Direct laser writing defects in holographic lithography-created photonic lattices

As a well-established laser fabrication approach, holographic lithography, or multibeam interference patterning, is known for its capability to create long-range ordered large-volume photonic crystals (PhCs) rapidly. Its broad use is, however, hampered by difficulty in inducing artificially designed defects for device functions. We use pinpoint femtosecond laser ablation to remove and two-photon photopolymerization to add desired defective features to obtain photonic acceptors and photonic donors, respectively, in an otherwise complete PhC matrix produced by holographic lithography. The combined use of the two direct laser writing technologies would immediately make holographic lithography a promising industrial tool for PhC manufacture.     

Polymer waveguide module for visible wavelength division multiplexing plastic optical fiber communication

We report a polymer waveguide module that provides bidirectional communication over a single plastic optical fiber (POF) with dual visible wavelength LEDs. The module is constructed using light-induced self-written waveguides, which enables a three-dimensional optical circuit for visible wavelength division multiplexing to be fabricated by an extremely simple process. We demonstrated 250 Mbits/s communication using a pair of these modules that each contained one green (lambda = 495 nm) and one red (lambda = 650 nm) LEDs by measuring the bit error rates. The results indicate that the system could transmit over more than 20 m of POF in full duplex mode.     

Oxidation process of Mg films by using high-concentration ozone for magnetic tunnel junctions

Ozone oxidization process of metal Mg film for the barrier formation in magnetic tunnel junctions (MTJs) is investigated. Ozone exposure method is expected to oxidize ultra-thin metal films more mildly than with the plasma oxidization method, since the energy level of atomic oxygen is ∼2 eV lower in the ozone method than in the plasma method. The main results were as follows: (1) In the case of ozone oxidation, the diffusion coefficient of oxygen in the insulator is much smaller than that in plasma oxidation. (2) Mg–O film thickness, which is formed by reaction immediately on the metal Mg surface, is thicker as compared with the Al case. (3) In the ozone oxidation method of metal films with the thickness of more than the film thickness formed by reaction, the oxidation is spontaneously stopped at the interface to the bottom Co–Fe. As a result, we succeeded in inducing a TMR ratio of 25% at room temperature in MTJs with Mg(1.3 nm)–O barrier with wider exposure range than in the plasma case.     

Scavengers for peroxynitrite: inhibition of tyrosine nitration and oxidation with tryptamine derivatives, alpha-lipoic acid and synthetic compounds

The inhibitory effects of various endogenous and synthetic compounds on the nitration and oxidation of L-tyrosine by peroxynitrite were examined. Nitrating and oxidizing activities were monitored by the formation of 3-nitrotyrosine and dityrosine with a HPLC-UV-fluorescence detector system, respectively. Glutathione, serotonin and synthetic sulfur- and selenium-containing compounds inhibited both the nitration and oxidation reaction of L-tyrosine effectively. However, 5-methoxytryptamine, melatonin and alpha-lipoic acid only inhibited the nitration reaction, and enhanced the formation of an oxidation product. This is important evidence that there are different intermediates in the nitrating and oxidizing reactions of L-tyrosine by peroxynitrite. It was suggested that 5-methoxytryptamine, melatonin and alpha-lipoic acid reacted only with the nitrating intermediate of peroxynitrite and inhibited nitration of L-tyrosine. Actually, the DNA strand breakage, which is believed to be a typical reaction of hydroxyl radical-like species, caused by peroxynitrite was not effectively inhibited by 5-methoxytryptamine. 5-Methoxytryptamine, melatonin and alpha-lipoic acid were viewed as useful reagents for investigating the mechanisms of damage by peroxynitrite in vitro.     

Determination of membrane Peptide orientation by 1H-detected 2H NMR spectroscopy

We demonstrate the application of the proton inverse detected deuteron (PRIDE) NMR technique to the measurement of the orientation of membrane-bound peptides with enhanced sensitivity. Gramicidin D, a transmembrane peptide, and ovispirin, a surface-bound peptide, were used as model systems. The peptides were 2H-labeled by 1H/2H exchange and oriented uniaxially on glass plates. The directly detected 2H spectra of both peptides showed only a strong D(2)O signal and no large quadrupolar splittings. In contrast, the PRIDE spectrum of gramicidin exhibited quadrupolar splittings as large as 281 kHz, consistent with its transmembrane orientation. Moreover, the large D(2)O signal in the directly detected 2H spectra was cleanly suppressed in the PRIDE spectrum. For ovispirin, the 1H indirectly detected 2H spectrum revealed a 104 kHz splitting and a zero-frequency peak. The former reflects the in-plane orientation of most of the helix axis, while the latter results from residues with a magic-angle orientation of the N-D bonds. These are consistent with previous 15N NMR results on ovispirin. The combination of PRIDE and exchange labeling provides an economical and sensitive method of studying membrane peptide orientations in lipid bilayers without the influence of D(2)O and with the ability to detect N-D bonds at the magic angle from the bilayer normal.     

Discrete 2-convex functions

Mathematical Programming - In this paper we reconsider a known technique for constructing strong MIP formulations for disjunctive constraints of the form $$x \in \bigcup _{i=1}^m P_i$$ , where the...     

Chloride concentration and temperature effects on the hydration of Th(IV) ion: a molecular dynamics simulation

Molecular dynamics simulations have been performed to investigate the structural and dynamical properties of the second hydration shell of Th⁴⁺ ion at various chloride concentrations and temperatures. When the concentration increases (ca. 5 M), the hydration of Th⁴⁺ ion involves the displacement of the water molecules by Cl⁻ ligand and slightly decreases the total coordination number. The residence time of water molecules in the second hydration shell decreases as a function of increasing solution temperature.     

Generalization of boson-fermion equivalence and Fay's addition theorem

Generalizations of Fay's addition theorem for Abel functions are obtained by using generalized boson-fermion equivalence of off-shell string amplitudes. A simple example of such generalizations is presented explicitly which relates derivatives of a Riemann -function to its determinant.     

Topological inverse problem for oscillating systems and its application

This note is just an introduction to a problem to find a topological type of potentials from given data and a problem to see which data or experiment is necessary to obtain the topological classification of practical use. Here we propose a method of hysteresis on the space of Fourier coefficients, which reduces to the theory of resonance curves in a very special case. The direction of the hysteresis curve is proved to characterize the (first) topological type of potential. In contrast with the usual direction, which is common to the transistor oscillator, the unusual direction is found in EEG experiments (on humans) called photic driving experiments on rhythm.     

High Resolution Structure of Bacteriorhodopsin Determined by Electron Crystallography

Abstract— Bacteriorhodopsin pumps protons from the cytoplasm to the outside of halobacteria, Halobacterium salinarium , by using absorbed light energy. The newly observed density map at 3 Å resolution clarified nearly the entire structure; the resolution in the direction perpendicular to the membrane surface is 3.2 Å. The new structure clearly indicates the proton transfer pathway in bacteriorhodopsin. In particular, the location of key aspartic acid and glutamic acid residues in the derived structural model suggested funneling structures with different designs for input and output of protons on the cytoplasmic and extracellular sides, respectively, of the protein. This paper describes the major differences between the model based on the new observation and the former model obtained through crystallographic refinement by Grigorieff et al . ( J. Mol. Biol 259; 393-421, 1996).