Physics Commons^™

Size- And Composition-Dependent Structure Of Ternary Cd-Te-Se Nanoparticles, Mustafa Kurban

Turkish Journal of Physics

In this study, the geometrical, thermal, and energetic properties of zinc-blende CdTe1-xSex (x = 0.25, 0.50, and 0.75) nanoparticles were investigated using the bond order potential based on the modern classical molecular dynamics (MD) method. All MD simulations were performed using LAMMPS. Some physical properties were investigated, such as compositional variations of Cd, Te, and Se atoms; order parameter; radial distribution function; coordination number; potential energy; and heat capacity (Cv). The simulation results were compared with the available experimental results. The obtained results revealed that an increase in the composition of Se atoms can provide contributions to stability, which is …

Confined Photonic Mode Propagation Observed In Photoemission Electron Microscopy, Theodore Stenmark, Robert Campbell Word, Rolf Konenkamp

Physics Faculty Publications and Presentations

Using photoemission electron microscopy (PEEM) we present a comparative analysis of the wavelength dependence of propagating fields in a simple optical slab waveguide and a thin film photonic crystal W1-type waveguide. We utilize an interferometric imaging approach for light in the near-ultraviolet regime where a 2-photon process is required to produce photoelectron emission. The typical spatial resolution in these experiments is < 30 nm. Electromagnetic theory and finite element simulations are shown to be in good agreement with the experimental observations. Our results indicate that multiphoton PEEM is a useful sub-wavelength characterization technique in thin film optics.

Zno Nanoparticles Modulate The Ionic Transport And Voltage Regulation Of Lysenin Nanochannels, Sheenah L. Bryant, Josh E. Eixenberger, Steven Rossland, Holly Apsley, Connor Hoffman, Nisha Shrestha, Michael Mchugh, Alex Punnoose, Daniel Fologea

Physics Faculty Publications and Presentations

Background: The insufficient understanding of unintended biological impacts from nanomaterials (NMs) represents a serious impediment to their use for scientific, technological, and medical applications. While previous studies have focused on understanding nanotoxicity effects mostly resulting from cellular internalization, recent work indicates that NMs may interfere with transmembrane transport mechanisms, hence enabling contributions to nanotoxicity by affecting key biological activities dependent on transmembrane transport. In this line of inquiry, we investigated the effects of charged nanoparticles (NPs) on the transport properties of lysenin, a pore-forming toxin that shares fundamental features with ion channels such as regulation and high transport rate.

Results: …

Investigation Of Iron Oxide Nanocolloidal Suspension Diffusion Using A Direct Imaging Method, Ashley E. Rice, Ana Oprisan

Journal of the South Carolina Academy of Science

We performed a set of experiments using a direct imaging method to investigate the diffusion process of iron oxide, Fe₂O₃, nanoparticles. We studied concentration fluctuations that move against the concentration gradient and induce disturbances in the interface between the iron oxide suspension and water in the sample cell. Using this imaging method in combination with the differential dynamic algorithm for image processing, we are able to extract information about the power, size, and lifetime of the fluctuations. We performed this experiment both in the presence and in the absence of a 4.2 mT magnetic field. We …

Ion Transport Across Biological Membranes By Carborane-Capped Gold Nanoparticles, Marcin P. Grzelczak, Stephen P. Danks, Robert C. Klipp, Domagoj Belic, Adnana Zaulet, Casper Kunstmann-Olsen, Dan F. Bradley, Tatsuya Tsukuda, Clara ViñAs, Francesc Teixidor, Jonathan J. Abramson, Mathias Brust

Physics Faculty Publications and Presentations

Carborane-capped gold nanoparticles (Au/carborane NPs, 2–3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with …

Magnetic Sensing Potential Of Fe3o4 Nanocubes Exceeds That Of Fe3o4 Nanospheres, Arati G. Kolhatkar, Yi-Ting Chen, Pawilai Chinwangso, Ivan Nekrashevich, Gamage C. Dannangoda, Ankit Singh, Andrew C. Jamison, Oussama Zenasni, Irene A. Rusakova, Karen S. Martirosyan

Physics & Astronomy Faculty Publications

This paper highlights the relation between the shape of iron oxide (Fe3O4) particles and their magnetic sensing ability. We synthesized Fe3O4 nanocubes and nanospheres having tunable sizes via solvothermal and thermal decomposition synthesis reactions, respectively, to obtain samples in which the volumes and body diagonals/diameters were equivalent. Vibrating sample magnetometry (VSM) data showed that the saturation magnetization (Ms) and coercivity of 100–225 nm cubic magnetic nanoparticles (MNPs) were, respectively, 1.4–3.0 and 1.1–8.4 times those of spherical MNPs on a same-volume and same-body diagonal/diameter basis. The Curie temperature for the cubic Fe3O4 MNPs for each size was also higher …

Variations In Biocorona Formation Related To Defects In The Structure Of Single Walled Carbon Nanotubes And The Hyperlipidemic Disease State, Achyut J. Raghavendra, Kristofer Fritz, Sherleen Fu, Jared M. Brown, Ramakrishna Podila, Jonathan H. Shannahan

Publications

Ball-milling utilizes mechanical stress to modify properties of carbon nanotubes (CNTs) including size, capping, and functionalization. Ball-milling, however, may introduce structural defects resulting in altered CNT-biomolecule interactions. Nanomaterial-biomolecule interactions result in the formation of the biocorona (BC), which alters nanomaterial properties, function, and biological responses. The formation of the BC is governed by the nanomaterial physicochemical properties and the physiological environment. Underlying disease states such as cardiovascular disease can alter the biological milieu possibly leading to unique BC identities. In this ex vivo study, we evaluated variations in the formation of the BC on single-walled CNTs (SWCNTs) due to physicochemical …

Dispersion Characteristics Of Non-Newtonian Fluid During Transportation Of Nanoparticles In Permeable Capillary, Rekha Bali, Nivedita Gupta, Swati Mishra

Applications and Applied Mathematics: An International Journal (AAM)

The present analysis deals with the dispersion characteristics of blood described as Herschel- Bulkley fluid in capillary with permeable walls for fluid and impermeable for the nanoparticles. The contribution of molecular and convective diffusion is recalled from the Taylor and Aris coefficient of diffusion. The effective longitudinal diffusion depends on three parameters namely rheological parameter, pressure parameter, and the permeability parameter. We investigate the influence of the longitudinal transport of nanoparticles with permeable blood vessels on the effective dispersion. It shows that the effective diffusion of nanoparticles reduces with increase in radius of the plug region (i.e., the volume of …

Multi-Frequency Ferromagnetic Resonance Investigation Of Nickel Nanocubes Encapsulated In Diamagnetic Magnesium Oxide Matrix, Saritha Nellutla, Sudhakar Nori, Srinivasa R. Singamaneni, John T. Prater, Jagdish Narayan, Alix I. Smirnov

Chemical Sciences Faculty Publications

Partially aligned nickel nanocubes were grown epitaxially in a diamagnetic magnesium oxide (MgO:Ni) host and studied by a continuous wave ferromagnetic resonance (FMR) spectroscopy at the X-band (9.5 GHz) from ca. 117 to 458 K and then at room temperature for multiple external magnetic fields/resonant frequencies from 9.5 to 330 GHz. In contrast to conventional magnetic susceptibility studies that provided data on the bulk magnetization, the FMR spectra revealed the presence of three different types of magnetic Ni nanocubes in the sample. Specifically, three different ferromagnetic resonances were observed in the X-band spectra: a line 1 assigned to large nickel …

Slip-Jump Model For Carbon Combustion Synthesis Of Complex Oxide Nanoparticles, A. A. Markov, Mkhitar A. Hobosyan, Karen S. Martirosyan

Physics & Astronomy Faculty Publications

Carbon Combustion Synthesis of Oxides (CCSO) is a promising method to produce submicron- and nano- sized complex oxides. The CCSO was successfully utilized for producing several complex oxides, a complete theoretical model including the sample porosity, fl ow parameters and reaction energetics is needed to predict the combustion parameters for CCSO. In this work, we studied the ignition temperature and combustion wave axial temperature distribution, activation energy, combustion heat and thermal losses for a typical CCSO synthesis for cylindrical samples of Ni-Zn ferrites with high (>85%) porosity. We developed a two level combustion model of chemically active nano-dispersed mixture, …

In Vacuo Fabrication And Electronic Structure Characterization Of Atomic Layer Deposition Thin Films, Michael Schaefer

USF Tampa Graduate Theses and Dissertations

Improvement of novel electronic devices is possible by tailor-designing the electronic structure at device interfaces. Common problems observed at interfaces are related to unwanted band alignment caused by the chemical diversity of interface partners, influencing device performance negatively. One way to address this problem is by introducing ultra-thin interfacial dipole layers, steering the band alignment in a desired direction. The requirements are strict in terms of thickness, conformity and low density of defects, making sophisticated deposition techniques necessary. Atomic layer deposition (ALD) with its Ångstrom-precise thickness control can fulfill those requirements.

The work presented here encompasses the implementation of an …

Novel Magnetic And Optical Properties Of Sn1−XZnXO2 Nanoparticles, Nevil A. Franco, Kongara M. Reddy, Josh Eixenberger, Dmitri A. Tenne, Charles B. Hanna, Alex Punnoose

Physics Faculty Publications and Presentations

In this work, we report on the effects of doping SnO₂ nanoparticles with Zn²⁺ ions. A series of ∼2–3 nm sized Sn_1−x Zn_xO₂ crystallite samples with 0 ≤ x ≤ 0.18 were synthesized using a forced hydrolysis method. Increasing dopant concentration caused systematic changes in the crystallite size, oxidation state of Sn, visible emission, and band gap of SnO₂ nanoparticles. X-ray Diffraction studies confirmed the SnO₂ phase purity and the absence of any impurity phases. Magnetic measurements at room temperature showed a weak ferromagnetic behavior characterized by an open hysteresis loop. Their …

Biophysical Interaction Between Nanoparticles And Biomolecules, Slaven Radic

All Dissertations

In the last two decades nanotechnology market has undergone remarkable growth. Breakthroughs in nanomaterial synthesis increased diverse nanomaterials production and subsequently their application. Owing to its large surface to volume ratio and remarkable physical properties not seen in the bulk materials, nanoparticles are finding emerging use in industry and medicine. Hence, it is expectable that at some point these nanomaterials will end up released into the environment and interact with bio systems. The purpose of this dissertation is to elicit implications of nanomaterial transformation once it gets inside biological milieu.

Comparative Metal Oxide Nanoparticle Toxicity Using Embryonic Zebrafish, Leah C. Wehmas, Catherine Anders, Jordan Chess, Alex Punnoose, Cliff B. Pereira, Juliet A. Greenwood, Robert L. Tanguay

Physics Faculty Publications and Presentations

Engineered metal oxide nanoparticles (MO NPs) are finding increasing utility in the medical fields as anticancer agents. Before validation of in vivo anticancer efficacy can occur, a better understanding of whole-animal toxicity is required. We compared the toxicity of seven widely used semiconductor MO NPs made from zinc oxide (ZnO), titanium dioxide, cerium dioxide and tin dioxide prepared in pure water and in synthetic seawater using a five-day embryonic zebrafish assay. We hypothesized that the toxicity of these engineered MO NPs would depend on physicochemical properties. Significant agglomeration of MO NPs in aqueous solutions is common making it challenging to …

Enhanced Magnetoimpedance And Microwave Absorption Responses Of Soft Ferromagnetic Materials For Biodetection And Energy Sensing, Jagannath Devkota

USF Tampa Graduate Theses and Dissertations

A combination of magnetic sensors with magnetic nanoparticles offers a promising approach for highly sensitive, simple, and rapid detection of cancer cells and biomolecules. The challenge facing the field of magnetic biosensing is the development of low-cost devices capable of superconducting quantum interference device (SQUID)-like field sensitivity at room temperature. In another area of interest, improving the sensitivity of existing electromagnetic field sensors for microwave energy sensing applications is an important and challenging task. In this dissertation, we have explored the excellent magnetoimpedance and microwave absorption responses of soft ferromagnetic amorphous ribbons and microwires for the development of high-performance magnetic …

Additional Results For "Joint Entropy Of Continuously Differentiable Ultrasonic Waveforms" [J. Acoust. Soc. Am. 133(1), 283-300 (2013)], M S. Hughes, J N. Marsh, S A. Wickline, John E. Mccarthy

Mathematics Faculty Research

Previous results on the use of joint entropy for detection of targeted nanoparticles accumulating in the neovasculature of MDA435 tumors [Fig. 7 of M. S. Hughes et al., J. Acoust. Soc. Am. 133, 283–300 (2013)] are extended, with sensitivity improving by nearly another factor of 2. This result is obtained using a “quasi-optimal” reference waveform in the computation of the joint entropy imaging technique used to image the accumulating nanoparticles.

Ac-Susceptibility And Epr Investigations Of Superspin Dynamics In Magnetite Nanoparticles, Alex D. Price

Open Access Theses & Dissertations

In this investigation we use two complementary techniques to distinguish between superparamagnetic blocking (SPB) and superspin-glass (SSG) freezing phenomena in magnetite nanoparticles. While these manifestations of the superspin dynamics are fundamentally different, they have similar "signatures", especially in dc-magnetization experiments. Even if ac-susceptibility measurements are employed, careful use of mathematical models to analyze the data are needed to uncover which type of phenomena (SPB or SSG freezing) occurs within the material. Yet, by utilizing electron paramagnetic resonance (EPR) on a 10 nm Fe3O4 nano-powder as well as on a ferrofluid (based on the same nanoparticle ensemble) we found a very …

A Theoretical And Experimental Investigation Of The Physical And Chemical Properties Of Solid Nanoscale Interfaces, Jeronimo Matos

Electronic Theses and Dissertations

With the emerging interest in nanoscale materials, the fascinating field of surface science is rapidly growing and presenting challenges to the design of both experimental and theoretical studies. The primary aim of this dissertation is to shed some light on the physical and chemical properties of selected nanoscale materials at the interface. Furthermore, we will discuss the effective application of cutting edge theoretical and experimental techniques that are invaluable tools for understanding the systems at hand. To this effect, we use density functional theory (DFT) with the inclusion of van der Waals (vdW) interactions to study the effect of long-range …

Nanoscale Manipulation Of Pristine And Functionalized Freestanding Graphene Using Scanning Tunneling Microscopy, Matthew Ackerman

Graduate Theses and Dissertations

Over the past ten years the 2D material graphene has attracted an enourmous amount of attention from researchers from across diciplines and all over the world. Many of its outstanding electronic properties are present only when it is not interacting with a substrate but is instead freestanding. In this work I demonstrate that pristine and functionalized freestanding graphene can be imaged using a scanning tunneling microscope (STM) and that imaging a flexible 2D surface is fundamentally different from imaging a bulk material due to the attraction between the STM tip and the sample. This attraction can be used to manipulate …

Cytotoxicity Of Zno Nanoparticles Can Be Tailored By Modifying Their Surface Structure: A Green Chemistry Approach For Safer Nanomaterials, Alex Punnoose, Kelsey Dodge, John W. Rasmussen, Jordan Chess, Denise Wingett, Catherine Anders

Physics Faculty Publications and Presentations

ZnO nanoparticles (NP) are extensively used in numerous nanotechnology applications; however, they also happen to be one of the most toxic nanomaterials. This raises significant environmental and health concerns and calls for the need to develop new synthetic approaches to produce safer ZnO NP, while preserving their attractive optical, electronic, and structural properties. In this work, we demonstrate that the cytotoxicity of ZnO NP can be tailored by modifying their surface-bound chemical groups, while maintaining the core ZnO structure and related properties. Two equally sized (9.26 ± 0.11 nm) ZnO NP samples were synthesized from the same zinc acetate precursor …

Magnetism Of Zn-Doped Sno2: Role Of Surfaces, Pushpa Raghani, Balaji Ramanujam

Physics Faculty Publications and Presentations

Surface effects on the magnetization of Zn-doped SnO₂ are investigated using first principles method. Magnetic behavior of Zn-doped bulk and highest and lowest energy surfaces—(001) and (110), respectively, are investigated in presence and absence of other intrinsic defects. The Zn-doped (110) and (001) surfaces of SnO₂ show appreciable increase in the magnetic moment (MM) compared to Zn-doped bulk SnO₂. Formation energies of Zn defects on both the surfaces are found to be lower than those in bulk SnO₂. Zn doping favors the formation of oxygen vacancies. The density of states analysis on the Zn-doped …

Spin And Orbital Moments And Magnetic Order In Fe3o4 Nanoparticle Assemblies, Yanping Cai

Theses and Dissertations

Fe3O4 magnetic nanoparticles of 5 to 11 nm in size were prepared by organic methods. Particle size was analyzed by both X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. Zero Field Cooling (ZFC) / Field Cooling (FC) and magnetization loop measurements were recorded by VSM, and they confirmed superparamagnetic behavior in the sample. The blocking temperature is found to be in the range of 30 K ~ 170 K. It has a dependence on the particle size. ZFC / FC curves also indicate the presence of magnetic coupling between particles. X-ray Magnetic Circular Dichroism (XMCD) measurements of these nanoparticles …

Fracture And Failure Of Nanoparticle Monolayers And Multilayers, Yifan Wang, Pongsakorn Kanjanaboos, Edward Barry Edward Barry, Sean P. Mcbride, Xiao-Min Lin, Heinrich M. Jaeger

Physics Faculty Research

We present an experimental investigation of fracture in self-assembled gold nanoparticle mono- and multilayers attached to elastomer substrates and subjected to tensile stress. Imaging the fracture patterns down to the scale of single particles provides detailed information about the crack width distribution and allows us to compare the scaling of the average crack spacing as a function of strain with predictions by shear-lag models. With increasing particle size, the fracture strength is found to increase while it decreases as the film thickness is built up layer by layer, indicating stress inhomogeneity in the thickness dimension.

Size-Induced Chemical And Magnetic Ordering In Individual Fe–Au Nanoparticles, Pinaki Mukherjee, Priyanka Manchanda, Pankaj Kumar, Lin Zhou, Matthew J. Kramer, Arti Kashyap, Ralph Skomski, David J. Sellmyer, Jeffrey E. Shield

David Sellmyer Publications

Formation of chemically ordered compounds of Fe and Au is inhibited in bulk materials due to their limited mutual solubility. However, here we report the formation of chemically ordered L12-type Fe₃Au and FeAu₃ compounds in Fe–Au sub-10 nm nanoparticles, suggesting that they are equilib-rium structures in size-constrained systems. The stability of these L12-ordered Fe₃Au and FeAu₃ com-pounds along with a previously discovered L10-ordered FeAu has been explained by a size-dependent equilibrium thermodynamic model. Furthermore, the spin ordering of these three com-pounds has been computed using ab initio first-principle calculations. All ordered compounds exhibit a …

Inverted Linear Halbach Array For Separation Of Magnetic Nanoparticles, Chetan Poudel

Honors Papers

Magnetic nanoparticles have unique physical and chemical properties, making them appealing candidates for biomedical applications. These applications depend critically on size and magnetic uniformity of the nanoparticles. Unfortunately, very few purification methods exist to sort nanoparticles based on their magnetic properties. Here, we describe an unusual approach to this problem through our construction of a device containing a linear array of permanent magnets in a Halbach configuration, where successive magnet blocks have their magnetization orientation at right angles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient where sorting of nanoparticles based on …

Quantitative Scanning Transmission Electron Microscopy Of Thick Samples And Of Gold And Silver Nanoparticles On Polymeric Surfaces, Aniruddha Dutta

Electronic Theses and Dissertations

Transmission Electron Microscopy (TEM) is a reliable tool for chemical and structural studies of nanostructured systems. The shape, size and volumes of nanoparticles on surfaces play an important role in surface chemistry. As nanostructured surfaces become increasingly important for catalysis, protective coatings, optical properties, detection of specific molecules, and many other applications, different techniques of TEM can be used to characterize the properties of nanoparticles on surfaces to provide a path for predictability and control of these systems. This dissertation aims to provide fundamental understanding of the surface chemistry of Electroless Metallization onto Polymeric Surfaces (EMPS) through characterization with TEM. …

Fabrication Of Yttrium Ferrite Nanoparticles By Solution Combustion Synthesis, A. A. Saukhimov, Mkhitar A. Hobosyan, Gamage C. Dannangoda, N. N. Zhumabekova, S. E. Kumekov

Physics & Astronomy Faculty Publications

The ternary oxide system Y-Fe-O presents fascinating magnetic properties that are sensitive to the crystalline size of particles. There is a major challenge to fabricate these materials in nano-crystalline forms due to particle conglomeration during nucleation and synthesis. In this paper we report the fabrication of nano sized crystalline yttrium ferrite by solution combustion synthesis (SCS) where yttrium and iron nitrates were used as metal precursors with glycine as a fuel. The magnetic properties of the product can be selectively controlled by adjusting the ratio of glycine to metal nitrates. Yttrium ferrite nano-powder was obtained by using three concentration of …

Inverted Linear Halbach Array For Separation Of Magnetic Nanoparticles, Yumi Ijiri, Chetan Poudel, P. Stephen Williams, Lee R. Moore, Toru Orita, Maciej Zborowski

Faculty & Staff Scholarship

A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~5 and 20 …

Effects Of Extraneous Surface Charges On The Enhanced Raman Scattering From Metallic Nanoparticles, H. Y. Chung, P. T. Leung, D. P. Tsai

Physics Faculty Publications and Presentations

Motivating by recent experiments on surface enhanced Raman scattering (SERS) from colloidal solutions, we present here a simple model to elucidate the effects of extraneous surface charges on the enhanced Raman signal. The model is based on the well-established Gersten-Nitzan model coupled to the modified Mie scattering theory of Bohren and Hunt in the long wavelength approximation. We further introduce corrections from the modified long wavelength approximation to the Gersten-Nitzan model for the improvement of its accuracy. Our results show that the surface charge will generally lead to a blueshift in the resonance frequency and greater enhancements in the SERS …

Magnetic Properties Of Fe Doped, Co Doped, And Fe+Co Co-Doped Zno, J. J. Beltrán, J. A. Osorio, C. A. Barrero, Charles B. Hanna, A. Punnoose

Physics Faculty Publications and Presentations

The structural, electronic, and magnetic properties of Zn_0.95Co_0.05O, Zn_0.95Fe_0.05O, and Zn_0.90Fe_0.05Co_0.05O nanoparticles prepared by a sol-gel method are presented and discussed. X-ray diffraction and optical analysis indicated that high spin Co²⁺ ions substitute for the Zn²⁺ ions in tetrahedral sites. ⁵⁷Fe Mössbauer spectroscopy showed the presence of isolated paramagnetic Fe³⁺ ions in both Fe doped and Fe+Co co-doped ZnO, however, no evidence of ferromagnetically ordered Fe³⁺ ions is observed. In the Zn_0.95Fe_0.05O sample, weak presence of ZnFe …