Interfacial Selective Study on the Gelation Behavior of Aqueous Methylcellulose Solution via a Quartz Crystal Microbalance.

It is important to understand the interfacial structure and physical properties of a polymer material to improve its function. In this study, we used a quartz crystal microbalance (QCM) and neutron reflectivity (NR) measurements to evaluate the viscoelasticity and structure of an aqueous methylcellulose solution near the gold interface. The apparent shear modulus, which was calculated from the complex frequency, was used to assess gelation behavior. The apparent shear modulus determined via the QCM suggested high-frequency rheological properties that reflected the relaxation of skeletal stretching and rotational motion of polymer segments, as well as cooperative motion of the various functional groups. The gelation temperature was found to be lowered at the interface in comparison with that of the bulk. It is suggested that the QCM can evaluate the shear modulus accompanying the gelation near the interface. The interfacial segregation on the gold substrate caused by the surface free energy and long-range van der Waals interaction was observed from NR measurements.

Interictal High Gamma Oscillation Regularity as a Marker for Presurgical Epileptogenic Zone Localization.

BACKGROUND: To ensure that epilepsy surgery is effective, accurate presurgical localization of the epileptogenic zone is essential. Our previous reports demonstrated that interictal high gamma oscillation (30-70 Hz) regularity (GOR) on intracranial electroencephalograms is related to epileptogenicity. OBJECTIVE: To examine whether preoperative GOR analysis with interictal high-density electroencephalography (HD-EEG) improves the accuracy of epileptogenic focus localization and enhances postoperative seizure control. METHODS: We calculated GOR from 20 seconds of HD-EEG data for 21 patients with refractory focal epilepsy (4 with nonlesional temporal lobe epilepsy) scheduled for epilepsy surgery. Low-resolution brain electromagnetic tomography was used to analyze the high GOR source. To validate our findings, we made comparisons with other conventional localization methods and postoperative seizure outcomes. RESULTS: In all patients, the areas of interictal high GOR were identified and resected. All patients were seizure-free after the operation. The concordance between the results of interictal high GOR on HD-EEG and those of source estimation of interictal discharge was fully overlapping in 10 cases, partially overlapping in 8 cases, and discordant in 3 cases. The concordance between the results of interictal high GOR on HD-EEG and those of interictal 123 I-iomazenil single-photon emission computed tomography was fully overlapping in 8 cases, partially overlapping in 11 cases, and discordant in 2 cases. In 4 patients with nonlesional temporal lobe epilepsy, the interictal high GOR on HD-EEG was useful in confirming the epileptogenic zone. CONCLUSION: The interictal high GOR on HD-EEG is an excellent marker for presurgical epileptogenic zone localization.

Experimental Evidence of Slow Mode Water in the Vicinity of Poly(ethylene oxide) at Physiological Temperature.

In some synthetic polymers used for medical applications, hydration water in the vicinity of the polymer chains is known to play an important role in biocompatibility and is referred to as intermediate water. The crystallization of water below 0 °C observed during thermal analysis has been considered as evidence of the presence of intermediate water. However, the origin and physicochemical properties of intermediate water have not yet been elucidated. In this study, as a typical biocompatible polymer, poly(ethylene oxide) and its hydration water were investigated with the use of terahertz time-domain spectroscopy and quasi-elastic neutron scattering. The obtained results prove the existence of a significant amount of mobile water that interacts with the polymer chains even when the water content is low at physiological temperatures.

Local Dynamics of the Hydration Water and Poly(Methyl Methacrylate) Chains in PMMA Networks.

The dynamic behavior of water molecules and polymer chains in a hydrated poly(methyl methacrylate) (PMMA) matrix containing a small amount of water molecules was investigated. Water molecules have been widely recognized as plasticizers for activating the segmental motion of polymer chains owing to their ability to reduce the glass transition temperature. In this study, combined with judicious hydrogen/deuterium labeling, we conducted quasi-elastic neutron scattering (QENS) experiments on PMMA for its dry and hydrated states. Our results clearly indicate that the dynamics of hydrated polymer chains are accelerated, and that individual water molecules are slower than bulk water. It is therefore suggested that the hydration water affects the local motion of PMMA and activates the local relaxation process known as restricted rotation, which is widely accepted to be generally insensitive to changes in the microenvironment.

Structure and Mechanical Properties of Polybutadiene Thin Films Bound to Surface-Modified Carbon Interface.

The structure and mechanical properties of polybutadiene (PB) films on bare and surface-modified carbon films were examined. There was an interfacial layer of PB near the carbon layer whose density was higher (lower) than that of the bulk material on the hydrophobic (hydrophilic) carbon surface. To glean information about the structure and mechanical properties of PB at the carbon interface, a residual layer (RL) adhering to the carbon surface, which was considered to be a model of "bound rubber layer", was obtained by rinsing the PB film with toluene. The density and thickness of the RLs were identical to those of the interfacial layer of the PB film. In accordance with the change in the density, normal stress of the RLs evaluated by atomic force microscopy was also dependent on the surface free energy: the RLs on the hydrophobic carbon were hard like glass, whereas those on the hydrophilic carbon were soft like rubber. Similarly, the wear test revealed that the RLs on the hydrophilic carbon could be peeled off by scratching under a certain stress, whereas the RLs on the hydrophobic carbons were resistant to scratching.

Mechanically Induced Opening-Closing Action of Binaphthyl Molecular Pliers: Digital Phase Transition versus Continuous Conformational Change.

Reversible dynamic control of structure is a significant challenge in molecular nanotechnology. Previously, we have reported a mechanically induced continuous (analog) conformational variation in an amphiphilic binaphthyl, where closing of molecular pliers was achieved by compression of a molecular monolayer composed of these molecules at the air-water interface. In this work we report that a phase transition induced by an applied mechanical stress enables discontinuous digital (1/0) opening of simple binaphthyl molecular pliers. A lipid matrix at the air-water interface promotes the formation of quasi-stable nanocrystals, in which binaphthyl molecules have an open transoid configuration. The crystallization/dissolution of quasi-stable binaphthyl crystals with accompanying conformational change is reversible and repeatable.

Hydrophobized plant polyphenols: self-assembly and promising antibacterial, adhesive, and anticorrosion coatings.

Hydrophobized plant polyphenols can be easily prepared by rational and controlled etherification of highly abundant aromatic hydroxyls with linear alkyl chains. The resultant organo-soluble polyphenols spontaneously formed fibrous structures and unravelled to be potential adhesive, anticorrosion, and antibacterial coatings.

Hydrophilic polymer nanofibre networks for rapid removal of aromatic compounds from water.

Hydrophobic mesoporous polymer nanofibre networks were converted to hydrophilic ones by a mild sulfonation reaction. The resultant mesoporous polystyrene with a large free surface area effectively captured water-soluble dye molecules and allowed aromatic compounds to rapidly permeate into the internal binding sites.

Flash freezing route to mesoporous polymer nanofibre networks.

There are increasing requirements worldwide for advanced separation materials with applications in environmental protection processes. Various mesoporous polymeric materials have been developed and they are considered as potential candidates. It is still challenging, however, to develop economically viable and durable separation materials from low-cost, mass-produced materials. Here we report the fabrication of a nanofibrous network structure from common polymers, based on a microphase separation technique from frozen polymer solutions. The resulting polymer nanofibre networks exhibit large free surface areas, exceeding 300 m(2) g(-1), as well as small pore radii as low as 1.9 nm. These mesoporous polymer materials are able to rapidly adsorb and desorb a large amount of carbon dioxide and are also capable of condensing organic vapours. Furthermore, the nanofibres made of engineering plastics with high glass transition temperatures over 200 °C exhibit surprisingly high, temperature-dependent adsorption of organic solvents from aqueous solution.

Effect of Long Range Interactions on the Glass Transition Temperature of Thin Polystyrene Films.

The glass transition temperature (Tg) of thin polystyrene (PS) films supported on silicon wafers with oxide layers of varying thickness was characterized by the temperature dependence of the film thickness using ellipsometry. This allowed us to uncover how a long-range interaction affects the Tg of polymer films. As previously reported using a variety of methods, the Tg decreased with decreasing film thickness. However, the extent was not the same among the reports. In this study, we found that the Tg attenuation of a PS film of a given thickness was dependent on the oxide layer thickness of the silicon wafer via the long-range interaction.

Glass transition dynamics and surface layer mobility in unentangled polystyrene films.

Most polymers solidify into a glassy amorphous state, accompanied by a rapid increase in the viscosity when cooled below the glass transition temperature (T(g)). There is an ongoing debate on whether the T(g) changes with decreasing polymer film thickness and on the origin of the changes. We measured the viscosity of unentangled, short-chain polystyrene films on silicon at different temperatures and found that the transition temperature for the viscosity decreases with decreasing film thickness, consistent with the changes in the T(g) of the films observed before. By applying the hydrodynamic equations to the films, the data can be explained by the presence of a highly mobile surface liquid layer, which follows an Arrhenius dynamic and is able to dominate the flow in the thinnest films studied.

[MBL quality control survey of autoantibodies--25 years of activity and its achievement--mainly antinuclear antibodies].

Annual MBL Quality Control Survey of Autoantibodies has continued to this day since it started in 1983 as the only quality control survey of autoantibodies in Japan. The survey has aimed at unification and standardization of measurement value, as well as finding out between-laboratory differences in results through reporting the results of tabulation to the participating laboratories. For carrying out the survey, we intend to make our efforts to promote assurance and standardization of the quality control of the autoantibodies. The number of participant on this survey has been increasing every year and more than 500 laboratories participate not only in Japan but also from Asia and European countries. The laboratories that participated in this survey are the ones that usually perform ANA test, anti-DNA antibodies test, anti-ENA antibodies test, AMA test, ASMA test, anti-cardiolipin antibodies test and anti-CCP antibodies test. The purpose of the survey is to standardize antinuclear antibodies testing value in semi quantitative assay using ANA control serum or our titer control HEPASERA-1. We got 12% increase from 79% to 91% in 1986 using ANA control serum. Additionally, we reached 97% (86% to 97%) of convergence in 2001 by using HEPASERA-1, which contains 4 major pattern titer controls from 1993. In 2007, coefficient of variation (CV) for anti-dsDNA antibodies was 13%, showing better result than 25% of the first survey in 1993. We started secondary survey for laboratories which reported a result far apart. In the secondary survey, we made investigation for cause and improvement action. We conclude quality control survey is useful for autoantibodies testing for its result convergence.

Relaxation behavior of poly(methyl methacrylate) at a water interface.

The relaxation behavior of poly(methyl methacrylate) (PMMA), spin-coated on a silicon wafer, at the water interface was examined by lateral force microscopy as a function of temperature and scanning rate. Even in water, the lateral force peak which was assigned to the segmental motion of PMMA plasticized by water molecules was clearly observed in the temperature domain. The apparent activation energy for the plasticized alpha(a)-relaxation process was much smaller than those for the original alpha(a)-relaxation processes at the intact surface and in the bulk. The depth profile of the glass transition temperature (T(g)) of the PMMA film in water was obtained, showing that T(g) decreases with proximity to the water phase. The T(g) depression observed here was best explained in terms of the water content of the film, rather than a confinement effect.

Interfacial width in polymer bilayer films prepared by double-spin-coating and flotation methods.

A spin-coating method with the aid of selective solvents has been used to construct multilayer structures for organic devices under the assumption that the solvents do not invade a preformed structure. To confirm the assumption, we examined the interfacial width (lambda(i)) of model polymer bilayers, composed of polystyrene and perdeuterated poly(methyl methacrylate), prepared by spin-coating and flotation methods. Neutron reflectivity measurements revealed that the lambda(i) value was larger for the spin-coating method than for the flotation method. These results cast doubt on the validity of the assumption. This knowledge should be kept in mind when this method is applied to construct multilayer structures.

Nonsolvents cause swelling at the interface with poly(methyl methacrylate) films.

Density profiles of a perdeuterated poly(methyl methacrylate) (dPMMA) film spin-coated on a substrate in water, hexane, and methanol, which are "nonsolvents" for dPMMA, were examined along the direction normal to the interface by specular neutron reflectivity (NR). The interfaces of dPMMA with the liquids were diffuse in comparison with the pristine interface with air; the interfacial width with water was thicker than that with hexane. Interestingly, in water, the dPMMA film was composed of a swollen layer and the interior region, which also contained water, in addition to the diffused layer. The interface of dPMMA with hexane was sharper than that with water. Although there were slight indications of a swollen layer for the dPMMA in hexane, the solvent molecules did not penetrate significantly into the film. On the other hand, in methanol, the whole region of the dPMMA film was strikingly swollen. To conserve mass, the swelling of the film by the nonsolvents is accompanied by an increase in the film thickness. The change in the film thickness estimated by NR was in excellent accord with the results of direct observations using atomic force microscopy (AFM). The modulus of dPMMA in the vicinity of the interfaces with liquids was also examined on the basis of force-distance curves measured by AFM. The modulus decreased closer to the outermost region of the film. The extent to which the modulus decreased in the interfacial region was consistent with the amount of liquid sorbed into the film.