Preparation of Metal-Immobilized Methacrylate-Based Monolithic Columns for Flow-Through Cross-Coupling Reactions

With the aim of developing efficient flow-through microreactors for high-throughput organic synthesis, in this work, microreactors were fabricated by chemically immobilizing palladium-, nickel-, iron-, and copper-based catalysts onto ligand-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) [poly(GMA-co-EDMA)] monoliths, which were prepared inside a silicosteel tubing (10 cm long with an inner diameter of 1.0 mm) and modified with several ligands including 5-amino-1,10-phenanthroline (APHEN), iminodiacetic acid (IDA), and iminodimethyl phosphonic acid (IDP). The performance of the resulting microreactors in Suzuki−Miyaura cross-coupling reactions was evaluated, finding that the poly(GMA-co-EDMA) monolith chemically modified with 5-amino-1,10-phenanthroline as a binding site for the palladium catalyst provided an excellent flow-through performance, enabling highly efficient and rapid reactions with high product yields. Moreover, this monolithic microreactor maintained its good activity and efficiency during prolonged use.

Seismic Performance Degeneration of Assembled Concrete Columns with Grouting Defects

In order to evaluate the influence of internal defects of semi-grouting sleeve connection on seismic performance of assembled monolithic columns, four specimens of assembled monolithic concrete column with semi grouting sleeve connecting reinforcement bar were fabricated with 10%, 20%, 30% internal defects. The test results show that (1) the assembled columns are all damaged by bending, the grouting layer of the assembled column can be pulled apart easily and the cracks develop more closely on the upper part of the sleeve; (2) the larger the internal defects in the sleeve, the less the cracks on the column, and the less sufficient the cracks development; (3) the seismic energy dissipation capacity of the column without defect is better than that of the defective columns.

ON THE ISSUE OF ESTIMATING THE EFFECTIVE LENGTH OF NON-CENTRALLY COMPRESSED REINFORCED CONCRETE ELEMENTS

Research work was carried out at NIIZHB named after A.A. Gvozdev, one of the tasks of which was to study the influence of the conditions for stiff fixing supports on the parameters of the effective lengths of reinforced concrete columns with square and rectangular cross-sections assigned when calculating the strength of normal sections. As part of the study, the influence of different values and directions of the angles of rotation of the fixing and their displacements was evaluated. The conducted computational and theoretical studies based on the analysis of experimental data showed that the method of determining the effective lengths, adopted in domestic standards, can be improved. Based on the results of the research, proposals were formulated to take the results of the work into account in the current regulatory framework. Taking into account the peculiarities of the conditions for fixing the structures considered in the work, which correspond to the nature of the work of monolithic columns and pylons, it is recommended to include the provisions of the proposed methodology in SP 430.1325800.2018, which applies to monolithic structural systems of buildings. The prepared proposals for the calculation are supposed to be included in the current regulatory documents as one of the possible options for determining the effective length of non-centrally compressed elements when calculating their strength.

Overview on liquid chromatography and its greener chemistry application

This literature review is concerning with liquid chromatography specifically high performance liquid chromatography (HPLC), Ultra high performance liquid chromatography (UHPLC), chromatography theory, chromatographic parameters, monolithic columns, principles of green chemistry and its application ingreen chromatography.

Selection of formwork systems for arrangement of monolithic columns according to the method of integer rating of laborability and process duration

The relevance of this article is related to the problem of standardization of technological processes in which there is construction equipment for concrete work. Almost all construction processes are performed using construction equipment. The arrangement of monolithic structures is accompanied by the processes of installation and dismantling of the formwork. It is impossible to make a reasonable choice of options for equipping construction processes according to the existing standard time norms. For all possible variants of column formwork, almost the same time norms are used [1]. The article considers the comparison of several formwork options for the installation of monolithic reinforced concrete columns of frame structures. To determine the duration and complexity of the process used the method of integer rationing [2], which allows taking into account even minor changes in the formwork. Calculation by this method makes it possible to select the most effective options for formwork. As a basis, this technique uses an analysis of the number of actions and responsibilities of these actions in relation to the quality of the process and its reliability. Any construction equipment is characterized by structural and technological versatility, which also affects the choice of options conditions of the process, so the article provides an analysis of these factors in terms of quality. If in the structure of the structure there are columns with different cross-sectional dimensions or heights, the preference is given to formwork options with greater structural versatility. The material of the article opens a whole direction for further research in the field of construction equipment in other processes.