51 research outputs found
Exploiting PUF Variation to Detect Fault Injection Attacks
No full textThe massive deployment of Internet of Things (IoT) devices makes them vulnerable against physical tampering attacks, such as fault injection. These kind of hardware attacks are very popular as they typically do not require complex equipment or high expertise. Hence, it is important that IoT devices are protected against them. In this work, we present a novel fault injection attack detector with high flexibility and low overhead. Our solution is based on the reuse of a security primitive used in many IoT devices, i.e., ring oscillator (RO) physically unclonable function (PUF). Our results show that we obtain a high detection effectiveness and no false alarms against most popular fault injection attacks based on voltage and clock manipulations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Computer EngineeringQuantum & Computer Engineerin
A computational glance at organometallic cyclizations and coupling reactions
No full text210 p.Organometallic chemistry is one of the main research topics in chemical science.Nowadays, organometallic reactions are the subject of intensive theoretical investigations.However, in many cases, only joint experimental and theoretical effortscould reveal the answers what we are looking for.The fruits of such experimental and theoretical co-operations will be presentedhere. In this work, we are going to deal with homogeneous organometallic catalysisusing computational chemical tools. Particularly, DFT study of palladium andgold-catalyzed reactions and special carbometalations will be described.Chapter 1 gives an introductory overview of organometallic chemistry andcatalysis in general using a historical perspective. It covers the 9 thousand yearshistory of catalysis from 7000 BC (the earliest concrete evidence of man-made fermentation/biocatalysis) through several milestones (Libavius, Berzelius etc.) upto the present days of organometallic chemistry.Chapter 2 is a short methodological summary and intended to shed some lighton the theoretical foundations of the applied quantum chemical tools, but it is neithercomplete, nor deep, just enough to scratch the surface and give insight into thecomplexity of the theory.The results of our calculations presented in three separate chapters,(Chapter 3, 4 and 5) in each of which the calculations discussed along with theviiiSupervisor: Prof. Enrique Gómez Bengoa Author: Béla Fisercorresponding experimental findings of our collaborators and/or other scientists.Chapter 3 describe specific issues of palladium-catalyzed reactions. In this partof the work, palladium(II)-catalyzed dynamic kinetic asymmetric C¿P couplingfor the asymmetric synthesis of QUINAP and other atropos P,N-ligands is discussedand the reaction investigated at the M06/6-31+G(d,p)/SDD//B3LYP/6-31G(d)/LANL2DZ level of theory. The computational results along with xperimentalevidences collected by our collaborators allowed to propose a mechanismbased on the formation of cationic oxidative addition intermediates which underthe reaction conditions, undergo a fast interconversion (Figure 0.0.1). Coordinationof the isoquinoline N atom to Pd is essential to facilitate this process.Figure 0.0.1: Proposed Mechanism for the Epimerization of DiastereomericOxidative Addition Intermediates (OAI and OAI¿).The calculations also show that the energy requirements for a dynamic kineticprocess are met, since the fast equilibrating palladacyclic intermediates evolve throughixSupervisor: Prof. Enrique Gómez Bengoa Author: Béla Fiserdiastereomeric transmetalation steps of very large energy difference. The easinessof the final reductive elimination ensures the irreversibility of the process.Chapter 4 can be divided into two parts in which gold(I)-catalyzed reactionsare studied.In the first section, the tandem gold(I)-catalyzed rearrangement/Nazarov reactionof propargylic ester derivatives studied in deeply computationally and thecalculations revealed the details of the reaction mechanism (Figure 0.0.2) whichallowed us to evaluate energetically the influence of the substrate structures on thereaction rate and on the regio- and stereoselectivity.Figure 0.0.2: Reaction Mechanism. Top: Acetate Rearrangement in the InitialSteps of the Mechanism. Bottom: Cyclization Step from the pre-Nazarovcyclization complex III and Protodeauration. Gibbs Free Energy Changes(¿G) and Barrier Heights (¿Gz) are Given in kcal/mol.xSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserIn the second section, gold(I)-catalyzed cycloisomerizations calculated (Figure0.0.3). The calculations showed that with both types of substrates, the oxyaurationstep has a low barrier or almost no barrier at all when it involves the internalposition of a terminal triple bond, resulting in a 5-exo-dig process. In contrast,the 6-endo-dig mechanism is always favoured with substituted alkynes. The preferencebeing purely geometrical and irrespective of the type of substitution, thusproviding either ß-enaminones or their reduced equivalents, ß-amino ketones, ina robust, reliable, and convenient way.Figure 0.0.3: Transition State Structures and the Corresponding BarrierHeights (¿Gz, in kcal/mol) for Terminal and Internal Alkynes.xiSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserChapter 5 is a systematical study of intramolecular metal catalyzed cyclizations.Group 10 alkyl metalations are studied systematically by means of DFT calculationsand based on the results the extension of the Baldwin¿s rules for metal catalyzedring closure reactions is proposed (Figure 0.0.4).Figure 0.0.4: Studied Group 10 Alkyl Metalations.An intuitive summary of the qualitative results created and the results couldserve as a guide to explore not yet described cyclization processes based on the accessiblecomputed activation energies and the qualitative comparison of the preferences.Our manuscripts published in connection with the topics discussed in the thesiscan be found in the Appendix.xiiSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserA Computational Glance at Organometallic Cyclizationsand Coupling ReactionsAbstractLa química organometálica es uno de los campos más activos de investigación enciencias químicas. Hoy en día, las reacciones organometálicas son sujeto de numerosasinvestigaciones teóricas. Sin embargo, en muchos casos, sólo los esfuerzosconjuntos teóricos y experimentales son capaces de encontrar las respuestasque buscamos. En este trabajo se presentan los frutos de tales colaboracionesexperimentales/teóricas. Hemos empleado herramientas computacionales paraestudiar reacciones catalizadas en condiciones homogéneas, y más concretamentedescribimos a continuación estudios DFT de reacciones de ciclación catalizadaspor Paladio y Oro, así como algunos tipos de carbometalación.Capítulo 1. Se da un repaso introductorio de la catálisis organometálica ycatálisis en general usando una perspectiva histórica. Cubre los 9000 años de historiade la catálisis desde el 7000 a. C. (la más antigua evidencia de fermentación/ biocatálisis hecha por el hombre) a través de diversos hitos (Libavius, Berzelius,etc.) hasta la química organometálica de nuestros días.Capítulo 2. Es una breve descripción metodológica que intenta dar luz sobrelas formulaciones teóricas que se aplican en las herramientas químicas cuánticas,sin la intención de ser completa ni profusa, sino solamente arañando la superficiede esta parte tan compleja de la teoría.Los resultados de nuestros cálculos se presentan en tres capítulos separadosxiiiSupervisor: Prof. Enrique Gómez Bengoa Author: Béla Fiser(capítulos 3, 4 y 5), en cada uno de los cuales se entremezclan con los resultadosexperimentales de nuestros colaboradores y otros grupos de investigación.Capítulo 3. Describe algunas características especiales de la química del paladio.En esta parte de la Tesis, se han estudiado reacciones de síntesis asimétricade QUINAP, mediante un acoplamiento C-P dinámico cinético asimétrico catalizadopor complejos de paladio (II). Además de QUINAP, se han estudiado otrosatropo-ligandos P, N por métodos DFT al nivel de cálculoM06/6-31+G(d,p)/SDD//B3LYP/6-31G(d)/LANL2DZ.Figure 0.0.1: Mecanismo Propuesto para la Epimerización de los IntermediosDiastereoméricos de Adición Oxidante (OAI y OAI¿).xivSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserLos resultados computacionales junto a las evidencias experimentales recopiladaspor nuestros colaboradores nos permiten proponer un mecanismo de reacciónbasado en la formación de intermedios catiónicos de adición oxidante, queen las condiciones de reacción sufren una interconversión rápida entre diferentesisómeros (Figura 0.0.1). La coordinación del nitrógeno de la isoquinolina al átomode Pd es esencial para facilitar el proceso.Los cálculos también muestran que se cumplen los requisitos energéticos parauna resolución cinética dinámica, ya que los intermedios de reacción equilibranrápidamente y evolucionan por estados de transición de transmetalación de barrerasde activación muy diferentes.xvSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserCapítulo 4. Se divide en dos partes en las que se estudian dos reacciones catalizadaspor Au(I) diferentes. En la primera sección, se ha estudiado computacionalmenteal detalle la reacción tándem de transposición / ciclación Nazarov catalizadaspor Au(I) de ésteres propargílicos, y nuestros cálculos revelan el mecanismodetallado en la Figura 0.0.2, permitiéndonos evaluar energéticamente la influenciade las estructuras de los substratos en la velocidad de reacción y en la regio- yestereoselectividad.Figure 0.0.2: Mecanismo de Reacción. Arriba: Transposición de Acetato enlos Inicios de la Reacción. Abajo: Paso de Ciclación desde el Complejo pre-Nazarov III y Protodesauración. Los Cambios en la Energía Libre de Gibbs(¿G) y Barreras de Activación (¿Gz) se dan en kcal/mol.xviSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserEn la segunda sección, se han calculado reacciones de cicloiosomerización catalizadaspor Au(I) (Figura 0.0.3). Los cálculos muestran que para ambos tipos desustratos mostrados, el paso de oxiauración ocurre con una barrera de activaciónmuy baja o inexistente cuando ocurre en la posición interna del triple enlace, resultandoen un proceso 5-exo-dig. La preferencia es puramente geométrica e independientedel tipo de sustitución, dando lugar tanto las ß-enaminonas como susequivalentes reducidos, ß-amino cetonas, de un modo robusto, apropiado y fiable.Figure 0.0.3: Estructuras de los Estados de Transición y sus CorrespondientesBarreras de Activación (¿Gz, se dan en kcal/mol) para los AlquinosTerminales e Internos.xviiSupervisor: Prof. Enrique Gómez Bengoa Author: Béla FiserCapítulo 5. Es un estudio sistemático de reacciones de ciclación catalizadaspor metales de transición. Se han estudiado sistemáticamente las ciclaciones conlos metales del grupo 10 por métodos computacionales, y basándonos en los resultados,se propone una extensión de las reglas clásicas de Baldwin para ciclacionesa la catálisis metálica (Figura 0.0.4)Figure 0.0.4: Metalaciones del Grupo 10 Estudiadas.Los resultados cualitativos han dado lugar a un resumen intuitivo de los resultadosque podría servir como guía para explorar nuevos procesos catalíticos decarbometalación.Los manuscritos publicados como resultado de estos capítulos se adjuntan enel Apéndice I.xvii
Bordetella adenylate cyclase toxin mobilizes its beta2 integrin receptor into lipid rafts to accomplish translocation across target cell membrane in two steps.
No full textBordetella adenylate cyclase toxin (CyaA) binds the alpha(M)beta(2) integrin (CD11b/CD18, Mac-1, or CR3) of myeloid phagocytes and delivers into their cytosol an adenylate cyclase (AC) enzyme that converts ATP into the key signaling molecule cAMP. We show that penetration of the AC domain across cell membrane proceeds in two steps. It starts by membrane insertion of a toxin 'translocation intermediate', which can be 'locked' in the membrane by the 3D1 antibody blocking AC domain translocation. Insertion of the 'intermediate' permeabilizes cells for influx of extracellular calcium ions and thus activates calpain-mediated cleavage of the talin tether. Recruitment of the integrin-CyaA complex into lipid rafts follows and the cholesterol-rich lipid environment promotes translocation of the AC domain across cell membrane. AC translocation into cells was inhibited upon raft disruption by cholesterol depletion, or when CyaA mobilization into rafts was blocked by inhibition of talin processing. Furthermore, CyaA mutants unable to mobilize calcium into cells failed to relocate into lipid rafts, and failed to translocate the AC domain across cell membrane, unless rescued by Ca(2+) influx promoted in trans by ionomycin or another CyaA protein. Hence, by mobilizing calcium ions into phagocytes, the 'translocation intermediate' promotes toxin piggybacking on integrin into lipid rafts and enables AC enzyme delivery into host cytosol
Mereni koncentrace ethanolu ve fermentacnim mediu
No full textAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi
User Assisted Creation of Open-Linked Data for Training Web Information Extraction in a Social Network
No full textContinuous Assembly of β-Roll Structures Is Implicated in the Type I-Dependent Secretion of Large Repeat-in-Toxins (RTX) Proteins
No full textDespite the continued analysis of HDAC inhibitors in clinical trials, the heterogeneous nature of the protein complexes they target limits our understanding of the beneficial and off-target effects associated with their application. Among the many HDAC protein complexes found within the cell, Sin3 complexes are conserved from yeast to humans and likely play important roles as regulators of transcriptional activity. The presence of two Sin3 paralogs in humans, SIN3A and SIN3B, may result in a heterogeneous population of Sin3 complexes and contributes to our poor understanding of the functional attributes of these complexes. Here, we profile the interaction networks of SIN3A and SIN3B to gain insight into complex composition and organization. In accordance with existing data, we show that Sin3 paralog identity influences complex composition. Additionally, chemical cross-linking MS identifies domains that mediate interactions between Sin3 proteins and binding partners. The characterization of rare SIN3B proteoforms provides additional evidence for the existence of conserved and divergent elements within human Sin3 proteins. Together, these findings shed light on both the shared and divergent properties of human Sin3 proteins and highlight the heterogeneous nature of the complexes they organize
A parametric study of influence of material properties on car cabin environment
No full textRecently the author presented the paper describing a car cabin heat load model for the prediction of the car cabin environment. The model allowed to simulate a transient behavior of the car cabin, i.e. radiant temperature of surfaces, air temperature and relative humidity. The model was developed in Dymola and was built on the basic principles of thermodynamics and heat balance equations. The model was validated by experiments performed on the Škoda Felicia during various operational conditions. In this paper the authors present a parametric study investigating influence of material properties on a car cabin environment. The Matlab version of the car cabin heat load model has been developed and used. The model was extended by simple graphical user interface and it was deployed into the stand alone executable application. The aim of this parametric study is to identify most important material properties and its effect on the cabin environment during specific operational conditions of car. By means of a sensitive analysis it can identified which material parameters have to be defined precisely and which parameters are not so important for the prediction of the air temperature inside cabin
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