Search results for "visual_art.visual_art_medium"
showing 10 items of 2982 documents
Chemical characterization of ancient liturgical vestment (chasuble) by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP–OES)
2016
Abstract This paper presents the chemical characterization of the yarns of an ancient liturgical vestment (chasuble). The samples have been analyzed for Al, Ag, Au, Cd, Co, Cr, Cu, Ni, Pb and Zn using amounts always less than 1 mg by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). Except a sample, silver is the most abundant element in all the yarns. In the samples containing silver, it ranged from 68 to 97%. Only two samples contain aluminum. Although the investigated chasuble is recorded in the inventory as an artifact of the XV century, a part of the yarns is composed of materials attributed to later period. In fact, the voluntary use of aluminum in metal alloys is du…
Localization and Characterization of Ferritin in Demospongiae: A Possible Role on Spiculogenesis
2014
Iron, as inorganic ion or as oxide, is widely used by biological systems in a myriad of biological functions (e.g., enzymatic, gene activation and/or regulation). In particular, marine organisms containing silica structures—diatoms and sponges—grow preferentially in the presence of iron. Using primary sponge cell culture from S. domuncula–primmorphs—as an in vitro model to study the Demospongiae spiculogenesis, we found the presence of agglomerates 50 nm in diameter exclusively inside sponge specialized cells called sclerocytes. A clear phase/material separation is observed between the agglomerates and the initial stages of intracellular spicule formation. STEM-HRTEM-EDX analysis of the agg…
Magnetic behavior control in niccolite structural metal formate frameworks [NH2(CH3)2][Fe(III)M(II)(HCOO)6] (M = Fe, Mn, and Co) by varying the dival…
2010
By changing template cation but introducing trivalent iron ions in the known niccolite structural metal formate frameworks, three complexes formulated [NH(2)(CH(3))(2)][Fe(III)M(II)(HCOO)(6)] (M = Fe for 1, Mn for 2, and Co for 3) were synthesized and magnetically characterized. The variation in the compositions of the complexes leads to three different complexes: mixed-valent complex 1, heterometallic but with the same spin state complex 2, and heterometallic heterospin complex 3. The magnetic behaviors are closely related to the divalent metal ions used. Complex 1 exhibits negative magnetization assigned as Neel N-Type ferrimagnet, with an asymmetric magnetization reversal in the hysteres…
The Use of Polyoxometalates in the Design of Layer‐Like Hybrid Salts Containing Cationic Mn 4 Single‐Molecule Magnets
2013
Herein, we describe the combination of polyoxometalates (POMs) with a polynuclear metallic cluster Mn4 {Mn4 = [Mn4(OAc)2(pdmH)6]2+, (pdmH = deprotonated pyridine-2,6-dimethanol; C7H8NO2)} for the construction of ionic crystals with layered architectures. Choosing a POM with the appropriate charge and size not only allows for the fine tuning of the stacking periodicity, but it also allows modifying the in-plane packing motif and density of the cationic metallic clusters. The isolation of differently layered hybrid crystals with the same Mn4 single-molecule-magnet (SMM) system allowed for the direct comparison of the magnetic properties of such materials. The variation of the slow relaxation …
Spin Trapping of Carbon-Centered Ferrocenyl Radicals with Nitrosobenzene
2015
In contrast to metal centered 17 valence electron radicals, such as [Mn(CO)5]•, ferrocenium ions [Fe(C5H5)2]+ (1+), [Fe(C5Me5)2]+ (2+), [Fe(C5H5)(C5H4Et)]+ (3+), [Fe(C5H5)(C5H4NHC(O)Me)]+ (4+), and [Fe(C5H5)(C5H4NHC(S)Me)]+ (5+) do not add to nitrosobenzene PhNO to give metal-coordinated stable nitroxyl radicals. In the presence of the strong and oxidatively stable phosphazene base tert-butylimino-tris(dimethylamino)phosphorane, the quite acidic ferrocenium ions 1+–5+ are deprotonated to give a pool of transient and persistent radicals with different deprotonation sites [1–Hx]•–[5–Hx]•. One rather persistent iron-centered radical [4–HN]•, deprotonated at the nitrogen atom, has been detected…
Reactive surface coatings based on polysilsesquioxanes: universal method toward light-responsive surfaces.
2011
Reactive surface coatings were used as an ideal precursor coating for the fabrication of three different photoswitchable surface coatings in parallel. Different light-responsive moieties, such as azobenzene, salicylideneaniline, and spiropyran, were immobilized on glass, polycarbonate, and steel surfaces. Independent from the underlying substrate, wettability could be switched reversibly by UV irradiation. The maximum switching range was obtained after functionalization of the reactive coating with spiropyran, resulting in a contact angle difference between the two isomeric states of almost 30°.
In vitro antibacterial and biofilm inhibitory activity of the sawdust essential oil of Tetraclinis articulata (vahl) against catheter-associated Stap…
2021
Abstract The aim of the present study was to determine the chemical composition, antibacterial and antibiofilm activities of the essential oil of sawdust from root burl wood of T. articulata. Nine strains including 8 clinical isolates from catheters-related infections and one ATCC 25923 were tested. Twenty-seven different compounds were identified by GC–MS in the essential oil of T. articulata extracted by hydrodistillation. Carvacrol and cedrol were the principal compounds representing 34.37 ± 0.07 and 11.07 ± 0.09 respectively. The EO had a strong antibacterial activity against all strains including one Multidrug-Resistant (MDR) and two Methicillin-Resistant S. aureus strains. Inhibition …
Atypical transistor-based chaotic oscillators: Design, realization, and diversity
2017
In this paper, we show that novel autonomous chaotic oscillators based on one or two bipolar junction transistors and a limited number of passive components can be obtained via random search with suitable heuristics. Chaos is a pervasive occurrence in these circuits, particularly after manual adjustment of a variable resistor placed in series with the supply voltage source. Following this approach, 49 unique circuits generating chaotic signals when physically realized were designed, representing the largest collection of circuits of this kind to date. These circuits are atypical as they do not trivially map onto known topologies or variations thereof. They feature diverse spectra and predom…
A linear open-chain piperazine-pyridine ligand and its meso-helical Co complex
1998
Abstract An oligomeric ligand (HPPy) 2 P, N , N ′-bis[2-(6-( N -( N ′-(2-hydroxyethyl)piperazinyl)methyl)]piperazine, was designed to resemble structurally open-chain aza-crowns. Owing to the all- trans configuration of piperazine and pyridine free electron pairs, it should adopt a near linear overall structure in solvent. Theoretical calculations at ab initio level confirm the overall linear structure of free ligand. The crystal structure of the complex [(HPPy) 2 P][Co(NO 3 ) 2 ] 2 shows a contraction from ∼3 to 2 nm structure. Each coordination site creates either a Δ or Δ configuration around the metal ion, thus causing a ligand with an even number of coordination centres to be meso -hel…
Solid state conformational and theoretical study of complexes containing the (CxN)Pd moiety (CxN = 2-(phenylazo)phenyl-C,N and its derivatives)
2003
Palladium complexes having the 2-(phenylazo)phenyl-C,N ligand exhibit a planar chelating ring with NN and N–C distances longer and shorter respectively than those found in trans-azobenzene. The ligand is not planar upon complexation, the mean angle between the phenyl ring and the chelating one found in the Cambridge Structural Database being of 45.6°. We have quantified and characterised the kind of distortion from planar coordination around metallic centers. The method employed makes use of two improper torsion angles, tetrahedral distortion being most frequently found in phenylazophenyl palladium complexes. Crystal structures of three succinimidate complexes having the title moiety are re…