Supramolecular complexation between cucurbit[7]uril and folate and analytical applications

Folate (FA) plays a key role in the biosynthesis of amino acids, purines, and pyrimidines in the human body, and intracellular folate metabolism has become an attractive target of tumor chemotherapy. In this work, an inclusion interaction was found between FA and cucurbit[7]uril (CB[7]), and the formation of a CB[7]-FA 2:1 supramolecular inclusion complex was confirmed by fluorescence spectra, UV-Vis absorption spectroscopy, 1H NMR, and molecular modeling calculations. In addition, FA is generally determined through the indirect fluorescent method because it shows weak fluorescence in aqueous solution. Therefore, a simple, direct fluorescence probe method for rapidly measuring FA was investigated, and the linear equation of FA was ΔF = 14.691C + 37.366 within the concentration ranges of 0.82 ~ 18.31 µg mL–1. The proposed direct fluorescence method was applied to the determination of spiked plasma. We demonstrated that this method could provide an experimental basis for the targeted administration of the CB[7]-FA complex, and it could be extended as a promising fluorescence detection method for drugs in vivo.

Computational Investigation of Inclusion Removal in the Steel-Refining Ladle Process

In a steel-refining ladle, the properties of manufactured steel can be notably degraded due to the presence of excessive inclusions. Stirring via gas injection through a porous plug is often used as part of the steel-refining process to reduce these inclusions. In this paper, 3D computational fluid dynamics (CFD) modeling is used to analyze transient multiphase flow and inclusion removal in a gas-stirred ladle. The effects of gas stirring with bubble-inclusion interaction are analyzed using the Euler–Euler approach for multiphase flow modeling, while the effects of inclusions aggregation and removal are modeled via a population balance model (PBM).

Quantifying progressive failure of micro-anchored fiber optic cable–sand interface via high-resolution distributed strain sensing

Distributed fiber optic sensing (DFOS) is gaining increasing interest in geotechnical monitoring. By using soil-embedded fiber optic cables, strain profiles as well as deformation patterns of geotechnical infrastructures can be captured. Probing the fiber optic cable–soil interfacial behavior is vital to the advancement of DFOS-based geotechnical monitoring and our understanding of the soil–inclusion interaction mechanism. To this aim, laboratory pullout tests were performed to investigate the progressive failure of the interface between micro-anchored cables and the surrounding sand. High-resolution strain profiles recorded using Brillouin optical time-domain analysis (BOTDA) not only elucidated the influence of anchorage on strain measurements, but also allowed the classical soil–inclusion interaction problem to be studied in detail. Interfacial shear stresses calculated from step-like strain profiles provided clear evidence of the contribution of each micro-anchor to the pullout resistance. The cable–soil contact is a combination of overall bonding and point fixation depending on the level of mobilized interfacial shear stress, and therefore the validity of measured strains is correlated to a three-stage process of interface failure. This study also shows that installing heat-shrink tubes on the fiber optic cable is a rapid, low-cost, effective approach to make an anchored DFOS system for deformation monitoring of earth structures.

Formation mechanisms of maximal loads on cutters and cutting heads of coal mining machines

Purpose. To determine an influence exerted by the cutting mode and by geometry of cutters on the impact loads in various scenarios of cuttersolid inclusion interaction. Methodology. Mathematical simulation, statistical analysis Findings. Fracture of coal seams of a complex structure which contain solid discontinuities (solid inclusions and hard dirt bands) is associated with generation of impact loads on cutters and cutting heads of mining machines which cause a decrease in the productivity of the coal extraction process and premature failure of their components and elements. This impairs efficiency of coal cutting and causes premature failure of different components and parts. It is found that when a cutter cuts an inclusion or touches it, the size of the inclusion has no influence on the value of the peak load. On the contrary, in case of tear-out of an inclusion, the peak cutting force value essentially depends on the size and shape of the inclusion, as well as on the brittleness and plasticity of coal as these properties govern coal-inclusion cohesion. It is found that out of all modes of cutter-solid inclusion interaction, the highest loads arise in the mode of central cutting of inclusions. The mechanisms and behavior of occurrence of loads in short-term cutting of large (unbroken) solid inclusions by a group of cutters are discussed. The maximal loads on groups of cutters on cutting heads can also arise in gradual stalling when the average loading level approaches the tractive effort torque of electric motor when a group of cutters cuts many solid inclusions simultaneously, or in undermining of roof rocks, or in cutting hard dirt bands. Originality. The probabilities of solid inclusion cutting by a cutter are determined for different outputs of a cutting head, and the action times of the maximal peak load in cutting a coal strip 100 m long are assessed. The relations are proposed to calculate the levels and action times of maximal loads on a group of cutters in cutting solid inclusions, as well as the coefficients of variation in the loads and the loading inequality of a cutting head. Practical value. The results obtained by the authors should be taken as a basis in determination of the maximal instantaneous torque in the cutting head transmission to be used later on in calculation of the long-term strength of the transmission components.

A novel pillar[5]arene-based emission enhanced supramolecular sensor for dual-channel selective detection and separation of Hg2+

We constructed a supramolecular sensor (APRA–G) via a host–guest inclusion interaction between a rhodamine hydrazide-functionalized pillar[5]arene (APRA) and a bipyridine salt guest (G), which formed a stable dimer.