Hybrid Orthorhombic Carbon Flakes Intercalated with Bimetallic Au-Ag Nanoclusters: Influence of Synthesis Parameters on Optical Properties

Until recently, planar carbonaceous structures such as graphene did not show any birefringence under normal incidence. In contrast, a recently reported novel orthorhombic carbonaceous structure with metal nanoparticle inclusions does show intrinsic birefringence, outperforming other natural orthorhombic crystalline materials. These flake-like structures self-assemble during a laser-induced growth process. In this article, we explore the potential of this novel material and the design freedom during production. We study in particular the dependence of the optical and geometrical properties of these hybrid carbon-metal flakes on the fabrication parameters. The influence of the laser irradiation time, concentration of the supramolecular complex in the solution, and an external electric field applied during the growth process are investigated. In all cases, the self-assembled metamaterial exhibits a strong linear birefringence in the visible spectral range, while the wavelength-dependent attenuation was found to hinge on the concentration of the supramolecular complex in the solution. By varying the fabrication parameters one can steer the shape and size of the flakes. This study provides a route towards fabrication of novel hybrid carbon-metal flakes with tailored optical and geometrical properties

cis-Tetra­chloridobis(1H-imidazole-κN 3)platinum(IV)

In the title complex, cis-[PtCl4(C3H4N2)2], the PtIV ion lies on a twofold rotation axis and is coordinated in a slightly distorted octa­hedral geometry. The dihedral angle between the imidazole rings is 69.9 (2)°. In the crystal, mol­ecules are linked by N—H⋯Cl hydrogen bonds, forming a three-dimensional network

Production of food nanomaterials by specialized equipment

In the past decade, there has been a great interest in using nanotechnology by different industries, including food, pharmaceutical, and beauty. Nanotechnology provides many advantages to produce functional compounds which tend to be delivered for desired properties, such as protection from the environment or food matrix, controlled release, and increased bioavailability and bioaccessibility (Muhammad et al., 2019, Sedaghat Doost et al., 2019b, Sedaghat Doost et al., 2018c). There is a variety of methods to prepare food nanomaterials. Specialized equipment is frequently employed for the production of efficient nano-delivery systems, which is the focus of this chapter; the basic principle of conventional and recent techniques, as well as their advantages and disadvantages are described

Click reactions in chitosan chemistry

The review provides the first generalized and systematized information on the use of click reactions in chitosan chemistry for the preparation of novel polymers with attractive physicochemical and biological properties. The reactions of copper-catalyzed azide—alkyne cycloaddition and the click reactions of chitosan derivatives occurring in the absence of salts or metal complexes are discussed in detail. The data on the pre-click modification of chito-san (i.e., the introduction of azide function, alkyne fragment, highly dipolarophilic moieties, and thiol group into the polymer) are reviewed. Special attention is given to the application of new chitosan derivatives obtained by click modification. © 2017, Springer Science+Business Media, LLC

ПОЛУЧЕНИЕ ЭКОЛОГИЧНЫХ И НЕТОКСИЧНЫХ АНТИБАКТЕРИАЛЬНЫХ СИСТЕМ НА ОСНОВЕ ХИТОЗАНА И АНТИБИОТИКА ЦИПРОФЛОКСАЦИНА

Ультразвук эффективно способствует DCC-опосредованному связыванию между функциональными группами COOH и NH2 в воде. Данную методику использовали для конъюгации ципрофлоксацина с хитозаном. Полученные конъюгаты ципрофлоксацин/хитозан способны к образованию самособирающихся наночастиц (ССНЧ) в водной среде. ССНЧ могут быть дополнительно загружены ципрофлоксацином для формирования новых систем высвобождения ципрофлоксацина. Данные системы продемонстрировали высокую эффективность загрузки и инкапсуляции и характеризуются пролонгированным профилем высвобождения (20 часов). Разработанные системы восвобождения были протестированы in vivo на крысах. Антибактериальный эффект полученных систем in vivo превосходит таковой исходного ципрофлоксацина. Более того, острая и хроническая токсичность наночастиц i n vivo была практически идентична хитозану, который считается нетоксичным биополимером

Click reactions in chitosan chemistry

The review provides the first generalized and systematized information on the use of click reactions in chitosan chemistry for the preparation of novel polymers with attractive physicochemical and biological properties. The reactions of copper-catalyzed azide—alkyne cycloaddition and the click reactions of chitosan derivatives occurring in the absence of salts or metal complexes are discussed in detail. The data on the pre-click modification of chito-san (i.e., the introduction of azide function, alkyne fragment, highly dipolarophilic moieties, and thiol group into the polymer) are reviewed. Special attention is given to the application of new chitosan derivatives obtained by click modification. © 2017, Springer Science+Business Media, LLC

Ultrasound-assisted catalyst-free phenol-yne reaction for the synthesis of new water-soluble chitosan derivatives and their nanoparticles with enhanced antibacterial properties

This work describes ultrasound-assisted phenol-yne addition of p-hydroxybenzaldehyde and propargylic ester of betaine hydrochloride giving only 2-((3-(4-formylphenoxy)allyl)oxy)-N,N,N-trimethyl-2-oxoethan-1-aminium chloride as a product at 100 kHz 300 W in water. The ultrasonic assisted phenol-yne addition was enhanced to chitosan chemistry. Phenolic chitosan derivatives were obtained by treatment of chitosan with o-, m- or p-hydroxybenzaldehyde followed by reduction of the formed C[dbnd]N bound by NaBH4. The phenolic chitosan derivatives (phenolic component) were involved in ultrasound-mediated reaction with propargylic ester of betaine hydrochloride (yne component). The reaction led to betaine chitosan derivatives in different degree of substitution as o-, m- and p-isomers. The phenolic and betaine derivatives were tested as antibacterial agents against E. coli in comparison with reference antibiotic Tetracycline. Betaine derivatives showed high antibacterial activity. The most effective polymer was p-isomer of high substituted betaine derivative and its activity was more than 2 times higher than the activity of Tetracycline. The nanoparticles based on this polymer were obtained by ionic gelation method. They had 2Rh 126 nm, ξ-potential 20 mV and were more effective than the corresponding chitosan derivative. © 2019 Elsevier B.V

Arguments for tightness testing of nuclear system pipeline parts, attached to pressureless tanks

Actual standard, namely Rules for design and safe operation of equipment and pipelines of nuclear power installations (2015) does not regulate strength and tightness testing of pipeline parts, located between valves and pressureless tanks of nuclear systems at nuclear power plants. This paper introduces arguments for strength and tightness test conduction of such areas of nuclear power plant pipelines, designed in accordance with Russian standards. It was also proposed some amendments for the norm aimed to improve safety and reliability of nuclear power plant systems with radioactive contamination. It was suggested to apply the result of current study to Leningradskaya-2 in order to improve safety and decrease the number of failures of the liquid radioactive waste storage system