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Selected Abstracts

Growth and characterization of pure and doped nonlinear optical l-arginine acetate single crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2007
M. Gulam Mohamed
Abstract Single crystals of organic nonlinear optical material of pure, Cu2+ and Mg2+ doped L-arginine acetate (LAA) were successfully grown by slow evaporation method at room temperature. The UV-Vis-NIR spectra of pure and doped LAA indicate that these crystals possess a wide optical transmission window from 240-1600 nm. Non-linear optical studies reveal that the SHG efficiency of LAA is nearly three times that of KDP. The dielectric response of the samples was studied in the frequency region 100 Hz to 2 MHz and the influence of Cu2+ and Mg2+ substitution on the dielectric behaviour had been investigated. Photoconductivity study proves that both pure and Cu2+ and Mg2+ doped LAA crystal exhibit positive photoconductivity. It is evident from the Vickers hardness study that the hardness of the crystal decreases with increasing load both for pure and doped samples. ESR studies confirmed the incorporation of Cu2+ into LAA and the value of g-factor was found to be 2.1654. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Hg3In2Te6 -based photodiodes for fiber optic communication

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2009
L. A. Kosyachenko
Abstract Schottky barrier photodiodes obtained by vacuum evaporation of the semi-transparent film over the surface of single crystalline Hg3In2Te6 substrates pre-treated by Ar ion bombardment. The responsivity maximum of the photodiodes is at the wavelength of 1.55 ,m, corresponding to the transmission window in silica glass fiber with the minimal optical losses. The dark current in the diodes is determined by generation-recombination processes in the space-charge region and quantitatively governed by the Sah,Noyce,Shockley theory. A comparison of the photoelectric parameters of Hg3In2Te6 and Ge photodiodes is reported. The speed of the photodiode response is in the range 10,8 s to 10,7 s. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The detection, correlation, and comparison of peptide precursor and product ions from data independent LC-MS with data dependant LC-MS/MS

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 6 2009
Scott J. Geromanos
Abstract The detection, correlation, and comparison of peptide and product ions from a data independent LC-MS acquisition strategy with data dependent LC-MS/MS is described. The data independent mode of acquisition differs from an LC-MS/MS data acquisition since no ion transmission window is applied with the first mass analyzer prior to collision induced disassociation. Alternating the energy applied to the collision cell, between low and elevated energy, on a scan-to-scan basis, provides accurate mass precursor and associated product ion spectra from every ion above the LOD of the mass spectrometer. The method therefore provides a near 100% duty cycle, with an inherent increase in signal intensity due to the fact that both precursor and product ion data are collected on all isotopes of every charge-state across the entire chromatographic peak width. The correlation of product to precursor ions, after deconvolution, is achieved by using reconstructed retention time apices and chromatographic peak shapes. Presented are the results from the comparison of a simple four protein mixture, in the presence and absence of an enzymatically digested protein extract from Escherichia coli. The samples were run in triplicate by both data dependant analysis (DDA) LC-MS/MS and data-independent, alternate scanning LC-MS. The detection and identification of precursor and product ions from the combined DDA search results of the four protein mixture were used for comparison to all other data. Each individual set of data-independent LC-MS data provides a more comprehensive set of detected ions than the combined peptide identifications from the DDA LC-MS/MS experiments. In the presence of the complex E. coli background, over 90% of the monoisotopic masses from the combined LC-MS/MS identifications were detected at the appropriate retention time. Moreover, the fragmentation pattern and number of associated elevated energy product ions in each replicate experiment was found to be very similar to the DDA identifications. In the case of the corresponding individual DDA LC-MS/MS experiment, 43% of the possible detectable peptides of interest were identified. The presented data illustrates that the time-aligned data from data-independent alternate scanning LC-MS experiments is highly comparable to the data obtained via DDA. The obtained information can therefore be effectively and correctly deconvolved to correlate product ions with parent precursor ions. The ability to generate precursor-product ion tables from this information and subsequently identify the correct parent precursor peptide will be illustrated in a companion manuscript. [source]

Building Nanocrystalline Planar Defects within Self-Assembled Photonic Crystals by Spin-Coating,

ADVANCED MATERIALS, Issue 9 2006
R. Pozas
A new type of 2D defect within artificial opals is presented. Sequential deposition of a colloidal crystal by convective self-assembly and a slab of oxide nanocrystals by spin-coating gives rise to heterostructures (as shown in the figure). The nanocrystalline layer behaves as an optical dopant, opening transmission windows within the forbidden frequency interval of the lattice, as can be seen in the superimposed transmittance spectra. [source]

The design and fabrication of optical fiber Bragg grating filter with dual-bandpass pair by phase sampling and phase shift techniques

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2009
Li Xia
Abstract Phase sampling and phase shift techniques are introduced in a uniform fiber Bragg grating structure to achieve a multi-bandpass filter with ultranarrow transmission bandwidth. A pair of dual-bandpass transmission windows are opened at 1542.32, 1542.36, and 1542.66, 1542.71 nm, respectively. The channel spacing between the pair can be designed by the phase sampling period, as well as the wavelength spacing in the dual-bandpass can be controlled through the phase shift length. This new kind of bandpass structure can be applied in the ultranarrow filtering in multichannel, multiwavelength distributed feedback Bragg lasing, photonic generation of microwave signal etc. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 790,791, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24140 [source]