422 research outputs found

    Matrix-matched calibration in LA-ICP-MS of silicate, phosphate and carbonate minerals: application of G-Probe samples

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    Received: 23.12.2019. Accepted: 20.02.2020. Published: 31.03.2020.Laser ablation (LA) sampling provides fast microelement ICP-MS analysis of a wide range of solid materials without their dissolution, thus decreasing contamination from water and reagents as well as reducing polyatomic isobaric interferences from acid solutions. However, the issue of matrix-matched calibration becomes crucial for LA-ICP-MS due to differences in behaviour during laser interaction and evaporation of solid samples. There are several approaches to LA calibration: simultaneous supply of standard solutions into a spray chamber; calibration using a set of NIST 61х synthetic glasses and glasses prepared from natural rocks and minerals (basalt, nephelinite, etc.) or pressed synthetic samples (calcium carbonates, phosphates and sulphides produced by USGS). A set of natural glasses for microanalysis is available from the International Association of Geoanalysts (IAG) in co-operation with the USGS. The G-Probe proficiency testing programme has been operating since 2008 and deals with solid samples for microanalysis (LA-ICP-MS, EPMA, EDS-SEM). A number of samples of different compositions were distributed: BBM‑1G and BSWIR‑1G natural basaltic glasses, GSM‑1 gabbro; NIST SRM-based basaltic and diabase glasses; GP-MACS synthetic pressed calcium carbonate, GP-MAPS phosphate and some others. The aim of the present work was to estimate the LA-ICP-MS analysis quality using matrix-matched calibration with G-probe samples of various composition. All G-Probe samples were analysed using an ELAN 9000 Q-ICP-MS combined with a LSX‑500 (Nd:YAG, 266 nm) laser ablation system. For silicate rocks, TB‑1 basaltic glass was used for calibration; the remaining samples were analysed as unknowns. MAPS‑4 calibration material were used for phosphate rock analysis. A combination of external matrix-matched calibration and internal normalisation was used for calculating element concentrations. LA-ICP-MS analysis quality was estimated using z-scores. Most of the results obtained were in a good agreement with assigned values.The study was carried out at the Geoanalytic Collective Use Centre and supported by RSF grant No. 16‑17‑10283

    Dynamics and configurations of galaxy triplets

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    The purpose is to infer the probable dynamical states of galaxy triplets by the observed data on their configurations. Two methods are proposed for describing the distributions of the triplet configuration parameters characterizing a tendency to alignment and hierarchy: (1) obtaining a representative sample of configurations and determining its statistical parameters (moments and percentages); and (2) dividing the region of possible configurations of triple systems (Agekian and Anosova, 1967) into a set of segments and finding the probabilities for the configurations to find themselves in each of them. Both these methods allow representation of the data by numerical simulations as well as observations. The effect of projection was studied. It rather overestimates the alignment and hierarchy of the triple systems. Among the parameters of interest there are found some parameters that are least sensitive to projection effects. The samples consist of simulated galaxy triplets (with hidden mass) as well as of 46 probably physical triple galaxies (Karachentseva et al., 1979). The observed triples as well as numerical models show a tendency to alignment. The triple galaxies do not show any tendency to hierarchy (formation of the temporary binaries), but this tendency may be present for simulated triplets without significant dark matter. The significant hidden mass (of order ten times the total mass of a triplet) decreases the probability of forming a binary and so weakens the hierarchy. Small galaxy groups consisting of 3 to 7 members are probably the most prevalent types of galaxy aggregate (Gorbatsky, 1987). Galaxy triplets are the simplest groups, but dynamically nontrivial ones

    Study on the influence of the magnetron power supply on the properties of the silicon nitride films

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    Silicon nitride (Si3N4) films were deposited by magnetron sputtering of silicon target in (Ar+N2) atmosphere with refractive index 1.95 - 2.05. The results of Fourier transform infrared (FTIR) spectrophotometry showed Si-N bonds in the thin films with concentration 2.41·1023 - 3.48·1023 cm-3. Dependences of deposition rate, optical characteristics and surface morphology on rate of N2 flow and properties of magnetron power supply

    Some Issues of Terminating a Criminal Case

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    This publication continues the experience of covering the work of the Scientific and Meth­odological Council under the Prosecutor of the Omsk Region, among the main tasks of which remains the development and discussion, together with representatives of legal science, of sound recommenda­tions on problematic issues of prosecutorial supervision, legislation and law enforcement practice, legal advisory opinions on issues arising in prosecutorial practice. In this regard, the article proposes to dis­cuss certain topical problems of law enforcement practice raised at one of the last meetings of the Scien­tific and Methodological Council under the Prosecutor of the Omsk Region. Thus, based on a systematic analysis of errors in the implementation of the institution of a judicial fine, it is proposed to provide prosecutors with systematic supervision over compliance with the requirements of the law when it is ap­plied, which requires a more thorough study of criminal cases, as well as a proper initiative to establish the circumstances associated with the application of a judicial fine, and timely challenging unfounded court decisions. In addition, the practice of law enforcement highlights the fundamental problem of a unified interpretation of the grounds for terminating a criminal case (criminal prosecution) against a person who has committed an act prohibited by criminal law in a state of insanity. Based on the analy­sis of legal situations and various approaches to their resolution, the article argues for the need to make a decision on the studied criminal cases on the grounds of paragraph 4 of part 1 of Art. 24 of the Criminal Procedure Code of the Russian Federation in connection with the death of a person involved in criminal proceedings. In other similar situations, but related to the criminal prosecution of these persons, the deci­sion must be made taking into account the specific circumstances of the criminal case

    The influence of bone substitute material on mechanical properties of trabecular bone in augmentation of intra-articular impression fractures. Experimental study

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    The purpose was to evaluate the effect of bone substitute materials on mechanical properties of trabecular bone adjacent to the joint. Material and methods A total of 21 female chinchilla rabbits weighing 3-3.5 kg was used for the experimental study. A bilateral impression fracture was simulated in the medial tibial condyle and surgically augmented with one of the bone substitution materials: beta-tricalcium phosphate, xenoplastic material and carbon nanostructures. The animals were sacrificed at 6, 12 and 24 weeks postsurgery. Uniaxial compression test was performed to determine mechanical properties of the tibial fragments. Bone microstructure was evaluated with scanning electron microscopy. Statistical data analysis was performed with nonparametric tests. Results Beta-tricalcium phosphate augmentation of the bone interface led to slow resorption accompanied by formation of adequate high-grade bone tissue with mechanical properties gradually increasing with greater observation time that indicated to the bone substitute integrated well with the host bone of the impression bone defect. Xenoplastic augmentation resulted in rapid resorption accompanied by formation of immature bone with mechanical properties declining at 6 to 12 weeks of observation. Carbon nanostructure augmentation of the bone interface caused perifocal bone resorption and absence of osteointegration with mechanical properties declining at 12 to 25 weeks of observation. © Gilev M.V., Zaytsev D.V., Izmodenova M.Y., Kiseleva D.V., Volokitina E.A., 2018

    Clinical and methodological aspects in the diagnosis of magnesium deficiency in patients with paroxysmal atrial fibrillation

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    Aim. To determine magnesium deficiency in patients with paroxysmal atrial fibrillation using a comprehensive clinical and laboratory approach. Methods. The prospective cohort study included 35 patients of the cardiology department of the Medical association «Novaya bolnitsa». The main group consisted of 22 patients with frequently recurrent paroxysmal atrial fibrillation, the control group - 13 patients without cardiac arrhythmias. The clinical status, Holter-monitoring of the electrocardiogram, the results of the clinical test for magnesium deficiency, laboratory parameters of calcium, magnesium in blood plasma and formed elements, magnesium in whole blood, free fatty acids and plasma osmolarity were evaluated. Results. The clinical score of magnesium deficiency was significantly higher in patients from the main group compared to the control [16.5 (11÷21) vs 13 (8÷15), p <0.001]. In the main group, there was a decrease of magnesium in the whole blood [0.55 (0.5÷0.59) vs 0.61 (0.58÷0.54), p=0.002] and inside the blood cells [0.68 (0.53÷1.29) vs 1.38 (1.29÷1.44), p <0.001]. In patients with atrial fibrillation there is a shift of the ratio of calcium to magnesium in blood plasma [2.5 (2.5÷3) vs 2.9 (2.8÷3.15), p=0.029] and intracellularly [4.85 (2.62÷9.3) vs 1.7 (1.4÷1.95), p=0.002]. The redistribution of calcium and magnesium is influenced not only by the initial concentration of cations, but also by free fatty acids. The best redistribution was obtained when the concentration of free fatty acids was 900 µmol/l, magnesium 1 mmol/l, and calcium 3 mmol/l, which is consistent with the optimal value of cations in the blood plasma. Conclusion. Patients with paroxysmal atrial fibrillation had a significantly lower magnesium content in whole blood and inside the blood cells; magnesium concentration in the cells and in whole blood closely correlated with the results of the clinical test for evaluating magnesium deficiency; intracellular magnesium content can be influenced by the complexing interaction with free fatty acids

    Theory of differential inclusions and its application in mechanics

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    The following chapter deals with systems of differential equations with discontinuous right-hand sides. The key question is how to define the solutions of such systems. The most adequate approach is to treat discontinuous systems as systems with multivalued right-hand sides (differential inclusions). In this work three well-known definitions of solution of discontinuous system are considered. We will demonstrate the difference between these definitions and their application to different mechanical problems. Mathematical models of drilling systems with discontinuous friction torque characteristics are considered. Here, opposite to classical Coulomb symmetric friction law, the friction torque characteristic is asymmetrical. Problem of sudden load change is studied. Analytical methods of investigation of systems with such asymmetrical friction based on the use of Lyapunov functions are demonstrated. The Watt governor and Chua system are considered to show different aspects of computer modeling of discontinuous systems

    МЕТОДИКА ОПРЕДЕЛЕНИЯ ИЗОТОПНЫХ ОТНОШЕНИЙ Cu И Zn МЕТОДОМ МК ИСП-МС С ИСПОЛЬЗОВАНИЕМ СМОЛЫ AG MP-1

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    The isotopic composition of copper is of great interest for researchers in various fields of science, geochemistry and hydrology in particular, wherein the consideration is being given to the variations in the isotopic composition of the Earth's crust, extraterrestrial matter, and water basins, as well as to the origin and transfer of matter. Zn isotopes appear to be promising for identifying the sources and pathways of the environmental pollution. The aim of this study involves the refinement and validation of the zinc and copper isotopic ratio determination methodology covering the whole process from sample digestion to MC ICP-MS measurements. For this reason, as well as to assess the suitability of the methodology for the analysis of environmental samples, Zn and Cu isotopic analysis of the BHVO-2, BCR-2 and AGV2 USGS certified reference materials has been performed. The method for determination of Cu and Zn stable isotope ratios by multi-collector inductively coupled plasma mass spectrometry in environmental samples is developed. The application of the AG MP1 resin with optimized layer parameters (resin bed height 3.5 cm, diameter 1 cm) provides the highpurity Cu and Zn fractions. The method is characterized by high throughput and adequate analytical figures of merit when using the standardsample bracketing technique for mass bias correction. The procedural blanks related to chemical dissolution and ion exchange procedures are lower than 1 and 3 ng for Cu and Zn, respectively, assuring no blank effect on the isotopic composition of samples. The accuracy and precision obtained for Cu and Zn isotope measurements in the BHVO2, BCR2 and AGV2 geological certified reference materials demonstrate good agreement with the reference values published. © 2022 Institute of the Earth's Crust. All rights reserved.ААААА181180530900458; Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2021-680; Russian Science Foundation, RSF: 18-77-10024The work of Okuneva T.G. is supported by the Russian Science Foundation (project 18-77-10024), the rest authors are supported by the state assignment of the IGG UB RAS ААААА181180530900458. Isotopic analyses are performed at the "Geoanalitik" Shared Research Facilities of the IGG UB RAS. The reequipment and comprehensive development of the "Geoanalitik" Shared Research Facilities of the IGG UB RAS is financially supported by the grant of the Ministry of Science and Higher Education of the Russian Federation (Agreement 075-15-2021-680).authors are supported by the state assignment of the IGG UB RAS ААААА 猃?猃猃稃爃眃甃爃笃爃爃瘃?稁 Isotopic analyses are performed at the 㘀Geoanalitik ? Shared Research Facilities of the IGG UB RAS. The reequipment and comprehensive development of the 㘀Geoanalitik 㘀 Shared Research Facilities of the IGG UB RAS is 퀀inancially supported by the grant of the Ministry of Science and Higher Education of the Russian Federation (Agreement 075-15-2021-680).FUNDING: The work of Okuneva T.G. is supported by the Russian Science Foundation (project 18-77-10024), the res
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