Technical University of Berlin

About: Technical University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Laser & Catalysis. The organization has 27292 authors who have published 59342 publications receiving 1414623 citations. The organization is also known as: Technische Universität Berlin & TU Berlin.

Engineering of Promoter Replacement Cassettes for Fine-Tuning of Gene Expression in Saccharomyces cerevisiae

Abstract: The strong overexpression or complete deletion of a gene gives only limited information about its control over a certain phenotype or pathway. Gene function studies based on these methods are therefore incomplete. To effect facile manipulation of gene expression across a full continuum of possible expression levels, we recently created a library of mutant promoters. Here, we provide the detailed characterization of our yeast promoter collection comprising 11 mutants of the strong constitutive Saccharomyces cerevisiae TEF1 promoter. The activities of the mutant promoters range between about 8% and 120% of the activity of the unmutated TEF1 promoter. The differences in reporter gene expression in the 11 mutants were independent of the carbon source used, and real-time PCR confirmed that these differences were due to varying levels of transcription (i.e., caused by varying promoter strengths). In addition to a CEN/ARS plasmid-based promoter collection, we also created promoter replacement cassettes. They enable genomic integration of our mutant promoter collection upstream of any given yeast gene, allowing detailed genotype-phenotype characterizations. To illustrate the utility of the method, the GPD1 promoter of S. cerevisiae was replaced by five TEF1 promoter mutants of different strengths, which allowed analysis of the impact of glycerol 3-phosphate dehydrogenase activity on the glycerol yield.

Ozonation and Advanced Oxidation of Wastewater: Effect of O3 Dose, pH, DOM and HO•-Scavengers on Ozone Decomposition and HO• Generation

Abstract: The decomposition of ozone in wastewater is observed starting 350 milliseconds after ozone addition. It seems not to be controlled by the autocatalytic chain reaction, but rather by direct reactions with reactive moieties of the dissolved organic matter (DOM). A larger ozone dose increases ozone consumption prior to 350 milliseconds but decreases the rate of ozone decomposition later on; this effect is predicted by a second-order kinetic model. Transferred Ozone Dose (TOD) is poorly correlated with ozone exposure (= ∫[O3]dt) indicating that TOD is not a suitable parameter for the prediction of disinfection or oxidation in wastewater. HO• concentrations (> 10−10 M) and Rct (=∫[HO•]dt/∫[O3]dt > 10−6) are larger than in most advanced oxidation processes (AOP) in natural waters, but rapidly decrease over time. Rct also decreases with increasing pre-ozonation doses. An increase in pH accelerates ozone decomposition and HO• generation; this effect is predicted by a kinetic model taking into account deprotonatio...

Photoluminescence of freestanding single- and few-layer MoS 2

Abstract: We present a photoluminescence study of freestanding and Si/${\text{SiO}}_{2}$ supported single- and few-layer ${\text{MoS}}_{2}$. The single-layer exciton peak (A) is only observed in freestanding ${\text{MoS}}_{2}$. The photoluminescence of supported single-layer ${\text{MoS}}_{2}$ instead originates from the A${}^{\ensuremath{-}}$ (trion) peak as the ${\text{MoS}}_{2}$ is $n$-type doped from the substrate. In bilayer ${\text{MoS}}_{2}$, the van der Waals interaction with the substrate decreases the indirect band gap energy by up to $\ensuremath{\approx}80$ meV. Furthermore, the photoluminescence spectra of suspended ${\text{MoS}}_{2}$ can be influenced by interference effects.

New vistas in N-heterocyclic silylene (NHSi) transition-metal coordination chemistry: syntheses, structures and reactivity towards activation of small molecules.

Abstract: This account is a review on the synthesis and transition-metal coordination chemistry of N-heterocyclic silylenes (NHSi’s) over the last 20 years till the present time (2012). Recently, fascinating and novel synthetic methods have been developed to access transition-metal–NHSi complexes as an emerging class of compounds with a wealth of intriguing reactivity patterns. The striking influence of coordinating NHSi’s to transition-metal complex fragments affording different reactivities to the “free” NHSi is a connecting theme (“leitmotif”) throughout the review, and highlights the potential of these compounds which lie at the interface of contemporary main-group and classical organometallic chemistry towards new molecular catalysts for small-molecule activation.