Perovskite solar cells have already demonstrated high radiation hardness substantially exceeding that of crystalline silicon and GaAs based solar panels commonly used in space. However, aerospace ...applications of PSCs require a number of other important prerequisites, among which the stability towards a combination of multiple stress factors characteristic of the outer space environment is of particular importance. Herein, we present an in-depth investigation of the influence of the Eu2+/Eu3+ redox pair on the intrinsic photostability of PbI2 and complex lead halides. We confirm that the incorporation of europium effectively suppresses the photochemical production of metallic lead and other aging products. Furthermore, the Eu-modified methylammonium-free double cation perovskite formulation Cs0.12FA0.88Pb0.99Eu0.01I3 demonstrated excellent radiation hardness under exposure to ultrahigh doses of gamma rays (5.5 MGy) and 8.5 MeV electron beams (fluences up to 3 × 1016 e per cm2) owing to the mitigated aging pathways such as radiochemical Pb0 formation and segregation of CsPbI3 and/or FAPbI3 δ-phases. Thus, the stabilizing effect of the Eu2+/Eu3+ redox shuttle was exploited here for the first time to substantially increase the stability of perovskite absorber materials with respect to three different stress factors simultaneously: light, gamma-rays and high-energy electrons. Further development of this research direction might facilitate commercialization of PSCs for aerospace applications.
Perovskite solar cells have already demonstrated high radiation hardness substantially exceeding that of crystalline silicon and GaAs based solar panels commonly used in space. However, aerospace ...applications of PSCs require a number of other important prerequisites, among which the stability towards a combination of multiple stress factors characteristic of the outer space environment is of particular importance. Herein, we present an in-depth investigation of the influence of the Eu
2+
/Eu
3+
redox pair on the intrinsic photostability of PbI
2
and complex lead halides. We confirm that the incorporation of europium effectively suppresses the photochemical production of metallic lead and other aging products. Furthermore, the Eu-modified methylammonium-free double cation perovskite formulation Cs
0.12
FA
0.88
Pb
0.99
Eu
0.01
I
3
demonstrated excellent radiation hardness under exposure to ultrahigh doses of gamma rays (5.5 MGy) and 8.5 MeV electron beams (fluences up to 3 × 10
16
e per cm
2
) owing to the mitigated aging pathways such as radiochemical Pb
0
formation and segregation of CsPbI
3
and/or FAPbI
3
δ-phases. Thus, the stabilizing effect of the Eu
2+
/Eu
3+
redox shuttle was exploited here for the first time to substantially increase the stability of perovskite absorber materials with respect to three different stress factors simultaneously: light, gamma-rays and high-energy electrons. Further development of this research direction might facilitate commercialization of PSCs for aerospace applications.
The incorporation of Eu
2+
cations in lead-halide perovskites improves their photostability and radiation hardness with respect to γ-rays and high-energy electron fluences, which are the key prerequisites for aerospace applications of PSCs.
Objective.
The aim of the work is to study the use of nanofluids as heat carriers to increase the efficiency of heat removal in energy facilities. To solve this problem, materials of domestic and ...foreign scientific articles, conferences and dissertations on the subject of nanofluids were analyzed. Numerous scientific publications, including those cited in the international databases Web of Science and Scopus, indicate that the topic of nanofluids is in the focus of modern science. However, despite a rather long period of fluid research, not all issues of this topic are sufficiently well covered and systematized, which opens up great opportunities for further research in this direction.
Method
. When achieving this goal, the areas of possible application of fluids, the mechanism of their synthesis, the features of their operation are considered, the advantages as a liquid coolant are indicated, and the disadvantages that prevent their widespread use are identified. Particular attention is paid to such issues as: synthesis of standardized nanofluids; ensuring their stable properties; the use of surfactants; increasing the pressure drop inside heat exchangers during operation of this coolant.
Result.
To eliminate the main drawback in the form of agglomeration of nanoparticles in the base fluid, it is proposed to use the oscillatory circulation of the coolant, which will also further intensify heat exchange from forced turbulence of the fluid.
Conclusion.
The results obtained can be used to improve the efficiency of heat and mass transfer devices with liquid coolant and systems based on them, as well as to reduce the weight and size parameters of such devices.
The micropackaging of chemical compounds in a small and precisely defined quantity, which can be encased, stored, is essential for response to a specific chemical, biological or physical trigger in a ...controllable manner is one of the premier challenges in the development of delivery systems. In this review, the authors discuss the application of layer-by-layer (LbL) assemblies of macromolecules for micropackaging and controlled release of various types of cargo. The LbL assembly method provides unique opportunities by incorporation of different functional and responsive layer constituents tailored into one entity. Micron and submicron sized capsules made on colloidal templates are used for biomolecule encapsulation and enable time- and site-specific release when triggered by pH, temperature, specific enzymes, mechanic load, light, ultrasound, or magnetic field. In comparison to individual capsules, the authors discuss the recently introduced micropackaging approach involving cargo loading into arrays of microchambers, made by a combination of imprinting technology and LbL assembly. In conclusion, the authors summarise advantages and fabrication obstacles for micropackaging in capsules and microchambers and discuss already existing as well as potential future applications.
Melamine-formaldehyde resins are widely used in the production of various technical and household products. By foaming a special resin, it is possible to obtain various foam plastics, including ...melamine sponges (MS), which, due to their unusual mesh structure and properties, absorb and wash away contamination quite well and have well-pronounced abrasive characteristics. The area of application of melamine sponges can be significantly expanded by their modification. Radiation-synthesized telomeres of tetrafluoroethylene (TFE) are of considerable interest for MS modification, as they make it possible to create protective hydrophobic coatings on various materials and products. This work presents the results of studies of the MS hydrophobization process, using TFE telomeres, synthesized in acetone and the binary solvent of freon 113 + ammonia. The composition and structure of hydrophobized melamine sponges have been studied by the methods of X-ray photoelectron and Raman spectroscopy, optical and scanning electron microscopy. It is shown that the treatment with tetrafluoroethylene telomere solutions makes it possible to give the initial hydrophilic material a highly hydrophobic state, characterized by a contact angle of wetting of the order of 135°–140°. This treatment significantly improves the performance characteristics and expands the practical application possibilities of melamine sponges. The morphology and composition of the modified samples have been studied. It is shown that the telomere can exist in two different states in the MS spatial network: closely bound and loosely bound fractions. The loosely bound fraction can be removed mechanically, the closely bound fraction remains on the MS surface even after several treatments with solvents, ensuring the stability of the hydrophobic properties of the sponge.
A description is given of the causes by which the transmission of vibration and airborne noise from equipment to the environment should be controlled. The paths of this transmission and applicable ...ways for its reduction by passive and active methods are examined. It has been demonstrated that pipelines, even vibration-isolated from the equipment by means of expansion joints, can transmit and even amplify vibration from the installation in a wide frequency range. It is noted that reducing the vibration of pipelines is important for effective vibration isolation of equipment in power and transport machine building, shipbuilding, and of oil and gas pipelines at pump stations. Effective control of the vibration and noise transmission to the environment has been shown to require a preliminary comprehensive analysis of the importance of all paths of their transmission. A description is given of a dedicated universal research test facility for a comprehensive study of the possibility and methods for reducing the transmission of vibration and airborne noise from operating equipment with a flow of working fluid through piping using passive and active methods.
The results of experimental studies on the creation of highly efficient designs of vibration-isolating compensators for pipelines with liquid are considered. It is noted that the only way to evaluate ...the effectiveness of various compensators in reducing vibration at different frequencies currently is to compare their transient vibration stiffness or transient mechanical impedance, which were measured on special stands at a given frequency. The stiffness of the compensator increases significantly with increasing frequency vibrations. Hazardous frequencies may vary between piping systems. For this reason, it is impossible to set an integral criterion for the effectiveness of a vibration-isolating compensator, similar to static stiffness. The results of measurements carried out on a special stand on the transitional vibration stiffness of a new design compensator with thin-layer rubber-metal elements (TRME) are presented. The rigidity decreased by 10 or 100 times or more in the frequency range from 50 to 800 Hz relative to the rigidity of a serial compensator based on rubber cord casing (RCC), including in the presence of water inside it. It has been experimentally shown that the vibration-isolating ability of the same compensator as part of a pipeline system, determined by the value of the dynamic force transmitted by the compensator to the pipeline from the pump, significantly depends on the presence of water in them and its flow, which is not taken into account in known methods. The results of testing compensators with RCC and TRME with a bore diameter of 80 mm as part of a stand with a ring pipeline system, a pump, systems for monitoring the flow of the working fluid, vibrations, pressure pulsations, and dynamic (vibration) forces transmitted by the compensators to the pipeline are presented. In a stand with pipelines, the efficiency of vibration-isolating compensators with TRME is still 10 and 100 times higher than compensators with RCC in the absence of water and decreases by an order of magnitude in the presence of water without its flow when the pump is vibrated by a vibrator. Efficiency decreases even further if water flows through expansion joints and pipelines while the pump is running.
Coatings of aluminoborosilicate fabric have been obtained by deposition from solutions of radiation-synthesized tetrafluoroethylene telomers. The resulting coatings were characterized by IR ...spectroscopy. By the sessile drop method, it has been established that the surface of the coatings is hydrophobic with a water contact angle of 140°. The effect of gamma-radiation on the molecular structure of coatings has been examined using IR spectroscopy. It has been shown that irradiation of the studied samples in air results in the formation of terminal COOH groups, which worsen the hydrophobicity of the samples. Irradiation in vacuum does not affect the hydrophobic properties of telomeric coatings.
