Previous H2 permeation tests showed a degradation of H2 permeation flux with time. To understand the cause of degradation and develop a solution, the stability of $ {\text{SrCe}}_{{0.9}} {\text{Eu}}_{{0.1}} {\text{O}}_{{3 - \delta }} $ and $ {\text{SrZr}}_{{0.2}} {\text{Ce}}_{{0.7}} {\text{Eu}}_{{0.1}} {\text{O}}_{{3 - \delta }} $ samples were studied under dry and wet H2 atmospheres. Total conductivity of $ {\text{SrCe}}_{{0.9}} {\text{Eu}}_{{0.1}} {\text{O}}_{{3 - \delta }} $ increased with time in dry H2. The X-ray diffraction pattern of $ {\text{SrCe}}_{{0.9}} {\text{Eu}}_{{0.1}} {\text{O}}_{{3 - \delta }} $ after dry hydrogen atmosphere heat treatments show CeO2 peaks indicating that $ {\text{SrCe}}_{{0.9}} {\text{Eu}}_{{0.1}} {\text{O}}_{{3 - \delta }} $ decomposes under dry H2 atmospheres; scanning electron microscopy and energy dispersive X-ray spectroscopy analyses prove that decomposition proceeded along the grain boundaries. $ {\text{SrZr}}_{{0.2}} {\text{Ce}}_{{0.7}} {\text{Eu}}_{{0.1}} {\text{O}}_{{3 - \delta }} $ was investigated and demonstrated greater stability under dry hydrogen atmospheres. However, Zr substitution results in a tradeoff with electrical properties. 相似文献
We experimentally demonstrate a new wavelength- and mode-selective coupler utilizing intermodal coupling between a standard single-mode fiber (SMF) and a hollow optical fiber (HOF). The fabricated device routes optical signals such that a 1.3-microm signal is directed to the HOF port, adiabatically converting the LP(01) mode into a ring-shaped mode, which can be further connected to a gigabit ethernet link, reducing the differential mode-dispersion penalty. Optical signals near 1.5microm , meanwhile, stay in the LP(01) mode of the SMF arm for further connection to conventional wavelength-division multiplexing links based on erbium-doped fiber amplifiers. The performance of the device is characterized in terms of insertion loss, channel isolation, and mode-conversion efficiency. 相似文献
Let G be a connected simply connected almost
-simple algebraic group with
non-compact and
a cocompact congruence subgroup. For any homogeneous manifold
of finite volume, and a
, we show that the Hecke orbit Ta(x0H) is equidistributed on
as
, provided H is a non-compact commutative reductive subgroup of G. As a corollary, we generalize the equidistribution result of Hecke points ([COU], [EO1]) to homogeneous spaces G/H. As a concrete application, we describe the equidistribution result in the rational matrices with a given characteristic
polynomial.
The second author partially supported by DMS 0333397.
Received: May 2005 Revision: March 2006 Accepted: June 2006 相似文献
The origin and the magnitude of the charge in a macroion are critical questions in mass spectrometry analysis coupled to electrospray and other ionization techniques that transfer analytes from the bulk solution into the gaseous phase via droplets. In many circumstances, it is the later stages of the existence of a macroion in the containing solvent drop before the detection that determines the final charge state. Experimental characterization of small (with linear dimensions of several nanometers) and short-lived droplets is quite challenging. Molecular simulations in principle may provide insight exactly in this challenging for experiments regime. We discuss the strengths and weaknesses of the molecular modeling of electrosprayed droplets using molecular dynamics. We illustrate the limitations of the molecular modeling in the analysis of large macroions and specifically proteins away from their native states.
Biodegradable microparticles are promising for the sustained release of encapsulated lipophilic drugs. In particular, the microparticles with uniform size show excellent linearity of cumulated release over time with minimized initial burst. Here, we encapsulate the biodegradable microparticles with a hydrogel shell to improve the controllability over the sustained release and suspension stability. With a capillary microfluidic device, monodisperse oil-in-water-in-oil (O/W/O) double-emulsion droplets are produced to have a toluene solution of polylactic acid (PLA) in the core and sodium alginate and calcium-ethylenediaminetetraacetic acid (EDTA) complex in the shell, whereas the continuous oil phase contains acetic acid. As the toluene evaporates, PLA consolidates to form a microsphere in the core. At the same time, acetic acid diffuses from the continuous phase to the water layer, which causes the dissociation of the Ca-EDTA complex and the gelation of alginate. The hydrogel-shelled PLA microspheres are transferred from the oil to an aqueous solution of calcium chloride, which further tightens the gel shell. The resulting core-shell microspheres show sustained release of encapsulants for extended periods as the hydrogel shell serves as a diffusion barrier. Moreover, the hydrogel shells prevent interparticle agglomeration and adhesion to the solid walls, securing high suspension stability during the injection. 相似文献
Journal of Solid State Electrochemistry - Li-doped high surface area of activated carbon (LHSAC) for Li ion capacitor (LIC) has been prepared by controlling the LiOH amounts for surface... 相似文献
This study prepared a waterproof cellulose nanofibril (CNF) sheet via the deposition of an alkyl ketene dimer (AKD) on the sheet’s controlled porous structure. The porosity of the CNF sheet was controlled by drying under different conditions, which included hot-press drying (HD) and solvent-exchange drying (SD), and the effect on the hydrophobization and water-related barrier performance of the sheet were investigated. When the SD sheet was immersed in an AKD wax solution, the sheet exhibited super-hydrophobicity and a lower water vapor transmission rate, compared with the HD sheet. This indicated that the porous structure of the SD sheet enabled AKD to be adsorbed on both the surface and the inner surface and it filled in the pores of the sheet, thereby giving rise to excellent waterproofing properties. The performance of a hydrophobized SD sheet as a water barrier material was comparable to a linear low-density polyethylene film. This study confirms the possibility for AKD wax to be immersed in a porous CNF sheet and used as a potential barrier material in hydrogel packaging.
Amyloid-β (Aβ) in the form of neurotoxic aggregates is regarded as the main pathological initiator and key therapeutic target of Alzheimer's disease. However, anti-Aβ drug development has been impeded by the lack of a target needed for structure-based drug design and low permeability of the blood–brain barrier (BBB). An attractive therapeutic strategy is the development of amyloid-based anti-Aβ peptidomimetics that exploit the self-assembling nature of Aβ and penetrate the BBB. Herein, we designed a dimeric peptide drug candidate based on the N-terminal fragment of Aβ, DAB, found to cross the BBB and solubilize Aβ oligomers and fibrils. Administration of DAB reduced amyloid burden in 5XFAD mice, and downregulated neuroinflammation and prevented memory impairment in the Y-maze test. Peptide mapping assays and molecular docking studies were utilized to elucidate DAB-Aβ interaction. To further understand the active regions of DAB, we assessed the dissociative activity of DAB with sequence modifications. 相似文献