Nanoscience and Nanotechnology Commons^™

Electrodeposition Study Of Odn : Swcnt Hybrids On Gold Substrates, Roya Lahiji, Bridget Dolash, Jennifer Mcdonald, Dmitry Zemlyanov, Donald Bergstrom, R. Reifenberger

Dmitry Yurievich Zemlyanov

Sonication of short single-stranded DNA (oligodeoxyribonucleotide; ODN) with Single-Walled Carbon Nanotubes (SWCNTs) greatly facilitates the dispersion of SWCNTs from entangled ropes in an aqueous solution, creating ODN:SWCNT hybrids. Electrodeposition has been investigated to determine if well-dispersed ODN :SWCNT hybrids on a metal substrate can be created. Preliminary studies indicate that electrodeposition using an Au substrate held at +0.5 V produces ODN: SWCNT hybrids that are uniformly deposited across the Au substrate. This result can be compared to samples produced by drop casting and evaporation techniques which yield a thick tangled mat of ODN :SWCNT hybrids across the substrate. The resulting …

Controllable Surface Expression Of Bioactive Peptides Incorporated Into A Silica Thin Film Matrix, Sabrina Jedlicka, Jenna Rickus, Dmitry Zemlyanov

Dmitry Yurievich Zemlyanov

Mammalian cell culture platforms often require biomolecular modification to enhance cell adhesion and proliferation, Often, these modifications are performed using self-assembled monolayers or whole protein coatings, Such its collagen. These protocols are inherently useful but generally suffer from repeatability. Undesirable conditions during self-assembly can lead to complications in the surface presentation of the biological ligands. Whole proteins are often unstable and derived from animal sources, making them less attractive for tissue engineering applications. As the biological effect of the material often depends strongly on the concentration of the integrated ligand(s), any complication due to synthesis or stability can lead to …

Dissociation Of Water On The Surface Of Organic Salts Studied By X-Ray Photoelectron Spectroscopy, Peter Guerrieri, Dmitry Zemlyanov, Lynn Taylor

Dmitry Yurievich Zemlyanov

Water dissociation has important implications for numerous chemical processes. Although extensively studied on metals and to some extent on inorganic salts, this phenomenon has not yet been shown to occur on organic surfaces. Herein, the ability of two crystalline organic hydrochloride salts to induce water dissociation at their surface was demonstrated. Using a modified X-ray photoelectron spectroscopy setup, the oxygen lacking crystalline organic salts were exposed to high water vapor pressures within an environment sealed from ambient air. Thus, the O(1s) peak resulting from exposure to water vapor at room temperature could be unambiguously assigned to dissociated water, a phenomenon …

Assessment Of The Passivation Capabilities Of Two Different Covalent Chemical Modifications On Gap(100), David Richards, Dmitry Zemlyanov, Albena Ivanisevic

Dmitry Yurievich Zemlyanov

Gallium phosphide is a semiconductor material that can be used for the fabrication of optoelectronic devices. The report compares the ability of two similar organic molecules to form covalent bonds with the GaP(100) surface. Undecenoic acid (UDA) is a terminal alkene that can potentially form Ga-C bonds, and mercaptoundecanoic acid (MUA) is a thiol that can be used to generate Ga-S bonds. The chemical passivation capabilities of the functionalized surfaces exposed to different media were investigated by contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Toxicity levels, which are important for sensing applications. were evaluated by …

Dna Immobilization On Gap(100) Investigated By Kelvin Probe Force Microscopy, David Richards, Dmitry Zemlyanov, Rafay Asrar, Yena Chokshi, Emily Cook, Thomas Hinton, Xinran Lu, Viet Nguyen, Neil Patel, Jonathan Usher, Sriram Vaidyanathan, David Yeung, Albena Ivanisevic

Dmitry Yurievich Zemlyanov

Understanding changes in the properties of semiconductor materials after immobilization of biomolecules on the surface is essential for the fabrication of well-tuned and programmable devices. The work examines changes in the properties of gallium phosphide (GaP) after modification with an organic linker, a single stranded DNA, and its complementary strand. We investigated changes in surface potential with Kelvin probe force microscopy (KPFM). Analysis revealed that a more ordered adlayer of ssDNA was present when a lower concentration of linker molecule was used. KPFM data combined with coverage data obtained from X-ray photoelectron spectroscopy (XPS) further confirmed this result. Successful hybridization …

Electron Spectroscopy A New Window Opens, Dmitry Zemlyanov

Dmitry Yurievich Zemlyanov

No abstract provided.

Afm Study Of Ridges In Few-Layer Epitaxial Graphene Grown On The Carbon-Face Of 4h-Sic(000(1)Over-Bar), Gyan Prakash, Michael Capano, Michael Bolen, Dmitry Zemlyanov, R. Reifenberger

Dmitry Yurievich Zemlyanov

A characterization of the graphitic overlayer that forms on 4H-SiC(000 (1) over bar) substrates heated for ten minutes to temperatures T > 1350 degrees C under vacuum conditions has been performed. X-ray photoelectron spectroscopy of the C-face reveals the presence of graphitic carbon with a thickness that increases with growth temperature. Parallel atomic force microscope (AFM) studies find a mesh-like network of ridges with high curvature that bound atomically flat, tile-like facets of few-layer graphene (FLG). By imaging the network that develops on FLG, it is possible to map out the regions where the elastic energy is concentrated.

Temperature-Induced Modifications Of Pdzn Layers On Pd(111), W Stadlmayr, Ch Rameshan, C Weilach, H Lorenz, M Haevecker, R Blume, T Rocha, D Teschner, A Knop-Gericke, Dmitry Zemlyanov, S Penner, R Schloegl, G Rupprechter, B Kloetzer, N Memmel

Dmitry Yurievich Zemlyanov

Ultrathin PdZn surface alloys on Pd(111) are model systems well-suited for obtaining a microscopic understanding of the mechanisms of Pd/Zn-based catalysis for methanol steam reforming. The temperature-induced compositional and structural changes of these alloy films are investigated in the catalytically relevant temperature range. Heating of multilayer Zn films to 500 K results in the formation of multilayer PdZn alloy films with surface and near-surface composition close to 1:1. In the temperature regime above 550 K the subsurface layers deplete quickly in Zn due to diffusion of Zn atoms into the Pd bulk. In contrast, the composition of the surface layer …

Characterization Of Amino Acid Adlayers On Inas Surfaces Using X-Ray Photoelectron Spectroscopy, John Slavin, Upasana Jarori, Dmitry Zemlyanov, Albena Ivanisevic

Dmitry Yurievich Zemlyanov

Removal of surface oxide layers and the prevention of their reformation is an essential step in the use of Ill-V semiconductor technologies. Highlighted here are data exploring the use of amino acid (AA) self-assembled monolayers (SAMs) to block the pre-growth of oxides on indium arsenide surfaces. Three different AAs were used: lysine, aspartic acid, and cysteine. The adlayers were characterized by atomic force microscopy (AFM), Raman, and angle resolved X-ray photoelectron spectroscopy (ARXPS). AFM data suggest that the AA functional groups affect the packing and orientation of the molecules on the surfaces, reinforced by contact angle data. Raman data provide …

Forisome Performance In Artificial Sieve Tubes, Michael Knoblauch, Mike Stubenrauch, Aart J.E. Van Bel, Winfried S. Peters

Winfried S. Peters

Random Lasing In Bone Tissue, Qinghai Song, Shumin Xiao, Zhengbin Xu, Jingjing Liu, Xuanhao Sun, V. Drachev, V. Shalaev, Ozan Akkus, Young Kim

Zhengbin Xu

Owing to the low-loss and high refractive index variations derived from the basic building block of bone structure, we, for the first time to our knowledge, demonstrate coherent random lasing action originated from the bone structure infiltrated with laser dye, revealing that bone tissue is an ideal biological material for random lasing. Our numerical simulation shows that random lasers are extremely sensitive to subtle structural changes even at nanoscales and can potentially be an excellent tool for probing nanoscale structural alterations in real time as a novel spectroscopic modality. (C) 2010 Optical Society of America

Random Laser Spectroscopy For Nanoscale Perturbation Sensing, Qinghai Song, Shumin Xiao, Zhengbin Xu, V. Shalaev, Young Kim

Zhengbin Xu

We report a spectroscopic method using coherent random lasers for a simple, yet nanoscale, sensing approach. Unique spectral properties of coherent random laser emission can be detectably altered when introducing nanoscale perturbations to a simple nanocomposite film that consists of dielectric nanospheres and laser-dye-doped polymer to serve as a transducer. Random lasing action provides a means to amplify subtle perturbations to readily detectable spectral shifts in multiple discrete emission peaks. Owing to several advantages, such as large-area detection, narrow and multiple emission peaks, straightforward detection, and simple fabrication, random laser spectroscopy has the potential for ultrasensitive, yet simple, biosensors in …

Optically Induced Electrokinetic Patterning And Manipulation Of Particles, Stuart Williams, Aloke Kumar, Steven Wereley

Aloke Kumar

The ability to easily and dynamically control fluid mo- tion as well as manipulate particles in suspension is impor- tant for the development and characterization of a variety of lab-on-a-chip processes. Recently, we have introduced an op- tically induced electrokinetic technique termed rapid electro- kinetic patterning (REP) that can rapidly concentrate, trans- late, and pattern colloids of many different sizes and compositions. We have tested polystyrene, latex, and silica beads in sizes ranging from 49 nm to 3.0 um.1,2

Hybrid Opto-Electric Manipulation In Microfluidics-Opportunities And Challenges, Aloke Kumar, Stuart Williams, Han-Sheng Chuang, Nicolas Green, Steven Wereley

Aloke Kumar

Hybrid opto-electric manipulation in microfluidics/nanofluidics refers to a set of methodologies employing optical modulation of electrokinetic schemes to achieve particle or fluid manipulation at the micro-and nano-scale. Over the last decade, a set of methodologies, which differ in their modulation strategy and/or the length scale of operation, have emerged. These techniques offer new opportunities with their dynamic nature, and their ability for parallel operation has created novel applications and devices. Hybrid opto-electric techniques have been utilized to manipulate objects ranging in diversity from millimetre-sized droplets to nano-particles. This review article discusses the underlying principles, applications and future perspectives of various …

Experiments On Opto-Electrically Generated Microfluidic Vortices, Aloke Kumar, Stuart Williams, Steven Wereley

Aloke Kumar

Strong microfluidic vortices are generated when a near-infrared (1,064 nm) laser beam is focused within a microchannel and an alternating current (AC) electric field is simultaneously applied. The electric field is generated from a parallel-plate, indium tin oxide (ITO) electrodes separated by 50 lm. We present the first l-PIV analysis of the flow structure of such vortices. The vortices exhibit a sink-type behavior in the plane normal to the electric field and the flow speeds are characterized as a function of the electric field strength and biasing AC signal frequency. At a constant AC frequency of 100 kHz, the fluid …

All-Spin Logic Device With Inbuilt Nonreciprocity, Srikant Srinivasan, Angik Sarkar, Behtash Behin-Aein, Supriyo Datta

Srikant Srinivasan

The need for low-power alternatives to digital electronic circuits has led to increasing interest in logic devices where information is stored in nanomagnets. This includes both nanomagnetic logic, where information is communicated through magnetic fields of nanomagnets, and all-spin logic (ASL), where information is communicated through spin currents. A key feature needed for logic implementation is nonreciprocity, whereby the output is switched according to the input but not the other way around, thus providing directed information transfer. The objective of this paper is to draw attention to possible ASL-based schemes that utilize the physics of spin-torque to build in nonreciprocity, …

Purely Electronic Switching With High Uniformity, Resistance Tunability, And Good Retention In Pt-Dispersed Sio2 Thin Films For Reram, Albert Chen

Albert B Chen

Resistance switching memory operating by a purely electronic switching mechanism, which was first realized in Pt-dispersed SiO2 thin films, satisfies criteria including high uniformity, fast switching speed, and long retention for non-volatile memory application. This resistive element obeys Ohm's law for the area dependence, but its resistance exponentially increases with the film thickness, which provides new freedom to tailor the device characteristics.

Metamaterials On Parylene Thin Film Substrates: Design, Fabrication, And Characterization At Terahertz Frequency, Xianliang Liu, Samuel Macnaughton, David Shrekenhamer, Hu Tao, Selvapraba Selvarasah, Atcha Totachawattana, Richard Averitt, Mehmet Dokmeci, Sameer Sonkusale, Willie Padilla

Mehmet R. Dokmeci

We design, fabricate, and characterize terahertz (THz) resonant metamaterials on parylene free-standing thin film substrates. Several different metamaterials are investigated and our results show strong electromagnetic responses at THz frequencies ranging from 500 GHz to 2.5 THz. The complex frequency dependent dielectric properties of parylene are determined from inversion of reflection and transmission data, thus indicating that parylene is an ideal low loss substrate or coating material. The biostable and biocompatible properties of parylene coupled with the multifunctional exotic properties of metamaterials indicate great potential for medical purposes such as THz imaging for skin cancer detection.

Direct Measurement Of Graphene Adhesion On Silicon Surface By Intercalation Of Nanoparticles, Zong Zong, Chia-Ling Chen, Mehmet Dokmeci, Kai-Tak Wan

Mehmet R. Dokmeci

We report a technique to characterize adhesion of monolayered/multilayered graphene sheets on silicon wafer. Nanoparticles trapped at graphene-silicon interface act as point wedges to support axisymmetric blisters. Local adhesion strength is found by measuring the particle height and blister radius using a scanning electron microscope. Adhesion energy of the typical graphene-silicon interface is measured to be 151±28 mJ/m2. The proposed method and our measurements provide insights in fabrication and reliability of microelectromechanical/nanoelectromechanical systems.

Low-Voltage And Short-Channel Pentacene Field-Effect Transistors With Top-Contact Geometry Using Parylene-C Shadow Masks, Yoonyoung Chung, Boris Murmann, Selvapraba Selvarasah, Mehmet Dokmeci, Zhenan Bao

Mehmet R. Dokmeci

We have fabricated high-performance top-contact pentacene field-effect transistors using a nanometer-scale gate dielectric and parylene-C shadow masks. The high-capacitance gate dielectric, deposited by atomic layer deposition of aluminum oxide, resulted in a low operating voltage of 2.5 V. The flexible and conformal parylene-C shadow masks allowed fabrication of transistors with channel lengths of L = 5, 10, and 20 μm. The field-effect mobility of the transistors was μ = 1.14 (±0.08) cm²/V s on average, and the IMAX/IMIN ratio was greater than 10⁶.

Mechanical And Electrical Evaluation Of Parylene-C Encapsulated Carbon Nanotube Networks On A Flexible Substrate, Chia-Ling Chen, Ernesto Lopez, Yung-Joon Jung, Sinan Müftü, Selvapraba Selvarasah, Mehmet Dokmeci

Sinan Müftü

Carbon nanotube networks are an emerging conductive nanomaterial with applications including thin film transistors, interconnects, and sensors. In this letter, we demonstrate the fabrication of single-walled carbon nanotube (SWNT) networks on a flexible polymer substrate and then provide encapsulation utilizing a thin parylene-C layer. The encapsulated SWNT network was subjected to tensile tests while its electrical resistance was monitored. Tests showed a linear-elastic response up to a strain value of 2.8% and nearly linear change in electrical resistance in the 0%–2% strain range. The networks’ electrical resistance was monitored during load-unload tests of up to 100 cycles and was hysteresis-free.

Investigation Of Electrical Transport In Hydrogenated Multiwalled Carbon Nanotubes, Adam Friedman, Hyunkyung Chun, Don Heiman, Yung Jung, Latika Menon

Latika Menon

Highly disordered multiwalled carbon nanotubes of large outer diameter (~60 nm) fabricated by means of chemical vapor deposition process inside porous alumina templates exhibit ferromagnetism when annealed in a H2/Ar atmosphere. In the presence of an applied magnetic field, there is a transition from positive to negative magnetoresistance. The transition may be explained in terms of the Bright model for ordered and disordered carbon structures. Additionally, temperature dependent electrical transport experiments exhibit a zero-bias anomaly at low temperature.

Separation Modes In Microcontacts Identified By The Rate Dependence Of The Pull-Off Force, L. Chen, Nicol Mcgruer, George Adams, Yan Du

Nicol E. McGruer

We report the observation of two distinct modes of rate-dependent behavior during contact cycling tests. One is a higher pull-off force at low cycling rates and the other is a higher pull-off force at high cycling rates. Subsequent investigation of these contacts using scanning electron microscopy (SEM) demonstrates that these two rate-dependent modes can be related to brittle and ductile separation modes. The former behavior is indicative of brittle separation, whereas the latter accompanies ductile separation. Thus by monitoring the rate dependence of the pull-off force, the type of separation mode can be identified during cycling without interrupting the test …

Parallel Arrays Of Individually Addressable Single-Walled Carbon Nanotube Field-Effect Transistors, Sarah Lastella, Govind Mallick, Raymond Woo, Shashi Karna, David Rider, Ian Manners, Yung-Joon Jung, Chang Ryu, Pulickel Ajayan

Yung Joon Jung

High-throughput field-effect transistors (FETs) containing over 300 disentangled, high-purity chemical-vapor-deposition-grown single-walled carbon nanotube (SWNT) channels have been fabricated in a three-step process that creates more than 160 individually addressable devices on a single silicon chip. This scheme gives a 96% device yield with output currents averaging 5.4 mA and reaching up to 17 mA at a 300 mV bias. Entirely semiconducting FETs are easily realized by a high current selective destruction of metallic tubes. The excellent dispersity and nearly-defect-free quality of the SWNT channels make these devices also useful for nanoscale chemical and biological sensor applications.

Toxicity Of Cdse Nanoparticles In Caco-2 Cell Cultures, Lin Wang, Dattatri Nagesha, Selvapraba Selvarasah, Mehmet Dokmeci, Rebecca Carrier

Mehmet R. Dokmeci

Background
Potential routes of nanomaterial exposure include inhalation, dermal contact, and ingestion. Toxicology of inhalation of ultra-fine particles has been extensively studied; however, risks of nanomaterial exposure via ingestion are currently almost unknown. Using enterocyte-like Caco-2 cells as a small intestine epithelial model, the possible toxicity of CdSe quantum dot (QD) exposure via ingestion was investigated. Effect of simulated gastric fluid treatment on CdSe QD cytotoxicity was also studied.

Results
Commercially available CdSe QDs, which have a ZnS shell and poly-ethylene glycol (PEG) coating, and in-house prepared surfactant coated CdSe QDs were dosed to Caco-2 cells. Cell viability and attachment …

Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier Casse, Ravinder Banyal, W. Lu, Y. Huang, Selvapraba Selvarasah, Mehmet Dokmeci, Srinivas Sridhar

Srinivas Sridhar

We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 μm that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.

Münch, Morphology, Microfluidics – Our Structural Problem With The Phloem [Review Article], Michael Knoblauch, Winfried S. Peters

Winfried S. Peters

Knowledge, Capabilities And Manufacturing Innovation: A Us-Europe Comparison, Stephen Roper, Jan Youtie, Philip Shapira, Andrea Fernandez-Ribas

Andrea Fernandez-Ribas

This paper presents a comparative analysis of factors contributing to the innovation performance of manufacturing firms in Georgia (USA), Wales (UK), the West Midlands (UK), and Catalonia (Spain). Enabled by comparable survey data, multivariate probit models are developed to estimate how various types of firms’ innovative activities are influenced by links to external knowledge sources, internal resources, absorptive capacity, and public innovation support. The results suggest the potential for mutual learning. For the European study regions there are insights about how universities in Georgia support innovation. For Georgia and Catalonia there are lessons from UK firms about better capturing potential …

Anisotropic Contraction In Forisomes: Simple Models Won't Fit, Winfried Peters, Michael Knoblauch, Stephen Warmann, William Pickard, Amy Shen

Winfried S. Peters

Tailed Forisomes Of Canavalia Gladiata: A New Model To Study Ca2+-Driven Protein Contractility, Winfried Peters, Michael Knoblauch, Stephen Warmann, Reinhard Schnetter, Amy Shen, William Pickard

Winfried S. Peters