Nanoscale mapping of temperature-dependent conduction in an epitaxial VO2 film grown on an Al2O3 substrate

Vanadium dioxide (VO₂) is one of the extensively studied strongly correlated oxides due to its intriguing insulator–metal transition near room temperature. In this work, we investigated temperature-dependent nanoscale conduction in an epitaxial VO₂ film grown on an Al₂O₃ substrate using conductive-atomic force microscopy (C-AFM). We observed that only the regions near the grain boundaries are conductive, producing intriguing donut patterns in C-AFM images. Such donut patterns were observed in the entire measured temperature range (300–355 K). The current values near the grain boundaries increased by approximately two orders of magnitude with an increase in the temperature, which is consistent with the macroscopic transport data. The spatially-varied conduction behavior is ascribed to the coexistence of different monoclinic phases, i.e., M1 and M2 phases, based on the results of temperature-dependent Raman spectroscopy. Furthermore, we investigated the conduction mechanism in the relatively conductive M1 phase regions at room temperature using current–voltage (I–V) spectroscopy and deep data analysis. Bayesian linear unmixing and k-means clustering showed three distinct types of conduction behavior, which classical C-AFM cannot resolve. We found that the conduction in the M1 phase regions can be explained by the Poole–Frenkel mechanism. This work provides deep insight into IMT behavior in the epitaxial VO₂ thin film at the nanoscale, especially the coexistence and evolution of the M1 and M2 phases. This work also highlights that I–V spectroscopy combined with deep data analysis is very powerful in investigating local transport in complex oxides and various material systems.

We investigated temperature-dependent nanoscale conduction in an epitaxial VO₂ film grown on an Al₂O₃ substrate using conductive-atomic force microscopy and deep data analysis.     

Ureteral injuries during classic intrafascial supracervical hysterectomy: an 11-year experience in 1163 patients

STUDY OBJECTIVE: To examine the incidence, characteristics, and treatment of ureteral injuries during classic intrafascial supracervical hysterectomy for benign gynecologic diseases. DESIGN: Retrospective study (Canadian Task Force classification II-3). SETTING: Department of obstetrics and gynecology, university teaching hospital. PATIENTS: A total of 1163 women with benign gynecologic diseases. INTERVENTIONS: Classic intrafascial supracervical hysterectomy. MEASUREMENTS AND MAIN RESULTS: A retrospective chart review was conducted to determine the rate of ureteral injury. Four cases of ureteral injuries occurred among the 1163 classic intrafascial supracervical hysterectomy procedures (0.34%). Ureteral injury occurred during peritoneal dissection in 1 case, which was treated immediately with laparoscopy. In 2 cases, ureteral injuries were recognized by watery vaginal discharge several days after the operation and were treated with laparotomy procedures. Ureteral injury was not detected postoperatively in another case, resulting in a laparoscopic nephrectomy caused by a nonfunctioning kidney 3 years after the initial operation. The predisposing factors for ureteral injury were adhesion as a result of endometriosis, and earlier surgery in which the normal pelvic anatomy was distorted. CONCLUSION: The incidence of ureteral injury during classic intrafascial supracervical hysterectomy as noted in this study is 0.34%. Postoperative cases were associated with high morbidity. Early detection of ureteral injury is crucial for appropriate management as intraoperative diagnosis and repair of the injury then has fewer consequences and less serious complications than postoperative cases.     

Gastric Cancer Risk Was Associated with Dietary Factors Irritating the Stomach Wall: A Case–Control Study in Korea

The incidence of gastric cancer is high in Korea, and dietary factors are important risk factors for gastric cancer. This study examined whether gastric cancer risk was related to dietary factors that directly irritate the stomach wall. This case–control study consisted of 308 matched pairs of gastric cancer cases and controls recruited from 2002 to 2006 at two hospitals in Korea. Dietary assessments were completed using a food frequency questionnaire and a dietary habit questionnaire. Gastric cancer risk was increased for high meal frequency of >3 vs. low meal frequency of ≤3 times per day, overeating vs. not overeating, and preferred vs. not preferred spicy or salty foods. Furthermore, participants with dietary factors of high meal frequency, overeating, and preference for spicy or salty foods elevated the risk of gastric cancer compared to those with low meal frequency, not overeating, and not preferring spicy or salty foods, simultaneously. In conclusion, gastric cancer risk was significantly increased in people with dietary factors that irritate the stomach wall, such as high meal frequency, overeating, and preference for spicy or salty foods.