Direct Observation of the Relationship between Thixotropic Behavior and Shear-Induced Orientation of Clay Particles in Synesthetic Hectorite Suspensions.

A thixotropic characteristics of aqueous gels containing smectite clay minerals were used in various industrial applications such as paint additives, which have been affected by the clay types and clay particle sizes. A model called a house-of-card arrangement of clay particles and anisotropic arrangement in aqueous gels has been proposed. We prepared different sizes of synthetic hectorite and studied them by scanning electron-assisted dielectric microscopy (SE-ADM) and simultaneous small-angle neutron scattering and rheological measurements (Rheo-SANS).

Energy redistribution and spatiotemporal evolution of correlations after a sudden quench of the Bose-Hubbard model.

An optical lattice quantum simulator is an ideal experimental platform to investigate nonequilibrium dynamics of a quantum many-body system, which is, in general, hard to simulate with classical computers. Here, we use our quantum simulator of the Bose-Hubbard model to study dynamics far from equilibrium after a quantum quench. We successfully confirm the energy conservation law in the one- and three-dimensional systems and extract the propagation velocity of the single-particle correlation in the one- and two-dimensional systems.

Novel Flexible Supramolecular Assembly of Dioleyldimethylammonium Ion in a Two-Dimensional Nanospace Studied by Neutron Scattering.

Dioleyldimethylammonium ion was used to construct two-dimensional hybrid structures with clay and the hybrid was shown to possess higher flexibility than that of the hybrid of dioctadecyldimethylammonium and the clay. The important difference between the two surfactant systems was studied by quasi-elastic neutron scattering, confirming the useful characteristics of the presently designed dioleyldimethylammonium-clay over the well-known dioctadecyldimethylammonium-clay for various materials applications.

Effects of amine, amine salt and amide on the behaviour of carbon dioxide absorption into calcium hydroxide suspension to precipitate calcium carbonate.

The amount of carbon dioxide (CO2) absorption and calcium ion (Ca2+) concentration besides the pH of aqueous solution were observed during the CO2 absorption to precipitate calcium carbonate (CaCO3) from calcium hydroxide (Ca(OH)2). A reaction rate-limiting effect of an amount of CO2 absorption without any organic additives in the early stage of the precipitation was observed, which was attributed to an interruption effect of bicarbonate ion (HCO3(-)) on the precipitation of CaCO3. The improvement for the reaction rate was achieved not only by amine additives but also by neutral additives such as epsilon-caprolactam or amine salt.

Photoinduced electron transfer between the anionic porphyrins and viologens in titania nanosheets and monodisperse mesoporous silica hybrid films.

Photoinduced electron transfer between an anionic porphyrin derivative (tetrakis(p-carboxyphenyl)porphyrin; H(2)TCPP(4-)) and an electron accepting methyl viologen (MV(2+)) was investigated in two different nanoscale configurations, i.e., layered titania nanosheet (TNS) photocatalysts and ammonium-functionalized monodisperse mesoporous silica (AMMSS) particles.

Photosynthetic oxygen evolution in mesoporous silica material: adsorption of photosystem II reaction center complex into 23 nm nanopores in SBA.

An oxygen-evolving photosynthetic reaction center complex (PSII) was adsorbed into nanopores in SBA, a mesoporous silica compound. We purified the dimer of PSII complex from a thermophilic cyanobacterium, Thermosynechococcus vulcanus, which grows optimally at 57 °C. The thermally stable PSII dimeric complex has a diameter of 20 nm and a molecular mass of 756 kDa and binds more than 60 chlorophylls.

Photosynthetic electron transfer from reaction center pigment-protein complex in silica nanopores.

A photosynthetic reaction center (RC) pigment-protein complex purified from a thermophilic purple photosynthetic bacterium, Thermochromatium tepidum, was adsorbed to a folded-sheet silica mesoporous material (FSM). The RC has a molecular structure with a 7.0 x 5.

Photo-induced electron migrations in the nano-cavities of mesoporous silica sensitized by a cationic porphyrin dye.

Photo-induced redox reactions in a hybrid film of a cationic porphyrin dye (H2TMPyP) accommodated within a transparent mesoporous silica (MPS) film spin-coated on an FTO electrode have been investigated for such applications as the construction of efficient solar energy storage devices and novel light-stimulated sensors. In this system, anodic and cathodic photocurrents were observed under bias voltages of +0.3 V and -0.

Superfluidity of 4He in one and three dimensions realized in nanopores.

Superfluidity in one and three dimensions has been studied for 4He fluid films adsorbed in nanopores which are straight channels and three-dimensionally connected pores, respectively. We observed the superfluid in one and three dimensions where thermal phonon wavelengths are much longer than the channel diameter and the period of the pore connection, respectively, and found that the superfluid onset depends on the pore connection. In the straight channels, the observed superfluid density disappears at a temperature far below the heat capacity anomaly of the Ginzburg-Landau transition, while in the pores connected in three dimension, the adsorbed 4He films show an evident three-dimensional transition where the superfluid onset occurs at the heat capacity peak.

Effective immobilization of subunit protein in mesoporous silica modified with ethanol.

Ethoxylated FSM-type mesoporous silica (folded-sheet mesoporous material) with a pore diameter of 6.2 nm (FSM6.2) remarkably enhances rigidly of the structure in aqueous solutions.

Function of membrane protein in silica nanopores: incorporation of photosynthetic light-harvesting protein LH2 into FSM.

A high amount of functional membrane protein complex was introduced into a folded-sheet silica mesoporous material (FSM) that has nanometer-size pores of honeycomb-like hexagonal cylindrical structure inside. The photosynthetic light-harvesting complex LH2, which is a typical membrane protein, has a cylindrical structure of 7.3 nm diameter and contains 27 bacteriochlorophyll a and nine carotenoid molecules.

Encapsulation of myoglobin with a mesoporous silicate results in new capabilities.

A metmyoglobin (Fe3+), an oxidized form of myoglobin (Fe2+), was confined in nanospaces of about 4 nm in diameter in mesoporous silica (FSM; folded-sheet mesoporous material), forming a metmyoglobin (Fe3+)-FSM nanoconjugate. The spectral characteristics of metmyoglobin (Fe3+)- and myoglobin (Fe2+)-FSM show an absorption curve quite similar to that of native metmyoglobin, indicating that myoglobin retains its higher-order structure in the pores of FSM. The metmyoglobin (Fe3+)-FSM conjugate had not only a peroxidase-like activity in the presence of hydrogen peroxide (a hydrogen acceptor) and 2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfomic acid (ABTS) or guaiacol (a hydrogen donor) but also an advanced molecular recognition ability enabling it to distinguish between ABTS and guaiacol.

Phytol-modified heme in mesoporous silica: conjugates as models of hemoproteins.

A ferriprotoporphyrin, hemin (Fe(3+)), modified with 3,7,11,15-tetramethyl-2-hexadecen-1-ol, phytol, was adsorbed in nano-spaces of about 4 nm in diameter in mesoporous silica (FSM; folded-sheet mesoporous material) forming a phytol-modified hemin (Fe(3+))-FSM nano-conjugate. The properties and the structure of the conjugate were studied by UV-visible light absorption, IR absorption spectroscopy, and a nitrogen adsorption isotherm. Although the hemin without phytol could not be adsorbed to the mesoporous silica, modification with phytol imparted preferential adsorption properties.

Possible one-dimensional 3He quantum fluid formed in nanopores.

Heat capacity measurements have been made down to 5 mK for 3He fluid films adsorbed in one-dimensional (1D) nanometer-scale pores, 28 A in diameter, preplated with 4He of 1.47 atomic layers. At low 3He density, the heat capacity shows a density-dependent, Schottky-like peak near 150 mK asymptoting to the value corresponding to a 2D Boltzmann gas at high temperatures.

Photoinduced one-electron reduction of MV2+ in titania nanosheets using porphyrin in mesoporous silica thin films.

Composite films of a meso-(tetramethylpyridinium)porphyrin (TMPyP) hybrid incorporated in mesoporous silica (MPS) and cast on a methyl viologen (MV2+)/titania nanosheet hybrid were synthesized and a light-induced charge separation between the two could be observed. These composite thin films were able to initiate a one-electron reduction of the MV2+ ions accompanied by the simultaneous decomposition of the TMPyP organic dye within the mesoporous silica channels.

Photostabilized chlorophyll a in mesoporous silica: adsorption properties and photoreduction activity of chlorophyll a.

Chlorophyll a was adsorbed to mesoporous silica (FSM, folded-sheet mesoporous material) to form a chlorophyll-FSM conjugate, in which a nanometer-scale interaction between chlorophyll a molecules resembles a living plant leaf. The mesopores of FSM acted as nanoscale spaces not only for an interaction between chlorophyll molecules and the silica support but also for a nanoscale interaction between the absorbed chlorophyll molecules. These interactions contribute to photostability.