8 research outputs found
Magnetooptics in Gold and Silver NanoSizes Low-Dimensional Objects
The spectra of optical absorption and of magnetic circular dichroism (MCD) have been measured in the 350–1150 nm wavelength range for a set of colloidal solutions containing Au and Ag nanoparticles. The average size of Au nanoparticles was 6 nm and having thiolate coatings with different degrees of chirality. (The average size of Ag nanoparticles was 14 nm and having citrate coatings) The form of absorption and MCD spectra suggests the dipole character of interband transitions involving the 5d–6(sp) for Au orbitals and 4d–5(sp) for Ag orbitals. The absence (within the experimental error) of the MCD spectra dependence on the coating type rules out the hypothesis on the orbital nature of the observed magnetism. We argue that the spin polarization plays the dominant role in the magnetism both for Au and Ag nanoparticles.
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New complexes of gadolinium with dicarboxylate diphosphabetaines
The processes of complexation of dicarboxylate diphosphabetaines with gadolinium nitrate were studied, as a result of which stable polymer metal complexes insoluble in inorganic and organic solvents were obtained. To carry out these reactions, dicarboxylate diphosphabetaines were previously synthesized: 3,3'-(propane-1,3-diylbis (diphenyl)phosphoniondiyl)dipropanoate and 3,3'-(hexane-1,3-diylbis (diphenyl)phosphoniondiyl)dipropanoate, based on maleic acid with 1,3-bis(diphenylphosphino)bisphosphinspropane and 1,6-bis(diphenylphosphino)bisphosphinshexane. The structure of dicarboxylate diphosphabetaines and poly-nuclear polymer complexes of gadolinium has been confirmed by modern physical and chemical methods of research, including NMR and IR spectra, elemental and X-ray structural analysis, thermal stability has been studied by simultaneous thermogravimetry and differential scanning calorimetry
Antimicrobial activity of novel isothiuronium salts with 7-chloro-4,6-dinitrobenzofuroxan-5-olate anion
New thermally stable long-chained 2-alkylisothiuronium 7-chloro-4,6-dinitrobenzofuroxan-5-olates were obtained from the corresponding bromides and 5,7-dichloro-4,6-dinitrobenzofuroxan, the hydrolysis of the C(5)–Cl bond to produce phenolic function having occurred in the course of the process. The compound structure was determined by IR spectroscopy, elemental analysis and X-ray single crystal study. Salts with C14–C18 alkyl groups revealed moderate antibacterial and antifungal activities
The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts
The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Brønsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled. © 2020 Kuznetsova et al
Tau-function theory of chaotic quantum transport with β = 1, 2, 4
We study the cumulants and their generating functions of the probability distributions of the conductance, shot noise and Wigner delay time in ballistic quantum dots. Our approach is based on the integrable theory of certain matrix integrals and applies to all the symmetry classes β∈{1,2,4} of Random Matrix Theory. We compute the weak localization corrections to the mixed cumulants of the conductance and shot noise for β = 1, 4, thus proving a number of conjectures of Khoruzhenko et al. (in Phys Rev B 80:(12)125301, 2009). We derive differential equations that characterize the cumulant generating functions for all β∈{1,2,4}. Furthermore, when β = 2 we show that the cumulant generating function of the Wigner delay time can be expressed in terms of the Painlevé III′ transcendant. This allows us to study properties of the cumulants of the Wigner delay time in the asymptotic limit n→∞. Finally, for all the symmetry classes and for any number of open channels, we derive a set of recurrence relations that are very efficient for computing cumulants at all orders