Search

Pachyonychis paradoxus Clark, 1860 and Pachyonychus paradoxus Melsheimer, 1847 are two species of Alticini whose strikingly similar names have led to significant confusion in the past. Recent study of American Oedionychina Chapuis, 1875 raised doubts about the validity of the subtribal placement of Pachyonychis Clark. Although general characteristics put this genus in Oedionychina, other features, especially the unusual shape of the pronotum, suggested that this monotypic genus would belong in Monoplatina Chapuis, 1875 instead. To collect evidence for the validity of its current placement, we compared external and genitalic morphology of both species to other members of Monoplatina and Oedionychina. Here we present images and descriptions of female genitalia for both species and male genitalia of Pachyonychus paradoxus Melsheimer, to our knowledge the first of their kind, and we conclude that the evidence supports the current subtribal placement of these two genera. Lectotypes are designated for both Pachyonychis paradoxus Clark and Pachyonychus paradoxus Melsheimer.

In modern economic and industrial realities, agricultural lands are often located next to industrial areas, which leads to soil contamination and, as a result, agricultural products with pollutants. Pollution of soils and plants by several pollutants of various nature has acquired huge proportions. There is a threat of migration of dangerous ecotoxicants, including heavy metals and benz[a]pyrene, one of the main persistent compounds, a marker of PAH soil contamination, along trophic chains that may be dangerous to public health. This study examines the use of various types of mineral sorbents (Tripoli, Brown coal, Diatomite) and mineral sorbents (Biochar, Granular activated coal) to reduce the toxic effects of pollutants on the sources of anthropogenic emissions of heavy metals and polycyclic aromatic hydrocarbons adjacent to the sources. Using scanning electron microscopy, it was found that the sorbents have a high specific surface area. With the help of phytotesting in combined contaminated soils, the optimal dose of sorbent administration was determined at the level of 1% and 2% for various pollution variants. In addition, the analyzed sorbents are ordered by the effect of reducing the phytotoxicity of combined soil pollution. It was found that the introduction of sorbents into contaminated soil contributed to an increase in the morphometric parameters of the test culture - barley (Hordeum sativum distichum), which confirms the effectiveness of the sorption remediation of jointly contaminated soils with heavy metals and benz(a)pyrene.

The use of DNA barcoding has revolutionized biodiversity science, but its application depends on the existence of comprehensive and reliable reference libraries. For many poorly known taxa, such reference sequences are missing even at higher-level taxonomic scales. We harvested the collections of the Smithsonian’s National Museum of Natural History (USNM) to generate DNA barcoding sequences for genera of terrestrial arthropods previously not recorded in one or more major public sequence databases. Our workflow used a mix of Sanger and Next-Generation Sequencing (NGS) approaches to maximize sequence recovery while ensuring affordable cost. In total, COI sequences were obtained for 5,686 specimens belonging to 3,888 genera and 202 families. Success rates varied widely according to collection data and focal taxon. NGS helped recover sequences of specimens that failed a previous run of Sanger sequencing. Success rates and the optimal balance between Sanger and NGS are the most important drivers to maximize output and minimize cost in future projects. The corresponding sequence and taxonomic data can be accessed through the Barcode of Life Data System, GenBank, the Global Biodiversity Information Facility, the Global Genome Biodiversity Network Data Portal and the NMNH data portal.

To study the dynamic strength of pipe steels, a cycle of dynamic tests of three grades of pipeline steels (X80, X90, and X100) was performed, which included three types of experiments based on the Kolsky method: uniaxial tension of smooth specimens, as well as tension of specimens with a V-shaped annular notch and Charpy impact test according to the three-point bending pattern of beam-type specimens with a V-notch. In the last two cases, the fracture force and impact toughness, as well as the nominal fracture stress in the specimen, were determined. To assess the effect of “cold brittleness” and determine the temperature of the ductile-brittle transition, the specified test cycle was carried out in the temperature range from +20°C to –100°C. As shown by the test results, the studied steels have a fairly high ductility: the elongation at break is 25-30%. Therefore, the destruction of specimens directly in the first load cycle is not always possible. The use of an original system for registering additional loading cycles makes it possible to determine in which loading cycle the specimen ruptured. The limiting characteristics of plasticity (ψ and δ) of all tested steel grades are weakly dependent on both the strain rate and temperature (within the range of their variation). Whereas the impact toughness of steels significantly (2-3 times) decreases with a decrease in temperatures from room temperature to –100°C.

The paper presents the results of dynamic testing of two wood species: lime-tree (Tilia europoea) and pine (Pinaceae). The dynamic compressive tests were carried out using the traditional Kolsky method in compression tests. The Kolsky method was modified for testing the specimen in a rigid limiting holder. In the first case, stress–strain diagrams for uniaxial stress state were obtained, while in the second, for uniaxial deformation. To create the load a gas gun was used. According to the results of the experiments, dynamic stress–strain diagrams were obtained. The limiting strength and deformation characteristics were determined. The fracture energy of lime and pine depending on the type of test was also obtained. The strain rates and stress growth rates were determined. The influence of the cutting angle of the specimens relative to the grain was noted. Based on the results obtained, the necessary parameters of the wood model were determined and their adequacy was assessed by using a special verification experiment.

Metallic materials with a nanocrystalline or ultrafine-grained (UFG) structure can exhibit increased strength, albeit with reduced ductility. The behaviour of such materials under high-speed and impact loads has been insufficiently explored. This work presents experimental results on the dynamic response of UFG pure copper (99.95%) processed by equal-channel angular pressing (ECAP) in comparison with its initial coarse-grained (CG) structure. The yield strength in the case of compression tests of cylindrical samples and the energy consumed for deformation and fracture in the case of a three-point bending of a beam with a V-notch are considered. The UFG copper has higher yield strength in compression tests, but its sensitivity to the loading rate is significantly less than that of the CG initial material and depends on the number of ECAP passes. The UFG material shows higher impact toughness KCV and energy consumption for the entire process of deformation and fracture under impact three-point bending.

International audience; Experimental results on assessing the effects of strain and stress rates on the behavior of fine-grain concretes are presented. Specimens of fine-grain and fiberreinforced concretes were dynamically tested using the Kolsky method and its modification, the “Brazilian test”. As a result of the experiments, values of the Dynamic Increase Factor (DIF) were determined for both the materials studied. Their curves as a function of strain and stress rates were constructed. The experimental data is compared with the theoretically obtained values of DIF as a function of strain rate available in the literature

This work presents results of an experimental and theoretical study on dynamic and quasi-static failure of rocks and concrete. The results of dynamic compression and splitting of rocks (gabbro, granite, marble), as well as dry, water-saturated and frozen limestone and concrete are discussed. The tests were conducted using the Split-Hopkinson pressure bar with the diameter of 20 mm. It is shown that one material (or its condition) can have a lower dynamic strength for a higher static strength compared to the other material (or its condition). Also, it is shown a dependence of the threshold limit stress on the stress pulse duration. An unified interpretation of the experimental results, based on the structural–temporal approach is presented.

It was concluded that the need to define the essence of social norms is secondary to the development of the concept of such norms in assessing the stability and dynamism of social norms in the legal and economic doctrine of the business ecosystem. The study of the influence of social norms on the sphere of regulation of economic entities’ activity, especially under conditions of technological modernization, suggests that the current Russian economic reality exists in a state of so-called “anomie”. It was found that the polyvalent processing of economic transactions in the entrepreneurial ecosystem can work effectively and efficiently at the organizational level but not at the market level. Accordingly, the economic organization as a form and process of relations is the point of reference for the theoretical architecture of relational economics. In this respect, the governance structure must adapt flexibly to social norms and cope with different but interacting polycontextual decision-making logics.

The paper presents the results of studying the structure and wear resistance of compacts produced from fine dispersed reduced iron powder (average particle size 3– 5 μ m) with the addition of tungsten carbide (WC) nanopowder with the average particle size of 25–30 nm. The mass fraction of tungsten carbide (wolfram carbide) in the powder composition was 5% and 10% of the total mass. Impulse pressing was conducted using the modified Kolsky method at compacting temperatures of 20 °C to 300 °C. The produced compacts had relative density of over 90%. Metallographic studies using the scanning electronic microscopy method on a TESCAN VEGA II electronic microscope have shown that the produced compacts have a fairly homogeneous fine-grained structure, with a uniform pattern of pore distribution, the form of the pores being close to spherical. X-ray microanalysis using an INCA Energy 250 energy-dispersion spectrometer with scanning along the surface line and transversal laps testifies to the fact that, in the considered temperature range, dynamic compaction does not lead to any noticeable changes in the distribution of the Fe, W and C elements over the bulk of the specimens. The conducted measurements of micro-hardness of the compacts have shown that it increases considerably with the pressing temperature. The produced compacts were tested for wear resistance in a dry friction regime, using the ‘rotating disk – stationary specimen’ configuration. Mass loss of the compacts as a function of testing time is presented. Wear resistance of compacts depends on pressing temperature and concentration of the WC powder in the matrix of reduced iron. It has been experimentally determined that maximal wear resistance is observed in the compacts with the mass fraction of WC equal to 10%, produced at a pressing temperature of 300 °C.

The pultrusion of large-diameter glass fiber reinforced epoxy rods at high pulling speed is often accompanied by the formation of cracks at the surface of a profile, leading to product rejection. In this study, we investigate the causes of crack formation based on numerical simulations of manufacturing process mechanics, including the temperature distribution, degree of polymerization, and residual stresses. Based on the built model, we solve the problem of temperature condition optimization for maximizing pulling speed. The results show that up to 27% increases in pulling speed are possible provided that the following conditions are met: thermal destruction of the material is avoided; a profile is cooled sufficiently quickly before cut-off; a high degree of polymerization is achieved in a final product; and there are no cracks in a profile.

The dynamic characterization of materials under intermediate and high strain rates is fundamental to understand the material behaviour in case of dynamic loadings. In this study dynamic tests of rocks in compression and splitting by the Kolsky method and its modification were analysed. The time dependence of the critical stress can predict by the incubation time of fracture criterion and these dependencies turned out to be in good agreement with experiments.

The problems of creation of an automated system for obtaining, processing and storing experimental information on the physical and mechanical properties of structural materials, building materials and various soil media used to provide information support for automated computing systems for analysis of strength and design of structures are discussed. The developed database is focused on studying the effects of the behavior of structural materials under highly parametric influences of force, temperature and other physical fields, as well as on equipping and experimental substantiation of mathematical models describing these effects. In the proposed variant, the database is implemented as a client-server application executed on the Microsoft.Net Framework using a powerful database management system MS SQL Server. The content of the created bank is made up of sections of primary information, material properties and material models. In order to automate the processing of data at all stages of information conversion, a special “Desktop” subsystem is included in the bank, which allows aggregating data obtained from several different experiments, correcting the selected data, processing and converting it. Processing and transformation of data in the subsystem “Desktop” can be carried out either in manual mode or on the basis of special algorithms using appropriate mathematical methods.

El genero Busbiscus fue descrito por Savini et al. 2009 en base a la especie B. voseri de Costa Rica. Se describen dos especies nuevas, Bubiscus carinatus y Bubiscus napo provenientes de Ecuador y se incluye una clave de identificacion para las tres especies descritas del genero.

The results of dynamic compression and splitting of dry and water-saturated limestone are presented. The tests have been performed using the Kolsky method and its modification for dynamic splitting. The strength and fracture time of this material at high strain rates have been obtained. It is shown that these characteristics are sensitive to the strain rate. A unified interpretation of these rate effects based on the incubation time approach is presented. Theoretical calculations show that the application of the incubation time concept allows to select the optimal ratio of duration and amplitude of action, which can reduce energy consumption during production and processing of rocks.

Criocerine leaf beetles found in Nepal feeding on Dioscorea bulbifera (L.), an exotic, invasive weed of Asian origin, were identified as Lilioceris cheni Gressitt and Kimoto based on a synopsis of the Oriental Lilioceris species and review of the Lilioceris impressa species group. All the continental, Oriental species included in the group are diagnosed and illustrated, and a key for their identification is provided. Species status of Lilioceris thibetana Pic, 1916 is resurrected. The following new synonyms are proposed: L. coomani (Pic, 1928) = L. egena (Weise, 1922), and L. subcostata (Pic, 1921a), L. laticornis (Gressit, 1942), L. inflaticornis Gressit and Kimoto, 1961, and L. maai Gressit and Kimoto, 1961 = L. impressa (Fabricius, 1787). Lectotypes of the following species are designated: L. coomani Pic, 1928; L. impressa (Fabricius, 1787); L. laosensis (Pic, 1916); L. malabarica (Jacoby, 1904); L. ruficornis (Pic, 1921b); L. subcostata (Pic, 1921a); L. thibetana (Pic, 1916); and L. unicolor (Hope, 1831).

This work presents the study of an influence of ultrafine-grained (UFG) structure on impact toughness and dynamic compression of commercially pure titanium Grade 4. The UFG structure was provided by means of equal-channel angular pressing according to the Conform scheme (ECAP-Conform, Ufa) with subsequent heat treatment. Impact toughness tests on samples with U-shaped notch were carried out using a drop weight impact machine. Dynamic compression test of cylindrical samples were carried out on a setup with the Split-Hopkinson pressure bar (SHPB-20) by the Kolsky method. It was found that the impact toughness of the UFG titanium is 15% greater than that of its coarse-grained (CG) counterpart. However, fracture process of the CG material requires 1.5 times more energy. The ECAP treatment significantly increased yield strength of the material. At the same time, an increase of compression strain rate by 6 orders resulted in an increase of yield strength of the CG material by 20%, while yield strength of the UFG titanium remained at the level of a quasi-static load. The UFG material showed a well-expressed strain hardening behaviour for all strain rates.

It is known that experiments with intensive dynamic influences and high-speed deformation of specimens under tension are important in the analysis of deformations and strength of structures and their elements. The most reasonable and widely used method for obtaining dynamic stressstrain curves, characteristics of ultimate strength and deformations is the modified Kolsky method. It should be noted a small number of publications on the analysis of the influence of fillets and the length of the working part of the specimen on the most important mechanical characteristics obtained by this method. This work is aimed at increasing knowledge in this area. By numerical and experimental analysis it was established that when the working part of the specimen has a length of 5 mm, then the uniformity and one-dimensionality of the stressed state are seriously violated. When choosing the length of the specimen in the Kolsky method, there are important limitations: the length of the specimen must be much smaller than the length of the loading pulse. Therefore, in this study, two specimen lengths of 10 and 15 mm were analyzed. In this paper, we give experimental and calculated diagrams and their comparison with each other. It was shown, that for the above-mentioned lengths, the homogeneity and one-dimensionality of the stressed state is substantially improved.

The combined experimental and theoretical approach was applied to the study of high-speed deformation and fracture of the 1810 stainless steel. The material tests were performed using a split Hopkinson pressure bar to determine dynamic stress-strain curves, strain rate histories, plastic properties and fracture in the strain rate range of 102 ÷ 104 s-1. A scheme has been realized for obtaining a direct tensile load in the SHPB, using a tubular striker and a gas gun of a simple design. The parameters of the Johnson-Cook material model were identified using the experimental results obtained. Using a series of verification experiments under various types of stress-strain state, the degree of reliability of the identified mathematical model of the behavior of the material studied was determined.

A description of experimental complexes, methodological and hardware means for determining the mechanical properties of materials under high-speed deformation and fracture is given in the report. Determination of mechanical properties in the strain rate range 5•102÷103 s-1 is the first direction of work in the laboratory of “Dynamic Materials Testing”. These tests are done using automated complexes based on the Kolsky method and its modifications for compression, tension and shearing. It is also possible to determine the fracture toughness, the characteristics of dynamic crack resistance, as well as to obtain stressstrain curves of low-density materials under uniaxial strain. Original gas guns with a caliber of 10, 20 and 57 mm are used for creation a dynamic load. The study of the behavior of materials at strain rates of 105 s-1 and higher is the second direction of work. In this case, the methods of a planewave shock experiment based on gas guns of 57 and 85 mm caliber are used. Manganine and dielectric pressure sensors, as well as laser interferometry are used for measuring the parameters of elastoplastic waves and for determining such important characteristics as impact compressibility, Hugoniot yield strength, spall strength.

The objective of this study was to investigate the compression behaviour of the UHPFRC and its matrix (UHPC) under high strain rate. Two experimental set-ups were used for compression testing: a traditional Split Hopkinson Pressure Bars and a compression version of the Modified Hopkinson Bar. The tests were conducted, in the range of 100–500 s −1 on cylindrical specimens with both diameter and height of 20 mm. Results show significant increases in peak strength and dissipated energy.

A study of the strength and deformation properties of freshwater ice under compression, tension and shear in a wide range of strain rates (10−4 − 3 ⋅ 103 s−1 ) and temperatures of − 5∘ C, − 20∘ C, − 40∘ C and − 60∘ C was performed. Static stress-strain curves of ice under compression were obtained on which the identified strength properties of ice as well as compressive modulus. To determine the mechanical properties of ice at high-speed loading the Kolsky method was used with various embodiments of split Hopkinson bar. The deformation curves were obtained at various loading conditions. Thereon breaking points were defined as well as their dependence on the strain rate and temperature. Also static and dynamic strength properties of ice at splitting and circular shear were defined. Increase in the dynamic strength properties upon the static ones for all loading conditions was marked.

The paper presents the dynamic characterization in tension and compression of three rocks, Carrara marble, Onsernone gneiss and Peccia Marble, at high strain-rates. Two versions of a Split Hopkinson Bar have been used. The version for direct tension tests is installed at the DynaMat Laboratory of the University of Applied Sciences of Southern Switzerland, while the traditional version in compression is installed at the Laboratory of Dynamic Investigation of Materials of Lobachevsky State University. Results of the tests show a significantly strain-rate sensitive behaviour, exhibiting dynamic strength increasing with strain-rate. The experimental research has been developed in the frame of the Swiss-Russian Joint Research Program.