Antibacterial activities of gel-derived Ag-TiO<sub>2</sub>-SiO<sub>2</sub> nanomaterials under different light irradiation

Biofouling is a major obstacle to the efficient extraction of uranium from seawater due to the numerous marine microorganisms in the ocean. Herein, we report a novel amidoxime (AO) crystalline cova...

The initiation of UV light-induced signaling in mammalian cells is largely considered to be subsequent to DNA damage. Several studies have also described ceramide (CER), a lipid second messenger, as a major contributor in mediating UV light-induced c-Jun N-terminal kinase (JNK) activation and cell death. It is demonstrated here that UV-C light irradiation of U937 cells results in the activation and translocation of a Zn2+-independent acid sphingomyelinase, leading to CER accumulation in raft microdomains. These CER-enriched rafts aggregate and play a functional role in JNK activation. The observation that UV-C light also induced CER generation and the externalization of acid sphingomyelinase and JNK in human platelets conclusively rules out the involvement of a nuclear signal generated by DNA damage in the initiation of a UV light response, which is generated at the plasma membrane.

Slow Photon-Enhanced Heterojunction Accelerates Photocatalytic Hydrogen Evolution Reaction to Unprecedented Rates

Does reactive surface area depend on grain size? Results from pH 3, 25 °C far-from-equilibrium flow-through dissolution experiments on anorthite and biotite

Remarkable bactericidal traits of a metal-ceramic composite coating elated by hierarchically structured surface.

Magnesium oxide (MgO) was synthesized by three different methods: the sol–gel (SG), microwave-assisted sol–gel (MW), and hydrothermal (HT) methods for comparing the influence of the preparation conditions on the properties of the products. The powders were annealed at 450 °C. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM/HRTEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), BET specific surface area and porosity, photoluminescence, and UV–Vis spectroscopy. The samples consisted mainly of periclase as a crystalline phase, and the MW and HT preparation methods generated particles with higher specific surface areas. The powders had less-defined morphologies and high levels of aggregation. The optical band gaps of the samples were determined from UV DRS, and the photocatalytic activities of the magnesium oxides obtained by the three methods towards the degradation of methyl orange (MO) under UV light irradiation was evaluated.

Stability of Carthamin and Safflor Yellow B on Silk Powders under Continuous Irradiation of Fluorescent or UV-C Light

HNO3-involved one-step low temperature solvothermal synthesis of N-doped TiO2 nanocrystals for efficient photocatalytic reduction of Cr(VI) in water

Plant extracts serve as reducing and coating agents and are, therefore, commonly employed for the generation of silver (Ag) nanoparticles (NPs). Plant extract mediated synthesis of Ag NPs is a green, environmentally friendly and cost-effective technique which offers a new and potential alternative to chemically synthesized NPs, decreasing the utilization of hazardous and toxic chemicals and protecting the environment. Origanum vulgare L. extracts were evaluated for total flavonoid and phenol content. The free radical scavenging activity was determined employing 2,2-diphenyl-1-picrylhydrazyl assay. Ag NPs were produced exploiting ethanolic extracts of O. vulgare L. leaves. The generation of Ag NPs was carried out both in light and dark conditions. The biosynthesized Ag NPs were characterized employing microscopic and spectroscopic techniques. Antibacterial activities of Ag NPs were determined following appropriate methods. The results revealed that energy of photons was required to reduce Ag+ to Ag0. According to scanning electron microscopy reports, biologically formed Ag NPs ranged in size from 1 to 50 nmand were presented instability causing aggregation. They indicated that O. vulgare L. extracts were rich in flavonoids and phenols and exhibited strong antioxidant activity. Ag NPs exhibited good antibacterial activity immediately after production. Gram-positive strains showed higher sensitivity to Ag NPs compared to Gram-negative stains. Ag NPs can serve as an effective antibacterial agent against antibiotic-resistant strains. The kanamycin-resistant strain was more sensitive to Ag NPs than the ampicillin-resistant strain. Thus, Origanum extract-mediated synthesized Ag NPs can be recommended as alternative effective antibacterial agents, but their activity depended on bacterial species and strains.

Effects of micro-mesopore structure characteristics on methane adsorption capacity of medium rank coal

Photocatalytic oxidation of 2,4,6-trinitrotoluene in the presence of ozone under irradiation with UV and visible light

The BiVO4/HNTs hybrid photocatalysts were synthesized by liquid phase precipitation using natural halloysite nanotubes (HNTs) as supporter and Bi(NO3)·5H2O as resource of Bi. XRD, scanning electron microscopy (SEM), transmission electron microscopy, HRTEM, x-ray photo electron spectroscopy and UV–Vis DRS were used to characterize the samples prepared at different calcination temperatures, and the effects of crystallization, Brunauer–Emmett–Teller specific surface area and morphological structure on the photoactivity were investigated. Results reveal that increasing calcination temperature can accelerate the transition of BiVO4 from tetragonal to monoclinic and also decrease the surface area of BiVO4/HNTs. The SEM results showed that BiVO4 was successfully coated on HNTs surface with ellipsoid or near rod like morphology, and the obtained BiVO4/HNTs had regular nanotube morphology. HRTEM results showed that, the regular fringe spacing of the lattice planes are about 0.474 and 0.364 nm, which is consistent with the (110) and (200) plane of the monoclinic and tetragonal BiVO4, confirming the exiting of mixed crystal structure in BiVO4/HNTs. BiVO4 with tetragonal phase (80.02%) and monoclinic phase (19.98%) mixed crystal is loaded on the surface of HNTs with calcinations at 400 °C for 2 h. The structure and Si (Al)–O bond of HNTs can be obviously changed over the calcination temperature of 400 °C. The effect of calcination temperature on photocatalytic reactivity of samples was investigated by degradation of dyes (MB, MO and RhB) under simulated solar light. And the sample calcined at 400 °C with the better mixed crystalline structure and larger specific surface area exhibits significant activity with the removal rate of MB and RhB up to 100% within 4 h. The degradation of MB follows the first order kinetic model. BiVO4/HNTs photocatalysts with the band gap of 2.34 eV has higher photocatalytic reaction rate and better sedimentation performance than Degussa P25. The photocatalytic degradation efficiency of BiVO4/HNTs for MB was no significant reduction after four times recycles.

Preparation of visible light-driven SnS2/TiO2 nanocomposite photocatalyst for the reduction of aqueous Cr(VI)

Hydrothermal synthesis of visible light active zinc-doped tin disulfide photocatalyst for the reduction of aqueous Cr(VI)

We systematically investigated the physiological response as well as DNA damage repair and damage tolerance in Shewanella oneidensis MR-1 following UVC, UVB, UVA, and solar light exposure. MR-1 showed the highest UVC sensitivity among Shewanella strains examined, with D37 and D10 values of 5.6 and 16.5% of Escherichia coli K-12 values. Stationary cells did not show an increased UVA resistance compared to exponential-phase cells; instead, they were more sensitive at high UVA dose. UVA-irradiated MR-1 survived better on tryptic soy agar than Luria-Bertani plates regardless of the growth stage. A 20% survival rate of MR-1 was observed following doses of 3.3 J of UVC m(-2), 568 J of UVB m(-2), 25 kJ of UVA m(-2), and 558 J of solar UVB m(-2), respectively. Photoreactivation conferred an increased survival rate to MR-1 of as much as 177- to 365-fold, 11- to 23-fold, and 3- to 10-fold following UVC, UVB, and solar light irradiation, respectively. A significant UV mutability to rifampin resistance was detected in both UVC- and UVB-treated samples, with the mutation frequency in the range of 10(-5) to 10(-6). Unlike in E. coli, the expression levels of the nucleotide excision repair (NER) component genes uvrA, uvrB, and uvrD were not damage inducible in MR-1. Complementation of Pseudomonas aeruginosa UA11079 (uvrA deficient) with uvrA of MR-1 increased the UVC survival of this strain by more than 3 orders of magnitude. Loss of damage inducibility of the NER system appears to contribute to the high sensitivity of this bacterium to UVR as well as to other DNA-damaging agents.