Luster measurement of pearl by UV-Vis reflectance spectroscopy

Pearl is an organic gem with its unique color and luster. One of the factors determining the quality and price of pearl is the luster. The different luster of pearls could be related to the different phase structures such as aragonite, calcite and vaterite. Previously, a gloss meter has been developed to measure light specularly reflected at 45° to the surface normal. Six different visual criteria for measuring gloss have been determined. Luster, a type of gloss, was defined as the ratio of specularly reflected light and that diffusely reflected normal to the surface. In practice, luster may be interpreted as relative brightness of specularly and diffusely reflecting areas. Due to the roundness of pearl, we measured the luster of pearl samples by a portable UV-Vis spectrophotometer with an integrating sphere. The luster could be calculated from the difference of CIELAB lightness measured by SCI and SCE geometries.

Characterization of Ni-Cr-Mo alloy phase structures under DLD process

Direct laser deposition of Ni-Cr-Mo alloy has been carried out to study the phase structure transformation under various operating parameters. To assess the phase composition SEM, TEM and XRD analysis were performed. It clearly seen that the precipitation of straightening phases (γ' and γ") depends on the temperature gradients caused by different laser power. The nucleation of γ' phase starts at 750 W while γ" phase at 1000 W. The changes in temperature gradients lead to different diffusion condition across all the stage of laser power variation and formation of δ-phase, primary MC carbides and Laves phase. δ-phase of all samples did not change the shape and characterized only by plate-like shape.

Polychromatic Hilbert diagnostics of phase and temperature disturbances, induced by candle flame in air

The work is motivated by the scientific and practical significance of the problem of non-disturbing diagnostics of phase and temperature fields induced in a gas medium by a flame of a torch (candle). The spatial conditions in which the fields are studied satisfy the model of axial symmetry of the torch associated with the vertical orientation of the candle. A method adequate to the problem to be solved has been developed, based on polychromatic Hilbert visualization of phase optical density fields, measurement of the temperature profile in selected sections of the medium under study, registration and selection of RAW images recorded by the photomatrix in RGB channels. The visualized Hilbert structures contain information on the phase optical density perturbations induced by the temperature field. The reliability of the results is confirmed by comparing the experimentally obtained hilbertograms and those reconstructed from phase structures using the Abel transform.

Effects of Oxide Additives on the Phase Structures and Electrical Properties of SrBi4Ti4O15 High-Temperature Piezoelectric Ceramics

In this work, SrBi4Ti4O15 (SBT) high-temperature piezoelectric ceramics with the addition of different oxides (Gd2O3, CeO2, MnO2 and Cr2O3) were fabricated by a conventional solid-state reaction route. The effects of oxide additives on the phase structures and electrical properties of the SBT ceramics were investigated. Firstly, X-ray diffraction analysis revealed that all these oxides-modified SBT ceramics prepared presented a single SrBi4Ti4O15 phase with orthorhombic symmetry and space group of Bb21m, the change in cell parameters indicated that these oxide additives had diffused into the crystalline lattice of SBT and formed solid solutions with it. The SBT ceramics with the addition of MnO2 achieved a high relative density of up to 97%. The temperature dependence of dielectric constant showed that the addition of Gd2O3 could increase the TC of SBT. At a low frequency of 100 Hz, those dielectric loss peaks appearing around 500 °C were attributed to the space-charge relaxation as an extrinsic dielectric response. The synergetic doping of CeO2 and Cr2O3 could reduce the space-charge-induced dielectric relaxation of SBT. The piezoelectricity measurement and electro-mechanical resonance analysis found that Cr2O3 can significantly enhance both d33 and kp of SBT, and produce a higher phase-angle maximum at resonance. Such an enhanced piezoelectricity was attributed to the further increased orthorhombic distortion after Ti4+ at B-site was substituted by Cr3+. Among these compositions, Sr0.92Gd0.053Bi4Ti4O15 + 0.2 wt% Cr2O3 (SGBT-Cr) presented the best electrical properties including TC = 555 °C, tan δ = 0.4%, kp = 6.35% and d33 = 28 pC/N, as well as a good thermally-stable piezoelectricity that the value of d33 was decreased by only 3.6% after being annealed at 500 °C for 4 h. Such advantages provided this material with potential applications in the high-stability piezoelectric sensors operated below 500 °C.

Phase structures and magnetostriction of Fe71.3Ga28.7 alloys prepared by different solidification rates

Magnetostrictive property shows anisotropic characteristics, which are related to phase structure and crystal orientation. In this paper, phase structures and magnetostrictive properties of Fe[Formula: see text]Ga[Formula: see text] at different solidification rates during zone-melting directional solidification were studied. Results show that when the solidification rate exceeds 72 mm/h, the sample has a single A2 structure. A multiphase structure of D03 and A2 is formed when the solidification rate is 36 mm/h. The multiphase structure of L12 and A2 emerges in the sample prepared with a solidification rate of 18 mm/h. The samples with L12 and A2 multiphase structure have excellent low-field magnetostrictive properties, reaching 68 × 10[Formula: see text] under a magnetic field of 20 kA/m.

Evaluation of the anesthesia depth in experimental animals by parameters of cerebral blood flow and structures of the blood serum solid phase (experimental study)

Актуальность. Важным патогенетическим звеном развития осложнений при введении наркоза является нарушение дыхания в виде апноэ, которое может переходить в агонию. Вместе с тем, не существует работ по регистрации мозгового кровотока в период агонии. Несмотря на многочисленные результаты исследований на животных, демонстрирующих, что общая анестезия приводит к нейродегенерации и когнитивным нарушениям, на сегодняшний день чёткого консенсуса о влиянии анестетиков на человека всё ещё не достигнуто. Цель исследования: выявить маркёры стадий наркоза у экспериментальных животных по структурам твёрдой фазы сыворотки крови (СК) и показателям мозгового кровотока (МК). Материалы и методы. Исследования проведены на половозрелых беспородных крысах-самцах. Животные наркотизировались хлоралгидратом: контрольные группы получали дозу 400 мг/кг, в/б, а опытные - 500-600 мг/кг, в/б. В разные фазы действия наркоза регистрировали системное артериальное давление (АД), МК, частоту дыхания и частоту сердечных сокращений. МК регистрировали прибором ЛАКК-02 (ЛАЗМА). АД измеряли монитором MEC8 Mindray. Структуры твёрдой фазы СК животных исследовали методом краевой дегидратации на тест-картах диагностического набора «Литос-система». Микроскопию структур СК проводили в поляризованном свете при увеличении × 200 и × 400 (микроскоп DM2500 фирмы «Leica»). Результаты. В контрольных группах показатели МК, частоты дыхательных движений и частоты сердечных сокращений достоверно не различались. В опытных группах через один час после дачи повышенной дозы наркоза наблюдали снижение частоты сердечных сокращений, частоты дыхания и показателей АД (р < 0,05). Сразу после начала апноэ МК начинал быстро снижаться вслед за падением АД. Амплитуда сердечного ритма в спектре колебаний МК повышалась в три раза по сравнению с контролем. От начала апноэ время снижения МК до нуля составляло от 60 до 240 с. До введения наркотического средства структуры СК были представлены в виде сферолитов и веерных образований, которые характерны для физиологического состояния организма. В стадии апноэ сферолиты и веерные структуры СК были испещрены множеством мелких изотропных включений, а также имели единичные мелкие и обширные изотропные разломы. В агональной стадии большинство структурных образований СК было представлено фрагментами сферолитов с многочисленными полосками и ветвистыми образованиями с высокой анизотропией, множественными разломами с изъеденными границами. Заключение. Динамика морфофункциональных показателей экспериментальных животных в результате воздействия наркотизирующих средств определяется перестройкой, возникающей в структуре белковых молекул, строение которых визуализируется при переводе СК в твёрдую фазу. Особенности патологических структур твёрдой фазы СК указывают на глубину наркотизации организма. Эти изменения согласуются с динамикой показателей сердечно-сосудистой и дыхательной систем экспериментальных животных после наркотизации. Результаты указывают на возможность применения анализа структур твёрдой фазы СК при ретроспективной оценке динамики МК, глубины наркотизации и побочных эффектов, вызываемых различными наркотизирующими средствами у пациентов с последующим использованием этих данных для выбора вида и оптимальной дозы наркотизирующего вещества при предстоящих хирургических вмешательствах. Background. An important pathogenetic step in the development of anesthesia complications is a breathing disorder in the form of apnea, which may transform into agony. However, there are no reports of cerebral blood flow (CBF) during the period of agony. Despite numerous animal studies showing that general anesthesia leads to neurodegeneration and cognitive impairment, there is still no clear consensus on effects of anesthetics in humans. Aim of the study. To identify markers of anesthesia stages in experimental animals by structures of blood serum (BS) solid phase and by indexes of CBF. Materials and methods. The study was carried out on sexually mature outbred male rats. The animals were anesthetized with chloral hydrate: control groups received a chloral hydrate dose of 400 mg/kg, i.p., and experimental groups received 500-600 mg/kg, i.p. Blood pressure (BP), CBF, respiratory rate and heart rate were recorded during different phases of anesthesia. CBF was recorded with a LAKK-02 device (LAZMA); BP was measured with a MEC8 Mindray monitor. BS solid phase structures were studied using the method of marginal dehydration on test cards of the “Litos-system” diagnostic kit. BS structures were examined under a microscope in polarized light at a magnification of ×200 and ×400 (DM2500 microscope, Leica). Results. In the control groups, indexes of CBF, respiratory rate, and heart rate did not significantly differ. In the experimental groups, one hour following administration of the increased anesthetic dose, the heart rate, respiratory rate, and BP were decreased (p < 0.05). Immediately after the onset of apnea, the drop in blood pressure was followed by a rapid decline in CBF. The heart rate amplitude in the spectrum of CBF oscillations was increased three times compared to the control. The time from the apnea onset to zero CBF ranged from 60 to 240 s. Before the drug administration, the BS structures represented spherulites and fan-shaped formations characteristic of the physiological state of the body. During the apnea stage, BS spherulites and fan-shaped structures were dotted with many small isotropic inclusions, and also had single small and extensive isotropic faults. During the agonal stage, most of the BS structural formations represented fragments of spherulites with numerous stripes and branched formations with high anisotropy and multiple faults with corroded boundaries. Conclusion. The changes in morpho-functional indexes under the action of anesthetics are determined by structural rearrangement of protein molecules as visualized during the BS transformation into the solid phase. The features of BS solid phase pathological structures indicate the anesthesia depth. These changes are consistent with changes in cardiovascular and respiratory parameters in anesthetized animals. The results indicate a possibility of using the analysis of the BS solid phase structures for a retrospective assessment of changes in CBF, the depth of anesthesia, and side effects caused by various anesthetics in patients. Subsequently, these data may be used for selecting the anesthetic type and its optimum dose for upcoming surgical interventions.