نتایج جستجو برای: cerium
تعداد نتایج: 3705 فیلتر نتایج به سال:
The effect of nanomaterials on biota under realistic environmental conditions is an important question. However, there is still a lack of knowledge on how different illumination conditions alter the toxicity of some photocatalytic nanomaterials. We have investigated how environmentally relevant UV-A exposure (intensity 8.50 ± 0.61 W/m(2), exposure dose 9.0J/cm(2)) affected the toxicity of ceriu...
Primary aquo species of tetravalent cerium (Ce(IV)) in perchloric acid has been identified as a single oxo-bridging dinuclear complex, not a mononuclear one, by extended X-ray absorption fine structure (EXAFS) spectroscopy combined with density functional theory (DFT) calculations.
A stable sol of cerium oxide nanoparticles forms spontaneously when cerium(iv) ammonium nitrate (CAN) is dissolved in room-temperature water at mM concentrations. Electron microscopy experiments reveal the formation of highly crystalline cerium oxide particles several nm in diameter and suggest that they are formed from amorphous particles that are similar in size. Under the low pH conditions o...
The stability of palladium supported on ceria (Pd/CeO2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the s...
The germanide Ce2Rh3Ge5 was synthesized from the elements in a bismuth flux, and the structure was refined from single-crystal X-ray diffractometer data: U2Co3Si5 type, Ibam, a = 1010.1(2), b = 1210.4(2), c = 599.1(1) pm, wR = 0.0596, 760 structure factors, 31 variables. The rhodium and germanium atoms build up a three-dimensional [Rh3Ge5] network (242 – 269 pm Rh–Ge; 300 pm Rh–Rh; 266 pm Ge–Ge...
The effects of cerium and lanthanum on the vegetative and reproductive growth of Arabidopsis thaliana were investigated. Addition of cerium (III) nitrate (0.5-50μM) and/or lanthanum nitrate (0.5-50μM) to the culture medium and the potting mix showed varied results. Pot trials were done with uniform conditions for light, water and temperature. Factors examined include root length, height, number...
Interactions of nanoparticles with biological matter-both somatically and in nature-draw scientists' attention. Nanoparticulate systems are believed to be our saviors, acting as versatile drug delivery vehicles. However, they can also cause life-threatening bodily damage. One of the most important properties of nanocrystalline cerium dioxide is its antioxidant activity, which decreases the abun...
Methanol, formaldehyde, carbon monoxide, and propylene conversion were examined in a laboratory flow reactor over three base-metal containing alumina-supported palladium (Pd) catalysts in addition to Pd on y-alumina catalyst. The base metals were cerium, barium, and a combination of the two. Experiments were performed to determine the effect of air to fuel ratio on lightoff temperatures of vari...
The stationary functional of the density functional plus embedded dynamical mean field theory formalism to perform free energy calculations and structural relaxations is implemented for the first time. Here, the first order error in the density leads to a much smaller, second order error in the free energy. The method is applied to several well-known correlated materials: metallic SrVO_{3}, Mot...
To enable the transition away from a fossil-fuel-based energy economy, it is essential to address, in addition to energy extraction from sustainable resources, the problem of energy storage. We pursue in this work a storage strategy that relies on the capacity of selected nonstoichiometric metal oxides to uptake and release oxygen. Specifically, doped cerium oxide (ceria), a relatively abundant...
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