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Rock mass is one of the most important load-bearing media in geotechnical engineering. It has been continually vulnerable to geological tectonic movements, natural calamities, and human excavation activities. Its inherent weak surfaces such as primary pores, joints, and fissures have resulted in varying damage degrees. In mining operations, the damaged rock mass has a variety of negative impacts on the stability of its overlying structures and is frequently disturbed by the load. To study the damage law of rock mass under cyclic loading, in this paper, an acoustic emission (AE) device was employed to monitor the rock under the action of two types of cyclic loads: the variable upper and lower pre-loads, and the fixed upper and lower pre-loads. The damage of the loaded rock was split into three stages in this research, based on the features of the AE signals of the rock under uniaxial load, and the damage evolution of the loaded rock was analyzed in distinct stages. The AE signals of the rock under cyclic loading were mainly emitted in the first loading stage. When the stress did not exceed the maximum stress value in the stress history of the loaded rock, few new AE event was generated in the loaded rock. After the low-frequency cyclic static load, the AE signals varied with the load-bearing stress of the rock during the whole process from initial loading to failure, which was consistent with the characteristics of the AE signals of the loaded rock. The research results can be adapted to rock mass in open-pit mines stability analysis and risk prediction while providing some references for the early warning and danger relief of rock masses in engineering. [ABSTRACT FROM AUTHOR]

The object of this study is the process of choosing the appropriate types of reservation of reconnaissance fire systems under the conditions of performing a combat mission. The problem that was solved is the unsuitability of existing scientific and methodological apparatus to substantiate the appropriate type of reservation for reconnaissance and fire systems under specific conditions for performing a combat mission. Possible types of reservation of reconnaissance fire systems have been analyzed. Based on the results of the analysis, appropriate types of reservation were established, in particular, active, unactive, majoritarian sliding, distributed, for subsystems, as well as general reservation. A feature of this analysis is that it was carried out taking into account the peculiarities of the functioning of reconnaissance and fire systems. This makes it possible to eliminate existing problem associated with the complexity of the use of reconnaissance and fire systems in a combat event. The scope of practical use of the results of the proposed analysis is the management processes associated with the creation, layout, and use of reconnaissance and fire systems in military administration bodies. A methodology for determining the appropriate type of reservation of reconnaissance fire systems has been devised. A feature of the proposed procedure is the choice of such a type of reservation that makes it possible to save the resource of elements, provided that the task is completed. The proposed methodology ensures an increase in the stability of the functioning of reconnaissance and fire systems by an average of 20 % for the conditions adopted within the limits of the example. The proposed methodology closes the problem part, which concerns the procedure and rules for choosing the appropriate type of reservation. The scope and conditions for the practical use of the proposed methodology are management processes related to the planning and determination of the projected effectiveness of hostilities by military authorities. [ABSTRACT FROM AUTHOR]

The structural-morphological parameters of hybrid nanosystems, which are promising as photosensitizers (PS) for photodynamic therapy (PDT), are comparatively studied by atomic force microscopy (AFM), ultraviolet (UV) spectroscopy, photoluminescence (PL) and dynamic light scattering. The nanosystems are nanoparticles of zinc selenide (ZnSe) prepared using the hydrothermal synthesis method, stabilized by various polymer matrices: bovine serum albumin (BSA), polymethacrylic acid (PMAA) and, the second generation PS, photoditazin (PD). Comparison of the nanostructure size characteristics in ZnSe nanoparticles/polymer + PD systems (in a solution by means of the molecular optics and PL, and on a surface of a silicon wafer in air by means of AFM) at the same concentration of reagents in the reaction mixture shows that nanocluster sizes in the solution are two times larger than those in a thin film prepared on the substrate surface. When the order of the BSA and PD introduction into the system is changed, the nanosystem morphology changes strongly (nanocluster sizes and shape), which is due to the competition of the polymer stabilizers during complex formation with ZnSe nanoparticles. Analysis of the photoluminescence excitation and emission spectra of PD and the triple-system aqueous solutions shows that the ZnSe/BSA nanostructures do not suppress PD photoluminescence in the triple system ZnSe/BSA + PD, i.e., do not affect their ability to generate active forms of oxygen and make them promising as the basis for the creation of photosensitive compounds for PDT in oncology. [ABSTRACT FROM AUTHOR]

In order to study the shear behavior of the interface between sand and structure, a series of shear tests were carried out using an HJ-1 ring shear apparatus (Nanjing, China). First, through the monotonic shear tests, the loose sand and dense sand were sheared at the steel interface with different roughnesses. The results showed that when the interface was relatively smooth, the shear stress–shear displacement curves of loose sand and dense sand both exhibit strain hardening characteristics. When the interface was rough, the dense sand showed strain softening. The initial shear stiffness of the sand–steel interface increased with the increase in normal stress, interface roughness, or sand relative density. Then, considering the influence of initial shear stress, through the cyclic shear test, this work analyzed the shape of the loading and unloading curves and the development law of cumulative normal deformation, and discussed the change of loading and unloading shear stiffness under different stress level amplitudes and the residual deformation generated during the cycle. The research results showed that loose sand and dense sand generally shrunk in volume during the cycle. The initial loading process was similar to the case of static loading. In the later dynamic loading process, the shear shrinkage per cycle was relatively small and continued to develop. Additionally, it was found that the unloading stiffness of the sand–steel interface is always greater than the initial loading stiffness. As the number of cycles increases, the loading stiffness increases, and it may eventually approach the unloading stiffness. [ABSTRACT FROM AUTHOR]

The reaction of 5-arylisoxazolyl- and 4,5-dichloroisothiazolylallylamines with pyromucic acid chlorides (2-furoyl and 5-methyl-2-furoyl chlorides) was studied. The reaction proceeds via the initial acylation of the allylamine nitrogen atom and the subsequent spontaneous intramolecular Diels–Alder reaction involving the furan ring of intermediate N-furoylamides with the formation of a single diastereomer of 3a,6-epoxyisoindol-3-ones. [ABSTRACT FROM AUTHOR]

Creep constitutive equations have been derived for the materials that exhibit the properties of orthotropy (transversal isotropy) and transient creep under cyclic loading. A low-frequency case is considered. The paper provides results of experimental studies of the short-term creep of St3 steel under static and stepwise cyclic loading at room temperature. The results of calculations by the proposed constitutive equations are compared with the experimental data. A good agreement has been found for the number of cycles above 4 or 5, which demonstrates the applicability of the proposed constitutive equation to the low-frequency creep calculations for sheet materials. [ABSTRACT FROM AUTHOR]

An efficient approach to bridged pentacyclic nitrogen heterocycles via the tandem acylation/intramolecular Diels-Alder furan (IMDAF) reaction of 2-furylquinazolinones is described. Reactions of a,ß-unsaturated acid anhydrides with 2-furyl-2,3-dihydroquinazolin-4- ones give 6b,9-epoxyisoindolo[2,1-a]quinazolines in average yields. In this case, the exo-IMDAF reactions proceed with excellent diastereoselectivity giving five stereogenic centers and three new rings in one synthetic step. Isomeric 2,4a-epoxyisoindolo[1,2-b]quinazolines are obtained by one-pot, three-component condensation reactions of allylamine, isatoic anhydride and furaldehydes involving the same IMDAF reaction as the key step. Some useful transformations including halogenation, hydrogenation, Prilezhaev epoxidation, and esterification of the synthesized epoxyisoindoloquinazolines are also demonstrated. [ABSTRACT FROM AUTHOR]

The isomeric title compounds, C12H13NO4 (Ia) and C12H13NO4 (IIa), the products of an usual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9boctahydro- 7,9a-epoxypyrrolo[2,1-a]isoindole-6-carboxylic acid, represent the two different diastereomers and have very similar molecular geometries. The molecules of both compounds comprise a fused tetracyclic system containing four five-membered rings (pyrrolidine, pyrrolidinone, dihydrofuran and tetrahydrofuran), all of which adopt the usual envelope conformations. The dihedral angle between the basal planes of the pyrrolidine and pyrrolidinone rings are 14.3 (2) and 16.50 (11)°, respectively, for (Ia) and (IIa). The nitrogen atom has a slightly pyramidalized geometry [bond-angle sum = 355.9 and 355.3°, for (Ia) and (IIa)], respectively. In the crystal of (Ia), molecules form zigzag-like hydrogen-bonded chains along [010] through strong O--H...O hydrogen bonds and are further linked by weak C--H...O hydrogen bonds into complex twotier layers parallel to (100). Unlike (Ia), the crystal of (IIa) contains centrosymmetric cyclic hydrogen-bonded dimers [graph set R2²(14)], formed through strong O--H...O hydrogen bonds and are further linked by weak C-- H...O hydrogen bonds into ribbons extending across [101]. [ABSTRACT FROM AUTHOR]

A metal-free, thermal, intramolecular Diels-Alder (IMDA) reaction of furan in aqueous media without the use of microwave irradiation was investigated. Protection of the amine functionality and the cycloaddition reaction were performed as a one-pot, two-component process. Various nitrogen-protecting groups and their electronic and steric effects on the cycloaddition reaction were studied. The protection- intramolecular Diels-Alder reaction sequence proceeds under environmentally benign aqueous conditions, which are tolerated by substrates with a broad range of nitrogen-protecting groups such as benzyloxycarbonyl (Cbz), trityl, tert-butoxycarbonyl (Boc), trifluoroacetyl, tosyl, mesyl, and p-nosyl [(4-nitrophenyl)sulfonyl]. This study allowed the development of a stereoselective, tandem allylamine isomerization- Diels-Alder cycloaddition sequence leading to the rapid assembly of complex nitrogen-containing heterocycles in a simple onepot process. [ABSTRACT FROM AUTHOR]

We describe herein preliminary studies on the intramolecular Diels-Alder furan-mediated synthesis of 8-aryl-3,4-dihydroisoquinolin- 1(2H)-ones that constitutes a new, formal synthesis of indeno[1,2,3-ij]isoquinolines. [ABSTRACT FROM AUTHOR]

The cross sections for radiative capture and fission for U in the neutron energy ranges 1-2000 eV and 1-1000 eV, respectively, have been measured. The measurements were performed on a flight baseline 5.2 m of the FAKEL linear electron accelerator at the National Research Center Kurchatov Institute using a method based on measuring the distribution of the number of particles emitted by an excited nucleus with simultaneous measurement of the energy of each particle. The spectrum of the neutrons incident on a sample was measured by detecting the reaction B(n, α)Li. The cross sections were normalized with respect to the resonance in U at 5.45 eV. The data obtained are compared with the results of other experiments and evaluated data. [ABSTRACT FROM AUTHOR]

Mathematical modeling of the neutron-resonance method analyzing the elemental and isotopic of matter is performed. The method is based on investigation of γ cascades, emitted by nuclei as a result of the radiative capture of neutrons. Gamma cascades of the determined element (effect) and elements of the matrix (background) are modeled and these cascades are detected with a γ-ray multisectional 4π detector. The response functions of the detector are presented for the case of an analysis of the gold content in a natural medium. It is shown that the introduction, performing together with neutron spectrometry, the spectrometry of γ cascades makes it possible to increase the effect/background ratio by a factor of 100. It is noted that this ratio can be further increased by improving the method used to detect γ cascades and analyzing the results of the measurements. [ABSTRACT FROM AUTHOR]

A review of the literature devoted to the problem of efficiency of the use of aluminum alloys in automotive structures is presented. Requirements are formulated on the structure and properties of alloys for cold rolling of car parts. The results of a study of sheets from AV alloy with a fine-grained recrystallized structure and adaptability to manufacture, which makes the sheets suitable for automotive panels, and mechanical properties at the level of steel sheets after aging in the process of drying of the lacquer coating, are presented. [ABSTRACT FROM AUTHOR]

We have studied the optical properties of silicon-based sandwich structures with diamond-like films deposited by electrophoresis from aqueous suspensions of modified detonation nanodiamonds. It is shown that these films can be used as antireflection and protective coatings for silicon-based solar cells. [ABSTRACT FROM AUTHOR]

The joint evaluated fission and fusion nuclear data library 3.3 is described. New evaluations for neutron-induced interactions with the major actinides 235 U , 238 U and 239 Pu , on 241 Am and 23 Na , 59 Ni , Cr, Cu, Zr, Cd, Hf, W, Au, Pb and Bi are presented. It includes new fission yields, prompt fission neutron spectra and average number of neutrons per fission. In addition, new data for radioactive decay, thermal neutron scattering, gamma-ray emission, neutron activation, delayed neutrons and displacement damage are presented. JEFF-3.3 was complemented by files from the TENDL project. The libraries for photon, proton, deuteron, triton, helion and alpha-particle induced reactions are from TENDL-2017. The demands for uncertainty quantification in modeling led to many new covariance data for the evaluations. A comparison between results from model calculations using the JEFF-3.3 library and those from benchmark experiments for criticality, delayed neutron yields, shielding and decay heat, reveals that JEFF-3.3 performes very well for a wide range of nuclear technology applications, in particular nuclear energy. [ABSTRACT FROM AUTHOR]

The possibility of obtaining thin (1500-3000 Å) layers of ultradisperse diamond from an aqueous suspension is reported and the first results of studies of its optical properties are presented. It is deduced from an analysis of the optical absorption spectra of layers of ultradisperse diamond that the band gap of ultradisperse diamond is 2.06 eV. The luminescence spectra of ultradisperse diamond reveal a characteristic line with a peak at 363.7 nm. [ABSTRACT FROM AUTHOR]

The full text of the nine papers selected by the Technical Paper Awards Committee (M-141) to receive Superior Paper Award honors can be accessed on the ASAE Technical Library at [...]

Superior Paper Award Winners: N. Scheerlinck, P Verboven, K. A. Fikiin, J. De Baerdemaeker, B. M. Nicolai, 'Finite Element Computation of Unsteady Phase Change Heat Transfer During Freezing or Thawing [...]