Comprehensive exploration of chemical space using trisubstituted carboranes

A total of 42 trisubstituted carboranes categorised into five scaffolds were systematically designed and synthesized by exploiting the different reactivities of the twelve vertices of o-, m-, and p-carboranes to cover all directions in chemical space. Significant inhibitors of hypoxia inducible factor transcriptional activitay were mainly observed among scaffold V compounds (e.g., Vi–m, and Vo), whereas anti-rabies virus activity was observed among scaffold V (Va–h), scaffold II (IIb–g), and scaffold IV (IVb) compounds. The pharmacophore model predicted from compounds with scaffold V, which exhibited significant anti-rabies virus activity, agreed well with compounds IIb–g with scaffold II and compound IVb with scaffold IV. Normalized principal moment of inertia analysis indicated that carboranes with scaffolds I–V cover all regions in the chemical space. Furthermore, the first compounds shown to stimulate the proliferation of the rabies virus were found among scaffold V carboranes.

Analytical model of skip motion taking into account influence of head and balancing ropes

The article describes an analytical model of mine skip dynamics taking into account the presence of the head and balancing ropes and the existing curvilinearity of the guides. Expressions for the forces acting on the skip from the side of the guides have been constructed. It is shown, that the frequencies of natural vibrations of skip depend on the vertical acceleration and the distance traveled during its lifting. A graph (diagram) of skips vertical speed which observance does not lead to the appearance of skips vertical vibrations due to elasticity of the ropes is developed. An algorithm for finding the forces principal vector and the forces principal moment acting on the skip based on the reading of three accelerometers recording horizontal accelerations of skip during its movement is presented.

Approximate analysis of quadrilateral slabs having various cases of boundary conditions and aspect ratios

This paper provides an approximate analysis of quadrilateral slabs having various cases of aspect ratios and boundary conditions based on actual two-way action. Nine slabs with different boundary conditions, each having 11 aspect ratios were analyzed using SAP2000 software, thereafter, robustly validated against mathematical solutions. In this article, the hydrostatic point phenomenon was established as a reference point for identifying the slabs with actual two-way action and as a growth reference for other cases. This allows for the use of growth models for the hydrostatic and deviatoric moment tensors. The innovative selection of the extreme positive point moment facilitates the introduction of materials nonlinearity into the design. The plate shorter dimension was used for moment normalization in both directions to preserve the directional influence of the dimensions and to isolate the hydrostatic phenomenon. Through starting at a point of hydrostatic phenomenon occurrence and via fixing one of the plate’s dimensions and extending the other (for any boundary conditions), the extreme point’s Mohr circle develops from the hydrostatic point phenomenon as a growth in the hydrostatic component and drastic growth in the deviatoric component. Subsequently, the largest principal moment develops a higher magnitude as the aspect ratio increases. Furthermore, the non-identical boundary conditions on two perpendicular directions result in a deviation of the two-way action.

Study on the Thin Plate Model with Elastic Foundation Boundary of Overlying Strata for Backfill Mining

In order to better study the movement principles of overlying strata during backfill mining, we established a thin plate model on an elastic foundation with elastic foundation boundary of the main roof. And by the finite difference method, the variation principles of the main roof’s principal moments and maximum subsidence ω0 with the elastic foundation coefficient k1 of the coal seam, the elastic foundation coefficient k2 of backfill body, the thickness h, Young’s modulus E, and Poisson’s ratio μ of main roof are calculated and studied. Using these calculations, we were able to determine that the main roof had three principal bending moment extreme points, including Mzz in backfill areas, Mc of the long side area, and Md of the short side area. The distance Lc of Mc advancing coal wall continuously increased with the increase in k2, while the principal moment of main roof’s middle area decreased with an increase in k2; when k2 became larger, the maximum principal moment in the midpoint of main roof transferred to the surrounding and the maximum principal moments was in four-corner area; Mc and Md decreased with an increase in k2, and Md was more sensitive to k2 than Mc; and Md decreased significantly with the increase in k2. Lc continuously decreased with the increase in k1, while Mc, Md and Mzz increased with the increase in k1 and the reduced amplitude of Mzz was the minimum. The effect of μ on principal bending moments and ω0 was very small; The growth rate of Mzz was the largest when E or h increased. Md, Mzz, and Lc remained unchanged when k1, k2, and Young’s modulus E of the main roof increased while the ratio value remained constant (k1/k2/E). Finally, the theoretical calculations were applied to the I26 backfill working face in the Xingdong mine to calculate the final subsidence amounts of the main roof. Field observations and theoretical calculations were about 48 mm, verifying the method’s applicability.

Non–Linear Analysis of Slender Masonry Beam

This paper deals with numerical analysis and design of slander prismatic masonry beams loaded predominantly by axial force and bending moment in plane of the principal moment of inertia. Because of the material non-linearity, classical mathematical theory of slender columns cannot be applied for masonry elements, therefore the proposed method uses iterative non–linear calculation considering both material and geometrical non–linearity.

Micropore Structures in Cenosphere-Containing Cementitious Materials Using Micro-CT

Cenospheres have been recently applied to increase the volume of uniform micropores in hardened cementitious materials. Therefore, application of micro-CT to cenosphere-containing binders will help better understand the micropores formed by cenospheres in the hardened materials. Accordingly, the present study prepared Portland cement paste, alkali-activated fly ash/silica fume, and alkali-activated fly ash with 60% weight replacement by cenospheres and reconstructed their micropore structures using micro-CT. From the pore structure, individual micropores were extracted and analyzed using the principal moment ratios (I11/I33 and I22/I33). Based on the moment ratios, the representative pore shapes were determined in the different pore-volume ranges. Four-factor pore compliance contribution (4-factor PCC) model was then applied to predict the influences of the micropores on the elastic moduli of the micropore/matrix composites.

A Theoretical and Numerical Study of the Dzhanibekov and Tennis Racket Phenomena1

This paper presents a complete explanation of the Dzhanibekov and the tennis racket phenomena. These phenomena are described by Euler's equation for an unconstrained rigid body that has three distinct moment of inertia values. In the two phenomena, the rotations of a body about the principal axes that correspond to the largest and the smallest moments of inertia are stable. However, the rotation about the axis corresponding to the intermediate principal moment of inertia becomes unstable, leading to the unexpected rotations that are the basis of the phenomena. If this unexpected rotation is not explained from a complete perspective which accounts for the relevant physical and mathematical aspects, one might misconstrue the phenomena as a violation of the conservation of angular momenta. To address this, the phenomenon is investigated using more precise mathematical and graphical tools than those employed previously. The torque-free Euler equations are integrated using the fourth-order Runge–Kutta method. Then, a recovery equation is applied to obtain the rotation matrix for the body. By combining the geometrical solutions with numerical simulations, the unexpected rotations observed in the Dzhanibekov and the tennis racket experiments are shown to preserve the conservation of angular momentum.