Noninvasive 3D vital imaging and characterization of notochordal cells of the intervertebral disc by femtosecond near-infrared two-photon laser scanning microscopy and spatial-volume rendering

The central region of the intervertebral disc (IVD) in infant humans is made and maintained by notochordal cells (NCs). These cells disappear during maturation to be replaced by mature chondrocyte-like cells. NCs are completely different morphologically from the mature chondrocyte-like IVD cells and have complex and essential functions but little is known about them. Recently, two-photon laser scanning microscopy (TPLSM) using near-infrared (NIR) femtosecond pulsed lasers has emerged as a promising noninvasive optical technique for observing unfixed living 3D biological specimens in situ and in vitro. Several lines of evidence suggest that compared with conventional laser scanning confocal microscopy (LSCM), femtosecond NIR laser-based TPLSM has any number of advantages including 3D resolution without a spatial filter (confocal pinhole), minimal photobleaching, and photodamage above and below the focal plane, and importantly, greater depth penetration. We have thus taken advantage of these unique features of femtosecond laser-based TPLSM for vital 3D imaging in conjunction with advanced spatial-volume rendering modalities to compare morphologies of NCs/clusters from pig caudal discs with chondrocyte-like IVD cells from bovine caudal discs, both in ex vivo tissue and when isolated and grown in vitro within 3D alginate scaffolds. Our results provide evidence that (a) ex vivo notochordal tissue consists of areas with NC clusters, and those dominated by tubular structures of low cell density (b) within 3D in vitro scaffolds the morphology of NC is heterogeneous and the cells contain distinct cytoplasmic vacuole-like structures occasionally including acidic subinclusions (c) a quantitative determination based on 3D spatial and volumetric-rendering reveals an average NC diameter of 22.05 microm (range 11.96-46.63 microm) and NC volume of 9701 microm(3) (2041-36427 microm(3)) whereas chondrocyte-like cells have a mean volume of 3279 microm(3) and diameter of 12.20 microm. Taken together, this study demonstrates that femtosecond TPLSM has unique advantages over other conventional histological and in particular LSCM for high resolution noninvasive vital characterization of notochordal and chondrocyte-like cells of IVD over extended depths beyond 300-500 microm.     

液体粘性软起动装置摩擦片传热机理研究

针对带式输送机液体粘性软起动装置摩擦片的结构特性，将粘性流体力学和摩擦学原理有机结合，分析起动过程中摩擦片与油膜间的导热过程，推导出摩擦功耗计算公式及冷却油对流换热微分方程，以保证液体粘性软起动装置中摩擦片不至于温度过高而损坏，设计出满足使用要求的液体粘性软起动装置。     

A study on the improvement of release application characteristics of pneumatic brakes for freight train

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.     

调节阀阀瓣型面在计算机中自动绘制的方法

介绍了利用计算机根据已知流量系数和给定阀座直径、行程、可调比及流量特性的条件下自动绘制柱塞式调节阀阀瓣型面的方法。     

Design and implementation of optical system for Placido-disc topography

Corneal topography provides powerful support in the diagnosis and treatment of corneal disease by displaying the corneal surface topography in data or image format. To realize the precise detection of corneal surface topography, an optical system for the corneal topography that is based on a Placido disc is designed, which includes a ring distribution on a Placido disc, an imaging system and a collimating illumination system. First, a mathematical model that is based on the corneal topography working principles is established with MATLAB to determine the distribution of white-and-black rings on the Placido disc, in which the ellipsoid facial rings-target of the Placido disc is utilized. Second, the imaging lens structure is designed and optimized by Zemax software. Last, the collimating illumination lens structure is designed by paraxial ray trace equations. The quality of the corneal topography, which is based on our designed optical system, is evaluated. The high-contrast image of uniformly distributed white-and-black rings is observed through the CCD camera. Our optical system for the corneal topography has high precision, with a measuring region of the cornea with a diameter of approximately 10 mm. Therefore, the creation of this optical system offers guidance for designing and improving the optical system of Placido-disc topography.     

Potential flow solutions for energy extracting actuator disc flows

The actuator disc is the oldest representation of a rotor, screw or propeller. Performance prediction is possible by applying momentum theory, giving integrated values for power and velocity. Computational fluid dynamics has provided much more flow details, but a full potential flow solution zooming in on these flow details was still absent. With the wake boundary discretized by vortex rings, flow states for energy extracting discs have been obtained for thrust coefficients up to 0.998. Boundary conditions are met with an accuracy of a few ‰. Results from momentum theory are confirmed. Most rotor design codes use momentum theory in annulus or differential form, assuming that the axial velocity v_x at the disc is uniform. However, the absolute velocity | v | is found to be uniform, and arguments for this are presented. The non‐uniformity of v_x is an inherent part of the flow solution caused by, in terms of momentum theory, the pressure acting at the annuli. This makes the annuli not independent from each other as assumed in current design codes. Although this was already known, it is now confirmed up to the highest thrust coefficients. Optimizing a rotor design should be carried out for the non‐uniform distribution of v_x. To enable this, an equation for the non‐uniformity as function of thrust and radial position is presented, being a surface‐fit to the calculated data. Qualitatively, the non‐uniform distribution does the same as the Prandtl–Glauert–Shen tip correction applied to a uniform distribution. Copyright © 2015 John Wiley & Sons, Ltd.     

卷烟机平准器对烟支空头率影响的探究

通过对比三槽型平准器和三深三浅型平准器在相同生产条件下的烟支空头剔除率和部分烟支物理指标值,探究了他们对烟支空头率的影响。结果表明,三深三浅型平准器在烟支空头率控制方面,比三槽型平准器更有优势,烟支空头率相差7.8%;在同样降低了烟支空头率的情况下,三深三浅型平准器比三槽型平准器具有更好的质量稳定性。     

Grey and black-box modelling based on neural networks and artificial immune systems applied to solid dissolution by rotating disc method

The dissolution rates of urea, sodium bicarbonate, and sodium carbonate in water and aqueous solutions were determined using the rotating disc technique. The experiments showed that the dissolution rate increases with increasing disc surface area, temperature, and rotating speed, while it decreases with the solute concentration increase in the dissolution medium. The comparison between experimental values for the dissolution rate and those calculated from Levich equation evidenced a satisfactory agreement in the case of the urea dissolution and poor compliance for the sodium bicarbonate and sodium carbonate dissolution. This poor results and the lack of a good model for making predictions in different situations determined the generation of empirical and semiempirical models (black and grey box approaches) which include neural networks developed with Clonal Selection algorithm (belonging to the Artificial Immune System class) and combination between neural network and phenomenological model. Satisfactory results were obtained with neural networks (black box models) and hybrid models (grey box models).     

Driver sensitivity to brake pulse duration and magnitude

Adaptive cruise control (ACC) requires that the driver intervene in situations that exceed the capability of ACC. A brake pulse might provide a particularly compatible means of alerting the driver to situations in which the acceleration authority of the ACC has been exceeded. This study examined the sensitivity of the driver to brake pulses of five different amplitudes (0.01–0.025 g) and five different durations (50–800 ms). Drivers were sensitive to accelerations as low as 0.015 g. Pulse duration interacted with pulse amplitude, such that moderate duration pulses were more detectable than long and short duration pulses at intermediate levels of pulse amplitude. A power function with an exponent of 1.0 accounted for 99% of the variance in drivers' sensitivity to pulse amplitude; however, a power function with an exponent of 0.23 accounted for only 70% of the variance in drivers' sensitivity to pulse duration. These results can help designers create ACC algorithms and develop brake pulse warnings.     

CO2‐induced crystal engineering of polylactide and the development of a polymeric nacreous microstructure

Nacre's biomineralization process and its self‐organizing brick‐and‐mortar crystalline microstructure have inspired many researchers to develop new materials derived from the natural world. In our study, we took a novel approach to two‐dimensional (2‐D) crystallization. That is, we applied the biomineralization self‐organizational principle that exists in natural materials to a biopolymer (polylactide). The CO₂‐induced crystallization of poly(d ‐lactide), with its unique diffusion‐controlled crystallization mechanism, tends to produce distinct 2‐D spherulitic structures. We found that these 2‐D spherulites were self‐organizing in nature, and that they created a stack of 2‐D spherulitic structures. These crystalline microstructures, with their intervening amorphous phase, were foamed in situ due to the CO₂‐induced crystallization self‐exclusion phenomenon. We compared the resultant crystalline structure with nacre's brick‐and‐mortar crystalline microstructure to confirm the biomimetic principle of self‐organization. To the best of our knowledge, this is the first time that a biopolymer has been crystallized in a 2‐D manner in a way that resembles nature's biomineralization process. The hierarchical crystalline microstructure is morphologically similar to that of nacre biomaterials. This novel crystallization technique is simple, absolutely non‐toxic and works swiftly to produce a brick‐and‐mortar crystalline microstructure with a high degree of order. © 2017 Society of Chemical Industry