Recessed-Channel WSe2 Field-Effect Transistor via Self-Terminated Doping and Layer-by-Layer Etching.

Effective channel control with low contact resistance can be accomplished through selective ion implantation in Si and III-V semiconductor technologies; however, this approach cannot be adopted for ultrathin van der Waals materials. Herein, we demonstrate a self-aligned fabrication process based on self-terminated p-doping and layer-by-layer chemical etching to achieve low contact resistance as well as a high on/off current ratio in ultrathin tungsten diselenide (WSe2) field-effect transistors (FETs). Damage-free layer-by-layer thinning of the WSe2 channel is repeated up to a thickness of approximately 1.4 nm, while maintaining the selectively p-doped source/drain regions. The device characteristics of the recessed-channel WSe2 FET are systematically monitored during this layer-by-layer recess-channel process. The WSe2 etching rate is estimated to be 2-3 layers per cycle of oxidation and subsequent chemical etching. The self-terminated tungsten oxide (WOX) layer grown through ultraviolet-ozone treatment induces robust p-doping in the neighboring (or underlying) WSe2 through the electron withdrawal mechanism, which remains in the source/drain regions after channel oxide removal. The adopted self-terminated and self-aligned recess-channel process for ultrathin WSe2 FETs enables the realization of a high on/off output current ratio (>108) and field-effect mobility (∼190 cm2/V·s), while maintaining low contact resistance (0.9-6.1 kΩ·µm) without a postannealing process. The proposed facile and reproducible doping and atomic-layer-etching method for the fabrication of a recessed-channel FET with an ultrathin body can be helpful for high-performance two-dimensional semiconductor devices and is applicable to post-Si complementary metal-oxide semiconductor devices.

Using Etomidate in a Two-month-old Infant with Cushing Syndrome due to Adrenocortical Carcinoma

Cushing syndrome (CS) is a rare disease caused by hypercortisolemia. Although surgical treatment is the first-line treatment in CS, the appropriate medication for the patient's condition should be selected when medical treatment is needed. Etomidate is an adrenal-blocking drug used to treat CS and the most suitable for severe hypercortisolemia and adrenocortical carcinoma (ACC), due to cardiovascular stability and an anti-tumorigenic effect. However, its use and safe recommended dosage in infants with CS is unreported. Here we describe the case of a 2-month-old girl treated with etomidate for CS caused by ACC. Even though radical mass excision was performed, severe hypercortisolemia persisted, resulting from metastatic lesions in the liver, and medical treatment was considered. The etomidate doses, no bolus dose and infusion rate of 0.03 mg/kg/hour, may be an appropriate dose for severe hypercortisolemia in infants. This case will help determine future treatment strategies for similar cases in infants.

A CBCT study on positional change in mandibular condyle according to metallic anchorage methods in skeletal class III patients after orthognatic surgery.

PURPOSE: This study was to evaluate the postoperative stability of the mandibular condyle according to the number of screws in the proximal segment using cone beam computed tomography (CBCT). PATIENTS AND METHODS: Thirty patients diagnosed with skeletal class III malocclusion and underwent sagittal split ramus osteotomy (SSRO) were enrolled in this study. In Group A, 4 screws and a 4-hole miniplate were used for the internal fixation of an osteotomy and 3 screws, only 1 screw in the proximal segment, and a 4-hole miniplate were used in Group B. We digitally measured anteroposterior, supero-inferior, and mediolateral positions and angles of the long axis of the mediolateral poles in CBCT scans pre-operatively, within 1 week postoperatively and 3, 6 months after surgery. RESULTS: The condylar head angle in the axial plane showed consistent and significant changes. The condylar head angle in the coronal plane decreased in both groups, which shows that condylar heads bent inward. In the axial plane, Group A showed statistically significant differences while Group B did not in early stage (T0-T1-T2). The change in distance between condylar heads shows that these have moved outward in both groups. CONCLUSION: The results show that a fixation method using 3 screws with a 4-hole miniplate did seemed preferable and may give some flexibility for condylar heads to be positioned in physiologic position during postoperative phase.

Usefulness of the retromandibular transparotid approach for condylar neck and condylar base fractures.

Condyle fractures represent 20% to 30% of all mandibular fractures and are thus among the most common facial fractures. The fracture pattern can vary greatly and may occur anywhere along the line from the sigmoid notch to the mandibular angle. The main problems are access, difficulty in repositioning the extremely slender fragments, and fixation of the condyle.Eighty-seven patients were diagnosed with condylar neck or condylar base fractures from January 2007 to December 2009 in the Department of Oral & Maxillofacial Surgery of Kyung Hee University Dental Hospital. In this study, we included 35 patients who underwent open surgery and a total of 28 patients who were treated using a retromandibular transparotid approach.Surgical treatment aims were anatomic repositioning and rigid fixation of the fragments, occlusal stability, rapidly return to function, maintenance of vertical ramus dimension, no airway compromise, and reduced long-term temporomandibular joint dysfunction. Considering the high rate of occurrence of condylar fracture and the importance of the condylar as a growth center of the mandible, extraoral approaches for the open reduction of condylar fractures are considered effective and can be used widely.Short access route, easy reduction, short operating time, and stable postoperative occlusion are the advantages of the retromandibular transparotid approach. Also, there was no permanent damage from facial nerve injury, salivary leakage, or preauricular hypoesthesia. Therefore, the retromandibular transparotid approach is considered a safe and effective method for patients with a condylar neck or condylar base fracture classified according to the Strasbourg Osteosynthesis Research Group's classification, who require surgical treatment with an extraoral approach.