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Hintergrund: Die Pulmonalvenenisolation (PVI) mit Hilfe von Kryoballonkathetern ist eine anerkannte Methode zur Behandlung von Vorhofflimmern (AF). Diese Methode bietet eine kürzere Behandlungsdauer als die klassische Therapie durch die Hochfrequenzablation (HF). Ziel dieser Studie war es, verschiedene Kryoballonkatheter, HF-Katheter und Ösophaguskatheter in ein Herzrhythmusmodell zu integrieren und mittels statischer und dynamischer Simulation elektrische und thermische Felder bei PVI unter Vorhofflimmern zu untersuchen.
Methodik: Die Modellierung und Simulation erfolgte mit der elektromagnetischen und thermischen Simulationssoftware CST (CST Darmstadt). Zwei Kryoballons, ein HF-Ablationskatheter und ein Ösophaguskatheter wurden auf der Grundlage der technischen Handbücher der Hersteller Medtronic und Osypka modelliert. Der 23 mm Kryoballon und ein kreisförmiger Mappingkatheter wurden in das Offenburger Herzrhythmusmodell integriert, insbesondere die left inferior pulmonary vein (LIPV) zur Simulation der thermischen Feldausbreitung während einer PVI. Die Simulation einer PVI mit HF-Energie wurde mit dem integrierten HF-Ablationskatheter in der Nähe der LIPV durchgeführt. Der im Herzrhythmusmodell platzierte TO8 Ösophaguskatheter ermöglichte die Ableitung linksatrialer elektrischer Felder bei AF und die Analyse thermischer Felder während PVI.
Ergebnisse: Elektrische Felder konnten bei Sinusrhythmus und AF mit einem AF-Fokus in der LIVP statisch und dynamisch im Herzen und Ösophagus simuliert werden. Bei einer simulierten 20 Sekunden Applikation eines Kryoballon-Katheters bei -50°C wurde eine Temperatur von -24°C in einer Tiefe von 0,5 mm im Myokard gemessen. In einer Tiefe von 1 mm betrug die Temperatur -3°C, bei 2 mm Tiefe 18°C und bei 3 mm Tiefe 29°C. Unter der 15 sekündigen Anwendung eines HF-Katheters mit einer 8-mm-Elektrode und einer Leistung von 5 W bei 420 kHz betrug die Temperatur an der Spitze der Elektrode 110°C. In einer Tiefe von 0,5 mm im Myokard betrug die Temperatur 75°C, in einer Tiefe von 1 mm 58°C, in einer Tiefe von 2 mm 45°C und in einer Tiefe von 3 mm 38°C. Im Ösophagus konnte bei den meisten Simulationen eine konstante Temperatur von 37°C gemessen und die Gefahr einer Ösophagus-Fistel ausgeschlossen werden. Bei Kryoablation der LIPV wurde eine Abkühlung des Ösophagus auf 30°C gemessen.
Schlussfolgerungen: Die Herzrhythmussimulation elektrischer und thermaler Felder ermöglichen mit Anwendung unterschiedlicher Herzkatheter eine statische und dynamische Simulation von PVI durch Kryoablation, HF-Ablation und Temperaturanalyse im Ösophagus. Unter Einbeziehung von MRT- oder CT-Daten können elektrische und thermale Simulationen möglicherweise zur Optimierung von PVIs genutzt werden.
The invention relates to an oesophageal electrode probe (10) for bioimpedance measurement and/or for neurostimulation; a device (100) for transoesophageal cardiological treatment and/or cardiological diagnosis; and a method for the open-loop or closed-loop control of a cardiac catheter ablation device and/or a cardiac, circulatory and/or respiratory support device. The oesophageal electrode probe comprises a bioimpedance measuring device for measuring the bioimpedance of at least one part of the tissue surrounding the oesophageal electrode probe. The bioimpedance device comprises at least one first and one second electrode, wherein the at least one first electrode (12A) is arranged on a side (14) of the oesophageal electrode probe facing towards the heart and the at least one second electrode (12B) is arranged on a side (16) of the oesophageal electrode probe facing away from the heart. The device (100) comprises the oesophageal electrode probe (10) and a control and/or evaluation device (30), which is configured for receiving a first bioimpedance measurement signal from the at least one first electrode (12A) and a second bioimpedance measurement signal from the at least one second electrode (12B), and comparing same, and generating a control signal on the basis of the comparison. The control signal can be a signal for the open-loop or closed-loop control of a cardiac catheter ablation device and/or a cardiac, circulatory and/or respiratory support device.
In den letzten Jahren sind die strategischen Ausrichtungen in der Versicherungsbranche verstärkt durch marketingorientierte Managemententscheidungen geprägt. Ein solches Marketing-Broadening bedeutet die Ausrichtung aller Unternehmensbereiche auf den Markt, und hier vornehmlich auf den Kunden. Schon lange sieht sich dabei nicht nur die deutsche, sondern auch die europäische Versicherungsbranche den Herausforderungen eines weitgehend liberalisierten Marktes gegenüber. Begleitend hat sich das Kundenverhalten, etwa im Hinblick auf die Informationsbeschaffung oder das Kommunikationsverhalten, ganz grundlegend verändert.Aktuell entwickelt sich die Digitalisierung rasant als komplexe und zu der in der Zukunft wahrscheinlich schwerwiegendsten Herausforderung für die Versicherungsbranche. Da einer Digitalisierung die grundlegende Anpassung sämtlicher Geschäftsprozesse eines Versicherungsunternehmens durch eine Änderung aller diesbezüglicher betrieblichen Komponenten, deren Schnittstellen zum Kunden und deren Produkte oder Dienstleistungen folgt, gilt es komplexe Veränderungen zu steuern.
Dem Anliegen einen aktuell fokussierten Blick auf die wesentlichen Herausforderungen dieses Veränderungsprozesses einer ganzen Branche zu werfen, fühlen sich die Herausgeber und Verfasser des Handbuches Versicherungsmarketing verpflichtet. Das bewährte Konzept der ersten, auf äußerst positive Resonanz gestoßenen Auflage, beibehaltend, zeichnet diese nun vorliegende zweite Auflage vor allem die Managementrelevanz ihrer zahlreichen, neu hinzugekommenen und hoch aktuellen Beiträge aus.
In den letzten Jahrzehnten haben permanentmagneterregte Synchronmaschinen und deren Regelung immer mehr Einzug in industrielle Applikationen erhalten. Durch die weltweit wachsende Elektromobilität partizipiert das Automobil an deren fortschreitenden Einsatzmöglichkeit.
Die Modellierung eines physikalisch-technischen Systems ist ein wichtiger Bestandteil in der Entwicklung einer Regelung. Inhaltlich setzt sich die Abschlussarbeit mit dieser Vorgehensweise für eine 6-phasige permanentmagneterregte Synchronmaschine auseinander. Durch die doppelte Anzahl an Statorwicklungen existieren unter anderem zwei verschiedene Wicklungskonzepte, wie eine elektrische Maschine aufgebaut sein könnte. Beide Wicklungskonzepte, bei dem entweder eine volle magnetische Kopplung oder keine magnetische Kopplung der betrachteten Teilsysteme vorliegt, werden untersucht. Ziel der Masterthesis ist es, eine mathematische Grundlage für die Modellbildung einer 6-phasigen permanentmagneterregten Synchronmaschine herzuleiten, um darauf aufbauend eine feldorientierte Regelung zu entwerfen. Wie in der industriellen Antriebstechnik gebräuchlich, erfolgt die Regelung in einem rotierenden Koordinatensystem. Die Stromregelung basiert auf einen zeitkontinuierlichen PI-Regler samt Spannungsbegrenzung und einer Anti-Windup-Struktur. In der Ausarbeitung wird mithilfe zweier Simulationsmodelle bewiesen, dass sowohl das mathematische Modell einer 6-phasigen permanentmagneterregten Synchronmaschine als auch deren Regelung simulationstechnisch die erwarteten Resultate liefern.
Message co chairmen
(2017)
The visualization of heart rhythm disturbance and atrial fibrillation therapy allows the optimization of new cardiac catheter ablations. With the simulation software CST (Computer Simulation Technology, Darmstadt) electromagnetic and thermal simulations can be carried out to analyze and optimize different heart rhythm disturbance and cardiac catheters for pulmonary vein isolation. Another form of visualization is provided by haptic, three-dimensional print models. These models can be produced using an additive manufacturing method, such as a 3d printer. The aim of the study was to produce a 3d print of the Offenburg heart rhythm model with a representation of an atrial fibrillation ablation procedure to improve the visualization of simulation of cardiac catheter ablation. The basis of 3d printing was the Offenburg heart rhythm model and the associated simulation of cryoablation of the pulmonary vein. The thermal simulation shows the pulmonary vein isolation of the left inferior pulmonary vein with the cryoballoon catheter Arctic Front Advance™ from Medtronic. After running through the simulation, the thermal propagation during the procedure was shown in the form of different colors. The three-dimensional print models were constructed on the base of the described simulation in a CAD program. Four different 3d printers are available for this purpose in a rapid prototyping laboratory at the University of Applied Science Offenburg. Two different printing processes were used and a final print model with additional representation of the esophagus and internal esophagus catheter was also prepared for printing. With the help of the thermal simulation results and the subsequent evaluation, it was possible to draw a conclusion about the propagation of the cold emanating from the catheter in the myocardium and the surrounding tissue. It was measured that just 3 mm from the balloon surface into the myocardium the temperature dropped to 25 °C. The simulation model was printed using two 3d printing methods. Both methods, as well as the different printing materials offer different advantages and disadvantages. All relevant parts, especially the balloon catheter and the conduction, are realistically represented. Only the thermal propagation in the form of different colors is not shown on this model. Three-dimensional heart rhythm models as well as virtual simulations allow very clear visualization of complex cardiac rhythm therapy and atrial fibrillation treatment methods. The printed models can be used for optimization and demonstration of cryoballoon catheter ablation in patients with atrial fibrillation.
Spinal cord stimulation (SCS) is the most commonly used technique of neurostimulation. It involves the stimulation of the spinal cord and is therefore used to treat chronic pain. The existing esophageal catheters are used for temperature monitoring during an electrophysiology study with ablation and transesophageal echocardiography. The aim of the study was to model the spine and new esophageal electrodes for the transesophageal electrical pacing of the spinal cord, and to integrate them in the Offenburg heart rhythm model for the static and dynamic simulation of transesophageal neurostimulation. The modeling and simulation were both performed with the electromagnetic and thermal simulation software CST (Computer Simulation Technology, Darmstadt). Two new esophageal catheters were modelled as well as a thoracic spine based on the dimensions of a human skeleton. The simulation of directed transesophageal neurostimulation is performed using the esophageal balloon catheter with an electric pacing potential of 5 V and a trapezoidal signal. A potential of 4.33 V can be measured directly at the electrode, 3.71 V in the myocardium at a depth of 2 mm, 2.68 V in the thoracic vertebra at a depth of 10 mm, 2.1 V in the thoracic vertebra at a depth of 50 mm and 2.09 V in the spinal cord at a depth of 70 mm. The relation between the voltage delivered to the electrodes and the voltage applied to the spinal cord is linear. Virtual heart rhythm and catheter models as well as the simulation of electrical pacing fields and electrical sensing fields allow the static and dynamic simulation of directed transesophageal electrical pacing of the spinal cord. The 3D simulation of the electrical sensing and pacing fields may be used to optimize transesophageal neurostimulation.
In this study, a high-performance controller is proposed for single-phase grid-tied energy storage systems (ESSs). To control power factor and current harmonics and manage time-shifting of energy, the ESS is required to have low steady-state error and fast transient response. It is well known that fast controllers often lack the required steady-state accuracy and trade-off is inevitable. A hybrid control system is therefore presented that combines a simple yet fast proportional derivative controller with a repetitive controller which is a type of learning controller with small steady-state error, suitable for applications with periodic grid current harmonic waveforms. This results in an improved system with distortion-free, high power factor grid current. The proposed controller model is developed and design parameters are presented. The stability analysis for the proposed system is provided and the theoretical analysis is verified through stability, transient and steady-state simulations.
Exploiting Dissent: Towards Fuzzing-based Differential Black Box Testing of TLS Implementations
(2017)
The Transport Layer Security (TLS) protocol is one of the most widely used security protocols on the internet. Yet do implementations of TLS keep on suffering from bugs and security vulnerabilities. In large part is this due to the protocol's complexity which makes implementing and testing TLS notoriously difficult. In this paper, we present our work on using differential testing as effective means to detect issues in black-box implementations of the TLS handshake protocol. We introduce a novel fuzzing algorithm for generating large and diverse corpuses of mostly-valid TLS handshake messages. Stimulating TLS servers when expecting a ClientHello message, we find messages generated with our algorithm to induce more response discrepancies and to achieve a higher code coverage than those generated with American Fuzzy Lop, TLS-Attacker, or NEZHA. In particular, we apply our approach to OpenssL, BoringSSL, WolfSSL, mbedTLS, and MatrixSSL, and find several real implementation bugs; among them a serious vulnerability in MatrixSSL 3.8.4. Besides do our findings point to imprecision in the TLS specification. We see our approach as present in this paper as the first step towards fully interactive differential testing of black-box TLS protocol implementations. Our software tools are publicly available as open source projects.
Proton Exchange Membrane Fuel Cell (PEMFC) is one of the most promising technologies for sustainable energy production due to the high power density, low operative temperature and more convenient use for several applications. Nevertheless, the high generated current that characterizes PEMFC requires a specific power conditioning. In addition, specific controller must be designed to fit with system operative points changing associated with the variation of this high current. To deal with this challenge, in this paper, an electrochemical system composed of a Proton Exchange Membrane Fuel Cell (PEMFC) feeding via two phases IBC has been proposed and investigated. For robustness, the used IBC for fuel cell voltage regulation is controlled by linear quadratic regulator (LQR). Then, genetic algorithms technique is applied to optimize the LQR controller parameters giving optimal control coefficients and can if necessary be adjusted according to each working situation change. The model of the entire system is studied using Matlab/Simulink environment. The simulation’s comparative standard and robustness results both demonstrate that the proposed GA-based LQR controller outperforms the conventional PI in terms of performance metrics (overshoot reduction: between 58.93% and 97.09%; response time reduction: between 56.40% and 77.00% and ripple reduction: between 84.00% and 94.86%).
Energy and environment continue to be major issues of human mankind. This holds true on the regional, the national, and the global level. And it is one of the problems, where engineers and scientists in conjunction with political will and people's awareness, can find new approaches and solutions to save the natural resources and to make their use more efficient.
Instabilities of the interface between two thin liquid films under DC electroosmotic flow are investigated using linear stability analysis followed by an asymptotic analysis in the long-wave limit. The two-liquid system is bounded by two rigid plates which act as substrates. The Boltzmann charge distribution is considered for the two electrolyte solutions and gives rise to a potential distribution in these liquids. The effect of van der Waals interactions in these thin films is incorporated in the momentum equations through the disjoining pressure. Marginal stability and growth rate curves are plotted in order to identify the thresholds for the control parameters when instabilities set in. If the upper liquid is a dielectric, the applied electric field can have stabilizing or destabilizing effects depending on the viscosity ratio due to the competition between viscous and electric forces. For viscosity ratio equal to unity, the stability of the system gets disconnected from the electric parameters like interface zeta potential and electric double-layer thickness. As expected, disjoining pressure has a destabilizing effect, and capillary forces have stabilizing effect. The overall stability trend depends on the complex contest between all the above-mentioned parameters. The present study can be used to tune these parameters according to the stability requirement.
DEM–FEA estimation of pores arrangement effect on the compressive Young’s modulus for Mg foams
(2015)
This work reports the study of the effect of the pore arrangement on the compressive behavior of Mg foams with regular pore size and porosities ranging from 25% to 45%. Pore arrangements were modeled using Finite Element Analysis (FEA), with random and ordered models, and compared to the estimations obtained for a previous work. The coordinates of the random pore arrangements were firstly generated using Discrete Element Method (DEM), and used in a second stage for modeling the pores by FEA. Estimations were also compared to the experimental results for Mg foams obtained by means of powder metallurgy. Results show important drops in the Young’s moduli as the porosity increases for both, experimental results and FEA estimations. Estimations obtained using ordered pore arrangements presented significant differences when compared to the estimations acquired from models with random arrangements. The randomly arranged models represent more accurately the real topologies of the experimental metallic foams. The Young’s moduli estimated using these models were in excellent agreement with the experiments, whilst the estimations obtained using ordered models presented relative errors significantly higher. The importance of the use of more realistic FEA models for improving the predicting ability of this method was probed, for the study of the mechanical properties of metallic foams.
The automatic classification of the modulation format of a detected signal is the intermediate step between signal detection and demodulation. If neither the transmitted data nor other signal parameters such as the frequency offset, phase offset and timing information are known, then automatic modulation classification (AMC) is a challenging task in radio monitoring systems. The approach of clustering algorithms is a new trend in AMC for digital modulations. A novel algorithm called `highest constellation pattern matching' is introduced to identify quadrature amplitude modulation and phase shift keying signals. The obtained simulation and measurement results outperform the existing algorithms for AMC based on clustering. Finally, it is shown that the proposed algorithm works in a real monitoring environment.
Neuroprosthetics 2.0
(2019)
For e-commerce retailers it is crucial to present their products both informatively and attractively. Virtual reality (VR) systems represent a new marketing tool that supports customers in their decision-making process and offers an extraordinary product experience. Despite these advantages, the use of this technology for e-commerce retailers is also associated with risks, namely cybersickness. The aim of the study is to investigate the occurrence of cybersickness in the context of the customer’s perceived enjoyment and the perceived challenge of a VR product presentation. Based on a conceptual research framework, a laboratory study with 533 participants was conducted to determine the influence of these factors on the occurrence of cybersickness. The results demonstrate that the perceived challenge has a substantially stronger impact on the occurrence of cybersickness, which can only be partially reduced by perceived enjoyment. When realizing VR applications in general and VR product presentations in particular, e-commerce retailers should therefore first minimize possible challenges instead of focusing primarily on entertainment aspects of such applications.
Purpose
The purpose of this study is to investigate the effects of telepresence while using a smartphone-based virtual reality system (SBVR) to explore a hotel virtually and to determine the influence of this immersive experience on the booking intention of the potential customer.
Design/methodology/approach
Within the scope of this study, a conceptual research model was developed which covered utilitarian and hedonic aspects of the user experience of SBVRs and showed their relevance for the booking intention. A virtual reality application was programmed especially for the study, in which the test persons were able to virtually explore a hotel complex. A total of 569 people participated in the study. A questionnaire was used for the data collection. The structural equation modelling and hypothesis verification were carried out using the partial least squares method.
Findings
The immersive feeling of telepresence increases the perceived enjoyment and usefulness of the potential customer. In addition, the user's curiosity is aroused by the telepresence, which also significantly increases the perceived enjoyment as well as the perceived usefulness. The hedonic and utilitarian value of the virtual hotel experience increases the probability that the customer will book the travel accommodation.
Research limitations/implications
The virtual reality application developed for the study is based on static panoramic images and does not contain audio-visual elements (e.g. sound, video, animation). Audio-visual elements might increase the degree of immersion and could therefore be investigated in future research.
Practical implications
The results of the study show that the SBVR is a suitable marketing tool to present hotels in an informative and entertaining way, and can thereby increase sales and profits.
Originality/value
For the first time, this study investigates the potential of SBVRs for the virtual product presentation of hotels and provides empirical evidence that the availability of this innovative form of presentation leads to a higher booking intention.
The instability of ultra-thin films of an electrolyte bordering a dielectric gas in an external tangential electric field is scrutinized. The solid wall is assumed to be either a conducting or charged dielectric surface. The problem has a steady one-dimensional solution. The theoretical results for a plug-like velocity profile are successfully compared with available experimental data. The linear stability of the steady-state flow is investigated analytically and numerically. Asymptotic long-wave expansion has a triple-zero singularity for a dielectric wall and a quadruple-zero singularity for a conducting wall, and four (for a conducting wall) or three (for a charged dielectric wall) different eigenfunctions. For infinitely small wave numbers, these eigenfunctions have a clear physical meaning: perturbations of the film thickness, of the surface charge, of the bulk conductivity, and of the bulk charge. The numerical analysis provides an important result: the appearance of a strong short-wave instability. At increasing Debye numbers, the short-wave instability region becomes isolated and eventually disappears. For infinitely large Weber numbers, the long-wave instability disappears, while the short-wave instability persists. The linear stability analysis is complemented by a nonlinear direct numerical simulation. The perturbations evolve into coherent structures; for a relatively small external electric field, these are large-amplitude surface solitary pulses, while for a sufficiently strong electric field, these are short-wave inner coherent structures, which do not disturb the surface.
The formation and analysis of ten microporous triazolyl isophthalate based MOFs, including nine isomorphous and one isostructural compound is presented. The compounds 1 M – 3 M with the general formula [ M ( R 1 - R 2 - trz - ia ) ] ∞ 3 ·x H 2 O (M 2+ = Co 2+ , Cu 2+ , Zn 2+ , Cd 2+ ; R 1 = H, Me; R 2 = 2py, 2pym, prz (2py = 2-pyridinyle; 2pym = 2-pyrimidinyle; prz = pyrazinyle)) crystallize with rtl topology. They are available as single crystals and also easily accessible in a multi-gram scale via refluxing the metal salts and the protonated ligands in a solvent. Their isomorphous structures facilitate the synthesis of heteronuclear MOFs; in case of 2 M , Co 2+ ions could be gradually substituted by Cu 2+ ions. The Co 2+ :Cu 2+ ratios were determined by ICP-OES spectroscopy, the distribution of Co 2+ and Cu 2+ in the crystalline samples are investigated by SEM-EDX analysis leading to the conclusions that Cu 2+ is more favorably incorporated into the framework compared to Co 2+ and, moreover, that the distribution of the two metal ions between the crystals and within the crystals is inhomogeneous if the crystals were grown slowly. The various compositions of the heteronuclear materials lead to different colors and the sorption properties for CO 2 and N 2 are dependent on the integrated metal ions.
A wide range catalyst screening with noble metal and oxide catalysts for a metal–air battery with an aqueous alkaline electrolyte was carried out. Suitable catalysts reduce overpotentials during the charge and discharge process, and therefore improve the round-trip efficiency of the battery. In this case, the electrodes will be used as optimized cathodes for a future lithium–air battery with an aqueous alkaline electrolyte. Oxide catalysts were synthesized via atmospheric plasma spraying. The screening showed that IrO2, RuO2, La0.6Ca0.4Co3, Mn3O4, and Co3O4 are promising bi-functional catalysts. Considering the high price for the noble metal catalysts further investigations of the oxide catalysts were carried out to analyze their electrochemical behavior at varied temperatures, molarities, and in case of La1−x Ca x CoO3 a varying calcium content. Additionally all catalysts were tested in a longterm test to proof cyclability at varied molarities. Further investigations showed that Co3O4 seems to be the most promising bi-functional catalyst of the tested oxide catalysts. Furthermore, it was shown that a calcium content of x = 0.4 in LCCO has the best performance.
We tested the MOF framework Cu-BTC for natural gas (NG) storage. Adsorption isotherms of C1–C4 alkanes were simulated applying the Grand Canonical ensemble and the Monte Carlo algorithm in a classical molecular mechanics approach. Experimental monocomponent isotherm of the alkanes was used to validate the force field. We performed multicomponent adsorptions calculations for three different quaternary mixtures of C1–C4 alkanes, matching typical NG streams composition, and predicted theoretical storage capacities, efficiency and accumulation of the NG within that composition. Despite being one of the frameworks with greatest storage capacity of methane, we found that Cu-BTC presented great sensitivity to the variation of the heavier alkanes in NG composition. When we increase the percentage of butane from 0.1% to 0.7% in the mixture, the mass of components retained in the discharge pressure (1 bar) increases from 35 to 60%. We also perform siting and interaction energy investigations and compare the NG storage performance of the Cu-BTC with that of activated carbons. To our knowledge, this is the first study regarding the efficiency of the NG storage in Cu-BTC.
Stadtmarketing
(2019)
Stadtmarketing ist das Aufgabenfeld verschiedener Disziplinen und Berufsgruppen. Neben Marketingfachleuten aus Wissenschaft, Beratung und Praxis beschäftigt es auch Verwaltungsexperten oder Praktiker aus Handel und Gastronomie. Voraussetzung und Basis für erfolgreiche Marketingstrategien ist daher eine interdisziplinäre, konstruktive und flexible Zusammenarbeit aller Beteiligten.
Dieses Buch gibt einen Überblick über die Grundlagen des Stadtmarketing und liefert Ansatzpunkte für die Weiterentwicklung von Städten, Kommunen und Regionen. Es beleuchtet die wichtigen Aspekte Transformation, Mobilität und Infrastruktur und bietet gezielte Anregungen für die Marketingpraxis. Zudem werden Beispiele erfolgreicher praktischer Umsetzungen aufgezeigt, wie etwa in Freiburg, Frankfurt, Neumünster, Offenburg, Jena, Mainz oder Leipzig.
Über 40 renommierte Branchenexperten beschreiben, was die Branche bewegt und was es in Zukunft zu beachten gilt. Das Werk bietet Neulingen und Quereinsteigern aus anderen Fachgebieten sowie Studierenden großen Nutzwert. Außerdem enthält es wegweisende Anregungen für erfahrene Praktiker, die die Kommunikation und Kooperation mit Stakeholdern aus unterschiedlichen Fachdisziplinen verbessern möchten und zugleich nach Impulsen für die eigene Arbeit suchen.
Die vorliegende Master-Thesis befasst sich mit dem Thema Handel. In der Arbeit wird der Bereich des Multi-Channel-Handels genauer durchleuchtet. Es wird aufgezeigt, wie der Zukunft des Handels weltweit und in Deutschland aussehen wird.
Der Handel wird besonders heute sehr vom Konsumierendenverhalten beeinflusst. Unternehmen passen sich mehr als je zuvor an Wünsche und Anforderungen der Zielgruppe an. Dies ist wichtig für Handelsunternehmen um wettbewerbsfähig und profitabel zu bleiben, vor allem in einem immer aggressiver werdenden Wettbewerbskampf um Konsumierende. In dieser Arbeit wird dargestellt, wie sich die Customer Journey und der Kaufprozess der Konsumierenden verändert hat und flexibler geworden ist. Es gibt nicht mehr nur einen Weg, wie potentielle Verkaufsinteressierende zu Kundschaft wird. Die Kundschaft lässt sich nicht mehr von Unternehmen leiten, sondern möchte eigenständig und selbstbestimmt zwischen verschiedenen Absatzkanälen und Endgeräten wechseln. Daher ist ein verknüpftes Multi-Channel-System für Handelsunternehmen wichtig. In dieser Arbeit soll zudem gezeigt werden, dass die Omni-Channel-Strategie die Strategie der Zukunft ist und wie der Begriff des New Retail sowohl den Online-Handel, als auch den stationären Handel prägen wird.
Online-Handelsunternehmen wie Amazon, Alibaba und Bonprix haben bereits verstanden, dass der stationäre Handel nicht „ausstirbt“, sondern durch eine intelligente Verknüpfung mit dem Online-Handel sehr zukunftsweisend gemacht werden kann. Daher wird in dieser Arbeit auch gezeigt, wie sich pure E-Commerce-Unternehmen in den Innenstädten und Einkaufszentren in den USA, China und Deutschland ausbreiten und damit eine Omni-Channel-Strategie schaffen.
Durch den stark wachsenden Klinikcampus des Universitätsklinikums Freiburg ist die zentrale Versorgung mit medizinischem Sauerstoff an ihrer Kapazitätsgrenze angelangt. Es handelt sich um ein großflächiges, teilweise über viele Jahrzehnte altes Ringleitungssystem, an das immer wieder neue Kliniken und Institute angeschlossen wurden.
Das Ziel der vorliegenden Masterarbeit ist eine umfangreiche Untersuchung und Beurteilung von Sicherheits- und Kapazitätsparametern der zentralen medizinischen Gasversorgung. Hierzu erfolgte zunächst eine Literaturrecherche zum aktuellen Stand der Technik. Danach wurde eine Umfrage an insgesamt 14 deutschen Universitätskliniken mit ähnlicher Ringleitungstopologie durchgeführt. Es zeigte sich, dass in den meisten Fällen bisher noch keine detaillierte Analyse des eigenen Ringleitungssystems für medizinische Zwecke durchgeführt wurde.
An der Universitätsklinik Freiburg erfolgte die Analyse des Ringleitungssystems mit Hilfe der nicht-invasiven Clamp-On Messmethode für Gase. Dabei wurde als erstes festgestellt, dass die Strömungsgeschwindigkeiten innerhalb des Ringleitungssystems im Mittel so niedrig sind, dass keine Brandgefährdung vom z.B. durch die Selbstentzündung von Sauerstoff für die Klinik zu erwarten ist. Es stellte sich weiter heraus, dass für die Notversorgung der einzelnen Kliniken und Institute die Dimensionierung der Flaschenbatterien in lokalen Gasunterzentralen deutlich zu gering ist und dort nachgebessert werden sollte. Im Hinblick auf die o.g. Umfrage ist diese Masterarbeit sicher auch für andere Universitätskliniken bzw. Kliniken mit Campusinfrastruktur mit ähnlicher Ringleitungstopologie interessant.
Private households constitute a considerable share of Europe's electricity consumption. The current electricity distribution system treats them as effectively passive individual units. In the future, however, users of the electricity grid will be involved more actively in the grid operation and can become part of intelligent networked collaborations. They can then contribute the demand and supply flexibility that they dispose of and, as a result, help to better integrate renewable energy in-feed into the distribution grids.
High-precision signal processing algorithm to evaluate SAW properties as a function of temperature
(2013)
This paper presents a signal processing algorithm which accurately evaluates the SAW properties of a substrate as functions of temperature. The investigated acoustic properties are group velocity, phase velocity, propagation loss, and coupling coefficient. With several measurements carried out at different temperatures, we obtain the temperature dependency of the SAW properties. The analysis algorithm starts by reading the transfer functions of short and long delay lines. The analysis algorithm determines the center frequency of the delay lines and obtains the delay time difference between the short and long delay lines. The extracted parameters are then used to calculate the acoustic properties of the SAW material. To validate the algorithm, its accuracy is studied by determining the error in the calculating delay time difference, center frequency, and group velocity.
Researchers are developing new GNSS receivers and antennas based on an innovative signal-processing scheme to significantly improve GNSS tracking reliability and accuracy under degraded signal conditions. It is based on the principles of synthetic-aperture radar. Like in a multi-antenna phased array receiver, GNSS signals from different spatial locations are combined coherently forming an optimized synthetic antenna-gain pattern. The method is implemented in a real-time PC-based software receiver and works with GPS, GLONASS, and Galileo signals. Multiple frequencies are generally supported. The idea of synthetic-aperture processing is realized as a coherent summation of correlation values of each satellite over the so-called beamforming interval. Each correlation value is multiplied with a phase factor. For example, the phase factor can be chosen to compensate for the relative antenna motion over the beam-forming interval and the resulting sum of the scaled correlation values represents a coherent correlation value maximizing the line of sight signal power.
The paper proposes a system architecture for charging infrastructure that serves the requirements of future fleets of shared-use electric vehicles in urban scenarios. The focus of the development is on the interfaces to central stakeholders such as mobility service providers, distribution network operators and utilities. The main concept of the proposed system is the adherence to a stringent resource-oriented design approach, following the design principles of the Representational State Transfer (REST) architectural software style for distributed systems. This design approach is used from the cloud-based services down to the implementation of the charging infrastructure's control algorithms. Focusing on the resources of the various entities simplifies the implementation of their interactions, compared to the explicit declaration of services that are available. The system design ensures that the charging infrastructure is open to all users and generates a benefit beyond basic charging operations. Integration in emerging smart markets is done via open web-based interfaces. These allow for the generation of an added value of concrete services for shared-use electric mobility. A link to the field of grid operation is proposed using the ISO/IEC 61850 telecontrol standard. The smart meter capabilities of the charging stations can be used to gain additional information on the current state of the distribution grid. As an exemplary service a load management service for a fleet of shared-use electric vehicles is going to be implemented.
Die Analyse von Engpässen im Güterverkehr ist eine wichtige Voraussetzung, um zukünftige Heraus-forderungen der Infrastrukturplanung und Logistik bewältigen zu können. Im Rahmen des EU-Projekts Code24 sollen Strategien für die Behandlung zukünftiger Herausforderungen im Schienengüterverkehr im wichtigsten europäischen Güterverkehrskorridor Rotterdam-Genua entwickelt werden. Hierfür sind Infor-mationen über Zugzahlen und die Kapazitätsauslastung auf einzelnen Streckenabschnitten eine wichtige Voraussetzung.
Raman spectra from three different binary gasoline-ethanol blends (with ratios 95:5, 90:10, and 85:15) have been obtained by using a low-cost, frequency precise Fourier-transform Raman spectrometer (FT-Raman) prototype. The spectral information is presented in the range of 0 to 3500 cm-1 with a resolution of 1.66 cm-1, which is greater than the required for most liquid and solid chemical samples. This set-up delivers spectral information about the sample with a reduced spectral deviation compared to theoretical values (less than 0.4 cm-1 without compensation for instrumental response). The robust and highly fexible FT-Raman prototype presented for the spectral analysis, consisting mainly of a Michelson interferometer and a self-designed photon counter, is able to deliver high resolution and frequency precise Raman spectra from the gasoline-ethanol blends comparable to the obtained by using commercial devices. This FT-Raman set-up does not need additional complex hardware or software control and relies on re-sampling and interpolation algorithms. The qualitative spectral information obtained has been used to calculate the proportion of gasoline and ethanol present in the used chemical samples without using extra calibrations methods or chemical markers.
Background: Increasing awareness of the importance of evidence-based medicine is demonstrated not only by an increasing number of articles addressing it but also by a specialty-wide evidence-based medicine initiative. The authors critically analyzed the quality of reporting of randomized controlled trials published in this Journal over a 21-year period (1990 to 2010).
Methods: A hand search was conducted, including all issues of Plastic and Reconstructive Surgery from January of 1990 to December of 2010. All randomized controlled trials published during this time period were identified with the Cochrane decision tree for identification of randomized controlled trials. To assess the quality of reporting, a modification of the checklist of the Consolidated Standard of Reporting Trials Statement was used.
Results: Of 7121 original articles published from 1990 to 2010 in the Journal, 159 (2.23 percent) met the Cochrane criteria. A significant increase in the absolute number of randomized controlled trials was seen over the study period (p < 0.0001). The median quality of these trials from 1990 to 2010 was "fair," with a trend toward improved quality of reporting over time (p = 0.127).
Conclusions: A favorable trend is seen with respect to an increased number of published randomized controlled trials in Plastic and Reconstructive Surgery. Adherence to standard reporting guidelines is recommended, however, to further improve the quality of reporting. Consideration may be given to providing information regarding the quality of reporting in addition to the "level of evidence pyramid," thus facilitating critical appraisal.
Die Zuverlässigkeit und Betriebssicherheit von Feldgeräten ist für den sicheren und wirtschaftlichen Betrieb prozesstechnischer Anlagen unerlässlich. Ein entscheidender Faktor ist die Widerstandskraft der Geräte gegen die herrschenden Umgebungsbedingungen. Durch Korrosionsschäden hervorgerufene Anlagenstillstände zeigen, dass diesem Thema nicht immer die notwendige Aufmerksamkeit gewidmet wird, obwohl die korrosionsbedingten wirtschaftlichen Schäden immens sind. Wie man mit dem Thema Korrosionsschutz ernsthaft umgehen kann, zeigt dieser Beitrag am Beispiel elektrischer Stellantriebe.
Im Eurocode 3 wird im Gegensatz zu DIN 18800 die Bemessung von Verbindungen nicht in der Grundnorm DIN EN 1993‐1‐1, sondern in anderen Normenteilen geregelt. Dieser Beitrag behandelt die Bemessung geschweißter Verbindungen nach DIN EN 1993‐1‐8, die auch Hohlprofile, aber weder dünnwandige Bauteile noch Stähle höherer Festigkeit als S460 einschließt, vergleicht diese Bemessung mit der nach DIN 18800‐1, erläutert sie an Beispielen und hebt die wesentlichen Änderungen hervor. Da diese Änderungen auch die im Vergleich zu DIN 18800 viel stärkere Verknüpfung der in der Tragwerksplanung ansetzbaren Beanspruchbarkeiten mit dem Aufwand der Prüfung und Qualitätsüberwachung bei der Herstellung betreffen, werden abschließend wichtige Regelungen der DIN EN 1090‐2 zur Ausführung und Prüfung von Schweißnähten beschrieben, die auch der Tragwerksplaner kennen muss.
There is an increasing demand by an ever-growing number of mobile customers for transfer of rich media content. This requires very high bandwidth which either cannot be provided by the current cellular systems or puts pressure on the wireless networks, affecting customer service quality. This study introduces COARSE – a novel cluster-based quality-oriented adaptive radio resource allocation scheme, which dynamically and adaptively manages the radio resources in a cluster-based two-hop multi-cellular network, having a frequency reuse of one. COARSE is a cross-layer approach across physical layer, link layer and the application layer. COARSE gathers data delivery-related information from both physical and link layers and uses it to adjust bandwidth resources among the video streaming end-users. Extensive analysis and simulations show that COARSE enables a controlled trade-off between the physical layer data rate per user and the number of users communicating using a given resource. Significantly, COARSE provides 25–75% improvement in the computed user-perceived video quality compared with that obtained from an equivalent single-hop network.
Improved separation of highly toxic contact herbicides paraquat (1,1′-dimethyl-4-4′-bipyridinium), diquat (6,7-dihydrodipyridol[ 1,2-a:2′,1′-c]pyrazine-5,8-di-ium), difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium-methyl sulfate), mepiquat (1,1-dimethyl-piperidinium), and chloromequat (2-chloroethyltrimethylammonium) were presented by high-performance thin-layer chromatography (HPTLC). The quantification is based on a derivatization reaction, using sodium tetraphenylborate. Measurements were made in the wavelength range from 500 to 535 nm, using a light-emitting diode (LED) for excitation purposes, which emits very dense light at 365 nm. For calculations, a new theory of standard addition method was used, thus leading to a minimal error if exactly the same amount of sample content is added as a standard. The method provides a fast and inexpensive approach to quantification of the five most important quats used for plant protection purposes. The method works reliably because it takes into account losses during pre-treatment procedure. The method meets the European legislation limits for paraquat and diquat in drinking water according to United States Environmental Protection Agency (US EPA) method 549.2 which are 680 ng L−1 for paraquat and 720 ng L−1 for diquat. The method of standard addition in planar chromatography can be beneficially used to reduce systematic errors. Although recovery rates of 33.7% to 65.2% are observed, calculated contents according to the method of standard addition lie between 69% and 127% of the theoretical amounts.
The CO2 uptake on nanoscale AlO(OH) hollow spheres (260 mg g−1) as a new material is comparable to that on many metal–organic frameworks although their specific surface area is much lower (530 m2 g¬1versus 1500–6000 m2g¬1). Suited temperature–pressure cycles allow for reversible storage and separation of CO2 while the CO2 uptake is 4.3-times higher as compared to N2.
Multi-phase management is crucial for performance and durability of electrochemical cells such as batteries and fuel cells. In this paper we present a generic framework for describing the two-dimensional spatiotemporal evolution of gaseous, liquid and solid phases, as well as their interdependence with interfacial (electro-)chemistry and microstructure in a continuum description. The modeling domain consists of up to seven layers (current collectors, channels, electrodes, separator/membrane), each of which can consist of an arbitrary number of bulk phases (gas, liquid, solid) and connecting interfaces (two-phase or multi-phase boundaries). Bulk and interfacial chemistry is described using global or elementary kinetic reactions. Multi-phase management is coupled to chemistry and to mass and charge transport within bulk phases. The functionality and flexibility of this framework is demonstrated using four application areas in the context of post-lithium-ion batteries and fuel cells, that is, lithium-sulfur (Li-S) cells, lithium-oxygen (Li-O) cells, solid oxide fuel cells (SOFC) and polymer electrolyte membrane fuel cells (PEFC). The results are compared to models available in literature and properties of the generic framework are discussed.
Pure gas adsorption isotherms of CH4 and N2 and their binary mixtures were measured at 273 K, 298 K and 323 K and up to 2 MPa on two different microporous metal–organic frameworks (MOFs), i.e. the commercially available Basolite® A100 and the recently reported copper-based triazolyl benzoate MOF 3∞[Cu(Me-4py-trz-ia)] (1). The Tòth isotherm model and the vacancy solution model were used to describe the experimentally determined isotherms and proved to be well suited for this purpose. While 1 shows a more homogeneous surface with a nearly constant isosteric heat of adsorption of 18–18.5 kJ mol−1 for CH4 and 12–15 kJ mol−1 for N2, the isosteric heat of adsorption at zero coverage for Basolite® A100 is 19 kJ mol−1 for CH4 and 16.2 kJ mol−1 for N2, decreasing significantly with increasing loading. Binary adsorption isotherms were measured gravimetrically to determine the total adsorbed mass of CH4 and N2. The van Ness method was successfully applied to calculate partial loadings from gravimetrically measured binary adsorption isotherms. Further studies by volumetric–chromatographic experiments support the good correlation between experimental data and predictions by the vacancy solution model (VSM-Wilson) and the ideal adsorbed solution theory (IAST) from pure gas isotherms. The experimental selectivities were determined to be αCH4/N2 = 4.0–5.0 for 1, slightly higher than for Basolite® A100 with αCH4/N2 = 3.4–4.5. These values are in good agreement with predictions for ideal selectivities based on Henry's law constants. From the experimental selectivities the potential of both MOFs in gas separation of CH4 from N2 can be derived.
Limits of quantification of some neonicotinoid insecticides measured by thin-layer chromatography
(2012)
A simple method to quantify the neonicotinoid insecticides nitenpyram, thiamethoxam, acetamiprid, imidacloprid, thiacloprid and clothianidin directly on an HPTLC-plate is presented. As stationary phase silica gel 60 RP-18WF254 s plates were used and a mixture of methyl-t-butyl ether, 2-butanone, NH3 (25%) (5 + 2+0.1, v/v) was used as solvent. All neonicotinoid insecticides show light absorptions below 300 nm. The calculated limits of quantification (LOQ) by UV-detection are in the range from 12 ng to 26 ng on plate depending on the different insecticides.Nitenpyram can be stained using fast blue salt B, forming red zones. The observed LOQ is 25 ng on plate. Acetamiprid can be specifically stained using phenylglyoxylic acid forming a yellow/green fluorescent compound. The LOQ is 52 ng per spot.The compounds thiamethoxam, acetamiprid, thiacloprid and clothianidin can be transformed into blue fluorescing zones, using a relatively new staining solution. This consists of tetraphenylborate and HCl. This is the first publication mentioning that neonicotinoids undergo this reaction. The calculated limits of quantification are in the range from 10 ng to 27 ng on plate.A simple pre-treatment procedure using an acetonitrile extraction and a Chromabond SiOH clean up procedure leads to overall LOQs for bee samples of 48 to 108 µg/Kg. The method can be used to measure neonicotinoid contaminations of bees.
The study from Mehrazin et al. in HJNM 2011; 14(3): 243-50 on the neuropsychology, morphological computerized tomography (CT) and functional neuroimaging with 99mTc-labelled ethylene cystein-ate dimer single-photon emission tomography (SPET) in mild trau-matic brain injury (MTBI) is an interesting new approach to a disease condition which is often neglected or denied. Related to the above, we may note that the French composer Maurice Ravel (1875-1937), who suffered from Pick ́s disease with primary progressive apha-sia, had a taxi accident in 1932, with a mild concussion, perhaps an MTBI. Apart from the dysphasia and beginning apraxia, which Rav-el had already 5 years prior to the taxi accident, these symptoms exacerbated-the dysphasia became a progressive aphasia-and he developed additional severe deficits in concentration and atten-tion after the accident. It has also been suspected that this accident may have triggered Ravel ́s agraphia the unability to write down any new composition beyond the date of the taxi accident, a condi-tion that Ravel himself described as unacceptable and which made him feel very sad as his mind was full of ideas. Due to the deterio-ration of his health, which can also be seen in his appearance on late photographs, Ravel consulted the famous neurosurgeon Prof. Clovis Vincent. Vincent, who suspected a hydrocephalus, opened Ravel ́s skull on December 19, 1937, showing a normal brain. Soon after surgery Ravel died. In conclusion, a SPET/CT approach com-bined with a brain perfusion analysis using statistical parametric mapping might be the recommendable approach today for mild traumatic brain injury.
In this paper, the multiaxial formulation of a mechanism-based model for fatigue life prediction is presented whichcan be applied to low-cycle fatigue (LCF) and thermomechanical fatigue (TMF) problems in which high-cycle fa-tigue loadings are superimposed. The model assumes that crack growth is the lifetime limiting mechanism and thatthe crack advance in a loading cycleda/dNcorrelates with the cyclic crack-tip opening displacement ΔCTOD.The multiaxial formulation makes use of fracture mechanics solutions and thus, does not need additional modelparameters quantifying the effect of the multiaxiality. Furthermore, the model includes contributions of HCF on ΔCTODand assesses the effect of the direction of the HCF loadings with respect to LCF or TMF loadings inthe life prediction. The model is implemented into the finite-element program ABAQUS. It is applied to predictthe fatigue life of a thermomechanically loaded notched specimen that should represent the situation between theinlet and outlet bore holes of cylinder heads. A good correlation of the predicted and the measured fatigue lives isobtained.
The newly synthesized Zn4O-based MOF 3∞[Zn4(μ4-O){(Metrz-pba)2mPh}3]·8 DMF (1·8 DMF) of rare tungsten carbide (acs) topology exhibits a porosity of 43% and remarkably high thermal stability up to 430 °C. Single crystal X-ray structure analyses could be performed using as-synthesized as well as desolvated crystals. Besides the solvothermal synthesis of single crystals a scalable synthesis of microcrystalline material of the MOF is reported. Combined TG-MS and solid state NMR measurements reveal the presence of mobile DMF molecules in the pore system of the framework. Adsorption measurements confirm that the pore structure is fully accessible for nitrogen molecules at 77 K. The adsorptive pore volume of 0.41 cm3 g−1 correlates well with the pore volume of 0.43 cm3 g−1 estimated from the single crystal structure.
Städte und Gemeinden müssen sich heute den veränderten Informations- und Kommunikationsverhalten in der Gesellschaft anpassen und entsprechend den Kommunikationsmix erweitern beziehungsweise neu ausrichten. Dabei bieten insbesondere die Online-Kommunikationsmaßnahmen zahlreiche neue Möglichkeiten, zum Beispiel das Targeting. Der folgende Beitrag gibt zunächst einen Überblick über den Kommunikationsprozess und das Content-Marketing. Im Anschluss werden einige wichtige Kommunikationsinstrumente für das Stadtmarketing näher vorgestellt.
An isomorphous series of 10 microporous copper-based metal–organic frameworks (MOFs) with the general formulas ∞3[{Cu3(μ3-OH)(X)}4{Cu2(H2O)2}3(H-R-trz-ia)12] (R = H, CH3, Ph; X2– = SO42–, SeO42–, 2 NO32– (1–8)) and ∞3[{Cu3(μ3-OH)(X)}8{Cu2(H2O)2}6(H-3py-trz-ia)24Cu6]X3 (R = 3py; X2– = SO42–, SeO42– (9, 10)) is presented together with the closely related compounds ∞3[Cu6(μ4-O)(μ3-OH)2(H-Metrz-ia)4][Cu(H2O)6](NO3)2·10H2O (11) and ∞3[Cu2(H-3py-trz-ia)2(H2O)3] (12Cu), which are obtained under similar reaction conditions. The porosity of the series of cubic MOFs with twf-d topology reaches up to 66%. While the diameters of the spherical pores remain unaffected, adsorption measurements show that the pore volume can be fine-tuned by the substituents of the triazolyl isophthalate ligand and choice of the respective copper salt, that is, copper sulfate, selenate, or nitrate.
The suffix-free-prefix-free hash function construction and its indifferentiability security analysis
(2012)
In this paper, we observe that in the seminal work on indifferentiability analysis of iterated hash functions by Coron et al. and in subsequent works, the initial value (IV) of hash functions is fixed. In addition, these indifferentiability results do not depend on the Merkle–Damgård (MD) strengthening in the padding functionality of the hash functions. We propose a generic n-bit-iterated hash function framework based on an n-bit compression function called suffix-free-prefix-free (SFPF) that works for arbitrary IVs and does not possess MD strengthening. We formally prove that SFPF is indifferentiable from a random oracle (RO) when the compression function is viewed as a fixed input-length random oracle (FIL-RO). We show that some hash function constructions proposed in the literature fit in the SFPF framework while others that do not fit in this framework are not indifferentiable from a RO. We also show that the SFPF hash function framework with the provision of MD strengthening generalizes any n-bit-iterated hash function based on an n-bit compression function and with an n-bit chaining value that is proven indifferentiable from a RO.
As a basis for the evaluation of hydrogen storage by physisorption, adsorption isotherms of H2 were experimentally determined for several porous materials at 77 K and 298 K at pressures up to 15 MPa. Activated carbons and MOFs were studied as the most promising materials for this purpose. A noble focus was given on how to determine whether a material is feasible for hydrogen storage or not, dealing with an assessment method and the pitfalls and problems of determining the viability. For a quantitative evaluation of the feasibility of sorptive hydrogen storage in a general analysis, it is suggested to compare the stored amount in a theoretical tank filled with adsorbents to the amount of hydrogen stored in the same tank without adsorbents. According to our results, an “ideal” sorbent for hydrogen storage at 77 K is calculated to exhibit a specific surface area of >2580 m2 g−1 and a micropore volume of >1.58 cm3 g−1.
In this work the adsorption of CO2 and CH4 on a series of isoreticular microporous metal–organic frameworks based on 2-substituted imidazolate-4-amide-5-imidates, IFP-1–IFP-6 (IFP = Imidazolate Framework Potsdam), is studied firstly by pure gas adsorption at 273 K. All experimental isotherms can be nicely described by using the Tòth isotherm model and show the preferred adsorption of CO2 over CH4. At low pressures the Tòth isotherm equation exhibits a Henry region, wherefore Henry's law constants for CO2 and CH4 uptake could be determined and ideal selectivity αCO2/CH4 has been calculated. Secondly, selectivities were calculated from mixture data by using nearly equimolar binary mixtures of both gases by a volumetric–chromatographic method to examine the IFPs. Results showed the reliability of the selectivity calculation. Values of αCO2/CH4 around 7.5 for IFP-5 indicate that this material shows much better selectivities than IFP-1, IFP-2, IFP-3, IFP-4 and IFP-6 with slightly lower selectivity αCO2/CH4 = 4–6. The preferred adsorption of CO2 over CH4 especially of IFP-5 and IFP-4 makes these materials suitable for gas separation application.
We present a video-densitometric quantification method for the pain killer known as diclofenac and ibuprofen. These non-steroidal anti-inflammatory drugs were separated on cyanopropyl bonded plates using CH2Cl2, methanol, cyclohexane (95 + 5 + 40, v/v) as mobile phase. The quantification is based on a bio-effective-linked analysis using Vibrio fisheri bacteria. Within 10 min a CCD-camera registered the white light of the light-emitting bacteria. Diclofenac and ibuprofen effectively suppressed the bacterial light emission which can be used for quantification within a linear range of 10 to 2000 ng. The detection limit for ibuprofen is 20 ng and the limit of quantification 26 ng per zone. Measurements were carried out using a 16-bit ST-1603ME CCD camera with 1.56 megapixels (from Santa Barbara Instrument Group, Inc., Santa Barbara, USA). The range of linearity covers more than two magnitudes because the extended Kubelka-Munk expression is used for data transformation. The separation method is inexpensive, fast, and reliable.
High pressure adsorption phenomena are discussed for different gases on HKUST-1 (Cu3(BTC)2, commercially available product BasoliteTM C300). Sorption isotherms for hydrogen, nitrogen, methane and carbon dioxide on HKUST-1 were measured in the temperature range of 273–343 K and at pressures up to 50 MPa. The calculated surface excess adsorption capacities for all four adsorptive are one of the highest reported in the literature for HKUST-1 samples. All surface excess data were further calculated from the experimental data by using the helium buoyancy correction. A detailed description was given.
Also a procedure to calculate the absolute amount adsorbed from the surface excess amount by using two different models is shown. Using one model, the density and the volume of the adsorbed phase can be calculated. The density of the adsorbed phase ρads corresponds to the liquid density of the adsorptive at its boiling point ρliq,BP. In case of hydrogen no excess maximum was found up to 50 MPa, so that one model could not be applied. Finally, the isosteric heat of adsorption for each gas was calculated by using the Clausius–Clapeyron equation.