A three-dimensional numerical simulation of the solid oxide fuel cell ͑SOFC͒ anode overpotential is conducted in a microstructure which is reconstructed by dual-beam focused ion beam-scanning electron microscopy ͑FIB-SEM͒. Gaseous, ionic, and electronic transport equations are solved by a lattice Boltzmann method with electrochemical reaction at the three-phase boundary. The predicted anode overpotential agrees with the experimental data at the fuel supply of 1.2% H 2 O-98.8% H 2 , while it is larger than the data at 10% H 2 O-90% H 2 . The dependence of exchange current density on steam partial pressure, gas diffusion modeling, as well as computational domain size must be further investigated in the future. Local three-dimensional distributions of electrochemical potential and current density inside the anode microstructure are obtained. Their nonuniformities are attributed to the scattered three-phase boundaries and complex transport paths through the solid phases.Solid oxide fuel cell ͑SOFC͒ is anticipated to play a major role in future energy utilization because of its superior efficiency and fuel flexibility. 1 However, its cost effectiveness and durability must be further improved before market introduction. The electrode microstructure has significant effects on the cell performance and durability of SOFCs. Thus, a basic understanding of the microscopic features of the electrode is indispensable. Quantitative investigations that relate the electrode microstructural parameters obtained from two-dimensional images and the polarization resistances have been reported. Wilson and Barnett 2 related anode polarization resistances to the three-phase boundary ͑TPB͒ densities of Ni-yttria-stabilized zirconia ͑YSZ͒ active layers by means of stereology. Shikazono et al. 3 also used stereology as well as the concept of contiguity theory to investigate the relationship between polarization characteristics and microstructural parameters such as TPB length and effective conductivities. However, a random mixture is assumed in stereology and the concept of contiguity theory, which has to be validated for further investigation. Furthermore, dead ends of the phases and electrochemically inactive TPBs should be rationally removed to quantitatively discuss the effects of microstructure on polarization characteristics. To overcome these issues, it is necessary to establish a method that can directly predict the polarization resistance in the real three-dimensional ͑3D͒ microstructure.Recently, direct measurements of a 3D SOFC electrode microstructure have been carried out using focused ion beam-scanning electron microscopy ͑FIB-SEM͒ 4-10 and X-ray computed tomography ͑XCT͒. 11 As a result, useful quantitative data such as TPB length and tortuosity factor are obtained from the reconstructed 3D microstructures. However, difficulty remains in removing errors that arise from a discretization process and insufficient sample volume size. 9,10,12 In addition to the above experimental studies, numerical simulations have the possibility ...
The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) trans activates the 21-bp enhancer of HTLV-1. A sequence of more than two copies of the 21-bp enhancer is efficiently activated by Tax, but one copy is not activated extensively. Another sequence (TRE-2, positions-163 to-117) adjacent to the 21-bp enhancer in the long terminal repeat of HTLV-1 can enhance a single copy of the 21-bp enhancer activity in trans activation by Tax. This sequence contains motifs related to the Ets-and NF-KB-binding sequences, but mutations at these sites indicated that neither is responsive to cooperation with the 21-bp enhancer. A deletion mutation of TRE-2 identified 25 bases at positions-158 to-134 (TRE-2S) as an essential sequence, and TRE-2S was sufficient to give maximum cooperation with one copy of the 21-bp enhancer in trans activation by Tax protein. Using TRE-2S as a probe, we screened a cDNA library of HUT102 cells by the Southwestern (DNA-protein) procedure and isolated two cDNA clones, THP-1 and-2. These two clones encode TRE-2Sbinding proteins, and they differ by only an extra 17 amino acids in THP-2. Both THP proteins contain five zinc finger motifs which are strikingly similar to those of the GLI family, an amplified gene product in glyoma cells. The binding site of THP-1 and-2 was GAACCACCCA in TRE-2S, which is highly homologous to the GLI-binding site. These results suggest that binding of THP to TRE-2S may be involved in cooperation with one copy of the 21-bp enhancer in responding to Tax trans activation.
Frozen-thawed epididymal spermatozoa have good fertilization capability in vitro; however, their artificial insemination conception rate is less than half of that of frozen-thawed ejaculated spermatozoa. Because the addition of seminal plasma to the thawing solution enhances the in vivo fertilizing ability of frozen-thawed ejaculated spermatozoa, we hypothesized that the reproductive performance of frozen-thawed epididymal spermatozoa could also be improved by the inclusion of seminal plasma. When frozenthawed epididymal spermatozoa were incubated for up to 6 hours, the motility of the sperm significantly decreased in a time-dependent manner. The acrosomal membrane was damaged in the majority of frozen-thawed epididymal spermatozoa. The addition of seminal plasma to the thawing solution significantly decreased the percentage of sperm with abnormal acrosomes and increased their total motility in a dose-dependent manner. Furthermore, the addition of seminal plasma reduced the abundance of a 15-kDa tyrosinephosphorylated protein in frozen-thawed sperm, and the maximum effect was observed at 15% (vol/vol) seminal plasma. When cryopreserved epididymal spermatozoa from 3 different boars were thawed with a 15% (vol/vol) seminal plasma-containing solution, the conception rate and mean litter size obtained by artificial insemination were significantly increased as compared with those in the control without seminal plasma. From these results, we concluded that the addition of seminal plasma to the thawing solution is a key step in obtaining an optimal number of piglets by artificial insemination using frozen-thawed boar epididymal spermatozoa.
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