Influence of Protective Gas Content on Quality of Welded Joint While Welding With Impulse Supply of Electrode Wire

Currently one of the advanced ways of obtaining quality welded joint while welding of medium alloy martensitic-bainitic steel is the one with impulse supply of electrode wire in gas mixture Ar(70%±3%)+СО2(30%±3%). Results of experimental studies proved that application of protective gas Ar(70%±3%)+СО2(30%±3%) in comparison with СО2(100%) enables to increase strength properties of the welded joint by 10-15% and enlarge the transitioncoefficient of chemical elements

Revision Anterior Cruciate Ligament Reconstruction: Current Approaches to Preoperative Planning (Systematic Review)

Background. The number of primary anterior cruciate ligament (ACL) reconstructions increases every year, which causes an increase in revision interventions due to ACL graft failure. When studying the literature, we identify many factors that together influence the outcome of revision ACL reconstruction, but are not always taken into account by surgeons. Aim of the review — is to perform a systematic review of studies that evaluated the outcomes of revision anterior cruciate ligament reconstructions and to identify optimal solutions to the most common problems encountered in preoperative planning. Methods. Information search was performed in the eLIBRARY, PubMed, and Scopus databases for the period from 2013 to 2022. Studies describing the main aspects of revision ACL reconstruction were selected for analysis. Inclusion criteria were the following: mean patient follow-up period of no less than 12 months, number of observations of no less than 10 cases. After evaluation of 898 articles, 22 articles were included in the systematic review. Results. Five main factors that should be taken into account in preoperative planning of revision ACL reconstruction have been identified: choice of the graft, necessity of reconstruction of the anterolateral complex, correction of tibial plateau deformity in the sagittal plane, determination of indications for one- or two-stage intervention, method of bone defect replacement in two-stage surgical treatment. Conclusion. The patient’s autogenous tissues should be preferred when choosing a graft. Correction of excessive anteroposterior tibial plateau inclination angle is performed only at the second revision intervention if the inclination angle exceeds 12º. Reconstruction of the anterolateral complex should be performed in young, active patients who are involved in pivot sports and in case of severe anterior instability. When determining the possibility of performing revision ACL reconstruction in one or two stages, the canal diameter is not a crucial parameter, as it is necessary to take into account the possibility of fusion of the canals from the previous surgery with the newly created ones. If the canals have correct entry points, one-stage revision reconstruction can be performed with the canal width not exceeding 10 mm and depending on the expected diameter and type of the prepared tendon graft. Bone grafting of the secondary dilated canals in two-stage intervention can be carried out using any material, but allogenous bone or synthetic grafts have certain advantages

Bone Regeneration in the Application of a New Device for Osteosynthesis in the Experiment

Background. Treatment of residual cavities after radical surgery for bone diseases is a vital problem of modern traumatology. Currently, there is an active search for devices both for osteosynthesis and bone-substituting masses. Aims. The purpose of this work was to test a new device for osteosynthesis. It can be used both for fixing bone fragments, and for studying the morphological features of bone regenerate in experiment.Materials and methods. A device for bone osteosynthesis of tubular bones in an experiment (Patent of the Russian Federation N 20116121487) was applied. The device consisted of two half-bushings, fastened to each other by a fierce clamp. Polypropylene was used as the material for the half-bushings, therefore no immunological reactions were observed. On the inner surface there were silicone cylinders, which directed pressure on the fragments and did not disturb the nutrition of the periosteum. The experiment was performed on Wistar rats. The surgical defect of the femur was filled with hydroxyapatite. Two groups of animals were identified. The bone in the first group was fixed by the device. The wire cerclage was used in the second group.Results. The study showed that the developed device does not disturb the nutrition of the periosteum, and also tightly fixes the osteoplastic material in the bone defect. Histological examination showed that bone regeneration was faster when the device was used. On the 21st day of the experiment, the regenerate filled the defect in the control group by 62 %, and in the experimental group by 73 %. The regenerate was represented by a woven bone. In all animals, bone regenerate formed a strong osteo-integrative connection with the maternal bone. In both groups, it looked like a mature bone tissue at the end of the experiment (28 days).Conclusion. The data indicate that the device does not disturb the processes of bone formation and allows for more efficient use osteoplastic material

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Nucleotide Weight Matrices Reveal Ubiquitous Mutational Footprints of AID/APOBEC Deaminases in Human Cancer Genomes.

Cancer genomes accumulate nucleotide sequence variations that number in the tens of thousands per genome. A prominent fraction of these mutations is thought to arise as a consequence of the off-target activity of DNA/RNA editing cytosine deaminases. These enzymes, collectively called activation induced deaminase (AID)/APOBECs, deaminate cytosines located within defined DNA sequence contexts. The resulting changes of the original C:G pair in these contexts (mutational signatures) provide indirect evidence for the participation of specific cytosine deaminases in a given cancer type. The conventional method used for the analysis of mutable motifs is the consensus approach. Here, for the first time, we have adopted the frequently used weight matrix (sequence profile) approach for the analysis of mutagenesis and provide evidence for this method being a more precise descriptor of mutations than the sequence consensus approach. We confirm that while mutational footprints of APOBEC1, APOBEC3A, APOBEC3B, and APOBEC3G are prominent in many cancers, mutable motifs characteristic of the action of the humoral immune response somatic hypermutation enzyme, AID, are the most widespread feature of somatic mutation spectra attributable to deaminases in cancer genomes. Overall, the weight matrix approach reveals that somatic mutations are significantly associated with at least one AID/APOBEC mutable motif in all studied cancers

Polymorphism in a Cobalt-Based Single-Ion Magnet Tuning Its Barrier to Magnetization Relaxation

A large barrier to magnetization reversal, a signature of a good single-molecule magnet (SMM), strongly depends on the structural environment of a paramagnetic metal ion. In a crystalline state, where SMM properties are usually measured, this environment is influenced by crystal packing, which may be different for the same chemical compound, as in polymorphs. Here we show that polymorphism can dramatically change the magnetic behavior of an SMM even with a very rigid coordination geometry. For a cobalt­(II) clathrochelate, it results in an increase of the effective barrier from 109 to 180 cm^–1, the latter value being the largest one reported to date for cobalt-based SMMs. Our finding thus highlights the importance of identifying possible polymorphic phases in search of new, even more efficient SMMs

Chloride Ion-Aided Self-Assembly of Pseudoclathrochelate Metal Tris-pyrazoloximates

Chloride ion-aided one-pot template self-assembly of a mixed pyrazoloxime ligand with phenylboronic acid on a corresponding metal­(II) ion as a matrix afforded the first boron-capped zinc, cobalt, iron, and manganese pseudoclathrochelate tris-pyrazoloximates. The presence of a pseudocross-linking hydrogen-bonded chloride ion is critical for their formation, as the same chloride-capped complexes were isolated even in the presence of large excesses of bromide and iodide ions. As revealed by X-ray diffraction, all complexes are capped with a chloride ion via three N–H···Cl hydrogen bonds that stabilize their pseudomacrobicyclic frameworks. The MN₆ coordination polyhedra possess a distorted trigonal prismatic geometry, with the distortion angles φ between their nonequivalent N₃ bases of approximately 0°. Temperature dependences of the effective magnetic moment for the paramagnetic complexes showed the encapsulated metal­(II) ions to be in a high-spin state in the temperature range of 2–300 K. In the case of the iron­(II) pseudoclathrochelate, density functional theory (DFT) and time-dependent DFT calculations were used to assess its spin state as well as the ⁵⁷Fe Mössbauer and UV–vis–NIR parameters. Cyclic voltammetry studies performed for these pseudomacrobicyclic complexes showed them to undergo irreversible or quasi-reversible metal-localized oxidations and reductions. As no changes are observed in the presence of a substantial excess of bromide ion, no anion-exchange reaction occurs, and thus the pseudoclathrochelates have a high affinity toward chloride anions in solution