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Articles 1 - 13 of 13
Full-Text Articles in Nanoscience and Nanotechnology
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mikhail Khenner
Dewetting of pulsed-laser irradiated, thin (< 20 nm), optically reflective metallic bilayers on an optically transparent substrate with a reflective support layer is studied within the lubrication equations model. A steady-state bilayer film thickness (h) dependent temperature profile is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Large thermocapillary forces are observed along the plane of the liquid-liquid and liquid-gas interfaces due to this h-dependent temperature, which, in turn, is strongly influenced by the h-dependent laser light reflection and absorption. Consequently the dewetting is a result of the competition between thermocapillary and intermolecular forces. A linear analysis of the dewetting length scales established that the non-isothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational non-linear dynamics study of the dewetting pathway was performed for Ag/Co and Co/Ag bilayer systems to predict the morphology evolution. We found that the systems evolve towards formation of different morphologies, including core-shell, embedded, or stacked nanostructure morphologies.
A Review Of International Best Practice In E-Governmentsome Lessons For New Adopters, Deogratias Harorimana Sr
A Review Of International Best Practice In E-Governmentsome Lessons For New Adopters, Deogratias Harorimana Sr
Dr Deogratias Harorimana
Efficient bureaucratic processes as essential to attract and retain investment, as well as promote SME growth. The e_Gov is one of many ways emerging economies have used to streamline public service delivery and create a freindly and conducive atmosphere for business -both MNC and SMEs. This presentation provide an overview of some of the World's most recent case examples on the successful design-plan-implementation of eGov to build a strong basis to attract investment and deliver seamless essential services to Citizens.
A Critical Review Of The Effectiveness Of Fiscal And Monetary Policies In The Pacific Island Countries (Pics) Between 1990-2010, Deogratias Harorimana Mr
A Critical Review Of The Effectiveness Of Fiscal And Monetary Policies In The Pacific Island Countries (Pics) Between 1990-2010, Deogratias Harorimana Mr
Dr Deogratias Harorimana
The purpose of this paper is to critically assess the effectiveness of Fiscal and Monetary Policies in the South Pacific Island Countries. The paper tracks down the economic growth for the last 20 years between 1990-2010, and drawing from key fiscal and monetary policies in place during the time under consideration, as well as specific interventions in the region, we find that: 1) While the South Pacific Island Countries (SPICs) particularly the six major economies (Solomon Islands, Fiji, Vanuatu, PNG, Samoa, Tonga) pursued fiscal and monetary policies for promoting growth and diversification of their economies, their fiscal policies relied heavily …
Issues In Human Capital Development : Lessons For Public Administration And Governance, Deogratias Harorimana Mr
Issues In Human Capital Development : Lessons For Public Administration And Governance, Deogratias Harorimana Mr
Dr Deogratias Harorimana
With few minerals or other natural resources, Rwanda believes that she can still achieve her ambitions by investing in human capital - her unique resource. If this ambition can be achieved, then is this the next role model for international development? We used a case study design and analysis methods to examine development models used elsewhere in recent decades, using both qualitative and quantitative data on Rwanda to establish the comparative advantages in relation to Singapore’s economic development model. The implications for international development are that (1) an effective human capital development strategy should be inclusive enough to respond to …
Investigation Of Electrical Transport In Hydrogenated Multiwalled Carbon Nanotubes, Adam Friedman, Hyunkyung Chun, Don Heiman, Yung Jung, Latika Menon
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.
Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier F. Casse, Ravinder K. Banyal, W. T. Lu, Y. J. Huang, Selvapraba Selvarasah, Mehmet R. Dokmeci, Srinivas Sridhar
Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier F. Casse, Ravinder K. Banyal, W. T. Lu, Y. J. Huang, Selvapraba Selvarasah, Mehmet R. Dokmeci, Srinivas Sridhar
Mehmet R. Dokmeci
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.
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
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.
Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Y. Voyk, Donald J. Scherer Ii, Leonard Spinu, Weillie Zhou, Scott Whittenburg, Zachary Davis, Jin-Seung Jung
Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Y. Voyk, Donald J. Scherer Ii, Leonard Spinu, Weillie Zhou, Scott Whittenburg, Zachary Davis, Jin-Seung Jung
Scott L Whittenburg
Arrays consisting of nanosized stripes of Permalloy with different length-to-width ratios have been fabricated using electron beam nanolithography, magnetron sputtering, and lift-off process. These stripes have a thickness of 100 nm, a width of 300 nm, and different lengths ranging from 300 nm to 100 μm. The stripes are separated by a distance of 1 μm. Magnetization hysteresis loops were measured using a superconducting quantum interference device susceptometer. Microwave absorption at 9.8 GHz was determined by means of ferromagnetic resonance technique. The dependence of the resonant field on the angle between the nanostructure and the in-plane dc magnetic field indicates …
Carboxymethylation Of Kappa-Carrageenan For Intestinal-Targeted Delivery Of Bioactive Macromolecules, Kok Hoong Leong
Carboxymethylation Of Kappa-Carrageenan For Intestinal-Targeted Delivery Of Bioactive Macromolecules, Kok Hoong Leong
Kok Hoong Leong
The work presented herein discusses the carboxymethylation of kappa-carrageenan, a natural linear polysaccharide, to afford a pH-dependent swelling property allowing for intestinal-targeted delivery of bioactive macromolecules. The carboxymethylation conditions with respect to the volume and concentration of sodium hydroxide (VNaOH, CNaOH), weight of monochloroacetic acid (WMCA), and reaction temperature (T) were optimized using a response surface method incorporating a multivariate spline interpolation technique (RSMS). Fluorescein isothiocyanate-labeled dextran (FD-4; 4.4 kDa) was used as a hydrophilic macromolecule model. Beads made from encapsulating FD-4 in the carboxymethylated kappa-carrageenan displayed pH-dependent swelling and encapsulation efficiency of 74%. The release of FD-4 was low …
Rh1−Xpdxnanoparticle Composition Dependence In Co Oxidation By Oxygen: Catalytic Activity Enhancement In Bimetallic Systems, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Dat Tien Hoang, Selim Alayoglu, Derek R. Butcher, Franklin Tao, Zhi Liu, Gabor A. Somorjai
Rh1−Xpdxnanoparticle Composition Dependence In Co Oxidation By Oxygen: Catalytic Activity Enhancement In Bimetallic Systems, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Dat Tien Hoang, Selim Alayoglu, Derek R. Butcher, Franklin Tao, Zhi Liu, Gabor A. Somorjai
Wenyu Huang
Bimetallic 15 nm Rh1−xPdxnanoparticle catalysts of five different compositions and supported on Si wafers have been synthesized, characterized using TEM, SEM, and XPS, and studied in CO oxidation by O2 in two pressure regimes: atmospheric pressure and 100–200 mTorr. The RhPd bimetallic nanocrystals exhibited similar synergetic effect of increased reaction activity at both atmospheric (760 Torr) and moderate (100–200 mTorr) pressures compared with pure Pd or Rh. The magnitude of the effect depends on the relative pressures of the CO and O2 reactant gases and the reaction temperature. The catalytic activity of the nanocrystals measured at moderate pressure is directly …
Rh1−X Pd X Nanoparticle Composition Dependence In Co Oxidation By No, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Gabor A. Somorjai
Rh1−X Pd X Nanoparticle Composition Dependence In Co Oxidation By No, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Gabor A. Somorjai
Wenyu Huang
Bimetallic 15 nm Pd-core Rh-shell Rh1−x Pd x nanoparticle catalysts have been synthesized and studied in CO oxidation by NO. The catalysts exhibited composition-dependent activity enhancement (synergy) in CO oxidation in high NO pressures. The observed synergetic effect is attributed to the favorable adsorption of CO on Pd in NO-rich conditions. The Pd-rich bimetallic catalysts deactivated after many hours of oxidation of CO by NO. After catalyst deactivation, product formation was proportional to the Rh molar fraction within the bimetallic nanoparticles. The deactivated catalysts were regenerated by heating the sample in UHV. This regeneration suggests that the deactivation was caused …
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine
Mikhail Khenner
The linear dispersion relation for longwave surface perturbations, as derived by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength (from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding Wulff shape). Through detailed parametric studies it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained films.
Modeling Diverse Physics Of Nanoparticle Self-Assembly In Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner
Modeling Diverse Physics Of Nanoparticle Self-Assembly In Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner
Mikhail Khenner
Presents physics behind dewetting of thin liquid films and mathematical/computational modeling tools (Educational/Research presentation for senior physics majors).