Search results for "Atomi"
showing 10 items of 28717 documents
Effect of Ion Escape Velocity and Conversion Surface Material on H- Production
2011
According to generally accepted models surface production of negative ions depends on ion escape velocity and work function of the surface. We have conducted an experimental study addressing the role of the ion escape velocity on H− production. A converter‐type ion source at Los Alamos Neutron Science Center was employed for the experiment. The ion escape velocity was affected by varying the bias voltage of the converter electrode. It was observed that due to enhanced stripping of H− no direct gain of extracted beam current can be achieved by increasing the converter voltage. The conversion efficiency of H− was observed to vary with converter voltage and follow the existing theories in qual…
TDDFT Analysis of Optical Properties of Thiol Monolayer-Protected Gold and Intermetallic Silver–Gold Au144(SR)60 and Au84Ag60(SR)60 Clusters
2014
The optical absorption spectra of atomistic model structures for experimentally isolated all-gold Au144(SR)60 and intermetallic Au84Ag60(SR)60 clusters are systematically analyzed from linear-response time-dependent density functional theory (LR-TDDFT) and time-dependent density functional perturbation theory (TD-DFPT) calculations. The computed spectra, utilizing the atomistic model for Au144(SR)60 published by us in 2009, reproduce closely the experimental observations for corresponding isolated compounds, reported previously by Kumara and Dass in 2011. A collective dipole oscillation within the metal cores of the all-gold and intermetallic clusters is formed as response to light in the v…
Force Distribution Analysis of Mechanochemically Reactive Dimethylcyclobutene
2013
Internal molecular forces can guide chemical reactions, yet are not straightforwardly accessible within a quantum mechanical description of the reacting molecules. Here, we present a force-matching force distribution analysis (FM-FDA) to analyze internal forces in molecules. We simulated the ring opening of trans-3,4-dimethylcyclobutene (tDCB) with on-the-fly semiempirical molecular dynamics. The self-consistent density functional tight binding (SCC-DFTB) method accurately described the force-dependent ring-opening kinetics of tDCB, showing quantitative agreement with both experimental and computational data at higher levels. Mechanical force was applied in two different ways, namely, exter…
The electronic structure of Ge9[Si(SiMe3)3]3-: a superantiatom complex.
2012
We report on the electronic structure of Ge(9)[Si(SiMe(3))(3)](3)(-). Systematic density functional theory analysis of the electronic shell structure of the cluster and its derivatives reveals that the Ge(9)[Si(SiMe(3))(3)](3)(-) and its neutral counterpart have electronic shells that can be explained using the superatom model. The ligand-core interaction of these complexes is distinctly different from previously identified gold, gallium, and aluminium superatom complexes, indicating an electron-donating rather than electron-withdrawing ligand. We modify the electron-counting rule for this case and introduce a simple picture for superatom and superantiatom complexes. Discussions comparing s…
Delayed and In-beam Spectroscopy on Francium and Astatine Nuclei at the Proton Drip Line
2011
Delayed and in‐beam spectroscopy on francium and astatine nuclei at and beyond the proton drip line has been performed. In neutron deficient astatine nuclei a shift to deformed shapes as a function of decreasing neutron has been obtained. In neutron deficient francium isotope the same shift is evident.
Curvelet-based method for orientation estimation of particles from optical images
2014
A method based on the curvelet transform is introduced to estimate the orientation distribution from two-dimensional images of small anisotropic particles. Orientation of fibers in paper is considered as a particular application of the method. Theoretical aspects of the suitability of this method are discussed and its efficiency is demonstrated with simulated and real images of fibrous systems. Comparison is made with two traditionally used methods of orientation analysis, and the new curvelet-based method is shown to perform better than these tradi- tional methods. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of th…
Coupling high-resolution satellite imagery with ALS-based canopy height model and digital elevation model in object-based boreal forest habitat type …
2014
We developed a classification workflow for boreal forest habitat type mapping. In object-based image analysis framework, Fractal Net Evolution Approach segmentation was combined with random forest classification. High-resolution WorldView-2 imagery was coupled with ALS based canopy height model and digital terrain model. We calculated several features (e.g. spectral, textural and topographic) per image object from the used datasets. We tested different feature set alternatives; a classification accuracy of 78.0 % was obtained when all features were used. The highest classification accuracy (79.1 %) was obtained when the amount of features was reduced from the initial 328 to the 100 most imp…
Evaluation of alveolar cortical bone thickness and density for orthodontic mini-implant placement.
2013
Objective: Mini-implant stability is primarily related to bone quality and quantity. This study evaluated alveolar cortical bone thickness and density differences between interradicular sites at different levels from the alveolar crest, and assessed the differences between adolescents (12-18 years of age) and adults (19-50 years of age), males and females, upper and lower arch, anterior and posterior region of jaws and buccal and oral side. Study Design: In this retrospective study, 48 Computed Tomography scans, performed for oral surgery purposes were selected from dental records of 3,223 Caucasian orthodontic patients. The SimPlant software (Materialise, Leuven, Belgium) was used to measu…
The Case of Insertional Adductor Tendinopathy of an International-Level 3,000-m Steeplechase Runner
2021
Background: Groin pain is a frequent condition among athletes. One of the causes of groin pain is tendinopathy, a frequently diagnosed medical condition, which can also occur in the adductor muscles. Despite the high prevalence of this medical condition among athletes, it is infrequent to observe tendinopathic groin pain in steeplechase runners. The aim of this case study is to describe the case of an international-level 3,000-m steeplechase runner with groin pain, who was subsequently diagnosed with adductor insertional tendinopathy.Case Presentation: We present the case of an Italian 3,000-m steeplechase and long distance runner, Ala Zoghlami (180 cm, 57 kg), with groin pain, diagnosed as…
Intravenous iron therapy in patients with heart failure. A double-edged sword
2013
We read with interest the article of Beck-da-Silva et al., who recently concluded that intravenous (IV) iron seems to be superior over oral supplementation for improving functional capacity of heart failure patients [1]. Irrespective of the study design, involving comparison of functional outcomes between two different means of iron supplementation, we raise some clinical issues about the rationale underlying this investigation. According to the data published by Beck-da-Silva et al., the modest number of patients (n = 23) enrolled in this multicenter investigation had moderate anemia (i.e., hemoglobin concentration comprised between 90 and 120 g/L) but no evidence of iron deficiency, which…