The use of small-sized models of structures printed on 3-D printers is possible due to the electroelastic properties of ABS plastic. A comparison of their reactions with analogs made of plexiglas, ...used in studies of concrete structures, was made. The influence of the environment - water or sea sand, support conditions - free support or pinching, shape - simple or complex in planon the response of models from two different materials was investigated. The laboratory setup simulated a dynamic sinusoidal effect using: a digital frequency generator from 1 to 10000 Hz, an acoustic system diffuser, a microphone amplifier, two electrodes, and a computer in a two-channel oscilloscope mode. The vibration characteristics at the base and top of the models were recorded. The experimental system turned out to be sensitive to the shape, methods of fastening elements, the structure as a whole, and the medium of wave propagation. The response was analyzed in terms of the dynamic compliance coefficient and resonance frequencies, reflecting the similarity of the responses of the plexiglas and ABS models. Printing will allow you to adjust the shape and connections of the elements of the models so that they work like mechanical resonators – filters - in a narrow band. No resonances are expected outside this band. In the operated structures, the quality of the element connections is reproduced. Changing the existing rigidity to obtain resonances in a narrow band can serve as a criterion for choosing an effective amplification method.
The article presents a method for calculating the erosion furrow depth and the metal loss of piles and other structures of marine hydraulic facilities under wave action containing a water-pebble ...mixture (pebble bombardment of piles).
In article the possibility of use of magnetic fluid as a sensitive element for fixing of change of induction of magnetic field in space is considered. Importance of solvable tasks is connected with ...search of the perspective magnetic substances susceptible to weak magnetic field. The results of a study of the capacitive method for fixing the change in the magnetic field on the basis of a ferromagnetic liquid are presented. The formation of chain structures in the ferrofluid from magnetic particles under the influence of the applied magnetic field leads to a change in the capacitance of the plate condenser. This task has important practical value for development of a magnetosensitive sensor of change of magnetic field.
The dataset contains microclimate parameters including air temperature, relative humidity and dew point measurements from a large wetland, Shichengskoe mire system, in Vologda Region, Russia, during ...four vegetation periods. Data were collected in 2013–2015 and 2017 using DT-171 data loggers (Elma Instruments). Data loggers were attached to the wooden posts at 0.5 m height from the surface. Continuous recordings were performed every 30 min providing 48 measurements of air temperature, relative humidity and dew point per day. The dataset presented in the article is of particular value to understanding the heterogeneity of abiotic parameters within mire systems.
The ultrastructure of sperm morphology and some aspects of acrosomal complex development were examined in Kulikovia alborostrata, K. torquata, Kulikovia sp., and Micrura bella using transmission and ...scanning electron microscopy. The studied Kulikovia species have spermatozoa with a bullet-shaped head consisting of an acrosomal complex with a single cup-like acrosomal vesicle, a cone-shaped nucleus, and a short midpiece that are characteristic of the ect-aquasperm type. Despite the general similarity in spermatozoon organization, an ultrastructural analysis has revealed some species-specific size differences. M. bella is distinguished by an elongated curved sperm head with an acrosomal complex containing one large electron-dense and a few small, moderately electron-dense acrosomal vesicles. As a rule, five mitochondria are located in the midpiece in all the studied species. According to data published in literature and the present findings, all Pilidiophora have spermatozoa with several (three, four or five) mitochondria, and they never contain a single mitochondrion. We suggest this trait to be a synapomorphy for the class Pilidiophora, while the posterior acrosomal ring component, an annular structure formed by the basal part of the acrosomal vesicle, to be a synapomorphy for Heteronemertea. Acrosomal vesicles develop from numerous proacrosomal vesicles that are synthesized in spermatocytes I and fuse (or partly fuse in M. bella) at the spermatid stage. We regard the separate small acrosomal vesicles in the acrosomal complex of M. bella spermatozoa as the retention of an ancient trait in the sperm structure via “progenetic spermatogenesis” during the sperm cell development.
•Micrura bella has an unique multivesicular acrosomal complex•Kulikovia spp. have a simple single-vesicle acrosomal complex•Initial proacrosomal vesicles in all species emerge in spermatocytes I•The acrosomal organization in M. bella may result from “progenetic spermatogenesis”•Midpiece with 3-4-5 mitochondria is a synapomorphy for the class Pilidiophora
This article presents data on the mesonephros histology and ultrastructure in the Atlantic salmon from the Baltic Sea and Barents Sea populations, with an emphasis on comparisons between the ...following ontogenetic stages: parr, smolting, adult life at sea, the adults' return to their natal river to spawn, and spawning. The ultrastructural changes in the renal corpuscle and cells of the proximal tubules of the nephron occurred as early as the smolting stage. Such changes reflect fundamental alterations during the pre-adaptation to life in saltwater. In the Barents Sea population, the adult salmon sampled in the sea had the smallest diameters of the renal corpuscle and proximal and distal tubules, the most narrow urinary space, and the thickest basement membrane. In the group of salmon that entered the mouth of the river and spent less than 24 h in freshwater, the structural rearrangements occurred only in the distal tubules. Better development of the smooth endoplasmic reticulum and a greater abundance of mitochondria in the tubule cells were observed in the adult salmon from the Barents Sea compared to those from the Baltic Sea. Cell-immunity activation was initiated during the parr-smolt transformation. Another pronounced innate-immunity response was registered in the adults returning to the river to spawn.
—The paper reports mineral chemistry, whole-rock major and trace element composition, structure, and geological setting of the phlogopite peridotite lens within the Bug granulite–gneiss terrane of ...the Dniester–Bug Province, Ukrainian Shield. Geochemical features of the studied peridotites and minerals indicate a complex evolution of the lens. The early stage is marked by the crystallization of olivine + spinel (Al-chromite) cumulus from melt of supposably picritic composition, and further crystallization of clinopyroxene. The melt shows signs of hybridization by host gneissic enderbite. Orthopyroxene crystallized later and frequently replaces clinopyroxene. The phlogopite cystallization is likely related to the fluid activity and the growth of potassium potential in the fluid. Granulite-facies metamorphism accompanied by ductile deformations affected the mineral asseblage and chemical compositions of peridotites and orthopyroxenites. At the final stage, the rocks and minerals experienced retrograde metamorphism and local foliation of the rocks.
The ground control using optical fibers is discussed. The designed monomode fiber pressure sensor is capable to perform high-precision measurement of overlying rock mass pressure imposed on walls of ...underground excavation. The mathematical apparatus is presented for the calculation of radiation intensity of optical wave traveling along an optical fiber with and with no mechanical effects. The simulation model is developed for an underground excavation with steel arch support. The model is equipped with the fiber-optic monitoring system and pressure sensors. This model enables practicing the ground control methods and measurements. The critical element of the simulation model is its hardware/software complex with interface showing four check zones with fiber-optic pressure sensors. This monitoring system is explosion-proof and is suitable for operation in super hazardous mines in terms of gas and dust outbursts.
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