[en] Thermophysical properties were investigated for ZrB2 and ZrB2-30vol% SiC ceramics. Thermal conductivities were calculated from measured thermal diffusivities, heat capacities, and thermal expansions. The thermal conductivity of ZrB2 increased from 58.7 W/m K at room temperature to 62.0 W/m K at 1675 K, whereas the thermal conductivity of ZrB2-SiC decreased from 62.0 W/m K to 56 W/m K over the same temperature range. Electron and phonon contributions to thermal conductivity were determined using electrical resistivity measurements and were used, along with grain size models, to explain the observed trends. The results are compared to previously reported thermal conductivities for ZrB2 and ZrB2-SiC

[en] We wanted to assess the usefulness of four-dimensional (4D) ultrasonography (US), i.e., real-time three-dimensional US, as an adjunct for performing various US-guided interventional procedures in superficial lesion. Thirty-three patients were referred for US-guided interventional procedures for superficial lesions, including core biopsy in 19, fine- needle aspriation in eight, therapeutic drug injection in four and needle puncture in two. The procedures were performed under 4D US guidance. We reviewed the pathologic/cytologic results of the core biopsies or needle aspirations, and also the outcomes of drug injection or needle puncture. For all the patients who underwent 4D US-guided core biopsy, the specimens were adequate for making the pathological diagnosis, and specimens were successfully obtained for those patients who underwent 4D US-guided aspiration. The patients treated with 4D US-guided therapeutic drug injection or needle puncture had a good response. No major procedure-related complications occurred. The procedural times were similar to those procedural times with using two-dimensional US. Combining the two dimensional and 4D US techniques aids the physician when performing US-guided interventional procedures for the superficial lesions

[en] Radionuclide Cisternography (RNC) is of potential value in pointing out the sites of cerebrospinal fluid (CSF) leakage in patients with spontaneous intracranial hypotension (SIH). In the current report, we present two patients who underwent RNC for suspected CSF leakage. Both patients underwent magnetic resonance imaging (MRI) and RNC for evaluation. We describe a simple method to increase the detection ability of RNC for CSF leakage in patients with SIH

[en] Pyriform sinus fistula (PSF) refers to a persistent embryologic third or fourth pharyngeal pouch, which typically presents as a congenital sinus tract that originates from the pyriform sinus. The sinus tract is often diagnosed by a barium study or direct endoscopic inspection. Utilization of advanced imaging studies, including ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), may aid in the diagnosis of this disease entity. To review the imaging findings of PSF and demonstrate the value of various cross-sectional imaging (US, CT, and MRI) in the diagnosis of PSF. PSF in five children was verified surgically. Preoperative barium esophagography, US, CT, and MRI were performed selectively in these patients. The clinical and imaging findings are reviewed retrospectively. Barium studies demonstrated the sinus tract in all five patients. US, CT, and MRI demonstrated an associated inflammatory process. By utilizing the trumpet maneuver, the presence of sinus tract was evident in two patients during US. The sinus tract is also demonstrated by CT in another patient. Although barium esophagography is advantageous in demonstration of the sinus tract in PSF, US and CT are also capable of showing the sinus tract. The extent of inflammatory process related to PSF is better delineated by US, CT, and MRI. (orig.)

[en] Nanofluids, colloidal dispersions of nanoparticles in a base fluid such as water, can afford very significant Critical Heat Flux (CHF) enhancement. Such engineered fluids potentially could be employed in reactors as advanced coolants in safety systems with significant safety and economic advantages. However, a satisfactory explanation of the CHF enhancement mechanism in nanofluids is lacking. To close this gap, we have identified the important boiling parameters to be measured. These are the properties (e.g., density, viscosity, thermal conductivity, specific heat, vaporization enthalpy, surface tension), hydrodynamic parameters (i.e., bubble size, bubble velocity, departure frequency, hot/dry spot dynamics) and surface conditions (i.e., contact angle, nucleation site density). We have also deployed a pool boiling facility in which many such parameters can be measured. The facility is equipped with a thin indium-tin-oxide heater deposited over a sapphire substrate. An infra-red high-speed camera and an optical probe are used to measure the temperature distribution on the heater and the hydrodynamics above the heater, respectively. The first data generated with this facility already provide some clue on the CHF enhancement mechanism in nanofluids. Specifically, the progression to burnout in a pure fluid (ethanol in this case) is characterized by a smoothly-shaped and steadily-expanding hot spot. By contrast, in the ethanol-based nanofluid the hot spot pulsates and the progression to burnout lasts longer, although the nanofluid CHF is higher than the pure fluid CHF. The presence of a nanoparticle deposition layer on the heater surface seems to enhance wettability and aid hot spot dissipation, thus delaying burnout. (author)

[en] Neuroendocrine cervical carcinoma is a rare subtype of cervical cancer. These tumors exhibit an aggressive behavior with early regional lymph node and distant metastases. The purpose of our study was to describe five cases of neuroendocrine cervical-vaginal carcinoma and to discuss the potential of the 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) scan for the detection of this rare malignancy. Five cases of cervical-vaginal neuroendocrine tumor were retrospectively collected, during a two year (from September 2009 to August 2011) period in our hospital. The clinical staging distributions were International Federation of Gynecology and Obstetrics (FIGO) stage IB2 (1 of 5), stage IIA (3 of 5) and stage IVA (1 of 5). Two cases (cases 1 and 4) were restaged after ¹⁸F-FDG PET/CT scan in the initial staging process. Post-treatment ¹⁸F-FDG PET/CT scans, in three patients, revealed positive findings for tumor recurrence or lymph node metastases. Two patients (cases 2 and 3) died of tumor within two years. ¹⁸F-FDG PET/CT scan is a useful tool in cervical-vaginal neuroendocrine tumor. In its initial staging, the ¹⁸F-FDG PET/CT scan may help assess the possible nodal involvement or early hematogeneous spreading. We can also use the ¹⁸F-FDG PET/CT to detect local recurrence and to evaluate the treatment response after clinical manipulation.

[en] Highlights: • Periodic inverted pyramid (IP) structures employed for Si heterojunction (SHJ). • Improved carrier collection efficiency by the superior passivation of IP structures. • SHJ cells with the optimized IP structure achieving the efficiency of 14.6. The Si heterojunction (SHJ) solar cell is presently the most popular design in the crystalline Si (c-Si) photovoltaics due to the high open-circuit voltages (V_OC). Photon management by surface structuring techniques to control the light entering the devices is critical for boosting cell efficiency although it usually comes with the V_OC loss caused by severe surface recombination. For the first time, the periodic inverted pyramid (IP) structure fabricated by photolithography and anisotropic etching processes was employed for SHJ solar cells, demonstrating concurrent improvement in optical and electrical characteristics (i.e., short-circuit current density (J_SC) and V_OC). Periodic IP structures show superior light-harvesting properties as most of the incident rays bounce three times on the walls of the IPs but only twice between conventional random upright pyramids (UPs). The high minority carrier lifetime of the IP structures after a-Si:H passivation results in an enhanced V_OC by 28 mV, showing improved carrier collection efficiency due to the superior passivation of the IP structure over the random UP structures. The superior antireflective (AR) ability and passivation results demonstrate that the IP structure has the potential to replace conventional UP structures to further boost the efficiency in solar cell applications.

[en] Nanofluids, colloidal dispersions of nanoparticles in a base fluid such as water, can afford very significant Critical Heat Flux (CHF) enhancement. Such engineered fluids potentially could be employed in reactors as advanced coolants in safety systems with significant safety and economic advantages. However, a satisfactory explanation of the CHF enhancement mechanism in nanofluids is lacking. To close this gap, we have identified the important boiling parameters to be measured and have deployed a pool boiling facility to measure them. The facility is equipped with a thin indium-tin-oxide heater deposited over a sapphire substrate. An intra-red high-speed camera and an optical probe are used to measure the temperature distribution on the heater and the hydrodynamics above the heater, respectively. The first data generated with this facility already provide some clue on the CHF enhancement mechanism in nanofluids. (author)

[en] We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.

[en] Nanofluids, colloidal dispersions of nanoparticles in a base fluid such as water, can afford very significant Critical Heat Flux (CHF) enhancement. Such engineered fluids potentially could be employed in reactors as advanced coolants in safety systems with significant safety and economic advantages. However, a satisfactory explanation of the CHF enhancement mechanism in nanofluids is lacking. To close this gap, we have identified the important boiling parameters to be measured. These are the properties (e.g., density, viscosity, thermal conductivity, specific heat, vaporization enthalpy, surface tension), hydrodynamic parameters (i.e., bubble size, bubble velocity, departure frequency, hot/dry spot dynamics) and surface conditions (i.e., contact angle, nucleation site density). We have also deployed a pool boiling facility in which many such parameters can be measured. The facility is equipped with a thin indium-tin-oxide heater deposited over a sapphire substrate. An infra-red high-speed camera and an optical probe are used to measure the temperature distribution on the heater and the hydrodynamics above the heater, respectively. The first data generated with this facility already provide some clue on the CHF enhancement mechanism in nanofluids. Specifically, the progression to burnout in a pure fluid (ethanol in this case) is characterized by a smoothly-shaped and steadily-expanding hot spot. By contrast, in the ethanol-based nanofluid the hot spot pulsates and the progression to burnout lasts longer, although the nanofluid CHF is higher than the pure fluid CHF. The presence of a nanoparticle deposition layer on the heater surface seems to enhance wettability and aid hot spot dissipation, thus delaying burnout.