200 research outputs found
Non-invasive color imaging through scattering medium under broadband illumination
Due to the complex of mixed spectral point spread function within memory
effect range, it is unreliable and slow to use speckle correlation technology
for non-invasive imaging through scattering medium under broadband
illumination. The contrast of the speckles will drastically drop as the light
source's spectrum width increases. Here, we propose a method for producing the
optical transfer function with several speckle frames within memory effect
range to image under broadband illumination. The method can be applied to image
amplitude and color objects under white LED illumination. Compared to other
approaches of imaging under broadband illumination, such as deep learning and
modified phase retrieval, our method can provide more stable results with
faster convergence speed, which can be applied in high speed scattering imaging
under natural light illumination
Catalyst Performance Studies on the Guerbet Reaction in a Continuous Flow Reactor Using Mono- and Bi-Metallic Cu-Ni Porous Metal Oxides
Higher alcohols like 1-butanol are considered important biofuels with superior properties compared to the more readily available bio-ethanol. An attractive route to prepare 1-butanol from ethanol is the Guerbet reaction. We here report the use of hydrotalcite-derived mono- (Cu-PMO or Ni-PMO) and bi-metallic (CuNi-PMO) porous metal oxide catalysts for the Guerbet coupling of ethanol to 1-butanol in a continuous flow reactor (320 °C, 0.1 MPa, LHSV = 15 mL g−1 h−1) at extended times on stream (~160 h). Two distinct regimes with different product distributions were observed for the Cu-PMO and CuNi-PMO catalyst with time on stream. At the start of the run, the initial conversion of ethanol dropped from about 85% to less than 20% after 60 h and acetaldehyde was the main product (regime 1). At prolonged times on stream (60–160 h), fairly constant low conversions of ethanol (14%) were observed and 1-butanol was the main product (regime 2). Performance of the monometallic Cu-PMO catalyst in terms of 1-butanol yield and stability was lower compared to the bi-metallic CuNi-PMO. Detailed catalyst characterization studies (XRD, H2-TPR, sorption of acrylic acid, TGA, TEM, HAADF-STEM, and EDS mapping) on both fresh and spent CuNi-PMO taken at various times on stream was performed to determine the changes in catalyst morphology and composition during a run, and particularly to obtain information on changes in catalyst structure operating in regime 1 or 2. The change in chemoselectivity is in line with an increase in basicity of the catalyst at extended runtimes
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A Novel Signal Transduction Pathway that Modulates <i>rhl</i> Quorum Sensing and Bacterial Virulence in <i>Pseudomonas aeruginosa</i>
The rhl quorum-sensing (QS) system plays critical roles in the pathogenesis of P. aeruginosa. However, the regulatory effects that occur directly upstream of the rhl QS system are poorly understood. Here, we show that deletion of gene encoding for the two-component sensor BfmS leads to the activation of its cognate response regulator BfmR, which in turn directly binds to the promoter and decreases the expression of the rhlR gene that encodes the QS regulator RhlR, causing the inhibition of the rhl QS system. In the absence of bfmS, the Acka-Pta pathway can modulate the regulatory activity of BfmR. In addition, BfmS tunes the expression of 202 genes that comprise 3.6% of the P. aeruginosa genome. We further demonstrate that deletion of bfmS causes substantially reduced virulence in lettuce leaf, reduced cytotoxicity, enhanced invasion, and reduced bacterial survival during acute mouse lung infection. Intriguingly, specific missense mutations, which occur naturally in the bfmS gene in P. aeruginosa cystic fibrosis (CF) isolates such as DK2 strains and RP73 strain, can produce BfmS variants (BfmSL181P, BfmSL181P/E376Q, and BfmSR393H) that no longer repress, but instead activate BfmR. As a result, BfmS variants, but not the wild-type BfmS, inhibit the rhl QS system. This study thus uncovers a previously unexplored signal transduction pathway, BfmS/BfmR/RhlR, for the regulation of rhl QS in P. aeruginosa. We propose that BfmRS TCS may have an important role in the regulation and evolution of P. aeruginosa virulence during chronic infection in CF lungs.</p
Adrenocortical carcinoma in patients with MEN1: a kindred report and review of the literature
Objective: Up to 40% of multiple endocrine neoplasia type 1 (MEN1) patients may have adrenal cortical tumors. However, adrenocortical carcinoma (ACC) is rare. The clinical manifestations, prevalence, inheritance and prognosis of ACC associated with MEN1 remain unclear. Here we report the clinical manifestations and prevalence of ACC in patients with MEN1.
Design and methods: A retrospective analysis of ACC associated with MEN1 patients at a single tertiary care center from December 2001 to June 2017. Genetic analysis of MEN1 and other ACC associated genes, loss of heterozygosity (LOH) of MEN1 locus, immunohistochemistry staining of menin, P53 and β-catenin in ACC tissue were performed.
Results: Two related patients had ACC associated with MEN1. The father had ENSAT stage IV tumor with excessive production of cortisol; the daughter had nonfunctional ENSAT stage I tumor. Both patients carried novel germline heterozygous mutation (c.400_401insC) of MEN1. The wild-type MEN1 allele was lost in the resected ACC tissue from the daughter with no menin staining. The ACC tissue had nuclear β-catenin staining, with heterozygous CTNNB1 mutation of 357del24 and P53 staining in only 20% cells.
Conclusions: ACC associated with MEN1 is rare and may occur in familial aggregates
Gut Symbionts alleviate Mash Through a Secondary Bile acid Biosynthetic Pathway
The gut microbiota has been found to play an important role in the progression of metabolic dysfunction-associated steatohepatitis (MASH), but the mechanisms have not been established. Here, by developing a click-chemistry-based enrichment strategy, we identified several microbial-derived bile acids, including the previously uncharacterized 3-succinylated cholic acid (3-sucCA), which is negatively correlated with liver damage in patients with liver-tissue-biopsy-proven metabolic dysfunction-associated fatty liver disease (MAFLD). By screening human bacterial isolates, we identified Bacteroides uniformis strains as effective producers of 3-sucCA both in vitro and in vivo. By activity-based protein purification and identification, we identified an enzyme annotated as β-lactamase in B. uniformis responsible for 3-sucCA biosynthesis. Furthermore, we found that 3-sucCA is a lumen-restricted metabolite and alleviates MASH by promoting the growth of Akkermansia muciniphila. together, our data offer new insights into the gut microbiota-liver axis that may be leveraged to augment the management of MASH
Biocleavable Polycationic Micelles as Highly Efficient Gene Delivery Vectors
An amphiphilic disulfide-containing polyamidoamine was synthesized by Michael-type polyaddition reaction of piperazine to equimolar N, N′-bis(acryloyl)cystamine with 90% yield. The polycationic micelles (198 nm, 32.5 mV), prepared from the amphiphilic polyamidoamine by dialysis method, can condense foreign plasmid DNA to form nanosized polycationic micelles/DNA polyelectrolyte complexes with positive charges, which transfected 293T cells with high efficiency. Under optimized conditions, the transfection efficiencies of polycationic micelles/DNA complexes are comparable to, or even higher than that of commercially available branched PEI (Mw 25 kDa)
Blocking TLR2 Activity Attenuates Pulmonary Metastases of Tumor
Background: Metastasis is the most pivotal cause of mortality in cancer patients. Immune tolerance plays a crucial role in tumor progression and metastasis. Methods and Findings: In this study, we investigated the potential roles and mechanisms of TLR2 signaling on tumor metastasis in a mouse model of intravenously injected B16 melanoma cells. Multiple subtypes of TLRs were expressed on B16 cells and several human cancer cell lines; TLR2 mediated the invasive activity of these cells. High metastatic B16 cells released more heat shock protein 60 than poor metastatic B16-F1 cells. Importantly, heat shock protein 60 released by tumor cells caused a persistent activation of TLR2 and was critical in the constitutive activation of transcription factor Stat3, leading to the release of immunosuppressive cytokines and chemokines. Moreover, targeting TLR2 markedly reduced pulmonary metastases and increased the survival of B16-bearing mice by reversing B16 cells induced immunosuppressive microenvironment and restoring tumor-killing cells such as CD8 + T cells and M1 macrophages. Combining an anti-TLR2 antibody and a cytotoxic agent, gemcitabine, provided a further improvement in the survival of tumor-bearing mice. Conclusions and Significance: Our results demonstrate that TLR2 is an attractive target against metastasis and that targeting immunosuppressive microenvironment using anti-TLR2 antibody is a novel therapeutic strategy for combating
Does or did the supernova remnant Cassiopeia A operate as a PeVatron?
For decades, supernova remnants (SNRs) have been considered the prime sources
of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to
PeV energies and thus dominate CR flux up to the knee is currently under
intensive theoretical and phenomenological debate. The direct test of the
ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy
(UHE; ~TeV) -rays. In this context, the historical
SNR Cassiopeia A (Cas A) is considered one of the most promising target for UHE
observations. This paper presents the observation of Cas A and its vicinity by
the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE
band, combined with the young age of Cas A, enabled us to derive stringent
model-independent limits on the energy budget of UHE protons and nuclei
accelerated by Cas A at any epoch after the explosion. The results challenge
the prevailing paradigm that Cas A-type SNRs are major suppliers of PeV CRs in
the Milky Way.Comment: 11 pages, 3 figures, Accepted by the APJ
Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A
The diffuse Galactic -ray emission, mainly produced via interactions
between cosmic rays and the interstellar medium and/or radiation field, is a
very important probe of the distribution, propagation, and interaction of
cosmic rays in the Milky Way. In this work we report the measurements of
diffuse -rays from the Galactic plane between 10 TeV and 1 PeV
energies, with the square kilometer array of the Large High Altitude Air Shower
Observatory (LHAASO). Diffuse emissions from the inner
(, ) and outer
(, ) Galactic plane are detected with
and significance, respectively. The outer Galactic
plane diffuse emission is detected for the first time in the very- to
ultra-high-energy domain (~TeV). The energy spectrum in the inner Galaxy
regions can be described by a power-law function with an index of
, which is different from the curved spectrum as expected from
hadronic interactions between locally measured cosmic rays and the
line-of-sight integrated gas content. Furthermore, the measured flux is higher
by a factor of than the prediction. A similar spectrum with an index of
is found in the outer Galaxy region, and the absolute flux for
TeV is again higher than the prediction for hadronic
cosmic ray interactions. The latitude distributions of the diffuse emission are
consistent with the gas distribution, while the longitude distributions show
clear deviation from the gas distribution. The LHAASO measurements imply that
either additional emission sources exist or cosmic ray intensities have spatial
variations.Comment: 12 pages, 8 figures, 5 tables; accepted for publication in Physical
Review Letters; source mask file provided as ancillary fil
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