Results of experimental research of wound ballistics of separate types and calibers of modern bullets

There was made the analysis of wound ballistics of modern expansive bullets in comparison with shell bullets on 25 blocks of ballistic plasticine (ROMA PLASTILINA No. 1, Ballistic Testing Backing Material), made in the USA, in which one shot from an AKS-74 automatic firearm and carbine ZBROYAR Z-10 with an optical sight was fired. The bullet speed was the highest in 5.45x39 caliber cartridge with a V-max bullet. – 1185 m/s, low in the bullet caliber cartridge .308 Win with a bullet SP, – 664 m/s. The difference is significant at the level of significance α=0.05. In terms of the size of the entrance hole, the largest is from the bullet of cartridge .308 Win with a bullet SP – 10.0 cm, the smallest - from the bullet "PS" with a steel core 5.45x39 mm, cartridge sample of the year 1974 (7H6) – 1.2 cm. The difference is significant at the level of significance α=0.05. In the expansive bullet of type "V-Max" of shortgun cartridge of caliber 5.45x39 mm, the size of the entrance hole was 9.1 cm, with asterial shape having radial gaps and turned edges of ballistic plasticine on the outside. All cartridges with expansive bullets did not have an exit hole after the shot. The dimensions of the formed residual cavity were the largest after firing with .308 Win caliber cartridge with a bullet SP – 25.0x5.0 cm., the smallest – bullet of a military caliber cartridge of 5.45x39 mm (7H6) – 6.0x4.0 cm. The difference is significant at significance level α=0.05. The shape and character of the residual cavity in ballistic plasticine was significant for all expansive bullets, in contrast to the bullet of a military cartridge 5.45x39 mm (7H6), where no such changes are detected. The considerable signs of expansion properties and deformation of the bullet in the form of a "flower of death" were identified in the bullet of caliber cartridge .308 Win with a bullet SP, other bullets with expansive properties showed significant fragmentation, with the location of fragments both in the residual cavity and outside its borders at different distances. Expansive bullets differ significantly at the level of significance α=0.05. The low flight speed of bullets (m/s) of .308 Win caliber cartridges with bullets BTHP and SP is due to their structure, weight, and caliber. Bullet of type V-max with cartridge 5.45x39 mm has the highest speed – 1185 m/s, and due to its design has significant expansive properties. Common to expansive bullets is a entrance hole, the blind nature of the lesion with the presence of a large residual cavity, which is due to kinetic energy return 114.37 E, J/mm2 inside the object of lesion. Fragmentation of expansion bullets occurs inside an object with fragments located at different distances. A .308 Win caliber cartridge with SP bullet causes deformation of s bullet by the type of "death flower" causing significant damage.

Plastering mud around the entrance hole affects the estimation of threat levels from nest predators in Eurasian Nuthatches

Background For cavity-nesting birds, the nest entrance plays an important role in preventing predators from accessing nests. Several species of nuthatches use mud to narrow the entrance of cavities. In theory, the smaller the entrance hole size, the more effective it is against predators; however, few studies have tested whether narrowing the entrance hole size can affect the estimation of threat levels from nest predators in cavity-nesting birds. Methods Using dummy experiments, we tested whether Eurasian Nuthatches (Sitta europaea, narrow the entrance hole of cavities) and Cinereous Tits (Parus cinereus, do not narrow the entrance hole, as a control) perform different nest defence behaviours against Common Chipmunks (Tamias sibiricus, small nest predator) and Red Squirrels (Sciurus vulgaris, larger nest predator). Results Both nuthatches and tits exhibited stronger response behaviours (high dummy response scores) against chipmunks than against squirrels. Compared with tits, nuthatches exhibited more aggressive behaviours to chipmunks, but their responses to squirrels were similar. Conclusions Nest defence behaviours of nuthatches to chipmunks differed from tits, and the results suggested that nuthatches might estimate threat levels of nest predators according to their narrowed entrance-hole size.

Big Entrance Hole Perforation as New Alternative Approach to Optimize Thru-Tubing Sand Control Technique While Maintaining Reservoir Deliverability for Tunu Gas Reservoir in Unconsolidated Sand Formation

Mahakam block with one of its gas fields, Tunu, has been developed for decades. Hundreds of wells were drilled to unlock layered sand reservoirs ranging from unconsolidated to consolidated reservoirs. Through field experience, well architecture is actively developing. The latest architecture, targeting shallow reservoirs only, is called Shallow Light Architecture (SLA). The well is completed with 3.5in production tubing cemented inside a 8.5in open-hole reservoir section. SLA is the default architecture for chemical sand consolidation (SCON) or thru-tubing screens as subsurface sand control. Perforation is performed by deep penetration (DP) hollow-carrier guns deployed with double-density to maximize open area and reduce sand production risk. DP charges were used based on the requirement to bypass near-wellbore damage, which is the same practice used in consolidated sand reservoir perforating. As more marginal reservoirs need to be unlocked, big entrance hole (BEH) perforation was initiated for the current sand control optimization alternative by SCON chemical reduction with shorter perforation intervals; and for thru-tubing metal screen performance improvement by placement in front of perforation entrance tunnels with minimum erosion risk. BEH was then studied as it has never been used previously in Mahakam with thru-tubing applications. Simulation and pilot well trials were explored to ensure that a short penetration would not significantly impact reservoir delivery on SLA wells. Inflow performance relationship (IPR) analysis resulted in slight additional drawdown compared to the calculated drawdown using DP at 2.5 MMscfd as an average gas rate in current thru-tubing sand control, which was considered acceptable from the operating envelope perspective. In total, BEH perforation was executed on ten wells with reservoir permeability range from 220 millidarcy (mD) to an extreme case of 3000 mD. Various SCON treatments were injected at optimized perforation lengths by cutting chemical costs up to 60% with sand-free production at a particular parameter and chemical type. On the other hand, in the application using screens, evaluation was not conclusive due to screen sizing issues for some installations. However, in-situ gas velocity could be reduced to the theoretical erosion velocity limit for a metal screen. This new approach to BEH charges utilization has a potential solution optimizing current SCON costs while also reducing erosion risk for the through tubing screen application to improve its performance. By using short penetration of charges, this approach was successfully implemented without jeopardizing reservoir's deliverability.

Microscopic picture of the entrance hole of gunshot wounds

Forensic medical examination should always be based on incontestable provisions, proven by appropriate scientific development. In some cases, the scientific development of individual issues available to date turns out to be insufficient and we have to look for new evidence that will facilitate the exact resolution of the questions posed to the examination. This is the position now on the issue of gunshot injuries.

Nest Architecture and Animals Associated with Neoponera verenae (Forel) (Formicidae, Ponerinae)

The nests of ants Neoponera have chambers that can also be occupied by other species of organisms that can be tenants, visitors or prey. However, few studies have considered the assemblage of the associated species and described their composition. This study aimed to describe the architecture and catalog the visitors and prey species found in Neoponera verenae nests. Talcum powder was pumped inside eight nests to mark the chambers and tunnels. The nests were then excavated to describe the architecture and obtain measurements of chambers. The associated species encountered in the nests were collected and identified allowing us to obtain new records of visiting (Linepithema sp., cryptodesmid millipedes and Neotropacarus sp.) and prey taxa (membracids, apid bees and springtails) of N. verenae. Generally, nests had a single entrance hole and a depth of up to 42 cm. Nest chambers were found with three basic forms, elliptical, hangers and boot. Although studies show that this species can occupy abandoned nests of leaf-cutting ants, we found that the nests of N. verenae were more similar to those of Ectatomma ants. Indeed, we found one of the N. verenae nests was attached to a Ectatomma edentatum nest, leading us to suggest that N. verenae may occupy abandoned nests or displace other ants to occupy them.

Transmediastinal Gunshot Wound in a Pregnant Patient with Stable Hemodynamics

Transmediastinal gunshot wounds (TGWs) may lead to life-threatening injuries of vital organs such as large vessels, the esophagus, and lungs. Although they are not commonly encountered in pregnant women, additional caution should be given to these patients. Physical examination for the diagnosis and the choice of treatment modality contain controversial points in hemodynamically stable patients, and resuscitation has excessive importance due to physiological changes in pregnancy. We present a hemodynamically stable 26-week pregnant woman brought to the emergency department for TGW. She had a 1-cm diameter of bullet entrance hole on the right anterior 4th intercostal space, 2 cm lateral to the sternum, and a 3-cm diameter exit hole on the right posterior 12th intercostal space on the midscapular line. With our conservative approach, she had an uncomplicated pregnancy period, and gave birth to a healthy baby at term.

Morphology analysis of tracks in the aerogels impacted by hypervelocity irregular particles

As an attractive collector medium for hypervelocity particles, combined with outstanding physical properties and suitable compositional characteristics, SiO2 aerogel has been deployed on outer space missions and laser shock-loaded collection experiments. In this paper, impact experiments were conducted to understand the penetration process of irregular grains, irregular Al2O3 grains with two different sizes and speeds (~110 μm@7 km/s, ~251 μ[email protected] km/s) at various density silica aerogels. By classifying the shapes of projectile residues and tracks, the morphology of tracks was analyzed. It was observed that there were several kinds of typical tracks in the penetration of irregular grains, accompanied by residues with the shapes of near-sphere, polyhedron, streamlined body wedge, and rotator. The rotational behavior was demonstrated by the final status of one flake projectile as direct evidence. In addition, there was no obvious relationship between the track length and experimental parameters, which may be caused by the uncertain interaction between aerogels and irregular particles. In addition, it confirmed the existence of fragmentation, melting situation by observing the shape of the impact entrance hole. At the same time, optical coherence tomography was used to observe the detail of tracks clearly, which provided a method to characterize the tracks nondestructively.