Large Number Of Fragments Research Articles

Multiphase fragmentation: Molecular shattering

Abstract Recent observations suggest galaxies may ubiquitously host a molecular component to their multiphase circumgalactic medium (CGM). However, the structure and kinematics of the molecular CGM remains understudied theoretically and largely unconstrained observationally. Recent work suggests molecular gas clouds with efficient cooling survive acceleration in hot winds similar to atomic clouds. Yet the fragmentation of molecular clouds into a large number of fragments (‘shattering’) when subjected to external shocks or undergoing rapid cooling remains unstudied. We perform radiative, inviscid hydrodynamics simulations of clouds perturbed out of pressure equilibrium to explore the process of shattering to molecular temperatures. We find molecular clouds larger than a critical size can shatter into a mist of tiny droplets, with the critical size deviating significantly from the atomic case. We find that cold clouds shatter only if the sound crossing time exceeds the local maximum of the cooling time ∼8000 K. Moreover, we find evidence for a universal mechanism to ‘shatter’ cold clouds into a ‘mist’ of tiny droplets as a result of rotational fragmentation – a process we dub ‘splintering.’ Our results have implications for resolving the molecular phase of the CGM in observations and cosmological simulations.

Fractionation as the main method for smoked tobacco products identification

Smokeless tobacco products are products that do not require a pyrolysis process and / or the production of tobacco aerosol (smoke) at the time of use. In the absence of data on the toxicological risks of smokeless tobacco, their consumption is potentially on the rise. The variety of non-smoking tobacco products creates certain problems in identifying chewing tobacco and sucking tobacco (banned for sale in the Russian Federation) as products that are identical in terms of physiological effects, method of consumption, and component composition. A methodology has been developed for a comprehensive assessment of non-smoking products, including the determination of consumer properties and technological indicators by instrumental methods, as well as the determination of the level of toxic components (nicotine, TSNA, B(a)P). The difference between the types of smokeless tobacco is mainly in the granulometric composition of the product: snus – finely ground tobacco, chewing tobacco – snatches of tobacco with a removed middle vein. Identification indicators have been determined: the presence of raw tobacco, the size of its particles and the number of large fragments in the finished product. The presence of raw tobacco can be determined by optical microscopy and/or luminescent analysis, and the quantitative content can be determined by sieve analysis. The quantitative content of the coarse fraction in chewing tobacco (not less than 15 %) is the main indicator of the product. The use of the fractionation method makes it possible to differentiate between sucking and chewing tobacco. A «Method for determining the fractional composition of non-smoking tobacco products for oral consumption by the method of sieve analysis» was developed (Certificate No. 022-01.00281-2013-2022). To certify the methodology, a set of studies was carried out, the data were obtained as a result of five parallel measurements by three performers for each sample. The technique is registered in the State Register of Measuring Instruments (FR.1.31.2022.43935 of 09/02/2022). Technological indicators of SLT samples were established: humidity (11,4-53,3) %, pH level 5,7-9,7, coarse fraction content (0,4-56,9) %, dust fraction content (0,2-76,3) %. The results of identification of commercial samples of a segmental product are presented.

Experimental and numerical studies of fragmentation shells filled with advanced HMX-plastic explosive compared to various explosive charges

The wide usage of TNT as a main charge for fragmentation shells has been eliminated due to its lower performance and exudation on the fuze thread and relevant safety measures inconvenience. These disadvantages have not become accepted anymore due to the desired safety requirements and the limited efficiency of the TNT, especially when different new explosives are introduced into researches. This research studies the fragmentation calculations of the 120 mm high explosive shell when its is loaded with different explosives rather than TNT. Different explosives have been used in the current research include the melt cast compositions such as Octol and composition B, a cast cured composition based on RDX with HTPB polymer matrix and the plastic explosive composition HMX-silicone. The fingerprint of the fragmentation pattern of each shell loaded with different explosive has been obtained using Autodyn smooth particle hydrodynamic (SPH) algorithm, whose numerical model has been validated with previous measurements using TNT explosive. Based on obtained numerical estimates, the HMX-silicone explosive has been proposed to replace the traditional TNT explosive material. This explosive has been then manufactured and casted into the studied 120 mm shell, where the experimental field pit test was established to collect, separate and analyse the resultant fragments. Current calculations and experimental results showed that the shell loaded by composition HMX-silicone produced the highest fragmentation velocities (i.e. 1.5 times that of TNT) and the largest number of fragments (i.e. 2.7 times that of TNT) with lower masses, which will be recommended for our next production stages instead of the traditional TNT.

Early experience in ureteroscopy and pneumatic lithoclast in AL Hilla City

Introduction: Urological treatment of urinary calculi has changed much in the past 20 years (1). Endoscopic intra Ureteral lithotripsy has developed as the result of advances in techniques for uretroscopy and lithotripsy Aim of the study to determine the utility and the efficacy of pneumatic lithoclast in the treatment of uretric stone as early experience in AL- HillA city. Method: cross sectional study of one hundred patients with uretric stone with size ranged from (0.5-1.5 cm) and different level (upper, middle, lower Ureter 15, 20, 65 respectively) treated with uretroscopy and pneumatic lithoclast under general and spinal anesthesia. Result: About 90 patients have cleared from uretric stone within 2 weeks. The other 10patient’s not responding because Upward migration (6 patients), Ureteral perforation (4 patients). 50 patient’s need’s double j stenting at the end of the procedure because large number of fragments’ and due to hematuria. The other 50 patients not need double j stenting because small stone and easy to pass spontaneous. Conclusion: By conclusion early intervention is advisable .mid or upper ureteric stone also can deal with.

Microstructure and mechanical properties of unalloyed molybdenum fabricated via wire arc additive manufacturing

Molybdenum is an important high-temperature structural material but has poor processability. Additive manufactured unalloyed Mo is generally very small and the mechanical properties is seldomly studied. In this work, wire arc additive manufacturing was adopted, and crack-free molybdenum parts with high-density (99.0%) and characteristic size of 20 mm×20 mm×120 mm were successfully fabricated by short-track scanning. The microstructure and mechanical properties of samples in both the as-deposited and heat-treated states were studied and compared. Large columnar grains were observed, which were basically along the 〈001〉 direction. Heat treatment leads to grain coarsening, and the elimination of some sub-grain boundaries. Due to the weakened effect of grain and sub-grain boundary hardening, the mechanical properties of heat-treated specimens were worse than that of as-deposited specimens at room temperature. Both of them exhibit brittle fracture features. Under high temperature, the ductile fracture is observed, and the as-deposited specimen has similar strength and ductility, compared with the heat-treated specimens, suggesting a weak role of grain and sub-grain boundary at high temperature. A large number of fragments were observed at the fracture surface after high-temperature tests, which was MoO3 by energy dispersive spectroscopy test.

CATComp: A Compression-Aware Authorization Protocol for Resource-Efficient Communications in IoT Networks

The Internet of Things (IoT) devices exchange certificates and authorization tokens over the IEEE 802.15.4 radio medium that supports a maximum transmission unit (MTU) of 127 bytes. However, these credentials are significantly larger than the MTU and are, therefore, sent in a large number of fragments. As IoT devices are resource constrained and battery powered, there are considerable computations and communication overheads for fragment processing both on the sender and receiver devices, which limit their ability to serve real-time requests. Moreover, the fragment processing operations increase energy consumption by CPUs and radio transceivers, which results in shorter battery life. In this article, we propose CATComp—a compression-aware authorization protocol for constrained application protocol (CoAP) and datagram transport layer security (DTLS) that enables IoT devices to exchange small-sized certificates and capability tokens over the IEEE 802.15.4 media. CATComp introduces additional messages in the CoAP and DTLS handshakes that allow communicating devices to negotiate a compression method, which devices use to reduce the credentials’ sizes before sending them over an IEEE 802.15.4 link. The decrease in the size of the security materials minimizes the total number of packet fragments, communication overheads for fragment delivery, fragment processing delays, and energy consumption. As such, devices can respond to requests faster and have longer battery life. We implement a prototype of CATComp on Contiki-enabled RE-Mote IoT devices and provide a performance analysis of CATComp. The experimental results show that communication latency and energy consumption are reduced when CATComp is integrated with CoAP and DTLS.

Excavation of the Western Suburban Complex of Bol’shoy K’irk-K’iz in 2021

During excavations in 2021 at the Western Suburban Complex (WSC) of the Bol’shoy K’irk-K’iz, room I and the northern courtyard were investigated. In room II, the later interior extensions in its western and southern parts were dismantled. After it became clear that the width of room II was originally 4 m. At the first stage of functioning, the walls were covered with clay plaster with whitewash. The few pottery fragments that were found in room II date back to the 4th-2nd centuries. BC, possibly 1st c. BC. In 2021, the study of the new room III began. The original excavation was extended to the south by 8.4 m. At an elevations of -207 and -202 from the benchmark, the floor was opened in the form of a pavement of mud bricks (40×40×12; 42×42×12; 39×42×11–12 cm). In rooms II and III, a large number of fragments of plaster with traces of polychrome painting were found. Particularly numerous are fragments of bright blue paint, which undoubtedly dominated the color scheme of room III, which made it possible to call it the “Blue Hall”. The WSC arose simultaneously with the Bol’shoy K’irk-K’iz no later than the turn of the 4th-3rd centuries. BC. The period of functioning of the complex does not go beyond the ancient Chorasmian period. In general, the planning scheme of the WSC, as well as the existing architectural analogies, allows us to speak with confidence about the palace-temple character of the entire monument.

INTROSPECTION AS A SIGN OF LYRICALLY-DRAMATIC GENRE TYPE IN E. ELGAR’S VIOLIN CONCERTO

Statement of the problem. Edward Elgar’s instrumental concertos occupy the special place in European music. Most of the violin concertos of Romantic composers were written before E. Elgar created his own (1910); the concertos by J. Sibelius (1904) and M. Reger (1908) are closest to this work in time, and Elgar’s Concerto almost coincides with the chronology of K. Nielsen’s Violin Concerto (1911), which has already been, however, significantly influenced by neoclassical aesthetics. In five years, K. Szymanowski’s First Violin Concerto (1916) will appear, rejecting the romantic way of expression, and later a new “era” in the development of this genre will begin. Elgar’s Violin Concerto (1910), the first of his two instrumental concerts, is another step of the composer on the way to mastering various musical genres, the accumulation of new creative ideas. In a number of parameters, the work is closer to the First Symphony, becoming almost a doppelganger of it but with a solo violin, an instrument played by the composer himself. Thus, the study of the Concerto is relevant, at least, in three aspects: in the analysis of the creative evolution of the composer, for understanding his attitude to the concert genre, and for revealing the meaning of the composer’s self-expression. Consideration of the work in the aspect of the latter – identifying features of introspection in the music of the Violin Concerto as part of its genre structure – is the purpose of this study, which is the first attempt of its kind. Conclusions. Elgar’s Violin concerto follows the tradition of lyricallydramatic type of symphonism, which the composer employed in his First symphony written shortly before the Concerto. It can be seen both in thematically-intonational content and in special features of dramaturgy and composition (“throughout” themes, large duration, conflict dramaturgy). The genre of instrumental concerto suggests additional dimension of the work, relation between solo and orchestral parts, and in this case the composer maintains a balance in such things as distribution of themes and their development and interpretation of soloist’s part. The introspective character of the Violin concerto is most obvious in its Cadenza – the most significant episode for this genre – due to its significant length, the lyrical way of expression, reminiscences and derivative themes, the rejection of a clear metrorhythmic organization that allows the perception of Cadenza as a stop in time for lyrical reflection. Other aspects of introspectiveness include the predominance of lyrical themes, a large number of fragments with quiet dynamics and the genre’s predicted concentration of attention on the soloist, although the composer retains balance between solo and orchestral parts.

Effects of drop shock on fragmentation of two stored grain pest species, Tribolium castaneum and Sitophilus zeamais

To prevent insect contamination in food supply chains, an understanding of the circumstances and timing of insect invasion is important. Fragmented insects are often found in food products, and mechanical stress such as drop shock during transportation and/or handling may contribute to such fragmentation. In this study, we used two stored grain pest species, Tribolium castaneum and Sitophilus zeamais, to investigate the effects of drop shock and the state of the insect (living, or dead for 1 day or 1 month) on the number and size of insect fragments. A cardboard box containing an adult insect placed between two aluminum plates was dropped from heights of 0.2–0.8 m. The results revealed that the number of fragments of dead insects of both groups was larger than that of living insects. Both species showed similar trends in the number of fragments, although the two species had different fragilities at each drop height. The number of fragments increased with the drop height for both groups of dead insects, but it was not associated with the drop height for living insects. The trends of fragmentation suggested that an insect with a large number of fragments was subjected to severe shock after death, whereas one with a small number of fragments was subjected to light shock after death or to any degree of drop shock while alive. We concluded that the difference in fragmentation can provide useful information about the circumstances and timing of insect contamination in food supply chains.

Protoplanet collisions: Statistical properties of ejecta

ABSTRACT The last phase of the formation of rocky planets is dominated by collisions among Moon- to Mars-sized planetary embryos. Simulations of this phase need to handle the difficulty of including the post-impact material without saturating the numerical integrator. A common approach is to include the collision-generated material by clustering it into few bodies with the same mass and uniformly scattering them around the collision point. However, this approach oversimplifies the properties of the collision material by neglecting features that can play important roles in the final structure and composition of the system. In this study, we present a statistical analysis of the orbital architecture, mass, and size distributions of the material generated through embryo–embryo collisions and show how they can be used to develop a model that can be directly incorporated into the numerical integrations. For instance, results of our analysis indicate that the masses of the fragments follow an exponential distribution with an exponent of −2.21 ± 0.17 over the range of 10−7 to 2 × 10−2 Earth-masses. The distribution of the post-impact velocities show that a large number of fragments are scattered towards the central star. The latter is a new finding that may be quite relevant to the delivery of material from the outer regions of the asteroid belt to the accretion zones of terrestrial planets. Finally, we present an analytical model for the 2D distribution of fragments that can be directly incorporated into numerical integrations.

Time-Frequency Characteristics and the Influence Mechanism of the EMR from Coal with Different Joint Angles

It is vital to understand the electromagnetic radiation’s time-frequency characteristics in the process of coal and rock failure with different joint angles in order to reveal the generation mechanism of the electromagnetic radiation (EMR) and improve the accuracy of EMR early warning. We studied the time-frequency characteristics of EMR signals of coal samples with different joint angles. The study finds that, (1) with the increase of joint angle, the failure time and peak load of samples decrease first and increase later, and the postpeak failure time decreases gradually. The EMR counts’ peak value showed a slow rise, a sharp rise, and a slow rise in the three intervals of α = 0° to 45°, 45° to 60°, and 60° to 90°, respectively. The accumulated EMR counts showed a steady upward trend. The duration of the EMR waveform, the dominant frequency of the EMR, and the peak number of the frequency spectrum of coal samples are on the rise. (2) As the joint angle increases, the samples’ failure mode changes from the stage fracture dominated by tension cracks to the rapid fracture with the coexistence of shear and tension cracks and finally to the burst fracture which produces a large number of fragments. This is also the main reason for the difference of the EMR generation mechanism and the signal of samples with different joint angles. (3) According to the experimental results, we established the modified formulas for calculating the EMR threshold value and deviation of coal and rock with joints under different stress environments and revealed that the longer the EMR waveform duration, the higher the dominant frequency, and the more the number of spectrum peaks, the greater the burst risk of coal and rock.

Formation and penetration of PELE/EFP multi-mode warhead based on double-layer shaped charge

ABSTRACT The outer layer of a double-layer shaped charge (DLSC) adopts high-detonation-velocity explosive (HE) and the inner layer adopts low-detonation-velocity explosive (LE). Compared with ordinary shaped charge (OSC), it changes the incidence angle of detonation wave on liner and improves the detonation pressure. According to different battlefield targets, the multi-mode warhead selects corresponding projectiles, when penetrator with enhanced lateral efficiency (PELE) penetrates a light armor, it can break into a large number of fragments behind target to enhance aftereffect damage. Explosively formed projectile (EFP) is used to penetrate long-distance heavy armors, the performance indexes of EFP are penetration depth and opening diameter. This article establishes a mathematical model of PELE/EFP in DLSC and studies the terminal damage effect of PELE/EFP through numerical simulation and experiment. The results of theoretical analysis, numerical simulation and experimental research are consistent. The results show that when a DLSC is applied to PELE/EFP multi-mode warhead, the overall damage performance of PELE/EFP is greatly improved compared with an OSC. The dispersion radius of effective fragments behind target is increased by 32.6%, the number of fragments is increased by 78.67% and the penetration depth is increased by at least 107.8%.

Кремневое производство на поселении усатовской культуры Маяки

Usatovo culture settlement of Mayaki was discovered in 1961. The site is located on the southeastern outskirts of the village of Mayaki, on the plateau of the Dniester left bank. The first studies were carried out by V. G. Zbenovich on an area of ca. 500 m2. It was found out that the site is a system of ditches of different sizes, filled with cultural remains. The author publishes the flint collection (3683 pieces) from Mayaki settlement (studies led by V. G. Petrenko in 1990s — 2000s). The primary flint splitting and production of secondary retouched tools took place on the area of the site. This is evidenced by a fairly large number of fragments, core spalls, cores and production waste in the form of various flakes, scales, as well as secondary retouched finished products. The collection contains flint pebbles, cores, flakes, blades, production wastes, scrapers, trapeziums, Kukrek insert, points, retouched blades, flakes, fragments and other tools. Some tools turned out to belong to the earlier archaeological eras. They were picked up somewhere by the Eneolithic inhabitants of the settlement. At the Usatovo culture settlement of Usatovo-Bolshoi Kuyalnik, quite a lot of tools were produced from imported flint. On the contrary, at Mayaki settlement, based on the examined materials, practically all tools, with some exceptions, were produced from local raw materials.

Bone resorption of the greater tuberosity after open reduction and internal fixation of complex proximal humeral fractures: fragment characteristics and intraoperative risk factors

In complex proximal humeral fractures, bone resorption of the greater tuberosity is sometimes observed after open reduction and internal fixation (ORIF). However, this has not been well characterized, and risk factors for resorption are not completely understood. We aimed (1) to identify the risk factors associated with bone resorption of the greater tuberosity and (2) to quantify the geometric and bone density characteristics associated with bone resorption using 3-dimensional computed tomography models in complex proximal humeral fractures treated with ORIF. We identified a retrospective cohort of 136 patients who underwent ORIF of 3- or 4-part proximal humeral fractures; greater tuberosity resorption developed after ORIF in 30 of these patients. We collected demographic, fracture-related, and surgery-related characteristics and performed multivariable logistic regression analysis to identify factors independently associated with the development of greater tuberosity resorption. Furthermore, we identified 30 age- and sex-matched patients by use of propensity score matching to perform quantitative fragment-specific analysis using 3-dimensional computed tomography models. After the fragment of the greater tuberosity was identified, the number of fragments, the relative fragment volume to the humeral head, and the relative bone density to the coracoid process were calculated. Measurements were compared between matched case-control groups. We found that an unreduced greater tuberosity (odds ratio [OR], 10.9; P < .001), inadequate medial support at the calcar (OR, 15.0; P < .001), and the use of an intramedullary fibular strut (OR, 4.5; P = .018) were independently associated with a higher risk of bone resorption. Quantitative fragment-specific analysis showed that greater tuberosities with a larger number of fragments (5 ± 2 vs. 3 ± 2, P = .021), smaller fragments (9.9% ± 3.8% vs. 18.6% ± 4.7%, P < .001), and fragments with a lower bone density (66.4% ± 14.3% vs. 88.0% ± 18.4%, P = .001) had higher rates of resorption. An unreduced greater tuberosity or inadequate medial support increases the risk of greater tuberosity resorption, as do a larger number of fracture fragments, smaller fragments, and lower bone density. Additionally, fibular strut grafting is an independent risk factor for tuberosity resorption. Further study is needed, but alternatives to strut grafting such as femoral head allograft may warrant serious consideration.

Evaluation of BOX-PCR and REP-PCR as Molecular Typing Tools for Antarctic Streptomyces.

Molecular studies led to the resurgence of natural products research from genus Streptomyces, already known for their long history and importance for the pharmaceutical industry. However, species belonging to this genus are difficult to identify and the most commonly used techniques, which are based on 16S rRNA sequencing, do not discriminate between related species. In this work, amplification profiles generated from BOX-PCR and REP-PCR of 49 Antarctic soil streptomycetes were compared to evaluate the diversity present in the group and to characterize the bacterial isolates, along with some 16S rRNA amplifications. The BOX-A1R primer exhibit clearer amplification fragments, different from the amplification patterns obtained using the REP 1R and 2R primers. A higher diversity was observed with REP-PCR amplifications, even though a larger number of fragments was obtained with BOX-A1R primer amplifications. There are at least four isolates that showed great similarity (about 90%) in both techniques. In other hand, there are two others that are 90% similar in BOX-PCR, but distant in REP-PCR, showing only 40% of similarity. Results of the combination of BOX-PCR and REP-PCR represent a simple and low-cost method to discriminate between Streptomyces strains. There is no species identification with only the 16S rRNA, most isolates seem to be related to S. globisporus. Further studies added to the obtained results may provide better data to help the characterization of these microorganisms.

Multiscale modeling of continuous crushing of granular media: the role of grain microstructure

Natural granular materials such as sands often possess complex microstructural features including cleavage and minerals interfaces. Those features bring apparent mechanical anisotropy to particles and are known to have pronounced influence on particle crushing characteristics. This paper presents a multiscale simulation of continuous crushing of granular sand under one-dimensional compression in consideration of particle-scale anisotropy through modeling planes of weakness inside individual particles, with reference to granular materials rich in minerals and containing cleavages. The multiscale modeling is based on a coupled peridynamics and non-smooth contact dynamics method where peridynamics is used to model crushing of individual particles and non-smooth contact dynamics is employed to simulate discrete granular system. Weak microstructural planes are simulated by breaking a fraction of peridynamic bonds as an initial condition. Simulation results show that anisotropic particles containing weak planes result in larger number of fragments and exhibit relatively higher fractal dimension with respect to particle size. Particle shape is found to approach a steady state profile with continuous crushing. Anisotropic particles generally bear smaller sphericity, aspect ratio, elongation and flatness than those isotropic particles. The anisotropy in particles seems to mitigate shape effect on particle strength and crushing energy. Macromechanical yield stress of the sample is related to single particle strength monotonically, but the relationship appears to be nonlinear when different microstructural features are involved.

On models of meteoroid disruption into the cloud of fragments

The meteoroid disruption into a large number of fragments when they move with a common shock wave before dispersion to a sufficient distance to move independently is considered. Disrupted meteoroid under the action of pressure forces is deformed: it is compressed in a flight direction and expands in a lateral one. Four models of the meteoroid disruption into a cloud of fragments moving as a single body are considered: two models developed by the authors and two models used in the literature (Grigoryan, 1979; Hills and Goda, 1993). The principal differences between the proposed and accepted models are shown. Numerical solutions of the meteor physics equations are obtained using the above models to simulate the interaction of the Chelyabinsk meteoroid with the atmosphere. To model the meteoroid ablation, an approximate formula is used for the radiative heat transfer coefficient as a function of the meteoroid velocity and size and the atmospheric density. The influence of the heat transfer coefficient uncertainty (including its constant value) on the meteoroid mass loss, energy deposition and initial mass estimate is studied. Solutions using different fragmentation models are compared with each other and with observational data and the results of comparisons are discussed.

Including crystallographic symmetry in quantum-based refinement: Q|R#2.

Three-dimensional structure models refined using low-resolution data from crystallographic or electron cryo-microscopy experiments can benefit from high-quality restraints derived from quantum-chemical methods. However, nonperiodic atom-centered quantum-chemistry codes do not inherently account for nearest-neighbor interactions of crystallographic symmetry-related copies in a satisfactory way. Here, these nearest-neighbor effects have been included in the model by expanding to a super-cell and then truncating the super-cell to only include residues from neighboring cells that are interacting with the asymmetric unit. In this way, the fragmentation approach can adequately and efficiently include nearest-neighbor effects. It has previously been shown that a moderately sized X-ray structure can be treated using quantum methods if a fragmentation approach is applied. In this study, a target protein (PDB entry 4gif) was partitioned into a number of large fragments. The use of large fragments (typically hundreds of atoms) is tractable when a GPU-based package such as TeraChem is employed or cheaper (semi-empirical) methods are used. The QM calculations were run at the HF-D3/6-31G level. The models refined using a recently developed semi-empirical method (GFN2-xTB) were compared and contrasted. To validate the refinement procedure for a non-P1 structure, a standard set of crystallographic metrics were used. The robustness of the implementation is shown by refining 13 additional protein models across multiple space groups and a summary of the refinement metrics is presented.

An efficient method for collecting the full-length adults, fragments, and eggs of Trichobilharzia spp. from the liver of definitive hosts.

Precise identification of avian schistosomes in the genus Trichobilharzia at the species level is difficult and requires both traditional morphological and molecular techniques. To obtain satisfactory results by traditional methods, the characteristics of the intact adults or large fragments of male and females are necessary. The present study aimed to introduce a more efficient method for collecting eggs and both fragments and intact worms for morphological identification of visceral Trichobilharzia spp. Thirty-eight domestic ducks (twenty-eight fresh and ten frozen) were studied. For fresh samples, warm saline (40-45°C) was injected into the portal vein or liver tissue, followed by slicing of the liver to small pieces in a large Petri dish. All materials were then transferred into the laboratory sieves arranged from the largest to the smallest mesh size and while crushed with the hand, washed, and filtered using a trigger water sprayer. The collected materials were studied under a stereomicroscope for parasite eggs, fragments, and full-length worms. Out of 28 freshly killed ducks, 19 (67.9%) and of 10 frozen ducks 6 (60%) were positive for visceral Trichobilharzia spp. The full-length worms and large fragments of male worms were mostly recovered with the mesh no. 150 (diameter of 106μm) and small fragments, especially of females, and eggs with the mesh no. 270 (diameter of 53μm). In addition to large numbers of fragments, 15 full-length adults were obtained from fresh and 2 from frozen ducks. The number of collected full-length adults was related to the worm burden. Since morphological description of different species of the genus Trichobilharzia is primarily based on the availability of adult worms, the application of methods that provide a higher number of intact males and females will result in better characterization of the species and deposition of appropriate voucher specimens. These results show the present method as a suitable tool for the collection of quality adults of visceral Trichobilharzia spp. in ducks.

Archaeological EXCAVATIONS &#x0D; OF THE MEDIEVAL SETTLEMENT MATLAS &#x0D; IN THE MOUNTAINOUS AREA OF DAGESTAN

The article is devoted to the results of preserving archaeological research of the Matlas settlement, located on the western tip of the Khunzakh plateau, in the Khunzakh region, in the Midland Dagestan. The total area of the study was 406 square meters. As a result of the work, the foundations of the walls of stone buildings, probably residential and economic structures, were fixed. In addition, a piece of land, used for farming, was fixed. The cultural layer of the settlement contains fragments of various metal products, fragments of glass bracelets, stone products, ceramics, including fragments of glazed vessels, and numerous animal bones. An open complex of buildings dates from the XI-XII centuries, basing on chronological indicators (glazed ceramics and glass bracelets).Matlas settlement was a stationary settlement. This is indicated by the presence in the cultural layer of a large number of fragments of ceramic dishes, bones of domestic animals, individual finds related to human everyday activities (stone tools, millstone details, fragments of glass jewellery, and rare finds of metal objects). The presence of pig bones in the archeozoological material is an additional indicator of the settled life. Findings of millstone fragments indicate the cultivation of grain by its inhabitants. The prevalence of cattle bones in the layers of the settlement suggests the presence of cattle breeding, most likely distant one.Archaeological material, obtained during the excavations of the Matlas settlement, is significant for characterizing the culture, life and economic activities of the population of the mountainous area of medieval Dagestan.