Three aides working for US President Donald Trump, vice-president Mike Pence, and first daughter Ivanka Trump have tested positive for the novel coronavirus this week. This has brought the pandemic to within a degree of the center of power in the US.

The Trump administration is tightening visa guidelines for Chinese journalists in response to the treatment of US journalists in China, as tensions flare between the two nations over the coronavirus.

Labour Court had directed firm to pay all allowances as he ‘was not given opportunity to defend himself’

Coronavirus breaches White House as rest of America re-opens

Hong Kong: Trump administration tightens visas for Chinese reporters - Times of India

4.75 lakh e-tokens issued for liquor sale in Delhi

Tesla said the county's position left it no choice but to take legal action to ensure Tesla and its employees can go back to work

The Mambalam police on Saturday arrested Prasanth, 32, owner of T. Nagar-based Jain Bakeries and Confectioneries, on the charge of outraging religious

He wrote that whether the company keeps any manufacturing in Fremont depends on how Tesla is treated in the future.

However, the company says it does not have the urgency to begin production in the factory, but bring back the rhythm of the manufacturing unit.

Autor: Andreas, de Schärding, ca. 15. Jh.
Erschienen 1450
BSB-Signatur Clm 18458

URN: urn:nbn:de:bvb:12-bsb00130120-0
URL: http://daten.digitale-sammlungen.de/~db/0013/bsb00130120/images/

An X-ray amplitude-splitting interferometer based on compound refractive lenses, which operates in the reflection mode, is proposed and realized. The idea of a reflecto-interferometer is to use a very simplified experimental setup where a focused X-ray beam reflected from parallel flat surfaces creates an interference pattern in a wide angular range. The functional capabilities of the interferometer were experimentally tested at the European Synchrotron Radiation Facility (ESRF) ID06 beamline in the X-ray energy range from 10 keV to 15 keV. The main features of the proposed approach, high spatial and temporal resolution, were demonstrated experimentally. The reflections from free-standing Si3N4 membranes, gold and resist layers were studied. Experimentally recorded interferograms are in good agreement with our simulations. The main advantages and future possible applications of the reflecto-interferometer are discussed.

Wavefront sensing at X-ray free-electron lasers is important for quantitatively understanding the fundamental properties of the laser, for aligning X-ray instruments and for conducting scientific experimental analysis. A fractional Talbot wavefront sensor has been developed. This wavefront sensor enables measurements over a wide range of energies, as is common on X-ray instruments, with simplified mechanical requirements and is compatible with the high average power pulses expected in upcoming X-ray free-electron laser upgrades. Single-shot measurements were performed at 500 eV, 1000 eV and 1500 eV at the Linac Coherent Light Source. These measurements were applied to study both mirror alignment and the effects of undulator tapering schemes on source properties. The beamline focal plane position was tracked to an uncertainty of 0.12 mm, and the source location for various undulator tapering schemes to an uncertainty of 1 m, demonstrating excellent sensitivity. These findings pave the way to use the fractional Talbot wavefront sensor as a routine, robust and sensitive tool at X-ray free-electron lasers as well as other high-brightness X-ray sources.

The time evolution of the electron density and the resulting time dependence of the X-ray polarizability of a crystal irradiated by highly intense XFEL femtosecond pulses is investigated theoretically. Rate equations for bound electrons and the Boltzmann equation for the unbound electron gas are used in calculations.

Contributions of experimental and selected theoretical charge-density research to medicinal chemistry are reviewed; combining experimental methods from high-resolution small-molecule and macromolecular crystallography with theory proves to be fruitful.

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Interview: Michael Stephenson, British Geological Survey head of science & technology  The Engineer

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The reaction of ligand 5,7-di­hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine (L) with CuI lead to the formation of a three-dimensional coordination polymer, incorporating the well known [CuxIx]n staircase motif (x = 4). These polymer [Cu4I4]n chains are linked via the N and S atoms of the ligand to form the three-dimensional coordination polymer poly[(μ4-5,7-di­hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine-κ4N:N':S:S')tetra-μ3-iodido-tetra­copper], [Cu4I4(C8H8N2S2)]n (I). The asymmetric unit is composed of half a ligand mol­ecule, with the pyrazine ring located about a center of symmetry, and two independent copper(I) atoms and two independent I− ions forming the staircase motif via centers of inversion symmetry. The framework is consolidated by C—H⋯I hydrogen bonds.

The reaction of ligand 3,4,8,10,11,13-hexa­hydro-1H,6H-bis­([1,4]di­thio­cino)[6,7-b:6',7'-e]pyrazine (L) with CuI led to the formation of a two-dimensional coordination polymer, incorporating a [Cu2I2] motif. These units are linked via the four S atoms of the ligand to form the title two-dimensional coordination poly­mer, poly[[μ4-3,4,8,10,11,13-hexa­hydro-1H,6H-bis­([1,4]di­thio­cino)[6,7-b:6',7'-e]pyrazine]di-μ-iodido-dicopper(I)], [Cu2I2(C12H16N2S4)]n, (I). The asymmetric unit is composed of a ligand mol­ecule, two copper(I) atoms and two I− ions. Both copper(I) atoms are fourfold S2I2 coordinate with almost regular trigonal-pyramidal environments. In the crystal, the layers, lying parallel to (102), are linked by C—H⋯I hydrogen bonds, forming a supra­molecular framework.

In the title compound, C61H15ClN2O3, the heterocyclic ring adopts an envelope conformation, folded across the N⋯N line, with the 2,5-di­meth­oxy­phenyl unit occupying a quasi-axial site. There are two N—H⋯O hydrogen bonds in the structure: one hydrogen bond links mol­ecules related by a 41 screw axis to form a C(6) chain, and the other links inversion-related pairs of mol­ecules to form an R22(8) ring. The ring motif links all of the chains into a continuous three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

The PtII atom in the title complex, [Pt(C15H18N4O4S)(C2H6OS)], exists within a square-planar NS2O donor set provided by the N, S, O atoms of the di-anionic tridentate thio­semicarbazo ligand and a dimethyl sulfoxide S atom. The two chelate rings are coplanar, subtending a dihedral angle of 1.51 (7)°. The maximum deviation from an ideal square-planar geometry is seen in the five-membered chelate ring with an S—Pt—S bite angle of 96.45 (2)°. In the crystal, mol­ecules are linked via N—H⋯O, C—H⋯O, C—H⋯N and C—H⋯π inter­actions into two-dimensional networks lying parallel to the ab plane. The conformations of related cyclo­hexyl­hydrazine-1-carbo­thio­amide ligands are compared to that of the title compound.

Twelve 4-(4-meth­oxy­phen­yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. The monohydrated benzoate, 4-fluoro­benzoate, 4-chloro­benzoate and 4-bromo­benzoate salts, C11H17N2O+·C7H5O2−·H2O (I), C11H17N2O+·C7H4FO2−·H2O (II), C11H17N2O+·C7H4ClO2−·H2O (III), and C11H17N2O+·C7H4BrO2−·H2O (IV), respectively, are isomorphous and all exhibit disorder in the 4-meth­oxy­phenyl unit: the components are linked by N—H⋯O and O—H⋯O hydrogen bond to form chains of rings. The unsolvated 2-hy­droxy­benzoate, pyridine-3-carboxyl­ate and 2-hy­droxy-3,5-di­nitro­benzoate salts, C11H17N2O+·C7H5O3− (V), C11H17N2O+·C6H4NO2− (VI) and C11H17N2O+·C7H3N2O7− (VII), respectively, are all fully ordered: the components of (V) are linked by multiple N—H⋯O hydrogen bonds to form a chain of rings; those of (VI) are linked into a three-dimensional framework by a combination of N—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds and those of (VII), where the anion has a structure reminiscent of the picrate anion, are linked into a three-dimensional array by N—H⋯O and C—H⋯O hydrogen bonds. The hydrogensuccinate and hydrogenfumarate salts, C11H17N2O+·C4H5O4− (VIII) and C11H17N2O+·C4H3O3− (IX), respectively, are isomorphous, and both exhibit disorder in the anionic component: N—H⋯O and O—H⋯O hydrogen bonds link the ions into sheets, which are further linked by C—H⋯π(arene) inter­actions. The anion of the hydrogenmaleate salt, C11H17N2O+·C4H3O3− (X), contains a very short and nearly symmetrical O⋯H⋯O hydrogen bond, and N—H⋯O hydrogen bonds link the anions into chains of rings. The ions in the tri­chloro­acetate salt, C11H17N2O+·C2Cl3O2− (XI), are linked into simple chains by N—H⋯O hydrogen bonds. In the hydrated chloranilate salt, 2C11H17N2O+·C6Cl2O42−·2H2O (XII), which crystallizes as a non-merohedral twin, the anion lies across a centre of inversion in space group P21/n, and a combination of N—H⋯O and O—H⋯O hydrogen bonds generates complex sheets. Comparisons are made with the structures of some related compounds.

A one-dimensional ladder-type coordination polymer, poly[[(μ2-hydroxido)(μ2-1H-pyrazole-3,5-di­carboxyl­ato)gallium(III)] monohydrate], [Ga(C5H2N2O4)(OH)(H2O)]n or [Ga(HPDC)(OH)(H2O)]n, I, isotypic with a V3+ coordination polymer previously reported by Chen et al. [J. Coord. Chem. (2008). 61, 3556–3567] was prepared from Ga3+ and pyrazole-3,5-di­carb­oxy­lic acid monohydrate (H3PDC·H2O). Compound I was isolated using three distinct experimental methods: hydro­thermal (HT), microwave-assisted (MWAS) and one-pot (OP) and the crystallite size should be fine-tuned according to the method employed. The coordination polymeric structure is based on a dimeric Ga3+ moiety comprising two μ2-bridging hydroxide groups, which are inter­connected by HPDC2− anionic organic linkers. The close packing of individual polymers is strongly directed by the supra­molecular inter­actions, namely several O—H⋯O and N—H⋯O hydrogen-bonding inter­actions.