Influence of Atmospheric Scattering on the Accuracy of Laser Altimetry of the GF-7 Satellite and Corrections

Satellite laser altimetry can obtain sub-meter or even centimeter-scale surface elevation data over large areas, but it is inevitably affected by scattering caused by clouds, aerosols, and other atmospheric particles. This laser ranging error caused by scattering cannot be ignored. In this study, we systematically combined existing atmospheric scattering identification technology used in satellite laser altimetry and observed that the traditional algorithm cannot effectively estimate the laser multiple scattering of the GaoFen-7 (GF-7) satellite. To solve this problem, we used data from the GF-7 satellite to analyze the importance of atmospheric scattering and propose an identification scheme for atmospheric scattering data over land and water areas. We also used a look-up table and a multi-layer perceptron (MLP) model to identify and correct atmospheric scattering, for which the availability of land and water data reached 16.67% and 26.09%, respectively. After correction using the MLP model, the availability of land and water data increased to 21% and 30%, respectively. These corrections mitigated the low identification accuracy due to atmospheric scattering, which is significant for facilitating satellite laser altimetry data processing.

Thermo-Hydraulic Characteristics of Micro-Scale Surface Roughness Topology of Additively Manufactured Surface Model: Modal Decomposition Perspective

As a consequence of rapid development of additive manufacturing (3D printing) methods, the academic/industrial demand has been continuously increasing. One field of application is the manufacturing of heat exchanging devices using this promising method. In this regard, understanding the underlying mechanisms from a thermo-hydraulic viewpoint becomes important. Therefore, in this study, scale-resolving large eddy simulation (LES) is applied to reveal the flow details in combination with a model of roughness topology occurring in additive manufacturing. To process the transient LES results, proper orthogonal decomposition (POD) is used to extract the coherent flow structures, and the extended POD is used to rank the flow modes based on thermal importance. The main aim of the present work is to go beyond the conventionally applied methodologies used for the evaluation of surface roughness, i.e., averaged numerical study or experimental overall performance evaluation of the flow/thermal response of additively manufactured surfaces in heat exchangers. This is necessary to reveal the underlying flow mechanisms hidden in the conventional studies. In this study, the behavior of the flow over the micro-scale surface roughness model and its effects on heat transfer are studied by assuming cone-shaped roughness elements with regular placement as the dominant surface roughness structures. The major discussions reveal the footprint of flow mechanisms on the heat transfer coefficient spatial modes on the rough surface. Moreover, comparative study on the flow/thermal behavior at different levels of roughness heights shows the key role of the height-to-base-diameter ratio of the roughness elements in thermal performance.

Cell-surface tethered promiscuous biotinylators enable small-scale surface proteomics of human exosomes

Characterization of cell surface proteome differences between cancer and healthy cells is a valuable approach for the identification of novel diagnostic and therapeutic targets. However, selective sampling of surface proteins for proteomics requires large samples (>10e7 cells) and long labeling times. These limitations preclude analysis of material-limited biological samples or the capture of rapid surface proteomic changes. Here, we present two labeling approaches to tether exogenous peroxidases (APEX2 and HRP) directly to cells, enabling rapid, small-scale cell surface biotinylation without the need to engineer cells. We used a novel lipidated DNA-tethered APEX2 (DNA-APEX2), which upon addition to cells promoted cell agnostic membrane-proximal labeling. Alternatively, we employed horseradish peroxidase (HRP) fused to the glycan binding domain of wheat germ agglutinin (WGA-HRP). This approach yielded a rapid and commercially inexpensive means to directly label cells containing common N-Acetylglucosamine (GlcNAc) and sialic acid glycans on their surface. The facile WGA-HRP method permitted high surface coverage of cellular samples and enabled the first comparative surface proteome characterization of cells and cell-derived exosomes, leading to the robust quantification of 1,020 cell and exosome surface proteins. We identified a newly-recognized subset of exosome-enriched markers, as well as proteins that are uniquely upregulated on Myc oncogene-transformed prostate cancer exosomes. These two cell-tethered enzyme surface biotinylation approaches are highly advantageous for rapidly and directly labeling surface proteins across a range of material-limited sample types.

Improving bond strength and mass transport properties of spacer-concrete interface with textured spacers

Spacers are important devices used in all concrete structures to support reinforcing steel and achieve the required cover. However, spacers induce a weak, porous and microcracked interface that facilitates ingress of aggressive agents. This paper aims to address the problem by developing a method to produce cementitious spacers with a range of small-scale surface textures including grooves, squares, rectangles, hemispheres and pyramids. The textured spacers were cast in Portland cement mortar or concrete, cured up to 28 days, and tested for tensile bond strength, accessible porosity and mass transport properties. The properties were correlated to surface characteristics to establish the effects of texture on spacer-concrete interface. Results show that textured spacers promote mechanical interlocking with concrete, thereby increasing bond strength, resistance against microcracking and pressure-induced flow. The use of certain textures can compensate for the negative effects of spacers, achieving similar bond strength and permeability to monolithic concrete without the interface.