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Reducing heat loss is one of the most important development concerns for improving the thermal efficiency of the diesel engine. In order to know heat transfer through the combustion chamber wall mo...

Owing to cavitation inside the nozzle, spray breakup, and complex flow fields in the cylinder of a spark ignition engine, a certain degree of cycle-to-cycle variation (CCV) remains in different spray cycles under the same operating conditions, thereby affecting the spark ignition engine significantly. Therefore, the effect of cross-flow on the cyclic variation of the spray characteristics is investigated in this work. The CCV of fuel spray characteristics is evaluated via the statistical analysis of 30 repeated experiments under atmospheric pressure. First, the coefficient of variation (COV) is used to assess variations in the spray penetration, area, and optical thickness. Moreover, the effects of injection pressure and cross-flow velocity on the statistical characteristics of the spray are analyzed at the end of injection (EOI). Finally, a dimensionless “Ins number”, which is defined as the parameter of any spray characteristic at a certain time divided by the average experimental value, is proposed to evaluate the spray variation characteristics under cross-flow conditions. Therefore, when the absolute value of the Ins number approaches 1, the CCV of the spray characteristic parameters is low. Results show that the COV of the spray penetration is the largest in the initial stage of injection and then decreases gradually. Meanwhile, the COV of the vertical penetration can be categorized into two stages. Furthermore, it is discovered that the variation in the horizontal penetration is enhanced by the cross-flow and injection pressure at the EOI. In addition, in terms of the COV of the optical thickness, the variation on the windward side is greater, and the cross-flow enhanced the variation in the spray tip region. Most of the Ins numbers of the spray characteristics range from 0.9 to 1.1 (±10%) in this study, and they can provide data support for improving the accuracy of empirical prediction equations and models.

Downsizing the hole diameter and increasing the injection pressure can effectively increase the fuel–gas mixture formation and thermal efficiency of the diesel engine. In this study, the characteristics of the liquid length and combustion processes were studied using diffuse back-illumination and OH* chemiluminescence imaging. The results show that the time for the liquid length to reach a stable stage reduces with the increase in injection pressure and decrease in hole diameter. Although the injection pressure has a slight effect on the liquid length, the liquid length of the micro-hole injector under ultra-high injection pressure conditions is slightly reduced. Increasing the injection pressure and reducing the hole diameter can reduce soot generation per unit fuel mass. Compared with the use of the micro-hole diameter (D = 0.07 mm, Pinj = 100 MPa), increasing the injection pressure to 300 MPa (D = 0.133 mm, Pinj = 300 MPa) can suppress soot generation per unit fuel mass more effectively. The strong oxidation reaction was distributed both in the upstream and downstream areas of the flame only when the micro-hole injector was used under ultra-high injection pressure. When the liquid length is longer than the flame lift-off length, a large amount of soot is generated during combustion. Through the intersection of the liquid length and flame lift-off length trend line, it is estimated that the region of the liquid length is less than the lift-off length under different conditions. The determination of this region provides guidance and suggestions for the selection of the hole diameter of injectors and injection pressure for diesel engines.

Cavitation in nozzle orifices plays an important role on atomization and spray. In the industrial manufacturing, the processing method, especially the fluid grinding technology seriously affects the geometry of the orifice, such as the inlet rounding and roughness of inner orifice, which may result in the cavitation and turbulence of the internal flow. Therefore, the effect of grinding nozzle orifice on fuel spray was studied in this paper. Two mini-sac injectors with the same single orifice were used to compared. One was electrical discharge machining (EDM) nozzle orifice with Hydro-Erosive (HE) Grinding, and the other was EDM orifice without grinding. The spray experiments were conducted in the constant volume chamber. Firstly, the discharged coefficient (Cd) was calculated by controlling the injection duration and quantity. Secondly, non-evaporating characteristics were obtained through Mie scattering method. The spray tip penetration, spray area, spray cone angle and spray angle were defined and analyzed. Then, evaporating behaviors were characterized by laser absorption scattering (LAS) measurement as well as vapor mass and evaporation ratio. Finally, microscopic behaviors of near-nozzle spray and droplets were compared with the help of particle image analysis (PIA) technology. Results showed that owing to the cavitation without grinding process, Cd decreased sharply, leading to less spray area and angle. But the evaporation was promoted by the cavitation and turbulence. More vapor mass and evaporation ratio can be obtained without HE Grinding. Furthermore, droplet size becomes smaller without grinding due to the better atomization by turbulence. However, the mean velocity decreases sharply, and the coefficient of variation (COV) increases without grinding, which should be considered carefully in the injector design.

We created nano-micro hierarchical surface structures on Ag and measured their optical second harmonic generation (SHG) response. We found that the hierarchical surface structures can significantly modify the optical nonlinearity of the metal surfaces. The macroscopic symmetries of surface's shape influenced SHG. In addition, the observed SHG on Ag showed the contribution by the surface plasmon excitation. We also observed unique anisotropic enhancement of SHG in metal. We attribute our observations to both symmetry and surface plasmons on nano-micro hierarchical structures. Copyright © 2016 John Wiley & Sons, Ltd.

It is well known that the liquid adhesion by impingement in the direct-injection spark-ignition (DISI) engine hinders the engine combustion efficiency and increases the particular matter (PM) emissions. Although numerous investigations were done on it, it is still blur for the scholars owing to the complicated droplets-wall dynamics. Due to the dense liquid near the wall, it is difficult to observe the impinging droplets in this region, let alone analyzing it on the micro level. Therefore, the “multiple droplets producer” was applied to cut the spray for clear observation in this study. Tslicer was finally determined at 40 μm to make the multiple droplets impacting on the wall at the near-wall region under various injection pressure from 10 to 30 MPa during the quasi-steady state. Four different locations of (15, 15), (17, 15), (20, 15), (22, 15) were selected along the jet development after impingement. Particle image analysis (PIA) technology was applied to capture the micro behaviors. The diameter and velocity of droplets were calculated and analyzed as well as the Weber number. Results show that droplet behaviors near the wall can be recorded at Tslicer = 40 μm during the injection. Droplet size becomes larger with spray propagation at the near-wall region. Observations demonstrate that the coalescence phenomenon of the secondary droplets as well as the splashing crown structures occurrence leads to the larger droplet and lower velocity. Moreover, non-dimensional parameter We was used to further prove the splashing transition occurring from (17, 15) to (20, 15). Additionally, the experimental results can provide strong evidence and verification basis for computational fluid dynamics (CFD) simulations.

The objective of this study is to obtain an enhanced understanding of the effect of diesel spray/flame impingement on transient heat flux to the wall. By using a constant volume vessel under engine-like condition, surface heat flux of the wall at spray/flame impingement was measured with three thin film thermocouple heat flux sensors. Fuel was injected using a single-hole injector with a 0.133 mm diameter nozzle. In order to investigate the relation between diesel flame and wall heat loss, two color-method was applied to observe flame temperature distribution. 21 % and 16 % as the various oxygen concentration were investigated at each injection pressure of pressure 80, 120, and 180 MPa. The results showed that the lower oxygen concentration was generated heat loss regardless of injection pressures. The lower flame temperature and flame contact area and period were influence factor on heat loss on the wall. Furthermore, the relation between Nusselt number (Nu) and Reynolds number (Re) were also investigated to understand the heat transfer phenomena in diesel engines.

A comparison of diesel spray for injectors with single-hole (SH) and multi-hole (MH) nozzles has been conducted under same rail pressure and similar injection rate (30 MPa for SH and 100 MPa for MH) conditions. The result showed that the spray of SH injector has a longer penetration under same rail pressure condition caused by the faster build-up process of sac pressure. The spray of MH injector has a larger spray angle resulted from the complicated nozzle flow. These further affect the evaporation rate and mixture formation process. Regarding the same rail pressure condition, the spray of SH injector shows a fast evaporation rate, as well as the MH injector, although the spray angle of SH injector is quite small. For the entire mixture formation process, more spray vapor of SH is distributed in the thin area. For similar injection rate condition, the effect of different spray tip penetration can be eliminated while the advantage of the large spray angle of MH injector becomes apparent. The evaporation rate and mixture formation process of the SH injector are much worse than those of the MH injector. The complex nozzle internal flow of MH injector is responsible., This work was supported by the Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “Innovative combustion technology” (funding agency: JST).

Much attention has recently been given to high-efficiency cooling of pistons in internal combustion engines by cooling channels because of improved thermal efficiency. Cooling a piston efficiently requires a grasp of the gas-liquid multiphase flow state. However, because the magnitude and direction of the inertial force applied to the piston change depending on the crank angle, the flow field in the cooling channel that forms a complex gas-liquid multiphase flow remains a problem. Therefore, we developed a rig test apparatus simulating the reciprocating motion of a piston and visualized internal flows in a clear acrylic channel using a high-speed camera. This paper examines the effects of the Reynolds number of the oil jet and oscillation frequency of the reciprocating motion on flow characteristics in a right circular cylindrical channel. The Reynolds number and oscillation frequency were tested in the ranges 1000 to 2500 and 0 to 8.33 Hz, respectively. We found that the oil flow pattern in the channel forms the complex air-oil multiphase flow via air entrainment caused by the collision between the oil jet and the channel oil at the inlet. The gas phase area ratio in the channel increases with increasing Reynolds number, but its fluctuation is dominated by oscillation frequency. The fluctuation of the gas phase center of gravity becomes larger because of increases in inertial force with increases in oscillation frequency. The average bubble diameter in the channel decreases with increasing Reynolds number and oscillation frequency. We found that bubbles of small diameter are generated because the interfacial fluctuation of the oil jet increases as the jet goes downstream.

We investigated the optical third harmonic generation (THG) signal from nanostructure-covered microcubes on Ni. We found that the hierarchical structures greatly change the third-order optical nonlinearity of the metallic surface. While the symmetry and lightning rod (LR) effects on microstructures did not significantly influence the THG, the localized surface plasmon (LSP) effect on the nanostructures enhanced it. By removing the nanostructures on the hierarchical structures, THG intensity could be strongly suppressed. In the present paper, we also discuss the mechanism that enhances THG in nano/micro structures.

A pulsatile turbulent flow within an S-shaped double bend pipe is experimentally and numerically studied to characterize the flow field in conditions resembling an automotive engine environment. Particle image velocimetry (PIV) measurements were carried out to measure streamwise and secondary flow velocities. The flows are accelerated around the inner side walls of both bends. The secondary flow, after passing through the second bend, is directed toward the inner side in the core of the cross section, and, as a result, Lyne-type vortices, which are not consistent with the second bend curvature, are formed. A numerical simulation is performed under the same condition as the experiments with computational fluid dynamics software. The numerical simulation gives qualitative results in comparison with the experimental data though there is some deviation, and shows the cause of the Lyne-type vortex formation in the second bend. After passing through the first bend, the high-speed region appearing around the inner side shifts in accordance with the Dean-type secondary flow formed in the first bend, and thus the non-uniform flow enters the second bend. In the second bend, the low-velocity region in which the centrifugal force is not strong enough to direct the flow toward the outer side, appears in the core of the cross section. Details of the Lyne-type vortex formation are discussed by considering the driving forces of the secondary flow.

Shadow deposition fabricated Pd nanowires with well-oriented crystalline axes on MgO(210) faceted templates, and high-resolution transmission electron microscopy was used to examine the growth of the Pd nanowires in the [001] direction. The plane-view transmission electron microscopy images show long moire fringes in the [001] directions with some imperfections, while the diffraction patterns contain Pd spots. The [001] and [010] directions of the Pd lattices are in the same directions as those of MgO lattices, but their lattice constants differ by 7.6%. The high crystallinity of Pd nanowires likely originates from the low-density nuclei growth on the (100) facet on the MgO(210) face. Copyright © 2014 John Wiley & Sons, Ltd.

An ultrathin Terahertz (THz) quarter wave plate with high transmittance by flexible metamaterial is proposed in this paper. The device employs double layers of split ring resonator (SRR) with a polymer as the substrate. Due to the anisotropy of the SRR, it obtains a quarter wave plate with the transmittance of 0.72 and the ellipticity of 0.9994 at 0.854 THz from simulation. The device has a thickness in sub-wavelength of 50 μm.

Metamaterial device with double layers of split ring resonators (SRRs) on flexible substrate is proposed for building a new terahertz (THz)-wave near-field imaging system with real-time performance. The SRRs work as an array of probes that reserve the object near-field information and transfer it to the detection system, which is based on the frequency up-conversion with nonlinear crystal DAST (4-dimethylamino-N-methyl-4-stilbazolium tosylate). A flexible polymer is used for the substrate of the metamaterial device, which finally covers the DAST crystal for the THz wave imaging experiment.

Aggregation behavior of the organic-soluble semi-aromatic polyimides, whose degrees of imidization range from 69 to 96%, obtained using 4,4′-oxydianiline, 4,4′-diamino-3,3′dihydroxybiphenyl, and bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) in N-methylpyrrolidone (NMP), NMP/cyclohexanone, and NMP/γ-butyrolactone (BCDA-based polyimides) were studied by static light scattering (SLS) and dynamic light scattering (DLS). The DLS analyses for the multirelaxation modes demonstrated the specific character unlike flexible polymers that the single BCDA-based polyimide chains first associate with each other to form small clusters in the dilute region, and then expand to large aggregates by the entanglements between the small clusters with an increasing concentration into the semi-dilute region. Given the semi-aromatic structure of BCDA-based polyimides weakening the charge transfer (CT) interaction between the diamine and the dianhydride unit, it is concluded that the unique aggregation behavior of BCDA-based polyimides is dominated by the balance between the driving force for the “organic solubility” given by both the increase in bulkiness and the decrease in the CT interaction, and that for the “organic insolubility” derived from both the hydrogen-bonded interaction of the phenolic hydroxyl groups and the π–π interaction of the phenyl rings. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

Aggregation behavior including dilute solution property and surface-activity of the amphiphilic random copolymer composed of 2-(acrylamido)-2-methylpropanesulfonic acid and tris(trimethylsiloxy)silylpropylmethacrylate (AMPS/TRIS copolymer) in aqueous solution were studied by static light scattering (SLS), dynamic light scattering (DLS), surface tension measurement, and transmission electron microscopy (TEM). The surface tension measurement made it clear that AMPS/TRIS copolymer exhibited weaker surface-activity than a typical low-molecular weight surfactant sodium dodecyl sulfate in water, that is, there were no plateau of surface tension γ versus concentration and no critical micelle concentration (CMC) in the whole concentration studied. SLS and DLS analyses, and TEM revealed that AMPS/TRIS copolymer self-associated into imperfect core-shell micelles having hydrophobic TRIS core surrounded by hydrophilic AMPS shell in water. AMPS shell was considered as a hard shell due to the stiffness of AMPS chain in water. TRIS chain could not densely aggregate in water due to the large steric hindrance between bulky trimethylsiloxy groups despite its hydrophobic nature, thereby providing TRIS core with less-dense structure. The balance between the spreading force of stiff AMPS chain and the cohesion force of bulky TRIS chain provides the driving force for forming the unique micelle having less-dense TRIS core and hard AMPS shell. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011

We have measured optical second harmonic (SH) intensity from Pt nanowires with modified ellipsoidal cross sections on the MgO(110) faceted template. The observed SH intensity patterns as a function of the sample rotation angle φ around the surface normal were characterized by the effective nonlinear susceptibility arising from Cs symmetry of the Pt nanowires. The effective nonlinear susceptibility element χ222 was observed dominantly with the suffix 2 representing the [11 ― 0] direction of the MgO substrate. Other nonlinear susceptibility elements were also detected and their origins are discussed.

To investigated heat transfer phenomena inside the combustion chamber wall in diesel engines, we investigated the effects of spray/flame impingement on transient heat flux to the wall. By using a constant volume vessel under engine-like condition, surface heat flux of the wall at spray/flame impingement was measured with three thin film thermocouple heat flux sensors. Fuel was injected using a single-hole injector with a 0.133 mm diameter nozzle. Under these conditions, spray evaporates, then burns near the wall. In order to investigate the relation between diesel flame and wall heat loss, two colour-method was applied to observe local flame temperature distribution. The effect of oxygen concentration on the heat transfer was investigated parametrically. The results showed that the ratio of oxygen concentration influenced the combustion behaviour, which has significant effect on flame temperature and flame contact area that gave rise to further heat loss on the wall.

We have measured azimuthal angle dependence of the optical second-harmonic (SH) intensity from Pt nanowire arrays on the faceted MgO(110) substrates. The cross-sectional shapes of the fabricated Pt nanowires were also observed by transmission electron microscopy. The observed SH intensity patterns as a function of the sample rotation angle around the surface normal were characterized by the effective nonlinear susceptibility arising from the Cs symmetry of the Pt nanowire arrays. The correlation of the cross-sectional shapes of the wires and their nonlinear susceptibility is discussed. Copyright © 2010 John Wiley & Sons, Ltd.

Solution property of poly(γ-benzyl-L-glutamate)-b-polyisoprene-b)-poly(γ-benzyl-L-giutamate) (GIG copolymer) was studied by using dynamic light scattering and static light scattering for N,N-dimethylformamide (DMF) solution and DMF/toluene mixed solutions. GIG copolymer proved to aggregate in DMF and under DMF-rich condition, that is, high-polar region. The aggregate decreased in size, and completely disappeared under toluene-rich condition, that is, low-polar region. The correlation between solubility parameter and aggregate size of GIG copolymer in the DMF/toluene solution systems quantitatively demonstrated how strongly polarity caused by hydrogen bond made an impact on the aggregation behavior. Because the main driving force to the aggregation under DMF-rich condition originates with polyisoprene (PIP) blocks, the aggregate in DMF is considered to be a core-shell micelle consisting of flexible PIP core surrounded by rigid poly(γ-benzyl-L-glutamate) (PBLG) shell. The values of dimensionless parameter p, defined as the ratio of radius of gyration 〈S 2 〉 1/2 to hydrodynamic radius R H , revealed that a single chain of GIG copolymer had the form of rigid rod with flexibility, that is, once-broken rod, caused by the incorporation of a flexible PIP chain between two rigid PBLG rods in the DMF/toluene solution system.

Introduction We previously reported that a combination of factors VIIa (FVIIa) and X (FX) might represent an effective and attractive alternative to recombinant factor VIIa (rFVIIa) and plasma-derived activated prothrombin complex concentrate (APCC) for controlling bleeding in hemophiliacs with inhibitors. The present study describes the standardization and preparation of a virus-inactivated and nano-filtrated plasma-derived FVIIa/FX concentrate. We hypothesized that the hemostatic capacity was equivalent to or better than current bypassing agents as evaluated by measurements of waveform APTT clotting and thrombin generation. Results Kinetic analyses showed that a "normal" FX concentration of approximately 140 nM in plasma did not induce maximum catalytic efficacy of FVIIa and that an increase in the concentration of FX in hemophilic plasma enhanced the thrombin generation potential of FVIIa. Thus, the FVIIa/FX mixture was prepared by assembling plasma-derived FVIIa and FX at a weight ratio of 1:10. The FVIIa/FX mixture proved superior to rFVIIa with regards to shortening the APTT and accelerating the thrombin generation in hemophilic plasma. The FVIIa/FX mixture promoted the generation of thrombin more than did rFVIIa. Conclusions Increasing the FX concentration in hemophilic plasma gives a higher clotting potential of FVIIa. A FVIIa/FX concentrate may serve as a new alternative bypassing agent.

Solution property of hydrogenated polystyrene-b-poly(ethylene/butylene)-b-polystyrene triblock copolymer (SEBS copolymer) was studied by using static light scattering and dynamic light scattering for cyclohexane and N-methylpyr-rolidone (NMP) solutions. From the values of dimensionless parameters p, defined as the ratio of radius of gyration 〈S 2 〉 1/2 to hydrodynamic radius R H , and solubility parameters, SEBS copolymer proved to exist as single chain close to random coil in nonpolar cyclohexane, whereas aggregate into the core-shell micelle consisting of poly(ethylene/butylene) (PEB) core surrounded by PS shell in polar NMP. The core-shell micelle formed in NMP is composed of 65 polymer chains, having three times larger average chain density (d = 0.12 g cm ―3 ) than a single polymer chain (d = 0.04 g cm 3 ) in cyclohexane. The comparison with the aggregation behaviors in other solvents demonstrated that the aggregate compactness of the copolymer depended largely on solvent polarity, resulting in formation of the highly dense PEB core (R c = 4.5 nm) and the thick PS shell (ΔR = 22.9 nm) in high-polar NMP.

Cyclic saturated copolymers were prepared from 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.12,5.17,10]dodec-3-ene (MMT) with polar ester group and dicyclopentadiene (DCP) without polar group. This procedure consisted of ring-opening metathesis polymerization (ROMP) followed by hydrogenation. Monomer reactivity of DCP was higher than that of MMT; the monomer reactivity ratio rDCP/rMMT varied from 2.135 to 1.159 in a temperature range from 80 to 130 °C. These kinetic results indicated that the copolymer had distribution of DCP composition in a macromolecule chain, which could provide the interesting aggregation behavior. The aggregation behaviors of the hydrogenated copolymer and the homopolymer in various solvents were also examined using dynamic light scattering (DLS) and static light scattering (SLS). DLS analysis indicated that the fast mode in each polymer is attributed to the diffusive motion of each single polymer chain, while the slow mode in the copolymer is caused by aggregated polymer. The aggregation degree of the copolymer decreased with increasing hydrophobicity of solvent, decreasing polymer concentration, decreasing molecular size of solvent and increasing temperature. Based on these findings, the mechanism of aggregation behavior was clarified that the DCP-rich unit in a macromolecule might be acting as core to give the aggregation in poor solvent.

The present study discusses an acceleration of a swimming killifish-like small fish by fluid force, using three-dimensional simulations with CIP method in combination with an immersed boundary method. Simulation results have indicated that time variation of a small fish speed in small Reynolds number can be estimated as a free fall model of a sphere, that is, the fluid force can be separated into positive part (thrust) and negative part (viscous drag). Thrust is almost independent of Reynolds number, but a coefficient of viscous drag is a decreasing function of Reynolds number when a swimming motion of a fish with a shape is determined.

We propose a multi-dimensional scheme to solve the shallow water equations by using the CIP(Constrained Interpolation Profile/Cubic Interpolated Pseudoparticle) method which has the accuracy by one-order of magnitude better than the cubic Lagrange. This third-order accuracy is kept even in non-uniform grid, while the cubic Lagrange becomes the first order. The semi-Lagrangian approach to the characteristic equations has been used for solving gravity waves because it can make time step be much longer than the Courant-Friedrichs-Lewy (CFL) condition. Even in two dimensions, the method can give a symmetrical wave propagation under the large CFL condition.

Laser-supported propulsion of a micro-airplane with a water-covered ablator is demonstrated. The repetitive use of an overlay structure is experimentally demonstrated with a specially designed water supply. Various transparent overlays are investigated by the CIP-based hydrodynamic code and by experiments using a pendulum and using a semi-conductor load cell. A momentum-coupling efficiency of ∼104 N s/MJ is achieved by water–exotic-target experiments, in agreement with the simulation code, which predicts a maximum efficiency of ∼105 N s/MJ. The concept of laser-supported propulsion can also be used for driving a Mach 5 airplane in the stratosphere, a micro-ship inside the human body, and a robot in a nuclear power reactor accident, during which large numbers of neutrons make electronic devices useless.

We present a review of the CIP method, which is a kind of semi-Lagrangian scheme and has been extended to treat incompressible flow in the framework of compressible fluid. Since it uses primitive Euler representation, it is suitable for multi-phase analysis. The recent version of this method guarantees the exact mass conservation even in the framework of semi-Lagrangian scheme. Comprehensive review is given for the strategy of the CIP method that has a compact support and subcell resolution including front capturing algorithm with functional transformation.

Laser-supported propulsion of a micro-airplane with a water-covered ablator is demonstrated. The repetitive use of an overlay structure is experimentally demonstrated with a specially designed water supply. Various transparent overlays are investigated by the CIP-based hydrodynamic code and by experiments using a pendulum and using a semi-conductor load cell. A momentum-coupling efficiency of ∼104 N s/MJ is achieved by water–exotic-target experiments, in agreement with the simulation code, which predicts a maximum efficiency of ∼105 N s/MJ. The concept of laser-supported propulsion can also be used for driving a Mach 5 airplane in the stratosphere, a micro-ship inside the human body, and a robot in a nuclear power reactor accident, during which large numbers of neutrons make electronic devices useless.

This study demonstrates the presence of calmodulin in the vestibular end-organs of the gerbil by use of immunocytochemistry. Using fluorescence microscopy, calmodulin was localized to the cytoplasm, cuticular plate, and stereocilia of both type I and type II hair cells in the sensory epithelia of the utricle and cristae ampullaris; no label was found in the supporting cells, the dark cells, or the nerve fibers. There was no immunoreactive distinction between the labeling of type I and type II hair cells in the striolar or extrastriolar regions. Thus, immunocytochemical labeling for calmodulin provides a good marker for hair cells in gerbil vestibular epithelium. The presence of calmodulin in the stereocilia was confirmed by immunoelectron microscopy using secondary antibodies coupled to colloidal gold.

We investigated the ability of polyethylene glycol 4000 to accelerate thrombin generation in a mixture of prothrombin and factor X at concentrations of 1–30%. In the presence of 5 mM of CaCl 2 , polyethylene glycol 4000 promoted prothrombin activation at concentrations above 1%. The peak of activation was seen at levels of 14 and 20% of polyethylene glycol 4000. The effect of the polyethylene glycol was remarkably dependent on its molecular weight; molecular weights greater than 2000 were required for accelerating thrombin generation. Under optimal conditions, polyethylene glycol 4000, in the presence of CaCl 2 , promoted conversion of all of the prothrombin into thrombin and its derivatives. We conclude that polyethylene glycol 4000, at concentrations ranging from 14 to 20%, effectively accelerates thrombin generation in the presence of 5 mM of CaCl 2 . This new method for preparing thrombin is based on the use of polyethylene glycol 4000 and CaCl 2 and is applicable to the manufacture of thrombin.

A rare case of retrobulbar optic neuropathy caused by an isolated mucocele in an Onodi cell is presented. A 63-year-old man suffering from left recurrent optic neuropathy had shown improved visual acuity with steroid treatment at the age of 48 and 56 years. Impaired visual acuity and blurred vision in the left eye appeared again, and a marked inferior decrease in the left visual field was noted. Although axial computed tomography (CT) showed no abnormal findings, magnetic resonance imaging (MRI) revealed a small squamous-shaped lesion (17 × 17 × 7.3 mm) in the left posterior ethmoidal air cell (Onodi cell) hanging over the left optic nerve. Endoscopic sinus surgery was performed. The optic canal was extruding into the Onodi cell cavity, and the superior bony wall of the canal was eroded by the mucocele. The isolated mucocele in the Onodi cell seemed to be compressing the optic nerve downward and causing retrobulbar optic neuropathy. An Onodi cell lesion, even if it was isolated and small, would cause optic neuropathy. MRI and coronal CT scanning should be performed for the diagnosis and preoperative planning in a case of retrobulbar optic neuropathy.