Semi-quantitative approach to estimating GFR by magnetic resonance imaging

Objective: The purpose of this study was to compare a semi-quantitative approach to estimating glomerular filtration rate (GFR) by magnetic resonance imaging with radionuclide calculation of GFR, and to investigate whether spin echo or gradient echo is more suitable for estimating GFR.Methods and patients: Fourteen kidneys of seven patients (GFR ranging from 26 to 57 ml/min) were studied. Spin echo and gradient echo sequences interleaving each other at every excitation were used. After intravenous injection of gadopentetate dimeglumine, serial scans were performed. The signal intensities measured in the regions of interest were converted to time-transverse relaxation rate changes for both spin echo (ΔR2) and gradient echo (ΔR2^*). The areas under the time-ΔR2 and time-ΔR2^* curves were calculated as a semi-quantitative index of GFR for both spin echo and gradient echo images, and the results were compared by GFR measured by radionuclide imaging.Results: The semi-quantitative index of the GFR calculated from spin echo images showed a significant correlation with the GFR measured by radionuclide imaging (r=0.85,P<0.001). On the other hand, the semi-quantitative index of the GFR calculated from gradient echo images showed no such correlation (r=0.46,P=0.10).Conclusion: Spin echo sequences may be more suitable than gradient echo sequences for the evaluation of GFR.     

Thermal conductivity of high porosity alumina refractory bricks made by a slurry gelation and foaming method

Alumina has high heat resistance and corrosion resistance compared to other ceramics such as silica or mullite. However, for its application to refractory bricks, its high thermal conductivity must be reduced. To reduce this thermal conductivity by increasing the porosity, a GS (gelation of slurry) method that can produce high porosity solid foam was applied here to produce the alumina refractory brick. This method was successfully applied to produce alumina foam with high porosity and thermal conductivity of the foam is evaluated. At room temperature, the thermal conductivity was about 0.12 W/mK when the foam density was 0.1 g/cm³. At elevated temperature above 783 K, thermal conductivity of the foam was strongly affected by heat radiation and increased with increasing temperature, in contrast to the thermal conductivity of alumina itself, which decreased with increasing temperature. The alumina foams developed here achieved sufficient thermal insulating properties for use in refractory bricks.     

Defect sizing of small inclined cracks on a free surface using multi-tip waves

The most effective method of ultrasonic defect sizing is recognized to be the tip echo method. However, tip waves have very weak intensities, and require skill and experience by the operator. Recently, low noise fully digital flaw detectors have been developed, which make it easy to capture several tip echoes simultaneously. Experiments were carried out using a fully digital detector for the reflection by an artificial inclined crack of 1.5 mm height on a free surface, and numerical simulations were also performed to distinguish each tip echo. Crack height, inclination angle, and crack width were estimated using the tip echo distances of the experimental data from one side. The results show good agreement with actual values. The method is stable for changes in probe position. An experiment on fatigue cracks was also performed. Automatic inspection will be possible using the results of this method in the near future. Many tip waves are generated by the deflection of ultrasound from crack tips and corners, and the evaluation of defect size can be accomplished by full use of the tip waves.     

Cloning and Characterization of clpB in Acetobacter pasteurianus NBRC 3283

The clpB gene in Acetobacter pasteurianus was cloned and characterized. Although the clpB gene was transcribed in response to a temperature shift and exposure to ethanol, the clpB disruption mutant was only affected by high temperature, suggesting that the ClpB protein is closely associated with heat resistance in A. pasteurianus.     

Multiple melting behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) investigated by differential scanning calorimetry and infrared spectroscopy

The multiple melting behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(HB-co-HHx)) (HHx = 12 mol%) isothermally crystallized from the melt state has been characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The influence of different experimental variables (such as crystallization temperature, time, and heating rate) on the multiple melting behavior of P(HB-co-HHx) was investigated by using DSC. Moreover, it has been further examined by monitoring intensity changes of the characteristic IR bands during the subsequent heating process. For the isothermally crystallized P(HB-co-HHx) samples, triple melting peaks were observed upon heating. The weak lowest-temperature DSC endotherm I always appears at the position just above the crystallization temperature, and shifts to a higher temperature linearly with the logarithm of the crystallization time. The combination of DSC and IR results suggested that the occurrence of peak I was a result of the melting of crystals formed upon long-time annealing. As for the other two main melting endothermic peaks, endotherm II corresponds to the melting of crystals formed during the primary crystallization, and endotherm III is ascribed to the melting peak of the crystals formed by recrystallization during the heating process.     

Prediction of heat exchanger capacity by thermal network method (Influence of thermal conduction in fins on capacity of a condenser)

This paper describes the influence of heat flow from high‐temperature refrigerant to low‐temperature refrigerant through fins by thermal conduction. To estimate that influence, we applied a thermal network method that can consider refrigerant quality distribution in the heat exchanger. At the same time, for verifying the estimation, an experiment was performed with a two‐row, two‐pass heat exchanger. Prediction shows that the heat transfer capacity of a condenser is reduced by 3% for a simple two‐row, two‐pass heat exchanger by heat conduction in fins. Comparison of experimental results and predicted results proves that the prediction error was within 1% for condenser capacity. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(2): 101–114, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20184     

Fabrication and Sintering of Fine Yttria-Doped Ceria Powder

Yttria–doped ceria powder was prepared from oxalate precursors. The oxalate coprecipitation bath parameters were closely monitored and found to influence the sintering behavior of the subsequently obtained oxide powders strongly. The use of concentrated (Ce,Y) metal nitrate solutions and dilute neutralized oxalic acid for coprecipitation were identified as the most–important parameters. Following calcination at 700°C, compacts of such powders were sintered to high density (98%) at 1400°C (4 h). Ball milling of the powder further reduced the sintering temperature. Dry milling, for tape–casting applications of the powder in particular, was more effective than wet milling. Tape–cast membranes were fired at 1400°C (2 h), with resulting densities of 98%.