Wide tuning characteristics of double-ring coupled lasers

The wide tuning characteristics of double-ring coupled lasers with/without an extended waveguide are analyzed and optimized using the scattering matrix formalism. To obtain the optimum design schemes of the tunable laser diodes, the cross coupling ratios of two rings, the tuning enhancement factor, the propagation loss of passive waveguides, the optical gain of an active region, and the back and front-facet reflectivity of the waveguide are taken into account. When the coupling ratio of the ring and input/output waveguides is fixed, the extinction ratio and the linewidth are decreased as the tuning enhancement factor is increased, while the tuning range is increased.     

Laser spectroscopy of CaF2:Eu:Sm thin films grown by pulsed laser deposition

Thin films of CaF₂ co-doped with low concentrations of Eu and Sm ions were grown by pulsed laser deposition (PLD) using a KrF (λ=248 nm) as the ablation source. To the best of our knowledge, the work presented here is the first report of rare-earth-doped CaF₂ films grown by PLD with this source. Combined laser excitation-emission spectroscopy was used to map out electronic transitions of Eu³⁺ with ⁷F₀→⁵D₁ excitation and the ⁵D₀→⁷F₁ emission. At the low concentrations used here the crystal field center of cubic symmetry is dominant in the films that are same for laser targets. However, charge compensated centers are present in the bulk crystal precursor. The removal of the charge compensated centers in the films and the target is likely caused by the target preparation where high pressure and temperature were applied.     

Power flow analysis for a floating sandwich raft isolation system using a higher-order theory

A higher-order sandwich theory is implemented in conjunction with an equivalent mobility-based power flow progressive method to determine power flow for a sandwich configured floating raft vibration isolation system. The power spectrum changes in whole frequency range effectively when core materials’ properties change. It is also shown that the loss factors of the sandwich configured floating raft influence the power flow transmitted to the foundation effectively in the medium- to high-frequency range and that the resonant peak cannot be avoided by increasing damping only in high-frequency ranges which is not found in floating raft isolation systems with isotropic beams.     

Effect of Ni doping on the phase stability and conductivity of scandia-stabilized zirconia

The effect of Ni doping on the phase stability and conductivity of scandia-stabilized zirconia (SSZ) thick film was studied. A free-standing 10SSZ thick-film (10 mol% Sc₂O₃-stabilized zirconia, ~ 10 μm thick) that was previously in contact with a Ni layer during co-firing was fabricated. The 10SSZ thick-film showed a cubic phase in contrast to the rhombohedral phase shown for a bulk 10SSZ sample. The Ni content in the SSZ thick film was ~ 1.7 mol%. The effect of Ni on the cubic phase formation was also confirmed by the similar observation of the cubic phase in the Ni-doped bulk 10SSZ sample. The observed conductivity behavior also supported the XRD observation. Ni was found to hinder the transformation of the cubic phase to the rhombohedral on cooling in 10SSZ samples after a reduction treatment.     

Dichloro­[(6R,7S,8S,14S)‐(–)‐sparteine‐κ2N,N′]mercury(II)

In the title compound, [HgCl₂(C₁₅H₂₆N₂)], the chiral alkaloid (6R,7S,8S,14S)‐(−)‐l ‐sparteine acts as a bident­ate ligand, with two Cl⁻ ligands occupying the remaining coordination sites, producing a distorted tetra­hedron. The N—Hg—N plane is twisted by 81.1 (2)° from the Cl—Hg—Cl plane. The mid‐point of the N⋯N line does not lie exactly on the Cl—Hg—Cl plane but is tilted towards one of the N atoms by 0.346 Å. Similarly, the mid‐point of the Cl⋯Cl line is tilted toward one of the Cl atoms by 0.163 Å. The packing structure shows that the complex is stabilized by two inter­atomic Cl⋯H contacts involving both Cl atoms and the methyl­ene or methine H atoms of the (−)‐sparteine ligand.     

Di­chloro­[(6R,7S,8S,14S)‐(–)‐sparteine‐κ2N,N′]­nickel(II)

In the title compound, [NiCl₂(C₁₅H₂₆N₂)], the chiral alkaloid (6R,7S,8S,14S)‐(−)‐l ‐sparteine acts as a bidentate ligand, with two chloride ligands occupying the remaining coordination sites, producing a slightly distorted tetrahedron. The N—Ni—N plane in the title complex is twisted by 81.31 (11)° from the Cl—Ni—Cl plane. Other distortions of the tetrahedron are discussed.     

Double sample preconcentration by in‐line coupled large volume single drop microextraction and sweeping in capillary electrophoresis

Single drop microextraction (SDME) is a convenient and powerful preconcentration method for CE before injection. By simple combination of sample‐handling sequences without modification of the CE apparatus, a drop of an aqueous acceptor phase covered with a thin organic layer was formed at the tip of a capillary; 10 min SDME of fluorescein and 6‐carboxyfluorescein from a donor phase of pH 1 to an acceptor phase of pH 9 provided 110‐fold enrichments without stirring the donor phase. To improve the concentration effect further, SDME was coupled with an on‐line (after injection) sample preconcentration method, sweeping, in which analytes in a long sample zone are accumulated at the boundary of a pseudostationary phase penetrating into the sample zone. It is thus necessary to inject a sample of much larger volume than that of a drop in typical SDME. A Teflon sleeve over the capillary inlet allowed a large volume drop to be held stably during extraction. By in‐line coupling 10 min SDME and sweeping of a 30 nL sample using a cationic surfactant dodecyltrimethylammonium, enrichment factors of the double preconcentration were increased up to 32 000.     

Approaches for application of sub and supercritical fluid extraction for quantification of orbifloxacin from plasma and milk: Application to disposition kinetics

Since its extensive development in the early 1980s, SFE has attracted considerable attention as a sample-preparation procedure. However, other different sample preparation procedures, including precipitation, liquid- and/or solid-phase extraction in biological fluids, also remain in use. In this investigation, SFE was introduced to isolate and identify orbifloxacin from plasma and milk. Four parameters, including the temperature and the pressure of supercritical fluid, modifier ratios, and dynamic extraction time, were evaluated and optimized to obtain the best yield of the analyte from the biological fluids. Determinations of the orbifloxacin (OBFX) in the extracts were carried out using HPLC-FLD. The optimum conditions of the extraction process that yielded the maximum analyte extraction efficiencies were 150 °C vs. 60 °C, 250 kg cm⁻², 30% vs. 35% methanol, and 40 min vs. 20 min, for plasma and milk, respectively. The linearity of the calibration curves as well as the instrument LODs/LOQs were evaluated. Good linearity (at least r² ≥ 0.999) of the calibration curves was obtained over the range from 0.2 to 0.01 μg mL⁻¹. The method showed a good recovery rate (74.2-127.73%) and precision (RSDs: 1.64-20%). The instrumental LOD and LOQ values were 0.004 μg mL⁻¹ vs. 0.01 μg mL⁻¹ or 0.006 μg mL⁻¹ vs. 0.02 μg mL⁻¹, for plasma and milk, respectively. The method was successfully applied to estimate the pharmacokinetic variables of orbifloxacin in lactating does. To the best of our knowledge, this is the first time that SFE has been applied to isolate an antimicrobial agent from biological fluids. This method is promising for clinical applications and for pharmacokinetic studies of various pharmaceuticals in biological fluids.     

Simultaneous LC−UV Analysis of Mirodenafil and Its Two Main Metabolites in Rat Plasma and Urine, and in Tissue Homogenates

A simple, rapid, and reproducible isocratic reversed-phase LC method has been established for simultaneous analysis of mirodenafil and its two main metabolites, SK3541 and SK3544, in rat plasma, urine, and tissue homogenates. Samples were deproteinized with acetonitrile containing sildenafil (internal standard). The compounds were separated on a C₁₈ column with 52:48 (v/v) 0.02 m ammonium acetate buffer (pH 6)—acetonitrile as mobile phase at a flow rate of 1.4 mL min^?1. UV detection was at 254 nm and detection limits of mirodenafil, SK3541, and SK3544 in plasma were 0.03, 0.05, and 0.1 μg mL^?1, respectively. The method is applicable to pharmacokinetic studies of mirodenafil and its metabolites in rats.     

An experimental design approach using response surface techniques to obtain optimal liquid chromatography and mass spectrometry conditions to determine the alkaloids in Meconopsi species

A statistic approach using response surface methodology (RSM) for optimization of the ultra-high performance liquid chromatography (UHPLC) gradient and ionization response of electrospray ionization mass spectrometry (ESI-MS) to analyze the main alkaloids from the plant matrices of six Meconopsi species is presented. The optimization was performed with Box–Behnken designs (BBD) and the multicriteria response variables were described using global Derringer's desirability. Four parameters of UHPLC and six major parameters of ESI-MS were investigated for their contribution to analytes separation and response, leading to a total of 27 and 54 experiments being performed for each instrument, respectively. Quantitative analysis of four main alkaloids in nine samples from six Meconopsis species was employed to evaluate the statistical significance of the parameters on UHPLC–QTOF/ESI-MS analytes response. The results indicated that the optimized UHPLC–QTOF-MS method is very sensitive with the limit of detections (LODs) ranging from 0.5 to 0.1 ng/ml. The overall intra-day and the inter-day variations were less than 2.45%. The recovery of the method was in the range of 94.3–104.8% with RSD less than 4.0%. This approach has important implication in sensitivity enhancement of the ultra-trace determination of alkaloids from complex matrixes in the fields of natural products, metabolomics and pharmacokinetics.