Exploring initial challenges for green software engineering: summary of the first GREENS workshop, at ICSE 2012

The GREENS workshop provides a forum for practitioners and academics to share knowledge, ideas, practices and current results related to green and sustainable software engineering. This first workshop was held at ICSE 2012 in Zurich, Switzerland. It featured a keynote talk, twelve research position statements and two breakout sessions that discussed topics that ranged from bringing sustainability and energy efficiency into all software lifecycle stages, to green measures and estimations, practices, notations, and tools to both greening the software engineering process, and greening the resulting Information and Communication Technology systems. This report presents the themes of the workshop, summarizes the results of the discussions held in the breakout sessions, as well as the identified research challenge

Algorithms and Bounds for Drawing Directed Graphs

In this paper we present a new approach to visualize directed graphs and their hierarchies that completely departs from the classical four-phase framework of Sugiyama and computes readable hierarchical visualizations that contain the complete reachability information of a graph. Additionally, our approach has the advantage that only the necessary edges are drawn in the drawing, thus reducing the visual complexity of the resulting drawing. Furthermore, most problems involved in our framework require only polynomial time. Our framework offers a suite of solutions depending upon the requirements, and it consists of only two steps: (a) the cycle removal step (if the graph contains cycles) and (b) the channel decomposition and hierarchical drawing step. Our framework does not introduce any dummy vertices and it keeps the vertices of a channel vertically aligned. The time complexity of the main drawing algorithms of our framework is $O(kn)$, where $k$ is the number of channels, typically much smaller than $n$ (the number of vertices).Comment: Appears in the Proceedings of the 26th International Symposium on Graph Drawing and Network Visualization (GD 2018

Characterization of borides in Co Re Cr based high temperature alloys

Co Re Cr based alloys with additions of 200 ppm or 1000 ppm boron were investigated by high resolution methods such as scanning electron microscopy, transmission electron microscopy and three dimensional atom probe. The chemical composition of borides with a lamellar structure resembling a eutectic as determined by three dimensional atom probe is Cr0.68Re0.46Co0.24B, the composition of isolated boride particles at the grain boundaries is Cr0.76Re0.40Co0.35B. A systematic study was carried out to determine the crystal structure of the various types of borides. Despite their varying chemical composition, the borides in the two alloys, even when appearing in different morphologies, exhibit the same orthorhombic Ccentred unit cell with lattice parameters a 0.436 nm, b 0.755 nm and c 1.498 nm

Intermolecular [2π+2σ]-photocycloaddition enabled by triplet energy transfer

© 2022, The Author(s), under exclusive licence to Springer Nature Limited.For more than one century, photochemical [2+2]-cycloadditions have been used by synthetic chemists to make cyclobutanes, four-membered carbon-based rings. In this reaction, typically two olefin subunits (two π-electrons per olefin) cyclize to form two new C–C σ-bonds. Although the development of photochemical [2+2]-cycloadditions has made enormous progress within the last century, research has been focused on such [2π+2π]-systems, in which two π-bonds are converted into two new σ-bonds1,2. Here we report an intermolecular [2+2]-photocycloaddition that uses bicyclo[1.1.0]butanes as 2σ-electron reactants3–7. This strain-release-driven [2π+2σ]-photocycloaddition reaction was realized by visible-light-mediated triplet energy transfer catalysis8,9. A simple, modular and diastereoselective synthesis of bicyclo[2.1.1]hexanes from heterocyclic olefin coupling partners, namely coumarins, flavones and indoles, is disclosed. Given the increasing importance of bicyclo[2.1.1]hexanes as bioisosteres—groups that convey similar biological properties to those they replace—in pharmaceutical research and considering their limited access10,11, there remains a need for new synthetic methodologies. Applying this strategy enabled us to extend the intermolecular [2+2]-photocycloadditions to σ-bonds and provides previously inaccessible structural motifs.11Nsciescopu