Highly sensitive chiral shift reagent bearing two zinc porphyrins

A new type of chiral receptor (R,R)- or (S,S)-1b with C(2) symmetry was synthesized. An induced-fit type of binding behavior of 1b for diamines was revealed by CD spectroscopy. NMR studies demonstrated that 1b can function as a highly sensitive chiral shift reagent for the determination of the enantiomeric purity of chiral diamines, aziridine, and isoxazoline at the microgram level. [structure: see text]     

Discrimination of the geometrical isomers of 2,3-, 2,5-, and 2,6-dimethylpiperazines based on 1 H?Nmr spectral data

¹ H-Nmr spectra of cis and trans isomers of 2,3-, 2,5-, and 2,6-dimethylpiperazines were taken at various temperatures. The spectra of geometrical isomers bearing the ae or ea dimethyl groups showed broadening at lower temperatures. It was clarified that the measurement of the spectra at lower temperatures is useful for the discrimination of the geometrical isomers of dimethylpiperazines.     

Electronic resistivity and deffect structure of β-LiAl as a function of temperature and composition

The electrical resistivity of β-Li_xAl_1?x has been measured from 10 K to 290 K in single crystal samples for four different concentrations, x=0.480, 0.486, 0.500 and 0.525. An anomaly at 100 K is observed for the three lowest Li concentrations. This anomaly is associated with an ordering of constitutional Li vacancies. Above 100 K the temperature dependent part of the resistivity is independent of the Li concentration. However, the residual resistivity increases very rapidly with increasing Li concentration, becoming ～ 75 μΩ-cm for x=0.525. These results suggest that the two defect model of β-LiAl may be incomplete.     

Measurement of flow phenomena using the ultrasonic velocity profile method in a simulated Czochralski crystal puller

An experimental investigation of flow phenomena in a simulated Czochralski (CZ) crystal puller was conducted using an ultrasound velocity profile (UVP) probe to measure fluid velocities. To isolate the various forces that influence the fluid motion, only the crystal was rotated and a water-glycerol mixture was used as the test fluid in this experiment. Measurements of the velocity components, V_z and V_r, under the initial transient from zero rotation to a set rotation rate as well as under steady-state conditions were made. The corresponding Reynolds number based on the crystal radius and rotation varied from Re_Ω,_x ≈ 660–5000 (Ω_x ≈ 110–2000 rpm). The measured velocity profiles, V_z and V_r, were processed using a simple color image scheme based on the magnitude and direction of flow with respect to the probe. These profiles were studied to postulate flow patterns in the simulated CZ device. The measurements revealed three major regions of flow: (1) one beneath the crystal, (2) one near the free surface and crucible wall and (3) one beneath the crystal and occupying the extent of the crucible. In the initial transient, spatially symmetric outward flow beneath the crystal developed until the recirculating flow from below disturbed this pattern. At this point the apparent shear between the flow beneath the crystal and that circulating upwards from the bottom of the crucible induced flow instabilities and a non-axisymmetric flow pattern. The non-axisymmety was verified by the color-coded velocity profiles and a power spectrum analysis. The analysis revealed the critical Reynolds number for the onset of the primary instability to be Re_Ωcrit ≈ 669. The linear variation in the power of the primary peak with the Reynolds number indicates that the onset of the axisymmetry-breaking instability is due to Hopf bifurcation.     

An action function for a higher step Grushin operator

The purpose of this paper is to discuss how we can construct the heat kernel for (sub)-Laplacian in an explicit (integral) form in terms of a certain class of special functions. Of course, such cases will be highly limited. Here we only treat a typical operator, called Grushin operator. So, first we explain two methods to construct the heat kernel of a “step 2” Grushin operator. One is the eigenfunction expansion which leads to an integral form for the heat kernel, then we treat the formula by a method called, complex Hamilton–Jacobi method invented by Beals–Gaveau–Greiner. One of the main result in this paper is to construct an action function for a higher order oscillator. Until now, no explicit expression of the heat kernel for higher order cases have been given in an explicit form and we show a phenomenon that our action function will play a role toward the construction of the heat kernel of higher step Grushin operators.     

Color Conversion Method for Multiprimary Display Using Matrix Switching

The range of reproducible color, i.e., color gamut, of conventional three-primary display devices is sometimes insufficient for reproducing the natural color of an object through color imaging systems. A multiprimary display is being developed for the purpose of reproducing an expanded color gamut using more than three primary colors. In this paper, a color conversion method is proposed to reproduce the natural color by additive mixture of multiprimary colors. The multiprimary color signal in this conversion method is calculated from the three-dimensional color coordinates CIE-XYZ, considering the dynamic range of each primary color. Divided into some linear elements from the polyhedral color solid of the multiprimary display, the conversion considering the constraint of the dynamic range can be performed by simple calculation without iterative calculation or a huge three-dimensional look up table. A fast computation method with a two-dimensional look-up-table is also presented. Using the proposed method, the result of the color reproduction is experimentally demonstrated by a six-primary projection display.     

Rhodium-Catalyzed Acrylate Synthesis from Carbon Dioxide and Ethylene by using a Guanidine-Based Pincer Ligand: Perturbing Occupied d-Orbitals by pπ-dπ Repulsion Makes a Difference

Rhodium-catalyzed acrylate synthesis from CO₂ and ethylene was accomplished by using a guanidine-based NCN pincer ligand. The repulsion between pπ-electron of guanidine sidearms and occupied dπ orbital of rhodium center raised the level of d-electrons close to those of formerly known d⁸-ruthenium catalyst, thereby promoting the metallalactone formation from carbon dioxide and ethylene. This work fills the absence of group-9 metal based catalyst for the acrylate synthesis and provides a designing approach for pincer-ligated d⁸-metal catalysts to utilize pπ-dπ interaction for promoting desirable redox processes.     

Four-color hole burning spectra of phenol/ammonia 1:3 and 1:4 clusters

The hole burning spectra of phenol/ammonia (1:3 and 1:4) clusters were measured by a newly developed four-color (UV-near-IR-UV-UV) hole burning spectroscopy, which is a kind of population labeling spectroscopy. From the hole burning spectra, it was found that single species is observed in an n = 3 cluster, while three isomers are observed simultaneously for n = 4. A possibility was suggested that the reaction efficiency of the hydrogen transfer from the electronically excited phenol/ammonia clusters, which was measured by a comparison with the action spectra of the corresponding cluster, depends on the initial vibronic levels.