Gold Clusters: From the Dispute on a Gold Chair to the Golden Future of Nanostructures

The present work opens with an acknowledgement to the research activity performed by Luciana Naldini while affiliated at the Università degli Studi di Sassari (Italy), in particular towards gold complexes and clusters, as a tribute to her outstanding figure in a time and a society where being a woman in science was rather difficult, hoping her achievements could be of inspiration to young female chemists in pursuing their careers against the many hurdles they may encounter. Naldini’s findings will be a key to introduce the most recent results in this field, showing how the chemistry of gold compounds has changed throughout the years, to reach levels of complexity and elegance that were once unimagined. The study of gold complexes and clusters with various phosphine ligands was Naldini’s main field of research because of the potential application of these species in diverse research areas including electronics, catalysis, and medicine. As the conclusion of a vital period of study, here we report Naldini’s last results on a hexanuclear cationic gold cluster, [(PPh3)6Au6(OH)2]2+, having a chair conformation, and on the assumption, supported by experimental data, that it comprises two hydroxyl groups. This contribution, within the fascinating field of inorganic chemistry, provides the intuition of how a simple electron counting may lead to predictable species of yet unknown molecular architectures and formulation, nowadays suggesting interesting opportunities to tune the electronic structures of similar and higher nuclearity species thanks to new spectroscopic and analytical approaches and software facilities. After several decades since Naldini’s exceptional work, the chemistry of the gold cluster has reached a considerable degree of complexity, dealing with new, single-atom precise, materials possessing interesting physico-chemical properties, such as luminescence, chirality, or paramagnetic behavior. Here we will describe some of the most significant contributions.

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Potential of Biochar Derived from Agricultural Residues for Sustainable Management

Sustainability ◽

10.3390/su13158147 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8147

Author(s):

Sasiwimol Khawkomol ◽

Rattikan Neamchan ◽

Thunchanok Thongsamer ◽

Soydoa Vinitnantharat ◽

Boonma Panpradit ◽

...

Keyword(s):

Chemical Properties ◽

Agricultural Residues ◽

Hydroxyl Groups ◽

Asian Countries ◽

Heating Value ◽

Coconut Husk ◽

High Heating Value ◽

Horizontal Drum ◽

Physical And Chemical ◽

And Chemical Properties

A horizontal drum kiln is a traditional method widely used in Southeast Asian countries for producing biochar. An understanding of temperature conditions in the kiln and its influence on biochar properties is crucial for identifying suitable biochar applications. In this study, four agricultural residues (corncob, coconut husk, coconut shell, and rice straw) were used for drum kiln biochar production. The agricultural residues were turned into biochar within 100–200 min, depending on their structures. The suitability of biochar for briquette fuels was analyzed using proximate, ultimate, and elemental analysis. The biochar’s physical and chemical properties were characterized via bulk density, iodine number, pHpzc, SEM, and FTIR measurements. All biochars had low O/C and H/C ratios and negative charge from both carbonyl and hydroxyl groups. Coconut husk and shell biochar had desirable properties such as high heating value and a high amount of surface functional groups which can interact with nutrients in soil. These biochars are thus suitable for use for a variety of purposes including as biofuels, adsorbents, and as soil amendments.

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Effect of High-Temperature Defibration on the Chemical Structure of Hardwood

Holzforschung ◽

10.1515/hf.2002.009 ◽

2002 ◽

Vol 56 (1) ◽

pp. 51-59 ◽

Cited By ~ 16

Author(s):

P. Widsten ◽

J.E. Laine ◽

P. Qvintus-Leino ◽

S. Tuominen

Keyword(s):

High Temperature ◽

Lignin Content ◽

Bulk Composition ◽

Chemical Properties ◽

Water Extract ◽

Fiber Surface ◽

Phenolic Hydroxyl ◽

Hydroxyl Groups ◽

Surface Chemical ◽

Alkyl Aryl

Summary The present paper aims at elucidating the effect of high-temperature defibration at different temperatures on the bulk and surface chemical properties of defibrated birch, aspen and eucalypt. The results indicate that defibration of these hardwoods results in partial depolymerization of fiber lignin via (homolytic) cleavage of interunit alkyl-aryl (β-O-4) ether bonds. This increases the phenolic hydroxyl content and produces relatively stable (phenoxy) radicals. Syringyl-type lignin is more extensively depolymerized than guaiacyl-type lignin. Defibration generates water-extractable material, which is enriched in hemicellulose-derived carbohydrates and has a substantial content of aromatic compounds rich in phenolic hydroxyl groups. The amount of water-extract and the extent of lignin interunit ether bond cleavage increase with an increase in defibration temperature. The differences between various hardwood species in this respect are small. The surface chemical composition of the fibers differs considerably from their bulk composition, but is not significantly influenced by variations in defibration temperature. Lipophilic extractives cover a large portion of the fiber surface, while the lignin content of lipophilic extractives-free fiber surfaces is 2–3 times as high as the bulk lignin content of the fibers.

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Scale-up of a NiMoP/γAl2O3 catalyst for the hydrotreating and mild hydrocracking of heavy gasoil

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2018094 ◽

2019 ◽

Vol 74 ◽

pp. 22 ◽

Cited By ~ 1

Author(s):

Ricardo Prada Silvy

Keyword(s):

Scale Up ◽

Catalyst Support ◽

Chemical Properties ◽

Pilot Scale ◽

Solid Particles ◽

Metallic Surface ◽

Hydroxyl Groups ◽

Alumina Surface ◽

Distribution Profile ◽

Surface Hydroxyl

This contribution shows the acquired experience during the scale-up of a NiMoP/γAl2O3 catalyst employed for the hydrotreating and mild hydrocracking of heavy gasoil. Three different strategies were adopted for preparing catalyst batches at pilot scale. They consisted on co-impregnation of γ-alumina extrudates with aqueous solutions containing Ni and Mo salts and phosphoric acid in one or two successive steps. The textural, chemical composition, mechanical strength, metallic surface dispersion and elemental radial distribution profile properties were influenced by the impregnation procedure employed. The co-impregnation with diluted Ni, Mo and P solutions in two successive steps is the best way to prepare the catalyst. This procedure provides a catalyst that exhibits better physico-chemical properties and catalytic activity profile than the other impregnation methods investigated. Heat and mass transfer limitations became very important when preparing catalysts in large quantities. The diffusion intra-particle and extra-particle was observed influenced by the density and viscosity properties of the metallic solution, the liquid-solid contact angle, the reactivity of phosphate, polymolybdate and phosphomolybdate species with the alumina surface hydroxyl groups, the raise of temperature produced in the solid particles during the initial impregnation step and the porosity properties of the catalyst support. It was concluded that the fine control of the metal distribution on the alumina surface during the impregnation is crucial for producing highly active uniform catalysts.

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ChemInform Abstract: PHYSICAL AND CHEMICAL PROPERTIES OF INACTIVE SURFACE HYDROGEN-BONDED HYDROXYL GROUPS

Chemischer Informationsdienst ◽

10.1002/chin.198447027 ◽

1984 ◽

Vol 15 (47) ◽

Author(s):

S. KONDO ◽

H. YAMAUCHI ◽

Y. KAJIYAMA ◽

T. ISHIKAWA

Keyword(s):

Chemical Properties ◽

Hydroxyl Groups ◽

Physical And Chemical Properties ◽

Surface Hydrogen ◽

Physical And Chemical ◽

And Chemical Properties ◽

Hydrogen Bonded

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Morphologic and Chemical Properties of PMMA/ATH Layers with Enhanced Abrasion Resistance Realised by Cold Plasma Spraying at Atmospheric Pressure

Advances in Condensed Matter Physics ◽

10.1155/2018/3539417 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

L. Wallenhorst ◽

R. Rerich ◽

M. Vovk ◽

S. Dahle ◽

H. Militz ◽

...

Keyword(s):

Plasma Spraying ◽

Abrasion Resistance ◽

Cold Plasma ◽

Phenol Formaldehyde ◽

Chemical Properties ◽

Formaldehyde Resin ◽

Hydroxyl Groups ◽

Properties Of Coatings ◽

Process Gas ◽

And Chemical Properties

This study investigated the morphologic and chemical properties of coatings based on PMMA/ATH powder and deposited by cold plasma spraying on wood and glass. Since the deposition of pure PMMA/ATH powder with air as process gas yielded coatings with insufficient abrasion resistance, two modifications of the basic process were investigated. Previous studies showed that replacing air as process gas with forming gas did not enhance the abrasion resistance, but the addition of a phenol-formaldehyde resin (PF) succeeded in stabilising the particle coatings. In this work, results from morphologic and chemical analysis suggested an encasement of the PMMA/ATH particles by plasma-modified PF and thus a fusion of individual particles, explaining the enhanced bonding. Moreover, adhesion tests confirmed an outstanding bonding between the coating and wood as well as glass, which is assumed to result from interactions between the PF’s hydroxyl groups and functional groups on the substrates’ surfaces. Studies on the wettability revealed a hydrophobic character of such coatings, therefore generally indicating a possible application, for example, to reduce water uptake by wooden materials.

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Sex workers in Nairobi: Services users at BHESP

LIAS Working Paper Series ◽

10.29311/lwps.201812967 ◽

2018 ◽

Vol 1 ◽

Cited By ~ 2

Author(s):

Rahma Hassan ◽

Teela Sanders ◽

Peninah Mwangi

Keyword(s):

Sex Work ◽

Sex Workers ◽

Female Sex Workers ◽

Formal Education ◽

Young Female ◽

Joint Work ◽

Research Activity ◽

Support Programme ◽

Baseline Information ◽

The University

This baseline pilot study was the joint work of the University of Leicester and Bar Hostess Empowerment and Support Programme. Bar Hostess Empowerment & Support Programme (BHESP) is an organisation for and by sex workers (known as bar hostesses) in Nairobi, Kenya. The project consisted of experts in public health, human rights interventions and the sociology of sex work, who came together to develop and administer a unique research activity. The study further provided BHESP with baseline information on the various services provided and the gaps at the clinic, as well as barriers that young female sex workers face in returning to formal education, and /or pursuing their careers.

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Online chemical adsorption studies of Hg, Tl, and Pb on SiO2 and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Radiochimica Acta ◽

10.1515/ract-2017-2914 ◽

2018 ◽

Vol 106 (12) ◽

pp. 949-962 ◽

Cited By ~ 2

Author(s):

Lotte Lens ◽

Alexander Yakushev ◽

Christoph Emanuel Düllmann ◽

Masato Asai ◽

Jochen Ballof ◽

...

Keyword(s):

Experimental Data ◽

Chemical Properties ◽

Relativistic Effects ◽

Chemical Yield ◽

Single Atom ◽

Chemical Adsorption ◽

Detector Arrays ◽

Adsorption Studies ◽

Heaviest Elements ◽

Fusion Evaporation Reactions

Abstract Online gas-solid adsorption studies with single-atom quantities of Hg, Tl, and Pb, the lighter homologs of the superheavy elements (SHE) copernicium (Cn, Z=112), nihonium (Nh, Z=113), and flerovium (Fl, Z=114), were carried out using short-lived radioisotopes. The interaction with Au and SiO2 surfaces was studied and the overall chemical yield was determined. Suitable radioisotopes were produced in fusion-evaporation reactions, isolated in the gas-filled recoil separator TASCA, and flushed rapidly to an adjacent setup of two gas chromatography detector arrays covered with SiO2 (first array) and Au (second array). While Tl and Pb adsorbed on the SiO2 surface, Hg interacts only weakly and reached the Au-covered array. Our results contribute to elucidating the influence of relativistic effects on chemical properties of the heaviest elements by providing experimental data on these lighter homologs.

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Synthesis of Analogues of (+)-Gomphoside, a Potent HIF-1 Inhibitor and Cardenolide

Natural Product Communications ◽

10.1177/1934578x1801300315 ◽

2018 ◽

Vol 13 (3) ◽

pp. 1934578X1801300

Author(s):

Eckehard Cuny

Keyword(s):

Hypoxia Inducible Factor ◽

Chemical Properties ◽

Structural Features ◽

Hydroxyl Group ◽

Breast Cancer Cell Lines ◽

Hydroxyl Groups ◽

Human Breast ◽

Carbon 14 ◽

Sugar Ring ◽

Carbonyl Function

The milkweed bush Gomphocarpus fruticosus R.Br. found in Australia contains the steroidal glycoside (+)-gomphoside, its derivatives (-)-3'-dehydrogomphoside and (+)-3'- epi-gomphoside, as well as other glycoside compounds. The key structural features of these unique herbal agents are bislinked steroid to sugar linkages. (+)-Gomphoside is an extremely potent cardenolide and highly effective Hypoxia-Inducible Factor (HIF)-1 inhibitor. In addition, (+)-gomphoside exhibits strong cytotoxicity on human breast cancer cell lines. The syntheses of (+)-gomphoside analogues with modified steroidal D rings are described here. The syntheses started with glycosylation of (+)-(2α,3β,5α)-2,3-cholestanediol with benzoylated 2-keto sugar bromides, promoted by silver carbonate. Two regioisomeric glycosides with bent up and bent down ring anellation geometry were obtained, because of the two hydroxyl groups in the diol. Modification of the sugar ring of these glycosides by base-induced elimination of benzoic acid yielded (-)-3'-dehydrogomphoside analogues. The analogues of (+)-gomphoside and (+)-3'- epi-gomphoside were then obtained by stereoselective reduction of the 3'-carbonyl function. Compared to natural (+)-gomphoside, these analogues have the following unique structural features: a steroidal D ring with C8H17-alkyl chain instead of an exocyclic butenolide moiety, a different configuration at bridgehead carbon-14, and lack of a hydroxyl group at this position. The resulting altered chemical properties make them interesting structures for pharmacological evaluation and they are potentially suitable candidates for the development of new inhibitors in cancer therapy.

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Modification of Chemical Properties of Shellac with Glycerol and Acrylic Acid

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.789.87 ◽

2018 ◽

Vol 789 ◽

pp. 87-91

Author(s):

Harry Marareza ◽

Rochmadi ◽

Sarto

Keyword(s):

Acrylic Acid ◽

Natural Product ◽

Intermediate Product ◽

Chemical Properties ◽

Acid Value ◽

Hydroxyl Groups ◽

Glycerol Concentration ◽

Free Glycerol ◽

Temperature Modification

Shellac is a natural product which has been presumed as a fragile polymer due to itschemical properties. The objective of this study was to improve chemical properties of shellac by themodification with different concentration of glycerol and acrylic acid. Shellac was reacted withglycerol at various temperature and amounts of glycerol. The intermediate product was reacted withacrylic acid at different concentration. Acid value, hydroxyl groups, and free glycerol concentrationof modified shellac was determined. The result showed that acid value gradually decrease alongincreasing temperature for each ratio of glycerol and acrylic acid to shellac. The concentration ofhydroxyl groups rise as temperature and ratio increases. Furthermore, free glycerol concentration felldown along with the rise temperature. Modification chemical properties of shellac with glycerol andacrylic acid can be applied for the further study to enhance shellac properties.

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