We measured velocity distributions in the anterior chamber of porcine eyes under simulated cataract surgery using stereoscopic particle image velocimetry (stereo-PIV). The surface of the cornea was detected based on the images of laser-induced fluorescent light emitted from fluorescent dye solution introduced in a posterior chamber. A coaxial phacoemulsification procedure was simulated with standard size (standard coaxial phacoemulsification) and smaller (micro coaxial phacoemulsification) surgical instruments. In both cases, an asymmetric flow rate of irrigation was observed, although both irrigation ports had the same dimensions prior to insertion into the eye. In cases where the tip of the handpiece was placed farther away from the top of the cornea, i.e., closer to the crystalline lens, direct impingement of irrigation flow onto the cornea surface was avoided and the flow turned back toward the handpiece along the surface of the corneal endothelium. Viscous shear stress on the corneal endothelium was computed based on the measured mean velocity distribution. The maximum shear stress for most cases exceeded 0.1 Pa, which is comparable to the shear stress that caused detachment of the corneal endothelial cells reported by Kaji et al. in Cornea 24:S55–S58, (2005). When direct impingement of the irrigation flow was avoided, the shear stress was reduced considerably. 相似文献
Recently, stricter diesel particulate emission standards have been set in many countries. As for the after-treatment of exhaust
gas, a diesel filter has been developed to trap diesel particles inside small-scale porous structure. Since measurement of
flow in the filter is impossible, the phenomena of particle deposition in the filter are not well understood. In this study,
we conducted Lattice Boltzmann simulation on flow in the newly developed diesel filter. The soot deposition was included to
consider the particle trap in the filter. The inner structure of the diesel filter as well as trapped soot region was scanned
by an X-ray CT technique. Results show that the flow pattern is largely changed when the soot is attached to the filter surface.
By comparing simulation results with CT images, soot accumulation region is well predicted. It is found that the amount of
trapped soot is proportional to the filter back-pressure even when soot deposition probability is changed. 相似文献
An energy‐domain 57Fe‐Mössbauer spectrometer using synchrotron radiation (SR) with a diamond anvil cell (DAC) has been developed for ultrahigh‐pressure measurements. The main optical system consists of a single‐line pure nuclear Bragg reflection from an oscillating 57FeBO3 single crystal near the Néel temperature and an X‐ray focusing device. The developed spectrometer can filter the Doppler‐shifted single‐line 57Fe‐Mössbauer radiation with a narrow bandwidth of neV order from a broadband SR source. The focused incident X‐rays make it easy to measure a small specimen in the DAC. The present paper introduces the design and performance of the SR 57Fe‐Mössbauer spectrometer and its demonstrative applications including the newly discovered result of a pressure‐induced magnetic phase transition of polycrystalline 57Fe3BO6 and an unknown high‐pressure phase of Gd57Fe2 alloy placed in a DAC under high pressures up to 302 GPa. The achievement of Mössbauer spectroscopy in the multimegabar range is of particular interest to researchers studying the nature of the Earth's core. 相似文献
The resultant local Seebeck coefficient αR (=αS−αT) at the interface of a thermoelement has not yet been measured, although it is an important factor governing the thermoelectric
efficiency, where αS is the local Seebeck coefficient and αT is the one caused by the Thomson effect. It is shown in this paper that αS, αT, and αR of the p- and n-type Cu/Bi–Te/Cu composites are obtained analytically and experimentally on the assumption that the local temperature of
the composite on which the temperature difference ΔT is imposed varies linearly with changes in position along the composite. They were indeed estimated as a function of position
from the local experimental data of R,ΔI,ΔT, and V generated by applying an additional current of ±I to the composite, where R is the electrical resistance and ΔI is a current generated by the composite. As a result, it was found that the absolute values of αS at the hot interface of the p- and n-type composites are approximately 1.5 and 1.4 times higher than their lowest values in the middle region of the composite,
respectively, while those of αT are less than 8% of αS all over the composite and are so small that the relation αR≈αS can be held. We thus succeeded in measuring αR at the interfaces of the composite. 相似文献
The local Seebeck coefficient αL and the resultant Seebeck coefficient αR of M/Bi0.88Sb0.12/M (M = Cu and Ni) composites with different thicknesses tBi–Sb of Bi–Sb alloy were measured as functions of z and T, where T is the absolute temperature, z is the distance from a center of Bi–Sb alloy to the middle point of two probes and αL and αR were measured using two probes separated by s=1.0 mm and s=tBi−Sb+0.1 mm, respectively. As a result, αL was enhanced extremely at the position of 0.2–0.3 mm away from the interfaces, while the local temperature along a composite
varies linearly with changes in z within Bi–Sb alloy. The local maximum of αR at 344 K appeared at tBi−Sb≈0.9 mm, so that it is expected to increase up to −167 μV/K at tBi−Sb=0.87 mm from the expression fitted well to the experimental data, which is 2.1 times as large as the intrinsic α at 344 K of Bi–Sb alloy. Such a local enhancement in αL would probably be caused by a temperature gradient across the depletion layer formed at the interface. The thermoelectric
figure of merit ZT of a composite with an optimum tBi−Sb of 0.87 mm is expected to reach the large value of 0.98 at 344 K, which corresponds to 4.5 times as high a value as ZT=0.22 at 344 K of Bi–Sb alloy. It is thus considered that the increase in αL at the interface is available as a useful mean of further increase in ZT of thermoelectric devices. 相似文献
In the present paper, we report a new approach toward light-harvesting reverse micellar systems from molecular blends of anthracene and perylene building blocks. The self-assembly initiated by protonation of the molecular blends gave rise to the mixed reverse micelles, in which intermolecular energy transfer from the anthracene to the perylene chromophores was observed. The atomic force microscope (AFM) studies on the reverse micelles prepared from the donor and acceptor blends at a range of the feed ratios showed a number of nanoscale-sized spherical objects homogeneously dispersed on the highly oriented pyrolytic graphite (HOPG) substrate. The critical micelle concentration (cmc) values of the reversed micelles at the donor:acceptor ratios of 100:0, 50:50, and 0:100 were estimated to be 7, 3, and 10 μM by fluorescence batch titrations, respectively, indicating that the cmc values should be almost equivalent regardless of the constitution of each chromophoric component. Attempt to generate the mixed reverse micelles through pairwise mixing of the donor- and acceptor-based reverse micelles resulted in spectral behaviors identical with those obtained by the self-assembly employing the donor-acceptor blends. This suggests that these two reverse micelles undergo thermodynamic exchange of the surfactant molecules to afford the mixed reverse micelles when mixing the two discrete reverse micellar systems. 相似文献
Going separate ways : By using π‐allyl–palladium chemistry (path A) and PdII‐catalyzed Claisen chemistry (path B), a highly selective stereodivergent synthesis of separable amide rotamers was achieved (see scheme).