On the Origin of Potential Barrier for the Reaction OH-+ CO2→ HCO3-in Water:  Studies by Using Continuum and Cluster Solvation Methods

2002 ◽  
Vol 106 (7) ◽  
pp. 1734-1740 ◽  
Author(s):  
Alexander V. Nemukhin ◽  
Igor A. Topol ◽  
Bella L. Grigorenko ◽  
Stanley K. Burt
Keyword(s):  
Potential Barrier ◽  
Cluster Solvation

The potential barrier height for a Jahn-Teller center

2004 ◽  
Vol 99 (1) ◽  
pp. 189-196 ◽  
Author(s):  
V. N. Vasyukov ◽  
A. D. Prokhorov ◽  
V. P. D’yakonov ◽  
H. Szymczak
Keyword(s):  
Barrier Height ◽  
Potential Barrier ◽  
Potential Barrier Height ◽  
Jahn Teller

Bereaved Informal Caregivers Rarely Recall a Relationship Between Transfusions and Hospice in Acute Myeloid Leukemia

2021 ◽  
pp. 104990912110132
Author(s):  
Larry D. Cripe ◽  
Ann H. Cottingham ◽  
Caroline E. Martin ◽  
Mary Lynn Hoffmann ◽  
Katherine Sargent ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
End Of Life ◽  
Potential Barrier ◽  
Myeloid Leukemia ◽  
Informal Caregivers ◽  
Blood Transfusions ◽  
Enrollment Decisions ◽  
To Receive ◽  
Acute Myeloid

Aims: The inability to prescribe blood transfusions is a potential barrier to timely hospice enrollment for patients with blood cancers. The benefits and harms of transfusions near the end of life (EOL), however, are poorly characterized and patients’ preferences are unknown. We sought to characterize the recollections of bereaved caregivers about the relationships between transfusions and hospice enrollment decisions. Methods: We recruited 18 bereaved caregivers of 15 decedents who died within 6-18 months of the interview. Interviews focused on caregivers’ recollections of transfusion and hospice enrollment decisions. Transcripts were analyzed for themes. Results: We identified 2 themes. First, caregivers described that transfusions were necessary and the decisions to receive transfusions or not were deferred to the clinicians. Second, only 1 caregiver recalled transfusions as relevant to hospice decisions. In that instance there was a delay. Caregivers identified difficulties recognizing death was imminent, hope for miracles, and the necessity of accepting life was ending as more relevant barriers. Conclusions: The results indicate clinicians’ beliefs in transfusion at EOL may be a more relevant barrier to hospice enrollment than patients’ preferences. Strategies to evaluate accurately and discuss the actual benefits and harms of transfusions at the EOL are necessary to advise patients and integrate their preferences into decisions.

scholarly journals Effects of Charge Compensation on Colossal Permittivity and Electrical Properties of Grain Boundary of CaCu3Ti4O12 Ceramics Substituted by Al3+ and Ta5+/Nb5+

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3294
Author(s):  
Jakkree Boonlakhorn ◽  
Jedsada Manyam ◽  
Pornjuk Srepusharawoot ◽  
Sriprajak Krongsuk ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Barrier Height ◽  
Potential Barrier ◽  
Charge Compensation ◽  
Solid State Reaction Method ◽  
Wide Frequency Range ◽  
Potential Barrier Height

The effects of charge compensation on dielectric and electrical properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics (x = 0−0.05) prepared by a solid-state reaction method were studied based on the configuration of defect dipoles. A single phase of CaCu3Ti4O12 was observed in all ceramics with a slight change in lattice parameters. The mean grain size of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics was slightly smaller than that of the undoped ceramic. The dielectric loss tangent can be reduced by a factor of 13 (tanδ ~0.017), while the dielectric permittivity was higher than 104 over a wide frequency range. Impedance spectroscopy showed that the significant decrease in tanδ was attributed to the highly increased resistance of the grain boundary by two orders of magnitude. The DFT calculation showed that the preferential sites of Al and Nb/Ta were closed together in the Ti sites, forming self-charge compensation, and resulting in the enhanced potential barrier height at the grain boundary. Therefore, the improved dielectric properties of CaCu3Ti4-x(Al1/2Ta1/4Nb1/4)xO12 ceramics associated with the enhanced electrical properties of grain boundaries. In addition, the non-Ohmic properties were also improved. Characterization of the grain boundaries under a DC bias showed the reduction of potential barrier height at the grain boundary. The overall results indicated that the origin of the colossal dielectric properties was caused by the internal barrier layer capacitor structure, in which the Schottky barriers at the grain boundaries were formed.

Sign in / Sign up

Export Citation Format

Share Document