Designs of all-optical buffer and OR gate using SOA-MZI

In the paper a novel scheme for an all-optical buffer and OR logic gates based on Mach–Zehnder interferometer structure is discussed. The operations of the scheme with 10 Gb/s return to zero pseudorandom bit streams simulated correctly with extinction ratio 19.21 and 17.61 dB where Q-factor 25.94 and 11.22 for buffer and OR gate respectively. With the help of numerical analyses, it can be seen that the extinction ratio of the OR operation is degraded and the output pattern effect is decreased by 0.9 dB compared to optical buffer schemes under the same condition. Furthermore, the carrier recovery time of a semiconductor optical amplifier is no longer a crucial parameter to restrict the operation speed of this scheme. The scheme is also potentially capable of multi input OR operation at higher speed.     

Electrochemical properties and first-principle analysisof Na x [M y Mn1−y ]O2 (M = Fe,Ni) cathode

Journal of Solid State Electrochemistry - Sodium-ion batteries are the commercially and environmentally viable next-generation candidates for automobiles. Structural and electrochemical aspects are...     

Application of Hydrazino Dinitrophenyl-Amino Acids as Chiral Derivatizing Reagents for Liquid Chromatographic Enantioresolution of Carbonyl Compounds

A new series of chiral derivatizing reagents (CDRs) consisting of five hydrazino dinitrophenyl (HDNP)-amino acids (CDR 1?C5) was prepared by a two-step synthesis procedure starting from 1,5-difluoro-2,4-dinitrobenzene (DFDNB). In the first step, five fluoro-dinitrophenyl (FDNP)-reagents, namely FDNP-l-Leu, FDNP-l-Val, FDNP-l-Phe, FDNP-l-Ala and FDNP-d-Phg were synthesized by substituting one of the fluorine atoms in DFDNB moiety with amino acids l-Leu, l-Val, l-Phe, l-Ala and d-Phg, respectively. In the following step, the remaining fluorine atom of the FDNP reagents was substituted with hydrazine hydrate to obtain five HDNP reagents (i.e. CDR 1?C5; HDNP-l-Leu, HDNP-l-Val, HDNP-l-Phe, HDNP-l-Ala and HDNP-d-Phg). These five CDRs were used for synthesis of diastereomers of six racemic carbonyl compounds which were resolved by high-performance liquid chromatography using C18 column and gradient eluting mixture of acetonitrile or methanol with triethylammonium phosphate buffer with UV detection at 348 nm. Microwave irradiation was used for synthesis of both the CDRs and the diastereomers. The newly synthesized CDRs were observed to be superior in comparison to their counterparts having amino acid amides as chiral auxiliaries in terms of cost effectiveness and providing better resolution of diastereomers. The method was validated for limit of detection, linearity, accuracy and precision.     

Synthesis,characterization and dyeing performance of new bisazo–bisazomethine disperse dyes

New bisazo–bisazomethine disperse dyes were prepared by the coupling of diazotized solutions of various aromatic amines with 2,2′-{methylenebis[4,1-phenylenenitrilomethylylidene]}diphenol (Schiff base). Schiff base (SB) was prepared by the condensation of 2-hydroxybenzaldehyde with 4,4′-diaminodiphenylmethane (DDM). The resultant dyes were characterized by elemental analysis, IR and ¹H NMR spectral studies. The UV–visible absorption spectral data were investigated in dimethylformamide (DMF) and are discussed in terms of structure property relationship. The dyes when applied on polyester fabric, gave golden yellow to reddish brown shades having fairly good to good light fastness, very good to excellent washing, perspiration and sublimation fastness and good to very good rubbing fastness properties.     

Effect of In-segregation on subbands in GaInNAs/GaAs quantum wells emission around 1.3 and 1.55 micron

The effect of In-segregation on optical properties in 7.5-nm GaInNAs/GaAs single quantum well (QW) is studied theoretically. The nominal (In, N) contents in the QW are chosen to be (0.35, 0.015) and (0.39, 0.03) for the emission wavelengths around 1.3 and 1.55 μm, respectively. Muraki’s model is used to model the composition profiles in the QWs. In-plane strain, confinement potential, and subband energy levels of the QW are calculated using multi-band effective mass theory. We show a space-indirect transition between light holes localized in indium deficient region and electrons localized in indium rich region of the quantum well. Our results show that the optical transition energies are approximately constant for the segregation efficiencies smaller than 0.7 in both QWs.     

Interfacial structure and properties in polystyrene/epoxy bilayer films

The interfacial structure and properties of immiscible deuterated polystyrene (dPS)/epoxy bilayer films were investigated with neutron reflectivity as functions of the composition of the epoxy layer, the thickness of the dPS layer, and the annealing time. We have found that the interfacial width and its growth rate depend strongly on the compositions of the epoxy layer but only weakly on the thickness of the dPS layer. The effect of the resin/crosslinker composition on the interfacial width and its growth rate is likely due to the different near‐surface structures that result for different epoxy stoichiometries. For an ultra‐thin dPS film (thickness = 2R_g), the data suggest a slight suppression of the growth of the interfacial width that could be due to confinement effects for the long‐chain molecules such as have been previously reported for a thickness of less than approximately 4R_g, where R_g is the radius of gyration of polymer molecules. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2653–2660, 2002     

Composition and in vitro cytotoxic activities of essential oil of Hedychium spicatum from different geographical regions of western Himalaya by principal components analysis

The rhizome of Hedychium spicatum has been widely used in traditional medicines. The present study deals with the evaluation of the cytotoxic potential of rhizome essential oils from four different regions of the Western Himalaya (India) along with comparative correlation analysis to characterise the bioactive cytotoxic component. The essential oils were coded as MHS-1, MHS-2, MHS-3 and MHS-4, and characterised using GC-FID and GC–MS. The main volatile compounds identified were 1,8-cineol, eudesmol, cubenol, spathulenol and α-cadinol. In vitro cytotoxic activities were assessed against human cancer cell lines such as, the lung (A549), colon (DLD-1, SW 620), breast (MCF-7, MDA-MB-231), head and neck (FaDu), and cervix (HeLa). MHS-4 is significantly active in comparison to other samples against all cancer cell lines. Sample MHS-4 has major proportion of monoterpene alcohol mainly 1,8-cineol. Principal components analysis was performed for the experimental results and all four samples were clustered according to their percentage inhibition at different doses.     

Inositol derived crown ethers: effect of auxiliary protecting groups and the relative orientation of crown ether oxygen atoms on their metal ion binding ability

The binding constants of crown ethers prepared from tetra-O-substituted myo- and scyllo-inositol derivatives and 2-O-substituted myo- and scyllo-inositol-1,3,5-orthoformates, with metal picrates show that the O-substituents and the relative orientation of the crown ether oxygen atoms contribute significantly to the binding of crown ethers with metal ions. In particular, the binding efficiency of myo-inositol derived crown ethers to silver and potassium ions could be enhanced by introducing benzyl ethers in the inositol ring. Hence binding efficacy and selectivity of metal ions to inositol derived crown ethers can be tuned by varying substituents on the myo-inositol ring and/or the relative orientation of crown ether oxygen atoms.