bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrofluoride Method of Complex Processing of Titanium-Containing Raw Materials
Authors: Gordienko P.S. , Dostovalov V.A. , Pashnina E.V.
Published: September 2017

The use of titanium dioxide is so diverse that varies from food to heavy industry and it is the main substance in the titanium industry. Over 90% of the world's mined titanium concentrates are processed to produce pigments. The sources for the production of titanium dioxide are the typically used titanium-containing ores including minerals rutile, ilmenite, and others. The volume of world production of titanium dioxide pigment exceeds 5 million tons per year and it is carried out in two ways: sulphate and chlorine (in approximately equal volumes). The changed approach to the green production processes requires the improvement of existing technologies and the development of new methods for processing titanium-containing raw materials. The authors have experimentally confirmed the high efficiency of complex, waste-free processing of titanium-containing raw materials developed by hydrofluoride. Creating pigment production on the basis hydrofluoride method will meet not only the domestic needs but also offer thepigment for export, as its parameters will surpass those of the best world analogues.
Applying the Electron Concentration Calculation Method to Assess the Influence of Hydrogen on the Position of the Variable Solubility Lines in Ti-Cr System
Authors: Popov Artemiy A. , Illarionov A.G. , Grib S.V.
Published: September 2017

A possibility of using the electron concentration calculation method to evaluate Acm and Ac3 temperatures in the Ti-Cr system alloys with different hydrogen content (0.15-0.93 wt %) is considered. It is found that the proposed method gives results similar to the experimental data only in the case of low hydrogen concentrations since it does not take into account the degree of hydrogen ion screening by electrons.
Comparative Assessment of Resistance of Hardwearing Anodes, Ternary Coated with Iridium, Ruthenium and Titanium
Authors: Fesenko L.N. , Pchelnikov I.V. , Fedotov R.V.
Published: September 2017

A selection of anode coatings has been studied to get sodium hypochlorite in low concentrationduring the electrolysis of 3% solution of sodium salt and the Black Sea water. The corrosive resistance of anodes has been determined, with different batches of ruthenium and iridium oxides, as well as their characteristics: chlorine outlet while passing throughthe current, voltage on the cell, the dynamics of concentration growth of available chlorine in solution.
Determining Undeformed Chip Thickness Models in Milling and its Verification during Wood Processing
Authors: Fomin A.A.
Published: September 2017

This paper presents a mathematical model of the maximum thickness and the chip area for the processes of cylindrical and profile milling of various materials, including wood. The analytical dependences connecting the geometry of the shear layer with the elements of the milling mode and cutter design parameters are determined. Also, a model of the volume of material removed from the surface of the workpiece during the milling profile is presented. The comparative calculations of the previously known models and the models developed by the author were done. It was found that the models of the geometric parameters of cutting layer presented in the article are adequate and can be used to calculate the energy performance of the wood milling process with cylindrical and shaping cutters. These models are suitable for use in the calculations of the processing parameters for a wide range of material: metals, wood, plastic, glass and others.
Multifractal Parametrization of Welded Joints Structure as an Instrument of Diagnostics and Detection of Defects
Authors: Poyarkova E.V. , Kuzeev I.R.
Published: September 2017

In each particular material the hierarchical peculiarities of defects indicate the corresponding hierarchical peculiarities of mechanisms of damage and limit states accumulation. In accordance with the points of view of V.S. Ivanova, V.V. Bolotin, A.A. Shanyavsky, L.I. Tushinsky, O.B. Naymark, V.V. Lepov, A.A. Bataev, the occurrence of the limiting state on a particular structural level is possible in case of accumulation on it of the ultimate concentration of defects of a certain kind. In such case the “established system” gets a new, additional degree of freedom, which promotes change of the prevailing mechanism of damage accumulation. The acceptability of this concept has been previously determined for a limited range of materials, which usually don’t have evident structural and mechanical heterogeneity. Thus, the extension of available results to the structurally heterogeneous materials and especially to the welded joints of such materials turned out to be a very difficult task. However, the concept of maximum (critical) level of damage accumulation on a particular scale level was introduced not so long ago. When assessing structural and mechanical heterogeneities of the structural material, an important role is played by concepts of similarity of mechanical phenomena, self-similarity of deformation and destruction processes and by the scale factor of reliability, which are considered in their historical development as a part of application of fractal concepts in the materials science. The application of complex synthesized approach (consisting of a set of diagnostic methods in the form of scanning electron microscopy and multifractal parametrization of materials microstructures) for detection of potentially hazardous zones of welded joints with the highest level of structural and mechanical heterogeneity was the main ideology of our study. In order to establish the cause-and-effect relationships of appearance of “macro-corrugations” on the surface of the material, the analysis of the structure of heterogeneous welded joints represented as a hierarchically organized system was performed.
External Factors Impact on Basic Properties of Hovercraft Skirt Materials
Authors: Yakimov A.K. , Butusova Ye.N. , Tumanin A.V.
Published: September 2017

The article is devoted to the research of the most common materials for air-cushion vehicles skirt (ACV, hovercraft). The paper presents the results of the impact various external factors have on hovercraft operational properties. The impact of temperature and operation time of the ACV on strength characteristics of these materials are investigated. The influence of prolonged soaking in fresh water on the adhesion of the coating was researched. It is noted that temperature variation strongly affects the tear resistance of the materials. It is shown that the strength properties and adhesion are significantly changed during the operation of the ACV. It is noticed that such changes are intrinsic to both materials. It is recommended to use the obtained results in the design of hovercraft skirts for the reliable prediction of their life.
GaN Materials Nanostructures Growth Control in the Epitaxial Units
Authors: Zhilenkov A.
Published: September 2017

The article overviews the results of the research into the peculiarities of GaN and AlGaN epitaxy from metal organic compounds, the influence of its peculiarities on the formation of GaN epitaxial layers and gives recommendations on the development of new methods for GaN epitaxial growth as well as on the research how they impact the characteristics of grown layers. The use of such semi-conductors allows obtaining full-color RGB light sources, increasing record density of a digital data storage device, getting high-capacity and efficient sources of white light. The electronic properties of such semi-conductors allow using them as a basis for high-power and high-frequency transistors and other electronic devices the specifications of which are competitive with those of SiC-based devices.
Hardening Kinetics of Geopolymer Binder Based on Magmatic Rock with Mineral Additives
Authors: Eroshkina N.A. , Korovkin M.O.
Published: September 2017

The influence of various factors on the hardening kinetics of composite geopolymer binders based on the milled waste of magmatic rock production and processing has been investigated. The type and dosage of the binder mineral additives - granulated blast-furnace slag and fly ash - as well as the composition of the hardening activator, component dispersion, and hardening temperature have been studied as the factors determining the rate of strength development. Some analytical dependencies describing the influence of the examined factors on the strength of geopolymer magmatic rock-based binders have been developed. The dependencies developed were used to establish the requirements for process conditions of the geopolymer construction products and structures production.
Influence of Constant Magnetic Field on Domain Wall Dynamics in YFeO3
Authors: Komina O.Yu. , Zhukov E.A.
Published: September 2017

The work presents the experimental results of the dynamics of the domain wall in the plate of yttrium orthoferrite. In our case the speeds of this motion are much less than the speeds of sound in these crystals. A constant magnetic field was oriented parallel to the plate along the domain wall motion and at the angle ≈ 50° to the sample plane and parallel to the plate along the DW motion. We consider forced vibrations of the domain wall under the influence of weak alternating magnetic fields. The domain walls motion was caused by an alternating magnetic field, which was generated by the coils. The effect of the constant magnetic field on the domain wall dynamics has been found.
Assessment of Welded Joints Structure Defectiveness Based on the Presence of Non-Metallic Inclusions
Authors: Poyarkova E.V. , Kuzeev I.R. , Zabelin K.L.
Published: September 2017

Both welded joints and base metal are arranged at different structural-scale levels. Unlike the base metal, welded joint can have structural inclusions of complex composition and spatial geometry. During simulation and forecasting of behavior of various characteristics and properties, welded joints quality assessment is not possible without performance of corresponding metallographic studies. The article discusses the non-metallic inclusions in the oxide and silicate types welding joints and their influence on the formation of the metal mechanical properties.
Limiting Product Surface and its Use in Profile Milling Design Operations
Authors: Fomin A.A.
Published: September 2017

The article establishes the analytical relationships linking the geometric parameters of the shaping cutters. A mathematical model describing the geometrical errors caused by the discrete process of product profile milling with shaping cutters was developed. It was specified based on the model that the distribution of errors on the surface treated with cylindrical and shaping cutters is significantly different. It is found that the errors due to the kinematics of the cylindrical milling process, are constant at value irrespectively of the considered cross section of the cutting tooth, and the errors after the milling significantly differ in the distance function of considered transverse plane from its geometric center. The maximum error occurs in the local longitudinal planes of the product, the profile of which is located at the maximum distance from the mounting technological base of product's surface. The plane of the product, where the maximum geometrical errors are formed during the profile milling is called limiting surface. The design of technological process is performed in the product profile geometry, formed in this plane. The rule of spacious arrangement location of the limiting surface of the product according to its drawing. Using the limiting surface in the design of the operation of profile milling with shaping cutters significantly reduces the duration of the design procedure and eliminates the cost of production on experimental studies related to ensuring the geometric accuracy of products at the initial stage of their production.
New Material Creation by Phase Separation in Liquid Mixtures Induced by Non-Uniform Electric Field
Authors: Volkova T.A. , Aletdinov R.F. , Fedosov E.M.
Published: September 2017

The fractionation technology of liquid mixtures under the action of an externally applied inhomogeneous electric field and the device – a capacitive electromechanical energy transducer that implements this technology are considered in this article. The operational principle of a capacitive electromechanical energy transducer with liquid rotor is described. The conclusion on the possibility of applying this technology to the fractionation of oil containing emulsions is made.
New Method of Quench Surface Turning
Authors: Zubkov N.N. , Vasil'ev S.G. , Poptsov V.V.
Published: September 2017

The heating, generated in the process of deformational cutting without chip separation used for phase transformation in steel during lathe machining. Chips are not separated from the workpiece and remain on the surface thus forming a special reinforced structure. The result of processing is a steel surface quenching up to 1 mm deep. The proposed method also makes it possible to obtain hardened surface structures with alternating inclined layers of different hardness. The article presents calculations of heating and cooling rates, types of hardened structures, hardness investigation of hardened steel surfaces.
On Deformation Powers of the Explosion Welded and Rolled Titanium-Aluminium Composite
Authors: Gurulev D.N. , Palatkina L.V. , Gonik I.L.
Published: September 2017

Received by explosion welding titanium-aluminum billet can be subjected to various operations of metals processing by pressure, which results in change of metals mechanical properties and the arrangement of the layers. The work investigated the influence of temperature on the deformation ability of titanium-aluminum layer composites by rolling. It is revealed that the deformation capacity of the layered titanium-aluminum composite is determined by the plastic properties of aluminum layers at the temperature of rolling. At 450 °C a sharp increase in strain capacity of titanium-aluminum composite is revealed.
Research into the Structure of Aluminum Matrix Composite АK12+2.38%Cu+0.06%SiC with a Scanning Probe Microscope
Authors: Voronin S.V. , Chaplygin K.K. , Litoshina A.D. , Konovalov Sergey V.
Published: September 2017

The paper provides an overview of the results obtained when using the method of scanning probe microscopy for exploring surfaces of aluminum matrix composite (АC12+2.38%Cu+0.06%SiC) and modified aluminum alloy (АL2) samples with nanohardness measuring device “NanoScan-3D”. The authors describe a calibration process of the device, which was implemented via precise positioning the optical axis of nanohardness measuring device “NanoScan-3D” with the indenter axis. The paper highlights that the structure images of materials under study obtained in the process of optical metallographic tests are similar to results of scanning probe microscopy. The second major finding is that the modules of elasticity of phase components in materials АC12+2.38%Cu+0.06%SiC and АL2 can be appropriately measured using the method of scanning probe microscopy with nanohardness measuring device “NanoScan-3D”. The paper identifies that modules of elasticity of alpha solid solution grains, eutectic and released silicon are comparable in aluminum matrix composite АC12+2.38%Cu+0.06%SiC and modified aluminum alloy АL2. The authors also point out the convergence of modules of elasticity in the zones with embedded particles of silicon carbide with the data given in literature. The paper reports practical approval of the procedure for detecting the strengthening particles of silicon carbide in aluminum matrix composite АC12+2.38%Cu+0.06%SiC using the method of scanning probe microscopy with device “NanoScan-3D”.
Engineering Analysis Methods for Hydraulic Shell Structures with Infill
Authors: Tsimbelman N.Ya. , Chernova T.I. , Shalaya T.E.
Published: September 2017

The article examines the history of development and state-of-the-art of the design theory of structures of filled shells delivered in “Civil Engineering” specialist, MSc, and postgraduate engineering disciplines courses. The analysis of the engineering design methods based on the theory of shells propositions has been performed. Structural numerical model field of application expansion has been proved. The obtained parameters and proposed methods can be used in numerical simulations using finite element method to analyze and design the thin shell structures with soil infill. The propositions reflecting state-of-the-art of the design theory of the structures under consideration have been set; their place in the logic of delivering engineering disciplines taught to civil engineering students has been designated.
Influence of Intermetallics on Complex Alloyed Brass Hardness
Authors: Mysik R.K. , Sulitsin A.V. , Brusnitsyn S.V.
Published: September 2017

The results of the study of phase composition, structure, and properties of multi-component complex alloyed wear-resistant brass are presented. The material contains aluminium, manganese, silicon, nickel, and chromium besides copper and zinc. A review of the influence of these components on the formation of intermetallics with different chemical composition and morphology is made. Based on the analysis it is revealed that the wear resistance of brass is highly dependent on the ratio of α-and β-phases and the volume fraction of the intermetallic particles. Chemical X-ray fluorescence, scanning electron microscopy (SEM) and electron-probe microanalysis (EPMA) are used. Based on the experiments it is established that alloys without chromium contain rod-shaped intermetallics based on Mn-Si compound with a ratio of length to cross sectional dimension 2–4. These intermetallics create the effect of anisotropy in an alloy. The presence of chromium in an alloy leads to the formation of equiaxial intermetallics with the chromium silicide core and manganese silicide coat; in this case the alloy is isotropic. It is established with metallographic study that the density of intermetallic compounds distribution of 50–130 thousand particles per 1 mm3 is required to archive the 291–298 HB hardness of brass. Cast ingots are made following the semi-casting method and then pressed to tube bars; the finished products are made by stamping so, the production technology can improve the mechanical characteristics of alloy.
Influence of Chemical Composition of Tough-to-Machine Materials on Grinding Technologies
Authors: Ivanova T.N.
Published: September 2017

The main purpose of processing of tough-to-machine materials is improving of cutting process of steels with different physicochemical properties and alloying by means of various chemical elements in combination with heat treatment. Producing of high quality surface layers depends on properties of material used to make details, that is why reasons of tough machining were identified: influence of chemical composition and resulting structure. The studies of grinding of tough-to-machine materials were undertaken by means of grinding wheels made from synthetic diamonds as they are most resistant and highly-productive. Based on the studies recommendations for using of characteristics of grinding wheels and tough-to machine steel grades.
Impact of Cooling Character on Structure and CTE of Invar Alloy with 0.6%C
Authors: Zhilin A.S. , Grachev S.V. , Nikiforova S.M.
Published: September 2017

Metallography analysis of invar alloys crystallized with different cooling rates has been carried out. The study has demonstrated that velocity of crystallization has an impact on the dispersity of graphite. The higher velocity of cooling, the more dispersive graphite is. The volume percentage of graphite in alloy, crystallized with high cooling rate, is lower than compared with low cooling rate. Crystallization with low cooling rate leads to the reduction of the amount of carbon into γ-phase. The coefficient of thermal expansion is basically depends on the amount of carbon into γ-phase.
Method for Describing Fatigue Processes in Structural Materials
Authors: Mironov V. , Lukashuk O. , Vichuzhanin D.
Published: September 2017

The article studies one of the methods for phenomenological description of fatigue processes in structurally-inhomogeneous structural materials. The initial statement about the interrelationship between the static and cyclic material properties is investigated using the complete stress-strain curves or diagrams method (CSSD). Based on the analysis of the mathematic modeling results, the interrelationship is predicted to exist between the highly-localized fatigue process in a structurally-inhomogeneous material and the degradation of a static CSSD for a macroscopic specimen. It is noted that the conditions under which the specimen fails in a testing machine are similar to the ones for the material in a construction. Then the results are given for the direct experimental testing of the model predictions, illustrated with the examples of cyclic degradation of several structural materials. The tests on multiple-cycle fatigued specimens reveal degradation of several mechanical properties. The justification for the selection of the available plasticity of a material as a parameter representative of the fatigue process is given. The authors describe a few examples of building one-parameter cyclic degradation models for steels and some prospects of using the complete strain-stress diagrams for various purposes.
Magnetic and Microstructural Properties of Cobalt Substituted NiZn Ferrite Powders
Authors: Knyazev A.V. , Lähderanta E. , Zakharchuk I.A.
Published: September 2017

This paper presents the results of magnetic and microstructural study of cobalt-substituted NiZn ferrite powders, Ni0.5Zn0.3Co0.2Fe2O4, synthesized with the solid-state reaction method. The lattice parameter decreased with Co substitution, as the ionic radius of cobalt is less than that of zinc. Raman spectroscopy showed clear peaks of the A1g, Eg, and F2g modes, revealing cubic spinel structure and good crystallinity of the samples. The saturation magnetization reduced in the substituted sample to 50.28 emu/g at room temperature. In comparison to the bulk ferrite, the powder sample showed pronounced coercivity even at room temperature. The temperature dependence of the magnetization had superparamagnetic curvature, which yielded the effective anisotropy constant equal to 8.832 kJ/m3.
Investigation of the Equilibrium Germanium-Substituted Wustite with Metal and Spinel Solutions in the Fе-Gе-O System
Authors: Shtin S.V. , Lykasov A.A.
Published: September 2017

The phase equilibrium in the Fe-Ge-O system is investigated by measuring EMF of galvanic elements with solid oxygen-conductive electrolytes. The samples for investigation were prepared by the solid phase reaction at 900 °C. The samples were analyzed to determine the total and phase composition. The gross composition of the samples was refined by chemical analysis. The iron content was determined by the standard method of bichromatometric titration, while that of germanium was determined by the photometric method, which is based on measuring the optical density of the colored colloid solution of germanium phenyl fluoronate, which is formed upon the interaction of germanium dioxide with phenylfluorone in the acidic medium. The phase composition was established using X-ray diffractometry and electron probe microanalysis using a DRON-3 diffractometer and a JEOL JSM-6460LV computer controlled scanning (raster) microscope. The experimental function of EMF galvanic elements of temperature is formulated. After processing the obtained data, the equilibrium oxygen pressures over the samples were calculated, the solubility of germanium in iron monoxide (wustite) was determined, the phase composition of the regions bordering the wustite region was established, the isothermal sections of the state diagram of the system were constructed at 1173 and 1273 K in the equilibrium region of the wustite solution with metallic and spinel phases
Strengthening Mini Silo Construction Made of Reinforced Concrete Blocks with Carbon Fiber Lamellae
Authors: Mayatskaya I.A. , Fedchenko A.E. , Zagutin D.S.
Published: September 2017

The use of prefabricated mini silo structures enables us to build containers for grain or animal feed and to transport the structural elements to the installation site. Traditional types of strengthening of concrete structures are steel and concrete cages. Polymer materials are widely used in construction. The methods of strengthening modern materials, such as lamellae, are being increasingly used. The issue of strengthening the structures with composite polymer materials is relevant.
Thermodynamic Modeling of Phase Equilibrium in Fe-Y-Cr-C-O Liquid Metal System
Authors: Mikhailov G.G. , Makrovets L.A.
Published: September 2017

The thermodynamic characteristics of processes in the liquid metal system Fe–Y–Cr–C–O are considered as applied to low-carbon and low-alloy metal. The critical parameters for the state diagram of the oxide system Y2O3–Cr2O3 were established based on the values quoted in literature. The temperature dependence of the melting reaction constant Y2O3·Cr2O3 was determined. The coordinates of eutectic transformation points for the system Y2O3–Cr2O3 were calculated. In accordance with subregular solution theory, the energetic parameters which are necessary to calculate the activities Cr2O3 and Y2O3 of oxide melts in the system Y2O3–Cr2O3 were determined. The energetic parameters of subregular solution theories for the oxide system FeO–Cr2O3–Y2O3 were determined based on the values for the binary systems FeO–Y2O3, FeO–Cr2O3 and Y2O3–Cr2O3. The view of this diagram, as coupled with the existence domain of liquid metal within the framework of the quaternary system Fe–Y–Cr–O–С, suggests that low-carbon chromic liquid metal when injected with yttrium can form the following non-metallic inclusions: |Cr2O3|, |Y2O3|, |FeO·Cr2O3|, |Y2O3·Cr2O3| or oxide melt (FeO, Y2O3, Cr2O3). Oxide melt may contain up to 2 % of divalent chrome (Cr2+). The equilibrium constants for the main reactions of steel deoxidation with the formation of liquid, solid and gas products of chemical reactions were also established. The activity of components dissolved in metal was calculated using interaction parameters. The set of derived expressions for the activity of components and the dependences of equilibrium constants of chemical reactions and phase transformations allowed us to diagram the surface of component solubility in liquid metal (SCSM). SCSM diagrams show the compositions of liquid metal and indicate oxide phases which are in equilibrium with liquid metal.
Strengthening Building Structures with Polymer Composite Materials
Authors: Mayatskaya I.A. , Fedchenko A.E. , Demchenko D.B.
Published: September 2017

One of the work cycles of reinforced concrete structures is the state of repair and reconstruction, including the steps of strengthening elements. The traditional types of strengthening of reinforced concrete which are steel and concrete collars and shirts - now are receding into the background. New methods of strengthening with modern materials such as lamellae are increasingly being used. The article deals with the issues related to strengthening the structures made of high-strength concrete using composite polymeric materials.
Effect of Continuous Casting Parameters on Quality of Billets Manufactured by UMMC Steel LLC
Authors: Kalitaev A.N. , Tutarova V.D. , Shapovalov A.N.
Published: September 2017

The analysis of the production records on casting 150õ150mm billets at UMMC Steel LLC has made it possible to define the basic factors worsening the billet quality and increasing the rejection of the rolled materials: steel casting in case the sulfur and phosphorus content exceeds 0.015 % and overheat is more than 30°Ñ. In order to minimize the formation of local nonuniformity in the billets manufactured from low carbon and medium carbon steel, open cast by CCM, it is necessary to maintain a maximum [Mn]:[S] ratio with [Mn]:[Si] ratio at the level less than 2-3, which ensures the formation of fusible deoxidation products and prevents the formation of solid conglomerates in steel. In order to reduce the formation of axial porosity it is advisable to retain the carbon content at the lower limit for the steel grade and avoid overheating of steel above the specified values. In order to minimize the consequences of the overheated steel casting it is necessary to adjust the billet casting rate in accordance with the operating procedures.
Influence of Concrete Mix Transportation with Inertia Conveyor on Concrete Properties
Authors: Osmanov S.G.
Published: September 2017

The practical expediency of the study of physical and mechanical properties of concrete, received from the mix, exposed at its feeding to the point of placement to the transportation with the inertia conveyor by means of original technology, which shows its competitiveness at factories producing precast concrete units, is proved. The experimental procedures of the research performed by the authors, where they analyzed the process of transportation relating to the use of ready-mix concrete on the dense aggregate, are described. The data on the effect of received previously rational values of the major parameters of engineering process studied (the parameters of asymmetric oscillations of work member of the conveyor and the thickness of the mix layer moved by it) both on the homogeneity of fresh concrete and the strength and strength homogeneity of hardened concrete are represented and analyzed.
Force Interaction of Technological Tool and Elastic-Plastic Link at Large Diameter Tubes Preliminary Forming
Authors: Chechulin Yu.B. , Pesin Yu.V. , Boklag N.Yu.
Published: September 2017

The sustainability of the manufacturing process and quality improvement of the longitudinal electric-welded large diameter tubes, produced from the U-shaped workpiece, is determined based on a science-based approach to the parameters selection and the preliminary press forming technological tool settings. For this purpose we developed a software system that allows interactively performing multiple calculations of the kinematics and press equipment energy-power characteristics in the interaction of mutually movable links of the supporting rocker mechanism with a punch through the forming workpiece, presented in the form of elastic-plastic link. As a result of the study of forming workpiece stress-strain state and the mechanism force analysis, dependence of the equipment maximum loads in function of the geometry, size and setting instrument parameters, the forming tube size and material is determined. Physical modelling of the press forming process was performed to analyze the influence of these factors on the maximum load value. The forces perceived oscillating rocker stand and videogram of the process were recorded during physical modelling. Experimental data matches with the results of the developed software calculation with a precision of 12%. An original modular tool with variable geometry is proposed. It is shown that the use of the two-radius punch construction allows to reduce the maximum loads magnitude during preliminary forming by 30% and, therefore, to reduce the load of the whole technological tool. In addition, the possibilities to receive U-shaped products with high precision and predetermined shape parameters are expanded.
Heat Treatment of Low-Alloyed Steel up to Grade Q125
Authors: Iyengar S. , Bogomolov A.V. , Zhakupov A.
Published: September 2017

This work investigates the problem of how to reduce the prime cost of Grade Q125 Group 4 casing and tubing according to API 5CT and proposes process solutions to resolve it, consisting in the enhancement of series of mechanical properties without chemical alloying of steel with expensive elements such as chromium, molybdenum, vanadium, niobium and boron. During the investigation the process parameters of 9MnSi5 low-alloy steel heat treatment were developed, which confirmed the efficiency of this technology providing high values of strength and yield strengths which are minimum 931 MPa and 862 MPa respectively; at the same time maintaining the required cold resistance and resistance to hydrogen cracking of pipe. The suggested process parameters were based on heat cycle quenching with heating in induction furnace up to 1050–1100°С, 880–900°С and 740–780°С accordingly at each cycle and cooling rate in each case equal to 50°С/sec, during which the uniform martensite grain size ranging from 5 to 10 micron was obtained.
Association of HLA antigens with the clinical course of sarcoidosis and familial disease
Authors: Yanardag Halil , Tetikkurt Cuneyt , Bilir Muammer , Yılmaz Erkan
Published: September 2017

Patients with sarcoidosis usually have a benign course and a favourable prognosis. Although spontaneous remission is common, a progressive disease with a severe prognosis occurs in a small but significant number of patients. The aim of this study was to evaluate the potential significance of HLA antigens as a clinical marker on the outcome of sarcoidosis patients. We conducted a retrospective cohort study for HLA class I and II allels in 74 sarcoidosis patients and 72 healthy transplant donors. Bronchoscopy and bronchial biopsies were performed in each patient. Two or more positive bronchial biopsy samples revealing granulomatous inflammation was defined as diffuse while one positive biopsy sample was considered as limited endobronchial disease. Three or more extrapulmonary organ involvement was denoted as severe extrapulmonary disease. The patients were followed-up at least for eight years.  Incidence of progressive disease was significantly high in patients with positive HLA-DRB1*07, DRB1*14 (p<0.05) and DRB1*15 (p <0.001) allels. HLA-DRB1*14 and DRB1*15 were associated with severe extrapulmonary organ involvement (p<0.001). HLA-DRB1 *14 (p<0.05) and DRB1*15 (p<0.001) were significantly more frequent in patients with diffuse endobronchial involvement. Incidence of familial disease was 14.8% with a 6.7% identical HLA typing. Presence of HLA class I and II allels may influence the severity and prognosis of sarcoidosis significantly. Apart from defining genetic susceptibility, HLA class I and class II allels appear to be relevant and crucial markers for the to predict the clinical outcome of sarcoidosis. Distinct heterogenity of sarcoidosis may arise from the particular presence of different allels in invidual patients. 
Development of wheelchair caster testing equipment and preliminary testing of caster models
Authors: Mhatre Anand , Ott Joseph , Pearlman Jonathan
Published: September 2017

Background: Because of the adverse environmental conditions present in less-resourced environments (LREs), the World Health Organization (WHO) has recommended that specialised wheelchair test methods may need to be developed to support product quality standards in these environments. A group of experts identified caster test methods as a high priority because of their common failure in LREs, and the insufficiency of existing test methods described in the International Organization for Standardization (ISO) Wheelchair Testing Standards (ISO 7176).Objectives: To develop and demonstrate the feasibility of a caster system test method.Method: Background literature and expert opinions were collected to identify existing caster test methods, caster failures common in LREs and environmental conditions present in LREs. Several conceptual designs for the caster testing method were developed, and through an iterative process using expert feedback, a final concept and a design were developed and a prototype was fabricated. Feasibility tests were conducted by testing a series of caster systems from wheelchairs used in LREs, and failure modes were recorded and compared to anecdotal reports about field failures.Results: The new caster testing system was developed and it provides the flexibility to expose caster systems to typical conditions in LREs. Caster failures such as stem bolt fractures, fork fractures, bearing failures and tire cracking occurred during testing trials and are consistent with field failures.Conclusion: The new caster test system has the capability to incorporate necessary test factors that degrade caster quality in LREs. Future work includes developing and validating a testing protocol that results in failure modes common during wheelchair use in LRE.
The Black Atlantic as reversal: A reappraisal of African and black theology
Authors: Engdahl Hans
Published: September 2017

In this article, I will try to do three things. Firstly, pay attention to the notion of Black Atlantic as coined by Paul Gilroy, which in effect could signify a reversal of colonialism and slavery. Secondly, revisit the 1970s and the debate about the relevance of Black theology vis-à-vis African theology, using John Mbiti’s article ‘An African Views American Black Theology’ as entry point. Here, I will discuss contributions also made by Desmond Tutu and James Cone. Thirdly, starting with the premise that both theologies are relevant and soul mates today, which would (probably) be confirmed by all the above mentioned at this point in time, an assessment of current voices will be made, that is, Tinyiko Maluleke and Vuyani Vellem on black and African ecclesiologies from a South African perspective, and Lawrence Burnley on the fate of the Black Church in the United States.
The notion of autobiographical form redefined
Authors: Snyman Elizabeth
Published: September 2017

No abstract available.
Prevalence of eye pathology in a group of diabetic patients at National District Hospital Outpatient Department in Bloemfontein, South Africa
Authors: Cairncross Joleen P. , Steinberg Wilhelm J. , Labuschagne Mathys J.
Published: September 2017

Background: Diabetic retinopathy is the third most common cause of blindness after cataracts and glaucoma in South Africa. Primary healthcare interventions providing eye care services play an important role in preventing complications.Aim: To determine the prevalence of eye pathology in a group of diabetic patients at National District Hospital by screening for diabetes-associated ocular pathology.Setting: Outpatients Department run by Department of Family Medicine at National District Hospital in Bloemfontein from June to July 2014.Methods: Interviews were used to collect information regarding diabetic patients’ history of diabetes mellitus and if and when previous diabetic retinopathy screening was performed. Visual acuity was assessed, intra-ocular pressure measured and a non-mydriatic digital fundus camera used to screen for retinal pathology.Results: During the last year, only 4.5% of patients had their vision checked with a Snellen chart, and 16.5% were examined with an ophthalmoscope. Since diagnosis of diabetes, only 15.5% of patients were referred to an ophthalmologist. Patient referral was needed for 87 (42.9%) cases for refractive disorders, 37 (18.2%) for suspected glaucoma, 30 (14.8%) for cataracts, and 22 (10.8%) for diabetic retinopathy.Conclusion: This study confirms that glaucoma, cataracts and diabetic retinopathy are prevalent eye conditions among diabetic patients. Offering eye screening at primary healthcare level may contribute to early detection of eye pathology and timeous referral for sight-saving treatment.
Geographical distribution and profile of medical doctors in public sector hospitals of the Limpopo Province, South Africa
Authors: Ntuli Samuel T. , Maboya Edwin
Published: September 2017

Background: The shortage and unequal distribution of medical doctors in low- and middle-income countries continues to be a public health concern.Objective: To establish the geographical distribution and demographic profile of medical doctors in public sector hospitals of the Limpopo Province, South Africa.Method: The PERSAL system was used to obtain information on the number of medical doctors employed in public sector hospitals of the Limpopo Province. Data were exported from PERSAL’s database and then analysed using STATA version 9.0.Result: The mean age of the 887 medical doctors was 40.1 ± 11.2 years (range 24–79 years). Sixty per cent of the doctors were male, 66% were aged ≤ 45 years and 84% were African. Most of the doctors (86%) were medical officers, of which 55% had < 5 years working experience. Overall, the doctor-to-population ratio for the five districts in the province was 16.4/100 000, with Capricorn (33.7/100 000) and Waterberg (20.2/100 000) recording the highest ratios. A large proportion (43%) of medical officers are employed in the Capricorn District, of which 71% were practising at the tertiary hospital.Conclusion: This study demonstrated a shortage and maldistribution of medical doctors in the public sector hospitals of the Limpopo Province. This has a potentially negative effect on the delivery of an appropriate and efficient healthcare service to the population and requires urgent attention.
Decentralised training for medical students: Towards a South African consensus
Authors: De Villiers Marietjie R. , Blitz Julia , Couper Ian , Kent Athol , Moodley Kalavani , Talib Zohray , Van Schalkwyk Susan , Young Taryn
Published: September 2017

Introduction: Health professions training institutions are challenged to produce greater numbers of graduates who are more relevantly trained to provide quality healthcare. Decentralised training offers opportunities to address these quantity, quality and relevance factors. We wanted to draw together existing expertise in decentralised training for the benefit of all health professionals to develop a model for decentralised training for health professions students.Method: An expert panel workshop was held in October 2015 initiating a process to develop a model for decentralised training in South Africa. Presentations on the status quo in decentralised training at all nine medical schools in South Africa were made and 33 delegates engaged in discussing potential models for decentralised training.Results: Five factors were found to be crucial for the success of decentralised training, namely the availability of information and communication technology, longitudinal continuous rotations, a focus on primary care, the alignment of medical schools’ mission with decentralised training and responsiveness to student needs.Conclusion: The workshop concluded that training institutions should continue to work together towards formulating decentralised training models and that the involvement of all health professions should be ensured. A tripartite approach between the universities, the Department of Health and the relevant local communities is important in decentralised training. Lastly, curricula should place more emphasis on how students learn rather than how they are taught.
Maternity and paternity leave and career progression of black African women in dual-career couples
Authors: Motaung Lucky L. , Bussin Mark H.R. , Joseph Renjini M.
Published: September 2017

Orientation: The study focused on examining the perceptions of dual-career couples at a stateowned company about the influence of taking maternity and paternity leave on the career progression of black African women in middle management and leadership occupations.Research purpose: The primary purpose of the study was to identify core barriers in relation to maternity and paternity leave that contribute negatively in the career progression of black African women in dual-career couples.Motivation for the study: To obtain insight into the underrepresentation and progression of black African women within dual-career couples, in middle management and leadership occupations.Research design, approach and method: This study was qualitative, comprising a sample of 10 black African women and 10 black African men, with data collected through in-depth semistructured interviews. Thematic analysis was utilised to analyse the interview dialogues.Main findings: The findings established that taking maternity leave has a negative influence on the career progression of black African women in dual-career couples at the state-owned company. The participants further confirmed that involuntary time off work and productiveness were principal influencing barriers of taking maternity leave, leading to other undesirable consequences, such as unproductiveness and reliability.Practical and managerial implications: The state-owned company should review its current talent management and recruitment and selection policies, in order to positively contribute to increasing the representation and facilitating career progression of black African women within dual-career couples, in middle management and leadership occupations.Contributions or value-add: Insights were provided on the influences of taking maternity and paternity leave in the underrepresentation and progression of black African women within dual-career couples, in middle management and leadership occupations.
Organisational change and the psychological contract at a pharmaceutical company
Authors: Magano Kelebogile D. , Thomas Adèle
Published: September 2017

Orientation: Over a period of 6 years, a South African pharmaceutical company had been involved in several mergers and acquisitions. These changes had proved difficult for staff and staff attrition had risen.Research purpose: The objective of the study was to explore the perceptions of senior managers about the impact of change on the psychological contract. The sub-objectives were to determine what organisational factors contribute to changes in the psychological contract during periods of change, and the implications of the breach of the psychological contract for the company and its employees.Motivation for the study: As the company was set to embark on further mergers and acquisitions, the opinions of senior managers about how such changes should be addressed are important for the company.Research design, approach and method: A case study approach was used in this qualitative study. The population comprised 60 senior managers of whom 12 were purposefully selected for inclusion in the study. A semistructured interview schedule was used to capture the views of these managers and themes were extracted by means of content analysis.Main findings: Seven themes emerged which encapsulated the perceptions of senior managers about the impact of change on the psychological contract during periods of mergers and acquisitions – lack of communication, an absence of planning, lack of employee engagement, less than optimal human resources involvement, lack of preparation of the organisational culture and poor change management processes. These factors need to be addressed to strengthen the psychological contract of employees during periods of change.Practical/managerial implications: The study highlighted areas that leaders and managers of the company should consider when embarking on mergers and acquisitions if the psychological contract of employees is not to be negatively impacted.Contribution: While caution must be exercised in the generalisation of the findings, companies in the same industry or those in other industries could use the findings as points of departure for considering the elements that should be addressed in change initiatives.