Condensation heat transfer in a rotating horizontal cylinder with a scraper

A dryer used in the drying process of paper production is usually a rotating horizontal cylinder in which steam condenses. This study concerns some experiments and analyses of condensate flow and heat transfer in a dryer with a scraper.

A laminar film model and a solid film model are introduced for the theoretical analyses. In the former the condensate flow is assumed to be laminar. In the latter the condensate film is assumed to adhere to the cylinder wall. In the analysis with the laminar film model, the film thickness diverges at relatively slow rotations. A criterion for the critical condition at which the divergence commences is proposed. From the solid film model, analytical expressions can be derived for the film thickness and the heat transmission coefficient through the condensate film and the cylinder wall.

The experiments are conducted with an acrylic resin cylinder and a stainless steel cylinder. The experimental result on heat transmission agrees with the analytical result for the solid film model if a condensate film about 25 μm thick remains in spite of scraping.     

Microchip analysis of plant glucosinolates

We describe a new and selective analytical method for the separation and quantitation of plant glucosinolates. The new method, which utilizes microchip CE (micro-CE) with fluorescence detection, circumvents the multistep procedures characteristic of conventional methods. Glucosinolates form charge transfer complexes with the xanthene dyes phloxine-B and eosin-B. The glucosinolates-phloxine-B complex cannot be excited at 470 nm. Thus, the decrease in peak intensity of phloxine-B after complex formation is used to quantitatively measure total glucosinolates in Arabidopsis thaliana seeds. For qualitative analysis, complex formation with eosin-B is used. The sensitivity of eosin-B detection at excitation/emission 470 nm/540 nm was low. However, sensitivity increased following complex formation with sinigrin (> or =3 microg/mL). A batch-learning, self-organizing map was applied to visualize and organize analytical data into 2-D matrix with similar and related data clustered together or near each other. This organized matrix was used to optimize electrophoretic conditions for the analysis. This study suggests potential applications of micro-CE in plant metabolomics analyses without use of labeling fluorophores.     

Preparation of “pore-fill” type Pd–YSZ–γ-Al2O3 composite membrane supported on α-Al2O3 tube for hydrogen separation

Mesoporous YSZ–γ-Al₂O₃ membranes were coated on α-Al₂O₃ (Ø2 mm) tube by dipping the α-Al₂O₃ support tube into mixed sol consists of nano-size YSZ and bohemite particles followed by drying and calcination at 600 °C. Addition of bohemite in YSZ sol helped a good adhesion and uniform coating of the membrane film onto α-Al₂O₃ support. The quality of the mesoporous YSZ–γ-Al₂O₃ membranes was evaluated by the gas permeability experiments. The number of defects was minimized when the γ-Al₂O₃ content became more than 40%. Addition of γ-Al₂O₃ inhibited the crystal growth of YSZ, sintering shrinkage and distortion stress. Increase of calcination temperature and time results in the increase of pore size and N₂ permeance. A hydrogen perm-selective membrane was prepared by filling palladium into the nano-pores of YSZ–γ-Al₂O₃ layer by vacuum-assisted electroless plating. Crystal growth of palladium was observed by thermal annealing of the membrane at 600 °C for 40 h. The Pd–YSZ–γ-Al₂O₃ composite membrane revealed improved thermal stability allowing long-term operation at elevated temperature (>500 °C). This has been attributed to the improved fracture toughness of YSZ–γ-Al₂O₃ layer and matching of thermal expansion coefficient between palladium and YSZ. Although fracture of the membrane did not occur, decline of H₂ flux was observed when the membrane was exposed in 600 °C. This has been attributed to the agglomeration of palladium particles by crystal growth and dense packing into the pore networks of YSZ–γ-Al₂O₃ by elevation of temperature.     

Lanthanide-based protease activity sensors for time-resolved fluorescence measurements

Lanthanide-based luminescent sensors are noteworthy because their long-lifetime luminescence enables time-resolved fluorescence measurements. After exploring suitable antenna groups, we designed and synthesized lanthanide-based luminogenic sensors detecting protease activities. This sensor yielded strong luminescence on addition of proteases such as calpain I and leucine aminopeptidase (LAP). Since the luminescence lifetimes of the probes were very long, the sensors could be applied to time-resolved measurements that exclude background fluorescence signals derived from proteins or other impurities. This sensing principle could be applicable to general time-resolved fluorescence assays for other proteases.     

Binding of Ricinus communis agglutinin to a galactose-carrying polymer brush on a colloidal gold monolayer

A polymer with many pendent galactose residues was prepared by atom-transfer radical polymerization (ATRP) of galactose-carrying vinyl monomer, 2-lactobionamidoethyl methacrylate (LAMA), with a disulfide-carrying ATRP initiator, 2-(2'-bromoisobutyroyl)ethyl disulfide (DT-Br). The galactose-carrying polymer obtained (DT-PLAMA) was accumulated as a polymer brush via Au-S bond on a colloidal gold monolayer deposited on a cover glass. For comparison, a disulfide which carried one galactose residue at both ends (2-lactobionamidoethyl disulfide, Cys-Lac) was accumulated as a self-assembled monolayer (SAM) on the colloidal gold monolayer, too. The association and dissociation processes of galactose residues on the colloidal gold with a lectin, Ricinus communis agglutinin (RCA(120)), were observed by the increase and decrease in absorbance at 550nm corresponding to localized surface plasmon resonance (LSPR) phenomena. The Cys-Lac SAM-carrying glass chip showed a strong non-specific adsorption of the lectin, whereas the DT-PLAMA brush-carrying one reversibly associated with the lectin, indicating reusability of the latter device. The apparent association constant of the lectin with the galactose residues in the DT-PLAMA brush was much larger than the association constant for free galactose, and the detection limit of RCA(120) by the glycopolymer brush-modified device was satisfactorily low. Furthermore, a microscopic observation clearly indicated that the DT-PLAMA brush could reversibly associate with a HepG2 cell having galactose receptors, though these processes could not be observed spectrophotometrically due to a gigantic size of the cell.     

A new mechanism for the addition of alcohols to disilenes revealed by DFT and ONIOM calculations

Density functional and ONIOM calculations of alcohol and phenol additions to two (tetramethyl and tetramesityl) disilenes were carried out. The dimer of MeOH adds to Me₂SiSiMe₂ more readily than the monomer. The trimer does not afford the adduct, but a zwitter-ionic intermediate. In the (CF₃OH)₂ addition to Me₂SiSiMe₂, H?Si bond formation is more advanced than O?Si bond formation in the transition state (TS). Addition of seven phenol derivatives to Me₂SiSiMe₂ was examined, and the dimer reactions were found to be superior to the monomer reaction regardless of the substituents on the benzene rings. (MeOH)₂ reacts also with Mes₂SiSiMes₂ favorably, and an isomer of the reactant-like complex (precursor) may afford an adduct of different stereochemistry via internal rotations. Generally, the dimer of the alcohol or phenol is the reactant toward the disilenes. Exceptionally, a monomer of p-(dimethylamino)phenol reacts with Mes₂SiSiMes₂ owing to steric congestion by the four mesityl groups.     

Efficient and rapid synthesis of phenolic analogs of 4-phenylbutanoic acid using microwave-assisted Michael addition as a key reaction

The addition of phenols to acrylonitrile in the presence of aqueous benzyltrimethylammonium hydroxide or tetramethylammonium hydroxide under microwave irradiation yielded the corresponding Michael adducts. The obtained adducts were easily transformed to phenolic analogs of 4-phenylbutanoic acids via the hydrolysis of nitrile groups.     

Molecular macrocluster formation on silica surfaces in phenol-cyclohexane mixtures

The adsorption of phenol, an aromatic compound with a hydrogen-bonding group, onto a silica surface in cyclohexane was investigated by colloidal probe atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and adsorption isotherm measurements. ATR-FTIR measurements on the silica surface indicated the formation of surface macroclusters of phenol through hydrogen bonding. The ATR-FTIR spectra were also measured on the H-terminated silicon surface to observe the effect of the silanol groups on the phenol adsorption. The comparison of the ATR-FTIR spectra for both the silicon oxide and H-terminated silicon surfaces proved that the silanol groups are necessary for the formation of phenol clusters on the surface. The surface force measurement using colloidal probe AFM showed a long-range attraction between the two silica surfaces in phenol-cyclohexane mixtures. This long-range attraction resulted from the contact of the adsorbed phenol layers for the phenol concentrations below 0.6 mol %, at which no significant phenol clusters formed in the bulk solution. The attraction started to decrease at 0.6 mol % phenol due to the exchange of the phenol molecules between the clusters in the bulk phase and on the surface. The surface density of phenol in the adsorbed layer was calculated on the basis of the long-range attraction and found to be much smaller than the liquid phenol density. The plausible structure of the adsorbed phenol layer was drawn by referring to the crystal structure of the bulk phenol and orientation of the phenol molecules on the surface, estimated by the dichroic analysis of ATR-FTIR spectroscopy. The investigation of the phenol adsorption on the silica surface in a nonpolar solvent using this novel approach demonstrated the effect of the aromatic ring on the surface packing density.     

Temporal diet changes recorded by stable isotopes in Asiatic black bear (Ursus thibetanus) hair

Carbon and nitrogen stable isotope ratios were measured in hair samples of the Asiatic black bear (Ursus thibetanus) inhabiting the Northern Japanese Alps (NJA) (n?=?20) and the periphery of Nagano City (NC) (n?=?6), in Nagano Prefecture, Japan. The hair of NJA bears, which did not have access to anthropogenic foods, showed lower values of δ¹³C and δ¹⁵N than that of NC bears which had access to garbage and corn fields, especially during the summer. These results reflect somewhat differing diets between the NJA and NC bears. We attempted to assess the feeding history during the hair growth cycle using the growth section analysis method. Each hair sample had been cut into 3?mm lengths from root to tip, labeled, and analyzed along the hair growth. We measured the carbon and nitrogen stable isotope ratios of each 3?mm length of hair sample from one NC bear which had been killed while raiding a corn field. The sections showed wide ranges of isotope ratios, from ?23.2‰ to ?14.6‰ for δ¹³C, and from 0.3‰ to 4.6‰ for δ¹⁵N. It was shown that the diet of this bear shifted dramatically from principally C₃ plants to more C₄ plants and to foods of animal origin. An analysis of the whole hair reflects just the average feeding habit during hair growth, but the present method can trace its diet history. This method can contribute to obtain precise ecological information of wildlife.