Preparation and application of silver/chitosan-sepiolite materials with antimicrobial activities and low cytotoxicity.

Antimicrobial materials can prevent microbial infection and affect the beauty and structure of interior walls. Herein, a hybrid material silver/chitosan-sepiolite (Ag/5CTs-Sep) with antimicrobial activities was prepared via impregnation. Its antimicrobial properties were investigated via the disk diffusion method. Results showed that the width of inhibition zone of Ag/5CTs-Sep against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Aspergillus niger reached 58.15, 32.95 and 35.18 mm, respectively. The Sep was a suitable carrier for increasing thermal stability and antimicrobial durability, and chitosan improved the dispersion of silver to enhance antimicrobial activities. In addition, characterization indicated that the modification of Sep by CTs can promote the formation of lattice oxygen in Ag/5CTs-Sep, which can induce a high reactive oxygen species (ROS) content, causing the death of microbials. The antifungal mechanism revealed that the death of Aspergillus niger was due to Ag/5CTs-Sep that induced the production of high ROS level and damaged cell membrane. Moreover, Ag/5CTs-Sep possessed low cytotoxicity, and an applied test of the water-based coatings showed that the addition of Ag/5CTs-Sep could both effectively inhibit microorganisms and meet the performance standards for water-based coatings. This work may provide new guidance for the design and application of antibacterial materials.

Preparation of organic-inorganic chitosan@silver/sepiolite composites with high synergistic antibacterial activity and stability.

Organic-inorganic antibacterial materials chitosan@silver/sepiolite (CTs@Ag/Sep) was prepared by grafting organometallic chelate of chitosan and silver on sepiolite. The prepared samples were characterized, and their antibacterial properties were detected. The carrier sepiolite was beneficial for the thermal stability of the composite material. The utilization of silver was enhanced and its amount of usage could be obviously reduced by introduction of nontoxic chitosan which was benefical for the formation of highly dispersed silver nanoparticles on the CTs@Ag/Sep by the interaction between the silver ion and the plentiful amino and hydroxyl groups on the chitosan, thus improved the antibacterial activities and stability. The average width of the inhibition zone of CTs@Ag/Sep against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Aspergillus niger were 51.8, 31.8, and 44.7 mm, respectively. The cytotoxicity of CTs@Ag/Sep was further evaluated with A549 cells, and the results indicated that it exhibited low cytotoxicity to eukaryotic cells.

Selective Cl-Decoration on Nanocrystal Facets of Hematite for High-Efficiency Catalytic Oxidation of Cyclohexane: Identification of the Newly Formed Cl-O as Active Sites.

Understanding the structure-reactivity relationship at the atomic scale is of great theoretical importance for rational design of highly active catalysts, which has long been a central concern in catalysis communities and interface science. Herein, we developed a high-efficiency catalyst for catalytic oxidation of C6H12 by poststructural decoration on well-defined single-crystal facets of hematite. Especially for Cl-decorated {012} facets, the conversion and KA oil selectivity are improved about 3.4 times and 2 times, respectively. A better catalytic performance of the newly formed active site is derived from the charge difference between Cl and the neighboring outmost O atoms, which is affected by the geometric and electronic structures of the original catalyst surface. Based on the experimental results and the theoretical analysis, we concluded that the contribution of various O terminations to Cl-decoration follows the order O(I) > O(III) > O(II). Cl-decorated {001} facets show the highest intrinsic activity, whereas Cl-decorated {012} facets show the best catalytic performance because of their more active sites for Cl-decoration.

Solid-State, Low-Cost, and Green Synthesis and Robust Photochemical Hydrogen Evolution Performance of Ternary TiO2/MgTiO3/C Photocatalysts.

Solar-driven photochemical hydrogen evolution is a promising route to sustainable hydrogen fuel production. Large-scale preparation of highly active photocatalysts using elementally abundant and less-expensive materials is urgently required for widespread practical application. Here, we report a highly efficient and low-cost TiO2/MgTiO3/C heterostructure photocatalyst for photochemical water splitting, which was synthesized on gram scale via a facile mechanochemical method. The heterostructure and carbon sensitization offer excellent photoconversion efficiency as well as good photostability. Under irradiation of one AM 1.5G sunlight, the optimal TiO2/MgTiO3/C photocatalyst can show a great solar-driven hydrogen evolution rate (33.3 mmol·h-1·g-1), which is much higher than the best yields ever reported for MgTiO3-related photocatalysts or pure TiO2 (P-25). We hope this work will attract more attention to inspire further work by others for the development of low-cost, efficient, and robust photocatalysts for producing hydrogen in artificial photosynthetic systems.

Different Crystal Form Titania Supported Ruthenium Nanoparticles for Liquid Phase Hydrodeoxygenation of Guaiacol.

Titania supported Ruthenium-based catalysts were prepared for liquid phase hydrodeoxygenation of guaiacol to cyclohexanol. The catalytic performance is affected by the different crystal forms of titania supports. Anatase and rutile titania supported catalyst 5%Ru/a-r-TiO2 presents higher BET surface area, better dispersion of Ru particles with smaller particle size of 3-4 nm, more acidic centers, and more Ruδ+ located at the boundary between anatase titania and rutile titania. Hence, 5%Ru/a-r-TiO2 gives the best catalytic performance of 95.33% conversion of guaiacol and 79.23% selectivity to cyclohexanol, other products mainly include cyclohexane, benzene, cyclohexanone and 1,2-cyclohexanediol. Based on the results of this work, the possible reaction path for guaiacol hydrodeoxygenation was proposed.

Ti-doped α-Fe2O3 nanorods with controllable morphology by carbon layer coating for enhanced photoelectrochemical water oxidation.

Ti-doped α-Fe2O3 nanorods (NRs) with carbon layer coating were fabricated for photoelectrochemical (PEC) water oxidation. The α-Fe2O3 NRs were grown on the surface of a Ti foil substrate by hydrothermal synthesis. Ti4+ was diffused from the Ti substrate and doped into the α-Fe2O3 NRs by sintering at 800 °C. The presence of Fe2+ in the α-Fe2O3 lattice was achieved by annealing the NRs in a lack of oxygen atmosphere, e.g. in argon. The co-existence of Ti4+ and Fe2+ results in significant enhancement of the PEC performance compared with the hematite NRs obtained by annealing in air, showing the absence of Fe2+. The carbon layer coating was conducted by the carbonization of glucose. Impressively, the coated carbon layer can not only facilitate the charge transfer of the photogenerated carriers but also effectively restrain the structural aggregation of the NRs upon high temperature sintering. The carbon layer coated NRs exhibited 1.2 times higher photocurrent density than the uncoated NRs due to the reduced charge recombination and well-distinct NR structures.

Boosting one-step conversion of cyclohexane to adipic acid by NO2 and VPO composite catalysts.

We demonstrate VPO composites as efficient catalysts for highly selective oxidation of cyclohexane to adipic acid with NO2. In particular, the Ni-Al-VPO composite catalyst exhibits the striking conversion of cyclohexane (60.6%) and exceptionally high selectivity towards adipic acid (85.0%). Moreover, N2O is an environmentally harmful gas, and its yield in the present process is only 0.03 t/t adipic acid, which is far below that obtained using the industrial method (0.3 t/t adipic acid). This work provides a new strategy for the one-step synthesis of dicarboxylic acids from cycloalkanes.

Hyperplane intercept vector calibration method in grey analytical systems.

A novel vector calibration method, hyperplane intercept, is proposed for grey analytical systems to resolve the concentrations of the chemical components from the multi-component data gained from attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. This method is capable of quantifying a particular component known to be present in the mixture without having to know the identity of the rest of the components. Through the target factor analysis (TFA), a section of the IR spectrum of the interested component is chosen to calculate the concentration by the proposed hyperplane intercept method. Results calculated from on-line ATR-FTIR spectroscopy data of cyclohexanone ammoximation process are used to illustrate the simplicity and efficiency of this proposed method.

Study on bromocresol green-cetyltrimethylammonium-deoxyribonucleic acids system by resonance light scattering spectrum methods.

An assay of deoxyribonucleic acids (DNA) determination, with the sensitivity at nanogram level, was established in the present study by using a common spectrofluorometer to detect the intensity of resonance light scattering (RLS). In hexamethylene tetramine (HMTA) buffer (pH 11.00), Bromocresol Green (BCG) and deoxyribonucleic acids (DNA) react with cetyltrimethylammonium bromide (CTMAB) to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 336, 390, and 622 nm and at 336 nm that is the strongest of the three enhanced RLS peaks. Mechanistic studies showed that the enhanced RLS stems from the aggregation of BCG on DNA through the bridged and synergistic effect of CTMAB. Yeast DNA (yDNA), in the range of 0.05-0.90 ngml(-1), fish sperm DNA (fsDNA) in the range of 0.05-0.80 ngml(-1), and calf thymus DNA (ctDNA) in the range of 0.05-0.80 ngml(-1) can be determined if 2.0 x 10(-6) moll(-1) BCG was employed. The determination limit of yDNA was 12.7 ngml(-1). Three synthetic samples of yDNA were analyzed with good reproducibility.