bluuebunny/crossref_metadata_2025 huggingface dataset:
Forging of Copper and Iron Plates by the Damascus Technique
Authors: Strobl Susanne , Scheiblechner Wolfgang , Haubner Roland
Published: June 2019

Forging of different steel grades is called Damascus technique and results in a layered composite material termed “Damascus steel”, but forging of different copper alloys is termed “mokume gane”. In this paper the joining of copper and iron plates by forging is described. Metallographic investigations showed well bonded interfaces of copper and iron. A very small diffusion zone was observed. To study the diffusion between copper and iron two heat treatments were performed in Ar atmosphere. After 30 minutes at 1000 °C a marginal Cu-Fe interaction took place. Above the melting point of Cu at 1100 °C an intense Cu-Fe interaction was observed, which significantly changes the interface of both metals. Cu penetrated Fe along the grain boundaries and Fe droplets were formed sporadically. This correlates with the typical morphologies of liquid metal embrittlement (LME). Moreover, Fe is dissolved in Cu at 1100 °C and after cooling fine Fe precipitates in the Cu phase were detected.
Lightweight Potential of 3D Endless Fiber Reinforcement of Polyurethane Foam Cores with Spacer Fabrics in Hybrid Sandwich Structures with Fiber Reinforced Thermoplastic Facings
Authors: Schäfer Kay , Nestler Daisy , Jahn Kristina , Jentzsch Henrik , Kroll Lothar
Published: June 2019

Sandwich structures consisting of fibre-reinforced plastic (FRP) facings and core are ideally suited as substitution materials for reducing component masses. The endless fibre reinforcement has the greatest performance potential. Both thermoset and thermoplastics are already being processed into endless fibre-reinforced sandwich facings according to the state of the art. The 3D endless fibre reinforcement of cores is a current research topic. This paper describes the development of a hybrid sandwich consisting of thermoplastic composite facings and an innovative core composite. This is made of polyurethane (PUR) rigid or flexible foam, which is reinforced with spacer fabric. The sandwich manufacturing in Reaction Injection Moulding (RIM) includes the original forming of the core and the simultaneous bonding of the facings. This efficient process offers the potential for the production of such complex structures in medium or large series. The sandwich structures and their individual components were characterised in the standardised compression and bending test. The lightweight potential of spacer fabric reinforcement is demonstrated by comparing the specific mechanical properties of sandwich structures with and without core reinforcement. In comparison to reinforced and unreinforced foams, the effect of sandwich design is also shown.
Investigation on the Crack Evolution in Glass-Fiber Laminates Depending on the Stacking Sequence
Authors: Begemann Benjamin , Horst Peter
Published: June 2019

In this paper experiments on the fatigue behavior of flat and tubular Glass Fiber Reinforced Plastics (GFRP) specimens with three different layups ([0/905/0], [0/902/01/2]s and [0/±45/01/2]s) are presented. The experiments are conducted to study the mechanics under cyclic tension-tension loading (R=0.1) until crack saturation (CDS). Fatigue testing is performed below the critical static load level where first matrix cracks can be observed. Therefore Load Levels (LLs) are derived from crack evolution curves obtained by static tests under usage of transmitted light photography. The shear lag model of Berthelot [1] is applied to the two cross-ply specimens to predict crack evolution. The results show good agreement between the prediction and the experimental data. Deviations can be found in prediction of crack evolution in [0/902/01/2]s-specimens. For predicting fatigue stiffness degradation the phenomenological model of Adden [2] is used. The results show good capabilities for predicting stiffness degradation after crack onset.
Modeling of Organosandwich Structures Using an RVE Model of the Thermoplastic Honeycomb Core
Authors: Geyer Anne , Petersilge Matthias , John Marianne , Pflug Jochen , Schlimper Ralf
Published: June 2019

In the present study, Organosandwich structures consisting of a folded polypropylene (PP) honeycomb core and glass-fiber reinforced PP cross-ply face sheets are investigated with the aim of developing a valid method for structural simulation of Organosandwich structures. On the one hand, effective material properties are gained from a mesoscopic model on the basis of a representative volume element (RVE) and compared with data from experimental characterization. The morphology of the folded honeycomb structure was investigated via X-Ray computed tomography and 3d image analysis. On the other hand, the differences between experimental and effective core properties are shown, and the correlation between the mesoscopic honeycomb core structure and the entire sandwich behavior is validated by bending tests and a corresponding finite element model. A comparison shows that results can be achieved with the RVE model as well as with the homogenized core FE model with good agreement with the experimental data.
Parameter Selection for Peel Strength Optimization of Thermoplastic CF-PA6 for Humm3TM
Authors: Yadav Neha , Schledjewski Ralf
Published: June 2019

For Automated Tape Placement process, degree of bond varies with variation in process parameters and material. Interlaminar bond strength characterization is one of the most important criteria in determining the quality of bond between two layers of thermoplastic tapes. Depending on the bond strength achieved using different process parameters, a process window is defined. Based on the process window an iterative procedure is adopted to find optimum parameters to realize maximum bond strength. This paper aims to investigate the interlaminar bond strength of thermoplastic CF-PA6, during Automated Tape Placement process. A fairly new heating source, a pulsed light solution, i.e. a humm3TM system, which delivers uniform, highly controllable heat to the nip point is used. Experiments were conducted for different process parameters and results obtained using wedge peel test were analyzed. Results acquired help in assessing the material and the heating source in terms of capabilities and efficiency.
Influence on the Microstructure of Powder Metallurgical Metal Foam by Means of Mechanical Alloying
Authors: Siebeck Steve , Trautmann Maik , Hohlfeld Jörg , Hipke Thomas , Wagner Guntram
Published: June 2019

Due to the process, metal foams produced by powder metallurgy have an inhomogeneous pore structure. The pore size variations from a few tenths of a millimeter up to the centimeter range is so typical. This leads to inconstant properties and makes the predictability of metal foam based components difficult. The present work deals with the approach to precondition the feedstock powder for the production of metal foams by mechanical alloying. Thereby, the homogeneous distribution of the blowing agent TiH2 is already present in the so-called composite powder. In addition, there is the possibility to add reinforcement particles with regard to a further improvement of the mechanical properties. Overall, this leads to a rather wide range of possible influencing factors and parameters to be varied. Accordingly, the present work is only a preview of a broad experimental program, taking into account the design of experiments and is currently being processed. In this first study, an alloy AA6060 has been used as the matrix material. The evaluated method provides a finer pore structure associated with a modified foaming behavior.
Generating Permanent and Temporary Material Compounds in FLM Processes
Authors: Doerffel Christoph , Schmidt Raik , Spieler Mirko , Nendel Wolfgang , Kroll Lothar , Petzold Jens , Schreiter David , Hunold Mathias
Published: June 2019

Like all additive manufactured parts, FLM (fused-layer-modeling) components are characterized by a large number of joints between the similar and different materials. These joints can be divided into five categories:- Permanent cohesive bonds between single layers of the same thermoplastic material,- Permanent adhesive bonds between single layers of different thermoplastic materials- Temporary adhesive bonds between single layers of different thermoplastic materials,- Permanent adhesive bonds between a single layer of thermoplastic material and a non-thermoplastic base material,- Temporary adhesive bonds between a single layer of thermoplastic material and a non-thermoplastic base material.The first three types of bonds describe the binding process when parts are manufactured of base material, a second permanently bonded component or a support material that has good release properties. The last two types of connection describe the permanent connection between the printing part and a non-FLM-component or the temporary joint between the printed part and the build platform during the printing process. The resulting compounds can be characterized as material compounds.Since the FLM process is mainly used for design and hobby applications, the fundamentals of the bonding processes and their influence on the internal structure of the material are hardly described. Some information can be taken from the literature for welding plastics and the production of hybrid parts by injection molding. Due to the different pressure and temperature conditions as well as the very large surface-volume-ratio of the discharged strand occur significant differences in the following factors: melt flow, solidification time, formation of surface layers and wetting of the surfaces.The investigation and characterization of these effects as a function of external process parameters is an important constituent for the further development of the FLM process into an industrially suitable manufacturing process for thermoplastic components with very high lightweight and complex geometry in small series etc.
Manufacturing CFRP-Parts Using a Modified Co-Curing Method – Fundamental Experimental Analysis
Authors: Rieger Florian , Rief Thomas , Motsch Nicole , Hausmann Joachim M.
Published: June 2019

With the increasing utilization of fiber-reinforced polymers in various areas of application such as aviation and automotive, the need for efficient production methods appropriate for these materials also gains importance. The widespread use of metallic fasteners in conjunction with differential design leads to stress concentrations when applied to FRPs and prevents the full utilization of their mechanical properties. In an effort to develop an appropriate joining technology that also contributes to reducing tooling costs, co-curing of thermoset FRP laminates is analyzed in the present work. To gain insight into the feasibility of the use of pre-cured laminates in co-curing processes, laminates of varying degree of cure are joined with uncured laminates in a co-curing process and the mechanical properties of the resulting laminates are investigated experimentally. Based on these experimental results, an interdependence between bonding properties and the degree of cure of the pre-cured laminate can be shown.
Scalable Monitoring System for the Localization of Damaging Events in Thin-Walled CFRP Structures Based on Acoustic Emission Analysis and Neural Networks
Authors: Kelkel Benjamin , Argus Philipp , Gurka Martin
Published: June 2019

A constant challenge for the design and operation of CFRP primary structures is their sensitivity towards impact loading. This can lead to the formation of externally invisible delaminations which endanger the structural integrity. In practice, this circumstance is encountered with elaborate inspections or conservative design. Structural Heath Monitoring (SHM) systems offer the potential for permanent monitoring and represent an alternative approach that has drawn more attention in the last decade. The biggest barriers to market entry for this technology are system costs and reliability. This study is dedicated to these two points with the development of a low-cost system with which representative acoustic emission sources can be located reliably in a complex CFRP structure. The implementation is carried out using acoustic emission analysis, which represents a promising solution for the integral monitoring of primary structures. It is based on the detection of acoustic waves that are released during crack initiation and growth and propagate over large areas in thin-walled structures as Lamb waves. The challenges of source localization in thin-walled CFRP structures lie in the consideration of wave dispersion, anisotropic material properties, variable component geometry and interfaces. In this thesis, this complexity is captured by training a neural network. For this purpose, artificial sources are used which imitate acoustic emissions of typical damaging events in the material in frequency and mode content. The demonstrating component is an omega profile equipped with a network of piezoelectric sensors that is designed for reliable localization within a defined window. Signal processing takes place on a single-board computer which, together with a digital oscilloscope, completes the measurement chain. The system represents a modular, low-cost approach that can be transferred to other applications by adapting the hardware and training.
Influence of Sputtering Temperature and Layer Thickness on the Electrical Performance of Thin Film Strain Sensors Consisting of Nickel-Carbon Composite
Authors: Karapepas Christos , Nestler Daisy , Wagner Guntram
Published: June 2019

Hybrid laminates consisting of fibre-reinforced thermoplastic films and metallic thin sheets are successively replacing thermoset based systems due to their obvious advantages of higher formability and aptitude for mass production. In order to monitor the material under operating conditions, hybrid laminates need to be equipped with smart sensor units. Artifact-free integration of commercial strain gauges into hybrid laminates is almost impossible. Therefore, a new thin film strain sensor based on a PVD sputtering process was developed.The aim of this work was to evaluate the influence of the layer thickness as well as the elevated temperature during the sputtering process on the electrical performance of Ni-C strain sensors. The Ni-C films with different layer thickness and different sputtering temperatures manufactured by means of a magnetron sputtering process were investigated for the sheet resistance and the change of temperature coefficients of resistance. In addition, Raman spectroscopy was utilized to investigate the phase development with regard to different sputtering temperatures. It can be seen that the gauge factor gets doubled while optimizing the layer thickness. When the sputtering temperature was increased, the graphitic phase formation was preferred and the impurities were reduced. These results are discussed in this paper and appropriate solution concepts are provided.
Investigation on the Influence of Pressure Terms in a Volume-Averaged Energy Balance in the Modelling of Liquid Composite Moulding Processes
Authors: Sebastian Rohit George , Obertscheider Christof , Fauster Ewald , Schledjewski Ralf
Published: June 2019

The growing use of composite materials has generated interest in improving and optimising composite manufacturing processes such as Liquid Composite Moulding (LCM). In LCM, dry preforms are placed in a mould and impregnated with the matrix material. The efficiency of filling the moulds can be improved by using Computational Fluid Dynamics (CFD) filling simulations during the design of the mould. As part of an on-going effort to develop a CFD tool for the simulation of LCM processes, a volume averaged energy balance equation has been derived and implemented in a custom OpenFOAM solver. The energy balance is implemented in a custom OpenFOAM solver with and without the pressure terms for comparison with results from RTM experiments. It is found that the pressure terms do not significantly influence the results for LCM processes.
Experimental Characterization of the Fiber Angles of Multiple Curved Laminate Segments Using Prepreg-Based Carbon Fiber Reinforced Polymers as a Structure for a Non-Engaging Bellows Coupling
Authors: Oblinger Christian , Baeten André , Drechsler Klaus
Published: June 2019

This paper deals with the experimental characterization of the fiber angles of multiple curved laminate segments using prepreg-based carbon fiber reinforced polymers as a structure for a non-engaging bellows coupling. The main task of this generic shaft coupling is the torsionally stiff torque transmission and the compensation of axial displacement as well as the angular misalignment of metallic shafts. The multiple curved structure can be manually draped by several cut segments using epoxy-based fabric prepreg. Moreover, the intended initial fiber orientation of the laminate is ±45° with respect to the rotation axis of the structure. For the experimental determination of the local fiber angles various CFRP cut segments were defined as CFRP specimens with varying number of layers and constant width. All investigations were based on cured CFRP specimens. The measurements were performed with a robot-assisted optical surface sensor and an optical digital microscope. The influence of the manual draping process according to the z-method could be quantitatively determined by the fiber angle measurements.
Development of a 25kN In Situ Load Stage Combining X-Ray Computed Tomography and Acoustic Emission Measurement
Authors: Thum Florian , Potstada Philipp , Sause Markus G.R.
Published: June 2019

Combination of material testing methods such as X-ray computed tomography with in-situ load stages allows for detailed analysis of damage formation and progression in fibre-reinforced composites. X-ray computed tomography is highly suited to volumetrically analyse the damage evolution induced by the load stage for tensile testing after subsequent load increments. Simultaneous acoustic emission monitoring allows identifying the occurrence of particular failure mechanisms and allows stopping the loading procedure for volumetric scanning. However, typical commercial designs focus on a broad range of materials and are not necessarily optimized for high load capacity at high voxel resolution or the possibility to attach acoustic emission sensors to the test sample. Accordingly, we designed a new load stage to fit larger samples up to 180 mm in length and 18 mm in width, which also allows two piezoelectric acoustic emission sensors to be directly applied on the sample. In order to test fibre reinforced laminate samples with a relevant cross-section, the support structure of the load stage is made of a carbon fibre reinforced polymer tube, which withstands a maximum load of 25 kN and still stays reasonably X-ray transparent. With an outer diameter of 27 mm, a computed tomography scan with a resolution down to 2.6 μm is still possible for these laminate cross-sections. This allows to study in detail how matrix and fibres behave under loads in laminates, which are comparable to specimen sizes by typical test standards. As example, we present results from glass fibre-reinforced epoxy samples with a [±45°]5layup and carbon fibre-reinforced epoxy samples with a [0,90,90,0] layup.
Dispersion of Mechanical Properties at Nanoscale Studied by Indentation Mapping of a Fiber Reinforced Composite
Authors: Hangen Ude D. , Stauffer Douglas
Published: June 2019

The properties of a resin transfer molded sheet of strand-reinforced composite for automotive applications are investigated at the microscopic level. Three components of the composite can be identified in the bright field micrograph – glass fibers, epoxy matrix and binder. The latter having been added in manufacturing process. Accelerated Nanoindentation with 64.451 single indentation experiments is performed at room temperature to generate a mechanical property map of an area containing the 3 components. The distribution of properties, mean value and standard deviation, is determined for each component. Two locations in the composite are selected for a study of the local glass transition behavior by performing dynamic indentation experiments while simultaneous variation of the temperature of the indenter tip and sample within a micro-heating chamber.
Optimization of the Specimen Geometry of Unidirectional Reinforced Composites with a Fibre Orientation of 90° for Tensile, Quasi-Static and Fatigue Tests
Authors: Schneider Christian , Drvoderic Matthias , Schuecker Clara , Pinter Gerald
Published: June 2019

When testing unidirectional reinforced composites with a fiber orientation of 90° in tensile tests with rectangular specimens, the influence of the clamping often causes a failure in their vicinity and therefore the test cannot be regarded as valid. In this paper, a test specimen design was determined which is well suited for testing the material properties transverse to the fiber direction by calculating the influence of geometric details of shoulder bar specimens with the help of finite element simulation. The particularly critical clamping and shoulder areas were examined more closely to ensure failure mainly in the test field. In the clamping area the design of the glued-on tabs was investigated and in the shoulder area an optimization of the shoulder geometry was done. Based on the two optimized design proposals, test specimens were produced and evaluated by monotonous tensile tests. Subsequently, Wöhler tests were carried out at different R-ratios and load levels and compared with results of rectangular specimens.
Mechanical and Fracture Mechanical Properties of Matrix-Reinforced Carbon Fiber Composites with Carbon Nanotubes
Authors: Sinn Gerhard , Singer Gerald , Jocher Leo , Unterlass Miriam M. , Rennhofer Harald , Windberger Ursula , Wendrinsky Josef , Stöger Werner , Semlitsch Karl H , Lichtenegger Helga C.
Published: June 2019

Carbon fiber reinforced Plastics are materials with high strength and stiffness at low weight compared to metals. These properties make the materials ideal candidate for structures in aerospace applications, where they are often used under bending conditions. Due to the strongly anisotropic composition the CFRP typically fail in compression by fiber buckling. In order to improve this weakness, nanotube and nanofiber reinforced matrix was used to build CFRP. Four-point bending tests showed that stiffness and strength could be improved by the fillers, whereas negative influence was found on fracture energy.
Composite Materials Made of Basalt Fibres and Biobased Matrix Material for Technical Applications
Authors: Buschbeck Sebastian , Tautenhain Florian , Reichelt Claudia , Rinberg Roman , Kroll Lothar
Published: June 2019

Basalt fibres are inorganic man-made fibres which, in fibre-reinforced plastic composites (FRP), represent a cost-effective alternative to carbon fibres. Within petrochemical thermoplastic matrices, basalt fibres are established in technical applications. The use of biobased polyamides as matrix material is an innovative approach for the production of FRP with a high proportion of renewable raw materials. In addition to material selection, the compound manufacturing process also defines the properties of the FRP. At the Institute of Lightweight Structures, extensive investigations are carried out into material development and optimization of the associated process technology. As a result, basalt fibre-reinforced, biobased polyamides are produced whose mechanical relevant properties are above those of petrochemical based glass fibre-reinforced polyamides.
Effects of Heat-Treatment on Microstructures and Mechanical Properties of Hot Deformed TiB/Ti-6Al-4V Matrix Composites
Authors: Hu Zheng Yang , Zhang Zhao Hui , Song Qi , Yin Shi Pan , Wang Hao , Li Xian Yu
Published: June 2019

In this paper, TiB reinforced Ti-6Al-4V matrix composites were successfully fabricated using a spark plasma sintering, hot rolling and heat treating process. (Transformed β-Ti + secondary α-Ti) domains were formed in TiB/TMCs after heat treatment. The size of these domains increases from 2.5 μm to 4.6 μm with the increase of solution time. The aspect ratio of whiskers monotonously decreases along with the solution time extending. The highest ultimate tensile strength of 1332 MPa and yield-strength of 1315 MPa were achieved by (940 °C, 15min+ water-quenching+537 °C, 4h) TMC.
The Microstructure and Solidification Mechanism of Al-Ti-C-Ce Prepared by Petroleum Coke
Authors: Zhou Xin Feng , He Yong Dong , Zhang Yuan Qing , Ma Dong Liang
Published: June 2019

The microstructure of an Al-Ti-C-Ce alloy was studied by XRD, SEM, and EDS. This mother alloy consisted of α (Al),(AlTi),(TiC), and (Ti2Al20Ce) phases, and there was a second phase of a composite structure in the alloy. The TiC phase was the primary crystal nucleus, and the (TiAl) phase was segregated on the surface of TiC phase to form a TiC-(TiAl) composite crystal nucleus. Al formed a fine TiC-(TiAl)-α (Al) primary composite crystal nucleus by a peritectic reaction.The primary composite crystal nucleus with higher energy and larger cluster size was taken as the core,and other composite crystal nuclei were segregated on its surface to form a secondary composite crystal nucleus. Next, the secondary composite crystal nucleus formed the tertiary composite crystal nucleus, and so on, to form the titanium-enriched area of composite particles.
Synthesis and Characterization of Hematite onto Cellulose Supports for Adsorption of Roxarsone
Authors: Kong De Xu , Wilson Lee D.
Published: June 2019

This study reports on the development of an iron oxide-cellulose composite material for the controlled removal of 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone), a model organoarsenical. Hematite (He) and a hematite-cellulose (HeCell) composite adsorbents were prepared and characterized by thermal gravimetric analysis (TGA), nitrogen adsorption, and various spectroscopic (IR, Raman, XRD, and TEM) methods. The uptake of roxarsone at ambient conditions of He and HeCell, and goethite-cellulose (GoCell) adsorbent were compared to study the factors that influence adsorption. The monolayer adsorption capacity (mmol/g) of each adsorbent are listed in parentheses, as follows: cellulose (0.028), goethite (0.0730), Hematite (0.155), 10 % Fe coated GoCell (0.0222) and 10% Fe coated HeCell (0.0873). The relatively large surface area of hematite nanoparticles (NPs) and good dispersion of these NPs onto the cellulose supports contribute to their effective adsorption of roxarsone.
Research on TiH2 Preparation Mechanism and Structure Properties of Al-Ti-C Mother Alloy
Authors: Yang Xiao Yu , He Yong Dong , Li Qing Xin , Ma Dong Liang
Published: June 2019

Structure properties of Al-Ti-C mother alloy which was prepared by TiH2 and graphite method were studied by various characterization methods.Results demonstrated that the synthesis process of Al-Ti-C alloy contained three stages.Firstly,TiH2 and graphite was respectively used as titanium and carbon sources.Secondly,titanium reacted with aluminum and graphite,producing Ti-Al,C-Al,Ti-C compounds.Finally,these compounds formed Al-Ti-C alloy.It was equiaxed or dendrite structure with grain size of 20～40μm.There were needle-like and elongated phases in alloy matrix.There are petal primary crystals containing Ti,C,Fe and Si on grain boundaries.Ti and C distribute evenly along grain boundaries and grains.Ti and C enrichment and segregation occurred close to the primary phase.Cryolites were conducive to wetting of carbon and aluminum, the second phase generated more fully in the grain.
Preparation and Electrochemical Performance of Mg2 + Doped Li4Ti5O12 Anode Materials for Lithium-Ion Batteries
Authors: Wang Ming , Zhang Xue Ming , Wang Ying Bo , Cheng Li Li , Wang Xue Lei , Zhang Qiang
Published: June 2019

Spinel Li4Ti5O12 (LTO) doped with Mg2+ was synthesized by solid-phase reaction method. The Mg2+ doping quantity was 3%, 6%, 9%, and 12%, respectively. The structure and electrochemical performance of the prepared LTO composites were investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), and galvanostatic charge-discharge tests. It was found that the doped Mg ion did not change the structure of Li4Ti5O12, and it was evenly distributed around Li4Ti5O12. When Mg2+ doping quantity increased from 3% to 12%, the internal resistance and charge transfer resistance of the composite both decreased. The first discharge specific capacity of 6%-Mg2+ doped LTO composite was 168 mAh/g, which was close to the theoretical capacity of pure lithium titanate (175 mAh/g), and the capacity retention rate was 98% after 100 cycles.
Corrosion Performance of TRIP Steels under Atmospheric Environment
Authors: Wang Hao Xu , Cai Yi Qin , Li Zhuang , Zhou Qi
Published: June 2019

Atmospheric corrosion test of TRIP steels was conducted in laboratory. The surface morphologies of the specimens were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and electro-probe microanalysis (EPMA). Corrosion performance of TRIP steels under atmospheric environment was investigated by discussing the protective mechanism. The corrosion rates of steel A are significantly greater than steel B in atmospheric environment tests. The enhancement of corrosion performance of TRIP steel is attributed to the additions of alloying elements, such as P, Cr, Cu, and Ni etc.. The alloying elements increase the compactness and densification of rust layers. Electrochemical characteristic of TRIP steel is improved by means of the enhancement of the thermodynamic stability.
Is subscapularis repair correlated with better outcome compared to non-repair in reverse total shoulder arthroplasty? A systematic review of comparative trials
Authors: Malahias Michael Alexander , Gerogiannis Dimitrios , Chronopoulos Efstathios , Kaseta Maria-Kyriaki , Brilakis Emmanouil , Antonogiannakis Emmanouil
Published: June 2019

We aimed to investigate whether combined reverse total shoulder arthroplasty (RTSA) and subscapularis repair leads to improved clinical and functional outcome in comparison with RTSA alone. Two reviewers independently conducted a systematic search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews. These databases were queried with the terms “reverse” AND “shoulder” AND “arthroplasty” AND “with” AND “subscapularis” AND “repair”. From the 72 initial studies, we finally chose five studies which were eligible to our inclusion-exclusion criteria. The total mean modified Coleman methodology test was 55/100 (range: 47/100 to 60/100). The eligible studies included 1087 patients, in total. Regarding the subjective functional scores as well as range of motion (ROM), the differences amongst groups were insignificant in almost all studies. The mean complications’ rate of the repair group was 10.4%, whereas the respective rate of the non-repair group was 10.2%. All studies concluded that the repair of subscapularis did not affect the complications’ rate of patients who were treated with RTSA. The mean dislocations’ rates of the repair and the non-repair group were 1.5% and 2.3%, respectively. Although subscapularis repair was proven safe and effective for the augmentation of RTSA, it did not offer any additional clinical or functional benefit in the outcome of patients treated with lateralized RTSA. Therefore, it is not supported its routine use for patients who have a preoperatively sufficient subscapularis tendon.
Influence of graft diameter on patient reported outcomes after hamstring autograft anterior cruciate ligament reconstruction
Authors: Duerr Robert A. , Garvey Kirsten D. , Ackermann Jakob , Matzkin Elizabeth G.
Published: June 2019

Several studies have identified graft diameter as a risk factor for failure following anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to evaluate the effect of graft diameter on patient reported outcome measures (PROMS) following ACLR. We performed a retrospective review of prospectively collected data using a global surgical registry. 153 of 287 patients (53.3%) had complete data for each timepoint. Effect of graft diameter, graft type, femoral tunnel drilling technique, patient age, sex, and body mass index were evaluated. At 1-year post-operatively, a 1-mm increase in graft diameter was found to correlate with a 5.7-point increase in the Knee Injury and Osteoarthritis Outcome Score (KOOS) activity of daily living score (p = 0.01), a 10.3-point increase in the sport score (p=0.003), and a 9.8-point increase in the quality of life score (p=0.013). At 2-years post-operatively, a 1-mm increase in graft size was found to be marginally correlated with KOOS symptoms and sport scores. Patients undergoing hamstring autograft ACLR, increasing graft diameter can result in improved PROMS, specifically improved KOOS subscale scores at 1 and 2-years post-operative.
ἐλθέτω ἡ βασιλεία σου: Interpreting the Lord’s Prayer (Mt 6:10a) in the light of Ewe-Ghanaian eschatological vision
Authors: Van Eck Ernest , Sakitey Daniel
Published: June 2019

This article examines the phrase ἐλθέτω ἡ βασιλεία σου in Matthew and Luke’s versions of the Lord’s Prayer in the light of Ewe-Ghanaian eschatological vision. Theoretically, it uses a combination of the historical–critical and indigenous Mother Tongue Biblical Hermeneutical approaches to explore the implication of βασιλεία for the Ewe-Ghanaian Christian. The article discusses the diversity in the interpretations of the text from the early church to the modern and postmodern periods in Christian history and argues that this diversity has occurred as a result of the fluidity of the eschatological visions in the Judeo-Christian Scriptures and that the linear eschatological vision described by the church is inconsistent with the cyclical vision in Ewe cosmology. This dual eschatological vision creates a dilemma in the Ewe-Ghanaian Christian’s understanding of the eternal states. Finally, it is argued that to resolve this eschatological dilemma is to clearly define the place of Ewe eschatological vision in Christian eschatology and interpreting the former as replica of the latter.
The relationship between chief executive officer compensation and the size and industry of South African state-owned enterprises
Authors: Coetzee Mariette , Bezuidenhout Magda L.
Published: June 2019

Orientation: Concerns about exorbitant executive compensation are making headlines, because executives receive lucrative packages despite state-owned enterprises (SOEs) performing poorly. It appears as if chief executive officers (CEOs) are not being held accountable for the performance of the SOEs.Research purpose: The purpose of the study was to determine whether the size and the industry of an SOE had an impact on CEO compensation packages.Motivation for the study: A greater understanding of the relationship between CEO remuneration and the size and type of industry of SOEs would assist with the standardisation of CEO remuneration and linking CEO pay to SOE performance.Research approach/design and method: A multiple regression analysis on a pooled dataset of 162 panel observations was conducted over a 9-year period. Financial data of 18 SOEs were extracted from the McGregor BFA database and the annual reports of SOEs.Main findings: The findings show that the size of an SOE does not influence the total compensation of CEOs. However, larger SOEs pay larger bonuses due to these SOEs being in a stronger financial position to offer lucrative bonuses. CEO’s remuneration was aligned within certain industries.Practical/managerial implications: The findings emphasise the need to link CEO compensation with SOE performance. Standardisation in setting CEO compensation and implementing performance contracts should be considered.Contribution/value-add: The study confirms that CEO pay is not linked to performance and not justified when considering SOE size or industry.
Advanced Strategies in Pharmacy Experiential Education
Authors: Legal Michael
Published: June 2019

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Walking the Talk: Actions to Resolve Canada’s Opioid Crisis
Authors: Doucette Douglas
Published: June 2019

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Latin Blackness in Parisian Visual Culture, 1852–1932
Authors: Williams Lyneise E.
Published: June 2019

Latin Blackness in Parisian Visual Culture, 1852-1932 examines an understudied visual language used to portray Latin Americans in mid-19th to early 20th-century Parisian popular visual media. The term ‘Latinize’ is introduced to connect France’s early 19th-century endeavors to create “Latin America,” an expansion of the French empire into the Latin-language based Spanish and Portuguese Americas, to its perception of this population.

Latin-American elites traveler to Paris in the 1840s from their newly independent nations were denigrated in representations rather than depicted as equals in a developing global economy. Darkened skin, etched onto images of Latin Americans of European descent mitigated their ability to claim the privileges of their ancestral heritage. Whitened skin, among other codes, imposed on turn-of-the-20th-century Black Latin Americans in Paris tempered their Blackness and rendered them relatively assimilatable compared to colonial Africans, Blacks from the Caribbean, and African Americans.

After identifying mid-to-late 19th-century Latinizing codes, the study focuses on shifts in latinizing visuality between 1890-1933 in three case studies: the depictions of popular Cuban circus entertainer Chocolat; representations of Panamanian World Bantamweight Champion boxer Alfonso Teofilo Brown; and paintings of Black Uruguayans executed by Pedro Figari, a Uruguayan artist, during his residence in Paris between 1925-1933.
What do we want and what do we get from the coach? Preferred and perceived leadership in male and female team sports
Authors: Wałach-Biśta Zuzanna Maria
Published: June 2019

Purpose

The purpose of the study was to investigate any similarities or differences between the genders in the scope of preferred coaching behaviours. Moreover, it was an attempt at establishing whether there are discrepancies between the respondents’ expectations and their evaluation of the actual perceived behaviour of the coaches towards them. It was also considered whether the type of the played sport would differentiate the respondents depending on their expectations.

Methods

The study consisted of two stages. The athletes’ preferences concerning coaching behaviours were studied with the ‘athletes’ preferences’ version of the Leadership Scale for Sports. The perceived coaching behaviour was evaluated by the athletes at the end of the season with the ‘coach’s behaviour as perceived by the athletes’ version of the scale.

Results

Significant differences between women and men were observed when it comes to their preferences concerning coaching behaviours. Moreover, the analysis for dependent samples demonstrated that the athletes received from the coaches fewer coaching-related instructions, less feedback, and fewer democratic behaviours than they would have expected.

Conclusions

The results indicate that women and men differ in their preferences concerning coaching behaviours. These differences, however, are not big. The played sport may also have a significant influence on the expectations regarding the coach’s behaviour; this observation is, however, limited to women. Regardless of the athletes’ gender, coaches provided them
with less behaviours than the athletes would have expected. This implies that coaches adjust their behaviour to the athletes’ preferences and the situational requirements in an inadequate manner.
Effects of judo participation on anthropometric characteristics, motor abilities, and posture in young judo athletes
Authors: Protic-Gava Branka , Drid Patrik , Krkeljas Zarko
Published: June 2019

Purpose

Despite the benefits of sport participation to schoolchildren, some highly competitive activities may induce sportspecific physical adaptations that may predispose children to long-term motor impairments. Hence, the aim of this study was to compare the anthropometric characteristics, motor abilities, and posture between schoolchildren actively participating in judo and their peers participating in general physical education classes.

Methods

The study included 148 male participants aged 12–14 years. The two groups of subjects were compared in terms of their anthropometrics, posture, and motor abilities.

Results

Statistically significant differences were observed in subscapular skinfold and triceps skinfold in favour of the young judokas. Judo competitors also demonstrated better functional coordination, flexibility, explosive force of lower limbs, and pelvic and isometric muscular endurance. In addition, judokas were characterized by better postural alignment relative to shoulders, chest, and abdomen.

Conclusions

The results suggest that participation in judo in addition to physical education classes builds specific motor and physical characteristics in children that may aid in healthy body development.
The use of analgesics among Poznań marathon runners
Authors: Kamińska Joanna , Pawlak Maciej
Published: June 2019

Purpose

Running is becoming an increasingly more popular form of leisure activity. However, intense physical activity, such as running a marathon, can put a significant strain on the body and lead to the use of painkillers to reduce or avoid pain. Therefore, the purpose of the research was to determine the percentage of participants in the Poznań Marathon taking
analgesics before or during the run and to investigate the runners’ knowledge about the possible negative health effects of such behaviour.

Methods

The study was carried out in 3 consecutive years (2014–2016) among 308 runners participating in the Poznań Marathon. The respondents completed a survey consisting of 3 parts: (1) personal details, (2) use of analgesics before and/or during the marathon run, and (3) the runner’s awareness of the possible negative effects of using such medicines during increased physical activity.

Results

Taking analgesics before or during a marathon run was declared by 18.6%, 14.9%, and 16.8% of the participants in years 2014, 2015, and 2016, respectively. Compared with men, women used painkillers more frequently (22.3% vs. 16.1%). On average, 59.3% of runners believed that using analgesics might be harmful to their health and increase the risk of injury, but 39.8% of them took painkillers anyway.

Conclusions

Nearly every sixth participant of the Poznań Marathon used analgesics before or during running because of the pain they experienced or expected. The awareness of analgesic-related side effects did not stop the runners from using painkillers.
Coarse and Giant Particles are Ubiquitous in Saharan Dust Export Regions
and are Radiatively Significant over the Sahara
Authors: Ryder Claire L. , Highwood Eleanor J. , Walser Adrian , Seibert Petra , Philipp Anne , Weinzierl Bernadett
Published: June 2019

Abstract. Mineral dust is an important component of the climate system, interacting with radiation, clouds and biogeochemical systems, and impacting atmospheric circulation, air quality, aviation and solar energy generation. These impacts are sensitive to dust particle size distribution (PSD), yet models struggle or even fail to represent coarse (diameter (d) > 2.5 µm) and giant (d>20 µm) dust particles and the evolution of the PSD with transport. Here we examine three state-of-the-art airborne observational datasets, all of which measured the full size range of dust (d = 0.1 to > 100 µm) at different stages during transport, with consistent instrumentation. We quantify the presence and evolution of coarse and giant particles and their contribution to optical properties. Observations are taken from the Fennec fieldwork over the Sahara and in the Saharan Air Layer (SAL) near the Canary Islands, and from the AER-D fieldwork in the vicinity of the Cape Verde Islands in the SAL. Observations show significantly more abundant coarse and giant dust particles over the Sahara compared to the SAL: effective diameters of up to 20 µm were observed over the Sahara, compared to 4 µm in the SAL. Mass profiles show that over the Sahara 40 % of dust mass was found in the giant mode, contrasting to 2 to 12 % in the SAL. Size-resolved optical property calculations show that in the shortwave (longwave) spectrum excluding the giant mode omits 18 % (26 %) of extinction over the Sahara, compared to 1–4 % (2–6 %) in the SAL. Excluding giant particles results in significant underestimation of both shortwave and longwave extinction over the Sahara, as well as of mass concentration, while the effects in the SAL are smaller but non-negligible. Omitting the giant mode results in a greater omission of dust longwave radiative effects compared to the shortwave, suggesting a bias towards a radiative cooling effect of dust when the giant mode is excluded and/or the coarse mode is underestimated. This will be important in dust models, which typically exclude giant particles and underestimate coarse mode concentrations. A compilation of effective diameters against dust age since uplift time suggests that two regimes of dust transport exist. During the initial 1.5 days, both coarse and giant particles are rapidly deposited. During the subsequent 1.5 to 10 days, PSD barely changes with transport, and the coarse mode is retained to a much greater degree than expected from estimates of gravitational sedimentation alone. The reasons for this are unclear, and warrant further investigation in order to improve dust transport schemes, and the associated radiative effects of coarse and giant particles in models.
Future trends in stratosphere-to-troposphere transport in CCMI models
Authors: Abalos Marta , Orbe Clara , Kinnison Douglas E. , Plummer David , Oman Luke D. , Jöckel Patrick , Morgenstern Olaf , Garcia Rolando R. , Zeng Guang , Stone Kane A. , Dameris Martin
Published: June 2019

Abstract. One of the key questions in the air quality and climate sciences is how will tropospheric ozone concentrations change in the future. This will depend on two factors: changes in stratosphere-to-troposphere transport (STT) and changes in tropospheric chemistry. Here we aim to identify robust changes in STT using simulations from the Chemistry Climate Model Initiative (CCMI) under a common climate change scenario (RCP6.0). We use two idealized stratospheric tracers to isolate changes in transport: stratospheric ozone (O3S), which is exactly like ozone but has no chemical sources in the troposphere, and st80, a passive tracer with fixed volume mixing ratio in the stratosphere. We find a robust increase in the tropospheric columns of these two tracers across the models. In particular, stratospheric ozone in the troposphere is projected to increase 10–16 % by the end of the 21st century in the RCP6.0 scenario. Future STT is enhanced in the subtropics due to the strengthening of the shallow branch of the Brewer-Dobson circulation (BDC) in the lower stratosphere and of the upper part of the Hadley cell in the upper troposphere. The acceleration of the deep branch of the BDC and changes in eddy transport contribute to increase STT at high latitudes. The idealized tracer st80 shows that these STT changes are dominated by greenhouse gas (GHG) increases, while phasing out of ozone depleting substances (ODS) does not lead to robust STT changes. Nevertheless, the increase of O3S concentrations in the troposphere is attributed to GHG only in the subtropics. At middle and high latitudes it is due to stratospheric ozone recovery linked to ODS decline. A higher emission scenario (RCP8.5) produces qualitatively similar but stronger STT trends, with changes in tropospheric column O3S more than three times larger than those in the RCP6.0 scenario by the end of the 21st century.