Hydraulic properties of bentonite buffer material beyond 100 °C.

Bentonite buffer materials are important components of engineered barrier systems for the disposal of high-level radioactive waste produced during nuclear power generation. The design temperature of the buffer material is < 100 °C, and increasing the design temperature can reduce the required disposal area. This characteristic necessitates the evaluation of the thermal-hydraulic-mechanical properties of the buffer at temperatures above 100 °C to increase its target temperature. Therefore, the hydraulic properties of Gyeongju (KJ) bentonite buffer material were evaluated in this study, including the soil-water characteristic curve (SWCC) and hydraulic conductivity. An experimental system was manufactured to measure the suction and saturated hydraulic conductivity of KJ bentonite buffer material above 100 °C; the relative humidity of KJ bentonite buffer material was measured at 25-149 °C with an initial water content of 0, 0.06, and 0.12 under constant saturation conditions. The suction decreased as the temperature increased (10%-25% reduction at 99 °C-149 °C). The Van-Genuchten SWCC fitting parameters were also derived at 25 °C-149 °C using previously reported and newly generated experimental results, and the applicability of the modified Van-Genuchten SWCC model in this temperature range was verified. The hydraulic conductivity was proportional to temperature up to 100 °C, in agreement with the theoretical model results. Between 100 °C and 150 °C, the hydraulic conductivity increased nonlinearly because of molecular motion and structural changes inside the sample.

Versatility of the Posterior Interosseous Artery Flap: Emphasis on Powering Up the Toe Transfer.

BACKGROUND: Reverse-flow posterior interosseous artery (rPIA) flap is an excellent tool for restoration of defects in the hand and upper extremity, sparing the main arteries to the hand. Its reliability has been well established. MATERIALS AND METHODS: Fifty-one cases of rPIA flap involving 49 patients were retrospectively reviewed. The inclusion criteria were age, sex, etiology, size and location of the defect, flap size, number of perforators included, pedicle length, flap inset, donor site coverage, complications, and ancillary procedures. RESULTS: This study included 44 men and 5 women, ranging in age between 10 and 73 years. The subjects had soft tissue defects of the hand and upper extremity mainly due to traumatic injuries, including scar contractures of the first web space in 18 cases, thumb amputations in 6 cases, and congenital defects in 1 case. Among the 51 rPIA flap elevations, 3 cases involved flap failure due to the absence of proper pedicle. A fasciocutaneous pattern was observed in 45 cases and a myocutaneous pattern in 3 cases. In 5 cases of unplantable thumb amputations, the rPIA flap was performed for arterial inflow to the secondary toe-to-thumb transfer. Venous congestion of varying degrees was noted in 7 cases involving partial necrosis in 2 cases. During the mean 17 months of follow-up, patients were generally satisfied with the final outcomes. CONCLUSION: The rPIA flap can be used not only for soft tissue coverage of the hand and upper extremity but also as a recipient arterial pedicle for a secondary toe-to thumb transfer.

Tuning Organic Electrochemical Transistor Threshold Voltage using Chemically Doped Polymer Gates.

Organic electrochemical transistors (OECTs) have shown promise as transducers and amplifiers of minute electronic potentials due to their large transconductances. Tuning the OECT threshold voltage is important to achieve low-powered devices with amplification properties within the desired operational voltage range. However, traditional design approaches have struggled to decouple channel and materials properties from threshold voltage, thereby compromising on several other OECT performance metrics, such as electrochemical stability, transconductance, and dynamic range. In this work, simple solution-processing methods are utilized to chemically dope polymer gate electrodes, thereby controlling their work function, which in turn tunes the operation voltage range of the OECTs without perturbing their channel properties. Chemical doping of initially air-sensitive polymer electrodes further improves their electrochemical stability in ambient conditions. Thus, OECTs that are simultaneously low-powered and electrochemically resistant to oxidative side reactions under ambient conditions are demonstrated. This approach shows that threshold voltage, which is once interwoven with other OECT properties, can in fact be an independent design parameter, expanding the design space of OECTs.

Uncalcified Synovial Chondromatosis in the Pisotriquetral Joint.

Synovial chondromatosis is a rare lesion in the wrist, but some cases in the distal radioulnar joint have been reported and previous case reports emphasize joint calcifications, shown on preoperative plain radiographs. We report an extremely uncommon case of synovial chondromatosis in the pisotriquetral joint, in which radiographs and magnetic resonance imaging did not demonstrate apparent calcified bodies. In our case, for the accurate diagnosis and treatment, surgical exploration of the joint and synovectomy with removal of loose bodies was performed.

A retrospective analysis of 154 arterialized venous flaps for hand reconstruction: an 11-year experience.

BACKGROUND: The purpose of this study was to present the authors' 11-year clinical experience involving 154 cases of arterialized venous flaps for hand reconstruction. METHODS: The authors classified the venous flaps based on their size and composition. According to their size, flaps smaller than 10 cm were classified as small (n = 48), flaps larger than 25 cm were classified as large (n = 42), and those in between were classified as medium (n = 64). Classified according to their composition, there were 88 cases (57.1 percent) of venous skin flaps, 28 cases (18.2 percent) of innervated venous flaps, 15 cases (9.7 percent) of tendocutaneous venous flaps, and 17 cases (11 percent) of conduit venous flaps to repair arterial defects. There were six cases (3.9 percent) of composite venous flaps. RESULTS: The success rate of the flap transfer was 98.1 percent. The incidence of partial flap necrosis was 5.2 percent. The mean number of included veins was 2.17 for a small flap, 2.60 for a medium-sized flap, and 4.07 for a large flap (p < 0.01). The mean area of flap necrosis was 45.0 percent, 31.67 percent, and 18.75 percent for small, medium, and large flaps, respectively (p = 0.807). In eight cases of innervated venous flaps, the average static two-point discrimination was 10 mm (range, 8 to 15 mm). In 12 cases of tendocutaneous venous flaps, active range of motion at the proximal interphalangeal, distal interphalangeal, and metacarpophalangeal joints was 60, 20, and 75 degrees, respectively. CONCLUSIONS: The authors conclude that the arterialized venous flap is a valuable and effective tool for reconstructing complex hand injuries and may have a more comprehensive set of indications.

Immediate partial great toe transfer for the reconstruction of composite defects of the distal thumb.

BACKGROUND: Thumb defects distal to the interphalangeal joint do not cause any disability; therefore, any consideration to reconstruct the thumb is governed by the lifestyle and cultural background of the patient. This study presents the excellent results achieved by immediate partial great toe-to-hand transfer to reconstruct acute composite defects of the distal thumb. METHODS: Fifty-three patients with amputation or crush injury of the distal thumb who underwent partial great toe-to-hand transfer at the authors' institute over an 11-year period were reviewed. Based on the amputation level of the distal thumb, the authors classified the injuries into three groups. Operative techniques used were osteo-onychocutaneous flap with partial or whole toenail from the great toe and partial great toe transfer with arthrodesis of the interphalangeal joint. Overall results were evaluated in terms of success rate, incidence of emergency reexploration, and number and type of secondary operation. Static two-point discrimination, range of motion, pinch strength, and subjective satisfaction were also evaluated. RESULTS: The success rate of immediate partial great toe-to-hand transfer was 100 percent. The incidence of inflammation and the reexploration rate were not significantly different from those in previously reported articles. In 35 cases where postoperative follow-up was possible, static two-point discrimination, total active range of motion, and pinch strength were generally excellent and the majority of the patients were satisfied with the final outcome. CONCLUSION: Immediate reconstruction with partial great toe transfer is an excellent option for reconstruction of composite defects of the distal thumb, not only for aesthetic reasons but also for functional purposes.