Dielectric and Electromechanical Properties of Textured Niobium-Doped Bismuth Titanate Ceramics

Textured Nb-doped bismuth titanate ceramics (Bi₄Ti_{3− x /5}- Nb _{x /5}O₁₂, where x = 0.02) were fabricated by templated grain growth. It was found that the use of a fine precursor powder led to enhanced densification of the ceramic, while Nb doping reduced electrical conduction and dielectric loss, which enabled poling at high temperatures and high electric fields. Sintered tapes showed anisotropic dielectric and piezoelectric properties when measured parallel and perpendicular to the casting plane (e.g., the remanent polarization differed by more than a factor of 15 in the two directions). The piezoelectric constant parallel to the casting plane of the tape was ∼30 pC/N, or ∼77% of the single-crystal value. Thermal depoling studies demonstrated that high-temperature piezoelectric applications are possible up to ∼450°C in textured, doped bismuth titanate.     

The Engineering of Bacteria Bearing Azido‐Pseudaminic Acid‐Modified Flagella

Catch a tiger by the tail : We have demonstrated that by feeding nonmotile mutant C. jejuni bacteria with a neutral azide‐labelled pseudaminic acid precursor we can restore their ability to generate functional flagella. The presence of azido‐pseudaminic acid on the surface of the flagella provides a bio‐orthogonal chemical handle that can be used to modify the flagellar proteins.

     

Designed Proteins as Novel Imaging Reagents in Living Escherichia coli

Fluorescence imaging is a powerful tool to study protein function in living cells. Here, we introduce a novel imaging strategy that is fully genetically encodable, does not require the use of exogenous substrates, and adds a minimally disruptive tag to the protein of interest (POI). Our method was based on a set of designed tetratricopeptide repeat affinity proteins (TRAPs) that specifically and reversibly interact with a short, extended peptide tag. We co‐expressed the TRAPs fused to fluorescent proteins (FPs) and the peptide tags fused to the POIs. We illustrated the method using the Escherichia coli protein FtsZ and showed that our system could track distinct FtsZ structures under both low and high expression conditions in live cells. We anticipate that our imaging strategy will be a useful tool for imaging the subcellular localization of many proteins, especially those recalcitrant to imaging by direct tagging with FPs.     

Ozonation of swine manure wastes to control odors and reduce the concentrations of pathogens and toxic fermentation metabolites

The use of ozone for the remediation of nuisance odorous chemicals in liquid swine manure slurry was investigated. Gaseous ozone was bubbled directly into stored swine manure slurry in a continuously stirred batch reactor. One‐liter samples of swine slurry were ozonated to achieve ozone dosages of 1.0, 2.0 and 3.0 g ozone/liter of waste. Olfactometric determinations demonstrated a significant reduction in odors in ozonated samples as compared to raw and oxygenated samples. Volatile fatty acids, nitrate, phosphate and ammonia concentrations were unchanged by ozonation. The biochemical oxygen demand (BOD) and the chemical oxygen demand (COD) were essentially unaffected by ozonation. The concentrations of odorous phenolic microbial metabolites (e.g., phenol, p‐cresol and p‐ethylphenol) and odorous indolic microbial metabolites (e.g., 3‐methylindole and indole) were reduced to non‐detectable levels by ozonation. Hydrogen sulfide concentrations were reduced slightly by the process, with a concurrent increase in the sulfate concentration. E. coli counts were reduced by a factor of three log units and total coliforms showed a one log decrease in concentration after treatment with ozone at 1.0 g/L.

The results of this study demonstrate clearly that at the pH values studied (ca. 7), ozonation is effective for the elimination of the malodors associated with stored swine slurry and for killing potentially pathogenic bacteria, without increasing the concentrations of major pollutants of current concern, (i.e., nitrate and phosphate) and without oxidizing ammonia, which is a major plant nutrient.     

Stabilization of filled polysiloxane elastomers to cyclic stress at elevated temperature through use of zinc oxide fillers

The susceptibility of filled polysiloxane elastomers to cyclic stress at elevated temperatures is investigated. It is shown that zinc oxide fillers, unlike other fillers examined previously, can produce filled elastomers with remarkable stability to combined mechanical and thermal stresses. The influences of filler concentration, diphenylsiloxane incorporation, and molecular weight between network crosslinks are examined. The data demonstrate that the elastomer stability to cyclic stress at elevated temperature increases with increasing filler content and does not correlate with diphenylsiloxane content. It is suggested that chemical interactions between the polysiloxane network and the filler surfaces control the response to cyclic stress at elevated temperature and that the response strongly depends on the type of filler selected. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1499–1509, 1997     

Flaxseed Oil or n-7 Fatty Acid-Enhanced Fish Oil Supplementation Alters Fatty Acid Composition,Plasma Insulin and Serum Ceramide Concentrations,and Gene Expression in Lambs

The objective of this study was to examine the effects of flaxseed (FLAX) oil or 16-carbon n-7 fatty acid -enhanced fish oil (Provinal; POA) supplementation on serum, liver and skeletal muscle fatty acid concentrations, serum ceramide and plasma insulin concentrations, and gene expression. Lambs [n = 18; 42 ± 5.6 kg body weight (BW); 7 months] were individually fed one of the three treatments: (1) control (CON), no oil supplement, (2) FLAX; at 0.1% of BW, or (3) POA at 0.1% of BW for 60 days. Daily feed intake and weight gain were decreased by 21% and 34%, respectively, for POA than FLAX. Liver and skeletal muscle concentrations of palmitoleic acid were greater by 396% and 87%, respectively, for POA than FLAX; whereas, liver and skeletal muscle α-linolenic acid concentrations were greater by 199% and 118%, respectively, for FLAX. Supplementation with POA also had greater serum and tissue concentrations of eicosapentaenoic and docosahexaenoic acids. Serum glucose and plasma insulin concentrations were elevated with FLAX supplementation at the end of the study. Supplementation with POA altered serum ceramide concentrations compared to CON or FLAX. Oil supplementation, both FLAX and POA, downregulated expression of unesterified fatty acid receptors (FFAR) 1 and FFAR4 in the liver; however, oil supplementation upregulated expression of FFAR1 in muscle. Interleukin-6 (IL6) and tumor necrosis factor-α (TNFA) expression were downregulated with oil supplementation in the liver; however, FLAX upregulated TNFA in muscle. These results show that oil supplementation can enhance uptake and deposition of unique fatty acids that alter ceramide concentrations and gene expression in tissues.     

The Effects of Low Oxygen Activity Conditions on the Phase Equilibria and Cation Occupancy of Strontium Barium Niobate

Strontium barium niobate (SBN) is a tungsten bronze family ferroelectric which shows promising thermoelectric properties under reducing conditions. It is found here that the enhanced electrical conductivity of oxygen‐deficient SBN correlates with the formation of a NbO₂ secondary phase. The effects of the reducing environment and the NbO₂ phase formation are studied via a detailed defect chemistry analysis. Increasing amounts of the NbO₂ phase are accompanied by an interesting mechanism where the A‐site occupancy of the SBN matrix increases. The resulting donor defects source the large carrier concentrations which cause the enhanced electrical conductivity necessary for thermoelectric performance. In investigation of the phase equilibria, it is found that a solid solution between (Sr_0.6,Ba_0.4)Nb₂O₆ and (Sr_0.6,Ba_0.4)_1.2Nb₂O₆ exists and that the A‐site filling is found to occur at more modest reduction conditions in Sr‐ and Ba‐rich compositions. Finally, thermogravimetric analysis of the reoxidation process is performed, and the results suggest that the A‐site filling is compensated ionically. Not only do the presented results explain the enhanced electrical conductivity of oxygen‐deficient strontium barium niobate but also modification of the site occupancies by reduction and reoxidation may widen the design space for property modification in tungsten bronze‐structured materials in general.     

Physicochemical Properties and Adhesion Performance of Canola Protein Modified with Sodium Bisulfite

The objective of this research was to study the adhesion properties of sodium bisulfite (NaHSO₃)-modified canola protein. Protein was extracted from canola meal through alkali solubilization and acid precipitation methods, then modified with different concentrations of NaHSO₃ (0–15 g/L) during the isolation process. As NaHSO₃ concentration increased, canola protein purities decreased. Amino acid profiles showed that the hydrophobic amino acids in canola protein constituted only 27% of total protein, indicating that canola protein is mostly hydrophilic. The reducing effects of NaHSO₃ were exerted on canola protein through the breaking of disulfide bonds in both its cruciferin and napin components, as reflected by the protein electrophoresis profile, DSC data, and morphological images. The wet protein isolates were used as adhesives. The greatest wet shear strength of canola protein adhesive without modification was 3.97 MPa with 100% wood cohesive failure (WCF), observed at a curing temperature of 190 °C. NaHSO₃ had slight weakening effects on the adhesion performance of canola protein. Canola protein modified with 3 g/L NaHSO₃ exhibited wet shear strength similar to the control at 190 °C and higher strength at 150 and 170 °C. The NaHSO₃ modification significantly improved handling and flowability of canola protein adhesives.     

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

The conversion of eugenol (4-allyl-2-methoxyphenol), a compound derived from the lignin in woody biomass, was catalyzed by HY zeolite at 573 K and atmospheric pressure. The main products were isoeugenol and guaiacol, formed by isomerization and by deallylation, respectively. Substituted guaiacols with saturated side-chains (4-methylguaiacol, 4-ethylguaiacol, and 4-propylguaiacol) were also formed, by hydrogen transfer and alkylation reactions. The pseudo-first-order rate constant for the overall disappearance of eugenol was found to be 12.4 L (g of catalyst)/h. When the catalyst was Pt/γ-Al₂O₃ used in the presence of H₂, significant hydrogenation of the propenyl side-chain took place, accompanied by isomerization, and hydrodeoxygenation. Under similar operating conditions, the reaction catalyzed by Pt/γ-Al₂O₃ in the presence of H₂ gave a higher eugenol conversion (X = 0.70) than the reaction catalyzed by HY zeolite (X = 0.11), primarily because of the dominant hydrogenation observed with the former catalyst. In the absence of H₂ as a co-reactant, the acidic γ-Al₂O₃ support in Pt/γ-Al₂O₃ evidently catalyzed all the classes of reactions catalyzed by HY zeolite.