bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of prolinamide with adamantane for aldol reaction catalysis in brine and separation using a poly(AN-MA-β-CD) nanofibrous film via host–guest interaction
Authors: Wang Rui , Xu Enjie , Su Zhenming , Duan Haifeng , Wang Jinjin , Xue Longqi , Lin Yingjie , Li Yaoxian , Wei Zhonglin , Yang Qingbiao
Published: August 2018

Prolinamide with adamantane catalyzed the aldol reaction. The reaction of cyclohexanone with m-nitrobenzaldehyde assessed recyclability of catalyst. After run, the catalyst was adsorbed with nanofibrous of polymer via host–guest interaction.
Heat transfer effect in scaling-up a fluidized bed reactor for propylene polymerization
Authors: Bumphenkiattikul Panut , Limtrakul Sunun , Vatanatham Terdthai , Khongprom Parinya , Ramachandran Palghat A.
Published: August 2018

The effects of operating conditions and scaling-up on reactor temperature control and performance in propylene polymerization fluidized bed reactors were studied by phenomenological and CFD models.
Synthesis and physical properties of tris(dialkylamino)cyclopropenium dicyanamide ionic liquids
Authors: Curnow Owen J. , Polson Matthew I. J. , Walst Kelvin J. , Yunis Ruhamah
Published: August 2018

An investigation of symmetry (D3h,C3h,C2vandCs) and alkyl chain length (6–60 alkyl carbon atoms) effects on the physical properties of peralkylated triaminocyclopropenium dicyanamide salts.
Three-dimensional flower-like NiCo2O4/CNT for efficient catalysis of the oxygen evolution reaction
Authors: Ma Zhaoling , Fu Hao , Gu Cibing , Huang Youguo , Hu Sijiang , Li Qingyu , Wang Hongqiang
Published: August 2018

Three-dimensional flower-like NiCo2O4were grown on CNTs prepared by chemical vapor deposition and showed better electrochemical performances on oxygen evolution reaction.
Continuous low temperature synthesis of MAPbX3 perovskite nanocrystals in a flow reactor
Authors: Liang Xinxing , Baker Robert W. , Wu Kejun , Deng Wentao , Ferdani Dominic , Kubiak Peter S. , Marken Frank , Torrente-Murciano Laura , Cameron Petra J.
Published: August 2018

Perovskite nanocrystals prepared at room temperature using a simple flow reactor.
Lead-free halide double perovskite-polymer composites for flexible X-ray imaging
Authors: Li Haoran , Shan Xin , Neu Jennifer N. , Geske Thomas , Davis Melissa , Mao Pengsu , Xiao Kai , Siegrist Theo , Yu Zhibin
Published: August 2018

X-ray detectors are demonstrated using composite films of lead-free Cs2AgBiBr6 halide double perovskite embedded in a polymer matrix as the X-ray photoconductors.
Microstrip‐line‐fed elliptical wide‐slot antenna with similar parasitic patch for multiband applications
Authors: Kumar Munish , Nath Vandana
Published: August 2018

This study presents two design improvements over conventional microstrip antenna in terms of multiband operation, gain and cross‐polarisation (XP) level. The first design (Type‐I) consists of a microstrip line on one side and an elliptical slot (ES) on the other side of the substrate. The second design (Type‐II) consists of a parasitic elliptical patch inside the ES in addition to the first design. A theoretical analysis using an equivalent circuit model is performed for both antenna designs for estimating the dimensions of each part of the proposed structures. It is found that the size of the wide ES determines the lower operating frequency, whereas coupling between the parasitic patch and microstrip line decides the multiband operation. Experimental results show that the Type‐I antenna resonates in three frequency bands at 2.49, 3.7, and 9.76 GHz with peak gain and XP level of 8.66 and 44.43 dB, respectively. With proper selection of the dimensions of the parasitic patch, the Type‐II antenna generates five frequency bands at 1.87, 6.42, 10.76, 12.67, and 13.66 GHz. An exceptionally high gain of 16.79 dB with an XP level of 36.15 dB is reported in Type‐II antenna. The theoretical and simulation results show a good agreement with the measured results.
Block error rate performance of OOK free‐space optical links over gamma–gamma turbulence channels with generalised non‐zero boresight pointing errors
Authors: Ninos Michalis P. , Nistazakis Hector E. , Sandalidis Harilaos G. , Stassinakis Argyris N. , Tombras George S.
Published: August 2018

The authors consider a point‐to‐point optical wireless communication link with on–off keying (OOK) modulation scheme. The propagation is deteriorated by the joint effects of gamma–gamma atmospheric turbulence and misalignment induced fading described by a non‐zero boresight pointing error model. Mathematical expressions are derived for the average block error rate and their accuracy is verified through numerical simulations with Monte Carlo method.
UWB radar recognition system based on HOS and SVMs
Authors: Sadli Rahmad , Tatkeu Charles , Hamidoun Khadija , El Hillali Yassin , Rivenq Atika
Published: August 2018

This study proposes an original ultra‐wideband short‐range radar (UWB‐SRR) recognition system based on higher‐order statistics (HOS) and support vector machines (SVMs). The main purpose of this work is to improve the road safety by implementing these techniques for detection and recognition of the uncovered road users such as pedestrians and cyclists. The combination of HOS and cell‐averaging constant false alarm rate (CA‐CFAR) radar detector has been proposed and investigated. The results show that a combination of HOS and CA‐CFAR promises a good performance for UWB radar detector. The authors have also evaluated the performance of SVM‐based target recognition system using normalised radar signature as input features. A total of 1000 signatures have been extracted for each class including pedestrian, cyclist, and car, where 50% of them have been used for the training data and the rest for the validation data. The results show that the SVM gives a good performance for the proposed system, where the recognition rates are up to 96.23, 95.25 and 97.23% for the cyclist, pedestrian and car. In the real testing performance using their scenarios, the system has successfully identified 92.77% of the right cyclist, 90.82% of the right pedestrian and 90.73% of the right car.
The XXL Survey
Authors: Koulouridis E. , Ricci M. , Giles P. , Adami C. , Ramos-Ceja M. , Pierre M. , Plionis M. , Lidman C. , Georgantopoulos I. , Chiappetti L. , Elyiv A. , Ettori S. , Faccioli L. , Fotopoulou S. , Gastaldello F. , Pacaud F. , Paltani S. , Vignali C.
Published: August 2018

Context. We present the results of a study of the active galactic nucleus (AGN) density in a homogeneous and well-studied sample of 167 bona fide X-ray galaxy clusters (0.1 < z < 0.5) from the XXL Survey, from the cluster core to the outskirts (up to 6r500). The results can provide evidence of the physical mechanisms that drive AGN and galaxy evolution within clusters, testing the efficiency of ram pressure gas stripping and galaxy merging in dense environments.

Aims. The XXL cluster sample mostly comprises poor and moderately rich structures (M = 1013–4 × 1014 M⊙), a poorly studied population that bridges the gap between optically selected groups and massive X-ray selected clusters. Our aim is to statistically study the demographics of cluster AGNs as a function of cluster mass and host galaxy position.

Methods. To investigate the effect of the environment on AGN activity, we computed the fraction of spectroscopically confirmed X-ray AGNs (LX [0.5-10 keV] > 1042 erg cm−1) in bright cluster galaxies with Mi* − 2 < M < Mi* + 1, up to 6r500 radius. The corresponding field fraction was computed from 200 mock cluster catalogues with reshuffled positions within the XXL fields. To study the mass dependence and the evolution of the AGN population, we further divided the sample into low- and high-mass clusters (below and above 1014M⊙, respectively) and two redshift bins (0.1–0.28 and 0.28–0.5).

Results. We detect a significant excess of X-ray AGNs, at the 95% confidence level, in low-mass clusters between 0.5r500 and 2r500, which drops to the field value within the cluster cores (r < 0.5r500). In contrast, high-mass clusters present a decreasing AGN fraction towards the cluster centres, in agreement with previous studies. The high AGN fraction in the outskirts is caused by low-luminosity AGNs, up to LX [0.5-10 keV] = 1043 erg cm−1. It can be explained by a higher galaxy merging rate in low-mass clusters, where velocity dispersions are not high enough to prevent galaxy interactions and merging. Ram pressure stripping is possible in the cores of all our clusters, but probably stronger in deeper gravitational potentials. Compared with previous studies of massive or high-redshift clusters, we conclude that the AGN fraction in cluster galaxies anti-correlates strongly with cluster mass. The AGN fraction also increases with redshift, but at the same rate with the respective fraction in field galaxies.
Enhancement of Mechanical Integrity of Advanced Composites using PMAA-Electropolymerised CF Fabrics
Authors: Semitekolos Dionysios A. , Goulis Panagiotis , Batsouli Despoina I. , Koumoulos Elias P. , Zoumpoulakis Loukas , Charitidis Costas A.
Published: August 2018

The aim of the present study is the development of new composite materials that show improved mechanical and structural integrity. In order to accomplish this goal, a novel functionalization method of the carbon fibers for the reinforcement of the composites surface was investigated. Through the electrografting of methacrylic acid onto the surface of the carbon fiber, this treatment aims to selectively modify the surface of the carbon fabrics, in order to create active groups that can chemically react with the epoxy resin, under heat and pressure. By this way, better adhesion as mechanical interlocking between the resin and the reinforcement can be achieved. The surface treatment was examined qualitatively by means of Infrared spectroscopy, Scanning Electron Microscopy and Raman spectroscopy. The carbon fiber reinforced polymers were manufactured via the hot-press technique and they were subsequently submitted to flexural, shear and nanoindentation test. Finally, the internal structural integrity was tested through micro-Computing Tomography.
Analysis of S0/A0 elastic wave mode conversion phenomenon in glass fibre reinforced polymers
Authors: Wandowski Tomasz , Malinowski Pawel , Ostachowicz Wieslaw
Published: August 2018

In this paper results of experimental analysis of elastic guided wave mode conversion phenomenon in glass fibre reinforced polymers GFRP are presented. Results of research presented in this paper are strictly focused on S0/A0' mode conversion caused by discontinuities in the form of circular teflon insert simulating damage and impact damage. Experimental research is based on non-contact elastic wave sensing with utilisation of scanning laser Doppler vibrometer SLDV and full wave-field measurements. In presented research influence of location of circular teflon insert on S0/A0' mode conversion is investigated. Teflon inserts were located between layers of composite material at different depth. Moreover influence of impact damage with different energy on S0/A0' mode conversion is investigated. Analysis of influence of investigated discontinuities on S0/A0' mode conversion are based on the elastic wave mode filtration in frequency-wavenumber domain. Mode filtration process allows to remove effects of unwanted type of mode propagation in forward or backward direction. Effects of S0/A0' mode conversion are characterise by mode conversion indicator based on amplitude of new mode A0'.
Numerical simulation of GLARE 4A fiber-metal laminates subjected to ballistic impact
Authors: Bikakis George , Tsigkros Nikolaos , Sideridis Emilios , Savaidis Alexander
Published: August 2018

This article deals with the evaluation of the ballistic resistance of GLARE 4A fiber-metal laminates subjected to high velocity impact by a cylindrical projectile. Important impact variables such as the ballistic limit, the impact load and the absorbed energy time histories are predicted using the ANSYS LS-DYNA software. The simultaneous existence of various impact damage mechanisms, which is unique in fiber-metal laminates, is demonstrated using the numerical results. Each of the mechanisms absorbs a part of the initial impact energy and contributes to the high ballistic impact resistance the materials. With reference to the considered GLARE 4A panels, the behavior of the transient impact load is analyzed and useful conclusions are drawn. It is found that the maximum impact load is applied at the beginning of ballistic impacts, during the initial local indentation of the panels under the projectile. It is substantially higher than the following peak values of the impact force time history. It is revealed that during the beginning of ballistic impacts, the impulse of the collision increases as the thickness of the panels is increased. The work done by the impact load during the local indentation stage is also an increasing function of the panels’ thickness.
Analysis of the elastic properties of CNTs and their effect in polymer nanocomposites
Authors: Laspalas Manuel , Chiminelli Agustín , Saenz Carlos , Serrano Francisco , Valero Clara
Published: August 2018

A study about of the influence of CNTs elastic properties in polymer nanocomposites is presented. These properties are assumed to be dependent on the CNTs diameter and number of walls, identified as key characteristics of these reinforcements. The analysis is carried out using a micromechanical model based on the mean field homogenization theory for the prediction of the composite elastic properties of a MWCNT – epoxy resin system. A transversally isotropic elastic behavior has been considered for the CNTs based on values/dependencies reported in the literature. Interphase properties between the CNT and epoxy resin has been investigated by means of molecular dynamics simulations.
Computation of elastic moduli of nanocrystalline materials using Voronoi models of representative volume elements
Authors: Bazios Panagiotis , Tserpes Konstantinos , Pantelakis Spiros
Published: August 2018

In the present work, a numerical model is developed to predict the Young’s modulus and shear modulus of nanocrystalline materials using a Finite Element Analysis. The model is based on Representative Volume Elements (RVE) in which the microstructure of the material is described using the Voronoi tessellation algorithm. The use of the Voronoi particles was based on the observation of the morphology of nanocrystalline materials by Scanning Electron and Transmission Electron Microscopy. In each RVE, three-dimensional modelling of the grain and grain boundaries as randomly-shaped sub-volumes is performed. The developed model has been applied to pure nanocrystallline copper at grain volume fractions of 80%, 90% and 95% taking also into account the parameters of grain size and grain boundary thickness. The elastic moduli of nanocrystalline copper have been computed by loading the RVE in tension. The numerical results reveal that the elastic moduli of nanocrystalline copper increase with increasing the grain volume fraction. On the other hand, for a given grain volume fraction, the results showed no effect of the grain size. The model predictions have been validated successfully against numerical results from the literature and predictions of the Rule of Mixtures and the Mori-Tanaka analytical model.
On the precise measurement capability of the direct microscopic measurement method for wear volume characterization
Authors: Türedi Enbiya
Published: August 2018

There are plenty of methods for determining the wear volume after a wear test. Due to the geometrical assumptions, some of them could unfortunately lead to mistaken results. It has been shown that a novel method, the direct microscopic measurement, is able to calculate the wear volume on a specimen surface very precisely and accurately [1-2]. It is based on creating a series of line profiles perpendicular to the wear scar. This novel method, however, needs to be characterized in terms of measurement limitations and minimum detectable volume capability. For example, how small or how shallow a wear scar could be calculated or measured with this method, must be determined. For this purpose, it has been prepared a series of wear test specimens exposed to the different amounts of wear in a “pin-on-disk” type test rig. As specimens, two different non-ferrous mold materials, Al bronze alloys, were selected and prepared metallographically. Counterpart materials were inox steel and bearing steel balls with diameter of 6 mm. Normal load was set to 5 N. Test configurations were set to 1, 5, 10 and 100 m of sliding distance values, in turn. Wear tests were conducted in according to ASTM G99 standard. Wear volume results were determined both direct microscopic measurement and also a 3D optical microscope methods. Comparison results showed that the novel method could be successfully used for wear volume calculations even with small amounts of wear volume conditions.
Indirect determination of the mechanical properties of stochastic lattices
Authors: Maliaris Georgios , Lazaridis Theologos , Sarafis Ilias T. , Kavafaki Sofia
Published: August 2018

Determination of the mechanical behaviour of lattice structures has become a necessity to successfully implement lightweight concepts in various applications. Due to the large surface to volume ratio of these structures, the computational effort required for the FE simulation of models incorporating lattices is significantly increased mainly because of the large finite elements number which are necessary to accurately describe the complex input geometry. In this work a simple solution is employed in order to calculate the stress – strain properties, using a bilinear material law and equivalent bulk geometry. The verification of the FE model is fulfilled through the comparison of the lattice deformation and compressive force between experimental data and FE calculated results. After the verification of the FE model, it was possible to determine the mechanical behaviour of stochastic lattices, for an extended range of the investigated parameters, using only computational tools.
Multiaxial Fatigue Life Calculation Model for Engineering Components in Rolling-Sliding Contact
Authors: Basan Robert , Marohnić Tea
Published: August 2018

Number of important engineering components and elements such as gears, rollers, bearings operate in conditions of rolling-sliding contact loading. Determination of fatigue lives of such components and elements is very important for engineering practice but remains quite chalenging task due to complex states of stress and strain in the material in the vicinity of contact (multiaxiality, non-proportionality, rotation of principal axes, mean compressive stress) as well as complex contact conditions such as loading amplitude, complex geometry of bodies in contact, type of lubrication, value of coefficient of friction, etc. Proposed fatigue life calculation model for cases of rolling-sliding contact is based on critical plane approach in the form of Fatemi-Socie crack initiation criterion. Developed model was implemented in the case of gears teeth flanks in mesh and compared with results and fatigue lives of gears reported in literature. Good agreement was determined confirming validity of developed model. Further advantage of presented approach and developed model is obtained information on critical location(s) and critical plane(s) orientation which can subsequently be used for estimation of crack shapes in initial phases of their growth and later damage type into which they can be expected to develop.
Surface structure, pore characteristics and mechanical response of aluminum foam processed by wire-EDM and milling
Authors: Michailidis Nikolaos , Klink Andreas , Smyrnaios Emmanouil , Olivier Marcel , Baklatzoglou Nearchos , Welschof Lukas , Stergioudi Fani
Published: August 2018

Material removal processes like milling, leave only a small process window to minimally distort the surface of Aluminum foams. Wire-EDM arises as a suitable alternative. Closed-cell aluminum foams were produced and processed at various conditions through wire-EDM to investigate their effect on the foams' surface integrity. Microstructural analysis, porosity assessment and mechanical testing were employed to evaluate the footprint of the manufacturing process. Depending on the process parameters and especially on the working fluid, severe surface and pores damage may occur, affecting the mechanical response under quasistatic and high-velocity impact loads. A process optimization loop offered a distortion-free surface.
State of the Art and Emerging Trends in Additive Manufacturing: From Multi-Material processes to 3D printed Electronics
Authors: Lehmhus Dirk , Busse Matthias , von Hehl Axel , Jägle Eric
Published: August 2018

Additive manufacturing is considered a disruptive technology that is expected to revolutionize production technology and affect value chains on a global scale. The scope of accessible materials ranges from polymers to metals and ceramics as well as composites. The keynote will provide an overview of available manufacturing processes for the various material groups and discuss the specific advantages of additive manufacturing – e.g. realization of complex geometries, part count and assembly effort reduction, art-to-part approach - in view of selected applications and production scenarios. Further to this, selected emerging trends in additive manufacturing will be presented and discussed, including fabrication of composites, hybrid structures, multi-material techniques and associated promises with respect to local tailoring of material properties, and the integration of sensors and/or electronic systems in AM parts.
Aerodynamic Modelling and Analysis of a Novel Mechanism for Chord and Camber Morphing Wing
Authors: Şahin Harun Levent , Çakır Bora Orçun , Yaman Yavuz
Published: August 2018

This paper presents the aerodynamic modelling and analysis of surfaces created by a novel deployable mechanism, which is composed of a four-bar linkage and a scissor-structural mechanism (SSM) which contains several scissor-like elements (SLEs). With the help of that mechanism, which is located inside the trailing portion of wing section, continuous adjustment of the airfoil is possible. In order to highlight the advantageous aerodynamic characteristics of newly created airfoil geometries via proposed SSM, several aerodynamic analyses have been performed. The flow characteristics used for the analyses are determined by the flight envelope of an intended generic UAV. Since the maximum speed range of the sample aircraft is well below Mach 0.3, incompressible flow assumption is made throughout the solutions and conservation laws of Reynolds Transport Theorem are employed.
Parametric design and Finite Element Analysis of metallic tanks transporting dangerous goods
Authors: Sykaras Konstantinos , Malikoutsakis Michail , Loulas Minas , Mihailidis Athanassios
Published: August 2018

Metallic tanks are widely used for the transportation of dangerous goods. Manufacturers utilize standards in conjunction with European legislation concerning the international carriage (ADR and RID) to specify the minimum design and construction requirements. The analysis of the tank’s attachment to the vehicle is not covered by analytical calculation methods, and only the Finite Element stress analysis can be used prior to manufacture. New ADR amendments demand that the certification authorities conduct stringent examinations that the manufacturer has the ability to perform high quality weldings. Applying the structural strength concept implemented in the International Institute of Welding (IIW) guidelines into the calculation is a protracted task. Aiming at speeding up the procedure, a parametric design and an efficient FE analysis is developed for a LGBF tank. Utilizing parametric design offers sufficient overview of the whole structure, while a supplementary surface model is generated to reduce pre-processing time. The tank is subjected to prescribed load cases, while the meshing directives of the structural hot spot stress concept (SHSSC) according to the IIW recommendations are incorporated in the procedure, in order to assess both the static and fatigue strength of the weld details. Using a multi-compartment LGBF tank as a case study, it is shown that the proposed detailed and automated analysis succeeds in reducing the time and effort needed, as well as in allocating the critical spots, substantially increasing the calculation accuracy.
Integrity Analysis of the Rainwater Pump Impeller
Authors: Galatanu Sergiu-Valentin , Muntean Sebastian , Marsavina Liviu , Micota Dan , Draghici Ionel
Published: August 2018

The purpose of this paper is to examine the failure problems encountered during the operation of the rainwater pump impellers installed in a wastewater station. The rainwater pumps are specially designed to operate in wastewater plants. The fibbers and wastes are discharged together with rainwater during storms with this type of pumps to avoid the flood of the wastewater station. Several problems have occurred in service due to the fibbers clog the gap between the impeller blades and the pump casing. The analysis of the catastrophic events associated to the rainwater pumps installed in a wastewater station is performed. As a result, it has been identified that the catastrophic events are due to the brittle fracture of the fasten bolts connecting the impeller blades and the pump hub, respectively. Analytical and numerical analysis were perform in order to determine the maximum shear stress on the fasten bolts. As a conclusion the partial clogging of the gap between one impeller blade and pump casing, inducing the lock of the blade and leading to catastrophic failure.
A test method for the determination of the peel resistance of the bonded rubber lining of conveyor belt metal drums
Authors: Papanikolaou Sofia , Maropoulos Andreas , Fasnakis Dimitrios , Maropoulos Stergios
Published: August 2018

A test method for the peel resistance of the bonded rubber lining of large of large conveyor belt metal drums is presented that will assist engineer in designing conveyor systems with predetermined specifications. A simple specimen preparation method is developed and the peel strength of the liming is measured using a modified version of the Standard EN 28510-1:2014, 'Adhesives-Peel test for a flexible-bonded-to-rigid test specimen assembly' [1]. The method was applied to various types of samples and it was found that only metal drums where the rubber lining was bonded using hot-vulcanisation under pressure satisfied the condition of the peel force greater than 2 N/m.
A critical review of FEM models to simulate the nano-impact test on PVD coatings
Authors: Skordaris Georgios , Bouzakis Konstantinos , Charalampous Paschalis
Published: August 2018

Nano-impact test is a reliable method for assessing the brittleness of PVD coatings with mono- or multi-layer structures. For the analytical description of this test, a 3D-FEM Finite Element Method (FEM) model and an axis-symmetrical one were developed using the ANSYS LS-DYNA software. The axis-symmetrical FEM simulation of the nano-impact test can lead to a significantly reduced computational time compared to a 3D-FEM model and increased result's accuracy due to the denser finite element discretization network. In order to create an axissymmetrical model, it was necessary to replace the cube corner indenter by an equivalent conical one with axis-symmetrical geometry. Results obtained by the developed FEM models simulating the nano-impact test on PVD coatings with various structures were compared with experimental ones. Taking into account the sufficient convergence between them as well as the reduced calculation time only in the case of an axis-symmetrical model, the latter introduced numerical procedure can be effectively employed to monitor the effect of various coating structures on their brittleness.
Failure analysis of Rotating Blades of Lowpressure Steam Turbine Rotors and Possibility of Prediction Corrosion-fatigue Ruptures
Authors: Kasl Josef , Matějová Miroslava , Mrštík Jakub
Published: August 2018

Over the last few years, corrosion fatigue fractures initiating from corrosion pits have been a root cause of failures of rotating blades of the third stage of the low-pressure parts in several 200 MW turbines in ČEZ a.s. power stations. This contribution deals with the analysis of several of these failures. Metallurgical investigation of the blades showed that the cause of the failures was the initiation and growth of a fatigue crack from a corrosion pit. ČEZ, a.s. has developed, based on the knowledge obtained by EPRI (Electric Power Research Institute), a methodology which can, in real conditions during checks of turbines, reliably detect the parameters of corrosion pits and predict the possibility of development of fatigue damage from detected pits. The process of methodology and its uncertainties (influence of filling of pits with oxides, cyclic stress calculations, and the selection of the geometric factor Y) are summarized.
The role of NDI on the failure analysis of an aircraft propeller hub
Authors: Spyroglou Iordanis , Koutsomichalis Angelos , Stavropoulos Panos , Roussis Nikolaos
Published: August 2018

This paper analyses the causes of an incident in an aircraft propeller hub. The aluminum alloy propeller blade hub was detached from the plane bearing one of its two blades with the other one being jettisoned away. Stereoscopic examination of the fractured hub revealed that it was initially cracked by fatigue, with the crack initiating on the root of the third and fourth spirals and propagating form the inner to the outer. SEM analysis showed that the crack epicentres were created very close or/and on the spiral roots and were attributed to microcracks from corrosion pits and high stress concentration. Non Destructive Inspection was both used on the other side of the hub and the remaining three hubs of the plane and confirmed the presence of cracks similar to those which caused the fatigue failure of the fractured hub but at earliest stage of development.
Full Scale Fatigue Test and Failure Analysis of Advanced Jet Trainer Wing
Authors: Horak Vaclav , Novotny David
Published: August 2018

A verification method for the fatigue life of the jet trainer wing with integrated fuel tanks is presented. The test was performed to identify the critical points of the structure, to determine strain data and to proof fatigue life of the wing. During the test the non-destructive inspection methods for the identification and evaluation of the critical failures were employed; i.e. visual, ultrasonic and eddy current method. The failures were classified according to significance and reparability. The special test rig was designed to redistribute the load on the structure and to determine test data. The load control system MTS AeroSTTM was used for fatigue test control. The fatigue load sequences with multilevel profiles of static and fatigue loading were applied. During the test, more than 230 failures were identified. The critical failures were repaired when found using two types of repair (metal and composite). The repairs were monitored during subsequent fatigue test run and evaluated to utilize in service.
Experimental investigation of the failure modes of in-plane loaded inserts in CFRP sandwich panels
Authors: Richert Philip , Dafnis Athanasios , Schröder Kai-Uwe
Published: August 2018

The aim of this paper is the experimental determination and investigation of the different failure modes of various insert types under inplane load in sandwich materials with CFRP face sheets and a perforated aluminum honeycomb core. In addition, also insert under an out-of-plane load are tested. In total three different kind of inserts are investigated: blind inserts, trough-the-thickness inserts and special inserts which are developed within the iBOSS research project. The inserts are tested until failure and monitored with the digital image correlation system Aramis. This test monitoring is intended to determine the first failure mode. It is shown that this works well for out-of-plane loaded insert connections and the special inserts under in-plane load. However, this does not work so well with in-plane loaded standard inserts. In further investigations, a failure of the adhesive shortly before failure of the top layers can be shown.
A comprehensive evaluation of cache utilization characteristics in large scale WSN considering network driven cache replacement techniques
Authors: Panagiotou Christos , Antonopoulos Christos , Koubias Stavros
Published: August 2018

WSNs as adopted in current smart city deployments, must address demanding traffic factors and resilience in failures. Furthermore, caching of data in WSN can significantly benefit resource conservation and network performance. However, data sources generate data volumes that could not fit in the restricted data cache resources of the caching nodes. This unavoidably leads to data items been evicted and replaced. This paper aims to experimentally evaluate the prominent caching techniques in large scale networks that resemble the Smart city paradigm regarding network performance with respect to critical application and network parameters. Through respective result analysis valuable insights are provided concerning the behaviour of caching in typical large scale WSN scenarios.
Hämochromatose-assoziierte Arthropathien
Authors: Braner Axel
Published: August 2018

Arthropathy is the most common and often the earliest clinical manifestation of hereditary hemochromatosis (HH). It is difficult to treat and there is a high risk for early endoprosthetic joint replacement. Research done during the last decade shows that it is a joint disease in its own right. Clinically, there are degenerative articular changes with an atypical pattern of distribution, a crystal arthropathy (CPPD) with congenital joint swelling and synovitis like in RA. The X-ray image shows typical but not exclusive findings. In MRI, groundbreaking subchondral findings are found, especially in the large joints, and ultrasound shows inflammatory lesions in non-arthropathy patients as well. In animal experiments and pathomorphological studies of the synovial membrane, the arthropathy can be differentiated from osteoarthrits and RA. The pathophysiological significance of iron overload can be distinguished from immunohistochemical and cytogenetic investigations in chronic degenerative HH arthropathy and inflammatory-destructive arthropathy in hemophilia. By elucidating the pathophysiology, new therapeutic approaches can be formulated. In addition to colchicine, the IL-1 receptor antagonist anakinra is available for activation of the NLRP3 inflammasome by CPPD crystals and subsequent induction of IL-1β overproduction. Other manifestations include symptomatic pain therapy and intensive physiotherapy and occupational therapy. To promote further research into hemochromatosis arthropathy, the Hemochromatosis Arthropathy Research Initiative (HARI) was established in 2016.
Geht’s den Eltern gut, geht’s dem Kind gut
Authors: Lusebrink Christina , Kappel Nadine , Kocks Andreas
Published: August 2018

98 Prozent der Geburten in Deutschland finden im Krankenhaus statt. Nicht immer ist Geburtshilfe und die Betreuung in der Schwangerschaft oder im Wochenbett eine
rein problemlose und glückliche Zeit. Immer wieder gibt es auch gesundheitliche, soziale oder psychische Herausforderungen, die die Mutter, den Vater, das Kind
und auch die ganze Familie belasten. Das Konzept der Frühen Hilfen im Krankenhaus hat es sich zur Aufgabe gemacht, früh Unterstützungen anzubieten und Experten
aus unterschiedlichen Professionen zu vernetzen. Dabei verfolgt das Konzept die Maxime: Geht es der Mutter und der Familie gut, geht es dem Kind gut.
Prävention: neue Impulse von Pflegekassen
Authors: Blättner Beate
Published: August 2018

Macht Pflege nicht ohnehin Prävention? Gesundheit zu fördern und Krankheit zu verhüten, gehört zum beruflichen Selbstverständnis der Pflege. Seit der
Einführung des Präventionsgesetzes im Jahr 2015 sollen Pflegekassen in der voll- und teilstationären Pflege darüber hinaus präventive Leistungen für stationär
Pflegebedürftige erbringen. Die Abgrenzung solcher Maßnahmen von der aktivierenden Pflege führt oft zur Irritation – zu Unrecht, denn beide Ansätze ergänzen
sich.
Selbstbestimmte Zukunft der Pflege?!
Authors: Zergiebel Dominik
Published: August 2018

Zeichen Die Entstehung von Pflegekammern in drei Bundesländern und die Vereinigung der Pflegenden in Bayern sind ein Zeichen: Pflege soll in der Politik und in der Öffentlichkeit gehört werden. Was sind aber die Unterschiede zwischen Selbstverwaltung in Kammern und einer Interessenvertretung? Wer sind Unterstützer und wer Kritiker und wen vertreten sie?
Neuromuscular Parameters Predict the Performance in an Incremental Cycling Test
Authors: García-García Oscar , Cuba-Dorado Alba , Fernández-Redondo Diego , López-Chicharro José
Published: August 2018

The aim was to determine the predictive capacity of neuromuscular parameters on physiological predictors of performance related to pedaling power. The sample comprised fifty elite cyclists. On the same day, they were given a neuromuscular evaluation with tensiomyography (TMG) and then performed an effort test on a cycle ergometer until exhaustion. The TMG recorded the maximum radial muscle belly displacement, contraction time, delay time, derivative normalized response speed, and lateral symmetry. Peak power output (Wpeak·kg−1), effort time, maximum lactate concentration, power in the first lactate threshold, and power in the second lactate threshold were recorded in the effort test. Linear regression analysis was used to determine the explanatory capacity of neuromuscular parameters on potential cycling performance indicators. A higher Wpeak·kg−1 during a maximal incremental test on the cycle ergometer can be predicted moderately (R2=0.683; R2a=0.615; R=0.826; Std. Error=0.26017; p<0.001) by a longer rectus femoris contraction time and a greater radial muscle belly displacement of the vastus lateralis and vastus medialis as well as a slower normalized response speed of the biceps femoris. In conclusion, neuromuscular parameters can partially explain performance in a specific cycling test until exhaustion.
Nykturie beim Benignen Prostatasyndrom
Authors: Oelke Matthias , Fangmeyer Bernhard , Zinke Jörg , Witt Jörn
Published: August 2018

Nykturie, definiert als Miktion von mindestens 1 Mal pro Nacht, ist eines der am häufigsten vorkommenden Symptome bei Männern mit benignem Prostatasyndrom (BPS) und oft Ursache für Arztkonsultationen. Nykturie ist für den Betroffenen nicht nur lästig, sondern auch für eine erhöhte Morbidität und Mortalität verantwortlich. Nykturie kann durch eine vermehrte Flüssigkeitsaufnahme, gesteigerte Diurese oder verminderte Blasenkapazität verursacht werden. Häufig liegen beim einzelnen Mann mehrere Ursachen vor, die nur durch systematische Abklärung detektiert und differenziert werden können. Das Blasentagebuch für drei Tage ist ein essenzieller Bestandteil bei der Abklärung der zugrundeliegenden Pathophysiologie, die Grundlage für eine rationelle Therapie der Nykturie darstellt. Behandlungsziele sind die Reduktion der Miktion auf weniger als 2 Mal pro Nacht, die Verlängerung der ersten Schlafphase auf über 4 Stunden, die durch den Schlafmangel ausgelöste verminderte Lebensqualität wieder herzustellen und die mit Nykturie assoziierte Morbidität und Mortalität zu senken. Liegt beim Patienten mit BPS eine funktionell reduzierte Blasenkapazität durch Restharnbildung vor, können α-Blocker, 5α-Reduktasehemmer, Phosphodiesterase Typ 5-Inhibitoren, Pflanzenextrakte oder Prostataoperationen (z. B. TURP) die Nykturiefrequenz signifikant senken. Liegt jedoch eine nächtliche Polyurie vor, wie bei 80 % der BPS-Patienten mit Nykturie nachgewiesen wurde, sollte das therapeutische Ziel die Verminderung des nächtlichen Urinvolumens sein. Bei Mangel des antidiuretischen Hormons (Arginin-Vasopressin) ist die Einnahme von Desmopressin vor dem Schlafengehen die erste Therapiewahl. Eine neue galenische Zubereitung von Desmopressin reduziert die Wahrscheinlichkeit der Hyponatriämie und kann daher auch bei Männern über 65 Jahre sicher eingesetzt werden. Eine Medikamentenkombination könnte bei Männern mit mehreren Ursachen für die Nykturie sinnvoll sein.
Video-Thoracoscopic Management of Postpneumonectomy Empyema
Authors: Spaggiari Lorenzo , Galetta Domenico
Published: August 2018

Background Postpneumonectomy empyema (PPE) is a serious complication even when it is not associated with bronchopleural fistula (BPF). Besides irrigation, an aggressive treatment is usually applied for removing infected material. However, a minimally invasive approach might achieve satisfactory results in selected patients.

Methods We retrospectively identified 18 patients presenting with PPE receiving video-thoracoscopic approach. Of these 18 patients, pneumonectomy was performed for nonsmall cell lung cancer in 15 cases, for mesothelioma in 2, and for trauma in 1 case. There were 14 males and 4 females, (mean age, 62 years; range, 44–73 days). Empyema was confirmed by thoracentesis and bacteriological examination. All patients had immediate chest tube drainage and underwent thoracoscopic debridement of the empyema. Fifteen patients had no proven BPF; two had suspicious BPF, and one had a minor (<3 mm) BPF.

Results Median time from pneumonectomy to empyema diagnosis was 129 days (range, 7–6205 days). Median time from drain position to video-assisted thoracoscopic surgery (VATS) procedure was 10 days (range, 2–78 days). A bacterium was isolated in 13 cases (72.2%). There was no mortality and no morbidity related to the procedure. The average duration of thoracoscopic debridement was 56 minutes (range, 40–90 minutes). Median postoperative stay was 7 days (range, 6–18 days). Only in one patient an open-window thoracostomy was performed. Median follow-up of the 18 patients receiving thoracoscopy was 41.5 months (range, 1–78 months). None had recurrent empyema. The patient with a minor BPF remained asymptomatic and is doing well at 48 months follow-up.

Conclusions Thoracoscopy might be a valid approach for patients presenting with PPE with or without minimal BPF. Video-thoracoscopic debridement of postpneumonectomy space is an efficient method to treat PPE.
A Pilot Study of Prospective Data Collection by Italian Homeopathic Doctors
Authors: Andreoli Beatrice , Zanolin Elisabetta , Bellavite Paolo
Published: August 2018

Objective The main purpose of this article is to report the systematic data collection pertaining to the consultations of a group of qualified homeopathic physicians. Studies have been performed concerning: (1) the most frequently treated pathologies; (2) the symptoms reported by patients, with a particular focus on “fear” symptoms; and (3) the evaluation of the outcomes of the treatment, including likelihood ratio (LR) for fear symptoms of mostly prescribed remedies.

Design Prospective observational study.

Setting Individualized homeopathic treatment at private homeopathic surgeries in Italy.

Participants Adult patients asking for homeopathic therapy for a series of common ailments.

Outcome Measures Types of diseases and remedies used and clinical parameters (frequency of acute attacks, and their intensity and duration); the overall outcome of the cure was registered using the Outcome Related to Impact on Daily Living (ORIDL) scale.

Results Only 94 patients could be enrolled by eight homeopathic doctors in a 2-year period between 2015 and 2017. Ninety (72 females, 18 males) patients completed the observation period. The most represented pathologies belonged to the group “Anxiety and anxiety disorders” followed by gastrointestinal ailments. The most prescribed remedy was Phosphorus (9 cases), followed by Natrum muriaticum (4 cases) and Ignatia (4 cases). The intensity of the symptoms and the frequency of the attacks decreased during the course of the study. Most patients reported a positive outcome (ORIDL scale). In the “Phosphorus” group, LR values were calculated for fear symptoms: LR+ for fear of dark = 2.25 (95% confidence interval [CI] = 0.56 to 9.02), LR− for fear of crowds = 1.27 (95% CI = 1.13 to 1.42), and LR− for fear of ghosts = 1.12 (95% CI = 1.04 to 1.22).

Conclusion The recruited group was smaller than expected, but data from most participants could be collected. Positive clinical outcomes were recorded and LR of a few specific fears contributed to distinguish Phosphorus patients from the remaining population.
Reduction and Association of the Scaphoid and Lunate: A Functional and Radiographical Outcome Study
Authors: Aibinder William , Izadpanah Ali , Elhassan Bassem
Published: August 2018

Background Management of scapholunate (SL) ligament disruption is a challenging problem. The reduction and association of the scaphoid and lunate (RASL) procedure has been described with varying results. This study assessed the outcomes of the RASL procedure.

Purpose The objective of this study was to assess the outcomes of patients undergoing the RASL procedure at our institution in regard to pain relief, range of motion, radiographic and functional outcomes, complications, and reoperations.

Materials and Methods Twelve patients with symptomatic chronic SL instability underwent the RASL procedure. The mean age was 35 years. The mean time from injury to surgery was 40 weeks. The mean follow-up was 89 months. Outcomes included visual analog score for pain, wrist range of motion, grip strength, and Mayo Wrist Scores. Preoperative and postoperative radiographs were reviewed.

Results Pain scores improved in 10 wrists. Range of motion and grip strength worsened. The average Mayo Wrist Score was 63.3. The mean SL diastasis and angle improved, but seven wrists developed progressive degenerative changes, with two requiring a salvage procedure. Symptomatic progressive screw lucency occurred in eight wrists requiring screw removal.

Conclusion The RASL procedure can improve SL widening but has a high rate of early failure and reoperation. Following reoperation, long-term follow-up demonstrates reasonable long-term durability in some cases.

Level of Evidence This is a Level IV, therapeutic case study.
Breast tumor cell hybrids form spontaneously in vivo and contribute to breast tumor metastases
Authors: Chitwood Casey A. , Dietzsch Claire , Jacobs Gabriel , McArdle Tanner , Freeman Brian T. , Banga Annanya , Noubissi Felicite K. , Ogle Brenda M.
Published: August 2018

Cancer cell fusion was suggested as a mechanism of metastasis about a century ago. Since then, many additional modes of material transfer (i.e., tunneling nanotubes, and exosomes) to generate cell hybrids have been identified. However, studies documenting spontaneous tumor hybrid formation in vivo as a mechanism that enables metastasis are still lacking. Here, we tested whether spontaneous hybrid formation in vivo contributes to bona fide metastatic tumors. We first used single cell RNASeq to analyze the gene expression profile of spontaneously formed cancer cell-stromal hybrids, and results revealed that hybrids exhibit a clustering pattern that is distinct from either parental cell and suggestive of substantial diversity of individual hybrids. Despite the newly gained diversity, hybrids can retain expression of critical genes of each parental cell. To assess the biological impact of cancer cell hybrids in vivo, we transfected murine mammary tumor cells, isolated from FVB/N-Tg(MMTV-PyVT)634Mul/J mice (PyVT) with Cre recombinase prior to injection to the murine fat pad of FVB.129S6(B6)-Gt(ROSA)26Sortm1(Luc)Kael/J mice such that luciferase expression is induced with hybrid formation; luciferase expression was tracked for up to four months. We observed that hybrid formation occurs spontaneously in vivo and that a significantly higher number of hybrids reside in metastases compared to the primary tumor, supporting the possibility that hybrids can emerge from the primary tumor and proliferate to help create a new tumor at a distant site. Additional studies are now warranted to delineate the mechanisms of cancer cell hybrid transit to metastases since drugs to inhibit hybrid formation might prevent metastatic spread.