We present maps of atomic carbon C i( ) and C i( ) emission (hereafter C i (1−0) and C i (2−1), respectively) at a linear resolution ∼1 kpc scale for a sample of one H ii, six LINER, three Seyfert, ...and five starburst galaxies observed with the Herschel Space Observatory. We compare spatial distributions of two C i lines with that of CO (hereafter CO (1−0)) emission, and find that both C i lines distribute similarly to CO (1−0) emission in most galaxies. We present luminosity ratio maps of / , / , (hereafter ) and 70-to-160 m far-infrared color of f70/f160. / , and are centrally peaked in starbursts; whereas they remain relatively constant in LINERs, indicating that star-forming activity can enhance carbon emission, especially for C i (2−1). We explore the correlations between the luminosities of CO (1−0) and C i lines, and find that correlates tightly and almost linearly with both and , suggesting that C i lines, similar to CO (1−0), can trace total molecular gas in H ii, LINER, Seyfert, and starburst galaxies on kpc scales. We investigate the dependence of / , / and C i excitation temperature, Tex, on dust temperature, Tdust, and find noncorrelation and a weak and modest correlation, respectively. The ratio of / stays a smooth distribution in most galaxies, indicating that the conversion factor of C i (1−0) luminosity to H2 mass ( ) changes with CO (1−0) conversion factor ( ) proportionally. Under optically thin and local thermodynamical equilibrium assumptions, we derive a galaxy-wide average carbon excitation temperature of , and an average neutral carbon abundance of in our resolved sample, which is comparable to the usually adopted value of 3 × 10−5, but ∼3 times lower than the carbon abundance in local (ultra)luminous infrared galaxies. We conclude that the carbon abundance varies in different galaxy types.
Abstract We present a study of the molecular gas in early-mid stage major mergers, with a sample of 43 major-merger galaxy pairs selected from the Mapping Nearby Galaxies at Apache Point Observatory ...survey and a control sample of 195 isolated galaxies selected from the xCOLD GASS survey. Adopting kinematic asymmetry as a new effective indicator to describe the merger stage, we aim to study the role of molecular gas in the merger-induced star formation enhancement along the merger sequence of galaxy pairs. We obtain the molecular gas properties from CO observations with the James Clerk Maxwell Telescope, Institut de Radioastronomie Milimetrique 30 m telescope, and the MaNGA-ARO Survey of CO Targets survey. Using these data, we investigate the differences in molecular gas fraction ( f H 2 ), star formation rate (SFR), star formation efficiency (SFE), molecular-to-atomic gas ratio ( M H 2 / M H i ), total gas fraction ( f gas ), and the SFE of total gas (SFE gas ) between the pair and control samples. In the full pair sample, our results suggest the f H 2 of paired galaxies is significantly enhanced, while the SFE is comparable to that of isolated galaxies. We detect significantly increased f H 2 and M H 2 / M H i in paired galaxies at the pericenter stage, indicating an accelerated transition from atomic gas to molecular gas due to interactions. Our results indicate that the elevation of f H 2 plays a major role in the enhancement of global SFR in paired galaxies at the pericenter stage, while the contribution of enhanced SFE in specific regions requires further explorations through spatially resolved observations of a larger sample spanning a wide range of merger stages.
Abstract
The Submillimetre Common User Bolometer Array 2 (SCUBA-2) is the James Clerk Maxwell Telescope’s continuum imager, operating simultaneously at 450 and 850
μ
m. SCUBA-2 was commissioned in ...2009–2011, and since that time, regular observations of point-like standard sources have been performed whenever the instrument is in use. Expanding the calibrator observation sample by an order of magnitude compared to previous work, in this paper we derive updated opacity relations at each wavelength for a new atmospheric extinction correction, analyze the Flux Conversion Factors used to convert instrumental units to physical flux units as a function of date and observation time, present information on the beam profiles for each wavelength, and update secondary calibrator source fluxes. Between 07:00 and 17:00 UTC, the portion of the night that is most stable to temperature gradients that cause dish deformation, the total flux uncertainty and the peak flux uncertainty measured at 450
μ
m are found to be 14% and 17%, respectively. Measured at 850
μ
m, the total flux and peak flux uncertainties are 6% and 7%, respectively. The analysis presented in this work is applicable to all SCUBA-2 projects observed since 2011.
In this work, carbon black (CB) was introduced into polypropylene/carbon fiber (PP/CF) composite to fabricate multifunctional composites with the improved thermal stability, flame retardancy and ...electrical conductivity. The morphology investigation showed that one-dimensional CF and zero-dimensional were well dispersed in the PP matrix, and the multistage structure was formed in PP matrix. Compared to pristine PP, the maximum weight loss temperature under air atmosphere was enhanced by 79°C. The peak value of the heat release rate measured by a cone calorimeter was significantly reduced by 70%, and the total heat release decreased from 198 to 166MJ/m2. The dramatically enhanced flame retardancy of PP composites was attributed to the formation of a strong three-dimensional (3D) network structure in PP matrix where one-dimensional CF acted as bridges connecting individual zero-dimensional CB, and the accelerated oxidation crosslinking reaction of PP radicals by CB and CF. Furthermore, the electrical conductivity of PP composites was significantly enhanced to 7.8S/m due to the formation of 3D conductive pathways from CB and CF within the matrix.
ABSTRACT
Molecular gas plays a critical role in explaining the quiescence of star formation (SF) in massive isolated spiral galaxies, which could be a result of either the low molecular gas content ...and/or the low SF efficiency. We present IRAM 30-m observations of the CO lines in the Sombrero galaxy (NGC 4594), the most massive spiral at $d\lesssim 30\rm ~Mpc$. We detect at least one of the three CO lines covered by our observations in all 13 observed positions located at the galactic nucleus and along an $\sim 25\rm ~kpc$-diameter dusty ring. The total extrapolated molecular gas mass of the galaxy is $M_{\rm H_2}\approx 4\times 10^{8}\rm ~M_\odot$. The measured maximum CO gas rotation velocity of $\approx 381\rm ~km~s^{-1}$ suggests that NGC 4594 locates in a dark matter halo with a mass $M_{\rm 200}\gtrsim 10^{13}\rm ~M_\odot$. Comparing to other galaxy samples, NGC 4594 is extremely gas poor and SF inactive, but the SF efficiency is apparently not inconsistent with that predicted by the Kennicutt–Schmidt law, so there is no evidence of enhanced SF quenching in this extremely massive spiral with a huge bulge. We also calculate the predicted gas supply rate from various sources to replenish the cold gas consumed in SF, and find that the galaxy must experience a starburst stage at high redshift, then the leftover or recycled gas provides SF fuels to maintain the gradual growth of the galactic disc at a gentle rate.
Mixed ionic‐electronic conducting (MIEC) membranes have gained growing interest recently for various promising environmental and energy applications, such as H2 and O2 production, CO2 reduction, O2 ...and H2 separation, CO2 separation, membrane reactors for production of chemicals, cathode development for solid oxide fuel cells, solar‐driven evaporation and energy‐saving regeneration as well as electrolyzer cells for power‐to‐X technologies. The purpose of this roadmap, written by international specialists in their fields, is to present a snapshot of the state‐of‐the‐art, and provide opinions on the future challenges and opportunities in this complex multidisciplinary research field. As the fundamentals of using MIEC membranes for various applications become increasingly challenging tasks, particularly in view of the growing interdisciplinary nature of this field, a better understanding of the underlying physical and chemical processes is also crucial to enable the career advancement of the next generation of researchers. As an integrated and combined article, it is hoped that this roadmap, covering all these aspects, will be informative to support further progress in academics as well as in the industry‐oriented research toward commercialization of MIEC membranes for different applications.
The roadmap involving multidisciplinary research fields, presented by various global experts in their fields, is intended to give an overview on the status and breakthroughs of this evolving and growing interdisciplinary field and provide insights into the challenges driven by the research needs and opportunities in the diverse and rich field of using mixed ionic‐electronic conducting membranes.
Damage in a rock mass is heavily dependent on the existence and growth of joints, which are also influenced by the complex stress states induced by human activities (e.g., tunneling and excavation). ...A proper representation of the loading path is essential for understanding the mechanical behaviors of rock masses. Based on the discrete element method (DEM), the influence of the loading path on the cracking process of a rock specimen containing an open flaw is examined. The effectiveness of the model is confirmed by comparing the simulation results under a uniaxial compression test to existing research findings, where wing crack initiates first and secondary cracks contribute to the failure of the specimen. Simulation results confirm that the cracking process is dependent upon both the confining pressure and the loading path. Under the axial loading test, a higher confining pressure suppresses the development of tensile wing cracks and forces the formation of secondary cracks in the form of shear bands perpendicular to the flaw. Increase of confining pressure also decreases the influence of the loading path on the cracking process. Reduction of confining pressure during an unloading test amplifies the concentration of tensile stress and ultimately promotes the appearance of a tensile splitting fracture at meso-scale. Confining pressure at the failure stage is well predicted by the Hoek-Brown failure criterion under quasi-static conditions.
We present CO (J = 1−0) and/or CO (J = 2−1) spectroscopy for 31 galaxies selected from the ongoing Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, obtained with multiple ...telescopes. This sample is combined with CO observations from the literature to study the correlation of the CO luminosities ( ) with the mid-infrared luminosities at 12 ( ) and 22 m ( ), as well as the dependence of the residuals on a variety of galaxy properties. The correlation with is tighter and more linear, but galaxies with relatively low stellar masses ( M ) and blue colors ( and/or NUV − r 3) fall significantly below the mean - relation. We propose a new estimator of the CO (1−0) luminosity (and thus the total molecular gas mass Mmol) that is a linear combination of three parameters: , , and g − r. We show that, with a scatter of only 0.18 dex in log , this estimator provides unbiased estimates for galaxies of different properties and types. An immediate application of this estimator to a compiled sample of galaxies with only CO (J = 2−1) observations yields a distribution of the CO (J = 2−1) to CO (J = 1−0) luminosity ratios (R21) that agrees well with the distribution of real observations, in terms of both the median and the shape. Application of our estimator to the current MaNGA sample reveals a gas-poor population of galaxies that are predominantly early-type and show no correlation between molecular gas-to-stellar mass ratio and star formation rate, in contrast to gas-rich galaxies. We also provide alternative estimators with similar scatters, based on r- and/or z-band luminosities instead of . These estimators serve as cheap and convenient Mmol proxies to be potentially applied to large samples of galaxies, thus allowing statistical studies of gas-related processes of galaxies.
Background: Tumor PD-L1 levels have predictive value in PD-1/PD-L1 checkpoint blockade therapies, yet biopsies can only provide baseline information. Whether PD-L1 expression on circulating tumor ...cells (CTCs) could serve as an alternative biomarker is of great interest.
Design: We established an immunofluorescence assay for semi-quantitative assessment of the PD-L1 expression levels on CTCs with four categories (PD-L1
negative
, PD-L1
low
, PD-L1
medium
and PD-L1
high
). 35 patients with different advanced gastrointestinal tumors were enrolled in a phase 1 trial of a PD-1 inhibitor, IBI308. The CTC numeration and the PD-L1 expression levels were analyzed.
Results: Prior the treatment of IBI308, 97% (34/35) patients had CTCs, ranging from1 to 70 (median 7). 74% (26/35) had PD-L1
positive
CTCs, and 60% (21/35) had at least one PD-L1
high
CTCs. The disease control (DC) rate in PD-L1
high
patients (48%) is much higher than the others (14%). The group with at least 20% abundance of PD-L1
high
CTCs had even higher DC rate of 64% (9/14), with only 14% DC rate for the rest (3/21). We also observed that the count changes of total CTC, PD-L1
postive
CTC and PD-L1
high
CTC correlate quite well with disease outcome (P<0.001, P = 0.002 and 0.007, respectively). In addition, the abundance of PD-L1
high
CTCs at baseline had predicative significance for progression free survival (PFS).
Conclusions: We revealed that the abundance of PD-L1
high
CTCs at baseline might serve as a predictor to screen patients for PD-1/PD-L1 blockade therapies and measuring the dynamic changes of CTC could indicate the therapeutic response at early time.
Context.
Spatially resolved observations of the ionized and molecular gas are critical for understanding the physical processes that govern the interstellar medium (ISM) in galaxies. The observation ...of starburst systems is also important as they present extreme gas conditions that may help to test different ISM models. However, matched resolution imaging at ∼kpc scales for both ISM gas phases are usually scarce, and the ISM properties of starbursts still remain poorly understood.
Aims.
We aim to study the morpho-kinematic properties of the ionized and molecular gas in three dusty starburst galaxies at
z
= 0.12−0.17 to explore the relation between molecular ISM gas phase dynamics and the star-formation activity.
Methods.
We employ two-dimensional dynamical modelling to analyse Atacama Large Millimeter/submillimiter Array CO(1–0) and seeing-limited Spectrograph for INtegral Field Observations in the Near Infrared Paschen-
α
(Pa
α
) observations, tracing the molecular and ionized gas morpho-kinematics at ∼kpc-scales. We use a dynamical mass model, which accounts for beam-smearing effects, to constrain the CO-to-H
2
conversion factor and estimate the molecular gas mass content.
Results.
One starburst galaxy shows irregular morphology, which may indicate a major merger, while the other two systems show disc-like morpho-kinematics. The two disc-like starbursts show molecular gas velocity dispersion values comparable with those seen in local luminous and ultra luminous infrared galaxies but in an ISM with molecular gas fraction and surface density values in the range of the estimates reported for local star-forming galaxies. We find that these molecular gas velocity dispersion values can be explained by assuming vertical pressure equilibrium. We also find that the star-formation activity, traced by the Pa
α
emission line, is well correlated with the molecular gas content, suggesting an enhanced star-formation efficiency and depletion times of the order of ∼0.1−1 Gyr. We find that the star-formation rate surface density (Σ
SFR
) correlates with the ISM pressure set by self-gravity (
P
grav
) following a power law with an exponent close to 0.8.
Conclusions.
In dusty disc-like starburst galaxies, our data support the scenario in which the molecular gas velocity dispersion values are driven by the ISM pressure set by self-gravity and are responsible for maintaining the vertical pressure balance. The correlation between Σ
SFR
and
P
grav
suggests that, in these dusty starbursts galaxies, the star-formation activity arises as a consequence of the ISM pressure balance.
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