Suchergebnisse

Web systems have become an integral part in daily life of billions of people. Social is a key characteristic today's web projects need to feature in order to be successful in the social age. To benefit from an improved user experience, individual persons are continually invited to reveal more and more personal data to web systems. With a rising severity of attacks on web systems, it is evident that their security is inadequate for the amount of accumulated personal data. Numerous threat reports indicate that social media has become a top-ranking attack target, with climbing impacts, with ramifications beyond single individuals and with a booming black market to trade leaked personal data. To enhance information security in managing personal data by web systems for the mutual benefit of individual persons, companies and governments, this dissertation proposes a solution architecture and three research contributions. While the solution architecture establishes the foundation for a more secure management of personal data by web systems, the research contributions represent complementary components for protecting personal data against unwanted data disclosure, tampering and use without the actual data owner's intent or knowledge. Not only do these components enable seamless integration and combination, but they also contribute to assure quality and maintainability. The dissertation concludes with discussing evaluation results and providing an outlook towards future work.

Antimonene, a novel group 15 two-dimensional material, is functionalized with a tailormade perylene bisimide through strong van der Waals interactions. The functionalization process leads to a significant quenching of the perylene fluorescence, and surpasses that observed for either graphene or black phosphorus, thus allowing straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge-transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, thus pointing towards the spontaneous formation of a sub-nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge-transfer band gap of 1.1 eV ; We thank the ESCA microscopy beamline team at Elettra for technical assistance with the scanning X‐ray photoelectron microscopy measurements. The research leading to these results has received partial funding from the European Union Seventh Framework Programme under grant agreement no. 604391 Graphene Flagship. We thank the Deutsche Forschungsgemeinschaft (DFG‐SFB 953 "Synthetic Carbon Allotropes", Projects A1 and C2), the Interdisciplinary Center for Molecular Materials (ICMM), and the Graduate School Molecular Science (GSMS) for financial support. We thank the MINECO (Spain) for financial support through the "María de Maeztu" Programme for Units of Excellence in R&D (MDM‐2014‐0377) and the projects: MAT2016‐77608‐C3‐1P and 3P, as well as MAT2014‐52477‐C5‐5 and MAT2015‐66888‐C3‐3‐R. Co‐funding from UE is also acknowledged. G.A. thanks the EU for a Marie Curie Fellowship (FP7/2013‐IEF‐627386), and the FAU for the Emerging Talents Initiative (ETI) grant #WS16‐17_Nat_04

[EN] Group 15 elements in zero oxidation state (P, As, Sb and Bi), also called pnictogens, are rarely used in catalysis due to the difficulties associated in preparing well-structured and stable materials. Here, we report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, suspended in an ionic liquid, with the native atoms ready to interact with external reagents while avoiding aerobic or aqueous decomposition pathways, and on their use as efficient catalysts for the alkylation of nucleophiles with esters. The few layer pnictogen material circumvents the extremely harsh reaction conditions associated to previous superacid-catalyzed alkylations, by enabling an alternative mechanism on surface, protected from the water and air by the ionic liquid. These 2D catalysts allow the alkylation of a variety of acid-sensitive organic molecules and giving synthetic relevancy to the use of simple esters as alkylating agents. ; We thank the European Research Council (ERC Starting Grant 804110 to G.A., and ERC Advanced Grant 742145 B-PhosphoChem to A.H.) for financial support. The research leading to these results was partially funded by the European Union Seventh Framework Program under grant agreement No. 604391 Graphene Flagship. G.A. has received financial support through the Postdoctoral Junior Leader Fellowship Program from "la Caixa" Banking Foundation (LCF/BQ/PI18/11630018). G.A. thanks support by the Deutsche Forschungsgemeinschaft (DFG; FLAG-ERA AB694/2-1), the Generalitat Valenciana (SEJI/2018/034 grant) and the FAU (Emerging Talents Initiative grant #WS16-17_Nat_04). Financial support by MINECO through the Excellence Unit Maria de Maeztu (MDM-2015-0538), Severo Ochoa (SEV-2016-0683) and RETOS (CTQ2014-55178-R) program is acknowledged. M.A.R.-C. thanks MINECO for the concession of a FPU fellowship. We also thank the DFG (DFG-SFB 953 "Synthetic Carbon Allotropes", Project A1), the Interdisciplinary Center for Molecular Materials (ICMM), and the Graduate School ...