scholarly journals Order–disorder transition of a rigid cage cation embedded in a cubic perovskite

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhifang Shi ◽  
Zheng Fang ◽  
Jingshu Wu ◽  
Yi Chen ◽  
Qixi Mi
Keyword(s):  
Organic Cation ◽  
Driving Forces ◽  
Molecular Reorientation ◽  
Design Synthesis ◽  
Disorder Transition ◽  
Lattice Symmetry ◽  
Nmr Crystallography ◽  
Inorganic Framework ◽  
Abrupt Rise ◽  
And Calorimetry

AbstractThe structure and properties of organic–inorganic hybrid perovskites are impacted by the order–disorder transition, whose driving forces from the organic cation and the inorganic framework cannot easily be disentangled. Herein, we report the design, synthesis and properties of a cage-in-framework perovskite AthMn(N3)3, where Ath+ is an organic cation 4-azatricyclo[2.2.1.02,6]heptanium. Ath+ features a rigid and spheroidal profile, such that its molecular reorientation does not alter the cubic lattice symmetry of the Mn(N3)3− host framework. This order–disorder transition is well characterized by NMR, crystallography, and calorimetry, and associated with the realignment of Ath+ dipole from antiferroelectric to paraelectric. As a result, an abrupt rise in the dielectric constant was observed during the transition. Our work introduces a family of perovskite structures and provides direct insights to the order–disorder transition of hybrid materials.

scholarly journals Order–Disorder Transition of a Rigid Cage Cation Embedded in a Cubic Perovskite

2021 ◽  
Author(s):  
Zhifang Shi ◽  
Zheng Fang ◽  
Jingshu Wu ◽  
Yi Chen ◽  
Qixi Mi
Keyword(s):  
Organic Cation ◽  
Driving Forces ◽  
Molecular Reorientation ◽  
Design Synthesis ◽  
Disorder Transition ◽  
New Family ◽  
Nmr Crystallography ◽  
Inorganic Framework ◽  
Abrupt Rise ◽  
And Calorimetry

Abstract The structure and properties of organic–inorganic hybrid perovskites are impacted by the order–disorder transition, whose driving forces from the organic cation and the inorganic framework cannot easily be disentangled. Herein, we report the design, synthesis and properties of a cage-in-framework perovskite AthMn(N3)3, where Ath+ is an organic cation 4-azatricyclo[2.2.1.02,6]heptanium. Ath+ features a rigid and spheroidal profile, such that its molecular reorientation does not alter the cubic lattice symmetry of the Mn(N3)3− host framework. This pure order–disorder transition is well characterized by NMR, crystallography, and calorimetry, and associated with the realignment of Ath+ dipole from antiferroelectric to paraelectric. As a result, an abrupt rise in the dielectric constant was observed during the transition. Our work introduces a new family of perovskite structures and provides direct insights to the order–disorder transition of hybrid materials.

rOCT2 is a basolateral potential-driven carrier, not an organic cation/proton exchanger

1999 ◽  
Vol 277 (6) ◽  
pp. F890-F898 ◽  
Author(s):  
Douglas H. Sweet ◽  
John B. Pritchard
Keyword(s):  
Organic Cation ◽  
Driving Forces ◽  
Cell Clone ◽  
Mdck Cells ◽  
Rat Kidney ◽  
Ph Effect ◽  
Physiological Role ◽  
Organic Cation Transporter ◽  
Ph Sensitive ◽  
Medium Ph

The driving forces mediating tetraethylammonium (TEA) transport were systematically assessed in Xenopus oocytes and MDCK cells expressing organic cation transporter (OCT) 2 cloned from rat kidney (rOCT2). In rOCT2 cRNA-injected oocytes, uptake of [14C]TEA was saturable, with an estimated Michaelis constant ( K m) of 393 μM, and was specifically inhibited by organic cations. Furthermore, TEA uptake demonstrated two distinct components, one that was potential sensitive and one that was pH sensitive. When membrane potential was intact, TEA uptake was largely unaffected by changes in medium pH; when the oocyte membrane was depolarized (K+ in = out = 102.5 mM, plus valinomycin), decreasing external medium pH significantly reduced TEA uptake. Consistent with the potential sensitivity of uptake, electrophysiological analysis of rOCT2-injected oocytes demonstrated movement of positive charge into the oocyte upon TEA addition. To further evaluate the nature of the pH effect and assess the properties of rOCT2 in a renal epithelium, rOCT2 was introduced into MDCK cells. A stably transfected single cell clone (MDCK-rOCT2) showed mediated, potential-sensitive, pH-sensitive TEA uptake ( K m = 48 μM). TEA efflux from preloaded MDCK-rOCT2 cells was stimulated by externally applied ( trans) tetramethylammonium but was trans-inhibited by H+ (external pH 5.4). The effect of external H+ was to modulate rOCT2-mediated transport. Thus rOCT2 is a potential-driven transporter, not an organic cation/H+exchanger, consistent with a physiological role in the basolateral entry step in renal organic cation secretion.

Interface Mobility Under Different Driving Forces

2002 ◽  
Vol 17 (1) ◽  
pp. 234-245 ◽  
Author(s):  
M. I. Mendelev ◽  
D. J. Srolovitz ◽  
L. S. Shvindlerman ◽  
G. Gottstein
Keyword(s):  
External Field ◽  
Driving Force ◽  
Material Parameter ◽  
Driving Forces ◽  
Boundary Migration ◽  
The Other ◽  
Boundary Mobility ◽  
Circular Boundary ◽  
Lattice Symmetry ◽  
Half Loop

We used an Ising model to determine whether boundary mobility is an intrinsic material parameter or if it depends on the nature of the driving force for boundary migration. The simulations included both capillarity and external field-driven boundary migration. The external field-driven, flat boundary simulations showed that boundary mobility depends strongly on boundary inclination at low temperature but not at high temperature. On the other hand, the boundary mobility in capillarity-driven migration shows no dependence on boundary inclination and is independent of the boundary migration geometry. An initially circular grain shrinks as a circle and a half-loop boundary retracts with profiles predicted under the assumption that the boundary mobility is isotropic during capillarity-driven migration even when the temperature is very low and the external-field-driven boundary migration is extremely anisotropic. However, when an external field is superimposed on the capillarity driven migration of the circular boundary, the circular grain exhibits well-defined corners consistent with the simulation lattice symmetry. In this case, the boundary mobility is much different than if the external field were omitted. This is a clear demonstration that the boundary mobility can depend on the nature of the driving force for boundary migration.

Computer Indexing of Electron Diffraction Patterns Including the Effects of Lattice Symmetry

1977 ◽  
Vol 35 ◽  
pp. 22-23
Author(s):  
J. S. Lally ◽  
R. J. Lee
Keyword(s):  
Electron Diffraction ◽  
Zone Axis ◽  
Crystal Thickness ◽  
Double Diffraction ◽  
Automated Method ◽  
Lattice Symmetry ◽  
Intensity Calculations ◽  
Unknown Structure ◽  
Diffraction Patterns ◽  
Orientation Parameters

In the 50 year period since the discovery of electron diffraction from crystals there has been much theoretical effort devoted to the calculation of diffracted intensities as a function of crystal thickness, orientation, and structure. However, in many applications of electron diffraction what is required is a simple identification of an unknown structure when some of the shape and orientation parameters required for intensity calculations are not known. In these circumstances an automated method is needed to solve diffraction patterns obtained near crystal zone axis directions that includes the effects of systematic absences of reflections due to lattice symmetry effects and additional reflections due to double diffraction processes.Two programs have been developed to enable relatively inexperienced microscopists to identify unknown crystals from diffraction patterns. Before indexing any given electron diffraction pattern, a set of possible crystal structures must be selected for comparison against the unknown.

Solute redistribution during in-situ irradiation of alloys in the high voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 370-371
Author(s):  
P. R. Okamoto ◽  
N.Q. Lam ◽  
R. L. Lyles
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Driving Forces ◽  
Solute Diffusion ◽  
Solute Redistribution ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Thin Foils ◽  
Solute Atoms

During irradiation of thin foils in a high voltage electron microscope (HVEM) defect gradients will be set up between the foil surfaces and interior. In alloys defect gradients provide additional driving forces for solute diffusion since any preferential binding and/or exchange between solute atoms and mobile defects will couple a net flux of solute atoms to the defect fluxes. Thus, during irradiation large nonequilibrium compositional gradients can be produced near the foil surfaces in initially homogeneous alloys. A system of coupled reaction-rate and diffusion equations describing the build up of mobile defects and solute redistribution in thin foils and in a semi-infinite medium under charged-particle irradiation has been formulated. Spatially uniform and nonuniform damage production rates have been used to model solute segregation under electron and ion irradiation conditions.An example calculation showing the time evolution of the solute concentration in a 2000 Å thick foil during electron irradiation is shown in Fig. 1.

Chronic Pain: Fundamental Scientific Considerations, Specifically for Legal Claims

2013 ◽  
Vol 18 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Robert J. Barth
Keyword(s):  
Health Outcomes ◽  
Pain Perception ◽  
Driving Forces ◽  
Psychological Treatment ◽  
Dominant Role ◽  
Meta Analysis ◽  
General Medicine ◽  
Pain Syndrome ◽  
Problematic Relationship

Abstract Scientific findings have indicated that psychological and social factors are the driving forces behind most chronic benign pain presentations, especially in a claim context, and are relevant to at least three of the AMA Guides publications: AMA Guides to Evaluation of Disease and Injury Causation, AMA Guides to Work Ability and Return to Work, and AMA Guides to the Evaluation of Permanent Impairment. The author reviews and summarizes studies that have identified the dominant role of financial, psychological, and other non–general medicine factors in patients who report low back pain. For example, one meta-analysis found that compensation results in an increase in pain perception and a reduction in the ability to benefit from medical and psychological treatment. Other studies have found a correlation between the level of compensation and health outcomes (greater compensation is associated with worse outcomes), and legal systems that discourage compensation for pain produce better health outcomes. One study found that, among persons with carpal tunnel syndrome, claimants had worse outcomes than nonclaimants despite receiving more treatment; another examined the problematic relationship between complex regional pain syndrome (CRPS) and compensation and found that cases of CRPS are dominated by legal claims, a disparity that highlights the dominant role of compensation. Workers’ compensation claimants are almost never evaluated for personality disorders or mental illness. The article concludes with recommendations that evaluators can consider in individual cases.

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