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The development of photocurable compositions is in high demand for the manufacture of functional materials for electronics, optics, medicine, energy, etc. The properties of the final photo-cured material are primarily determined by the initial mixture, which needs to be tuned for each application. In this study we propose to use simple systems based on di(meth)acrylate, polyimide and photoinitiator for the preparation of new photo-curable compositions. It was established that a fluorinated cardo copolyimide (FCPI) based on 2,2-bis-(3,4-dicarboxydiphenyl)hexafluoropropane dianhydride, 9,9-bis-(4-aminophenyl)fluorene and 2,2-bis-(4-aminophenyl)hexafluoropropane (1.00:0.75:0.25 mol) has excellent solubility in di(met)acrylates. This made it possible to prepare solutions of FCPI in such monomers, to study the effect of FCPI on the kinetics of their photopolymerization in situ and the properties of the resulting polymers. According to the obtained data, the solutions of FCPI (23 wt.%) in 1,4-butanediol diacrylate (BDDA) and FCPI (15 wt.%) in tetraethylene glycol diacrylate were tested for the formation of the primary protective coatings of the silica optical fibers. It was found that the new coating of poly(BDDA–FCPI23%) can withstand prolonged annealing at 200 °C (72 h), which is comparable or superior to the known most thermally stable photo-curable coatings. The proposed approach can be applied to obtain other functional materials. [ABSTRACT FROM AUTHOR]

A 2.03 μm gas-discharge fiber laser based on atomic xenon is investigated. Various gas mixtures, such as He–Xe, Ar–Xe, He–Ar–Xe, and He–Ne, are studied by optical emission spectroscopy. The possibility of extending laser generation further into the mid-infrared range is analyzed. [ABSTRACT FROM AUTHOR]

Broadband supercontinuum (SC) fiber sources covering the mid-IR range have many significant applications, largely due to their compactness, reliability, and ease of use. However, most of the existing SC fiber sources cannot boast of either high reliability or a wide bandwidth. Thus, supercontinuum sources based on silica fibers are robust, but are not capable of generating SC in the mid-IR range. Sources based on soft glasses (tellurite, chalcogenide, etc.) generate broadband SC in the mid-IR range but are not used commercially, due to the poor mechanical and chemical characteristics of such fibers. In this work, we propose a new approach consisting of cascade generation of a supercontinuum sequentially in a silica photonic crystal fiber (PCF) and a germanate fiber. Using a standard ytterbium chirped-pulse amplification (CPA) laser system for pumping, we have demonstrated a supercontinuum in the range of 450–2950 nm in PCF and germanate fiber firmly connected by a standard fusion splicing technique. Further optimization of the cascade pump will make it possible to create a compact and reliable all-fiber SC source from the visible to mid-IR range. [ABSTRACT FROM AUTHOR]

The extended representation of the water management problem that is an important component of the supply of resources is vital in an effective regional economy. This article justifies the importance of such a representation through the lens of the paired strategizing of the water resource system and regional economic development. The authors' purpose is to analyse the rationality of the usage of water resources in conjunction with regional socio-economic development indicators, by applying tools that allow grouping based on the existing trends in water consumption. The article studies the importance of the effective management of the allocation of scarce water resources among users. It also examines the rationality of their usage in the context of optimising resource usage, and the high variations across areas based on the potential of the resource components, as well as the dynamic socio-economic indicators. The theoretical framework of the rational water usage paradigm comprises a set of interrelated concepts and theories, such as the theory of economic growth, as well as theories and concepts of regional development, particularly regional resource management, considering the parameters of current and proposed mesoeconomic policies in combination with the basin approach for the allocation of water resources. It has been shown that the gross regional product (GRP) water intensity indicator is one of the important criteria in assessing the rational usage of territorial water resources. The authors' hypothesis is that regional peculiarities in the tendencies of GRP water intensity indicator changes allow not only to define the current situation pertaining to water use, but also to determine the direction of the control actions to increase its efficiency. In the study, this hypothesis is confirmed. Unlike other existing approaches and models which are oriented chiefly towards the identification of scarce water resource allocation options in accordance with the standards of water use, this article implements an approach to the assessment of the efficiency of water usage as a strategic resource for socioeconomic development at the regional level. Based on the analysis of the GRP water intensity indicator and the problematic nature of region grouping from the standpoint of rational water usage, regions are identified. The results can serve as a guide for designing regional development strategies. [ABSTRACT FROM AUTHOR]

Mid-infrared Raman laser based on silica fiber is demonstrated. Hollow-core silica fiber filled by the mixture of 1H2 and D2 gases was used as an active medium. Pumped by nanosecond pulses of a high-power Er-doped 1.56 μm fiber laser, the Raman laser generates radiation at 2.9, 3.3, and 3.5 μm wavelength, which depends on gas composition and pump power.Quantum conversion efficiency as high as ∼10% is achieved. The possibilities to optimize the performance of the Raman laser are discussed. [ABSTRACT FROM AUTHOR]