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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Extrakční detoxikace citlivých komponent / Extraction Detoxification of Sensitive Components

Andrle, Marek January 2014 (has links)
Solvent extraction is one of the methods available for the decontamination of sensitive equipments that are contaminated with chemical warfare agents. The efficiency of extraction method have been verified on the samples, (steel or rubber) that have been contaminated with drops of mustard gas. These samples have been inserted into the extraction flow cell through which solvent (ethoxynonafluorobutane - HFE-7200) flowed. The solvent was sampled in the time intervals. These samples of solvent were analysed for the concentration of mustard gas. Process of extraction was monitored for the three operational factors (the solvent flow rate, temperature and the ultrasound power) and for three different situations (dissolution of drops of mustard gas, mustard gas desorption from the structure of the sample and dissolve drops of mustard gas with the subsequent desorption from the sample). The development of the decontamination process in time was found to consist of two stages. In the first stage the rapid dissolution of the liquid part of mustard gas in a solvent and in the second phase was such as mustard desorption from the structure of the sample and this phase was considerably slower. Extraction is to accelerate increasing the value of the flow of the solvent, the temperature and the performance of the ultrasound. These operational fac-tors have a significant impact on the thickness of the laminar layer of solvent, the solvent replacement coefficient in a cell, diffusion parameters in the process, the viscosity, the solubility of mustard gas in a solvent and the maximum achievable concentration of mustard gas in the rubber sample. The values of adjustable parameters was obtained by mathematical analysis of mathematical model. The progress of extraction under different operational conditions can be predicted by these parameters. The effect of solvents and ultrasound was experimentally verified for selected equipments of computing and communication technology. The possibility of separation of chemical warfare agents from the solvent was verified too.
352

Synthesis of new nanomaterials based on porphyrins and graphene for elaboration of sensitive and selective DNA biosensors / Synthèse de nouveaux nanomatériaux basés sur des porphyrines et du graphène pour l'élaboration de biocapteurs d'ADN sensibles et sélectifs

Wang, Yaqiong 09 October 2017 (has links)
La conception et le développement de biocapteurs pour la détection directe de biomarqueurs dans un échantillon de fluide biologique constituent un véritable défi dans la recherche pour leur application dans le système de point de soins en diagnostic. Mon projet est axé sur l'élaboration d'une nouvelle plateforme de décomposition biologique composée de graphène qui présente une surface électroactive et spécifique élevée permettant de greffer de nombreux biomolécules avec des métalloporphyrines en tant que nouveau marqueur redox pour suivre le processus de reconnaissance biologique obtenu dans le cas d'un capteur d'ADN. Le concept sera de démontrer que les métalloporphyrines où le potentiel d'oxydo-réduction pourrait être contrôlé par la nature des ions métalliques pourraient être appliquées dans une plate-forme de biocapteurs électrochimique multidétection. L'association de la métalloporphyrine avec le graphène offrira de nombreux avantages, comme la promotion de la réaction de transfert d'électrons et ayant une grande surface pour l'immobilisation des protéines. La détection de la cible présente sera réalisée suite à l'activité redox des métalloporphyrines greffées à la surface. Nous avons déjà synthétisé différentes métalloporphyrines modifiées et caractérisées par des techniques habituelles de spectrométrie telles que la RMN, les UV et la MS. Le biocapteur d'ADN a été construit par le composite de graphène et métalloporphyrine et sonde d'ADN comme biorécepteur suivant l'approche d'attachement covalent et l'optimisation de la construction de biocapteur pour améliorer la stabilité et la reproductibilité. Et nous avons déjà fait une détection de l'ADN cible par diverses méthodes électrochimiques, y compris la voltamétrie cyclique, la voltampérométrie à onde carrée et la spectroscopie d'impédance. Cette stratégie a été réalisée d'abord avec la porphyrine Mn insérée puis généralisée à divers complexes métalliques pour une approche multidétection. Parallèlement, les nanomatériaux hybrides combinant les caractéristiques du graphène (haute conductivité et grande surface spécifique) et des porphyrines (propriétés physiques et chimiques et capacité de transfert d'électrons), tels que la tétraphénylporphyrine portant un et quatre groupes carboxyliques nommés H₂TPP-nCP (n = 1, 4) et la tétraphénylporphyrine incorporant du manganèse (III) (MnTPP-1CP) ont été synthétisés avec succès. L'interaction entre H₂TPP-nCP (n = 1, 4) et l'oxyde de graphène chimiquement réduit (CRGO) a été étudiée dans mon travail de thèse. Pour étudier les propriétés caractéristiques des nanomatériaux préparés, la microscopie électronique à balayage (MEB), la microscopie à force atomique (AFM), les spectres UV-visible, les spectres infrarouges à transformée de Fourier (FT-IR) et les spectres de photoélectrons X. Afin d'éliminer l'absorption non spécifique, la modification de l'électrode par le PEA a également été appliquée et obtenir une excellente application pour la détection de la cible d'ADN. / The design and development of biosensors for direct detection of biomarkers in biological fluid sample is real challenge in research for their application in point of care system in diagnostic. My project is focus on the elaboration of a new platform for biological detaction composed of graphene which exhibits a high electroactive and specific surface suitable for grafting numerous biomoleculer with metalloporphyrins as a novel redox marker for following biological recognition process obtained in the case of DNA sensor. The concept will be to demonstrate that the metaloporphyrines where there redox potential could be controlled by the nature of metal ions could be applied in multidetection electrochemical biosensor platform. The association of metalloporphyrin with graphene will offer numerous advantages, as promoting electron transfer reaction and having a large surface for protein immobilization. The detection of target present will be performed following redox activity of the metalloporphyrins grafted on the surface. We have already synthesized various modified metalloporphyrins and characterizatized by usual spectrometry techniques such as NMR, UV and MS. The DNA biosensor has been constructed by the composite of graphene and metalloporphyrin and DNA probe as bioreceptor following covalent attachment approach and optimization of the biosensor construction for improving stability and reproducibility. And we have already done some detection of DNA Target by various electrochemical methods including cyclic voltammetry, square wave voltammetry and impedance spectroscopy. This strategy was performed firstly with on Mn inserted porphyrin and then generalized to various metal complex for multidetection approach. Meanwhile, the hybrid nanomaterials which combined the features of both graphene (high conductivity and large specific surface area) and porphyrins (physical and chemical properties and electron transfer ability), such as tetraphenylporphyrin bearing one and four carboxylic group named H₂TPP-nCP(n=1, 4) and tetraphenylporphyrin incorporating manganese (III) (MnTPP-1CP) were successfully synthesized. The interaction modes between H₂TPP-nCP(n=1, 4) and chemically reduced graphene oxide (CRGO) was studied in my thesis work. To investigate the characteristic properties of as-prepared nanomaterials, scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible spectra, Fourier Transform infrared spectra (FT-IR), X-ray photoelectron spectra (XPS). In order to eliminate the non-specific absorption, the modification of the electrode by monolayer PEA was also applied and obtain excellent application for the detection of DNA target.
353

Performance Analysis of the Preemption Mechanism in TSN

Murselović, Lejla January 2020 (has links)
Ethernet-based real-time network communication technologies are nowadays a promising communication technology for industrial applications. It offers high bandwidth, scalability and performance compared to the existing real-time networks. Time-Sensitive Networking is an enhancement for the existing Ethernet standards thus offers compatibility, cost efficiency and simplified infrastructure, like previous prioritization and bridging standards. Time-Sensitive Networking is suitable for networks with both time-critical and non-time-critical traffic. The timing requirements of time-critical traffic are undisturbed by the less-critical traffic due to TSN features like the Time-Aware Scheduler. It is a time-triggered scheduling mechanism that guarantees the fulfilment of temporal requirements of highly time-critical traffic. Features like the Credit-Based Shapers and preemption result in a more efficiently utilized network. This thesis focuses on the effects that the preemption mechanism has on network performance. Simulation-based performance analysis of a singe-node and singe-egress port model for different configuration patterns is conducted. The simulation tool used is a custom developed simulator called TSNS. The configuration patterns include having multiple express traffic classes. In a single-egress port model, the most significant performance contributor is the response time and this is one of the simulation measurements obtained from the TSNS network simulator. The comparison between the results of these different network configurations, using realistic traffic patterns, provides a quantitative evaluation of the network performance when the network is configured in various ways, including multiple preemption scenarios.
354

"Att inte alltid orka" : En grundad teori om högkänslighet och moderskap

Larsson, Frida, Kainulainen, Maria January 2019 (has links)
Högkänslighet (HSP) är ett för vår tid relativt nytt begrepp som flera människor kommit att identifiera sig med. Intresseområdet för den här studien har varit högkänsliga mödrar och med hjälp av grundad teori som metodansats ämnade vi upptäcka högkänsliga mödrars huvudangelägenhet. Ämnet är aktuellt och knyter an till samhällets ökade behov av självkännedom och självförverkligande. Vår grundade teori belyser ett tidigare outforskat område inom vetenskapen vilket bidrar till en ökad förståelse och kunskap kring det högkänsliga moderskapet och vad det innebär för mödrarna själva. Tio intervjuer genomfördes med mödrar som identifierade sig själva som högkänsliga. Under studien formades en forskningsfråga som löd: hur gör högkänsliga mödrar för att orka vara närvarande i sina barns liv? Forskningsfrågan belyser mödrarnas huvudangelägenhet Att inte alltid orka. Studien resulterade i en grundad teori som beskriver hur mödrarna hanterar Att inte alltid orka genom kärnkategorin Anpassning och underkategorierna Avläsningsförmåga, Samhällelig kunskapslucka, Ökad självkännedom, Egentid och Ett annorlunda moderskap. Den grundade teori som genererats i den här studien har placerats inom ett teoretiskt ramverk bestående av narrativ teori för att ge en djupare förståelse inför de berättelser som mödrarna har delgett oss.
355

Studium systému oxidativní fosforylace u vzácných typů mitochondriálních onemocnění / Oxidative phosphorylation system in rare types of mitochondrial diseases

Zdobinský, Tomáš January 2019 (has links)
In their bioenergetic metabolism mammalian cells are primarily dependent on ATP production through the oxidative phosphorylation system (OXPHOS). Defects of OXPHOS function can lead to occurrence of mitochondrial disorders with different severity and diverse symptoms. Most severely affected are usually tissues with high energy demand which are also difficult to access for biochemical and other examinations. The aim of this thesis was mainly to characterize the effects of mutations in seven different genes (OPA1, DARS2, NDUFS8, NR2F1, HTRA2, MGME1, POLG) on bioenergetic metabolism and mitochondrial network structure of skin fibroblasts from eight different patients diagnosed with mitochondrial disorders. The main method used was measurement of oxygen uptake by permeabilized cells using highly sensitive polarography. Significant changes in fibroblast respiration of four patients were found. Changes in mitochondrial network morphology were found in two of those and two other patient cell lines compared to controls using fluorescent microscopy and different cultivating conditions. Skin fibroblasts are relatively easy to obtain and offer a number of benefits for both diagnostic and study purposes. The results of this work illustrate the possibilities of their use for validation of potential causal...
356

Get In Sync With TSN : A Study of Partially Synchronized TSN Networks

Johansson, Andreas Johansson January 2022 (has links)
Automotive and industrial embedded systems are increasingly dependent on real-time capabilities. TSN aims to offer flexibility of the traffic by providing Ethernet with hard and soft real-time capabilities which allows for integration with other protocols in legacy systems. TSN requires the network to be fully synchronized to achieve high performance. However, there are cases where legacy systems are not able to synchronize with TSN. These systems might nonetheless be able to synchronize with each other through their legacy synchronization mechanisms. In this thesis, we have investigated effects in terms of jitter and clock drift in endpoints by synchronizing them with each other and passing communication through an unsynchronized intermediary TSN switch. Our results revealed that with the introduction of TSN, jitter was reduced, while clock drift between endpoints and the TSN switch was introduced. The results show that negative clock drift leads to packets missing their scheduled TSN windows and positive drift leads to packets being dropped in the switch buffer queues. We proposed two solutions in order to manage the experienced clock drift. In one solution we statically changed the switch cycle, and in the other, we let the receiver node dynamically update the sending period in the sender node. In the static solution, the clock drift was reduced from negative eight microseconds per second to two nanoseconds per second. In the dynamic solution, a packet error rate of one per 100 seconds was reduced to zero errors in 19 hours.
357

Variability in Hydrogeochemical Characteristics in Regions with High Arsenic Groundwater at Matlab, Southeastern Bangladesh.

Rahman, Md Moklesur January 2009 (has links)
Elevated levels of geogenic arsenic (As) in groundwater are regarded as the most formidable environmental crisis in the contemporary world and an estimated 30-70 million people in Bangladesh are at risk. Many of the provided options for mitigation have not been well accepted. In recent years, local drillers have been targeting As-low groundwater on the basis of the color of the sediments. A correlation between the color characteristics of the sediments and the groundwater redox conditions and thereby the risk for As mobilization has been established. It is possible to assess the relative possibility of occurrence of high As concentrations in groundwater if the color characteristics of the sediments are known. One main objective of the present study is to validate if targeting As-safe groundwater is a sustainable mitigation strategy. This has been done through monitoring groundwater from tube-wells installed in sediments with different color, depth and redox characteristics. Samples were collected yearly from a set of 17 tube-wells for the period of 2004 to 2008 in Matlab, Bangladesh. The wells were grouped into oxidized and reduced/non-oxidized wells. All of these wells tap water within a depth of 85 m from the surface. Major cations and trace elements including As were analysed by high resolution ICP-OES; and anions were measured by ion chromatography. Groundwater chemistry of the water abstracted from different sediments revealed that no major change had occurred over the period of 5 years. In reduced wells, concentration of major cations and anions varied by <10% over time, and no significant variation was observed in redox sensitive elements, such as Fe, Mn and S. There were some minor variations in the As concentrations in the wells. In the oxidized wells, except well 58, major cations, anions and redox sensitive elements varied by <5%, while the As concentrations were found quite low and stable (<5.2 μg/L). Time series trends thus suggest that the change in groundwater chemistry is insignificant over the period of 5 years from 2004 to 2008. Low As concentrations in the tubewells installed in the oxidized brownish sediments thus validate the mitigation strategy corresponding to the conceptual understanding of the groundwater system in Matlab in southeastern Bangladesh.
358

Risk-Prone and Risk-Averse Foraging Strategies Enable Niche Partitioning by Two Diurnal Orb-Weaving Spider Species

Long, Mitchell D 01 May 2022 (has links)
Niche partitioning is a major component in understanding community ecology and how ecologically similar species coexist. Temporal and spatial partitioning and differences in foraging strategy, including sensitivity to risk (variance), likely contribute to partitioning as well. Here, we approach this partitioning with fine resolution to investigate differences in overall strategy between two species of diurnal, orb-weaving spiders, Verrucosa arenata and Micrathena gracilis (Araneae: Araneidae), that share similar spatial positioning, temporal foraging window, and prey. Through field observation, we found that V. arenata individuals appear to increase spatial and temporal sampling to compensate for an overall risk-prone strategy that depends on the interception and active capture of rare, large prey. Conversely, M. gracilis individuals employ a risk-averse strategy relying on passive capture of small but abundant prey consumed alongside the orb. We have thus identified how differing risk-sensitive foraging strategies may contribute to niche partitioning between otherwise similar species.
359

To Force a Bug : Extending Hybrid Fuzzing

Näslund, Johan, Nero, Henrik January 2020 (has links)
One of the more promising solutions for automated binary testing today is hybrid fuzzing, a combination of the two acknowledged approaches, fuzzing and symbolic execution, for detecting errors in code. Hybrid fuzzing is one of the pioneering works coming from the authors of Angr and Driller, opening up for the possibility for more specialized tools such as QSYM to come forth. These hybrid fuzzers are coverage guided, meaning they measure their success in how much code they have covered. This is a typical approach but, as with many, it is not flawless. Just because a region of code has been covered does not mean it has been fully tested. Some flaws depend on the context in which the code is being executed, such as double-free vulnerabilities. Even if the free routine has been invoked twice, it does not mean that a double-free bug has occurred. To cause such a vulnerability, one has to free the same memory chunk twice (without it being reallocated between the two invocations to free). In this research, we will extend one of the current state-of-the-art hybrid fuzzers, QSYM, which is an open source project. We do this extension, adding double-free detection, in a tool we call QSIMP. We will then investigate our hypothesis, stating that it is possible to implement such functionality without losing so much performance that it would make the tool impractical. To test our hypothesis we have designed two experiments. One experiment tests the ability of our tool to find double-free bugs (the type of context-sensitive bug that we have chosen to test with). In our second experiment, we explore the scalability of the tool when this functionality is executed. Our experiments showed that we were able to implement context-sensitive bug detection within QSYM. We can find most double-free vulnerabilities we have tested it on, although not all, because of some optimizations that we were unable to build past. This has been done with small effects on scalability according to our tests. Our tool can find the same bugs that the original QSYM while adding functionality to find double-free vulnerabilities. / En av de mer lovande lösningarna för automatiserad binärtestning är i dagsläget hybrid fuzzing, en kombination av två vedertagna tillvägagångssätt, fuzzing och symbolisk exekvering. Forskarna som utvecklade Angr och Driller anses ofta vara några av de första med att testa denna approach. Detta har i sin tur öppnat upp för fler mer specialiserade verktyg som QSYM. Dessa hybrid fuzzers mäter oftast sin framgång i hänsyn till hur mycket kod som nås under testningen. Detta är ett typiskt tillvägagångssätt, men som med många metoder är det inte felfri. Kod som har exekverats, utan att en bugg utlösts, är inte nödvändigtvis felfri. Vissa buggar beror på vilken kontext maskininstruktioner exekveras i -- ett exempel är double-free sårbarheter. Att minne har frigjorts flera gånger betyder inte ovillkorligen att en double-free sårbarhet har uppstått. För att en sådan sårbarhet ska uppstå måste samma minne frigöras flera gånger (utan att detta minne omallokerats mellan anropen till free). I detta projekt breddar vi en av de främsta hybrid fuzzers, QSYM, ett projekt med öppen källkod. Det vi tillför är detektering av double-free i ett verktyg vi kallar QSIMP. Vi undersöker sedan vår hypotes, som säger att det är möjligt att implementera sådan funktionalitet utan att förlora så mycket prestanda att det gör verktyget opraktiskt. För att bepröva hypotesen har vi designat två experiment. Ett experiment testar verktygets förmåga att detektera double-free sårbarheter (den sortens kontext-känsliga sårbarheter vi har valt att fokusera på). I det andra experimentet utforskar vi huruvida verktyget är skalbart då den nya funktionaliteten körs. Våra experiment visar att vi har möjliggjort detektering av kontext-känsliga buggar genom vidareutveckling av verktyget QSYM. QSIMP hittar double-free buggar, dock inte alla, på grund av optimiseringar som vi ej har lyckats arbeta runt. Detta har gjorts utan större effekter på skalbarheten av verktyget enligt resultaten från våra experiment. Vårt verktyg hittar samma buggar som orignal verktyget QSYM, samtidigt som vi tillägger funktionalitet för att hitta double-free sårbarheter.
360

Temperature-Sensitive Translation of MS2 Bacteriophage RNA

Armstrong-Major, Jackie, Champney, W. Scott 20 February 1985 (has links)
A comparison was made of bacteriophage MS2 RNA translation in infected Escherichia coli cells and in a defined cell-free system. A number of temperature-sensitive mutants were used as hosts for viral RNA translation at permissive and restrictive temperatures. The amount of viral coat protein synthesis was determined after gel electrophoresis of proteins from the cell lysates. These results were compared to those obtained with cell-free translation assays conducted with ribosomes isolated from the same mutants. Compared with control cells, a reduced activity in vivo and in vitro was found for each mutant examined at elevated temperatures. A good correlation between the two types of translational assays was observed. These findings are discussed in terms of the translational defects known to be a characteristic of some of these mutant strains.

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