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The male of Phaenopoma nigropunctatum O. Pickard-Cambridge, 1883 was the first time recorded from Caffraria, South Africa. During surveys in the Eastern Cape, a female was the first time sampled with a male. The general morphology of both sexes of the species is described and photographs of live specimens provided and notes on their behaviour, distribution in South Africa, and conservation are provided. &nbsp

A vast number of experiments have now shown that helium nanodroplets are an exemplary cryogenic matrix for spectroscopic investigations. The experimental techniques are well established and involve in most cases the pickup of evaporated neutral species by helium droplets. These techniques have been extended within our research group to enable nanodroplet pickup of anions or cations stored in an ion trap. By using electrospray ionization (ESI) in combination with modern mass spectrometric methods to supply ions to the trap, an immense variety of mass-to-charge selected species can be doped into the droplets and spectroscopically investigated. We have combined this droplet doping methodology with IR action spectroscopy to investigate anions and cations ranging in size from a few atoms to proteins that consist of thousands of atoms. Herein, we show examples of small complexes of fluoride anions (F−) with CO2 and H2O and carbohydrate molecules. In the case of the small complexes, novel compounds could be identified, and quantum chemistry can in some instances quantitatively explain the results. For biologically relevant complex carbohydrate molecules, the IR spectra are highly diagnostic and allow the differentiation of species that would be difficult or impossible to identify by more conventional methods.

The self-assembly of the 42-residue amyloid-β peptide, Aβ42, into fibrillar aggregates is associated with neuronal dysfunction and toxicity in Alzheimer's disease (AD) patient brains, suggesting that small molecules acting on this process might interfere with pathogenesis. Here, we present experimental evidence that the small molecule sclerotiorin (SCL), a natural product belonging to the group of azaphilones, potently delays both seeded and non-seeded Aβ42 polymerization in cell-free assays. Mechanistic biochemical studies revealed that the inhibitory effect of SCL on fibrillogenesis is caused by its ability to kinetically stabilize small Aβ42 oligomers. These structures exhibit low β-sheet content and do not possess seeding activity, indicating that SCL acts very early in the amyloid formation cascade before the assembly of seeding-competent, β-sheet-rich fibrillar aggregates. Investigations with NMR WaterLOGSY experiments confirmed the association of Aβ42 assemblies with SCL in solution. Furthermore, using ion mobility-mass spectrometry we observed that SCL directly interacts with a small fraction of Aβ42 monomers in the gas phase. In comparison to typical amyloid fibrils, small SCL-stabilized Aβ42 assemblies are inefficiently taken up into mammalian cells and have low toxicity in cell-based assays. Overall, these mechanistic studies support a pathological role of stable, β-sheet-rich Aβ42 fibrils in AD, while structures with low β-sheet content may be less relevant.

The isomeric structure of high-mannose N-glycans can significantly impact biological recognition events. Here, the utility of travelling-wave ion mobility-mass spectrometry (TW IM-MS)for isomer separation of high-mannose N-glycans is investigated. Negative ion fragmentation using collisioninduced dissociation (CID) gave more informative spectra than positive ion spectra with mas sdifferent fragment ions characterizing many of the isomers. Isomer separation by ion mobility in both ionization modes was generally limited, with the arrival time distributions (ATD) often showing little sign of isomers. However, isomers could be partially resolved by plotting extracted fragment ATDs of the diagnostic fragment ions from the negative ion spectra and the fragmentation spectra of the isomers could be extracted by using ions from limited areas of the ATD peak. In some cases, asymmetric ATDs were observed but no isomers could be detected by fragmentation. In these cases, it was assumed that conformers were being separated. Collision cross sections (CCSs) of the isomers in positive and negative fragmentation mode were estimated from TW IM -MS data using dextran glycans as calibrant. More complete CCS data were achieved in negative ion mode by utilizing the diagnostic fragment ions. Examples of isomer separations are shown for N-glycans released from the well-characterized glycoproteins chicken ovalbumin, porcine thyroglobulin and gp120 from the human immunodeficiency virus. In addition to the cross sectional data, details of the negative ion collision induced dissociation (CID) spectra of all resolved isomers are discussed.

The isomeric structure of high-mannose N-glycans can significantly impact biological recognition events. Here, the utility of travelling-wave ion mobility mass spectrometry for isomer separation of high-mannose N-glycans is investigated. Negative ion fragmentation using collision-induced dissociation gave more informative spectra than positive ion spectra with mass-different fragment ions characterizing many of the isomers. Isomer separation by ion mobility in both ionization modes was generally limited, with the arrival time distributions (ATD) often showing little sign of isomers. However, isomers could be partially resolved by plotting extracted fragment ATDs of the diagnostic fragment ions from the negative ion spectra, and the fragmentation spectra of the isomers could be extracted by using ions from limited areas of the ATD peak. In some cases, asymmetric ATDs were observed, but no isomers could be detected by fragmentation. In these cases, it was assumed that conformers or anomers were being separated. Collision cross sections of the isomers in positive and negative fragmentation mode were estimated from travelling-wave ion mobility mass spectrometry data using dextran glycans as calibrant. More complete collision cross section data were achieved in negative ion mode by utilizing the diagnostic fragment ions. Examples of isomer separations are shown for N-glycans released from the well-characterized glycoproteins chicken ovalbumin, porcine thyroglobulin and gp120 from the human immunodeficiency virus. In addition to the cross-sectional data, details of the negative ion collision-induced dissociation spectra of all resolved isomers are discussed.

Durch die Kombination von verschiedenen Trennmethoden konnten mithilfe des Freie-Elektronen-Lasers des Fritz-Haber-Instituts Infrarotspektren von größenselektierten Aggregaten von Peptidionen in der Gasphase gemessen werden. Die Spektren erlauben Rückschlüsse auf den Faltungszustand der Peptide, der von helikal zu β-Faltblatt variiert. Dieser Ansatz zur Faltungsbestimmung in Peptid- und Proteinaggregaten könnte zukünftig zum besseren Verständnis von Protein-Fehlfaltung und Aggregation und von den dadurch verursachten Krankheiten beitragen. The combination of several separation methods with the Fritz Haber Institute free electron laser has allowed to measure infrared spectra of size selected peptide-ion aggregates in the gas phase. The spectra reveal information on the peptides’ folding states, varying between helical and β-sheet. In the future, this approach of determining folding in peptide and protein aggregates can, potentially, contribute to the better understanding of protein misfolding, aggregation and the hereby caused diseases.

This technical article introduces the basic principles of electrorheological fluids. A highly dynamic servo-valve developed based on the mechanics of flow resistances, developed at the Fraunhofer Institute for Machine Tools and Forming Technology (IWU) in cooperation with the PTL Leipzig GmbH and the IMA Dresden GmbH who worked in the framework of promoting research projects by the European Regional Development Fund (ERDF) and the Free State of Saxony, will be presented.

Formgedächtnislegierungen (FGL) gehören zur Gruppe der aktiven Funktionswerkstoffe. Diese Materialien besitzen die Fähigkeit zur Energiewandlung. FGL-Drähte reagieren mit einer Kontraktionsbewegung, wenn sie bis über eine bestimmte Temperatur erwärmt werden. Die Beheizung erfolgt zweckmäßig durch einen elektrischen Strom, was die problemlose Anpassung der Leistungszufuhr ermöglicht. Diese Eigenschaften erlauben den Aufbau von Aktorsystemen mit einer außergewöhnlich hohen Energiedichte. Neben den mechanischen Eigenschaften besitzen die eingesetzten NiTiCu-Aktoren auch die Möglichkeit zum sogenannten ""Self-Sensing"". Die Änderung des elektrischen Widerstandes der Aktoren, welche durch die Langenänderung hervorgerufen wird, dient im vorliegenden Beispiel zur stufenlosen Steuerung eines Greifsystems nach dem Vorbild der menschlichen Hand. Zusätzliche Sensoren zur Positionserkennung der einzelnen Finger sind somit überflüssig. Der vorliegende Prototyp zeigt die Möglichkeiten und Grenzen der FGL-Aktoren und bietet einen Ansatz zur Ergänzung vorhandener Antriebssysteme von Fremdkraftprothesen.

Der Artikel beschreibt die Entwicklung eines hochdynamischen hydraulischen Servoventils auf Basis elektrorheologischer Flüssigkeiten (ERF). Im Gegensatz zu konventionellen elektroservohydraulischen Ventilen wird der Vorsteuerkreislauf nicht durch Torquemotoren, sondern durch sehr viel dynamischere ER Strömungswiderstände angesteuert. Diese zeichnen sich dadurch aus, dass sie durch Anlegen elektrischer Hochspannung ihren Strömungswiderstand schlagartig ändern und dadurch hochdynamisch Druckdifferenzen erzeugen, mit denen der Steuerschieber des Hauptkreislaufs angesteuert wird. Dem Anwender steht damit ein deutlich dynamischeres Ansteuerventil für Prüfstände zur Verfügung, welches es ihm ermöglicht, diesen mit höheren Frequenzen zu betreiben. Hierdurch kann beispielsweise der erhebliche Zeitaufwand für Betriebslastensimulationen an Kraftfahrzeugen reduziert werden

In the condensed phase, the peptide gramicidin S is often considered as a model system for a beta-sheet structure Here, we investigate gramicidin S free of any influences of the environment by measuring the mid-IR spectra of doubly protonated (deuterated) gramicidin S in the gas phase In the amide I (i e, C=O stretch) region, the spectra show a broad split peak between 1580 and 1720 cm(-1). To deduce structural information, the conformational space has been searched using molecular dynamics methods and several structural candidates have been further investigated at the density functional level The calculations show the importance of the interactions of the charged side-chains with the backbone, which is responsible for the lower frequency part of the amide I peak When this interaction is inhibited via complexation with two 18-crown-6 molecules, the amide I peak narrows and shows two maxima at 1653 and 1680 cm(-1) A comparison to calculations shows that for this complexed ion, four C=O groups are in an antiparallel beta-sheet arrangement Surprisingly, an analysis of the calculated spectra shows that these beta-sheet C=O groups give rise to the vibrations near 1680 cm(-1) This is in sharp contrast to expectations based on values for the condensed phase, where resonances of beta-sheet sections are thought to occur near 1630 cm(-1) The difference between those values might be caused by interactions with the environment, as the condensed phase value is mostly deduced for beta-sheet sections that are embedded in larger proteins, that interact strongly with solvent or that are part of partially aggregated species

Electrospray ionization (ESI) is the softest ionization method that is currently available and it is widely accepted, that ESI generated ions of proteins and protein assemblies at certain conditions retain characteristic aspects of their solution-state conformation. ESI mass spectrometry (MS) therefore evolved as a useful tool to obtain information on composition, stoichiometry, and dynamics of non-covalently associated protein complexes. While tertiary structure information of proteins can be obtained from ion mobility spectrometry (IMS), only a few techniques yield direct information on the secondary structure of gas-phase peptides and proteins. We present here the mid-IR spectroscopic secondary structural analysis of three de novo designed alpha-helical coiled coil model peptides and their non-covalently associated complexes in the gas-phase. The conformational stability of such coiled coil peptides in solution is primarily driven by aggregation. Isolated monomers usually remain unfolded. Two of the investigated peptides were designed to assemble into stable alpha-helical complexes in acidic solution, while the third one remains monomeric and unfolded at these conditions. Monomer ions of all three peptides show comparable photodissociation IR spectra and therefore suggest an unfolded conformation in the gas phase. in contrast, considerable C=O stretch (amide-1) and N-H bend (amide-II) band shifts have been observed for the dieters which is consistent with an elevated H-bond content. These findings provide evidence that at least a fraction of the condensed phase a.-helical structure is retained in the gas-phase coiled coil complexes. (C) 2009 Elsevier B.V. All rights reserved.