The main gas-sensing mechanisms of 2D materials are surface charge transfer by analytes and Schottky barrier (SB) modulation at the interface between the metallic and semiconducting surfaces. In particular, dramatic differences in the gas-sensing performances of 2D materials originate from SB modulation. However, SB sites typically exist only at the interface between the semiconducting channel material and the metal electrode. Herein, in situ formed multiple SBs in a single gas-sensing channel are demonstrated, which are derived from the heterojunction of metallic Ti 3 C 2 and semiconducting TiO 2. In stark contrast with previous techniques, edge-oxidized Ti 3 C 2 flakes are synthesized by solution oxidation, allowing the uniform formation of TiO 2 crystals on all flakes that comprise the gas sensing channel. Oxidized colloidal solutions are subjected to vacuum filtration to automatically form SB sites at the multiple inter-flake junctions in both the outer surface and inner bulk regions of the film. The TiO 2 /Ti 3 C 2 composite sensor shows 13.7 times higher NO 2 sensitivity as compared with pristine Ti 3 C 2 MXene, while the responses of the reducing gases are almost unchanged. The results suggest a new strategy for improving gas-sensing performance by maximizing the density of SB sites through a simple method.

Background and purpose: We analyzed the incidence and causes of oral anticoagulant (OAC) cessation and subsequent stroke after OAC withdrawal in a cohort of Korean stroke patients with atrial fibrillation. Methods: The Korean Atrial Fibrillation Evaluation Registry in Ischemic Stroke patients (K-ATTENTION) is a multicenter cohort study, merging stroke registries from 11 tertiary centers in Korea. The number of OAC interruption episodes and the reasons were reviewed from hospital records. Stroke after OAC withdrawal was defined when a patient experienced ischaemic stroke within 31 days after OAC withdrawal. Clinical variables were compared between patients who experienced stroke recurrence during OAC interruption and those who did not experience recurrence. Results: Among 3213 stroke patients with atrial fibrillation, a total of 329 episodes of OAC interruption were detected in 229 patients after index stroke (mean age 72.9 AE 8.3 years, 113 female patients). The most frequent reason for OAC withdrawal was poor compliance [103 episodes (31.3%)] followed by extracranial bleeding [96 episodes (29.2%)]. Stroke after OAC withdrawal was noted in 13 patients. Mean age, vascular risk factor profile and mean CHA 2 DS 2 -VASc score were not significantly different between patients with and without recurrent stroke. Conclusions: A considerable number of stroke patients with atrial fibrillation experienced temporary interruption of OAC after index stroke, which was associated with stroke recurrence of 4.0 cases per 100 interruption episodes.