Electrochemical Deposition and Characterization of Fe₃O₄ Films Produced by the Reduction of Fe(III)-triethanolamine

In this paper, we demonstrate that films of magnetite, Fe3O4, can be deposited by the electrochemical reduction of a Fe(III)-triethanolamine complex in aqueous alkaline solution. the films were deposited with a columnar microstructure and a [100] preferred orientation on stainless steel substrates. In-plane electrical transport and magnetoresistance measurements were performed on the films after they were stripped off onto glass substrates. the resistance of the films was dependent on the oxygen partial pressure. We attribute the increase in resistance in O2 and the decrease in resistance in Ar to the oxidation and reduction of grain boundaries. the decrease in resistance in an Ar atmosphere exhibited first-order kinetics, with an activation energy of 0.2 eV. the temperature dependence of the resistance showed a linear dependence of log(R) versus T-1/2, consistent with tunneling across resistive grain boundaries. a room-temperature magnetoresistance of -6.5% was observed at a magnetic field of 9 T

Epitaxial Electrodeposition of Metal Oxide Thin Films and Superlattices for Energy Conversion and Storage

Track IV: Materials for Energy ApplicationsIncludes audio file (21 min.)Electrodeposition, like biomineralization, is a soft solution processing method in which inorganic materials are produced from solution precursors. The technique provides degrees of freedom that are not accessible to UHV deposition methods. The shape, orientation, and even chirality can be controlled through solution additives, pH, and electrode potential. Our emphasis is on producing epitaxial nanostructures of metal oxide semiconductors such as ZnO and Cu2O, magnetic materials such as Fe3O4, and battery materials such as LiMnO2. These materials are being produced for both the conversion and storage of energy. Cu2O is produced for photovoltaic devices and ZnO is produced for both photovoltaic devices and solid state lighting. Because the ZnO deposits as nanowires, electron-hole recombination can be minimized. We have recently found that ZnO can be epitaxially grown on single-crystal Si(111). In addition to exciton PL emission from the ZnO, there is also strong green emission due to native defects. Fe3O4 is being produced as thin films and superlattices for spintronic devices. Nanoribbons of LiMnO2 are deposited for use in high capacity lithium batteries. This material is presently used in Li batteries, but it is made by traditional powder metallurgy methods. The electrodeposition of nanostructured cathodes of this material could prove to be a major breakthrough in the lithium battery field

Construction of an ~700-kb transcript map around the Familial Mediterranean Fever locus on human chromosome 16p13.3

We used a combination of cDNA selection, exon amplification, and computational prediction from genomic sequence to isolate transcribed sequences from genomic DNA surrounding the familial Mediterranean fever (FMF) locus. Eighty-seven kb of genomic DNA around D16S3370, a marker showing a high degree of linkage disequilibrium with FMF, was sequenced to completion, and the sequence annotated. A transcript map reflecting the minimal number of genes encoded within the ∼700 kb of genomic DNA surrounding the FMF locus was assembled. This map consists of 27 genes with discreet messages detectable on Northerns, in addition to three olfactory-receptor genes, a cluster of 18 tRNA genes, and two putative transcriptional units that have typical intron–exon splice junctions yet do not detect messages on Northerns. Four of the transcripts are identical to genes described previously, seven have been independently identified by the French FMF Consortium, and the others are novel. Six related zinc-finger genes, a cluster of tRNAs, and three olfactory receptors account for the majority of transcribed sequences isolated from a 315-kb FMF central region (betweenD16S468/D16S3070 and cosmid 377A12). Interspersed among them are several genes that may be important in inflammation. This transcript map not only has permitted the identification of the FMF gene (MEFV), but also has provided us an opportunity to probe the structural and functional features of this region of chromosome 16.Michael Centola, Xiaoguang Chen, Raman Sood, Zuoming Deng, Ivona Aksentijevich, Trevor Blake, Darrell O. Ricke, Xiang Chen, Geryl Wood, Nurit Zaks, Neil Richards, David Krizman, Elizabeth Mansfield, Sinoula Apostolou, Jingmei Liu, Neta Shafran, Anil Vedula, Melanie Hamon, Andrea Cercek, Tanaz Kahan, Deborah Gumucio, David F. Callen, Robert I. Richards, Robert K. Moyzis, Norman A. Doggett, Francis S. Collins, P. Paul Liu, Nathan Fischel-Ghodsian and Daniel L. Kastne

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

Electrodeposition of inorganic materials with tailored shapes and chiral morphologies

This dissertation investigates the electrodeposition of metal oxide films and biomaterial deposits on polycrystalline and single crystal substrates. Paper I describes the mechanisms and the characterization of an electrodeposited polycrystalline insulator, ceria (CeO₂), on Hastelloy substrates produced by the electrochemical oxidation of Ce(III) acetate complexes. In Paper II, epitaxial films of magnetite (Fe₃O₄) and ferrihydrite (Fe₁₀O₁₄(OH)₂) are deposited on gold single crystals. Paper III reports the electrodeposition of epitaxial Fe₃O₄ and zinc ferrite (ZnFe₂O₄) periodic nanostructures known as superlattices by pulsing between two potentials. Papers IV and V describe chiral electrodeposition. In Paper IV, epitaxial, chiral orientations of cupric oxide (CuO) are electrodeposited on Au(001) single crystals. In Paper V, chiral morphologies of the biomaterial calcite (CaCO₃) are electrochemically deposited on stainless steel substrates. In both chiral electrodeposition studies, the chirality of these materials is controlled by the enantiomer in solution. The first two appendices of this dissertation cover morphology and x-ray diffraction characterization. The third appendix has supplementary information from the calcite paper (Paper V) followed by unpublished biomineralization results --Abstract, page iv

Electrochemical Biomineralization: The Deposition of Calcite with Chiral Morphologies

The biominerals calcite and aragonite are electrodeposited by electrochemically generating base in a solution containing Ca2+ and HCO3-. Although calcite crystallizes in the achiral space group Rc, orientations of calcite which lack mirror or glide plane symmetry are chiral. Chiral morphologies of calcite are electrodeposited in the presence of tartaric, malic, and aspartic acid. Calcite grows with left-handed spirals when deposited from L-tartaric acid but grows with right-handed spirals when deposited from L-malic acid or L-aspartic acid. a racemic mixture of D- and L-malic acid produces an achiral microstructure, instead of producing a racemic mixture of chiral microstructures

Epitaxial Electrodeposition of ZnO on Au(111) from Alkaline Solution: Exploiting Amphoterism in Zn(II)

The amphoteric nature of ZnO is used to produce the material from strongly alkaline solution. The solution pH is lowered globally to produce ZnO powder, and it is lowered locally at a Au(111) surface to produce epitaxial films. ZnO powder is precipitated from a solution of 10 mM Zn(II) in 0.25 M NaOH by simply adding 1 M HNO3 to the solution. For the film electrodeposition, the local pH at the electrode surface is decreased by electrochemically oxidizing the ascorbate dianion. The chemically precipitated ZnO powder grows with a sea urchin-like nanostructure, whereas the electrodeposited films have a columnar structure. ZnO electrodeposited onto a Au(111) single crystal has a ZnO(0001)[101]//Au(111)[10] orientation relationshi