Tuning the onset voltage of resonant tunneling through InAs quantum dots by growth parameters

We investigated the size dependence of the ground state energy in self-assembled InAs quantum dots embedded in resonant tunneling diodes. Individual current steps observed in the current-voltage characteristics are attributed to resonant single-electron tunneling via the ground state of individual InAs quantum dots. The onset voltage of the first step observed is shown to decrease systematically from 200 mV to 0 with increasing InAs coverage. We relate this to a coverage-dependent size of InAs dots grown on AlAs. The results are confirmed by atomic force micrographs and photoluminescence experiments on reference samples.Comment: 3 pages, 3 figure

Redox-Rich Metallocene Tetrazene Complexes: Synthesis, Structure, Electrochemistry, and Catalysis

Thermal or photochemical metal-centered cycloaddition reactions of azidocobaltocenium hexafluoridophosphate or azidoferrocene with (cyclooctadiene)(cyclopentadienyl)cobalt- (I) afforded the first metallocenyl-substituted tetrazene cyclopentadienyl cobalt complexes together with azocobaltocenium or azoferrocene as side products. The trimetallic CpCo compounds are highly conjugated, colored, and redox-active metallo-aromatic compounds, as shown by their spectroscopic, structural, and electrochemical properties. The CpCo-tetrazenido complex with two terminally appended cobaltocene units catalyzes electrochemical proton reduction from acetic acid at a mild overpotential (0.35 V). Replacing cobaltocene with ferrocene moieties rendered the complex inactive toward catalysis.Austrian Science Fund (FWF), Christian Doppler Association (Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development), OMV, Marie Skłodowska-Curie, Deutsche Forschungsgemeinschaf

Creation of Coatings by Temperature-Controlled Polymer Deposition

In this paper, the results of the recent studies on application of lower critical solution temperature (LCST) phenomena of polymer solutions to the surface modification of flat and spherical substrates are reported. It was found that a controlled polymer deposition can be achieved upon prevailing of the LCST, a peculiar surface topology of polymer coating and particles those remarkably effective in stabilizing pigment dispersiions. Second, the finding is that the temperature induces polymer deposition as the coprecipitation of a finely dispersed component on the substrate surface. That goes along with the polymer deposition after exceeding of the LCST which in turn allows for the tailored surface modification of pigments in that particulate additiives can be incorporated into the surface modifying coating

Detection of Bronchial Neoplasia in Uranium Miners by Autofluorescence Endoscopy (SAFE-1000)

The increase in the detection rate for premalignant changes of bronchial epithelium was studied in 56 symptom-free volunteers from the risk group of Czech uranium miners (mean age 50.69 years, mean WLM 21.06 (1 Working Level Month is equal to the absorption of latent energy of 2.08 × 10–5 J/m3 in one month, i.e. 170 working hours)) by the additional employment of the System of Autofluorescence Endoscopy (SAFE-1000 Pentax) to conventional white-light bronchoscopy, comparing results with those of bronchial biopsy histopathology examination. Histopathology using hematoxylin and eosin staining confirmed intraepithelial neoplasias in 15 areas in 10 persons. White-light bronchoscopy sensitivity was 21.05%, and specificity 93.7% which an autofluorescence bronchoscopy sensitivity was 78.95% and specificity 81.89%

Profound functional and molecular diversity of mitochondria revealed by cell type-specific profiling in vivo

Mitochondria vary in morphology and function in different tissues, however little is known about their molecular diversity among cell types. To investigate mitochondrial diversity in vivo, we developed an efficient protocol to isolate cell type-specific mitochondria based on a new MitoTag mouse. We profiled the mitochondrial proteome of three major neural cell types in cerebellum and identified a substantial number of differential mitochondrial markers for these cell types in mice and humans. Based on predictions from these proteomes, we demonstrate that astrocytic mitochondria metabolize long-chain fatty acids more efficiently than neurons. Moreover, we identified Rmdn3 as a major determinant of ER-mitochondria proximity in Purkinje cells. Our novel approach enables exploring mitochondrial diversity on the functional and molecular level in many in vivo contexts

Decomposers and root feeders interactively affect plant defence in Sinapis alba

Aboveground herbivory is well known to change plant growth and defence. In contrast, effects of soil organisms, acting alone or in concert, on allocation patterns are less well understood. We investigated separate and combined effects of the endogeic earthworm species Aporrectodea caliginosa and the root feeding nematode species Pratylenchus penetrans and Meloidogyne incognita on plant responses including growth and defence metabolite concentrations in leaves of white mustard, Sinapis alba. Soil biota had a strong impact on plant traits, with the intensity varying due to species combinations. Nematode infestation reduced shoot biomass and nitrogen concentration but only in the absence of earthworms. Earthworms likely counteracted the negative effects of nematodes. Infestation with the migratory lesion-nematode P. penetrans combined with earthworms led to increased root length. Earthworm biomass increased in the presence of this species, indicating that these nematodes increased the food resources of earthworms—presumably dead and decaying roots. Nitrogen-based defence compounds, i.e. glucosinolates, did not correlate with nitrogen levels. In the presence of earthworms, concentrations of aromatic glucosinolates in leaves were significantly increased. In contrast, infection with P. penetrans strongly decreased concentrations of glucosinolates (up to 81%). Infestation with the sedentary nematode M. incognita induced aromatic glucosinolates by more than 50% but only when earthworms were also present. Myrosinase activities, glucosinolate-hydrolysing enzymes, were unaffected by nematodes but reduced in the presence of earthworms. Our results document that root-feeding nematodes elicit systemic plant responses in defence metabolites, with the responses varying drastically with nematode species of different functional groups. Furthermore, systemic plant responses are also altered by decomposer animals, such as earthworms, challenging the assumption that induction of plant responses including defence traits is restricted to herbivores. Soil animals even interact and modulate the individual effects on plant growth and plant defence, thereby likely also influencing shoot herbivore attack

Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis

open24siSelenoproteins are rare proteins among all kingdoms of life containing the 21st amino acid, selenocysteine. Selenocysteine resembles cysteine, differing only by the substitution of selenium for sulfur. Yet the actual advantage of selenolate- versus thiolate-based catalysis has remained enigmatic, as most of the known selenoproteins also exist as cysteine-containing homologs. Here, we demonstrate that selenolate-based catalysis of the essential mammalian selenoprotein GPX4 is unexpectedly dispensable for normal embryogenesis. Yet the survival of a specific type of interneurons emerges to exclusively depend on selenocysteine-containing GPX4, thereby preventing fatal epileptic seizures. Mechanistically, selenocysteine utilization by GPX4 confers exquisite resistance to irreversible overoxidation as cells expressing a cysteine variant are highly sensitive toward peroxide-induced ferroptosis. Remarkably, concomitant deletion of all selenoproteins in Gpx4cys/cys cells revealed that selenoproteins are dispensable for cell viability provided partial GPX4 activity is retained. Conclusively, 200 years after its discovery, a specific and indispensable role for selenium is provided.openIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, MarcusIngold, Irina; Berndt, Carsten; Schmitt, Sabine; Doll, Sebastian; Poschmann, Gereon; Buday, Katalin; Roveri, Antonella; Peng, Xiaoxiao; Porto Freitas, Florencio; Seibt, Tobias; Mehr, Lisa; Aichler, Michaela; Walch, Axel; Lamp, Daniel; Jastroch, Martin; Miyamoto, Sayuri; Wurst, Wolfgang; Ursini, Fulvio; Arnér, Elias S J; Fradejas-Villar, Noelia; Schweizer, Ulrich; Zischka, Hans; Friedmann Angeli, José Pedro; Conrad, Marcu