Luminescence intensity and dopant concentration in AlN:Tb

The luminescence intensity of Tb³⁺ embedded in sputter deposited and subsequently annealed AlN shows strong concentration dependence. The intensity of the characteristic green luminescence of Tb³⁺ rises at low concentrations with rising concentration. At higher concentrations, strong concentration quenching occurs. The optimum concentration range of Tb³⁺ in AlN was observed to range between 2.5 at% Tb and 3.6 at% Tb. The experimentally evaluated concentration dependence results can be described by a rate equation approach based on available models of luminescence quenching.     

A superoleophobic textile repellent towards impacting drops of alkanes

A commercially available polyester fabric has been rendered superoleophobic by coating with silicone nanofilaments and subsequent plasma fluorination. The treated samples show outstanding oil-repellency. They achieve the highest possible oil-repellency grade of 8, repel impacting drops of alkanes and show a plastron layer in hexadecane. The oil repellency is shown to depend on the topography of the silicone nanofilament coating.     

Electronic Structure and Absorption Spectra of Biferrocenyl and Bisfulvalenide Diiron Radical Cations: Detection and Assignment of New Low‐Energy Transitions

New transitions : Low‐energy electronic transitions have been detected spectroscopically in the Fe^II–Fe^III mixed‐valent biferrocenyl radical cation, but are absent in the spectra of the neutral analogue. They have been assigned by time‐dependent DFT calculations (squares in figure). Analogous investigations were performed for the bisfulvalenide Fe^II–Fe^III radical cation.

     

Rapid Assessment of the Reaction‐Condition‐Based Sensitivity of Chemical Transformations

A systematic, user‐friendly assessment tool that delivers a clear overview of the sensitivity of reactions to key parameters is highly desirable. Herein, the development of such a method is described. The intuitive, standardized presentation of the results in a radar diagram enables the sensitivity of a protocol to be rapidly assessed. This method was applied to five different visible‐light‐mediated photochemical reactions, and the results were correlated to the underlying mechanism. Ultimately, we believe that this assessment will help to increase the uptake of new synthetic methods and their reproducibility.     

Cyclopropanol Warhead in Malleicyprol Confers Virulence of Human‐ and Animal‐Pathogenic Burkholderia Species

Burkholderia species such as B. mallei and B. pseudomallei are bacterial pathogens causing fatal infections in humans and animals (glanders and melioidosis), yet knowledge on their virulence factors is limited. While pathogenic effects have been linked to a highly conserved gene locus (bur/mal) in the B. mallei group, the metabolite associated to the encoded polyketide synthase, burkholderic acid (syn. malleilactone), could not explain the observed phenotypes. By metabolic profiling and molecular network analyses of the model organism B. thailandensis, the primary products of the cryptic pathway were identified as unusual cyclopropanol‐substituted polyketides. First, sulfomalleicyprols were identified as inactive precursors of burkholderic acid. Furthermore, a highly reactive upstream metabolite, malleicyprol, was discovered and obtained in two stabilized forms. Cell‐based assays and a nematode infection model showed that the rare natural product confers cytotoxicity and virulence.     

Tetrahydroxy‐Perylene Bisimide Embedded in a Zinc Oxide Thin Film as an Electron‐Transporting Layer for High‐Performance Non‐Fullerene Organic Solar Cells

By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO‐PBI ligands were obtained which upon deprotonation can complex Zn^II ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic–inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO: HO‐PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non‐fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 % for a non‐fullerene based organic solar cell.     

Metathesis at an Implausible Site: A Formal Total Synthesis of Rhizoxin D

The new approach to the anticancer agent rhizoxin D described herein does not cohere with the conventional logic of metathesis, according to which macrocycles are best closed at a disubstituted olefinic site; rather, the trisubstituted C11?C12 alkene flanked by an allylic ‐OH group served as the pivot point for synthesis. This motif was attained in good yield and excellent selectivity by a sequence of alkyne metathesis, trans‐hydrostannation and cross coupling. Because the exact same substructure is prominently featured in numerous other natural products, the underpinning strategy, though unusual, might bear more general relevance.     

On vibration mitigation and energy harvesting of a non-ideal system with autoparametric vibration absorber system

This paper demonstrates that vibration mitigation and energy harvesting can be achieved simultaneously by using of an electricity-generating from autoparametric vibration absorber system (AVAS) and non-ideal system (NIS). The NIS consists of a simple portal frame excited by a small dc motor with eccentric mass, with limited power supply and located on the top. The AVAS consists of a cantilever beam with tip mass parallel coupled to NIS. A piezoelectric material is considered for energy harvesting installed in the base of the AVAS and an electric circuit is connected to the piezoelectric material in order to produce voltage output. Several numerical simulations were carried out focusing on the passage through the resonance of NIS, when the motor rotational frequency is near the portal frame natural frequency and when the non-ideal subsystem frequency is approximately twice the absorber beam frequency (two-to-one internal resonance). The results showed the existence of Sommerfeld effect in NIS and saturation phenomenon in the NIS–AVAS.     

Speeding up thermalisation via open quantum system variational optimisation

Optimising open quantum system evolution is an important step on the way to achieving quantum computing and quantum thermodynamic tasks. In this article, we approach optimisation via variational principles and derive an open quantum system variational algorithm explicitly for Lindblad evolution in Liouville space. As an example of such control over open system evolution, we control the thermalisation of a qubit attached to a thermal Lindbladian bath with a damping rate γ. Since thermalisation is an asymptotic process and the variational algorithm we consider is for fixed time, we present a way to discuss the potential speedup of thermalisation that can be expected from such variational algorithms.