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ITC scam a pre-meditated loot of public money: HC

No one goes hungry, under this Chennai cop’s watch

As Chennai botches up, districts show way | Chennai News - Times of India

Next batch of train passes to be issued after rush clears, say cops

'Next batch of train passes after rush clears'

Tattoo artist held with husband for snatching

The Dallas-based retailer plans to cede control to creditors in exchange for eliminating $4 billion of debt. Its debt currently totals about $5 billion

Germany gets a respite while Brazil emerges as a hotspot, and gyms open in Beijing

Work to construct the final portion of the Chennai Outer Ring Road (CORR) at Padianallur in Red Hills has begun after the government allowed construct

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While Andhra Pradesh Road Transport Corporation(APSRTC) is transporting essential goods like rice, vegetables and fruits within the State, it has also

The first batch of 326 Indian nationals stranded in the U.K. due to the coronavirus-linked global travel restrictions arrived in Mumbai from London ea

A video on India's massive repatriation operation to bring back stranded Indians from different parts of the world in the wake of the coronavirus crisis

A video on the opening of liquor shops after the easing of the COVID-19 lockdown in India

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BSB-Signatur Clm 18565

URN: urn:nbn:de:bvb:12-bsb00131315-7
URL: http://daten.digitale-sammlungen.de/~db/0013/bsb00131315/images/

A simple and robust tool for spatio-temporal overlap of THz and XUV pulses in in-vacuum pump–probe experiments is presented. The technique exploits ultrafast changes of the optical properties in semiconductors (i.e. silicon) driven by ultrashort XUV pulses that are probed by THz pulses. This work demonstrates that this tool can be used for a large range of XUV fluences that are significantly lower than when probing by visible and near-infrared pulses. This tool is mainly targeted at emerging X-ray free-electron laser facilities, but can be utilized also at table-top high-harmonics sources.

The development of ultrashort X-ray pulse sources requires optics that keep the pulse length as short as possible. One source of pulse stretching is the penetration of the pulse into a crystal during diffraction. Another source is the inclination of the intensity front when the diffraction is asymmetric. The theory of short X-ray pulse diffraction has been well developed by many authors. As it is rather complicated, it is sometimes difficult to foresee the pulse behavior (mainly stretching) during diffraction in various crystal arrangements. In this article, a simple model is suggested that gives a qualitatively similar shape to the diffracted pulse which follows from exact theory. It allows proposal of what experimental arrangement is optimal to minimize the pulse stretching during diffraction. First, the effect of pulse stretching due to penetration into a crystal surface is studied. On the basis of this, the pulse profile change during diffraction by two crystals, either symmetric or asymmetric, is predicted.

Tannerella forsythia is an oral dysbiotic periodontopathogen involved in severe human periodontal disease. As part of its virulence factor armamentarium, at the site of colonization it secretes mirolysin, a metallopeptidase of the unicellular pappalysin family, as a zymogen that is proteolytically auto-activated extracellularly at the Ser54–Arg55 bond. Crystal structures of the catalytically impaired promirolysin point mutant E225A at 1.4 and 1.6 Å revealed that latency is exerted by an N-terminal 34-residue pro-segment that shields the front surface of the 274-residue catalytic domain, thus preventing substrate access. The catalytic domain conforms to the metzincin clan of metallopeptidases and contains a double calcium site, which acts as a calcium switch for activity. The pro-segment traverses the active-site cleft in the opposite direction to the substrate, which precludes its cleavage. It is anchored to the mature enzyme through residue Arg21, which intrudes into the specificity pocket in cleft sub-site S1'. Moreover, residue Cys23 within a conserved cysteine–glycine motif blocks the catalytic zinc ion by a cysteine-switch mechanism, first described for mammalian matrix metallopeptidases. In addition, a 1.5 Å structure was obtained for a complex of mature mirolysin and a tetradecapeptide, which filled the cleft from sub-site S1' to S6'. A citrate molecule in S1 completed a product-complex mimic that unveiled the mechanism of substrate binding and cleavage by mirolysin, the catalytic domain of which was already preformed in the zymogen. These results, including a preference for cleavage before basic residues, are likely to be valid for other unicellular pappalysins derived from archaea, bacteria, cyanobacteria, algae and fungi, including archetypal ulilysin from Methanosarcina acetivorans. They may further apply, at least in part, to the multi-domain orthologues of higher organisms.

Transforming growth factor β-1 (TGFβ-1) is a secreted signalling protein that directs many cellular processes and is an attractive target for the treatment of several diseases. The primary endogenous activity regulatory mechanism for TGFβ-1 is sequestration by its pro-peptide, latency-associated peptide (LAP), which sterically prohibits receptor binding by caging TGFβ-1. As such, recombinant LAP is promising as a protein-based therapeutic for modulating TGFβ-1 activity; however, the mechanism of binding is incompletely understood. Comparison of the crystal structure of unbound LAP (solved here to 3.5 Å resolution) with that of the bound complex shows that LAP is in a more open and extended conformation when unbound to TGFβ-1. Analysis suggests a mechanism of binding TGFβ-1 through a large-scale conformational change that includes contraction of the inter-monomer interface and caging by the `straight-jacket' domain that may occur in partnership through a loop-to-helix transition in the core jelly-roll fold. This conformational change does not appear to include a repositioning of the integrin-binding motif as previously proposed. X-ray scattering-based modelling supports this mechanism and reveals possible orientations and ensembles in solution. Although native LAP is heavily glycosylated, solution scattering experiments show that the overall folding and flexibility of unbound LAP are not influenced by glycan modification. The combination of crystallography, solution scattering and biochemical experiments reported here provide insight into the mechanism of LAP sequestration of TGFβ-1 that is of fundamental importance for therapeutic development.

The bacterial flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase complex derived from Burkholderia cepacia (BcGDH) is a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. In this study, the X-ray structure of BcGDHγα, the catalytic subunit (α-subunit) of BcGDH complexed with a hitchhiker protein (γ-subunit), was determined. The most prominent feature of this enzyme is the presence of the 3Fe–4S cluster, which is located at the surface of the catalytic subunit and functions in intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit. The structure of the complex revealed that these two molecules are connected through disulfide bonds and hydrophobic interactions, and that the formation of disulfide bonds is required to stabilize the catalytic subunit. The structure of the complex revealed the putative position of the electron-transfer subunit. A comparison of the structures of BcGDHγα and membrane-bound fumarate reductases suggested that the whole BcGDH complex, which also includes the membrane-bound β-subunit containing three heme c moieties, may form a similar overall structure to fumarate reductases, thus accomplishing effective electron transfer.

A complete method of comprehensive and quantitative evaluation of through-silicon via reliability using a highly sensitive phase-contrast X-ray microtomography was established. Quantitative characterizations include 3D local morphology and overall consistency of statistics.

In this article, the effect of stretching of short X-ray pulses after symmetric or asymmetric diffraction on crystal systems is studied. This is used to determine the optimal experimental arrangement to minimize the pulse stretching during diffraction.

An algorithm, based on the matching of q-vectors pairs, is combined with three-dimensional pattern matching using a nearest-neighbors approach to index Laue and monochromatic serial crystallography data recorded on small unit cell samples.

The structure of a 22-base-pair RNA helix with mismatched pyrimidine base pairs is reported. The helix contains two symmetry-related CUG sequences: a triplet-repeat motif implicated in myotonic dystrophy type 1. The CUG repeat contains a U–U mismatch sandwiched between Watson–Crick pairs. Additionally, the center of the helix contains a dimerized UUCG motif with tandem pyrimidine (U–C/C–U) mismatches flanked by U–G wobble pairs. This region of the structure is significantly different from previously observed structures that share the same sequence and neighboring base pairs. The tandem pyrimidine mismatches are unusual and display sheared, cross-strand stacking geometries that locally constrict the helical width, a type of stacking previously associated with purines in internal loops. Thus, pyrimidine-rich regions of RNA have a high degree of structural diversity.

On the heels of spring’s arrival, a wattled crane (Bugeranus carunculatus) chick hatched at the Smithsonian’s National Zoo March 20, the third of its kind […]

The post Wattled crane chick hatches at the National Zoo appeared first on Smithsonian Insider.

Just as people use airplanes to fly overseas, marine snails may use birds to fly over land,” said Mark Torchin, staff scientist at the Smithsonian.

The post Hitchhiking snails fly from ocean to ocean appeared first on Smithsonian Insider.

The fossil represents the youngest nodosaur ever discovered, and the only known specimen of a new genus and species of dinosaur that lived approximately 110 million years ago during the Early Cretaceous Era.

The post New dinosaur species named from hatchling fossil donated to National Museum of Natural History appeared first on Smithsonian Insider.

For three years—2001, 2002 and 2008—on Teopa Beach in Jalisco, Mexico, researchers examined the shell, neck and flippers of female turtles that had come out onto the beach to nest, collecting and carefully documenting all the organisms—known as epibionts—they found.

The post Sea turtle “hitchhikers” ID’d in survey appeared first on Smithsonian Insider.

A member of one of the world’s most endangered species—the brown kiwi (Apteryx mantelli)—successfully hatched at the Smithsonian’s National Zoo’s Bird House Dec. 11 at 10:25 a.m. The egg was laid Oct. 1 and keepers began looking for signs of the chick hatching starting in early December. The chick is the sixth kiwi successfully hatched at the National Zoo.

The post Kiwi chick hatching a success at the National Zoo appeared first on Smithsonian Insider.

Both investigations were carried out through DNA analysis of fish tissue performed in a laboratory using a U.S. Food and Drug Administration protocol that originated largely at the Smithsonian’s National Museum of Natural History. DNA from the fish in question was identified by matching it against a database of DNA fish barcodes that again, has its origins at the Smithsonian.

The post Smithsonian research with DNA barcoding is making seafood substitution easier to catch appeared first on Smithsonian Insider.

A baby boom is underway at the Smithsonian’s National Zoo. Two Guam rail (Gallirallus owstoni) chicks hatched March 3 and 4; they join six others in the Zoo’s collection—three of which live at the Smithsonian Conservation Biology Institute in Front Royal, Va.

The post Extremely rare Guam rails hatch at the Smithsonian’s National Zoo appeared first on Smithsonian Insider.

Supermassive black holes snack infrequently, making the recent discovery of a black hole in the act of feeding all the more exciting to astronomers.

The post Scientists catch black hole in a feeding frenzy appeared first on Smithsonian Insider.