Indoles and hydantoins are important heterocycles scaffolds which present in numerous bioactive compounds which possess various biological activities. Moreover, they are essential building blocks in ...organic synthesis, particularly for the preparation of important hybrid molecules. The series of hybrid compounds containing indoles and imidazolidin-2-one moiety with direct C-C bond were synthesized using an amidoalkylation one-pot reaction. All compounds were investigated as a growth regulator for germination, growth and development of wheat seeds (
L). Their effect on drought resistance at very low concentrations (4 × 10
M) was evaluated. The study highlighted identified the leading compounds,
a and
e, with higher growth-regulating activity than the indole-auxin analogues.
Natural and synthetic phytohormones are widely used in agriculture. The synthetic cytokinin ethylenediurea (EDU) induces protection in plants against ozone phytotoxicity. In our study, new hybrid ...derivatives of EDU were synthesized and tested for phytoactivity. The germination potential (Gp), germination of seeds (G), and relative water content in leaves (RWC), characterizing the drought resistance of plants, were determined. The results of laboratory studies showed that EDU and its hybrid derivatives have a positive effect on root length, the growth and development of shoots, as well as the ability of plants to tolerate stress caused by a lack of water.
Abstract
The paper presents the obtained results of the vibration studies, particularly, the structural elements of the railway rolling stock, created at the driver workplaces, structures of the ...internal combustion engines, hoods, frames while moving and a stationary machine, which determine the vibration spectral composition and propose the specific engineering solutions for the noise and vibration protection system.
Small fission chambers manufactured by Photonis, Reuter-Stokes, CEA, and Centronic are routinely calibrated in standard neutron fields of the BR1 reactor at SCK CEN in Mol, Belgium. Two irradiation ...fields are available: fast spectrum in the MARK3 convertor and thermal spectrum in the Empty Cavity. In this work, for the first time the calibration procedure of larger fission chambers (Photonis CFUL01 and CFUM21 type) with the deposit length exceeding the length of the convertor is presented. Spatial energy correction factors taking into account the neutron flux shape beyond the convertor and radial gradient of the neutron flux were calculated with MCNP and experimentally validated. The combination of calibration (i.e., effective mass measurement) in fast and thermal irradiation fields allows for determination of the purity of 238 U deposit. This is demonstrated on three CFUL01-type fission chambers with purity between 99.8% and 99.998%.
This review aims at becoming a guide which will help to plan the experimental design and to choose adequate methods to assess the outcomes when testing cell-based products in the treatment of the ...damaged vocal folds. The requirements to preclinical trials of cell-based products remain rather hazy and dictated by the country regulations. Most parameters like the way the cells are administered, selection of the cell source, selection of a carrier, and design of in vivo studies are decided upon by each research team and may differ essentially between studies. The review covers the methodological aspects of preclinical studies such as experimental models, characterization of cell products, assessment of the study outcome using molecular, morphological and immunohistochemical analyses, as well as measuring the tissue physical properties. The unified recommendations to perform preclinical trials could significantly facilitate the translation of cell-based products into the clinical practice.
Improving the quality of products causes an increase in the requirements for the accuracy of the dimensions and shape of the surfaces of the workpieces. This, in turn, raises the requirements for ...accuracy and productivity of measuring of the workpieces. The use of coordinate measuring machines is currently the most effective measuring tool for solving similar problems. The article proposes a method for optimizing the number of control points using Monte Carlo simulation. Based on the measurement of a small sample from batches of workpieces, statistical modeling is performed, which allows one to obtain interval estimates of the measurement error. This approach is demonstrated by examples of applications for flatness, cylindricity and sphericity. Four options of uniform and uneven arrangement of control points are considered and their comparison is given. It is revealed that when the number of control points decreases, the arithmetic mean decreases, the standard deviation of the measurement error increases and the probability of the measurement α-error increases. In general, it has been established that it is possible to repeatedly reduce the number of control points while maintaining the required measurement accuracy.
We have studied the spectral properties of the inhomogeneities in the surface profile of a quartz plate in the spatial range from 10 μm to 100 mm on the basis of precision interferometric ...measurements. Analytical integral relations connecting one- and two-dimensional spectral densities of an isotropic random function, such as surface profile or spatial phase distribution of the laser beam, were obtained. It is shown that if the one-dimensional spectral density in a certain range of spatial frequencies decreases in a power-law manner, then the two-dimensional spectral density in the same range also decreases in a power-law manner with an exponent greater by one. The experimental data are in good agreement with the theoretical ones.
Planning an achievable trajectory for a mobile robot usually consists of two steps: (i) finding a path in the form of a sequence of discrete waypoints and (ii) transforming this sequence into a ...continuous and smooth curve. To solve the second problem, this paper proposes algorithms for automatic dynamic smoothing of the primary path using a tracking differentiator with sigmoid corrective actions. Algorithms for setting the gains of the differentiator are developed, considering a set of design constraints on velocity, acceleration, and jerk for various mobile robots. When tracking a non-smooth primary path, the output variables of the differentiator generate smooth trajectories implemented by a mechanical plant. It is shown that the tracking differentiator with a different number of blocks also generates derivatives of the smoothed trajectory of any required order, taking into account the given constraints. Unlike standard analytical methods of polynomial smoothing, the proposed algorithm has a low computational load. It is easily implemented in real time on the on-board computer. In addition, simple methods for modeling a safety corridor are proposed, taking into account the dimensions of the vehicle when planning a polygon with stationary obstacles. Confirming results of numerical simulation of the developed algorithms are presented.
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