Synchrotron structure determination of an α‐Keggin doubly PtIV‐substituted silicotungstate, (CH6N3)8[α‐SiPt2W10O40]·6H2O

The crystal structure of octaguanidinium α‐silicodiplatino­decatungstate hexahydrate, (CH₆N₃)₈[α‐SiPt₂W₁₀O₄₀]·6H₂O, has been analyzed via a high‐energy X‐ray diffraction experiment at the SPring‐8 BL04B2 beamline. The title compound contains a novel α‐Keggin heteropolyanion in which two of the addenda atoms are replaced by Pt atoms. W and Pt atoms occupy the same coordinates; the occupancy fractions are (W) and (Pt), and the α‐Keggin anion has symmetry. The two types of W(Pt)—W(Pt) distance are in the ranges 3.3565 (4)–3.3704 (4) and 3.7033 (4)–3.7100 (4) Å, the four types of W(Pt)—O bond length are in the ranges 1.721 (5)–1.725 (5), 1.910 (5)–1.932 (5), 1.934 (5)–1.956 (5) and 2.339 (4)–2.348 (4) Å, and the Si—O bond length is 1.646 (4) Å.     

Ir3Co6 and Co3Fe3 dithiolene cluster complexes: multiple metal-metal bond formation and correlation between structure and internuclear electronic communication

π-Conjugated trinuclear iridium and cobalt dithiolenes undergo multiple metal-metal bond formation with Co(2)(CO)(8) and Fe(CO)(5), giving rise to Ir(3)Co(6) nonanuclear and Co(3)Fe(3) hexanuclear cluster complexes 5 and 6, respectively. 5 retains a planar framework and intense π conjugation across the three iridadithiolenes and the phenylene bridge, which results in intense electronic communication among the three Co(2)(CO)(5) units in reduced mixed-valent states.     

Electrical detection of single pollen allergen particles using electrode-embedded microchannels

We report on the development of a microfluidic system for the electrical detection of single pollen allergen particles. Our device consists of 500 nm electrode gaps fabricated in an 800 nm wide fluidic channel. We flowed pollen allergen particles of average size 330 nm along the channel via fluid pumping and simultaneously monitored temporal change in dc current flowing through the sensing electrodes. Current spikes were detected, which can be attributed to a capacitance discharging upon trapping/detrapping of single allergens in the electrode gap. This sensing mechanism may open new avenues for a highly sensitive pollen allergen sensor.     

Direct nanopatterning of silsesquioxane/poly(ethylene glycol) blends with high stability and nonfouling properties

A free‐radical‐polymerizable SSQ/PEG blend with direct patternability has been proposed as an ideal nonfouling material for nanostructure‐based biomedical applications. Cured SSQ/PEG networks show an UV transparency of >90% at 365 nm, high resistance to organic/aqueous solutions, hydrophilicity and Young's moduli of 1.898–2.815 GPa. SSQ/PEG patterns with 25‐nm linewidths, 25‐nm spacing, and an aspect ratio of 4:1 were directly fabricated on transparent substrates by UV embossing, and cured SSQ/PEG networks with long‐term stability under chemical, thermal, and biological stress showed strong resistance to the nonspecific adsorption of biomolecules. These characteristics may offer a new strategy for the development of a number of medical nanodevice applications such as labs‐on‐a‐chip.

     

Characteristics of developing vertical bubbly flow under normal and microgravity conditions

The axial development of the void fraction profile, interfacial area concentration and Sauter mean bubble diameter of adiabatic nitrogen-water bubbly flows in a 9 mm-diameter pipe were measured using stereo image processing under normal and microgravity conditions. The flow measurements were performed at four axial locations (axial distance from the inlet, z normalized by the pipe diameter, D, z/D = 5, 20, 40 and 60) and with various flows: superficial gas velocity of 0.00840-0.0298 m/s, and superficial liquid velocity of 0.138-0.914 m/s. The effect of gravity on radial distribution of bubbles and the axial development of two-phase flow parameters is discussed in detail based on the obtained database and visual observation. Following Serizawa-Kataoka’s phase distribution pattern criteria under normal gravity conditions, the phase distribution pattern map was developed. Similar to normal gravity two-phase flows, wall, core and intermediate void peak patterns are observed under microgravity conditions but a transition void distribution pattern is not observed in the current experimental conditions. The data obtained in the current experiment are expected to contribute to the benchmarking of CFD simulation of phase distribution pattern and interfacial area concentration in forced convective pipe flow under microgravity conditions.     

Photocontrol of magnetization in Al-substituted Fe3O4 thin films

Thin films of (111)-oriented spinel ferrite Al_0.5Fe_2.5O₄ have been prepared by a pulsed-laser deposition (PLD) technique on α-Al₂O₃ (0001) substrates. The films exhibit cluster-glass behaviors with a spin-freezing temperature, T_g, near or above room temperature. The magnetization was found to increase following light irradiation below T_g, which indicates the photoinduced melting of cluster-glass states. An analysis comparing the dynamic behavior of magnetic response to light irradiation between zero-field-cooled (ZFC) states and field-cooled (FC) states at 10 K under various light intensities, I, revealed that the direct photoexcitation of spins occurs when I≤0.78 mW/mm², while the thermal heating effect following the light absorption of the samples also contributes to the enhancement of magnetization when I≥1.22 mW/mm². The magnetization of the films could be controlled by light irradiation even at room temperature. This suggests the possibility of utilizing these films in the development of novel magneto-optical memory devices.     

Self-organized interconnect method for molecular devices

Lack of an appropriate method for wiring molecules that have controlled functions and structures has been a barrier for the development of molecular devices. We developed an interconnect method to program three kinds of component molecules with their own functions and to wire a molecular device in a self-organized manner. By using the interconnect method we developed, we produced conductive wires and optical switching devices and have demonstrated their device functions. Our interconnect method allows us to control various molecular device characteristics by combining the three molecules.     

Single molecular observation of penta- and hexagonic assembly of bisporphyrin on a gold surface

Artificial light-harvesting antennae of coordination-organized macrocyclic porphyrin pentamer and hexamer are visualized by high resolution scanning tunneling microscopy (HRSTM) on a gold surface.