Preparation of porous polysulfone beads for selective removal of endocrine disruptors

Porous polysulfone (PSf) beads are prepared using a liquid–liquid phase separation technique. The porous PSf beads are then used for the removal of endocrine disruptors, such as Biphenyl (BP), dibenzofuran (DBF), dibenzo-p-dioxin (DBD), biphenol A (BPA), and diethylstylbestrol (DES) from their aqueous solutions. The endocrine disruptors could be removed efficiently by a simple sorption method with hydrophobic porous PSf beads. The removal ratio was high for endocrine disruptors having high octanol–water distribution coefficients. The effect of sorption time, weight of PSf beads, ethanol amount in the solution, and the porosity of the beads on the removal of endocrine disruptors was investigated. The adsorbed endocrine disruptors in the PSf beads could be effectively removed by 2-propanol or ethanol, which indicated that the beads could be reused. The study suggested that the porous PSf beads have a potential ability to be used for the removal of endocrine disruptors in environmental application.     

Phase separation temperatures in the polystyrene—poly(α-methyl styrene)—methylcyclohexane system

The phase separation temperatures (PST) in the ternary system polystyrene (PS) (M_w = 1.75 × 10⁴ g mol⁻¹ — poly(α-methyl styrene) (PαMS) (M_w = 6.0 × 10⁴) — methylcyclohexane (MCH) and the binary systems PS-MCH and PαMS-MCH have been determined by using a He---Ne laser light-scattering apparatus over the total polymer weight fraction (W_{PS + PαMS}) range of 0.018 to 0.80 and various polymer blend ratios. The PST determined at a scattering angle of 0° agreed with those at 90° for the binary systems over polymer concentrations of 0.1 to 0.7 and for the ternary over W_{PS + PαMS} of higher than 0.3. Deviations of the PST determined at an angle of 90° from those at 0° were observed in the ternary system when W_{PS + PαMS} was lower than 0.3. Two phase separation temperatures, at which the intensity scattered from zero angle changed discontinuously, are observed at concentrations lower than W_{PS + PαMS} = 0.042 in the ternary system. The PST in the ternary system decreases monotonically with increasing W_{PS + PαMS} over 0.3 to 0.7. The phase diagram for the PS-PαMS-MCH system at W_{PS + PαMS} = 0.8 is characterized by a maximum PST around − 14°C.     

Cationic grafting from carbon black

Summary The cationic ring-opening copolymerization of tetrahydrofuran (THF) with a cyclic acid anhydride such as phthalic anhydride (PAn) and maleic anhydride was initiated by acylium perchlorate groups on carbon black to give alternating copolymer, i.e., polyester. Epichlorohydrin was found to act as effective promoter in the copolymerization. The polyester formed was effectively grafted from carbon black depending upon the propagation of the polymer from the surface: the grafting ratio of polyester from THF and PAn was increased up to about 65% with an increase in conversion. The polyester-grafted carbon black gave a stable colloidal dispersion in chloroform.     

Grafting onto carbon black by the reaction of reactive carbon black having acyl chloride group with several polymers

Summary Acyl chloride group introduced onto carbon black rapidly lost its activity by the moisture in air. However, the decrease of acyl chloride group content in vacuum was negligibly small. By the reaction of the acyl chloride group with several polymers having hydroxyl or amino group, such as polyethylene glycol (PEG), poly(vinyl alcohol)(PVA), and polyethyleneimine (PEI), these polymers were found to be effectively grafted onto carbon black; for instance, the grafting ratio of PEG (Mn=8.2×10³), PVA (Mn=2.2×10⁴), and PEI (Mn=2.0×10⁴) was 18.5%, 32.9%, and 45.8%, respectively. The number of polymer grafted onto carbon black decreased with an increase of its molecular weight.     

Sterols and fatty acids of a whisk fernPsilotum nudum

The sterols and fatty acids ofPsilotum nudum were investigated. The 4,4-dimethyl- and 4α-methylsterol fractions contained 24β-methyl-Δ²⁵-unsaturated sterols,viz., cyclolaudenol and 24β-methyl-25-dehydrolophenol, respectively, as dominant sterols among the other components common in vascular plants. 24-Methylcholesterol (mixture of C-24 epimers) and sitosterol constituted the dominant sterols in the 4-demethylsterol fraction. This is the first identification of 24-methylene-5α-lanost-8-en-3β-ol, 24β-methyl-25-dehydrolophenol, codisterol, isofucosterol, 24-methylene-25-methylcholesterol and avenasterol in a fern. The major fatty acids were 16:0, 18:1, 18:2, 18:3 and 20:3. In addition, several C₂₀ fatty acids with various unsaturation were found to be present in low concentrations.     

UV-Curable Adhesives For Optical Communications

UV-curable optical adhesive systems featuring refractive indices in the 1.45 to 1.59 region controllable to within 0.005 are developed using new fluoro-epoxies and fluoro-epoxy (meth) acrylates. These adhesives possess excellent refractive index matching with optical glass and optical fibres, and the joints exhibit high bonding strength and good durability. These high performance adhesives are readily applicable as optical adhesives in fabricating optical components, attaching fibres to optical waveguides, and splicing optical fibres for optical communications.     

Tribological characteristics of novel branched perfluoropolyether lubricant films in hard disk drives

In this study, the basic tribological characteristics of novel branched perfluoropolyether (PFPE) lubricant films such as TA-30 and QA-40 were examined. Their surface free energy characteristics and adhesive and friction forces were investigated using an atomic force microscope. The interactions between the lubricant molecules and the water molecules were also examined by monitoring the changes in the contact angle of distilled water on the test lubricant films. The interactive forces such as the adhesive and friction forces of a film that is approximately one monolayer thick were found to be strongly dependent on the conformation of the lubricant molecules on diamond-like carbon thin films. In addition, the TA-30 and QA-40 lubricant molecules appeared to interact with the water molecules more actively than conventional Ztetraol2000 molecules. These results afforded fundamental insight into the tribological performance of novel branched PFPE lubricants in the head-disk interface.     

Digital image processing for nonperiodic objects and an on-line image processing system for high resolution electron microscopy

A digital image processing method for noise removal and image enhancement in nonperiodic structural images is described. The method for noise removal uses a reversible transform between an image and image autocorrelation function. The Laplacian filter is then employed for image enhancement. Furthermore, an on-line image processing system for highresolution TEM is presented.     

A study of bacterial culturability during bioaerosol challenge test using a test chamber

The bioaerosol challenge test using a chamber is performed to evaluate the specificity of air purifiers and samplers. Bacterial cells are exposed to various stresses in each step of the test and the detail of the influences by the stresses has been reported. These reports are very detailed but the change of the bacterial biological activity through the chamber test has not been referred yet. We followed the bacterial activity in each step through the practical bioaerosol challenge test for the specificity evaluation of an apparatus using Staphylococcus epidermidis and Escherichia coli, and tried to estimate the degree to which bacterial cells are stressed during the test by investigating bacterial culturability and the redox dye reduction activity. We used the ratio of the culturable or active cell number to the total cell number as a common indicator through the test step. According to the results, culturability of S. epidermidis and E. coli decreased to 98% and 93% of initial value by nebulization, respectively, but the culturability change of each bacterium was not significantly different. On the other hand, 54% of the cells in the original suspension used for nebulization lost their culturability after aerosolization in S. epidermidis. Furthermore we observed that culturability changed after a centrifugation wash cycle during sample preparation in E. coli, but not in S. epidermidis. We do not intend just to report the bacterial viability or culturability change in our system as one of the case studies in this paper. Bacterial biological activity cannot be controlled completely every time even if the cells are prepared by the same protocols. For the purpose of accurate evaluation, we will discuss the importance to mind that the cells which the tested apparatus is measuring in each step of the test are the cells which exist in what status of bacterial activity with showing our actual results through the chamber test. The actual evaluation systems for the specificity confirmation of apparatuses will be commonly established based on the reported basic information. The difference of opinion about the bacterial activity through the chamber test could lead to misjudgment of the specificity of a tested apparatus.     

Effect of Tensile Stress on Hall Coefficients of Nickel-Base Superalloys

This paper reports on Hall Effect measurements on nickel-base superalloys and their stress dependency. The work is motivated by the desire to develop a nondestructive method of characterizing the near-surface protective residual stress in metals. Our approach is based on the assumption that the Hall coefficient deviates under the stress. It is anticipated that stress measurements based on the Hall Effect are less contaminated by cold work and other effects than conductivity-based measurements such as eddy current. The paper focuses on the two superalloys, Inconel 718 and Inconel 600. The challenge is that Hall coefficients are small in metals, and the stress-induced changes are even smaller. To measure the small effect, the lock-in technique was used, with AC injected current and AC magnetic field. It was found that the Hall coefficients indeed vary proportionally to the stress. The proportionality coefficients are significantly larger than what are estimated from the volumetric effect in a free carrier gas model. The temperature and injected current dependences of the Hall coefficients were also measured, while no dependence on the magnetic flux density was observed.