Efficient conversion of tomatidine into neuritogenic pregnane derivative

Moderate acetylation of tomatidine with anhydrous acetic acid and pyridine for 20 h at r.t., followed by pseudomerization in ice-water, gave a delta(20(22))-pseudo compound, which was then subjected to ozonolysis to provide a pregnane derivative in a total 54% yield showing neuritogenic and NGF-enhancing activities.     

A pregnane glycoside from overripe tomato

A new pregnane glycoside, 3-O-beta-lycotetraosyl 5alpha-pregna-3beta,26beta-diol-20-one was isolated from overripe tomato, the fruit of Lycopersicon esculentum MILL.     

Micro air vehicle-motivated computational biomechanics in bio-flights: aerodynamics, flight dynamics and maneuvering stability

Aiming at developing an effective tool to unveil key mechanisms in bio-flight as well as to provide guidelines for bio-inspired micro air vehicles（MAVs） design,we propose a comprehensive computational framework,which integrates aerodynamics,flight dynamics,vehicle stability and maneuverability.This framework consists of（1） a Navier-Stokes unsteady aerodynamic model;（2） a linear finite element model for structural dynamics;（3） a fluidstructure interaction（FSI） model for coupled flexible wing aerodynamics aeroelasticity;（4） a free-flying rigid body dynamic（RBD） model utilizing the Newtonian-Euler equations of 6DoF motion;and（5） flight simulator accounting for realistic wing-body morphology,flapping-wing and body kinematics,and a coupling model accounting for the nonlinear 6DoF flight dynamics and stability of insect flapping flight.Results are presented based on hovering aerodynamics with rigid and flexible wings of hawkmoth and fruitfly.The present approach can support systematic analyses of bio- and bio-inspired flight.     

Hollow tube fabrication in photoresist film using continuous wave laser

This paper is a study of three-dimensional (3D) micron/submicron fabrication with a continuous wave (CW) laser. The fabrication forms vertical and horizontal hollow tubes in a photoresist film with nonlinear optical properties. We controlled beam intensities and dose amounts to manipulate a reaction time constant of the photoresist; we fabricated the 3D hollows in high contrast.     

Synthesis and CuAAC Reactions of Azidoalkylethoxysilanes: Grafting CuAAC Products onto Silica Surface

One-pot synthetic protocols of novel azido functionalized silane coupling agents from corresponding terminal mesylated or tosylated 1-olefins were developed. Azido groups were successfully converted to the corresponding 1,2,3-triazol ring by the copper-catalyzed azido alkyne coupling (CuAAC) reaction without alkoxysilane decomposition. The CuAAC product was readily grafted onto the silica surface in good yield.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

A new steroidal glycoside and a new phenyl glycoside from a ripe cherry tomato

A new steroidal glycoside and a new phenyl glycoside have been isolated from a ripe cherry tomato [Lycopersicon esculentum var. cerasiforme (DUNAL) ALEF., Solanaceae] along with two known steroidal alkaloid glycosides, esculeoisides A and B, and five aromatic compounds, zizibeoside I, benzyl alcohol beta-gentiobioside, rutin, methyl caffeate, and phenylalanine. Their chemical structures were determined on the basis of spectroscopic data as well as chemical evidence.     

Mechanism for conversion of spirosolane derivative into pregnane

Previously, we reported an interesting reaction by which esculeogenin A [(5alpha,22S,23S,25S)-3beta,23,27-trihydroxyspirosolane], a sapogenol of tomato-saponin, esculeoside A, was easily converted into a pregnane derivative, 5alpha-pregn-16-en-3beta-ol-20-one, merely by refluxing with pyridine and water. Its chemical mechanism including air oxidation is here described.     

Electrical detection of single methylcytosines in a DNA oligomer

We report label-free electrical detections of chemically modified nucleobases in a DNA using a nucleotide-sized electrode gap. We found that methyl substitution contributes to increase the tunneling conductance of deoxycytidines, which was attributed to a shift of the highest occupied molecular orbital level closer to the electrode Fermi level by methylation. We also demonstrate statistical identifications of methylcytosines in an oligonucleotide by tunneling current. This result suggests a possible use of the transverse electron-transport method for a methylation level analysis.     

Dimerization of copper(II) decanoate in 1,4-dioxane-water mixed solvents

Complex formation of copper(II) with decanoic acid (HA) has been studied by potentiometric measurement in 1,4-dioxane-water mixtures at a constant ionic concentration of 0.1 mol dm^?3 (Na, H)ClO₄ and at 25°C. The experimental data can be interpreted with the formation of CuA⁺, CuA₂ and Cu₂A₄. The dimerization constant formulated as:

was found to be log K_dim = 3.75, 4.02 and 4.26 for 0.3, 0.4 and 0.5 mole fractions of dioxane, respectively. Absorbances at 373 and 670 nm are interpreted with the aid of the formation constants determined by potentiometry. Solvent effect on the dimerization of the monomeric copper(II) decanoate is discussed on the basis of selective solvation of CuA₂ and Cu₂A₄ with water molecules.