Численное моделирование решения одномерных задач термоупругости при наличии теплового потока, меняющегося по координате линейным и нелинейным законами

Многие элементы конструкций одновременно испытывают воздействия температуры, теплового потока, теплообмена и наружных механических сил с различными амплитудными характеристиками. При таких воздействиях стержневые элементы конструкций могут не выдержать, что приводит к разрушению всей конструкции. Этот вопрос весьма актуален. Статья посвящена построению универсального вычислительного алгоритма, основанного на применении метода конечных элементов. Суть которого - дискретизация нелинейными конечными элементами исследуемой конструкции. Кроме того, определен закон распределения температуры по объему последней, минимизируя который по узловым значениям перемещений, получаем поле упругих, температурных и термоупругих составляющих компонентов деформаций и напряжений

Comparative morphological and anatomical characteristics of Saussurea amara (L.) DC. and S. salsa pall. Spreng

In this paper, the authors conducted research of the comparative morphological and anatomical characteristics of two species of Saussurea, which grow in the steppes of Central Kazakhstan - S. amara L. (S. bitter) and S. salsa Pall. Spreng. (S. solonchak). Researchers revealed a number of clear distinctive morphological and anatomical signs of the over ground organs of S. amara and S. salsa, which make it possible to distinguish these species both as at the stage of collection of plants and also in the process of laboratory examination of the raw materials. The distinctive features of the anatomical stems of S. amara and S. salsa are the degree of furrows, strongly marked sclerenchyma of the conducting beams, and the size of parenchymatous cells of the primary cortex and the core. S. amara compared with S. salsa is characterized by more furrowed stems, less sclerenchyma in the conducting vascular bundles and smaller parenchymatous cells

Design of small molecule-responsive microRNAs based on structural requirements for Drosha processing

MicroRNAs (miRNAs) are prevalent regulatory RNAs that mediate gene silencing and play key roles in diverse cellular processes. While synthetic RNA-based regulatory systems that integrate regulatory and sensing functions have been demonstrated, the lack of detail on miRNA structure–function relationships has limited the development of integrated control systems based on miRNA silencing. Using an elucidated relationship between Drosha processing and the single-stranded nature of the miRNA basal segments, we developed a strategy for designing ligand-responsive miRNAs. We demonstrate that ligand binding to an aptamer integrated into the miRNA basal segments inhibits Drosha processing, resulting in titratable control over gene silencing. The generality of this control strategy was shown for three aptamer–small molecule ligand pairs. The platform can be extended to the design of synthetic miRNAs clusters, cis-acting miRNAs and self-targeting miRNAs that act both in cis and trans, enabling fine-tuning of the regulatory strength and dynamics. The ability of our ligand-responsive miRNA platform to respond to user-defined inputs, undergo regulatory performance tuning and display scalable combinatorial control schemes will help advance applications in biological research and applied medicine

A fast and efficient translational control system for conditional expression of yeast genes

A new artificial regulatory system for essential genes in yeast is described. It prevents translation of target mRNAs upon tetracycline (tc) binding to aptamers introduced into their 5'UTRs. Exploiting direct RNA–ligand interaction renders auxiliary protein factors unnecessary. Therefore, our approach is strain independent and not susceptible to interferences by heterologous expressed regulatory proteins. We use a simple PCR-based strategy, which allows easy tagging of any target gene and the level of gene expression can be adjusted due to various tc aptamer-regulated promoters. As proof of concept, five differently expressed genes were targeted, two of which could not be regulated previously. In all cases, adding tc completely prevented growth and, as shown for Nop14p, rapidly abolished de novo protein synthesis providing a powerful tool for conditional regulation of yeast gene expression

Logic integration of mRNA signals by an RNAi-based molecular computer

Synthetic in vivo molecular ‘computers’ could rewire biological processes by establishing programmable, non-native pathways between molecular signals and biological responses. Multiple molecular computer prototypes have been shown to work in simple buffered solutions. Many of those prototypes were made of DNA strands and performed computations using cycles of annealing-digestion or strand displacement. We have previously introduced RNA interference (RNAi)-based computing as a way of implementing complex molecular logic in vivo. Because it also relies on nucleic acids for its operation, RNAi computing could benefit from the tools developed for DNA systems. However, these tools must be harnessed to produce bioactive components and be adapted for harsh operating environments that reflect in vivo conditions. In a step toward this goal, we report the construction and implementation of biosensors that ‘transduce’ mRNA levels into bioactive, small interfering RNA molecules via RNA strand exchange in a cell-free Drosophila embryo lysate, a step beyond simple buffered environments. We further integrate the sensors with our RNAi ‘computational’ module to evaluate two-input logic functions on mRNA concentrations. Our results show how RNA strand exchange can expand the utility of RNAi computing and point toward the possibility of using strand exchange in a native biological setting

Synthetic human cell fate regulation by protein-driven RNA switches

Understanding how to control cell fate is crucial in biology, medical science and engineering. In this study, we introduce a method that uses an intracellular protein as a trigger for regulating human cell fate. The ON/OFF translational switches, composed of an intracellular protein L7Ae and its binding RNA motif, regulate the expression of a desired target protein and control two distinct apoptosis pathways in target human cells. Combined use of the switches demonstrates that a specific protein can simultaneously repress and activate the translation of two different mRNAs: one protein achieves both up- and downregulation of two different proteins/pathways. A genome-encoded protein fused to L7Ae controlled apoptosis in both directions (death or survival) depending on its cellular expression. The method has potential for curing cellular defects or improving the intracellular production of useful molecules by bypassing or rewiring intrinsic signal networks

Состав и содержание экдистероидов в растениях Silene fruticulosa (Pall.) Schischk

The ecdysteroid profile of Silene fruticulosa (Pall.) Schischk growing in Kazakhstan has been investigated. It has been shown that the plant contained ecdysterone (2.4 g/kg of dry weight), 2-deoxyecdysone (0.45 g/kg) and 2-deoxyecdysterone (0.11 g/kg).Предпринято изучение экдистероидного профиля смолевки кустарничковой Silene fruticulosa (Pall.) Schischk, которая встречается на всей территории Казахстана в природных местообитаниях. Показано, что надземные части данного растения содержат экдистерон (содержание 2.4 г/кг сухой массы), 2-дезоксиэкдизон (0.45 г/кг) и 2-дезоксиэкдистерон (0.11 г/кг)

Micropatterning of Aptamer Beacons to Create Cytokine-Sensing Surfaces

Aptamer beacons are DNA or RNA probes that bind proteins or small molecules of interest and emit signal directly upon interaction with the target analyte. This paper describes micropatterning of aptamer beacons for detection of IFN-γ—an important inflammatory cytokine. The beacon consisted of a fluorophore-labeled aptamer strand hybridized with a shorter, quencher-carrying complementary strand. Cytokine molecules were expected to displace quenching strands of the beacon, disrupting FRET effect and resulting in fluorescence signal. The glass substrate was first micropatterned with poly(ethylene glycol) (PEG) hydrogel microwells (35 μm diameter individual wells) so as to define sites for attachment of beacon molecules. PEG microwell arrays were then incubated with avidin followed by biotin-aptamer-fluorophore constructs. Subsequent incubation with quencher-carrying complementary strands resulted in formation of DNA duplex and caused quenching of fluorescence due to FRET effect. When exposed to IFN-γ, microwells changed fluorescence from low (quencher hybridized with fluorophore-carrying strand) to high (quenching strand displaced by cytokine molecules). The fluorescence signal was confined to microwells, was changing in real-time and was dependent on the concentration of IFN-γ. In the future, we plan to co-localize aptamer beacons and cells on micropatterned surfaces in order to monitor in real-time cytokine secretion from immune cells in microwells

Mathematical modelling and development of a computational algorithm for the study of thermo-stressed state of a heat-resistant alloy

The problem of increasing the thermal stability of structural elements made of heat-resistant metals and alloys operating in a complex force and thermal field is one of the key priorities of modern high technology research. The most important case is the study of the thermal stability of structural elements in real conditions of heat fluxes with varying intensity, with a complex configuration of heat-insulated local surfaces and internal point heat sources. Many basic load-bearing structural elements operating in a large thermal field (elements of gas turbine and jet engines, etc.), are made of heat-resistant alloys. The physical feature of such alloys is that the coefficient of thermal expansion and the modulus of elasticity of the material strictly depends on the temperature distribution field, that is, the coefficients are a function of temperature. The purpose of this study is to simulate a thermo-stressed state in rod elements of a structure based on the law of conservation of energy, in the presence of a heat flux applied on the lateral surface, which varies along the coordinate in a linear manner. To solve the outlined problem, a potential energy minimisation method is used in combination of a quadratic finite element with three nodes. As a result, from the condition of the minimum of the functional defining the potential energy, a resolving system of linear algebraic equations is obtained. All possible natural boundary conditions are taken into account. In this system, all integrals used are calculated analytically. Moreover, the law of conservation of energy is fulfilled for each of the equations of the resulting system. As a result, the values of displacement, deformation and stresses were calculated, as well as the values of elastic temperature and thermoelastic components of deformations and stresses for a specific example