Transient Behavior of Gas Entrainment Caused by Surface Vortex

A compact sodium-cooled reactor is an important candidate as a fast breeder reactor (FBR) and has been investigated in the feasibility study of FBR cycle. Due to the compact sizing of the reactor vessel, gas entrainment at the free surface of sodium coolant becomes one of the significant issues for reactor design, and it is required to clarify the criterion of gas entrainment at free surface and the tolerance. In the present study, some visualization experiments were performed in a water-air system focusing on the gas entrainment due to surface vortex and its transient phenomena. Influences of horizontal velocity were clarified by the visualization. The gas entrainment due to the surface vortex occurs intermittently. Time trends of circulation and length of gas core for the intermittent surface vortices were measured by the particle image velocimetry and visualization. It was found that the gas core length extends with time delay to the increase of circulation around the vortex.     

Effect of interfacial heat exchange on thermocapillary flow in a cylindrical liquid bridge in microgravity

The effect of interfacial heat exchange on thermocapillary flow in a cylindrical liquid bridge of 1 cst silicone oil (with Prandtl number 16.0) with aspect ratio 1.8 in microgravity, was investigated in an extended range of Biot number. With both constant and linearly distributed ambient temperature, the computed results predict that the marginal stability curve for the thermocapillary flow exhibits a roughly convex trend. In the range of small Biot number, however, a sharp local maximum exists with a special oscillation mode of azimuthal wave number m = 0, in contrast to the other cases with m = 1. In addition, the normalized “thermal” energy balance between the basic state and the critical perturbation of the thermocapillary flow was investigated. Finally, the effect of the interfacial heat exchange on the thermocapillary flow in a liquid bridge of low Prandtl number fluid in microgravity was investigated as a comparison.     

Effects of water chemistry and potential distribution on electrochemical corrosion potential measurements in 553 K pure water

The effects of water chemistry distribution on the potential of a reference electrode and of the potential distribution on the measured potential should be known qualitatively to obtain accurate electrochemical corrosion potential (ECP) data in BWRs. First, the effects of oxygen on a platinum reference electrode were studied in 553 K pure water containing dissolved hydrogen (DH) concentration of 26–105 μg kg^?1 (ppb). The platinum electrode worked in the same way as the theoretical hydrogen electrode under the condition that the molar ratio of DH to dissolved oxygen (DO) was more than 10 and that DO was less than 100 ppb. Second, the effects of potential distribution on the measured potential were studied by using the ECP measurement part without platinum deposition on the surfaces connected to another ECP measurement part with platinum deposition on the surfaces in 553 K pure water containing 100–130 ppb of DH or 100–130 ppb of DH plus 400 ppb of hydrogen peroxide. Measured potentials for each ECP measurement part were in good agreement with literature data for each surface condition. The lead wire connecting point did not affect the measured potential. Potential should be measured at the nearest point from the reference electrode in which case it will be not affected by either the potential distribution or the connection point of the lead wire in pure water.     

Advanced Method for Measuring Proteinase A in Beer and Application to Brewing*

Proteinase A, excreted from yeast cells into beer during fermentation in the brewing process, has been shown to degrade foam-active proteins and to decrease foam stability. In order to improve the measurement of this enzyme in beer, a new fluorescent peptide, MOCAc-Ala-Pro-Ala-Lys-Phe-Phe-Arg-Leu-Lys (Dnp)-NH₂, was synthesised and applied to the accurate and rapid estimation of proteinase A in commercial beer and fermenting wort. This novel substrate is several hundred times more sensitive to proteinase A than other previously reported synthetic substrates or native protein substrates. The concentration of proteinase A in beer is closely related to foam stability and proteinase A activity was found to increase gradually during fermentation. The concentration of proteinase A excreted from yeast cells is also closely related to the vitality of pitching yeast cells. This new method was successfully applied to the evaluation of yeast vitality and the development of optimum yeast handling procedures.     

Determination of standard gibbs energies of formation of Fe2Mo3O12, Fe2Mo3O8, Fe2MoO4, and FeMoO4 of the Fe-Mo-O ternary system and μ phase of the Fe-Mo binary system by electromotive force measurement using a Y2O3-stabilized ZrO2 solid electrolyte

The standard Gibbs energies of formation of Fe₂Mo₃O₁₂, Fe₂Mo₃O₈, FeMoO₄, and Fe₂MoO₄ of the Fe-Mo-O ternary system and the μ phase of the Fe-Mo binary system have been determined by measuring electromotive forces of galvanic cells having an Y₂O₃-stabilized ZrO₂ solid electrolyte. The results are as follows: $$\begin{gathered} \Delta _f G^\circ (FeMoO_4 )/kJ \cdot mol^{ - 1} = - 1053.5 + 0.2983(T/K) \pm 0.4 \hfill \\ Temperature range: 1112 to 1339 K \hfill \\ \Delta _f G^\circ (Fe_2 Mo_3 O_8 )/kJ \cdot mol^{ - 1} = - 2347 + 0.6814(T/K) \pm 1 \hfill \\ Temperature range: 1112 to 1339 K \hfill \\ \Delta _f G^\circ (Fe_2 Mo_3 O_{12} )/kJ \cdot mol^{ - 1} = - 2993 + 0.9105(T/K) \pm 2 \hfill \\ Temperature range: 1040 to 1145 K \hfill \\ \Delta _f G^\circ (Fe_{0.58} Mo_{0.42} )/kJ \cdot mol^{ - 1} = - 18.7 + 0.0117(T/K) \pm 0.1 \hfill \\ Temperature range: 1162 to 1223 K \hfill \\ \Delta _f G^\circ (Fe_2 MoO_4 )/kJ \cdot mol^{ - 1} = - 1174 + 0.342(T/K) \pm 1 \hfill \\ Temperature range: 1243 to 1466 K \hfill \\ \end{gathered} $$ where the standard pressure is 1 bar (100 kPa).     

Oxygen Uptake and Release Mechanism of Lithium Manganese Ferrite in the Low Temperature Range of 573–773 K

Oxygen uptake and release of (Li,Mn) ferrite [LMF; (Li_0.60Mn_1.20Fe_1.20)_1−δO₄; δ= 0.007 to 0.033] was investigated concerning the relations between redox reactions of ferrite and cation migration. Mössbauer spectroscopy and X-ray diffractometry showed that some of the Li⁺ and Fe³⁺ ions migrated from the A sites to the B sites of the spinel-type structure and Mn⁴⁺ ions migrated from the B sites to the A sites during oxygen uptake at 573 K. The cation-deficient LMF formed by the oxygen uptake released oxygen molecules in He gas only at 660 K. The cation migration during the oxygen release was in the opposite direction of the movement during oxygen uptake at 573 K.     

Anomalous behavior of unplasticized PVC compounds in capillary flow

Capillary rheometry was performed over a temperature range of 170°–200°C and a shear-rate range of 3–3000 sec^?1 on an unplasticized poly(vinyl chloride) compound. The data were corrected for the effect of pressure on viscosity, for pressure loss in the barrel and at the capillary entrance, and for the non-Newtonian velocity profile. The pressure coefficient of viscosity was found to be in the same order of magnitude as those previously found with linear polyethylene and butadieneacrylonitrile copolymers. The pressure–shear-rate superposition of the flow curves is valid at least approximately, although the temperature–shear-rate superposition is inapplicable. The shape of flow curves at 180°, 190°, and 200°C are concave downward when they are expressed as log-shear-stress-log-shear-rate. Similar plots at 170° and 175°C, however, are very different; shear stress is independent of shear rate at low shear rates, increases somewhat and becomes independent of shear rate again at high shear rates. There is no detectable temperature dependence of flow behavior at 170° and 175°C. Irregularly shaped extrudates were obtained at higher shear rates. At constant shear rate the irregularity increased with the length of the capillary. The effect of thermal-mechanical history on the particulate and crystalline structure is discussed with possible influence on the reproducibility of the rheological data.     

Charged ultrafiltration membrane for permeation of proteins

Polyacrylonitrile-g-poly(N,N-dimethylaminoethyl methacrylate) was synthesized photochemically and quaternized. The positively charged membranes made from the quaternized graftcopolymer showed high ultrafiltration rate for water by adding poly(vinyl alcohol) to casting solution and washing it out after the casting. In buffered saline solution, the permeability of the membranes was very small at pH below isoelectric point of albumin but increased markedly at higher pH. On the other hand, the permeability for γ-globulin was very small and did not show any pH dependence.     

Correlations of Hepatic Hemodynamics,Liver Function,and Fibrosis Markers in Nonalcoholic Fatty Liver Disease: Comparison with Chronic Hepatitis Related to Hepatitis C Virus

The progression of chronic liver disease differs by etiology. The aim of this study was to elucidate the difference in disease progression between chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) by means of fibrosis markers, liver function, and hepatic tissue blood flow (TBF). Xenon computed tomography (Xe-CT) was performed in 139 patients with NAFLD and 152 patients with CHC (including liver cirrhosis (LC)). The cutoff values for fibrosis markers were compared between NAFLD and CHC, and correlations between hepatic TBF and liver function tests were examined at each fibrosis stage. The cutoff values for detection of the advanced fibrosis stage were lower in NAFLD than in CHC. Although portal venous TBF (PVTBF) correlated with liver function tests, PVTBF in initial LC caused by nonalcoholic steatohepatitis (NASH-LC) was significantly lower than that in hepatitis C virus (C-LC) (p = 0.014). Conversely, the liver function tests in NASH-LC were higher than those in C-LC (p < 0.05). It is important to recognize the difference between NAFLD and CHC. We concluded that changes in hepatic blood flow occurred during the earliest stage of hepatic fibrosis in patients with NAFLD; therefore, patients with NAFLD need to be followed carefully.     

Internal oxidation of dilute silver alloys

Internal oxidation of dilute silver alloys containing Al, Mg, Zn, Cu, and Sn was studied in air at temperatures between 573 K and 1173 K. Electrical resistivity, gravimetric, and gas-extraction measurements were made. The general trend of the resistivity is that it increases upon oxidation at lower temperatures and the resistivity decreases at higher temperatures in all of these alloys except Ag-Mg, in which it increases even at 1173 K. The increase in resistivity is considered to be related to the formation of clusters having excess oxygen. A detailed investigation was performed on Ag-Al alloys. The O/Al ratio in the clusters in Ag-2.2 at.% Al is much higher on oxidation at 773 K than for stoichiometric Al₂O₃ at 1173 K. The clusters release the excess oxygen on subsequent annealing at high temperatures, and decompose to stable Al₂O₃ at 1173 K.