Three-Dimensional Lattice Boltzmann Simulation of Two-Phase Flow Containing a Deformable Body with a Viscoelastic Membrane

First published in Communications in Commun. Comput. Phys. in No. 5, 9 (2011), published by Global Science PressThe lattice Boltzmann method (LBM) with an elastic model is applied to the simulation of two-phase flows containing a deformable body with a viscoelastic membrane. The numerical method is based on the LBM for incompressible two-phase fluid flows with the same density. The body has an internal fluid covered by a viscoelastic membrane of a finite thickness. An elastic model is introduced to the LBM in order to determine the elastic forces acting on the viscoelastic membrane of the body. In the present method, we take account of changes in surface area of the membrane and in total volume of the body as well as shear deformation of the membrane. By using this method, we calculate two problems, the behavior of an initially spherical body under shear flow and the motion of a body with initially spherical or biconcave discoidal shape in square pipe flow. Calculated deformations of the body (the Taylor shape parameter) for various shear rates are in good agreement with other numerical results. Moreover, tank-treading motion, which is a characteristic motion of viscoelastic bodies in shear flows, is simulated by the present method.ArticleCommunications in Computational Physics. 9(5):1397-1413 (2011)journal articl

Lattice Boltzmann simulation of nucleate pool boiling in saturated liquid

First published in Communications in Commun. Comput. Phys. in No. 5, 9 (2011), published by Global Science PressA thermal lattice Boltzmann method (LBM) for two-phase fluid flows in nucleate pool boiling process is proposed. In the present method, a new function for heat transfer is introduced to the isothermal LBM for two-phase immiscible fluids with large density differences. The calculated temperature is substituted into the pressure tensor, which is used for the calculation of an order parameter representing two phases so that bubbles can be formed by nucleate boiling. By using this method, two-dimensional simulations of nucleate pool boiling by a heat source on a solid wall are carried out with the boundary condition for a constant heat flux. The flow characteristics and temperature distribution in the nucleate pool boiling process are obtained. It is seen that a bubble nucleation is formed at first and then the bubble grows and leaves the wall, finally going up with deformation by the buoyant effect. In addition, the effects of the gravity and the surface wettability on the bubble diameter at departure are numerically investigated. The calculated results are in qualitative agreement with other theoretical predictions with available experimental data.ArticleCommunications in Computational Physics. 9(5):1347-1361 (2011)journal articl

Disequilibrium REE compositions of garnet and zircon in migmatites reflecting different growth timings during single metamorphism (Aoyama area, Ryoke belt, Japan)

Chemical disequilibrium of coexisting garnet and zircon in pelitic migmatites (Aoyama area, Ryoke belt, SW Japan) is shown by microtextural evidence and their heavy rare earth element (HREE) patterns. In zircon, two stages of metamorphic rim growth is observed under cathodoluminescence image, although their SHRIMP UPb zircon ages are similar at ca. 92 Ma. Inner and outer rims of zircon tend to show steep HREE patterns irrespective of the UPb age. The inner rims tend to give higher U content than the outer rims; some rim analyses give various Th/U ratios of 0.02–0.07 compared to the very low (<0.02) values seen in the rest of rim analyses. The higher-Th/U values are ascribed to the mixed analyses between thin prograde domains and thick retrograde overgrowths. Zircon grains with inclusions similar to previously-reported melt inclusions are further enclosed in garnet, supporting the growth of thin zircon domains coexisting with garnet during the prograde metamorphism. Garnet rims are commonly replaced by biotite-plagioclase intergrowths, indicating a back reaction with partial melts. Garnet exhibits decrease in HREE and Y concentrations towards the rim, pointing to its prograde growth. The garnet cores have prograde xenotime inclusions, show steep HREE patterns, and yield growth temperature of ~530–570 °C by a YAG-xenotime thermometer. On the other hand, the garnet rims have no xenotime inclusion and show flat HREE patterns. Rare garnet domains including sillimanite needles also show flat HREE patterns and low Y concentrations, which is interpreted as a product of dehydration melting consuming biotite and sillimanite at near-peak P-T conditions (~800 °C and ~0.5 GPa). One such garnet domain gives nearly-equilibrium REE distribution pattern when paired with the matrix zircon rims. Retrograde xenotime is present in the cracks in garnet and in the biotite-plagioclase intergrowths, suggesting that retrograde breakdown of garnet released HREE and Y to form it. Considering the availability of HREE and Zr and presence of melt inclusions in zircon rims, most part of the zircon rims with positive HREE patterns likely grew during the melt crystallization stage, meaning that the zircon rims and presently-preserved garnet domains did not grow in equilibrium. The above scenario was tested by the array plot analysis and it gave a result consistent with microtextural and traditional REE distribution constraints. Combination of microtextural and the array plot analyses may become a powerful tool to reliably correlate the zircon ages to the P-T evolution of the high-grade metamorphic rocks

BHLHA15-Positive Secretory Precursor Cells Can Give Rise to Tumors in Intestine and Colon in Mice

Background & Aims: The intestinal epithelium is maintained by long-lived intestinal stem cells (ISCs) that reside near the crypt base. Above the ISC zone, there are short-lived progenitors that normally give rise to lineage-specific differentiated cell types but can dedifferentiate into ISCs in certain circumstances. However, the role of epithelial dedifferentiation in cancer development has not been fully elucidated. Methods: We performed studies with Bhlha15-CreERT, Lgr5-DTR-GFP, Apc flox/flox , LSL-Notch (IC), and R26-reporter strains of mice. Some mice were given diphtheria toxin to ablate Lgr5-positive cells, were irradiated, or were given 5-fluorouracil, hydroxyurea, doxorubicin, or dextran sodium sulfate to induce intestinal or colonic tissue injury. In intestinal tissues, we analyzed the fate of progeny that expressed Bhlha15. We used microarrays and reverse-transcription PCR to analyze gene expression patterns in healthy and injured intestinal tissues and in tumors. We analyzed gene expression patterns in human colorectal tumors using The Cancer Genome Atlas data set. Results: Bhlha15 identified Paneth cells and short-lived secretory precursors (including pre-Paneth label-retaining cells) located just above the ISC zone in the intestinal epithelium. Bhlha15 + cells had no plasticity after loss of Lgr5-positive cells or irradiation. However, Bhlha15 + secretory precursors started to supply the enterocyte lineage after doxorubicin-induced epithelial injury in a Notch-dependent manner. Sustained activation of Notch converts Bhlha15 + secretory precursors to long-lived enterocyte progenitors. Administration of doxorubicin and expression of an activated form of Notch resulted in a gene expression pattern associated with enterocyte progenitors, whereas only sustained activation of Notch altered gene expression patterns in Bhlha15 + precursors toward those of ISCs. Bhlha15 + enterocyte progenitors with sustained activation of Notch formed intestinal tumors with serrated features in mice with disruption of Apc. In the colon, Bhlha15 marked secretory precursors that became stem-like, cancer-initiating cells after dextran sodium sulfate–induced injury, via activation of Src and YAP signaling. In analyses of human colorectal tumors, we associated activation of Notch with chromosome instability-type tumors with serrated features in the left colon. Conclusions: In mice, we found that short-lived precursors can undergo permanent reprogramming by activation of Notch and YAP signaling. These cells could mediate tumor formation in addition to traditional ISCs

Administration of Bone Marrow-Derived Mononuclear Cells Contributed to the Reduction of Hypoxic-Ischemic Brain Injury in Neonatal Rats

Background/Objective: Perinatal hypoxic-ischemia (HI) causes neonatal death and permanent neurological deficits. Cell therapy using various cell sources has been recently identified as a novel therapy for perinatal HI. Among the available types of cell sources, bone marrow-derived mononuclear cells (BMMNCs) have unique features for clinical application. For example, stem cells can be collected after admission, thus enabling us to perform autologous transplantation. This study aimed to investigate whether the administration of BMMNCs ameliorated HI brain injury in a neonatal rat model.Methods: Seven-day-old rats underwent left carotid artery ligation and were exposed to 8% oxygen for 60 min. BMMNCs were collected from the femurs and tibias of juvenile rats using the Ficoll–Hypaque technique and injected intravenously 24 h after the insult (1 × 105 cells). Active caspase-3, as an apoptosis marker, and ED1, as an activated microglia/macrophage marker, were evaluated immunohistochemically 48 h after the insult (vehicle, n = 9; BMMNC, n = 10). Behavioral assessments using the rotarod treadmill, gait analysis, and active avoidance tests were initiated 3 weeks after the insult (sham, n = 9, vehicle, n = 8; BMMNC, n = 8). After these behavioral tests (6 weeks after the insult), we evaluated the volumes of their hippocampi, cortices, thalami, striata, and globus pallidus.Results: The mean cell densities of the sum of four parts that were positive for active caspase-3 significantly decreased in the BMMNC group (p &lt; 0.05), whereas in the hippocampi, cortices, thalami, and striata cell densities decreased by 42, 60, 56, and 47%, respectively, although statistical significance was not attained. The number of ED1 positive cells for the sum of the four parts also significantly decreased in the BMMNC group compared to the vehicle group (p &lt; 0.05), whereas in each of the four parts the decrease was 35, 39, 47, and 36%, respectively, although statistical significance was not attained. In gait analysis, the BMMNC normalized the contact area of the affected hind paw widened by HI. The volumes of the affected striata and globus pallidus were significantly larger in the BMMNC group than in the control group.Conclusion: These results indicated that the injection of BMMNCs ameliorated HI brain injury in a neonatal rat model

Extravasated platelet aggregation in the livers of rats with drug-induced hepatic sinusoidal obstruction syndrome

Oxaliplatin-based chemotherapy plays an important role in the treatment of colorectal liver metastases. Oxaliplatin, however, causes sinusoidal obstruction syndrome (SOS), which is characterized by portal hypertension, splenomegaly, thrombocytopenia, and liver dysfunction. SOS is diagnosed histopathologically by disruption of the sinusoidal endothelium, collagen deposition, fbrosis especially around zone 3, dilatation of the sinusoidal space and congestion. This study assessed the characteristics of a rat model of SOS. SOS was induced in rats by administration of monocrotaline (MCT). Blood chemistries and macroscopic and microscopic fndings were compared in rats administered MCT and vehicle (control group). Levels of expression in the liver of CD41, P-selectin, rat endothelial cell antigen-1, CD34, and cleaved caspase-3 were analyzed immunohistochemically. Moreover, livers of these rats were analyzed by electron microscopy. Macroscopically, MCT-treated rats showed accumulation of bloody ascites and blue liver and were diagnosed with SOS histologically. Serum concentrations of aspartate aminotransferase (P=0.003), alanine aminotransferase (P=0.008), total-bilirubin (P=0.012), direct-bilirubin (P=0.007), indirect-bilirubin (P=0.003), lactate dehydrogenase (P<0.001) and hyaluronic acid (P=0.016) were signifcantly higher, and platelet counts signifcantly lower (P=0.004), in MCT-treated than in control rats. The livers of MCT-treated rats were immunohistochemically positive for CD41 and P-selectin, suggesting platelet aggregates; for rat endothelial cell antigen-1 and CD34, suggesting sinusoidal endothelial disorder; and for cleaved caspase-3, suggesting hepatocyte apoptosis. Electron microscopic fndings revealed platelet aggregation in the space of Disse in the MCT group. Extravasated platelet aggregation in Disse\u27s space may be involved in the development of SOS

Constraining the fluid activity in the crust by chlorine concentration of biotite and apatite -An exaple from Balchenfjella, Sør Rondane Mountains, East Antactica

第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所　2階大会議室前フロ