A Simple Nickel Catalyst Enabling an E‐Selective Alkyne Semihydrogenation

Stereoselective alkyne semihydrogenations are attractive approaches to alkenes, which are key building blocks for synthesis. With regards to the most atom economic reducing agent dihydrogen (H 2 ), only few catalysts for the challenging E ‐selective alkyne semihydrogenation have been disclosed, each with a unique substrate scope profile. Here, we show that a commercially available nickel catalyst facilitates the E ‐selective alkyne semihydrogenation of a wide variety of substituted internal alkynes. This results in a simple and broadly applicable overall protocol to stereoselectively access E ‐alkenes employing H 2 which could serve as a general method for synthesis.DFG, 352364740, Diwasserstoff-vermittelte nachhaltige BindungsknüpfungsreaktionenTU Berlin, Open-Access-Mittel - 201

Non-reciprocal coherent dynamics of a single spin under closed-contour interaction

Three-level quantum systems have formed a cornerstone of quantum optics since the discovery of coherent population trapping (CPT) and electromagnetically induced transparency. Key to these phenomena is quantum interference, which arises if two of the three available transitions are coherently driven at well-controlled amplitudes and phases. The additional coherent driving of the third available transition would form a closed-contour interaction (CCI) from which fundamentally new phenomena would emerge, including phase-controlled CPT and one atom interferometry. However, due to the difficulty in experimentally realising a fully coherent CCI, such aspects of three-level systems remain unexplored as of now. Here, we exploit recently developed methods for coherent driving of single Nitrogen-Vacancy (NV) electronic spins to implement highly coherent CCI driving. Our experiments reveal phase-controlled, single spin quantum interference fringes, reminiscent of electron dynamics on a triangular lattice, with the driving field phases playing the role of a synthetic magnetic flux. We find that for suitable values of this phase, CCI driving leads to efficient coherence protection of the NV spin, yielding a nearly two orders of magnitude improvement of the coherence time, even for moderate drive strengths <~1MHz. Our results establish CCI driving as a novel paradigm in coherent control of few-level systems that offers attractive perspectives for applications in quantum sensing or quantum information processing.Comment: 18 pages, 11 figures. Including supplementary material. Comments are welcome. For further information visit https://quantum-sensing.physik.unibas.ch/news.htm

Stereoselective alkyne semihydrogenations with an air-stable copper(I) catalyst

An air-stable and preactivated copper(I) hydroxide/N-heteroyclic carbene (NHC) complex for alkyne semihydrogenations is reported. Next to an enhanced practicability of the process, the resulting alkenes are obtained with high Z-selectivities and no overreduction to the corresponding alkanes

Repensando efeitos colaterais de responsabilização/accountability na educação. Resultados de um estudo multi-métodos em quatro sistemas escolares alemães

Based on a research project comprising data from an interview study and a survey with teachers and school principals in four German federal states (Bundesländer), this paper questions the claim that the side effects of accountability in education are bound to high-stakes contexts, and also provides evidence of side effects occurring in no- and low-stakes contexts. The findings suggest that side effects cannot be fully explained by certain implementation features of accountability regimes (e.g. high stakes), but should rather be understood as a result of implementation features as well as systematic effects of accountability in education.Basado en un proyecto de investigación que comprende datos de entrevistas y encuestas con profesores y directores de escuelas en cuatro Estados federados (Bundesländer), este trabajo cuestiona la afirmación de que los efectos secundarios de rendición de cuentas en educación están limitados a contextos de gran repercusión (high-stakes) y también proporciona evidencias de efectos secundarios que ocurren en contextos de baja o sin repercussion (low-stakes). Los resultados sugieren que los efectos secundarios no pueden explicarse completamente por ciertas características de la aplicación de los regímenes de rendición de cuentas por ejemplo de gran repercusión, pero debe entenderse más bien como ambos: como resultado de características de implementación y como efectos sistemáticos de rendición de cuentas en la educación. Baseado em um projeto de pesquisa que abrange dados de entrevistas e questionários com professores e diretores de escolas em quatro unidades da federação alemã (Bundesländer), este texto questiona a alegação de que os efeitos colaterais de responsabilização/accountability na educação estão vinculados aos contextos onde há sançoes (high-stakes) e também traz evidências dos efeitos que ocorrem em contextos com menores ou sem consequencias (low-stakes). Os resultados sugerem que efeitos colaterais não podem ser totalmente explicados por certas características de implementação de regimes de responsabilidade, por exemplo, high-stakes, mas antes devem ser entendidos como ambos: como resultado de características de implementação e como efeitos sistemáticos de responsabilização na educação

Towards the classification of symplectic linear quotient singularities admitting a symplectic resolution

Over the past two decades, there has been much progress on the classification of symplectic linear quotient singularities V/G admitting a symplectic (equivalently, crepant) resolution of singularities. The classification is almost complete but there is an infinite series of groups in dimension 4 - the symplectically primitive but complex imprimitive groups - and 10 exceptional groups up to dimension 10, for which it is still open. In this paper, we treat the remaining infinite series and prove that for all but possibly 39 cases there is no symplectic resolution. We thereby reduce the classification problem to finitely many open cases. We furthermore prove non-existence of a symplectic resolution for one exceptional group, leaving 39+9=48 open cases in total. We do not expect any of the remaining cases to admit a symplectic resolution

Creative Heritage - New Perspectives from Media Arts and Artificial Intelligence

This book constitutes the refereed post-conference proceedings of the 10th EAI International Conference on ArtsIT, Interactivity and Game Creation, ArtsIT 2021 which was held in December 2021. Due to COVID-19 pandemic the conference was held virtually. The 31 revised full papers presented were carefully selected from 57 submissions. The papers are thematically arranged in the following sections: Media Arts and Virtual Reality; Games; Fusions; Collaboration, Inclusion and Participation; Artificial Intelligence in Art and Culture; Approaches and Applications

Phylogenetic relationship of phototrophic purple sulfur bacteria according to pufL and pufM genes

The phylogenetic relationship of purple sulfur bacteria (PSB), of the order Chromatiales (class Gammaproteobacteria), was analyzed based on photosynthetic gene sequences of the pufL and pufM genes, and the results compared to phylogenetic trees and groupings of the 16S rRNA gene. Primers for pufL and pufM genes were constructed and successfully used to amplify the pufLM genes of members of 16 genera of Chromatiales. In total, pufLM and 16S rRNA gene sequences of 66 PSB strains were analyzed, including 29 type strains and 28 new isolates. The inferred phylogenetic trees of the pufLM and 16S rRNA genes reflected a largely similar phylogenetic development suggesting coevolution of these essential genes within the PSB. It is concluded that horizontal gene transfer of pufLM genes within the PSB is highly unlikely, in contrast to the Situation in other groups of anoxygenic phototrophic bacteria belonging to Alpha- and Betaproteobacteria. The phylogeny of pufLM is therefore in good agreement with the current taxonomic classification of PSB. A phylogenetic classification of PSB to the genus level is possible based on their pufL or pufM sequences, and in many cases even to the species level. In addition, our data support a correlation between Puf protein structure and the type of internal photosynthetic membranes (vesicular, lamellar, or tubular

Phylogenetic relationship of phototrophic purple sulfur bacteria according to pufL and pufM genes

The phylogenetic relationship of purple sulfur bacteria (PSB), of the order Chromatiales (class Gammaproteobacteria), was analyzed based on photosynthetic gene sequences of the pufL and pufM genes, and the results compared to phylogenetic trees and groupings of the 16S rRNA gene. Primers for pufL and pufM genes were constructed and successfully used to amplify the pufLM genes of members of 16 genera of Chromatiales. In total, pufLM and 16S rRNA gene sequences of 66 PSB strains were analyzed, including 29 type strains and 28 new isolates. The inferred phylogenetic trees of the pufLM and 16S rRNA genes reflected a largely similar phylogenetic development suggesting coevolution of these essential genes within the PSB. It is concluded that horizontal gene transfer of pufLM genes within the PSB is highly unlikely, in contrast to the situation in other groups of anoxygenic phototrophic bacteria belonging to Alpha- and Betaproteobacteria. The phylogeny of pufLM is therefore in good agreement with the current taxonomic classification of PSB. A phylogenetic classification of PSB to the genus level is possible based on their pufL or pufM sequences, and in many cases even to the species level. In addition, our data support a correlation between Puf protein structure and the type of internal photosynthetic membranes (vesicular, lamellar, or tubular). [Int Microbiol 2009; 12(3):175-185

A quantum algorithm for computing the unit group of an arbitrary degree number field

Computing the group of units in a field of algebraic numbers is one of the central tasks of computational algebraic number theory. It is believed to be hard classically, which is of interest for cryptography. In the quantum setting, efficient algorithms were previously known for fields of constant degree. We give a quantum algorithm that is polynomial in the degree of the field and the logarithm of its discriminant. This is achieved by combining three new results. The first is a classical algorithm for computing a basis for certain ideal lattices with doubly exponentially large generators. The second shows that a Gaussian-weighted superposition of lattice points, with an appropriate encoding, can be used to provide a unique representation of a real-valued lattice. The third is an extension of the hidden subgroup problem to continuous groups and a quantum algorithm for solving the HSP over the group ℝ^n

Bacterial isolates from the bryozoan Membranipora membranacea: influence of culture media on isolation and antimicrobial activity

From specimens of the bryozoan Membranipora membranacea collected in the Baltic Sea, bacteria were isolated&nbsp;on four different media, which significantly increased the diversity of the isolated groups. All isolates were classifiedaccording to 16S rRNA gene sequence analysis and tested for antimicrobial properties using a panel of five indicator strainsand six different media. Each medium featured a unique set of isolated phylotypes, and a phylogenetically diverse collection&nbsp;of isolates was obtained. A total of 96 isolates were assigned to 49 phylotypes and 29 genera. Only one-third of the members&nbsp;of these genera had been isolated previously from comparable sources. The isolates were affiliated with Alpha- and&nbsp;Gammaproteobacteria, Bacilli, and Actinobacteria. A comparable large portion of up to 22 isolates, i.e., 15 phylotypes, probably&nbsp;represent new species. Likewise, 47 isolates (approximately 50%) displayed antibiotic activities, mostly against grampositive&nbsp;indicator strains. Of the active strains, 63.8 % had antibiotic traits only on one or two of the growth media, whereas&nbsp;only 12.7 % inhibited growth on five or all six media. The application of six different media for antimicrobial testing resulted&nbsp;in twice the number of positive hits as obtained with only a single medium. The use of different media for the isolation of&nbsp;bacteria as well as the variation of media considered suitable for the production of antibiotic substances significantly&nbsp;enhanced both the number of isolates obtained and the proportion of antibiotic active cultures. Thus the approach described&nbsp;herein offers an improved strategy in the search for new antibiotic compounds.&nbsp;[Int Microbiol 2012; 15(1):17-32