T1ρ-based fibril-reinforced poroviscoelastic constitutive relation of human articular cartilage using inverse finite element technology

BackgroundMapping of T1ρ relaxation time is a quantitative magnetic resonance (MR) method and is frequently used for analyzing microstructural and compositional changes in cartilage tissues. However, there is still a lack of study investigating the link between T1ρ relaxation time and a feasible constitutive relation of cartilage which can be used to model complicated mechanical behaviors of cartilage accurately and properly.MethodsThree-dimensional finite element (FE) models of ten in vitro human tibial cartilage samples were reconstructed such that each element was assigned by material-level parameters, which were determined by a corresponding T1ρ value from MR maps. A T1ρ-based fibril-reinforced poroviscoelastic (FRPE) constitutive relation for human cartilage was developed through an inverse FE optimization technique between the experimental and simulated indentations.ResultsA two-parameter exponential relationship was obtained between the T1ρ and the volume fraction of the hydrated solid matrix in the T1ρ-based FRPE constitutive relation. Compared with the common FRPE constitutive relation (i.e., without T1ρ), the T1ρ-based FRPE constitutive relation indicated similar indentation depth results but revealed some different local changes of the stress distribution in cartilages.ConclusionsOur results suggested that the T1ρ-based FRPE constitutive relation may improve the detection of changes in the heterogeneous, anisotropic, and nonlinear mechanical properties of human cartilage tissues associated with joint pathologies such as osteoarthritis (OA). Incorporating T1ρ relaxation time will provide a more precise assessment of human cartilage based on the individual in vivo MR quantification

LSHR-Net: a hardware-friendly solution for high-resolution computational imaging using a mixed-weights neural network

Recent work showed neural-network based approaches to reconstructing images from compressively sensed measurements offer significant improvements in accuracy and signal compression. Such methods can dramatically boost the capability of computational imaging hardware. However, to date, there have been two major drawbacks: (1) the high-precision real-valued sensing patterns proposed in the majority of existing works can prove problematic when used with computational imaging hardware such as a digital micromirror sampling device and (2) the network structures for image reconstruction involve intensive computation, which is also not suitable for hardware deployment. To address these problems, we propose a novel hardware-friendly solution based on mixed-weights neural networks for computational imaging. In particular, learned binary-weight sensing patterns are tailored to the sampling device. Moreover, we proposed a recursive network structure for low-resolution image sampling and high-resolution reconstruction scheme. It reduces both the required number of measurements and reconstruction computation by operating convolution on small intermediate feature maps. The recursive structure further reduced the model size, making the network more computationally efficient when deployed with the hardware. Our method has been validated on benchmark datasets and achieved state of the art reconstruction accuracy. We tested our proposed network in conjunction with a proof-of-concept hardware setup

Double deletion of PINK1 and Parkin impairs hepatic mitophagy and exacerbates acetaminophen-induced liver injury in mice

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.Mitochondria damage plays a critical role in acetaminophen (APAP)-induced necrosis and liver injury. Cells can adapt and protect themselves by removing damaged mitochondria via mitophagy. PINK1-Parkin pathway is one of the major pathways that regulate mitophagy but its role in APAP-induced liver injury is still elusive. We investigated the role of PINK1-Parkin pathway in hepatocyte mitophagy in APAP-induced liver injury in mice. Wild-type (WT), PINK1 knockout (KO), Parkin KO, and PINK1 and Parkin double KO (DKO) mice were treated with APAP for different time points. Liver injury was determined by measuring serum alanine aminotransferase (ALT) activity, H&E staining as well as TUNEL staining of liver tissues. Tandem fluorescent-tagged inner mitochondrial membrane protein Cox8 (Cox8-GFP-mCherry) can be used to monitor mitophagy based on different pH stability of GFP and mCherry fluorescent proteins. We overexpressed Cox8-GFP-mCherry in mouse livers via tail vein injection of an adenovirus Cox8-GFP-mCherry. Mitophagy was assessed by confocal microscopy for Cox8-GFP-mCherry puncta, electron microscopy (EM) analysis for mitophagosomes and western blot analysis for mitochondrial proteins. Parkin KO and PINK1 KO mice improved the survival after treatment with APAP although the serum levels of ALT were not significantly different among PINK1 KO, Parkin KO and WT mice. We only found mild defects of mitophagy in PINK1 KO or Parkin KO mice after APAP, and improved survival in PINK1 KO and Parkin KO mice could be due to other functions of PINK1 and Parkin independent of mitophagy. In contrast, APAP-induced mitophagy was significantly impaired in PINK1-Parkin DKO mice. PINK1-Parkin DKO mice had further elevated serum levels of ALT and increased mortality after APAP administration. In conclusion, our results demonstrated that PINK1-Parkin signaling pathway plays a critical role in APAP-induced mitophagy and liver injury.NIH R01 AA 020518NIH R01 DK 102142NIH U01 AA 024733NIH P20 GM 103549NIH P30 GM 118247NIH COBRE grant 9P20GM104936NIH S10RR02756

Multitrophic arthropod diversity mediates tree diversity effects on primary productivity

Forests sustain 80% of terrestrial biodiversity and provide essential ecosystem services. Biodiversity experiments have demonstrated that plant diversity correlates with both primary productivity and higher trophic diversity. However, whether higher trophic diversity can mediate the effects of plant diversity on productivity remains unclear. Here, using 5 years of data on aboveground herbivorous, predatory and parasitoid arthropods along with tree growth data within a large-scale forest biodiversity experiment in southeast China, we provide evidence of multidirectional enhancement among the diversity of trees and higher trophic groups and tree productivity. We show that the effects of experimentally increased tree species richness were consistently positive for species richness and abundance of herbivores, predators and parasitoids. Richness effects decreased as trophic levels increased for species richness and abundance of all trophic groups. Multitrophic species richness and abundance of arthropods were important mediators of plant diversity effects on tree productivity, suggesting that optimizing forest management for increased carbon capture can be more effective when the diversity of higher trophic groups is promoted in concert with that of trees

Towards a methodical framework for comprehensively assessing forest multifunctionality

Funded by Deutsche Forschungsgemeinschaft. Grant Number: DFG FOR 891/1-3 National Natural Science Foundation of China. Grant Numbers: 30710103907, 30930005, 31170457, 31210103910 Swiss National Science Foundation (SNSF) Sino-German Centre for Research Promotion in Beijing. Grant Number: GZ 986Peer reviewedPublisher PD

Differential sensitivity of target genes to translational repression by miR-17~92

MicroRNAs (miRNAs) are thought to exert their functions by modulating the expression of hundreds of target genes and each to a small degree, but it remains unclear how small changes in hundreds of target genes are translated into the specific function of a miRNA. Here, we conducted an integrated analysis of transcriptome and translatome of primary B cells from mutant mice expressing miR-17~92 at three different levels to address this issue. We found that target genes exhibit differential sensitivity to miRNA suppression and that only a small fraction of target genes are actually suppressed by a given concentration of miRNA under physiological conditions. Transgenic expression and deletion of the same miRNA gene regulate largely distinct sets of target genes. miR-17~92 controls target gene expression mainly through translational repression and 5’UTR plays an important role in regulating target gene sensitivity to miRNA suppression. These findings provide molecular insights into a model in which miRNAs exert their specific functions through a small number of key target genesCX is a Pew Scholar in Biomedical Sciences. This study is supported by the PEW Charitable Trusts, Cancer Research Institute, National Institute of Health (R01AI087634, R01AI089854, RC1CA146299, R56AI110403, and R01AI121155 to CX), National Natural Science Foundation of China (31570882 to WHL, 31570883 to NX, 31570911 to GF, 91429301 to JH, 31671428 and 31500665 to YZ), 1000 Young Talents Program of China (K08008 to NX), 100 Talents Program of The Chinese Academy of Sciences (YZ), National Program on Key Basic Research Project of China (2016YFA0501900 to YZ), the Fundamental Research Funds for the Central Universities of China (20720150065 to NX and GF), Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2015R1C1A1A01052387 to SGK, NRF-2016R1A4A1010115 to SGK and PHK), and 2016 Research Grant from Kangwon National University (SGK)

Efficient and tunable liquid crystal random laser based on plasmonic-enhanced FRET

Random lasers (RLs), which possess peculiar advantages (e.g., emission and coherence tunable) over traditional lasers with optical resonators, have witnessed rapid development in the past decades. However, it is still a challenge to tune the lasing peak of an RL over a wide range. Here, a temperature-dependent Förster resonance energy transfer (FRET) RL is demonstrated in pyrromethene 597 (PM597, “donor”) and Nile blue (NB, “acceptor”) doped chiral liquid crystals. By changing the temperature that drives the liquid crystal bandgap shift, our RL device exhibits a lasing output change from 560 nm (yellow) to 700 nm (red). While the intrinsic FRET efficiency between PM597 and NB is relatively low, the red lasing is weak. By introducing gold nanorods (GNRs) into these RL devices and utilizing GNRs’ localized surface plasmon resonance (LSPR) effect, the efficiency of FRET transfer is increased by 68.9%, thereby reducing the threshold of the RL devices. By tuning the longitudinal LSPR to match the emission wavelength of NB, the best 200-fold lasing intensity enhancement is recorded. Our findings open a pathway toward realizing LSPR-enhanced FRET tunable RLs and broaden the range of their possible exploration in photonics research and technologies

Ex Situ Reconstruction-Shaped Ir/CoO/Perovskite Heterojunction for Boosted Water Oxidation Reaction

The oxygen evolution reaction (OER) is the performance-limiting step in the process of water splitting. In situ electrochemical conditioning could induce surface reconstruction of various OER electrocatalysts, forming reactive sites dynamically but at the expense of fast cation leaching. Therefore, achieving simultaneous improvement in catalytic activity and stability remains a significant challenge. Herein, we used a scalable cation deficiency-driven exsolution approach to ex situ reconstruct a homogeneous-doped cobaltate precursor into an Ir/CoO/perovskite heterojunction (SCI-350), which served as an active and stable OER electrode. The SCI-350 catalyst exhibited a low overpotential of 240 mV at 10 mA cm-2 in 1 M KOH and superior durability in practical electrolysis for over 150 h. The outstanding activity is preliminarily attributed to the exponentially enlarged electrochemical surface area for charge accumulation, increasing from 3.3 to 175.5 mF cm-2. Moreover, density functional theory calculations combined with advanced spectroscopy and 18O isotope-labeling experiments evidenced the tripled oxygen exchange kinetics, strengthened metal-oxygen hybridization, and engaged lattice oxygen oxidation for O-O coupling on SCI-350. This work presents a promising and feasible strategy for constructing highly active oxide OER electrocatalysts without sacrificing durability