ABSTRACT
Five fast radio bursts (FRBs), including three apparently non-repeating ones, FRB 180924, FRB 181112, and FRB 190523, and two repeaters, FRB 121102 and FRB 180916.J0158+65, have already been ...localized so far. We apply a method developed recently by us to these five localized FRBs to give a cosmology-insensitive estimate of the fraction of baryon mass in the intergalactic medium, fIGM. Using the measured dispersion measure (DM) and luminosity distance dL data (inferred from the FRB redshifts and dL of Type Ia supernovae at the same redshifts) of the five FRBs, we constrain the local $f_{\rm IGM} = 0.84^{+0.16}_{-0.22}$ with no evidence of redshift dependence. This cosmology-insensitive estimate of fIGM from FRB observations is in excellent agreement with previous constraints using other probes. Moreover, using the three apparently non-repeating FRBs only we get a little looser but consistent result: $f_{\rm IGM} = 0.74^{+0.24}_{-0.18}$. In these two cases, reasonable estimations for the host galaxy DM contribution (DMhost) can be achieved by modelling it as a function of star formation rate. The constraints on both fIGM and DMhost are expected to be significantly improved with the rapid progress in localizing FRBs.
In this study, anisotropic heterogeneous geotechnical fields are characterized using random field theory, in which five basic patterns of material anisotropy are simulated including isotropy, ...transverse anisotropy, rotated anisotropy, general anisotropy, and general rotated anisotropy. Theoretical formulations of scale of fluctuation as a function of directional angle are developed for the five basic patterns of anisotropy through modifications of the coordinate system. These formulations of scale of fluctuation are identical for different correlation structures. Correlation functions for the exponential and Gaussian correlation structures are also derived. The matrix decomposition method is then applied to generate anisotropic random fields. The generated random field correlated data are verified with two realizations of transverse anisotropy and general rotated anisotropy random fields. Test values of the sample mean, sample deviation, and scales of fluctuation in six directions match well with the prescribed values. This study provides a technique to characterize inherent geotechnical variability and anisotropy, which is required to realistically simulate complex geological properties in engineering reliability analysis and design.
Natural soils often exhibit an anisotropic fabric pattern as a result of soil deposition, weathering or filling. This study aims to investigate the effects of spatially variable anisotropic soil ...fabric in a slope on its safety factor and failure mechanisms, and to identify the critical fabric orientation that is most unfavorable to the slope stability. The strength properties of colluvium (i.e., cohesion and friction angle) are modeled as random fields under two conditions (i.e., independent and negatively correlated). The study reveals that there exists a critical fabric orientation at 30° at which the mean factor of safety is the lowest and the probability of failure is the highest. The negative cross-correlation between soil shear strength properties leads to a significantly lower probability of failure, compared to the independent case. The highest proportion of deep failure mechanism is also identified at the same fabric orientation of 30°. The identified critical fabric orientation is gentler than the slope inclination. This study suggests that the conventional understanding that stratification parallel to the slope surface appears to be the most unfavorable condition leading to the lowest safety level does not hold for spatially varying soils.
Fly ash and red mud have been employed as adsorbents for the removal of a typical basic dye, methylene blue, from aqueous solution. Heat treatment and chemical treatment have also been applied to the ...as-received fly ash and red mud samples. It is found that fly ash generally shows higher adsorption capacity than red mud. The raw fly ash and red mud show adsorption capacity at 1.4×10
−5 and 7.8×10
−6
mol/g, respectively. Heat treatment reduces the adsorption capacity for both fly ash and red mud but acid treatment by HNO
3 induces a different effect on fly ash and red mud. Nitric acid treatment results in an increase in adsorption capacity of fly ash (2.4×10
−5
mol/g) while it decreases the adsorption capacity for red mud (3.2×10
−6
mol/g). The adsorption data have been analysed using Langmuir, Freundlich and Redlich–Peterson isotherms. The results indicate that the Redlich–Peterson model provides the best correlation of the experimental data. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. For fly ash and red mud, adsorption of methylene blue is endothermic reaction with
Δ
H
0
at 76.1 and 10.8
kJ/mol, respectively.
Lasing is observed from carbon nanodots (C‐dots) dispersed into a layer of poly(ethylene glycol) coated on the surface of optical fibers under 266 nm optical excitation. This is due to the ...enhancement of photoluminescence intensity via the esterification of carboxylic groups of the C‐dots, and the formation of high‐Q cylindrical microcavities to support second‐type whispering gallery modes.
•Mesoporous titania spheres were prepared using CS/PVA hydrogel beads as a template.•The titania spheres prepared was mesoporous structure.•The photocatalytic activity of the mesoporous titania ...spheres calcined at 500°C was highest.
Mesoporous titania spheres were prepared by modified sol–gel method using chitosan/poly(vinyl alcohol) hydrogel beads as a template. Effects of calcination temperature on physical parameters were investigated by X-ray diffraction (XRD), N2 adsorption–desorption, Fourier transform infrared (FT-IR) spectra, thermogravimetry and differential thermal analyses (TG-DTA), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The photocatalytic activity of mesoporous titania spheres prepared was also evaluated by photocatalytic degradation of phenol as a model molecule under UV irradiation. With increasing calcination temperature, average crystallite size and pore size increased. In contrast, Brunauer–Emmett–Teller (BET) specific surface areas, porosity and pore volumes steadily decreased. Results of characterization proved that prepared titania spheres with highly organized pores were mesoporous structure. The photocatalytic activity of mesoporous titania spheres calcined at 500°C was more effective than those calcined at other temperatures, which were attributed to the porous structure, large BET surface area, crystalline, and smaller crystallite size. This work may provide new insights into the preparation of novel mesoporous titania spheres and further practical applications in the treatment of wastewater.
The emergence of pandemic H1N1/2009 influenza demonstrated that pandemic viruses could be generated in swine. Subsequent reintroduction of H1N1/2009 to swine has occurred in multiple countries. ...Through systematic surveillance of influenza viruses in swine from a Hong Kong abattoir, we characterize a reassortant progeny of H1N1/2009 with swine viruses. Swine experimentally infected with this reassortant developed mild illness and transmitted infection to contact animals. Continued reassortment of H1N1/2009 with swine influenza viruses could produce variants with transmissibility and altered virulence for humans. Global systematic surveillance of influenza viruses in swine is warranted.
The human gene
Ptpn11, which encodes the tyrosine phosphatase Shp2, may act as a proto-oncogene because dominantly activating mutations have been detected in several types of leukemia. Herein we ...report a tumor-suppressor function of Shp2. Hepatocyte-specific deletion of Shp2 promotes inflammatory signaling through the Stat3 pathway and hepatic inflammation/necrosis, resulting in regenerative hyperplasia and development of tumors in aged mice. Furthermore, Shp2 ablation dramatically enhanced diethylnitrosamine (DEN)-induced hepatocellular carcinoma (HCC) development, which was abolished by concurrent deletion of Shp2 and Stat3 in hepatocytes. Decreased Shp2 expression was detected in a subfraction of human HCC specimens. Thus, in contrast to the leukemogenic effect of dominant-active mutants,
Ptpn11/Shp2 has a tumor-suppressor function in liver.
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► Hepatic deletion of
Ptpn11 promotes hepatocarcinogenesis ► Detection of deficient/low Shp2 expression in human HCC specimens ►
Ptpn11/Shp2 may act as either tumor promoter or suppressor ► Stat3 has both pro-oncogenic and anti-oncogenic effects in HCC
We carry out a project to independently measure the distances of supernova remnants (SNRs) in the first quadrant of the Galaxy. In this project, red clump (RC) stars are used as standard candles and ...extinction probes to build the optical extinction (AV)-distance(D) relation in each direction of extinction-known SNRs. The distances of 15 SNRs are determined. Among them, the distances of G65.8-0.5, G66.0-0.0, and G67.6+0.9 are given for the first time. We also obtain 32 upper/lower limits of distances, and the distances to G5.7-0.1, G15.1-1.6, G28.8+1.5, and G78.2+2.1 are constrained. Most of the distances measured by the RC method are consistent with previous results. The RC method provides independent access to the distances of SNRs.
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