Structure and transport properties of triple-conducting BaxSr1−xTi1−yFeyO3−δ oxides

In this work, Ba_xSr_1−xTi_1−yFe_yO_3−δ perovskite-based mixed conducting ceramics (for x = 0, 0.2, 0.5 and y = 0.1, 0.8) were synthesized and studied. The structural analysis based on the X-ray diffraction results showed significant changes in the unit cell volume and Fe(Ti)–O distance as a function of Ba content. The morphology of the synthesized samples studied by means of scanning electron microscopy has shown different microstructures for different contents of barium and iron. Electrochemical impedance spectroscopy studies of transport properties in a wide temperature range in the dry- and wet air confirmed the influence of barium cations on charge transport in the studied samples. The total conductivity values were in the range of 10⁻³ to 10⁰ S cm⁻¹ at 600 °C. Depending on the barium and iron content, the observed change of conductivity either increases or decreases in humidified air. Thermogravimetric measurements have shown the existence of proton defects in some of the analysed materials. The highest observed molar proton concentration, equal to 5.0 × 10⁻² mol mol⁻¹ at 300 °C, was obtained for Ba_0.2Sr_0.8Ti_0.9Fe_0.1O_2.95. The relations between the structure, morphology and electrical conductivity were discussed.

Ba_xSr_1−xTi_1−yFe_yO_3−δ-based perovskite materials with different barium and iron contents are reported as triple conducting oxides (TCOs), which may conduct three charge carriers: oxygen ions, protons and electrons/holes.

Meeting the challenges of healing chronic wounds in older adults

Older Americans are living longer. With aging, the skin becomes thinner, more fragile, and more susceptible to injury. Progressive normal and pathological aging changes increase the risk for chronic health problems that may lead to open wounds and delayed healing. Optimum care of chronic wounds supports the older person's specific health and care needs, progresses to cleansing and débridement of the wound, then uses an appropriate cover and other protective interventions to promote healing.

Identification of a 97-kDa heat shock protein from S. franciscanus ovaries with 94% amino acid identity to the S. purpuratus egg surface receptor for sperm

To identify species-specific regions of the sea urchin egg surface receptor for sperm, we cloned and sequenced the cDNA from S. franciscanus (Sf) ovary mRNA that is homologous to the S. purpuratus (Sp) sperm receptor sequence. The Sf cDNA contains an 886-amino-acid open reading frame (ORF) that is 96% identical at the nucleotide level to the Sp sperm receptor sequence over 2.9 kb. In contrast to the published Sp sequence, the Sf sequence does not encode a signal peptide or transmembrane domain. However, like the Sp sperm receptor sequence, the Sf protein has substantial similarity to the 70-kDa heat shock family of proteins and appears to encode a member of a newly identified subfamily of hsp70-related proteins designated hsp110/SSE. A BLAST search using the 5' end of the published Sp cDNA sequence as a query indicates that a segment of approximately 400 bp, which encodes the putative signal sequence, is 95% identical to Sp mitochondrial DNA. Resequencing of the Sp cDNA clone failed to confirm the presence of the published transmembrane and cytoplasmic domains. These results suggest that the published sequence of the Sp egg receptor for sperm may contain errors in the critical regions that were believed to encode an amino-terminal signal sequence, transmembrane domain, and cytoplasmic tail and that the protein products encoded by these cDNAs are highly related to mammalian cytoplasmic hsp110s.