Rheological properties of deionized Chinese ink

Rheological properties for Chinese ink in exhaustively deionized aqueous media were carefully examined. In the steady shear measurement, the shear viscosities of the ink could be well explained by considering the “effective” volume fraction of the particles in the ink including the electrical double layers and by using Einstein's equation for dilute suspension viscosity, when the particle volume fraction was substantially low. In the case that the volume fraction was higher, the shear viscosities showed extremely higher than those from Einstein's prediction, though the ink remained a Newtonian liquid. In the stress-strain measurement, the shear moduli were observed at strain smaller than 0.2. The “weak” aggregation among the particles in the ink under no shear or low shear rates was supported. It should be noted that the glue in the suspension plays an important role for the good liquidity of the ink and for the “weak” bridges among the particles resulting its good dispersion stability.     

The development of an automated continuous measurement system for the monitoring of HCHO and CH3CHO in the atmosphere by using an annular diffusion scrubber coupled to HPLC

An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH₃CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-performance liquid chromatograph (HPLC). With this technique, atmospheric HCHO and CH₃CHO were effectively collected by the annular diffusion scrubber which consists of a porous polytetrafluoroethylene (PTFE) tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine (DNPH) was selected as the scrubbing solution for collecting HCHO and CH₃CHO, which are derivatized to 2,4-dinitrophenylhydrazone-formaldehyde (DNPH-HCHO) and 2,4-dinitrophenylhydrazone-acetaldehyde (DNPH-CH₃CHO), respectively. An aliquot of the sample solution was automatically injected into an HPLC equipped with a semi-micro ODS column and a UV-VIS detector for separating and determining DNPH-HCHO and DNPH-CH₃CHO. All the operations are sequenced by a programmable controller, and automated continuous measurements are performed with a typical temporal resolution of 1 h. The collection efficiencies of HCHO and CH₃CHO were about 97% and 93%, respectively, at an air flow rate of 0.2 L/min. The lower detection limits (3σ of the blank hydrazones) of HCHO and CH₃CHO were 0.05 ppbv and 0.10 ppbv, respectively, in the case of 12-L air sample volume. Analytical response of a standard solution of DNPH-HCHO and DNPH-CH₃CHO by the HPLC during a 10-day continuous measurement was unchanged and the relative standard deviation (RSD) was < 1.0%. Interferences from O₃ and NO₂ were insignificant in this annular diffusion scrubber method. Both for HCHO and CH₃CHO measurements, concentrations from this developed system well agreed with those measured by a DNPH Silica cartridge method. Received: 15 July 1998 / Revised: 5 October 1998 / Accepted: 7 October 1998     

The development of an automated continuous measurement system for the monitoring of HCHO and CH3CHO in the atmosphere by using an annular diffusion scrubber coupled to HPLC

An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH₃CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-performance liquid chromatograph (HPLC). With this technique, atmospheric HCHO and CH₃CHO were effectively collected by the annular diffusion scrubber which consists of a porous polytetrafluoroethylene (PTFE) tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine (DNPH) was selected as the scrubbing solution for collecting HCHO and CH₃CHO, which are derivatized to 2,4-dinitrophenylhydrazone-formaldehyde (DNPH-HCHO) and 2,4-dinitrophenylhydrazone-acetaldehyde (DNPH-CH₃CHO), respectively. An aliquot of the sample solution was automatically injected into an HPLC equipped with a semi-micro ODS column and a UV-VIS detector for separating and determining DNPH-HCHO and DNPH-CH₃CHO. All the operations are sequenced by a programmable controller, and automated continuous measurements are performed with a typical temporal resolution of 1 h. The collection efficiencies of HCHO and CH₃CHO were about 97% and 93%, respectively, at an air flow rate of 0.2 L/min. The lower detection limits (3σ of the blank hydrazones) of HCHO and CH₃CHO were 0.05 ppbv and 0.10 ppbv, respectively, in the case of 12-L air sample volume. Analytical response of a standard solution of DNPH-HCHO and DNPH-CH₃CHO by the HPLC during a 10-day continuous measurement was unchanged and the relative standard deviation (RSD) was < 1.0%. Interferences from O₃ and NO₂ were insignificant in this annular diffusion scrubber method. Both for HCHO and CH₃CHO measurements, concentrations from this developed system well agreed with those measured by a DNPH Silica cartridge method.     

Lipase‐Catalyzed Ring‐Opening Polymerization of β‐Butyrolactone: End‐Group Analysis of Poly(3‐hydroxybutanoate) Using Supercritical Fluid Chromatography

The ring‐opening polymerization of (R,S)‐β‐butyrolactone (BL) in bulk was analyzed with respect to the polymer structure of the resulting poly[(R,S)‐3‐hydroxybutanoate)] [P(3HB)] by isolation of the pure form using preparative supercritical CO₂ fluid chromatography. It was confirmed that the four‐membered BL was polymerized in bulk by lipase to yield the corresponding cyclic, hydroxy‐ and crotonate‐terminated P(3HB)s. The relative ratios of the three types of polymers depended on the lipase concentration as well as on the monomer conversion. It was also confirmed that both cyclic and linear P(3HB) polymer species were subject to hydrolysis, and inter‐ and intramolecular transesterification by lipase to produce two series of polymers having linear and cyclic structures with higher and lower molecular weight. The formation of the cyclic P(3HB) iss regarded as the characteristic feature of the lipase‐catalyzed polymerization of BL.     

Tetra‐n‐butyl­ammonium tetrakis(penta­fluoro­benzenethiol­ato‐κS)­aurate(III)

The title compound, (C₁₆H₃₆N)[Au(C₆F₅S)₄], is the first example of a structurally characterized gold(III) complex with monodentate benzene­thiol­ate ligands. The Au atom lies on a fourfold axis and the AuS₄ group has square‐planar geometry. The anion shows a two‐dimensional linkage through π–π and C—F⋯π intermolecular interactions.     

Application of a novel photopolymer to a holographic head‐up display

A novel photopolymer for fabrication of high‐resolution volume holograms, which primarily are used on holographic optical elements such as head‐up display (HUD), is reported. This photopolymer consists of bisphenol‐type epoxy resin and radically polymerizable aliphatic monomer with diaryliodonium salt and 3‐ketocoumarin (KCD) as a complex initiator. The chemistry of imaging formation is based on the radical polymerization of the monomer initiated by a holographic exposure, following by the cationic polymerization of epoxy resin by UV‐exposure after post‐exposure baking. The yellowish color of hologram derived from KCD, the shape of peak of reconstructed light and the blue shift of wavelength of reconstructed light, were improved in order to satisfy the specifications for the combiner of HUD. A stand type holographic HUD system as an example of automotive display attached on the dashboard of an automobile is demonstrated. The display gives a high contrast image, and the combiner has good durability. Copyright © 1999 John Wiley & Sons, Ltd.     

Influence of contamination layer on thickness evaluation by X-ray reflectometry

In this study, the effect of allowing for a contamination layer on a SiO₂ film/Si substrate system on thickness determination by X-ray reflectometry (XRR) was investigated. The calculated XRR profiles obtained using a calculation model that utilizes a contamination layer for analysis showed good agreement with measured profiles. Further, the obtained physical structures were promising and within acceptable limits. Where the existence of a contamination layer was ignored in the calculation process, a part of the thickness of the contamination layer was incorporated into the determined thickness of the SiO₂ layer. In that case, the evaluated thickness was proportional to the density ratio between the contaminated and SiO₂ layers. The results of investigation of the effect of X-ray energy on layer thickness determination indicated that the effects of contamination also depend on the X-ray energy used for XRR measurements. These effects increase in the case of experiments that employ X-ray energy with a high contrast for the contamination.