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Experimental studies of chronic noise exposure in modern urban life testified about oxidative stress due to the corresponding hormones effects leading to accumulation of reactive oxygen species and endothelial dysfunction. This study aims to evaluate the protective effect of α2-adrenoblockers to modulate oxidative stress and corticosterone levels due to chronic noise exposure. To achieve this, we examined the effects of beditin (2-aminothiozolyl-1,4-benzodioxane) and mesedin (2-(2-methyl-amino-thiozolyl)-1,4-benzodioxane hydrochloride), along with changes in corticosterone, Ca2 + content, and morphological alterations in various tissues under noise-induced stress. Beyond this, detection of immune-reactivity and proliferation of Galarmin-containing cells in adrenals, and isolation of the total fractions of superoxide-producing associate from the rat liver under noise exposure and the beditin and mesedin actions on them were pertinent. Experiments were provided on the albino female rats divided into four groups: (1) control, (2) noise-exposed, (3) noise-exposed and beditin-injected (2 mg/kg, i.p.), and (4) noise-exposed and mesedin-injected (10 mg/kg, i.p.) animals. The noise exposure was of 91 dBA noise on 60 days with a daily duration of 8 h. For the first time, the total fractions of superoxide-containing associates were separated from the cell membranes of the rat liver tissue under the chronic noise stress conditions and the regulative effects of the α2-adrenoblockers. Increased 45Ca2+ and decreased corticosterone levels in the mentioned tissues, as well as dystrophic changes, were observed under the chronic noise exposure. Prominently, α2-adrenoblockers showed antioxidant effects, modulating pathological shifts of the noise-induced stress. [ABSTRACT FROM AUTHOR]

Maze tasks, originally developed in animal research, have become a popular method for studying human cognition, particularly with the advent of virtual reality. However, these experiments frequently rely on simplified environments and tasks, which may not accurately reflect the complexity of real-world situations. Our pilot study aims to transfer a multi-alternative maze with a complex task structure, previously demonstrated to be useful in studying animal cognition, to studying human spatial cognition. The challenges to be resolved at this stage included developing a virtual maze and selecting an appropriate instruction that will elicit processes similar to those observed in animal models. A virtual maze was developed, and two types of instructions were provided to the participants: (1) to collect coins; (2) to interact with the maze in order to draw its structure after the game. The results indicate that a more structured instruction with a clear attainable goal (“collect”) prompted more in-depth exploration and engagement with the key elements of the maze, eliciting processes similar to those of animals. While the maze demonstrates promise as a tool for comparative studies, it also has the potential to uncover different aspects of human cognition. [ABSTRACT FROM AUTHOR]

Antiphospholipid syndrome (APS) is associated with recurrent pregnancy morbidity, yet the underlying mechanisms remain elusive. We performed multifaceted characterization of the biological and transcriptomic signatures of mouse placenta and uterine natural killer (uNK) cells in APS. Histological analysis of APS placentas unveiled placental abnormalities, including disturbed angiogenesis, occasional necrotic areas, fibrin deposition, and nucleated red blood cell enrichment. Analyses of APS placentas showed a reduced cell proliferation, lower protein content and thinning of endothelial cells. Disturbances in APS trophoblast cells were linked to a cell cycle shift in cytotrophoblast cells, and a reduced number of spiral artery-associated trophoblast giant cells (SpA-TGC). Transcriptomic profiling of placental tissue highlighted disruptions in cell cycle regulation with notable downregulation of genes involved in developmental or signaling processes. Cellular senescence, metabolic and p53-related pathways were also enriched, suggesting potential mechanisms underlying placental dysfunction in APS. Thrombotic events, though occasionally detected, appeared to have no significant impact on the overall pathological changes. The increased number of dysfunctional uNK cells was not associated with enhanced cytotoxic capabilities. Transcriptomic data corroborated these findings, showing prominent suppression of NK cell secretory capacity and cytokine signaling pathways. Our study highlights the multifactorial nature of APS-associated placental pathologies, which involve disrupted angiogenesis, cell cycle regulation, and NK cell functionality. [ABSTRACT FROM AUTHOR]

This paper presents the results of studying the structural features and physical properties of two-component composites (1-x)PbFe12O19–xPbTiO3, obtained from pre-synthesized and mechanically activated powders. To control the physical properties of composites, in addition to changing the dopant (PbTiO3) concentration within the range of 0.2–0.8 in steps of 0.2, the method of mechanical activation (nanostructuring) was used. This method implies that the Bridgman anvils simultaneously apply a compressive force to the powder placed between them and produce a shear deformation by rotating the lower anvil. X-ray diffraction revealed a sharp decrease in the unit cell parameters of the dopant of the initial composition at x = 0.4, followed by a similarly sharp leap in the parameters of the hexagonal cell after mechanical activation. The dimensions of the coherent scattering regions (D) of the PbFe12O19 component after mechanical activation decreased by more than a half, while the dislocation density (ρD) and the magnitude of microstrains (ε) increased by more than an order of magnitude. It was found that the magnetic phase transition temperature of composites decreases by about 14 °C with increasing dopant concentration, and the nanostructuring of composites leads to a further decrease in the transition temperature by another 12–36 °C, depending on the dopant concentration. The band gap Eg of the nanostructured compositions increases by approximately 0.3 eV regardless of the dopant concentration. Using the impedance spectroscopy method, it has been discovered that the dependence of the grain capacitance Cg(T) in the temperature range of 150–350 °C has a bell-shaped form, which is explained in terms of Maxwell–Wagner polarization, where the relaxation is of the non-Debye type. [ABSTRACT FROM AUTHOR]

The paper presents studies on the correctness of the application of the simplified Boer formula for estimating the components of the angular velocity vector of the spacecraft using the example of the small ISOI spacecraft (SXC3-219). The simplification consists in neglecting the total derivative of the induction vector of the Earth's magnetic field in time compared to the local derivative. This is due to the fact that measurements are carried out quite often. Therefore, the magnetic induction vector in two adjacent dimensions can be considered unchanged. The aim of the work is to estimate the error in determining the angular velocity due to this simplification. The presented results show the admissibility of neglecting the full derivative, provided that the measurement frequency is sufficient. Reference metrological tests were carried out, in which a gyroscopic angular velocity vector meter was selected as the reference measuring instrument. The errors in the estimates of micro-accelerations and the control moment, which are a consequence of the error in determining the angular velocity, are calculated. [ABSTRACT FROM AUTHOR]

The human primase-polymerase PrimPol is a key participant of the mechanism of DNA synthesis restart during replication fork stalling at sites of DNA damage. PrimPol has DNA primase activity and synthesizes DNA primers that are used by processive DNA polymerases to continue replication. Recruitment of PrimPol to the sites of DNA damage, as well as stimulation of catalytic activity, depends on interaction with the replicative protein RPA, which binds single-stranded DNA. The C-terminal domain of PrimPol contains a negatively charged RPA-binding motif (RBM), mutations in which disrupt the interaction between two proteins. The RBM motif also plays a role in the negative regulation of PrimPol interaction with DNA. Deletion of the RBM dramatically increases PrimPol affinity to DNA and stimulates PrimPol activity. The mechanism of RBM-mediated regulation of PrimPol activity is unclear. The relatively strong negative charge of RBM potentially may contribute to the interaction of PrimPol with RPA and DNA. RBM contains two negatively charged regions RBM-A and RBM-B. In this work, we additionally added (substitution V546E) or decreased (substitution D547H) a negative charge in RBM-B PrimPol and characterized these mutant variants biochemically. It was shown that the local change in the RBM-B charge has no effect on the interaction of PrimPol with DNA and RPA, or of the catalytic activity of the enzyme. [ABSTRACT FROM AUTHOR]

A new tribe Twangsteini trib. nov. (Hymenoptera, Ichneumonidae, Pimplinae) including a new genus Twangste gen. nov. with a new species T. belokobylskiji sp. nov. is described from Late Eocene Baltic amber. The tribe Twangsteini is interpreted as an extinct, basal and at the same time strongly advanced phylogenetic lineage of Pimplinae. This inference is based on a number of characters in which it resembles the Mesozoic subfamily Labenopimplinae and a number of apomorphies and plesiomorphies. Morphological similarity with the extant "Polysphincta" group of genera is the basis for the assumption that Twangste developed as a parasitoid on adult spiders (Arachnida, Araneida) or in their egg cocoons, supposedly the primary biology for the Polysphincta genus group. [ABSTRACT FROM AUTHOR]

In problems of X-ray phase contrast in dynamic diffraction of a spherical wave, it is recommended to use a highly absorbing superlattice plate with a small period in the Laue geometry as an analyzer crystal. By choosing the value of the temperature gradient, it is proposed to focus all the satellites on the exit surface of the sample, guided by the lens formula for a crystalline medium. A method for recording reflexes without additional movement of the phase object is described. [ABSTRACT FROM AUTHOR]

We report on the high-resolution imaging and molecular dynamics simulations of a 3D-printed eutectic high-entropy alloy (EHEA) Ni40Co20Fe10Cr10Al18W2 consisting of nanolamellar BCC and FCC phases. The direct lattice imaging of 3D-printed samples shows the Kurdjumov–Sachs (K–S) orientation relation {111} FCC parallel to {110} BCC planes in the dual-phase lamellae. Unlike traditional iron and steels, this alloy shows an irreversible BCC-to-FCC phase transformation under high pressures. The nanolamellar morphology is maintained after pressure cycling to 30 GPa, and nano-diffraction studies show both layers to be in the FCC phase. The chemical compositions of the dual-phase lamellae after pressure recovery remain unchanged, suggesting a diffusion-less BCC–FCC transformation in this EHEA. The lattice imaging of the pressure-recovered sample does not show any specific orientation relation between the two resulting FCC phases, indicating that many grain orientations are produced during the BCC–FCC phase transformation. Molecular dynamics simulations on phase transformation in a nanolamellar BCC/FCC in K–S orientation show that phase transformation from BCC to FCC is completed under high pressures, and the FCC phase is retained on decompression aided by the stable interfaces. Our work elucidates the irreversible phase transformation under static compression, providing an understanding of the orientation relationships in 3-D printed EHEA under high pressures. [ABSTRACT FROM AUTHOR]

We report the synthesis of iron oxide nanoparticles using solution combustion synthesis, focusing on the controlled manipulation of material characteristics, such as particle size, phase composition, and magnetic properties, by applying external inert gas pressure. It was shown that variation of nitrogen gas pressure in the reactor in the range 0.1 to 1.1 MPa changed the time-temperature history of the process and resulted in the gradual change of phase composition of the fabricated materials along the FeO → FeO∙Fe2O3 → Fe2O3 route. The particle size varied in the 50–400 nm range, with a maximum for powder synthesized at a pressure of 0.25 MPa. For magnetic fluid hyperthermia, the critical parameter is specific loss power. It was demonstrated that this parameter can be optimized by gas pressure variation. The maximum specific loss power measured under conditions suitable for magnetic hyperthermia (magnetic field 33.5 mT and frequency 259.6 kHz) appears to be 174 W/g. The proposed innovative approach is an effective tool for controlling the synthesis of various nanoparticles with desired properties. Highlights: Inert gas pressure controls material's structure fabricated by solution combustion synthesis. A raise in gas pressure leads to a vary in phase composition along the FeO → Fe3O4 → Fe2O3 line. The particle size alters in 50–400 nm range with minimum for that made at a pressure of 1.1 MPa. The specific loss power under magnetic hyperthermia conditions was as high as 174 W/g. The innovative approach can be used for synthesis of various nanoparticles with desired properties. [ABSTRACT FROM AUTHOR]

One of the reasons of the development of pathologies causing death is hypoxia. The purposes of this study were (1) to study some physiological and biochemical mechanisms of α2-adrenoblockers, which ensure the tissue resistance increase to hypoxia; (2) to offer new drugs contributing to the increase of tissues' stability towards the hypoxic affection; and (3) to submit new medications to surpass by their anti-hypoxic activity of those already used in modern medicine and have some advantages. The reactivity of postsynaptic vascular α2-adrenoceptors was determined on the damaged spinal cord expressed by the blood pressure increase in response to intravenous administration of azepexole that selectively binds to α2-adrenoceptors. Determination of the systemic hemodynamic values and the vascular resistance to the blood flow was performed by the method with plastic microspheres of marked isotopes. pO2 in the blood and the oxygen-transporting function were determined in a sample of 0.1 ml of blood in 30, 90, and 180 min after the α2-adrenoblockers' injections. It has been found that one of the major hemodynamic effects of mesedin and beditin was an improvement in cardiac output, as well as a prolonged increase in coronary blood flow and vasodilation of the heart vessels. Some anti-hypoxic mechanisms of the studied α2-adrenoblockers are an improvement of blood oxygen-transporting function followed by tissue oxygenation and the increased level of corticosterone and resistance to hypoxia. Revealing the mechanisms of action of the postsynaptic α2-adrenoceptors suggests that mesedin and beditin are potentially effective therapeutic means for many hypoxic conditions. [ABSTRACT FROM AUTHOR]

A theoretical study of X-ray diffraction on a superlattice with overlapping stacking faults is carried out. Expressions for the X-ray reflection coefficient in the directions of satellites, depending on the wave's phase jump on the stacking faults and the depth of their occurrence are obtained. For comparison with an ideal superlattice, the relative change in the reflection coefficient is obtained. [ABSTRACT FROM AUTHOR]

An X-ray point source was used to examine the diffraction behavior of a low-angle twist boundary. It is shown that when radiation is focused inside a crystal, because of the dislocation structure of the defect wall, the vertical divergence can be reduced so much that the size of the focus in this direction is significantly smaller than in the horizontal direction. This circumstance can be used to create X-ray optical elements. [ABSTRACT FROM AUTHOR]

The results of numerical modeling of thermal processes in locally inclined targets made of pressed molybdenum powder with holders of titanium and copper are presented. The simulation was conducted to determine the suitability of such targets for irradiation with high-intensity proton beams in the "Nirta Solid Compact Model TS06" target module for producing the medical radioisotope Tc-99m. Calculations were carried out using the Fluid Flow (Fluent) engineering package of the ANSYS Workbench software platform on models of targets with axially symmetric corrugations in the irradiation zone. It is shown that the target temperature decreases on locally inclined targets with titanium and copper holders due to corrugation. On targets with copper holders, it is also possible to increase the maximum irradiation current by 1.5 times compared to standard flat targets, comparable with previously obtained results for targets with niobium holders. It has been established that on locally inclined targets with titanium holders, corrugation does not provide a practically significant increase in the maximum irradiation current due to the low thermal conductivity of titanium. [ABSTRACT FROM AUTHOR]

The purpose of this prospective pilot study was to evaluate the feasibility and effects of cognitive-motor intervention on the cognitive and motor abilities of pediatric survivors of posterior fossa tumors. The study involved patients aged 7 to 18 years with cognitive deficits who had completed primary treatment for posterior fossa tumors. 25 participants (Mage=11.3 ± 2.93, 64% male; 17 medulloblastoma, 1 ependymoma, 1 desmoplastic medulloblastoma, 6 piloid astrocytoma; 22 in remission (Mmonths =45), 3 in stabilization (Mmonths=49)) were recruited from the Research Institute for Brain Development and Peak Performance. The intervention consisted of two phases with a 3-month break for home training, and a total duration of 6 months. Each phase lasted 7 weeks and included two assessment procedures (pre- and post-intervention) and 10 training sessions over a period of 5 weeks (two 3-hour sessions per week). At baseline and pre- and post-intervention, all participants underwent a battery of cognitive and motor tests. Each training session included gross motor training (GMT), graphomotor training (GT), and cognitive-motor training (CMT). Statistical analysis was performed using the Friedman test for repeated measures and post-hoc Durbin-Conover test. The results indicated significant improvements in visuospatial working memory, visual attention, eye-hand coordination, semantic verbal fluency, auditory-motor synchronization, reaction time, and a decrease in the rate of ataxia. These improvements remained stable even in the absence of direct intervention. The findings demonstrate positive effects and feasibility of the intervention and suggest the need for further research in this area including randomized controlled feasibility studies with a larger sample. [ABSTRACT FROM AUTHOR]

The peculiarity of conjugation of β-adrenoreactivity of erythrocyte membranes (β-ARM) as an indicator of the state of autonomic regulation of the cardiovascular system with other clinical and laboratory indicators in drug-resistant arterial hypertension (RAH) with the absence and presence of type 2 diabetes mellitus (T2DM) was investigated. It was shown that patients with RAH, regardless of the presence of T2DM, were characterized by reduced adrenoreactivity, while the β-ARM index of erythrocytes was more than 2 times higher than the reference values. The intergroup difference in the mean values of β-ARM of erythrocytes and the frequency of cases of this indicator exceeding the established reference values did not have significant differences. In RAH, regardless of the presence of T2DM, the β-ARM index of erythrocytes is statistically significantly coupled with blood pressure variability, the volume of daily diuresis, and increased contractile capacity of the left ventricle. In addition, in the presence of T2DM, the association of β-ARM with an increase in left ventricular elastance, heart rate variability, and duration of arterial hypertension and T2DM was revealed. Thus, with the development of RAH in humans, the β-ARM indicator can be a new biomarker for personalized assessment of the activity of autonomic regulation of the cardiovascular system. T2DM expands the conjugacy of β-ARM with clinical and laboratory parameters. [ABSTRACT FROM AUTHOR]

The energy pathways of possible decomposition and isomerization reactions of iso-propyl (i-C3H7) and n-propyl (n-C3H7) radicals are studied by computational methods of quantum chemistry. The B3LYP, M062X, MP2, and CBS-QB3 methods are used to localize stationary points on the potential energy surface of a system containing propyl radicals. A number of intermediate compounds formed during the isomerization and decomposition of propyl radicals are identified and information is obtained on their structure and thermochemical parameters. Based on the results of the research, a diagram of the energy levels of the system under consideration is constructed. [ABSTRACT FROM AUTHOR]

Locally inclined targets are developed to produce medical radioisotopes which can be used for high-intensity proton beam irradiation. The results of a numerical analysis of thermal processes in locally inclined targets made of pressed molybdenum powder with a niobium target holder for the Nirta Solid Compact Model TS06 target module are presented. Computations were carried out using the Fluid Flow (Fluent) engineering package of the ANSYS Workbench 18.2 software platform for variants of targets with linear and axially symmetric grooves in the proton irradiation zone. It has been shown that using various models of locally inclined targets with a cooling area increased by 2.37 times, it is possible to increase the irradiation current by 1.34–1.46 times compared to a standard flat target. An analysis of the distribution of heat flows and temperatures in the targets was also carried out. [ABSTRACT FROM AUTHOR]

Purpose: Central nervous system (CNS) tumors are the most common solid malignancies in children worldwide, including in Armenia. The current study aims to analyze epidemiological data, treatment, and outcomes of children and young adults (≤25 years) with CNS tumors in Armenia during the last 26 years. Methods: We collected data from pediatric and young adult patients treated in selected sites in Armenia from 1st January 1995 to 31st December 2020. Incidence by sex, age at diagnosis, time from first complaints to diagnosis, histopathology results, treatment strategies, complications, and overall survival (OS) rates were calculated. Results: The multicenter data analysis revealed 149 patients with diagnosed primary CNS tumors over 26 years. Among them, 84 (56.4%) were male. The median age at diagnosis was 7 years (range, 3 months to 25 years), and the median time from the first complaints to diagnosis was 2 months (range, 1 week to 70 months). Medulloblastomas and other embryonal tumors (47), low-grade gliomas (32), and high-grade gliomas (22) were the most commonly diagnosed malignancies. Ependymomas, craniopharyngiomas, germ cell tumors, and other malignancies were observed in 22 patients. For 26 patients, no histopathological or radiological diagnosis was available. Follow-up information was available for 98 (65.8%) patients. The 5-year OS rate for the whole study group was 67.7%. Conclusion: Consistent with international data, embryonal tumors, and gliomas were the most commonly diagnosed CNS malignancies in Armenia. Multimodal treatment was often not available in Armenia during the study period, especially for early cases. [ABSTRACT FROM AUTHOR]

The study of the oxidation of propane-ethylene mixtures by numerical kinetic modeling allowed us to establish that in the range of 400–600°C with an increase in the conversion of propane with an increase in temperature, the selectivity of propylene formation passes through a maximum whose position depends on the concentration of ethylene in the initial mixture. The addition of ethylene to the initial mixture leads to a reduction in propane consumption and an increase in the selectivity of propylene formation. The conditions under which ethylene introduced into the initial mixture is not consumed during the process are determined; thus, formally it can be considered as a catalyst, and the process of propane oxidation as proceeding in a pseudo-catalytic regime. [ABSTRACT FROM AUTHOR]

A new method for obtaining ultrafine particles of cobalt ferrites is proposed. This synthesis is a two-step process: the first step is the synthesis of ultrafine particles from aqueous solutions of nitrates under the action of non-equilibrium low-temperature plasma. The second stage is high-temperature treatment of the resulting powders. The action of plasma on solutions of iron and cobalt nitrates leads to the formation of a colloidal suspension at the plasma-solution interface in the liquid anode. The kinetics of co-precipitation from solutions under the action of plasma has been studied. It is shown that the process of formation is complex, includes several stages. The rate of formation of particles directly depends on the concentration of iron nitrate in the initial mixture. An increase in the discharge current leads to an increase in the rate of particle formation. The obtained substances were studied immediately after the plasma-solution interaction, after centrifugation, and after high-temperature treatment. X-ray diffraction analysis showed that the resulting ultrafine particles are a mixture of hydroxonitrites and hydroxides of cobalt and iron. The data of thermogravimetric analysis confirm the data of X-ray diffraction analysis. The surface morphology was studied using a scanning electron microscope; the resulting powders have a well-developed surface. The resulting particles are characterized by two sizes, 92 nm and 1.46 μm. The magnetic characteristics of the particles were studied using a vibrating magnetometer at room temperature with a maximum applied field of up to 30 kOe. The coercive force of the obtained particles was 210 Oe. The saturation magnetization (MS) obtained at room temperature was found to be 65 emu/g and remanent magnetization (Mr) was 22 emu/g. [ABSTRACT FROM AUTHOR]

The introduction rates of electrically active radiation defects Δ N def / Δ Φ were studied as a function of 15.5 MeV energy proton radiation fluence Φ in n-type and p-type Si semiconductor crystals. The concentration of electrically active radiation defects N def was determined as the difference between the charge carrier concentration before n 0 and after n Φ irradiation, at room temperature. It was demonstrated that the concentration of electrically active radiation defects in silicon crystals produced by proton irradiation can be described by an empirical exponential function. The experimental results show that the introduction rate of electrically active radiation defects depends on the initial sample parameters, and during the initial phase of irradiation by protons it is significantly higher than that for 3.5 MeV energy electron irradiation. It was shown that samples with a low introduction rate of radiation defects are more resistant to the effects of particle irradiation. The charge carrier mobility in both n-type and p-type silicon crystals changes slightly as a result of proton irradiation, in contrast to the significant decreases observed under conditions of electron irradiation. In the case of proton irradiation, the resistivity of n-type and p-type silicon crystals increases exponentially with the level of radiation fluence. [ABSTRACT FROM AUTHOR]

Stress is one of the major contributing factors to the development of neurodegenerative diseases and mental disorders. These pathologies are reportedly characterized by progressive loss of neurons and impaired motor and cognitive functions. Changes in stress-induced mechanisms, such as oxidative stress (OS) with corresponding neurotransmitters' interplay are important for both, the mechanisms of defense and the progression of mental disorders. OS implies an imbalance in the pro-oxidant/antioxidant homeostasis resulting in the generation of aggressive radicals, reactive oxygen species (ROS), and exaggeration of neurodegenerative disease. However, in clinical trials, antioxidants such as alfa-tocopherol have not provided efficacious protection as an alternative therapy for neurodegenerative diseases. Norepinephrine (NE) is the main stress hormone capable of modulating the stress response and providing neuroprotection during neurodegeneration by limiting the production of ROS and stimulating the antioxidative defense, especially against the OH• radical. This in turn leads to the protection of cells from ROS-mediated damage and the improvement of cognitive and behavioral functions. Mounting evidence from preclinical studies in the last decade suggests the α2-adrenoblockers-mediated increase of NE release in the brain to be a promising therapeutic approach in neurodegenerative diseases. In this review, we focus on the role of (1) OS in neurodegenerative diseases; (2) the role of adrenergic receptors (ARs) in disease pathology and mechanisms of defense during neurodegeneration, and (3) the adrenergic signaling system in cognitive functions and neuroprotection provided by NE and α2-adrenoblockers. [ABSTRACT FROM AUTHOR]

This article provides data on the development and creation of a vacuum window module, which will bring out the proton beam of the C18 cyclotron (IBA, Belgium) with energy of 18 MeV from a vacuum environment into the atmosphere. The module is made of aluminum and consists of a flange with a collimator and a helium (He) chamber of foil plates cooling. The module was installed at the end of the cyclotron's beam line. Profile measurements were made for various current values of proton beam from 1 to 30 µA. The vacuum window showed its functionality. [ABSTRACT FROM AUTHOR]

The first known fossil representative of Darwin wasps (Ichneumonidae) of the subfamily Poemeniinae is described, from the Late Eocene Baltic amber; Amberpoemenia kirejtshuki gen. et sp. nov. The fossil genus Amberpoemenia occupies an isolated position in the subfamily, having features of specialization that are not typical of recent representatives of the subfamily Poemeniinae. [ABSTRACT FROM AUTHOR]

An approach to designing the structure of Eu2+-containing silicate glass-crystalline materials was implemented for the first time, using which a rare-earth activator is introduced into Ba-containing silicates formed during glass crystallization. Eu2+-activated fluorine-containing glasses and glass-ceramics in the MgO–BaO–ZrO2–SiO2 system were synthesized, and their crystal structure and luminescence properties were studied. It was shown that the simultaneous incorporation of Eu into several different silicate crystals formed during the crystallization of glasses yields a material with a broad luminescence band in the visible part of the spectrum. A study of the luminescence excitation and emission spectra of glass demonstrated the possibility of excitation energy transfer from Eu2+ ions to Eu3+ ions. The approach proposed for the first time to designing the structure of glass-crystalline materials is quite promising for the further creation of new optical media used in high-power light-emitting diodes. [ABSTRACT FROM AUTHOR]

Parkinson disease (PD) is a chronic progressive neurodegenerative disease characterized by both motor and non-motor features. Numerous risk factors (oxidative stress, free radical formation, and several environmental toxins) have been associated with PD. The experimental studies were carried out under in vivo conditions. Biochemical data analysis indicated that compared with the parameters of control (C) rats, rotenone-induced PD rats showed a significant decrease in the specific content of the total fraction of isoforms of O2−-producing, heat-stable, NADPH-containing associates (NLP-Nox) from membrane formations of tissues (brain, liver, lung, and small intestine). Compared with the C group indices, in the PD and PD + curcumin (PD + CU) groups there is some change in the shape of the optical absorption spectra of isoforms associated with a change in the amount of Nox in the isoform composition of the total fraction of the NLP-Nox associate. Thus, daily administration of CU (200 mg/kg, i.p.) to PD rats for 63 days had a regulatory effect, bringing the specific content and O2−-producing activity of the total fraction of NLP-Nox isoforms closer to the norm. CU has membrane-stabilizing effects in rotenone-induced PD. [ABSTRACT FROM AUTHOR]

The species Electrotoma kopylovi sp. nov. is described from a larva (prepupa) from the Upper Eocene Baltic amber. It is the second find of a fossil of the family Electrotomidae. The new species differs from the only known congeneric specimen, E. succini Rasnitsyn, 1977 in the closer placed antenna and stemma, less shortened clypeus, symmetrical labrum and denser chaetae on head and thorax. The composition of E. kopylovi syninclusions supports the previously stated hypothesis that a combination of unusual circumstances were required for electrotomids to be preserved in resin. [ABSTRACT FROM AUTHOR]

Improved thermal barrier coatings (TBCs) will enable future gas turbines to operate at higher gas temperatures. Considerable effort is being invested, in identifying new materials with even better performance than the current industry standard, yttrium stabilized zirconia (YSZ). TBCs are also supposed to be applied in spacecrafts as protective layer against heat. The operation of spacecrafts in cosmic conditions in turn suggests continuous irradiation with cosmic rays, particularly with MeV energy protons, electrons, and neutrons. Therefore, it is very important to investigate the behavior of such barrier coatings under irradiation conditions. In this work, we investigate the radiation resistance of TBCs based on silicate compounds obtained by a hydrothermal microwave method by using proton and neutron beam irradiation. For this purpose, zinc silicates and cerium-doped zinc silicates were irradiated with 18 MeV protons with doses 1013–1015 p/cm2 and neutrons with doses 1013, 1015 n/cm2. The diffuse reflectance measurements and X-ray diffraction analysis (XRD) of materials before and after irradiation indicated that the samples have high radiation resistance, and the samples maintain the crystalline structure. [ABSTRACT FROM AUTHOR]

The dimensional magnetic effects of single-domain Ni nanoparticles encapsulated by a carbon shell (Ni@C nanocomposites) have been studied. The studied samples were obtained by solid-phase pyrolysis of solid solutions of nickel phthalocyanine (NiPc) and metal-free phthalocyanine (H2Pc): (NiPc)x(H2Pc)1 – x, where 0 ⩽ x ⩽ 1. The Ni concentration in the carbon matrix varied in the range of 0–12 wt %, the sizes of the average diameter of nanoparticles in different samples were from 4 to 40 nm. The paramagnetism of the surface and near-surface atoms of Ni nanoparticles, which is due to the charge transfer from the carbon matrix with the formation of Ni ions has been studied in detail. A method for determining the blocking temperature of superparamagnets in temperature measurements of the paramagnetic susceptibility in the case of high magnetic fields is considered. The magnetic characteristics, which reflect size effects in SQUID magnetometry and FMR, exhibit "anomalous" deviations in the range of ultrasmall particles. These are high values of the blocking temperature, high values of the coercive force, and the ferromagnetic resonance linewidth, as well as a significant shift of the effective g-factor in the FMR spectra. Generalizing equations are presented that include the contributions of the surface magnetic anisotropy along with the bulk magnetocrystalline anisotropy, which is consistent with the experimental results over the entire investigated range from 4 to 40 nm. It is shown that the parameters of the total magnetic resonance spectra (FMR + ESR) are caused by the ferromagnetism of the core of nickel nanoparticles and the paramagnetism of surface and near-surface Ni ions, as well as π-electrons of the organic matrix. A general diagram of the dependence of the coercive force on particle sizes for temperatures lower than the blocking temperature (T < Tb) is also presented. [ABSTRACT FROM AUTHOR]

A new species, Crusopimpla klopfsteinae sp. nov. (Hymenoptera, Ichneumonidae, Pimplinae) is described from Upper Eocene Baltic amber. This is the first reliable finding of Darwin wasps of the subfamily Pimplinae in Baltic amber. The systematic position of Pimpla succini Giebel, 1856, the previously described species from Baltic amber as a taxon of uncertain systematic status (Ichneumonoidea incertae sedis) is established. The diagnosis of the genus Crusopimpla, previously known from impression fossils from the Tadushi Formation (early Eocene), is amended. Finding of a representative of the subfamily Pimplinae confirms that Baltic amber is an extremely selective oryctocenosis that only approximately reflects the true biological situation. The studied fauna is shown to have broader connections with other fossil localities than previously assumed. [ABSTRACT FROM AUTHOR]

Endoprosthetic replacement of the ankle joint, particularly in cases of tumors of the tibia, is a quite rare and complex operation. The few designs of imported prostheses are accompanied by a significant number of postoperative complications associated with aseptic instability of the components and dislocations in the prosthetic joint. We propose an original design for a revision endoprosthesis for the ankle joint, which improves the results of endoprosthesis replacement. This article outlines the basic principles of the algorithm for designing personalized ankle joint endoprostheses. [ABSTRACT FROM AUTHOR]

The reaction of arylmethylidenecyanoacetic esters with N-arylamides of malonic acid led to the formation of previously unknown diethyl 6-amino-1,4-diaryl-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxylates in 15–83% yields. Antibacterial activity of some obtained compounds was studied. [ABSTRACT FROM AUTHOR]

In order to study the potential energy surfaces (PESs) of systems containing ethylene, hydrogen, and oxygen atoms, quantum chemical calculations are carried out using the hybrid B3LYP method of the density functional theory (DFT) and the composite CBS-QB3 method. An enthalpy diagram reflecting the PES of this reaction system is constructed. It is shown that the addition of a hydrogen atom to ethylene with the formation of an ethyl radical occurs through the formation of a van der Waals complex. The diagram of enthalpies of monomolecular reactions of decomposition and isomerization of the ethoxyl radical is presented in detail, and a conclusion is made about the probability of their occurrence. The global PES minimum of the system describing the sequential addition of hydrogen and oxygen atoms to ethylene is the hydroxyethyl radical. Intermediates CHCH2OH and CH2OCH2 are localized on the PES of the C2H4 + O system and possible pathways for their further transformation are analyzed. The data obtained make it possible to estimate the ranking of individual elementary reactions in the processes of combustion and oxidation of hydrocarbons and the probabilities of various directions for the transformation of chemical species in the studied systems. [ABSTRACT FROM AUTHOR]

In this work, the influence of simultaneous action of high pressure and shear deformation (mechanical activation) on the physical properties of synthesized YbFeO3 was studied using complex methods. The formation of crystalline structures of YbFeO3 powders with different concentrations of structural defects was carried out using Bridgman anvils. It was found that during mechanical activation, the tilting angles of FeO6 oxygen octahedra change within the range θ = 12.69–28.45°. Using X-ray diffraction, it was established that the linear unit cell parameters a, b and c change in a consistent manner with changing mechanical activation pressure, while the space-group symmetry D 2 h 16 –Pbnm is preserved. The sizes of the coherent scattering regions (D) decrease by more than 90% at the maximum mechanical activation pressure (1200 MPa). It was found that the mechanical activation pressures of YbFeO3 have a threshold value (800 MPa), above which the dislocation density decreases. According to the results of impedance spectroscopy, the nature of relaxation was found to be non-Debye and the activation energy increased from 0.649 eV for the starting sample to 1.395 eV for the sample mechanically activated sample at 1 GPa. The magnetization curves M(H) were described using the law of approach to magnetic saturation (LAS), and the critical crystallite size (Dcr) was determined to be 50 nm, at which the maximum Hc is observed. The behaviors of the spectroscopic splitting factor (g) and half-width (ΔH) of the electron paramagnetic resonance (EPR) spectrum are analogous to Hc and Mr, however, the maximum ΔH is observed in the range of 50–105 nm, and the g-factor reaches its maximum at particle sizes of 105 nm. [ABSTRACT FROM AUTHOR]

We propose in this paper a method for the synthesis of α-WC powder by the method of electric spark discharge, where WC–8% Co (anode) and W (cathode) are used as electrode materials, and deionized water is used as a dielectric liquid. The synthesized powder was subjected to thermal annealing after drying in an air atmosphere at temperatures of 250, 400, and 600°C for 2 h in order to analyze its thermal stability and identify possible temperature-dependent phase transitions. The phase composition, morphology, and particle sizes of the synthesized powder and powders subjected to thermal annealing were studied by powder X-ray diffraction and scanning electron microscopy. The synthesized powder contained two phases: the dominant α-WC phase and the α-W2C phase. Both α-WC and α-W2C phases almost completely transformed into the CoWO4 phase at an annealing temperature of 600°C. The processes of formation of the phase components of the synthesized powder and the transition of these components to the CoWO4 phase as a result of thermal annealing are discussed. [ABSTRACT FROM AUTHOR]

The effect of electron irradiation on the optical properties of thermoregulating coatings from zinc silicate was studied. Samples were obtained by hydrothermal microwave (HTMW) synthesis. Methods of spectroscopic and structural analysis were used to study the radiation resistance, the relationship between the structures and characteristics of materials. The results of scanning electron microscopy, photoluminescence, diffuse reflection and absorption coefficients showed that coatings based on Ce–Zn2SiO4 have a high radiation resistance compared to pure Zn2SiO4. [ABSTRACT FROM AUTHOR]

Neurons are overproduced during cerebral cortical development. Neural progenitor cells (NPCs) divide rapidly and incur frequent DNA double-strand breaks (DSBs) throughout cortical neurogenesis. Although half of the neurons born during neurodevelopment die, many neurons with inaccurate DNA repair survive leading to brain somatic mosaicism. Recurrent DNA DSBs during neurodevelopment are associated with both gene expression level and gene length. We used imaging flow cytometry and a genome-wide DNA DSB capture approach to quantify and map DNA DSBs during human induced pluripotent stem cell (hiPSC)-based neurogenesis. Reduced p53 signaling was brought about by knockdown (p53KD); p53KD led to elevated DNA DSB burden in neurons that was associated with gene expression level but not gene length in neural progenitor cells (NPCs). Furthermore, DNA DSBs incurred from transcriptional, but not replicative, stress lead to p53 activation in neurotypical NPCs. In p53KD NPCs, DNA DSBs accumulate at transcription start sites of genes that are associated with neurological and psychiatric disorders. These findings add to a growing understanding of how neuronal genome dynamics are engaged by high transcriptional or replicative burden during neurodevelopment. [ABSTRACT FROM AUTHOR]

Noise as an environmental stressor becomes of increasing importance in our industrialized world, and especially traffic noise from the environment represents a potential novel neurodegenerative risk factor, as well as for hearing loss. A significant number of studies have been suggested that the overproduction of reactive oxygen species (ROS) has a complex role in stimulation of pathologic events. Experimental studies upon molecular pathways of traffic noise exposure proposed that it increased the level of stress hormones and mediated the inflammatory and oxidative stress (OS) pathways resulting in endothelial and neuronal dysfunction. Studies have shown that neurons are especially sensitive to OS due to high polyunsaturated fatty acids content in membranes, high oxygen uptake, and weak antioxidant defense. However, OS induces the necrotic and apoptotic cell deaths in the cochlea. Chronic noise is one of the many overall reasons of obtained sensorineural hearing loss which destroys cognitive functions in human and animals, as well as suppresses neurogenesis in the hippocampus. Nevertheless, behavioral disorders caused by noise are mainly accompanied with oxidative stress, but the clear molecular mechanism of neurodegeneration due to disruption of the pro- and antioxidant systems is still not fully understood. This paper aims to highlight the down-stream pathophysiology of noise-induced mental disorders, including hearing loss, annoyance, anxiety, depression, memory loss, and Alzheimer's disease, describing the underlying mechanisms of induction of inflammation and oxidative stress. [ABSTRACT FROM AUTHOR]

Molecular subtypes of small cell lung cancer (SCLC) defined by the expression of key transcription regulators have recently been proposed in cell lines and limited number of primary tumors. The clinical and biological implications of neuroendocrine (NE) subtypes in metastatic SCLC, and the extent to which they vary within and between patient tumors and in patient-derived models is not known. We integrate histology, transcriptome, exome, and treatment outcomes of SCLC from a range of metastatic sites, revealing complex intra- and intertumoral heterogeneity of NE differentiation. Transcriptomic analysis confirms previously described subtypes based on ASCL1, NEUROD1, POU2F3, YAP1, and ATOH1 expression, and reveal a clinical subtype with hybrid NE and non-NE phenotypes, marked by chemotherapy-resistance and exceedingly poor outcomes. NE tumors are more likely to have RB1, NOTCH, and chromatin modifier gene mutations, upregulation of DNA damage response genes, and are more likely to respond to replication stress targeted therapies. In contrast, patients preferentially benefited from immunotherapy if their tumors were non-NE. Transcriptional phenotypes strongly skew towards the NE state in patient-derived model systems, an observation that was confirmed in paired patient-matched tumors and xenografts. We provide a framework that unifies transcriptomic and genomic dimensions of metastatic SCLC. The marked differences in transcriptional diversity between patient tumors and model systems are likely to have implications in development of novel therapeutic agents. Molecular subtypes of small cell lung cancer characterized by neuroendocrine differentiation have been described in cell lines and primary tumors. The clinical implications of neuroendocrine subtypes in metastatic and relapsed tumors, and the extent to which the subtype distribution is recapitulated in patient-derived models remains unclear. Here, the authors integrated genomics and transcriptomics on 100 small cell cancers from a range of metastatic sites finding complex intra- and intertumoral heterogeneity, notably not recapitulated in patient-derived model systems, and distinct therapeutic vulnerabilities associated with neuroendocrine subtypes. [ABSTRACT FROM AUTHOR]

In this work, the structure and physical properties of (1 − x)(CoFe2O4) − x(PbTiO3) compositions, synthesized by the solid-phase method, were studied for the first time using complex methods. It was found that the solid-phase sintering of the inverse spinel CoFe2O4 (CFO) and the ferroelectric PbTiO3 (PTO) is frequently accompanied by the formation of additional phases—hexaferrite PbFe12O19 (PFO) and solid solutions, which were identified by X-ray diffraction, energy-dispersive X-ray analysis, and Raman spectroscopy. The dependencies of the unit cell parameters of the main components and additional phases on the concentration of PTO were studied at room temperature. The concentration interval (x = 0.3–0.7) with extreme values of structural parameters and non-monotonic changes of the physical properties was discovered. Complex quantities such as dielectric permittivity ɛ*(ω) and electric modulus M*(ω) were studied over a wide range of frequencies and temperatures using dielectric spectroscopy. The polarization switching kinetics of (1 − x)(CFO) − x(PTO) compositions were studied, and the saturated ferroelectric hysteresis loops P(E) with maximum spontaneous polarization Ps equal to 132 μC/cm2 were obtained for the first time. The bandgap Eg was determined by optical absorption spectroscopy at room temperature; Eg varies depending on the PTO concentration in the range 2.11–2.57 eV. The dynamic properties of the compositions were studied by Fourier transform infrared spectrometer (FTIR) and Raman spectroscopy. The Raman modes corresponding to PFO are well detected starting from compositions 0.3(CFO)–0.7(PTO). [ABSTRACT FROM AUTHOR]

This paper was the first to present the results of studying the influence of structural defects on the physical properties of pre-synthesized ytterbium iron garnet (YbIG). The concentration and type of structural defects were controlled by mechanically activating the powders using Bridgman anvils. Using scanning electron microscopy and X-ray diffraction (XRD), it was revealed that the particle morphology, the unit cell parameters, mean size of the coherent scattering regions (D ) and microstrains ( Δ d / d ) vary in a wide range. Using optical spectroscopy, XRD and FTIR to study the dynamic properties of the crystal lattice, showing that the bandgap and force constants of dodecahedral-coordinated ytterbium (Yb–O)d and octahedral-coordinated iron (Fe–O)o change non-monotonically with decreasing crystallite size. By analyzing the dependence of the magnetic hysteresis loop M (H) on the crystallite size D , it was concluded that there was a critical crystallite size ( D crit = 75 nm) of YbIG, at which the coercive force H c has a maximum value. For the first time, changes in g-factor and the half-width Δ H of the electron paramagnetic resonance (EPR) spectra of nanoscale crystallites were found to be correlated with the parameters of the magnetic hysteresis loop M (H) . [ABSTRACT FROM AUTHOR]

Rotenone is involved in the degeneration of dopaminergic neurons, and curcumin may prevent or effectively slow the progression of Parkinson's disease (PD). Previous research has shown that the naturally occurring phenolic compound curcumin can reduce inflammation and oxidation, making it a potential therapeutic agent for neurodegenerative diseases. The present study involves investigation of rotenone-induced histological changes in the brain area, hippocampus using Nissl staining after 35 day of subcutaneous injection of rotenone in adult male rats. We sought to determine whether curcumin could protect against rotenone-induced dopaminergic neurotoxicity in a rat model by in vivo electrical recording from Substantia nigra pars compacta (SNc). Curcumin treatment significantly improved electrical activity of neurons in the SNc of rotenone-induced PD model rats. The pattern of histological alterations corresponds with electrophysiological manifestations. [ABSTRACT FROM AUTHOR]

The paper describes the formation of a solid phase in aqueous solutions of potassium permanganate under the action of a direct current discharge in air above the liquid phase at atmospheric pressure. The discharge current was 40 mA (the total input power was 6 W). The discharge was ignited in the system without contact of the electrodes with the liquid phase. Assumptions were made about considerable difference between the mechanisms of reactions induced by the discharge and reactions that take place in solutions of transition metal salts under the same conditions. The obtained solid product was investigated by X-ray diffraction analysis and thermogravimetric analysis and by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Ni@C nanocomposites in a graphite-like carbon matrix and cobalt nanoparticles in carbon nanotubes were obtained by solid-phase pyrolysis of nickel phthalocyanine (NiC32N8H16) and cobalt phthalocyanine (CoC32N8H16). The metal concentrations in the carbon matrix in both cases in Ni/C and Co/C are the same—12 wt %. The structure and morphology of the obtained samples were studied by high-resolution scanning and transmission electron microscopy as well as X-ray diffraction. The capacitive and resistive characteristics of the obtained Ni/C and Co/C compounds as an electrode material for supercapacitors (SC) have been investigated. The specific capacitances measured by cyclic voltammetry are 12 F/g and 8 F/g for Ni/C and Co/C samples, respectively. The synthesized compounds can become a promising electrode material for super capacitors with an electrolyte solution of H2SO4. [ABSTRACT FROM AUTHOR]

The magnetic and some physicochemical properties of glasses based on barium-borosilicate eutectic doped with iron and lithium oxides were studied. The magnetic permeability increases with increasing content of Fe2O3. The character of magnetic permeability remains unchanged when Fe2O3 and Li2O are introduced simultaneously. The formation of structural motifs of barium hexaferrite in glass is responsible for magnetic properties. According to EPR data, some iron ions are present in tetrahedral coordination, incorporating into the structural mesh of the glass, and the others in octahedral coordination, acting as a modifier. [ABSTRACT FROM AUTHOR]

In neurodegenerative diseases, mainly in Parkinson's disease (PD), neurodegeneration involves antinociceptive centers, which is accompanied by persistent pain not relieved by opioids. In this study, in three experimental series carried out on 13 white mongrel rats, we analyzed the impulse activity of 390 single neurons of the raphe magnus nucleus (RMG) elicited by high-frequency stimulation (HFS) of the periaqueductal gray matter (PAG) under normal conditions, in the rotenone model of PD, and under conditions of hydrocortisone protection. Based on the programmatic mathematical analyses of the degree of manifestation of the average frequency of post-stimulus depressor and excitatory synaptic effects, a sharp increase in the tetanic and post-tetanic excitatory effects was revealed in the PD model. At the same time, there was a multiple decrease in the number of neurons responding with depressor synaptic reactions, and with an increase in those, responding with excitatory reactions. This effect was due to excessive excitability, attesting to a well-known compensatory increase in the excitability of the preserved RMG neurons, accompanied by their inevitable degenerative damage. After hydrocortisone exposure, the depressor synaptic reactions increased drastically with a significant increase in the number of the neurons involved, indicating a neutralization of the excitatory reactions that resulted in their natural decay. Considering the protective role of depressor reactions that we found previously, the analogous effect of hydrocortisone is quite evident. Moreover, on the PD model, RMG neurons during HFS of the PAG exhibited a pronounced (3- and 5-fold) increase in the pre-stimulus frequency of activity that preceded the depressor post-stimulus synaptic reactions. Hydrocortisone protection led to a significant (7- and 9-fold) reduction in the frequency of pre-stimulus impulse activity that preceded excitatory post-stimulus manifestations of activity, clearly arguing in favor of the protective effect of hydrocortisone. In the PD model, the post-stimulus frequency of RMG neuronal activity, accompanied by excitatory synaptic effects, far (7–5-fold and more) exceeded the norm, also attesting to a huge increase in the excitability of neurons. Under hydrocortisone protection, there was a sharp (18.3- and 17.7-fold) reduction in the post-stimulus frequency of impulse activity in RMG neurons in the PD model, accompanied by the excitatory post-stimulus effects. The data obtained herein demonstrate a pronounced protective effect of hydrocortisone due to increased inhibitory synaptic effects. [ABSTRACT FROM AUTHOR]

We performed a comparative study of the colony-forming ability and the number of residual foci of DNA repair proteins in cultured human lung fibroblasts (MRC-5 cell line) after exposure to subpicosecond beams of accelerated electrons with an energy of 3.6 MeV and quasi-continuous radiation (accelerated electrons with an energy of 4 MeV and X-rays). The yield of damages causing reproductive cell death after pulsed subpicosecond radiation exposure was higher by ~1.8 times than after quasi-continuous radiation exposure. The quantitative yield of residual γH2AX foci (phosphorylated H2AX histone, a protein marker of DNA double breaks) in cells irradiated with subpicosecond beams of accelerated electrons was shown to be ~2.0- 2.5-fold higher than in cells irradiated with quasi-continuous beams of accelerated electrons. [ABSTRACT FROM AUTHOR]

The paper presents the results of the first experiments on measuring the horizontal and vertical profiles of the proton beam of the C18 cyclotron using a profiling station based on vibrating wire monitors. The measurements were performed at the proton beam exit into the air from a special vacuum window located at the end of the cyclotron beam guide. The profiles were measured for different values of proton beam current. The station showed its operability under the conditions of strong disturbances caused by the exposure of protective lead plates to the proton beam. [ABSTRACT FROM AUTHOR]

In free-space optical communications that use both amplitude and phase data modulation (for example, in quadrature amplitude modulation (QAM)), the data are typically recovered by mixing a Gaussian local oscillator with a received Gaussian data beam. However, atmospheric turbulence can induce power coupling from the transmitted Gaussian mode to higher-order modes, resulting in a significantly degraded mixing efficiency and system performance. Here, we use a pilot-assisted self-coherent detection approach to overcome this problem. Specifically, we transmit both a Gaussian data beam and a frequency-offset Gaussian pilot tone beam such that both beams experience similar turbulence and modal coupling. Subsequently, a photodetector mixes all corresponding pairs of the beams' modes. During mixing, a conjugate of the turbulence-induced modal coupling is generated and compensates the modal coupling experienced by the data, and thus the corresponding modes of the pilot and data mix efficiently. We demonstrate a 12 Gbit s−1 16-QAM polarization-multiplexed free-space optical link that is resistant to turbulence. A transmission scheme for free-space optical communications is shown to be highly robust against turbulence. [ABSTRACT FROM AUTHOR]