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We present a study of strong intervening absorption systems in the near-IR spectra of 31 luminous quasars at z > 5.7. The quasar spectra were obtained with Gemini GNIRS that provide continuous wavelength coverage from ∼0.9 to ∼2.5 μm. We detect 32 strong Mg ii doublet absorbers with rest-frame equivalent width Wr(λ2796) > 1.0 Å at 2.2 < z < 6.0. Each Mg ii absorber is confirmed by at least two associated Fe ii absorption lines in the rest-frame wavelength range of ∼1600–2600 Å. We find that the comoving line density (dN/dX) of the strong Fe ii -bearing Mg ii absorbers decreases toward higher redshift at z > 3, consistent with previous studies. Compared with strong Mg ii absorbers detected in damped Lyα systems at 2 < z < 4, our absorbers are potentially less saturated and show much larger rest-frame velocity widths. This suggests that the gas traced by our absorbers are potentially affected by galactic superwinds. We analyze the Hubble Space Telescope near-IR images of the quasars and identify possible associated galaxies for our strong absorbers. There are a maximum of two galaxy candidates found within 5″ radius of each absorber. The median F105W-band magnitude of these galaxy candidates is 24.8 mag, which is fainter than the L* galaxy luminosity at z ∼ 4. By using our observed dN/dX of strong Mg ii absorbers and galaxy candidates median luminosity, we suggest that at high redshift, strong Mg ii absorbers tend to have a more disturbed environment but smaller halo size than that at z < 1. [ABSTRACT FROM AUTHOR]

We present the study of a Lyman limit system (LLS) at zabs = 1.5441 toward quasar J134122.50+185213.9 observed with VLT X-shooter. This is a very peculiar system with strong C i absorption seen associated with a neutral hydrogen column density of log N(H i) (cm−2) = 18.10, too small to shield the gas from any external UV flux. The low-ionization absorption lines exhibit a simple kinematic structure consistent with a single component. Using CLOUDY models to correct for ionization, we find that the ionization parameter of the gas is in the range −4.5 < log U < –4.2 and the gas density –1.5 < log n(H) (cm−3) < –1.2. The models suggest that carbon is overabundant relative to iron, [C/Fe] > +2.2 at [Fe/H] ∼–1.6. Such a metal abundance pattern is reminiscent of carbon-enhanced metal-poor stars detected in the Galaxy halo. Metal enrichment by the first generation of supernovae provide a plausible explanation for the inferred abundance pattern in this system. [ABSTRACT FROM AUTHOR]

Highlights • Oral, intraperitoneal and intratumoral β-glucans inhibited S-180 tumor growth. • β-glucans targeted tumors and interacted with tumor cells. • β-glucans promoted CD4+ T cell differentiation and neutrophil infiltration. Graphical abstract Abstract β-glucans are polysaccharides comprising β-D-glucoses with various bioactivities. Herein, we extracted three β-glucans from Lentinus edodes with different sources and assessed their antitumor activities on a mice model with intragastric, intraperitoneal and intratumoral injection. Three polysaccharides were shown to have the same chemical structure of β-(1,3)-glucan with β-(1,6) branches, and exhibited S-180 tumor-suppressing ability with good safety. It was found that β-glucans up-regulated CD4+ T cell level in lymphoid organs decreased by tumor-burden, indicating promotion of immunomodulation. β-glucans targeted tumors in vivo even after oral or intraperitoneal injection. Furthermore, β-glucans not only targeted to lymphoid organs and increased CD4+ T cells number, but also enhanced CD4+ T cells and neutrophils populations in tumors. It was proposed that β-glucans promoted CD4+ T cell immunomodulation and neutrophils infiltration into tumors, leading to tumor growth inhibition. These findings reveal that β-glucans can be used as an effective agent for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Colorectal cancer is the third most common cancer in the world, and therapies with safety are in great need. In this study, the β-glucan isolated from Lentinus edodes was successfully fractionated into three fractions with different weight-average molecular weight (M w) by ultrasonic degradation and used for the treatment of colorectal cancer. In our findings, the β-glucan was successfully degraded with the M w decreased from 2.56 × 106 Da to 1.41 × 106 Da, exhibiting the triple helix structure without conformation disruption. The in vitro results indicate that β-glucan fractions inhibited colon cancer cell proliferation, induced colon cancer cell apoptosis, and reduced inflammation. The in vivo results based on Azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model demonstrate that the lower-molecular weight β-glucan fraction showed stronger anti-inflammatory and anti-colon cancer activities by reconstructing intestinal mucosal barrier, increasing short chain fatty acids (SCFAs) content, regulating metabolism of gut microbiota, and rebuilding the gut microbiota structure with the increased Bacteroides and the decreased Proteobacteria at the phylum level, as well as with the decreased Helicobacter and the increased Muribaculum at the genus level. These findings provide scientific basis for using the β-glucan to regulate gut microbiota as an alternative strategy in the clinical treatment of colon cancer. [Display omitted] [ABSTRACT FROM AUTHOR]

Yeast β-glucan has many formulations with different chemical structures, water solubility and purity. In particular, the purity of β-glucan in these formulations is variable and relatively low, contributing to different data on its biological activity. In this study, the major polysaccharide component in the crude Baker’s yeast polysaccharides coded as BBG with high purity of 99% was obtained, and its chemical structure was determined to be a linear β-(1,3)-glucan. It was found that BBG interacted with complement receptor 3 (CR3) and toll-like receptor 2 (TLR2) on the surface of macrophage-like RAW264.7 cells, and initiated activation of RAW264.7 cells characterized by significant production of tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein 1 (MCP-1). Additionally, activation of the nuclear factor kappaB p65 (NF-κB p65), c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) induced by BBG, were also observed, further confirming the stimulation of RAW264.7 cells by BBG. All these findings provided important scientific evidences for better understanding the molecular mechanism of action for the linear β-(1,3)-glucan in cells. [ABSTRACT FROM AUTHOR]

• β-glucan was confirmed to show weak tumor-targetability. • The tumor targetability of β-glucan was enhanced by aptamer conjugated to polydeoxyadenylic acid. • Versatility for different kinds of tumor cells and aptamer were confirmed. Herein the nucleic acid aptamers were attached to the polydeoxyadenylic acid (poly(dA)) tail for improving the tumor-targetability and cellular internalization of s-LNT/poly(dA) composite composed of two single chains of triple helical β -glucan lentinan (s-LNT) and one poly(dA) chain. The in vitro results demonstrate that the cellular uptake of s-LNT/poly(dA) composites in MCF-7 cancer cells was enhanced effectively after attaching the aptamer. The as-prepared fluorescin isothiocyanate (FITC)-labelled LNT (LNT-FITC) through grafting was used for tracing the enhanced tumor-targetability of the composites. As a result, the cellular internalization of the LNT-FITC into MCF-7 and 4T1 cancer cells was further increased by the aptamer conjugated to poly(dA). Meanwhile, the in vivo experiments further demonstrate more s-LNT/poly(dA)-aptamer composites were effectively accumulated at the tumor site compared with s-LNT alone. This work provides a novel strategy for fabricating triplex β -glucan as delivery vectors with active tumor-targetability. [ABSTRACT FROM AUTHOR]

The observations from the Dark Energy Spectroscopic Instrument (DESI) will significantly increase the numbers of known extremely metal-poor stars by a factor of ∼10, improving the sample statistics to study the early chemical evolution of the Milky Way and the nature of the first stars. In this paper we report follow-up observations with high signal-to-noise ratio of nine metal-poor stars identified during the DESI commissioning with the Optical System for Imaging and Low-Resolution Integrated Spectroscopy (OSIRIS) instrument on the 10.4 m Gran Telescopio Canarias. The analysis of the data using a well-vetted methodology confirms the quality of the DESI spectra and the performance of the pipelines developed for the data reduction and analysis of DESI data. [ABSTRACT FROM AUTHOR]

We report on a green procedure for the stabilization of selenium nanoparticles (SeNPs) by a naturally occurring β-glucan with triple helical conformation known as Lentinan (t-LNT) in water after denaturing into single chains (s-LNT) at 140 °C. The results demonstrated that the s-LNT can interact with SeNPs through Se O H interaction. Transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectra, UV/vis, X-ray diffraction (XRD) and dynamic light scattering (DLS) showed that s-LNT coated SeNPs to form a stable nano-composite Se/s-LNT, leading to good dispersion of SeNPs. Especially, the as-prepared Se/s-LNT composite in the solution could remain homogeneous and translucent for 30 days without any precipitates. Different size distribution of SeNPs was prepared by simply controlling the concentrations of selenite sodium and the corresponding reducing agent ascorbic acid. The size effect of SeNPs on anti-tumor activity was revealed that the SeNPs with more evenly particle size distribution show the higher anticancer activity. [ABSTRACT FROM AUTHOR]

The outward diffusion equation of the instantaneously released ion in pores of a porous layer was derived theoretically, and then applied for the study of oxygen ion diffusion in porous Fe which was generated by fast electrochemical reduction of solid Fe2O3 in molten CaCl2. The solid cathode was constructed by filling mixed Fe/Fe2O3 powders (8:1 in mass ratio) into cylindrical cavities in a Mo foil substrate. This fabricated mini porous electrode was subjected to the double-potential treatment with selected potentials according to the cyclic voltammetry (CVs) of Fe2O3. The lower potential of −0.7V (vs. quartz sealed Ag/AgCl) enabled fast reduction of solid Fe2O3, and instantaneous release of O2− ions into the pores of the generated porous Fe. During the standing time at −0.7V, outward O2− diffusion occurred, and the amount of O2− remaining in the porous electrode was determined by re-oxidation at a potential of 0.16V. The experimental outward diffusion of O2− was in good accord with the theoretical equation, consequently, the diffusion coefficients of O2− in CaCl2 contained in porous Fe were evaluated as 8.2×10−6, 9.1×10−6 and 1.0×10−5 cm2 s−1 at 1108, 1123 and 1138K respectively. These data followed the Arrhenius’ equation with diffusion activation energy of about 67.8kJmol−1. The whole work can provide a simple method for the study of diffusion in a porous electrode, and the designed ultrafast deoxidation of solid Fe2O3 may be also helpful to the present effort in developing iron metallurgy by molten salt electrolysis. [ABSTRACT FROM AUTHOR]

Broad-line regions (BLRs) in high-redshift quasars provide crucial information on chemical enrichment in the early universe. Here we present a study of BLR metallicities in 33 quasars at redshift 5.7 < z < 6.4. Using the near-IR spectra of the quasars obtained from the Gemini telescope, we measure their rest-frame UV emission-line flux and calculate flux ratios. We then estimate BLR metallicities with empirical calibrations based on photoionization models. The inferred median metallicity of our sample is a few times the solar value, indicating that the BLR gas had been highly metal enriched at z ∼ 6. We compare our sample with a low-redshift quasar sample with similar luminosities and find no evidence of redshift evolution in quasar BLR metallicities. This is consistent with previous studies. The Fe ii /Mg ii flux ratio, a proxy for the Fe/ α element abundance ratio, shows no redshift evolution as well, further supporting rapid nuclear star formation at z ∼ 6. We also find that the black hole massâ€"BLR metallicity relation at z ∼ 6 is consistent with the relation measured at 2 < z < 5, suggesting that our results are not biased by a selection effect due to this relation. [ABSTRACT FROM AUTHOR]

We report the detection of the host galaxy of a damped Lyα system (DLA) with log N(H i) [cm−2] = 21.0 ± 0.10 at z ≈ 3.0091 toward the background quasar SDSS J011852+040644 using the Palomar Cosmic Web Imager at the Hale (P200) telescope. We detect Lyα emission in the dark core of the DLA trough at a 3.3σ confidence level, with Lyα luminosity of LLyα = (3.8 ± 0.8) × 1042 erg s−1, corresponding to a star formation rate of ≳2 M⊙ yr−1 (considering a lower limit on Lyα escape fraction) as typical for Lyman break galaxies at these redshifts. The Lyα emission is blueshifted with respect to the systemic redshift derived from metal absorption lines by 281 ± 43 km s−1. The associated galaxy is at very small impact parameter of ≲12 kpc from the background quasar, which is in line with the observed anticorrelation between column density and impact parameter in spectroscopic searches tracing the large-scale environments of DLA host galaxies. [ABSTRACT FROM AUTHOR]

Timely and accurate detection of SARS-CoV-2 variants of concern (VOCs) is urgently needed for pandemic surveillance and control. Great efforts have been made from a mass of scientists in increasing the detection sensitivity and operability, and reducing the turn-around time and cost. Here, we report a nucleic acid testing-based method aiming to detect and discriminate SARS-CoV-2 mutations by combining RT-RPA and CRISPR-Cas12a detecting assays (RRCd). With a detection limit of 10 copies RNA/reaction, RRCd was validated in 194 clinical samples, showing 89% positive predictive agreement and 100% negative predictive agreement, respectively. Critically, using specific crRNAs, representatives of single nucleotide polymorphisms and small deletions in SARS-CoV-2 VOCs including N501Y, T478K and ΔH69-V70 were discriminated by RRCd, demonstrating 100% specificity in clinical samples with C t < 33. The method completes within 65 min and could offer visible results without using any electrical devices, which probably facilitate point-of-care testing of SARS-CoV-2 variants and other epidemic viruses. • A SARS-CoV-2 detection method (RRCd) was developed. • RRCd can detect and discriminate SARS-CoV-2 mutations. • RRCd was validated in 194 clinical samples showing high accuracy and sensitivity. • RRCd is independent of bulk and electrical devices. [ABSTRACT FROM AUTHOR]