Mitsui Chemical Analysis and Consulting Service Inc.

Chiba, Japan

Mitsui Chemical Analysis and Consulting Service Inc.

Chiba, Japan
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Kametani S.,Tokyo University of Agriculture and Technology | Kametani S.,Mitsui Chemical Analysis and Consulting Service Inc. | Tasei Y.,Tokyo University of Agriculture and Technology | Nishimura A.,Tokyo University of Agriculture and Technology | Asakura T.,Tokyo University of Agriculture and Technology
Physical Chemistry Chemical Physics | Year: 2017

Polyalanine (polyA) sequences are well known as the simplest sequence that naturally forms anti-parallel β-sheets and constitute a key element in the structure of spider and wild silkworm silk fibers. We have carried out a systematic analysis of the packing of anti-parallel β-sheets for (Ala)n, n = 5, 6, 7 and 12, using primarily 13C solid-state NMR and MD simulation. HFIP and TFA are frequently used as the dope solvents for recombinant silks, and polyA was solidified from both HFIP and TFA solutions by drying. An analysis of Ala Cβ peaks in the 13C CP/MAS NMR spectra indicated that polyA from HFIP was mainly rectangular but polyA from TFA was mainly staggered. The transition from the rectangular to the staggered arrangement in (Ala)6 was observed for the first time from the change in the Ala Cβ peak through heat treatment at 200 °C for 4 h. The removal of the bound water was confirmed by thermal analysis. This transition could be reproduced by MD simulation of (Ala)6 molecules at 200 °C after removal of the bound water molecules. In this way, the origin of the stability of the different packing arrangements of polyA was clarified. © 2017 the Owner Societies.

Sasahara T.,Kitasato University | Mase H.,Materials Development, Inc. | Abe M.,Mitsui Chemical Analysis and Consulting Service Inc. | Abe M.,Kitasato University | Saito H.,Japan Copper Development Association
Acta Dermato-Venereologica | Year: 2013

Metallic copper has been shown signifcantly to reduce methicillin-resistant Staphylococcus aureus (MRSA) contamination of the ambient surroundings of the beds of MRSA-carrying patients in dermatology wards. The aim of this study was to determine whether a bed sheet made of copper-coated film will reduce the spread of MRSA contamination in the environment of a heavily-colonized patient. The bacterial count was highest on the bed sheet. MRSA cell counts on the surface of the non-film-coated control sheet were high (6,600-11,000 colony forming units (cfu)), but those on the copper film were considerably lower (20-130 cfu). Use of metallic copper on the bed sheets of patients who are likely to be a source of MRSA contamination may help to prevent the spread of MRSA contamination in hospital wards. © 2013 The Authors.

Asakura T.,Tokyo University of Agriculture and Technology | Asakura T.,Japan Institute for Molecular Science | Ohata T.,Tokyo University of Agriculture and Technology | Kametani S.,Mitsui Chemical Analysis and Consulting Service Inc. | And 9 more authors.
Macromolecules | Year: 2015

We have previously suggested that crystalline Bombyx mori silk in silk II form (the silk structure after spinning) is not a simple antiparallel β-sheet but is intrinsically heterogeneous. Using the peptide (AG)15, we have obtained the first fully assigned high resolution solid state 1H NMR spectrum. Distinct heterogeneity was observed, in both 1H and 13C CP/MAS signals. Based on these results, a new model is proposed that contains two different packing arrangements of antiparallel β-sheets. The structures were energetically minimized by CASTEP calculation and used to calculate the solid state 1H, 13C, and 15N NMR chemical shifts using the GIPAW method. This new model was supported by good agreement between the calculated and observed 1H, 13C, and 15N chemical shifts and relative 1H-1H proximities obtained from 2D 1H DQMAS experiments. We conclude that the intermolecular packing of B. mori silk fibroin has been finally resolved. © 2014 American Chemical Society.

Yokoyama K.,Yamaguchi University | Jinnai K.,Yamaguchi University | Jinnai K.,Kyowa Kako Co. | Sakiyama Y.,Yamaguchi University | And 2 more authors.
Applied Soil Ecology | Year: 2012

This study was conducted to analyze the relative contribution of nitrifying microbial groups in tea field soils with relatively neutral pH where high ammonia availability was expected after heavy fertilization. The nitrification potential in tea field soils supplied with organic fertilizers (OF) or chemical fertilizers (CF) was determined by the chlorate-inhibition method. The response of the potential to the net ammonia concentration, which was employed as an index of ammonia availability, was tested by loading various levels of ammonium sulfate to soil slurries. The potential of tolerance to 10Pa acetylene was highlighted. The acetylene-tolerant nitrification potential occurred all year at a significant level. It was stimulated by ammonia availability of more than 10-5.5molNH3L-1, where the nitrification potential determined under an acetylene-free condition (total potential) was affected negatively. As the test results show, the contribution of the acetylene-tolerant potential ranged from 2 to 38% with OF soils and from 8 to 67% with CF soils. These indicated a significant contribution of heterotrophic microorganisms to the nitrification potential of these neutral tea soils. The addition of cycloheximide rather than streptomycin remarkably suppressed the acetylene-tolerant nitrification potential, suggesting the primary contribution of fungi. A new aspect of heterotrophic nitrification was identified. © 2012 Elsevier B.V.

Kobayashi Y.,Division Prime | Kobayashi Y.,Kanazawa University | Kanno H.,Mitsui Chemical Analysis and Consulting Service Inc. | Hanamoto Y.,Mitsui Chemical Analysis and Consulting Service Inc. | And 3 more authors.
Journal of Applied Polymer Science | Year: 2010

The relationship between microhardness and morphology of polypropylene near the surface of injection molded plaques was investigated. Crystal structures and molecular orientation from the surface to shear oriented layer were characterized by microbeam synchrotron wide angle X-ray diffraction, polarizing optical microscope and Fourier transformed infrared spectroscopy. From precise measurements, using an X-ray beam with width of 0.35 lm, the frozen layer was divided into two layers. Molecular and crystal orientations changed greatly in the surface layer but remained constant in the inner layer. These oriented morphology did not affect microhardness along the depth direction on the cross-cut surface. Microhardness was proportional to crystallinity and showed a local maximum at shear oriented layer and a minimum at the surface. Then, positional dependence of microhardness was compared at the gate and the center of the plaque. Although crystallinity near the gate was lower than that at the center position, micro-hardness was higher. Therefore, crystallinity mainly affects microharness but superstructure like cross-hatching lamellae which is induced in biaxially extended melt flow is also not neglected in injection molded polypropylene parts. © 2010 Wiley Periodicals, Inc.

Watanabe E.,Tokyo University of Agriculture and Technology | Boutis G.S.,Brooklyn College | Sato H.,Mitsui Chemical Analysis and Consulting Service Inc. | Sekine S.,Mitsui Chemical Analysis and Consulting Service Inc. | Asakura T.,Tokyo University of Agriculture and Technology
Polymer (United Kingdom) | Year: 2014

The thermo-responsive behavior of a unique biocompatible polymer, poly(N-substituted α/β-asparagine) derivative (PAD), has been studied with several NMR methods. The 1H and 13C solution NMR measurements of the PAD in DMSO-d6 were used to investigate the isolated polymer and perform spectral assignments. By systematic addition of D2O we have tracked structural changes due to aggregation and observed contraction of hydrophilic side chains. Solution and cross polarization/magic angle spinning (CP/MAS) 13C NMR approaches were implemented to investigate the aggregates of the PAD aqueous solution during the liquid to gel transition as the temperature was increased. At temperatures near 20 C, all of the peaks from the PAD were observed in the 13C CP/MAS and 13C solution NMR spectra, indicating the presence of polymer chain nodes. Increasing the temperature to 40 C resulted in a partial disentanglement of the nodes due to thermal agitation and further heating resulted in little to no additional structural changes. Deuterium T 1-T2 and T2-T2 two-dimensional relaxation spectroscopies using an inverse Laplace transform, were also implemented to monitor the water-PAD interaction during the phase transition. At temperatures near 20 C the dynamical characteristics of water were manifested into one peak in the deuterium T1-T2 map. Increasing the temperature to 40 C resulted in several distinguishable reservoirs of water with different dynamical characteristics. The observation of several reservoirs of water at the temperature of gel formation at 40 C is consistent with a physical picture of a gel involving a network of interconnected polymer chains trapping a fluid. Further increase in temperature to 70 C resulted in two non-exchanging water reservoirs probed by deuterium T2-T2 measurements. © 2013 Elsevier Ltd. All rights reserved.

Kokufuta M.K.,Mitsui Chemical Analysis and Consulting Service Inc. | Sato S.,University of Tsukuba | Kokufuta E.,University of Tsukuba
Colloid and Polymer Science | Year: 2012

The lower critical solution temperature (LCST) behavior of copolymers of N-isopropylacrylamide (NiPA) and N-isopropylmethacrylamide (NiPMA) in water was studied as a function of the copolymer composition, using a combination of turbidity measurements and differential scanning calorimetry (DSC). The copolymers were prepared by free radical polymerization using N,N-dimethylformamide as a solvent and α,α′- azobis(isobutyronitrile) as an initiator. The copolymer composition was determined by elemental analysis. It was found that the temperature (T c) at which the copolymer undergoes a phase transition, i.e., LCST, increases linearly with increasing the mole fraction (f m) of NiPMA in the copolymer, within the T c range from 32 °C (at f m=0; NiPA homopolymer) to 42 °C (at f m=1; NiPMA homopolymer). Also found from heating DSC thermograms were the linear dependencies of the enthalpy (ΔH) and entropy (ΔS) changes at T c upon f m. However, the ΔH (5.5 kJ/unit-mol) at fm01 was slightly smaller than that (5.7 kJ/unit-mol) of poly(N-n-propylacrylamide) but considerably smaller than that (7.8 kJ/unit-mol) of poly(N-n- propylmethacrylamide). The same trend was observed in the f m dependence of ΔS. These results were discussed in terms of the structural effects of the NiPMA monomer unit on the heat-induced phase transition in water of poly(NiPA-co-NiPMA)s. It was suggested that a strong interaction of water with the amide group in the NiPMA would raise the transition temperature, but a local dehydration which occurs around the isopropyl side chain would not lead to large changes in the enthalpy and entropy at T c. © Springer-Verlag 2012.

Kokufuta E.,University of Tsukuba | Sato S.,University of Tsukuba | Kokufuta M.K.,Mitsui Chemical Analysis and Consulting Service Inc.
Langmuir | Year: 2013

Electrophoretic behavior was studied for N-isopropylacrylamide (NIPA) microgels, into which different amounts of poly(acrylic acid) (PAAc) were physically entrapped. Copolymer microgels of NIPA with acrylic acid (AAc) were also studied as a control. Electrophoretic mobility was measured in 0.1 M NaCl solution at 25 C as a function of pH, using an electrophoretic light scattering technique. The mobility of the copolymer microgel whose COOH groups are fully ionized agreed with that of PAAc when its ionization degree (α n) is close to the mole fraction (fAAc) of the AAc unit in the copolymer gel. There was good agreement between the mobility values of the copolymer microgel and the linear NIPA/AAc copolymer when their AAc contents are very close to each other. However, the mobility of the microgel with immobilized PAAc was higher than that of the copolymer microgel, even when there was no difference in the AAc content for both microgels. Moreover, the immobilized PAAc showed a higher mobility than the free PAAc when its αn is equal to fAAc in the immobilized system. No correlation was observed between the mobility and the hydrodynamic radius. These results were discussed in terms of the free draining model (FDM) for the electrophoresis of polyelectrolytes. It became apparent that the mobility difference depending upon whether (i) the PAAc ions are in the cage of the NIPA network or (ii) the AAc units are copolymerized with the network chain is due to the structural difference of the segments considered in the FDM. © 2013 American Chemical Society.

Jinnai H.,Kyushu University | Jinnai H.,Japan Science and Technology Agency | Tsuchiya T.,Mitsui Chemical Analysis and Consulting Service Inc. | Motoki S.,Tokyo Electron | And 5 more authors.
Journal of Electron Microscopy | Year: 2013

This review summarizes the recent advances in three-dimensional (3D) imaging techniques and their application to polymer nanostructures, for example, microphase-separated structures of block copolymers. We place particular emphasis on the method of transmission electron microtomography (electron tomography for short; hereafter abbreviated as ET). As a result of recent developments in ET, truly quantitative 3D images of polymer nanostructures can now be obtained with subnanometer resolution. The introduction of scanning optics in ET has made it possible to obtain large amounts of 3D data from micrometer-thick polymer specimens by using conventional electron microscopes at a relatively low accelerating voltage, 200 kV. Thus, ET covers structures over a wide range of thicknesses, from a few nanometers to several hundred nanometers, which corresponds to quite an important spatial range for hierarchical polymer nanostructures. ET provides clear 3D images and a wide range of new structural information that cannot be obtained using other methods. Information traditionally derived from conventional microscopy or scattering methods can be directly acquired from 3D volume data. ET is a versatile technique that is not restricted to only polymer applications; it can also be used as a powerful characterization tool in energy applications such as fuel cells. © 2012 The Author.

Kokufuta M.K.,Mitsui Chemical Analysis and Consulting Service Inc. | Sato S.,University of Tsukuba | Kokufuta E.,University of Tsukuba
Colloids and Surfaces B: Biointerfaces | Year: 2011

We synthesized the glutaraldehyde cross-linked hydrogels using four kinds of poly(lysine)s (PLs) and measured the equilibrium swelling ratio (Q) as a function of pH. Also measured was the temperature change of Q at a fixed pH (11.6) in the absence and presence of additives (LiBr, methanol and urea) that affect the secondary structure of PLs. The swelling data were examined using a force balance approach in which the repulsive and attractive interactions among the cross-linked PL chains were considered based on the conformational properties of PLs in aqueous solutions. It was found that the formation of the helical segments in the cross-linked chain has little effect in the gel collapse, but their association acts as the attractive interaction causing the gel to shrink. The formation of the beta-sheet structure within the network also acts as the attractive interaction. These attractive interactions are mainly due to the hydrogen bonding, but hydrophobic interactions between the lysine side chains should be considered. In addition, in the swelling behavior of all the PL gels the polyampholyte nature appears due to electrostatic interactions of the basic groups with the C-terminal carboxyl group. © 2011 Elsevier B.V.

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