Mass Components Research Articles

Observation of Gravitational Waves from the Coalescence of a 2.5–4.5 M ⊙ Compact Object and a Neutron Star

We report the observation of a coalescing compact binary with component masses 2.5–4.5 M ⊙ and 1.2–2.0 M ⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO–Virgo–KAGRA detector network on 2023 May 29 by the LIGO Livingston observatory. The primary component of the source has a mass less than 5 M ⊙ at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We provisionally estimate a merger rate density of 55−47+127Gpc−3yr−1 for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star–black hole merger, GW230529_181500-like sources may make up the majority of neutron star–black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star–black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap.

Improving the efficiency of combined displacement of ultra-viscous oil from the reservoir by carbon dioxide and coolant

Currently, in the world practice, special attention is paid to the processing of carbon dioxide in the aspect of obtaining it at the field itself, which reduces the cost of the technology of gas capture and injection into the well, because it is important for Russia due to the remoteness of the main part of oil fi elds. Realization of the gas method of oil feedstock extraction increases its efficiency several times taking into account the elimination of the ecological problem of utilization of carbon dioxide formed on a large scale industrially, with the growth of qualitative parameters of extracted commercial oil feedstock, taking into account the relatively small cost of carbon dioxide, the ability to recycle, as well as the use at any stage of fi eld operation. It is obvious that the increase of efficiency of technologies of carbon dioxide influence on the formation mass in complex with a thermal agent for super viscous oil feedstock requires an integrated approach in terms of methodical and empirical studies of regime parameters, applied technological processes and materials. On the basis of systematization of known theoretical data, results of empirical studies and their industrial approbation the authors recommend an algorithm for research of the problem. The article presents empirical substantiation of the ability to increase the effi ciency of exploitation of carbonate deposit of super viscous oil at great depth through the impact of thermal agent and carbon dioxide through the inclusion of the matrix component of the reservoir mass in more mobile development. It is shown that it is possible to incorporate the oil-saturated matrix by means of increasing the mobility of carbon dioxide when the temperature in the reservoir rises, the high degree of solubility of extra-viscous oil there and the additive drop in its dynamic viscosity. The data of empirical studies lead to the conclusion that the level of heating of the deposit and the volume of carbon dioxide supplied serve as optimizable factors, with a rational combination of which can increase the effectiveness of their influence.

Hydrodynamic force characterization and experiments of underwater piezoelectric flexible structure

The unsteady hydrodynamics of underwater flexible structures internally actuated by smart materials are drawing growing attention. In this study, the dynamic measurement and characterization of hydrodynamic forces acting on flexible structures actuated by macro fiber composites (MFC) are performed. A measurement system composed of a cantilevered transducer and a laser sensor is proposed for dynamically acquiring the induced hydrodynamic force. The parameter indexes of the measurement system are carefully determined to achieve the requirements of high resolution, high sensitivity and good anti-interference of the designed measurement system. Calibration experiments demonstrate the good measuring performances. Then, the relationship between the hydrodynamic force and the actuation frequency is explored using the data obtained from the designed measurement system. Moreover, by decomposing the measured hydrodynamic force, it is found that the added mass component shares similar behaviors with the hydrodynamic force, whereas the hydrodynamic damping component initially increases and then decreases across the explored ranges. Finally, manageable formulas for these components in the forms of hydrodynamic function are developed, and explicit expressions for the Morison’s formula are obtained. These findings are meaningful for the realization of flexible structures with the actuation of smart materials in marine applications.

Analysis of the subsolar-mass black hole candidate SSM200308 from the second part of the third observing run of Advanced LIGO-Virgo

We present a follow-up study of a subsolar black hole candidate identified in the second part of the third observing run of the LIGO-Virgo-KAGRA collaboration. The candidate was identified by the GstLAL search pipeline in the Hanford and Livingston LIGO detectors with a network signal-to-noise ratio of 8.90 and a false-alarm-rate of 1 per 5 years. It is the most significant of the three candidates found below the O3b subsolar mass false-alarm rate threshold of 2 per year, but still not significant enough above the background to claim a clear gravitational wave origin. A Bayesian parameter estimation of this candidate, denoted SSM200308, reveals that if the signal originates from a compact binary coalescence, the component masses are m1=0.62−0.20+0.46M⊙ and m2=0.27−0.10+0.12M⊙ (90% credible intervals) with at least one component being firmly subsolar, below the minimum mass of a neutron star. This discards the hypothesis that the signal comes from a standard binary neutron star. The signal coherence test between the two LIGO detectors is consistent with, but does not necessarily imply, a compact object coalescence origin.

Investigation of a W UMa-type contact binary GZ And in a physical triple system

GZ And is a variable star within the visually observed multiple-star system ADS 1693. Recent observations have yielded new light curves for GZ And, obtained using the Xinglong 85-cm telescope and the Transiting Exoplanet Survey Satellite (TESS) satellite. These light curves, along with radial velocity curves, were analyzed simultaneously to ascertain the fundamental physical parameters of GZ And’s components. The findings indicate that the primary star has a mass of M1 = 0.57 (4)M⊙, radius of R1 = 0.75 (2)R⊙, and luminosity of L1 = 0.42 (2)L⊙. The secondary star is characterized by a mass of M2 = 1.19 (9)M⊙, radius of R2 = 1.04 (3)R⊙, and luminosity of L2 = 0.63 (3)L⊙. Their orbital separation is determined to be a = 2.30 (6)R⊙. An analysis of the accumulated times of light minima reveals that GZ And is undergoing orbital period variations at a rate of dP/dt = −7.58 (7) × 10−8day ⋅ year−1, likely due to mass transfer from the more massive component to its lighter counterpart at a rate of dM2/dt = −9.06 (8) × 10−8M⊙⋅ year−1. Additionally, distance measurements for the component stars in ADS 1693, derived from Gaia DR3 astrometric data, suggest that ADS 1693A (GZ And) and ADS 1693B are gravitationally bound and likely originated from the same molecular cloud, sharing similar ages. This evidence supports the classification of GZ And as a W UMa-type contact binary within a physically associated triple system.

Model Parameter Calibration for Vibration Fatigue Analysis by Means of Bayesian Updating and Artificial Neural Network Based Surrogate Models

Abstract In this paper, a methodology for model parameter calibration for vibration fatigue analysis is proposed. It combines Bayesian updating of uncertain model parameters and artificial neural networks (ANNs). The calibrated parameters are used to increase the accuracy of fatigue lifetime calculations for components submitted to vibrational loads. The Bayesian updating uses eigenfrequencies, mode shapes, total mass, and the frequency response functions (FRFs). These quantities are predicted by ANN-based surrogate models to accelerate the Bayesian updating process. A novel strategy for the prediction of the magnitude and phase of FRFs with ANNs is proposed. The frequency is used as an additional input variable, and a schematic selection of significant points of the FRF curves is presented. A high prediction accuracy of the surrogate models could be achieved. The procedure includes the analysis of the relevant frequency range and a sensitivity analysis based on the Morris method to identify appropriate modes and the most-influential parameters. The proposed framework is applied to a current vehicle component subjected to vibrational loads. An experimental modal analysis is used for the calibration and consideration of real parameter uncertainty. First, the accuracy of the surrogate models and Bayesian updating is verified by a nominal reference simulation and then validated with experimental data. The measurable control parameter thickness and component mass are used to examine the calibration accuracy. Finally, a decrease in the dispersion of the vibration fatigue distribution is obtained with the calibrated parameters.

Optimized design of truck cab lightweighting based on sensitivity hierarchical comparative analysis method

The relative sensitivity analysis method is an important method in the field of vehicle lightweighting. Combined with optimization algorithms, experiment of design (DOE), etc., it can efficiently explore the impact of unit mass of components on performance and search for components with lightweight space. However, this method does not take into account the size level of each component and the order of magnitude differences in sensitivity under different operating conditions.Therefore, this paper proposed a sensitivity hierarchical comparative analysis method, on the basis of which the thicknesses of 10 groups of components were screened out as design variables by considering the lightweighting effect, cab performance and passive safety.Through the optimal Latin hypercube method, 70 groups of sample points were extracted to carry out the experimental design, the Kriging surrogate model was established and the NSGA-II genetic algorithm was used to obtain the Pareto optimal solution set, and ultimately a weight reduction of 13.13 kg was realized under the premise that all the performance of the cab has been improved.

Isochrone fitting of the open cluster M67 in the era of Gaia and improved model physics

ABSTRACT The Gaia mission has provided highly accurate observations that have significantly reduced the scatter in the colour–magnitude diagrams of open clusters. As a result of the improved isochrone sequence of the open cluster M67, we have created new stellar models that avoid commonly used simplifications in 1D stellar modelling, such as mass-independent core overshooting and a constant mixing length parameter. This has enabled us to deliver a precise isochrone specifically designed for M67, available for download. We follow a commonly used qualitative approach to adjust the input physics to match the well-defined colour–magnitude sequence, and we test the model-predicted masses against a known eclipsing binary system at the main sequence turnoff of the cluster. Despite using improvements in photometry and stellar physics we cannot match the masses of both binary components with the same theoretical isochrone. A $\chi ^{2}$-based isochrone fitting approach using our preferred input physics results in a cluster age of $3.95^{+ 0.16}_{- 0.15}$ Gyr.

The DBL Survey I: discovery of 34 double-lined double white dwarf binaries

ABSTRACT We present the first discoveries of the double-lined double white dwarf (DBL) survey that targets overluminous sources with respect to the canonical white dwarf cooling sequence according to a set of well-defined criteria. The primary goal of the DBL survey is to identify compact double white dwarf binary star systems from a unique spectral detection of both stars, which then enables a precise quantification of the atmospheric parameters and radial velocity variability of a system. Our search of 117 candidates that were randomly selected from a magnitude-limited sample of 399 yielded a 29 per cent detection efficiency with 34 systems exhibiting a double-lined signature. A further 38 systems show strong evidence of being single-lined or potentially DBL binaries and seven single-lined sources from the full observed sample are radial velocity variable. The 45 remaining candidates appear as a single WD with no companion or a non-DA white dwarf, bringing the efficiency of detecting binaries to 62 per cent. Atmospheric fitting of all double-lined systems reveals a large fraction that have two similar mass components that combine to a total mass of 1.0–1.3 $\mathrm{M}_\odot$ – a class of double white dwarf binaries that may undergo a sub-Chandrasekhar mass type Ia detonation or merge to form a massive O/Ne WD, although orbital periods are required to infer on which time-scales. One double-lined system located 49 pc away, WDJ181058.67+311940.94, is super-Chandrasekhar mass, making it the second such double white dwarf binary to be discovered.

Unraveling female mate choice in Schizocosa mccooki: The interplay of male mass and vibratory courtship

AbstractSexual selection is an important evolutionary force and despite extensive research, understanding mate choice on naturally occurring trait variation remains an intriguing area of study. The correlation between mass, a trait associated with courter viability and common target for mate choice, and signals is particularly noteworthy. This study focuses on Schizocosa mccooki, the largest member of a wolf spider genus renowned for its diverse complex male courtship. Our objective was to understand the relationship of male mass and other courtship signals on female choice within this species. We conducted lab experiments involving random pairings of field caught males and females, recording vibratory courtship and its outcomes. Our findings revealed that S. mccooki courtship consisted of vibratory signals with two major components, thumps and raps. Male mass, overall courtship vigor, and thump duration were found to predict mating success. Interestingly, we found no correlation between temporal traits and mass suggesting independent information and an absence of trade‐offs between mass, courtship vigor, and signal component rates/durations. Instead, we found that heavier males tend to produce thumps with lower frequencies. The finding that male mass predicts mating success contrasts with patterns observed in other species in this well‐studied genus. By uncovering the mate choice patterns of S. mccooki, this study underscores the importance of comparative studies to understand the ways in which sexual selection drives diversification, even among closely related taxa.

Constraining Possible γ-Ray Burst Emission from GW230529 Using Swift-BAT and Fermi-GBM

GW230529 is the first compact binary coalescence detected by the LIGO–Virgo–KAGRA collaboration with at least one component mass confidently in the lower mass gap, corresponding to the range 3–5 M ⊙. If interpreted as a neutron star–black hole merger, this event has the most symmetric mass ratio detected so far and therefore has a relatively high probability of producing electromagnetic (EM) emission. However, no EM counterpart has been reported. At the merger time t 0, Swift-BAT and Fermi-GBM together covered 100% of the sky. Performing a targeted search in a time window [t 0 − 20 s, t 0 + 20 s], we report no detection by the Swift-BAT and Fermi-GBM instruments. Combining the position-dependent γ-ray flux upper limits and the gravitational-wave posterior distribution of luminosity distance, sky localization, and inclination angle of the binary, we derive constraints on the characteristic luminosity and structure of the jet possibly launched during the merger. Assuming a top-hat jet structure, we exclude at 90% credibility the presence of a jet that has at the same time an on-axis isotropic luminosity ≳1048 erg s−1 in the bolometric band 1 keV–10 MeV and a jet opening angle ≳15°. Similar constraints are derived by testing other assumptions about the jet structure profile. Excluding GRB 170817A, the luminosity upper limits derived here are below the luminosity of any GRB observed so far.

Об одной новой схеме применения метода конечных элементов в горных науках

At the moment a large number of research papers are being published in the field of mining sciences, utilizing FEM (finite element method) in one way or another. The vast majority of these papers are devoted to solving various engineering problems in mining using different software products such as ABAQUS, PLAXIS, etc. It has been determined that almost all existing works in this field follow the typical scheme for the application of FEM. Materials and methods. The analysis showed that the typical scheme for the application of FEM in mining sciences contains a fundamental error related to the inadequate consideration of the representative volume of rocks during the construction of a continuous medium model and the formation of a discrete model. This leads to a significant degree of inaccuracy in the modeling results. Results and discussion. To resolve the fundamental error, a new scheme for the application of FEM in mining sciences is proposed. It differs from the typical scheme by introducing a new intermediate model between the rock mass and the continuum model. This model, named ‘rock mass body’, represents a set of geoparticles. The sizes of the geoparticles are determined according to the representative volume of the structural or textural components of the rock mass. Comparative analysis has shown that, unlike the typical scheme for the application of FEM, the use of the proposed scheme allows to get solutions with a high degree of accuracy when researching rocks with coarse-grained and medium-grained structures. Conclusion. An analysis of the typical scheme for the application of FEM identified a fundamental error in its use for rock mass modeling tasks. A new scheme has been proposed to correct this error. Suggestions for practical application and direction of future research. The research results can be used to improve the accuracy of finite element models of rock masses. Further research should focus on improving methods for determining the shape of finite elements in relation to the symmetry of the structural and textural components of the rock mass. At the same time, it is necessary to take into account the fracturing of rocks.

First photometric study of W UMa-type binary systems: BK Vul and V699 Cep

In this study, new CCD photometric observations and photometric analysis of BK Vul and V699 Cep systems, which are classified as contact binaries in the literature, are presented. For the V699 Cep, the TESS light curve was also used in the photometric analysis. We determined the basic astrophysical parameters of the BK Vul and V699 Cep systems from photometric analysis using the Wilson–Devinney method. Due to the lack of spectroscopic data for both systems in the literature, these absolute parameters were approximately calculated as to be M2 = 0.73 M⊙, R1 = 1.39 R⊙ and R2 = 1.09 R⊙ for BK Vul, and M2 = 0.36 M⊙, R1 = 2.40 R⊙ and R2 = 1.33 R⊙ for V699 Cep after estimating the mass of the primary component. The period decrease rate (dP/dt) and cyclic variation period of BK Vul were determined from the O−C analysis as -3.86 ×10−7 day yr−1 and 27 yrs., respectively. The evolutionary status of components of both systems were discussed.

Insights into the Optimization of Catalytic Active Sites in Lithium-Sulfur Batteries.

ConspectusLithium-sulfur batteries (LSBs), recognized for their high energy density and cost-effectiveness, offer significant potential for advancement in energy storage. However, their widespread deployment remains hindered by challenges such as sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LiPSs). By the introduction of catalytic materials, the effective adsorption of LiPSs, smooth surface migration behavior, and significantly reduced conversion energy barriers are expected to be achieved, thereby sharpening electrochemical reaction kinetics and fundamentally addressing the aforementioned challenges. However, driven by practical application targets, the demand for higher loadings and reduced electrolyte parameters inevitably exacerbates the burden on catalytic materials during their service. Additionally, given that catalytic materials contribute negligible electrochemical capacity, their incorporation inevitably increases the mass of nonactive components for reducing the energy density of LSBs. A meticulous insight into the lithium-sulfur catalytic reaction reveals that the conversion of LiPSs is dominated by active sites on the surfaces of catalytic materials. These microregions provide the necessary electron and ion transport for the conversion reaction of LiPSs, with their efficacy and quantity directly impacting the conversion efficiency. In light of these considerations, the strategic optimization of active sites emerges as a paramount pathway toward promoting the performance of LSBs while concurrently mitigating unnecessary mass. Here, we outline three strategies developed by our group to optimize active sites of catalytic materials: (1) Augmenting active sites by customizing structural modulation and precise dimensional control to maximize exposure. Emphasis has been placed on the approaches for material synthesis and the essence of reactions for achieving this strategy. (2) Regulating the microenvironment of active sites by integrating the coordination refinement, long-range atomic interactions, metal-support interactions, and other electronic regulation strategies, thereby providing an elevation in the intrinsic catalytic performance. (3) Implementing a self-cleaning mechanism for active sites to counteract deactivation by designing a tandem adsorption-migration-transformation pathway of sulfur contained within the molecular domain. Throughout this process, the intrinsic mechanisms driving performance enhancement through active site optimization strategies have been prominently emphasized, which encompass aspects such as electronic structure, atomic composition, and molecular configuration and significantly expand the comprehension of Li-S catalytic chemistry. Subsequently, considerations demanding heightened attention in future processes of active site optimization for catalytic materials have been delineated, including the in situ evolution patterns and resistance to the poisoning of active sites. It is noteworthy that given the similarity between Li-S catalysis chemistry and traditional electrocatalytic processes, this Account elucidates the concept of active site optimization by drawing insights from representative works and our own works in the field of electrocatalysis, which is relatively rare in previous reviews of LSBs. The proposed insights contribute to uncovering the intrinsic mechanisms of Li-S catalysis chemistry and introducing innovative ideas into active site optimization, ultimately advancing energy density and stability in LSBs.

Cardiovascular and cardiorespiratory effects of high-intensity interval training in body fat responders and non-responders

This study aimed to investigate cardiovascular and cardiorespiratory adaptations to exercise intervention among participants who showed higher (responders–RsBFP) and lower (non-responders–NRsBFP) levels of body fat percentage (BFP) responsiveness. Adolescents (42.5% males) participated in a ten-week school-based high-intensity interval training (HIIT), followed by a comparison of BFP, blood pressure (BP), and cardiorespiratory fitness (CRF). RsBFP age of 16.15 ± 0.36 years, body height 170.82 ± 8.16 cm, weight 61.23 ± 12.80 kg, and BMI 20.86 ± 3.29 kg/m2. Meanwhile, NRsBFP age of 16.04 ± 0.36 years, body height 168.17 ± 8.64 cm, weight 57.94 ± 8.62 kg, and BMI 20.47 ± 2.24 kg/m2. HIIT intervention impacted BFP, with a higher decrease in the RsBFP than the NRsBFP (ΔBFPRs = − 2.30 ± 3.51(10.34%) vs. ΔBFPNRs = 1.51 ± 1.54(6.96%) p < 0.001). The primary comparison showed a statistically significant interaction effect in relation to CRF (F(1,71) = 14.12; p < 0.001). Detailed comparisons showed large and significant CRF changes in RsBFP (7.52%; d = 0.86; p < 0.001) but not in NRsBFP (2.01%; d = 0.11; p = 0.576). In addition, RsBFP and NRsBFP benefited equally in SBP (5.49%, d = 0.75; p < 0.001; 4.95%, d = 0.74; p < 0.001, respectively). These findings highlight that exercise benefits on body fat may be mainly related to gains in CRF. Due to substantial intra-individual variability in adaptation, there is a need for personalized intervention tailored for those with different reaction thresholds in body mass components.

Expected evolution of the binary system PTF J2238+743015.1

Binary systems harboring a low-mass CO WD and a He-rich donor are considered to be the possible progenitors of explosive events via He detonation, producing low-luminosity thermonuclear supernovae with a peculiar nucleosynthetic pattern. Recently, the binary system PTF J223857.11+743015.1 was proposed as a candidate for this kind of stars. We investigate the evolution of the PTF J223857.11+743015.1 system, which is composed of a 0.75\ CO WD and a 0.390\ subdwarf. We consider the rotation of the WD component. Using the FuNS code, we computed the evolution of the two stars simultaneously, taking into account the possible evolution of the orbital parameters, as determined by mass transfer between the components and by mass ejection from the system during episodes of Roche lobe overflow. We consider that the WD gains angular momentum due to accretion and we followed the evolution of the angular velocity profile as determined by angular momentum transport via convection and rotation-induced instabilities. As the donor H-rich envelope is transferred, the WD experiences recurrent very strong H-flashes triggering Roche lobe overflow episodes during which the entirety of the accreted matter is lost from the system. Due to mixing of chemicals by rotation-induced instabilities during the accretion phase, H-flashes occur inside the original WD. Hence, pulse by pulse, the mass of the accretor is reduced down to 0.7453\ Afterwards, when He-rich matter is transferred, He detonation does not occur in the rotating WD, which undergoes six very strong He-flashes and subsequent mass-loss episodes. Also in this case, due to rotation-induced mixing of the accreted layers with the underlying core, the WD is eroded. Later, as the mass-transfer rate from the donor decreases, a massive He buffer is piled up onto the accretor, which ends its life as a cooling WD. The binary system PTF J2238+743015.1 and all other binary systems with components of similar masses and similar orbital parameters are not good candidates as thermonuclear explosion progenitors.

Thermal degradation of non-isocyanate polyurethanes

Non-isocyanate polyurethanes (NIPUs) are considered as a class of environmentally-safe polymers that show promising properties, such as chemical and mechanical resistance. An important feature that may limit some important applications is the thermal degradation behavior of NIPUs and their composites and hybrids. Hence, this article comprehensively reviews recent developments in these materials groups, focusing on the thermal stability and degradation routes. Influence of urethane linkage vicinity, molar mass and ratio of carbonate and amine components, and chemical structure on NIPU thermal degradation behavior was discussed. The onset temperature of degradation was found to be mainly influenced by urethane bonds concentration and crosslinking density of NIPU material. Chain length of amine component has also a significant impact on the thermal degradation profile. The incorporation of bio-sourced and nano-scaled additives (carbon- and silica-based nanoparticles) and their impact on thermal stability of NIPU matrix was analyzed, too, and future outlooks were given.

Improved model of the Supernova Refsdal cluster MACS J1149.5+2223 thanks to VLT/MUSE

We present new \, observations of the Hubble Frontier Field (HFF) galaxy cluster MACS J1149.5+2223, lensing the well-known supernova ``Refsdal'' into multiple images, which has enabled the first cosmological applications with a strongly lensed supernova. Thanks to these data, targeting a northern region of the cluster and thus complementing our previous \, program on the cluster core, we have released a new catalog containing \, secure spectroscopic redshifts. We confirmed 22 cluster members, which had previously been only photometrically selected, and detected ten additional ones, resulting in a total of 308 secure members, of which 63&lt;!PCT!&gt; are spectroscopically confirmed. We further identified 17 new spectroscopic multiple images belonging to six different background sources. By exploiting these new and our previously published \, data, in combination with the deep HFF images, we developed an improved total mass model of MACS J1149.5+2223. This model includes 308 total mass components for the member galaxies and requires four additional mass profiles, one of which is associated with a cluster galaxy overdensity identified in the north, representing the dark matter mass distribution on larger scales. The values of the resulting 34 free parameters are optimized based on the observed positions of 106 multiple images from 34 different families, that cover an extended redshift range between 1.240 and 5.983. Our final model has a multiple image position root mean square value of which is in good agreement with other cluster lens models based on a similar number of multiple images. With this refined mass model, we have paved the way toward an improved strong-lensing analyses that will exploit the deep and high resolution observations with \, and \, on a pixel level in the region of the supernova Refsdal host. This will increase the number of observables by around two orders of magnitude, thus offering the opportunity to carry out more precise and accurate cosmographic measurements in the future.

Структурные особенности коренных сосняков северной и средней тайги при пирогенных воздействиях

The study of indigenous pine forests of evolutionary formation as endangered virgin forests is the basic for fundamental research into the processes of formation of sustainable forest communities. The aim of the study presented in the article is a comparative assessment of the structures of tree fractions of phytocenoses according to the parameters of the age series of stands and the successional position, dynamic indicators of woody waste, the influence of the pyrogenic factor, and the presence of rot damage to the stands. Age structures, numerical and linear parameters of pyrogenic factors, their impact on the infestation of trees with rot, volumetric indicators of wood waste and characteristics of natural regeneration, the mass of wood xylolysis products during its decomposition by wood-destroying fungi have been studied in pine biogeocenoses with various dynamic characteristics in the taiga zone of European Russia. Pine biogeocenoses under these conditions have structures of different ages, altered by fires of different types. Using the example of an indigenous pine forest in the Pechora-Ilychskiy Nature Reserve (middle taiga), the influence of pyrogenic effects on the formation of various types of rot and damage to trunks is shown. The volumes of woody waste are distributed according to the stages of decomposition in pine forests with different structural and dynamic characteristics; pine undergrowth – according to height gradations. An example is given of calculating the mass of wood components deposited in the stands and released during the decomposition of woody waste by wood-destroying fungi for the biogeocenosis of the Pechora-Ilychskiy Nature Reserve. The majority of indigenous pine forests in the northern territories have been affected by fires of varying intensity and types, sometimes several times during a development cycle. Pyrogenic effects have a significant on changes in the age structures of pine forests, damage to their trunks, the general infestation of forest stands by wood-destroying fungi of the biotrophic complex, the volumes of woody waste, and the formation of natural regeneration structures.

Improving the electrical conductivity of multiwalled carbon nanotubes‐containing micromoldings via in situ construction of electrically conductive networks

AbstractMicroinjection molding (μIM) is characterized by high shearing and cooling rates, resulting in higher a degree of filler orientation which impairs the electrical conductivity (σ) of conductive filler‐containing polymer composites when compared with that of compression molding and conventional injection molding processes. In this study, polypropylene/polyamide 6/multiwalled carbon nanotubes (PP/PA6/CNT) composites were used as the model system to investigate how blending sequence, injection speed, and component mass ratios affected the morphology and σ of PP/PA6/CNT microparts. The results demonstrated that CNTs exhibited a higher affinity for the polar PA6 phase and they tended to be preferentially distributed in PA6 domains. The deformation and coalescence of CNT‐rich PA6 phase promoted the creation of an intact and continuous filler network structure along the flow direction under the influence of high shearing conditions in μIM. When the mass ratio of PP:PA6 was 70:30 and the concentration of CNT was 7 wt%, the micropart possessed the highest σ (1.2 × 10−6 S/m) when compared with their PP/CNT (4.4 × 10−9 S/m) and PA6/CNT (3.4 × 10−10 S/m) counterparts. Higher injection speeds resulted in higher degree of CNT orientation, which negatively affected the σ of subsequent moldings. This work established an approach for producing electrically conductive microparts that demonstrate promising applications in the fields of electronics, automotive, and microsystems among others.Highlights PP/PA6/CNT composites were used as model systems for microinjection molding. The electrical conductivity was improved by shear‐induced deformation of CNT‐rich phase. The properties of PP/PA6/CNT microparts were affected by process parameters.