Search

We investigated the khatyrkite–cupalite holotype sample, 1.2 × 0.5 mm across. It consists of khatyrkite (Cu,Zn)Al2, cupalite (Cu,Zn)Al, and interstitial material with approximate composition (Zn,Cu)Al3. All mineral phases of the holotype sample contain Zn and lack Fe that distinguishes them from khatyrkite and cupalite in the Khatyrka meteorite particles (Bindi et al. 2009, 2011, 2012, 2015; MacPherson et al. 2013; Hollister et al. 2014). Neither highly fractionated natural systems nor geo- or cosmochemical processes capable of forming the holotype sample are known so far. The bulk chemistry and thermal history of khatyrkite–cupalite assemblage in the holotype sample hint for its possible industrial origin. Likewise, the aluminides in the Khatyrka meteorite particles may also be derived from industrial materials and mixed with extraterrestrial matter during gold prospecting in the Listvenitovy Stream valley.

Experimental study of pumping characteristics of a pilot model of a claw single-stage vacuum pump with identical rotors was carried out. The curves of pumping speed vs. pressure at different rotary speed and the ultimate pressure at different rotors speed were determined on a test unit. Indicator pressure diagrams in working chambers of claw vacuum pump were obtained with the help of special sensors. Thus, an experimental data bank concerning the pumping characteristics of claw vacuum pump was created. It may be used for estimation of mathematical model adequacy and further development of the pump design. Experimentelle Untersuchungen von Pumpcharakteristiken olfreier Klauenpumpen An einem speziellen Pumpstand wurden Messungen zur Bestimmung der Pumpencharakteristik einer einstufigen Klauenpumpen durchgefuhrt. Fur verschiedene Rotorgeschwindigkeiten wurde die Pumpgeschwindigkeit in Abhangigkeit vom Druck mithilfe von Sensoren aufgenommen. Ebenso wurde der zu erzielende Enddruck in Abhangigkeit der Rotorengeschwindigkeit gemessen. Damit steht erstmalig fur diesen Pumpentyp eine Datenbank mit den experimentell bestimmten Charakteristiken zur Verfugung, die zur Bewertung mathematischer Modelle und zur Weiterentwicklung dieser Pumpen herangezogen werden kann.

The mechanical and thermal causes of deformations of the orbiting and the fixed elements of oil free vacuum pumps are considered. Basic data for deformation calculation are geometric dimensions of the pump and dependence of working chamber volume on the orbiting scroll element rotation angle. Gas temperature and pressure values in each vacuum pump chamber are obtained with the help of a working process mathematical model. Deformation calculation is carried out by the finite element method realized in the software ANSYS. It is shown that deformations caused by pressure-induced mechanical forces do not have considerable influence on the change of radial clearances between the scrolls. They may not be taken into account for pumping characteristics calculation. Thermal-induced deformations are much greater, and the change of the clearances due to this cause may be 25 % and even larger. Deformationen an Maschinenelementen trockenlaufender Scrollverdichter — mechanische und thermische Ursachen Der Beitrag beleuchtet mechanisch und thermisch bedingte Verformungen an den feststehenden und beweglichen Spiralen trockenlaufender Scrollverdichter. In die Berechnungen der Deformationen fliesen die Grose der Pumpe und die Abhangigkeit des aktuellen Pumpraums zwischen den Spiralen vom Drehwinkel des Spiralelements ein. Auf der Grundlage eines mathematischen Models des Pumpvorgangs werden Druck und Temperatur des zu pumpenden Gases in jedem Kammerelement ausgerechnet. Mit Hilfe der Finite-Elemente-Methode (ANSYS) werden dann die Deformationsrechnungen durchgefuhrt. Die Simulationsrechnungen ergaben, dass die mechanisch bedingten Verformungen keine wesentlichen Auswirkungen auf den radialen Ab stand zwischen den beiden Spiralen haben. Die warmebedingten Deformationen sind dagegen um ein Vielfaches groser und konnen Veranderungen der Abstandsmase um 25 % und mehr be wirken.

The range of operation pressures of non-contact vacuum pumps may reach six decades, and flow regime in slot channels of the rotor mechanism may vary from molecular flow to viscous flow. This article is a continuation of a series of authors‘ publications dedicated to the development of a method which makes it possible to calculate promptly the conductance of slot channels with complex contoured geometry with the minimal clearance at a certain point along gas flow direction for all three gas flow regimes: molecular, transient and viscous. The numerical solution of the differential equations system (equations of motion, energy, continuity and state) is used for calculation of mass flow rate in transient gas flow regime. On the basis of the numerical calculation results the relationship is obtained which represents a smooth joining of the data for molecular and viscous flow regimes. Verification of the model and the obtained relationship is carried out by comparison of numerical calculation results of gas mass flow rate and conductance with experimental data obtained by blowing-through of slot channels. The maximal deviation of calculation according to the obtained relationship from the experiment does not exceed 14%, the average uncertainty being less than 8%, which makes it possible to recommend it for practical application in transient flow regime. Berechnung der Leitwerte von Spaltkanalen mit variablen Querschnitten fur molekulare bis viskose Gasstromung Der Druckbereich kontaktlos arbeitender Vakuumpumpen deckt uber sechs Dekaden ab. Dabei konnen die Flussverhaltnisse in den Spaltkanalen und Rotorblocken von molekularer uber Knudsen- bis hin zu viskoser Stromung variieren. Die bereits in vorangegangenen Beitragen beschriebene Methode zur Berechnung der Leitwerte von Spaltkanalen komplexer Geometrie wird hier weiterentwickelt und um die Beschreibung viskoser Stromungsverhaltnisse erganzt. Somit konnen nun Leitwerte von Spaltkanalen mit kleinsten Zwischenraumen fur molekulare, Knudsen- und viskose Stromung berechnet werden. Die numerische Losung des Differentialgleichungssystems (Bewegungs-, Energie- und Kontinuitatsgleichung) wird zur Berechnung des Massenflusses im Bereich der Knudsenstromung benutzt. Die daraus resultierende mathematische Beziehung fugt sich glatt an die fur die Bereiche molekularer und viskoser Stromung gewonnen Daten an. Die groste Abweichung der berechneten von den gemessenen Daten betragt 14 %; die mittlere Unsicherheit ist kleiner 8 %. Dieses Ergebnis qualifiziert den Ansatz fur die praktische Anwendung.

Polypropylene-based composites filled with carbon fibers and multiwall carbon nanotubes were produced by coagulation precipitation technique. Composite articles were produced by conventional injection molding technique. It was shown that the addition of carbon nanotubes (10% of total amount of carbon fibers) results in significantly increased anisotropic thermal conductivity of the composite due to formation of thermal conductive bridges between carbon fibers, which are oriented during molding. The addition of CNTs has a significant effect with more than a 50–70% increase of both the axial and transverse thermal conductivity of the composite. Produced composites were used for injection molding of polymeric radiators for LED lamps, showing sufficient heat dissipation efficiency allowing using them for industrial application in the field. POLYM. COMPOS., 36:1951–1957, 2015. © 2014 Society of Plastics Engineer

Non-contact oil-free vacuum pumps are widely used in different technological processes such as nanomaterials industry, pharmaceuticals industry, food industry, medicine, etc., thanks to absence of oil seal, high discharge, long operating life, yet low energy consumption. Scroll pumps are of particular interest as they make it possible to isolate bearing assemblies with grease from the working volume of the pump with the help of bellows. Pumping characteristics of non-contact vacuum pumps are greatly influenced by backward leakage through slot channels of the rotor mechanism. The conductance is the main value characterizing backward leakage. In this paper an efficient method for prompt conductance calculation of slot channels with any geometry with the minimal clearance at a certain point along gas flow direction is presented. The calculation error of the presented method does not exceed 6%. The presented method was used in mathematical models for the pumping process of scroll pumps, claw pumps and Roots pumps. This method is recommended for pumping characteristics calculation of different non-contact pumps and gas flow rates in vacuum systems channels. Eine universelle Methode zur Berechnung der Leitungsfahigkeit von profilierten Spaltkanalen in kontaktlosen Vakuumpumpen Kontaktlose olfreie Pumpen finden immer breitere Anwendung bei verschiedensten technologischen Prozessen in Nanotechnologie und Mikroelektronik sowie der Pharmazeutik, Nahrungsmittelindustrie und Medizin. Die Vorteile des kontaktlosen Mechanismus liegen im Verzicht auf Schmiermittel, der Gewahrleistung einer hohen Produktivitat und einem geringen Energieverbrauch. Besonders attraktiv sind hierbei die Spiralmaschinen, die die schmiermittelbeladenen Walzlagerkopfe mit Hilfe eines Faltenbalgs vollstandig vom Rezipienten trennen konnen. Die Pumpcharakteristiken der beliebigen kontaktlosen Vakuumpumpen werden in erster Linie von der Ruckstromung des Gases durch die Spaltkanale des Wendelmechanismus bestimmt. Die Leitfahigkeit ist die die Ruckstromung bestimmende Grose. Diese Arbeit stellt ein Methode vor, mit der sich die Leitfahigkeit von Spaltkanalen beliebiger Geometrie mit einem Fehler unter 6 % berechnen lasst. Die mathematischen Modelle lassen sich auf Spiralpumpen ebenso wie auf Roots- und Klauenpumpen anwenden und kann zur Berechnung von Pumpcharakteristiken eingesetzt werden.

The article presents research on the mechanical properties of epoxy resin modified with potassium polytitanate small additives. The influence of the surface modification of potassium polytitanate particles on their properties and interaction with epoxy resins and the mechanical properties of the resulting composite were investigated. The interactions among the dressing additives, binders and fillers were determined. The study shows the dependence of properties of composite materials on the content of dressing additives and method of filling with potassium polytitanate. This study also highlights possible reasons for variation in the mechanical properties of epoxy resin filled with potassium polytitanate particles. POLYM. ENG. SCI., 54:2866–2871, 2014. © 2014 Society of Plastics Engineers

Gas flow through channels formed by cylindrical walls in molecular gas flow regime is considered in this work. Ex- perimentally obtained conductance of three types of channels in a wide pressure range is presented. Conductance in molecular flow regime is specified. Test particle Monte Carlo (TPMC) method is used for calculation of probability of molecule transition through channels formed by cylindrical walls when wall's radii and clearances vary. Generalization of calculated values is carried out, and a uniform formula for three types of channels is given. It can be used for gas flow in vacuum systems and oil-free pumps such as scroll pumps and Roots pumps. Leitwert von Schlitzkanalen mit zylindrischen Wanden bei molekularer Gaststromung Die molekulare Stromung von Gas durch schmale, von zylindrischen Wanden begrenzte Kanale wird betrachtet. Experimentelle Untersuchungen von Leitfahigkeiten dreier Kanaltypen uber weite Druckbereiche werden vorgestellt. Durch Monte-Carlo-Algorithmen werden die Wahrscheinlichkeit des Durchganges der Molekule bei der Veranderung der Wandradien und des Spielraums zwischen den Wanden berechnet. Die Verallgemeinerung der Rechendaten liefert eine einheitliche Formel fur drei Kanaltypen. Sie kann zur Berechnung von Gasstromen in Vakuumsystemen und in verschiedenen ol-losen Pumpen herangezogen werden.

The treatment of uncertainties associated with modeling and risk assessment has recently attracted significant attention. The methodology and guidance for dealing with parameter uncertainty have been fairly well developed and quantitative tools such as Monte Carlo modeling are often recommended. However, the issue of model uncertainty is still rarely addressed in practical applications of risk assessment. The use of several alternative models to derive a range of model outputs or risks is one of a few available techniques. This article addresses the often-overlooked issue of what we call "modeler uncertainty," i.e., difference in problem formulation, model implementation, and parameter selection originating from subjective interpretation of the problem at hand. This study uses results from the Fruit Working Group, which was created under the International Atomic Energy Agency (IAEA) BIOMASS program (BIOsphere Modeling and ASSessment). Model-model and model-data intercomparisons reviewed in this study were conducted by the working group for a total of three different scenarios. The greatest uncertainty was found to result from modelers' interpretation of scenarios and approximations made by modelers. In scenarios that were unclear for modelers, the initial differences in model predictions were as high as seven orders of magnitude. Only after several meetings and discussions about specific assumptions did the differences in predictions by various models merge. Our study shows that parameter uncertainty (as evaluated by a probabilistic Monte Carlo assessment) may have contributed over one order of magnitude to the overall modeling uncertainty. The final model predictions ranged between one and three orders of magnitude, depending on the specific scenario. This study illustrates the importance of problem formulation and implementation of an analytic-deliberative process in risk characterization.

Biomagnification of organochlorine and other persistent organic contaminants by higher trophic level organisms represents one of the most significant sources of uncertainty and variability in evaluating potential risks associated with disposal of dredged materials. While it is important to distinguish between population variability (e.g., true population heterogeneity in fish weight, and lipid content) and uncertainty (e.g., measurement error), they can be operationally difficult to define separately in probabilistic estimates of human health and ecological risk. We propose a disaggregation of uncertain and variable parameters based on: (1) availability of supporting data; (2) the specific management and regulatory context (in this case, of the U.S. Army Corps of Engineers/U.S. Environmental Protection Agency tiered approach to dredged material management); and (3) professional judgment and experience in conducting probabilistic risk assessments. We describe and quantitatively evaluate several sources of uncertainty and variability in estimating risk to human health from trophic transfer of polychlorinated biphenyls (PCBs) using a case study of sediments obtained from the New York-New Jersey Harbor and being evaluated for disposal at an open water off-shore disposal site within the northeast region. The estimates of PCB concentrations in fish and dietary doses of PCBs to humans ingesting fish are expressed as distributions of values, of which the arithmetic mean or mode represents a particular fractile. The distribution of risk values is obtained using a food chain biomagnification model developed by Gobas ( 1 , 2 ) by specifying distributions for input parameters disaggregated to represent either uncertainty or variability. Only those sources of uncertainty that could be quantified were included in the analysis. Results for several different two-dimensional Latin Hypercube analyses are provided to evaluate the influence of the uncertain versus variable disaggregation of model parameters. The analysis suggests that variability in human exposure parameters is greater than the uncertainty bounds on any particular fractile, given the described assumptions.

The reaction can regarded as 1,8-addition starting with direct nucleophilic attack by amino nitrogen of amines (II) on CH=N carbon.

Products (III) and (V) exhibit the enantiotropic nematic mesomorphism in a sufficiently wide temperature range.

The article presents a theoretical model for calculating the gas flow through channels with moving walls in the molecular flow regime. The analytical equations are solved by iteration techniques. The calculated data for the pumping speed and the compression ration of a molecular pump are compared with the experimental results. The agreement between calculated and measured values is good. Der Artikel stellt ein theoretisches Modell zur Berechnung der Gasstromung durch Kanale mit sich bewegenden Wanden im molekularen Stromungsbereich vor. Die analytischen Gleichungen werden mit einem Iterationsverfahren gelost. Die berechneten Daten fur das Saugvermogen und das Kompressionsverhaltnis einer molekularkinetischen Pumpe werden mit experimentellen Ergebnissen verglichen. Die Ubereinstimmung von gerechneten und gemessenen Daten ist gut.

Addition of hydrogen chloride to quinones and N-substituted quinone imines follows 1,4[1] or 6,3-addition pattern [2], leading to aromatization of the quinoid ring with introduction of chlorine into the aromatic ring. We found that 4-[2-(4-nitrobenzylidene)hydrazono]cyclohexa-2,5-dien-1-one (I) reacts with hydrogen chloride to give 4-[2-(α-chloro-4-nitrobenzylidene)hydrazino]phenol (II). This reaction is unusual, for no chlorine atom is introduced into the aromatic ring, but highly reactive imidoyl chloride II is obtained. 4-[2-(α-Chloro-4-nitrobenzylidene)hydrazino]phenol (II). Concentrated hydrochloric acid, 5 ml, was added to a solution of 1.0 g (4 mmol) of compound I in 100 ml of glacial acetic acid, the mixture was stirred for 45 min, 100 ml of methylene chloride and 150 ml of water were added, the mixture was shaken for 10 min, and the organic phase was separated, washed with a 5% solution of sodium carbonate and water, and dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure, and the brown precipitate was washed with several portions of hexane. Yield 0.81 g (70%), mp 159–162°C. H NMR spectrum, δ, ppm: 10.12 s (1H, NH), 9.11 s (1H, OH), 8.28–8.04 d.d (4H, O2NC6H4, J = 8.9 Hz), 7.24 d (2H, 2-H, 6-H, J = 8.7 Hz), 6.74 d (2H, 3-H, 5-H, J = 8.7 Hz). Found, %: C 53.38; H 4.76; Cl 12.06; N 14.35. C13H10ClN3O3. Calculated, %: C 53.42; H 4.79; Cl 12.12; N 14.38. The H NMR spectra were recorded on a Varian Gemini 2000 spectrometer (400 MHz). The purity of compounds I and II was checked by TLC on Kieselgel 60 F254 plates (Merck) using chloroform–acetone (9 : 1) as eluent.