Some features of the fabrication of multilayer fiber composites by explosive welding

The fabrication of multilayer fiber composites by explosive welding is characterized by intense plastic deformation of the matrix material as it fills the spaces between fibers and by high velocity of the collision between matrix layers due to acceleration in the channels between fibers. The plastic deformation of the matrix layers and fiber-matrix friction provide mechanical and thermal activation of the contact surfaces, which contributes to the formation of a bond. An important feature of the process is that the fiber-matrix adhesion strength can be varied over a wide range by varying the parameters of impulsive loading

On the Fermionic Frequencies of Circular Strings

We revisit the semiclassical computation of the fluctuation spectrum around different circular string solutions in AdS_5xS^5 and AdS_4xCP^3, starting from the Green-Schwarz action. It has been known that the results for these frequencies obtained from the algebraic curve and from the worldsheet computations sometimes do not agree. In particular, different methods give different results for the half-integer shifts in the mode numbers of the frequencies. We find that these discrepancies can be removed if one carefully takes into account the transition matrices in the spin bundle over the target space.Comment: 13 pages, 1 figur

Activity of the right cardiac ventricle and metabolism in healthy persons during an orthostatic test after short term immobilization

A 15 minute orthostatic test was performed on healthy male volunteers under conditions of catheterization of the right ventricle of the heart and the radial (or brachial) artery before and after 5 day bedrest in an antiorthostatic position of the body (with the foot of the bed raised 4.5 degrees). The change to a vertical position after immobilization was attended by a more marked increase in the rate of cardiac contractions, an increase of max dp/dt pressure in the right ventricle, and a decrease of cardiac and stroke indices. The decrease of the cardiac index was compensated for, to a certain measure, by a further increase in the extraction and utilization of O2 by the tissues. The arterial blood pH did not change essentially, while the decrease in pCO2 and content of standard bicarbonate was more marked

Exact computation of one-loop correction to energy of pulsating strings in AdS_5 x S^5

In the present paper, which is a sequel to arXiv:1001:4018, we compute the one-loop correction to the energy of pulsating string solutions in AdS_5 x S^5. We show that, as for rigid spinning string elliptic solutions, the fluctuation operators for pulsating solutions can be also put into the single-gap Lame' form. A novel aspect of pulsating solutions is that the one-loop correction to their energy is expressed in terms of the stability angles of the quadratic fluctuation operators. We explicitly study the "short string" limit of the corresponding one-loop energies, demonstrating a certain universality of the form of the energy of "small" semiclassical strings. Our results may help to shed light on the structure of strong-coupling expansion of anomalous dimensions of dual gauge theory operators.Comment: 49 pages; v2: appendix F and note about antiperiodic fermions added, typos corrected, references adde

Single and Double Bundle Arthroscopic Reconstruction of Anterior Cruciate Ligament (Review of Literature)

Researches performed in the past 20 years show the necessity of the restoration of anatomic position of anterior cruciate ligament as the main stabilizing structure of the joint in combination with the restoration of other injured elements and correction of deformities, which affect the outcomes of the treatment.Complexity of the restoration of anatomic position of torn anterior cruciate ligament is caused by its wide area of contact in combination with relatively small sectional area through the joint cavity. More detailed study of topographic anatomy of anterior cruciate ligament allowed the researchers to explain this phenomenon, which pushed them closer to the solution of the problem.Systemic anatomy of anterior cruciate ligament include two bundles - anteromedial bundle and posterolateral bundle. Double bundle plasty of anterior cruciate ligament restored anatomy to its nearly normal condition, but single bundle plasty is used much more often because of its simpler technique. However, the researchers still cannot reach a consensus in the choosing of single or double beam plasty at the restoration of anterior cruciate ligament

Comparative Determination of the Mechanical Strength of a Transplant from a Tendon of a Semitendinosus Muscle for Plastic Surgery of the Anterior Cruciate Ligament Prepared in Various Ways (Experimental Study)

According to modern literature, a sufficient number of studies have been carried out to determine the mechanical strength of transplants from the tendon of the semitendinous and gracilis muscles, the autologous ligament of the patella, the broad fascia, peroneus longus tendon, each of which has unique characteristics, but at present, transplants prepared by original (new) methods are understudied.In the period from November 5 to December 17,2018 we conducted an experimental study to determine the mechanical strength of a transplant from a tendon of a semitendinosus muscle taken from cadaveric material. The transplants were prepared by original and well-known (Graft-Link technique) methods.The experimental study was approved by the Ethics committee of Irkutsk Scientific Center of Surgery and Traumatology. The material for the study was prepared on the basis of the Irkutsk Regional Bureau of Forensic Medical Examination.After sampling the cadaveric material being studied, the main stages of the experimental study were carried out at the materials resistance department of the Irkutsk State Technical University. Studies of the mechanical properties of the transplant were carried out on a Shimadzu testing machine registered in the State Register of Measuring Instruments and approved for use in the Russian Federation.As a result of the study, we obtained the following data. The mechanical strength of the graft obtained from the tendon of the semitendinosus muscle in an original way is on average 607.8 ± 101.2 N/mm. The mechanical strength of the graft obtained from the tendon of the semitendinosus muscle in a traditional manner (Graft-Link technique) is on average 351.8 ± 133.0 N/ mm

Estimation of the effectiveness of surgical treatment of patients with old rupture of heel tendon with short plaster splint immobilization

Heel tendon injuries is the most common trauma of tendomuscular apparatus. Old ruptures of heel tendon occur in 58 % of cases in humans. The aim of the research was to estimate the effectiveness of treatment of the patients with old ruptures of heel tendon with Myerson type III defects who had tendon reconstruction on Chernavsky and short plaster splint immobilization of lower extremity for 4 weeks. We operated 10 patients using reconstruction on Chernavsky in our clinic from 2012 to 2014 (average age - 47,6 ± 12,0 years, 8 males and 2 females). All patients had old ruptures of heel tendon. Average time from the moment of trauma till the operation was 112,6 ± 80,4 days. Diastasis between the ends of tendon was 5,8 ± 0,7 cm that corresponds to Myerson type 111. Average term of staying at hospital was 10 ± 2 days. We didn't register any complications in postoperative period. Term of plaster immobilization of the operated extremity was 4 weeks. AOFAS score was 34,2 ± 6,8 points at the control examination in 1,5 months that corresponds to bad functional result. We registered good functional results (88,6 ± 3,5 points) in 3 months. 1n 6 months, functional results were 95,9 ± 1,6 points. 1n 12 months after the operation average score was 97,9 ± 2,1 points that corresponds to excellent functional result. Using heel tendon reconstruction on Chernavsky at the Myerson type 111 defects in combination with short plaster immobilization and early activization of patients allows to decrease term of rehabilitation of patients after the operation

Carbon Sequestration Dynamics in Urban-Adjacent Forests: A 50-Year Analysis

Achieving carbon neutrality is crucial for urban ecosystems. Forests growing near cities largely determine the state of the environment in urban areas. The aim of the present research is to assess the carbon productivity dynamics in forests near Krasnoyarsk (a large industrial center) over a 50-year period in terms of carbon sequestration and conservation. The study was based on forest inventory conducted in Karaul'noe Forestry in 1972, 1982, and 2002 and forest inventory covering six forest compartments in 2022. The forest covers 3980 ha and consists of 52 forest compartments. The analysis was based on the assessment of carbon productivity dynamics and followed four levels of principles: forestry, structure, forest compartment, and forest stand. The research was based on forest fund dynamics, analyzing methods, long-term forest inventory, assessing carbon stock, and growing stock dynamics. Pine is the dominant forest-forming species that absorbs the most carbon in the study area. Pine is long-lived, covers a vast area, and has the highest carbon sequestration potential. At the forest structure level, the predominant carbon pools are mid-late successional and late successional stands dominated by pine, birch, and aspen. Forest compartment-level analysis revealed three trends in carbon sequestration: carbon balance, a decrease in carbon sequestration, and an increase in carbon sequestration. Notably, the prevailing trend is determined by changes in carbon sequestration by dominant forest-forming species (pine). Forest stand-level analysis showed that stands have become more and more uneven-aged. About 65% of total carbon stock is concentrated in mid successional, mid-late successional and late-successional stands, and 35% in young stands. The carbon sequestration rate decreases in forests with age. However, pine forests increase biological productivity and continue to successfully sequester carbon. Deciduous forests have lost their carbon sequestration potential, and the area they occupy is currently decreasing in the study area. The development of the young generation in pine stands suggests that the carbon sequestration potential in forests growing near the city will not decrease and may even increase due to climate change. Doi: 10.28991/CEJ-2023-09-09-08 Full Text: PD

Comparative analysis of the results of the anterior cruciate ligament reconstruction using an autograft preparation by known and new methods

Background. To date, the problem of choosing the optimal graft for anterior cruciate ligament (ACL) reconstruction and the methods for its formation is one of the main trends in the surgical treatment of patients with anterior knee joint instability.The aim. To compare the results of the anterior cruciate ligament reconstruction using the known method and the new proposed method for autograft formation.Materials and methods. The results of treatment of ACL injury in 44 patients were assessed. In the main group (19 patients), an original technique of ACL reconstruction from 1/2 of the width of m. peroneus longus tendon was used. In the control group (25 patients), ACL reconstruction was performed using a graft from the m. semitendinosus tendon prepared by the Lubowitz method.Results. The mean difference in the circumference of the distal third of the hip in the main group was 1.57 ± 1.162 cm and was statistically significantly better than in the control group, where the mean difference in the hip circumference was 4.74 ± 1.7207 cm.The range of motion of the knee joint in the main group 3 months after the surgery was 128.42 ± 9.287°, and in the control group mean flection was 109.6 ± 9.120°.The functional results in the main group were assessed by the Lisholm scale and were statistically significantly better than the results in the control group. The functional results by the AOFAS (American Orthopedic Foot & Ankle Society) scale in the main group were 100 points before the surgery and at all terms after the surgery: this indicates that the use of 1/2 of the width of m. peroneus longus tendon does not cause the its functional impairement.Conclusion. Anterior cruciate ligament plasty with use of 1/2 of the width of m. peroneus longus tendon prepared by the proposed method showed statistically significantly better results compared to the preparation of autograft from semitendinous muscle tendon using known method