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[en] In this study, trisodium citrate was used as draw solute in forward osmosis (FO) due to its biodegradability and easy reuse after FO dilution. The effect of operating conditions on FO performance was investigated. The study focused on the long-term flux performance and membrane fouling when surface water was used as feed solution. A water flux of 9.8 LMH was observed using 0.5 M trisodium citrate as draw solution in PRO mode. In the long-term FO process, trisodium citrate showed a slight decrease in total flux loss (13.06%) after 20 h of operation. The membrane fouling was significantly reduced after a two-step physical cleaning. A considerable flux recovery (> 95%) of the fouled membrane was finally obtained. Therefore, this study proves the superiority of trisodium citrate as draw solution and paves a new way in applying FO directly for surface water reclamation.
[en] The distributions of trace amounts of natural radionuclides in soil samples were studied. The K40, Na22, Sr91 radioisotopes were identified in all soil samples taken from Shirvan region of the Azerbaijan. The analyses carried out by gamma spectroscopy showed that in all soil samples the concentrations of natural radioisotopes Na22, K40, and Sr91 are 2.7, 2.5, and 0.57 Bq/kg, respectively. The cleaning methods of soil contaminated with radionuclides have been studied. By systematic studies have determined that with all cleaning methods, the degree of K40 extraction from soil samples is about 3-7 times lower than the release of Na22, and Sr91. The method of cleaning the soil from radionuclides by extraction with weak acidic and alkaline solutions is more effective than other cleaning methods.
[en] Using models of thermoassociated polymers, a cellular model of associated solutions is developed for cases where molecules of a solute are able to form from 2 to 6 bonds with each other. It is shown that solutions associated by weak intermolecular interactions in a certain range of concentrations can be considered as systems of flickering pseudo-polymeric macromolecules with a fractal structure.
[en] Nanotechnology provides innovative and promising solutions for the conservation of cultural heritage, but the development and application of new nano-enabled products pose concerns regarding their human health and environmental risks. To address these issues, we propose a sustainability framework implementing the Safe by Design concept to support product developers in the early steps of product development, with the aim to provide safer nano-formulations for conservation, while retaining their functionality. In addition, this framework can support the assessment of sustainability of new products and their comparison to their conventional chemical counterparts if any. The goal is to promote the selection and use of safer and more sustainable nano-based products in different conservation contexts. The application of the proposed framework is illustrated through a hypothetical case which provides a realistic example of the methodological steps to be followed, tailored and iterated along the decision-making process.
[en] The ability of superabsorbent polymers (SAP) to absorb and retain a large amount of water and/or aqueous solution enables their applications in areas such as agriculture, medicine and water treatment. This versatility has attracted the attention of researchers interested in developing new materials, especially bio-based polymers. As a result, there are numerous studies reporting different types of monomers and crosslinks to produce SAP. Conversely, in the literature there is a lack of discussion of the modeling approaches to describe SAP production. This paper makes a comprehensive and systematic review of the main issues for the synthesis of new SAP materials: monomer and crosslink types, as well as the kinetic model. A database on the raw materials to produce SAP for the main applications should be useful for those interested in producing new SAP materials. The mathematical model correlates structural properties with the synthesis conditions, thus supporting the development of tailor-made products.
[en] The present paper is devoted to association of molecules and properties of solutions. Therefore, the structure of solutions and the formation of hydrogen bonds of solutions have been studied by means of infrared spectroscopy method. (author)
[en] The effect of fullerenes C60 and C70 on surface tension coefficients of fullerene solutions has been studied. It has been shown that fullerenes C60 and C70 exhibit surface active properties and they are associated with the cluster nature of fullerenes in solutions. (author)
[en] The present problem aims to study the propagation behaviour of Shear Horizontal (SH) surface waves in a composite structure comprising of functionally graded piezoelectric plate fused with a porous piezoelectric plate. The material properties of the functionally graded piezoelectric material (FGPM) are assumed to be vary in quadratic manner. Method of separation of variables is used to obtain the solutions for the displacement and stress components in both the media. Solutions are obtained in terms of modified Bessel functions of first and second kinds. Dispersion relations are obtained for both the electrically open and short cases. Effects of thickness of the plates, gradient parameter, dielectric coefficient and piezoelectric coefficient on dispersion curve have been marked distinctly and portrayed through graphs. The electromechanical coupling factor is also plotted against wave number. Findings of the present investigation may set guidelines for the designing of more efficient Surface acoustic wave (SAW) devices. (paper)
[en] A pH sensor based on liquid-solid dual-gated IGZO thin-film transistor (LSDG TFT) has been demonstrated. Its sensitivity reaches 237 mV pH−1, which is nearly 4 times the Nernst limit at room temperature. The huge capacitance of the liquid gate with electric double layer (EDL) can contribute to the high sensitivity by capacitance coupling effect. However, the stability is a serious problem for its practical application. At pH measurement range of 4.00–9.18, the threshold voltage deviates seriously from the initial value at each pH solution after few cycling test. The study found that the IGZO thin film is susceptible to corrosion in pH 4.00 buffer solution. In contrast, the oxygen-related defects in the IGZO thin film are increased by immersing in pH 9.18 buffer solution, although no obvious corrosion is observed. These are presumably the causes of the device instability. (paper)