Search

Food hoarding is prevalent during the COVID-19 pandemic. To investigate the mechanism of urban consumers' food hoarding behaviors, we categorize hoarding motives into rational and irrational ones. Using random online survey samples from three cities in China, we employ the multivariate probit model to investigate the rational and irrational motives on food hoarding behavior. Our results confirmed the existence of both rational and irrational food hoarding, and also found factors attributing to the different buying behaviors. The amount of food at hand and the expectation on the infection possibility of COVID-19 are two major factors affecting rational hoarding. Bad mood and herd psychology are factors contributing to panic buying. This study provides an empirical evidence to support intervention policies aiming at mitigating panic buying behavior.

Heterogeneity in either chemically or microbiologically induced carbonate-based ground improvement methods is a major obstacle in engineering application. Spectral induced polarization (SIP), an innovative and nondestructive method, which has demonstrated promise in monitoring microbial activity, was used in this study to monitor enzyme induced carbonate precipitation (EICP). The complex conductivities, together with the shear wave velocities (Vs), of an EICP modified sand were monitored using a self-developed spectral induced polarization–bender element column. The mean precipitate size was calculated by relaxation time (τ) and the Schwarz equation. The precipitate contents were calculated by cumulative gamma distribution function on the global polarization magnitude (mn) with R2 = 0.989. The stiffness of the enhanced geomaterial, in terms of Vs, correlates to mn with a cumulative lognormal distribution function with R2 = 0.967. Contact cementation was postulated as the dominant association pattern. The possible mechanism for this may be the formation of eddies and the nucleation of CaCO3 crystals during precipitation. The results suggest that SIP can be used as an effective nondestructive monitoring tool to assess the stiffness of geomaterials.

Visible light-promoted dearomative [2 + 2] cycloaddition of indole derivatives tethered with olefins at the N1 position has been considered thermodynamically unfeasible due to the high triplet exci...

Infrared quasi-stellar objects (IR QSOs) are a rare subpopulation selected from ultraluminous infrared galaxies (ULIRGs) and have been regarded as promising candidates of ULIRG-to-optical QSO transition objects. Here we present NOEMA observations of the CO(1-0) line and 3 mm continuum emission in an IR QSO IRAS F07599+6508 at $z=0.1486$, which has many properties in common with Mrk 231. The CO emission is found to be resolved with a major axis of $\sim$6.1 kpc that is larger than the size of $\sim$4.0 kpc derived for 3 mm continuum. We identify two faint CO features located at a projected distance of $\sim$11.4 and 19.1 kpc from the galaxy nucleus, respectively, both of which are found to have counterparts in the optical and radio bands and may have a merger origin. A systematic velocity gradient is found in the CO main component, suggesting that the bulk of molecular gas is likely rotationally supported. Based on the radio-to-millimeter spectral energy distribution and IR data, we estimate that about 30$\%$ of the flux at 3 mm arises from free-free emission and infer a free-free-derived star formation rate of 77 $M_\odot\ {\rm yr^{-1}}$, close to the IR estimate corrected for the AGN contribution. We find a high-velocity CO emission feature at the velocity range of about -1300 to -2000 km s$^{-1}$. Additional deep CO observations are needed to confirm the presence of a possible very high-velocity CO extension of the OH outflow in this IR QSO., 20 pages, 13 figures; accepted for publication in ApJ

Background Nano-drug delivery systems show considerable promise for effective cancer therapy. Polymeric micelles have attracted extensive attention as practical nanocarriers for target drug delivery and controlled drug delivery system, however, the distribution of micelles and the release of the drug are difficult to trace in cancer cells. Therefore, the construction of a redox-sensitive multifunctional drug delivery system for intelligent release of anticancer drugs and simultaneous diagnostic imaging and therapy remains an attractive research subject. Results To construct a smart drug delivery system for simultaneous imaging and cancer chemotherapy, mPEG-ss-Tripp was prepared and self-assembled into redox-sensitive polymeric micelles with a diameter of 105 nm that were easily detected within cells using confocal laser scanning microscopy based on aggregation-induced emission. Doxorubicin-loaded micelles rapidly released the drug intracellularly when GSH reduced the disulfide bond. The drug-loaded micelles inhibited tumor xenografts in mice, while this efficacy was lower without the GSH-responsive disulfide bridge. These results establish an innovative multi-functional polymeric micelle for intracellular imaging and redox-triggered drug deliver to cancer cells. Conclusions A novel redox-sensitive drug delivery system with AIE property was constructed for simultaneous cellular imaging and intelligent drug delivery and release. This smart drug delivery system opens up new possibilities for multifunctional drug delivery systems.

Soil and groundwater contamination with lead (Pb) poses serious challenges for the environment. Activated carbon (AC) and biochar have huge potential application in the in-situ remediation processes through permeable reactive barriers (PRB). Spectral induced polarization (SIP) technique recently showed promises in nondestructively monitoring the spatio-temporal characteristics of physical, chemical and biological processes in porous media. In this study SIP technique was used for monitoring Pb remediation by AC and biochar in column scale. The calculated characteristic grain/pore size evolutions from SIP signals on AC, agreed well with the size of precipitates measured by SEM and mercury intrusion porosimetry (MIP) methods. The content increment process of the retained Pb on AC was also recorded via the magnitude increment of the imaginary conductivity. The mechanisms of Pb-AC and Pb-biochar interactions were investigated using SEM-EDS, TEM, FTIR, XRD, and XPS measurements. It showed that AC immobilizes through physical adsorption and precipitation, whereas complexation with functional groups is the remediation mechanism for biochar. Furthermore, the observed SIP responses of both AC and biochar are two orders of magnitude higher than those of typical natural soils or silica materials. This distinct difference is an additional advantage for the field application of SIP technique in PRB scenarios.

PurposeThis research is to examine the impact of online channels on food stockpile behavior.Design/methodology/approachIn this study, we use bivariate probit models to empirically investigate the impact of online purchasing channels on Chinese urban consumer food hoarding behaviors with random survey samples.FindingsResults show that fresh food e-commerce channels are more likely to be associated with panic stockpile behaviors due to higher likelihood of supply shortages than offline channels with government assistance in logistic management. In contrast, community group buy, another format of e-commerce, appears superior in satisfying the consumer needs and easing the panic buying perception.Practical implicationsIt suggests that online channels may have diverse impacts on consumers' panic stockpiling behaviors during the extreme situations. Online channels need to develop efficient supply chains to be more resilient to extreme situations and the government shall recognize the increasing share of the online channels together with traditional offline channels when implementing supporting policies.Social implicationsWith ever increasing share of online channels, it is imperative in terms of policy implications to understand how would online channels affect hoarding behavior.Originality/valueWe are the first study in online shopping's impact on food stockpile during pandemics using a random sample. Although food stockpile behavior at times of emergency have been investigated in many literature, there are no empirical studies on the impact of online channels on stockpile behaviors under extreme situations. Unlike disasters that immediately impact every entity in supply chains covering producers, vendors, distribution centers and retailers, pandemics did not render supply chains affected immediately, but rather increase consumers' willingness to shop online to avoid virus. Thus, Covid-19 provides a natural experiment to investigate the online channels' impact on stockpile behavior.

In this paper, we put forward a new secret sharing scheme. First, we give the mutually unbiased bases on the p2-dimensional quantum system where p is an odd prime number, and then we construct the corresponding unitary transformation based on the properties of these mutually unbiased bases. Second, we construct a (N, N) threshold secret sharing scheme by using unitary transformation between these mutually unbiased bases. At last, we analyze the scheme’s security by several ways, for example, intercept-and-resend attack, entangle-and-measure attack, trojan horse attack, and so on. Using our method, we construct a single-particle quantum protocol involving only one qudit, and the method shows much more scalability than other schemes.

Background Frequent injection of high-dose methylprednisolone (MP) is used to treat spinal cord injury (SCI), but free MP is associated with various side effects and its water solubility is low, limiting potential dosing regimes and administration routes. Albumin-based nanoparticles, which can encapsulate therapeutic drugs and release cargo in a controlled pattern, show high biocompatibility and low toxicity. The Nogo protein, expressed on the surface of oligodendrocytes, can inhibit axonal growth by binding with the axonal Nogo receptor (NgR). Peptide NEP1-40, an NgR antagonist, can bind specifically to Nogo, significantly improving functional recovery and axon growth in the corticospinal tract. Therefore, we hypothesized that delivering MP within nanoparticles decorated with NEP1-40 could avoid the disadvantages of free MP and enhance its therapeutic efficacy against SCI. Results We used human serum albumin to prepare MP-loaded NPs (MP-NPs), to whose surface we conjugated NEP1-40 to form NEP1-40-MP-NPs. Transmission electron microscopy indicated successful formation of nanoparticles. NEP1-40-MP-NPs were taken up significantly better than MP-NPs by the Nogo-positive cell line RSC-96 and were associated with significantly higher Basso–Beattie–Bresnahan locomotor scores in rats recovering from SCI. Micro-computed tomography assay showed that NEP1-40-MP-NPs mitigated SCI-associated loss of bone mineral density and accelerated spinal cord repair. Conclusions NEP1-40-MP-NPs can enhance the therapeutic effects of MP against SCI. This novel platform may also be useful for delivering other types of drugs. Electronic supplementary material The online version of this article (10.1186/s12951-019-0449-3) contains supplementary material, which is available to authorized users.

Squid is an important seafood resource in Asian and European countries. Due to the different nutritional and market values of various squid species, substitutions between species often occur for higher profits. In this study, a species-specific PCR assay was developed for genetic discrimination of eight commercially important squid species from each other, based on the single nucleotide polymorphism (SNP) sites exploited from mitochondrial cytochrome oxidase subunit I (COI) sequences. The introduction of additional mismatches both in the forward and reverse primers ensured absolute allele specificity despite a moderate annealing temperature. The eight squid species can be clearly discriminated from each other by simplex PCR, and the developed multiplex species-specific PCR assay can detect 1% of intentional adulteration of non-target squid species into target species down to the 0.1 ng level of template DNA without PCR optimization. Therefore, the present study provides a simple and reliable genetic assay for identification of squid origin either in single or mixed species, and the developed assay will be useful in correct labeling and quality control of squid products.

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disease. Long-term, high-dose glucocorticoid therapy can be used to treat the disease, but the fact that the drug distributes systemically can give rise to severe adverse effects. Here we develop a targeted system for treating RA in which the glucocorticoid prednisolone (PD) is encapsulated within solid lipid nanoparticles (SLNs) coated with hyaluronic acid (HA), giving rise to HA-SLNs/PD. HA binds to hyaluronic receptor CD44, which is over-expressed on the surface of synovial lymphocytes, macrophages and fibroblasts in inflamed joints in RA. As predicted, HA-SLNs/PD particles accumulated in affected joint tissue after intravenous injection into mice with collagen-induced arthritis (CIA), and HA-SLNs/PD persisted longer in circulation and preserved bone and cartilage better than free drug or drug encapsulated in SLNs without HA. HA-SLNs/PD reduced joint swelling, bone erosion and levels of inflammatory cytokines in serum. These results suggest that encapsulating glucocorticoids such as PD in HA-coated SLNs may render them safe and effective for treating inflammatory disorders.

Upconversion core–shell nanoparticles have attracted a large amount of attention due to their multifunctionality and specific applications. In this work, based on a NaGdF4 sub-10 nm ultrasmall nanocore, a series of core–shell upconversion nanoparticles with uniform size doped with Yb3+, Er3+ and NaDyF4 shells with different thicknesses were synthesized by a facile sequential growth process. NaDyF4 coated upconversion luminescent nanoparticles showed an obvious fluorescence quenching under excitation at 980 nm as a result of energy resonance transfer between Yb3+, Er3+ and Dy3+. NaGdF4:Yb,Er@NaDyF4 core–shell nanoparticles with ultrathin layer shells exhibited a better T1-weighted MR contrast.

A microporous metal-organic framework (Ga 2 (OH) 4 (C 9 O 6 H 4 ) or MIL-124) with one extra uncoordinated carbonyl group has been synthesized by the hydrothermal approach, then encapsulating the Eu 3+ cations into the channels as postsynthetic modification (PSM). The as-synthesized MIL-124@Eu 3+ exhibits the strong luminescence of Eu 3+ ion originated from efficient energy transfer from the ligand, which can sense the biological metabolites of BTEX (toluene, xylene and ethylbenzene) in urine. The results show a highly efficient recyclable luminescent probe MIL-124@Eu 3+ to detect of biomarkers of BTEX with excellent sensitivity and quick response time. Taken together, the study suggests that the MIL-124@Eu 3+ can be a great candidate for the direct detection of metabolites of BTEX in urine. A rapid test paper can be developed based on these findings.

Ultrathin KMnF 3 nanowires with several nanometers in diameter have been synthesized successfully by a high temperature organic solution method for the first time. The morphologies and size of the as-prepared products were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS), respectively. Ultrathin KMnF 3 nanowires and nanoparticles can be selectively synthesized by adjusting the amount of oleylamine. Moreover, the magnetic properties have been investigated using a vibrating sample magnetometer (VSM). Magnetic hysteresis loops revealed that the as-prepared KMnF 3 nanowires exhibit stronger paramagnetic performance than that of as-prepared nanoparticles.

We present ALMA observations of the CO(1-0) line and 3-mm continuum emission in eight ultraluminous infrared (IR) quasi-stellar objects (QSOs) at z = 0.06-0.19. All eight IR QSO hosts are clearly resolved in their CO molecular gas emission with a median source size of 3.2 kpc, and seven out of eight sources are detected in 3-mm continuum, which is found to be more centrally concentrated with respect to molecular gas with sizes of 0.4-1.0 kpc. Our observations reveal a diversity of CO morphology and kinematics for the IR QSO systems which can be roughly classified into three categories, rotating gas disk with ordered velocity gradient, compact CO peak with disturbed velocity, and multiple CO distinct sources undergoing a merger between luminous QSO and a companion galaxy separated by a few kpc. The molecular gas in three of IR QSO hosts are found to be rotation-dominated with the ratio of the maximum rotation velocity to the local velocity dispersion of $V_{\rm rot}/\sigma=4-6$. Basic estimates of the dynamical masses within the CO-emitting regions give masses between $7.4\times10^9$ and $6.9\times10^{10}$ $M_\odot$. We find an increasing trend between BH mass accretion rate and star formation rate (SFR) over three orders of magnitude in far-IR luminosity/SFR, in line with the correlation between QSO bolometric luminosity and SF activity, indicative of a likely direct connection between AGN and SF activity over galaxy evolution timescales., Comment: 25 pages, 7 figures, and 4 tables; accepted for publication in ApJ

In this seminal work, we introduce the role of institutions and knowledge spillovers in reversing the Dutch disease phenomena and providing a basis for future work. Hence, this study fills the existing literature gap by including institutional quality and knowledge spillovers in testing the Dutch disease hypothesis in Brazil, Russia, India, China, South Africa (BRICS) countries. We analyzed the combined effect of FDI spillovers and remittances inflow on the real effective exchange rate from 1989 to 2019. There is a cointegration relationship among the variables in all aggregate sample models and all the BRICS country's cross-sections. We find that knowledge spillover and institutional quality are important factors contributing to the appreciation of the real effective exchange rate in BRICS countries. This study suggests that for reversing Dutch disease phenomena, BRICS countries need to improve their institutions regarding policy implications. Quality institutions will facilitate remittances to be absorbed into investment activities. Hence, the development of institutions will bring more significant economic growth in the short-run and the long run.

It is a significant challenge to develop nanoscale magnetic resonance imaging (MRI) contrast agents with high performance of relaxation. In this work, Gd3+-doped CaF2-based core–shell nanoparticles (CaF2:Yb,Er@CaF2:Gd) of sub-10 nm size were controllably synthesized by a facile sequential growth method. The as-prepared hydrophilic CaF2:Yb,Er@CaF2:Gd nanoparticles modified using PEG-PAA di-block copolymer benefited from the presence of Gd only in the outer CaF2 layer of the nanoparticles, which exhibited r1 as high as 21.86 mM−1 s−1 under 3.0 T, seven times as high as that of commercially used gadopentetate dimeglumine (Gd-DTPA). Low cytotoxicity, no hemolysis phenomenon and no potential gadolinium ion leakage phenomenon of the hydrophilic CaF2:Yb,Er@CaF2:Gd nanoparticles have been observed and confirmed. Clear vascular details can be observed in magnetic resonance angiography and obvious MR signal of 4T1 tumor area could be significantly improved by intravenous injection of the hydrophilic CaF2:Yb,Er@CaF2:Gd nanoparticles at a low dosage in mice. A series of in vivo biological safety evaluations confirmed the good biocompatibility of the hydrophilic CaF2:Yb,Er@CaF2:Gd nanoparticles, which might be employed in clinical blood pool imaging and tumor diagnosis as a safe and efficient MRI probe.

As the implications of reactive oxygen species (ROS) are elucidated in many diseases, ROS-responsive nanoparticles are attracting great interest from researchers. In this work, a ROS sensitive thioketal (TK) moiety with a π-conjugated structure was introduced into biodegradable methoxy poly(ethylene glycol)-thioketal-poly(ε-caprolactone)mPEG-TK-PCL micelles as a linker, which was designed to speed up the drug release and thus enhance the therapeutic efficacy. The micelle showed a high drug loading content of 12.8% and excellent stability under physiological conditions because of the evocation of π-π stacking and hydrophobic interactions with the anticancer drug doxorubicin (DOX). The polymeric micelle presented a better drug carrier capacity and higher in vitro anticancer efficacy towards cancer cells. The in vivo study showed that DOX-loaded mPEG-TK-PCL micelles displayed lower toxicity towards normal cells and remarkably enhanced antitumor efficacy. This research provides a way to design potential drug carriers for efficient cancer chemotherapy.

Surface complexation models are widely used with batch adsorption experiments to characterize and predict surface geochemical processes in porous media. In contrast, the spectral induced polarization (SIP) method has recently been used to non-invasively monitor in situ subsurface chemical reactions in porous media, such as ion adsorption processes on mineral surfaces. Here we compare these tools for investigating surface site density changes during pH-dependent sodium adsorption on a silica gel. Continuous SIP measurements were conducted using a lab scale column packed with silica gel. A constant inflow of 0.05 M NaCl solution was introduced to the column while the influent pH was changed from 7.0 to 10.0 over the course of the experiment. The SIP measurements indicate that the pH change caused a 38.49 ± 0.30 μS cm− 1 increase in the imaginary conductivity of the silica gel. This increase is thought to result from deprotonation of silanol groups on the silica gel surface caused by the rise in pH, followed by sorption of Na+ cations. Fitting the SIP data using the mechanistic model of Leroy et al. (Leroyet al., 2008), which is based on the triple layer model of a mineral surface, we estimated an increase in the silica gel surface site density of 26.9 × 1016 sites m− 2. We independently used a potentiometric acid–base titration data for the silica gel to calibrate the triple layer model using the software FITEQL and observed a total increase in the surface site density for sodium sorption of 11.2 × 1016 sites m− 2, which is approximately 2.4 times smaller than the value estimated using the SIP model. By simulating the SIP response based on the calibrated surface complexation model, we found a moderate association between the measured and estimated imaginary conductivity (R2 = 0.65). These results suggest that the surface complexation model used here does not capture all mechanisms contributing to polarization of the silica gel captured by the SIP data.

Three novel transition-metal coordination polymers {[Mn 2 (qptc 4 − )(1,4-bib)(H 2 O) 2 ]·2H 2 O} n ( 1 ), [Cd 2 (qptc 4 − )(phen) 2 ] n ( 2 ) and [Ni 2 (qptc 4 − )(1,4-bib)(H 2 O) 8 ] n ( 3 ) (H 4 qptc = 1,1′:4′,1″:4″,1‴-quterphenyl-2,4,2‴,4‴-tetracarboxylic acid, 1,4-bib = 1,4-bis(1-imidazolyl) benzene and phen = 1.10-phenanthroline), have been synthesized hydrothermally, and characterized by single crystal X-ray diffraction, elemental analysis (EA), infrared spectroscopy (IR), and powder X-ray diffraction (PXRD). The single-crystal X-ray diffraction analysis shows that these polymers exhibit different types of structures, featuring 3D network ( 1 and 2 ) and a 1D chain ( 3 ) by varying reaction conditions. Polymer 1 consists of infinite 2D networks pillared by 1,4-bib bridging ligand, giving a 4,6-connected porous 3D framework with the point symbol (4 4 .6 10 .8)(4 4 .6 2 ). Polymer 2 is a 4,4-connected binodal 3D network with the topological type of lvt. Polymer 3 possesses a 1D zigzag chain structure, and the adjacent chains are further connected into a 3D supramolecular by non-covalent interactions involving contributions from carboxyl-water clusters. The magnetic susceptibility of polymers 1 and 3 , and fluorescent property of polymer 2 was also investigated.

One chiral Cu(I) metal–organic framework {[Cu(DCI)]·0.1Cyc·0.45Nbenz}n (1) (HDCI = 4,5-dicyanoimidazole, Cyc = cyclohexanol, Nbenz = nitrobenzene), was obtained under solvothermal condition. Complex 1 presents a 3D chiral porous framework with 38.2% porosity. The 3D metal–organic framework can be regarded as a PtS net with the vertex symbol of {42.84}. The gas adsorption/desorption experiments of complex 1 have been measured at 77 K. Moreover, the CD spectrum and photoluminescent behavior of complex 1 have been studied.

This study analyses the role of green growth in promoting a sustainable environment. In literature, the empirical and theoretical examination on the role of green growth in carbon dioxide (CO2) emissions is missing, especially in combination with other factors, i.e., human capital index, environment-related taxes and development of environment-related technologies. This study investigates the role of environmentally adjusted multifactor productivity growth (i.e. green growth) on CO2 emissions for G7 countries from 1991 to 2017. The study utilizes second generation panel data method(s), i.e. Cross-Sectionally Augmented Auto-regressive Distributive lag (CS-ARDL) model. The outcomes of theoretical and empirical findings indicate that both linear and non-linear term for green growth reduces CO2 emissions. Also, environmental tax, human capital and renewable energy use are found to decrease CO2 emissions. The impact of GDP growth both in short-run and long-run is environment depletion. However, our result supports the theoretical notion that green growth sustains environment quality. We obtained consistent results from panel causality test. Our results may further strengthen the belief of policymakers in developed countries on the promotion of green growth.

Monodisperse sub-10 nm core–shell nanocrystals have been extensively studied owing to their important applications in catalysis, bioimaging, nanomedicine, and so on. In this work, an amorphous shell component crystallization strategy has been proposed to prepare high quality sub-10 nm NaYF4:Yb/Er@NaGdF4 core–shell nanocrystals successfully via a sequential growth process. The dynamic light scattering technique has been used to investigate the secondary nucleation and growth process forming the core–shell nanocrystals. The size and morphology evolution of the core–shell nanocrystals reveals that the secondary nucleation of the shell component is unavoidable after hot-injecting the shell precursor at high temperatures, which was followed by dissolution and recrystallization (an Ostwald ripening process) to partially produce the core–shell nanocrystals. The present study demonstrates that the size of seed nanocrystals and the injection temperature of the shell component precursor play a vital role in the for...

Ouyang et al. proposed an (n, n) threshold quantum secret sharing scheme, where the number of participants was limited to n = 4k + 1, k ∈ Z+, and the security evaluation of the scheme was carried out accordingly. In this paper, we introduce an (n, n) threshold quantum secret sharing scheme for the number of participants n in any case (n ∈ Z+ ). The scheme is based on a quantum circuit, which consists of Clifford group gates and Toffoli gates. We study the properties of the quantum circuit in this paper and use the quantum circuit to analyze the security of the scheme for dishonest participant attack.

The topographic cues of the extracellular matrix may have significant effects upon cellular behavior, such as adhesion, spreading, migration, proliferation, differentiation, and in particular, morphology and orientation. In this study, we examined the effects of microgrooved collagen membrane (MCM) on mesenchymal stem cell (MSC) behavior. The MCM (9 μm in periodicity, and 1-2 μm in depth) was fabricated on an untreated (nonpolar) and smooth polystyrene substrate, based on the absorption and self-assembly properties of collagen on the polystyrene substrate. Methyl thiazolyl tetrazolium assay revealed that cell proliferation on the MCM was enhanced compared with the smooth collagen membrane at day 2. Qualitative observation of MSC behavior using confocal laser scanning microscopy and scanning electron microscopy showed that MSCs grew with a highly elongated morphology and were aligned strictly along the direction of the microgrooves. Additionally, scanning electron microscopy revealed the oriented cells produced a collagenous matrix on the MCM that had a preferential orientation, whereas the collagenous matrix produced by randomly oriented MSCs on the smooth collagen membrane was disorganized. Future studies should investigate the fabrication of oriented topographical substrates, based on the natural biomaterial collagen, to guide cell alignment and oriented growth along definite directions. These substrates may help produce aligned collagenous matrices that could have good potential for the production of tissue substitutes.

Upconversion nanoparticles/semiconductor nanocomposites have received intense interest in the past two decades. In this work, we demonstrated a facile electrospinning technique and a hydrothermal-assisted crystallization process to fabricate upconversion nanoparticles (UCNPs)/CdS/TiO2 nanofibers successfully. Polyvinylpyrrolidone (PVP, Mw ≈ 1 300 000) has been selected as the polymer matrix and tetrabutyl titanate (TBT, 99.0%) was used as the titanium source. The morphologies and phase of the as-prepared samples have been studied using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Experimental results revealed that the polymer matrix (PVP) can be dissolved and removed completely under hydrothermal conditions. In addition, the crystalline phase of TiO2 was also achieved under hydrothermal conditions. The as-prepared composite nanofibers are hundreds of micrometers in length and 650 nm in diameter and show weak upconversion fluorescence under the excitation of near-infrared light (980 nm), indicating the high energy transfer efficiency between upconversion nanoparticles and semiconductors. As expected, the UCNPs/CdS/TiO2 nanofibers may have enhanced photocatalytic performance as they make full use of solar energy using UCNPs as nanotransducers for infrared (IR) light.

A facile strategy was put forward to fabricate highly luminescent metal–organic frameworks (MOFs) with tunable and white-light emission by incorporating lanthanide cations (Ln3+) into the channels of MIL-121 (Al(OH)(H2btec)·H2O) whose uncoordinated carboxyl groups can act as post-synthetic modification sites. The intense luminescence of Ln3+ doped MIL-121 indicates that the framework with rigid, permanently porous structure and non-coordinated carboxyl can serve as both a scaffold and an antenna for hosting and sensitizing the luminescence of Ln3+ cations. Moreover, a fine-tuning of the emitted color luminescence can be easily achieved by simply modulating the doping ratio or adjusting the excitation wavelength. Notably, the red–green–blue-based white light emitting Ln-MOFs can be realized by simultaneously doping Eu3+ and Tb3+ into the host framework. In addition, because of the excellent luminescence and the structural stability of Ln3+ functionalized MIL-121 (Ln3+@MIL-121) in water or solvents, the Eu3+@MIL-121 was developed as a luminescent probe for sensing of anions in aqueous solutions and small organic molecules. Luminescent studies reveal that Eu3+@MIL-121 not only display a high-sensitivity sensing function with respect to fluoride and dichromate ions but also exhibit significant solvent-dependent luminescent response to small-molecule pollutants, such as chloroform and acetone.

Two novel metal–organic frameworks, formulated as [Ni3(qptc)2(H2O)3]·3.5H2O·3Me2NH (1) and [Co3(qptc)2(H2O)4]·5H2O (2) (H4qptc = 1,1′:4′,1′′:4′′,1′′′-quaterphenyl-2,4,2′′′,4′′′-tetracarboxylic acid), have been hydrothermally constructed based on a rigid aromatic multicarboxylate ligand. The single-crystal X-ray diffraction analysis shows that complex 1 crystallizes in the triclinic crystal system with space group P and possesses a 4,8-connected 3D open framework including trinuclear nickel Ni3 SBUs, which belongs to an scu topology with the point symbols (416·612) and (44·62). Complex 2 belongs to the monoclinic crystal system with space group C2/c and exhibits a 3D framework containing Co3 SBUs, which is a flu topology with the point symbols (412·612·84) and (46). Furthermore, the variable-temperature magnetic susceptibilities of complexes 1 and 2 have been investigated. Both complexes show weak ferromagnetic coupling between metal ions estimated by using a linear trinuclear model for 1 in the range of 2–300 K and the PHI program for 2 in the range of 20–300 K taking the orbital contribution into consideration.

In order to improve the visual quality to a best possible level for target recognition in turbid water such as river and lake, based on previous works, Maximum a posteriori (MAP) regularization based super-resolution restoration techniques using suitable point spread function (PSF) as prior knowledge are applied for a laser diode (LD) based imaging system operating in turbid water. Objective image quality metrics are used to evaluate the effectiveness of image enhancement and determine the iteration time of the proposed algorithm. Experimental results prove that the proposed method can effectively improve the resolution and quality for LD based imaging in turbid lake water, which shows potential of LD based imaging for detecting objects embedded in turbid media, such as murky water, lake water, river water, and sea water in various applications.

A luminescent nanoprobe based on a lanthanide-transition heterometallic metal–organic framework (MOF) is first designed for specific detection of urinary thiodiglycolic acid (TDGA) which is the biomarker of carcinogenic vinyl chloride monomer (VCM) and represents the internal dose of human exposure to VCM. The nanoprobe demonstrates high selectivity to TDGA with about 27.5-fold luminescence enhancement. It also displays excellent sensitivity with a detection limit as low as 89 ng·mL–1 and fast response to TDGA within 4 min, while refraining from the interference of other coexisting species in urine. Such good sensing performance enables the nanoprobe to practically monitor TDGA levels in human urine. Moreover, a portable urine dipstick based on the sensor is developed to conveniently evaluate individuals’ intoxication degree of VCM. This fast, sensitive, and selective nanoprobe has promising potential to be a useful tool for point-of-care diagnosis of disease associated with VCM exposure.

The targeted delivery of a photosensitizer (PS) with appropriate carriers represents an attractive means of selectively delivering cargo to target tissues or subcellular compartments for photodynamic therapy (PDT). Herein, a three-arm distyryl BODIPY derivative conjugated with mannose units (denoted by BTM) that can co-assemble with Tween 80 to form nanomicelles (BTM-NMs) for targeted PDT is reported. MDA-MB-231 breast cancer cells recognized and specifically internalized BTM-NMs via mannose-receptor-mediated endocytosis with preferential accumulation in the lysosomes. These NMs could disassemble in cell lysosomes and subsequently induce highly efficient singlet oxygen (1O2) generation upon light irradiation. 1O2 disrupted the lysosomal membrane and promoted the escape of BTM from the lysosome into the cytoplasm, thereby resulting in the efficient and selective killing of cancer cells through PDT. This study may provide a new strategy for designing targeted PDT systems to fight cancer.

We report two-dimensional spectroscopic analysis of massive red spiral galaxies ($M_{*}$ $>$ 10$^{10.5}$ $M_{\odot}$) and compare them to blue spiral and red elliptical galaxies above the same mass limit based on the public SDSS DR15 MaNGA observations. We find that the stellar population properties of red spiral galaxies are more similar to those of elliptical galaxies than to blue spiral galaxies. Red spiral galaxies show a shallow mass-weighted age profile, and they have higher stellar metallicity and Mgb/${\rm \langle Fe \rangle}$ across the whole 1.5$R_{\rm e}$ as compared to blue spirals, but all these properties are close to those of elliptical galaxies. One scenario to explain this is that red spirals form as remnants of very gas-rich major mergers that happened above $z$$\sim$1., 10 pages, 3 figures, accepted for publication in ApJL

Metal-organic frameworks as a powerful platform for drug delivery have attracted significant attention in recent years. In this study, mesoporous iron-metal-organic framework nanoparticles (mesoMOFs) were synthesized via the double-template method. Cetyltrimethylammonium bromide (CTAB) and citric acid (CA) were chosen as the double-template agent. The mesoMOFs were characterized by EDX, elemental analysis, TG, BET, SEM, TEM, and DLS. The anticancer drug doxorubicin hydrochloride (DOX) was encapsulated in the mesoMOFs, and the DOX loading content was up to 55 wt%. The mesoMOFs are non-toxic to both 4T1 breast cancer cells and 3T3 fibroblasts. The DOX-loaded mesoMOFs exhibit a better anti-tumor effect than free doxorubicin in vitro. The in vivo anticancer activities of the DOX-loaded mesoMOFs were investigated in 4T1 breast cancer-bearing mice. The intratumoral injection of DOX-loaded mesoMOFs revealed that the mesoMOFs could significantly reduce the systemic toxicity of DOX, sustainably release DOX, and maintain an effective DOX concentration for chemotherapy. The DOX-loaded mesoMOFs exhibit excellent therapeutic efficacy and low side effects in local chemotherapy.

The Ly$\alpha$ escape fraction is a key measure to constrain the neutral state of the intergalactic medium and then to understand how the universe was fully reionized. We combine deep narrowband imaging data from the custom-made filter NB393 and the $H_{2}S$1 filter centered at 2.14 $\mu$m to examine the Ly$\alpha$ emitters and H$\alpha$ emitters at the same redshift $z=2.24$. The combination of these two populations allows us to determine the Ly$\alpha$ escape fraction at $z=2.24$. Over an area of 383 arcmin$^{2}$ in the Extended Chandra Deep Field South (ECDFS), 124 Ly$\alpha$ emitters are detected down to NB393 = 26.4 mag at the 5$\sigma$ level, and 56 H$\alpha$ emitters come from An14. Of these, four have both Ly$\alpha$ and H$\alpha$ emissions (LAHAEs). We measure the individual/volumetric Ly$\alpha$ escape fraction by comparing the observed Ly$\alpha$ luminosity/luminosity density to the extinction-corrected H$\alpha$ luminosity/luminosity density. We revisit the extinction correction for H$\alpha$ emitters using the Galactic extinction law with the color excess for nebular emission. We also adopt the Calzetti extinction law together with an identical color excess for stellar and nebular regions to explore how the uncertainties in extinction correction affect our results. In both cases, an anti-correlation between the Ly$\alpha$ escape fraction and dust attenuation is found among the LAHAEs, suggesting that dust absorption is responsible for the suppression of the escaping Ly$\alpha$ photons. However, the estimated Ly$\alpha$ escape fraction of individual LAHAEs varies up to ~3 percentage points between the two methods of extinction correction. We find the global Ly$\alpha$ escape fraction at $z=2.24$ to be ($3.7\pm1.4$)% in the ECDFS. The variation in the color excess of the extinction causes a discrepancy of ~1 percentage point in the global Ly$\alpha$ escape fraction., Comment: 12 pages, 8 figures, 1 table, accepted for publication in ApJ

Based on a sample of 79 local advanced merger (adv-merger) (U)LIRGs, we search for the evidence of quenching process by investigating the distributions of the star formation history indicators (EW(H$\alpha$), EW(H$\delta$$_A$) and D$_n(4000)$) on the NUV-r color-mass and SFR-$M_{\ast}$ diagrams. The distributions of the EW(H$\alpha$) and D$_n(4000)$ on the NUV-r color-mass diagram show clear trends that at a given stellar mass, galaxies with redder NUV-r colors have smaller EW(H$\alpha$) and larger D$_n(4000)$. The reddest adv-merger (U)LIRGs close to the green valley have D$_n(4000)$$>1.4$ mostly. In addition, in the SFR-$M_{\ast}$ diagram, as the SFR decreases, the EW(H$\alpha$) decreases and the D$_n(4000)$ increases, implying that the adv-merger (U)LIRGs on the star formation main sequence have more evolved stellar populations than those above the main sequence. These results indicate that a fraction of the adv-merger (U)LIRGs have already exhibited signs of fading from the starburst phase and that the NUV-r reddest adv-merger (U)LIRGs are likely at the initial stage of post-starbursts with age of $\sim 1$ Gyr, which is consistent with the gas exhausting time-scales. Therefore, our results offer additional support for the fast evolutionary track from the blue cloud to the red sequence., Comment: 8 pages, 4 figures, accepted for publication in Research in Astronomy and Astrophysics

A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag(+) ions can tune the dual-emissive characters of the material. FA can interact with the Ag(+) ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.

With the aim of exploring the fast evolutionary path from the blue cloud of star-forming galaxies to the red sequence of quiescent galaxies in the local universe, we select a local advanced merging infrared luminous and ultraluminous galaxy (adv-merger (U)LIRGs) sample and perform careful dust extinction corrections to investigate their positions in the SFR-$M_{\ast}$, u-r and NUV-r color-mass diagrams. The sample consists of 89 (U)LIRGs at the late merger stage, obtained from cross-correlating the IRAS Point Source Catalog Redshift Survey and 1 Jy ULIRGs samples with the Sloan Digital Sky Survey DR7 database. Our results show that $74\%\pm 5\%$ of adv-merger (U)LIRGs are localized above the $1\, \sigma$ line of the local star-forming galaxy main sequence. We also find that all adv-merger (U)LIRGs are more massive than and as blue as the blue cloud galaxies after corrections of Galactic and internal dust extinctions, with $95\%\pm 2\%$ and $81\%\pm 4\%$ of them outside the blue cloud on the u-r and NUV-r color-mass diagrams, respectively. These results, combined with the short timescale for exhausting the molecular gas reservoir in adv-merger (U)LIRGs ($3\times 10^{7}$ to $3\times 10^{8}$ years), imply that the adv-merger (U)LIRGs are likely at the starting point of the fast evolutionary track previously proposed by several groups. While the number density of adv-merger (U)LIRGs is only $\sim 0.1\%$ of the blue cloud star-forming galaxies in the local universe, this evolutionary track may play a more important role at high redshift., Comment: 32 pages, 8 figures, accepted for publication in ApJ

Metal-organic frameworks (MOFs) are intriguing platforms with multiple functionalities. Additional functionalization of MOFs generates novel materials for various applications. Here, three main topics are examined regarding the functionalization of MOFs for use as photoactive materials. The first is chemical approaches for postsynthetic modification of the metal clusters and organic linkers in MOFs; that is, sites on pore surfaces and chemical trapping of photoactive moieties within the pores, which create materials with chemical functionalities for water splitting and CO2 reduction by light. The second topic focuses on the functionalization of MOFs for photochemical response and the versatile applications of such materials. State-of-the-art research on functionalizing MOFs through photochemical reactions on the pore surface and within the pores as guests is also summarized. The third topic introduces the functionalization of MOFs for photofunctional materials, including photoluminescent tuning and integration, photoluminescent LED devices and barcodes, and photophysical applications for chemical sensing. Finally, conclusions and perspectives on the fields are given.

Unsafe food is a huge threat to human health and the economy, and detecting food spoilage early is an ongoing and imperative need. Herein, a simple and effective strategy combining a fluorescence sensor and one-to-two logic operation is designed for monitoring biogenic amines, indicators of food spoilage. Sensors (methyl red@lanthanide metal-organic frameworks (MR@EuMOFs)) are created by covalently modifying MR into NH2 -rich EuMOFs, which have a high quantum yield (48%). A double-stimuli-responsive fluorescence center is produced via energy transfer from the ligands to Eu3+ and MR. Portable sensory hydrogels are obtained by dispersing and solidifying MR@EuMOFs in water-phase sodium salt of carboxy methyl cellulose (CMC-Na). The hydrogels exhibit a color transition upon "smelling" histamine (HI) vapor. This transition and shift in the MR-based emission peak are closely related to the HI concentration. Using the HI concentration as the input signal and the two fluorescence emissions as output signals, an advanced analytical device based on a one-to-two logic gate is constructed. The four output combinations, NOT (0, 1), YES (1, 0), PASS 1 (1, 1), and PASS 0 (0, 0), allow the direct analysis of HI levels, which can be used for real-time food-freshness evaluation. The novel strategy suggested here may be a new application for a molecular logic system in the sensing field.

1-Hydroxypyrene (1-HP), which is a biomarker of polycyclic aromatic hydrocarbons (PAHs) carcinogens and represents the internal dose of PAHs exposure in the human body, is detected by a newly designed luminescent Eu-functionalized metal-organic framework (1a) sensor. The luminescence of 1a can be effectively quenched by 1-HP via a fluorescent resonant energy transfer process, thus achieving its recognition of 1-HP. This is the first use of lanthanide metal-organic frameworks (Ln-MOFs) as chemical sensors for 1-HP. The probe exhibits outstanding performances for sensing 1-HP, such as high selectivity, excellent sensitivity, fast response, and good reusability. Importantly, the sensing system enables the detection of 1-HP in real human urine specimens, and a portable 1-HP urine test paper is also developed. Hence, the reported 1-HP sensing platform has promising application potential for clinical diagnosis of the intoxication level of PAHs.

We investigate the evolution of nuclear gas-phase oxygen abundance and star formation rate (SFR) of local far-infrared selected star-forming galaxies along the merger sequence, as traced by their optical morphologies. The sample was drawn from a cross-correlation analysis of the IRAS Point Source Catalog Redshift Survey and 1 Jy ultraluminous infrared galaxies sample with the Sloan Digital Sky Survey Data Release 7 database. The investigation is done by comparing our sample to a control sample matched in the normalized redshift distribution in two diagnostics, which are the nuclear gas-phase metallicity vs. stellar mass and the nuclear SFR vs. stellar mass diagrams. Galaxies with different morphological types show different mass-metallicity relations (MZR). Compared to the MZR defined by the control sample, isolated spirals have comparable metallicities with the control sample at a given stellar mass. Spirals in pairs and interacting galaxies with projected separations $r_{p} >$ 20 kpc show mild metallicity dilution of 0.02-0.03 dex. Interacting galaxies with $r_{p}, Comment: 24 pages, 6 figures, accepted for publication in Research in Astronomy and Astrophysics

Background Salvia miltiorrhiza (Danshen) is one of the most widely used medicinal herbs in traditional Chinese medicine. Locality-level and cultivar identification is of great importance not only for protecting highest therapeutic effectiveness of Daodi Danshen, but also for the genetic conservation and utilization of existing S. miltiorrhiza populations. Results Intron polymorphisms including SNPs (single nucleotide polymorphisms) and indels were exploited in major latex-like protein (MLP) gene. Based on these markers, genetic relationships among S. miltiorrhiza cultivar and populations in different locations were evaluated by constructing a dendrogram. Moreover, S. miltiorrhiza specimens from Laiwu region were geographically distinguishable by the developed SNP marker. A 204 bp-indel marker was exploited for the first space breeding cultivar Luyuan Danshen-1 (LD-1), and an effective real-time PCR assay was successfully developed for fast screening of LD-1 among local landraces. Conclusions MLP intron is a valuable DNA barcode for intra-specific study of S. miltiorrhiza populations, and the developed markers can serve as a useful tool for molecular identification of LD-1 cultivar and geographically distinct populations of S. miltiorrhiza. Electronic supplementary material The online version of this article (doi:10.1186/s40064-016-3611-5) contains supplementary material, which is available to authorized users.