5MeV electron beam facilities in Japan

There are 3 facilities with 5MeV electron beam processing machines in Japan and another one is planned to start operation in 1998. 2 of them are installed by Nissin-High Voltage and the other are by Sumitomo Heavy/Radiation Dynamics. In this report are introduced 2 facilities which we have installed and are operating satisfactorily. The first one was: installed at Radia Industry for irradiation services and the second one for in-house use in a factory of a pharmaceutical plastic container manufacturer, Shinko Chemical. And the second one is available for contract irradiation. The machine in Radia Industry has a comprehensive conveyor system with a turn-over equipment to shoot from the top and the bottom of materials with e-beam and X-ray, and has been successfully operated for many years. The machine in Shinko Chemical is equipped with a unique conveyor system with two conveyor lines under the beam window and the motion of the lines are opposite each other. This conveyor system also has a turn-over equipment like other machines but the direction of turning-over is designed to give the irradiated materials more uniform dose.     

Light activated patterning of dye-labeled molecules on surfaces

This Communication describes a novel method for patterning proteins, ligands, or other organic/inorganic species onto solid substrates. The process works by linking the moiety of interest to a fluorophore that can be subsequently photobleached and bound to the interface. The technique can be performed in aqueous solution and allows several species to be addressed onto the surface simultaneously by using different frequencies of light. Because the method can be used with fluorophores excited by visible light, shorter and more damaging wavelengths can be avoided.     

Enhancing the information content of vibrational spectra through sample perturbation

Infrared and Raman band frequencies, intensities and line shapes are often sensitive to the local molecular environment determined by molecular conformation, surrounding matrix, temperature, pressure, etc. The variety of local environments experienced by a condensed-phase molecule can lead to vibrational spectra with broad bands containing many overlapped spectral features. The spectral resolution of these overlapped features can be enhanced by making perturbations to the sample environment. Examples of perturbations which can be applied to the sample to enhance the information content of infrared spectra are changes in temperature, concentration and mechanical strain. In each instance, the spectra obtained as a function of the perturbation can be cross-correlated to produce a two-dimensional correlation map defined by two independent wavenumber axes. in this representation, infrared bands which respond to the perturbation in a similar or different manner can be clearly identified. This information can be used to help resolve overlapped bands and make unambiguous band assignments.     

Biocompatibility of nanofilm-encapsulated silicone and silicone-hydrogel contact lenses

A material placed in or in contact with a biological system, that causes the minimum perturbation that can be tolerated by the host biological system, can be considered to be biocompatible. The major effects caused by a contact lens can be considered to be 1) the blocking of the natural supply of oxygen to the epithelium cells of the cornea, 2) interference with the normal evaporation of water from the tear fluid layer, and 3) hindrance of the normal functions of blinking for replenishing oxygen-saturated tear fluid and removing dead epithelium cells, which result from apoptosis. The encapsulation of a highly oxygen-permeable contact lens by a nanofilm with an imperturbable surface state minimizes all these terms. The encapsulated contact lens can be worn safely in extended wear.     

Polymers Containing Lactone Groups

Polymers containing intact lactone groups are a new class of macromolecules with reactive groups, which are relatively easy to obtain by polymerization, polycondensation and polyaddition, as well as by reactions on existing macromolecules. Polymers with β-lactone Groups in particular can enter into numerous addition reactions, which can be used, for example, to obtain macromolecules containing hydroxy acid or amino acid groupings. The reactions proceed under mild conditions, and can even be carried out in aqueous media, frequently giving water-soluble polymers. The polymers can be cross-linked at low temperatures, even from the aqueous phase, by the addition of bifunctional or oligofunctional reagents. Polymers containing β-lactone groups can also be used as a basis for graft co-polymers; polyester or polyether branches can be grafted on, depending on whether monomeric lactones or monomeric epoxides are used.     

A targeted reweighting method for accelerating the exploration of high-dimensional configuration space

Time scales available to biomolecular simulations are limited by barriers among states in a high-dimensional configuration space. If equilibrium averages are to be computed, methods that accelerate barrier passage can be carried out by non-Boltzmann sampling. Barriers can be reduced by modifying the potential-energy function and running dynamics on the modified surface. The Boltzmann average can be restored by reweighting each point along the trajectory. We introduce a targeted reweighting scheme where some barriers are reduced, while others are not modified. If only equilibrium properties are desired, trajectories in configuration space can be generated by Langevin dynamics. Once past a transient time, these trajectories guarantee equilibrium sampling when reweighted. A relatively high-order stochastic integration method can be used to generate trajectories. The targeted reweighting scheme is illustrated by a series of double-well models with varying degrees of freedom and shown to be a very efficient method to provide the correct equilibrium distributions, in comparison with analytic results. The scheme is applied to a protein model consisting of a chain of connected beads characterized by dihedral angles and the van der Waals interactions among the beads. We investigate the sampling of configuration space for a model of a helix-turn-helix motif. The targeted reweighting is found to be essential to permit the original all-helical conformation to bend and generate turn structures while still maintaining the alpha-helical segments.     

A method for the determination of technetium in environmental waters

A method is described which can be used to determine technetium-99 levels in a range of water types. Ruthenium isotopes which may interfere in the analysis are removed from the sample by precipitation before concentration of pertechnetate onto an ion-exchange column. Other nuclides can be removed from the column using NaOH before elution of the technetium using NaSCN. The technetium in the NaSCN eluent can then be extracted into butan-2-one which can be evaporated onto a planchette. Technetium-99m is used as a yield tracer and after this has decayed away to negligible levles the amount of technetium on the planchette can be determined by measuring the rate of beta radiation emission from the final concentrate.     

Alkyl Chain Introduction: In Situ Solar‐Renewable Colorful Organic Mechanoluminescence Materials

Mechanoluminescence (ML) materials are environmentally friendly and emit light by utilizing mechanical energy. This has been utilized in light sources, displays, bioimaging, and advanced sensors. Organic ML materials are strongly limited to application by in situ unrepeatable ML. Now, in situ solar‐renewable organic ML materials can be formed by introducing a soft alkyl chain into an ML unit. For the first time, the ML from these polycrystalline thin films can be iteratively produced by simply recrystallizing the fractured crystal in situ after a contactless exposure to sunlight within a short time (≤60 s). Additionally, their ML color and lifetime can be also easily tuned by doping with organic luminescent dyes. Therefore, large‐area sandwich‐type organic ML devices can be fabricated, which can be repeatedly used in a colorful piezo‐display, visual handwriting monitor, and sensitive optical sensor, showing a lowest pressure threshold for ML of about 5 kPa.     

Polymer-induced recovery of nanoparticles from microemulsions

A new isothermal approach to the recovery of inorganic nanoparticles (NPs) is demonstrated. The NPs can be incorporated into a background microemulsion (ME) supporting fluid, and they can be recovered by addition of non-adsorbing polymer. A clean liquid-liquid (L-L) phase transition can be readily induced by addition of polymer to the MEs. Furthermore, the L-L transitions are also observed in the presence of added NPs, but now the nanoparticles concentrate in the lower co-existing ME phases. Once recovered, the NPs can be redispersed by adding extra ME as a solvent.     

Field-free molecular alignment control by phase-shaped femtosecond laser pulse

In this paper, we theoretically show that the field-free molecular alignment can be controlled by shaping the femtosecond laser pulse with a periodic phase step modulation, involving the maximum degree and temporal structure of the molecular alignment. We show that the molecular alignment can be completely suppressed or reconstructed as that by the transform-limited laser pulse, the temporal structure of the alignment transient can be controlled with a desired shape, and the molecular alignment and antialignment for any temporal structure can be switched. Furthermore, we also show that both the degree and direction of the molecular alignment at a fix time delay can be continuously modulated.     

A Novel Liquid-Gel Chromatographic Method for Extraction of Unconjugated Steroids from Aqueous Solutions

Abstract

Unconjugated steroids of low and medium polarity can be essentially quantitatively extracted from aqueous solutions by rapid filtration through a small column of Lipidex 1000. Forty ml of urine can be extracted by a 4 ml column bed at a flow rate of 5 ml/ min. Less polar steroids (progesterone, testosterone) can be extracted directly, whereas 5% pentylamine has to be added to the aqueous solution to give a quantitative extraction of cortisol. The same method can be used for extraction of steroids in plasma. It is suggested that this method may be generally applicable to the extraction from biological fluids of compounds with a polarity similar to or lower than that of steroids.     

Controlling and characterizing the coagulation of liquid aerosol droplets

We demonstrate that optical tweezers can be used to control and characterize the coagulation and mixing state of aerosols. Liquid aerosol droplets of 2-14 mum in diameter are optically trapped and characterized by spontaneous and stimulated Raman scatterings, which together provide a unique signature of droplet size and composition. From the conventional bright field image, the size of the trapped droplet can be estimated and compared with that determined from stimulated Raman scattering, and the motion of the particle within the trapping plane can be recorded. A maximum of four droplets can be manipulated in tandem by forming multiple optical traps through rapid beam steering. The coagulation of two droplets can be studied directly by controlling two droplets. The limiting conditions under which optical forces and capillary forces dominate the aerosol coagulation event are explored by varying the relative optical trap strengths and characterizing the coagulation of different droplet sizes. Finally, we demonstrate that the coagulation of different aerosol components can be compared and the mixing state of the final coagulated droplet can be investigated. In particular, we compare the outcome of the coagulation of an aqueous sodium chloride aerosol droplet with a second aqueous droplet, with an ethanol droplet or with a decane droplet.     

Development and applications of time-of-flight neutron depth profiling (TOF-NDP)

Neutron depth profiling (NDP) is a surface analysis technique based on the irradiation of samples with thermal or sub-thermal neutrons, and subsequent release of charged particles. Emitted particles rapidly lose kinetic energy primarily through interactions with the electrons of the substrate material. The depth of the reaction site can be found by using stopping power correlations. In conventional NDP, particle residual energy is measured by using a silicon semiconductor detector. In time-of-flight NDP (TOF-NDP), the energy can be determined by particle flight time. Time measurement can be made more sensitively than the energy measurement. Silicon semiconductor detectors can be replaced by microchannel plates (MCP). In this study, TOF-NDP concept will be briefly explained; Penn State TOF-NDP facility will be introduced; preliminary measurements performed with an alpha-source will be presented.     

Classification of wheat varieties: use of two-dimensional gel electrophoresis for varieties that can not be classified by matrix assisted laser desorpiton/ionization-time of flight-mass spectrometry and an artificial neural network

Analyzing a gliadin extract by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) combined with an artificial neural network (ANN) is a suitable method for identification of wheat varieties. However, the ANN can not distinguish between all different wheat varieties. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was applied to three pairs of wheat varieties, which can not be classified correctly by ANN. By 2-D PAGE the varieties in the three pairs can be discriminated and these six wheat varieties can be separated from each other, which could not be separated by MALDI-TOF-MS and NN.     

Solid-supported biomimetic membranes with tailored lipopolymer tethers

Stable lipid membranes with controlled substrate-membrane spacing can be prepared using well-defined lipopolymers as a tether. Based on the living cationic ring-opening polymerization of 2-methyl- or 2-ethyl-2-oxazoline, lipopolymers can be synthesized bearing a lipid head group as well as a silanol reactive coupling end group. Using a “grafting onto” procedure these polymers can form dense, brush like monolayers, whose layered structures can be obtained by x-ray reflectivity measurements. By transfer of a pre-organized monolayer that is followed by vesicle fusion, stable polymer supported lipid membranes can be prepared. The substrate-membrane spacing can be controlled via the degree of polymerization, while the lateral diffusion of lipids within the membrane depends on the density of polymer tethers. Preliminary experiments implied that the membrane with long (N = 40) polymer tethers could reside trans-membrane receptors homogeneously, suggesting a large potential of this strategy.     

Derivative spectrophotometric determination of mercury(II) with pan in the aqueous phase

The Hg-PAN complex can be made soluble in water by addition of surfactant, and this can be made the basis of a spectrophotometric determination of Hg at ppm level. The selectivity and sensitivity can be improved by use of derivative spectrometry. The method has been applied to mercury-containing pesticides.     

Photo-attaching functional polymers to cellulose fibers for the design of chemically modified paper

We introduce a novel approach for preparing polymer-modified and chemically microstructured paper substrates by a photo-chemical attachment of functional polymers to cellulose microfibers inside model filter papers. Poly(methyl methacrylate), PMMA copolymers, which carry a defined amount of photo-reactive benzophenone functional groups, are adsorbed to paper substrates from solution by a simple dip coating process, followed by covalent attachment of the physisorbed polymers through UV-light irradiation. Non-bound macromolecules can be removed from paper sheets by simple solvent extraction, and the resulting polymer-modified substrates were analysed with respect to chemical identity, attached polymer mass, and homogeneity of the polymer attachment. The amount of paper-attached polymers can be conveniently controlled in a wide range from a few mg/g cellulose fiber up to several tenth of mg/g cellulose fiber, by adjusting the polymer concentration in the coating solution. Polymers are being attached by photo-chemical means, and chemical micro patterns on paper can be designed by lithographical means. In first proof-of-concept studies, millimeter-scale channels were prepared that can be used to control fluid penetration by capillary actions. Because of the modularity in the design of photo-reactive polymers, a number of different chemically microstructured papers can be envisioned which may become potentially interesting in lab-on-paper devices.     

Biochemical reaction engineering for redox reactions

Redox reactions are still a challenge for biochemical engineers. A personal view for the development of this field is given. Cofactor regeneration was an obstacle for quite some time. The first technical breakthrough was achieved with the system formate/formate dehydrogenase for the regeneration of NADH2. In cases where the same enzyme could be used for chiral reduction as well as for cofactor regeneration, isopropanol as a hydrogen source proved to be beneficial. The coproduct (acetone) can be removed by pervaporation. Whole-cell reductions (often yeast reductions) can also be used. By proper biochemical reaction engineering, it is possible to apply these systems in a continuous way. By cloning a formate dehydrogenase and an oxidoreductase "designer bug" can be obtained where formate is used instead of glucose as the hydrogen source. Complex sequences of redox reactions can be established by pathway engineering with a focus on gene overexpression or with a focus on establishing non-natural pathways. The success of pathway engineering can be controlled by measuring cytosolic metabolite concentrations. The optimal exploitation of such systems calls for the integrated cooperation of classical and molecular biochemical engineering.     

简便荧光法测定Fenton反应产生的羟自由基

简便荧光法测定Fenton反应产生的羟自由基;芬顿反应;羟自由基;亮绿SF;荧光光度法     

Separation of different forms of transferrin by isoelectric focusing to detect effects on the liver caused by xenobiotics

Several genetic variants and also isoforms of transferrin differing in carbohydrate structure can be separated by polyacrylamide or agarose gel isoelectric focusing. Numerous blood plasma or serum samples can be analyzed in parallel in each gel. Studies of the heterogeneity of transferrin have already revealed many results of importance to different fields of human medicine. Gene typing can give important and useful information for paternity determination and in forensic medicine. The gene type C 2 seems to have increased frequency in certain malfunctions. Futhermore, functional abnormalities of liver cells can be revealed by determination of the concentrations of transferrin isoforms differing mainly in their carbohydrate parts. The isoforms can be quantified with zone immunoelectrophoresis assay. Thus valuable information can be obtained about important modulated regulations of cell and membrane functions, even when these are disturbed by disease and xenobiotics. The information may be useful e.g. in the detection of individuals suffering from toxic effects, to identify toxic agents and exposure conditions. Studies of house painters revealed that exposure to different types of paints had an effect on transferrin. Determination of the concentration of the isotransferrin with pI 5.7 in blood samples from alcoholics can be used as a marker for the detection of liver dysfunction and for the monitoring of therapy treatments. In addition, by analyzing the isotransferrins a rare genetic abnormality can be detected.