effect may also be significant in the mechanisms.     

Preparation and some reactions of 3,5:8,10-di-1,3-benzo[8](3,4)-1,2,5-thiadiazolocyclophane

Titled 1,2,5-thiadiazolometacyclophane 1 was prepared via thia[2.3]cyclophane 5 which was obtained by the reaction of di(bromomethyl) 2 with sodium sulfide under phase-transfer-catalyzed conditions. Cyclophane 1 gave the corresponding pyrene derivatives by the oxidative transannular reaction in the reaction with brominating reagent. Reduction of 1 with lithium aluminum hydride followed by acetylation with acetic anhydride gave a 4:l-mixture of cis- and trans-diamide 11 and 12 with a trace amount of cyclophane-ring-cleaved product 13 . On the other hand, 13 was obtained as a major product in the reduction with metal sodium and diisobutylaluminum hydride.