<p>Preferential processing favouring threatening information has received increased attention because cognitive formulations have placed increased emphasis on its role as a key cognitive factor underlying vulnerability to and maintenance of anxiety disorders. The present dissertation comprises four empirical studies within the area of preferential processing. Two different outcome measures were used to index preferential processing of threat-related information: Skin conductance responses (SCRs) were used in Studies I, II, and III. The emotional Stroop task was used in Study IV. The main focus has been on preferential processing of threat-related information that occurs outside awareness, thus <i>preferential preattentive processing</i>. Study I investigated the role of traumatic combat experience with regard to preferential processing among UN soldiers following a presentation of threat-related pictures. Results indicated that soldiers with combat experience consistently reacted with lower SCRs compared to soldiers without combat experience. One issue addressed in the individual studies was the association between preferential preattentive processing and trait anxiety. Studies II, III, and IV showed that elevated levels of trait anxiety promote preferential preattentive processing of negatively valenced information, whereas elevated levels of social desirability generally prevent preferential preattentive processing of negatively valenced information. Study II highlighted the importance of including the social desirability factor when studying effects of trait anxiety on preferential processing. In addition, Studies III and IV explored the relationship between preferential processing and emotional vulnerability. The main findings support the notion of preferential preattentive processing of threat representing an underlying predisposition to heightened emotional vulnerability in response to stressful events.</p>

Preferential processing favouring threatening information has received increased attention because cognitive formulations have placed increased emphasis on its role as a key cognitive factor underlying vulnerability to and maintenance of anxiety disorders. The present dissertation comprises four empirical studies within the area of preferential processing. Two different outcome measures were used to index preferential processing of threat-related information: Skin conductance responses (SCRs) were used in Studies I, II, and III. The emotional Stroop task was used in Study IV. The main focus has been on preferential processing of threat-related information that occurs outside awareness, thus preferential preattentive processing. Study I investigated the role of traumatic combat experience with regard to preferential processing among UN soldiers following a presentation of threat-related pictures. Results indicated that soldiers with combat experience consistently reacted with lower SCRs compared to soldiers without combat experience. One issue addressed in the individual studies was the association between preferential preattentive processing and trait anxiety. Studies II, III, and IV showed that elevated levels of trait anxiety promote preferential preattentive processing of negatively valenced information, whereas elevated levels of social desirability generally prevent preferential preattentive processing of negatively valenced information. Study II highlighted the importance of including the social desirability factor when studying effects of trait anxiety on preferential processing. In addition, Studies III and IV explored the relationship between preferential processing and emotional vulnerability. The main findings support the notion of preferential preattentive processing of threat representing an underlying predisposition to heightened emotional vulnerability in response to stressful events.

Waste appears to be a low-cost fuel compared to biofuel. This Masters thesis was conducted for Vattenfall Utveckling AB and deals with how waste in the fuel affects the performance of a SCR-catalyst. Different mechanisms of deactivation were surveyed, focusing on the poisoning mechanism. A literature study was carried out, which was used as a reference when analysing the results. Small samples (9x2x2 cm, 64 pieces) cut out from a full-scale unused honeycomb catalyst were exposed up to 1500h in two different combustion plants, Johannes in Gävle (co-combustion) and Högdalen in Stockholm (waste-combustion). The activity was measured mainly at 300°C but also at 250, 350, 375 and 400°C. SEM/EDS-analysis (about 20 samples) and wet chemical analysis (about 20 samples + 2 fly-ash samples) was then performed on the samples. A sample from each boiler was sent for BETanalysis. The results from the analysis above were compared to earlier studies conducted on bio-fuel plants in order to investigate what might have deactivated the catalyst samples. Also a small multivariate data analysis (MVDA) was performed. The results from the study show that the catalyst samples exposed in Johannes have slightly less than 60 % of the activity left after 1500h, for Högdalen only 20 % of the activity remains after 1500h. For Johannes when only firing biofuel the corresponding figure is 74 % and in a coal-fired boiler just over 80 % of the activity remains after 1500h. For catalysts with a higher initial activity the deactivation rate is slower. The main mechanism of deactivation is poisoning from alkali metals. In Johannes the poisoning is mainly due to water-soluble potassium. In Högdalen water-soluble potassium, sodium and acid soluble lead causes the deactivation. Potassium stands for just over half of the poisoning effect, sodium just over 1/3 and lead for less than 1/6. SEM/EDS-analysis shows that the potassium content is about 3 times higher the first centimetre from the inlet, than the rest of the sample. The difference in potassiumconcentration between the surface and the walls of the catalyst is rather small. The concentration of lead on the other hand was found to be constant along the catalyst, but the concentration on the surface is much higher than in the walls. Erosion, sintering and plugging have not been studied in detail. Erosion tends to be a bigger problem in Johannes than in Högdalen, probably due to the texture of the fly ash. It does not seem to be any risk of sintering where the test-bench was exposed. For Johannes plugging was estimated to affect around 25 % of the channels in the samples after 1000h of exposure. Solely exposure for fly ash wasn’t found to affect the activity significantly. / Avfall framstår som ett billigt bränsle jämfört med biobränsle. Detta examensarbete utfördes åt Vattenfall Utveckling AB och studerar hur prestanda för katalysatorn i en SCR-anläggning (för NOx-rening) påverkas vid inblandning av avfall i bränslet. Olika deaktiveringsmekanismer kartlades, med en tyngdpunkt på mekanismen förgiftning. Även en litteraturstudie genomfördes, för att användas som referens vid resultatanalysen. Små provbitar (9x2x2 cm, 64 stycken) utsågade ur en fullskalig oanvänd honeycombkatalysator exponerades upp till 1500h i två anläggningar, Johannes i Gävle (sameldning) samt Högdalen i Stockholm (avfallseldning). Aktiviteten mättes, därefter gjordes SEM/EDS-analyser (cirka 20 prov) och våtkemiska analyser (cirka 20 prov + 2 stycken flygaska). Ett prov från varje panna skickades på BET-analys. Analyserna ovan jämfördes med tidigare studier utförda på biobränsleeldade anläggningar för att ta reda på vad som kan ha deaktiverat katalysatorerna. Även en mindre multivariat dataanalys (MVDA) utfördes. Resultat från studien är bland annat att katalysatorproven exponerade i Johannes har knappt 60 % av aktiviteten kvar efter 1500h, för Högdalen är motsvarande siffra runt 20 %. Det kan jämföras med 74 % för Johannes om bara biobränsle eldas och drygt 80 % för katalysatorer i en koleldad panna efter samma exponeringstid. Katalysatorer med en högre begynnelseaktivitet deaktiverades långsammare. Den huvudsakliga deaktiveringsmekanismen är alkaliförgiftning. I Johannes beror förgiftningen främst av vattenlösligt kalium. I Högdalen sker förgiftningen sannolikt av både vattenlösligt kalium och natrium, samt syralösligt bly. Av förgiftningen i Högdalen står kalium för lite drygt hälften, natrium för drygt 1/3 och blyet för resten. SEM/EDS-analyserna visade att kalium finns i cirka 3 gånger så hög koncentration den första centimetern från inloppet på proverna för att sedan bli ganska konstant. Det är ingen större skillnad i kaliumkoncentration på ytorna eller i väggarna. För bly är koncentrationen mer jämn i längdled, men i väggarna avsevärt lägre halter än på ytorna. Erosion, sintring och igensättning har inte studerats utförligt. Vad som kan sägas är att erosionen verkar vara ett större problem i Johannes än i Högdalen, troligen på grund av annan textur på flygaskan. Det verkar inte föreligga någon risk för sintring vid platsen för exponeringen. Igensättningen uppskattades i Johannes till 25 % av kanalerna i proverna efter 1000h exponering. Exponering för enbart flygaska i 500h påverkade inte aktiviteten signifikant.

The purpose of this work was to provide a better understanding of urea’s decomposition and byproduct formation in an SCR system on heavy trucks. In my experimental setup with TGA-DSC-FTIR (a combination of two thermal analysis methods and a method for gas phase detection), an FTIR method for urea in the gas phase was developed for the qualitative and quantitative determination of urea and its decomposition products. Chemicals such as urea, biuret, cyanuric acid and melamine of p.a. quality were used in this method development. Beforehand, there was no FTIR method available to detect these substances; hence, the aim of this work was to develop an FTIR method to understand the degradation chain of urea.  The combination of TGA and DSC was used for analysis of different samples, where urea, biuret, cyanuric acid and melamine in varying amounts have been weighted in for various experiments in order to study the temperature at which a phase transition or reaction occurs, i.e. the temperature at which substances begin to melt, vaporize, decompose and react. In combination with FTIR, information was obtained for the appearance of substances at various temperatures. With FTIR, we have been able to develop unique infrared spectra of substances and along with weight loss in TGA the calibration of different substances has been achieved. These calibrations have been combined together to develop an FTIR method, which has been used for detection of the substances in the ongoing study of the reaction pathways. In this study we also investigated the degradation chain of urea in the presence of metals. Austenitic and ferritic silencer materials with different surface roughness were analyzed to study whether the metals have a catalytic function or effect on the byproduct formation. Those experiments have shown that a higher amount of urea was decomposed in contact with metal surface, i.e. a larger amount of NH3 and HNCO was formed. Biuret studies in the presence of metals appeared to give a higher formation of urea over the rougher surfaces (a larger amount of biuret was decomposed over the rougher surfaces), while experiments with cyanuric acid revealed a higher HNCO formation over ferrite than over austenite, i.e. a larger amount of cyanuric acid was decomposed. By the chosen method, used in FTIR in combination with TGA-DSC, the following important reactions have been demonstrated:  Biuret decomposed to urea and HNCO; Urea decomposed into HNCO and NH3; formation of cyanuric acid from the decompositions of urea and biuret and finally decomposition of cyanuric acid into HNCO at a higher temperature.

Forskning visar att människor huvudsakligen återger starkt emotionellt laddade händelser väl. Information och detaljer runt omkring händelsen har dock visat sig vara betydligt svårare att rapportera, jämfört med centrala detaljer som är kritiska för den känslomässiga upplevelsen. Syftet med föreliggande studie var att undersöka effekter av emotionell arousal beträffande minne för central respektive perifer detaljinformation. Hypotesen var att negativt känsloladdad information påverkar minnet positivt beträffande centrala detaljer, men negativt för perifera detaljer. Två experiment utfördes, där kontrollgruppen i båda experimenten förevisades 15 neutrala färgbilder föreställande vardagliga situationer. Samma bildspel visades för experimentgruppen, förutom att den åttonde bilden var utbytt mot en arousal-väckande obehaglig bild. I experiment 1 testades undersökningsdeltagarnas minne av detaljer ifrån dessa bilder. I experiment 2 lades ett igenkänningstest till i ett försök att främja minne. Resultaten från båda experimenten var i linje med hypotesen då experimentgruppen mindes den centrala detaljen bättre än kontrollgruppen, och ytterst få undersökningsdeltagare kunde rapportera den perifera detaljen ifrån den arousal-väckande bilden. Studien visar att människor som bevittnat händelser av negativt känsloladdad karaktär inte kan förväntas rapportera en helhetsbild av händelsen, vilket är av yttersta vikt i vittnespsykologiska sammanhang.

Zugl.: Karlsruhe, Univ., Diss., 2007

University, Diss., 1993--Karlsruhe.

En raison des de l’augmentation de la pollution à l’échelle mondial du notamment aux gaz d'échappement des automobiles, de nouvelles réglementations d'émissions ont été mises en place depuis les années 1990. Ces règlementations ont conduit à une évolution des carburants traditionnels vers les biocarburants et à des systèmes de post-traitement des gaz d'échappement, notamment pour les moteurs diesel, de plus en plus sophistiqués. Ils comprennent à ce jour une série d'unités catalytiques, contenant un filtre à particules, un catalyseur d’oxydation pour traiter le monoxyde de carbone et les hydrocarbures et enfin un catalyseur pour réduire les oxydes d’azote. Dans ce travail de thèse, deux de ces systèmes catalytiques industriels ont été étudiés, les catalyseurs à l'oxydation diesel (DOC) et les catalyseurs de réduction catalytique sélective (SCR). Une attention particulière est accordée à leur performance en présence de composés métaux alcalins. En effet, les alcalins sont présent dans les biocarburants et lorsque le biodiesel est utilisé comme carburant de remplacement, ils vont donc être présents dans les gaz d’échappement et à priori dans les systèmes de post-traitement. / Due to global lean exhaust gas and new emission regulations, exhaust after-treatment systems of diesel engines are getting more and more sophisticated and comprise a series of catalytic units. In the present work, two of these catalytic systems were studied, Diesel Oxidation Catalysts (DOC) and Selective Catalytic Reduction (SCR) catalysts. Particular attention is paid to their performance in the presence of alkali compounds when bio-diesel is utilized as the alternative fuel.Firstly, this thesis focuses on the catalytic behavior of the Diesel Oxidation Catalyst using different aging characteristics of road mileage in order to improve the efficiency of an ammonia SCR system on an after-treatment line composed by a DOC + DPF + SCR. The studied catalyst is a commercial diesel oxidation catalyst (Pt/Pd/Al2O3) provided by Continental. Hydrothermal aging under different conditions on carrots of monolith were performed. Also studied in the monolith form over the commercial DOC, the influence of the addition of different alkali metal species (K and Na) on the commercial DOC through catalytic tests performed on this structured catalyst under multicomponent (C3H6 / CO / NO / NO2) co-feeding conditions was explored. Aiming at investigating the effects of the presence of different alkali metal species on the DOC at the level of active phase, homemade bimetallic DOC is prepared and then different alkali metal species incorporated. Finally, encouraged by the evident influence of alkali compounds on DOCs, their impacts on the downstream SCR catalysts are also studied in this thesis. The studied SCR catalyst is a commercial V2O5-based catalyst provided by UMICORE company.

Tougher environmental legislations are a driving force for development of aftertreatment technologies for truck and car exhaust gases. In particular, the emission requirements are high on nitrogen oxides (NOx) and particulate matter. Focus of this thesis work is to develop a component in the exhaust system, a NOx level reduction system. The currently used technology with urea evaporator has problem with formation of urea crystals due to delayed urea evaporation. Crystalline urea causes reduced exhaust flow and thus build up a pressure in the system that has negative impact on the performance of the engine. Feasibility study was done to understand function, advantage and disadvantages of current design and the need for a new design. The main task of this project was to investigate and propose a new design of the helix-rotary evaporator and to present it in the form of parametric model. Material selection needed for urea injection arrangement, 3D printed model for visualization of the concept and integration of the model to next generation aftertreatment system (NGA) are examples of sub-tasks that was performed to reach the main objective. Several generations of selected concept were developed in 3D design which later was 3D printed to visualize the ideas. The parametric 3D model was designed so that it later serves as input model for a later phase in the development project, where computational fluid dynamics is utilized. Parametric modelling is used to provide wide range of possibility to generate different models for simulation and reduce pre-simulation works. Selected concept parametric model has six different parameters that can be analysed. Material selection carried out to injection manifold thought CES Edupack and consultancy of material engineers. Three different austenitic stainless steels were recommended.

This diploma thesis focuses on checking of impact of urea concentration on refractive index of the liquid for selective catalytic reduction. The attention in the introduction part is paid on basic optical terms and laws, particularly on refractive index. Furthermore, the measurement of refraction index is described through particular refractometers and utilization of the refractive index of the liquid in technical practice. In the second part the thesis is focused on problematics of creation of nitrogen oxide emissions, aqueous solution of urea and on description of the construction of the system of selective catalytic reduction. The last, practical part of the thesis includes methodics of measuring of the refractive index of the aqueous solution of urea in various concentrations of urea. The experimental measurement was carried out in laboratories of the Department of Technology and Automobile Transport of Mendel University in Brno. In the conclusion of the practical part are data gained by measuring graphically and statistically evaluated and they are commented appropriately.