Three-Dimensional Visualization of Oxygen-Vacancy Migration and Redistribution in Ca-Substituted BiFeO3.

Ionic movement has received renewed attention in recent years, particularly in the field of ferroelectric oxides, since it is intrinsically linked to chemical reaction kinetics and ferroelectric phase stability. The associated surface electrochemical processes coupled local ionic transport with an applied electric bias, exhibiting very high ionic mobility at room temperature based on a simple electrostatics scenario. However, few studies have focused on the applied-polarity dependence of ionic migration with directly visualized maps. Here, we use incorporated experiments of conductive scanning probe microscopy and time-of-flight secondary ion mass spectrometry to investigate oxygen ionic migration and cation redistribution in ionic oxides. The local concentrations of oxygen vacancies and other cation species are visualized by three-dimensional mappings, indicating that oxygen vacancies tend to be ejected toward the surface. An accumulation of oxygen vacancies and ionic redistribution strongly depend on tip polarity, thus corroborating their role in the electrochemical process. This work illustrates the interplay between ionic kinetics and electric switching.

Critical ionic transport across an oxygen-vacancy ordering transition.

Phase transition points can be used to critically reduce the ionic migration activation energy, which is important for realizing high-performance electrolytes at low temperatures. Here, we demonstrate a route toward low-temperature thermionic conduction in solids, by exploiting the critically lowered activation energy associated with oxygen transport in Ca-substituted bismuth ferrite (Bi1-xCaxFeO3-δ) films. Our demonstration relies on the finding that a compositional phase transition occurs by varying Ca doping ratio across xCa ≃ 0.45 between two structural phases with oxygen-vacancy channel ordering along <100> or <110> crystal axis, respectively. Regardless of the atomic-scale irregularity in defect distribution at the doping ratio, the activation energy is largely suppressed to 0.43 eV, compared with ~0.9 eV measured in otherwise rigid phases. From first-principles calculations, we propose that the effective short-range attraction between two positively charged oxygen vacancies sharing lattice deformation not only forms the defect orders but also suppresses the activation energy through concerted hopping.

Harnessing the topotactic transition in oxide heterostructures for fast and high-efficiency electrochromic applications.

Mobile oxygen vacancies offer a substantial potential to broaden the range of optical functionalities of complex transition metal oxides due to their high mobility and the interplay with correlated electrons. Here, we report a large electro-absorptive optical variation induced by a topotactic transition via oxygen vacancy fluidic motion in calcium ferrite with large-scale uniformity. The coloration efficiency reaches ~80 cm2 C-1, which means that a 300-nm-thick layer blocks 99% of transmitted visible light by the electrical switching. By tracking the color propagation, oxygen vacancy mobility can be estimated to be 10-8 cm2 s-1 V-1 near 300°C, which is a giant value attained due to the mosaic pseudomonoclinic film stabilized on LaAlO3 substrate. First-principles calculations reveal that the defect density modulation associated with hole charge injection causes a prominent change in electron correlation, resulting in the light absorption modulation. Our findings will pave the pathway for practical topotactic electrochromic applications.

EUS-Guided Versus Percutaneous Celiac Neurolysis for the Management of Intractable Pain Due to Unresectable Pancreatic Cancer: A Randomized Clinical Trial.

Although endoscopic ultrasound-guided celiac neurolysis (EUS-CN) and percutaneous celiac neurolysis (PCN) are utilized to manage intractable pain in pancreatic cancer patients, no direct comparison has been made between the two methods. We compared the efficacy and safety of EUS-CN and PCN in managing intractable pain in such patients. Sixty pancreatic cancer patients with intractable pain were randomly assigned to EUS-CN (n = 30) or PCN (n = 30). The primary outcomes were pain reduction in numerical rating scale (NRS) and opioid requirement reduction. Secondary outcomes were: successful pain response (NRS decrease ≥50% or ≥3-point reduction from baseline); quality of life; patient satisfaction; adverse events; and survival rate at 3 months postintervention. Both groups reported sustained decreases in pain scores up to 3 months postintervention (mean reductions in abdominal pain: 0.9 (95% confidence interval (CI): -0.8 to 4.2) and 1.7 (95% CI: -0.3 to 2.1); back pain: 1.3 (95% CI: -0.9 to 3.4) and 2.5 (95% CI: -0.2 to 5.2) in EUS-CN, and PCN groups, respectively). The differences in mean pain scores between the two groups at baseline and 3 months were -0.5 (p = 0.46) and -1.4 (p = 0.11) for abdominal pain and 0.1 (p = 0.85) and -0.9 (p = 0.31) for back pain in favor of PCN. No significant differences were noted in opioid requirement reduction and other outcomes. EUS-CN and PCN were similarly effective and safe in managing intractable pain in pancreatic cancer patients. Either methods may be used depending on the resources and expertise of each institution.

Device-Related Error in Patient-Controlled Analgesia: Analysis of 82,698 Patients in a Tertiary Hospital.

BACKGROUND: Patient-controlled analgesia (PCA) is one of the most popular and effective methods for managing postoperative pain. Various types of continuous infusion pumps are available for the safe and accurate administration of analgesic drugs. Here we report the causes and clinical outcomes of device-related errors in PCA. METHODS: Clinical records from January 1, 2011 to December 31, 2014 were collected by acute pain service team nurses in a 2715-bed tertiary hospital. Devices for all types of PCA, including intravenous PCA, epidural PCA, and nerve block PCA, were included for analysis. The following 4 types of infusion pumps were used during the study period: elastomeric balloon infusers, carbon dioxide-driven infusers, semielectronic disposable pumps, and electronic programmable pumps. We categorized PCA device-related errors based on the error mechanism and clinical features. RESULTS: Among 82,698 surgical patients using PCA, 610 cases (0.74%) were reported as human error, and 155 cases (0.19%) of device-related errors were noted during the 4-year study period. The most common type of device-related error was underflow, which was observed in 47 cases (30.3%). The electronic programmable pump exhibited the high incidence of errors in PCA (70 of 15,052 patients; 0.47%; 95% confidence interval, 0.36-0.59) among the 4 types of devices, and 96 of 152 (63%) patients experienced some type of adverse outcome, ranging from minor symptoms to respiratory arrest. CONCLUSIONS: The incidence of PCA device-related errors was <0.2% and significantly differed according to the infusion pump type. A total of 63% of patients with PCA device-related errors suffered from adverse clinical outcomes, with no mortality. Recent technological advances may contribute to reducing the incidence and severity of PCA errors. Nonetheless, the results of this study can be used to improve patient safety and ensure quality care.

Predictors of Response to a Medial Branch Block: MRI Analysis of the Lumbar Spine.

The aim of this study was to determine the association between radiologic spinal pathology and the response to medial branches block (MBB). This retrospective observational study compared 165 patients. A successful response was defined as ≥30% or a 2-point reduction in the numeric rating scale (NRS) compared with the baseline at the 1-month follow-up. The facet angle, facet angle difference, facet joint degeneration, disc height and spondylolisthesis grade were analyzed from an MRI at the L3 to S1 levels. Univariate and multivariate logistic regression analyses were used to evaluate independent factors associated with a successful response of MBB. In the univariate analysis, the disc height at L5-S1 and facet angle difference at L3-4 were lower in the positive responders (p = 0.022 and p = 0.087, respectively). In the multivariate analysis, the facet angle difference at L3-4 and disc height at L5-S1 were independent factors associated with a successful response (odds ratio = 0.948; p = 0.038 and odds ratio = 0.864; p = 0.038, respectively). In patients with a degenerative disc at L5-S1, MBB can lead to a good response for at least one month. In patients with facet tropism at L3-4 level, the response to MBB after one month is likely to be poor.

Clinical experiences of performing transforaminal balloon adhesiolysis in patients with failed back surgery syndrome: two cases report.

Epidural fibrosis is a contributing factor to the persistent pain that is associated with failed back surgery syndrome (FBSS) and other pathophysiologies, particularly as it inhibits the passage of regional medications to areas responsible for pain. Therefore, effective mechanical detachment of epidural fibrosis can contribute to pain reduction and improve function in FBSS patients. In this report, we describe the successful treatment of FBSS patients with epidural adhesiolysis using a Fogarty catheter via the transforaminal approach.