Highly enantioselective catalytic carbon dioxide incorporation reaction: nickel-catalyzed asymmetric carboxylative cyclization of bis-1,3-dienes

A method for nickel-catalyzed asymmetric carbon dioxide (CO2) incorporation via carbon-carbon bond formation was developed. In the presence of a catalytic amount of Ni(acac)2 and MeO-MOP, various bis-1,3-dienes reacted with CO2 (1 atm) and a diorganozinc reagent (Me2Zn or Ph2Zn) to afford cyclic carboxylic acids in good yields (71-100%) and with high enantioselectivities (90-96% ee).     

Broad-spectrum frequency comb generation and carrier-envelope offset frequency measurement by second-harmonic generation of a mode-locked fiber laser

A frequency comb spanning more than one octave has been achieved by injecting the second-harmonic generation (780 nm) of a mode-locked fiber laser (1.56 microm) into a photonic crystal fiber. We propose and realize a novel interferometric scheme for observing the carrier-envelope offset frequency of the frequency comb. Frequency noise has been observed on the measured carrier-envelope offset frequency, which has been confirmed to be generated in the photonic crystal fiber by comparing the measured beat frequencies between cw lasers and frequency combs before and after the photonic crystal fiber. The mode-locked fiber laser is considered to be an important candidate for the light source used in realizing a compact optical frequency measurement system including applications in the telecommunication bands.     

Novel fluorescent isoquinoline pigments, panaefluorolines A-C from the cultured mycobiont of a lichen, Amygdalaria panaeola

Novel fluorescent substances, named panaefluorolines A-C (1-3), were isolated from the cultured mycobiont of a lichen, Amygdalaria panaeola. These structures were elucidated on the basis of spectroscopic data, especially 2D NMR.     

A Method for Measuring the Three-Dimensional Refractive-Index Distribution of Single Cells Using Proximal Two-Beam Optical Tweezers and a Phase-Shifting Mach—Zehnder Interferometer

This paper describes a method for measuring the three-dimensional (3D) refractive-index distribution in a single cell. The method can be used to observe the distribution of cell components without fluorescence staining. The two-dimensional optical path length distributions from multiple directions are obtained by non-contact rotation of the cell. These optical path lengths are converted into the line integrals of the refractive index, and the 3D refractive-index distribution is reconstructed by means of computed tomography. The refractive-index distribution in a breast cancer cell can be measured using a phase-shifting Mach—Zehnder interferometer in conjunction with proximal two-beam optical tweezers.     

Time‐resolved x‐ray fluorescence for monitoring the intake of mineral nutrients in living plants

We have applied a time‐resolved means of measurement for studying living plants. The intake of mineral nutrients in a living plant such as stevia has been observed by this measuring instrument. A solution containing K, Ca, Mn, Fe, Cu, and Zn compounds was used as the mineral nutrient solution. The concentrations of the standard solutions were specifically chosen to obtain optimal intensities of the x‐ray peaks. The time dependence of the x‐ray fluorescence (XRF) intensity showed specific intake processes depending on the type of element. In addition, the experimental results suggest differences in the translocation of each element in the stevia stem. We conclude that time‐resolved XRF is a powerful technique for studying living plants. Copyright © 2007 John Wiley & Sons, Ltd.     

Extraction of Catecholamines by Calixarene Carboxylic Acid Derivatives

Extraction behaviors of catecholamines with a series of calixarene carboxylic acid derivatives were investigated. Relatively large calix[6]arene and calix[8]arene extract catecholamines into the organic solution, while smaller calix[4]arene and the monomer analog do not. The calix[6]arene, which has a cavity that fits a protonated amino group well, selectively extracts a primary amino compound dopamine over other catecholamines. Slope analysis and Job’s method confirmed formation of a 1:1 complex between the calix[6]arene and dopamine. On the other hand, the calix[8]arene extracts both dopamine and adrenaline, due to the large cavity for induced-fit recognition. Dopamine extracted with the calixarene is quantitatively stripped by contacting the organic solution with a fresh acidic solution.     

Ca at C82 isomers: computed temperature dependency of relative concentrations

Relative concentrations of nine isomers of Ca at C82 derived from the C82 isolated-pentagon-rule satisfying cages are computed in a wide temperature interval. The computations are based on the Gibbs energy constructed from partition functions supplied with molecular parameters from density functional theory calculations. Five structures show significant populations at higher temperatures: C2v > Cs > C2 > C3v > Cs. The computed relative stabilities agree well with available observations.     

Adsorption of microstructured particles at liquid-liquid interfaces

The solid particles are adsorbed at interfaces and form self-assembled structures when the particles have suitable wettability to both liquids. Here, we show theoretically how the microstructure on the particle surface affects their adsorption properties. The physical properties of the interface adsorbing a particle will be described by taking into account the surface roughness due to the microstructure. The microstructure on the surface changes drastically the wettability and the equilibrium position of the adsorbed particle. Therefore, the contact angle of the particle at the three-phase contact line shifts with the particle surface area, because the surface roughness enhances the interfacial properties of the particle surface. Moreover, the range of the interfacial tensions at which the particle is adsorbed becomes narrower with the increase of the surface roughness. The effect of the particle shape on the adsorption properties is also studied. In the case of disk-shaped particles, the energy changes discontinuously when the plane surface of the particle contacts the liquid-liquid interface. The adsorbing position does not change with the surface roughness. The orientation of a parallelepiped particle at the liquid-liquid interface is governed by the aspect ratio and the surface area of the particle. On the other hand, the particle which is partially covered with the microstructured surface is adsorbed firmly at the interface in an oriented state. We should consider not only the interfacial tensions but also the surface structure and the particle shape to control the adsorption behavior of the particle.     

Asymmetric sequential Michael reaction: Synthesis of optically active bicyclo[2.2.2]octane derivatives

The sequential Michael reaction of (S)-4,5-di-O-isopropylidenepent-2- enoate and with lithium enolate afforded diastereo- and enantioselectively bicyclo[2.2.2]octane and (or ), respectively. The adducts were efficiently converted into both enantiomeric keto aldehydes (−)- and (+)- .     

Concepts of probabilistic sets

In the field of pattern recognition or decision making theory, the important subjects are as follows: (1) ambiguity of property of objects, (2) variety of character of objects, (3) subjectivity of observers, (4) evolution of knowledge of observers (i.e. learning). Considering these points, the concept of probabilistic set is proposed. It is based on both probability theory and fuzzy concepts. A probabilistic set on a total space is defined by a point wise measurable function from a parameter space (which is a probability space) to a characteristic space (which is a measurable space). It is shown that the family of all probabilistic sets constitutes a complete pseudo-Boolean algebra. Moment analysis is possible by using a probability measure of the parameter space. Other useful concepts are also mentioned such as probabilistic mappings and expected cardinal numbers.