envelope surface
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Author(s):  
Jing Wang ◽  
Jinglin Zhou ◽  
Xiaolu Chen

AbstractIt is found that the batch process is more difficultly monitored compared with the continuous process, due to its complex features, such as nonlinearity, non-stable operation, unequal production cycles, and most variables only measured at the end of batch. Traditional methods for batch process, such as multiway FDA (Chen 2004) and multi-model FDA (He et al. 2005), cannot solve these issues well. They require complete batch data only available at the end of a batch. Therefore, the complete batch trajectory must be estimated real time, or alternatively only the measured values at the current moment are used for online diagnosis. Moreover, the above approaches do not consider the problem of inconsistent production cycles.


2021 ◽  
Author(s):  
Dong Zhou ◽  
Hongduo Wu ◽  
Ziyue Guo ◽  
Qidi Zhou ◽  
Yuning Liang

Abstract In virtual maintenance, the most widely used accessibility evaluation method is to use virtual human reach envelope surface to judge and evaluate accessibility. However, this method can only give two kinds of evaluation results: reachable and unreachable. There is not enough data and theoretical support for the construction of envelope surface, and the precision and accuracy of evaluation need to be improved. In this paper, a parameterized accessibility evaluation method and a method of accessibility envelope surface construction are proposed. Firstly, to objectively describe the movement of human body, a 6-joint and 5-link D-H (Denavit-Hartenberg) link model is established from the waist to the fingertip of the human body, and the ranges of 10 degrees of freedom and angles related to accessibility are determined according to ergonomics. Then, comfort is introduced to refine the accessibility evaluation, and a multi-level accessibility evaluation system based on comfort is constructed according to RULA (the rapid upper limb assessment). In order to facilitate the application of this method in virtual environment, a method of accessibility envelope surface construction is proposed. Firstly, the reachable points are generated by Monte Carlo simulation based on the D-H model. Secondly, the accessibility envelope surface is composed of the outermost random reachable points. Finally, the comparison experiment with the reachable envelope provided by DELMIA in virtual environment shows that the proposed method is more accurate, meticulous and objective. Based on this method, an accessibility evaluation tool has been developed in CATIA and has been applied in some scientific research institutes.


2021 ◽  
Author(s):  
Marissa D. Acciani ◽  
Maria F. Lay Mendoza ◽  
Katherine E. Havranek ◽  
Avery M. Duncan ◽  
Hersha Iyer ◽  
...  

Ebola virus (EBOV) attaches to target cells using two categories of cell surface receptors, C-type lectins and phosphatidylserine (PS) receptors. PS receptors typically bind to apoptotic cell membrane PS and orchestrate the uptake and clearance of apoptotic debris. Many enveloped viruses also contain exposed PS and can therefore exploit these receptors for cell entry. Viral infection can induce PS externalization in host cells, resulting in increased outer PS levels on budding virions. Scramblase enzymes carry out cellular PS externalization, thus, we targeted these proteins in order to manipulate viral envelope PS levels. We investigated two scramblases previously identified to be involved in EBOV PS levels, transmembrane protein 16F and Xk-related protein 8 (XKR8), as possible mediators of cellular and viral envelope surface PS levels during the replication of recombinant vesicular stomatitis virus containing its native glycoprotein (rVSV/G) or the EBOV glycoprotein (rVSV/EBOV-GP). We found that rVSV/G and rVSV/EBOV-GP virions produced in XKR8 knockout cells contain decreased levels of PS on their surfaces, and the PS-deficient rVSV/EBOV-GP virions are 70% less efficient at infecting cells through PS receptors. We also observed reduced rVSV and EBOV virus-like particle (VLP) budding in ΔXKR8 cells. Deleting XKR8 in HAP1 cells reduced rVSV/G and rVSV/EBOV-GP budding by 60% and 65% respectively, and reduced Ebola VLP budding more than 60%. We further demonstrated that caspase cleavage of XKR8 is required to promote budding. This suggests that XKR8, in addition to mediating virion PS levels, may also be critical for enveloped virus budding at the plasma membrane. Importance Within the last decade, countries in western and central Africa have experienced the most widespread and deadly Ebola outbreaks since the virus was identified in 1976. While outbreaks are primarily attributed to zoonotic transfer events, new evidence is emerging that outbreaks may be caused by a combination of spillover events and viral latency or persistence in survivors. The possibility that Ebola can remain dormant then re-emerge in survivors highlights the critical need to prevent the virus from entering and establishing infection in human cells. Thus far, host-cell scramblases TMEM16F and XKR8 have been implicated in Ebola envelope surface phosphatidylserine (PS) and cell entry using PS receptors. We assessed the contributions of these proteins using CRISPR knockout cells and two EBOV models: rVSV/EBOV-GP and EBOV VLPs. We observed that XKR8 is required for optimal EBOV envelope PS levels and infectivity, and particle budding across all viral models.


2021 ◽  
Vol 8 (1) ◽  
pp. 147-156
Author(s):  
Xavier Tellier ◽  
Romane Boutillier ◽  
Cyril Douthe ◽  
Olivier Baverel

Abstract Curved envelope structural building envelopes have been quite popular in architecture in the past decades, and pose many challenges in their design, manufacturing and planning. In gridshells, a popular structural morphology for curved structure, designers will often strive to orient beams such that their top face is parallel to the envelope surface. However, this tends to induce geometrical torsion along the beam centerline, which complexifies significantly the manufacturing of the connection nodes or of the beams themselves. It is well known that such issue can be avoided by aligning beams with principal curvature directions of the envelope surface, thus yielding a quadrangular paneling. In this article, we study how other types of patterns (non-quadrangular) can be used to design torsion-free grid-shells. Based on asymptotic considerations, we derive a set of geometrical rules which, if fulfilled by a pattern, insure that a surface can be covered by this pattern with negligible torsion and limited deviation of beams from surface normals. A wide variety of patterns fulfill these rules, offering interesting possibilities for the design of curved architectural envelopes (Figure 1) is shown. As these rules are based on first order asymptotic analysis, we perform global validation on case studies. One main application is for structures in which face planarity is not necessary, for example ones cladded with ETFE cushions.


Author(s):  
Marissa D. Acciani ◽  
Maria F. Lay-Mendoza ◽  
Katherine E. Havranek ◽  
Avery M. Duncan ◽  
Hersha Iyer ◽  
...  

AbstractEbola virus (EBOV) interacts with cells using two categories of cell surface receptors, C-type lectins and phosphatidylserine (PS) receptors. PS receptors typically bind to apoptotic cell membrane PS and orchestrate the uptake and clearance of apoptotic bodies. Many viruses coated with PS-containing lipid envelopes, acquired during budding from host cells, can also exploit these receptors for internalization. PS is restricted to the inner leaflet of the plasma membrane in homeostatic cells, an orientation that would be unfavorable for PS receptor-mediated uptake if conserved on the viral envelope. Therefore, it is theorized that viral infection induces host cell PS externalization to the outer leaflet during replication. Cells have several membrane scramblase enzymes that enrich outer leaflet PS when activated. Here, we investigate two scramblases, TMEM16F and XKR8, as possible mediators of cellular and viral envelope surface PS levels during recombinant VSV/EBOV-GP replication and EBOV virus-like particle (VLP) production. We found that rVSV/EBOV-GP and EBOV VLPs produced in XKR8 knockout cells contain decreased levels of PS in their outer leaflets. ΔXKR8-made rVSV/EBOV-GP is 70% less efficient at infecting cells through apoptotic mimicry compared to viruses made in parental cells. Our data suggest that virion surface PS acquisition requires XKR8 activity, whereas TMEM16F activity is not essential. Unexpectedly, we observed defective rVSV/G, rVSV/EBOV-GP, and EBOV VLP budding in ΔXKR8 cells, suggesting that phospholipid scrambling via XKR8 enhances both Ebola infectivity and budding efficiency. Overexpression of XKR8 dramatically increased budding activity, suggesting outer leaflet PS is required for both particle production and increased infectivity.ImportanceThe Democratic Republic of the Congo experienced its deadliest Ebola outbreak from 2018 to 2020, with 3,444 confirmed cases and 2,264 deaths (as of March 12, 2020). Owing to the extensive damage that these outbreaks have caused in Africa, as well as its future epidemic potential, Ebola virus (EBOV) ranks among the top eight priority pathogens outlined by the WHO in 2018. A comprehensive understanding of Ebola entry pathways into target cells is critical for antiviral development and outbreak control. Thus far, host-cell scramblases TMEM16F and XKR8 have each been named as the sole mediator of Ebola envelope surface phosphatidylserine (PS). We assessed the contributions of these proteins using CRISPR knockout cells and two EBOV models: rVSV/EBOV-GP and EBOV VLPs. We observed that XKR8 is required for optimal EBOV envelope PS levels, PS receptor engagement, and particle budding across all viral models, whereas TMEM16F did not play a major role.


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