Search results for "surface"
showing 10 items of 9345 documents
Quantitative molecular plating of large-area 242Pu targets with improved layer properties
2015
Abstract For measurements of the neutron-induced fission cross section of 242Pu, large-area (42 cm2) 242Pu targets were prepared on Ti-coated Si wafers by means of constant current density molecular plating. Radiochemical separations were performed prior to the platings. Quantitative deposition yields (>95%) were determined for all targets by means of alpha-particle spectroscopy. Layer densities in the range of 100–150 μg/cm2 were obtained. The homogeneity of the targets was studied by radiographic imaging. A comparative study between the quality of the layers produced on the Ti-coated Si wafers and the quality of layers grown on normal Ti foils was carried out by applying scanning electron…
Using photoelectron emission microscopy with hard-X-rays
2001
We present several successful test cases of using photoelectron emission microscopy (PEEM) for photon energy up to 25 keV. First, the full extended X-ray absorption fine structure analysis was implemented in areas as small as 100 mum(2) for transition-metal K edge absorption spectra and, therefore, demonstrated the feasibility of combining structural and chemical analysis with hard-X-ray absorption spectroscopy with high lateral resolution. We also show that PEEM can be used in a transmission (radiography) mode as an imaging detector for hard-X-ray, This approach again leads to the unprecedented 0.3 mum lateral resolution, particularly critical for the use of coherence-based phase contrast …
A Novel Na(I) Coordination Complex with s-Triazine Pincer Ligand: Synthesis, X-ray Structure, Hirshfeld Analysis, and Antimicrobial Activity
2023
The pincer ligand 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (bpmt) was used to synthesize the novel [Na(bpmt)2][AuCl4] complex through the self-assembly method. In this complex, the Na(I) ion is hexa-coordinated with two tridentate N-pincer ligands (bpmt). The two bpmt ligand units are meridionally coordinated to Na(I) via one short Na-N(s-triazine) and two slightly longer Na-N(pyrazole) bonds, resulting in a distorted octahedral geometry around the Na(I) ion. In the coordinated bpmt ligand, the s-triazine core is not found to be coplanar with the two pyrazole moieties. Additionally, the two bpmt units are strongly twisted from one another by 64.94°. Based on Hirshf…
Encapsulation of Xenon by a Self-Assembled Fe4L6 Metallosupramolecular Cage
2015
We report (129)Xe NMR experiments showing that a Fe4L6 metallosupramolecular cage can encapsulate xenon in water with a binding constant of 16 M(-1). The observations pave the way for exploiting metallosupramolecular cages as economical means to extract rare gases as well as (129)Xe NMR-based bio-, pH, and temperature sensors. Xe in the Fe4L6 cage has an unusual chemical shift downfield from free Xe in water. The exchange rate between the encapsulated and free Xe was determined to be about 10 Hz, potentially allowing signal amplification via chemical exchange saturation transfer. Computational treatment showed that dynamical effects of Xe motion as well as relativistic effects have signific…
Urea Glass Route as a Way to Optimize YAGG:Ce3+,Cr3+,Pr3+ Nanocrystals for Persistent Luminescence Applications
2022
A new approach for the synthesis of Y3Al2Ga3O12 (YAGG) nanophosphors allowing the preparation of crystallites with sizes starting from 45 nm is presented. The controllability of the energy and trap density of the resulting material samples by annealing temperature was confirmed by thermoluminescence (TL) measurements. It has been shown that the annealing of samples at temperatures up to 1300 degrees C does not cause any substantial growth of crystallites, still remaining below 100 nm, but leads to changes in the activation energy of the persistent luminescence (PersL) process. On the other hand, annealing above 1400 degrees C results in grain growth on the submicron scale, which was confirm…
Increased electron donor and electron acceptor characters enhance the adhesion between oil droplets and cells of Yarrowia lipolytica as evaluated by …
2003
The adhesion of methyl ricinoleate droplets to cells of the yeast Yarrowia lipolytica was investigated. A new cytometric method, relying on the double staining of fatty globules with Nile Red and of cells with Calcofluor, enabled us to quantify methyl ricinoleate droplet adhesion to cells precultured on a hydrophilic or on a hydrophobic carbon source. In this last case, droplet adsorption was enhanced and a MATS (microbial adhesion to solvents) test revealed that this increase was due to Lewis acid-base interactions and not to an increase in the hydrophobic properties of the cell surface. These preliminary results demonstrate that the developed cytometric method is promising for various app…
Acoustic vibrations of metal nanoparticles: high order radial mode detection
2004
The vibrational radial modes of silver nanospheres embedded in a glass matrix are investigated using a high sensitivity femtosecond pump-probe technique. The results yield evidence for coherent launching of the fundamental and higher order radial modes in agreement with a sphere dilation mediated excitation model. The results are consistent with low-frequency Raman scattering experiments.
Olive yield as a function of soil moisture dynamics
2011
This study introduces a water-driven crop model aiming to quantitatively link olive yield to climate and soil moisture dynamics using an ecohydrological approach. A mathematical model describing soil moisture, evapotranspiration and assimilation dynamics of olive orchards is developed here. The model is able to explicitly reproduce two different hydroclimatic phases in Mediterranean areas: the well-watered conditions in which evapotranspiration and assimilation assume their maximum values and the real conditions where the limitations induced by soil moisture availability are taken into account. Annual olive yield is obtained by integrating the carbon assimilation during the growing season, …
Physicochemical Investigation of the Solubilization of Ytterbium Nitrate in AOT Reverse Micelles and Liquid Crystals
2006
A wide investigation of the solubilization of the water-soluble salt Yb(NO3)(3) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles and AOT liquid crystals has been carried out. After saturation of water/AOT/organic solvent w/o microemulsions with pure Yb(NO3)(3), the Yb(NO3)(3)/AOT composites were prepared by complete evaporation under vacuum of the volatile components (water and organic solvent) of the salt-containing microemulsions. It was observed that these composites can be totally dissolved in pure n-heptane or CCl4, allowing the solubilization of a noticeable amount of Yb(NO3)(3) in quite dry apolar media. By UV-vis-NIR, FT-IR, and H-1 NMR spectroscopies, some informati…
Solvent-free synthesis of ZIFs: a route toward the elusive Fe(II) analogue of ZIF-8
2019
Herein we report the synthesis of an elusive metal-organic framework, the iron(II) analogue of ZIF-8 with the formula Fe(2-methylimidazolate) , here denoted as MUV-3. The preparation of this highly interesting porous material, inaccessible by common synthetic procedures, occurs in a solvent-free reaction upon addition of an easily detachable template molecule, yielding single crystals of MUV-3. This methodology can be extended to other metals and imidazolate derivatives, allowing the preparation of ZIF-8, ZIF-67, and the unprecedented iron(II) ZIFs Fe(2-ethylimidazolate) and Fe(2-methylbenzimidazolate) . The different performance of MUV-3 toward NO sorption, in comparison to ZIF-8, results …