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Effect of Program/Erase Speed on Switching Uniformity in Filament-Type RRAM
Jungho Shin,Jubong Park,Joonmyoung Lee,Sangsu Park,Seonghyun Kim,Wootae Lee,Insung Kim,Daeseok Lee,Hyunsang Hwang IEEE 2011 IEEE electron device letters Vol.32 No.7
<P>We investigated the effect of program/erase speed on switching uniformity in filament-type resistive memory with Mo/SiO<SUB>x</SUB>/Pt structure. The RRAM device exhibits a large on/off ratio (>; 10<SUP>5</SUP>), good data retention properties even at 200°C, and stable pulse-switching endurance up to 106 cycles. In comparison with slow switching operation, fast switching operation achieves more uniform program/erase performance in filament-type resistive memory. In order to determine the relationship between the switching speed and the uniformity, we carried out an effective analysis of real pulse operation.</P>
( Jungho Shin ),( Jin Ho Hwang ),( Sung Bin Park ),( Su Hyun Kim ) 대한신장학회 2023 Kidney Research and Clinical Practice Vol.42 No.4
Background: Microcirculatory dysfunction plays a critical role in sepsis-associated acute kidney injury (S-AKI) development; however, its impact on renal recovery remains uncertain. We investigated the association between cortical microcirculatory function assessed using contrast-enhanced ultrasonography (CEUS) and renal recovery after S-AKI needing renal replacement therapy (RRT). Methods: This retrospective study included 23 patients who underwent CEUS among those who underwent acute RRT for S-AKI. In addition, we acquired data from 17 healthy individuals and 18 patients with chronic kidney disease. Renal recovery was defined as sustained independence from RRT for at least 14 days. Results: Of the CEUS-derived parameters, rise time, time to peak, and fall time were longer in patients with S-AKI than in healthy individuals (p = 0.045, 0.01, and 0.096, respectively). Fourteen patients (60.9%) with S-AKI receiving RRT experienced renal recovery; and these patients had higher values of peak enhancement, wash-in area under the curve (AUC), wash-in perfusion index, and wash-out AUC than those without recovery (p = 0.03, 0.01, 0.03, and 0.046, respectively). We evaluated the receiver operating characteristic curve and found that the peak enhancement, wash-in AUC, wash-in perfusion index, and wash-out AUC of CEUS derivatives estimated the probability of renal recovery after S-AKI requiring RRT (p = 0.03, 0.01, 0.03, and 0.04, respectively). Conclusion: CEUS-assessed cortical microvascular perfusion may predict renal recovery following S-AKI that requires RRT. Further studies are essential to validate the clinical utility of microcirculatory parameters obtained from CEUS to estimate renal outcomes in various etiologies and severities of kidney disease.
Shin, Jungho,Choi, Jung-Hae,Cha, Pil-Ryung,Kim, Seong Keun,Kim, Inho,Lee, Seung-Cheol,Jeong, Doo Seok RSC Pub 2015 Nanoscale Vol.7 No.38
<P>Pt nanoparticles (NPs) in a proton exchange membrane fuel cell as a catalyst for an oxygen reduction reaction (ORR) fairly overbind oxygen and/or hydroxyl to their surfaces, causing a large overpotential and thus low catalytic activity. Realizing Pt-based core-shell NPs (CSNPs) is perhaps a workaround for the weak binding of oxygen and/or hydroxyl without a shortage of sufficient oxygen molecule dissociation on the surface. Towards the end, we theoretically examined the catalytic activity of NPs using density functional theory; each NP consists of one of 12 different 3d-5d transition metal cores (groups 8-11) and a Pt shell. The calculation results evidently suggest the enhancement of catalytic activity of CSNPs in particular when 3d transition metal cores are in use. The revealed trends in activity change upon the core metal were discussed with respect to the thermodynamic and electronic structural aspects of the NPs in comparison with the general d-band model. The disparity between the CSNP and the corresponding bilayer catalyst, which is the so-called size effect, was remarkable; therefore, it perhaps opens up the possibility of size-determined catalytic activity. Finally, the overpotential for all CSNPs was evaluated in an attempt to choose promising combinations of CSNP materials.</P>