250 research outputs found
dATP/ATP, a Multifunctional Nucleotide, Stimulates Bacterial Cell Lysis, Extracellular DNA Release and Biofilm Development
Background: Signaling by extracellular adenosine 59-triphosphase (eATP) is very common for cell-to-cell communication in many basic patho-physiological development processes. Rapid release of ATP into the extracellular environment from distressed or injured eukaryotic cells due to pathogens or other etiological factors can serve as a ‘‘danger signal’’, activating host innate immunity. However, little is known about how or whether pathogenic bacteria respond to this ‘‘danger signal’’. Methods and Principal Findings: Here we report that extracellular dATP/ATP can stimulate bacterial adhesion and biofilm formation via increased cell lysis and extracellular DNA (eDNA) release. We demonstrate that extracellular dATP/ATP also stimulates bacterial adherence in vitro to human bronchial epithelial cells. Conclusions and Significance: These data suggest that bacteria may sense extracellular dATP/ATP as a signal of ‘‘danger’’ and form biofilms to protect them from host innate immunity. This study reveals a very important and unrecognized phenomenon that both bacteria and host cells could respond to a common important signal molecule in a race to adapt to the presence of one another. We propose that extracellular dATP/ATP functions as an ‘‘inter-domain’ ’ warning signal that serves to induce protective measures in both Bacterial and Eukaryotic cells
The Activity of Small Urea‐γ‐AApeptides Toward Gram‐Positive Bacteria
Host Defense Peptides (HDPs) have gained considerable interest due to the omnipresent threat of bacterial infection as a serious public health concern. However, development of HDPs is impeded by several drawbacks, such as poor selectivity, susceptibility to proteolytic degradation, low‐to‐moderate activity and requiring complex syntheses. Herein we report a class of lipo‐linear α/urea‐γ‐AApeptides with a hybrid backbone and low molecular weight. The heterogeneous backbone not only enhances chemodiversity, but also shows effective antimicrobial activity against Gram‐positive bacteria and is capable of disrupting bacterial membranes and killing bacteria rapidly. Given their low molecular weight and ease of access via facile synthesis, they could be practical antibiotic agents.Double‐AA peptides: We investigated a new class of small linear molecules as potential antibiotic agents against Gram‐positive bacteria. Our studies suggest that these compounds can disrupt bacterial membranes and kill bacteria rapidly. Given their low molecular weight and ease of accessibility through a facile synthesis approach, they are good candidates for development into antibiotic agents.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152544/1/cmdc201900520-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152544/2/cmdc201900520.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152544/3/cmdc201900520_am.pd
Design and construction of a co-planar power bus interconnect for low inductance switching
A co-planar tab-slot type of interconnect demonstrator for connecting power switching devices and DC bus capacitors has been designed and constructed, aimed at low inductance switching. The demonstrator is composed of a double-sided tab connector and a dual polarity slot. This type of interconnect eliminates the use of screw terminal connection between a power module and the DC bus as well as between the DC bus and power capacitors, thus serves to maintain a coplanar current profile throughout the power distribution path. Parasitic analysis both in impedance testing and in Finite Element simulation suggests that the inductance in the bus loop of the demonstrator is approximately half of that achieved in an equally dimensioned busbar with conventional screw terminals
VIVO: Visual Vocabulary Pre-Training for Novel Object Captioning
It is highly desirable yet challenging to generate image captions that can
describe novel objects which are unseen in caption-labeled training data, a
capability that is evaluated in the novel object captioning challenge (nocaps).
In this challenge, no additional image-caption training data, other thanCOCO
Captions, is allowed for model training. Thus, conventional Vision-Language
Pre-training (VLP) methods cannot be applied. This paper presents VIsual
VOcabulary pretraining (VIVO) that performs pre-training in the absence of
caption annotations. By breaking the dependency of paired image-caption
training data in VLP, VIVO can leverage large amounts of paired image-tag data
to learn a visual vocabulary. This is done by pre-training a multi-layer
Transformer model that learns to align image-level tags with their
corresponding image region features. To address the unordered nature of image
tags, VIVO uses a Hungarian matching loss with masked tag prediction to conduct
pre-training. We validate the effectiveness of VIVO by fine-tuning the
pre-trained model for image captioning. In addition, we perform an analysis of
the visual-text alignment inferred by our model. The results show that our
model can not only generate fluent image captions that describe novel objects,
but also identify the locations of these objects. Our single model has achieved
new state-of-the-art results on nocaps and surpassed the human CIDEr score.Comment: AAAI 202
Experimental observation of Dirac-like surface states and topological phase transition in PbSnTe(111) films
The surface of a topological crystalline insulator (TCI) carries an even
number of Dirac cones protected by crystalline symmetry. We epitaxially grew
high quality PbSnTe(111) films and investigated the TCI phase by
in-situ angle-resolved photoemission spectroscopy. PbSnTe(111)
films undergo a topological phase transition from trivial insulator to TCI via
increasing the Sn/Pb ratio, accompanied by a crossover from n-type to p-type
doping. In addition, a hybridization gap is opened in the surface states when
the thickness of film is reduced to the two-dimensional limit. The work
demonstrates an approach to manipulating the topological properties of TCI,
which is of importance for future fundamental research and applications based
on TCI
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