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Global biodiversity is increasingly threatened by the spread of invasive species. Understanding the mechanisms influencing the initial colonization and persistence of invaders is therefore needed if conservation actions are to prevent new invasions or strive to slow their spread. The Eurasian Collared-Dove (Streptopelia decaocto, EUCO) is one of the most successful avian invasive species in North America; however, to our knowledge, no study has simultaneously examined the role that climate-matching, human activity, directional propagation, and local density have in this invasion process. Our research expands upon a cellular-automata-based hierarchical model developed to assess directional invasion dynamics to further quantify the impacts of climate, elevation, and land cover type on the spread of EUCO in North America. Our results suggest that EUCO's dispersal patterns can largely be explained by the effects of habitat, climate, and environmental conditions at different stages of the invasion process rather than some innate preferred north-westerly spread. Specifically, EUCO initially colonized warm and wet grassland habitats and tended to persist in urban areas. We also found that while EUCO were more likely to spread to the northeast of existing habitats, directional preference did not drive persistence and recolonization events. These findings highlight the importance of incorporating both neighborhood effects and environmental factors in the modelling of range-expanding species, adding to the toolset available to researchers to model invasive species spread. Further, our research demonstrates that historical records of invasive species occurrences can provide the data resources needed to disentangle the characteristics driving species invasion and enable predictions that are of critical importance to resource managers. [ABSTRACT FROM AUTHOR]

Si3N4:Al microbelts with tunable bandgap energy and resultant yellow-orange phosphors are prepared through a facile direct nitridation method. The bandgap energy of Si3N4:Al microbelts has been gradually trimmed from 2.58 eV to 2.67, 2.74 and 2.85 eV by regulating the Si/Al molar ratio from 1000 : 1 to 50 : 1. Si3N4:Al:Eu phosphors display a wide emission ranging from 500 to 800 nm when excited by a 450 nm blue LED light source. The crystal structure of Si3N4:Al microbelts is of the α-Si3N4 phase as characterized by X-ray diffraction, high-resolution TEM and crystal models. Si3N4:Al microbelts grow along the (012) stacking direction in a low doping concentration case and grow along the (011) stacking direction in a high doping concentration case. Theoretical calculation results show that Al prefers to occupy the low energy interstitial sites in the (012) plane. There are more substitutional sites in the (011) plane occupied by Al in the high doping concentration case with increasing the bandgap energy of Si3N4:Al. Warm white light emission has been achieved by precoating Si3N4:Al:Eu phosphors onto a blue LED chip, whose correlated color temperature (CCT) can be tailored from 3000 K to 6500 K by altering the phosphor amount, indicating a promising potential application of Si3N4:Al:Eu phosphors in warm white LEDs. [ABSTRACT FROM AUTHOR]

Free radicals are toxic agents known to induce cellular oxidative damage, and reactive oxygen species plays a key role in cancer therapy. Herein, we develop an efficient delivery nanomedicine for controlled free radical generation by loading innocuous percarbamide in chitosan-coated hollow mesoporous silica nanoparticles (PCA@HMSNs-CTS). Reactive oxygen species was generated continuously and kept at a high level during the sustained release process of hydrogen peroxide from PCA@HMSNs-CTS. The evidences for mechanism revealed an autocatalytic free radical chain reactions initiated by a short time soft-X-Ray. The reactive oxygen species intensity in solutions after initiation is 5.8-fold higher than that without soft-X-Ray initiation following with the decomposition of hyperoxides and generation of oxygen. PCA@HMSNs-CTS exhibit a pH-responsive reactive oxygen species release, and the reactive oxygen species exhibit a significant high level in cancer cells which efficiently decrease the cell viability. This work explores the radical generation strategy of percarbamide nanomedicine and is expected to present a new avenue to efficient nanomedicine for cancer therapy. [ABSTRACT FROM AUTHOR]

Tumor hypoxia is known to result in radiotherapy resistance and traditional radiotherapy using super-hard X-ray irradiation can cause considerable damage to normal tissue. Therefore, formamide peroxide (FPO) with high reactive oxygen content was employed to enhance the oxygen concentration in tumor cells and increase the radio-sensitivity of low-energy soft-X-ray. To improve stability of FPO, FPO is encapsulated into polyacrylic acid (PAA)-coated hollow mesoporous silica nanoparticles (FPO@HMSNs-PAA). On account of the pH-responsiveness of PAA, FPO@HMSNs-PAA will release more FPO in simulated acidic tumor microenvironment (pH 6.50) and subcellular endosomes (pH 5.0) than in simulated normal tissue media (pH 7.40). When exposed to soft-X-ray irradiation, the released FPO decomposes into oxygen and the generated oxygen further formed many reactive oxygen species (ROS), leading to significant tumor cell death. The ROS-mediated cytotoxicity of FPO@HMSNs-PAA was confirmed by ROS-induced green fluorescence in tumor cells. The presented FPO delivery system with soft-X-ray irradiation paves a way for developing the next opportunities of radiotherapy toward efficient tumor prognosis. [ABSTRACT FROM AUTHOR]

Low-energy ultrasound (LEUS), exhibiting obvious advantages as a safe therapeutic strategy, would be promising for cancer therapy. We had synthesized a LEUS-responsive targeted drug delivery system based on functional mesoporous silica nanoparticle for cancer therapy. Paclitaxel (PTX) was loaded in mesoporous silica nanoparticles with a hydrophobic internal channel, and folic acid (FA) functionalized β-Cyclodextrin (β-CD) was capped on the surface of the nanoparticles (DESN), which acted as a cancer-targeting moiety and solubilizer. The existence of a hydrophobic internal channel in the DESN was beneficial to the storage of hydrophobic PTX, along with the enhancement of the cavitation effect produced by mild low-energy ultrasound (LEUS, ≤1.0 W/cm2, 1 MHz). The DESN showed significantly enhanced cavitation effect, selective targeting, and achieved a rapid drug release under mild LEUS. To investigate the in vivo antitumor efficacy of the DESN upon LEUS irradiation, we established a 4T1 mammary tumor model. The DESN were confirmed to be of great biodegradability/biocompatibility. The tumor growth was significantly inhibited when the mice were treated with DESN (10 mg/kg) + LEUS with the relative tumor volume reduced to 4.72 ± 0.70 compared with the control group (V/V0 = 17.12 ± 2.75). The DESN with LEUS represented excellent inhibiting effect on tumor cell in vivo. This work demonstrated that DESN mediating dual mode chemo-sonodynamic therapy could be triggered by extracorporeal remote control, may suggest a promising clinical application in cancer therapy. [ABSTRACT FROM AUTHOR]

Fluorine plays an important role in dental protection and formation of enamel materials, however the intrinsic effect of fluorine on the formation mechanism of fluoridated hydroxyapatite still needs to be known. In this work, pure fluoridated hydroxyapatite (FHA) with a hierarchical architecture was produced by a simple one-pot method using CaF2, Ca(OH)2 and Ca(H2PO4)2·H2O. It was found that the hierarchical fluoridated hydroxyapatite showed a unique orientation structure and different phase transformation mechanism compared with hydroxyapatite (HA). In the phase transition process from DCPD (CaHPO4·2H2O, brushite) to DCPA (CaHPO4, monetite), and then to FHA, hierarchical FHA was formed with the c-axis-oriented nanowires perpendicular to the planes of DCPA plates. More importantly, the crystal orientation relationship between FHA and DCPA was found for the first time to be FHA [010]//DCPA [001] and FHA (001)//DCPA (010), which is quite different from the crystal orientation relationship of HA [1̅10]//DCPA [110] and HA (1̅12)//DCPA (112). It was found that the phase transition process from (100)DCPA to (100)FHA was occurred with a good crystal lattice match. F− on (100)FHA had a small ionic radius and high electronegativity, decreased the crystal lattices of (100)FHA and might enhance their negativity and reactivity. This result may help better understand the effect of fluorine on the crystal growth process of natural enamel and the preparation of pure FHA with a hierarchical architecture is informative for the synthesis of enamel-like biomaterials. [ABSTRACT FROM AUTHOR]

Rutile titania (TiO 2 ) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO 2 coatings. In the study, titania-nanosilver (TiO 2 /Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO 2 powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO 2 /Ag powders and coatings. Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO 2 /Ag coatings and no crystalline changed happened in the TiO 2 structure. The reduction ratios on the TiO 2 /Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus , respectively, and the TiO 2 /Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus , which indicated the TiO 2 /Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO 2 /Ag coatings were discussed with grain size and the content of silver as well as the microstructure of the coatings. [ABSTRACT FROM AUTHOR]

CO 2 photoreduction performance of CeO 2 has been markedly enhanced by Y doping, which is achieved by the introduction of abundant oxygen vacancies and the intermediate regulations on the catalyst. [Display omitted] • Doping in CeO 2 results in promoted CO 2 photoreduction to CO. • Doping in CeO 2 results in differential generation/transformation of intermediates. • CO 2 adsorption/activation facilitates generation/transformation of intermediates. • The intermediates accumulation is the main obstacle to achieve sustainable activity. Doping hetero-metal ions in semiconductors, especially metal oxides, is a common practice to elevate their photocatalytic reduction activity. However, the underlying enhancement mechanism of doping different metal ions into the host lattice on photocatalytic CO 2 reduction has been rarely explored and thus remains unclear. In this work, CeO 2 nanoparticles doped with three different metal ions (Ce M , M = Y, La, Mo) have been synthesized, which exhibited significantly improved photo-reduction CO 2 activity. According to the analysis of Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), Y and Mo doping results in increased oxygen vacancy concentration in CeO 2 , which promotes the absorption of UV–visible light and the separation/transfer of electrons and holes, consequently elevating the catalytic activity. More importantly, through in - situ FT-IR, CO 2 adsorption/activation and the intermediates generated on catalyst surface during CO 2 photoreduction reaction were investigated and discussed in-depth. Similar carbonates and hydrocarbonates, such as HCO 3 −, b-CO 3 2− and m-CO 3 2−, have been found to be produced on CeO 2 and Ce M , while these intermediates accumulated and strongly covered on the catalyst surface have been revealed to be responsible for the gradually declined CO 2 reduction activity and stability. [ABSTRACT FROM AUTHOR]