Recent Advances in Gas Chromatography

Gas chromatography is one of the most used analytical techniques in the industry. It is a powerful tool with a wide range of applications. This book presents recent advances in gas chromatography, multidimensional gas chromatography, and gas chromatography mass spectrometry. It also discusses inverse gas chromatography. The main focus is the use of gas chromatography techniques to analyze petroleum fluids, biomass, and ionic liquids in medical and petrochemical industries

Metaheuristic based Peer Rewiring for Semantic Overlay Networks

A Peer-to-Peer (P2P) platform is considered for collaborative Information Retrieval (IR). Each peer hosts a collection of text documents with subjects related to its owner's interests. Without a global indexing mechanism, peers locally index their documents, and provide the service to answer queries. A decentralized protocol is designed, enabling the peers to collaboratively forward queries from the initiator to the peers with relevant documents. Semantic Overlay Network (SON) is one of the state-of-the-art solutions, where peers with semantically similar resources are clustered. IR can then be efficiently performed by forwarding queries to the relevant peer clusters in an informed way. SONs are built and maintained mainly via peer rewiring. Specifically, each peer periodically sends walkers to its neighborhood. The walkers walk along peer connections, aiming at discovering more similar peers to replace less similar neighbors of its initiator. The P2P network hence gradually evolves from a random overlay network to a SON. Random and greedy walk can be applied individually or integrated in peer rewiring as a constant strategy during the progress of network evolution. However, the evolution of the network topology may affect their performance. For example, when peers are randomly connected with each other, random walk performs better than greedy walk for exploring similar peers. But as peer clusters gradually emerge in the network, a walker can explore more similar peers by following a greedy strategy. This thesis proposes an evolving walking strategy based on Simulated Annealing (SA), which evolves from a random walk to a greedy walk along the progress of network evolution. According to the simulation results, SA-based strategy outperforms current approaches, both in the efficiency to build a SON and the effectiveness of the subsequent IR. This thesis contains several advancements with respect to the state-of-the-art in this field. First of all, we identify a generic peer rewiring pattern and formalize it as a three-step procedure. Our technique provides a consistent framework for peer rewiring, while allowing enough flexibility for the users/designers to specify its properties. Secondly, we formalize SON construction as a combinatorial optimization problem, with peer rewiring as its decentralized local search solution. Based on this model, we propose a novel SA-based approach to peer rewiring. Our approach is validated via an extensive experimental study on the effect of network rewiring on (i) SON building and (ii) IR in SONs

Smart and Functional Interfaces for Sensitive SPR Biosensing Towards Biomedical Applications

The aim of this thesis is to develop Surface Plasmon Resonance (SPR) methods that improve biosensing performance, in particular the sensitivity and selectivity of the analysis and their adaptation for biomedical applications to samples with complex background. This is of significant importance in translating the biosensor technologies to deliver the same results as the conventional methods but in a more accessible, efficient, and economical manner. The first study exploited SPR as a DNA biosensor for the detection of Malaria Plasmodium falciparum parasite with the hybridization chain reaction (HCR), which resulted in the formation of self-assembled target DNA nanostructures for signal enhancement. The sensitivity was further improved by using gold nanoparticles (AuNPs) for additional signal amplification. Tests with human blood plasma indicated the results were comparable to analyses in buffer, despite noticeable non-specific binding from the plasma. The concern of non-specific binding was systematically investigated in the second study where an antifouling surface consists of supported lipid bilayer membranes (SLBs) and protein A was developed for detection of trace amount of proteins in undiluted human serum. Specifically, cholera toxin (CT) spiked into the serum was used as the target, and advanced interface was further extended to immunosensing of immunoglobulin G (IgG). In the third study, SPR biosensor was employed in combination of bright field microscopy to characterize cellular apoptosis. HeLa cells undergoing apoptosis induced by hydrogen peroxide (H2O2) were monitored by SPR and the signals were compared to microscopic analysis of the morphological changes. SPR study revealed a decreased signal as cell confluency decreases, with the rates increasing as H2O2 concentration increases. An abnormality was found at high concentrations when both apoptosis and necrosis were induced. A mathematical model was proposed to explain SPR response where a non- uniform adsorbed layer was partially responsible. The significance of this thesis is that a number of high performing biosensing approaches have been developed and demonstrated. In addition to the advantages of SPR (e.g. label-free, real-time biomolecules binding, and portability), these methods have paved the way towards realizing effective sensing in biomedical research, especially in the early detection of infectious diseases and in the treatment of cancers

Operational Business-IT Alignment in Healthcare: Theoretical Foundation and Empirical Evidence

This thesis examines IT-related change in healthcare. Building on and extending prior research on operational business-IT alignment, new insights are derived that enable practitioners to align IT and medical reality to realize expected potentials of health IT. The results posit that strong social capital mitigates the challenges that come with structurally decoupled organizations and facilitates identification and implementation of necessary IT-related change in hospitals. Likewise, shared understanding about how health IT will affect and is affected by socio-organizational complementarities is found to be a critical requirement for effective change processes. Strong linkages between IT and medical professionals as well as sufficient shared understanding enables effective change processes. These processes are characterized by reciprocal adaptations to HIS and other elements of interrelated organizational activity systems, in which IT is embedded in. The empirical results demonstrate that iterative resolution of contradictions and mitigation of tensions within and between activity systems increases the efficiency of IT and leads to sustained alignment. Overall, this dissertation extends prior theories on alignment, helps scholars understand and account for the unique and complex characteristics of the healthcare domain and offers actionable guidance for practice.Diese Dissertation untersucht IT-bezogene Veränderungsprozesse in Krankenhäusern. Aufbauend auf dem Stand der Forschung zum operativen Business-IT Alignment erarbeitet diese Dissertation neue Erkenntnisse, die es Praktikern ermöglichen, IT und medizinische Realität bestmöglich aufeinander abzustimmen und damit den Wertbeitrag der IT in dieser Domäne zu steigern. Die empirischen Ergebnisse zeigen, dass starkes Sozialkapital die Herausforderungen strukturell entkoppelter Organisationen ausgleicht und die Identifikation und Realisierung notwendiger IT-bezogener Veränderungen in Krankenhäusern erleichtert. Ebenso ist ein gemeinsames Verständnis der Beteiligten darüber, wie sich die Gesundheits-IT auf die komplementären sozio-organisatorischen Charakteristika auswirkt und von diesen beeinflusst wird, eine entscheidende Voraussetzung für effektive Veränderungsprozesse. Enge Verbindungen zwischen IT- und Medizinern sowie ein ausreichendes gemeinsames Verständnis begünstigen effektive IT-bezogene Veränderungsprozesse. Diese Prozesse sind gekennzeichnet durch wechselseitige Anpassungen an der IT und anderer Elemente zusammenhängender organisatorischer Tätigkeitssysteme, in welche die IT eingebettet ist. Die empirischen Ergebnisse zeigen, dass die iterative Lösung von Widersprüchen und der Abbau von Spannungen innerhalb und zwischen Aktivitätssystemen die Effizienz der IT steigert und zu einer nachhaltigen Business-IT Alignment führt. Insgesamt erweitert diese Dissertation das theoretische Wissen zu operativem Business-IT Alignment und verbessert das Verständnis über die Charakteristika und Komplexitäten der Domäne Krankenhaus und bietet praktische Hilfestellungen zur Gestaltung IT-bezogener Veränderungsprozesse

Phthalates mixtures in bottled water in Iran: human health risk assessment using direct and indirect exposure assessment

Phthalates are diesters of phthalic acid that are widely used in industry and personal care products resulting in exposure via ingestion, inhalation and dermal routes. There is an interest in the safety evaluation of phthalate exposure because these compounds are ubiquitous environmental contaminants with endocrine-disrupting properties, suspected to interfere with developmental androgen action, possibly leading to adverse effects on reproductive function. Toxicological properties of phthalates, the presence of phthalates in polyethylene terephthalate (PET) bottles as impurities, the high and regular consumption of bottled water, and the uncertainty about the impact of storage conditions of PET bottled water on migration of phthalates into the water, initiated the interest in their presence in bottled water and the accompanying risk assessment. In this study, common Iranian brands of bottled water were screened for phthalates. The effect of storage temperature on selected target chemical concentrations was investigated. A toxicological risk assessment was conducted to determine the potential health risks associated with the consumption of the bottled water. Along with indirect exposure assessment, a human biomonitoring approach was applied to facilitate better human exposure assessment of individual phthalates and their mixtures providing important information for identifying exposure sources and the contribution of intake from bottled water to the total daily intake. Chapter 1 of the thesis presents an introduction to the topic, the toxicological properties of phthalates, risk assessment strategies and the regulatory status of phthalates. Chapter 2 of the thesis describes the development of a method to extract phthalates from bottled water by applying surface-functionalized magnetic particles (MPs) as the adsorbent used in Magnetic Solid-Phase Extraction (MSPE). Based on the results obtained, it was concluded that the MSPE-GC-MS method developed provides a new method for the determination of phthalates in water samples. To extend the work to real samples chapter 3 presents the occurrence and concentrations of common phthalates (dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), and diethylhexyl phthalate (DEHP) ) in PET bottled water locally produced in the Iranian market and stored under various common storage conditions. According to the results obtained, an increase in temperature and/or in the duration of storage increases phthalate migration. The highest concentrations of all phthalates were observed when bottled water samples were kept at 40 °C for 45 days. DEHP in bottled water was the most abundant phthalate under all storage conditions, although the observed level of DEHP in the worst-case scenario (40 °C for 45 days) was still much lower than the DEHP maximum concentration limit (MCL) in bottled water (MCL= 6 µg/L) set by the U.S. Food and Drug Administration (U.S. FDA). When comparing the concentrations of DBP, BBP and DEHP with initial levels in the bottled water, the results demonstrate that the release of phthalates was not substantial under all storage conditions, and especially minimal at low temperatures ( In chapter 4, concentrations of diethyl phthalate (DEP) were measured in bottled water kept under various storage conditions, similar as those used in chapter 3 for DEHP, DBP and BBP, and the resulting risks of consumption of this water for children but also for other age groups were evaluated. The results indicate that storage duration and storage temperature also influence the release of DEP from PET bottles into water. In comparison to the initial level of DEP in bottled water samples, the migration of DEP appeared not considerable under most storage conditions, especially at low temperatures ( children > lactating women > teenagers > adults > pregnant women. However, for all age groups, none of the individuals exceeds existing intake limit values for DEP. Due to the anti-androgenic activity of some phthalates, in chapter 5 the cumulative health risks in pregnant and lactating women posed by combined exposure to BBP, DBP, and DEHP via consumption of bottled water was estimated. To this end, hazard quotient (HQ) values, representing the margin between health based guidance values (EPA RfD values) and estimated exposures, and hazard index (HI) values, representing the sum of HQ values of individual phthalates, were determined. The results of the study showed that the HQ values for individual phthalate intake via bottled water consumption in pregnant and lactating women were much lower than 1, and cumulative risk assessment for combined phthalate exposure demonstrated that the HIs for anti-androgenic effects were also lower than 1 which implies that adverse effects are unlikely to occur. In chapter 6 of the thesis a systematic review method was used to investigate whether the phthalate exposure would be a factor contributing to the development of autism spectrum disorders (ASD). The results of this systematic review revealed that only a limited number of studies has addressed phthalates in relation to autism. A total of five studies met the inclusion criteria and were included in the review. Of the 5 studies, two studies were cohort studies both from the U.S.A. and three were case-control studies conducted in the U.S.A., Italy and Turkey. Because of the heterogeneity in the type of included studies, different methods of assessing exposure to phthalates and the use of different statistics for summarizing the results, a meta-analysis could not be performed to combine the results of included studies. The review showed equivocal evidence for a possible connection between exposure to phthalates and ASD. Further comprehensive research is needed with appropriate attention to exposure assessment and relevant pre and post-natal confounders. In the next step we set our goal to get better insight in the total phthalate exposure of Iranian children, and to assess the proportion of phthalate intake from bottled water to the total daily intake. This was done using biomonitoring based exposure assessment. Chapter 7 of the thesis shows the data on the levels of phthalate metabolites in the spot urine samples of children and adolescents. We applied a calculation model based on the creatinine-adjusted urinary metabolite concentrations to obtain the EDIs for DEHP, DBP and BBP. The EDI values thus obtained were compared to available health-based guidance values (RfD and TDI values based on anti-androgenic effects). Assuming additive effects, the cumulative risk for combined exposure were estimated for three phthalates based on anti-androgenicity as the critical effect. The results from the risk assessment suggest that Iranian children and adolescents are exposed to low levels of a mixture of these phthalates. Risk assessment indicates that not only the exposure to the single phthalates, but also the combined exposure would not raise a safety concern. However, people typically come into contact with several chemicals with anti-androgenic properties in addition to the investigated phthalates in this study, which may also contribute to combined anti-androgenic effects. This indicates that a risk assessment of combined exposure including other anti-androgenic chemicals would be required to determine whether combined exposure to anti-androgenic chemicals is below acceptable levels. Comparison of the exposure values obtained to those obtained based on indirect estimates in earlier chapters of the thesis, revealed that bottled water provides only a limited contribution to total daily phthalates exposure in Iran. Chapter 8 presents a discussion of the results obtained and also presents some perspectives for future research and risk management of exposure to phthalates in Iran.</p

The case of the new Tagus bridge controversy

Tese de doutoramento em Engenharia do Ambiente, especialidade em Sistemas SociaisEste trabalho foca-se no uso da informação em processos de decisão pública em contextos multi-actores, multi-objectivos, e sem resposta única. Recorre a um caso de estudo sobre o processo de decisão da localização da nova travessia do Tejo. Muitos viram a escolha governamental como sendo "meramente política", considerando que a informaqb não foi usada na decisão. Talvez seja verdade, mas houve informação substancial e as pessoas usaram-na, em especial depois da controvérsia gerada pela decisão. Uma solução inesperada, que veio a ganhar o apoio de planeadores e ambientalistas preocupados com sustentabilidade, emergiu de um processo interactivo. A pacífica solução inicial entre duas alternativas tornou-se uma decisão controversa com o aparecimento da terceira opção. É então que o debate se desloca da localização da travessia para o modelo de desenvolvimento desejado para a área metropolitana. A informação foi amplamente usada e transformada no processo, e informação nova foi gerada em fóruns. Apesar da falta de coordenação horizontal, o modelo de desenvolvimento desejado para a área metropolitana e a forte rede de relações (networking) desempenharam um papel integrador. A informação assumiu um papel importante, sendo traduzida em imagens de grande significado. 0 uso da informação conduz à acção. Associações de interesse emergiram e as existentes modificaram estratégias e modos de actuação. Aprenderam a trabalhar em conjunto partilhando recursos, a lidar formalmente com instâncias mais elevadas, e a funcionar em contextos alargados. Foi identificada a necessidade de criar novas instituições e de reestruturar as já existentes para um melhor funcionamento dos processos de decisão pública

McNair Scholars Research Journal Volume XI

https://commons.stmarytx.edu/msrj/1010/thumbnail.jp