Spectroscopic measurements of excited particles in a N2 gas RF plasma-assisted carbon laser ablation

In this work, we investigated a carbon plasma plume produced by laser ablation of a graphite target in a nitrogen gas environment. The spatial distributions of C and N atoms were measured by time-resolved absorption spectroscopy. The spatial distributions of the relative densities of CN radicals, C₂, and C₃ molecules were measured using time-resolved emission spectroscopy. We determined that nitrogen gas produced an increase in carbon atom and molecule densities in the ablation plume. It was observed that the addition of RF plasma to the plume increased the CN radicals and C atom densities, and decreased the C₂ and C₃ molecule densities. The RF plasma changed the evolution of various fractional species of C, N, CN, C₂, and C₃ in the ablation plume. The chemical reactions with and without RF plasma were explained using the evolution and density of the fractional species of C, N, CN, C₂, and C₃in the plume. PACS 52.38.Mf; 42.62.Fi; 33.20.-t; 81.05.Uw     

Application of microdialysis for study of caffeine distribution into brain and cerebrospinal fluid in rats.

The usefulness of microdialysis was examined for the chronological determination of caffeine concentration in the brain and cerebrospinal fluids (CSF) following intravenous administration of caffeine in rats. The recovery percent of caffeine by microdialysis, the concentration ratio of caffeine in the dialysate against that in the brain tissue or CSF was determined. The recovery percent was proved to be constant at 5 different steady-state plasma concentrations of caffeine (0.1-280 nmol/ml) and in different collecting periods of dialysate ranging from 30 s to 10 min. The mean recovery percent in the brain and CSF were 10.9 and 13.1%, respectively. Thus, microdialysis was proved useful for determination of drug concentration in the tissue and biological fluids with time resolution of more than 30 s. The microdialysis method was then applied for the chronological determination of caffeine concentration in the brain and CSF following intravenous bolus administration. The estimated caffeine concentration in the brain and CSF was the same as those obtained by direct determination in isolated brain and CSF, respectively. Transfer of caffeine from plasma to brain and CSF were further pharmacokinetically analyzed using a modified 2-compartment model. In this kinetic model, the transfer of caffeine between the CSF and brain was neglected, since the mutual transfer of caffeine was not detected in in vivo experiments. Calculated curves were well fitted on observed caffeine concentrations in the plasma, brain and CSF.     

Radiative carrier recombination dependent on temperature and well width of InGaN/GaN single quantum well

Photoluminescence (PL) spectra and time-resolved PL are measured from around 10 to 300 K for the InGaN/GaN single quantum wells (SQWs) with well widths of 1.5, 2.5, 4 and 5 nm. For the SQWs with the well widths of 1.5 and 2.5 nm, the peak position of PL exhibits an S-shaped shift with increasing temperature. The radiative recombination time τ_RAD begins to increase at the temperature for the position to change from the red-shift to the blue-shift. The steep increase of τ_RAD is observed beyond the temperature from the blue-shift to the red-shift. For the SQWs with the well widths of 4 and 5 nm, the peak position of PL exhibits a monotonic red-shift. τ_RAD decreases at first and then increases with temperature. It is about 100-times longer in the low temperature region and about 10-times longer at room temperature as compared with those of the SQWs with narrower widths.     

A Small One-Fiber WDM Optical Ethernet PC Card for FTTD

A new generation of network interface card for fiber-to-the-desktop has been fabricated. The fabricated card is PC-card size and suitable for notebook PCs. It could become the key element in the coming optical Ethernet age.     

On orders of approximation of plane curves by parametric cubic splines

The aim of the present paper is to show that the convergence rate of the parametric cubic spline approximation of a plane curve is of order four instead of order three. For the first and second derivatives, the rates are of order three and two, respectively. Finally some numerical examples are given to illustrate the predicted error behaviour.     

Itinerant ferromagnetism in the multiorbital Hubbard model: a dynamical mean-field study

In order to resolve the long-standing issue of how itinerant ferromagnetism is affected by lattice structure and Hund's coupling, we compare various three-dimensional lattice structures in the single- and multiorbital Hubbard models with the dynamical mean-field theory with an improved quantum Monte Carlo algorithm that preserves the spin-SU(2) symmetry. The result indicates that both the lattice structure and the d-orbital degeneracy are essential for the ferromagnetism in the parameter region representing a transition metal. Specifically, (a) Hund's coupling, despite the common belief, is important, which is here identified to come from particle-hole scatterings, and (b) the ferromagnetism is a correlation effect (outside the Stoner picture) as indicated from the band-filling dependence.     

Similar Structural Dynamics for the Degradation of CH3NH3PbI3 in Air and in Vacuum

We investigate the degradation path of MAPbI₃ (MA=methylammonium) films over flat TiO₂ substrates at room temperature by means of X‐ray diffraction, spectroscopic ellipsometry, X‐ray photoelectron spectroscopy, and high‐resolution transmission electron microscopy. The degradation dynamics is found to be similar in air and under vacuum conditions, which leads to the conclusion that the occurrence of intrinsic thermodynamic mechanisms is not necessarily linked to humidity. The process has an early stage, which drives the starting tetragonal lattice in the direction of a cubic atomic arrangement. This early stage is followed by a phase change towards PbI₂. We describe how this degradation product is structurally coupled with the original MAPbI₃ lattice through the orientation of its constituent PbI₆ octahedra. Our results suggest a slight octahedral rearrangement after volatilization of HI+CH₃NH₂ or MAI, with a relatively low energy cost. Our experiments also clarify why reducing the interfaces and internal defects in the perovskite lattice enhances the stability of the material.     

Effect of γ irradiation on the surface properties of wet polysulfone films containing poly(vinylpyrrolidone)

In Japan, hemodialyzers are usually sterilized by γ irradiation. However, the polymer materials used in the dialysis membrane, such as polysulfone (PSf) and poly(vinylpyrrolidone) (PVP), undergo crosslinking or degradation on exposure to γ radiation. In the present study, we prepared PSf/PVP films (PVP content, 0–50 wt%) and used atomic force microscopy (AFM) to perform nanoscale evaluations of the effect of γ irradiation (25 and 50 kGy) on the surface properties of wet PSf/PVP surfaces. Force‐curve measurements were used to evaluate the hardness of and fibrinogen adsorbability on the wet PSf/PVP surface; fibrinogen adsorbability on the wet PSf/PVP surface was evaluated using AFM probes with fibrinogen immobilized on the tips of the probes. At PVP levels greater than 5 wt%, the wet PSf/PVP film surface was completely covered with hydrated and swollen PVP particles. The surface hardness of the wet PSf/PVP films exposed to 25‐kGy γ irradiation greatly decreased with increasing PVP content, whereas the surface hardness of the wet PSf/PVP films exposed to 50‐kGy γ irradiation did not decrease significantly. At higher PVP levels, the reduction in the fibrinogen adsorbability on a wet PSf/PVP film exposed to 25‐kGy γ irradiation was more significant than that on a wet PSf/PVP film exposed to 50‐kGy γ irradiation. PVP particles on the wet PSf/PVP film surface exposed to 50‐kGy γ irradiation did not show significant hydration and swelling because the polymer materials PVP–PSf and PVP‐PVP in these membranes has undergone excessive crosslinking due to γ irradiation. Copyright © 2010 John Wiley & Sons, Ltd.     

Phosphoproteome Profiling Using a Fluorescent Phosphosensor Dye in Two-Dimensional Polyacrylamide Gel Electrophoresis

We validated the novel PhosphoQUANTI SolidBlue Complex (PQSC) dye for the sensitive fluorescent detection of phosphorylated proteins in polyacrylamide- and two-dimensional gel electrophoresis (PAGE and 2DE, respectively). PQSC can detect as little as 15.6 ng of ß-casein, a pentaphosphorylated protein, and 61.3 ng of ovalbumin, a diphosphorylated protein. Fluorescence intensity correlates with the number of phosphorylated residues on the protein. To demonstrate the specificity of PQSC for phosphoproteins, enzymatically dephosphorylated lysates of Swiss 3T3 cells were separated in 2DE gels and stained by PQSC. The fluorescence signals in these gels were markedly reduced following dephosphorylation. When the phosphorylated proteins in Swiss 3T3 cell lysates were concentrated using a phosphoprotein enrichment column, the majority of phosphoproteins showed fluorescence signals in the pI 4–5 range. Finally, we performed phosphoproteome analysis to study differences in the protein phosphorylation profiles of proliferating and quiescent Swiss 3T3 cells. Over 135 discernible protein spots were detected, from which a selection of 15 spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS). The PQSC staining procedure for phosphoprotein detection is simple, reversible, and fully compatible with MALDI TOF-MS.     

Self-organizing surface-initiated polymerization: facile access to complex functional systems

Facile access to complex systems is crucial to generate the functional materials of the future. Herein, we report self-organizing surface-initiated polymerization (SOSIP) as a user-friendly method to create ordered as well as oriented functional systems on transparent oxide surfaces. In SOSIP, self-organization of monomers and ring-opening disulfide exchange polymerization are combined to ensure the controlled growth of the polymer from the surface. This approach provides rapid access to thick films with smooth, reactivatable surfaces and long-range order with few defects and high precision, including panchromatic photosystems with oriented four-component redox gradients. The activity of SOSIP architectures is clearly better than that of disordered controls.