Here we present electrochemically grown ultrathin platinum nanowires and demonstrate that their morphology and crystalline structure can be tuned by the waveform of the alternating voltage applied to ...the microelectrodes. The structure of the nanowires was analyzed by scanning and transmission electron microscopy. The voltage signal, applied to grow the nanowires, consisted of several Fourier components of a square-shaped wave. We observed that, depending on the number of Fourier components, the morphology of the nanowires changed from branched dendritic-like patterns to straight wires and the wire crystallinity changed from polycrystalline to highly oriented growth with the 111 direction of platinum crystallites along the nanowire axis. We propose a simple model to explain this intriguing observation.
We studied human melody perception and production in a songbird in the light of current concepts from the cognitive neuroscience of music. Bullfinches are the species best known for learning melodies ...from human teachers. The study is based on the historical data of 15 bullfinches, raised by 3 different human tutors and studied later by Jürgen Nicolai (
JN
) in the period 1967–1975. These hand-raised bullfinches learned
human folk melodies
(sequences of 20–50 notes) accurately. The tutoring was interactive and variable, starting before fledging and JN continued it later throughout the birds’ lives. All 15 bullfinches learned to sing alternately melody modules with JN (
alternate singing
). We focus on the aspects of note sequencing and timing studying song variability when singing the learned melody alone and the accuracy of listening-singing interactions during alternatively singing with JN by analyzing song recordings of 5 different males. The following results were obtained as follows: (1) Sequencing: The note sequence variability when singing alone suggests that the bullfinches retrieve the note sequence from the memory as different sets of note groups (=modules), as chunks (sensu Miller in Psychol Rev 63:81–87,
1956
). (2) Auditory–motor interactions, the coupling of listening and singing the human melody: Alternate singing provides insights into the bird’s brain melody processing from listening to the actually whistled part of the human melody by JN to the bird’s own accurately singing the consecutive parts. We document how variable and correctly bullfinches and JN alternated in their singing the note sequences. Alternate singing demonstrates that melody-singing bullfinches did not only follow attentively the just whistled note contribution of the human by auditory feedback, but also could synchronously anticipate singing the consecutive part of the learned melody. These data suggest that both listening and singing may depend on a single learned human melody representation (=coupling between perception and production).
ZusammenfassungDie Analysen von menschlichen Melodien und von Gesangsstrophen von Kanarienvögeln, welche Gimpel während ihrer Jugendentwicklung gelernt hatten, ergeben nicht nur einen Einblick, wie ...genau Singvögel Rhythmen und Tonintervalle von Vorbildern übernehmen können, sondern erlauben auch Rückschlüsse, ob Singvögel Lautfolgen lediglich als eine voneinander unabhängige Reihenfolge von Lauten oder entsprechend der Melodiewahrnehmung beim Menschen als melodische Einheit wahrnehmen können. Folgende Ergebnisse werden eingehend dokumentiert: (1) Ein Gimpel erlernte die 45 Noten umfassenden, gekürzten Melodien „Im tiefen Böhmerwald” und „Abend wird es wieder”, sowohl im Rhythmus als auch in den Intervallschritten weitgehend vorbildgetreu. Der von einem Kanarienvogel aufgezogene Gimpel erlernte 13 von der Gimpelnorm sehr stark abweichende Lautgruppen in der vom Kanarienvogel gesungenen Folgebeziehung. (2) Der menschliche Lehrer und der Gimpel singen die Melodie in einer unterschiedlichen absoluten Tonhöhe. Der Gimpel transponiert die Melodie, d. h. er erhöht die absolute Frequenz der einzelnen Töne um einen Halbtonschritt. Während der menschliche Lehrer von Strophe zu Strophe in der absoluten Tonhöhe der einzelnen Noten variiert, in einer ungefähren Tonlage von As-Dur pfeift, singt der Gimpel die identischen Noten in den Wiederholungen sehr konstant in A-Dur. Das Transponieren liefert den Nachweis, dass der Gimpel Lautfolgen nicht nur entsprechend der menschlichen Wahrnehmung als Melodie verarbeiten, sondern auch entsprechend pfeifen kann, obwohl bei den Singvögeln die für die Analyse der Beziehungen zwischen aufeinanderfolgenden Lauten wichtigen Gehirnzentren des Menschen völlig fehlen. (3) Der Vergleich der Noten- und Pausenwerte der einander entsprechenden Laute zwischen dem Vorbild und der Nachahmung zeigt, dass Gimpel sowohl die exakte Tonhöhe und die Tonhöhenintervalle zwischen aufeinanderfolgenden Tönen, als auch die den Melodierhythmus bestimmende Lautdauer für jeden Laut genau auf die Vorgabe durch das Vorbild abstimmen können. Für diese Leistung wird der an der Lauterzeugung beteiligte Atemstrom genau an die jeweilige Dauer der unterschiedlich lange ausgehaltenen Note angepasst.
An analysis of thin-wire antennas and scatterers using quadratic spline-based expansion and weighting functions within the method of moments (MoM) is presented. So-called quadratic B-splines are ...introduced as a generalisation of the well-known rectangular and triangle expansion functions. The thin-wire version of the electric-field integral equation (EFIE) is solved by the method of moments (MoM) using Galerkin's method. The described procedure results in a symmetrical structure of the impedance matrix, which allows the application of symmetric solvers with the benefit of a very effective solving procedure. Due to the choice of the expansion and weighting functions the results are very precise for near-fields and points near the structure. It become possible to investigate structures with very small separations between the wires. Numerical examples demonstrate the suitability of the method for the EMC-analysis and show the advantages of a reduced solving time in the analysis of large systems and a lower limit for the shortest separation between two wires.
In a number of gram-positive bacteria, including Listeria, the general stress response is regulated by the alternative sigma factor B (SigB). Common stressors which lead to the activation of SigB and ...the SigB-dependent regulon are high osmolarity, acid and several more. Recently is has been shown that also blue and red light activates SigB in Bacillus subtilis.
By qRT-PCR we analyzed the transcriptional response of the pathogen L. monocytogenes to blue and red light in wild type bacteria and in isogenic deletion mutants for the putative blue-light receptor Lmo0799 and the stress sigma factor SigB. It was found that both blue (455 nm) and red (625 nm) light induced the transcription of sigB and SigB-dependent genes, this induction was completely abolished in the SigB mutant. The blue-light effect was largely dependent on Lmo0799, proving that this protein is a genuine blue-light receptor. The deletion of lmo0799 enhanced the red-light effect, the underlying mechanism as well as that of SigB activation by red light remains unknown. Blue light led to an increased transcription of the internalin A/B genes and of bacterial invasiveness for Caco-2 enterocytes. Exposure to blue light also strongly inhibited swimming motility of the bacteria in a Lmo0799- and SigB-dependent manner, red light had no effect there.
Our data established that visible, in particular blue light is an important environmental signal with an impact on gene expression and physiology of the non-phototrophic bacterium L. monocytogenes. In natural environments these effects will result in sometimes random but potentially also cyclic fluctuations of gene activity, depending on the light conditions prevailing in the respective habitat.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PASEF multiplies the sequencing speed without any loss in sensitivity and is implemented in the timsTOF Pro instrument introduced here. Sequencing speeds above 100 Hz enable single run proteome ...analysis at a depth of 6000 proteins, making the instrument particularly attractive for rapid and highly sensitive proteomics. Collisional cross sections can be determined with up to 0.1% precision and acquired on a scale of 100,000s, which opens exciting areas for proteomics exploration.
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Highlights
•Online PASEF achieves greater than 100 MS/MS per second at full sensitivity.•Accurate label-free quantification of over 6000 proteins in 2 h.•High throughput demonstrated on 50 ng digests measured in 5 min.•High-precision determination of 100,000 peptide collisional cross sections.
In bottom-up proteomics, peptides are separated by liquid chromatography with elution peak widths in the range of seconds, whereas mass spectra are acquired in about 100 microseconds with time-of-flight (TOF) instruments. This allows adding ion mobility as a third dimension of separation. Among several formats, trapped ion mobility spectrometry (TIMS) is attractive because of its small size, low voltage requirements and high efficiency of ion utilization. We have recently demonstrated a scan mode termed parallel accumulation - serial fragmentation (PASEF), which multiplies the sequencing speed without any loss in sensitivity (Meier et al., PMID: 26538118). Here we introduce the timsTOF Pro instrument, which optimally implements online PASEF. It features an orthogonal ion path into the ion mobility device, limiting the amount of debris entering the instrument and making it very robust in daily operation. We investigate different precursor selection schemes for shotgun proteomics to optimally allocate in excess of 100 fragmentation events per second. More than 600,000 fragmentation spectra in standard 120 min LC runs are achievable, which can be used for near exhaustive precursor selection in complex mixtures or accumulating the signal of weak precursors. In 120 min single runs of HeLa digest, MaxQuant identified more than 6,000 proteins without matching to a library and with high quantitative reproducibility (R > 0.97). Online PASEF achieves a remarkable sensitivity with more than 2,500 proteins identified in 30 min runs of only 10 ng HeLa digest. We also show that highly reproducible collisional cross sections can be acquired on a large scale (R > 0.99). PASEF on the timsTOF Pro is a valuable addition to the technological toolbox in proteomics, with a number of unique operating modes that are only beginning to be explored.
Proper activation of macrophages (Mφ) in the inflammatory phase of acute wound healing is essential for physiological tissue repair. However, there is a strong indication that robust Mφ inflammatory ...responses may be causal for the fibrotic response always accompanying adult wound healing. Using a complementary approach of in vitro and in vivo studies, we here addressed the question of whether mesenchymal stem cells (MSCs)—due to their anti-inflammatory properties—would control Mφ activation and tissue fibrosis in a murine model of full-thickness skin wounds. We have shown that the tumor necrosis factor-α (TNF-α)-stimulated protein 6 (TSG-6) released from MSCs in co-culture with activated Mφ or following injection into wound margins suppressed the release of TNF-α from activated Mφ and concomitantly induced a switch from a high to an anti-fibrotic low transforming growth factor-β1 (TGF-β1)/TGF-β3 ratio. This study provides insight into what we believe to be a previously undescribed multifaceted role of MSC-released TSG-6 in wound healing. MSC-released TSG-6 was identified to improve wound healing by limiting Mφ activation, inflammation, and fibrosis. TSG-6 and MSC-based therapies may thus qualify as promising strategies to enhance tissue repair and to prevent excessive tissue fibrosis.
Covalent attachment of synthetic polymers to proteins, known as protein–polymer conjugation, is currently one of the main approaches for improving the physicochemical properties of these ...biomolecules. The most commonly employed polymer is polyethylene glycol (PEG), as evidenced by extensive research and clinical track records for its use in biopharmaceuticals. However, the occurrence of allergic reactions or hypersensitivity and the discovery of PEG antibodies, on the one hand, and the rise of controlled polymerization techniques and novel monomers, on the other hand, have been driving the search for alternative polymers for bioconjugation. The present study describes the synthesis, purification, and properties of conjugates of lysozyme with poly(N-acryloylmorpholine) (PNAM) and poly(oligoethylene glycol methyl ether methacrylate) (POEGMA). Particularly, conjugate species with distinct conjugation degrees are investigated for their residual activity, aggregation behavior, and solubility, by using a high-throughput screening approach. Our study showcases the importance of evaluating conjugates obtained by nonsite-specific modification through isolated species with discrete degrees of conjugation rather than on the batch level. Monovalent conjugates with relatively low molar mass polymers displayed equal or even higher activity than the native protein, while all conjugates showed an improved protein solubility. To achieve a comparable effect on solubility as with PEG, PNAM and POEGMA of higher molar masses were required.
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