766 research outputs found
Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphigidae) and its natural host Nicotiana attenuata. VIII. An unbiased GCxGC-ToFMS analysis of the plant´s elicited volatile emissions
Treating wounds in Nicotiana attenuata leaves with Manduca sexta oral secretions (W+OS) mimics most changes elicited by M. sexta herbivory, but an unbiased analysis of the effect of the different OS constituents on volatile emissions is lacking. We used two-dimensional gas chromatography/time-of-flight (GCxGC-ToF) mass spectrometry combined with multivariate statistics to parse volatiles into regulatory patterns. Volatiles released by wounding alone and by the alkalinity of OS were assessed by applying a buffer known to mimic the pH-mediated changes of OS elicitation (pectin methyl esterase activation and methanol release). The activities of fatty acid amino acid conjugates, well-known elicitors of antiherbivore defenses, and of 2-hydroxyoctadecatrienoic acid, a newly discovered signal in OS, were determined. Approximately 400 analytes were detected after deconvolution and alignment of GCxGC data; 35 volatiles were significantly regulated upon W+OS. Two-thirds of these were specifically regulated by OS, being either amplified (most terpenoids and certain hexenylesters) or strongly repressed (many short-chain alcohols and some aromatic and hexenylester derivatives). Fatty acid amino acid conjugates played a central role in this pattern of regulation, since they induced the emission of half of OS-elicited volatiles and inhibited the production of almost all OS-repressed volatiles; 2-hydroxyoctadecatrienoic acid influenced emission of trans-α-bergamotene, while other unknown OS constituents amplified hexenylester production. We conclude that the complex bouquet of herbivory-elicited volatiles results from the complex modulations of the wound response by diverse cues found in OS. This work also underscores the value of ultra-high-resolution GCxGC-ToF analysis combined with the nontargeted mining of the resulting data
Smart Institutions for Smart Cities
Smart cities employ creativity of the population for innovations supporting social and economic development. In this context, this paper explores the role of framework conditions on special supply effects of university hospitals, which can invite further research institutions for intense collaboration, thereby stimulating innovations. The case study, comparing a hospital in Russia with one in Germany, is based on the concept of the employment multiplier. The results show that exogenously given, but, more importantly, also modifiable framework conditions lead to large differences regarding the employment multiplier. Thus, it should be the concern of smart cities to make smart use of their institutions, such as university hospitals, by adjusting the conditions, under which they are operating. © 2018 Institute of Physics Publishing. All rights reserved
Dirac cones in two-dimensional borane
We introduce two-dimensional borane, a single-layered material of BH
stoichiometry, with promising electronic properties. We show that, according to
Density Functional Theory calculations, two-dimensional borane is semimetallic,
with two symmetry-related Dirac cones meeting right at the Fermi energy .
The curvature of the cones is lower than in graphene, thus closer to the ideal
linear dispersion. Its structure, formed by a puckered trigonal boron network
with hydrogen atoms connected to each boron atom, can be understood as
distorted, hydrogenated borophene (Science \textbf{350}, 1513 (2015)). Chemical
bonding analysis reveals the boron layer in the network being bound by
delocalized four-center two-electron bonds. Finally, we suggest
high-pressure could be a feasible route to synthesise two-dimensional borane.Comment: 5 pages, 3 figures, 1 tabl
Chemical composition and bioactivity of essential oils and extracts from Oregano from Madeira Island, Portugal
In the course of ongoing investigations on polymorphic Lamiaceae species, we
studied Origanum vulgare spp. virens growing wild in several locations of Madeira
Island, Portugal. Variation in essential oil composition with climate conditions was
studied. The antimicrobial activity of the various essential oils was determined
against 10 strains of bacteria and yeasts, usually found as human pathogenic or food
contaminants. The essential oils inhibited all the bacteria tested excepting for P.
aeruginosa. The most sensitive microorganism was M. smegmatis with MIC = 25 µg
ml-1 for two of the oils. The results of this study suggest a potential application of
these oils in preventing the human pathogenic and food contaminant
microorganisms growth. Radical scavenging capacity of essential oils and solvent
extract (hexane, chloroform, ethyl acetate and methanol) were also determined,
since interest of oregano resides in both non polar and polar fractions, all known by
their very high antioxidant activity. From the hexane fraction, we obtained a large
amount of 1-hexacosanol, C26H54O, a long chain alcohol, which was previously
extracted in the non-esterified form only from Hygrophila erecta.info:eu-repo/semantics/publishedVersio
Second Cluster Integral and Excluded Volume Effects for the Pion Gas
The quantum mechanical formula for Mayer's second cluster integral for the
gas of relativistic particles with hard-core interaction is derived. The proper
pion volume calculated with quantum mechanical formula is found to be an order
of magnitude larger than its classical evaluation.
The second cluster integral for the pion gas is calculated in quantum
mechanical approach with account for both attractive and hard-core repulsive
interactions. It is shown that, in the second cluster approximation, the
repulsive pion-pion-interactions as well as the finite width of resonances give
important but almost canceling contributions. In contrast, an appreciable
deviation from the ideal gas of pions and pion resonances is observed beyond
the second cluster approximation in the framework of the Van der Waals
excluded-volume model.Comment: 29 pages, Latex, 9 PS-figure
Optogalvanic Spectroscopy of Metastable States in Yb^{+}
The metastable ^{2}F_{7/2} and ^{2}D_{3/2} states of Yb^{+} are of interest
for applications in metrology and quantum information and also act as dark
states in laser cooling. These metastable states are commonly repumped to the
ground state via the 638.6 nm ^{2}F_{7/2} -- ^{1}D[5/2]_{5/2} and 935.2 nm
^{2}D_{3/2} -- ^{3}D[3/2]_{1/2} transitions. We have performed optogalvanic
spectroscopy of these transitions in Yb^{+} ions generated in a discharge. We
measure the pressure broadening coefficient for the 638.6 nm transition to be
70 \pm 10 MHz mbar^{-1}. We place an upper bound of 375 MHz/nucleon on the
638.6 nm isotope splitting and show that our observations are consistent with
theory for the hyperfine splitting. Our measurements of the 935.2 nm transition
extend those made by Sugiyama et al, showing well-resolved isotope and
hyperfine splitting. We obtain high signal to noise, sufficient for laser
stabilisation applications.Comment: 8 pages, 5 figure
Electronic stress tensor analysis of hydrogenated palladium clusters
We study the chemical bonds of small palladium clusters Pd_n (n=2-9)
saturated by hydrogen atoms using electronic stress tensor. Our calculation
includes bond orders which are recently proposed based on the stress tensor. It
is shown that our bond orders can classify the different types of chemical
bonds in those clusters. In particular, we discuss Pd-H bonds associated with
the H atoms with high coordination numbers and the difference of H-H bonds in
the different Pd clusters from viewpoint of the electronic stress tensor. The
notion of "pseudo-spindle structure" is proposed as the region between two
atoms where the largest eigenvalue of the electronic stress tensor is negative
and corresponding eigenvectors forming a pattern which connects them.Comment: 22 pages, 13 figures, published online, Theoretical Chemistry
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