XPS and NEXAFS study of fluorine modified TiO2 nano-ovoids reveals dependence of Ti3+ surface population on the modifying agent

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/)Crystalline titanium dioxide was synthesised under mild conditions by the thermal degradation of peroxotitanic acid in the presence of a number of fluoride-containing surface modifying agents (NH4F, NH4BF4, NH4PF6, NBu4F, NBu4BF4, NBu4PF6). The resulting materials were characterised by PXRD, SEM, HRTEM, XPS and NEXAFS. Particle phase, size, and surface area were noticeably affected by the choice of surface modifying agent. Both the cation and anion comprising the modifying agent affect the surface Ti3+ population of the materials, with two apparent trends observed: F− > BF4− > PF6− and NBu4+ > NH4+. All materials displayed evidence of fluorine doping on their surfaces, although no evidence of bulk doping was observed

Chemically-synthesised, atomically-precise gold clusters deposited and activated on titania

Synchrotron XPS was used to investigate a series of chemically-synthesised, atomically-precise gold clusters Au(n)(PPh₃)(y) (n = 8, 9, 11 and 101, with y depending on cluster size) immobilized on titania nanoparticles. The gold clusters were washed with toluene at 100 °C or calcined at 200 °C to remove the organic ligand. From the position of the Au 4f₇/₂ peak it is concluded that cluster size is not altered through the deposition. From the analysis of the phosphorous spectra, it can be concluded that the applied heat treatment removes the organic ligands. Washing and calcination leads to partial oxidation and partial agglomeration of the clusters. Oxidation of the clusters is most likely due to the interaction of the cluster core with the oxygen of the titania surface after removal of ligands. The position of the Au 4f₇/₂ peak indicates that the size of the agglomerated clusters is still smaller than that of Au₁₀₁.David P. Anderson, Jason F. Alvino, Alexander Gentleman, Hassan Al Qahtani, Lars Thomsen, Matthew I. J. Polson, Gregory F. Metha, Vladimir B. Golovko and Gunther G. Andersso

Lipid Classes and Fatty Acid Patterns are Altered in the Brain of γ-Synuclein Null Mutant Mice

The well-documented link between α-synuclein and the pathology of common human neurodegenerative diseases has increased attention to the synuclein protein family. The involvement of α-synuclein in lipid metabolism in both normal and diseased nervous system has been shown by many research groups. However, the possible involvement of γ-synuclein, a closely-related member of the synuclein family, in these processes has hardly been addressed. In this study, the effect of γ-synuclein deficiency on the lipid composition and fatty acid patterns of individual lipids from two brain regions has been studied using a mouse model. The level of phosphatidylserine (PtdSer) was increased in the midbrain whereas no changes in the relative proportions of membrane polar lipids were observed in the cortex of γ-synuclein-deficient compared to wild-type (WT) mice. In addition, higher levels of docosahexaenoic acid were found in PtdSer and phosphatidylethanolamine (PtdEtn) from the cerebral cortex of γ-synuclein null mutant mice. These findings show that γ-synuclein deficiency leads to alterations in the lipid profile in brain tissues and suggest that this protein, like α-synuclein, might affect neuronal function via modulation of lipid metabolism

Benzyl alcohol oxidation using gold catalysts derived from Au8 clusters on TiO2

Atomically-precise gold clusters have gained attraction in catalysis due to high fraction of low-coordinated gold atoms, unique structural geometry and ligand effect. Phosphine-ligated gold clusters offer an advantage in the light of the labile gold-phosphorous bond for easy ligand removal. Here, heterogeneous gold catalysts were prepared by depositing atomically-precise phosphine-ligated gold clusters, Au8(PPh3)8(NO3)2 onto anatase-phase TiO2 nanoparticles. The catalysts were then calcined under two different conditions: O2(Au8/TiO2:O2) and O2 followed by H2(Au8/TiO2:O2–H2) at 200°C, to dislodge phosphine ligands from the Au core. It was found that Au8/TiO2:O2–H2 catalyst showed a decent catalytic activity in benzyl alcohol oxidation while Au8/TiO2 and Au8/TiO2:O2 were completely inactive. Such results imply that small-size gold clusters (2–3nm) alone do not always contribute to high catalytic activity of gold catalysts. It is suggested that the presence of NO3− species defines the catalytic activity of supported gold clusters in benzyl alcohol oxidation in the case of these catalysts and reinforces our initial claim in the previous work

Нейронная сеть для решения задач прогнозирования

Головко Владимир Адамович, Савицкий Юрий Викторович, Гладыщук Виталий Б. Нейронная сеть для решения задач прогнозированияIn this paper are presents and investigates the various modifications of gradient descent method for Back-Propagation algorithm. Opportunity on reduction of neural network training time and increasing of training algorithm stability are considered The particular expressions for choosing of optimum steps of training neurons with sigmoid and linear functions of output activity are received. Results of experiments on predicting of various mathematical series and functions by using neural networks are presented The analysis of speed training neural network for offered training algorithm demonstrates its advantage before classical Back-Propagation algorithm

Предварительная обработка информации с датчиков для контроля надежности мобильного робота

Головко Владимир Адамович, Климович А. Н., Гладыщук В. Б. Предварительная обработка информации датчиков для контроля надежности мобильного роботаThe neural system for orientation of the robot on unfamliar district in this article is considered. In basis it lays several of the neural networks, which are united in the uniform system The primal problem o f the system is, that with an inexact іnfonration from sensor devices should to supply correct control of the robot

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

Glycoscience, despite its myriad of challenges, promises to unravel the causes of, potential new detection methods for, and novel therapeutic strategies against, many disease states. In the last two decades, glyco-gold nanoparticles have emerged as one of several potential new tools for glycoscientists. Glyco-gold nanoparticles consist of the unique structural combination of a gold nanoparticle core and an outer-shell comprising multivalent presentation of carbohydrates. The combination of the distinctive physicochemical properties of the gold core and the biological function/activity of the carbohydrates makes glyco-gold nanoparticles a valuable tool in glycoscience. In this review we present recent advances made in the use of one type of click chemistry, namely the azide–alkyne Huisgen cycloaddition, for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

Establishing a Au Nanoparticle Size Effect in the Oxidation of Cyclohexene Using Gradually Changing Au Catalysts

The effect of the size of gold nanoparticles on their catalytic activity in aerobic oxidation of cyclohexene was established using supported gold nanoparticles that gradually undergo a change in size during the catalytic reaction. Two triphenylphosphine-stabilized clusters, Au₉(PPh₃)₈(NO₃)₃ and Au₁₀₁(PPh₃)₂₁Cl₅, were synthesized and deposited on SiO₂. The clusters did not retain their structure during the catalytic reaction; larger particles with mean diameters of ∼5–10 nm gradually formed. By combining kinetic experiments with the monitoring of catalyst transformations using transmission electron microscopy, diffuse-reflectance ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy, we showed that catalytic activity appeared only after >2 nm Au⁰ particles had formed, while intact clusters and phosphine-free <2 nm particles were inactive in cyclohexene oxidation under the studied conditions

Investigation of Phosphine Ligand Protected Au 13 Clusters on Defect Rich Titania

Atomically precise chemically synthesized gold clusters protected by diphenylphosphine ligands [(Au13(dppe)5Cl2)Cl3] (dppe = 1,2-bis(diphenylphosphino)ethane) were deposited onto a defect-rich, atomic layer deposited titania surface prepared by heating and subsequently sputtering the titania under ultrahigh vacuum (UHV). The gold clusters deposited onto the pretreated titania were heated at 200 °C for 20 min under UHV with the aim to remove the ligands protecting the gold core of the clusters. The change in the electronic structure and the chemical composition after deposition after aforementioned heat treatment was investigated using metastable induced electron spectroscopy (MIES) and X-ray photoelectron spectroscopy (XPS). The MIES data allow identification of the density of states (DOS) of the deligated Au13 clusters on the titania to be made. The DOS of the Au13 are found to be similar to those previously found for Au9 clusters on sputtered ALD titania but have shifted binding energies. The differences in DOS of Au13 and Au9 are discussed.The work is supported by the US army project FA5209-16-R001

Aggregation Behavior of Ligand-Protected Au9 Clusters on Sputtered Atomic Layer Deposition TiO2

[Au9(PPh3)8)](NO3)3 (Au9) clusters were deposited onto sputtered ALD titania surfaces. Atomic force microscopy (AFM) was used to determine the height and distributions of the Au9 clusters over the titania surface fabricated using atomic layer deposition (ALD). Synchrotron X-ray photoelectron spectroscopy (XPS) was used to derive information about the degree of agglomeration of the Au9 clusters due to the annealing process. Both AFM and XPS show that the Au9 clusters deposited on ALD titania are partially agglomerated after annealing. Deposition of the [Au9(PPh3)8)](NO3)3 clusters on sputtered ALD titania is compared with deposition of the same cluster on titania nanosheets of previous work.H.S.A.Q acknowledges the King Abdullah Foreign Scholarship Program (KASP-Saudi Arabia) for providing scholarship support. We also acknowledge the support provided by the Flinders University−NIMS partnership. The XPS data were collected on the soft X-ray beamline at the Australian Synchrotron, Victoria, Australia (Grant AS123/SXR/5335)