Mathematical modelling of the spatial network of bone implants obtained by 3D-prototyping

In this paper, the mathematical model suitable for bone implants 3D-prototyping is proposed. The composite material with the spatial configuration of reinforcement with matrix of hydroxyapatite and titanium alloys fibers is considered. An octahedral cell is chosen as an elementary volume. The distribution of reinforcing fibers is described by textural parameters. Textural parameters are integrated characteristics that summarize information on the direction of reinforcing fibers and their volume fractions. Textural parameters, properties of matrix and reinforcing fibers allow calculating effective physical and mechanical properties of the composite material. The impact of height and width of the octahedral reinforcement cells on textural parameters of the composite material is investigated in this work. The impact of radius of fibers is also analyzed. It is shown that the composite becomes quasi-isotropic under certain geometrical parameters of cell. © 2016 Author(s)

Feedbacks in Non-equilibrium Oxidative Plasma Reacting with Polyethylene

The experimental results on studies of loading effect at the action of a glow DC discharge in oxygen and air on polyethylene film are presented. At the increase in a polymer amount under a treatment the specific rates of etching and CO2, CO, H2O, H2 product formation rates are decreased. The gas temperature is changed slightly. The reduced electric field strength is increased in oxygen plasma and decreased in air plasma

Steam turbines produced by the Ural Turbine Works for combined-cycle plants

The most interesting and innovative solutions adopted in the projects of steam turbines for combined-cycle plants with capacities from 115 to 900 MW are pointed out. The development of some ideas and components from the first projects to subsequent ones is shown. © 2013 Pleiades Publishing, Ltd

A new approach to use of oral mucosa in reconstructive urethral surgery: micrografts

Introduction. Treatment of patients with complex urethral strictures is an actual problem of reconstructive urology. After multi-staged urethral surgery with multiple revisions the new reconstruction is limited by paucity of plastic material (for grafts and flaps). In-thing, new materials for urethral reconstruction (various auto, allo and xenografts) are still being developed in reconstructive urethral surgery.Purpose of the study. To study the possibility of using oral mucosa micrografts to form the urethral plate in the multi-stage surgery for patients with extended urethral strictures.Materials and methods. In the experimental study, male Wistar rats (22 individuals) weighing 300 – 400 g underwent a full-thickness skin wound after intramuscular sedation. We used the wound chamber (12 mm diameter) to exclude the wound contraction. The oral mucosa graft was harvested (6 mm in diameter). After pre-fabrication, the graft was minced to fragments < 1 mm2. Micrografts with fibrin-thrombin glue were applied to the wound. By day 45, the epithelial plate was excised for histological examination. In the clinical study, 4 patients with recurrent penile urethral strictures were treated with staged urethroplasty with urethral plate formation using oral mucosa micrografts. The average length of the stricture was 7.5 ± 1.2 cm (with extremely narrow and obliteration sites). The urethral plate was formed as the first stage. The preparation of the graft bed and oral mucosa grafts harvesting was carried out according to the standard procedure. Micrografts preparation and implantation was carried out as in experimental part of this study. After 6 months, neourethra tubularization was performed. The patients were evaluated every 3 months after the final stage of urethroplasty (uroflowmetry, ultrasound, X-ray, PROM-USS). The median follow-up was 9 months (3 – 18 months).Results. On day 15, in the experimental study, in 16 of 22 (72.7%) rats, the wound chambers had focal growth of the oral mucosa epithelium. On day 45, the wounds healed completely healed with oral mucosa. The final area of the plate was 78 ± 12 mm2. In the clinical study, 6 months after the first stage, all patients (n = 4) had a urethral plate covered with an oral mucosa epithelium without scar formation and sufficient for neurethra tubularization. All patients underwent urethral tubularization. After catheter removal, all men urinated. After 9 months (median follow-up, n = 3), the Qmax was 22.7 ± 4.2 ml/s, the post-void residual urine was 34.8 ± 2.2 ml, the total PROM-USS score was 7.4 ± 1.2, urethral lumen is preserved. All patients showed high satisfaction with the treatment.Conclusion. The oral mucosa micrografts showed good take in heterotopic transplantation (72.7%) with the formation of an epithelial layer on the wound surface. The final mucosal plate area 3 times exceeded the initial micrografts area. This initial clinical experience of using oral mucosa micrografts shows the new possibility of this technology in reconstructive urethral surgery, especially in patients with complex urethral strictures

Evolution of climate, glaciation and subglacial environments of Antarctica from the deep ice core and Lake Vostok water sample studies (Key results of implementation of the Russian Science Foundation project, 2014–2016)

Work on the project focused on the following five areas: 1)  field works in Antarctica at Vostok and Concordia stations; 2)  experimental and theoretical studies in the field of ice core and paleoclimate research; 3) experimental and theoretical works related to the exploration of subglacial Lake Vostok; 4) development of technology and drilling equipment for deep ice coring and exploration of subglacial lakes; 5) upgrading the analytical instrumentation in the Climate and Environmental Research Laboratory (CERL) of the Arctic and Antarctic Research Institute. The main achievements in the field of ice core and paleoclimate research include 1) further elaboration of a new method of ice core dating, which is based on the link between air content of ice and local insolation, 2) investigation of the possible applications of the 17O-excess measurements in ice core to the paleoclimate research, 3)  a better understanding of the mechanisms of the formation of relief-related variations in the isotopic content of an ice core drilled in the area of Antarctic megadunes, and 4) obtaining the first reliable data set on the variations of the 17O-excess in the Vostok core corresponding to marine isotope stage 11. As part of our studies of subglacial Lake Vostok, we have obtained a large body of new experimental data from the new ice core recovered from the 5G-3 borehole to the surface of the subglacial lake. Stacked profiles of isotopic composition, gas content and the size and orientation of the ice crystals in the lake ice have been composed from the data of three replicate cores from boreholes 5G-1, 5G-2 and 5G-3. The study reveals that the concentration of gases in the lake water beneath Vostok is unexpectedly low. A clear signature of the melt water in the surface layer of the lake, which is subject to refreezing on the icy ceiling of Lake Vostok, has been discerned in the three different properties of the accreted ice (the ice texture, the isotopic and gas content of the ice). These sets of data indicate in concert that poor mixing of the melt (and hydrothermal) water with the resident lake water and pronounced spatial and/or temporal variability of local hydrological conditions are likely to be the characteristics of the southern end of the lake. A considerable part of the funding allocated by the RSF to this project was used for upgrading the analytical instrumentation for ice core studies in the CERL of AARI. Using this grant, we purchased and started working with the Picarro L-2140i, a new-generation laser mass analyzer, and set the upgraded mass spectrometer Delta V Plus into operation. The new equipment was used to carry out research planned as part of the project, including the setting up and carrying out of new measurements of 17О in ice cores

Soft elasticity in biaxial smectic and smectic-C elastomers

Ideal (monodomain) smectic-$A$ elastomers crosslinked in the smectic-$A$ phase are simply uniaxial rubbers, provided deformations are small. From these materials smectic-$C$ elastomers are produced by a cooling through the smectic-$A$ to smectic-$C$ phase transition. At least in principle, biaxial smectic elastomers could also be produced via cooling from the smectic-$A$ to a biaxial smectic phase. These phase transitions, respectively from $D_{\infty h}$ to $C_{2h}$ and from $D_{\infty h}$ to $D_{2h}$ symmetry, spontaneously break the rotational symmetry in the smectic planes. We study the above transitions and the elasticity of the smectic-$C$ and biaxial phases in three different but related models: Landau-like phenomenological models as functions of the Cauchy--Saint-Laurent strain tensor for both the biaxial and the smectic-$C$ phases and a detailed model, including contributions from the elastic network, smectic layer compression, and smectic-$C$ tilt for the smectic-$C$ phase as a function of both strain and the $c$-director. We show that the emergent phases exhibit soft elasticity characterized by the vanishing of certain elastic moduli. We analyze in some detail the role of spontaneous symmetry breaking as the origin of soft elasticity and we discuss different manifestations of softness like the absence of restoring forces under certain shears and extensional strains.Comment: 26 pages, 6 figure

Tumor microenvironment: the formation of the immune profile

Tumor microenvironment (TME) is formed as a result of interaction and cross-linking between the tumor cell and different types of surrounding cells. Recent studies have shown that the tumor reprograms the microenvironment so that TME promotes the development of primary tumors, their metastasis and becomes an important regulator of oncogenesis. Under the influence of the tumor, the immune profile in the TME undergoes significant changes, “editing". An immunosuppressive network is formed, which suppresses the activity of the main effector of cellular immunity — T lymphocytes. T cells in TMA are in a state of anergy and exhaustion. T cells in TME are characterized by increased expression of inhibitory receptors, decreased secretion of cytokines and cytolytic activity. Blocking inhibitory receptors with specific antibodies can lead to the restoration of the functions of exausted T cells. Therefore, the restoration of the functional activity of T lymphocytes is one of the important strategies in cancer immunotherapy. The formation of the immune profile is influenced by genetic aberrations accumulating in the tumor. They play an important role in creating a specific, characteristic only for this tumor immune environment in the TME. Genetic changes in tumor cells lead to phenotypic and functional rearrangements of lymphocytes, which allows the tumor to escape the reaction of immune cells. Since many tumors occur after prolonged inflammation or exhibit characteristics of chronic inflammation as they progress, inflammation is considered an important factor in the formation of immune profile in TME. Immune infiltrates from different human tumors associated with inflammation may contain valuable prognostic and pathophysiological information. Macrophages in the TME now began to be regarded as descriptive marker and as a therapeutic target. One of the main mechanisms by which tumor cells reprogram surrounding cells is the release of exosomes — small vesicles that carry and deliver proteins and nucleic acids to other cells. When exosomal cargo is absorbed, molecular, transcriptional and translational changes occur in the recipient non-tumor cells in the TME. Therefore, tumor exosomes are an effective means by which the functions of immune cells in TME are purposefully changed. Thus, along with individual molecular and genomic testing of the tumor, attention should be paid to a deeper analysis of the immune profile of TME. It is a large resource of biomarkers and targets for immunotherapy

APPLICATION OF TEXTURE PARAMETERS TO CALCULATE THE EFFECTIVE MECHANICAL PROPERTIES OF POLYCRYSTALLINE AND TWO-PHASE COMPOSITE MATERIALS

In the Ural Federal University, samples are obtained by the method of 3D-printing based on the agglomeration of Ti powders under the preclinical study of osseointegration with the use of an innovative implant. This paper presents a technique for calculating texture parameters for a textured polycrystal and for a composite material with a spatial reinforcement scheme. Also it presents a comparison of elastic properties of materials exemplified by vectorial models characterizing the dependence of Young's modulus on direction and crystalline texture

Holocene hydrological variability of Lake Ladoga, northwest Russia, as inferred from diatom oxygen isotopes

This article presents a new comprehensive assessment of the Holocene hydrological variability of Lake Ladoga, northwest Russia. The reconstruction is based on oxygen isotopes of lacustrine diatom silica (δ18Odiatom) preserved in sediment core Co 1309, and is complemented by a diatom assemblage analysis and a survey of modern isotope hydrology. The data indicate that Lake Ladoga has existed as a freshwater reservoir since at least 10.8 cal. ka BP. The δ18Odiatom values range from +29.8 to +35.0‰, and relatively higher δ18Odiatom values around +34.7‰ between c. 7.1 and 5.7 cal. ka BP are considered to reflect the Holocene Thermal Maximum. A continuous depletion in δ18Odiatom since c. 6.1 cal. ka BP accelerates after c. 4 cal. ka BP, indicating Middle to Late Holocene cooling that culminates during the interval 0.8–0.2 cal. ka BP, corresponding to the Little Ice Age. Lake‐level rises result in lower δ18Odiatom values, whereas lower lake levels cause higher δ18Odiatom values. The diatom isotope record gives an indication for a rather early opening of the Neva River outflow at c. 4.4–4.0 cal. ka BP. Generally, overall high δ18Odiatom values around +33.5‰ characterize a persistent evaporative lake system throughout the Holocene. As the Lake Ladoga δ18Odiatom record is roughly in line with the 60°N summer insolation, a linkage to broader‐scale climate change is likely