Extended Nanofluidic Immunochemical Reaction with Femtoliter Sample Volumes

The growing need to optimize immunoassay performance driven by interest in analyzing individual cells has resulted in a decrease in the amount of sample required. Miniaturized immunoassays that use ultra‐small femtoliter to attoliter sample volumes, a range known as the extended nanospace, can satisfy this analytical need; however, capturing every targeted molecule without loss in extended nanochannels for subsequent detection remains challenging. This is the first report of a successful extended nanofluidics‐based quantitative immunochemical reaction capable of high capture efficiency using a femtoliter‐scale sample volume. A novel patterning method using a photolithographic technique with vacuum ultraviolet light and low‐temperature (100 °C) bonding enables patterning of functional groups for antibody immobilization before bonding, resulting in an immunochemical reaction space of only 86 fL. Reaction rate analyses indicate a decrease in the required sample volume to 810 fL and improvement in the limit of detection to 3 zmol, 5‐6 orders of magnitude better than possible with the microfluidic immunoassay format. Highly efficient (near 100%) immunochemical reactions on a seconds time scale are possible due to the nm‐scale diffusion length, which should be advantageous for the analysis of ultra‐low‐volume samples.     

Transition-Metal-Catalyzed Highly Regio- and Stereoselective Co-Polymerization of Dialkynylbenzene with Benzenedithiol Leading to Poly（Phenylene Vinylene Sulfide）

Co-polymerization of dialkynylbenzene with benzenedithiol proceeds regio- and stereoselectively in the presence of transition metal catalysts, affording the corresponding poly（phenylene vinylene sulfide） in good yield. In the presence of palladium acetate as catalyst, Markovnikov addition takes place selectively, whereas chlorotris（triphenylphosphine）rhodium-catalyzed reaction affords anti-Markovnikov adduct with excellent regio- and stereoselectivity.     

Physical Properties and Structure of Silica-Alumina-Europium Oxide Glasses

SiO₂–Al₂O3–Eu₂O₃ glasses were prepared for the composition 50siO₂·(50 – x )Al₂O_3·xEu₂O₃, and their density, sound velocity, and elastic modulus were measured. The chemical shift of the AIK a band emission spectra and the isomer shift of ¹⁵¹Eu by Mössbauer effect were obtained to determine the coordination states of Al³⁺ and Eu³⁺ ions in these glasses. It was found that the coordination number of Eu³⁺ ions was 12 and that the average coordination number of A1³⁺ ions was almost 5 in these glasses. By introducing Eu₂O₃, the packing of constituent ions was strongly enhanced and the elastic modulus increased in this system. The compositional dependence of the molar volume and elastic modulus were explained by these states of high coordination number for Eu³⁺ and low coordination number for Al³⁺ ions compared with those in the corresponding M₂O₃ crystals.     

Temperature phase-matching properties for harmonic generation in GdCa4O(BO3)3 and Gd(x)Y(1-x)Ca4O(BO3)3

GdCa4O(BO3)3 has been found to have phase-matching points where the temperature variations of the phase-matching angles become zero for type-1 sum-frequency generation in the zx plane. We also found that the temperature sensitivities of the phase-matching conditions in the zx plane are different along the phi = 0 degrees and phi = 180 degrees directions in this material. In addition, the thermo-optic dispersion formula of this material that reproduces the temperature phase-matching properties of GdCa4O(BO3)3 and Gd(x)Y(1-x)Ca4O(BO3)3 is presented.     

Ultraviolet Photoelectron Spectroscopy of Two Titanium Metal Atoms Encapsulated Metallofullerenes, Ti2@C80 and Ti2@C84

Ultraviolet photoelectron spectra (UPS) of Ti₂@C₈₀ (mixture of two isomers) and two Ti₂@C₈₄ isomers excited by synchrotron radiation light source are presented. The spectra of Ti₂@C₈₀ are complicated compared with those of other metallofullerenes, which is considered with an aid of molecular orbital (MO) calculation. The photoelectron spectra of two Ti₂@C₈₄ isomers are fairly analogous with each other and show less structure than that of Sc₂@C₈₄. This suggests that the symmetry of two isomers differs from D_2d symmetry of Sc₂@C₈₄.     

Ionizing radiation induced luminescence properties of Mn-doped LiCa(Al,Ga)F<Subscript>6</Subscript>

Optical, scintillation and dosimeter properties of Mn 0.3 and 10 mol% doped LiCaAlF₆ and Mn 10 % doped LiCaAl_0.9Ga_0.1F₆ crystals were studied. Mn²⁺ emission appeared around 520 nm in the photoluminescence, scintillation and optically stimulated luminescence (OSL). As a dosimeter, the OSL and thermally stimulated luminescence (TSL) dose response functions were evaluated, and both the OSL and TSL showed a good linearity between the irradiated X-ray dose and response signal intensity from 1 to 1000 mGy. Compared with previously reported Ce- or Eu-doped LiCaAlF₆, OSL properties were improved.     

Origin of Surface Coating Effect for MgO on LiCoO2 to Improve the Interfacial Reaction between Electrode and Electrolyte

Surface coating on lithium‐ion battery cathodes improves their durability at high potentials, which is a well‐known practical application. However, the mechanism is still unclear because the coating influences the electrode/electrolyte interface at a few nanometer‐scale and direct observation of the interface under real operating conditions of a battery is challenging. This study reveals the mechanism of the surface coating effect on lithium‐ion battery cathodes by using in operando X‐ray absorption spectroscopy (XAS) on well‐defined MgO‐coated LiCoO₂ thin‐film electrodes prepared via pulsed laser deposition. Total‐reflection in operando XAS measurements reveal that LiCoO₂ forms a reductive phase at the interface between the uncoated‐LiCoO₂ electrode and the electrolyte, while the MgO coating layer inhibits the redox process, leading to an improvement in the cycle performance of the battery. Depth‐resolved in operando XAS measurements indicate that a solid solution of the magnesium phase forms at the LiCoO₂ surface upon MgO coating. Magnesium ions function as pillars to stabilize the layered structure at the interface between the LiCoO₂ electrode and the electrolyte for delithiated states upon cycling at potentials.     

Potential use of only Yb2O3 in producing dense Si3N4 ceramics with high thermal conductivity by gas pressure sintering

Yb₂O₃ is an efficient sintering additive for enhancing not only thermal conductivity but also the high-temperature mechanical properties of Si₃N₄ ceramics. Here we report the fabrication of dense Si₃N₄ ceramics with high thermal conductivity by the gas pressure sintering of α-Si₃N₄ powder compacts, using only Yb₂O₃ as an additive, at 1900 °C under a nitrogen pressure of 1 MPa. The effects of Yb₂O₃ content, sample packing condition and sintering time on the densification, microstructure and thermal conductivity were investigated. Curves of the density plotted against the Yb₂O₃ content exhibited a characteristic ‘N’ shape with a local minimum at 3 mol% Yb₂O₃ and nearly complete densification below and above this concentration. The effects of the sample packing condition on the densification, microstructure and thermal conductivity strongly depended on the Yb₂O₃ content. The embedded condition led to more complete densification but also to a decrease in thermal conductivity from 119 to 94 W m^-1 K⁻¹ upon 1 mol% Yb₂O₃ addition. The sample packing condition had little effect on the density and thermal conductivity (102–106 W m⁻¹ K⁻¹) at 7 mol% Yb₂O₃. The thermal conductivity value was strongly related to the microstructure.     

Effect of the amount of excess oxides on the densification of α-SiAlON fabricated via a reaction-bonding process

Y-α-SiAlONs with elongated grains were fabricated via a reaction-bonding process using starting compositions containing excess oxides in the form of Y₂O₃ and SiO₂. The density of post-sintered specimens reached a maximum value with compositions containing 2 mass% excess oxides, although conventionally sintered materials of this composition were not fully dense. However for compositions containing smaller amounts of excess oxides, the density of the specimen fabricated via a reaction-bonding process was lower than that via a conventional process. In these samples it is thought that liquid phase sintering was difficult to be achieve during the post-sintering process, since the amount of SiO₂ contained in the starting powder was lower and the Al₂O₃ in the starting composition was consumed for the production of β-SiAlON during nitridation. There was also a decrease in density of the reaction-bonded materials with further increases in the amounts of additional oxides. For these samples the compacts could not be densified uniformly, because of non-uniformity of the phase composition in the nitrided compacts. The dense reaction bonded α-SiAlON with elongated grains, fabricated from compositions with 2 mass% excess oxides exhibited both high fracture toughness and high hardness.     

Application of femtosecond-laser induced nanostructures in optical memory

The femtosecond laser induced micro- and nanostructures for the application to the three-dimensional optical data storage are investigated. We have observed the increase of refractive index due to local densification and atomic defect generation, and demonstrated the real time observation of photothermal effect after the femtosecond laser irradiation inside a glass by the transient lens (TrL) method. The TrL signal showed a damped oscillation with about an 800 ps period. The essential feature of the oscillation can be reproduced by the pressure wave creation and propagation to the outward direction from the irradiated region. The simulation based on elastodynamics has shown that a large thermoelastic stress is relaxed by the generation of the pressure wave. In the case of soda-lime glass, the velocity of the pressure wave is almost same as the longitudinal sound velocity at room temperature (5.8 microm/ns). We have also observed the localized photo-reduction of Sm3+ to Sm2+ inside a transparent and colorless Sm(3+)-doped borate glass. Photoluminescence spectra showed that some the Sm3+ ions in the focal spot within the glass sample were reduced to Sm2+ ions after femtosecond laser irradiation. A photo-reduction bit of 200 nm in three-dimensions can be recorded with a femtosecond laser and readout clearly by detecting the fluorescence excited by Ar+ laser (lambda = 488 nm). A photo-reduction bit can be also erased by photo-oxidation with a cw Ar+ laser (lambda = 514.5 nm). Since photo-reduction bits can be spaced 150 nm apart in a layer within glass, a memory capacity of as high as 1 Tbit can be achieved in a glass piece with dimensions of 10 mm x 10 mm x 1 mm. We have also demonstrated the first observation of the polarization-dependent periodic nanostructure formation by the interference between femtosecond laser light and electron acoustic waves. The observed nanostructures are the smallest embedded structures ever created by light. The period of self-organized nanostructures can be controlled from approximately 140 to 320 nm by the pulse energy and the number of irradiated pulses. Furthermore, we have also observed the self-assembled sub-wavelength periodic structures created in silica glass by femtosecond pulses on the plane of the propagation of light.