Preparation of phthalocyanine-bound myristoyl celluloses for photocurrent generation system

The influences of two structural modifications on the photocurrent generation performance of the Langmuir–Blodgett (LB) film of the 6-O-phthalocyaninyl cellulose derivative were investigated. These structural modifications were the substituent groups at the O-2 and O-3 positions, and the central metal of the phthalocyanine moiety. Specifically, 6-O-Zn/phthalocyaninyl- (8a) and Pd/phthalocyaninyl (8b) -2,3-di-O-myristoylcelluloses were prepared instead of 6-O-Zn/phthalocyaninyl-2,3-di-O-myristylcellulose (2). The LB monolayer film of compound 8a on an indium thin oxide electrode showed higher photocurrent generation performance than that of compound 2. This suggested that myristoyl groups (C-14 acyl groups) were more beneficial to photocurrent generation than myristyl groups (C-14 alkyl groups), as the substituent at the O-2 and O-3 positions. The LB monolayer film of compound 8b showed photocurrent generation from 500 to 700 nm, although a blue-shift in the Q-band maximum was observed. The photocurrent generation performance of compound 8b was significantly higher than that of compound 8a. This indicated that Pd was more beneficial to photocurrent generation than Zn. The film of compound 8b prepared by the horizontal lifting method showed better photocurrent generation performance than that prepared by the vertical dipping method. Consequently, compound 8b is a complementary material to the porphyrin-appended cellulose derivative (1) for photocurrent generation system.     

Geometric Properties of the Shifted Hypergeometric Functions

We will provide sufficient conditions for the shifted hypergeometric function \(z_2F_1(a,b;c;z)\) to be a member of a specific subclass of starlike functions in terms of the complex parameters a, b and c. For example, we study starlikeness of order \(\alpha ,\) \(\lambda \)-spirallikeness of order \(\alpha \) and strong starlikeness of order \(\alpha .\) In particular, those properties lead to univalence of the shifted hypergeometric functions on the unit disk.     

Nonlinear rheological behavior of a concentrated spherical silica suspension

Linear and nonlinear viscoelastic properties were examined for a 50 wt% suspension of spherical silica particles (with radius of 40 nm) in a viscous medium, 2.27/1 (wt/wt) ethylene glycol/glycerol mixture. The effective volume fraction of the particles evaluated from zero-shear viscosities of the suspension and medium was 0.53. At a quiescent state the particles had a liquid-like, isotropic spatial distribution in the medium. Dynamic moduli G^* obtained for small oscillatory strain (in the linear viscoelastic regime) exhibited a relaxation process that reflected the equilibrium Brownian motion of those particles. In the stress relaxation experiments, the linear relaxation modulus G(t) was obtained for small step strain (0.2) while the nonlinear relaxation modulus G(t, ) characterizing strong stress damping behavior was obtained for large (>0.2). G(t, ) obeyed the time-strain separability at long time scales, and the damping function h() (–G(t, )/G(t)) was determined. Steady flow measurements revealed shear-thinning of the steady state viscosity () for small shear rates (< ^–1; = linear viscoelastic relaxation time) and shear-thickening for larger (>^–1). Corresponding changes were observed also for the viscosity growth and decay functions on start up and cessation of flow, + (t, ) and _– (t, ). In the shear-thinning regime, the and dependence of ₊(t,) and _–(t,) as well as the dependence of () were well described by a BKZ-type constitutive equation using the G(t) and h() data. On the other hand, this equation completely failed in describing the behavior in the shear-thickening regime. These applicabilities of the BKZ equation were utilized to discuss the shearthinning and shear-thickening mechanisms in relation to shear effects on the structure (spatial distribution) and motion of the suspended particles.Dedicated to the memory of Prof. Dale S. Parson     

Experimental study of heat and mass transfer from a horizontal cylinder in downward air-water mist flow with blockage effect

An experimental study was made on convective heat and mass transfer from a horizontal heated cylinder in a downward flow of air-water mist at a blockage ratio of 0.4. The measured local heat transfer coefficients agree fairly well with the authors' numerical solutions obtained previously for the front surface of a cylinder over the ranges mass flow ratio 0–4.5×10⁻², a temperature difference between the cylinder and air 10–43 K, gas Reynolds number (7.9–23)×10³, Rosin-Rammler size parameter 105–168 μm, and dispersion parameter 3.4–3.7. Heat transfer augmentation, two-pahse to single-phase of greater than 19 was attained at the forward stagnation point. For heat transfer in the rear part of the cylinder, an empirical formula is derived by taking into account the dimensionless governing variables, that is, coolant-feed and evaporation parameters.     

Coordination characteristics of trivalent lanthanides and actinides in molten hydrate salts of Ca(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> and CaCl<Subscript>2</Subscript>

Distribution behavior of Ce(III), Am(III), and Cm(III) between tri-n-butyl phosphate solution and molten calcium nitrate hydrate Ca(NO₃)₂·RH₂O or molten calcium chloride hydrate CaCl₂·RH₂O was studied radiochemically. In Ca(NO₃)₂·RH₂O systems, maximum separation factors of Ce and Cm to Am were observed to be 12 (Ce/Am) and 1.7 (Cm/Am). The distribution ratios of these elements increased with the decrease of water activity in the hydrates, and the extractabilities at the water deficient region was less sensitive compared to those at the water abundant region. This trend was similar to the coordination circumstance change observed in electronic absorption spectra of Nd(III) in the hydrates.     

PIFA-mediated oxidative cycloisomerization of 2-propargyl-1,3-dicarbonyl compounds: divergent synthesis of furfuryl alcohols and furfurals

PhI(OCOCF₃)₂ (PIFA) in the presence of trifluoroacetic acid (TFA) in CH₂Cl₂ efficiently promotes the oxidative cycloisomerization of 2-propargyl 1,3-dicarbonyl compounds to give 4,5-disubstituted furfuryl alcohols. PIFA in hexafluoroisopropanol (HFIP) or PIFA-BF₃·OEt₂ in CH₂Cl₂ bring about the direct formation of furfurals from 2-propargyl 1,3-dicarbonyl compounds. In a few cases, PhIO is suitable for the direct formation of furfurals.     

Detection of interfacial phenomena with osteoblast-like cell adhesion on hydroxyapatite and oxidized polystyrene by the quartz crystal microbalance with dissipation

The adhesion process of osteoblast-like cells on hydroxyapatite (HAp) and oxidized polystyrene (PSox) was investigated using a quartz crystal microbalance with dissipation (QCM-D), confocal laser scanning microscope (CLSM), and atomic force microscope (AFM) techniques in order to clarify the interfacial phenomena between the surfaces and cells. The interfacial viscoelastic properties (shear viscosity (η(ad)), elastic shear modulus (μ(ad)), and tan δ) of the preadsorbed protein layer and the interface layer between the surfaces and cells were estimated using a Voigt-based viscoelastic model from the measured frequency (Δf) and dissipation shift (ΔD) curves. In the ΔD-Δf plots, the cell adhesion process on HAp was classified as (1) a mass increase only, (2) increases in both mass and ΔD, and (3) slight decreases in mass and ΔD. On PSox, only ΔD increases were observed, indicating that the adhesion behavior depended on the surface properties. The interfacial μ(ad) value between the material surfaces and cells increased with the number of adherent cells, whereas η(ad) and tanδ decreased slightly, irrespective of the surface. Thus, the interfacial layer changed the elasticity to viscosity with an increase in the number. The tan δ values on HAp were higher than those on PSox and exceeded 1.0. Furthermore, the pseudopod-like structures of the cells on HAp had periodic stripe patterns stained with a type I collagen antibody, whereas those on PSox had cell-membrane-like structures unstained with type I collagen. These results indicate that the interfacial layers on PSox and HAp exhibit elasticity and viscosity, respectively, indicating that the rearrangements of the extracellular matrix and cytoskeleton changes cause different cell-surface interactions. Therefore, the different cell adhesion process, interfacial viscoelasticity, and morphology depending on the surfaces were successfully monitored in situ and evaluated by the QCM-D technique combined with other techniques.     

Effect of interfacial proteins on osteoblast-like cell adhesion to hydroxyapatite nanocrystals

A quartz crystal microbalance with dissipation (QCM-D) technique was employed to detecting the protein adsorption and subsequent osteoblast-like cell adhesion to hydroxyapatite (HAp) nanocrystals. The interfacial phenomena with the preadsorption of three proteins (albumin (BSA), fibronectin (Fn), and collagen (Col)), the subsequent adsorption of fetal bovine serum (FBS), and the adhesion of the cells were investigated. The QCM-D measured the frequency shift (Δf) and dissipation energy shift (ΔD), and the viscoelastic properties of the adlayers were evaluated using ΔD-Δf plot and Voigt-based viscoelastic model. The Col adsorption significantly showed higher Δf, ΔD, elasticity, and viscosity values as compared to the BSA and Fn adsorption, and the subsequent FBS adsorption depended on the preadsorbed proteins. The ΔD-Δf plot of the cell adhesion also showed a different behavior depending on the surfaces, and the Fn- and Col-modified surfaces showed the rapid mass and ΔD changes by forming the viscous interfacial layers with cell adhesion, indicating that the processes were affected by the cellular reaction through the extracellular matrix (ECM) proteins. The confocal laser scanning microscope images of adherent cells showed a different morphology and pseudopod on the surfaces. The cells adhered to the surfaces modified with the Fn and Col had significantly uniaxially expanded shapes and fibrous pseudopods, and those modified with the BSA had a round shape. Therefore, the different cell-protein interactions would cause the arrangement of the ECM and the cytoskeleton changes at the interfaces, and these phenomena were successfully detected by the QCM-D and Voigt-based model.     

Near-infrared BODIPY dyes modulated with spirofluorene moieties

New structurally constrained BODIPY dyes having electron-donating substituents were synthesized. As the key compounds for the construction of the BODIPY dyes, 1′H-spiro-[fluorene-9,4′-indeno[1,2-b]pyrrole] (sp-FIP) derivatives with electron-donating groups, such as OMe and NMe₂ at its 6′-position, were prepared using palladium-catalyzed intramolecular direct C-H arylation of a pyrrole moiety. The resulting BODIPY dyes showed bathochromic shift in absorption and fluorescence spectra in comparison to the unsubstituted analogs. Furthermore, pH-dependent reversible spectrum changes of the BODIPY dye were observed with the addition of trifluoroacetic acid (TFA) and subsequent addition of i-Pr₂NEt.