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128 Covid deaths, 3,277 cases in 24 hrs; toll 2,109

Of the 2,109 fatalities, Maharashtra tops the tally with 779 deaths. Gujarat comes second with 472 deaths, followed by Madhya Pradesh at 215, West Bengal at 171, Rajasthan at 106, Uttar Pradesh at 74, Delhi at 73, and Andhra Pradesh and Tamil Nadu at 44.




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Tracking US President Donald Trump’s response to Covid-19 through his top 10 quotes




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Boris Johnson to set out Covid-19 warning system in public address




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'Famotidine may become the next HCQ for Covid-19'

Researchers at Northwell Health in New York are testing the effects on Famotidine (used in high intravenous doses) on Covid-19 patients as a potential treatment. After the hospital announced its clinical trials, it led to a drug shortage in the US. Back home, however, there has not been any surge in the demand for Famotidine yet.




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COVID-19 survivor Zoa Morani donates blood for plasma therapy




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Chandigarh: Bapu dham resident tests positive after death, UT sees 21 new cases




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Ayurveda medicine trial to begin on asymptomatic Covid-19 patients in Chandigarh




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Punjab and Haryana HC to hold 10 benches for hearing of urgent cases over video conferencing




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Plea in Punjab and Haryana HC seeks directions to health facilities to attend non-Covid cases




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Inside Track: Kishor’s expertise




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Kerala continues to deal competently with the Covid-19 pandemic as well




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31 new Covid-19 cases in Punjab, total 1,762




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Mohali: 18-month-old defeats Covid-19

Of the total three patients discharged on Saturday, a 18-month-old child was also discharged after defeating Covid-19.The total patients discharged in the city stands at 24.




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‘I owe dinners to Brendon McCullum, KKR staff for that auction bid’: Pat Cummins




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Low-dose X-ray structure analysis of cytochrome c oxidase utilizing high-energy X-rays

To investigate the effect of high-energy X-rays on site-specific radiation-damage, low-dose diffraction data were collected from radiation-sensitive crystals of the metal enzyme cytochrome c oxidase. Data were collected at the Structural Biology I beamline (BL41XU) at SPring-8, using 30 keV X-rays and a highly sensitive pixel array detector equipped with a cadmium telluride sensor. The experimental setup of continuous sample translation using multiple crystals allowed the average diffraction weighted dose per data set to be reduced to 58 kGy, and the resulting data revealed a ligand structure featuring an identical bond length to that in the damage-free structure determined using an X-ray free-electron laser. However, precise analysis of the residual density around the ligand structure refined with the synchrotron data showed the possibility of a small level of specific damage, which might have resulted from the accumulated dose of 58 kGy per data set. Further investigation of the photon-energy dependence of specific damage, as assessed by variations in UV-vis absorption spectra, was conducted using an on-line spectrometer at various energies ranging from 10 to 30 keV. No evidence was found for specific radiation damage being energy dependent.




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Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction

Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time.




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Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.




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A semi-analytical approach for the characterization of ordered 3D nanostructures using grazing-incidence X-ray fluorescence

Following the recent demonstration of grazing-incidence X-ray fluorescence (GIXRF)-based characterization of the 3D atomic distribution of different elements and dimensional parameters of periodic nanoscale structures, this work presents a new computational scheme for the simulation of the angular-dependent fluorescence intensities from such periodic 2D and 3D nanoscale structures. The computational scheme is based on the dynamical diffraction theory in many-beam approximation, which allows a semi-analytical solution to the Sherman equation to be derived in a linear-algebraic form. The computational scheme has been used to analyze recently published GIXRF data measured on 2D Si3N4 lamellar gratings, as well as on periodically structured 3D Cr nanopillars. Both the dimensional and structural parameters of these nanostructures have been reconstructed by fitting numerical simulations to the experimental GIXRF data. Obtained results show good agreement with nominal parameters used in the manufacturing of the structures, as well as with reconstructed parameters based on the previously published finite-element-method simulations, in the case of the Si3N4 grating.




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A portable on-axis laser-heating system for near-90° X-ray spectroscopy: application to ferropericlase and iron silicide

A portable IR fiber laser-heating system, optimized for X-ray emission spectroscopy (XES) and nuclear inelastic scattering (NIS) spectroscopy with signal collection through the radial opening of diamond anvil cells near 90°with respect to the incident X-ray beam, is presented. The system offers double-sided on-axis heating by a single laser source and zero attenuation of incoming X-rays other than by the high-pressure environment. A description of the system, which has been tested for pressures above 100 GPa and temperatures up to 3000 K, is given. The XES spectra of laser-heated Mg0.67Fe0.33O demonstrate the potential to map the iron spin state in the pressure–temperature range of the Earth's lower mantle, and the NIS spectra of laser-heated FeSi give access to the sound velocity of this candidate of a phase inside the Earth's core. This portable system represents one of the few bridges across the gap between laser heating and high-resolution X-ray spectroscopies with signal collection near 90°.




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ProQEXAFS: a highly optimized parallelized rapid processing software for QEXAFS data

The high temporal resolution in data acquisition, possible in the quick-scanning EXAFS (QEXAFS) mode of operation, provides new challenges in efficient data processing methods. Here a new approach is developed that combines an easy to use interactive graphical interface with highly optimized and fully parallelized Python-based routines for extracting, normalizing and interpolating oversampled time-resolved XAS spectra from a raw binary stream of data acquired during operando QEXAFS studies. The programs developed are freely available via a Github repository.




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Automated nucleic acid chain tracing in real time

A method is presented for the automatic building of nucleotide chains into electron density which is fast enough to be used in interactive model-building software. Likely nucleotides lying in the vicinity of the current view are located and then grown into connected chains in a fraction of a second. When this development is combined with existing tools, assisted manual model building is as simple as or simpler than for proteins.




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Pressure effects on lipids and bio-membrane assemblies

Pressure can play a key role in probing the structure and dynamics of membrane assemblies, and is also critical to the biology and adaptation of deep-sea organisms. This article presents an overview of the effect of pressure on the structure of membranes and recent developments in high-pressure instrumentation.




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EXAFS and XANES analysis of oxides at the nanoscale

This work presents a discussion of the possibilities offered by X-ray absorption spectroscopy (XAS) to study the local structure of nanomaterials. The current state of the art for the interpretation of extended X-ray absorption fine structure (EXAFS), including an advanced approach based on the use of classical molecular dynamics, is described and exemplified in the case of NiO nanoparticles. In addition, the limits and possibilities of X-ray absorption near-edge spectroscopy (XANES) in determining several effects associated with the nanocrystalline nature of materials are also discussed in connection with the development of ZnO-based dilute magnetic semiconductors and iron oxide nanoparticles.




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A modulation wave approach to the order hidden in disorder

A modulation wave approach is used to interpret the coupled longer range as well as truly short range order hidden in the highly structured diffuse intensity distributions of three representative such systems. The longer range as well as the truly short range order simultaneously encoded in such highly structured diffuse intensity distributions is highlighted.




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Did you feel earthquake? - Stamford Mercury

Did you feel earthquake?  Stamford Mercury



















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Crystal structure of the nucleoid-associated protein Fis (PA4853) from Pseudomonas aeruginosa

Factor for inversion stimulation (Fis) is a versatile bacterial nucleoid-associated protein that can directly bind and bend DNA to influence DNA topology. It also plays crucial roles in regulating bacterial virulence factors and in optimizing bacterial adaptation to various environments. Fis from Pseudomonas aeruginosa (PA4853, referred to as PaFis) has recently been found to be required for virulence by regulating the expression of type III secretion system (T3SS) genes. PaFis can specifically bind to the promoter region of exsA, which functions as a T3SS master regulator, to regulate its expression and plays an essential role in transcription elongation from exsB to exsA. Here, the crystal structure of PaFis, which is composed of a four-helix bundle and forms a homodimer, is reported. PaFis shows remarkable structural similarities to the well studied Escherichia coli Fis (EcFis), including an N-terminal flexible loop and a C-terminal helix–turn–helix (HTH) motif. However, the critical residues for Hin-catalyzed DNA inversion in the N-terminal loop of EcFis are not conserved in PaFis and further studies are required to investigate its exact role. A gel-electrophoresis mobility-shift assay showed that PaFis can efficiently bind to the promoter region of exsA. Structure-based mutagenesis revealed that several conserved basic residues in the HTH motif play essential roles in DNA binding. These structural and biochemical studies may help in understanding the role of PaFis in the regulation of T3SS expression and in virulence.




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Structure of the 4-hydroxy-tetrahydrodipicolinate synthase from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV and the phylogeny of the aminotransferase pathway

The enzyme 4-hydroxy-tetrahydrodipicolinate synthase (DapA) is involved in the production of lysine and precursor molecules for peptidoglycan synthesis. In a multistep reaction, DapA converts pyruvate and l-aspartate-4-semialdehyde to 4-hydroxy-2,3,4,5-tetrahydrodipicolinic acid. In many organisms, lysine binds allosterically to DapA, causing negative feedback, thus making the enzyme an important regulatory component of the pathway. Here, the 2.1 Å resolution crystal structure of DapA from the thermoacidophilic methanotroph Methylacidiphilum fumariolicum SolV is reported. The enzyme crystallized as a contaminant of a protein preparation from native biomass. Genome analysis reveals that M. fumariolicum SolV utilizes the recently discovered aminotransferase pathway for lysine biosynthesis. Phylogenetic analyses of the genes involved in this pathway shed new light on the distribution of this pathway across the three domains of life.




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Solution structure and assembly of β-amylase 2 from Arabidopsis thaliana

Solution structure of β-amylase 2 from Arabidopsis thaliana shows the role of the conserved N-terminus in enzyme tetramer formation.




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Sample deposition onto cryo-EM grids: from sprays to jets and back

Sample preparation within single-particle cryo-electron microscopy can still be a significant bottleneck, with issues in reproducibility, ice quality and sample loss. New approaches have recently been reported that use spraying or pin printing instead of the traditional blotting approach. Here, experience in the use of different nozzle designs and spraying regimes is reported together with their influence on the resulting spray and grid quality.




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Confidence maps: statistical inference of cryo-EM maps

The concept of statistical signal detection by controlling the false-discovery rate (FDR) to aid the atomic model interpretation of cryo-EM density maps is reviewed. The recommended usage of the FDR software tool is presented together with its successful integration into the CCP-EM suite.




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6-Amino-2-iminiumyl-4-oxo-1,2,3,4-tetra­hydro­pyrimidin-5-aminium sulfate monohydrate

The title compound, C4H9N5O2+·SO42−·H2O, is the monohydrate of the commercially available compound `C4H7N5O·H2SO4·xH2O'. It is obtained by reprecipitation of C4H7N5O·H2SO4·xH2O from dilute sodium hydroxide solution with dilute sulfuric acid. The crystal structure of anhydrous 2,4,5-tri­amino-1,6-di­hydro­pyrimidin-6-one sulfate is known, although called by the authors 5-amminium-6-amino-isocytosinium sulfate [Bieri et al. (1993). Private communication (refcode HACDEU). CCDC, Cambridge, England]. In the structure, the sulfate group is deprotonated, whereas one of the amino groups is protonated (R2C—NH3+) and one is rearranged to a protonated imine group (R2C=NH2+). This arrangement is very similar to the known crystal structure of the anhydrate. Several tautomeric forms of the investigated mol­ecule are possible, which leads to questionable proton attributions. The measured data allowed the location of all hydrogen atoms from the residual electron density. In the crystal, ions and water mol­ecules are linked into a three-dimensional network by N—H⋯O and O—H⋯O hydrogen bonds.




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Di­chlorido­{N,N,N'-trimethyl-N'-(1H-pyrazol-1-yl-κN2)meth­yl]ethane-1,2-di­amine-κ2N,N'}copper(II) methanol monosolvate

In the title compound, [CuCl2(C9H18N4)]·CH3OH, the central CuII ion is coordinated by three N atoms from the pyrazole derivative ligand and two chloride co-ligands. The coordination geometry around the CuII ion is distorted trigonal–bipyramidal. In the crystal, the mol­ecules are linked by C—H⋯O, C—H⋯Cl and O—H⋯Cl hydrogen bonds, forming a three-dimensional framework with the lattice solvent mol­ecule.




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Crystal structure of bis­(1-ethyl-1H-imidazole-κN3)(meso-tetra­mesitylporphyrinato-κ4N,N',N'',N''')iron(III) perchlorate chloro­benzene sesquisolvate

In the complex cation of title compound, [Fe(C56H52N4)(C5H8N2)2]ClO4·1.5C6H5Cl, the ironIII atom is coordinated in a distorted octa­hedral manner by four pyrrole N atoms of the porphyrin ring system in the equatorial plane, and by two N atoms of the 1-ethyl­imidazole ligands in the axial sites. A disordered perchlorate anion and one and a half chloro­benzene solvent mol­ecules are also present. The cationic complex exhibits a highly ruffled porphyrin core. The average Fe—Np (Np is a porphyrin N atom) bond length is 1.988 (5), and the axial Fe—NIm (NIm is an imidazole N atom) bond lengths are 1.962 (3) and 1.976 (3) Å. The two 1-ethyl­imidazole ligands are inclined to each other by a dihedral angle of 68.62 (16)°. The dihedral angles between the 1-ethyl­imidazole planes and the planes of the closest Fe—Np vector are 28.52 (18) and 43.57 (13)°. Inter­molecular C—H⋯Cl inter­actions are observed.




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2-Amino-6-chloro­pyridine–glutaric acid (1/1)

In the title 1:1 co-crystal [systematic name: 6-chloro­pyridin-2-amine–penta­nedioic acid (1/1)], C5H5ClN2·C5H8O4, the pyridine ring is essentially planar, with a maximum deviation of 0.003 (1) Å. The base and acid mol­ecules are linked via N—H⋯O and O—H⋯N hydrogen bonds, while inversion-related acid mol­ecules are linked via pairs of O—H⋯O hydrogen bonds. These inter­actions together with a C—H⋯O hydrogen bond connect the two components, forming (001) sheets.




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Crystal structure of bis­(benzoato-κO)[5,15-diphenyl-10,20-bis­(pyridin-4-yl)porphyrinato-κ4N,N',N'',N''']tin(IV)

In the crystal structure of the title compound, [Sn(C42H26N6)(C7H5O2)2], the SnIV ion is located on a crystallographic inversion centre and is octa­hedrally coordinated with an N4O2 set. Four N atoms of the porphyrin ring form the equatorial plane while the axial positions are occupied by two O atoms from benzoate anions. The molecular packing of the title complex involves non-classical hydrogen bonds of the types C—H⋯O and C—H⋯N, leading to a three-dimensional network structure.