Polyhedral oligomeric silsesquioxanes (POSS) are of considerable interest as building blocks for preparing low‐k materials. To date T8 POSS has been extensively investigated while the potential of larger POSS cages remain an unexplored area. Herein, the first known contribution to map the role of POSS cage size on the dielectric and other comprehensive properties of hybrid materials with identical chemical compositions is described. First, three vinyl POSS (T8, T10, and T12) species are isolated from a commercial POSS mixture. Then, they are converted to benzocyclobutene functionalized and thermo‐crosslinked hybrid materials. It is found that the cage size can strongly affect their k values, more importantly, showing a linear decrease while increasing the cage volumes (k = 2.24, 2.02, and 1.83 for c‐T8B8, c‐T10B10, and c‐T12B12, respectively). This finding highlights a profound influence of POSS cage changes on dielectric properties and could be used to predict ultralow‐k (1.5–1.1) materials by extrapolating to larger T14, T16, and T18 POSS cages. Meanwhile, varying the cage size has no obvious effect on the materials’ other properties, and all of them exhibit good comprehensive properties. Moreover, such low‐k values can persist at high temperature and high humidity conditions, which affords some promising (ultra)low‐k dielectrics for modern integrated circuit development.
Evans blue (EB) dye has owned a long history as a biological dye and diagnostic agent since its first staining application by Herbert McLean Evans in 1914. Due to its high water solubility and slow excretion, as well as its tight binding to serum albumin, EB has been widely used in biomedicine, including its use in estimating blood volume and vascular permeability, detecting lymph nodes, and localizing the tumor lesions. Recently, a series of EB derivatives have been labeled with PET isotopes and can be used as theranostics with a broad potential due to their improved half-life in the blood and reduced release. Some of EB derivatives have even been used in translational applications in clinics. In addition, a novel necrosis-avid feature of EB has recently been reported in some preclinical animal studies. Given all these interesting and important advances in EB study, a comprehensive revisiting of EB has been made in its biomedical applications in the review.
With the increasingly strict diesel standards in the countries of the world, deep processing of diesel oil to ultralow sulfur levels is receiving more and more attention. This paper mainly reviews the reaction mechanism, catalysts, and process conditions of diesel hydrodesulfurization, and it provides new research directions for producing ultralow sulfur diesel (ULSD). In terms of mechanism, the sterically hindered sulfides, nitrides, aromatic compounds, and hydrogen sulfide affect the direct desulfurization and hydrogenate pathways of the hydrodesulfurization reaction to varying degrees. In order to eliminate these effects, the properties of high-dispersion active metals, large pore size, high specific surface area, high content of medium-weak acid, and a certain amount of Bronsted acid support are beneficial to further improve the activity of the catalyst, to produce ULSD that meets market demand. This article also reviews the influences of process conditions (for instance, temperature, hydrogen pressure, liquid hourly space velocity, and hydrogen consumption) on the diesel ultradeep hydrodesulfurization reaction, and it finds those moderately high temperatures and high hydrogen partial pressures, as well as low space velocity, to be beneficial. In short, the development of new catalysts is the current research hotspot in the field of ultradeep hydrodesulfurization of diesel, and further research is still needed.
We present an energy-conserving multiple-relaxation-time finite difference lattice Boltzmann model for compressible flows. This model is based on a 16-discrete-velocity model. The collision step is first calculated in the moment space and then mapped back to the velocity space. The moment space and corresponding transformation matrix are constructed according to the group representation theory. Equilibria of the nonconserved moments are chosen according to the need of recovering compressible Navier-Stokes equations through the Chapman-Enskog expansion. Numerical experiments showed that compressible flows with strong shocks can be well simulated by the present model. The used benchmark tests include (i) shock tubes, such as the Sod, Lax, Sjogreen, Colella explosion wave and collision of two strong shocks, (ii) regular and Mach shock reflections, and (iii) shock wave reaction on cylindrical bubble problems. The new model works for both low and high speeds compressible flows. It contains more physical information and has better numerical stability and accuracy than its single-relaxation-time version.Comment: 11 figures, Revte
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