52 research outputs found
Graphite Nanoeraser
We present here a method for cleaning intermediate-size (5~50nm)
contamination from highly oriented pyrolytic graphite. Electron beam deposition
causes a continuous increase of carbonaceous material on graphene and graphite
surfaces, which is difficult to remove by conventional techniques. Direct
mechanical wiping using a graphite nanoeraser is observed to drastically reduce
the amount of contamination. After the mechanical removal of contamination, the
graphite surfaces were able to self-retract after shearing, indicating that van
der Waals contact bonding is restored. Since contact bonding provides an
indication of a level of cleanliness normally only attainable in a high-quality
clean-room, we discuss potential applications in preparation of ultraclean
surfaces.Comment: 10 pages, two figure
I2P-Rec: Recognizing Images on Large-scale Point Cloud Maps through Bird's Eye View Projections
Place recognition is an important technique for autonomous cars to achieve
full autonomy since it can provide an initial guess to online localization
algorithms. Although current methods based on images or point clouds have
achieved satisfactory performance, localizing the images on a large-scale point
cloud map remains a fairly unexplored problem. This cross-modal matching task
is challenging due to the difficulty in extracting consistent descriptors from
images and point clouds. In this paper, we propose the I2P-Rec method to solve
the problem by transforming the cross-modal data into the same modality.
Specifically, we leverage on the recent success of depth estimation networks to
recover point clouds from images. We then project the point clouds into Bird's
Eye View (BEV) images. Using the BEV image as an intermediate representation,
we extract global features with a Convolutional Neural Network followed by a
NetVLAD layer to perform matching. The experimental results evaluated on the
KITTI dataset show that, with only a small set of training data, I2P-Rec
achieves recall rates at Top-1\% over 80\% and 90\%, when localizing monocular
and stereo images on point cloud maps, respectively. We further evaluate
I2P-Rec on a 1 km trajectory dataset collected by an autonomous logistics car
and show that I2P-Rec can generalize well to previously unseen environments.Comment: Accepted by IROS 202
Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation
Communication between the SR (sarcoplasmic reticulum, SR) and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs) at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM). Although it has been demonstrated that CaR (calcium sensing receptor) activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re), the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation
Serum dihydroxyacetone kinase peptide m/z 520.3 as predictor of disease severity in patients with compensated chronic hepatitis B
Background & aim: Due to known limitations of liver biopsy, reliable non-invasive serum biomarkers for chronic liver diseases are needed. We performed serum peptidomics for such investigation in compensated chronic hepatitis B (CHB) patients. Methods: Liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) was used to identify differentially expressed peptides in sera from 40 CHB patients (20 with S0G0-S1G1 and 20 with S3G3-S4G4). Ion pair quantification from differentially expressed peptides in a validation set of sera from 86 CHB patients was done with multiple reaction monitoring (MRM). Results: 21 differentially represented peptide peaks were found through LC-MS/MS. Ion pairs generated from eleven of these peptides (m/z < 800) were quantified by MRM. Summed peak area ratios of 6 ion pairs from peptide m/z 520.3 (176.1, 353.7, 459.8, 503.3, 351.3, 593.1), which was identified as dihydroxyacetone kinase (DAK) fragment, decreased from mild to advanced stages of fibrosis or inflammation. Area Under Receiver Operating Characteristic Curves (AUROCs) of five ion models discriminating fibrosis degrees were 0.871 ~ 0.915 (S2-4 versus S0-1) and 0.804 ~ 0.924 (S3-4 versus S0-2). AUROCs discriminating inflammation grades were 0.840 ~ 0.902 (G2-4 versus G0-1) and 0.787 ~ 0.888 (G3-4 versus G0-2). The diagnostic power of these models provides improved sensitivity and specificity for predicting disease progression as compared to aspartate aminotransferase to platelet ratio index (APRI), FIB-4, Forn’s index and serum DAK protein. Conclusions: The peptide fragment (m/z 520.3) of DAK is a promising biomarker to guide timing of antiviral treatment and to avoid liver biopsy in compensated CHB patients
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