We report a simple and efficient synthetic method to prepare gold nanoparticles (AuNPs) in aqueous phase using HAuCl4 and poly(ethylene glycol) (PEG) ligands appended with bidentate anchoring groups. Our approach provides narrow size distribution nanocrystals over the size range between 1.5 and 18 nm; this range is much wider than those achieved using other small molecules and polymer ligands. The NP size was simply controlled by varying the molar ratio of Au-to-PEG ligand precursors. Further...
Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC OPTICAL SCIENCES DIV, *GOLD INTERMETALLICS, *GOLD,...
In this study hybrid nanoparticles (Pd@SiO2, Au@Gd2O3) have been synthesized and characterized. Gd2O3:Eu NPs were successfully synthesized using polyol synthetic routes. Nanoparticles with an average diameter size of 1-2 nm were produced in high yield. XPS analysis confirmed the successful coating of the nanoparticles with PEGCOOH and aminocapronic acid. Palladium nanoparticles synthesized using an aqueous route was more stable in aqueous solvent than palladium nanoparticles synthesized in the...
Topics: DTIC Archive, SOUTH AUSTRALIA UNIV MAWSON LAKES (AUSTRALIA), *GOLD, *PALLADIUM, *NANOPARTICLES,...
Improvement of the operating characteristics of rolling-element bearings was sought through development and implementation of MEMS (Micro Electro-Mechanical System) based strain sensors. The strain sensors developed in this program employ a piezoresistive transducer to convert changes in applied strains to output voltages with an on-chip temperature detector compensating for thermal effects in the strain measurement. Bonding of MEMS strain sensors to application substrates was accomplished with...
Topics: DTIC Archive, TIMKEN CORP CANTON OH, *ROLLER BEARINGS, CHIPS(ELECTRONICS), SUBSTRATES,...
Improved AlNi-based ohmic contacts to p-type 4H-SiC have been achieved using low energy ion (Al+) implantation, the addition of a thin Ti layer, and a novel two-step implant activation anneal process. AlNi/Au contacts with and without Ti were studied, which resulted in contact resistivities around 1.8x10(exp -4) ohms-sq cm and 2.0x10(exp -3) ohms-sq cm, respectively. Even though these values were higher than those of the Ti/AlNi/W system, which was the focus of previous studies, the reduced...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE, *ELECTRIC...
A new technique has been developed for wirebonding mercury cadmium telluride (MCT) devices using indium spheres. Indium powder with a mesh size of 170/200 is made up of indium spheres. These spheres are used as solder between the gold pad on the MCT device and the gold ball of the wirebond. This novel technique eliminates damage that typically occurs to the MCT material under gold wirebonding pads due to force and ultrasonic power needed in wirebonding.
Topics: DTIC Archive, ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE, *BONDING,...
Glucose oxidase catalyzes the formation of metallic gold particles in immediate proximity of the protein from gold (III) chloride in the absence of any other catalytic or reductive substrates. The protein-mediated gold reduction reaction leads to size-controllable gold particle formation and concomitant association of the enzyme in an electrically conductive metallic template. Such an enzyme immobilization strategy provides a simple and rapid method to create an intimate interface between...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB TYNDALL AFB FL, *GLUCOSE, *GOLD, *NANOSTRUCTURES,...
Semiconductor quantum dots (QDs) and metal nanoparticles (NPs) have attracted a great deal of attention in the biology community due to their application as fluorescent labels and sensors. The optical properties of NPs allow them to be effective imaging agents for biomolecules. Their biological sensing abilities include identifying target DNA through a linker, followed by color change and electrical signaling. However, size-controlled NPs have the potential to be used as more than just sensors...
Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD, *DEOXYRIBONUCLEIC ACIDS, OPTICAL...
We have studied the adsorption of molecular water at the (111) surface of cerium dioxide (CeO2) singe crystals by means of atomic force microscopy (AFM) working with atomic resolution. Our AFM data reveal that single molecular water does not dissociate upon adsorption at the bare CeO2(111) surface, but it remains stably adsorbed at the surface over the temperature rage in which we have performed this study (300K to 10K). We have been able to manipulate individual water molecules with the tip of...
Topics: DTIC Archive, NATIONAL INST FOR MATERIALS SCIENCE TSUKUBA IBARAKI (JAPAN), *CERIUM COMPOUNDS,...
We report the thermal conductance G of Au/Ti/graphene/SiO2 interfaces (graphene layers 1 or = n or = 10) typical of graphene transistor contacts. We find G approx. = 25 MW/sq m/K at room temperature, four times smaller than the thermal conductance of a Au/Ti/SiO2 interface, even when n = 1. We attribute this reduction to the thermal resistance of Au/Ti/graphene and graphene/SiO2 interfaces acting in series. The temperature dependence of G from 50 , or = T or = 500 K also indicates that heat is...
Topics: DTIC Archive, ILLINOIS UNIV AT URBANA DEPT OF MATERIALS SCIENCE AND ENGINEERING, *CARBON, *THERMAL...
Topics: DTIC Archive, ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE,...
Multiwalled carbon nanotubes (MWCNTs) were functionalized with 4-mercaptobenzoic acid in a polyphosphoric acid/phosphorous pentoxide medium to produce 4-mercaptobenzoyl-functionalized MWCNTs (MB-MWCNTs). Gold nanoparticles (GNPs), stabilized by trisodium citrate, were prepared from the in-situ reduction of gold(III) chloride trihydrate by sodium borohydride in the presence of MB-MWCNTs dispersed in ethanol. The morphology of the resulting GNP/MB-MWCNT hybrid showed that GNPs were formed with an...
Topics: DTIC Archive, ULSAN NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY (KOREA SOUTH), *CARBON NANOTUBES,...
It has been a long-standing goal to create magnetism in a non-magnetic material by manipulating its structure at the nanoscale. Many structural defects have unpaired spins; an ordered arrangement of these can create a magnetically ordered state. In this article we predict theoretically that stepped silicon surfaces stabilized by adsorbed gold achieve this state by self assembly, creating chains of polarized electron spins with atomically precise structural order. The spins are localized at...
Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL MATERIALS SCIENCE,...
Fabrication of sphere-like Au nanoparticles (NPs) of fixed orientation on sapphire, GaN, and SiO2 substrates through the irradiation of a few pulses of 266-nm laser onto Au thin films deposited on the substrates was demonstrated. Numerical simulations based on the finite-element method using the experimental parameters show highly consistent localized surface plasmon resonance spectral positions and their variation trends. From the simulation results, one can also observe the relative...
Topics: DTIC Archive, NATIONAL TAIWAN UNIV TAIPEI (TAIWAN) GRADUATE INST OF ELECTRO-OPTICAL ENGINEERING,...
A detection system for theophylline that combined the recognition properties of an aptamer and that plasmonic response of gold nanoparticles (AuNPs) is presented. The aptamer was used as a linker for AuNPs functionalized with complementary sequences to the aptamer (DNA-AuNPs), producing supramolecular complexes that disassemble when exposed to theophylline due to aptamer binding. The detection event was reported as a change in the AuNPs plasmonic peak and intensity. Addition of a spacer on the...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE...
We report on the chemical synthesis, structural and compositional characterization, and hierarchical organization of Co-core, concentric CoO Au multi-shell nanocrystals (Co@CoO@Au). Based on electron microscopy, magnetometry and spectroscopy experiments, we present compelling evidence for the formation of the Au outer shell on CoO, challenging the common assumption that the reduction reaction to form Au shells can only occur if the cobalt surface has not oxidized. Our findings suggest that the...
Topics: DTIC Archive, DREXEL UNIV PHILADELPHIA PA DEPT OF MATERIALS SCIENCE AND ENGINEERING, *COBALT,...
The objective of this investigation was to explore the ability of a radio frequency (RF) signal to interact with metal nanoparticles for the purposes of remote stimulation or control of cellular processes. For this study, spherical gold nanoparticles (Au NPs, 4nm and 13 nm) and spherical silver nanoparticles (Ag NPs, 8nm) were synthesized, biofunctionalized with oligonucleotides, and hybridized through the oligonucleotide functionalization as a potential method of intracellular control. Initial...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE,...
Gold nanorods (GNRs) are of interest in many biological applications, including drug delivery and biomedical imaging due to their unique optical properties and the versatility for surface modification. For use in such applications, it is important to understand the effect of surface chemistry on the toxicological effects of GNRs to cells. In the current study, GNR stabilized with cetyltrimethylammonium bromide (GNR-CTAB) and GNR functionalized via a ligand exchange method with either thiolated...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE,...
Advances in lithium primary battery technology, which serves as the gold standard power source for the dismounted soldier, have not kept pace with the ever increasing power and energy requirements of modern military electronic equipment. Fuel cells have long been touted as the solution to the dismounted soldier's power and energy problems, but until recently, have largely failed to live up to that promise. There is still a pressing need for better power sources at the Watt or sub-Watt level,...
Topics: DTIC Archive, HONEYWELL INC MINNEAPOLIS MN HONEYWELL LABORATORIES, *FIBERS, *FUEL CELLS, *LITHIUM...
