Structural Diversity of Lithium N ‐Mesityl‐ P , P ‐diphenylphosphinimidate of the type [(L)Li{O−PPh 2 =N−Mes] n Depending on Lewis Base L

Abstract Metalation of N ‐mesityl‐ P,P ‐diphenylphosphinic amide with n BuLi in toluene yields tetranuclear lithium N ‐mesityl‐ P , P ‐diphenylphosphinimidate ([Ph 2 P(OLi)=N−Mes] 4 , 1 ). Metalation of Ph 2 P(O)−N(H)Mes with a mixture of dibutylmagnesium and butyllithium in DME leads to formation of dinuclear [Ph 2 P{OLi(dme)}=N−Mes] 2 ( 2 ). Excess of Ph 2 P(O)−N(H)Mes gives dinuclear [Li(O−PPh 2 =N−Mes){Ph 2 P(=O)−N(H)−Mes}] 2 ( 3 ) with three‐coordinate alkali ions. The metathetical approach via reaction of 1 with anhydrous magnesium bromide in ethereal solution yields [{(thf)LiBr} 2 {(thf)Li(O−PPh 2 =NMes)(Et 2 O)Li(O−PPh 2 =NMes)}] ( 4 ). Heterobimetallic Li/Mg compounds are not accessible by these protocols. Reactions of 1 with DME, with excess of Ph 2 P(O)−N(H)Mes or with LiBr allows the straightforward conversion to compounds 2 , 3 and 4 .imag

Использование IoT-технологий в защите окружающей среды

Большинство дискуссий вокруг феномена Интернета вещей (IoT) обычно сводится к тем потенциальным преимуществам для бизнеса и к тем удобствам для пользователей, которые обеспечивают интеллектуальные устройства и объекты, окружающие нас ежедневно. Однако, каким образом Интернет вещей и индустриальный Интернет вещей (M2M - machine-to-machine), то есть беспроводная передача данных и информации между устройствами и объектами, будет способствовать устойчивому развитию и защите окружающей среды.Most of the discussions around the phenomenon of the Internet of Things (IoT) usually boils down to those potential benefits for the business and to those amenities for users that provide intelligent devices and objects that surround us daily. However, how the Internet of things and the industrial Internet of things (M2M - machine-to-machine), that is, the wireless transmission of data and information between devices and objects, can have a beneficial effect on our lives and will contribute to sustainable development and the protection of the environment on the planet

Cyclotron resonant scattering feature simulations. I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling

Electron cyclotron resonant scattering features (CRSFs) are observed as absorption-like lines in the spectra of X-ray pulsars. A significant fraction of the computing time for Monte Carlo simulations of these quantum mechanical features is spent on the calculation of the mean free path for each individual photon before scattering, since it involves a complex numerical integration over the scattering cross section and the (thermal) velocity distribution of the scattering electrons. We aim to numerically calculate interpolation tables which can be used in CRSF simulations to sample the mean free path of the scattering photon and the momentum of the scattering electron. The tables also contain all the information required for sampling the scattering electron's final spin. The tables were calculated using an adaptive Simpson integration scheme. The energy and angle grids were refined until a prescribed accuracy is reached. The tables are used by our simulation code to produce artificial CRSF spectra. The electron momenta sampled during these simulations were analyzed and justified using theoretically determined boundaries. We present a complete set of tables suited for mean free path calculations of Monte Carlo simulations of the cyclotron scattering process for conditions expected in typical X-ray pulsar accretion columns (0.01<B/B_{crit}<=0.12, where B_{crit}=4.413x10^{13} G and 3keV<=kT<15keV). The sampling of the tables is chosen such that the results have an estimated relative error of at most 1/15 for all points in the grid. The tables are available online at http://www.sternwarte.uni-erlangen.de/research/cyclo.Comment: A&A, in pres

The XMM-Newton view of the Crab

Aims. We discuss the current X-ray view of the Crab Nebula and Pulsar, summarising our analysis of observations of the source with the EPIC-pn camera on board the XMM-Newton observatory. Different modes of EPIC-pn were combined in order to yield a complete scenario of the spectral properties of the Crab resolved in space and time (pulse phase). In addition we give a description of the special EPIC-pn Burst mode and guidance for data reduction in that mode. Methods. We analysed spectra for the nebula and pulsar separately in the 0.6−12.0 keV energy band. All data were processed with the SAS 6.0.0 XMM-Newton Scientific Analysis System package; models were fitted to the data with XSPEC 11. The high time resolution of EPIC-pn in its Burst mode (7 μs) was used for a phase resolved analysis of the pulsar spectrum, after determination of the period with epoch folding techniques. Data from the SmallWindow mode were processed and corrected for pile-up allowing for spectroscopy simultaneously resolved in space and time. Results. The spatial variation of the spectrum over the entire region of the Crab shows a gradual spectral softening from the inner pulsar region to the outer nebula region with a variation in photon index, Γ, from 2.0 to 2.4. Pulse phase resolved spectroscopy of the Crab Pulsar reveals a phase dependent modulation of the photon index in form of a significant hardening of the spectrum in the inter-peak phase from Γ = 1.7 during the pulse peak to Γ = 1.5

Foliar lead uptake by lettuce exposed to atmospheric fallouts

Metal uptake by plants occurs by soil−root transfer but also by direct transfer of contaminants from the atmosphere to the shoots. This second pathway may be particularly important in kitchen gardens near industrial plants. The mechanisms of foliar uptake of lead by lettuce (Lactuca sativa) exposed to the atmospheric fallouts of a lead-recycling plant were studied. After 43 days of exposure, the thoroughly washed leaves contained 335 ± 50 mg Pb kg−1 (dry weight). Micro-X-ray fluorescence mappings evidenced Pb-rich spots of a few hundreds of micrometers in diameter located in necrotic zones. These spots were more abundant at the base of the central nervure. Environmental scanning electron microscopy coupled with energy dispersive X-ray microanalysis showed that smaller particles (a few micrometers in diameter) were also present in other regions of the leaves, often located beneath the leaf surface. In addition, submicrometric particles were observed inside stomatal openings. Raman microspectrometry analyses of the leaves identified smelter-originated Pb minerals but also secondary phases likely resulting from the weathering of original particles. On the basis of these observations, several pathways for foliar lead uptake are discussed. A better understanding of these mechanisms may be of interest for risk assessment of population exposure to atmospheric metal contamination

4U 1909+07: a well-hidden pearl

We present the first detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U 1909+07 is detected in the ISGRI 20-40 keV energy band with an average countrate of 2.6 cps. The pulse period of ~604 sec is not stable, but changing erratically on timescales of years. The pulse profile is strongly energy dependent: it shows a double peaked structure at low energies, the secondary pulse decreases rapidly with increasing energy and above 20 keV only the primary pulse is visible. This evolution is consistent between PCA, HEXTE, and ISGRI. The phase averaged spectrum can be well described by the sum of a photoabsorbed power law with a cutoff at high energies and a blackbody component. To investigate the pulse profile, we performed phase resolved spectral analysis. We find that the changing spectrum can be best described with a variation of the folding energy. We rule out a correlation between the black body component and the continuum variation and discuss possible accretion geometries.Comment: 9 pages, 11 figures, accepted for publication in A&A Sect.

Zero-range process with open boundaries

We calculate the exact stationary distribution of the one-dimensional zero-range process with open boundaries for arbitrary bulk and boundary hopping rates. When such a distribution exists, the steady state has no correlations between sites and is uniquely characterized by a space-dependent fugacity which is a function of the boundary rates and the hopping asymmetry. For strong boundary drive the system has no stationary distribution. In systems which on a ring geometry allow for a condensation transition, a condensate develops at one or both boundary sites. On all other sites the particle distribution approaches a product measure with the finite critical density \rho_c. In systems which do not support condensation on a ring, strong boundary drive leads to a condensate at the boundary. However, in this case the local particle density in the interior exhibits a complex algebraic growth in time. We calculate the bulk and boundary growth exponents as a function of the system parameters