Interface synergism and engineering of Pd/Co@N-C for direct ethanol fuel cells.

Direct ethanol fuel cells have been widely investigated as nontoxic and low-corrosive energy conversion devices with high energy and power densities. It is still challenging to develop high-activity and durable catalysts for a complete ethanol oxidation reaction on the anode and accelerated oxygen reduction reaction on the cathode. The materials' physics and chemistry at the catalytic interface play a vital role in determining the overall performance of the catalysts. Herein, we propose a Pd/Co@N-C catalyst that can be used as a model system to study the synergism and engineering at the solid-solid interface. Particularly, the transformation of amorphous carbon to highly graphitic carbon promoted by cobalt nanoparticles helps achieve the spatial confinement effect, which prevents structural degradation of the catalysts. The strong catalyst-support and electronic effects at the interface between palladium and Co@N-C endow the electron-deficient state of palladium, which enhances the electron transfer and improved activity/durability. The Pd/Co@N-C delivers a maximum power density of 438 mW cm-2 in direct ethanol fuel cells and can be operated stably for more than 1000 hours. This work presents a strategy for the ingenious catalyst structural design that will promote the development of fuel cells and other sustainable energy-related technologies.

The Effect of Omega-9 on Bone Viscoelasticity and Strength in an Ovariectomized Diet-Fed Murine Model.

Few studies have investigated the effect of a monosaturated diet high in ω-9 on osteoporosis. We hypothesized that omega-9 (ω-9) protects ovariectomized (OVX) mice from a decline in bone microarchitecture, tissue loss, and mechanical strength, thereby serving as a modifiable dietary intervention against osteoporotic deterioration. Female C57BL/6J mice were assigned to sham-ovariectomy, ovariectomy, or ovariectomy + estradiol treatment prior to switching their feed to a diet high in ω-9 for 12 weeks. Tibiae were evaluated using DMA, 3-point-bending, histomorphometry, and microCT. A significant decrease in lean mass (p = 0.05), tibial area (p = 0.009), and cross-sectional moment of inertia (p = 0.028) was measured in OVX mice compared to the control. A trend was seen where OVX bone displayed increased elastic modulus, ductility, storage modulus, and loss modulus, suggesting the ω-9 diet paradoxically increased both stiffness and viscosity. This implies beneficial alterations on the macro-structural, and micro-tissue level in OVX bone, potentially decreasing the fracture risk. Supporting this, no significant differences in ultimate, fracture, and yield stresses were measured. A diet high in ω-9 did not prevent microarchitectural deterioration, nevertheless, healthy tibial strength and resistance to fracture was maintained via mechanisms independent of bone structure/shape. Further investigation of ω-9 as a therapeutic in osteoporosis is warranted.

A novel approach for the prevention of ionizing radiation-induced bone loss using a designer multifunctional cerium oxide nanozyme.

The disability, mortality and costs due to ionizing radiation (IR)-induced osteoporotic bone fractures are substantial and no effective therapy exists. Ionizing radiation increases cellular oxidative damage, causing an imbalance in bone turnover that is primarily driven via heightened activity of the bone-resorbing osteoclast. We demonstrate that rats exposed to sublethal levels of IR develop fragile, osteoporotic bone. At reactive surface sites, cerium ions have the ability to easily undergo redox cycling: drastically adjusting their electronic configurations and versatile catalytic activities. These properties make cerium oxide nanomaterials fascinating. We show that an engineered artificial nanozyme composed of cerium oxide, and designed to possess a higher fraction of trivalent (Ce3+) surface sites, mitigates the IR-induced loss in bone area, bone architecture, and strength. These investigations also demonstrate that our nanozyme furnishes several mechanistic avenues of protection and selectively targets highly damaging reactive oxygen species, protecting the rats against IR-induced DNA damage, cellular senescence, and elevated osteoclastic activity in vitro and in vivo. Further, we reveal that our nanozyme is a previously unreported key regulator of osteoclast formation derived from macrophages while also directly targeting bone progenitor cells, favoring new bone formation despite its exposure to harmful levels of IR in vitro. These findings open a new approach for the specific prevention of IR-induced bone loss using synthesis-mediated designer multifunctional nanomaterials.

Omega-9 Modifies Viscoelasticity and Augments Bone Strength and Architecture in a High-Fat Diet-Fed Murine Model.

The influence of diet on the development of osteoporosis is significant and not fully understood. This study investigated the effect of diets of varying lipid profiles and ω-3, ω-6 and ω-9 composition on the structural and mechanical properties of bone. The hypothesis studied was that a diet high in saturated fat would induce osteoporosis and produce an overall increased detrimental bony response when compared with a diet high in unsaturated ω-6, or ω-9. Male C57BL/6J mice were fed either a control diet, 50:50 mix (saturated:unsaturated) high in ω-9 (HFD50:50), a diet high in saturated fat (HSF) or a polyunsaturated fat diet high in ω-6 (PUFA) over an 8-week duration. Tibiae were retrieved and evaluated using DMA, 3-point-bending, histomorphometry, and microCT. Mice fed a HSF diet displayed key features characteristic of osteoporosis. The loss tangent was significantly increased in the HFD50:50 diet group compared with control (p = 0.016) and PUFA-fed animals (p = 0.049). HFD50:50-fed mice presented with an increased viscous component, longer tibiae, increased loss modulus (p = 0.009), and ultimate stress, smaller microcracks (p < 0.001), and increased trabecular width (p = 0.002) compared with control animals. A diet high in ω-9 resulted in an overall superior bone response and further analysis of its role in bone health is warranted.

Dual-Doping and Synergism toward High-Performance Seawater Electrolysis.

Hydrogen (H2 ) production from direct seawater electrolysis is an economically appealing yet fundamentally and technically challenging approach to harvest clean energy. The current seawater electrolysis technology is significantly hindered by the poor stability and low selectivity of the oxygen evolution reaction (OER) due to the competition with chlorine evolution reaction in practical application. Herein, iron and phosphor dual-doped nickel selenide nanoporous films (Fe,P-NiSe2 NFs) are rationally designed as bifunctional catalysts for high-efficiency direct seawater electrolysis. The doping of Fe cation increases the selectivity and Faraday efficiency (FE) of the OER. While the doping of P anions improves the electronic conductivity and prevents the dissolution of selenide by forming a passivation layer containing P-O species. The Fe-dopant is identified as the primary active site for the hydrogen evolution reaction, and meanwhile, stimulates the adjacent Ni atoms as active centers for the OER. The experimental analyses and theoretical calculations provide an insightful understanding of the roles of dual-dopants in boosting seawater electrolysis. As a result, a current density of 0.8 A cm-2 is archived at 1.8 V with high OER selectivity and long-term stability for over 200 h, which surpasses the benchmarking platinum-group-metals-free electrolyzers.

Strength Analysis and Stress-Strain Deformation Behavior of 3 mol% Y-TZP and 21 wt.% Al2O3-3 mol% Y-TZP.

The mechanical behavior of 3 mol% Y2O3-ZrO2 ceramic and 21 wt.% Al2O3-3 mol% Y2O3-ZrO2 ceramic composite with submicron grain size was studied. Mechanical properties, such as hardness, Young's modulus, four-point bending strength, and fracture toughness of both materials were measured. Linear stress-strain deformation behavior of both 3 mol% Y2O3-ZrO2 and 21 wt.% Al2O3-3 mol% Y2O3-ZrO2 was observed in flexure, both at room temperature and at 400 °C. A small deviation from linear elastic deformation was detected in 21 wt.% Al2O3-3 mol% Y2O3-ZrO2 ceramic composite when loaded above a stress of 1500 MPa. Therefore, it was concluded that only elastic deformation occurred at low stresses upon loading, which exclude the presence of domain switching in zirconia upon bending under the loading conditions of this study.

Effect of Loading and Heating History on Deformation of LaCoO3.

The aim of this work was to study cyclic stress-strain deformation behavior of LaCoO3 as a function of loading and heating history. The ferroelastic hysteretic deformation of LaCoO3 at different stresses and temperatures was characterized using effective Young's modulus, hysteresis loop area and creep strain shift parameters. The deformation behavior of LaCoO3 was not significantly affected by the previous loading and heating history when tested at constant temperature. The high temperature strength and Young's modulus of LaCoO3 were higher compared to at room temperature. A creep strain shift parameter was introduced to characterize creep strain in LaCoO3 for the first time.

Do polyunsaturated fatty acids protect against bone loss in our aging and osteoporotic population?

Age-related bone loss is inevitable in both men and women and there will soon be more people of extreme old age than ever before. Osteoporosis is a common chronic disease and as the proportion of older people, rate of obesity and the length of life increases, a rise in age-related degenerating bone diseases, disability, and prolonged dependency is projected. Fragility fractures are one of the most severe complications associated with both primary and secondary osteoporosis and current treatment strategies target weight-bearing exercise and pharmacological intervention, both with limited long-term success. Obesity and osteoporosis are intimately interrelated, and diet is a variable that plays a significant role in bone regeneration and repair. The Western Diet is characterized by its unhealthy components, specifically excess amounts of saturated fat intake. This review examines the impact of saturated and polyunsaturated fatty acid consumption on chronic inflammation, osteogenesis, bone architecture, and strength and explores the hypothesis that dietary polyunsaturated fats have a beneficial effect on osteogenesis, reducing bone loss by decreasing chronic inflammation, and activating bone resorption through key cellular and molecular mechanisms in our aging population. We conclude that aging, obesity and a diet high in saturated fatty acids significantly impairs bone regeneration and repair and that consumption of ω-3 polyunsaturated fatty acids is associated with significantly increased bone regeneration, improved microarchitecture and structural strength. However, ω-6 polyunsaturated fatty acids were typically pro-inflammatory and have been associated with an increased fracture risk. This review suggests a potential role for ω-3 fatty acids as a non-pharmacological dietary method of reducing bone loss in our aging population. We also conclude that contemporary amendments to the formal nutritional recommendations made by the Food and Nutrition Board may be necessary such that our aging population is directly considered.

Spark Plasma Sintered B4C-Structural, Thermal, Electrical and Mechanical Properties.

The structural, thermal, electrical and mechanical properties of fully dense B4C ceramics, sintered using Spark Plasma Sintering (SPS), were studied and compared to the properties of B4C ceramics previously published in the literature. New results on B4C's mechanical responses were obtained by nanoindentation and ring-on-ring biaxial strength testing. The findings contribute to a more complete knowledge of the properties of B4C ceramics, an important material in many industrial applications.

Periodically Patterned Au-TiO2 Heterostructures for Photoelectrochemical Sensor.

Periodically patterned Au nanorods in TiO2 nanocavities (Au NRs@TiO2) were fabricated via magnetron sputtering followed by a thermal dewetting process. This innovative Au NRs@TiO2 heterostructure was used as a plasmonic sensing platform for photoelectrochemical detection of glucose and lactose. This Au NRs@TiO2 patterned heterostructure possesses superior sensing properties to other Au nanoparticle-based sensors because (i) localized surface plasmon resonance (LSPR) generated at Au/TiO2 interfaces enhanced sensitivity of glucose (lactose) amperometric detection; (ii) periodic Au nanocrystals in TiO2 nanocavities accelerated charge separation and transfer rate, especially under monochromatic blue light irradiation; (iii) discrete planar architectures comprising Au NRs immobilized on TiO2 substrates significantly improved stability and reusability of the sensors. A low detection limit of 1 µM (10 µM) and a high sensitivity of 812 µA mM-1 cm-2 (270 µA mM-1 cm-2) were achieved on the Au NRs@TiO2 heterostructures for glucose (lactose) detection without the addition of enzymes. Good selectivity and superb stability over more than 8 weeks was also demonstrated using these Au NRs@TiO2 heterostructures for glucose (lactose) detection. Additionally, this cost-efficient technique can be easily extended to other photoelectrochemical sensing systems when considering the combination of sensing and visible or infrared light source enhancement.

Enhanced Photoelectrocatalytic Reduction of Oxygen Using Au@TiO2 Plasmonic Film.

Novel Au@TiO2 plasmonic films were fabricated by individually placing Au nanoparticles into TiO2 nanocavity arrays through a sputtering and dewetting process. These discrete Au nanoparticles in TiO2 nanocavities showed strong visible-light absorption due to the plasmonic resonance. Photoelectrochemical studies demonstrated that the developed Au@TiO2 plasmonic films exhibited significantly enhanced catalytic activities toward oxygen reduction reactions with an onset potential of 0.92 V (vs reversible hydrogen electrode), electron transfer number of 3.94, and limiting current density of 5.2 mA cm-2. A superior ORR activity of 310 mA mg-1 is achieved using low Au loading mass. The isolated Au nanoparticle size remarkably affected the catalytic activities of Au@TiO2, and TiO2 coated with 5 nm Au (Au5@TiO2) exhibited the best catalytic function to reduce oxygen. The plasmon-enhanced reductive activity is attributed to the surface plasmonic resonance of isolated Au nanoparticles in TiO2 nanocavities and suppressed electron recombination. This work provides comprehensive understanding of a novel plasmonic system using isolated noble metals into nanostructured semiconductor films as a potential alternative catalyst for oxygen reduction reaction.

Size controlled mechanochemical synthesis of ZrSi2.

Mechanochemical metathesis reactions were utilized to synthesize nanocrystalline ZrSi(2) ranging from 9-30 nm in size. Size was controlled through dilution with CaCl(2). A linear relationship was found between diluent concentration and crystallite size. Unlike typical self-propagating metathesis reactions, this reaction did not self-propagate, requiring the input of mechanical energy.

Structural characterization combined with the first principles simulations of barium/strontium cobaltite/ferrite as promising material for solid oxide fuel cells cathodes and high-temperature oxygen permeation membranes.

Mixed ionic-electronic conducting perovskite type oxides with a general formula ABO(3) (where A = Ba, Sr, Ca and B = Co, Fe, Mn) often have high mobility of the oxygen vacancies and exhibit strong ionic conductivity. They are key materials that find use in several energy related applications, including solid oxide fuel cell (SOFC), sensors, oxygen separation membranes, and catalysts. Barium/strontium cobaltite/ferrite (BSCF) Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-delta) was recently identified as a promising candidate for cathode material in intermediate temperature SOFCs. In this work, we perform experimental and theoretical study of the local atomic structure of BSFC. Micro-Raman spectroscopy was performed to characterize the vibrational properties of BSCF. The Jahn-Teller distortion of octahedral coordination around Co(4+) cations was observed experimentally and explained theoretically. Different cations and oxygen vacancies ordering are examined using plane wave pseudopotential density functional theory. We find that cations are completely disordered, whereas oxygen vacancies exhibit a strong trend for aggregation in L-shaped trimer and square tetramer structure. On the basis of our results, we suggest a new explanation for BSCF phase stability. Instead of linear vacancy ordering, which must take place before the phase transition into brownmillerite structure, the oxygen vacancies in BSCF prefer to form the finite clusters and preserve the disordered cubic structure. This structural feature could be found only in the first-principles simulations and can not be explained by the effect of the ionic radii alone.