New Thermoelectric Materials Based on Solid Solutions of Compounds Tl2Тe–PbTe–Bi2Тe3 System

Проведено дослідження характеру фізико-хімічної взаємодії на квазібінарних перерізах системи Tl2Тe−PbTe–Bi2Тe3, підібрано раціональні склади, технологічні умови й одержано зразки тернарних телуридів і твердих розчинів на їх основі, для яких вивчено фізико-хімічні та термоелектричні властивості. The physico-chemical interaction on the quasibinary sections of Tl2Тe–PbTe–Bi2Тe3 system have been investigated, the materials of ternary telluride’s and solid solutions on which based were growth, some physico-chemical and thermoelectric properties were establishe

Ventilation and outcomes following robotic-assisted abdominal surgery: an international, multicentre observational study

Background: International data on the epidemiology, ventilation practice, and outcomes in patients undergoing abdominal robotic-assisted surgery (RAS) are lacking. The aim of the study was to assess the incidence of postoperative pulmonary complications (PPCs), and to describe ventilator management after abdominal RAS. Methods: This was an international, multicentre, prospective study in 34 centres in nine countries. Patients ≥18 yr of age undergoing abdominal RAS were enrolled between April 2017 and March 2019. The Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score was used to stratify for higher risk of PPCs (≥26). The primary outcome was the incidence of PPCs. Secondary endpoints included the preoperative risk for PPCs and ventilator management. Results: Of 1167 subjects screened, 905 abdominal RAS patients were included. Overall, 590 (65.2%) patients were at increased risk for PPCs. Meanwhile, 172 (19%) patients sustained PPCs, which occurred more frequently in 132 (22.4%) patients at increased risk, compared with 40 (12.7%) patients at lower risk of PPCs (absolute risk difference: 12.2% [95% confidence intervals (CI), 6.8–17.6%]; P<0.001). Plateau and driving pressures were higher in patients at increased risk, compared with patients at low risk of PPCs, but no ventilatory variables were independently associated with increased occurrence of PPCs. Development of PPCs was associated with a longer hospital stay. Conclusions: One in five patients developed one or more PPCs (chiefly unplanned oxygen requirement), which was associated with a longer hospital stay. No ventilatory variables were independently associated with PPCs. Clinical trial registration: NCT02989415

Оптичні властивості плівок оксиду ванадію

Як типовий корельований електронний матеріал, діоксид ванадію VO2 демонструє перехід метал-діелектрик при відносно низькій температурі. При нагріванні відбувається перехід від діелектричної моноклінної фази до металевої тетрагональної фази (структура рутилу) з перегрупуванням іонів ванадію вздовж осі моноклінної гратки. Зміна фази відповідає колосальному падінню питомого опору більш ніж на чотири порядки, а також іншим змінам властивостей, які можуть бути оборотними через природний процес охолодження. Таким чином, VO2 привернув велику увагу при його застосуванні у високочутливих розумних пристроях, які можуть різко реагувати на різноманітні зовнішні впливи. В останні роки швидкий прогрес у виробництві та модуляції властивостей VO2 значно полегшив його застосування в багатьох аспектах, таких як термічне зондування, термохроміка, електроніка та механіка з множинним відгуком. Методом модуляційної поляриметрії досліджено оптичні властивості тонких плівок діоксиду ванадію. Для осадження тонкої плівки VO2 використовувався двоетапний метод. Плівки VO2 вирощували на підкладках з кварцового скла шляхом магнетронного розпилення мішені VO2 з подальшим термічним відпалом. Плівки мали різні модифікації складу, структури, морфології та оптичних властивостей, зумовлені технологією виготовлення. У роботі було виміряно кутові залежності коефіцієнтів відбивання електромагнітного випромінювання s- і pполяризацій і їх різницю для різних довжин хвиль. Поляризаційні характеристики були змодельовані за допомогою матричного перетворення формул Френеля. Значення показників заломлення та поглинання плівок були отримані з умови найкращого узгодження між експериментом і математичним моделюванням. Як стандартні аналітичні методи використовували атомно-силовий мікроскоп і рентгенівський дифракційний аналіз.As a typical Correlated Electron Material, vanadium dioxide was discovered to demonstrate metalinsulator transition at a relatively low temperature. The transition occurs from an insulating monoclinic phase to a metallic tetragonal phase (rutile structure) upon heating with the rearrangement of vanadium ions along an axis of the monoclinic lattice. The phase change corresponds to a colossal resistivity drop by over four orders of magnitude as well as other dramatic property changes, which can be reversible via a natural cooling process. Therefore, vanadium dioxide has attracted extensive attention for its applications in highly sensitive smart devices that can abruptly respond to diverse external stimuli. In recent years, rapid advancement in the fabrication and property modulation of vanadium dioxide has greatly facilitated its applications in many aspects, such as thermal sensing, thermochromics, electronics, and multiple-response mechanics. The optical properties of thin vanadium dioxide films VO2 were researched using the modulation polarimetry technique. For VO2 thin film deposition the two-step method was used. VO2 films were grown on quartz glass substrates by magnetron sputtering of the VO2 target. The films had different modifications of composition, structure, morphology, and optical properties due to the manufacturing technology. The angular dependence of the reflection coefficients of electromagnetic radiation of s- and p- polarizations and their difference for different wavelengths was measured in the paper. The polarization characteristics were simulated by a matrix transformation of the Fresnel formulas. The values of the refractive and absorption indices of the films were obtained from the condition of the best agreement between the experiment and mathematical simulation. Atomic force microscope and X-ray diffraction analysis were used as standard analytical methods

Properties of Electrochromic Cell with WO3 and NiO: the Influence of Ionic Conductor

The electrochromic WO3 and NiO films were deposited by magnetron sputtering on indium tin oxides coated glass. The structural properties of the films were investigated by scanning electron microscopy and X-ray diffractometery techniques. The electrochromic properties of the films were investigated by means cyclic voltammetry using different types of ionic conductors. The use of water electrolytes and electrolytes which are based on propylene carbonate leads to the destruction of electrochromic cells. The stable working electrochromic cell with WO3 and NiO films was obtained using ionic liquid as the ionic conductor. The coloration efficiency of electrochromic cell which is based on amorphous WO3 film and crystalline NiO film is 28.7 cm2 /C. Keywords: tungsten oxide, nickel oxide, electrochromic cell, ion conductor

Influence of annealing on luminescence and energy transfer in ZnO multilayer structure co-doped with Tb and Eu

International audienceThe influence of rapid thermal annealing (RTA) on structural and optical properties of ZnO multilayer structures co-doped with Tb and Eu ions has been investigated by X-ray diffraction, Time-of-Fligth Secondary Ion Mass Spectrometry, Specular Infrared reflection, micro-Raman and photoluminescence (PL) methods. It is shown that incorporation of rare earth (RE) ions in ZnO host is accompanied by the formation of intrinsic defects in oxygen and zinc sub-lattices of ZnO. The appearance of intense Raman mode at 275 cm−1 is ascribed mainly to Eu ion incorporation on Zn site in ZnO matrix. The PL of RE ions localized in ZnO and other crystal phases is revealed. The effect of energy transfer from Tb3+ to Eu3+ ions in ZnO is identified. It is shown that the RTA improves crystal structure of ZnO host, i.e. stimulates the increase of coherent domain sizes and strain relaxation, as well as promotes the redistribution of RE ions across the structure. The effect of RTA on RE ion PL depends strongly on the annealing temperature. It is found that RTA at 500 °C promotes Eu incorporation into ZnO and the enhancement of Eu3+ PL due to energy transfer from Tb3+ to Eu3+, while RTA at 800 °C stimulates segregation of RE ions and the decrease of their PL

Redistribution of Tb and Eu ions in ZnO films grown on different substrates under thermal annealing and its impact on Tb-Eu energy transfer

International audienc