When ionizing irradiation interacts with a media, it can form reactive species that can react with the constituents of the system, leading to eradication of bioburden and sterilization of the tissue. Under-standing the media's properties such as polarity is important to control and direct those reactive species to perform desired reactions. Using ethanol as a polarity modifier of water, we herein generated a se-ries of media with varying relative polarities for electron beam (E-beam) irradiation of cornea at 25 kGy and studied how the irradiation media's polarity impacts properties of the cornea. After irradiation of corneal tissues, mechanical (tensile strength and modulus, elongation at break, and compression modu-lus), chemical, optical, structural, degradation, and biological properties of the corneal tissues were evalu-ated. Our study showed that irradiation in lower relative polarity media improved structural properties of the tissues yet reduced optical transmission; higher relative polarity reduced structural and optical prop-erties of the cornea; and intermediate relative polarity (ethanol concentrations = 20-30% (v/v)) improved the structural properties, without compromising optical characteristics. Regardless of media polarity, ir-radiation did not negatively impact the biocompatibility of the corneal tissue. Our data shows that the absorbed ethanol can be flushed from the irradiated cornea to levels that are nontoxic to corneal and retinal cells. These findings suggest that the relative polarity of the irradiation media can be tuned to generate sterilized tissues, including corneal grafts, with engineered properties that are required for spe-cific biomedical applications. Statement of significance Extending the shelf-life of corneal tissue can improve general accessibility of cornea grafts for transplan-tation. Irradiation of donor corneas with E-beam is an emerging technology to sterilize the corneal tissues and enable their long-term storage at room temperature. Despite recent applications in clinical medicine, little is known about the effect of irradiation and preservation media's characteristics, such as polarity on the properties of irradiated corneas. Here, we have showed that the polarity of the media can be a valuable tool to change and control the properties of the irradiated tissue for transplantation. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Purpose: To evaluate the effects of electron-beam (E-beam) irradiation on the human cornea and the potential for E-beam sterilization of Boston keratoprosthesis (BK) devices when pre-assembled with a donor cornea prior to sterilization. Methods: Human donor corneas and corneas pre-assembled in BK devices were immersed in recombinant human serum albumin (rHSA) media and E-beam irradiated at 25 kGy. Mechanical (tensile strength and modulus, and compression modulus), chemical, optical, structural, and degradation properties of the corneal tissue after irradiation and after 6 months of preservation were evaluated. Results: The mechanical evaluation showed that E-beam irradiation enhanced the tensile and compression moduli of human donor corneas, with no impact on their tensile strength. By chemical and mechanical analysis, E-beam irradiation caused a minor degree of crosslinking between collagen fibrils. No ultrastructural changes due to Ebeam irradiation were observed. E-beam irradiation slightly increased the stability of the cornea against collagenase-induced degradation and had no impact on glucose diffusion. The optical evaluation showed transparency of the cornea was maintained. E-beam irradiated corneal tissues and BK-cornea pre-assembled devices were stable for 6 months after room-temperature preservation. Conclusions: E-beam irradiation generated no detrimental effects on the corneal tissues or BK-cornea preassembled devices and improved native properties of the corneal tissue, enabling prolonged preservation at room temperature. The pre-assembly of BK in a donor cornea, followed by E-beam irradiation, offers the potential for an off-the-shelf, ready to implant keratoprosthesis device.

The prepared bifunctional Nb-OMS-2 catalysts are promising candidate in partial oxidation of methanol into dimethoxymethane at a lower temperature suggesting that there is an important temperature regime when forming active sites for DMM production.

Mesoporous Ni/CeO2 catalysts of variable loadings were prepared using in-situ doping and impregnation synthesis techniques. The catalysts were found to exhibit activity for the water-gas shift (WGS) reaction, particularly at temperatures above 250 degrees C. Structural, electronic, and surface chemical characterizations of the materials were carried out using in-situ X-ray diffraction (XRD), in-situ X-ray absorption (XANES), and in-situ infrared (DRIFTS) techniques. The effects of metal loading and preparation method on these properties were studied in order to develop a more complete understanding of the design and application of Ni-loaded mesoporous CeO2 catalysts. For WGS reaction activity, the in-situ doping method was observed to be superior, and overall activity was observed to increase with increasing metal loadings. Simple normalization of activity data to nominal nickel content revealed a trend favoring lower loadings, indicating higher activity per unit nickel. The reduction of the catalyst is observed with increasing reaction temperature (Ni2+ -> Ni degrees, Ce4+ -> Ce3+) while the active states of all catalysts were identified as a stable, partially reduced ceria fluorite lattice (Ce4+/Ce3+) with Ni2+ and Ni degrees. In Situ DRIFTS showed nearly identical surface chemistry for both doped and impregnated samples, likely involving an associative pathway at lower temperatures and a redox pathway at higher temperatures. Structural properties and surface chemistry were observed to depend both on metal loading and preparation method. Nickel loadings as low as 1 wt% prepared by in-situ doping were found to display the most favorable metal-support interactions for the WGS reaction.

In this study polymer, metal oxide and polymer-PZT composite microsphere materials were prepared by either hydrothermal or microwave assisted methods. Materials were subjected to microwave and ultrasound irradiation under specific conditions in order to understand their mechanical stability and morphological changes in dimensions. Scanning electron microscopy imaging was carried out before and after each irradiation and clear differences were observed depending on irradiation method and sample composition.

Mesoporous Co/CeO2 catalysts were found to exhibit significant activity for the high-temperature water-gas shift (WGS) reaction with cobalt loadings as low as 1 wt %. The catalysts feature a uniform dispersion of cobalt within the CeO2 fluorite type lattice with no evidence of discrete cobalt phase segregation. In situ XANES and ambient pressure XPS experiments were used to elucidate the active state of the catalysts as partially reduced cerium oxide doped with oxidized cobalt atoms. In situ XRD and DRIFTS experiments suggest facile cerium reduction and oxygen vacancy formation, particularly with lower cobalt loadings. In situ DRIFTS analysis also revealed the presence of surface carbonate and bidentate formate species under reaction conditions, which may be associated with additional mechanistic pathways for the WGS reaction. Deactivation behavior was observed with higher cobalt loadings. XANES data suggest the formation of small metallic cobalt clusters at temperatures above 400 degrees C may be responsible. Notably, this deactivation was not observed for the 1% cobalt loaded catalyst, which exhibited the highest activity per unit of cobalt.

Four micro (nano)-sized mesoporous ferric hydroxyphosphates (FHP) are synthesized by a reverse microemulsion-solvothermal method, and then are used as supports to prepare supported Pt catalysts. The mean particle diameter of Pt nanoparticles (NPs) was 4.5-4.6 nm. When the four different Pt/FHP catalysts were used into the hydrogenation of alpha,beta-unsaturated aldehydes (ketones) to their corresponding unsaturated alcohols, Pt/FHP (c) catalyst showed better catalytic performance than the other three partners. Under the optimal experimental conditions, several tested alpha,beta-unsaturated aldehydes could be effectively transformed into corresponding unsaturated alcohols over Pt/FHP (c) catalyst. The catalyst could be recycled and reused several times without activity loss. We propose the stronger interaction between the Pt NPs and ferric ions of the FHP (c) are responsible for its good catalytic performance, and this stronger interaction should be rooted in its enhanced Lewis acid strength. Graphical Abstract [GRAPHICS] .

The CO and H-2 (syngas) production from methane partial oxidation (MPO) using TiO2 supported Au-Pd bimetallic catalysts are discussed. The supported Au, Pd and Au-Pd bimetallic nanoparticles were prepared by an incipient wetness impregnation or co-impregnation method and were characterized. The supported Au-Pd catalyst was selective for reforming and was more active compared to bare TiO2, TiO2 supported Au only, or Pd only catalysts. The catalyst properties before and after MPO reaction were investigated, including the stability of the TiO2 support, and the stability of Au and Pd nanoparticles. The supported Au-Pd catalyst has the highest TON (TONH2 = 23 at 650 degrees C), compared to supported Au catalyst (TONH2 < 1) and supported Pd catalyst (TONH2 < 1). Based on the analysis of outlet gases from the MPO reaction in a flow reactor, synergetic effects between Au and Pd, where Pd activates C-H bonds while gold modulates the behavior of oxygen at the catalyst surface, are shown to contribute to MPO. Additionally, the Au-Pd/TiO2 material shows long-term activity (> 12 h) for the MPO reaction at 600 degrees C.

Aerobic Baeyer-Villiger oxidation of ketones into corresponding esters were performed over mesoporous Mn-Ce and Mn-Co composite oxides prepared by co-impregnation method and benzaldehyde was used as the sacrificing agent. It was found that the best conversion and selectivity were obtained when the Mn/Ce mole ratio was 1:2 (denoted as Mn0.33Ce0.67Os) through investigating the effect of Mn/Ce mole ratio on the catalytic activity. Interestingly, Mn0.33Ce0.67Os (Mn/Co mole ratio was 1:2) catalyst had no catalytic activity for this reaction. Xray diffraction (XRD) results showed that MnOx was completely dissolved into the CeO2 lattice, and Mn0.33Ce0.67Os sample was existed in the form of spinel structure (Co, Mn) (Mn, Co)(2)O-4 and obvious peaks of Co3O4. Nitrogen adsorption-desorption measurements revealed that Mn0.5Ce0.5Os, Mn0.33Ce0.67Os, Mn0.33Ce0.67Os and Mn0.33Ce0.67Os materials possessed mesoporous structure. X-ray photoelectron spectroscopy (XPS) analysis showed that the highest concentration of Ce3+ on the surface of Mn0.33Ce0.67Os catalyst, which could create unsaturated chemical bonds, charge imbalance, and oxygen vacancies on the surface of samples, it is beneficial to the oxidation reaction. Additionally, XPS data revealed that Mn0.33Ce0.67Os catalyst has great potential in catalytic oxidation due to the large amount of active oxygen species on the surface. In addition, manganese and cobalt species on the surface of Mn0.33Ce0.67Os are almost present in the form of Mn2+ and Co3+, it is known that Mn2+ can serve as a potent antioxidant and scavenge the activity of active oxygen species, while Co3+ ions can prevent the formation of oxygen vacancies and inhibit the release of reactive oxygen species, thus the presence of Mn2+ and Co3+ inhibited the catalytic activity of Mn0.33Ce0.67Os catalyst. The diffuse reflectance ultraviolet-visible spectroscopy (DR-UV-vis) and hydrogen temperature-programmed reduction (H-2-TPR) results are in accordance XPS data.

Rare-earth chromites are a new type of magnetoelectric multiferroics. In this work, a Ho0.33Gd0.67CrO3 powder sample was synthesized via a citrate route, and the structural properties were characterized by X-ray diffraction, scanning electron microscopy, and the Raman technique. The UV-Visible optical absorbance spectra were also measured in the wavelength range of 200–800 nm. The valence state of Cr was found to be purely 3+ according to the X-ray photoelectron spectroscopy. The temperature-dependent dielectric constant and loss tangent data measured between the frequencies of 1 kHz and 1 MHz show no anomalies around the magnetic transition temperature of the material. The dc magnetization measurements show that the ordering temperature of Cr3+ (TNCr) is 155 K for Ho0.33Gd0.67CrO3, which is larger than 140 K for HoCrO3. The positive slope of the Arrott plots from 0 T to 7 T reveals that the antiferromagnetic-paramagnetic phase transition is second-order in nature. At a field of 7 T, the Ho0.33Gd0.67CrO3 sample showed a giant magnetocaloric entropy change, −ΔS, of ∼23.3 J/kg K at 5 K, and a refrigeration capacity of ∼481.2 J/kg, which are much higher than those of pure bulk HoCrO3. This renders this material prospective for magnetic refrigeration in the low temperature (<30 K) range.

Four micro (nano)-sized mesoporous ferric hydroxyphosphates (FHP) are synthesized by a reverse microemulsion-solvothermal method, and then are used as supports to prepare supported Pt catalysts. The mean particle diameter of Pt nanoparticles (NPs) was 4.5–4.6 nm. When the four different Pt/FHP catalysts were used into the hydrogenation of α,β-unsaturated aldehydes (ketones) to their corresponding unsaturated alcohols, Pt/FHP (c) catalyst showed better catalytic performance than the other three partners. Under the optimal experimental conditions, several tested α,β-unsaturated aldehydes could be effectively transformed into corresponding unsaturated alcohols over Pt/FHP (c) catalyst. The catalyst could be recycled and reused several times without activity loss. We propose the stronger interaction between the Pt NPs and ferric ions of the FHP (c) are responsible for its good catalytic performance, and this stronger interaction should be rooted in its enhanced Lewis acid strength.

A tandem experimental and theoretical investigation of a mesoporous ceria catalyst reveals the properties of the metal oxide are conducive for activity typically ascribed to metals, suggesting reduced Ce3+ and oxygen vacancies are responsible for the inherent bi-functionality of CO oxidation and dissociation of water required for facilitating the production of H-2. The degree of reduction of the ceria, specifically the (100) face, is found to significantly influence the binding of reagents, suggesting reduced surfaces harbor the necessary reactive sites. The metal-free catalysis of the reaction is significant for catalyst design considerations, and the suite of in situ analyses provides a comprehensive study of the dynamic nature of the high surface area catalyst system. This study postulates feasible improvements in catalytic activity may redirect the purpose of the water-gas shift reaction from CO purification to primary hydrogen production.

The electronic and crystalline properties of solid complex materials dictate performance in electrochemical applications, such as electrodes or solid electrolytes in solid-state lithium ion power systems. Herein, we perform variable-temperature two-electrode impedance spectroscopy on a variety of nanocrystalline metal oxides to investigate their relative total conductivities and the kinetics of vacancy formation. Lithiated and unlithiated first-row transition metal oxides (manganese, iron, cobalt, and nickel) with various crystal structures, surface areas, and morphologies were investigated. Characterization of these materials by XRD, SEM, and TEM was performed to investigate the physiochemical properties and changes imparted by chemical lithiation, specifically on the textural properties. Activation energies derived from Arrhenius plots were found to vary between 17 and 33kJmol(-1) for the systems studied. Lithiated nickel oxide was observed to provide the lowest activation energy and highest conductivity of the studied systems. The relatively low electrical conductivity suggests conductive additives must be used to facilitate electron transfer in electrodes for these materials; however, the improved conductivity compared to nonporous bulk commercial oxide systems suggests these to be promising active materials for electrochemical applications.

The electrolysis of water provides a powerful pathway for the storage and conversion of clean and renewable energy. Therefore, the development of earth-abundant, inexpensive, highly efficient electrocatalysts contributes a great deal to the overall efficiency of a water electrolytic system. Here, inspired by the low charge transfer resistance of mixed-valence cations, the favorable H atom binding energy of cobalt, and high electrical conductivity of graphene, we report a facile synthesis strategy to synthesize a spinel ternary oxide material consisting of nickel, manganese, and cobalt supported on reduced graphene oxide (rGO/NMC) with further conversion into a spinel ternary sulfide via a gaseous sulfurization protocol. The rGO/NMC-312 oxide material is found to be an efficient OER electrocatalyst with an overpotential as low as 320 mV for a current density of 10 mA cm(-2), which is comparable to that of the state of the art OER catalysts. In addition, when used as HER electrocatalysts, the as-converted rGO/NMC-312 sulfide materials exhibit a low overpotential of 151 mV to reach a current density of 10 mA cm(-2), a small Tafel slope of 52 mV/decade, and a remarkable long-term stability. Impressively, a voltage of 1.56 V is required to achieve a current density of 20 mA cm(-2) in an alkaline medium at room temperature by applying rGO/NMC-312 oxide and sulfide as an alkaline water electrolysis anode and cathode, respectively. Our work offers a strategy to apply spinel ternary oxides and sulfides as electrocatalysts in water electrolysis.

We have synthesized and tested a highly active Cu doped mesoporous CeO2 catalyst system for the low temperature water-gas shift (WGS) reaction. While typical oxide-supported copper WGS catalysts are characterized by high copper loadings (30-40%), the morphological properties of the mesoporous CeO2 material enable high catalytic activity at copper loadings as low as 1%. Operando X-ray diffraction, in situ X-ray absorption near-edge structure spectroscopy (XANES), and operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) methods were used to probe the interactions between the metal and mesoporous oxide components under reaction conditions. Copper was observed to undergo reduction from oxide to metal under WGS conditions at 150 °C, while the CeO2 lattice was observed to expand upon heating, indicating Ce3+ formation correlated with CO2 production. The active state of the catalysts was confirmed by in situ XANES to contain Cu0 and partially reduced CeO2. DRIFTS analysis revealed carboxyl species bound to copper during reduction, as well as formate and carbonate surface species on ceria. Lower concentrations of copper were observed to foster enhanced metal-support interactions.

Recently, molybdenum disulfide (MoS2) and other transition metal dichalcogenide (TMD) compounds represent a class of layered materials which have received tremendous attention due to their promising electronic, electrode material, catalytic, and mechanical properties. Currently, many researchers have investigated molybdenum disulfide (MoS2) which represents one of the most promising catalysts among TMDs due to the semiconducting nature and enhanced photoluminescence properties for hydrogen evolution. In this work, a systematic study of the relationship between the hydrogen evolution reaction (HER) and the physiochemical properties of layered MoS2 and doped derivatives has been performed. HER measurements with chemically modified MoS2 nanosheets were carried out using a three-electrode cell with a 0.5 M sulfuric acid electrolyte. All of the modified MoS2 nanosheets exhibit variation of overpotential catalytic activity towards the hydrogen evolution reaction. Taking into account this experimental result a configurational change will significantly enhance physical and chemical properties.

Mn-Ce mixed oxides, synthesized by co-impregnation method, have been used in the catalytic oxidation of primary amines to corresponding nitriles. The effects of Mn/Ce molar ratio on the structure and catalytic properties were investigated, and the results showed the MnxCe1-xOs, mixed oxides exhibited higher catalytic activity than MnOx or CeO2. It was found that favorable selectivity and the best conversions for benzylic, heterocyclic, and aliphatic primary amines were obtained when the Mn/Ce atomic mole ratio was 2:1 (denoted as Mn0.67Ce0.33Os). These materials have been investigated using XRD, FT-IR, SEM, HRTEM, XPS, DR-UV vis, H-2-TPR, and EPR techniques. XRD results showed that the samples did not appear any diffraction of manganese oxides. SEM images showed that the nanoparticles of the mixed oxides can be uniformly distributed than MnOx or CeO2. HRTEM micrographs exhibited that Mn-Ce mixed oxides were all exposed (111) and (220) planes corresponding to CeO2, and Mn0.67Ce0.33Os catalyst had the highest mutual solubility, thus this catalyst could have the stronger interaction than other Mn-Ce mixed oxides, which was in accordance with XPS, H-2-TPR, and EPR analysis. XPS studies confirmed that the highest concentration of Ce3+ was obtained at the surface of Mn0.67Ce0.33Os sample, this situation provides a basis for the formation and stabilization of oxygen vacancies, and it is beneficial for oxidation reaction, which is in consistent with DR-UV vis results. In addition, XPS data also showed that Mn0.67Ce0.33Os sample provided the most adsorbed oxygen species, this suggested that the mobility and availability of the active oxygen species were enhanced. This conclusion also can be drawn from H-2-TPR analysis. EPR studies further supported the formation of Mn0.67Ce0.33Os solid solution. Based on the above analysis, the excellent catalytic performance should be attributed to the formation of a solid solution with the incorporation of Mnx+ into the CeO2 cubic fluorite lattice, this reduces the formation energy of oxygen vacancies and enhances the mobility of active oxygen species from the bulk to the catalyst surface. (C) 2017 Published by Elsevier B.V.