Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
Porcine pepsin is a gastric aspartic proteinase that reportedly plays a pivotal role in the\ndigestive process of many vertebrates. We have investigated the three-dimensional (3D) structure\nand conformational transition of porcine pepsin in solution over a wide range of denaturant urea\nconcentrations (0-10 M) using Raman spectroscopy and small-angle X-ray scattering. Furthermore,\n3D GASBOR ab initio structural models, which provide an adequate conformational description\nof pepsin under varying denatured conditions, were successfully constructed. It was shown that\npepsin molecules retain native conformation at 0-5 M urea, undergo partial denaturation at 6 M urea,\nand display a strongly unfolded conformation at 7-10 M urea. According to the resulting GASBOR\nsolution models, we identified an intermediate pepsin conformation that was dominant during the\nearly stage of denaturation. We believe that the structural evidence presented here provides useful\ninsights into the relationship between enzymatic activity and conformation of porcine pepsin at\ndifferent states of denaturation....
HI spectra of the supernova remnant G18.9-1.1 and the supernova remnant\ncandidate G28.6+0.0 are analyzed. We compared the spectra to 13CO emission\nspectra and to spectra of HII regions in the area to determine kinematic distances.........................
A collection of personal protective equipment (PPE), suitable for use in case of accident in nuclear facilities or radiological\nemergencies, was gathered at the National Institute for Nuclear, Chemical and Biological Protection, Czech Republic. The shielding\ncharacteristics of the various PPE materials were measured via narrow geometry spectral attenuation measurements with point\nradionuclide sources covering a broad range of photon energies. Photon relative penetration and attenuation for relevant energies\nof the spectra were the principal experimentally determined quantities for tested PPE. Monte Carlo simulations in the MCNPXâ?¢ code were carried out to determine photon attenuation for respective energies in the tested PPE, and the results were compared to\nthose determined experimentally. Energy depositions in a unit volume of an ORNL phantom were simulated in a radioactive\naerosols atmospheric environment to determine effective doses both for the whole body and in various organs in the human torso\nduring exposure to different dispersed radioactive aerosols while wearing one of the PPE protecting against X- and gamma-ray. This\nwork aimed to determine the effective dose and its decrease for individual PPE protecting against X- and gamma-ray....
In-situ high energy X-Ray diffraction (HEXRD) was used on compositionally graded steels\nto study the effect of substitutional elements on ferrite growth kinetics in Fe-C-X and Fe-C-X-Y\nsystems. Two systems were selected to illustrate the applicability of the combinatorial approach in\nstudying such transformations, Fe-C-Mn and Fe-C-Mn-Mo. Comparison between the measured\nferrite growth kinetics using HEXRD and the predicted ones using Para-Equilibrium (PE) and Local\nEquilibrium with Negligible Partitioning (LENP) models indicates that the fractions reached at\nthe stasis of transformation are lower than the predicted ones. Experiments indicated a deviation\nof measured kinetics from both PE and LENP models when increasing Mn and decreasing Mo\n(in Fe-C-Mn-Mo system). The large amount of data that can be obtained using this approach can be\nused for validating existing models describing ferrite growth kinetics....
The recent progress in the development of X-ray free electron lasers (XFELs) allows for\nthe delivery of over 10^11 high-energy photons to solid-density samples in a femtosecond time\nscale. The corresponding peak brightness of XFEL induces a nonlinear response of matter in a\nshort-wavelength regime. The absorption of an XFEL pulse in a solid also results in the creation\nof high energy density (HED) matter. The electronic structure and related fundamental properties\nof such HED matter can be investigated with the control of XFEL and various X-ray spectroscopic\ntechniques. These experimental data provide unique opportunities to benchmark theories and\nmodels for extreme conditions and to guide further advances. In this article, the current progress in\nspectroscopic studies on intense XFEL-matter interactions and HED matter are reviewed, and future\nresearch opportunities are discussed....
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