Beiträge zur Größencharakterisierung von Polyolefinen – Untersuchungen zu alternativen Lösungsmitteln und einer alternativen Trennmethode (HT-AF4)

Diese Arbeit beschäftigt sich mit zwei Aspekten der Größenseparation von Polyolefinen. Zum einen der Suche nach Lösungsmitteln die alternativ zum verbreiteten 1,2,4-Trichlorbenzol (TCB) eingesetzt werden können und zum anderen mit Untersuchungen zur Hochtemperatur Asymmetrischer-Fluss-Feld-Fluss-Fraktionierung (HT-AF4), einer Methode die alternativ zur klassischen Größenausschlusschromatographie bei hohen Temperaturen (HT-SEC) für die Größenseparation von Polyolefinen eingesetzt werden kann. TCB ist trotz seiner hohen Verbreitung ein unter ökologischen und toxikologischen Aspekten bedenkliches Lösungsmittel. Eine weniger bedenkliche Alternative für HT SEC Untersuchungen wäre daher hochwillkommen. Im Rahmen der Arbeit konnte eine Reihe neuer Lösungsmittel für Polyolefine identifiziert und hinsichtlich ihrer thermodynamischen Qualität beurteilt werden. Weitere Untersuchungen zur Eignung der Lösungsmittel für die HT-SEC unter Einsatz eines Verdampfungslichtstreudetektors (ELSD) förderten überraschend unterschiedliche Zusammenhänge zwischen dem Detektorsignal und der Molmasse sowie der chemischen Zusammensetzung von Polyolefin-Proben zu Tage. Es konnten insgesamt sowohl einige Lösungsmittel identifiziert werden, die geeignet erscheinen TCB zu ersetzen wie auch wichtige Erkenntnisse für die Wechselwirkungschromatographie von Polyolefinen gewonnen werden. In weiteren Untersuchungen kann die Verwendung alternativer Lösungsmittel nun optimiert werden. Die HT-AF4 zeichnet sich gegenüber der HT-SEC durch eine deutlich bessere Eignung zur Analyse von ultrahochmolekularen und langkettenverzweigten Polyolefinen aus, da Phänomene wie Scherdegradation und abnorm späte Coelution bei der HT-AF4 nicht auftreten. Frühere Untersuchungen zur HT-AF4 zeigten jedoch technische Schwierigkeiten, die einen Routine-Einsatz unmöglich machten. Seitdem wurde die Methode weiterentwickelt und im Rahmen der vorliegenden Arbeit wurde die Routinetauglichkeit der Methode erneut evaluiert. Dabei erwies sich die HT-AF4 Methode als nunmehr vollkommen routinetauglich. Bei den Untersuchungen wurden einige Phänomene gefunden, die weiterer Experimente bedurften. Einige der Phänomene konnten erklärt werden und schränken die Funktion der HT-AF4 nicht ein. Andere Phänomene bedürfen noch weiterer Untersuchungen um zu klären, wie mit diesen am sinnvollsten umzugehen ist. Erste Ansätze dazu und mögliche Erklärungen werden im Rahmen der Arbeit gezeigt

Human Practice. Digital Ecologies. Our Future. : 14. Internationale Tagung Wirtschaftsinformatik (WI 2019) : Tagungsband

Erschienen bei: universi - Universitätsverlag Siegen. - ISBN: 978-3-96182-063-4Aus dem Inhalt: Track 1: Produktion & Cyber-Physische Systeme Requirements and a Meta Model for Exchanging Additive Manufacturing Capacities Service Systems, Smart Service Systems and Cyber- Physical Systems—What’s the difference? Towards a Unified Terminology Developing an Industrial IoT Platform – Trade-off between Horizontal and Vertical Approaches Machine Learning und Complex Event Processing: Effiziente Echtzeitauswertung am Beispiel Smart Factory Sensor retrofit for a coffee machine as condition monitoring and predictive maintenance use case Stakeholder-Analyse zum Einsatz IIoT-basierter Frischeinformationen in der Lebensmittelindustrie Towards a Framework for Predictive Maintenance Strategies in Mechanical Engineering - A Method-Oriented Literature Analysis Development of a matching platform for the requirement-oriented selection of cyber physical systems for SMEs Track 2: Logistic Analytics An Empirical Study of Customers’ Behavioral Intention to Use Ridepooling Services – An Extension of the Technology Acceptance Model Modeling Delay Propagation and Transmission in Railway Networks What is the impact of company specific adjustments on the acceptance and diffusion of logistic standards? Robust Route Planning in Intermodal Urban Traffic Track 3: Unternehmensmodellierung & Informationssystemgestaltung (Enterprise Modelling & Information Systems Design) Work System Modeling Method with Different Levels of Specificity and Rigor for Different Stakeholder Purposes Resolving Inconsistencies in Declarative Process Models based on Culpability Measurement Strategic Analysis in the Realm of Enterprise Modeling – On the Example of Blockchain-Based Initiatives for the Electricity Sector Zwischenbetriebliche Integration in der Möbelbranche: Konfigurationen und Einflussfaktoren Novices’ Quality Perceptions and the Acceptance of Process Modeling Grammars Entwicklung einer Definition für Social Business Objects (SBO) zur Modellierung von Unternehmensinformationen Designing a Reference Model for Digital Product Configurators Terminology for Evolving Design Artifacts Business Role-Object Specification: A Language for Behavior-aware Structural Modeling of Business Objects Generating Smart Glasses-based Information Systems with BPMN4SGA: A BPMN Extension for Smart Glasses Applications Using Blockchain in Peer-to-Peer Carsharing to Build Trust in the Sharing Economy Testing in Big Data: An Architecture Pattern for a Development Environment for Innovative, Integrated and Robust Applications Track 4: Lern- und Wissensmanagement (e-Learning and Knowledge Management) eGovernment Competences revisited – A Literature Review on necessary Competences in a Digitalized Public Sector Say Hello to Your New Automated Tutor – A Structured Literature Review on Pedagogical Conversational Agents Teaching the Digital Transformation of Business Processes: Design of a Simulation Game for Information Systems Education Conceptualizing Immersion for Individual Learning in Virtual Reality Designing a Flipped Classroom Course – a Process Model The Influence of Risk-Taking on Knowledge Exchange and Combination Gamified Feedback durch Avatare im Mobile Learning Alexa, Can You Help Me Solve That Problem? - Understanding the Value of Smart Personal Assistants as Tutors for Complex Problem Tasks Track 5: Data Science & Business Analytics Matching with Bundle Preferences: Tradeoff between Fairness and Truthfulness Applied image recognition: guidelines for using deep learning models in practice Yield Prognosis for the Agrarian Management of Vineyards using Deep Learning for Object Counting Reading Between the Lines of Qualitative Data – How to Detect Hidden Structure Based on Codes Online Auctions with Dual-Threshold Algorithms: An Experimental Study and Practical Evaluation Design Features of Non-Financial Reward Programs for Online Reviews: Evaluation based on Google Maps Data Topic Embeddings – A New Approach to Classify Very Short Documents Based on Predefined Topics Leveraging Unstructured Image Data for Product Quality Improvement Decision Support for Real Estate Investors: Improving Real Estate Valuation with 3D City Models and Points of Interest Knowledge Discovery from CVs: A Topic Modeling Procedure Online Product Descriptions – Boost for your Sales? Entscheidungsunterstützung durch historienbasierte Dienstreihenfolgeplanung mit Pattern A Semi-Automated Approach for Generating Online Review Templates Machine Learning goes Measure Management: Leveraging Anomaly Detection and Parts Search to Improve Product-Cost Optimization Bedeutung von Predictive Analytics für den theoretischen Erkenntnisgewinn in der IS-Forschung Track 6: Digitale Transformation und Dienstleistungen Heuristic Theorizing in Software Development: Deriving Design Principles for Smart Glasses-based Systems Mirroring E-service for Brick and Mortar Retail: An Assessment and Survey Taxonomy of Digital Platforms: A Platform Architecture Perspective Value of Star Players in the Digital Age Local Shopping Platforms – Harnessing Locational Advantages for the Digital Transformation of Local Retail Outlets: A Content Analysis A Socio-Technical Approach to Manage Analytics-as-a-Service – Results of an Action Design Research Project Characterizing Approaches to Digital Transformation: Development of a Taxonomy of Digital Units Expectations vs. Reality – Benefits of Smart Services in the Field of Tension between Industry and Science Innovation Networks and Digital Innovation: How Organizations Use Innovation Networks in a Digitized Environment Characterising Social Reading Platforms— A Taxonomy-Based Approach to Structure the Field Less Complex than Expected – What Really Drives IT Consulting Value Modularity Canvas – A Framework for Visualizing Potentials of Service Modularity Towards a Conceptualization of Capabilities for Innovating Business Models in the Industrial Internet of Things A Taxonomy of Barriers to Digital Transformation Ambidexterity in Service Innovation Research: A Systematic Literature Review Design and success factors of an online solution for cross-pillar pension information Track 7: IT-Management und -Strategie A Frugal Support Structure for New Software Implementations in SMEs How to Structure a Company-wide Adoption of Big Data Analytics The Changing Roles of Innovation Actors and Organizational Antecedents in the Digital Age Bewertung des Kundennutzens von Chatbots für den Einsatz im Servicedesk Understanding the Benefits of Agile Software Development in Regulated Environments Are Employees Following the Rules? On the Effectiveness of IT Consumerization Policies Agile and Attached: The Impact of Agile Practices on Agile Team Members’ Affective Organisational Commitment The Complexity Trap – Limits of IT Flexibility for Supporting Organizational Agility in Decentralized Organizations Platform Openness: A Systematic Literature Review and Avenues for Future Research Competence, Fashion and the Case of Blockchain The Digital Platform Otto.de: A Case Study of Growth, Complexity, and Generativity Track 8: eHealth & alternde Gesellschaft Security and Privacy of Personal Health Records in Cloud Computing Environments – An Experimental Exploration of the Impact of Storage Solutions and Data Breaches Patientenintegration durch Pfadsysteme Digitalisierung in der Stressprävention – eine qualitative Interviewstudie zu Nutzenpotenzialen User Dynamics in Mental Health Forums – A Sentiment Analysis Perspective Intent and the Use of Wearables in the Workplace – A Model Development Understanding Patient Pathways in the Context of Integrated Health Care Services - Implications from a Scoping Review Understanding the Habitual Use of Wearable Activity Trackers On the Fit in Fitness Apps: Studying the Interaction of Motivational Affordances and Users’ Goal Orientations in Affecting the Benefits Gained Gamification in Health Behavior Change Support Systems - A Synthesis of Unintended Side Effects Investigating the Influence of Information Incongruity on Trust-Relations within Trilateral Healthcare Settings Track 9: Krisen- und Kontinuitätsmanagement Potentiale von IKT beim Ausfall kritischer Infrastrukturen: Erwartungen, Informationsgewinnung und Mediennutzung der Zivilbevölkerung in Deutschland Fake News Perception in Germany: A Representative Study of People’s Attitudes and Approaches to Counteract Disinformation Analyzing the Potential of Graphical Building Information for Fire Emergency Responses: Findings from a Controlled Experiment Track 10: Human-Computer Interaction Towards a Taxonomy of Platforms for Conversational Agent Design Measuring Service Encounter Satisfaction with Customer Service Chatbots using Sentiment Analysis Self-Tracking and Gamification: Analyzing the Interplay of Motivations, Usage and Motivation Fulfillment Erfolgsfaktoren von Augmented-Reality-Applikationen: Analyse von Nutzerrezensionen mit dem Review-Mining-Verfahren Designing Dynamic Decision Support for Electronic Requirements Negotiations Who is Stressed by Using ICTs? A Qualitative Comparison Analysis with the Big Five Personality Traits to Understand Technostress Walking the Middle Path: How Medium Trade-Off Exposure Leads to Higher Consumer Satisfaction in Recommender Agents Theory-Based Affordances of Utilitarian, Hedonic and Dual-Purposed Technologies: A Literature Review Eliciting Customer Preferences for Shopping Companion Apps: A Service Quality Approach The Role of Early User Participation in Discovering Software – A Case Study from the Context of Smart Glasses The Fluidity of the Self-Concept as a Framework to Explain the Motivation to Play Video Games Heart over Heels? An Empirical Analysis of the Relationship between Emotions and Review Helpfulness for Experience and Credence Goods Track 11: Information Security and Information Privacy Unfolding Concerns about Augmented Reality Technologies: A Qualitative Analysis of User Perceptions To (Psychologically) Own Data is to Protect Data: How Psychological Ownership Determines Protective Behavior in a Work and Private Context Understanding Data Protection Regulations from a Data Management Perspective: A Capability-Based Approach to EU-GDPR On the Difficulties of Incentivizing Online Privacy through Transparency: A Qualitative Survey of the German Health Insurance Market What is Your Selfie Worth? A Field Study on Individuals’ Valuation of Personal Data Justification of Mass Surveillance: A Quantitative Study An Exploratory Study of Risk Perception for Data Disclosure to a Network of Firms Track 12: Umweltinformatik und nachhaltiges Wirtschaften Kommunikationsfäden im Nadelöhr – Fachliche Prozessmodellierung der Nachhaltigkeitskommunikation am Kapitalmarkt Potentiale und Herausforderungen der Materialflusskostenrechnung Computing Incentives for User-Based Relocation in Carsharing Sustainability’s Coming Home: Preliminary Design Principles for the Sustainable Smart District Substitution of hazardous chemical substances using Deep Learning and t-SNE A Hierarchy of DSMLs in Support of Product Life-Cycle Assessment A Survey of Smart Energy Services for Private Households Door-to-Door Mobility Integrators as Keystone Organizations of Smart Ecosystems: Resources and Value Co-Creation – A Literature Review Ein Entscheidungsunterstützungssystem zur ökonomischen Bewertung von Mieterstrom auf Basis der Clusteranalyse Discovering Blockchain for Sustainable Product-Service Systems to enhance the Circular Economy Digitale Rückverfolgbarkeit von Lebensmitteln: Eine verbraucherinformatische Studie Umweltbewusstsein durch audiovisuelles Content Marketing? Eine experimentelle Untersuchung zur Konsumentenbewertung nachhaltiger Smartphones Towards Predictive Energy Management in Information Systems: A Research Proposal A Web Browser-Based Application for Processing and Analyzing Material Flow Models using the MFCA Methodology Track 13: Digital Work - Social, mobile, smart On Conversational Agents in Information Systems Research: Analyzing the Past to Guide Future Work The Potential of Augmented Reality for Improving Occupational First Aid Prevent a Vicious Circle! The Role of Organizational IT-Capability in Attracting IT-affine Applicants Good, Bad, or Both? Conceptualization and Measurement of Ambivalent User Attitudes Towards AI A Case Study on Cross-Hierarchical Communication in Digital Work Environments ‘Show Me Your People Skills’ - Employing CEO Branding for Corporate Reputation Management in Social Media A Multiorganisational Study of the Drivers and Barriers of Enterprise Collaboration Systems-Enabled Change The More the Merrier? The Effect of Size of Core Team Subgroups on Success of Open Source Projects The Impact of Anthropomorphic and Functional Chatbot Design Features in Enterprise Collaboration Systems on User Acceptance Digital Feedback for Digital Work? Affordances and Constraints of a Feedback App at InsurCorp The Effect of Marker-less Augmented Reality on Task and Learning Performance Antecedents for Cyberloafing – A Literature Review Internal Crowd Work as a Source of Empowerment - An Empirical Analysis of the Perception of Employees in a Crowdtesting Project Track 14: Geschäftsmodelle und digitales Unternehmertum Dividing the ICO Jungle: Extracting and Evaluating Design Archetypes Capturing Value from Data: Exploring Factors Influencing Revenue Model Design for Data-Driven Services Understanding the Role of Data for Innovating Business Models: A System Dynamics Perspective Business Model Innovation and Stakeholder: Exploring Mechanisms and Outcomes of Value Creation and Destruction Business Models for Internet of Things Platforms: Empirical Development of a Taxonomy and Archetypes Revitalizing established Industrial Companies: State of the Art and Success Principles of Digital Corporate Incubators When 1+1 is Greater than 2: Concurrence of Additional Digital and Established Business Models within Companies Special Track 1: Student Track Investigating Personalized Price Discrimination of Textile-, Electronics- and General Stores in German Online Retail From Facets to a Universal Definition – An Analysis of IoT Usage in Retail Is the Technostress Creators Inventory Still an Up-To-Date Measurement Instrument? Results of a Large-Scale Interview Study Application of Media Synchronicity Theory to Creative Tasks in Virtual Teams Using the Example of Design Thinking TrustyTweet: An Indicator-based Browser-Plugin to Assist Users in Dealing with Fake News on Twitter Application of Process Mining Techniques to Support Maintenance-Related Objectives How Voice Can Change Customer Satisfaction: A Comparative Analysis between E-Commerce and Voice Commerce Business Process Compliance and Blockchain: How Does the Ethereum Blockchain Address Challenges of Business Process Compliance? Improving Business Model Configuration through a Question-based Approach The Influence of Situational Factors and Gamification on Intrinsic Motivation and Learning Evaluation von ITSM-Tools für Integration und Management von Cloud-Diensten am Beispiel von ServiceNow How Software Promotes the Integration of Sustainability in Business Process Management Criteria Catalog for Industrial IoT Platforms from the Perspective of the Machine Tool Industry Special Track 3: Demos & Prototyping Privacy-friendly User Location Tracking with Smart Devices: The BeaT Prototype Application-oriented robotics in nursing homes Augmented Reality for Set-up Processe Mixed Reality for supporting Remote-Meetings Gamification zur Motivationssteigerung von Werkern bei der Betriebsdatenerfassung Automatically Extracting and Analyzing Customer Needs from Twitter: A “Needmining” Prototype GaNEsHA: Opportunities for Sustainable Transportation in Smart Cities TUCANA: A platform for using local processing power of edge devices for building data-driven services Demonstrator zur Beschreibung und Visualisierung einer kritischen Infrastruktur Entwicklung einer alltagsnahen persuasiven App zur Bewegungsmotivation für ältere Nutzerinnen und Nutzer A browser-based modeling tool for studying the learning of conceptual modeling based on a multi-modal data collection approach Exergames & Dementia: An interactive System for People with Dementia and their Care-Network Workshops Workshop Ethics and Morality in Business Informatics (Workshop Ethik und Moral in der Wirtschaftsinformatik – EMoWI’19) Model-Based Compliance in Information Systems - Foundations, Case Description and Data Set of the MobIS-Challenge for Students and Doctoral Candidates Report of the Workshop on Concepts and Methods of Identifying Digital Potentials in Information Management Control of Systemic Risks in Global Networks - A Grand Challenge to Information Systems Research Die Mitarbeiter von morgen - Kompetenzen künftiger Mitarbeiter im Bereich Business Analytics Digitaler Konsum: Herausforderungen und Chancen der Verbraucherinformati

Alignment of the CMS tracker with LHC and cosmic ray data

© CERN 2014 for the benefit of the CMS collaboration, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl. Any further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation and DOI.The central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multi-processor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10μm

Beiträge zur Größencharakterisierung von Polyolefinen – Untersuchungen zu alternativen Lösungsmitteln und einer alternativen Trennmethode (HT-AF4)

Diese Arbeit beschäftigt sich mit zwei Aspekten der Größenseparation von Polyolefinen. Zum einen der Suche nach Lösungsmitteln die alternativ zum verbreiteten 1,2,4-Trichlorbenzol (TCB) eingesetzt werden können und zum anderen mit Untersuchungen zur Hochtemperatur Asymmetrischer-Fluss-Feld-Fluss-Fraktionierung (HT-AF4), einer Methode die alternativ zur klassischen Größenausschlusschromatographie bei hohen Temperaturen (HT-SEC) für die Größenseparation von Polyolefinen eingesetzt werden kann. TCB ist trotz seiner hohen Verbreitung ein unter ökologischen und toxikologischen Aspekten bedenkliches Lösungsmittel. Eine weniger bedenkliche Alternative für HT SEC Untersuchungen wäre daher hochwillkommen. Im Rahmen der Arbeit konnte eine Reihe neuer Lösungsmittel für Polyolefine identifiziert und hinsichtlich ihrer thermodynamischen Qualität beurteilt werden. Weitere Untersuchungen zur Eignung der Lösungsmittel für die HT-SEC unter Einsatz eines Verdampfungslichtstreudetektors (ELSD) förderten überraschend unterschiedliche Zusammenhänge zwischen dem Detektorsignal und der Molmasse sowie der chemischen Zusammensetzung von Polyolefin-Proben zu Tage. Es konnten insgesamt sowohl einige Lösungsmittel identifiziert werden, die geeignet erscheinen TCB zu ersetzen wie auch wichtige Erkenntnisse für die Wechselwirkungschromatographie von Polyolefinen gewonnen werden. In weiteren Untersuchungen kann die Verwendung alternativer Lösungsmittel nun optimiert werden. Die HT-AF4 zeichnet sich gegenüber der HT-SEC durch eine deutlich bessere Eignung zur Analyse von ultrahochmolekularen und langkettenverzweigten Polyolefinen aus, da Phänomene wie Scherdegradation und abnorm späte Coelution bei der HT-AF4 nicht auftreten. Frühere Untersuchungen zur HT-AF4 zeigten jedoch technische Schwierigkeiten, die einen Routine-Einsatz unmöglich machten. Seitdem wurde die Methode weiterentwickelt und im Rahmen der vorliegenden Arbeit wurde die Routinetauglichkeit der Methode erneut evaluiert. Dabei erwies sich die HT-AF4 Methode als nunmehr vollkommen routinetauglich. Bei den Untersuchungen wurden einige Phänomene gefunden, die weiterer Experimente bedurften. Einige der Phänomene konnten erklärt werden und schränken die Funktion der HT-AF4 nicht ein. Andere Phänomene bedürfen noch weiterer Untersuchungen um zu klären, wie mit diesen am sinnvollsten umzugehen ist. Erste Ansätze dazu und mögliche Erklärungen werden im Rahmen der Arbeit gezeigt

Wie wirksam sind Haftvermittler?: Verbessertes Verständnis für modifizierte Polyolefinde sowie die Bewertung ihrer Wirksamkeit

Modifizierte Polyolefine besitzen große wirtschaftliche Bedeutung als Haftvermittler zwischen Polyolefinen und polaren Materialien. Eine neue neue chromatografische Methode erlaubt es jetzt erstmals, systematische Struktur-Eigenschaftsbeziehungen für diese Materialien zu erarbeiten, die entscheidende Hinweise für Optimierungen des Syntheseprozesses liefern

Elution behavior of polypropylene with different tacticity: An overview

High-temperature liquid chromatography (HT-HPLC) using solvent gradients enables to separate polypropylene (PP) according to tacticity. Varying the combination of adsorption and desorption promoting solvent the three stereochemical variants iPP, aPP and sPP can be selectively retained in a Hypercarb™ column. Two new desorption promoting solvents, namely 1-chloronaphtalene and 2-chlorotoluene, were tested. Among these 2-chlorotoluene was found to improve the selectivity of the separation of the atactic variant from the syndiotactic one. Linear polyethylene (PE) was retained in the column in the majority of the tested solvent/sorbent systems. Thus, several HPLC systems described in this paper enable the separation of blends consisting of PE and PP, as well as the realization of selective HPLC separations of polypropylene according to its tacticity

HPLC Separation of Ethylene-Vinyl Acetate Copolymers According to Chemical Composition

Ethylene–vinyl acetate (EVA) copolymers are in dependence on their chemical composition, amorphous, or semicrystalline materials. Therefore, fractionation techniques which are based on crystallization, such as temperature rising elution fractionation (TREF) and crystallization fractionation (CRYSTAF), cannot offer information about the chemical composition distribution of these polymers in the case of amorphous samples. Liquid chromatography has been shown to be a valuable alternative; yet, systems based on silica gel lacked in terms of long-term stability. Using porous graphite, this drawback may be overcome. An HPLC column packed with porous graphite Hypercarb™ and a solvent gradient 2-ethyl-1-hexanol (or cyclohexanone) → 1,2,4-trichlorobenzene can separate EVA copolymers over the full range of VA content at temperatures above 100 °C. A linear dependence between the VA content of the copolymers and their elution volume could be established. Moreover, the chromatographic resolution is larger than obtained using silica gel as stationary phase

Characterization of the chemical composition distribution of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) and comparison to theoretical predictions

Ethylene/1-olefin copolymers with a 1-olefin content>10wt%, known as polyolefin plastomers (POP) and elastomers (POE), are materials of growing commercial importance. A relevant example are ethylene/1-octene(EO) copolymers. The thermal properties of nine 1-octene based POP/POE were studied by differential scanning calorimetry (DSC). The obtained thermograms were indicative of an asymmetric chemical composition distribution(CCD), triggering further investigations. At first, analytical temperature rising elution fractionation (a-TREF) was employed which gave further evidence of an asymmetric CCD for some samples. Given the low crystallinity of many of the samples, their CCD could, however, only be studied by high temperature high performance liquid chromatography (HT-HPLC). The hypothesis about an asymmetric CCD could be confirmed for all samples. The results were compared with theoretically calculated CCD (Stockmayer distributions) which are symmetrical. In a semiquantitative comparison, the main peak of the experimental CCD was found to be in good agreement with Stockmayer distributions

High performance liquid chromatography of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) - Comparison of different solvent systems

A series of ethylene/1-octene copolymers with different chemical composition was separated in six binary mobile phases using solvent gradients and a column packed with porous graphite HypercarbTM. It was found that the elution volumes of the samples were to a larger extent influenced by the choice of desorption promoting solvent (desorli: 1,2-dichlorobenzene vs. 1,2,4-trichlorobenzene) than by the choice of adsorption promoting solvent (2-ethyl-1-hexanol, 1-decanol, n-decane). Elution volumes increased with decreasing number of chlorine atoms in the desorlis as well as with increasing polarity of the adsorlis. The resolution of HPLC systems depended pronouncedly on the choice of solvent pair: While in the majority of the tested HPLC systems, the chromatograms of the polymer samples indicate a shoulder, in n-decane→TCB the samples eluted without indication of a shoulder. In addition to the influence of different solvents on the samples elution behavior, the response of the employed detector, an evaporative light scattering detector (ELSD), was investigated. Its response was found to depend pronounced lyon the nature of the used solvents. Overall, the solvent pair 1-decanol→TCB appears to be the optimal compromise between the considered parameters and thus the best choice for HPLC of ethylene/1-octenecopolymers

Decolonization potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Abstract Background Long-term use of indwelling urethral catheters is associated with high risk of urinary tract infection (UTI) and blockage, which may in turn cause significant morbidity and reduce the life of the catheter. A 0.02% polyhexanide irrigation solution has been developed for routine mechanical rinsing together with bacterial decolonization of suprapubic and indwelling urethral catheters. Methods Using a practice-like in vitro assay and standard silicon catheters, artificially contaminated with clinically relevant bacteria, experiments were carried out to evaluate the bacterial decolonization potential of polyhexanide vs. 1) no intervention (standard approach) and 2) irrigation with a saline (NaCl 0.9%) solution. Swabbing and irrigation was used to extract the bacteria. Results Irrigation with polyhexanide reduced the microbial population vs. the control catheters by a factor of 1.64 log10 (swab extraction) and by a factor of 2.56 log10 (membrane filtration). The difference in mean microbial counts between the two groups (0.90) was statistically significant in favor of polyhexanide when the liquid extraction method was used (p = 0.034). The difference between the two groups using the swab extraction method did not reach statistical significance. Conclusions The saline and polyhexanide solutions are able to reduce bacterial load of catheters, which shows a combined mechanical and antimicrobial effect. Further research is required to evaluate the long-term tolerability and efficacy of polyhexanide in clinical practice