Search

In various biological systems, analyzing how cell behaviors are coordinated over time would enable a deeper understanding of tissue-scale response to physiologic or superphysiologic stimuli. Such data is necessary for establishing both normal tissue function and the sequence of events after injury that lead to chronic disease. However, collecting and analyzing these large datasets presents a challenge—such systems are time-consuming to process, and the overwhelming scale of data makes it difficult to parse overall behaviors. This problem calls for an analysis technique that can quickly provide an overview of the groups present in the entire system and also produce meaningful categorization of cell behaviors. Here, we demonstrate the application of an unsupervised method—the Variational Autoencoder (VAE)—to learn the features of cells in cartilage tissue after impact-induced injury and identify meaningful clusters of chondrocyte behavior. This technique quickly generated new insights into the spatial distribution of specific cell behavior phenotypes and connected specific peracute calcium signaling timeseries with long term cellular outcomes, demonstrating the value of the VAE technique. [ABSTRACT FROM AUTHOR]

Cellular response to stimulation governs tissue scale processes ranging from growth and development to maintaining tissue health and initiating disease. To determine how cells coordinate their response to such stimuli, it is necessary to simultaneously track and measure the spatiotemporal distribution of their behaviors throughout the tissue. Here, we report on a novel SpatioTemporal Response Analysis IN Situ (STRAINS) tool that uses fluorescent micrographs, cell tracking, and machine learning to measure such behavioral distributions. STRAINS is broadly applicable to any tissue where fluorescence can be used to indicate changes in cell behavior. For illustration, we use STRAINS to simultaneously analyze the mechanotransduction response of 5000 chondrocytes—over 20 million data points—in cartilage during the 50 ms to 4 hours after the tissue was subjected to local mechanical injury, known to initiate osteoarthritis. We find that chondrocytes exhibit a range of mechanobiological responses indicating activation of distinct biochemical pathways with clear spatial patterns related to the induced local strains during impact. These results illustrate the power of this approach. [ABSTRACT FROM AUTHOR]

The double-row tapered roller bearing (TRB) widely used to support the main shaft in a modern gearless wind turbine is one of the main components and its faults can lead to the malfunctions and downtime of wind turbines. Over the past decades, some numerical approaches have been proposed for calculating the contact force and pressure distribution of double-row TRBs. Nevertheless, most of the existing studies did not take the angular misalignment between inner and outer rings and the frictional force between the rollers and raceways into account. This paper presents a comprehensive quasi-static model to investigate the internal load and contact pressure distribution in a double-row TRB by considering the angular misalignment, the combined external loads and frictional force. It is found that a small misalignment angle between inner and outer rings can result in a significant change in the magnitude and distribution of the contact force and pressure. The double-row TRB with crowned roller profile exhibits a substantial improvement in contact pressure distribution by eliminating the occurrence of pressure concentration. Moreover, the peak contact pressure can be significantly reduced on the roller with the crowned profile, even if in the case of misaligned bearing. Comparisons of the simulated contact loads and pressure distributions demonstrate the necessity of considering angular misalignment and frictional force in the modelling of large size and heavily loaded double-row TRB. • A comprehensive quasi-static model is proposed for calculating internal load and contact pressure distributions in tapered double-inner ring bearing. • The model considers the effects of friction force and angular misalignment on the contact pressure distribution. • The effects of angular misalignment, combined external loads and friction force are investigated. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to improve the tribological properties of hydrodynamic journal bearing via surface texture, as well as the wear and antifriction mechanisms of textured bearing were represented. It provides a design direction for solving the tribological problem of rotor-bearing system. Design/methodology/approach: In this paper, the variation of surface texture parameters (e.g. texture diameter, d; area density, sp; and depth, hp) were analyzed based on finite difference method. The optimal surface texture parameters were obtained by designing orthogonal experiments, and the relationship between friction and wear properties and microstructure was studied via combining electron probe microanalyzer, scanning electron microscope, X-ray diffractometer and friction and wear testing machine. Findings: Dimensionless film pressure P increased as the d increased, whereas P first increased and then decreased as the sp and hp increased, and the maximum P was got as sp = 15% and hp = 25 µm, respectively. The friction coefficient of textured surface with suitable parameters was effectively reduced and the textured surface with the best antifriction effect was 5#. Orthogonal experimental design analysis showed that the influence order of factors on friction coefficient was as follows: sp > sp × d > d > d × hp > hp > sp × hp and the friction coefficient first decreased and then increased as the sp, d and hp increased. In addition, the friction and wear mechanism of textured bearing were three body friction and abrasive wear as the matrix structure and hard phase were a single β phase and Mn5Si3, respectively. While the antifriction mechanism of textured surface was able to store abrasive particles and secondary hydrodynamic lubrication was formed. Originality/value: The sample with reasonable texture parameter design can effectively reduce friction and wear of hydrodynamic journal bearing without reducing the service life, which can provide a reference for improving the lubrication performance and mechanical efficiency of rotor-bearing system. [ABSTRACT FROM AUTHOR]

The importance of methane conversion, syngas selectivity, and oxidizer conversion for efficient syngas production by the partial oxidation of methane using a metal oxide redox cycle is quantified. The operating conditions which enable high conversion of methane to syngas over cerium oxide and conversion of carbon dioxide to carbon monoxide in the subsequent oxidation reaction are identified experimentally. The parametric study considers operating temperatures of 900 and 1000 °C and methane flow rates from 1 to 15 mL min −1 g −1 in a fixed bed of porous ceria particles. The reduced ceria is reoxidized in a flow of 10 mL min −1 g −1 CO 2 to produce CO. A trade-off of achieving high methane conversion is observed. For example, at 1000 °C, the cycle-averaged methane conversion increases from 13% for reduction in 15 mL min −1 g −1 to 60% in 1 mL min −1 g −1 . For the same change in methane flow rate, the cycle-averaged selectivities decrease from 78% to 39% (CO) and 77% to 40% (H 2 ) and the oxidizer conversion decreases from 93% to 48%. The maximum projected solar-to-fuel thermal efficiency is 27% for cycling at 1000 °C with reduction in 5 mL min −1 g −1 methane. [ABSTRACT FROM AUTHOR]

• Pd-doping improves surface oxygen vacancy concentration in laco 0.2 Fe 0.8 O 3-δ anodes. • Adsorption abilities of CH 4 are promoted by oxygen vacancies on anode surfaces. • Initial oxidation of CH 4 molecule is essentially the oxidation of h atoms in CH 4. • Catalytic activity for CH 4 oxidation is related to Bader charges of surface metals. Initial oxidation of methane (CH 4) is essential for subsequent oxidation reactions on anode surfaces of solid oxide fuel cells (SOFCs). Here first principle method was employed to investigate the initial oxidation mechanism of CH 4 on Pd doped LaCo 0.2 Fe 0.8 O 3-δ (LCF) anode. Results show that Pd-doping decreases formation energies of surface oxygen vacancy. The adsorption ability of CH 4 molecules is also improved on perfect LCF surface by Pd-doping. Dissociation barriers of CH 4 on LCF surfaces are greatly decreased with min value of 1.14 eV by Pd-doping and surface oxygen vacancy compared to those on perfect and defective LCF surfaces (min values of 1.76 and 1.34 eV, respectively). Results of Bader charges and bond lengths of CH 4 (or CH 3) and O H show that the initial oxidation of CH 4 molecules is namely the oxidation of dissociated H atoms from CH 4 molecules. And higher valences of surface metal atoms interacted with CH 4 molecules mean the lower dissociation barriers of CH 4 molecules. [Display omitted] [ABSTRACT FROM AUTHOR]