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A DBU-mediated cascade strategy of propargylamines with dimethyl 3-oxoglutarate for constructing a functionalized benzo[c]chromen-6-one core has been achieved. This cascade process presumably involves a sequence of 1,4-conjugate addition, followed by lactonization, alkyne-allene isomerization, enol-keto tautomerization, 6π-electrocyclization, and aromatization. This protocol features mild reaction conditions, simple operation, rich structural diversity, and good functional group tolerance. A photophysical survey reveals that the benzo[c]chromen-6-one products exhibit fluorescence properties and show potential for exploring fluorescent material applications.

A novel and versatile approach to construct 12-phenacyl-11H-benzo[b]xanthene-6,11(12H)-dione derivatives through copper-catalyzed cascade reaction of propargylamines with 2-hydroxynaphthalene-1,4-diones has been developed. The procedure is proposed to go through a sequence of 1,4-conjugate addition, intramolecular nucleophilic addition/dehydration, and hydrolysis of alkyne followed by an enol-ketone tautomerization. The reaction provides a new and highly efficient method for the synthesis of 12-phenacyl-11H-benzo[b]xanthene-6,11(12H)-diones by formation of three new bonds and one heterocycle from readily available starting materials in good to high yields (70-88%) with broad functional group compatibility in a single step.

Supercritical-pressure heat transfer of a hydrocarbon fuel has practical importance in fuel precooling technology in hypersonic air-breathing propulsion systems. Heat transfer of n-decane in helica...

Enhancing the electrocatalytic activity of transition metal phosphides (TMPs) for hydrogen evolution has become an attractive way for noble-metal-free electrocatalysts. In this work, a novel composite of network-like tungsten phosphide nanostructures on carbon fibers (CFs@WP) was prepared by a two-step high-temperature calcination strategy. Owing to the high electrochemical active surface area originating from the WP nanostructures of network-like morphology and the enhanced conductivity caused by the introduction of carbon fibers, the obtained CFs@WP composite, as an integrated hydrogen evolution cathode, exhibits much higher electrocatalytic activity for hydrogen evolution than pure WP nano-/micro-particles after toasting their corresponding suspension onto bare CFs. This catalyst could, in 0.5 mol·L−1 H2SO4, deliver a current density of 10 and 100 mA·cm−2 respectively at the over-potential of merely 137 mV and 215 mV, and present a small Tafel slope of 69 mV·dec−1 as well as excellent stability at various current densities, although it may exhibit relatively inferior catalytic activity in hydrogen evolution in neutral and alkaline conditions. The present strategy may also offer a straight-forward model to enhance the hydrogen evolution activity of other TMPs catalysts.

A series of La-doped BiOCl hierarchical, flower-like nano-/micro-structures (NMFs) with ginkgo-leaf-like “petals” were prepared by etching La-doped Bi 2 O 3 films in HCl solution at room temperature. For the La-doped Bi 2 O 3 films, they were fabricated through hot-dipping Bi 2 O 3 thin films in La 2 O 3 powder at 650 °C. Microstructure examination revealed that the ginkgo-leaf-like La-doped BiOCl petals have a multilayered structure consisting of several ultra-thin nanosheets with different radii due to the external-to-internal etching process. The investigation on their formation mechanism revealed that the La-doped BiOCl hierarchical NMFs grew anisotropically through Ostwald ripening mechanism. Besides, the photodegradation of rhodamine B under simulated sunlight irradiation revealed that the La-doped BiOCl hierarchical NMFs possessed higher performance than pure BiOCl sample. And the active species trapping tests indicated that the photogenerated holes were the main active radicals for the degradation of rhodamine B.

To determine the etiopathogenesis of diabetic cataract by studying changes in relative expressions of silent information regulator protein-1 (SIRT1) and P53 in rat lens epithelial cells (LECs) in experimentally induced diabetes mellitus (DM).Six-week-old male SD rats (n = 120) were randomly divided into experimental (n = 80 rats) and control (n = 40 rats) groups. DM was induced in the experimental group (diabetic model) by intraperitoneal (i.p.) injection of 60 mg/kg streptozotocin (STZ). Control group rats were injected similarly with phosphate-buffered saline (PBS). Four and eight weeks after successful induction of DM, relative expressions of SIRT1 and P53 in LECs were analyzed using quantitative real-time (qRT) fluorescence polymerase chain reaction (qRT-PCR) and Western blot analysis.Expression of both SIRT1 and P53 was observed in LECs of control and experimental group rats at 4 and 8 weeks but was significantly greater in experimental compared with control group rats (p 0.05).Expression of both SIRT1 and P53 increases in the early stages of diabetic cataract formation, indicating that they play potentially important roles in the pathogenesis of diabetic cataract.

Enhancing the hydrogen evolution reaction (HER) performance of electrocatalysts is essential for developing clean energy, in which doping is one of the most effective ways. In this work, praseodymium-doped NiCoP nanowire arrays grown on nickel foam (Pr-NiCoP NWAs/NF) as electrocatalysts were synthesized through hydrothermal reaction and low temperature phosphating. The subsequent tests revealed that the introduction of Pr can modulate the morphology, density of the active sites and electrical conductivity of the NiCoP NWAs/NF. Thereby, the Pr-NiCoP NWAs/NF realized the fast reaction kinetics and exceptional HER performance. When the additive molar amount of Pr is 10%, Pr-NiCoP NWAs/NF electrode exhibited the highest electrocatalytic activity. Its overpotential corresponding to current density of 10 mA•cm−2 were 91 and 88 mV in 0.5 mol•L−1 H2SO4 and 1 mol•L−1 KOH, the Tafel slope of which were 45.5 and 69.2 mV•dec−1, respectively. Further, this work provides a promising strategy to explore highly efficient HER electrocatalysts.

Nowadays, it is still a great challenge to explore highly active and stable noble-metal-free electrocatalysts for sustainable overall water splitting. In this work, a novel electrode of three-dimensional network-like Ni2P-MoS2 heterogeneous nanosheet arrays on carbon cloth (HNSAs/CC) was designed and fabricated by a two-step strategy. Benefiting from the unique 3D hierarchical architecture, large specific surface area, synergistic effects between Ni2P and MoS2, and the support of highly conductive carbon cloth, the obtained electrode exhibits superior electrocatalytic activity for hydrogen and oxygen evolution reaction (HER and OER) in 1 mol L−1 KOH aqueous solution with extremely low overpotentials of 78 and 258 mV respectively to deliver a current density of 10 mA cm−2. The electrocatalytic system assembled with the obtained Ni2P-MoS2 HNSAs/CC sample as both anode and cathode for overall water splitting requires an impressively low onset potential of only 1.574 V to attain a current density of 10 mA cm−2 and displays an excellent long-term stability. According to density functional theory calculation, the enhanced water splitting activity could be mainly attributed to the modified interfacial electronic structures and the enhanced thermoneutral adsorption of absorbates on the surface of Ni2P (110) – MoS2 (100) heterostructure. The calculated theoretical overpotentials for HER and OER based on Ni2P (110) – MoS2 (100) heterostructure are 0.019 and 0.279 V, respectively. The facile synthesis method and insights into the HER and OER active interfaces reported here will advance the development of high-performance bifunctional overall water splitting electrocatalysts.

Efficient injection and distribution of nanoparticles in porous media are considered a formidable technical hurdle for injection-based in situ remediation. One approach to enhance the mobility of nanoparticles in an aquifer is to use surface modifiers. In this study, nanoscale magnesia (NMgOs), an innovative and effective remedial material for cadmium (Cd) removal from groundwater, was modified with the negatively charged and eco-friendly humic acid to enhance its mobility in aquifers. A two-dimensional reactor (60 × 50 × 10 cm), with 2 injection wells and 30 monitoring wells was designed, constructed, and sand-packed in the laboratory to simulate a saturated aquifer. The simulated aquifer was pre-contaminated with Cd to simulate a plume in groundwater. The distribution of injected unmodified NMgOs and humic acid-modified NMgOs slurry were evaluated in the reactor. The radius of influence (ROI) of humic acid-modified NMgOs was estimated to be approximately 5 cm based on visual observation, while no ROI was apparent for the unmodified NMgOs because of their aggregation at the bottom of the injection wells. The concentrations of Cd and magnesium (Mg) were monitored in all 30 monitoring wells at different time intervals to evaluate the effectiveness of Cd removal. The breakthrough curve analysis revealed that humic acid enhances the transport of NMgOs in the saturated porous media. Furthermore, the results of scanning electron microscopy-energy dispersive x-ray (SEM–EDX) characterization of silica sand before and after injection of NMgOs verified the presence of 5.78% of Mg from humic acid-modified NMgOs and 0.19% from unmodified NMgOs at 35 cm downgradient of the injection wells, which are consistent with the conclusion drawn from the breakthrough curves.

Regenerative cooling of the high-temperature components in propulsion and power-generation systems plays a paramount role in maintaining the reliability and durability of the systems. In this paper, a mathematical model is developed for studying fluid dynamics and heat-transfer characteristics of the aviation kerosene RP-3 at supercritical pressures. The model accommodates a detailed pyrolytic chemical reaction mechanism, which consists of 18 species and 24 elementary reactions (Jiang, R.; Liu, G.; Zhang, X. Thermal cracking of hydrocarbon aviation fuels in regenerative cooling microchannels. Energy Fuels 2013, 27, 2563−2577). Accurate calculations of thermophysical properties at supercritical pressures are properly incorporated. After rigorous model validations, numerical studies of turbulent heat transfer of RP-3 in a micro cooling tube at a supercritical pressure of 5 MPa are conducted under operating conditions of both constant wall heat flux and constant surface temperature to obtain a fundamental un...

Aviation kerosene is commonly used in combustion and regenerative engine cooling processes in propulsion and power-generation systems, including rocket, scramjet, and advanced gas turbine engines. In this paper, many surrogate models proposed in the open literature are examined for their applicability and accuracy in calculating thermodynamic and transport properties of the China aviation kerosene RP-3 at supercritical pressures, based on the extended corresponding-states methods. The enthalpy change from endothermic decomposition and low heating value from combustion of the jet fuel are also evaluated. Results from a number of simple and representative surrogate models, which contain species components ranging from 1 to 10, are analyzed in detail. Data analyses indicate that a surrogate model with four species is the best choice for thermophysical property calculations under the tested conditions, with fluid temperature up to 650 K at various supercritical pressures. The surrogate model is particularly accurate in predicting the pseudo-critical temperature of aviation kerosene RP-3 at a supercritical pressure. A simple surrogate model containing the n-decane species and a surrogate model containing 10 species are the other two acceptable options. The work conducted herein is of practical importance for theoretical analyses and numerical simulations of various physicochemical processes at engine operating conditions.

The solubility of acid soluble soy protein (ASSP) is poor in the pH range of 4-7. ASSP-dextran conjugates were prepared through the Maillard reaction to increase the solubility and/or dispersibility of ASSP. By using the conjugates and ultrasonication emulsification, stable oil-in-water emulsions with submicrometer-sized droplets were obtained. The factors, such as ASSP conjugation degree, that influence the emulsion stability were investigated. The emulsions were characterized using dynamic light scattering, zeta-potential, and atomic force microscopy. In the ultrasonication process, the increases of surface activity and aggregation of protein result in the formation of stable oil-water interface films. The dextran molecules conjugated to the protein effectively enhance the hydrophilicity and steric repulsion of the oil droplets, and therefore the emulsions are stable against heat treatment, long-term storage, and changes of pH and ionic strength. It was further verified that using protein-polysaccharide conjugates and ultrasonication emulsification is a versatile method for preparing stable emulsions.

A computational fluid dynamics (CFD) model has been developed and applied for numerical studies of fluid flows and heat transfer of the aviation kerosene RP-3 with consideration of fuel pyrolysis and surface coking in a circular cooling tube at a supercritical pressure of 5 MPa. A detailed pyrolytic chemical reaction mechanism, which contains 18 species and 24 elementary reactions, and a modified kinetic model for considering surface coking are incorporated in the CFD model. The effects of the surface heat flux and inlet flow velocity on the complex physicochemical process are examined. Results reveal that the endothermic fuel pyrolysis plays an important role in the heat transfer process, and the equivalent surface heat flux from the endothermic chemical reactions can contribute to around 70% of the total surface heat flux at the high fluid temperature region. As the aviation kerosene RP-3 is thermally decomposed, the main surface coking precursors, propene and aromatics, are produced. As a result, carbon deposition accumulates at the interior surface of the cooling tube, particularly at a low inlet flow velocity and high surface heat flux.

Submicron-size Fe(3)O(4)@silica core/shell microspheres were prepared by sol-gel method. Through coating inert silica shell and adjusting the thickness, the dispersibility of magnetic microspheres in water was greatly improved. The resultant Fe(3)O(4)@silica microspheres with controllable saturation magnetization between 34.3 emu/g and 47.3 emu/g were superparamagnetic. All as-prepared magnetic composite microspheres possessed fleetly magnetic responsivity. The PAA-modified Fe(3)O(4)@silica microspheres were used for selective adsorption and separation of lysozyme, and the experimental results showed that the maximum binding capacity is about 127 mg/g. After surface modification of Fe(3)O(4)@silica with polyacrylic acid (PAA) flexible chains, the binding capacity of Fe(3)O(4)@silica-g-PAA microspheres for lysozyme were 22 times as much as that of pure Fe(3)O(4)@silica microspheres at the same pH condition.