bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology of thermo-mechanical hardening of rotary carbide tools
Authors: Vasil’ev E V , Rauba A A , Abakumov A N , Zakharova N V , Sergeev V A
Published: January 2020

Improving physical and mechanical properties of tool materials is a complex scientific and technical problem. Application of thermo-mechanical hardening of monolithic carbide tools allows increasing the microhardness of at least 30%, which has a significant impact on the tool operating life. The use of the developed device allows for thermo-mechanical hardening of rotary carbide blanks for the manufacture of cutting tools, with high productivity and stability of the results.
Classification of crops by multispectral satellite images of sentinel 2 based on the analysis of vegetation signatures
Authors: Khamdamov R , Saliev E , Rakhmanov Kh
Published: January 2020

This article describes crop recognition methods from multispectral satellite imagery of Sentinel 2. The feature space includes taking into account parameters such as brightness and color of optical images over the entire channel of Sentinel 2 spectrozonal satellite imagery. The signs of multispectral images for various terrain classes in satellite images are analyzed. A comparative analysis of the classification results by the methods of “Expectation Maximization” and “k -means” has been compiled.
Computer modeling of filtration processes with piston extrusion
Authors: Kurbonov N , Aminov S
Published: January 2020

In this work, computer simulation of filtration processes based on the laws of hydrodynamics is considered. The adequacy of the developed models was verified by conducting a series of computational experiments. Created mathematical and software serves the purpose of research, forecasting and decision-making in the development and design of oil and gas fields.
Software for the computational experiment “Synthesis of the topological structure of the cognitive model”
Authors: Lozhnikov V , Marenko V
Published: January 2020

There is a great number of applications used today to support decision-making in socio-economic sphere. Various approaches and tools are used to implement the applications. The article provides the overview of scientific publications developing software algorithms based on cognitive modeling and fuzzy logic. The authors develop the software tool to conduct simulation experiments to synthesize the topological structure of a cognitive model for socio-economic facilities and objects. The results from the simulation experiment aimed to study the structure of the cognitive model taken as an example, are presented as a digraph “Impact of the Media on Mass Audience”. The software uses the programming language Java, JavaFX.
Definition of line formula on images
Authors: Narzillo Mamatov , Abdurashid Samijonov , Nilufar Niyozmatova , Musokhon Dadakhanov , Erkin Rahmonov
Published: January 2020

The article considers the problem of determining line formulas in a monochrome image. To solve this problem, a scheme, method and algorithm for determining the line coefficients using a finite difference are proposed. Based on the proposed method, it is also possible to solve the problems of approximation and interpolation.
On generic NP-completeness of the graph clustering problem
Authors: Rybalov Alexander
Published: January 2020

Generic-case approach to algorithmic problems was suggested by Miasnikov, Kapovich, Schupp and Shpilrain in 2003. This approach studies behavior of an algorithm on typical (almost all) inputs and ignores the rest of inputs. In this paper, we study the generic complexity of the problem of clustering graphs. In this problem the structure of relations of objects is presented as a graph: vertices correspond to objects, and edges connect similar objects. It is required to divide a set of objects into disjoint groups (clusters) to minimize the number of connections between clusters and the number of missing links within clusters. We prove that the graph clustering problem is NP-hard with respect to generic analog of polynomial Turing reduction. Supported by Russian Science Foundation, grant 18-71-10028.
Deep learning neural networks in fuzzy modeling
Authors: Sotvoldiev D , Muhamediyeva D T , Juraev Z
Published: January 2020

Deep learning neural networks have achieved remarkable success in various fields of application of artificial intelligence. This technology, which grew out of studies of artificial neural networks, has shown superior performance compared to other machine learning algorithms in areas such as image and voice recognition, natural language processing, and others. The use of deep learning neural networks in the construction of a fuzzy model is proposed.
Queue normalization methods in systems GI/GI/1/m with infinite variance of service time
Authors: Zadorozhnyi V N , Zakharenkova T R , Pagano M
Published: January 2020

Queuing systems with an infinite variance of service time are considered. The average waiting time in such systems is equal to infinity at a stationary regime. We analyze the efficiency of introducing of absolute priorities with infinite number of priority classes determined by the special axis marking on intervals for possible values of service time. It is stated that queues in systems become normalized, i.e. the average queue length become finite, when using regular marking. Furthermore, request loss probabilities radically decrease when buffer size is finite. More efficient marking – exponential marking – is proposed for practical purposes in networks with fractal traffic. The optimization problems of regular and exponential markings are solved.
Oil temperature influence on friction losses in silent chains
Authors: Velicu R
Published: January 2020

Evaluation of friction in chain drives is the first step in the process of reducing the friction. This paper presents the experiments on the analyses of temperature influence on friction in silent chains. A rig dedicated for friction measurements on parallel axes transmissions is used. Friction is measured as friction torque with possibility to control and measure the input rotational speed, chain tensioning, pressure and temperature of the oil for chain lubrication, pressure and temperature of the oil for bearings lubrication. Temperature depending viscosity of chain lubrication oil is measured separately. The functioning conditions of the bearings are maintained constant during the testing and only the temperature of chain oil lubrication is increased and then decreased in the range of functioning temperature of a timing chain. Oil temperature influence on friction from silent chains joints gives an image on the type of lubrication. The reduction of silent chain friction by reducing the functioning temperature may be a very simple solution and this paper shows how much power may be saved. Friction torque is measured for three distinct rotational speeds in the same tensioning parameters. Conclusions on the influence of rotational speed on friction losses with temperature are finally drawn.
On thermal calculation for helical gear transmission system
Authors: Gabroveanu I S , Cananau S , Mirica R F , Ilies A A
Published: January 2020

The purpose of the study in the paper is to evaluate the thermal comportment of the transmission systems with helical gears. Also, the influences of heat on characteristics of gear transmission system, based on the meshing thermal stiffness of gears are analyzed. An experimental testing stand of the system will be used to obtain data. The respond of the transmission under different working conditions is also analyzed. The study concerns the comparison of theoretical results obtained using calculation methods (from literature) and the experimental results, in order to obtain an evaluation of the friction in the meshing gears. The heat (temperature) affects the dynamic characteristics of the system by the meshing stiffness of the gear. The experimental results are used to verify the correctness of the theoretical model.
Eccentric device for varying the gear ratio
Authors: Roth M B , Romanet M , Ripeanu R G
Published: January 2020

In the paper is presented the working principle of the device as well as the constructive-functional scheme for its realization. The use of such a device allows variable gear ratios to be obtained in a very wide range. It has the advantage of a compact construction relative to other mechanisms with varying transmission ratios, such as the crank mechanism. The device contains a worm gear that allows for the eccentricity of a toothed wheel in relation to the cone wheel. The worm gear mechanism also ensures that it is self-locking while it is in operation without the need for other insurance items. The device can be used in the control of actuators in the field of machining or packaging in an automated process.
A bibliometric analysis of scientific research on tribology of composites in Southeastern Europe
Authors: Vencl Aleksandar , Vaxevanidis Nikolaos M , Kandeva Mara
Published: January 2020

In recent years there is a small but increasing number of articles presenting and/or analyzing the scientific production from discrete geographical regions on a certain scientific topic. These articles applied the so-called bibliometric methods in order to evaluate the contribution of different countries in a scientific research field. In the present work, the research output of all countries in Southeastern Europe on the scientific field of composites tribology is presented by using bibliometric indicators such as the total number of publications and citations, the average number of citations per publication, and the h-index. Analysis spans the last ten years and the required scientific data in order to calculate the bibliometric indicators were retrieved using the Scopus® scientific database.
Numerical considerations regarding the occurrence of plastic shearing with implications in scuffing
Authors: Fomin M , Musca I
Published: January 2020

Scuffing occurrence is also correlate with rheological behaviour of the lubricant. Using a viscous-plastic rheological lubricant model and an idealized roughness, as a symmetrical planar pad, a theoretical model of the pad-plane contact behaviour was developed. Based on this theoretical lubricating model, a numerical study was conducted in order to reveal the possibility of plastic shearing occurrence, in a pair formed by a symmetric pad, with dimensions comparable to the real roughness of the specimens previously used in previous experiments and a plane for values of operating parameters comparable to the real ones. The effect of the relative speed in contact, the effect of the minimum film thickness and the effect of the tilt angle of the idealized asperities flanks was analyzed. The numerical results, obtained based on the analytical model developed, correspond as order of magnitude and tendency of the parameters influence with the experimental scuffing results obtained by the authors and those presented in the literature and highlight the possibility of the occurrence of plastic shearing in the vicinity of the peak of the asperity and therefore the possibility of initiating the scuffing phenomena into contact.
Effects of organic compounds and nickel nitrate on friction coefficient of thermosetting
Authors: Păduraru I , Săracu G , Bogdan M , Graur I , Munteniţă C , Cîrciumaru A
Published: January 2020

The principal aim of this study is to point out the effect of organic compounds mixed with nickel nitrate in determined weight ratios on friction coefficient of two distinct types of epoxy systems.The two used organic compounds are starch and agar. Ultrasound exposure is typically used to properly prepare the powder modified composite materials namely to obtain a uniform dispersion of nickel nitrate in to the epoxy. Friction coefficient behaviour of composite materials is essential for successful applications among various modern industries of these challenging materials. Friction coefficient of the modified epoxy matrix was accurately measured using pin-on-disc geometry with TRM 1000 tribometer from Wazau at the Research and Development Center for Thermoset Matrix Composites from Dunărea de Jos University of Galaţi.
Effect of steel fiber addition on the mechanical and tribological behavior of the composite brake pad materials
Authors: Yanar H , Purcek G , Ayar H H
Published: January 2020

Effect of steel fiber addition on the friction and wear characteristics and mechanical properties of non-asbestos composites brake pad material was investigated. For this purpose, the content of steel fiber was added in the range of 0-20 wt.% with changing the rock fiber of the matrix structure. The matrix has also phenolic binder resin, cashew nut shell liquid, aramid pulp, magnetite, rubber and graphite. Friction behavior of the samples prepared from the mixture were tested using a pin-on-disk type test configuration according to the NF F 11-292 French standard. It was observed that coefficient of friction (CoF) of composite samples increased with increasing steel fiber content. After 5wt.% steel fiber addition, the CoF of composite did not significantly change. Although the steel fiber addition caused a significant increase in the CoF of the composite, no significant change can be observed in the specific wear rate with steel fiber addition up to 15wt.%, above which it increased significantly. On the other hand, steel fiber addition to the composite matrix deteriorated the mechanical properties, but improved the fade resistance of the sample.
Ball-on-flat reciprocating test to evaluate dry sliding wear behaviour of reinforced polymer composites
Authors: Iliuta V , Ripa M , Javorova J , Andrei G
Published: January 2020

This paper presents the results of the tribological investigations on polymeric composite materials reinforced with Cu, Zn, Sn, SiO2 and MoS2 microparticles, used for repairing metal parts made of brass and bronze. The tested material were: three composite materials (products of the company Diamant Metallplastic GmbH, Germany): Multimetall Messing (used for repair of brass parts), Multimetall Bronze (used for repair of bronze parts) and Moglice (for brass and bronze parts). The testing was conducted in dry conditions, in ball on flat configuration, by reciprocating method, on the CETR UMT-2 tribometer (Bruker Corporation) at normal loads 20, 30, 40 and 50N, over a sliding distance of 100m. The paper presents studies of the variations of the friction coefficient, linear wear, volumetric wear parameters, profilometric studies with SEM surface morphologies of the wear tracks. The researches allowed the classification of materials according to their tribological behaviour and the results recommend the tested reinforced composite materials as good candidates for repairing metal parts made of brass or bronzes.
Theoretical Analysis of Spherical Bearings Lubricated with Greases
Authors: Radulescu A V , Radulescu I
Published: January 2020

The paper presents theoretical researches concerning the spherical bearings lubricated with greases, in rheostatic conditions: high loads and low velocities. This type of bearing is very appropriate for modelling the human joints (hip, knee), spherical joints from automotive industry (pivots, connecting rods) or special joints from petroleum industry. Spherical bearings may be of the “fitted” type or the “clearance” type. The fitted type of nonflat bearing pad surface is lappedin to fit the runner. When it is operating, the fitted pad will have a varying film thickness across the pad sill, between the pad and the runner. Similarly, in the clearance type the film shape will be non-uniform across the pad sill. The variation in film thickness across the bearing pad, for nonflat pads, influences the resulting pressure distribution in the bearing pad and, hence, its load carrying capacity. In this paper, the pressure distribution and the load capacity are determined for “clearance” type bearings, for two different cases: complete spherical bearings and partial spherical bearings. It has been found that the eccentricity ratio influences the angular position of the maximum pressure, which becomes nearer to the minimum angle of the bearing, once with the increasing of the eccentricity ratio.
Tooth contact analysis of spur and helical gears with crowned profile for pinion
Authors: Cazan S , Dănilă C , Creţu S
Published: January 2020

The paper presents tooth contact analysis (TCA) of modified gears using semi-analytical methods (SAMs). The semi-analytical methods use Love’s analytical formulation for Boussinesq equation of linear half-space theory and Hartnett approach for numerical formulation. The linear contact between two teeth has a finite length and during meshing process the edge effect appears, with a harmful influence on the gear reliability. To eliminate this, some tooth profile modifications are needed. To turn a line contact into a point contact, the crowned lead profile surface is considered. The ways used to obtain the matrices of separation are discussed for both spur and helical cylindrical gears. The large pressures’ systems of equations were solved using the method of conjugate gradients and fast Fourier transform. For validation, in cases of hertzian geometries the SAM results have been compared with results obtained analytically, while for non-hertzian geometries, the SAM results have been compared with FEM results as presented in the specific literature. The developed SAM proved to be an accurate, robust and very fast tool for TCA of spur and helical cylindrical gear.
The influence of operating temperature and bearing steel structure in shakedown of three-dimensional elastic-plastic rolling contacts
Authors: Popescu G
Published: January 2020

This paper describes a model for the prediction of micro-plastic material transformation and associated residual stress field development in through-hardened and case-hardened bearing steels during over-rolling, considering the influence of operating temperature. The main challenge in analysing three-dimensional elastic-plastic rolling contacts is the accurate description of material properties in case of two-phase material, either is a constant amount of retained austenite (through-hardened AISI 52100 bearing steel) or variable amount of retained austenite along depth (case-hardened steel, i. e. 16MnCr5 bearing steel). Material parameters at room temperature, 650and 1000C degrees were obtained by half-compressive cycles tests on an INSTRONTMapparatus with a climate cell and further verified by performing experimental and numerical analyses in case of static indentation between a ceramic ball and a flat steel plate. To check the ability of the proposed models to simulate the elastic-plastic rolling contact in various loading condition, experiments were made on a special designated test rig and recorded values were compared with the numerical simulations obtained by using a semi-analytical solver. Measurements of residual cyclic profiles and residual stresses show a good agreement with theoretical values, leading to a better understanding of the fatigue process in hardened bearing steels.
Microscopic testing and analysis of drinking water filters after the final life cycle, using an experimental stand
Authors: Crişan H G , Crişan O A , Pustan M S , Bîrleanu C J , Merie V V
Published: January 2020

The purpose of this paper was to develop a testing infrastructure, under laboratory conditions, for the drinking water filters used in the household. The mechanical filtration of existing nanoparticles in drinking water distributed to the large public is a very important aspect of ensuring a high level of drinking water quality, at the final consumer-the household user, regardless of the conditions of supply or its distribution. Moreover, the importance of increasing the quality of domestic drinking water is reflected by the need to encourage its consumption, to the detriment of bottled PET packaging (polyethylene terephthalate), which confers a number of disadvantages in relation to environmental protection and consumer’s health. In order to achieve the proposed goal, a computer aided design (CAD) was developed and an experimental stand was designed and built to allow different categories of constructive and structural filters to be tested. The filters were chosen according to well established criteria. Their testing was aimed at identifying the potential and characteristics of mechanical filtration of existing nanoparticles in drinking water. Finally, using the atomic force microscopy technology (AFM), it was possible to microscopically investigate the nanofiltration results performed using the sample of tested filter elements and their classification according to the quality of the filtration obtained.
Influence of lubricant on the friction in an angular contact ball bearing under low load conditions
Authors: Popescu A , Olaru D N
Published: January 2020

The presence of the lubricant in a ball-race contact has two principal effects on friction: reduces the sliding friction, as a result of developing a film thickness between the contact surfaces and increases the rolling friction, as result of developing a hydrodynamic rolling friction. The influence of the hydrodynamic rolling friction on the torque of a modified 7205B angular contact ball bearing has been theoretically and experimentally studied. The experiments demonstrated that, for very low contact loads between balls and races, the effect of the hydrodynamic rolling force is dominant in the total friction torque. The experiments have been validated by using Biboulet’s transition model for hydrodynamic rolling forces developed in ball-race contacts.
Influence of ZnO concentration in rapeseed oil on tribological behavior
Authors: Ionescu T F , Guglea D , Georgescu C , Dima D , Deleanu L
Published: January 2020

This paper presents results of testing the coarse rapeseed oil additivated with different concentrations of ZnO (0.25%wt, 0.50%wt and 1%wt, with 14±5 nm in size), on a four-ball machine. The test parameters were load on main shaft of the machine: 100 N, 200 N and 300 N and the rotational speed 1000 rpm, 1400 rpm and 1800 rpm. For the tested range of ZnO concentration, the value of 1%wt does not improve the friction coefficient, but the wear rate of wear scar diameter was lower than that obtained with the neat rapeseed oil and the values are less sensitive with load and sliding speed for the more severe regimes. The additivation of rapeseed oil with ZnO is still efficient for the tested range of load and speed as compared to neat rapeseed oil. The authors formulated lubricants using as dispersant (2-methoxyphenol) in the ratio 1:1 to the additive. The technology is at scale laboratory and implies mechanical stirring and sonication. The tribological behavior was analysed based on obtained results, by mapping the friction coefficient, the wear rate of the wear scar diameter and the final temperature in the oil bath. For the additivated lubricants the following conclusions could be drawn. Friction coefficient tends to reach 0.1 only for low speed and high load (v = 0.38 m/s and F = 300 N), wear rate of wear scar diameter decreases with the increase of load, for each tested speed, probably because of a full fluid film generation. For F = 250…300 N, the map reveals a poor dependence on the additive concentration. The final temperature in the lubricant bath depends on speed, but for the same speed, it depends less on load, having a maximum value for 0.75% nano additive. These conclusions underlined the necessity of testing the new formulated lubricants because additive concentration and regime parameters could have synergic influences on the tribological parameters.
Study of the effect of duration of non-thermal plasma treatment on the surface properties of polymers
Authors: Tilmatine O , Zeghloul T , Fatu A , Dascalescu L
Published: January 2020

One of the factors affecting the electric charge acquired through friction between the polymers is their surface roughness. The dielectric barrier discharge (DBD) treatment is known to modify the surface characteristics of polymers. The aim of this study is to quantify the effect of atmospheric DBD exposure, in a well-defined configuration on the triboelectric behavior of polymers. Thus, Polytetrafluoroethylene (PTFE) plate samples characterized by different surface roughness were rubbed against bronze plate samples in a triboelectric test bench and then the electric potential at their surface was measured. The results were compared with those obtained for surfaces previously exposed to DBD treatment duration of which did not bring any change in their roughness. It was found that the roughness of the surface of the treated polymers hardly changed for rather short DBD exposure time (a few minutes). Significant changes were noticed for longer treatment duration (30 minutes and more). The samples that had undergone a longer treatment period modification acquired higher levels of electric charge by triboelectric effect.
Effect of deposition oxygen pressure on the properties of cuprous oxide thin films
Authors: Pustan M , Birleanu C , Merie V , Zarbo L , Garabagiu S , Marconi D
Published: January 2020

This study presents the effect of the oxygen pressure during deposition on the properties of cuprous oxide (Cu2O) thin films. The Cu2O is a p-type semiconductor material with a cubic crystallinity structure that has potential applications in solar cells, photo catalysis, gas sensing, superconductor, hydrogen production and thermoelectric generators. Different thicknesses of Cu2O films and different surface parameters are obtained if the oxygen pressure is modified during the depositions process. The samples were characterized by atomic force microscopy technique (AFM) and the results clearly demonstrate that Cu2O thin films properties are improved if the oxygen pressure during deposition decreases. The thickness of films and the surface parameters were measured using the AFM non-contact mode. The thickness and the surfaces roughness increase if the oxygen pressure during deposition decreases. This effect is based on obtaining higher particle sizes at low pressures. The modulus of elasticity and the hardness dependence on the deposition oxygen pressure is monitored by nanoindentation using a diamond Berkovich tip. The materials mechanical properties increase significantly if the oxygen pressure during deposition decreases, respectively. The results are useful to micro and nano-systems designers to fabricate reliable structures based on Cu2O thin films.
Nanoscale friction and wearing of octadecyltrichlorosilane covered silicon surface
Authors: Teodoroff-Onesim S , Besleaga A , Sirghi L
Published: January 2020

Silicon wafers were silanized by plasma hydroxylation and chemical vapour deposition of octadecyltrichlorosilane [OTS, CH3(CH2)17SiCl3]. Then, the OTS covered silicon samples were used in atomic force microscopy (AFM) measurements of wearing and friction at nanoscale. Wearing experiment performed by 1000 cycles of forwards and backwards movements of sharp AFM tip revealed formation of a wearing track with a depth that was much smaller than the thickness of OTS coating, which confirmed a very good wearing property of OTS coating. Friction versus normal loading force experiments performed with the same AFM tip revealed a nonlinear dependence of friction force on the normal loading force in agreement with prediction of Bowden and Tabor’s theory of friction and an increase of friction with the moving speed. Dependence of friction force on the sliding speed is attributed to a transfer of kinetic energy from the moving AFM tip to individual molecules of OTS coating.
Friction forces on human finger skin
Authors: Oprisan C M , Chiriac B , Carlescu V , Olaru D N
Published: January 2020

The prehension of the small objects with the human fingers is depending on the friction and adherence between finger’s skin and object’s surface. The design of finger pads for robotic and prosthetic hands must simulate both the human finger friction and adherence and elastic deformation, especially for small objects. In this paper, the authors have experimentally investigated the friction forces and friction coefficients in a dry sliding contact tribosystem using Microtribometer CETR UMT-2. A steel cylinder was sliding on the human finger with speeds between 0.5 to 10 mm/s at normal loads up to 10 N. The results showed that the friction coefficient increases with the sliding speed and decreases with the normal load. Also, it was evidenced the presence of the adherence and sliding zones during the laterally cyclic movement of steel cylinder as function of the normal loads and sliding speeds. A general equation for the friction coefficient as function of sliding speed and normal load has been obtained. Therefore, the experimental results offer important information to select the adequate artificial skin materials for robotic finger pads, often overlooked, with relatively simple shapes and mechanical properties typically used.
Temperature effect on the mechanical behaviour of niobium nitride thin films
Authors: Merie V V , Pustan M S , Negrea G , Bîrleanu C J , Crişan H G
Published: January 2020

Niobium nitride is used in a wide range of application due to its mechanical, physical, chemical, electrical and optical properties. The main aim of this paper is to deposit niobium nitride thin films by direct current magnetron sputtering and to characterize them at nanoscale. The films were deposited on silicon Si (100) substrates. Three types of films were deposited by modifying the deposition temperature. In this regard, some of the samples were deposited at room temperature (25 °C), some were deposited when the substrate was preheated at 200 °C, and the rest at substrate temperature of 400 °C. Regarding the topography of the samples, an increase in the average roughness was determined with the increase in deposition temperature. The nanoindentation tests were carried out at temperatures between 20 and 100 °C so that to emphasize the change in hardness and modulus of elasticity in terms of testing temperature. The results pointed out an important influence of both the deposition temperature and testing temperature on the topography, adhesion and mechanical properties of the niobium nitride thin films.
Thermophysical properties of SmTaO4, Sm3TaO7 and SmTa3O9 ceramics
Authors: Zhou Ying , Gan Guoyou , Ge Zhenhua , Feng Jing
Published: January 2020

SmTaO4, Sm3TaO7 and SmTa3O9 ceramics were prepared via a high temperature solid-state reaction. The results show that the phase structures of the SmTaO4 ceramics are a monoclinic phase (space group: I2 (5)), the Sm3TaO7 ceramics are an ordered orthorhombic phase (space group: Ccmm), and the SmTa3O9 ceramics are an orthorhombic phase (space group: Cmmm). Macromolecular and crystal structures of Sm3TaO7 and SmTa3O9 are more complex than those of SmTaO4, which can enhance phonon scattering and reduce thermal conductivity. Compared with those of SmTaO4 and SmTa3O9, Sm3TaO7 has the smallest grain size, indicating that a small grain size has an effect on strength and ensures material stability. Because of a distorted TaO6 octahedron and a high concentration of cation vacancy in the lattice of SmTa3O9, its thermal conductivity increases with increasing temperature. Compared with that of 7–8 YSZ, Sm3TaO7 has a low thermal conductivity (1.3–1.7 W·m−1·K−1 at 100 °C–900 °C), and its minimum thermal conductivity is nearly 30% lower than that of YSZ. The Sm3TaO7 ceramics have the highest TECs at approximately 9.82 × 10−6 K−1 at 1200 °C, which is close to that of 7–8 YSZ (approximately 10 × 10−6). This indicates that Sm3TaO7 has the potential to be employed as a thermal barrier coating.
Fabrication of magnetic and recyclable In2S3/ZnFe2O4 nanocomposites for visible light photocatalytic activity enhancement
Authors: Zhao Wenye , Huang Yun , Su Chunyan , Gao Yepen , Tian Wenhui , Yang Xudong
Published: January 2020

In this work, magnetic In2S3/ZnFe2O4 nanocomposites were fabricated via a two-step solvothermal process, which In2S3 loading amount on ZnFe2O4 support medium could be controlled by changing reaction mass. Investigation revealed that the photocatalytic activity of In2S3/ZnFe2O4 nanocomposites was uperior to pure In2S3 and ZnFe2O4 for the degradation of MB driven by visible light. The improved photocatalytic activity may be stemming from the synergy effect of In2S3 and ZnFe2O4, resulting in the enhanced visible light absorbance and higher separation efficiency of the photo-generated charge carriers. Significantly, this sort of nanocomposites could rapidly be separated through an external magnetic field, and five successive cycle experiments have proved that it was stable and recyclable. Finally, a possible mechanism related to the separation of charge and photocatalytic decomposition of MB was also provided.
Free vibration analysis of cracked functionally graded non-uniform beams
Authors: Shabani Shkelzen , Cunedioglu Yusuf
Published: January 2020

This paper presents the free vibration analysis of an edge cracked non-uniform symmetric beam made of functionally graded material. The Timoshenko beam theory is used for the finite element analysis of the multi-layered sandwich beam and the cantilever beam is modeled by 50 layers of material. The material properties vary continuously along the thickness direction according to the exponential and power laws. A MATLAB code is used to find the natural frequencies of two types of non-uniform beams, having a constant height but an exponential or linear width variation along the length of the beam. The natural frequencies of the beam are verified with ANSYS software as well as with available literature and good agreement is found. In the study, the effects of different parameters such as crack location, crack depth, power-law index, geometric index and taper ratio on natural frequencies are analyzed in detail.
Insulation performance analysis of novel high-temperature vacuum insulated panels with 2D and 2.5D braided structures
Authors: Wang Yang , Yang Jian , Chen Zhaofeng
Published: January 2020

In this paper, the thermal insulation performance and mechanism of novel High-temperature vacuum insulated panel (HTVIP) with 2D and 2.5D braided structures shell were compared and analyzed extensively. The effective thermal conductivity of 2.5D HTVIP ranged from 0.326 W m−1·K−1 to 0.748 W m−1·K−1 within the temperature from 25 °C to 900 °C is 12.4%–27.2% lower than the value of 2D HTVIP ranged from 0.368 W m−1·K−1 to 1.027 W m−1·K−1. The infrared images of both 2D and 2.5D HTVIP were also examined, which showed the 2.5D HTVIP has better thermal insulation performance. The thermal flow dynamic simulation of the HTVIP shows that the values of temperature at the center of the lower surface of the 2D and 2.5D HTVIP calculated by thermal simulation are 471 °C and 386 °C, respectively. And the heat flux density on the side of the 2.5D HTVIP is significantly lower than that of the 2D structure, the highest values are 163 KW m−2·K and 105 KW m−2·K, respectively.
The American Society for Clinical Pathology’s Job Satisfaction, Well-Being, and Burnout Survey of Laboratory Professionals
Authors: Garcia Edna , Kundu Iman , Kelly Melissa , Soles Ryan , Mulder Lotte , Talmon Geoffrey A
Published: January 2020

Objectives

To examine job satisfaction, well-being, job stress, and burnout among laboratory professionals.

Methods

The study utilized a cross-sectional survey design. The survey was administered online via the American Society for Clinical Pathology’s survey tool, to elicit information about job satisfaction, well-being, job stress, and burnout among medical laboratory professionals.

Results

Although this survey shows high job satisfaction among respondents, overall job-related stress is high and burnout is prevalent. The majority of the respondents rated their work-life balance as “fair.” The main contributing factors to job stress, burnout, and work-life balance are quantity of workload and understaffing.

Conclusions

Based on the results of this survey, creating targeted interventions may help improve the quality of well-being programs for laboratory professionals. A comprehensive wellness program developed at the institutional, local, and national levels may improve morale and alleviate the recruitment and retention challenges faced by medical laboratory professionals.
Dynamics of Cortical Local Connectivity during Sleep–Wake States and the Homeostatic Process
Authors: Miyazaki Takehiro , Kanda Takeshi , Tsujino Natsuko , Ishii Ryo , Nakatsuka Daiki , Kizuka Mariko , Kasagi Yasuhiro , Hino Hideitsu , Yanagisawa Masashi
Published: January 2020

Sleep exerts modulatory effects on the cerebral cortex. Whether sleep modulates local connectivity in the cortex or only individual neural activity, however, is poorly understood. Here we investigated functional connectivity, that is, covarying activity between neurons, during spontaneous sleep–wake states and during and after sleep deprivation using calcium imaging of identified excitatory/inhibitory neurons in the motor cortex. Functional connectivity was estimated with a statistical learning approach glasso and quantified by “the probability of establishing connectivity (sparse/dense)” and “the strength of the established connectivity (weak/strong).” Local cortical connectivity was sparse in non-rapid eye movement (NREM) sleep and dense in REM sleep, which was similar in both excitatory and inhibitory neurons. The overall mean strength of the connectivity did not differ largely across spontaneous sleep–wake states. Sleep deprivation induced strong excitatory/inhibitory and dense inhibitory, but not excitatory, connectivity. Subsequent NREM sleep after sleep deprivation exhibited weak excitatory/inhibitory, sparse excitatory, and dense inhibitory connectivity. These findings indicate that sleep–wake states modulate local cortical connectivity, and the modulation is large and compensatory for stability of local circuits during the homeostatic control of sleep, which contributes to plastic changes in neural information flow.
Persistence With Human Immunodeficiency Virus Pre-exposure Prophylaxis in the United States, 2012–2017
Authors: Huang Ya-Lin A , Tao Guoyu , Smith Dawn K , Hoover Karen W
Published: January 2020

Background

Daily oral pre-exposure prophylaxis (PrEP) is highly effective in preventing human immunodeficiency virus (HIV) infection if used adherently throughout periods of HIV risk. We estimated PrEP persistence among cohorts of persons with commercial or Medicaid insurance.

Methods

We analyzed data from the IBM MarketScan Research Database to identify persons aged 18–64 years who initiated PrEP between 2012 and 2017. We assessed PrEP persistence by calculating the time period that each person continued filling PrEP prescriptions until there was a gap in prescription fills > 30 days. We used Kaplan-Meier time-to-event methods to estimate the proportion of PrEP users who persisted with PrEP at 3, 6, and 12 months after initiation, and constructed Cox proportional hazards models to determine patient characteristics associated with nonpersistence.

Results

We studied 11 807 commercially insured and 647 Medicaid insured persons with PrEP prescriptions. Commercially insured patients persisted for a median time of 13.7 months (95% confidence interval [CI], 13.3–14.1), compared to 6.8 months (95% CI, 6.1–7.6) among Medicaid patients. Additionally, female sex, younger age, residence in rural location, and black race were associated with shorter persistence. After adjusting for covariates, we found that female sex (hazard ratio [HR], 1.81 [95% CI, 1.56–2.11]) and younger age (18–24 years: HR, 2.38 [95% CI, 2.11–2.69]) predicted nonpersistence.

Conclusions

More than half of commercially insured persons who initiated PrEP persisted with it for 12 months, compared to a third of those with Medicaid. A better understanding of reasons for nonpersistence is important to support persistent PrEP use and to develop interventions designed for the diverse needs of at-risk populations.
High-density lipoprotein (HDL), HDL2, and HDL3 cholesterol concentrations determined in serum of newborns, infants, children, adolescents, and adults by use of a micromethod for combined precipitation ultracentrifugation
Authors: Asayama K , Miyao A , Kato K
Published: January 2020

Cholesterol (C) concentrations in the two major subfractions of high-density lipoproteins (HDL2-C and HDL3-C) in sera from both sexes, ages ranging from newborns to adults, were measured by use of a micromethod for combined precipitation-ultracentrifugation. Sera were obtained from 91 boys, 68 girls, 15 healthy men, and 14 women. The HDL2-C concentration was higher in women than in men; the HDL3-C concentration was similar in these two groups. This sex-related difference, generally seen in adults, was found to begin at ages 11-15 y. The value of HDL2-C in females increased with age in a stepwise manner, whereas that in males increased up to ages 6-10 y but tended to decline thereafter. The HDL3-C concentration was higher in the adults than in the children. This micromethod for separating operationally defined HDL subfractions is of value for lipoprotein research in children.
Competitive binding enzyme immunoassay for zonisamide, a new antiepileptic drug, with selected paired-enzyme labeled antigen and antibody
Authors: Kalbe K , Nishimura S , Ishii H , Sunahara N , Naruto S , Kurooka S
Published: January 2020

We assessed the competitive binding between zonisamide (ZNS) in serum samples and beta-galactosidase-labeled ZNS derivatives, using competing antibodies to ZNS derivatives, and selected the best enzyme-labeled antigen and antibody for accurate enzyme immunoassay (EIA) of ZNS in serum without interference from its metabolites or from other antiepileptic drugs. This EIA, based on use of antibody linked to bacterial cell walls, has advantages over HPLC in simplicity, speed (50 samples per hour), and lack of requirement for special equipment. The concentrations of ZNS in serum as measured by the EIA correlated well with those by HPLC (n = 33, r = 0.977).
Thrombin-induced serotonin release as an in vitro indicator of the functional integrity of stored platelets
Authors: Hervig T , Vølundardottir T , Bakken A M , Farstad M
Published: January 2020

Measurements of endogenous serotonin and the thrombin-induced serotonin release reaction in platelet concentrates were compared with other methods of quality control: particle counting and pH and gas analyses. A discrepancy between the serotonin release reaction and the other data was observed after seven days of storage. The decline in the release reaction was not predictable from pH measurements or the number of platelets or leukocytes in the concentrate. There was a significant positive correlation between endogenous serotonin content and the thrombin-induced serotonin secretion after seven days of storage. We conclude that the current methods for routine control of platelet concentrates may not ensure the quality of the product after it has been stored for seven days. The thrombin-induced serotonin release may provide a valuable addition to the battery of tests available.
Improved purification of human lactate dehydrogenase isoenzyme-3 and studies with its fluorescein isothiocyanate and biotin conjugates
Authors: Weijers R N , de Bruijn R , Mulder J , Kruijswijk H
Published: January 2020

Lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) isoenzyme-3 (LD-3) has been isolated in milligram quantities from human erythrocytes. Using an improved procedure--which involves complete hemolysis of the erythrocytes, diethylaminoethyl (DEAE)-Sephacel column chromatography, and 5'-AMP-Sepharose 4B affinity chromatography--we obtained 23,000-fold purified isoenzyme from the crude hemolysate (overall yield about 90%). The final product was homogeneous on polyacrylamide disc gel electrophoresis and had a specific activity of about 435 kU/g. Its amino acid composition is presented. With the eventual aim to make visible and isolate IgA kappa antibody-secreting B lymphocytes, we developed reproducible methods for preparing fluorescein isothiocyanate isomer-1-conjugated LD-3 with a fluorescein/LD-3 molar ratio between 1.3 and 3.3, and biotinylated LD-3 with a biotin/LD-3 molar ratio between 1.3 and 2.5. In evaluating the stability of these two conjugates, we determined that they still can react with IgA kappa to form the IgA kappa (LD-3)2 complex.
A new enzyme immunoassay for prolactin in serum or plasma
Authors: Babiel R , Willnow P , Baer M , van Gent M , Ehrhardt V
Published: January 2020

This enzyme immunoassay (EIA) of human prolactin (hPRL) involves incubation of sample and anti-hPRL antibodies conjugated to horseradish peroxidase (EC 1.11.1.7) in tubes coated with a second antibody to hPRL. The test can be performed within 60 min. No reaction of the antibodies with human placental lactogen and human somatotropin is detectable. The presence of detergent allows assay of both serum and plasma. Precision was improved by including polyethylene glycol in the reaction mixture. To optimize analytical recovery, we added protease inhibitor. Assay of the EIA standards shows good correlation with results for World Health Organization reference preparations. The measurable range is 1 to 400 micrograms/L. Intra- and interassay CVs are about 5%. Comparisons with two RIAs and two other EIAs show reasonably good correlations. The components of our EIA are stable for 18 months.
Adenosine, inosine, and hypoxanthine/xanthine measured in tissue and plasma by a luminescence method
Authors: Jabs C M , Neglen P , Eklof B , Thomas E J
Published: January 2020

This simple method for sequentially quantifying hypoxanthine (HYP), inosine (INO), and adenosine (ADN) concentrations exploits the H2O2 peroxidase-catalyzed chemiluminescence of luminol. Though applied here only to tissue and plasma, this method can be adapted to analyze other body fluids. HYP in human plasma was stable for 30 min in 10 mmol/L EDTA reagent, whereas ADN was slowly converted to INO. Analytical recovery of HYP and INO added to plasma was 102% each; that of ADN was 95%. The within-run mean CVs for determinations of HYP, INO, and ADN at 1 mumol/L were 3.46%, 2.65%, and 3.01%; at 10 mumol/L they were 2.16%, 1.88%, and 1.63%, respectively. Corresponding between-run CVs were 5.34%, 4.09%, and 4.17%; and 3.43%, 2.40%, and 2.88%, respectively. Bilirubin at a concentration greater than 50 mumol/L interferes, but this interference is eliminated by bilirubin oxidase. Results for both tissue and plasma are compared with previously published results based on different analytical methods.
Quality management science in clinical chemistry: a dynamic framework for continuous improvement of quality
Authors: Westgard J O , Burnett R W , Bowers G N
Published: January 2020

Current quality assurance approaches will not be adequate to satisfy the needs for quality in the next decade. Quality management science (QMS), as evolving in industry today, provides the dynamic framework necessary to provide continuous improvement of quality. QMS emphasizes the importance of defining quality goals based on the needs and expectations (implied needs) of customers. The laboratory can develop customer-friendly goals and measures of quality by recognizing that customers' experiences are represented by a totality of results. Quality goals and measures are best communicated as "total performance" by specifying a limit and percentile of the distribution, rather than a mean and standard deviation. Application of quality goals within the laboratory will usually require partitioning the total performance goal into components and translating those components into specifications to guide the operation and management of production processes. QMS also extends beyond technical processes to people processes and provides guidance for improving the quality of worklife and caring for the laboratory's most essential resource--our people.