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Selected Works

2014

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Articles 1 - 30 of 231

Full-Text Articles in Physics

Hiv-1 Tat Membrane Interactions Probed Using X-Ray And Neutron Scattering, Cd Spectroscopy And Md Simulations., Kiyotaka Akabori, Kun Huang, Bradley Treece, Michael Jablin, Brian Maranville, Arthur Woll, John Nagle, Angel Garcia, Stephanie Tristram-Nagle Dec 2014

Hiv-1 Tat Membrane Interactions Probed Using X-Ray And Neutron Scattering, Cd Spectroscopy And Md Simulations., Kiyotaka Akabori, Kun Huang, Bradley Treece, Michael Jablin, Brian Maranville, Arthur Woll, John Nagle, Angel Garcia, Stephanie Tristram-Nagle

Prof. Stephanie Tristram-Nagle Ph.D.

We report the effect on lipid bilayers of the Tat peptide Y47GRKKRRQRRR57 from the HIV-1 virus transactivator of translation (Tat) protein. Synergistic use of low-angle X-ray scattering (LAXS) and atomistic molecular dynamic simulations (MD) indicate Tat peptide binding to neutral dioleoylphosphocholine (DOPC) lipid headgroups. This binding induced the local lipid phosphate groups to move 3Å closer to the center of the bilayer. Many of the positively charged guanidinium components of the arginines were as close to the center of the bilayer as the locally thinned lipid phosphate groups. LAXS data for DOPC, DOPC/dioleoylphosphoethanolamine (DOPE), DOPC/dioleoylphosphoserine (DOPS), and a ...


What Are The True Values Of The Bending Modulus Of Simple Lipid Bilayers?, John Nagle, Michael Jablin, Stephanie Tristram-Nagle, Kiyotaka Akabori Dec 2014

What Are The True Values Of The Bending Modulus Of Simple Lipid Bilayers?, John Nagle, Michael Jablin, Stephanie Tristram-Nagle, Kiyotaka Akabori

Prof. Stephanie Tristram-Nagle Ph.D.

Values of the bending modulus KC are reviewed, and possible causes for the considerable differences are discussed. One possible cause is the use of glucose and sucrose in the classical micromechanical manipulation and shape analysis methods. New data, using the more recent low angle X-ray method, are presented that do not support an effect of glucose or sucrose on KC. Another possible cause is using an incomplete theory to interpret the data. Adding a tilt term to the theory clearly does not affect the value obtained from the shape analysis method. It is shown that a tilt term, using a ...


Suncircles: A Prose/Poem 12/18/2014, Charles Kay Smith Dec 2014

Suncircles: A Prose/Poem 12/18/2014, Charles Kay Smith

Charles Kay Smith

A current project is writing a book of poetry. The different kind of poetry I’m trying to write melds science, humanities, and aesthetic aims of clarity and a polished plain style with social consciousness. I’m uploading one of the poems in the collection as an example of the kind of poetry I’m trying to compose.


A Comparative Analysis Of Numerical Approaches To The Mechanics Of Elastic Sheets, Michael Taylor, Benny Davidovitch, Zhanlong Qiu, Katia Bertoldi Nov 2014

A Comparative Analysis Of Numerical Approaches To The Mechanics Of Elastic Sheets, Michael Taylor, Benny Davidovitch, Zhanlong Qiu, Katia Bertoldi

Benny Davidovitch

No abstract provided.


Stilling Basin Performance Analysis By Adv, Seyed Sobhan Aleyasin, Nima Fathi, Peter Vorobieff Nov 2014

Stilling Basin Performance Analysis By Adv, Seyed Sobhan Aleyasin, Nima Fathi, Peter Vorobieff

Nima Fathi

The outlet flow from dams, channels, and pipes, as well as the river flow, can cause damage to the bed of the river or channel and cause scouring of structures such as the saddles of bridges, because of the huge amount of the kinetic energy carried by the flow. One of the ways to dissipate this energy is via the use of stilling basins, which are structures that calm the flow. Here we present a study of one type of stilling basins for pipe outlets based on a widely used standard1. During the study, splitters and cellular baffles were placed ...


A Sheet On Deformable Sphere: "Wrinklogami" Patterns Suppress Curvature-Induced Delamination, Evan Hohlfeld, Benny Davidovitch Nov 2014

A Sheet On Deformable Sphere: "Wrinklogami" Patterns Suppress Curvature-Induced Delamination, Evan Hohlfeld, Benny Davidovitch

Benny Davidovitch

No abstract provided.


Non-Vacuum Ads Cosmologies And The Approach To Equilibrium Of Entanglement Entropy, Sebastian Fischetti, David Kastor, Jennie Traschen Nov 2014

Non-Vacuum Ads Cosmologies And The Approach To Equilibrium Of Entanglement Entropy, Sebastian Fischetti, David Kastor, Jennie Traschen

David Kastor

We extend standard results for vacuum asymptotically locally AdS (AlAdS) spacetimes, showing that such spacetimes can be constructed as foliations where the induced metric on each hypersurface satisfies Einstein's equation with stress-energy. By an appropriate choice of stress-energy on the hypersurfaces, the resulting AlAdS spacetime satisfies Einstein's equation with a negative cosmological constant and physical stress tensor. We use this construction to obtain AlAdS solutions whose boundaries are FRW cosmologies sourced by a massless scalar field or by a perfect fluid obeying the strong energy condition. We focus on FRW universes that approach Minkowski spacetime at late times ...


Molecular Nanoscience And Engineering On Surfaces, Willi Auwarter, Agustin Schiffrin, Alexander Weber-Bargioni, Yan Pennec, Andreas Riemann, Johannes V. Barth Nov 2014

Molecular Nanoscience And Engineering On Surfaces, Willi Auwarter, Agustin Schiffrin, Alexander Weber-Bargioni, Yan Pennec, Andreas Riemann, Johannes V. Barth

Andreas Riemann

Molecular engineering of low-dimensional materials exploiting controlled self-assembly and positioning of individual atoms or molecules at surfaces opens up new pathways to control matter at the nanoscale. Our research thus focuses on the study of functional molecules and supramolecular architectures on metal substrates. As principal experimental tools we employ low-temperature scanning tunneling microscopy and spectroscopy. Here we review recent studies in our lab at UBC: Controlled manipulation of single CO molecules, self-assembled biomolecular nanogratings on Ag(111) and their use for electron confinement, as well as the organisation, conformation, metalation and electronic structure of adsorbed porphyrins.


Assessing The Flexibility Of Research-Based Instructional Strategies: Implementing Tutorials In Introductory Physics In The Lecture Environment, Mila Kryjevskaia, Andrew Boudreaux, Dustin Heins Nov 2014

Assessing The Flexibility Of Research-Based Instructional Strategies: Implementing Tutorials In Introductory Physics In The Lecture Environment, Mila Kryjevskaia, Andrew Boudreaux, Dustin Heins

Andrew Boudreaux

Materials from Tutorials in Introductory Physics, originally designed and implemented by the Physics Education Group at the University of Washington, were used in modified form as interactive lectures under conditions significantly different from those suggested by the curriculum developers. Student learning was assessed using tasks drawn from the physics education research literature. Use of tutorials in the interactive lecture format yielded gains in student understanding comparable to those obtained through the canonical tutorial implementation at the University of Washington, suggesting that student engagement with the intellectual steps laid out in the tutorials, rather than the specific strategies used in facilitating ...


Student Understanding Of Control Of Variables: Deciding Whether Or Not A Variable Influences The Behavior Of A System, Andrew Boudreaux, Peter S. Shaffer, Paula R. L. Heron, Lillian C. Mcdermott Nov 2014

Student Understanding Of Control Of Variables: Deciding Whether Or Not A Variable Influences The Behavior Of A System, Andrew Boudreaux, Peter S. Shaffer, Paula R. L. Heron, Lillian C. Mcdermott

Andrew Boudreaux

The ability of adult students to reason on the basis of the control of variables was the subject of an extended investigation. This paper describes the part of the study that focused on the reasoning required to decide whether or not a given variable influences the behavior of a system. The participants were undergraduates taking introductory Physics and K-8 teachers studying physics and physical science in inservice institutes and workshops. Although most of the students recognized the need to control variables, many had significant difficulty with the underlying reasoning. The results indicate serious shortcomings in the preparation of future scientists ...


Preliminary Investigation Of Instructor Effects On Gender Gap In Introductory Physics, Andrew Boudreaux, Kimberley Kreutzer Nov 2014

Preliminary Investigation Of Instructor Effects On Gender Gap In Introductory Physics, Andrew Boudreaux, Kimberley Kreutzer

Andrew Boudreaux

Gender differences in student learning in the introductory, calculus-based electricity and magnetism course were assessed by administering the Conceptual Survey of Electricity and Magnetism pre- and postcourse. As expected, male students outgained females in traditionally taught sections as well as sections that incorporated interactive engagement (IE) techniques. In two of the IE course sections, however, the gains of female students were comparable to those of male students. Classroom observations of the course sections involved were made over an extended period. In this paper, we characterize the observed instructor-student interactions using a framework from educational psychology referred to as wise schooling ...


Zwitterionic Self-Assembly Of L-Methionine Nanogratings On The Ag(111) Surface, Andreas Riemann, Agustin Schiffrin, Willi Auwarter, Yan Pennec, Alex Weber-Bargioni, Albano Cossaro, Alberto Morgante, Johannes V. Barth Nov 2014

Zwitterionic Self-Assembly Of L-Methionine Nanogratings On The Ag(111) Surface, Andreas Riemann, Agustin Schiffrin, Willi Auwarter, Yan Pennec, Alex Weber-Bargioni, Albano Cossaro, Alberto Morgante, Johannes V. Barth

Andreas Riemann

The engineering of complex architectures from functional molecules on surfaces provides new pathways to control matter at the nanoscale. In this article, we present a combined study addressing the self-assembly of the amino acid L-methionine on Ag(111). Scanning tunneling microscopy data reveal spontaneous ordering in extended molecular chains oriented along high-symmetry substrate directions. At intermediate coverages, regular biomolecular gratings evolve whose periodicity can be tuned at the nanometer scale by varying the methionine surface concentration. Their characteristics and stability were confirmed by helium atomic scattering. X-ray photoemission spectroscopy and high-resolution scanning tunneling microscopy data reveal that the L-methionine chaining ...


Paul Ion Trap As A Diagnostic For Plasma Focus, S.M. Kiai, .. ., Ahmad Talaei, Et Al. Nov 2014

Paul Ion Trap As A Diagnostic For Plasma Focus, S.M. Kiai, .. ., Ahmad Talaei, Et Al.

Ahmad Talaei

The plasma discharge contamination by high and low Z Impurities affect the rate of nuclear fusion reaction products, specially when light particles have to be confined. These impurities should be analyzed and can be fairly controlled. This paper reports on the development of a Paul ion trap with ion sources by impact electron ionization as a diagnostic for the 10 kJ Iranian sunshine plasma focus device. Preliminary results of the residual gas are analyzed and presented.


Preliminary Results Of Is Plasma Focus As A Breeder Of Short-Lived Radioisotopes 12c(D,N)13n, S.M. Kiai, . ., Ahmad Talaei, Et Al. Nov 2014

Preliminary Results Of Is Plasma Focus As A Breeder Of Short-Lived Radioisotopes 12c(D,N)13n, S.M. Kiai, . ., Ahmad Talaei, Et Al.

Ahmad Talaei

Modified IS (Iranian Sun) plasma focus (10 kJ,15 kV, 94 μF, 0.1 Hz) has been used to produce the short-lived radioisotope 13N (half-life of 9.97 min) through 12C(d,n)13N nuclear reaction. The filling gas was 1.5–3 torr of hydrogen (60%) deuterium (40%) mixture. The target was solid nuclear grade graphite with 5 mm thick, 9 cm width and 13 in length. The activations of the exogenous target on average of 20 shots (only one-third acceptable) through 10–13 kV produced the 511 keV gamma rays. Another peak found at the 570 keV gamma ...


Kinematic Effects In Large Transport Aircraft, Shem Malmquist, Dennis Vincenzi, Dahai Liu Nov 2014

Kinematic Effects In Large Transport Aircraft, Shem Malmquist, Dennis Vincenzi, Dahai Liu

Dahai Liu

The control of an aircraft relies on sensory feedback. It follows that any aspect that could create a situation where that feedback is faulty can lead to unintended outcomes. The size of very large jet aircraft can result in kinematic effects that impact the perceptions of the flight crew. Due to the large amount of inertia involved, coupled with aerodynamic factors, when the aircraft pitch (θ) is initially changed, the short term actual motion of the aircraft, as viewed from the center of gravity, remains relatively unchanged. As a consequence of aircraft design, this results in the flight deck changing ...


Weak Decays Of Λ4He, J. D. Parker, M. J. Athanas, P. D. Barnes, G. Diebold, Gregg Franklin, Brian Quinn, F. Rozon, Reinhard A. Schumacher, I. Sukaton, V. J. Zeps Nov 2014

Weak Decays Of Λ4He, J. D. Parker, M. J. Athanas, P. D. Barnes, G. Diebold, Gregg Franklin, Brian Quinn, F. Rozon, Reinhard A. Schumacher, I. Sukaton, V. J. Zeps

Reinhard A Schumacher

We measured the lifetime and the mesonic and nonmesonic decay rates of the Λ4He hypernucleus. The hypernuclei were created using a 750 MeV/c momentum K- beam on a liquid 4He target by the reaction 4He (K-,π-)Λ4He. The Λ4He lifetime was directly measured using protons from Λp→np nonmesonic decay (also referred to as proton-stimulated decay) and was found to have a value of τ=245±24 ps. The mesonic decay rates were determined from the observed numbers of π-'s and π○'s as Γπ-/Γtot=0.270±0.024 and Γπ○/Γtot=0.564±0.036 ...


Plasma Focus Device As A Breeder Of 14.66 Mev Protons To Produce Short-Lived Radioisotopes, A. Zaeem, S.M. Kaia, M. Sedaghatizadeh, Ahmad Talaei Oct 2014

Plasma Focus Device As A Breeder Of 14.66 Mev Protons To Produce Short-Lived Radioisotopes, A. Zaeem, S.M. Kaia, M. Sedaghatizadeh, Ahmad Talaei

Ahmad Talaei

In plasma focus devices filled deuterium gas with low pressure admixture gas, 3He, the deuterium creates high energy protons of 14.66 MeV through the 3He(d, p) 4He(Q = 18.35 MeV) fusion reaction. This reaction takes place due to the thermal and non-thermal (beam-target) mechanisms. The proton yield production for deuterium filling gas is determined by using the beam-target character of the pinched plasma and moving boiler model. If we use a low pressure admixture gas like 11B, these high energy protons in turn, could generate short-lived radioisotopes like 11C (used in positron emission tomography) via the 11B ...


Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia Oct 2014

Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia

Ahmad Talaei

In this article, considering the most important interactions between the ionized admixture particles and the working plasma ones, we have analyzed the effect of added gas on the current and confinement time of the pinched plasma in plasma focus devices. Moreover, we demonstrate how heating and cooling the pinched plasma can be controlled by the increase and decrease on the percentage of the added particles and by this way the rise in the rate of D–D nuclear reactions is calculated.


Theoretical Study Of The Endogenous Production Of N-13 In 115 Kj Plasma Focus Device Using Methane Gas, Saeedeh Haghani, A. Sadighzadeh, Ahmad Talaei, A. Zeem, S.M. Kiai, A. Heydarnia, V. Damideh Oct 2014

Theoretical Study Of The Endogenous Production Of N-13 In 115 Kj Plasma Focus Device Using Methane Gas, Saeedeh Haghani, A. Sadighzadeh, Ahmad Talaei, A. Zeem, S.M. Kiai, A. Heydarnia, V. Damideh

Ahmad Talaei

Mather type plasma focus device with the bank energy of 115 kJ (40 kV, 144μF) was studied for induced activity of N-13; a short-lived radioisotope β+ emitter with 511 keV of gamma rays and has a half-life of t1/2 = 9.93 min through 12C (d, n)13N nuclear reaction. N-13 radioisotope is used in Positron Emission Tomography (PET) for imaging and treatment. In this paper endogenous production of 13N is considered. It is shown by adding 3–4 % CH4 to the chamber, the induced activity of N-13 has increased about 4 %. Our study is representative of producing 106 − 109 ...


Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al. Oct 2014

Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al.

Ahmad Talaei

The output characteristics of a Filippove-Type plasma focus “Dena” (288 μF, 25 kV, 90 kJ) is numerically investigated by considering the voltage, current, current derivative, and maximum current as a function of capacitor bank energy in the constant Argon gas pressure and compared to the experiment. It is shown that increase on the bank energy leads to the increment on the maximum current and decrement on the pinch time.


Effects Of Admixture Gas On The Production Of 18f Radioisotope In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia, A. Zeem Oct 2014

Effects Of Admixture Gas On The Production Of 18f Radioisotope In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia, A. Zeem

Ahmad Talaei

In this article, the effect of admixture gas on the heating and cooling of pinched plasma directly related to the enhancement or reduction of 18F production through the 16O(3He, p)18F is considered in the plasma focus devices. It is shown that by controlling the velocity of added Oxygen particles mixed with the working helium gas into the plasma focus chamber, one can increase the current and decrease the confinement time (plasma heating) or vice verse (plasma cooling). The highest level of nuclear activities of 18F was found around 16% of the Oxygen admixture ...


Study The Influence Of The Bank Energy On The Dynamical Pinch In Plasma Focus, Ahmad Talaei, S.M. Kaia Oct 2014

Study The Influence Of The Bank Energy On The Dynamical Pinch In Plasma Focus, Ahmad Talaei, S.M. Kaia

Ahmad Talaei

The plasma focus discharge can generate, accelerate and pinch the plasma up to high density and temperature in a pulsed mode manner. Applications aspects of discharge require high efficiency of the fusion products. This situation acquires optimized operational parameters for the proper discharge. In this article, we have studied the plasma parameters and neutron performance dependency on bank energy. First, analytical expressions are derived from the equation of motion for the plasma particles in the radial phase. Then, the related fusion neutrons, both thermal and non-thermal, together with the discharge anisotropy in the low pressure regimes for the ‘Dena’ plasma ...


Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar Oct 2014

Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar

Ahmad Talaei

A characteristic feature of physical processes occurring in pinched plasma is their tendency to generate thermal and nonthermal emissions. In this case, the roles played by plasma compression dynamics such as pinch formation, pinch disruption, expansion, etc., are predominant. In this paper, first, we present some of the experimental results concerning the thermal and nonthermal neutron emissions. Then, a new approach based on some theoretical assumptions and the experimental data for which the pinched plasma density evolution was studied are introduced. In the new approach, the compression dynamics are divided into two phases: plasma compression (thermal) and plasma expansion (nonthermal ...


Development Of Practical Method Using A Monte Carlo Code For Evaluation Of Optimum Fuel Pitch In A Typical Vver-1000 Core, Navid Taheranpoura, Ahmad Talaei Oct 2014

Development Of Practical Method Using A Monte Carlo Code For Evaluation Of Optimum Fuel Pitch In A Typical Vver-1000 Core, Navid Taheranpoura, Ahmad Talaei

Ahmad Talaei

In this work, we developed a practical method to evaluate the optimum moderator-to-fuel ratio of a typical VVER reactor using a Monte Carlo code. To reach this aim, by analyzing the curves of the infinite multiplication factor (k) versus moderator-to-fuel ratio, the optimum fuel pitch is determined for different fuel diameters of the proposed fuel elements using the MCNPX code. Optimum moderator-to-fuel ratio and fuel pitch were determined from the curves where the value of k is maximum for cold conditions and is located in an under-moderated region for hot conditions. Also, the void reactivity coefficient must be negative and ...


Investigation Of The High Pressure Regimes Effects On The Neutron Production In Plasma Focus, Ahmad Talaei, S.M. Kaia Oct 2014

Investigation Of The High Pressure Regimes Effects On The Neutron Production In Plasma Focus, Ahmad Talaei, S.M. Kaia

Ahmad Talaei

Effects of high pressure regimes on the thermal mechanism of neutron yield and anisotropy factor with respect to the capacitor bank energy are presented by using moving boiler model. It is found that at high pressures, the thermal fusion reactions have a considerable effect on the neutron yield and anisotropy factor. We have compared the manner of the anisotropy in two low and high pressure discharges to investigate different behavior of the anisotropy factor as a function of bank energy in the difference working regimes of pressure for Dena PF.


Viscous And Induced Current Heating In Plasma Focus Plasmoids, Ahmad Talaei, Eric Lerner Oct 2014

Viscous And Induced Current Heating In Plasma Focus Plasmoids, Ahmad Talaei, Eric Lerner

Ahmad Talaei

Recently, Abolhasani et al, proposed that the high ion energies observed in plasmoids formed in the plasma focus could be explained by viscous heating. We here elaborate this proposal, demonstrating that during plasmoid formation, ion motion along magnetic field lines can be rapidly converted, at least in part, to thermal energy through viscous diffusion. This effect is strongly enhanced by higher-z ions. We compare the theoretical predictions with the recent observation by Lerner et al, of trapped ion energies of 160 keV. In addition, we propose a second source of heating. The mildly relativistic electron beam emitted by the plasmoid ...


Magnetic And Transport Properties Of Nimnal Thin Films, Andriy Vovk, Minghui Yu, Leszek Malkinski, Charles O'Connor, Zhenjun Wang, Eden Durant, Jinke Tang, Vladimir Golub Oct 2014

Magnetic And Transport Properties Of Nimnal Thin Films, Andriy Vovk, Minghui Yu, Leszek Malkinski, Charles O'Connor, Zhenjun Wang, Eden Durant, Jinke Tang, Vladimir Golub

Jinke Tang

The magnetic and transport properties of Ni2MnAl thin films prepared using pulse laser deposition were investigated. It was shown that the films are granular and multiphase. Contrary to the data reported earlier we observe nonmonotonic temperature dependence of resistance with minimum in the vicinity of 100 K for the films deposited on substrates held at 773 K and negative magnetoresistance (MR) values of about 2.5% at 5 K and 1.6% at RT in magnetic field of 50 kOe. These values of MR are the highest reported up to date for Ni2MnAl films. Large negative ...


4f Hybridization And Band Dispersion In Gadolinium Thin Films And Compounds, Takashi Komesu, H.-K. Jeong, David Wooton, Yaroslav B. Losovyj, J. N. Crain, M. Bissen, F. J. Himpsel, J. Petrosky, Jinke Tang, Wendong Wang, I. N. Yakovkin, Peter A. Dowben Oct 2014

4f Hybridization And Band Dispersion In Gadolinium Thin Films And Compounds, Takashi Komesu, H.-K. Jeong, David Wooton, Yaroslav B. Losovyj, J. N. Crain, M. Bissen, F. J. Himpsel, J. Petrosky, Jinke Tang, Wendong Wang, I. N. Yakovkin, Peter A. Dowben

Jinke Tang

There is interplay between intra-atomic orbital hybridization and extra-atomic hybridization in various gadolinium systems, which affects magnetic coupling and electron itinerancy (localization). The results do not always follow expectation. The experimental band structure of thin Gd(0001) films, grown on the Mo(112) surface, along the Γ − M does not agree with expectations even qualitatively. In particular, the dispersion of the gadolinium band, with strong 5d weight near 2 eV binding energy provides considerable evidence to support the case for 4f- 5d hybridization, with increasing 5d localization. On the other hand, there is also evidence of extra-atomic Gd 4f hybridization ...


Effect Of Gadolinium Doping On The Electronic Band Structure Of Europium Oxide, Juan Colon Santana, Joonhee Michael An, Ning Wu, Kirill Belashchenko, Xianjie Wang, Pan Liu, Jinke Tang, Yaroslav Losovyj, I. N. Yakovkin, Peter Dowben Oct 2014

Effect Of Gadolinium Doping On The Electronic Band Structure Of Europium Oxide, Juan Colon Santana, Joonhee Michael An, Ning Wu, Kirill Belashchenko, Xianjie Wang, Pan Liu, Jinke Tang, Yaroslav Losovyj, I. N. Yakovkin, Peter Dowben

Jinke Tang

High quality films of EuO and Eu0.96Gd0.04O were grown on p-type Si(100) via pulsed laser deposition. X-raydiffraction results show that the addition of Gd changes the growth texture from [001] to [111]. Angular-resolved photoemission spectroscopy reveals electron pockets around the X points in Gd-doped EuO, indicating that the band gap in EuO is indirect. Combined photoemission and inverse photoemission measurements showan apparent transition from n-type to p-type behavior, which is likely due to band bending near the polar (111) surface.


Tribological Properties Of Fullerenes C60 And C70 Microparticles, Wei Zao, Jinke Tang, Ashok Puri, Ray L. Sweany, Yuxin Li, Liquan Chen Oct 2014

Tribological Properties Of Fullerenes C60 And C70 Microparticles, Wei Zao, Jinke Tang, Ashok Puri, Ray L. Sweany, Yuxin Li, Liquan Chen

Jinke Tang

The frictional behaviors of fullerenes C60 and C70 were studied because they were speculated to be solid lubricants. For the sublimated pure C60 films on Si(001), a high friction coefficient (0.55–0.8) was observed under different loads and pin materials. For the C70 film, the friction coefficient showed a pin dependence, which changed from 0.5 with an Al2O3 pin to about 0.9 with a 440 stainless steel pin. The relatively high friction coefficients of C60 and C70 films were due to the tendency of the C60 and C70 particles to clump and compress into high ...