Cellulose dyeing parameters of 18 isomeric phenylazo-H-acid dyes containing two different reactive groups

Eighteen isomeric dyes, each based on phenylazo-H-acid and containing two reactive groups, namely a monochlorotriazine group and a sulphuric acid ester of ß-hydroxyethylsulphone, were applied to cotton fabric by an exhaustion process at 60d?C. The following properties were studied: spectra, uptake curves of the dyes before and after adding sodium carbonate, affinity, diffusion rate, and rates of hydrolysis and of reaction with cellulose, as evidenced by fixation and colour yield. Some significant correlations were found, but some missing or poor correlations indicated that there are further parameters or relationships between parameters that remain to be elucidated.     

Levelling properties of some reactive dyes on cellulose

The levelling properties of nine reactive dyes containing one or two sulphatoethylsulphone reactive groups or one sulphatoethylsulphone and one monochlorotriazine reactive groups have been investigated. A novel test method specifically applicable to reactive dyes has been used in order to evaluate levelling. Undyed and dyed cotton samples were simultaneously dyed in the same bath and the fractions of the additional dye fixed on each of the cotton samples were determined afterwards. A dye distribution index has been proposed that predicts reactive dye levelling according to whether the index exceeds 50% or not. The index was found to depend not only on the nature of the dyes, but also on the concentration of the dye fixed on cotton, the dyeing temperature and the salt concentration in the dye liquor. In redyeing tests the degrees of primary and secondary exhaustion and of dye fixation were measured as a function of concentration of the dye fixed on cotton. Finally a satisfactory correlation was found between the index and the classical inorganicity/organicity value of the dyes. The results also suggest that the levelling properties depend on the degree of dye aggregation.     

Acetylacetoin synthase as a marker enzyme for detecting the 2,3-butanediol cycle

Acetylacetoin synthase (AACSase) and acetylacetoin reductase (AACRase) are representative enzymes of the 2,3-butanediol cycle. After examining their induction conditions in various bacteria, the former was induced by acetoin and the latter by glucose. All strains carrying AACSase also had AACRase, but the reverse was not true. Therefore, AACSase indicates the existence of the cycle. Acetylacetoin (AAC) accumulation or the ratio of 2,3-butanediol isomer formed also indicated the presence of the cycle in bacteria. This cycle is present in some strains and not in others even for those belonging to the same species. The cycle was not always associated with the representative 2,3-butanediol-producing bacteria or bacterial sporogenesis as reported previously.     

Preparation of polydiacetylene single crystals based on physical vapor growth technique

We have succeeded in obtaining 10-mm-size polydiacetylene (PDA) single crystals using the physical vapor growth technique followed by the irradiation of ultraviolet (UV) rays, for the first time. The variety of growth conditions, such as growth temperature, growth time, carrier gases, and flow rate of gases are examined. Especially, the growth temperature and growth time have clear effects on the quality of crystals. Morphologies and sizes with relation to the various growth conditions are also observed. They show only one type of plateletlike shape with a pair of large parallelopiped planes, regardless of variety of growth conditions. The crystal thickness was estimated as about 500 nm by the observation of atomic force microscopy. The solubility of diacetylene (DA) and PDA to some organic solvents, and the X-ray diffraction data indicate that the obtained crystals are single crystals.     

A numerical approach to acrylic dyeing

A numerical approach to the relationship between depth of dyeing, dyeing temperature and rate of dyeing (time necessary for complete exhaustion) has been studied for the cationic dye/acrylic fibre dyeing system. A method for determining the optimum dyeing conditions from two absorption curves at two dyeing temperature levels has been developed. A calculation system based on these relationships has proved to be applicable and valuable in practical dyeing.     

Efficient sensitization of nanocrystalline TiO2 films with cyanine and merocyanine organic dyes

Various kinds of cyanine and merocyanine organic dyes having short anchoring groups as sensitizers on nanocrystalline TiO₂ electrodes were investigated to promote the short-circuit photocurrent (J_sc) and the solar light-to-power conversion efficiency (η_sun). The J_sc and η_sun improved when the three different three dyes (yellow and red cyanine dyes, and blue squarylium cyanine dye) were adsorbed simultaneously on a TiO₂ electrode, as compared with the J_sc and η_sun of the TiO₂ electrodes adsorbed by each single dye. The maximum η_sun was 3.1% (AM-1.5, 100 mW/cm²). The J_sc and η_sun were influenced by the solvents for the dye adsorption on the TiO₂ electrode, and the efficiencies were improved by the addition of some cholic acids into the dye solution for adsorption. The electron transfer and/or the energy transfer from the red cyanine dye to the blue cyanine dye was observed on a SiO₂ film using emission spectroscopy, suggesting a strong interaction between two dyes. The J-like aggregates of the blue cyanine dyes hardly showed sensitization efficiency.     

Photo-induced Surface Property on Transparent Mesoporous Silica Thin Films Containing Single-site Photocatalyst

The transparent Ti-containing or Cr-containing mesoporous silica thin films can be prepared on quartz plate using a spin-coating sol–gel method. The spectroscopic characterization has revealed that these thin films contain isolated and tetrahedrally coordinated titanium oxide moieties and chromium oxide moieties in their frameworks, respectively. These mesoporous silica thin films containing metal oxide moieties have demonstrated a strong hydrophilic surface property even before UV-light irradiation and the appearance of the super-hydrophilic property after UV-light irradiation. Especially, the Cr-containing mesoporous silica (CMS) thin film showed the super-hydrophilic property even under visible light irradiation. In the presence of ethylene gas, the polyethylene was successfully formed on the surface of the CMS thin film under UV-light irradiation. After the formation of polyethylene the surface property of the CMS was converted into hydrophobic while keeping its transparency. The isolated and tetrahedrally coordinated titanium oxide moieties and chromium oxide moieties are responsible for these photo-induced surface reactions.     

Surface hydrophilic–hydrophobic property on transparent mesoporous silica thin films containing chromium oxide single-site photocatalyst

Using a sol–gel/spin-coating method with organic template, the transparent mesoporous silica thin films containing chromium oxide moieties can be prepared on quartz plate. The spectroscopic characterization has revealed that these thin films contain isolated and tetrahedrally coordinated chromium oxide moieties (single-site photocatalyst) in their frameworks. Even before UV light irradiation these Cr-containing mesoporous silica (CrMS) thin films have demonstrated a hydrophilic surface property more strongly than Cr-containing non-porous silica films and mesoporous silica thin films without chromium oxide. Furthermore, the Cr-containing mesoporous silica thin films showed the super-hydrophilic property not only under UV light irradiation but also even under visible light irradiation from a fluorescent lamp. In the presence of ethylene gas, the polyethylene was successfully formed on the surface of the CrMS thin film under UV light irradiation. After the formation of polyethylene the surface property of the CrMS thin film was converted into hydrophobic while keeping its transparency. The isolated and tetrahedrally coordinated chromium oxide moieties are responsible for these photo-induced surface reactions.