Room-temperature miscibility gap in LixFePO4

The rechargeable lithium-ion cell is an advanced energy-storage system. However, high cost, safety hazards, and chemical instability prohibit its use in large-scale applications. An alternative cathode material, LiFePO(4), solves these problems, but has a kinetic problem involving strong electron/hole localization. One reason for this is believed to be the limited carrier density in the fixed monovalent Fe(3+)PO(4)/LiFe(2+)PO(4) two-phase electrode reaction in LixFePO4. Here, we provide experimental evidence that LixFePO4, at room temperature, can be described as a mixture of the Fe(3+)/Fe(2+) mixed-valent intermediate LialphaFePO4 and Li1-betaFePO4 phases. Using powder neutron diffraction, the site occupancy numbers for lithium in each phase were refined to be alpha=0.05 and 1-beta=0.89. The corresponding solid solution ranges outside the miscibility gap (0相似文献   

Stability of polydihydrosilane liquid films on solid substrates

The quality of polydihydrosilane liquid films is a key factor in the fabrication of solution-processed silicon films. This study investigates the stability of polydihydrosilane liquid films with a thickness L of ~ 40 nm on solid substrates by a comparison between the observed optical microscope images and the values of the Hamaker constant A_ALS for the air/liquid (polydihydrosilane)/solid substrate systems. A_ALS values for a series of SiO₂-based substrates were determined by adopting a simple spectrum method. We found that the micrographs of the polydihydrosilane films provide direct evidence of stability in accordance with the sign of A_ALS; a stable liquid film with A_ALS > 0 showed a continuous figure, while an unstable film with A_ALS < 0 exhibited an array of dots caused by the rupture of the film. The array of dots in the unstable liquid films has a slight orderly distribution with a period λ that is in accord with the characteristic wavelength of the undulation related to the spinodal-like decomposition in van der Waals unstable liquid.     

Pharmaceutical production of tableting granules in an ultra-small-scale high-shear granulator as a pre-formulation study

Objective: In some of drug developments, the amount of bulk drug powder to use in early stages is limited and it is not easy to supply a sufficient drug amount for conventional preparation methods. Therefore, an ultra-small-scale high-shear granulator (less than 5?g) (USG) was developed and applied to small-scale granulation as a pre-formulation. Method: The sample powder consisted of 66.5% lactose, 28.5% microcrystalline cellulose and 5.0% hydroxypropylcellulose. The granules were obtained to agitate 5?g of the sample powder with 1.0?mL of water at 300?rpm for 5?min after pre-powder mixing for 3?min by the USG and the manual hand (HM) methods. Results: The granules were evaluated by the 10% and 90% accumulated particle size and the recoveries of the granules and the powder solid. Median particle size for the USG and the HM methods was 159.2?±?2.3 and 270.9?±?14.9 μm, respectively. The USG method had a narrower particle size distribution than those by the HM method. The recovery of the granules by USG was significantly larger than that by the HM method. Conclusion: Characteristics of all of the granules indicated that the USG method could produce higher quality granules within a shorter time than the HM methods.     

Selective protein separation using siliceous materials with a trimethoxysilane-containing glycopolymer

A copolymer with α-D-mannose (Man) and trimethoxysilane (TMS) units was synthesized for immobilization on siliceous matrices such as a sensor cell and membrane. Immobilization of the trimethoxysilane-containing copolymer on the matrices was readily performed by incubation at high heat. The recognition of lectin by poly(Man-r-TMS) was evaluated by measurement with a quartz crystal microbalance (QCM) and adsorption on an affinity membrane, QCM results showed that the mannose-binding protein, concanavalin A, was specifically bound on a poly(Man-r-TMS)-immobilized cell with a higher binding constant than bovine serum albumin. The amount of concanavalin A adsorbed during permeation through a poly(Man-r-TMS)-immobilized membrane was higher than that through an unmodified membrane. Moreover, the concanavalin A adsorbed onto the poly(Man-r-TMS)-immobilized membrane was recoverable by permeation of a mannose derivative at high concentration.     

Kinetics of methane reforming over Ru/γ-Al2O3-catalyzed metallic foam at 650-900 °C for solar receiver-absorbers

The kinetics of methane reforming over Ru/γ-Al₂O₃-catalyzed high porosity Ni-Cr-Al foam were examined at temperatures of 650-900 °C in a quartz tubular reactor using an electric furnace. The kinetic data were analyzed by four different types of kinetic models based on the basic, Eley-Rideal, Langmuir-Hinshelwood, and stepwise mechanisms. Validation of the kinetic models was carried out by calculating the determination coefficient r² between the predicted and the experimental results for each model. The absolute average deviation percentage (AAD%) between the predicted and the experimental results was also estimated for each model. The kinetic model based on the reversible stepwise mechanism provided the best prediction of the experimental reforming rates with an AAD value of 6% in the range 650-850 °C.     

Comparative study of activity of cerium oxide at thermal reduction temperatures of 1300–1550 °C for solar thermochemical two-step water-splitting cycle

Thermochemical two-step water-splitting using CeO₂ (cerium oxide) particles was studied to examine oxygen and hydrogen productivity and repeatability at thermal reduction (T-R) temperatures of 1300–1550 °C and water decomposition (W-D) temperatures of 400–1000 °C for the production of hydrogen from water using concentrated solar radiation as the energy source. The temperature dependency of oxygen and hydrogen productivity and the cyclic repeatability of CeO₂ are reported in this paper. The characteristic features of CeO₂ particles in the thermochemical two-step water-splitting cycle are compared with the well-known highly active reactive mediums of zirconia-supported Ni-ferrites (NiFe₂O₄/m-ZrO₂ and NiFe₂O₄/c-YSZ) and unsupported NiFe₂O₄.     

Measurements of keV-neutron capture cross sections and capture gamma-ray spectra of 105Pd

The neutron capture cross sections and capture gamma-ray spectra of ¹⁰⁵Pd were measured in the region from 15 to 100 keV and at 585 keV. A neutron time-of-flight method was utilised with an anti-Compton NaI(Tl) spectrometer and a 1.5-ns pulsed neutron source by the ⁷Li(p,n)⁷Be reaction. The capture yields were obtained by applying a pulse-height weighting technique to the observed net capture gamma-ray pulse-height spectra. The capture cross sections of ¹⁰⁵Pd were derived with errors less than 5%, using the standard capture cross sections of ¹⁹⁷Au. The evaluated capture cross sections of JENDL-4.0 and ENDF/B-VII.1 were compared with the present results. The evaluations of JENDL-4.0 and ENDF/B-VII.1 were larger than the present results by 3%–15% in the region from 15 to 100 keV and at 585 keV. The capture gamma-ray spectra of ¹⁰⁵Pd were also derived by unfolding the observed net capture gamma-ray pulse-height spectra. The multiplicities of capture gamma rays of ¹⁰⁵Pd were obtained from the capture gamma-ray spectra.     

An optimization approach to establish an appropriate energy group structure for BWR pin-by-pin core analysis

An optimization approach to establish an appropriate multi-group energy structure for boiling water reactor (BWR) pin-by-pin fine mesh core analysis is proposed. In the present approach, the number of energy groups of cross sections is successively reduced or increased. In order to select an energy group boundary that is removed or added, performances of all possible candidates of energy group structures are tested in multi-assembly geometries. Then, the energy group boundary, which provides the minimum difference of the k-infinity or the pin-by-pin fission rate distribution, is finally removed or added. This procedure is repeated until the number of energy groups reaches to the target value. In order to confirm the applicability of the present approach, the accuracies of the k-infinity and the pin-by-pin fission rate distribution are investigated in various 2 × 2 multi-assembly geometries with the established energy group structure. From the verification results, the differences of the k-infinity and the pin-by-pin fission rate distribution between the reference (fine) and the established (coarse) energy group structure are small in the various 2 × 2 multi-assembly geometries. Therefore, we can conclude that the present approach is efficient to establish an appropriate energy group structure for BWR pin-by-pin fine mesh core analysis.