A key task nowadays is the development of novel materials and the enhancement of known ones in order to design high-performance anodes for sodium-ion batteries. This article presents a one-pot method of preparing a nanocomposite with hierarchical structure based on sodium trititanate and iron(III) oxide. In this method, simultaneous hydrothermal treatment of TiO2 and FeCl3 in a concentrated NaOH solution results in the formation of microscale particles self-assembled of Na2Ti3O7 nanotubes and Fe2O3 nanospheres. A Na2Ti3O7-Fe2O3 nanocomposite is being investigated for the first time as a potential anode material for sodium-ion batteries. It was found that combining Na2Ti3O7 with Fe2O3 as a high-capacitive modifier within the hierarchical structure improves Na-ion storage performance. Its specific capacity reaches about 220 and 50 mAh g-1 at 0.1C and 4 & Scy;, respectively. The pure Na2Ti3O7 gives only around 145 and 10 mAh g-1 at the same current densities. Besides, the Na2Ti3O7-Fe2O3 nanocomposite operates stably during 1000 charge/discharge cycles at a rate of 2C with a reversible capacity of 90 mAh g-1, whereas both pure Na2Ti3O7 and Fe2O3 exhibit worse long-term performance. These findings improve our knowledge of how to combine different materials in order to enhance their functionalities for application as an anode in sodium-ion batteries.

Strontium barium niobate SrxBa1 – xNb2O6 films, grown by plasma sputtering on layers of indium tin oxide and platinum on silicon and sapphire substrates, are investigated. Such materials are used in pyroelectric electro-optical converters of a new generation. A two orders of magnitude higher sensitivity to temperature change is detected in some of the investigated films compared to crystalline SrxBa1 – xNb2O6, the pyroelectric coefficient of which is γ 6 × 10−4 C/m2 K. The observed phenomenon is explained by the emergence of mobile elements in the “substrate–bottom electrode–ferroelectric–top electrode” system when the top electrode is detached from the ferroelectric. Leakage currents are unevenly distributed across the surface, often concentrated at local points or areas that can be considered one dimensional. It is known that the boundaries of ferroelectric domain walls exhibit abnormally high conductivity. In contrast to a tightly pressed electrode, where charge leakage may occur through it, in this structure, all the charge resulting from the change in spontaneous polarization during heating is transferred to the external circuit. This process occurs because the leakage-current points are local, and in the absence of a pressed electrode, the current flows along the surface.

Na2Ti3O7 has attracted attention as an alternative to hard carbon anode for Na-ion batteries due to suitable sodiation potential and, hence, no serious safety issues at high current densities. However, unfavorable electronic transport properties of Na2Ti3O7 need to be addressed to make it applicable for practice. Herein, a hydrothermal method was adopted to fabricate Na2Ti3O7 having a hierarchical micro/nano architecture and to dope it with copper through one stage. As compared to the non-doped Na2Ti3O7, the copper-containing product shows increased electronic conductivity (2.5 times higher) due to a smaller band gap (reduced by similar to 1 eV). Because of Cu-doping, the Na2Ti3O7 crystal structure has evolved, and its unit cell volume has increased by about 9.5 %. Doping with Cu enhances the electrochemical performance of Na2Ti3O7 in Na-ion batteries, which demonstrates higher rate capability (2.0-2.5 times more capacity at high current densities) and remarkable cycleability (85 % capacity retention over 300 cycles at 2C). The calculations show that Cu-doped Na2Ti3O7 is characterized by improved Na+ ion diffusion and increased contribution of the pseudocapacitive current during the sodiation-desodiation process. The research discloses the aspects of copper-doping strategy that enable to unfold the capability of Na2Ti3O7 for energy storage applications.

Sodium trititanate, Na2Ti3O7 is of interest as a negative electrode material for designing high-power and safe sodium-ion batteries due to the suitable potential of electrochemical sodium intercalation. Nevertheless, Na2Ti3O7 requires qualitative modification to improve its conductive properties, for example, doping with other elements or morphology optimization. Within the scope of this work, sodium trititanate doped with copper in various quantities, consisting of "microflowers" formed by nanotubes and nanosheets, was prepared via a one-stage hydrothermal treatment of titanium and copper salts in 10M sodium hydroxide solution. It was found that, in comparison with the undoped sample, the Cu-doped Na2Ti3O7 shows a narrowed band gap (by 1.1 eV) and increased electronic conductivity (by 2.5 times). The electrochemical insertion and extraction of Na+ + ions into copper-doped sodium trititanate were investigated. It was found that the specific capacity of doped Na2Ti3O7 at high current densities of 3C and 4C is 2.0-2.5 - 2.5 times higher as compared to the undoped sample. At low current densities (up to 0.5C), undoped and copper-doped Na2Ti3O7 samples have similar electrochemical performance. The kinetics of charge carriers in electrodes based on such materials in (de-)sodiation processes has been studied. It was shown that Cu-doped Na2Ti3O7 possesses a lower charge transfer resistance and higher Na+ + diffusion coefficient. This promotes a decrease in the polarization of the electrode during charge and discharge processes, providing increased specific capacity at high current loads.

В работе двухстадийным методом получен композиционный материал на основе волокон твердого углерода, модифицированных нанолистами дисульфида молибдена. Твердый углерод, используемый в качестве основы, получен термообработкой вискозы при 810 °С. Осаждение на волокнах наночастиц MoS2 выполнено гидротермальным способом. Структура и состав композита установлены с использованием методов рентгеновской дифракции, малоуглового рентгеновского рассеяния, спектроскопии комбинационного рассеяния света, сканирующей электронной микроскопии, энергодисперсионной спектроскопии, спектрофотометрии и рентгеновской фотоэлектронной спектроскопии. Исследованы электрохимические характеристики композита как анодного материала для натрий-ионных аккумуляторов. Обнаружено, что за счет эффекта синергизма композиционный материал обладает преимуществами над твердым углеродом и нанокристаллическим MoS2 в отдельности. По сравнению с твердым углеродом композит демонстрирует более высокие значения удельной емкости, в том числе при высоких плотностях тока. Так, при 1000 и 2000 мА/г композиционный материал показал удельную емкость 139 и 84 мА·ч/г, тогда как твердый углерод при тех же плотностях тока обеспечивает только 73 и 45 мА·ч/г. По отношению к MoS2 композит демонстрирует лучшую циклируемость. Для MoS2 наблюдается деградация энергозапасающих свойств уже после 90 цикла. Композиционный материал, напротив, сохраняет стабильность даже на 150 цикле с емкостью 204 мА·ч/г при 200 мА/г.

Because of the unique crystal framework, bronze TiO2 (or TiO2(B)) is considered the prospective choice for high-performance lithium-ion battery anodes. Nevertheless, TiO2(B) requires efficient modification, e.g., suitable doping with other elements, to improve the electronic properties and enhance the stability upon insertion/extraction of guest ions. However, due to the metastability of TiO2(B), doping is challenging. Herein, for the first time, TiO2(B) co-doped with Mn, F, and N were synthesized through a successive method based on a hydrothermal technique. The prepared doped TiO2(B) consists of ultrathin nanotubes (outer diameter of 10 nm, wall thickness of 2–3 nm) and exhibits a highly porous structure (pore volume of up to 1 cm3 g−1) with a large specific surface area near 200 m2 g−1. The incorporation of Mn, F, and N into TiO2(B) expands its crystal lattice and modifies its electronic structure. The band gap of TiO2(B) narrows from 3.14 to 2.18 eV upon Mn- and N-doping and electronic conductivity improves more than 40 times. Doping with fluorine improves the thermal stability of TiO2(B) and prevents its temperature-induced transformation into anatase. It was found that the diffusivity of Li is about two times faster in doped TiO2(B). These properties make Mn, F, and N co-doped TiO2(B) nanotubes promising for application as high-performance anodes in advanced lithium-ion batteries. In particular, it possesses a good reversible capacity (231.5 mAh g−1 after 100 cycles at 70 mA g−1) and prominent rate capability (134 mAh g−1 at 1500 mA g−1) in the half-cell configuration. The (Mn, F, N)-doped TiO2(B) possesses a remarkable low-temperature Li storage performance, keeping 70% of capacity at −20 °C and demonstrating potentialities to be employed in full-cell configuration with LiMn2O4 cathode delivering a reversible capacity of 123 and 79 mAh g−1 at 35 and 1500 mA g−1, respectively, at a voltage of ~2.5 V. This research underlies that regulation of electronic and crystal structure is desired to uncover capabilities of nanoparticulate TiO2(B) for electrochemical energy storage and conversion.

The gray-colored oxygen-deficient TiO2–δ(B) nanobelts have been synthesized through a combination of the hydrothermal method followed by an ion exchange process and vacuum annealing. Electron paramagnetic resonance reveals an existence of F-centers in the form of electron-trapped oxygen vacancies within the anionic sublattice of the gray bronze TiO2 that induces its colouration. The diffuse reflectance spectroscopy showed that the formation of oxygen vacancies into TiO2(B) significantly increases its absorption intensity in both visible and near infrared ranges. The band gap of TiO2(B) with anionic defects is equal to 3.03 eV (against 3.24 eV for white TiO2(B) treated in air). Room temperature ferromagnetism associated with the defects was detected in gray TiO2–δ(B), thus indicating it belongs it to the class of dilute magnetic oxide semiconductors. It was found that in the low-temperature range (4 K), the magnetic properties of vacuum annealed TiO2(B) do not differ from those for TiO2(B) treated in air. We hope that the findings are defined here make a contribution to further progress in fabrication and manufacturing of defective TiO2-based nanomaterials for catalysis, magnetic applications, batteries, etc.

Herein, a method for the preparation of hard carbon via carbonization of chemically modified (molybdenum-doped) commercially available viscose fiber was developed. The effects of a molybdenum dopant on carbonization conditions were studied. The carbonization products retained the fibrous structure and flexibility. The structural features of the synthesized hard carbon materials were investigated, and their relationships to the carbonization temperature and the amount of the molybdenum dopant were analyzed. The texture of materials was studied, and correlations between the specific surface area and porosity, on the one hand, and the synthesis conditions, on the other, were discovered. The usefulness of the products as anode materials for sodium-ion batteries was evaluated. The electrochemical tests, together the extant relevant data, indicate that molybdenum induces the structural rearrangement of the carbon framework upon annealing, accompanied by the growth and ordering of graphite-like nanoclusters. The material prepared at 1050°C exhibited the best electrochemical performances among the synthesized products and the stable cyclability with a capacity of 290 (mA h)/g at a current density of 25 mA/g.

To create microelectromechanical systems (MEMS) with a high specific mechanical power, a system ‘‘movable electrode–nanoscale gap–thin crystalline film made of a material with a high permittivity–immobile electrode’’ is used. It is shown that in this system, two-dimensional electromechanical wave emerge. The emergency of such excitations bounds the limit specific power of electromechanical transducer-actuators, MEMS engines and actuators. However, this phenomenon provides numerous possibilities of application of such structures.

Methods for determining the domain structure of thin ferroelectric films from the time dependence of the pyroelectric response to a short pulsed surface heating have been considered. The distribution of the pyroelectric coefficient by thickness has been found from the time dependence of the pyroelectric current by solving a Fredholm equation of the first kind. In the general case, this problem is ill-posed; however, it can be solved under additional assumptions about the form of the resolvent. The distribution of the pyroelectric coefficient by depth in a thin film of barium strontium niobate has been established under the assumption of a wedge-shaped domain.

A study is performed of the pyroelectric response of thin ferroelectric films of strontium barium niobate SrxBa1–xNb2O6 (SBN-x) when heated by a pulsed laser. It is shown that the distribution of the pyroelectric coefficient over the depth of a sample and the magnitude of spontaneous polarization can be determined from the response. Special attention is given to an SBN-50 film grown by plasma spraying on an indium–tin–oxide layer deposited on a sapphire substrate.

BACKGROUND:Persistence or recurrence of stenosis is a complication of initial coarctation repair. This study aims to report short-term outcomes of surgical management of recurrent coarctation and initial repair analysis.METHODS:We retrospectively reviewed our experience with 51 patients undergoing recoarctation surgical repair between 2008 and 2019 using antegrade cerebral perfusion (ACP) technique.RESULTS:Surgical correction included prosthetic patch aortoplasty in 23 (45%), resection with wide end-to-end anastomosis in 15 (29%), and a tube interposition graft in 13 (25%) patients. The median age at initial correction and reintervention was 12 months and 9 years. The median interval from primary repair to reintervention was 60 months. Initial repair analysis revealed 33% of patients had initial correction in the neonatal period, 72.5% of patients were done via a left thoracotomy approach and 63% of patients had end-to-end anastomosis at initial surgery.CONCLUSION:Our study demonstrates that surgical repair of recurrent coarctation of the aorta using ACP technique can be performed safely and with excellent results.

This clinical case report describes surgical management of a giant left ventricular fibroma and postoperative venoarterial extracorporeal membrane oxygenation support in a newborn male. Transthoracic echocardiography performed at 9-month follow-up showed an ejection fraction of 33% and a cardiac index of 4.5 liters per minute per square meter.

PURPOSE:Patients with Ebstein anomaly (EA) have a variety of clinical manifestation. The assessment of structural and geometric characteristics of the heart is important for optimal management.METHODS:We retrospectively analyzed echocardiography database from 2009 to 2020. We evaluate patients in two groups: patients with EA were in Group 1 and children without cardiovascular pathology were in Group 2. All children in both groups underwent echocardiography according to American Society of Echocardiography recommendations. The shape of the heart chambers and their function were studied in both groups.RESULTS:There were 153 in Group 1 and 2000 children without cardiovascular disease in Group 2. It was shown that in children with EA, the shape of the ventricle became less spherical, which was accompanied by a decrease in myocardial mass, and the ejection fraction was reduced 34% of patients. The functional volume (non-atrialized part) of the right ventricle in patients with EA was reduced, and its contractility was preserved in 62% of cases. Preservation of the contractile properties of the right ventricle in most cases was associated with higher systolic pressure in its cavity.CONCLUSION:TAPSE, TESV, and the velocity of the annulus fibrous ring movement according to tissue dopplerography in patients with EA do not allow us to assess the contractility of the right ventricle. The myocardial performance index (MPI) characterizes a decrease in the functional volume of the right ventricle.

Materials based on nickel- and zinc-doped TiO2(B), consisting of mesoporous nanorods, are produced via hydrothermal synthesis. Complementary methods are used to study the mechanism of doping and the physicochemical properties of the synthesized samples. According to the results of testing of materials in the cells of lithium- and sodium-ion batteries, it is found that the doping of TiO2(B) with nickel and zinc has a favorable effect.

Background:Development of tools, making for easier assessment of the age- and body size-specific echocardiographic parameters in the general population, becomes increasingly important.Materials and Methods:The application was developed on the basis of the previously designed model of normal values for basic echocardiographic parameters. The source population for the normal values was 10,604 apparently healthy people aged from 1 day to 65 years old, in which optimal visualization of the heart in the parasternal and apical echocardiographic views could be obtained. The whole population surveyed was categorized into three age groups. The predicted parameters were calculated by the group-specific regression equations. Deviation from the norm for one or another echocardiographic parameter was determined based on the value of z-score.Results:The mobile application was designed for the medical community and allows for a selective assessment of basic echocardiographic parameters in apparently healthy people with high accuracy. The application has a friendly graphical interface and provides color output on display of the results obtained.Discussion:The value of this application is in its uniqueness, since having analyzed available scientific works on mobile applications in medicine we could hardly find similar developments.Conclusions:Using the mobile application can save a doctor's time by simplifying the process of entering initial data, automating calculations, and providing convenient displaying of results. From this perspective, the application developed can become a useful tool in the sphere of telemedicine, in particular-the mobile medicine for remote consultation of patients.

Nickel- and zinc-doped TiO2(B) nanobelts were synthesized using a hydrothermal technique. It was found that the incorporation of 5 at.% Ni into bronze TiO2 expanded the unit cell by 4%. Furthermore, Ni dopant induced the 3d energy levels within TiO2(B) band structure and oxygen defects, narrowing the band gap from 3.28 eV (undoped) to 2.70 eV. Oppositely, Zn entered restrictedly into TiO2(B), but nonetheless, improves its electronic properties (Eg is narrowed to 3.21 eV). The conductivity of nickel- (2.24 × 10−8 S·cm−1) and zinc-containing (3.29 × 10−9 S·cm−1) TiO2(B) exceeds that of unmodified TiO2(B) (1.05 × 10−10 S·cm−1). When tested for electrochemical storage, nickel-doped mesoporous TiO2(B) nanobelts exhibited improved electrochemical performance. For lithium batteries, a reversible capacity of 173 mAh·g−1 was reached after 100 cycles at the current load of 50 mA·g−1, whereas, for unmodified and Zn-doped samples, around 140 and 151 mAh·g−1 was obtained. Moreover, Ni doping enhanced the rate capability of TiO2(B) nanobelts (104 mAh·g−1 at a current density of 1.8 A·g−1). In terms of sodium storage, nickel-doped TiO2(B) nanobelts exhibited improved cycling with a stabilized reversible capacity of 97 mAh·g−1 over 50 cycles at the current load of 35 mA·g−1.

A congenital left ventricular aneurysm is very rare. Clinical presentation varies from absence of symptoms to ventricular arrhythmias, heart failure or even sudden death. The optimal management is controversial and the surgical technique is not defined. A left ventricular aneurysm was diagnosed on prenatal echocardiography at 33 weeks gestation. After birth, initial transthoracic echocardiography confirmed the diagnosis. Two months later, the infant was taken to surgery for aneurysm repair using the Dor procedure with cardiopulmonary bypass. This technique eliminates the need for external prosthetic materials and produces a more physiologic left ventricular geometry. Transthoracic echocardiography performed at 6-month follow-up showed an ejection fraction of 66%.

В последние годы, стремительными темпами развивается целый ряд направлений промышленности, таких как гибридный и электрический автотранспорт, подводная робототехника, сфера бесперебойного энергообеспечения, прибрежная возобновляемая энергетика, и т.п., требующих от автономных накопителей энергии работы в жёстких условиях эксплуатации. Это диктует необходимость решения ряда задач, связанных с получением для них функциональных материалов с достаточно высокими удельными характеристиками, способностью стабильно и безопасно функционировать в широком температурном диапазоне и в условиях ускоренного заряда. В этой связи все больше внимания исследователями уделяется диоксиду титана. В рамках настоящего исследования получены наноленты диоксида титана со структурой бронз гидротермальным способом с использованием анатаза, состоящего из частиц различного размера. Обнаружено, что степень кристалличности и текстурные характеристики формирующегося TiO2-B определяются размером частиц и площадью поверхности стартового реагента. В свою очередь оба эти фактора оказывают значительное влияние на электрохимические характеристики бронзовой модификации TiO2: после 35 циклов заряда/разряда емкость составила 203 мА∙ч/г, а скорость деградации – 0,25% за цикл для материала, синтезированного из анатаза с размером частиц ~30 нм и площадью поверхности ~100 м2/г. В то же время образцы, полученные с использованием более крупных частиц, показывают худшие показатели емкости и циклируемости. Now, technology progress provides broad prerequisites for practical usage of batteries in the field of hybrid and electric vehicles, marine robotics, backup uninterruptible power supplies, coastal renewable energy sources, etc. with a more hard-working performance. This dictates the necessity of development an advanced electrode materials with a sufficiently high specific parameters, stability of operation and safely in a wide temperature range and under fast charge mode. In this way, a more attention has been paid to titanium dioxide. Herein, the titanium dioxide nanobelts with a bronze structure were obtained by the hydrothermal method using anatase with different particle size as a precursor. It was found that the degree of crystallinity and textural characteristics of as-formed TiO2-B are determined by the particle size and surface area of starting reagent. Both of these factors have a benefit effect on the electrochemical performance of TiO2-B: the capacity of 203 mA·h/g was registered after 35 charge/discharge cycles with a degradation of 0.25% per cycle for material synthesized from anatase with a particle size about ~30 nm (~100 m2/g). On the other hand, the samples prepared from a precursors with larger particles show the worst capacity and cyclability.