THE PADDLE-WHEEL MODEL FOR ION CONDUCTION IN SOME SOLID PHASES

1989 ◽  
pp. 45-63 ◽  
Author(s):  
Arnold Lundén ◽  
John O. Thomas
Keyword(s):  
Ion Conduction ◽  
Paddle Wheel ◽  
Wheel Model ◽  
Solid Phases

On the Paddle -Wheel Mechanism for Cation Conduction in Lithium Sulphate

1995 ◽  
Vol 50 (11) ◽  
pp. 1067-1076 ◽  
Author(s):  
Arnold Lundén
Keyword(s):  
Solid Electrolytes ◽  
Centre Of Mass ◽  
Paddle Wheel ◽  
Plastic Crystals ◽  
Cation Migration ◽  
Lithium Sulphate ◽  
Complicated Process ◽  
Wheel Model ◽  
Group Information ◽  
Reverse Monte Carlo Method

Abstract A few high-temperature sulphate phases are both plastic crystals and solid electrolytes, the latter because the hindered rotational motion of the sulphate ions enhances the mobility of the cations. This interpretation has been called the paddle-wheel model, and it is obvious that cation migration becomes a much more complicated process in a plastic ionic crystal than in a crystal with a stiff, time-independent structure. Thus, there are strongly enhanced contributions from conventional migration mechanisms, such as jumping from well-defined lattice sites, but it is evident that there also are contributions which are specific for the paddle-wheel mechanism. By the molecular dynamics study by Ferrario, Klein and McDonald it has become possible to identify separately the contributions from centre-of-mass displacements and rotations of the sulphate group. Information in this direction has also been obtained recently by Karlsson and McGreevy in a neutron powder diffraction study where the reverse Monte Carlo method is used for modelling the data. The latter authors have modified the terminology slightly, which causes confusion regarding the meaning of the term "paddle-wheel mechanism". The "paddle-wheel" enhances not only bulk migration but also migration along interfaces and surfaces. The mobility can also be increased for monovalent anions present. Some examples are given of other types of mobility enhancements which also are due to libration or rotation of polyatomic anions.

scholarly journals A Biophysical Analysis on the Arm Stroke Efficiency in Front Crawl Swimming: Comparing Methods and Determining the Main Performance Predictors

2019 ◽  
Vol 16 (23) ◽  
pp. 4715 ◽  
Author(s):  
Peterson Silveira ◽  
Soares ◽  
Zacca ◽  
Alves ◽  
Fernandes ◽  
...  
Keyword(s):  
Swimming Performance ◽  
Speed Ratio ◽  
Metabolic Power ◽  
Free Swimming ◽  
Front Crawl ◽  
Paddle Wheel ◽  
Performance Predictors ◽  
Biophysical Analysis ◽  
Wheel Model ◽  
Ratio Speed

Purpose: to compare different methods to assess the arm stroke efficiency (?F ), whenswimming front crawl using the arms only on the Measurement of Active Drag System (MADSystem) and in a free-swimming condition, and to identify biophysical adaptations to swimming onthe MAD System and the main biophysical predictors of maximal swimming speed in the 200 mfront crawl using the arms only (?200m). Methods: fourteen swimmers performed twice a 5 × 200 mincremental trial swimming the front crawl stroke using the arms only, once swimming freely, andonce swimming on the MAD System. The total metabolic power was assessed in both conditions.The biomechanical parameters were obtained from video analysis and force data recorded on theMAD System. The ?F was calculated using: (i) direct measures of mechanical and metabolic power(power-based method); (ii) forward speed/hand speed ratio (speed-based method), and (iii) thesimplified paddle-wheel model. Results: both methods to assess ?F on the MAD System differed (p< 0.001) from the expected values for this condition (?F = 1), with the speed-based method providingthe closest values (?F~0.96). In the free-swimming condition, the power-based (?F~0.75), speedbased(?F~0.62), and paddle-wheel (?F~0.39) efficiencies were significantly different (p < 0.001).Although all methods provided values within the limits of agreement, the speed-based methodprovided the closest values to the “actual efficiency”. The main biophysical predictors of ?200mwere included in two models: biomechanical (R2 = 0.98) and physiological (R2 = 0.98). Conclusions:our results suggest that the speed-based method provides the closest values to the “actual ?F” andconfirm that swimming performance depends on the balance of biomechanical and bioenergeticparameters

Influence of Wheel Alignment and Tire Characteristics on Vehicle Drift

1998 ◽  
Vol 26 (3) ◽  
pp. 186-205 ◽  
Author(s):  
S. Yamazaki ◽  
T. Fujikawa ◽  
T. Suzuki ◽  
I. Yamaguchi
Keyword(s):  
Wheel Model ◽  
Wheel Alignment ◽  
The Relationship

Abstract Tire properties are some of the most important factors causing vehicle drift. In this paper, the influences of wheel alignment and tire properties on vehicle drift are discussed. The relationship between the wheel alignment of a vehicle and vehicle drift are examined. Also analyzed is the relationship between vehicle drift and front tire torque by using a four-wheel model while considering tire characteristics. The calculated front tire torque is compared with vehicle drift.

scholarly journals Removal of Tramp Elements within 7075 Alloy by Super-Gravity Aided Rheorefining Method

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 701 ◽  
Author(s):  
Lei Guo ◽  
Xiaochun Wen ◽  
Qipeng Bao ◽  
Zhancheng Guo
Keyword(s):  
Heat Treatment ◽  
Liquid Phase ◽  
7075 Aluminum Alloy ◽  
Total Removal ◽  
Tramp Element ◽  
Removal Ratio ◽  
Gravity Coefficient ◽  
Flow Through ◽  
Solid Phases ◽  
7075 Alloy

An investigation was made on the super-gravity aided rheorefining process of recycled 7075 aluminum alloy in order to remove tramp elements. The separation temperatures in this study were selected as 609 °C, 617 °C and 625 °C. And the gravity coefficients were set as 400 G, 700 G, 1000 G. The finely distributed impurity inclusions will aggregate to the grain boundaries of Al-enriched phase during heat treatment. In the field of super-gravity, the liquid phase composed of tramp elements Zn, Cu, Mg et al. will flow through the gaps between solid Al-enriched grains and form into filtrate. Both the weight of filtrate and removal ratio of tramp element improved with the increase of gravity coefficient. The total removal ratio of tramp element decreased with the fall of temperature due to the flowability deterioration of liquid phase. The time for effective separation of liquid/solid phases with super-gravity can be restricted within 1 min.

scholarly journals Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

scholarly journals Thermodynamics of ion binding and occupancy in potassium channels

2021 ◽  
Author(s):  
Zhifeng Jing ◽  
Joshua A. Rackers ◽  
Lawrence Pratt ◽  
Chengwen Liu ◽  
Susan B. Rempe ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Ion Binding ◽  
Cellular Functions ◽  
Ion Conduction

Potassium channels modulate various cellular functions through efficient and selective conduction of K+ ions. The mechanism of ion conduction in potassium channels has recently emerged as a topic of debate....

scholarly journals ZnOTe Compounds Grown by DC-Magnetron Co-Sputtering

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 570
Author(s):  
Olga Sánchez ◽  
Manuel Hernández-Vélez
Keyword(s):  
Molar Fraction ◽  
Variable Parameter ◽  
Point Of View ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sample Series ◽  
Solid Phases ◽  
The One ◽  
High Bulk ◽  
Substrate Sample

ZnOTe compounds were grown by DC magnetron cosputtering from pure Tellurium (Te) and Zinc (Zn) cathodes in O2/Ar atmosphere. The applied power on the Zn target was constant equal to 100 W, while the one applied on the Te target took two values, i.e., 5 W and 10 W. Thus, two sample series were obtained in which the variable parameter was the distance from the Te targets to the substrate. Sample compositions were determined by Rutherford Backscattering Spectroscopy (RBS) experiments. Structural analysis was done using X-Ray diffraction (XRD) spectrometry and the growth of the hexagonal w-ZnO phase was identified in the XRD spectra. RBS results showed high bulk homogeneity of the samples forming ZnOTe alloys, with variable Te molar fraction (MF) ranging from 0.48–0.6% and from 1.9–3.1% for the sample series obtained at 5 W and 10 W, respectively. The results reflect great differences between the two sample series, particularly from the structural and optical point of view. These experiments point to the possibility of Te doping ZnO with the permanence of intrinsic defects, as well as the possibility of the formation of other Te solid phases when its content increases. The results and appreciable variations in the band gap transitions were detected from Photoluminescence (PL) measurements.

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