Search results for " function"

Electronic Structure and Optical Properties of the Intrinsically Chiral 16-Electron Superatom Complex [Au20(PP3)4]4+

2014

The recently solved crystal structure of the [Au20(PP3)4]Cl4 cluster (PP3: tris(2-(diphenylphophino)ethyl)phosphine) is examined using density functional theory (DFT). The Au20 core of the cluster is intrinsically chiral by the arrangement of the Au atoms. This is in contrast to the chirality of thiolate-protected gold clusters, in which the protecting Au-thiolate units are arranged in chiral patterns on achiral cores. We interpret the electronic structure of the [Au20(PP3)4]Cl4 cluster in terms of the superatom complex model. The 16-electron cluster cannot be interpreted as a dimer of 8-electron clusters (which are magic). Instead, a superatomic electron configuration of 1S(2) 1P(6) 1D(6) …

A DFT Study of Linear Gold–Thiolate Superclusters Absorbing in the Therapeutic NIR Window

2015

A series of linear clusters up to an aspect ratio of 1:6, formed as multimers of smaller clusters with an icosahedral Au13(5+) core having an eight-electron superatom configuration, are computationally predicted to have a greatly enhanced size-dependent absorption in the near-infrared (NIR) region extending to the biologically important NIR window. A novel structural model is presented for the previously isolated thiol-stabilized Au54(SR)30 cluster, where the metal core is formed as a heterodimer of the cores of the known Au25(SR)18(-/0) and Au38(SR)24 clusters.

The Role of the Anchor Atom in the Ligand of the Monolayer-Protected Au25(XR)18– Nanocluster

2015

We present a density functional theory (DFT) investigation on the role of the anchor atom and ligand on the structural, electronic, and optical properties of the anionic Au25(XR)18– nanocluster (X = S, Se, Te; R = H, CH3, and (CH2)2Ph). Substituting the anchor atom with other group 16 elements induces subtle changes in the Au–Au and Au–X bond lengths and polarization of the covalent bond. The changes in the electronic structure based on substituting both the anchor and R groups are presented through careful analysis of the density of states and theoretical determined optical spectra. We give a detailed side-by-side comparison into the structural, electronic, and optical properties of Au25(X…

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…

Crystal Structures and Density Functional Theory Calculations of o-and p-Nitroaniline Derivatives: Combined Effect of Hydrogen Bonding and aromatic i…

2013

The interplay of strong and weak hydrogen bonds, dipole–dipole interactions, and aromatic interactions of o- and p-nitroaniline derivatives was studied by combining crystal structure analysis and density functional theory (DFT) calculations. Crystal structures of four 2-nitroaniline derivatives, 2-((2-nitrophenyl)amino)ethyl methanesulfonate (1A), 2-((2-nitrophenyl)amino)ethyl 4-methylbenzenesulfonate (2A), N,N′-((1,3-phenylenebis(oxy))bis(ethane-2,1-diyl))bis(2-nitroaniline) (3A), and N-(2-chloroethyl)-2-nitroaniline (4A), and crystal structures of three 4-nitroaniline derivatives, 2-((4-nitrophenyl)amino)ethyl methanesulfonate (1B), 2-((4-nitrophenyl)amino)ethyl 4-methylbenzenesulfonate (…

Perceived Opportunities for Physical Activity and Willingness to Be More Active in Older Adults with Different Physical Activity Levels

2021

This study examined equity in physical activity (PA) by investigating whether perceived opportunity for PA was associated with willingness to be more active. Among community residents (75, 80, or 85 years old, n = 962) perceived opportunity for PA (poor and good), willingness to be more active (not at all, a bit, and a lot), and level of PA (low, moderate, and high) were assessed via questionnaires. Multinomial logistic regression showed that physical activity moderated the association between poor opportunity and willingness to increase PA. Among those with moderate PA, poor opportunity for PA increased the odds of willingness to be a lot more active (multinomial odds ratio, mOR 3.90, 95% …

Task-Specific Organic Salts and Ionic Liquids Binary Mixtures: A Combination to Obtain 5-Hydroxymethylfurfural From Carbohydrates

2019

The increase in energy demand and depletion of fossil fuels are among major issues of modern society. Valorization and transformation of raw materials in products of industrial value represents a challenge. This justifies the growing interest of scientific research towards the identification of suitable media and methodologies able to pursue above goals, paying attention to matter of sustainability. On this subject, we studied sulfonic-acid functionalized diimidazolium salts as catalysts for the conversion of fructose and sucrose to 5-hydroxymethylfurfural (5-HMF) in an ionic liquid mixture. In general, using these salts allowed us to obtain 5-HMF in good yields from both substrates in mild…

Ultraviolet B radiation induced alterations in immune function of fish : in relation to habitat preference and disease resistance

2009

Runsas altistuminen auringolle on tunnetusti haitallista ihmisten ja eläinten hyvinvoinnille. Eveliina Markkula tutki väitöskirjatyössään, miten ultravioletti B (UVB) -säteilylle altistuminen vaikuttaa kalojen vastustuskykyyn ja tautialttiuteen.- Ilmakehän otsonikerroksen oheneminen viime vuosikymmenten aikana on johtanut UVB-säteilyn lisääntymiseen maan pinnalla. UVB-säteily tunkeutuu myös kirkkaisiin järvi- ja merivesiin ja voi näin aiheuttaa haittaa kaloille, Markkula kertoo.UVB-säteilyn on jo aiemmin todettu lisäävän kalojen varhaisten elinvaiheiden epämuodostumia ja kuolleisuutta. Kertaluonteinenkin altistuminen lampuilla tuotetulle UVB-säteilylle aiheuttaa muutoksia kalan immuunijärje…

Trans-cranial MRI-guided Focused Ultrasound Surgery (tcMRgFUS): preliminary Italian (and world-first) experience at 1,5 Tesla (first 5 patient treate…

2015

Trans-cranial MRI-guided Focused Ultrasound Surgery (tcMRgFUS): preliminary Italian (and world-first) experience at 1,5 Tesla.

2015

PURPOSE: We present our preliminary results achieved with the first Italian installation of a trans-cranial MRI-guided Focused Ultrasound Surgery (tcMRgFUS) certified system for functional neurosurgery. Moreover, to our knowledge, this is the world-first tcMRgFUS system ever installed on a 1.5T MRI unit. Technical issues faced to achieve a safe and effective treatment will be discussed focusing on MR high-resolution live imaging and thermometry sequences optimization. METHOD AND MATERIALS: Patient enrollment was based on indication for functional neurosurgery and evidence of medication-refractory disease; a detailed medical history has been collected together with a complete clinical examin…