Efficient Visible-to-UV Photon Upconversion Systems Based on CdS Nanocrystals Modified with Triplet Energy Mediators

Developing high-performance visible-to-UV photon upconversion systems based on triplet–triplet annihilation photon upconversion (TTA-UC) is highly desired, as it provides a potential approach for UV light-induced photosynthesis and photocatalysis. However, the quantum yield and spectral range of visible-to-UV TTA-UC based on nanocrystals (NCs) are still far from satisfactory. Here, three different sized CdS NCs are systematically investigated with triplet energy transfer to four mediators and four annihilators, thus substantially expanding the available materials for visible-to-UV TTA-UC. By improving the quality of CdS NCs, introducing the mediator via a direct mixing fashion, and matching the energy levels, a high TTA-UC quantum yield of 10.4% (out of a 50% maximum) is achieved in one case, which represents a record performance in TTA-UC based on NCs without doping. In another case, TTA-UC photons approaching 4 eV are observed, which is on par with the highest energies observed in optimized organic systems. Importantly, the in-depth investigation reveals that the direct mixing approach to introduce the mediator is a key factor that leads to close to unity efficiencies of triplet energy transfer, which ultimately governs the performance of NC-based TTA-UC systems. These findings provide guidelines for the design of high-performance TTA-UC systems toward solar energy harvesting.     

N-Heterocyclization in Gliotoxin Biosynthesis is Catalyzed by a Distinct Cytochrome P450 Monooxygenase

Gliotoxin and related epidithiodiketopiperazines (ETP) from diverse fungi feature highly functionalized hydroindole scaffolds with an array of medicinally and ecologically relevant activities. Mutation analysis, heterologous reconstitution, and biotransformation experiments revealed that a cytochrome P450 monooxygenase (GliF) from the human-pathogenic fungus Aspergillus fumigatus plays a key role in the formation of the complex heterocycle. In vitro assays using a biosynthetic precursor from a blocked mutant showed that GliF is specific to ETPs and catalyzes an unprecedented heterocyclization reaction that cannot be emulated with current synthetic methods. In silico analyses indicate that this rare biotransformation takes place in related ETP biosynthetic pathways.     

Building up PtII−Thiosemicarbazone−Lysine−sC18 Conjugates

Three chiral tridentate N^N^S coordinating pyridine-carbaldehyde (S)-N4-(α-methylbenzyl)thiosemicarbazones (HTSCmB) were synthesised along with lysine-modified derivatives. One of them was selected and covalently conjugated to the cell-penetrating peptide sC18 by solid-phase peptide synthesis. The HTSCmB model ligands, the HTSCLp derivatives and the peptide conjugate rapidly and quantitatively form very stable Pt^II chlorido complexes [Pt(TSC)Cl] when treated with K₂PtCl₄ in solution. The Pt(CN) derivatives were obtained from one TSCmB model complex and the peptide conjugate complex through Cl⁻→CN⁻ exchange. Ligands and complexes were characterised by NMR, IR spectroscopy, HR-ESI-MS and single-crystal XRD. Intriguingly, no decrease in cell viability was observed when testing the biological activity of the lysine-tagged HdpyTSCLp, its sC18 conjugate HdpyTSCL-sC18 or the PtCl and Pt(CN) conjugate complexes in three different cell lines. Thus, given the facile and effective preparation of such Pt-TSC-peptide conjugates, these systems might pave the way for future use in late-stage labelling with Pt radionuclides and application in nuclear medicine.     

Combined software and hardware fault injection vulnerability detection

Innovations in Systems and Software Engineering - Fault injection is a well-known method to test the robustness and security vulnerabilities of software. Software-based and hardware-based...     

What determines the take-over time? An integrated model approach of driver take-over after automated driving

In recent years the automation level of driver assistance systems has increased continuously. One of the major challenges for highly automated driving is to ensure a safe driver take-over of the vehicle guidance. This must be ensured especially when the driver is engaged in non-driving related secondary tasks. For this purpose it is essential to find indicators of the driver’s readiness to take over and to gain more knowledge about the take-over process in general.     

Relay and sequential cropping corn with winter oilseed crops in northern climates

Nutrient Cycling in Agroecosystems - Winter oilseed crops camelina [Camelina sativa (L.) Crantz] and field pennycress (Thlaspi arvense L.) are potential candidates for diversifying the...     

Neomycin Inhibition of (+)-7-Iso-Jasmonoyl-L-Isoleucine Accumulation and Signaling

The majority of plant defenses against insect herbivores are coordinated by jasmonate (jasmonic acid, JA; (+)-7-iso-jasmonoyl-L-isoleucine, JA-Ile)-dependent signaling cascades. Insect feeding and mimicking herbivory by application of oral secretions (OS) from the insect induced both cytosolic Ca²⁺ and jasmonate-phytohormone elevation in plants. Here it is shown that in Arabidopsis thaliana upon treatment with OS from lepidopteran Spodoptera littoralis larvae, the antibiotic neomycin selectively blocked the accumulation of OS-induced Ca²⁺ elevation and level of the bioactive JA-Ile, in contrast to JA level. Furthermore, neomycin treatment affected the downstream expression of JA-Ile-responsive genes, VSP2 and LOX2, in Arabidopsis. The neomycin-dependent reduced JA-Ile level is partially due to increased CYP94B3 expression and subsequent JA-Ile turn-over to12-hydroxy-JA-Ile. It is neither due to the inhibition of the enzymatic conjugation process nor to substrate availability. Thus, blocking Ca²⁺ elevation specifically controls JA-Ile accumulation and signaling, offering an insight into role of calcium in defense against insect herbivory.     

Multicriteria optimization as enabler for Sustainable Ceramic Matrix Composites

Over the past 40 years, development of Ceramic Matrix Composites (CMCs) has focused mainly on the improvement of material performance and optimization of cost-efficient production routes. Recently, more fields of application have opened up for CMCs, in which environmental impacts are relevant. These impacts have barely been investigated so far but receive growing interest due to increasing awareness of the environmental consequences. Our innovative approach frames material properties in relation to environmental impacts (e.g., global warming potential in CO₂ emission) by varying process parameters to balance optimum performance against environmental considerations. First, the process of wet filament winding has been investigated up to the Carbon Fiber Reinforced Plastic (CFRP) state by changing both the curing and tempering temperatures. During the production of CFRP plates, mass and energy flows were tracked in each step. Three point-bending and interlaminar shear tests have been performed on the resulting samples to identify basic mechanical properties. The environmental impacts are determined by a cradle-to-gate Life Cycle Assessment (LCA), using the software SimaPro. The resulting tradeoffs between mechanical properties and environmental impacts show nonlinear behavior, thus revealing optimum points above which improved mechanical properties are associated with significantly higher CO₂ emissions.     

Controllable Broadband Absorption in the Mixed Phase of Metamagnets

Materials with broad absorption bands are highly desirable for electromagnetic filtering and processing applications, especially if the absorption can be externally controlled. Here, a new class of broadband‐absorption materials is introduced. Namely, layered metamagnets exhibit an electromagnetic excitation continuum in the magnetic‐field‐induced mixed ferro‐ and anti­ferromagnetic phase. Employing a series of complementary experimental techniques involving neutron scattering, muon spin relaxation, specific heat, ac and dc magnetization measurements, and electron magnetic resonance, a detailed magnetic phase diagram of Cu₃Bi(SeO₃)₂O₂Br is determined and it is found that the excitations in the mixed phase extend over at least ten decades of frequency. The results, which reveal a new dynamical aspect of the mixed phase in metamagnets, open up a novel approach to controllable microwave filtering.