The research was carried out in order to identify the relationship between the intensity of sticking of the workpiece material particles on the abrasive grains (AZ) of the grinding wheel with the ...physical and mechanical properties of the grains and ultrasonic vibrations (UZK) used in the processing process. Numerical simulation of local temperatures during micro-cutting (scratching) of samples made of 3X3M3F steel with abrasive grains made of various materials, including with the imposition of a narrow band. The deformation of the bulk and the stresses resulting from this deformation acting on the connection of the bulk with grains from materials with different coefficients of linear expansion are calculated. It was found that with increasing difference in the coefficients of linear expansion of the materials of the billet and AZ, the stresses that contribute to the separation of the adhesive from the surface of the AZ increase. In the course of experimental studies, samples were micro-cut with single abrasive grains. We controlled the salting coefficient equal to the ratio of the area of nalip to the area of the blunting site at the gas station and the wear of grain. It was found that AZ from Elbor wear out and become salted to a lesser extent when grinding with the imposition of a narrow-gauge blank.
We present the Migdal In Galactic Dark mAtter expLoration (MIGDAL) experiment aiming at the unambiguous observation and study of the so-called Migdal effect induced by fast-neutron scattering. It is ...hoped that this elusive atomic process can be exploited to enhance the reach of direct dark matter search experiments to lower masses, but it is still lacking experimental confirmation. Our goal is to detect the predicted atomic electron emission which is thought to accompany nuclear scattering with low, but calculable, probability, by deploying an Optical Time Projection Chamber filled with a low-pressure gas based on CF4. Initially, pure CF4 will be used, and then in mixtures containing other elements employed by leading dark matter search technologies — including noble species, plus Si and Ge. High resolution track images generated by a Gas Electron Multiplier stack, together with timing information from scintillation and ionisation readout, will be used for 3D reconstruction of the characteristic event topology expected for this process — an arrangement of two tracks sharing a common vertex, with one belonging to a Migdal electron and the other to a nuclear recoil. Different energy-loss rate distributions along both tracks will be used as a powerful discrimination tool against background events. In this article we present the design of the experiment, informed by extensive particle and track simulations and detailed estimations of signal and background rates. In pure CF4 we expect to observe 8.9 (29.3) Migdal events per calendar day of exposure to an intense D–D (D–T) neutron generator beam at the NILE facility located at the Rutherford Appleton Laboratory (UK). With our nominal assumptions, 5σ median discovery significance can be achieved in under one day with either generator.
When processing billets of plastic and adhesive-active materials, the loss of the cutting ability of the grinding wheel is mainly due to the adhesion of the workpiece material particles to the ...abrasive grains (AG). To develop recommendations aimed at reducing the intensity of adhesion, it is necessary to identify the relationship of the intensity of this process with the physical and mechanical properties of abrasive grains. The dependence for the calculation of the voltage at the contact area of the clip with the AG after the AG out of contact with the workpiece is obtained. Numerical simulation of local temperature when microreserve (scratching) samples of steel 3KH3M3F abrasive grains of various materials. According to the obtained dependences, the deformation of the excrescence and the stresses resulting from this deformation were calculated, and the ones acting on the connection of the 3KH3M3F steel excrescence with grains from materials having different coefficients of linear expansion. It is established that with the increase in the difference of the coefficients of linear expansion of the billet materials and AG, the stresses that contribute to the separation of the excrescence from the surface of AG increase, which allows to predict a lower intensity of sticking of the billet material to AG from such materials. It is established that with the increase in the difference of the coefficients of linear expansion of the billet materials and AG, the stresses that contribute to the separation of the excrescence from the surface of AG increase, which allows to predict a lower intensity of sticking of the billet material to AG from such materials. Experimental studies, during which micro-cutting of samples by single abrasive grains was carried out, showed that AG from elbor wear out and are salted to a lesser extent. Elbor has the maximum value of the coefficient of thermal conductivity among the tested materials and to a lesser extent wears out, so the local temperatures when cutting grains from Elbor are minimal. In addition, the difference between the linear expansion coefficients of the material excrescence and elbor has a maximum value. Therefore, at the site of contact AG from elbor with the adhesive there are stresses that contribute to the separation of the excrescence from this surface, which is the reason for the small value of the coefficient of salting AG from elbor. As a result, AG was ranked from various materials according to the criteria characterizing their wear and salting. Confirmed identified analytically the relationship between the intensity of brining of grain with a coefficient of linear expansion and thermal characteristics of the materials AG.
This paper reports results from a study of two new genetic types of diamond discovered in Kamchatka. These diamonds were formed under extra-mantle conditions, as can be inferred from the fact that ...there is no indication of post-crystallization annealing with the formation of aggregated nitrogen defects in them. The first of these types is defined by us as volcanic-atmoelectrogenic. This is formed directly in a volcanic ash-gas cloud due to deep-seated methane released by atmospheric electric discharges. The second genetic type of diamonds is formed at depth within a magmatic-pneumatolytic-hydrothermal ore deposit, and can be defined as the explosive-tuffisite type. The industrial potential of these types enables us to assert the discovery of a new diamondiferous province, i.e., the Kamchatka Province.
Comprehensive mineralogical and geochemical studies were conducted in application to a representative sample of tephra from Cumbre Vieja Volcano (the 2020–2021 eruption). The tephra has a ...gravel-psammitic grain-size distribution, and is characterized by an anomalously high degree of particle vesicularity. The whole-rock composition of this tephra is consistent with the transition from alkaline picrobasalts to alkaline basalts, while being essentially different from the tephra ashes discharged by marginal continental volcanoes. The tephra was studied to detect 45 trace elements with whole-rock compositions occasionally reaching 2333 g/t, above the respective figure for the tephra of island arc volcanoes. Judging by the relationship among geochemical criteria, the Cumbre Vieja tephra is consistent with the average parameter values for intraplate volcanoes in oceans. One geochemical feature of this tephra consists in a strong enrichment in lanthanoids, as well as in noble and platinoid metals. The lithogenic gas phase which was obtained by heating the tephra sample was found to contain H
2
, CO, CO
2
, H
2
O, CH
4
, C
2
H
4
, C
2
H
6
, C
3
H
6
, and С
3
H
8
. The proportions among inorganic components in the gas phase as a whole correspond to the boundary region between crustal and mantle–crustal derivates, but water is in relatively low amounts. Microlites were found to contain Fo
73–84
olivine; this contains dominantly diopside clinopyroxene, andesine–bytownite plagioclase, chrome-spinellids, phase-homogeneous solid solutions of ilmenite in magnetite, phases of Ni-Cu bearing native iron, quartz, and sodic hydroxyl-chlorides. In addition, the Cumbre Vieja tephra was found to contain dispersed scattered carbonaceous material with δ
13
С
PDB
= –30…–24‰ as the isotopic composition of carbon, which is consistent with the isotopic composition of carbon in abiogenic carbonaceous materials of volcanogenic origin. The entire set of results of these mineralogical and geochemical studies characterizes Cumbre Vieja Volcano as a typical intraplate-oceanic plume volcano.
This paper reports a study of xenoliths sampled in marine sedimentary carbonate rocks in fumaroles of the crater zone in the Second Cone of the GTFE (Great Tolbachik Fissure Eruption) North Vent. ...These rocks have been subjected to the action of the GTFE exhalative pneumatolytic fluids, resulting in carbonates giving rise to numerous compounds with mixed carbonate-sulfate-chloride anion radicals, which are treated as two interclass and nine intertype crystal-chemical hybrids. The patterns identified in the altered micro xenoliths, which consist in inhomogeneities of mineral paragenesis, are treated here as resulting from successive epigenetic transformation of the original carbonates to, at first, sulfate carbonates, then to carbonate sulfates, and subsequently to chloride-carbonate-sulfates and chlorides. Judging by an absence of signs of phase heterogeneity, the crystal-chemical hybrids studied here are homogeneous solid-phase mixtures of carbonates, sulfates, and chlorides in varying proportions. The carbonates in the micro xenoliths have isotopic compositions of carbon (δ
13
С
PDB
= –5.34 ± 0.62‰) and oxygen (δ
18
O
SMOW
= 24.09 ± 1.05‰) that are consistent with carbonates to be found in marine sedimentary limestones that were redeposited during volcanogenic transportation. The sulfate sulfur has the isotopic composition (δ
34
S = 1.5–2‰) varying within the range of variation established for sulfates of volcanogenic origin. In the carbonaceous particles associated with micro xenoliths, the isotopic composition of carbon (δ
13
C
PDB
= –27.37 ± 2.97‰) and of nitrogen (δ
15
N
Air
= 6.74 ± 2.48‰) tend toward the mode in the distribution of these values in the ejecta of present-day continental volcanism. The crystal-chemical hybrids identified here furnish a typomorphic criterion for the exhalation fumarole facies and are treated as a previously unknown phenomenon of present-day volcanism.
Our multidisciplinary petrologic, mineralogical, and geochemical studies of volcanic material sampled from three chronologically discrete, but successive, ash discharges during the period from ...November 30, 2020 to January 18, 2021 were concerned with grain-size inhomogeneity, chemical and mineral phase composition, the concentrations of trace elements, the isotopy of Sr, Nd, and carbon, and with the composition of inorganic and organic lithogenic gases. For the first time volcanic ashes were found to contain eskolaite, mantle spinellids of the magnetite–magnesioferrite composition, hybrid compounds of Ca–Zn-carbonates with titanium formate, and polycomponent metallo-organic compounds. The net result was to obtain proof of a mantle–asthenosphere origin of the ash material and to identify a previously unknown pattern consisting in a conjugate temporal orderliness in the variations of many properties in the material sampled from the explosions. This seems to reflect the evolution of the melt in the mantle magma chamber.
Multidisciplinary petrologic, mineralogical, and geochemical studies have been carried out for the first time concerning near-crater tephra from the world-largest intraplate stratovolcano (Erebus). ...The volcano is characterized by a unique basanite–phonolite effusive lineage. We studied the grain-size and chemical compositions of the tephra and the concentration of trace elements in it, the mineral phase composition, lithogenic gases encapsulated in the tephra, an atomically dispersed carbonaceous substance, and the isotope composition of carbon in it. We came to the conclusion that the tephra studied here can be treated as an explosive analogue of anorthoclase lava phonolites that terminate the continuous series of magmatic differentiates known as the Erebus lineage.
The LUX-ZEPLIN experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This ...Letter reports results from LUX-ZEPLIN's first search for weakly interacting massive particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross sections for WIMP masses above 9 GeV/c^{2}. The most stringent limit is set for spin-independent scattering at 36 GeV/c^{2}, rejecting cross sections above 9.2×10^{-48} cm at the 90% confidence level.
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