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Full-Text Articles in Physical Sciences and Mathematics
Thin Polyimide Films Prepared By Ionic Self-Assembly, Mark Anderson, Richey Davis, C. Douglas Taylor, Michiaiah Parker, Spencer Clark, Daniela Marciu, Michael Miller
Thin Polyimide Films Prepared By Ionic Self-Assembly, Mark Anderson, Richey Davis, C. Douglas Taylor, Michiaiah Parker, Spencer Clark, Daniela Marciu, Michael Miller
Mark R. Anderson
Layer-by-layer electrostatic deposition of polyelectrolytes was used to modify a gold substrate with polydiallyl dimethylammonium chloride and an Ultem-type poly(amic acid) salt. Following deposition, heat treatment converted the poly(amic acid) salt into a polyimide. A decrease in the thin film thickness and a substantial increase in the interfacial contact angle accompanied thermal treatment. Results from cyclic voltammetry measurements also show that the imidized surface had a decreased dielectric constant relative to an unmodified or a poly(amic acid)-modified interface. Each of these results is consistent with formation of the polyimide. Infrared spectra of the thin films formed by the electrostatic deposition …
Dopamine Adsorption At Surface Modified Carbon-Fiber Electrodes, Bradley Bath, Heidi Martin, R. Mark Wightman, Mark Anderson
Dopamine Adsorption At Surface Modified Carbon-Fiber Electrodes, Bradley Bath, Heidi Martin, R. Mark Wightman, Mark Anderson
Mark R. Anderson
Fast-scan cyclic voltammetry at high repetition rates was used to characterize adsorptive properties of dopamine (DA) at native and modified carbon-fiber microelectrode surfaces. Disk electrodes were fabricated from Thornel P55 fibers, and cylindrical electrodes, from Thornel T650 fibers. Their surfaces were modified by physisorption of 2,6-anthraquinone disulfonic acid (2,6-AQDS) or chemisorption of 4-carboxyphenyl or catechols. Chemisorption was accomplished via electrochemical reduction of diazonium salts. The degree of DA adsorption and its oxidation kinetics were found to vary for the two types of native carbon fiber electrodes and with the different chemical overlayers on the carbon surfaces. 2,6-AQDS measurably increased DA …
The Evidence Of The Mode Selectivity Of The Infrared Predissociation Reaction Of The Hydrogen Bonds In The Aniline–Water–Pyrrole Cluster Cation, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
The Evidence Of The Mode Selectivity Of The Infrared Predissociation Reaction Of The Hydrogen Bonds In The Aniline–Water–Pyrrole Cluster Cation, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
Naveed K. Piracha
The infrared spectrum of aniline–water–pyrrole cluster cation has been measured in the 3 μm region. Four strong vibrational bands were observed at 3313, 3515, 3637, and 3721cm−1, and the cluster dissociated into fragments in two reaction paths, AWP+→AW++P and AWP+→AP++W (A: aniline, W: water, P: pyrrole) when it absorbed an infrared photon. The branching ratio (AW+/AP+) has been determined to be 0.20±0.02 for the NH stretching vibration of aniline (3313cm−1, hydrogen-bonded to pyrrole) and 0.14±0.03 for the other three bands. This vibrational mode dependence should be due to the fast energy transfer from the NH to the intermolecular vibration through …
Transport Properties Of Bi2−Xinxse3 Single Crystals., J. Navrátil, T. Plecháček, J. Horák, S. Karamazov, P. LošŤÁK, Jeffrey Dyck, W. Chen, C. Uher
Transport Properties Of Bi2−Xinxse3 Single Crystals., J. Navrátil, T. Plecháček, J. Horák, S. Karamazov, P. LošŤÁK, Jeffrey Dyck, W. Chen, C. Uher
Jeffrey Dyck
The paper reports on the temperature dependence of the electrical and thermal conductivity, Hall constant, and Seebeck coefficient of Bi2−xInxSe3 (x=0, 0.2, 0.4) single crystals measured over the temperature range from 2 to 300 K. One single-valley conduction band model is used to interpret relations among transport coefficients. The data analysis relies on the use of a mixed carrier scattering mechanism consisting of acoustic scattering and scattering on ionized impurities. The effect of In incorporation into the Bi2Se3 crystal lattice on the individual components of thermal conductivity is evaluated and discussed. Copyright 2001 Academic Press.
Anomalous Barium Filling Fraction And N-Type Thermoelectric Performance Of Ba[Sub Y]Co[Sub 4]Sb[Sub 12]., L. Chen, T. Kawahara, X. Tang, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
Anomalous Barium Filling Fraction And N-Type Thermoelectric Performance Of Ba[Sub Y]Co[Sub 4]Sb[Sub 12]., L. Chen, T. Kawahara, X. Tang, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
Jeffrey Dyck
Barium-filled skutterudites BaCoSb with an anomalously large filling fraction of up to y=0.44 have been synthesized. The lattice parameters increase linearly with Ba content. Magnetic susceptibility data show that BaCoSb is paramagnetic, which implies that some of the Co atoms in BaCoSb have acquired a magnetic moment. The presence of the two different valence states of Co (Co3+ and Co2+) leads to the anomalously large barium filling fraction even without extra charge compensation. All samples show n-type conduction. The electrical conductivity increases with increasing the Ba filling fraction. The lattice thermal conductivity of BaCoSb is significantly depressed as compared to …
Third Generation Seesaw Mixing With New Vector-Like Weak-Doublet Quarks, Marko Popovic
Third Generation Seesaw Mixing With New Vector-Like Weak-Doublet Quarks, Marko Popovic
Marko B. Popovic
We present a class of models with a third generation seesaw mixing with new vectorlike weak-doublet quarks. We analyze a low-energy phenomenology and present several strong dynamics, high-energy realizations of these models. In the top-color-type scenario, named top-bottom color, we obtain an effective, composite two Higgs doublet model where the third generation isospin splitting is introduced via tilting interactions related to the broken non-Abelian gauge groups @i.e., without strong, triviality-sensitive U~1! groups#. In addition, we discuss t t ¯ production at the Next Linear Collider and suggest how one can experimentally observe and distinguish between the weak-doublet and the weak-singlet …
Stability Of A Pivoting Strategy For Parallel Gaussian Elimination, Jodi Mead, R. Renaud, B. Welfert
Stability Of A Pivoting Strategy For Parallel Gaussian Elimination, Jodi Mead, R. Renaud, B. Welfert
Jodi Mead
Gaussian elimination with partial pivoting achieved by adding the pivot row to the kth row at step k, was introduced by Onaga and Takechi in 1986 as means for reducing communications in parallel implementations. In this paper it is shown that the growth factor of this partial pivoting algorithm is bounded above by n <#60; 3 n–1, as compared to 2 n–1 for the standard partial pivoting. This bound n, close to 3 n–2, is attainable for class of near-singular matrices. Moreover, for the same matrices the growth factor is small under partial pivoting.
Kinetics Of Substitution Of Weakly Coordinating Nitrate By Chloride In (Η5-Cp)Ru(Co)(Er3)Ono2 (Er3 = Asph3, Pph3, P(P-Anisyl)3, Pph2(O-Anisyl), P(Oph)3) In Dichloromethane., Minhton Cao, Liem Do, Norris Hoffman, Man Lung Kwan, Julie Little, J. Mcgilvray, Christopher Morris, Bjorn Söderberg, Andrzej Wierzbicki, Thomas Cundari, Charles Lake, Edward Valente
Kinetics Of Substitution Of Weakly Coordinating Nitrate By Chloride In (Η5-Cp)Ru(Co)(Er3)Ono2 (Er3 = Asph3, Pph3, P(P-Anisyl)3, Pph2(O-Anisyl), P(Oph)3) In Dichloromethane., Minhton Cao, Liem Do, Norris Hoffman, Man Lung Kwan, Julie Little, J. Mcgilvray, Christopher Morris, Bjorn Söderberg, Andrzej Wierzbicki, Thomas Cundari, Charles Lake, Edward Valente
Man Lung Desmond Kwan
The d6 complexes of formula (η5-Cp)Ru(CO)(ER3)ONO2, where ER3 = AsPh3, PPh3, P(p-anisyl)3, PPh2(o-anisyl), and P(OPh)3, were prepared by reaction of their chloro analogues with AgNO3 in CH2Cl2. They underwent moderately slow substitution of the relatively weakly coordinating nitrate by chloride in dry CH2Cl2 in the presence of excess [N(PPh3)2+]Cl-. A kinetics study showed the reaction to be first order in nitrato complex and independent of chloride salt concentration under pseudo-first-order conditions. First-order rate constants for nitrate metathesis follow the trend P(OPh)3 < PPh3 < P(p-anisyl)3 < AsPh3 PPh2(o-anisyl), with k1 at 25 °C for the first four in the series from 1.4 to 4.4 × 10-5 s-1. Activation parameters for conversion of (η5-Cp)Ru(CO)(AsPh3)ONO2 to its chloride are ΔH‡ = 17(2) kcal/mol and ΔS‡ = −21(5) eu. Even use of a slightly moist solvent increased the rate of nitrate metathesis by 20−30% without changing the form of the rate law. The complex containing PPh2(o-anisyl) was approximately 2 orders of magnitude more reactive (k1 = 4.9 × 10-3 s-1). A likely explanation is stabilization of a coordinatively unsaturated intermediate by weak coordination of the potentially chelating o-OMe group. A mechanism entailing rate-limiting conversion of the neutral nitrato complex into a coordinatively unsaturated ion-paired species is consistent with this set of data. Semiempirical calculations (PM3(tm)), which model the structures of complexes in these systems quite well, supported such behavior. X-ray crystal structures were determined for the AsPh3 nitrato and chloro complexes and for the PPh3 chloro complex.
Investigation Of The Structure Of T He Ternary Cluster Of Aniline−Water−Tetrahydrofuran And Its Cation By Infrared Depletion Spectroscopy, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
Investigation Of The Structure Of T He Ternary Cluster Of Aniline−Water−Tetrahydrofuran And Its Cation By Infrared Depletion Spectroscopy, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito
Naveed K. Piracha
No abstract provided.
Environmental Justice And Southern California's “Riskscape” The Distribution Of Air Toxics Exposures And Health Risks Among Diverse Communities, James Sadd
James Sadd
Past research on “environmental justice” has often failed to systematically link hazard proximity with quantifiable health risks. The authors employ recent advances in air emissions inventories and modeling techniques to consider a broad range of outdoor air toxics in Southern California and to calculate the potential lifetime cancer risks associated with these pollutants. They find that such risks are attributable mostly to transportation and small-area sources and not the usually targeted large-facility pollution emissions. Multivariate regression suggests that race plays an explanatory role in risk distribution even after controlling for other economic, land-use, and population factors. This pattern suggests the …
Stereoselective One-Pot Synthesis Of Vinylsilanes From Aromatic Aldehydes, Man Lung Kwan, Chiu Yeung, Kerry Breno, Kenneth Doxsee
Stereoselective One-Pot Synthesis Of Vinylsilanes From Aromatic Aldehydes, Man Lung Kwan, Chiu Yeung, Kerry Breno, Kenneth Doxsee
Man Lung Desmond Kwan
Vinylsilanes serve as convenient vinyl anion equivalents, but procedures for their stereoselective synthesis from aldehydes are scarce. A variety of aromatic aldehydes are converted to the corresponding vinylsilanes in a one-pot procedure involving the addition of (trimethylsilylmethyl)lithium to the aldehyde followed by treatment with Cp2TiCH2·AlMe2Cl (‘Tebbe's reagent’). Halide and alkoxide substituents are tolerated, and (E)-vinylsilanes are formed exclusively in good yield.
A2bi8se1 3 (A = Rb, Cs), Csbi3.67se6, And Babi2< /Inf>Se4: New Ternary Semiconducting Bismuth Selenides, Lykourgis Iordanidis, Paul Brazis, Theodora Kyratsi, John Irel, Melissa Lane, Carl Kannewurf, Wei Chen, Jeffrey Dyck, Ctirad Uher, Nishant Ghelani, Tim Hogan, Mercouri Kanatzidis
A2bi8se1 3 (A = Rb, Cs), Csbi3.67se6, And Babi2< /Inf>Se4: New Ternary Semiconducting Bismuth Selenides, Lykourgis Iordanidis, Paul Brazis, Theodora Kyratsi, John Irel, Melissa Lane, Carl Kannewurf, Wei Chen, Jeffrey Dyck, Ctirad Uher, Nishant Ghelani, Tim Hogan, Mercouri Kanatzidis
Jeffrey Dyck
No abstract provided.
The Y-Triangle Move Does Not Preserve Intrinsic Knottedness, Ramin Naimi, Erica Flapan
The Y-Triangle Move Does Not Preserve Intrinsic Knottedness, Ramin Naimi, Erica Flapan
Ramin Naimi
We answer the question "Does the Y-triangle move preserve intrinsic knottedness?" in the negative by giving an example of a graph that is obtained from the intrinsically knotted graph K_7 by triangle-Y and Y-triangle moves but is not intrinsically knotted.
The Influence Of Ni On The Transport Properties Of Cosb3, C. Uher, Jeffrey Dyck, W. Chen, G. Meisner, J. Yang
The Influence Of Ni On The Transport Properties Of Cosb3, C. Uher, Jeffrey Dyck, W. Chen, G. Meisner, J. Yang
Jeffrey Dyck
The effect of Ni doping on the Co site of the binary skutterudite CoSb3 is investigated. We measured resistivity, Hall effect, magnetoresistance, thermopower, thermal conductivity, and magnetization of a series of samples of the form Co1-xNixSb3 with x in the range x=0 to x=0.01. We find that Ni takes the tetravalent state Ni4+, assumes the d6 electronic configuration for the lower energy non-bonding orbitals, and gives an electron to the conduction band. Ni doping dramatically suppresses the thermal conductivity, changes the temperature dependence of the thermopower, and increases the carrier concentration. Low temperature anomalies in thermopower, Hall coefficient and magnetoresistance …
Low Temperature Thermoelectric Properties Of Ni Doped N-Type Filled Skutterudites Ba0.3co4sb12 ., W. Chen, Jeffrey Dyck, C. Uher, L. Chen, X. Tang, T. Hirai
Low Temperature Thermoelectric Properties Of Ni Doped N-Type Filled Skutterudites Ba0.3co4sb12 ., W. Chen, Jeffrey Dyck, C. Uher, L. Chen, X. Tang, T. Hirai
Jeffrey Dyck
n-type Ba filled skutterudites doped with Ni, Ba0.3Ni xCo4-xSb12 with 0⩽x⩽0.2, have been synthesized and the Seebeck coefficient, thermal conductivity, electrical resistivity and Hall coefficient have been measured. ZT of 1.2 has been achieved at 800 K with x=0.05. The thermal conductivity data are fitted and the rattling effect of the Ba atoms is identified through a resonance scattering term. The Hall mobility is studied and a mixed scattering mechanism of acoustic phonons and ionized impurities based on a single, rigid band picture is presented. The role of Ni atoms in enhancing the thermoelectric performance is discussed
Multi-Filling Approach For The Improvement Of Thermoelectric Properties Of Skutterudites., L. Chen, X. Tang, T. Kawahara, Jeffrey Dyck
Multi-Filling Approach For The Improvement Of Thermoelectric Properties Of Skutterudites., L. Chen, X. Tang, T. Kawahara, Jeffrey Dyck
Jeffrey Dyck
Several skutterudite antimonides filled with atoms of different kinds, (Ba, M)yCo4Sb12 (M=Ce, La, Sr), have been synthesized by the combination of solid state reaction and melting methods. Thermal conductivity of (Ba,Sr)yCo4 Sb12 samples shows a behavior similar to that of BayCo4Sb12. Adding a small amount of Ce or La to the BayCo4Sb12 system is effective in further reducing the lattice thermal conductivity. The difference in the ionic radii of the two co-filler atoms is the most sensitive factor for scattering of phonons. The multi-filled (Ba, M)yCo4Sb12 (M=Sr, Ce, La) show lower Seebeck coefficients as compared to the single-filled BayCo 4Sb12 …
High-Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Zhang, R. Yuan, L. Chen, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
High-Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Zhang, R. Yuan, L. Chen, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
Jeffrey Dyck
Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type BayNixCo4-xSb12 (x = 0-0.1, y = 0.-0.4) were investigated at temperature range of 300 to 900 K. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When y was fixed at 0.3, thermal conductivity decreased with increasing Ni content and reached a minimum value at about x = 0.05. Lattice thermal conductivity decreased with increasing Ni content, monotonously (y ≤ 0.1). Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature and decreased with increasing …
Femtosecond Polarization Detection Using High-Speed Pulse Shaping, D. Keusters, Peifang Tian, W. Warren
Femtosecond Polarization Detection Using High-Speed Pulse Shaping, D. Keusters, Peifang Tian, W. Warren
Peifang Tian
This book presents the latest advances in ultrafast science, including ultrafast laser and measurement technology as well as studies of ultrafast phenomena. Pico- and femtosecond processes relevant in physics, chemistry, biology and engineering are presented. Ultrafast technology has had a profound impact in a wide range of applications, among them imaging, material diagnostics and transformation and high-speed optoelectronics. This book summarizes the results presented at the 12th Ultrafast Phenomena Conference and reviews the state of the art of this important and rapidly advancing field.
Preparation And Some Physical Properties Of Tetradymite-Type Sb2te3 Single Crystals Doped With Cds., P. LošŤÁK, Č. Drašar, A. Krejc ̆ Ova, L. Beneš, Jeffrey Dyck, W. Chen, C. Uher
Preparation And Some Physical Properties Of Tetradymite-Type Sb2te3 Single Crystals Doped With Cds., P. LošŤÁK, Č. Drašar, A. Krejc ̆ Ova, L. Beneš, Jeffrey Dyck, W. Chen, C. Uher
Jeffrey Dyck
Single crystals of Sb2Te3 doped with CdS were prepared by a modified Bridgman method from the elements Sb and Te of 5N purity and the CdS compound of 4.5N purity. Samples were characterized by X-ray diffraction and by measurement of reflectance in the plasma resonance frequency region at room temperature. Furthermore, we made measurements of temperature dependence of the electrical resistivity, Hall and Seebeck coefficients, and thermal conductivity in the temperature range of 4.2–300K. In the process of crystal growth, CdS dissociated and it was assumed that the Cd-atoms formed substitutional defects in the Sb-sublattice (CdSb′) while the S-atoms formed …
Ima Journal Of Management Mathematics,, Ron Buckmire, David Edwards
Ima Journal Of Management Mathematics,, Ron Buckmire, David Edwards
Ron Buckmire
No abstract provided.
Synthesis And High Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Chen, T. Goto, Jeffrey Dyck
Synthesis And High Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Chen, T. Goto, Jeffrey Dyck
Jeffrey Dyck
Single-phase filled skutterudite compounds BayNx Co4-xSb12 (x=0-0.1, y=0-0.4) were synthesized by a two-step solid state reaction. Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type Ba yNixCo4-xSb12 were investigated. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When barium filling fraction (y) was fixed at 0.3, the thermal conductivity decreased with increasing Ni content, and reached a minimum value at about x=0.05. Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature, and decreased with increasing Ba filling fraction and Ni content. A …
Thermoelectric Properties Of Yb-Filled And Sn-Compensated Skutterudites ., Jihui Yang, Gregory Meisner, Wei Chen, Jeffrey Dyck, Ctirad Uher
Thermoelectric Properties Of Yb-Filled And Sn-Compensated Skutterudites ., Jihui Yang, Gregory Meisner, Wei Chen, Jeffrey Dyck, Ctirad Uher
Jeffrey Dyck
The effect of alloying tin on the antimony site of ytterbium-filled skutterudites is examined. We performed measurements of Hall effect, electrical resistivity, Seebeck coefficient and thermal conductivity on the series Yb0.5Co4Sb12-x Snx, with x=0.5, 0.6, 0.8 and 0.83. We find that the substitution of tin does not alter the position of the Fermi level with respect to the conduction band of these heavily doped semiconducting samples, but rather it gives rise to a p-type band. Experimental data for x=0.83 can be understood in the context of a two-carrier electrical conduction. Thermal conductivity of these ytterbium-filled skutterudites is significantly suppressed with …
Geomagnetic Field Behavior Before And After The Kauai Reverse-Normal Polarity Transition, Scott Bogue
Geomagnetic Field Behavior Before And After The Kauai Reverse-Normal Polarity Transition, Scott Bogue
Scott Bogue
New paleomagnetic results from 4 m.y. old lava flows from Kauai, Hawaii, suggest that strong poloidal field is associated with an unusual state of the geodynamo that follows attempts at polarity reversal (successful or not). The new data comprise 50 paleomagnetic sites from superposed lava flows occurring just below and above the Kauai reverse-normal polarity transition. A composite record of 45 distinct field determinations was constructed by combining sites that record similar ancient field and correlating them to previously published results from Kauai. Of the 45 data, 25 include paleointensity estimates derived from double-heating experiments. A comparison of the composite …
Transport And Magnetic Properties Of Co1-Xnixsb3 With X Less Than 0.01, Jeffrey Dyck, W. Chen, Y. Yang, G. Meisner, C. Uher
Transport And Magnetic Properties Of Co1-Xnixsb3 With X Less Than 0.01, Jeffrey Dyck, W. Chen, Y. Yang, G. Meisner, C. Uher
Jeffrey Dyck
The filled skutterudite compounds based on the binary skutterudite CoSb3 are currently being investigated for their potential application as thermoelectric materials. One route to optimization of these compounds is by doping on the Co site. An obvious candidate for an n-type dopant is Ni, because it has one more electron in its valence shell than Co. We present electrical resistivity, thermopower, Hall effect and magnetic susceptibility measurements on polycrystalline, n-type Co1-xNixSb3 with x less than 0.01. A model which takes into account conduction of electrons residing in the conduction band in addition to hopping conduction within an impurity "band" formed …