Life Cycle of Smart Contracts in Blockchain Ecosystems

This paper discusses the life cycle of decentralized smart contracts, i.e. digital and executable representations of rights and obligations in a multi-party environment. The life cycle relies on blockchain technology, i.e. a distributed digital ledger, to ensure proper implementation and integrity of the smart contracts. The life cycle consists of four subsequent phases: Creation, freezing, execution, and finalization. For each phase actors and technological services are identified and explained in detail. With the life cycle at hand, risks and limitations of smart contracts and the underlying blockchain technology are briefly discussed.     

E as in Enigma: The Mysterious Role of the Voltage-Dependent Anion Channel Glutamate E73

The voltage-dependent anion channel (VDAC) is the main passageway for ions and metabolites over the outer mitochondrial membrane. It was associated with many physiological processes, including apoptosis and modulation of intracellular Ca²⁺ signaling. The protein is formed by a barrel of 19 beta-sheets with an N-terminal helix lining the inner pore. Despite its large diameter, the channel can change its selectivity for ions and metabolites based on its open state to regulate transport into and out of mitochondria. VDAC was shown to be regulated by a variety of cellular factors and molecular partners including proteins, lipids and ions. Although the physiological importance of many of these modulatory effects are well described, the binding sites for molecular partners are still largely unknown. The highly symmetrical and sleek structure of the channel makes predictions of functional moieties difficult. However, one residue repeatedly sticks out when reviewing VDAC literature. A glutamate at position 73 (E73) located on the outside of the channel facing the hydrophobic membrane environment was repeatedly proposed to be involved in channel regulation on multiple levels. Here, we review the distinct hypothesized roles of E73 and summarize the open questions around this mysterious residue.     

Synthesis and Anticancer Evaluation of New Indole-Based Tyrphostin Derivatives and Their (p-Cymene)dichloridoruthenium(II) Complexes

New N-alkylindole-substituted 2-(pyrid-3-yl)-acrylonitriles with putative kinase inhibitory activity and their (p-cymene)Ru(II) piano-stool complexes were prepared and tested for their antiproliferative efficacy in various cancer models. Some of the indole-based derivatives inhibited tumor cell proliferation at (sub-)micromolar concentrations with IC₅₀ values below those of the clinically relevant multikinase inhibitors gefitinib and sorafenib, which served as positive controls. A focus was set on the investigation of drug mechanisms in HCT-116 p53-knockout colon cancer cells in order to evaluate the dependence of the test compounds on p53. Colony formation assays as well as experiments with tumor spheroids confirmed the excellent antineoplastic efficacy of the new derivatives. Their mode of action included an induction of apoptotic caspase-3/7 activity and ROS formation, as well as anti-angiogenic properties. Docking calculations with EGFR and VEGFR-2 identified the two 3-aryl-2-(pyrid-3-yl)acrylonitrile derivatives 2a and 2b as potential kinase inhibitors with a preferential activity against the VEGFR-2 tyrosine kinase. Forthcoming studies will further unveil the underlying mode of action of the promising new derivatives as well as their suitability as an urgently needed novel approach in cancer treatment.     

Zur Frage der Elastizität,der Beanspruchung und der Festigkeit warmbetriebener Rohrleitungen

Zusammenfassung Die Entwicklung der Dampfkraftanlagen zu immer h?heren Temperaturen, Drücken und Leistungen zwingt den Rohrleitungsbauer, sich noch eingehender als bisher mit den Fragen der Elastizit?t, der Beanspruchung und der Festigkeit der Rohrleitung zu besch?ftigen. Zu einigen der wesentlichen Fragen werden im folgenden rechnerische und experimentelle Beitr?ge mitgeteilt. VDI     

Vertrauensvolle E-Mail-Kommunikation

Der ?elektronische Brief“ bzw. die elektronische Mail (E-Mail) ist seit über 30 Jahren im privaten wie beruflichen Umfeld im Einsatz. Behörden, Steuerbüros, Krankenhäuser, Finanzinstitute und viele weitere Gruppen versenden und empfangen E-Mails, um Informationen auszutauschen. Innerhalb kurzer Zeit findet eine E-Mail ihren Weg vom Sender in Deutschland zum Empfänger in beispielsweise den USA. Wie funktioniert das? Und was hat es mit E-Mail-Verschlüsselung auf sich? Dieser Artikel betrachtet die grundlegende technische Funktionsweise der E-Mail sowie Hintergründe und Funktionsweise der Verschlüsselung mit S/MIME und PGP.     

Design of acoustic beam aperture modifier using gradient-index phononic crystals

This article reports the design concept of a novel acoustic beam aperture modifier using butt-jointed gradient-index phononic crystals (GRIN PCs) consisting of steel cylinders embedded in a homogeneous epoxy background. By gradually tuning the period of a GRIN PC, the propagating direction of acoustic waves can be continuously bent to follow a sinusoidal trajectory in the structure. The aperture of an acoustic beam can therefore be shrunk or expanded through change of the gradient refractive index profiles of the butt-jointed GRIN PCs. Our computational results elucidate the effectiveness of the proposed acoustic beam aperture modifier. Such an acoustic device can be fabricated through a simple process and will be valuable in applications, such as biomedical imaging and surgery, nondestructive evaluation, communication, and acoustic absorbers.     

Dauerhaftigkeit und mechanische Stabilität von Terrassendielen bei erhöhter Temperatur – Ein Werkstoffvergleich: WPC,thermisch modifiziertes Holz und Massivholz

This article deals with the differences in the long-term durability and thermal stability under load of terrace deckings from various materials. The tested materials were deckings made of wood, thermally modified timber (TMT), and wood–polymer–composites (WPC). For the determination of the test temperatures for component testing according to EN 310, the surface temperatures of the decks during a normal hot summer day were measured. A cyclic test according to EN 321 was applied to all decking materials. Afterwards the component testing was repeated. All wooden samples reveal considerable cracks, some were twisted, and few were even broken. In particular regarding the optical appearance, wood decks show advantages against the TMT decks. Some WPC decks show very fine cracks on the face, which were additionally analyzed by means of X-ray computed tomography (CT). Except for the WPC deck with higher wood content, no WPC deck revealed significant changes after the cyclic test. The CT analysis was also suitable to find cracks inside the materials and illustrate them. Thus, the whole damage inside a sample could be characterized by calculating a kind of error pattern. No considerable cracks or failures could be observed on the WPC decks.