bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modelling and comparison analysis of pressure distribution in the gas film for non-contacting face seals
Authors: Blasiak Slawomir
Published: June 2019

The tightened-up norms concerning the emission of harmful substances into the natural environment are putting before designers of knots sealing very rigorous requirements. One should notice that mechanical seals are ones of most often applied sub-assemblies of the sealing nodes. The main task for mechanical seals is to maintain maximum tightness. They are applied practically in all branches of industry and must fulfil their function while working under various operating conditions. The determination of the pressure distribution in the fluid film layer is necessary to calculate the gasdynamic force and moments. A two-dimensional equation of Reynolds was solved based on Finite Volume Method (FVM). At the presented work findings of the simulation results concerning the comparison get based on the author's computer program in C++ language with results obtained from the commercial ANSYS CFX program was presented.
Calibration of Circulating Tumor Cell’s Model in Narrow Flow
Authors: Bohiniková Alžbeta , Bachratá Katarína
Published: June 2019

In this article our objective was to calibrate model of Circulating Tumor Cell (CTC). Diﬀerent types of cancer produce diﬀerent types of CTCs. For research purposes, we chose to set up the model according to MCF7 breast cancer cell lines, due to the availability of data from laboratory experiments. First, to obtain working model we used mechanics of our already existing RBC model, taking into consideration the diﬀerences between RBC and CTC. Next step was to find values for the elastic parameters of the cell model. We have chosen laboratory experiment where the deformability of breast cancer cell passing through narrow microfluidic channel was examined. The channel has similar dimensions as blood capillaries to mimic the in vivo environment. In order to achieve similar behavior of the cell’s model and the real cell in the experiment we needed to set fluid flow according to experimental data. This was achieved by adjusting the fluid force that is dependent on the volumetric flow rate. Due to the long computational time of the simulation we devised a function between the entry time and the volumetric flow rate. Afterwards we also found dependencies between the changes in elastic parameters and entry time, and we were able to set the elastic parameters so they mimic the behaviour from the laboratory experiment. Further work lies in validating these results.
Reduction and comparison of compressed air consumption in linear pneumatic motors
Authors: Fojtášek Kamil , Dorazil Antonín , Homa Dorota
Published: June 2019

Pneumatic mechanisms are used in a wide range of industrial applications. For transmission of energy and information in pneumatic mechanism are used compressed air. Production and distribution of compressed air in pneumatic systems leads to considerable losses. This fact causes a relatively low overall efficiency of the pneumatic system. The article will compare the possibilities of reducing compressed air consumption in linear pneumatic motors.
Thermal analysis of the car windscreen
Authors: Ho ejowska Sylwia , Orzechowski Tadeusz , Pawi ska Anna
Published: June 2019

The task of the ventilation and heating/cooling system in cars is to maintain the thermal comfort conditions in the passenger compartment to ensure safe driving. Designing such systems requires knowledge of many physical parameters, which often have to be specified individually. Such factors include heat transfer coefficients. The paper presents the results concerning the determination of the local heat transfer coefficients at the interface between the car windscreen and the cooling air from the inner side of the passenger compartment. The temperature of the outer side of the vehicle windscreen was measured using infrared thermography. The 2D mathematical approach describing the steady state heat transfer on a car windscreen was proposed. The temperature distribution was determined by the Trefftz method, and the heat transfer coefficient at the air–vehicle windscreen interface was calculated using the third type boundary condition. Graphs were used to represent thermographic images of the vehicle windshield, its temperature distribution, and corresponding values of local heat transfer coefficients as a function the length of the windshield. Results are presented and discussed.
Flow field velocity measurement of liquid interaction with rigid and flexible wall
Authors: Jasikova Darina , Kotek Michal , Pochyly Frantisek , Kopecky Vaclav
Published: June 2019

The motivation of this research was to determine the flow interactions on the pulsation and to express the influence on the flow character in the rigid and flexible tube. The character of Newtonian liquid was measured with the Particle Image Velocimetry method (PIV). Here, we used glass tube and Tygon tube for our comparison. We build the circuit equipped with membrane pump for generating pulsatile flow. The results were analysed over the pulse period sampled in 10 time steps. The fluid flow varied from Re 560 to Re 8800. The velocity profiles uncovered backward revers flows closed to the wall. These structures are prevailing close to flexible wall. The effect of interaction between pulsatile liquid flow and flexible wall was experimentally proved.
Settling slurry flow near deposition velocity in inclined pipe of negative slope
Authors: Kesely Mikoláš , Matoušek Václav , Vlasák Pavel
Published: June 2019

Pipe flow of sand-water slurry (settling slurry) is sensitive to pipe inclination. The effect of the angle to which the partially stratified flow is inclined from the horizontal has been subject to investigation in numerous studies. However, almost all of them focus on ascending flows, i.e. flows inclined to positive angles of inclination. It is well known that settling slurry flows inclined to negative slopes (descending flows) differ from those inclined to positive slopes, particularly at velocities near the deposition limit. The deposition limit velocity is the flow velocity at which stationary deposit starts to be formed at the bottom of the pipe. We investigate the effect of the negative slope on pipe flow near deposition limit velocity in the broad range of inclination angles. Besides the deposition limit, we focus on the distribution of solids across the pipe cross section. We combine experimental approach with mathematical modelling. Our new experiments with medium-to-coarse sand (mass-medium grain size 0.87 mm) in a 100-mm pipe inclined from 0 to -45 degree provide suitable data for a validation of predictions of our layered model for partially stratified flows in inclined pipes.
CFD analysis of probe interaction with expanding wet steam
Authors: Kolovratník Michal , Jun Gukchol , Bartoš Ondřej
Published: June 2019

Research on the impact of the interaction between an optical probe and the expanding steam flow field in a steam turbine on the measured parameters of the liquid phase of the wet steam has been ongoing at Czech Technical University in Prague (CTU) for several years. Previous CFD analyses were newly supplemented by the effect of changing the diameter and number of fine droplets as well as changing of steam wetness in the probe measuring space. The knowledge obtained was used to improve corrections of the extinction measurements at CTU and for conceptual design of a new extinction probe for phase transition investigation in high pressure steam. This paper briefly introduces these results.
Experimental measurements of gravity casting flow
Authors: Lobovský Libor , Mandys Tomáš
Published: June 2019

An experimental investigation of casting processes performed under well controlled laboratory conditions is presented. Casting molds made of transparent material allow for analysis of flow patterns by means of standard optical measurement methods. The tests are carried out for selected highly-viscous Newtonian fluids at room temperature. The physical properties of the test fluids (i.e. viscosity, surface tension and density) are identified. As a result, an extensive set of experimental data is provided.
2D and 3D numerical modelling of internal flow of Pressure-swirl atomizer
Authors: Maly Milan , Slama Jaroslav , Sapik Marcel , Jedelsky Jan
Published: June 2019

This paper compares 2D axisymmetric and 3D numerical models used to predict the internal flow of a pressure-swirl atomizer using a commercial software Ansys Fluent 18.1. The computed results are compared with experimental data in terms of spray cone angle (SCA), discharge coefficient (CD), internal air-core dimensions and swirl velocity profile. The swirl velocity was experimentally studied using a Laser Doppler Anemometry in a scaled transparent model of the atomizer. The internal air-core was visualized at high temporal and spatial resolution by a high-speed camera with backlit illumination. The internal flow was numerically treated as transient two-phase flow. The gas-liquid interface was captured with Volume of Fluid scheme. The numerical solver used both laminar and turbulent approach. Turbulence was modelled using k-ε, k-ω, Reynolds Stress model (RSM) and coarse Large Eddy Simulation (LES). The laminar solver was capable to predict all the parameters with an error less than 5% compared with the experimental results in both 2D and 3D simulation. However, it overpredicted the velocity of the discharged liquid sheet. The LES model performed similarly to the laminar solver, but the liquid sheet velocity was 10% lower. The two-equation models k-ε and k-ω overpredicted the turbulence viscosity and the internal air-core was not predicted.
Leidenfrost evaporation of a single droplet of gasoline blends of ethanol
Authors: Orzechowski Tadeusz
Published: June 2019

The increase in energy consumption is observed since the middle of the 20th century. At the same time, the International Energy Agency (IEA) forecasts a 50% increase in energy consumption by 2030. One of the ways to reduce the consumption of such fuels are small additions received from natural gas and renewable energy sources. Mixtures of alcohols with gasoline and diesel oil are produced. Their small additions allow for a certain share of energy from renewable sources without a noticeable change in the combustion characteristics of such fuels. The paper presents the studies on the evaporation of drops of gasoline with a total composition CnHn+2, where n = 5 to 7. Its components are distillation products of crude oil with a low flash point. It is a colourless liquid mixture which main components are: n-heptane, neohexane and cyclopentane. The evaporation characteristics of such a drop with the addition of ethanol are also given. The result of the conducted research is the loss of mass during the drop carried above the surface with temperature above the Leidefrost point.
Numerical study of the low-Reynolds flows in the vertical heated caverns
Authors: Petrichenko Mikhail , Sergeev Vitaly , Nemova Darya , Kotov Evgeny , Tarasova Darya
Published: June 2019

The object of research is the critical geometry of a three-dimensional air flow in a cavern between two vertical heated plates. In this rate the convection's contribution to heat transfer will be limited due to thermal conductivity at a fixture temperature drop. A three-dimensional RANS approach closed by the k-w SST turbulence model in conjunction with the energy equation. The model validated and verified by comparison with the experimental results. The results of the work applied in developing of ventilated façades.
Validation of numerical methods for flow patterns modeling based on comparison with the results of laboratory experiments using visualization methods
Authors: Sergeev Daniil , Kandaurov Alexander , Ermakova Olga , Suvorov Anatoly
Published: June 2019

A series of laboratory and numerical experiments were carried out to study the structure of the turbulent flow over a rectangular obstacle for high Reynolds number. The results of numerical simulation performed within ANSYS CFX were verified on data obtained in the wind tunnel of IAP RAS by visualization methods including Particle Image Velocimetry. It was found that the airflow over the obstacle can be conditionally divided into main several regions: the region of the initiation of the detachment and formation shielding zone, the region of the maximum vertical separation and vortex development and the region of flow reattachment. Comparison of numerical calculations with the results of experiments showed that the physical processes of the airflow around model objects can be optimally modeled in a three-dimensional setting using the Detached Eddy turbulence model (DES) with central numerical differentiation scheme and allowed to select optimal parameters of calculation grid.
Flow "reflexion" and " refraction" on perforated wall
Authors: Tesař Vaclav
Published: June 2019

This article presents some results accumulated by author during investigation of an oblique impact of fluid flow on a wall consisting of a spatially periodic rods of very simple oval cross section. The flowfield in the vicinity of the impact is quite complex and strongly Reynolds -number dependent. A part of the jet downstream from the impact is “reflected” from the wall — while the rest, which passes through the empty spaces between the cascade members, leaves the other wall side in what appears to be “refraction” direction.
Investigation of droplet nucleation in CCS relevant systems: Progress in the design and testing of the mixture preparation device
Authors: Vinš Václav , Čenský Miroslav , Hrubý Jan , Hykl Jiří
Published: June 2019

The study presents progress in the development of mixture preparation device (MPD) representing an important part of the larger experimental setup intended for investigation of homogeneous droplet nucleation in CO2-rich systems. MPD allows for accurate adjustment of flow parameters, i.e. temperature, pressure, and flow rate, of CO2 in either superheated vapor or supercritical fluid phases and of other gas components such as argon or nitrogen. Through accurate settings of flow rates of individual components, the mixture composition can continuously be defined. MPD is going to be connected to the expansion chamber, where the droplet nucleation will experimentally be observed. In this work, CO2-branch, i.e. the core part of MPD, was modified and tested. Several components, e.g., pressure transducers and safety valve, had to be calibrated and adjusted to assure well-defined and safe operation. Most attention was paid to the design and performance of throttling capillary tubes installed in thermostatic bath, which define final flow parameters of CO2 coming from the CO2 branch. The flow characteristics of two capillary tubes with lengths of 7.8 and 4.0 m and inner diameter 0.1 mm were measured and compared to the predictions of a numerical model. The 1-D model of isothermal capillary flow was found to provide quite good agreement with the measured data.
Measurement and calculating of supersonic ejectors
Authors: Vojta Lukas , Dvorak Vaclav
Published: June 2019

This paper deals with numerical and experimental investigation of the flow in an air to air supersonic ejector with constant area mixing chamber. The mixing chamber of previous ejector was completely repaired since a scratch from previous turning had been found. As a result, a new geometry of the mixing chamber was created. Several measurements were conducted with different nozzle position (NP): 1 mm, 2 mm and 3 mm. Furthermore, for a given NP, two different values of stagnation pressure of 200 kPa and 300 kPa at the primary air inlet were investigated in more detail. All numerical simulations were performed in the ANSYS Fluent software. It was found that the influence of the position of the nozzle influences the ejection factor only to a certain extent. For the other parameters of the ejector is also a need to find the optimum position of the nozzle. Repair of the mixing chamber has contributed to reduce the pressure difference at the wall of the mixing chamber.
A numerical study of hemodynamic effects on the bileaflet mechanical heart valve
Authors: Zbavitel Jan , Fialová Simona
Published: June 2019

The work is focused on calculating hemodynamically negative effects of a flow through bileaflet mechanical heart valves (BMHV). Open-source FOAM-extend and cfMesh libraries were used for numerical simulation, the leaflet movement was solved as a fluid-structure interaction. A real model of the Sorin Bicarbon heart valve was employed as the default geometry for the following shape improvement. The unsteady boundary conditions correspond to physiological data of a cardiac cycle. It is shown how the modification of the shape of the original valve geometry positively affected the size of backflow areas. Based on numerical results, a significant reduction of shear stress magnitude is shown. The outcome of a direct numerical simulation (DNS) of transient flow was compared with results of low-Reynolds URANS model k-ω SST. Despite the limits of the two-dimensional solution and Newtonian fluid model, the suitability of models frequently used in literature was reviewed. Use of URANS models can suppress the formation of some relevant vortex structures which may affect the BMHV’s dynamics. The results of this analysis can find use in optimizing the design of the mechanical valve that would cause less damage to the blood cells and lower risk of thrombus formation.
Time-optimality by distance-optimality for parabolic control systems
Authors: Bonifacius Lucas , Kunisch Karl
Published: June 2019

The equivalence of time-optimal and distance-optimal control problems is shown for a class of parabolic control systems. Based on this equivalence, an approach for the efficient algorithmic solution of time-optimal control problems is investigated. Numerical examples are provided to illustrate that the approach works well in practice.
Passive manipulation of low resonance scattering frequency associated with subsonic Rayleigh waves on submerged polymer spheres
Authors: Zhou Yanling , Fan Jun , Wang Bin
Published: June 2019

Observation of the backscattering form function for a solid polymethylmeth-acrylate(PMMA) sphere reveals a significant enhancement at low frequencies, which is associated with the subsonic Rayleigh waves resonance. The presence of these resonances suggests that solid PMMA spheres may be used as passive sonar targets for certain applications.The slightly deformed PMMA spheres with regular corrugation are constructed for studying and manipulating the low-frequency resonances of subsonic Rayleigh waves. For the regular-corrugated PMMA spheres, the first-order approximate of Rayleigh normal mode solution is obtained with the perturbation method and the backscattering form function is analyzed in each order. It can be found that coupling among multiple resonance modes is introduced by the boundary deformation and leads to the shift of resonance frequency. An approximate formula for the frequency shift with respect to the parameters of corrugated boundary is deduced. Based on this formula, it is possible to evaluate resonance frequency of subsonic Rayleigh waves quickly and then manipulate acoustic scattering filed of the slightly deformed PMMA spheres in water passively.
Simulation and analysis on low-frequency scattering characteristics of the finite cylindrical shell in shallow water
Authors: Li Jinyu , Shang Dejiang , Xiao Yan
Published: June 2019

Low-frequency acoustic scatterings from a finite cylindrical shell are numerically analyzed by FEM. The simulation results show that the acoustic-scattering field in waveguide has lots of frequency-related sidelobes, while no sidelobes exist in free space at low frequencies. The simulation also indicates that the module value in waveguide can be almost 20 dB larger than that in free space at low frequency, which is caused by the ocean boundaries. We also demonstrate that when the incident wave direction is normal to the target at low frequency, the target strength will be maximum and the distribution of the acoustic-scattering field is axisymmetric about the incident waving direction. Meanwhile, the acoustic-scattering field is also related to the impedance of the seabed, and the change of the impedance makes just a little contribution to the scattering field. Finally, the influence of different target locations is analyzed, including the targets near the sea surface, seabed and the middle region of the ocean waveguide, respectively. From simulation results, it is evident that the distribution of the acoustic-scattering field at low frequency has a little difference, which is smaller than 0.5 dB with various target locations, and the change is frequency and boundary-related.
Experiment and interpretation of geomorphological detection by multi-beam sonar in Huguang-yan Maar Lake
Authors: Zhang Peizhen , Wang Bin , Fan Jun
Published: June 2019

The Huguangyan Maar Lake is caused by a volcanic eruption. The original sediments at the bottom of the lake are natural yearbooks for the evolution of the earth’s climate and environment. A multi-beam sonar technique is used to scan the full coverage on the lake surface to get fine samples of echoes form the lake bottom. The information of the bathymetric data of the lake bottom is accurately described and the results of three-dimensional geomorphology imaging are given. The results show that the lake is divided into two parts, east and west, by a north-south underwater volcanic wall, and the maximum depth of water is over 22 meters. We apply a texture feature extraction method based on multi-scale fractal dimension to describe the characteristics of the sediments and roughness. Multi-scale fractal dimensions algorithm is used to extract waveform characteristics of depth samples in different directions. General distribution of sediment at the bottom of the lake is distinguished by the width of multi-scale fractal spectrum. The results obtained can be helpful for the estimation of the physical properties of sediments.
Volume oscillation and acoustical scattering of a gas bubble
Authors: Ma Yan , Ma Tao , Zhao Feiyan
Published: June 2019

The exact solution of a gas bubble’ volume was obtained based on volume oscillation of a gas bubble. The volume pulsation, acoustic impedance, scattering pressure of a gas bubble, acoustical power of scattering and acoustical scattering cross section of a single bubble are researched in a small amplitude acoustic field. The results show that a big bubble oscillates more violently than that of a small bubble in a weak acoustic field if the linear resonance does not happen. The occurrence of a linear resonance response of a single bubble leads to the volume oscillation and the scattering ability of a gas bubble become stronger. Additionally, the scattering cross section does not depend on the driving pressure. The amplitude of scattering pressure of a big bubble can reach the magnitude compared to the driving pressure when the resonance response occurs.
Compressed sensing using a non-uniformly sampled range-azimuth dictionary
Authors: Yang Changsheng , Song Bingbing , Liang Hong , Peremans Herbert
Published: June 2019

FM-bats are known to be able to sense the environment by echolocation. In this paper, assuming the objects in the environment can be characterized by a sparse representation of the echoes in range and azimuth, a compressed sensing algorithm using a range-azimuth dictionary is proposed. The monaural and binaural range-azimuth dictionaries are constructed from measurements collected with a bionic sonar system consisting of one emitter and two receivers fitted with a 3-D printed replica of a real bats external ears. To estimate the range and azimuth of a target, the L1-minimization method is used. Since the high coherence in azimuth templates could cause ambiguity in azimuth estimation, the use of a non-uniform sampled dictionary is investigated. The non-uniform sampling is derived from the coherence between different azimuth templates in the dictionary. The non-uniformly sampled monaural and binaural dictionaries are used to process the echoes collected from a real brick-wall. Results indicate that strong echoes can be correctly localized both in azimuth and range by all three dictionaries, but for weak, highly overlapping echoes, both monaural dictionaries have problems interpreting these echo signals correctly. In addition to missing many of the real brick seams they also generate many false reconstructed objects, but constructing a binaural dictionary the results can be improved significantly.
Underwater multi-sensor Bayesian distributed detection and data fusion
Authors: Li Cheng , Zhu Guangping
Published: June 2019

The relationship of decision rule of sensor for each other is relevant to data fusion, so different topological network of sensors usually results in different performance. This paper considers the parallel and sequential topological data fusion in some detail and applies it to detect underwater signal with three sensors which respectively detects the energy, impulse width and frequency. In this paper, the signal detection model is specified for binary hypotheses testing problem. This paper compares the probabilities of error and Bayesian risk under both topologies corresponding to different value of priori probabilities of two hypotheses. Usually, the parallel architecture of detection and fusion with three sensors as specified in this paper needs to solve eleven nonlinear equations to determine the thresholds of three sensors and fusion rules, as to sequential architecture, five nonlinear equations need to be solved. So, this paper attempts to search numerical solutions for the parallel and sequential architecture of distributed detection and data fusion. Finally, this signal detection problem is simulated.
Design and research on impact resistance characteristics of vector hydrophone application platform
Authors: Zhao Tianji , Chen Hongjuan
Published: June 2019

On the basis of the analysis of the impact resistance of the application platform of the vector hydrophone is analysed , this paper designed single-stage and two-stage vibration isolation system based on rubber damper by using its characteristics of large viscous damping coefficient, low mass and easy installation and disassembly. By comparing the output signal of vector hydrophones in the state of rigid connection and with single-stage vibration isolation system, it can be seen that under different connection conditions, the signal amplitude of the impact response of the hydrophone are also different. The results of the experiment verified the effect of vibration isolation system on impact signal and the accuracy of theoretical analysis results.
Experimental and reduction leaching kinetics simulation of iron-rich manganese oxide ore using tobacco stem concrete as reducing agent
Authors: Wu Fangfang , Xiao Zhu , Zeng Bin , Chen Long , Liu Hui , Liang Min , Yu Peng , Mi Baobin
Published: June 2019

Reduction leaching behaviors of Fe and Mn from an iron-rich manganese oxide ore using waste tobacco stem concrete as reducing agent were investigated in this paper with a view to determining the feasibility of tobacco stem concrete used in reduction leaching of Mn from iron-rich manganese oxide ore. Results indicated that the leaching processes of Fe and Mn were both dominated by internal diffusion, but the effects of leaching parameters on leaching ratios of Fe and Mn were different based on established leaching kinetic equations. The leaching ratio of Mn reached up to 96.18% while that of Fe kept a lower concentration (17.66%) under optimal leaching conditions, which achieved high selectivity recovery of Mn from iron-rich manganese oxide ore. In addition, the leached solution can be used as electrolytic stock solution in the production of electrolytic manganese. Characterization of the obtained electrolytic manganese product indicated that the quality of electrolytic manganese fully met the standards of YB/T 051-2003, which disclosing a novel recycling approach of utilizing the resource coming from the tobacco industry.
Kontinuierliches Glukosemonitoring (CGM)
Authors: Kolassa Ralf , Thomas Andreas , Siegmund Thorsten
Published: June 2019

CGM liefert nicht nur Glukosekurven, die einerseits dynamische Glukoseregulation und andererseits die Komplexität des Glukosestoffwechsels zeigen, sie stellen auch Anforderungen an deren Interpretation. Dazu ist ein strukturiertes Vorgehen unabdingbar, nämlich erstens die Betrachtung der Datenqualität (richtige Kalibrierung, wenn nötig, wenige Datenlücken), zweitens die Beurteilung, ob die Kurven stark von Hypoglykämien beeinflusst sind und erst dann drittens die Beurteilung von Glukoseniveau, Glukosestabilität und Glukosemustern. Unbedingt zu beachten ist, dass die CGM-Kurven die Glukoseregulation und das Therapiemanagement der Patienten beinhalten. Unter der Sensorunterstützten Pumpentherapie (SuP) mit Systemen mit Hypoglykämieabschaltung kommt hinzu, dass bei Eingriff des Glukosesensors in die Insulinabgabe die CGM-Kurve vom Systemmanagement modifiziert wird. Auf die Herausforderungen und die Möglichkeiten der CGM-Kurveninterpretation wird nachfolgend eingegangen.
Die monetären Aspekte der Blutzuckerselbstkontrolle
Authors: Burchert Heiko , Engelmann Julius , Kannenberg Maria
Published: June 2019

Dass Blutzuckerteststreifen und Sensoren mit Geld und Kosten verbunden sind, bedarf grundsätzlich keiner Erwähnung. Die gesetzlichen Krankenversicherungen zahlten allein 2017 für die verordneten Blutzuckerteststreifen 700 Mio. Euro 1. Die Sensoren kosten die gesetzlichen Krankenversicherungen schätzungsweise 234 Mio. Euro pro Jahr. Jede einzelne der in diesem Zusammenhang ausgestellten Verordnungen (ca. 0,1 Mio.) sowie der Arbeitsaufwand der damit ver-bundenen Untersuchungen und Beratungen des Diabetikers gehen zu Lasten der Budgets der verordnenden Ärzte. Zusammengefasst können die Höhe und die Entwicklung der Kosten für die Versorgung und Betreuung von Diabetikern in Deutschland in den KoDiM-Studien 2, 3, 4 nachgelesen werden. Noch nicht berücksichtigt ist bisher die Sichtweise von „einigen“ Diabetikern. Die durch eine Verordnung erhaltenen Blutzuckerteststreifen oder Sensoren nutzen sie entgegen den Absprachen mit dem betreuenden Arzt nicht für ihr Therapie-Selbstmanagement. Vielmehr wird mit diesen Produkten durch deren Verkauf, zum Beispiel auf eBay oder anderen Online-Handelsportalen ein zum Teil beträchtliches Nebeneinkommen realisiert. Welche Dimensionen dies zwischenzeitlich erreicht hat, wer Verkäufer und Käufer sind und welche Konsequenzen sich möglicherweise für die verordnenden Ärzte ergeben, ist Gegenstand der folgenden Ausführungen.
Cholangioscopy-guided lithotripsy for difficult bile duct stone clearance in a single session of ERCP: results from a large multinational registry demonstrate high success rates
Authors: Maydeo Amit P. , Rerknimitr Rungsun , Lau James Y. , Aljebreen Abdulrahman , Niaz Saad K. , Itoi Takao , Ang Tiing Leong , Reichenberger Jörg , Seo Dong Wan , Ramchandani Mohan K. , Devereaux Benedict M. , Lee Jong Kyun , Goenka Mahesh K. , Sud Randhir , Nguyen Nam Q. , Kochhar Rakesh , Peetermans Joyce , Goswamy Pooja G. , Rousseau Matthew , Bhandari Surya Prakash , Angsuwatcharakon Phonthep , Tang Raymond S. Y. , Teoh Anthony Y. B. , Almadi Majid , Lee Yun Nah , Moon Jong Ho ,   the SpyGlass AMEA Registry Group
Published: June 2019

Background Peroral cholangioscopy (POCS) can be useful for difficult bile duct stone clearance. Large prospective multinational data on POCS-guided lithotripsy for clearing difficult bile duct stones in a single session of endoscopic retrograde cholangiopancreatography (ERCP) are missing.

Methods Patients with difficult bile duct stones (defined as one or more of: largest stone diameter ≥ 15 mm, failed prior attempt at stone clearance, impacted, multiple, hepatic duct location, or located above a stricture) were enrolled at 17 centers in 10 countries. The principal endpoint was stone clearance in a single ERCP procedure using POCS.

Results 156 patients underwent 174 sessions of POCS-guided electrohydraulic or laser lithotripsy. Stone clearance had failed in a previous ERCP using traditional techniques in 124/156 patients (80 %), while 32 /156 patients (21 %) were referred directly to POCS-guided therapy based on preprocedural assessment of the difficulty of stone clearance. In 101/156 patients (65 %), there were impacted stones. POCS-guided stone clearance was achieved in a single POCS procedure in 125 /156 patients (80 %, 95 % confidence interval [CI] 73 % – 86 %), and was significantly more likely for stones ≤ 30 mm compared with > 30 mm (odds ratio 7.9, 95 %CI 2.4 – 26.2; P = 0.002). Serious adverse events occurred in 3/156 patients (1.9 %, 95 %CI 0.4 % – 5.5 %), and included pancreatitis, perforation due to laser lithotripsy, and cholangitis (n = 1 each), all resolved within 1 week.

Conclusion POCS-guided lithotripsy is highly effective for clearance of difficult bile duct stones in a single procedure and successfully salvages most prior treatment failures. It may also be considered first-line therapy for patients with difficult choledocholithiasis to avoid serial procedures.
Thyroid Lymphoepithelial Cysts Mimicking Calcified or Solid Nodules on Ultrasonography
Authors: Tsutsuura Yukie , Hirokawa Mitsuyoshi , Suzuki Ayana , Ota Hisashi , Oshita Maki , Fukushima Mitsuhiro , Kobayashi Kaoru , Miyauchi Akira
Published: July 2019

Thyroid lymphoepithelial cysts (TLECs) are rare, and detailed ultrasonography (US) findings have not been reported. This study aimed to examine in detail the US findings for 32 TLECs and to clarify the diagnostic problems associated with them.

We examined 32 TLECs resected from 21 patients at the Kuma hospital between January 2008 and April 2018. All patients underwent US before resection. From the patients’ medical records, we retrospectively assessed US reports and photographs of TLECs.

The following four types of TLECs were classified: cystic, mixed solid and cystic, pseudo-solid, and pseudo-calcified types. The incidences were 50.0%, 12.5%, 12.5%, and 25.0%, respectively. Among the four types, pseudo-calcified TLECs were the smallest in size (mean: 7.1 mm). Of 24 nodules that had been interpreted in US reports, 11, 9, 1, 2, and 1 were benign, very low, low, intermediate, and high, respectively. Calcification and intramural solid growth were not identified by histological examination.

We should be aware that approximately half of TLECs do not exhibit US appearances typical of simple cysts, and TLECs may mimic calcified or solid nodules on US, although the reason remains unknown.
Determination of Freeway Space in Completely Edentulous Patients Using Lateral Profile Photographs—In Vivo Study
Authors: Dagdiya Monika , Pakhan Ashok , Dubey Surekha , Sathe Seema , Dagdiya Manish
Published: June 2019

Objective This study aims to determine the freeway space (FWS) using lateral profile photograph (LPP) as an adjunct in completely edentulous patients.

Materials and Methods In this study, 30 patients in the age group of 45 to 60 years who met with the criteria were included. LPPs were taken for all participants using standard protocol and a duplicate copy was obtained, on which three soft tissue reference points—porion (Stp), gnathion (Stgn), and gonion (Stg)—were marked and joined to form an angle Stp-Stg-Stgn. This angle was correlated with the mean FWS obtained using swallowing. Simple linear regression model was used to develop a prediction formula for FWS using Stp-Stg-Stgn angle as the independent variable.

Result This study shows that the angle Stp-Stg-Stgn had a significant negative correlation with FWS.
Correlation of Optical Coherence Tomographic Findings with Clinical Features in High Myopia
Authors: Rao Evangeline , Mishra Maithili , Kerkar Sheela , Ahuja Arjun
Published: June 2019

This is a cross-sectional observational study to correlate relationship between macular and retinal nerve fiber layer (RNFL) thickness in relation to clinical features in high myopia. A total of 100 eyes of 50 consecutive patients underwent optical coherence tomography (OCT) of the macula and RNFL. It was observed that correlation of RNFL thickness to the axial length is better than that of RNFL thickness to the spherical equivalent. The macular thickness in the parafoveal region was observed to be thicker than the perifoveal region in all quadrants. This study therefore emphasizes the need to have macular thickness nomogram for high myopes to avoid misinterpretation of OCT results due to axial length and refractive error and, also, the need for a routine baseline OCT scan for all high myopia patients.
Synthesis and Transformation of 5-Acetyl-2-aryl-6-hydroxybenzofurans into Furanoflavanone Derivatives
Authors: Mphahlele Malose J. , Olomola Temitope O.
Published: June 2019

Tandem palladium-catalyzed Sonogashira cross-coupling and heteroannulation of 3-bromo-2,4-dihydroxy-5-iodoacetophenone with arylacetylenes followed by the base-mediated Claisen–Schmidt aldol condensation of the intermediate 5-acetyl-2-aryl-7-bromo-6-hydroxybenzofurans with benzaldehyde derivatives afforded the corresponding linear 2-arylbenzofuranchalcone hybrids. The presence of the o-hydroxy-trans-α,β-unsaturated carbonyl moiety in the prepared furanochalcone hybrids facilitated acid-mediated cycloisomerization into the corresponding linear furanoflavanones. The structures of the prepared compounds were confirmed using a combination of spectrometric techniques complemented with single crystal XRD analysis.
Organoselenium-Catalyzed Aza-Wacker Reactions: Efficient Access to Isoquinolinium Imides and an Isoquinoline N-Oxide
Authors: Li Huimin , Liao Lihao , Zhao Xiaodan
Published: June 2019

An efficient approach for the organoselenium-catalyzed aza-Wacker reaction of olefinic hydrazones and an oxime to form isoquinolinium imides and an isoquinoline N-oxide is developed. This transformation involves a direct intramolecular C–H amination using hydrazones and an oxime as imine-type nitrogen sources. This work not only provides a new approach for the construction of isoquinoline derivatives, but also expands the scope of nitrogen sources in electrophilic selenium catalysis.
Scalable Synthesis of a Chiral Selenium π-Acid Catalyst and Its Use in Enantioselective Iminolactonization of β,γ-Unsaturated Amides
Authors: Otsuka Yuta , Shimazaki Yuto , Nagaoka Hitoshi , Maruoka Keiji , Hashimoto Takuya
Published: June 2019

Chiral selenium π-acid catalysis has for a long time been lagging behind other areas of asymmetric catalysis due to a lack of highly enantioselective catalysts. In this regard, we recently developed the first chiral selenium π-acid catalyst which performs the oxidative cyclization of β,γ-unsaturated carboxylic acids with high enantioselectivities. We report herein our improved synthesis of this chiral selenium catalyst, which allows access to a large quantity of the catalyst as the diselenide. In addition, the catalyst is tested in the oxidative cyclization of N-methoxy β,γ-unsaturated amides to give iminolactones with high enantioselectivities.
Effect on Insulin upon Storage in Extreme Climatic Conditions (Temperature and Pressure) and Their Preventive Measures
Authors: Khurana Girish , Gupta Vipul
Published: June 2019

Insulin is a naturally occurring hormone secreted by the pancreas. Insulin is required by the body cellsto remove and use glucose from the blood. The insulin and its various analogues are essential in management of type 1 diabetes mellitus. This study has been done to analyze how variation in various storage conditions and climatic changes causes change in therapeutic efficacy. Storage condition affects the stability of insulin as observed in a study in which insulin stored at temperature between 32 and 37°C showed 14 to 18% decrease in its potency and could not cause a significant decrease in blood sugar level when compared with those receiving insulin stored at 5°C. This work was done with the aim of finding the effect of climatic changes and storage condition on efficacy of insulin.
Clinical Profile and Management Techniques of Surgical Obstructive Jaundice Cases in a Tertiary Center at Bareilly
Authors: Singh Shailendra Kumar , Choudhary Porus , Yadav Ruby
Published: June 2019

Introduction Obstructive jaundice is associated with high morbidity and mortality. Obstructive jaundice is not a definitive diagnosis. Detailed evaluation to establish the etiology of the cholestasis and cause of obstruction is crucial to avoid secondary pathologic changes and to plan different surgical techniques to intervene at an early stage.

Materials and Methods A cross-sectional study was conducted among 50 cases of surgical obstructive jaundice at Shri Ram Murti Smarak Institute of Medical Sciences (SRMSIMS), Bareilly.

Results The mean age of this study population was 48.44 ± 8.2 years, and 48% (24) patients had obstructive jaundice of benign etiology, whereas 52% (26) had malignant etiology. Among males, the common presentation was choledocholithiasis in benign disease and carcinoma of the gallbladder among malignancy. In females also, disease presentation was similar to that of males. Percutaneous transhepatic biliary drainage (PTBD) was the most common method of biliary decompression in malignant group. For biliary decompression in patients of benign etiology, common bile duct (CBD) exploration with T-tube drainage was done in most cases.

Conclusion Obstructive jaundice has different etiologic spectrum in both males and females. Irrespective of etiology, common presentation was pain (94% of the cases). Most patients with malignant etiology presented with palpable lump. PTBD was the most common method of biliary decompression in malignant group. CBD exploration with T-tube drainage has higher values of decrease in serum bilirubin, serum bilirubin (indirect), serum alkaline phosphatase, and albumin.
The Percutaneous Endoscopic Lumbar Interbody Fusion (PELIF): An Advanced and Innovation Technique
Authors: de Alcantara Tabata , Nogueira Monica Paschoal , Silva Anibal Correia
Published: June 2019

The degenerative spine changes, and its costs, have increased with high rates of work absenteeism and difficult clinical management. The search for minimally invasive treatments, with better results and early patients recover, with rapid hospital discharge are alternatives for these problems. The percutaneous endoscopic lumbar interbody fusion (PELIF) is a new and advanced option.
Merging parallel-plate and levitation actuators to enable linearity and tunability in electrostatic MEMS
Authors: Pallay Mark , Miles Ronald N. , Towfighian Shahrzad
Published: July 2019

In this study, a linear electrostatic MEMS actuator is introduced. The system consists of a MEMS cantilever beam with combined parallel-plate and electrostatic levitation forces. By using these two forcing methods simultaneously, the static response and natural frequency can be made to vary linearly with the voltage. The static response shows a linear increase of 90 nm/V and is maintained for more than 12μm of the tip displacement. The natural frequency shows a linear increase of 16 Hz/V and is maintained throughout a 2.9 kHz shift in the natural frequency. This wide range of linear displacement and frequency tunability is extremely useful for MEMS sensors and actuators, which suffer from the inherent nonlinearity of electrostatic forces. A theoretical model of the system is derived and validated with experimental data. Static response, natural frequency, and frequency response calculations are performed. Merging these two mechanisms enables high oscillation branches for a wide range of frequencies with potential applications in MEMS filters, oscillators, and sensors.
Anisotropic etching of β-Ga2O3 using hot phosphoric acid
Authors: Zhang Yuewei , Mauze Akhil , Speck James S.
Published: July 2019

We report a systematic investigation on the anisotropic etching behavior of β-Ga2O3. A wagon wheel pattern was designed and fabricated on (010)-oriented β-Ga2O3 substrates. The wet etching in hot phosphoric acid was found to be effective in reducing the sidewall roughness caused by plasma dry etching. The angular dependence of the sidewall etch rate and inclination angles after wet etching was evaluated. The fins aligned along the [001] direction showed nearly vertical sidewalls after wet etching and a fast sidewall etch rate, making it feasible for the fabrication of ultrascaled vertical channel devices. The fins aligned in the angular range between the [203] and [201] directions showed slanted sidewalls with high tilt angles, which could be useful in reducing the peak electric field near the corners of high power devices. The observed anisotropic etching in this work offers a low-cost, low damage, and controllable fabrication method for ultrascaled and advanced device structures.
MFM and first order reversal curve (FORC) study of switching mechanism in Co25Pd75 films
Authors: Abugri Joseph B. , Clark Billy D. , Visscher P. B. , Gong Jie , Gupta Subhadra
Published: July 2019

Recent research on CoPd alloys with perpendicular magnetic anisotropy has suggested that they might be useful as the pinning layer in CoFeB/MgO-based perpendicular magnetic tunnel junctions for various spintronic applications such as spin-torque transfer random access memory. We have previously studied the effect of seed layer and composition on the structure (by XRD, SEM, AFM, and TEM) and the performance (coercivity) of these CoPd films. These films do not switch coherently, so the coercivity is determined by the details of the switching mechanism, which was not studied in our previous paper. In the present paper, we show that information can be obtained about the switching mechanism from magnetic force microscopy (MFM) together with first order reversal curves, despite the fact that MFM can only be used at the zero field. We find that these films switch by a mechanism of domain nucleation and dendritic growth into a labyrinthine structure, after which the unreversed domains gradually shrink to small dots and then disappear.
Gardner physics in amorphous solids and beyond
Authors: Berthier Ludovic , Biroli Giulio , Charbonneau Patrick , Corwin Eric I. , Franz Silvio , Zamponi Francesco
Published: July 2019

One of the most remarkable predictions to emerge out of the exact infinite-dimensional solution of the glass problem is the Gardner transition. Although this transition was first theoretically proposed a generation ago for certain mean-field spin glass models, its materials relevance was only realized when a systematic effort to relate glass formation and jamming was undertaken. A number of nontrivial physical signatures associated with the Gardner transition have since been considered in various areas, from models of structural glasses to constraint satisfaction problems. This perspective surveys these recent advances and discusses the novel research opportunities that arise from them.