In many of the mixed flow pumps that have been studied in the past, the impeller has a sweepback wing. Especially, the positive slope characteristics have been studied to operate pump in a stable ...regime. The cause of the positive slope in the characteristic curve of the mixed flow pump is the reverse flow, with the turning becomes stronger, at the leading edge of the blade tip side in the flow rate range. Also, at the flow rate at which the slope of the characteristic curve becomes positive, the angular momentum becomes negative at the leading edge of the impeller, and the work amount sharply decreases at the leading edge more than the work amount increase at the trailing edge so the angular momentum decreases. However, the influence of the forward rake and skew blade on the performance, the positive slope characteristics, and the internal flow have not been studied much. In this study, we designed and analysed a forward rake and skew blade mixed flow pump. About the forward rake and skew blade, we found the cause of the positive slope characteristics is the same reason as the sweepback wing, but the flow rate range of occurrence of the positive slope characteristics was lower in the forward rake and skew pump than in the sweepback pump.
In the present study, we have attempted to elucidate the effects of the intra-arterial injection of microglia on the global ischemia-induced functional and morphological deficits of hippocampal CA1 ...neurons. When PKH26-labeled immortalized microglial cells, GMIR1, were injected into the subclavian artery, these exogenous microglia were found to accumulate in the hippocampus at 24 h after ischemia. In hippocampal slices prepared from medium-injected rats subjected to ischemia 48 h earlier, synaptic dysfunctions including a significant reduction of synaptic responses and a marked reduction of long-term potentiation (LTP) of the CA3–CA1 Schaffer collateral synapses were observed. At this stage, however, neither significant neuronal degeneration nor gliosis was observed in the hippocampus. At 96 h after ischemia, there was a total loss of the synaptic activity and a marked neuronal death in the CA1 subfield. In contrast, the basal synaptic transmission and LTP of the CA3–CA1 synapses were well preserved after ischemia in the slices prepared from the microglia-injected animals. We also found the microglial-conditioned medium (MCM) to significantly increase the frequency of the spontaneous postsynaptic currents of CA1 neurons without affecting the amplitude, thus indicating that MCM increased the provability of the neurotransmitter release. The protective effect of the intra-arterial injected microglia against the ischemia-induced neuronal degeneration in the hippocampus was substantiated by immunohistochemical and immunoblot analyses. Furthermore, the arterial-injected microglia prevented the ischemia-induced decline of the brain-derived neurotrophic factor (BDNF) levels in CA1 neurons. These observations strongly suggest that the arterial-injection of microglia protected CA1 neurons against the ischemia-induced neuronal degeneration. The restoration of the ischemia-induced synaptic deficits and the resultant reduction of the BDNF levels in CA1 neurons, possibly by the release of diffusible factor(s), might thus contribute to the protective effect of the arterial-injection of microglia against ischemia-induced neuronal degeneration.
We have assessed the effects of habitat fragmentation on understory tree communities in mesic temperate forests of the Tokachi plain of northern Japan. Tree community composition was analyzed across ...13 forest fragments of various sizes ranging from 0.30 to 8.51 ha. The community composition varied along the edge-to-interior gradient: there was a lower abundance of shade-tolerant shrubs in forest edges than in forest interiors, while saplings of dominant canopy trees and pioneer trees were more abundant near the edges. The edge influence extended approximately 56 m into the forest interiors. Even the interior area of small fragments were likely to be affected not only by the nearest edge but also by more distant edges. Consequently, most areas in fragments smaller than 2 ha were covered by these “edge-type” communities. These results indicate that it is of primary importance to conserve and restore forests with an area at least larger than several hectares to sustain forest-interior tree communities.
1. With ever-increasing human pressure on ecosystems, it is critically important to predict how ecosystem functions will respond to such human-induced perturbations. We define perturbations as either ...changes to abiotic environment (e.g. eutrophication, climate change) that indirectly affects biota, or direct changes to biota (e.g. species introductions). While two lines of research in ecology, biodiversity–ecosystem function (BDEF) and ecological resilience (ER) research, have addressed this issue, both fields of research have nontrivial shortcomings in their abilities to address a wide range of realistic scenarios. 2. We outline how an integrated research framework may foster a deeper understanding of the functional consequences of perturbations via simultaneous application of (i) process-based mechanistic predictions using trait-based approaches and (ii) detection of empirical patterns of functional changes along real perturbation gradients. In this context, the complexities of ecological interactions and evolutionary perspectives should be integrated into future research. 3. Synthesis and applications. Management of human-impacted ecosystems can be guided most directly by understanding the response of ecosystem functions to controllable perturbations. In particular, we need to characterize the form of a wide range of perturbation–function relationships and to draw connections between those patterns and the underlying ecological processes. We anticipate that the integrated perspectives will also be helpful for managers to derive practical implications for management from academic literature.
The performance of PIV system for combusting flow was evaluated by using artificial images generated from computer graphics and experimental data. The influences of shutter speed, filter, laser power ...and the PIV algorithms on the measurement uncertainty were studied for optimizing the performance of the PIV system. This system was applied to the spray combustor model for boiler, and the flow patterns with and without combustion were elucidated. Results showed that the burner flow generates complex three-dimensional flow pattern, which contributes to highly mixed fuel flow in the combustor. Although the flow pattern with and without combustion is similar, the growth of burner flow area and an increase in velocity magnitude are found in the flow field by the influence of chemical reactions in combustion.
To conduct a product development of turbomachinery continuously and developmentally, an approach using large eddy simulation (LES) should be one of the mainstream, because it is already essential to ...utilize computational fluid dynamics (CFD) using Reynolds averaged Navier–Stokes Simulation in industrial field. In recent years, the demand for a high-efficiency and low-noise jet fan, which is used for ventilation of a tunnel of a carriage way, is getting higher and higher. However, to conduct noise prediction of the jet fan with high accuracy, it needs the high-performance computing technique using a supercomputer. In this study, CFD of the jet fan is conducted using LES. Noise simulation is also conducted using the LES result. Moreover, the fine mesh model is generated by refining a coarse mesh, and LES is conducted using the Earth Simulator. The result of surface pressure using the fine mesh is clearer than the one using the coarse mesh.
Graphical abstract
The effects of hypothermia on caspase-3 activation were investigated in the newborn rat brain after hypoxia–ischemia (HI). Intense caspase-3 activation was observed in the control brains after HI, ...but this activation was significantly reduced by postischemic hypothermia. These findings suggest that the inhibition of caspase-3 activation may be an interventional point underlying the neuroprotective effect of hypothermia in neonates.
Vibration phenomena of a guide vane seem to be generated by a fluid exciting force working on the guide vane in unsteady flow field. Thus, in order to understand the vibration mechanism of the guide ...vane, it is important to reveal unsteady field inside a bend having the guide vane. In this paper, vibration phenomena of the guide vane inside the bend were considered by using numerical simulation. In order to decide analysis conditions of Large Eddy Simulation (LES), the results of LES were compared to the ones of Particle Image Velocimetry (PIV) for the downscaling model. Moreover, Fluid-Structure Interaction (FSI) analysis was conducted for the mitre bend having the guide vane modelled in actual scale. As a result, stress fluctuation at the centre of the trailing edge of the guide vane was largest. This result indicates that vibration phenomena are possible to occur on the trailing edge of the guide vane.
The serum concentration of leptin in 10 week old virgin ICR mice assessed by RIA was 1.70 ± 0.08 ng/ml. The serum leptin concentration in the pregnant mice mated at 10 weeks of age significantly ...increased from day 11 of pregnancy and reached a peak on day 17 of pregnancy (42.2 ± 4.8 ng/ml). After the delivery, the serum leptin concentration rapidly decreased and reached the level of the virgin mouse on the seventh day in the puerperium. Tissue contents of leptin in the placenta, the decidua, the uterus, and the adipose tissue were between 40 to 130 ng/g wet tissue. However, leptin mRNA was expressed only in the adipose tissue and the level of leptin mRNA on days 13 and 17 of pregnancy increased 3- to 5-fold compared with that of virgin mouse. Tissue content of leptin in the adipose tissue significantly increased from day 17 of pregnancy compared with that of the virgin mouse. The m-leptin secretion from the adipose tissue also significantly increasedin vitro.These results suggest that leptin, which was secreted by adipose tissue, may play important roles in mouse reproduction after midpregnancy.
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