Tanya Prozorov

Bio: Tanya Prozorov is an academic researcher from Ames Laboratory. The author has contributed to research in topics: Magnetotactic bacteria & Magnetosome. The author has an hindex of 27, co-authored 72 publications receiving 2556 citations. Previous affiliations of Tanya Prozorov include Iowa State University & United States Department of Energy.

Self-Assembled Monolayers of Alkanesulfonic and -phosphonic Acids on Amorphous Iron Oxide Nanoparticles

Abstract: We have functionalized amorphous Fe2O3 nanoparticles with alkanesulfonic and octadecanephosphonic acids. TEM reveals nanoparticles 5−10 nm in diameter. FTIR spectra suggest that while in all cases the alkyl chains are packed in a solid-like arrangement, packing disorder increased with decreasing chain length. TGA of the sulfonic acid-functionalized Fe2O3 nanoparticles shows that moieties started to decompose and desorb from the iron oxide surface at about 260 °C. In the case of the octadecanephosphonic acid (OPA)-functionalized Fe2O3, moieties started to decompose and desorb at 340 °C. It is suggested that free Fe−OH groups can serve as proton donors to assist in the sulfonic acid desorption process and that because of the diprotic nature of the phosphonic acid these free surface Fe−OH groups may no longer be available. Among all, the octadecanesulfonic acid coating displays the lowest magnetization, which may be explained by the high packing and ordering of the alkyl chains on the particle surface. The s...

High velocity interparticle collisions driven by ultrasound.

Abstract: Ultrasonic irradiation of slurries produces high velocity impacts between solid metal particles that are sufficient to cause interparticle melting. Sonication of 5 μm Zn powder as a slurry in alkanes, for example, produces dense agglomerates 50 μm in diameter consisting of ∼1000 fused particles. Particle size was found to be the most influential parameter in inducing local melting during interparticle collisions. Ultrasonic irradiation of mixed powders resulted in formation of agglomerates with larger Zn particles “soldered” by the smaller ones. A simple kinematic model of the ultrasound-driven interparticle fusion predicts a melting criterion that is nonmonotonically dependent on particle size and is shown to be in agreement with experiment.

A Cultured Greigite-Producing Magnetotactic Bacterium in a Novel Group of Sulfate-Reducing Bacteria

Abstract: Magnetotactic bacteria contain magnetosomes—intracellular, membrane-bounded, magnetic nanocrystals of magnetite (Fe3O4) or greigite (Fe3S4)—that cause the bacteria to swim along geomagnetic field lines. We isolated a greigite-producing magnetotactic bacterium from a brackish spring in Death Valley National Park, California, USA, strain BW-1, that is able to biomineralize greigite and magnetite depending on culture conditions. A phylogenetic comparison of BW-1 and similar uncultured greigite- and/or magnetite-producing magnetotactic bacteria from freshwater to hypersaline habitats shows that these organisms represent a previously unknown group of sulfate-reducing bacteria in the Deltaproteobacteria. Genomic analysis of BW-1 reveals the presence of two different magnetosome gene clusters, suggesting that one may be responsible for greigite biomineralization and the other for magnetite.

Protein-Mediated Synthesis of Uniform Superparamagnetic Magnetite Nanocrystals**

Abstract: Magnetite nanocrystals are synthesized in the presence of a recombinant Mms6 protein thought to be involved in the biomineralization of bacterial magnetite magnetosomes, the mammalian iron-storage protein, ferritin, and two proteins not known to bind iron, lipocalin (Lcn2) and bovine serum albumin (BSA). To mimic the conditions at which magnetite nanocrystals are formed in magnetotactic bacteria, magnetite synthesis is performed in a polymeric gel to slow down the diffusion rates of the reagents. Recombinant Mms6 facilitates formation of ca. 30 nm single-domain, uniform magnetite nanocrystals in solution, as verified by using transmission electron microscopy analysis and magnetization measurements. The nanocrystals formed in the presence of ferritin, Lcn2, and BSA, do not exhibit the uniform sizes and shapes observed for those produced in the presence of Mms6. Mms6-derived magnetite nanoparticles show the largest magnetization values above the blocking temperature, as well as the largest magnetic susceptibility compared to those of the nanomaterials synthesized with other proteins. The latter is indicative of a substantial effective magnetic moment per particle, which is consistent with the presence of magnetite with a well-defined crystalline structure. The combination of electron microscopy analysis and magnetic measurements confirms our hypothesis that Mms6 promotes the shape-selective formation of uniform superparamagnetic nanocrystals. This provides a unique bioinspired route for synthesis of uniform magnetite nanocrystals.

Sonochemistry and Sonoluminescence of Room-Temperature Ionic Liquids

Abstract: The sonication of ionic organic liquids leads to decomposition of the liquids. Multibubble sonoluminescence spectra and headgas analysis reveal a variety of decomposition products from the sonolysis of N,N‘-dialkylimidazolium ionic liquids. The decomposition is a result of acoustic cavitation, which generates localized hot spots from the implosive collapse of bubbles in the ionic liquids. Despite the negligible vapor pressure of the ionic liquids, reaction still occurs in a heated shell of the bubbles or from microdroplets thrown into the collapsing bubbles.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

Abstract: 1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inflammation, Apoptose, etc.)20866.2.

Handbook of Chemistry and Physics

Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis.

Abstract: The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications i...