RESUMO
Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300 °C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (≈1 nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250 °C) reveals a Pt HER mass activity of 22.2 ± 1.2 A mg-1 Pt at -50 mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2 A mg-1 Pt at -50 mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far.
RESUMO
PURPOSE: Kono-S anastomosis, an antimesenteric, functional, end-to-end handsewn anastomosis, was introduced in 2011. The aim of this meta-analysis is to evaluate the safety and effectivity of the Kono-S technique. METHODS: A comprehensive search of MEDLINE (PubMed), Embase (Elsevier), Scopus (Elsevier), and Cochrane Central (Ovid) from inception to August 24th, 2023, was conducted. Studies reporting outcomes of adults with Crohn's disease undergoing ileocolic resection with subsequent Kono-S anastomosis were included. PRISMA and Cochrane guidelines were used to screen, extract and synthesize data. Primary outcomes assessed were endoscopic, surgical and clinical recurrence rates, as well as complication rates. Data were pooled using random-effects models, and heterogeneity was assessed with I² statistics. ROBINS-I and ROB2 tools were used for quality assessment. RESULTS: 12 studies involving 820 patients met the eligibility criteria. A pooled mean follow-up time of 22.8 months (95% CI: 15.8, 29.9; I2 = 99.8%) was completed in 98.3% of patients. Pooled endoscopic recurrence was reported in 24.1% of patients (95% CI: 9.4, 49.3; I2 = 93.43%), pooled surgical recurrence in 3.9% of patients (95% CI: 2.2, 6.9; I2 = 25.97%), and pooled clinical recurrence in 26.8% of patients (95% CI: 14, 45.1; I2 = 84.87%). The pooled complication rate was 33.7%. The most common complications were infection (11.5%) and ileus (10.9%). Pooled anastomosis leakage rate was 2.9%. CONCLUSIONS: Despite limited and heterogenous data, patients undergoing Kono-S anastomosis had low rates of surgical recurrence and anastomotic leakage with moderate rates of endoscopic recurrence, clinical recurrence and complications rate.