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11.
In this issue of Chemistry & Biology, Morón et al. [1] report that Rhizobium tropici CIAT899 produces different Nod factors in response to flavonoid induction under differing environmental conditions. This unanticipated environmental dependence has implications for altering or potentially improving the host-bacteria interaction in bean nodulation. 相似文献
12.
Enamines 8a-e could be chlorinated by equimolar amounts of N-chlorosuccinimide (9) generating monochloroenamines 10a-e; 10a and 10d were isolated as pure substances. Two equivalents of 9 afforded the dichloroenamines 12a,c from 8a,c. Interaction of the chlorinated enamines 10a-e and 12a,c with cyanide gave morpholino-azabicyclohexane derivatives. 10a-d, thereby, led to exo-cyano-isomers lla-c; 12a,c generated endo-cyano compounds 13a,c. In the case of the ethoxycarbonylated chloroenamine 10e a mixture of diastereomeric products 11e and 14e resulted from the analogous reaction. Reduction of 11a and 14e with lithium aluminum hydride produced a pair of diastereomeric triamines 15 and 16. A tricyclic diazasystem 19 was formed from the reaction of cyanide with the carbamoylated chloroenamine 18. Monochloroenamine 10a and dichloroenamine 12a showed a significant mutagenic behaviour in the Ames test. 相似文献
13.
The evaporation of water drops with radii approximately 20 microm was investigated experimentally by depositing them onto atomic force microscope (AFM) cantilevers and measuring the deflection versus time. Because of the surface tension of the liquid, the Laplace pressure inside the drop, and the change of interfacial stress at the solid-liquid interface, the cantilever is deflected by typically a few hundred nanometers. The experimental results are in accordance with an analytic theory developed. The evaporation process could be monitored with high accuracy even at the last stage of evaporation because (1) cantilever deflections can be measured with nanometer resolution and (2) the time resolution, given by the inverse of the resonance frequency of the cantilever of approximately 0.3 ms, is much faster than the typical evaporation time of 1 s. Experimental results indicate that evaporation of the last thin layer of water is significantly slower than the rest of the drop, which can be due to surface forces. This drop-on-cantilever system can also be used to analyze the drop impact dynamics on a surface and to determine the spring constant of cantilevers. 相似文献
14.
Lambert C Nöll G Zabel M Hampel F Schmälzlin E Bräuchle C Meerholz K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(17):4232-4239
Two highly substituted azulene derivatives were synthesised by Pd-mediated dimerisation from the corresponding tolan species. One azulene derivative (2) has donor functionalities (dianisylaminophenyl and dianisylamino) in the 1-, 2-, 3- and 6-positions, while the other (1) has donors (dianisylaminophenyl) in the 2- and 6-positions and acceptors (nitrophenyl) in the 1- and 3-positions. Each azulene derivative shows strong bond length alternation in the solid state, determined by X-ray crystal analysis, and an intense CT band around 450-500 nm in its UV/Vis spectrum. The first-order hyperpolarisability of 1 and of 2 was measured by hyper-Rayleigh scattering and is about that of disperse red DR1. Both azulene derivatives show multiple oxidation processes. The intramolecular adiabatic ET behaviour of the mixed valence radical cations of 1 and of 2 was investigated by UV/Vis/NIR spectroelectrochemistry. The intervalence-CT band of 1(+) could be analysed by the Generalised Mulliken-Hush theory, which yields an electronic coupling V=1140 cm(-1) for the optically induced adiabatic hole transfer. 相似文献
15.
Allylic nitro compounds undergo relatively clean [2,3] sigmatropic rearrangement upon heating in refluxing 1,2-dichlorobenzene in the presence of DABCO to give the corresponding allylic alcohols via the intermediate allylic nitrite. [reaction: see text] 相似文献
16.
Horst Elmar Winkelnkemper 《Annals of Global Analysis and Geometry》1992,10(3):209-218
Let
t
be the flow (parametrized with respect to arc length) of a smooth unit vector field v on a closed Riemannian manifold M
n
, whose orbits are geodesics. Then the (n-1)-plane field normal to v, v, is invariant under d
t
and, for each x M, we define a smooth real function
x
(t) : (1 +
i
(t)), where the i(t) are the eigenvalues of AA
T, A being the matrix (with respect to orthonormal bases) of the non-singular linear map d2t
, restricted to v at the point x
-t M
n.Among other things, we prove the
Theorem (Theorem II, below). Assume v is also volume preserving and that
x
'
(t) 0 for all x M and real t; then, if
x
t
: M M is weakly missng for some t, it is necessary that vx 0 at all x M. 相似文献
17.
Michael Chariss Andrea Zickgraf Heike Stenger Elmar Bru Cristelle Desmarquet Martin Drger Silke Gerstmann Dainis Dakternieks James Hook 《Polyhedron》1998,17(25-26)
44 members of thecompound series Ph4−nMRn (M=Si, Ge, Sn, Pb; R=o-, m-, p-Tol; n=0–4) were synthesized (15 newcompounds). The crystal structures of Ph3Sn (o-Tol) and PhSn (o-Tol)3 were determined and compared to 16 known structures. Subject to the distanced (M–C), an interplay between through-space π–π repulsion and π–σ attraction leads to either elongated or compressed tetrahedral geometry. 29 Si-, 119 Sn- and 207 Pb-NMR chemical shifts were determined in solution and in the solid state. 73 Ge chemical shifts were measured only in solution. Anupfield or downfield sagging of the chemical shifts along each series is rationalized in terms of a π–σcharge transfer which is constrained by torsion of the aromatic groups. 相似文献
18.
Jakob Woisetschl?ger Adam D. Wexler Gert Holler Mathias Eisenhut Karl Gatterer Elmar C. Fuchs 《Experiments in fluids》2012,52(1):193-205
When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol,
a horizontal bridge forms between the two beakers. By repeating a version of Pellat’s experiment, it is shown that a horizontal
bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon
called a ‘floating water bridge’ can be explained by the gradient of Maxwell pressure, replenishing the liquid within the
bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges.
The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds
in the vicinity of the electrodes, is also discussed by two further experiments. 相似文献
19.
Rudolf Gompper Jan-Gerd Hansel Joachim Hock Kurt Polborn Elmar Dormann Hubert Winter 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):521-525
Abstract Novel dithiolene metal complexes, some of which absorb in the near infrared, and tetrathiafulvalenes, in particular tetraiodotetrathia- fulvalene, have been prepared, and their magnetic properties studied. 相似文献
20.
Dr. Elmar Kataev Daniel Wechsler Prof. Federico J. Williams Julia Köbl Dr. Natalia Tsud Dr. Stefano Franchi Prof. Hans-Peter Steinrück Dr. Ole Lytken 《Chemphyschem》2020,21(20):2293-2300
Thin-film growth of molecular systems is of interest for many applications, such as for instance organic electronics. In this study, we demonstrate how X-ray photoelectron spectroscopy (XPS) can be used to study the growth behavior of such molecular systems. In XPS, coverages are often calculated assuming a uniform thickness across a surface. This results in an error for rough films, and the magnitude of this error depends on the kinetic energy of the photoelectrons analyzed. We have used this kinetic-energy dependency to estimate the roughnesses of thin porphyrin films grown on rutile TiO2(110). We used two different molecules: cobalt (II) monocarboxyphenyl-10,15,20-triphenylporphyrin (CoMCTPP), with carboxylic-acid anchor groups, and cobalt (II) tetraphenylporphyrin (CoTPP), without anchor groups. We find CoMCTPP to grow as rough films at room temperature across the studied coverage range, whereas for CoTPP the first two layers remain smooth and even; depositing additional CoTPP results in rough films. Although, XPS is not a common technique for measuring roughness, it is fast and provides information of both roughness and thickness in one measurement. 相似文献