A simple monitoring system for single subpicosecond laser pulses using an SH spatial autocorrelation method and a CCD image sensor

A simple noncollinear SHG autocorrelator for monitoring the time behavior of single subpicosecond laser pulses is described. A new CCD image-line sensor with high sensitivity in the UV range is used to measure the second-harmonic (SH) spatial distribution which gives information on the duration of the fundamental light pulses. An input energy of only 10 μJ is enough to obtain the SH spatial beam patterns in this highly sensitive autocorrelation system.     

1,3,5-tristyrylbenzene dendrimers: a novel model system to explore oxygen quenching in a highly organized environment

Control of the efficiency of photoisomerization by oxygen was demonstrated for 1,3,5-tristyrylbenzene dendrimers 1-3; the large dendrons do not significantly affect the photochemistry itself due to volume-conserving isomerization mechanisms but may affect the mobility of the molecules.     

Systematic study on synthesis and structural, electrical transport and magnetic properties of Pb-substituted Bi-Ca-Co-O misfit-layer cobaltites

Single-phases of Pb-substituted Bi-Ca-Co-O misfit-layer cobaltites with various Pb concentrations have been synthesized and the Pb-substitution effects on the structural, electrical and magnetic properties have been systematically investigated. Powder X-ray diffraction analysis showed that the single-phases of Bi_1.8−x/2Pb_xCa₂Co₂O_z were obtained up to x=0.6-0.7 under the optimized synthesis conditions. The lattice parameters of Bi_1.8−x/2Pb_xCa₂Co₂O_z continuously changed with increasing Pb concentration. The electron diffraction analysis suggested that the structure consisted of two different sublattices with a rock salt structure (RS) and a hexagonal CdI₂ structure (H), respectively, without modulation. In combined with the chemical composition analysis, the chemical formulas of the x=0 and x=0.6 samples were determined approximately as [Bi_1.74Co_0.31Ca_2.01O₄]^RS[CoO₂]_1.69 and [Bi_1.47Pb_0.38Co_0.29Ca_1.98O₄]^RS[CoO₂]_1.71, respectively. The electrical resistivity became more metallic with increasing the Pb concentration up to x=0.6. Moreover, the Pb-substitution simultaneously increased the antiferromagnetic Weiss temperatures and decreased the effective magnetic moments of the Co ions.     

Quantification of ATRP initiator density on polymer latex particles by fluorescence labeling technique using copper‐catalyzed azide‐alkyne cycloaddition

We developed a novel fluorescence labeling technique for quantification of surface densities of atom transfer radical polymerization (ATRP) initiators on polymer particles. The cationic P(St‐CPEM‐C₄DMAEMA) and anionic P(St‐CPEM) polymer latex particles carrying ATRP‐initiating chlorine groups were prepared by emulsifier‐free emulsion polymerization of styrene (St), 2‐(2‐chloropropionyloxy)ethyl methacrylate (CPEM), and N‐n‐butyl‐N,N‐dimethyl‐N‐(2‐methacryloyloxy)ethylammonium bromide (C₄DMAEMA). ATRP initiators on the surface of polymer particles were converted into azide groups by sodium azide, followed by fluorescent labeling with 5‐(N,N‐dimethylamino)‐N′‐(prop‐2‐yn‐1‐yl)naphthalene‐1‐sulfonamide (Dansyl‐alkyne) by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). The reaction time required for both azidation of ATRP‐initiating groups and successive fluorescence labeling of azide groups with Dansyl‐alkyne by CuAAC were investigated in detail by FTIR and fluorescence spectral measurement, respectively. The ATRP initiator densities on the cationic P(St‐CPEM‐C₄DMAEMA) and anionic P(St‐CPEM) particle surfaces were estimated to be 0.21 and 0.15 molecules nm^?2, respectively, which gave close agreement with values previously determined by a conductometric titration method. The fluorescence labeling through click chemistry proposed herein is a versatile technique to quantify the surface ATRP initiator density both on anionic and cationic polymer particles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4042–4051     

Water‐disintegrative and biodegradable blends containing poly(L‐lactic acid) and poly(butylene adipate‐co‐terephthalate)

In this study, novel biodegradable materials were successfully generated, which have excellent mechanical properties in air during usage and storage, but whose structure easily disintegrates when immersed in water. The materials were prepared by melt blending poly(L ‐lactic acid) (PLLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) with a small amount of oligomeric poly(aspartic acid‐co‐lactide) (PAL) as a degradation accelerator. The degradation behavior of the blends was investigated by immersing the blend films in phosphate‐buffered saline (pH = 7.3) at 40 °C. It was shown that the PAL content and composition significantly affected morphology, mechanical properties, and hydrolysis rate of the blends. It was observed that the blends containing PAL with higher molar ratios of L ‐lactyl [LA]/[Asp] had smaller PBAT domain size, showing better mechanical properties when compared with those containing PAL with lower molar ratios of [LA]/[Asp]. The degradation rates of both PLLA and PBAT components in the ternary blends simultaneously became higher for the blends containing PAL with higher molar ratios of [LA]/[Asp]. It was confirmed that the PLLA component and its decomposed materials efficiently catalyze the hydrolytic degradation of the PBAT component, but by contrast that the PBAT component and its decomposed materials do not catalyze the hydrolytic degradation of the PLLA component in the blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Anomalous thermochromic transition of poly(di‐n‐octylsilane)

The thermochromic behavior of poly(di‐n‐octylsilane) {[Si(C₈H₁₇)₂]_n; PDOS} was studied by ultraviolet (UV) absorption, differential scanning calorimetry, and X‐ray diffraction measurements. The structure of PDOS in the low‐temperature phase strongly depended on not only the temperature but also the rate of cooling, that is, the thermal history. Temperature‐dependent UV absorption spectra were highly dependent on thermal hysteresis. Cooled rapidly (10 K/min), PDOS showed two absorption peaks at 3.32 and 3.51 eV in low‐temperature‐ordered phases, whereas a single absorption peak at 3.32 eV became predominant with slow cooling (0.3 K/min). The appearance of the two peaks at low temperatures suggested that a mixture of different conformations was introduced by rapid cooling. A fiber diffraction pattern measured at 240 K after rapid cooling also showed evidence of the existence of novel conformation. A temperature‐dependent powder X‐ray diffraction pattern changed significantly between 270 and 280 K. Rapid cooling reduced the intensity of the X‐ray diffraction peak in this temperature region. This intensity change was explained by the conformational mixture in the polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1085–1092, 2001     

An enzyme-linked immunometric assay for cortisol based on idiotype-anti-idiotype reactions

Cortisol levels in body fluids are useful for monitoring the function of the pituitary-adrenal axis. Here, we established an “enzyme-linked immunometric assay” (a noncompetitive-type ELISA) for cortisol based on idiotype-anti-idiotype reactions. Six different anti-idiotype monoclonal antibodies that recognized the variable regions of a newly established anti-cortisol antibody were generated using hybridoma technology; these were two β-type and four α-type anti-idiotype antibodies, recognizing the paratope and framework regions, respectively. An immunometric assay was established using a combination of a selected α-type and a selected β-type antibody. The analyte (cortisol) was captured by an excess amount of anti-cortisol antibody immobilized on microplates, and the unoccupied paratope was saturated with the β-type antibody. Hapten-occupied anti-cortisol antibody, with less steric hindrance, was then selectively bound by the α-type antibody, labeled with biotin. The amount of biotin residue on the microplates was colorimetrically monitored using a peroxidase-labeled streptavidin. This assay had an approximately threefold higher sensitivity (detection limit: 90 pg = 248 fmol cortisol) than a competitive ELISA using the same anti-cortisol antibody, as well as a practical specificity for providing reasonable determination of normal urinary cortisol levels.     

On the Cauchy problem for non-effectively hyperbolic operators,the Gevrey 5 well-posedness

In this paper, we prove that for non-effectively hyperbolic operators with smooth double characteristics exhibiting a Jordan block of size 4 on the double manifold, the Cauchy problem is well-posed in the Gevrey 5 class, beyond the generic Gevrey class 2 (see, e.g., [5]). Moreover, we show that this value is optimal, due to certain geometric constraints on the Hamiltonian flow of the principal symbol. These results, together with results already proved, give a complete picture of the well-posedness of the Cauchy problem around hyperbolic double characteristics.     

Organic high-spin systems: Synthesis,electrochemical and spectroscopic studies of π-extended tetraaryl m-phenylenediamines

Three highly π-extended tetraaryl-1,3-phenylenediamines for charged high-spin molecular systems were successfully synthesized using Suzuki coupling. Their electrochemical and spectroscopic properties were also examined. They showed blue fluorescence. The dications derived from highly π-extended tetraaryl-1,3-phenylenediamines were generated and characterized by electron transfer stopped-flow method.