Control of Luminescence by Tuning of Crystal Symmetry and Local Structure in Mn4+ -Activated Narrow Band Fluoride Phosphors.

Mn4+ -doped fluoride phosphors have been widely used in wide-gamut backlighting devices because of their extremely narrow emission band. Solid solutions of Na2 (Six Ge1-x )F6 :Mn4+ and Na2 (Gey Ti1-y )F6 :Mn4+ were successfully synthesized to elucidate the behavior of the zero-phonon line (ZPL) in different structures. The ratio between ZPL and the highest emission intensity υ6 phonon sideband exhibits a strong relationship with luminescent decay rate. First-principles calculations are conducted to model the variation in the structural and electronic properties of the prepared solid solutions as a function of the composition. To compensate for the limitations of the Rietveld refinement, electron paramagnetic resonance and high-resolution steady-state emission spectra are used to confirm the diverse local environment for Mn4+ in the structure. Finally, the spectral luminous efficacy of radiation (LER) is used to reveal the important role of ZPL in practical applications.

Oral Anticoagulation Timing in Patients with Acute Ischemic Stroke and Atrial Fibrillation.

BACKGROUND AND PURPOSE: Oral anticoagulants (OACs) prevent stroke recurrence and vascular embolism in patients with acute ischemic stroke (AIS) and atrial fibrillation (AF). Based on empirical consensus, current guidance recommends a "1-3-6-12 days" rule to resume OACs after AIS. This study investigated the suitability of guideline-recommended timing for OAC initiation. METHODS: Using data of 12,307 AF patients hospitalized for AIS, for the period 2012 to 2016, in Taiwan's National Health Insurance Research Database, we constructed a sequence of cohorts of OAC users and propensity score-matched nonusers, creating one cohort on each day of OAC initiation for 30 days since admission. Composite outcome included effectiveness (cardiovascular death, ischemic stroke, myocardial infarction, transient ischemic attack, systemic embolism, and venous thromboembolism) and safety (intracranial hemorrhage, gastrointestinal bleeding, and hematuria) outcomes. Comparing with nonusers, we examined the risks in the early OAC use (within 1-3-6-12 days) or guideline-recommended delayed use. Indirect comparison between the early and delayed use was conducted using mixed treatment comparison. RESULTS: Across the AIS severity, the risks of composite or effectiveness outcome were lower in OAC users than nonusers, and the risks were similar between the early and delayed use groups. In patients with severe AIS, early OAC use was associated with an increased risk of safety outcome, with a hazard ratio (HR) of 1.67 (confidence interval [CI]: 1·30-2·13) compared with nonusers and a HR of 1.44 (CI: 0·99-2·09) compared with the delayed use. CONCLUSION: Our study findings support an early OAC initiation in AF patients with mild-to-moderate AIS and a routine delayed use of OACs can be considered in those with severe AIS to avoid a serious bleeding event.

High frequency oscillatory ventilation in children: experience of a medical center in Taiwan.

BACKGROUND/PURPOSE: Data about the effectiveness of high frequency oscillatory ventilation (HFOV) in children with respiratory failure are limited. This study investigated the efficacy and prognostic factors of this treatment. METHODS: Children between 2 months and 18 years of age who received HFOV between January 2000 and September 2006 in a tertiary care center were enrolled in this retrospective study. RESULTS: Thirty-six HFOV treatments were given to 33 patients (twice in one patient and three times in another patient) at a mean age of 5.4 +/- 5.0 years. HFOV was used as a rescue after conventional mechanical ventilation (CMV) for 4.4 +/- 4.2 days. The mean duration of HFOV was 7.6 +/- 7.9 days. The most common indication for HFOV was oxygenation failure, which was due to pneumonia with acute respiratory distress syndrome in 15 (45.5%), severe lobar pneumonia in nine (27.3%), pulmonary hemorrhage in eight (24.2%) and pneumothorax in one (3%). PaCO2 was significantly improved 4 hours after HFOV and the PaO2/FiO2 ratio increased significantly 12 hours later. The oxygenation index and alveolar-arterial oxygen difference P(A-a)O2, however, did not change markedly. Four (12%) patients needed further extracorporeal life support and two of these survived. The overall survival rate was 45.5%. Patients with heavier body weight (p less than 0.05) and of the male gender (p less than 0.05) had a higher risk of mortality. CONCLUSION: As a relatively late rescue therapy after failure of CMV, HFOV may improve PaCO2 and PaO2/FiO2 in children with respiratory failure. However, it carries an increased mortality rate in patients with heavier body weight and male gender.

Special electrophysiological characteristics of pediatric idiopathic ventricular tachycardia.

BACKGROUND: Idiopathic ventricular tachycardia (VT) is an important pediatric arrhythmia but relevant studies in Asian cohort are rare. We determined the electrophysiological characteristics and outcomes of this rhythm disturbance. METHODS: From an institutional database, patients aged <18years without structural heart disease who have sustained monomorphic VT (longer than 30s) during 1995-2016 were enrolled. RESULTS: We enrolled 57 idiopathic VT patients (male:female=31:26). The initial presentation included palpitation (64.9%) and shock (12.3%). The electrocardiography revealed relatively short QRS duration (123±18ms) and absence of ventriculoatrial dissociation in 33.3% of the patients, causing initial misdiagnosis in 29.8% of these patients. Patients with a VT onset age of <10years were more likely to have a left bundle branch block morphology (52.2% vs. 11.8%, p=0.001) and spontaneous recovery than those with a VT onset age of ≥10years. An electrophysiology study in 44 patients revealed that the most common arrhythmia focus was the left ventricular septal area (78%), called fascicular VT. Radiofrequency ablation showed a satisfactory success rate (90%) and fair recurrence rate (14.3%). Tachycardia-induced cardiomyopathy was noted in 14% of the VT patients and cardiac function returned to normal in 1-18months (median, 3months) after successful ablation. CONCLUSIONS: In an Asian pediatric population, VT has distinct electrophysiological characteristics including dominant left ventricular origin, narrower QRS duration, and more symptomatic presentation. Transcatheter ablation is effective against VT, and the associated cardiomyopathy often resolves rapidly after successful ablation.

Primary ventricular tachycardia in paediatric population in a tertiary centre.

OBJECTIVE: To delineate the outcome of ventricular tachycardia (VT) in the paediatric population. METHODS: Patients who developed sustained VT between the ages of 0 and 18 years in a referral centre from 1991 to 2015 were enrolled. RESULTS: A total of 116 patients (67 male/49 female) had documented VT, and 53 (46%) had associated heart disease, namely cardiomyopathy in 20 (17%), structural heart disease in 19 (16%) and channelopathy in 14 (12%), and some of them presented with two types of associated heart disease. Idiopathic VT (63 patients), which presents without associated heart disease, was the most common type. Forty-one patients received catheter ablation, with 37 being successful (90%) and 6 of 37 recurrence (16%). None of the patients died during the 5.8±5.9 year follow-up. VT with cardiomyopathy was associated with the highest mortality rate, particularly in those with hypertrophic and restrictive cardiomyopathy. Among 16 patients initially presenting VT and heart failure, seven exhibited improved heart function after VT control, which could be predicted by benign onset symptoms, monomorphic QRS morphology and the presentation of VT at the initial diagnosis of cardiomyopathy. VT associated with structural heart disease was also associated with a high risk of mortality, but this risk decreased after aggressive intervention in the recent years. VT with channelopathy can be often controlled with medication, except for those with prenatal onset. CONCLUSIONS: Although VT may carry high mortality when associated with structural anomaly or cardiomyopathy, VT presenting to tertiary referral centre often has a favourable outcome after prompt intervention.