Reduced interface effect of proton beam irradiation on the electrical properties of WSe2/hBN field effect transistors.

Two-dimensional transition metal dichalcogenide (TMDC) semiconductors are emerging as strong contenders for electronic devices that can be used in highly radioactive environments such as outer space where conventional silicon-based devices exhibit nonideal characteristics for such applications. To address the radiation-induced interface effects of TMDC-based electronic devices, we studied high-energy proton beam irradiation effects on the electrical properties of field-effect transistors (FETs) made with tungsten diselenide (WSe2) channels and hexagonal boron-nitride (hBN)/SiO2gate dielectrics. The electrical characteristics of WSe2FETs were measured before and after the irradiation at various proton beam doses of 1013, 1014, and 1015cm-2. In particular, we demonstrated the dependence of proton irradiation-induced effects on hBN layer thickness in WSe2FETs. We observed that the hBN layer reduces the WSe2/dielectric interface effect which would shift the transfer curve of the FET toward the positive direction of the gate voltage. Also, this interface effect was significantly suppressed when a thicker hBN layer was used. This phenomenon can be explained by the fact that the physical separation of the WSe2channel and SiO2dielectric by the hBN interlayer prevents the interface effects originating from the irradiation-induced positive trapped charges in SiO2reaching the interface. This work will help improve our understanding of the interface effect of high-energy irradiation on TMDC-based nanoelectronic devices.

A Molecular-Switch-Embedded Organic Photodiode for Capturing Images against Strong Backlight.

When the intensity of the incident light increases, the photocurrents of organic photodiodes (OPDs) exhibit relatively early saturation, due to which OPDs cannot easily detect objects against strong backlights, such as sunlight. In this study, this problem is addressed by introducing a light-intensity-dependent transition of the operation mode, such that the operation mode of the OPD autonomously changes to overcome early photocurrent saturation as the incident light intensity passes the threshold intensity. The photoactive layer is doped with a strategically designed and synthesized molecular switch, 1,2-bis-(2-methyl-5-(4-cyanobiphenyl)-3-thienyl)tetrafluorobenzene (DAB). The proposed OPD exhibits a typical OPD performance with an external quantum efficiency (EQE) of <100% and a photomultiplication behavior with an EQE of >100% under low-intensity and high-intensity light illuminations, respectively, thereby resulting in an extension of the photoresponse linearity to a light intensity of 434 mW cm-2 . This unique and reversible transition of the operation mode can be explained by the unbalanced quantum yield of photocyclization/photocycloreversion of the molecular switch. The details of the operation mechanism are discussed in conjunction with various photophysical analyses. Furthermore, they establish a prototype image sensor with an array of molecular-switch-embedded OPD pixels to demonstrate their extremely high sensitivity against strong light illumination.

Fabrication of TiB2-Al1050 Composites with Improved Microstructural and Mechanical Properties by a Liquid Pressing Infiltration Process.

This study was conducted on titanium diboride (TiB2) reinforced Al metal matrix composites (MMCs) with improved properties using a TiB2 and aluminum (Al) 1050 alloy. Al composites reinforced with fine TiB2 at volume ratios of more than 60% were successfully fabricated via the liquid pressing infiltration (LPI) process, which can be used to apply gas pressure at a high temperature. The microstructure of the TiB2-Al composite fabricated at 1000 °C with pressurization of 10 bar for 1 h showed that molten Al effectively infiltrated into the high volume-fraction TiB2 preform due to the improved wettability and external gas pressurization. In addition, the interface of TiB2 and Al not only had no cracks or pores but also had no brittle intermetallic compounds. In conclusion, TiB2-Al composite, which has a sound microstructure without defects, has improved mechanical properties, such as hardness and strength, due to effective load transfer from the Al matrix to the fine TiB2 reinforcement.

Clinical Analysis of Radiocephalic Fistula Using Side-to-side Anastomosis with Distal Cephalic Vein Ligation.

BACKGROUND: The surgically created arteriovenous fistula has recently been recommended as the best available angioaccess for hemodialysis. Therefore, in this study, we carried out a clinical analysis on surgical procedures in the ligation and division of a distal vein to achieve similar effects as those of vein end-to-arterial side after side-to-side anastomosis. METHODS: We retrospectively reviewed the clinical data of 113 patients who came for an outpatient clinic follow-up to the department of internal medicine of our hospital; these patients were among the 125 patients who underwent radiocephalic arteriovenous fistula (side-to-side anastomosis with distal vein ligation and division) in our hospital in the period from January 2006 to December 2010. RESULTS: The patency rate showed no statistical significance with respect to sex (p=0.775), age (p=0.775), hypertension (p=0.262), diabetes (p=0.929), and cardio-neurovascular disease (p=0.717). Patency rates were 96% for the first month, 93% for the first year, and 90% for the second year for the radiocephalic arteriovenous fistula (side-to-side anastomosis with distal vein ligation and division) performed on the wrist. CONCLUSION: The patency rates revealed favorable results and few postoperative complications as compared to those of previous reports. Therefore, radiocephalic fistula using side-to-side anastomosis with distal cephalic vein ligation is considered a recommendable surgical procedure in the distal part for the hemodialysis of CRF patients.

Primary surgical closure should be considered in premature neonates with large patent ductus arteriosus.

BACKGROUND: Treatment for patent ductus arteriosus (PDA) in premature infants can consist of medical or surgical approaches. The appropriate therapeutic regimen remains contentious. This study evaluated the role of surgery in improving the survival of premature neonates weighing less than 1,500 g with PDA. MATERIALS AND METHODS: From January 2008 to June 2011, 68 patients weighing less than 1,500 g with PDA were enrolled. The patients were divided into three groups: a group managed only by medical treatment (group I), a group requiring surgery after medical treatment (group II), and a group requiring primary surgical treatment (group III). RESULTS: The rate of conversion to surgical methods due to failed medical treatment was 67.6% (25/37) in the patients with large PDA (≥2 mm in diameter). The number of patients who could be managed with medical treatment was nine which was only 20.5% (9/44) of the patients with large PDA. There was no surgery-related mortality. Group III displayed a statistically significantly low rate of development of bronchopulmonary dysplasia (BPD) (p=0.008). The mechanical ventilation time was significantly longer in group II (p=0.002). CONCLUSION: Medical treatment has a high failure rate in infants weighing less than 1,500 g with PDA exceeding 2.0 mm. Surgical closure following medical treatment requires a longer mechanical ventilation time and increases the incidence of BPD. Primary surgical closure of PDA exceeding 2.0 mm in the infants weighing less than 1,500 g should be considered to reduce mortality and long-term morbidity events including BPD.

Recurrent true brachial artery aneurysm.

True aneurysm of the brachial artery is a rare disease entity. The mechanism of aneurysm formation is considered to be compression of the arterial wall, producing contusion of the media and subsequent weakness of the wall and fusiform dilatation. It can be caused by arteriosclerotic, congenital, and metabolic disorders, and can be associated with diseases such as Kawasaki's disease. Doppler ultrasonography, computed tomography, arteriography, and selective upper extremity angiography may be performed for establishing the diagnosis of aneurysm. The best therapeutic option is operative repair, and it should be performed without any delay, in order to prevent upper extremity ischemic or thrombotic sequelae. Here, we report a case of recurrent brachial artery aneurysm with review of the literature.

Chylopericardium Secondary to Lymphangiomyoma - A case report -.

Chylopericardium is a rare disease entity characterized by the accumulation of chylous fluid in the pericardial sac. It usually arises from mediastinal neoplasms, thrombosis of the subclavian vein, tuberculosis, nonsurgical trauma, thoracic or cardiac surgery. The spectrum of symptoms for chylopericardium varies from an incidental finding of cardiomegaly to dyspnea, upper abdominal discomfort, cough, chest pain, palpitation, fatigue. However, most of the patients are asymptomatic. The main purpose of treatment of chylopericardium is the prevention of cardiac tamponade and prevention of metabolic, nutritional, and immunological compromise due to chyle leak. Here, we report a case of chylopercardium secondary to lymphangiomyoma with review of the literature.