Photothermal and photocatalytic processes on TiO2 based materials prepared by sol-gel method

In the present work, Fe³⁺ doped TiO₂ coatings on glass substrates were prepared by dip-coating from a sol-gel solution. The influence of the dopant concentration on the structure, optical, photocatalytic and photothermal properties of the films was studied. The results obtained have shown a strong correlation between the catalytic properties and the amount of iron dopant and the temperature of the thermal treatment.     

Conley index of Poincaré maps in isolating segments

We calculate the discrete-time Conley index of the Poincaré map of a time-periodic ordinary differential equation in an isolated invariant set generated by a periodic isolating segment. As an application, we present results on the existence of bounded solutions of some planar equations.     

Optical studies of aromatic polyazomethine thin films

Optical transmission and fundamental reflectivity spectra of aromatic polyazomethine thin films, obtained by vacuum evaporation via the polycondensation process have been investigated in the wide spectral range 0.49–6.2 eV. As initial monomers, terephaldehyde (TPA) and one of four different amines, i.e. paraphenylene-diamine (PPDA), 7,2-diamino-fluorene, 1,1′-biphenyl-3,3′,4,4′-tetramine and 3-amino-4-(1-naphthyldiazenyl)phenylamine (fat brown RR) have been used, respectively. Amorphous character of these films was confirmed by the results of X-ray diffraction and AFM investigations. Absorption coefficient of the films has been obtained and the edge of absorption seems to be similar to the absorption edge typical for amorphous semiconductors, what allowed to obtain the Urbach energy and E_T parameter. The energy gaps of the films, following the Tauc relation, are found to change from 2.05 to 2.4 eV, depending on the length of conjugated part of the polymer chain. Absorption bands above the absorption edge, observed for different polyazomethine films are connected with their chemical structure and possible electronic transitions.     

Catalyst‐Free Reductive Coupling of Aromatic and Aliphatic Nitro Compounds with Organohalides

A rare reductive coupling of nitro compounds with organohalides has been realized. The reaction is initiated by a partial reduction of the nitro group to a nitrenoid intermediate. Therefore, not only aromatic but also aliphatic nitro compounds are efficiently transformed into monoalkylated amines, with organohalides as the alkylating agent. Given the innate reactivity of the nitrenoid, a catalyst is not required, resulting in a high tolerance for aryl halide substituents in both starting materials.     

Transient Phosphenium and Arsenium Ions versus Stable Stibenium and Bismuthenium Ions

Fluoride abstraction from bis-m-terphenylelement fluorides (2,6-Mes₂C₆H₃)₂EF (E=P, As) generated the highly reactive phosphenium ion [(2,6-Mes₂C₆H₃)₂P]⁺ and the arsenium ion [(2,6-Mes₂C₆H₃)₂As]⁺, which immediately underwent intramolecular electrophilic substitution and formation of an 1,2,4-trimethyl-6-mesityl-5-m-terphenyl-benzo[b]phospholium ion and an 1,2,4-trimethyl-6-mesityl-5-m-terphenyl-benzo[b]arsolium ion, respectively. The formation of the latter involved a methyl group migration from the ortho-position of a flanking mesityl group to the meta-position. This reactivity of [(2,6-Mes₂C₆H₃)₂E]⁺ (E=P, As) is in sharp contrast to the related stibenium ion [(2,6-Mes₂C₆H₃)₂Sb]⁺ and bismuthenium ion [(2,6-Mes₂C₆H₃)₂Bi]⁺, which have been recently isolated and fully characterized (Angew. Chem. Int. Ed. 2018, 57 , 10080–10084). On the basis of DFT calculations, a mechanism for the rearrangement of the phosphenium and arsenium ions into the phospholium and arsolium ions is proposed, which is not feasible for the stibenium and bismuthenium ions.     

On the restabilization of protein-covered latex colloids at high ionic strengths

Recent experiments on restabilization of protein-covered latex colloids at high ionic strengths reported by Lopez-Leon et al.(1) revealed strong specific anion effects. The same authors also emphasized that a recent polarization model, which involves both hydration and double layer forces, can account only for some of their experimental results but are in disagreement with other experimental results. The aim of the present paper is to show that most experimental results of ref 1 can be described, more than qualitatively, when the association equilibria for all the ions (with both the acidic and basic sites of the protein) are taken into account. As the traditional Poisson-Boltzmann approach, the polarization model neglects additional interactions between ions, and ions and surfaces, not included in the "mean field" electrical potential; therefore, a complete quantitative agreement should not be expected. While many of the discrepancies between calculations and experiment occur at low ionic strengths (10(-)(4)-10(-)(2) M), in the range of validity of the traditional DLVO theory, the latter can neither explain them. It is suggested that the structural modifications of the protein configuration induced by the electrolyte are responsible for some of the disagreements between experiment and calculations.     

Distinct gaps between fractional parts of sequences

Let be a real number, a positive integer and a subset of . We give an upper bound for the number of distinct lengths of gaps between the fractional parts .

     

Quantifying nonclassicality of one-mode Gaussian states of the radiation field

We define the degree of nonclassicality of a one-mode Gaussian state of the quantum electromagnetic field in terms of the Bures distance between the state and the set of all classical one-mode Gaussian states. We find the closest classical Gaussian state and the degree of nonclassicality using a recently established expression for the Uhlmann fidelity of two single-mode Gaussian states. The decrease of nonclassicality under thermal mapping is carefully analyzed. Along the same lines, we finally present the evolution of nonclassicality during linear amplification.