Disentangling the Role of the SnO Layer on the Pyro-Phototronic Effect in ZnO-Based Self-Powered Photodetectors

Self-powered photodetectors (PDs) have been recognized as one of the developing trends of next-generation optoelectronic devices. Herein, it is shown that by introducing a thin layer of SnO film between the Si substrate and the ZnO film, the self-powered photodetector Al/Si/SnO/ZnO/ITO exhibits a stable and uniform violet sensing ability with high photoresponsivity and fast response. The SnO layer introduces a built-in electrostatic field to highly enhance the photocurrent by over 1000%. By analyzing energy diagrams of the p-n junction, the underlying physical mechanism of the self-powered violet PDs is carefully illustrated. A high photo-responsivity (R) of 93 mA W⁻¹ accompanied by a detectivity (D*) of 3.1 × 10¹⁰ Jones are observed under self-driven conditions, when the device is exposed to 405 nm excitation laser wavelength, with a laser power density of 36 mW cm⁻² and at a chopper frequency of 400 Hz. The Si/SnO/ZnO/ITO device shows an enhancement of 3067% in responsivity when compared to the Al/Si/ZnO/ITO. The photodetector holds an ultra-fast response of ≈ 2 µs, which is among the best self-powered photodetectors reported in the literature based on ZnO.     

Miniaturized and Automated Synthesis of Biomolecules—Overview and Perspectives

Chemical synthesis is performed by reacting different chemical building blocks with defined stoichiometry, while meeting additional conditions, such as temperature and reaction time. Such a procedure is especially suited for automation and miniaturization. Life sciences lead the way to synthesizing millions of different oligonucleotides in extremely miniaturized reaction sites, e.g., pinpointing active genes in whole genomes, while chemistry advances different types of automation. Recent progress in matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) imaging could match miniaturized chemical synthesis with a powerful analytical tool to validate the outcome of many different synthesis pathways beyond applications in the life sciences. Thereby, due to the radical miniaturization of chemical synthesis, thousands of molecules can be synthesized. This in turn should allow ambitious research, e.g., finding novel synthesis routes or directly screening for photocatalysts. Herein, different technologies are discussed that might be involved in this endeavor. A special emphasis is given to the obstacles that need to be tackled when depositing tiny amounts of materials to many different extremely miniaturized reaction sites.     

Mathematical Modeling of Homopolymerization on Supported Metallocene Catalysts

Summary: In this paper, a mathematical model describing olefin polymerization with metallocene catalysts is presented. It is an improvement of a previous model, the “particle growth model” (PGM) proposed by, among others, one of the authors of the present work and derives from the so‐called “multigrane model” (MGM). The main differences between this work and others is a more sophisticated approach to fragmentation with respect to the MGM. Additionally, there is a more specific modeling for the unfragmented core with respect to the PGM. The numerical results obtained by the model are compared with experimental data. The results of this work allow to extend the PGM to catalysts with lower activity. The importance of those catalysts depends on the fact that high activity catalysts could bring, in some cases, too poor polymer morphology.

Geometrical representation of the micro‐ and macroparticle.     

Online Journalism and the War in Cyberspace: A Comparison Between U.S. and International Newspapers

The 2003 Iraq War was the first military conflict in which online media played a significant role. Traditional news organizations from around the world provided extensive coverage of the conflict on their websites, reaching global audiences and adding new dimensions to traditional war reporting. This study explores how the Internet disseminated news about the war by comparing 26 international newspaper sites (N = 791) and their use of Web‐specific features such as hyperlinks, animations, multimedia content, and interactive elements. By proposing a three‐stage model of online journalism and applying it to the online war coverage, the analysis suggests that online journalism has not yet reached the state of convergence. The differences in online news coverage between the United States and international websites and their implications are also discussed.     

Assessment of a new synbiotic preparation in healthy volunteers: survival,persistence of probiotic strains and its effect on the indigenous flora

Background  

Use of synbiotic preparations as dietary supplement is believed to be a valid approach to restore and maintain colonic microflora. However, only few papers have been published on the assessment of these food supplements and none of them have used molecular biology techniques to evaluate the effects of the probiotic components.     

Tools for the study of genome rearrangements in laboratory and industrial yeast strains

In order to investigate the extent of genome rearrangements in laboratory and industrial yeast strains, a set of plasmids, containing ca. 300 bp fragments from highly conserved genes from S. cerevisiae, has been constructed. We chose three unique PCR products, each from a single gene, per chromosome: one from close to the centromere, and one from each chromosome end. Using these plasmids as probes to hybridize a Southern blot from a pulsed-field gel electrophoresis separation of the 16 yeast chromosomes, it is possible to identify large chromosomal rearrangements such as reciprocal translocations.     

Selective mixed potential ammonia exhaust gas sensor

Novel selective ammonia sensors with high potential for long-term stability in harsh exhaust environments are introduced. The sensor bases on the mixed potential effect. In contrast to common sensors, the electrode functionalities electrical conductivity, selective catalytic activity, and electrochemical activity combined with long-term stability are separated. For that reason, one of the two electrodes is covered by a well-known porous vanadia–tungstenia–titania-based SCR catalyst material, which has been developed for exhaust gas SCR applications. The resulting sensor signal depends semi-logarithmically on ammonia. The NO_x cross-sensitivity is marginal. If enough oxygen is in the exhaust, the sensor signal is independent of the oxygen concentration. Tests downstream of an SCR catalyst show that very small ammonia slips can be determined.