bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collective excitations on a surface of topological insulator
Authors: Efimkin Dmitry K , Lozovik Yurii E , Sokolik Alexey A 
Published: February 2012

Abstract
We study collective excitations in a helical electron liquid on a surface of three-dimensional topological insulator. Electron in helical liquid obeys Dirac-like equation for massless particles and direction of its spin is strictly determined by its momentum. Due to this spin-momentum locking, collective excitations in the system manifest themselves as coupled charge- and spin-density waves. We develop quantum field-theoretical description of spin-plasmons in helical liquid and study their properties and internal structure. Value of spin polarization arising in the system with excited spin-plasmons is calculated. We also consider the scattering of spin-plasmons on magnetic and nonmagnetic impurities and external potentials, and show that the scattering occurs mainly into two side lobes. Analogies with Dirac electron gas in graphene are discussed.

PACS: 73.20.Mf; 73.22.Lp; 75.25.Dk.
Metabolic syndrome correlates intracoronary stenosis detected by multislice computed tomography in male subjects with sleep-disordered breathing
Authors: Nakanishi-Minami Tomoko , Kishida Ken , Nakagawa Yasuhiko , Nishio Munetaka , Nakagawa Chisa , Nishida Yoshiharu , Yanagi Koji , Yoshida Ryoko , Funahashi Tohru , Shimomura Iichiro 
Published: March 2012

Abstract

Background
Sleep-disordered breathing (SDB), especially obstructive sleep apnea (OSA), has frequent complications include hypertension, dyslipidemia and insulin resistance based on abdominal obesity or excess visceral fat (called Syndrome Z). OSA is a potential risk factor for cardiovascular diseases. The clinical characteristics of Japanese OSA subjects with OSA remain unclear. The present study investigated prevalence and predictive factors of intracoronary stenosis detected by multislice computed tomography (MSCT) in Japanese male subjects with SDB/OSA.

Findings
The study (O-VFStudy) subjects were 39 Japanese men with SDB/OSA who underwent all-night cardiorespiratory monitoring with fully attended polysomnography, and moreover both fat computed tomography (CT) scan and 64-row MSCT coronary angiography. The prevalence of coronary stenosis in this selected population with SDB/OSA was 15%. Logistic regression analysis showed a significant relationship between age-adjusted CAD and metabolic syndrome (p < 0.05), but not serum adiponectin levels and nocturnal fall in adiponectin. Subjects with the metabolic syndrome had significantly higher prevalence of CAD (31.3 versus 4.3%, p = 0.033), and lower levels of serum adiponectin (4.5 ± 0.6 versus 6.4 ± 0.6 μg/mL, p = 0.014), compared with groups without the metabolic syndrome.

Conclusions
The present study describes that the prevalence of greater than 50% intracoronary stenotic lesions detected by MSCT was 15% and the metabolic syndrome was correlated with intracoronary stenosis detected by MSCT in Japanese SDB/OSA subjects.

Trial Registration
UMIN 000002997

https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000003633&language=E.
Photoelectrochemical Reduction of Carbon Dioxide at Si(111) Electrode Modified by Viologen Molecular Layer with Metal Complex
Authors: Sun Yu , Masuda Takuya , Uosaki Kohei 
Published: February 2012

Abstract
Photoelectrochemical carbon dioxide reduction was carried out at a p-type Si(111) electrode modified with a viologen molecular layer and [AuCl4]− or [PdCl4]2−. It was proven that the reduction reaction was mediated by viologen moiety and while CO2 reduction was dominant at the Si(111) electrode modified with [PdCl4]2− in the potential region where viologen moiety was in the first reduced state, it became dominant at the electrode modified with [AuCl4]− when viologen moiety became the second reduced state. FT-IR measurement confirmed the formation of formic acid/formate ion at the [PdCl4]2−/viologen-modified Si electrode.
Highly Selective Sorption of Small Polar Molecules by a Nonporous Ionic Crystal of a Lacunary Keggin-type Heteropoly Anion and Alkali Metal Cations
Authors: Miura Yu-ki , Kamiya Yuichi 
Published: February 2012

Abstract
Cesium–potassium salt of the lacunary phosphotungstate Cs6.1K0.9[PW11O39], which is a nonporous ionic solid, absorbed only water and methanol, whereas larger alcohols (C ≥ 2) and hydrocarbons were completely excluded. Cs6.1K0.9[PW11O39] selectively removed water from water–ethanol mixed gas and was reusable by vacuum treatment at room temperature.
Organizational Structure and the Limits of Knowledge Sharing: Incentive Conflict and Agency in Car Leasing
Authors: Pierce Lamar 
Published: February 2012

This paper argues that conflicting incentives among managers may impede potential knowledge-sharing benefits from vertical integration. I study knowledge-based agency costs from vertical integration in car leasing, where manufacturer-owned captive lessors compete with independent lessors. Both organizational forms must acquire and integrate diffuse knowledge to accurately predict vehicle depreciation—a condition critical for profitability. Using a data set of 180,000 leases, I compare contracts of independent and captive lessors across car models, market conditions, and product life cycles. I find that managers in vertically integrated firms have conflicting incentives on whether to accurately and completely share proprietary knowledge, and show that these incentives appear to generate agency costs inconsistent with corporate profitability as managers selectively use and share knowledge for personal gain. The findings suggest that most knowledge benefits of vertical integration will be nullified when managerial interests are incompatible with the profit concerns of the firm.This paper was accepted by Bruno Cassiman, business strategy.
Detection of Explosives by Hyper-Spectral Differential Reflectometry
Authors: Dubroca Thierry , Hummel Rolf E. 
Published: February 2012

ABSTRACTIn the wake of the recent terrorist attacks, such as the 2008 Mumbai hotel explosion or the December 25th 2009 “underwear bomber”, our group has developed a technique (US patent #7368292) to apply differential reflective spectroscopy to the problem of detecting explosives in order to detect terrorist threats. Briefly, light (200-500 nm) is shone on a surface such as a piece of luggage at an airport or a parcel at a courier distribution center. Upon reflection, the light is collected with a spectrometer combined with a camera. A computer processes the data and produces in turn a differential reflection spectrum taken between two adjacent areas of the surface. This differential technique is highly sensitive and provides spectroscopic data of explosives. As an example, 2,4,6, trinitrotoluene (TNT) displays strong and distinct features in differential reflectograms near 420 nm. Similar, but distinctly different features are observed for other explosives such as RDX, PETN or ANFO. Our detection system uses a two dimension detector (CCD camera) which provide spatial and spectroscopic information in each of the two dimensions. By scanning (involving fixed optical equipment and scanning moving bags or parcels on a conveyor belt), the surface to be surveyed the system provide the spatial location of the potential threat. We present in this paper how our detector works and how it is applied to the problem of explosive screening for explosives at airports and mail sorting centers. Additionally, we will present the effect of the explosives morphology on the detection response. In particular we will evaluate the implication on the limit of detection of the instrument as well as discuss the sample morphology with respect to a realistic threat scenario.
Lattice Boltzmann Simulation of Transport Phenomena in Nanostructured Cathode Catalyst Layer for Proton Exchange Membrane Fuel Cells
Authors: Stiles Christopher D. , Xue Yongqiang 
Published: February 2012

ABSTRACTA multi-component, multiple-relaxation-time (MRT) lattice Boltzmann (LB) model has been employed to study transport processes in the nanostructured cathode catalyst layer of a prototype proton exchange membrane (PEM) fuel cell. The electrode consists of an array of ordered and aligned nanorods that are continuously coated with platinum (Pt). The effect of spacing between the nanorods was studied. Simulation results showed that smaller spacing in nanorods leads to lower utilization of the Pt catalyst due to O2mass transport limitations. Results from the LB model were found to be in good agreement with the continuum model using the finite element method (FEM) with the same boundary conditions until the systems reached the O2mass transport limited regions, where the solutions diverged.
The Effects of Device Dimension, Substrate Temperature, and Gate Metallization on the Reliability of AlGaN/GaN High Electron Mobility Transistors
Authors: Ren F. , Pearton S. J. , Liu Lu , Kang T.-S. , Douglas E. A. , Chang C. Y. , Lo C.-F. , Cullen D. A. , Zhou L. , Smith D. J. 
Published: February 2012

ABSTRACTThe effects of source field plates on AlGaN/GaN High Electron Mobility Transistor reliability under off-state stress conditions were investigated using step-stress cycling. The source field plate enhanced the drain breakdown voltage from 55V to 155V and the critical voltage for off-state gate stress from 40V to 65V, relative to devices without the field plate. Transmission electron microscopy was used to examine the degradation of the gate contacts. The presence of cracking that appeared on both source and drain side of the gate edges was attributed to the inverse piezoelectric effect. In addition, a thin oxide layer was observed between the Ni gate contact and the AlGaN layer, and both Ni and oxygen had diffused into the AlGaN layer. The critical degradation voltage of AlGaN/GaN High Electron Mobility Transistors during off-state electrical stress was determined as a function of Ni/Au gate dimensions (0.1-0.17μm). Devices with different gate length and gate-drain distances were found to exhibit the onset of degradation at different source-drain biases but similar electric field strengths, showing that the degradation mechanism is primarily field-driven. The temperature dependence of sub-threshold drain current versus gate voltage at a constant drain bias voltage were used to determine the trap densities in AlGaN/GaN high electron mobility transistors (HEMTs) before and after the off-state stress. Two different trap densities were obtained for the measurements conducted at 300-493K and 493-573K, respectively.
Intrinsic Paramagnetic Defects in Zirconium and Hafnium Oxide Films
Authors: Schwartz Robert N. , Muller Heinrich G. , Adams Paul M. , Barrie James D. , Lacoe Ronald C. 
Published: February 2012

ABSTRACTThin films of zirconium oxide (ZrOx) and hafnium oxide (HfOx) were rf sputtered onto fused silica substrates in an oxygen rich argon environment. Pure zirconium and hafnium targets were used, and the oxygen partial pressure was varied to control the oxygen stoichiometry. Measurement of the EPR characteristics of the ZrOx films indicated two peaks corresponding to two orientations of the magnetic field. This anisotropic response suggested the films were polycrystalline with a preferred orientation. This was confirmed by XRD pole figures. The measured g-values for the ZrOx films were less than the free-spin g-value, indicating the defects corresponded to electron traps. It was further shown that the lower the oxygen partial pressure during deposition, the larger the EPR response, strongly suggesting the traps correspond to oxygen vacancies in ZrOx. Hafnium oxide thin films were also characterized by EPR. The EPR measurements indicated the presence of a single resonance peak, suggesting these films were polycrystalline without a preferred orientation or amorphous. XRD measurements confirmed that the HfOx films were amorphous. The g-value for these films was greater than that the free-spin value, indicating the presence of possibly self-trapped oxygen hole centers. These results will be discussed in the context of prior experimental and theoretical work on these systems.
Ferroelectric and Structural Antiphase Domains in Hexagonal RMnO3
Authors: Kobayashi K. , Koyama T. , Horibe Y. , Katsufuji T. , Cheong S-W. , Mori S. 
Published: February 2012

ABSTRACTWe have investigated characteristic ferroelectric and structural antiphase domain structures in single crystals of hexagonal RMnO3 (R=Y, Ho, Lu, and Yb) by obtaining various electron diffraction patterns, dark-filed images and high-resolution lattice images. In the ferroelectric phase of RMnO3 characteristic domain structures consisting of six ferroelectric and structural antiphase domains, which can be identified as the “cloverleaf” pattern, is found in the (110) plane, in addition to the (001) plane, and are inherent to the ferroelectric phase of hexagonal RMnO3. In domain configuration with the cloverleaf pattern in the (110) plane, the structural antiphase boundaries are inclined to be parallel to the [001] direction.
Effects of Performing Resistance Exercise Before Versus After Aerobic Exercise on Glycemia in Type 1 Diabetes
Authors: Yardley Jane E. , Kenny Glen P. , Perkins Bruce A. , Riddell Michael C. , Malcolm Janine , Boulay Pierre , Khandwala Farah , Sigal Ronald J. 
Published: February 2012

OBJECTIVE
To determine the effects of exercise order on acute glycemic responses in individuals with type 1 diabetes performing both aerobic and resistance exercise in the same session.

RESEARCH DESIGN AND METHODS
Twelve physically active individuals with type 1 diabetes (HbA1c 7.1 ± 1.0%) performed aerobic exercise (45 min of running at 60% V̇o2peak) before 45 min of resistance training (three sets of eight, seven different exercises) (AR) or performed the resistance exercise before aerobic exercise (RA). Plasma glucose was measured during exercise and for 60 min after exercise. Interstitial glucose was measured by continuous glucose monitoring 24 h before, during, and 24 h after exercise.

RESULTS
Significant declines in blood glucose levels were seen in AR but not in RA throughout the first exercise modality, resulting in higher glucose levels in RA (AR = 5.5 ± 0.7, RA = 9.2 ± 1.2 mmol/L, P = 0.006 after 45 min of exercise). Glucose subsequently decreased in RA and increased in AR over the course of the second 45-min exercise bout, resulting in levels that were not significantly different by the end of exercise (AR = 7.5 ± 0.8, RA = 6.9 ± 1.0 mmol/L, P = 0.436). Although there were no differences in frequency of postexercise hypoglycemia, the duration (105 vs. 48 min) and severity (area under the curve 112 vs. 59 units ⋅ min) of hypoglycemia were nonsignificantly greater after AR compared with RA.

CONCLUSIONS
Performing resistance exercise before aerobic exercise improves glycemic stability throughout exercise and reduces the duration and severity of postexercise hypoglycemia for individuals with type 1 diabetes.
Pilot Comparative Study of Unilateral and Bilateral Robot-Assisted Training on Upper-Extremity Performance in Patients With Stroke
Authors: Yang Chieh-Ling , Lin Keh-Chung , Chen Hsieh-Ching , Wu Ching-Yi , Chen Chia-Ling 
Published: February 2012

AbstractWe compared a unilateral robot-assisted training protocol (URTP) and a bilateral robot-assisted training protocol (BRTP) to study their differential effects. We recruited 21 patients with stroke who received 90–105 min of therapy 5 days/wk for 4 wk. Participants in the URTP and BRTP groups practiced forearm pronation and supination and wrist flexion and extension in a simultaneous manner with the Bi-Manu-Track. The control group received standard rehabilitation. Clinical measures included the Fugl-Meyer Assessment, the Medical Research Council instrument, grip strength, and the Modified Ashworth Scale to assess motor impairment, muscle power, muscle strength, and spasticity, respectively. The pilot study indicated that the URTP and BRTP might have differential benefits for movement improvement. URTP might be a more compelling approach to improving upper-limb motor impairment, muscle power, and strength at the distal joints than BRTP, whereas BRTP could be an optimal approach to improving proximal muscle power.
The Thermodynamics of Molecular Recognition
Authors: Gibb Corinne L. D. , Gibb Bruce C. 
Published: February 2012

AbstractIn this review, we discuss the theoretical and practical aspects of determining the thermodynamic data for the formation of host–guests complexes. More specifically, we discuss the theory behind the free energy, enthalpy, entropy, and heat capacity changes in the formation of 1:1 complexes. We also discuss the mathematical modeling behind these determinations, and how this is tailored for the commonly utilized analytical techniques of nuclear magnetic resonance (NMR) spectrometry, UV–vis spectroscopy, and isothermal titration calorimetry (ITC). Finally, we highlight many of the important practical aspects of thermodynamic determinations using these techniques, highlighting their respective strengths and limitations. Although the focus is on 1:1 host–guest complex formation, higher order binding events are also briefly discussed.
Cooperativity and the Chelate, Macrocyclic and Cryptate Effects
Authors: Taylor Richard W. , Ara Begum Rowshan , Day Victor W. , Bowman‐James Kristin 
Published: February 2012

Abstract
The interrelationships between cooperativity and the chelate, macrocyclic, and cryptate effects are described in this chapter. The chapter begins by defining and providing a brief historical background of these four closely related effects as they pertain to both transition metal coordination chemistry and supramolecular chemistry. The second section provides an overview of bonding for supramolecular chemistry with a comparison illustrating similarities with and differences from transition metal coordination. Sections 3 and 4 describe the chemistry of the chelate, macrocyclic, and cryptate effects and the important role that cooperativity plays in each for transition metals coordination and supramolecular chemistry, respectively. Thermodynamic aspects and structural foundations for the increasing stability of complexes as they evolve from chelates through cryptates are also described. Section 4 on supramolecular chemistry is further divided into sections on the chemistry of cations, followed by anions. A short conclusion is provided at the end of the chapter. Throughout the chapter, examples are provided that illustrate the manner in which these important chemical effects are manifested.
Affinity Capillary Electrophoresis as a Tool to Characterize Intermolecular Interactions
Authors: Kiessig Steffen , Stettler Alexandra , Fuhrimann Samuel , Schwarz Maria Anna 
Published: February 2012

Abstract

The application of affinity capillary electrophoresis (ACE), a submode of capillary zone electrophoresis, to investigate the interactions between ligands and their substrates is described in this chapter. Using ACE, it is possible to characterize noncovalent molecular interactions (complexation and partition equilibria) of different binding strengths. Resulting association constants (
K
) provide a measured value of the affinity of a ligand molecule to a substrate. Starting with the background of high‐performance capillary electrophoresis (HPCE), in general, and ACE, various possibilities are given how ACE can be used in capillaries or chips. A brief mathematical description of the context between measured parameters (ionic mobility, peak area, or peak height) and evaluated binding parameters (as binding constants and stoichiometry number), as well as various ACE modes and constellations of intermolecular interacting molecules suitable for a wide range of applications are provided. Finally, selected applications are described in detail in terms of the experimental setup and estimation of the binding strength by a suitable mathematical model.
Ion Chromatography and Membrane Separations Using Macrocyclic Ligands
Authors: Lamb John D. , Li Na 
Published: February 2012

AbstractThe selectivity of macrocyclic ligand hosts in binding ionic and neutral guests was recognized early and has been applied to separations science in a number of ways. Prominent among these applications are ion chromatography (IC) and liquid membranes. This chapter summarizes the various ways by which macrocyclic ligands have been incorporated into these two separations techniques. It begins with a description of the intrinsic selectivities of the macrocyclic hosts used in these applications to date. The next section describes the basic elements of IC and the chemical features of standard ion chromatographic separations. It then proceeds to describe how macrocycles such as crown ethers, cryptands, resorcinarenes, and others have been incorporated into both the mobile and stationary phases of ion chromatographic systems to effect novel separations of both cations and anions. The development of capacity gradient chromatography of anions, unique to macrocycle‐based IC, is described. The application to both analytical separations and preconcentration/matrix elimination is also included. The next section introduces the various types of liquid membranes, including bulk liquid membranes, solid supported liquid membranes, emulsion liquid membranes, and polymer inclusion membranes. This section then proceeds to describe the various studies conducted to characterize the use of macrocyclic ligands as selective carriers of cations, anions, and neutral species across these membranes for separations purposes.
Small‐Angle
X
‐
ray
Scattering (
SAXS
) and Wide‐Angle
X
‐
ray
Scattering (
WAXS
) of Supramolecular Assemblies
Authors: Toma Adriana C. , Pfohl Thomas 
Published: February 2012

Abstract
Small‐angle X‐ray scattering (SAXS) is widely used for investigations of structures and interactions between biomacromolecules in solution. We review recent studies using SAXS for supramolecular assemblies, complex fluids, and similarly analogous systems in biology. A brief introduction is followed by a description of the available X‐ray generating instrumentation. Examples are given for the applications of microfocused X‐ray beams, and the limitations induced by radiation damage on soft matter are described. Several experimental cases are discussed: (1) properties obtained from SAXS on dilute solutions and the available software for data analysis, (2) time‐resolved SAXS on crowded systems, (3) microfluidic approaches for kinetic studies of self‐assembly processes and (4) imaging with X‐rays revealing the sample nanostructure.
Cyclodextrins: From Nature to Nanotechnology
Authors: Lincoln Stephen F. , Pham Duc‐Truc 
Published: February 2012

Abstract

Cyclodextrins (CDs) are naturally occurring homochiral macrocycles composed of α‐1,4‐linked
D
‐glucopyranose in the
4
C
1
conformation. The three smallest α‐, β‐, and γ‐CDs are composed of 6, 7, and 8 glucopyranoses, and as a class constitute one of the most widely used molecular components in supramolecular chemistry. This usage is based on the ability of CDs to complex a vast range of guests in their hydrophobic annuli in water. In this brief review, CD supramolecular chemistry is explored from simple CD complexes to increasingly complex assemblies. The modification of CDs to give desirable properties is also examined along with their supramolecular chemistry. This exploration encompasses CD host–guest complexes, enantioselectivity, polymers, catalysis, metallocyclodextrins, rotaxanes and catenanes, and molecular devices and nanomachines, some of which mimic Nature and all of which represent a fascinating aspect of supramolecular chemistry with some extraordinary possibilities for further advances and practical application.