A portable device for studying the effects of fluid flow on degradation properties of biomaterials inside cell incubators.

A portable device was designed and constructed for studying the properties of biomaterials in physiologically relevant fluids under controllable flow conditions that closely simulate fluid flow inside the body. The device can fit entirely inside a cell incubator; and, thus, it can be used directly under standard cell culture conditions. An impedance-driven pump was built in the sterile flow loop to control the flow rates of fluids, which made the device small and portable for easy deployment in the incubator. To demonstrate the device functions, magnesium (Mg) as a representative biodegradable material was tested in the flow device for immersion degradation under flow versus static conditions, while the flow module was placed inside a standard cell incubator. The flow rate was controlled at 0.17 ± 0.06 ml/s for this study; and, the flow rate is adjustable through the controller module outside of incubators for simulating the flow rates in the ranges of blood flow in human artery (0.05 ∼0.43 ml/s) and vein (0.02 ∼0.08 ml/s). Degradation of Mg under flow versus static conditions was characterized by measuring the changes of sample mass and thickness, and Mg2+ ion concentrations in the immersion media. Surface chemistry and morphology of Mg after immersion under flow versus static conditions were compared. The portable impedance-driven flow device is easy to fit inside an incubator and much smaller than a peristaltic pump, providing a valuable solution for studying biomaterials and implants (e.g. vascular or ureteral stents) in body fluids under flow versus static conditions with or without cells

Inherent Safer Design for Chemical Process of 1,4-dioldiacetate-2-butene Oxidized by Ozone

PresentationOxidation reaction is the typical thermal runaway reaction. The reaction of 1,4-dioldiacetate-2- Butene oxidized by ozone was chosen to study the thermal hazards during the chemical process and the inherent safer designs (ISD) were proposed after analysis. The Qualitative Assessment for Inherently Safer Design (QAISD) was used to identify the risk during the chemical process. Meanwhile, the Reaction Calorimeter (RC1e) was used to analyze the thermal hazards of the chemical process. Two Inherent safer designs were proposed to increase the safe level of the process. ISD I is the improved reaction condition of reaction temperature at -5°C and ventilation rate of 200L•h-1, as well, ISDII is using a tubular reactor. The results indicate that the classification of the reaction hazard was lower with improvements of two ISDs, and the severity was reduced by 43%. Moreover, the inherent safety level of the reaction was increased by ISD I &IIof 63% and 43.4% respectively, which both have positive effects on inherent safety theories of "minimize", "substitute" and "moderate"

Analysis and Radiometric Calibration for Backscatter Intensity of Hyperspectral LiDAR Caused by Incident Angle Effect

Hyperspectral LiDAR (HSL) is a new remote sensing detection method with high spatial and spectral information detection ability. In the process of laser scanning, the laser echo intensity is affected by many factors. Therefore, it is necessary to calibrate the backscatter intensity data of HSL. Laser incidence angle is one of the important factors that affect the backscatter intensity of the target. This paper studied the radiometric calibration method of incidence angle effect for HSL. The reflectance of natural surfaces can be simulated as a combination of specular reflection and diffuse reflection. The linear combination of the Lambertian model and Beckmann model provides a comprehensive theory that can be applied to various surface conditions, from glossy to rough surfaces. Therefore, an adaptive threshold radiometric calibration method (Lambertian-Beckmann model) is proposed to solve the problem caused by the incident angle effect. The relationship between backscatter intensity and incident angle of HSL is studied by combining theory with experiments, and the model successfully quantifies the difference between diffuse and specular reflectance coefficients. Compared with the Lambertian model, the proposed model has higher calibration accuracy, and the average improvement rate to the samples in this study was 22.67%. Compared with the results before calibration with the incidence angle of less than 70 degrees, the average improvement rate of the Lambertian-Beckmann model was 62.26%. Moreover, we also found that the green leaves have an obvious specular reflection effect near 650-720 nm, which might be related to the inner microstructure of chlorophyll. The Lambertian-Beckmann model was more helpful to the calibration of leaves in the visible wavelength range. This is a meaningful and a breakthrough exploration for HSL.Peer reviewe

Internal Architectural Patterns of Bar Fingers Within Digitate Shallow-Water Delta: Insights from the Shallow Core, GPR and Delft3D Simulation Data of the Ganjiang Delta, China

Digitate shallow-water deltas are commonly found in modern lakes and bays, as well as within cratonic petroliferous basins. They develop one or multiple sinuous finger-like sands (i.e., bar fingers), including high-RSI (sinuosity ratio of distributary channel and bar finger ≥1) and low-RSI (RSI 10°) compared with those in the supplying river. This dip angle exhibits a negative relationship with downstream distance and a positive exponential relationship with lateral migration distance. Silty drapes become dense along the migration direction of the distributary channel. The levee develops multiple horizontal muddy accretion beds. The high-RSI bar finger develops a large number (>3) of accretion beds in mouth bars with high dip angles, and a large number of accretion beds in thick levees, compared with the low-RSI bar finger. The results of this paper provide insights into the prediction and development of cratonic digitate shallow-water delta reservoirs

Path Planning for Autonomous Vehicle Based on a Two-Layered Planning Model in Complex Environment

The autonomous vehicle consists of perception, decision-making, and control system. The study of path planning method has always been a core and difficult problem, especially in complex environment, due to the effect of dynamic environment, the safety, smoothness, and real-time requirement, and the nonholonomic constraints of vehicle. To address the problem of travelling in complex environments which consists of lots of obstacles, a two-layered path planning model is presented in this paper. This method includes a high-level model that produces a rough path and a low-level model that provides precise navigation. In the high-level model, the improved Bidirectional Rapidly-exploring Random Tree (Bi-RRT) based on the steering constraint is used to generate an obstacle-free path while satisfying the nonholonomic constraints of vehicle. In low-level model, a Vector Field Histogram- (VFH-) guided polynomial planning algorithm in Frenet coordinates is introduced. Based on the result of VFH, the aim point chosen from improved Bi-RRT path is moved to the most suitable location on the basis of evaluation function. By applying quintic polynomial in Frenet coordinates, a real-time local path that is safe and smooth is generated based on the improved Bi-RRT path. To verify the effectiveness of the proposed planning model, the real autonomous vehicle has been placed in several driving scenarios with different amounts of obstacles. The two-layered real-time planning model produces flexible, smooth, and safe paths that enable the vehicle to travel in complex environment. Document type: Articl