500 research outputs found
From secretome analysis to immunology: chitosan induces major alterations in the activation of dendritic cells via a TLR4-dependent mechanism
Dendritic cells are known to be activated by a wide range of microbial
products, leading to cytokine production and increased levels of membrane
markers such as major histocompatibility complex class II molecules. Such
activated dendritic cells possess the capacity to activate na\"ive T cells. In
the present study we demonstrated that immature dendritic cells secrete both
the YM1 lectin and lipocalin-2. By testing the ligands of these two proteins,
chitosan and siderophores, respectively, we also demonstrated that chitosan, a
degradation product of various fungal and protozoal cell walls, induces an
activation of dendritic cells at the membrane level, as shown by the
up-regulation of membrane proteins such as class II molecules, CD80 and CD86
via a TLR4-dependent mechanism, but is not able to induce cytokine production.
This led to the production of activated dendritic cells unable to stimulate T
cells. However, costimulation with other microbial products overcame this
partial activation and restored the capacity of these activated dendritic cells
to stimulate T cells. In addition, successive stimulation with chitosan and
then by lipopolysaccharide induced a dose-dependent change in the cytokinic
IL-12/IL-10 balance produced by the dendritic cells
Specific heats of dilute neon inside long single-walled carbon nanotube and related problems
An elegant formula for coordinates of carbon atoms in a unit cell of a
single-walled nanotube (SWNT) is presented and the potential of neon (Ne)
inside an infinitely long SWNT is analytically derived out under the condition
of the Lennard-Jones potential between Ne and carbon atoms.
Specific heats of dilute Ne inside long (20, 20) SWNT are calculated at
different temperatures. It is found that Ne exhibits 3-dimensional (3D) gas
behavior at high temperature but behaves as 2D gas at low temperature.
Especially, at ultra low temperature, Ne inside (20, 20) nanotubes behaves as
lattice gas. A coarse method to determine the characteristic temperature
for low density gas in a potential is put forward. If
, we just need to use the classical statistical
mechanics without solving the Shr\"{o}dinger equation to consider the thermal
behavior of gas in the potential. But if , we
must solve the Shr\"{o}dinger equation. For Ne in (20,20) nanotube, we obtain
K.Comment: 14 pages, 7 figure
Impact of stream impurities on compressor power requirements for CO2 pipeline transportation
The economic viability of Carbon Capture and Sequestration (CCS) as a means of mitigating CO2 emissions is significantly dependent on the minimisation of costs associated with the compression and transportation of the captured CO2. This paper describes the development and application of a rigorous thermodynamic model to compute and compare power requirements for various multistage compression strategies for CO2 streams containing typical impurities originating from various capture technologies associated with industrial and power emission sectors. The compression options examined include conventional multistage integrally geared centrifugal compressors, supersonic shockwave compressors and multistage compression combined with subcritical liquefaction and pumping. The study shows that for all the compression options examined, the compression power reduces with the increase in the purity of the CO2 stream, while the inter-stage cooling duty is predicted to be significantly higher than the compression power demand. For CO2 streams carrying less than 5% impurities, multistage compression combined with liquefaction and subsequent pumping from ca 62 bar pressure can offer higher efficiency than conventional gas-phase compression. In the case of a raw/dehumidified oxy-fuel CO2 stream of ca 85% purity, subcritical liquefaction at 62 bar pressure is shown to increase the cooling duty by ca 50% as compared to pure CO2
Strong Inter-valley Electron-Phonon Coupling in Magic-Angle Twisted Bilayer Graphene
The unusual properties of superconductivity in magic-angle twisted bilayer
graphene (MATBG) have sparked enormous research interest. However, despite the
dedication of intensive experimental efforts and the proposal of several
possible pairing mechanisms, the origin of its superconductivity remains
elusive. Here, using angle-resolved photoemission spectroscopy with micrometer
spatial resolution, we discover replicas of the flat bands in superconducting
MATBG unaligned with its hexagonal boron nitride (hBN) substrate, which are
absent in non-superconducting MATBG aligned with the hBN substrate. Crucially,
the replicas are evenly spaced in energy, separated by 150 +- 15 meV,
signalling the strong coupling of electrons in MATBG to a bosonic mode of this
energy. By comparing our observations to simulations, the formation of replicas
is attributed to the presence of strong inter-valley electron-phonon coupling
to a K-point phonon mode. In total, the observation of these replica flat bands
and the corresponding phonon mode in MATBG could provide important information
for understanding the origin and the unusual properties of its superconducting
phase.Comment: 17 pages, 4 figure
Fighting viral infections and virus-driven tumors with cytotoxic CD4+ T cells
CD4+ T cells have been and are still largely regarded as the orchestrators of immune responses, being able to differentiate into distinct T helper cell populations based on differentiation signals, transcription factor expression, cytokine secretion, and specific functions. Nonetheless, a growing body of evidence indicates that CD4+ T cells can also exert a direct effector activity, which depends on intrinsic cytotoxic properties acquired and carried out along with the evolution of several pathogenic infections. The relevant role of CD4+ T cell lytic features in the control of such infectious conditions also leads to their exploitation as a new immunotherapeutic approach. This review aims at summarizing currently available data about functional and therapeutic relevance of cytotoxic CD4+ T cells in the context of viral infections and virus-driven tumors
Targeting LOXL2 for cardiac interstitial fibrosis and heart failure treatment
Interstitial fibrosis plays a key role in the development and progression of heart failure. Here, we show that an enzyme that crosslinks collagen-Lysyl oxidase-like 2 (Loxl2)-is essential for interstitial fibrosis and mechanical dysfunction of pathologically stressed hearts. In mice, cardiac stress activates fibroblasts to express and secrete Loxl2 into the interstitium, triggering fibrosis, systolic and diastolic dysfunction of stressed hearts. Antibody-mediated inhibition or genetic disruption of Loxl2 greatly reduces stress-induced cardiac fibrosis and chamber dilatation, improving systolic and diastolic functions. Loxl2 stimulates cardiac fibroblasts through PI3K/AKT to produce TGF-β2, promoting fibroblast-to-myofibroblast transformation; Loxl2 also acts downstream of TGF-β2 to stimulate myofibroblast migration. In diseased human hearts, LOXL2 is upregulated in cardiac interstitium; its levels correlate with collagen crosslinking and cardiac dysfunction. LOXL2 is also elevated in the serum of heart failure (HF) patients, correlating with other HF biomarkers, suggesting a conserved LOXL2-mediated mechanism of human HF
GPI 2.0: Performance Evaluation of the Wavefront Sensor's EMCCD
The Gemini Planet Imager (GPI) is a high contrast imaging instrument that
aims to detect and characterize extrasolar planets. GPI is being upgraded to
GPI 2.0, with several subsystems receiving a re-design to improve the
instrument's contrast. To enable observations on fainter targets and increase
stability on brighter ones, one of the upgrades is to the adaptive optics
system. The current Shack-Hartmann wavefront sensor (WFS) is being replaced by
a pyramid WFS with an low-noise electron multiplying CCD (EMCCD). EMCCDs are
detectors capable of counting single photon events at high speed and high
sensitivity. In this work, we characterize the performance of the HN\"u 240
EMCCD from N\"uv\"u Cameras, which was custom-built for GPI 2.0. The HN\"u 240
EMCCD's characteristics make it well suited for extreme AO: it has low dark
current ( 0.01 e-/pix/fr), low readout noise (0.1 e-/pix/fr at a gain of
5000), high quantum efficiency ( 90% at wavelengths from 600-800 nm; 70% from
800-900 nm), and fast readout (up to 3000 fps full frame). Here we present test
results on the EMCCD's noise contributors, such as the readout noise,
pixel-to-pixel variability and CCD bias. We also tested the linearity and EM
gain calibration of the detector. All camera tests were conducted before its
integration into the GPI 2.0 PWFS system.Comment: 16 pages, 14 figures. Conference Proceedings for AO4ELT7, held in
June 2023 in Avignon, Franc
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