Visualization of the local ionic wind profile in a DC corona discharge field by laser-induced phosphorescence emission

Experimental visualization for ionic wind motion originated from DC corona discharges in a needle-plate electrode system has been investigated. A vapor-phase biacetyl tracer with laser-induced phosphorescence emission is used for optically characterizing the ionic wind profile. The ionic wind blows the excited biacetyl molecules away in continuing the visible phosphorescence emission for a long radiative lifetime. The captured image with elapsing time from the excitation presents the shifting location of radiative tracer along the ionic wind direction. The experimental results show the ionic wind profile enhanced in the electric field direction corresponding to the corona discharge progress. Especially, the ionic wind near an initiating point of corona discharges is focused as an advantage of this optical technique. The ionic wind velocity along the electrode axis can be obtained at the location close enough to the corona discharge initiation point, and the velocity at 0.5 mm from the discharge point is figured out as 9.3 to 19.2 m/s under the condition of the EHD Reynolds number of 0.95×10³ to 2.1×10³.     

Characterization of boron carbon nitride film modified by excimer laser annealing

Boron carbon nitride (BCN) shows promise as a field emitter material because of its mechanical hardness, chemical inertness, and low electron affinity. This study investigated the modification of a BCN film with an amorphous area using KrF excimer laser (wavelength: 248 nm, photon energy: 5.0 eV) annealing without substrate heating. This achieved significant variation in characteristics, such as an increase in bandgap energy and decrease in electron affinity. Laser annealing reduced electron affinity from 0.7 to 0.3 eV. The results indicate that the modification of the BCN film by KrF excimer laser annealing achieves characteristics similar to hexagonal BN (h-BN) film without losing the desirable properties of the BCN film, such as physical stability.     

An Acceleration Algorithm for Image Reconstruction Based on Continuous-Discrete Mapping Model

In image reconstruction for X-ray computed tomography, images reconstructed by filtered backprojection (FBP) include systematic errors because the FBP method does not take into account some of the properties of the actual imaging system such as the divergence of X-ray beam. One solution to this problem is to use algebraic reconstruction methods, such as generalized analytic reconstruction from discrete samples and natural pixel decomposition. However, in the process of reconstruction using these methods, it is necessary to solve the linear algebraic equations which have a large coefficient matrix. In this paper, we propose a method to accelerate the iteration solving these equations by preconditioning the coefficient matrix using a polynomial function. The results of the computer simulations show the effectiveness of the proposed method.     

Beat structure in spectrally resolved four-wave mixing under crosslinear polarization in GaAs quantum wells

The polarization dependence of beat structure in spectrally resolved four-wave mixing was investigated on 50 Å GaAs multiple quantum wells. Under crosslinear polarization we observed a beating structure at higher energy region of the main spectral peak due to biexciton–exciton transition. The beat has a period of 0.95 ps and is constructive at delay time T=0 ps, which suggests the corresponding double Feynman diagrams to be of the same type. By shortening the central wavelength of the sub-ps laser, we observed the distinctive peak corresponding to the beat period. Even in GaAs system, which is generally believed to have a small biexcitonic effect, there are two effective 2-exciton states with well-defined energies which are required to describe the third-order optical nonlinearly.     

n-Octyl α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside derivatives from the glandular trichome exudate of Geranium carolinianum

Chemical investigation of the glandular trichome exudate from Geranium carolinianum L. (Geraniaceae) led to the characterization of unique disaccharide derivatives, n-octyl 4-O-isobutyryl-α-L-rhamnopyranosyl-(1→2)-6-O-isobutyryl-β-D-glucopyranoside (1), n-octyl 4-O-isobutyryl-α-L-rhamnopyranosyl-(1→2)-6-O-(2-methylbutyryl)-β-D-glucopyranoside (2) and n-octyl 4-O-(2-methylbutyryl)-α-L-rhamnopyranosyl-(1→2)-6-O-isobutyryl-β-D-glucopyranoside (3), named caroliniasides A-C, respectively. These structures were determined by spectral means. n-Alkyl glycoside derivatives have been isolated from the glandular trichome exudates for the first time. This rare type of secondary metabolites could be applicable to chemotaxonomic perspective because they are found in glandular trichome exudates of plants belonging to the genus Geranium, according to our studies.     

Grafting of polyesters onto carbon black. VI. Copolymerization of alkylene carbonate with cyclic acid anhydride initiated by alkali metal carboxylate groups on carbon black surface

The ring-opening copolymerization of alkylene carbonate with cyclic acid anhydride was found to be initiated by carbon black containing potassium carboxylate (COOK) groups to give an alternating polymer, i.e., polyester. The polyester was propagated from COOK groups and effectively grafted from carbon black surface: e.g., the grafting ratio of polyester from ethylene carbonate (EC) and phthalic anhydride (PAn) went up to over 100%. On the other hand, the initiating activity of alkali metal carboxylate groups increased, depending on the alkali metal countercation, in the following order: COOLi < COONa < COOK < COORb < COOCs. This order was in agreement with that of increasing electropositivity of the counteraction. The activation energy of the copolymerization of EC with PAn was determined to be 26.3 kcal/mol. The rate of the copolymerization was accelerated in an aprotic solvent such as N-methyl-2-pyrrolidone. Furthermore, the effect of solvent and polymerization temperature on the grafting ratio of polyester was investigated.     

Flavonol glycosides in leaves of two Diospyros species

Fourteen flavonol glycosides including two new compounds were isolated from the leaves of two Diospyros plants (D. cathayensis and D. rhombifolia). The structures of isolated compounds were determined by spectroscopic analysis. The scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical of the isolated compounds was also investigated.     

Stepwise gradient of buffer concentration for capillary electrochromatography of peptides on sulfonated naphthalimido-modified silyl silica gel

The advantage of using a stepwise gradient of buffer concentration in CEC was demonstrated with the mixed-mode stationary phase, 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP). Before the application of a stepwise gradient, the effect of buffer concentration on the separations of six peptides and tryptic digests was investigated. Bubble formation caused by Joule heating at currents up to 95 microA was successfully suppressed by using SNAIP column even without pressurization, which contributed to a stepwise gradient of buffer concentration. Utilizing the stepwise gradient improved and shortened the separation of six peptides as compared to the separation under an isocratic elution.     

Opto-Electronic Block-Cipher Based on Iteration of the 2-D Toggle Cellular Automata: Algorithm

Parallel architectures and algorithms may offer a solution to the system bottleneck arising from the need to encrypt a very large amount of data without compromising security. In this respect the use of cellular automata with their parallel, simple, regular and modular structure is very promising. We extend the blockcipher algorithm, based on the iterations of so called “toggle” cellular automata rules to two dimensions.The advantages are higher complexity of the crypt-analytical attacks and substantial increase in the speed of the algorithm. Due to its massive parallelism and interconnectivity, the algorithm is very suitable for opto-electronic implementation.