The magnetic anisotropy measurements of metallic Y-Ba-Cu-O compounds in the normal phase reveal a temperature-dependent diamagnetic component of the susceptibility that increases with decreasing ...temperature. The temperature variation of the susceptibility anisotropy and its total change do not seem to be much affected by the presence of the superconductivity at some lower temperature and could not be accounted for by superconducting fluctuations. Rather, the data remind one of the behavior of some quasi-two-dimensional metals with anisotropic Fermi surfaces, reflecting the properties of the low-energy excitations in the normal phase. The anisotropy measurements above the bulk superconducting transition temperature {Tc} reveal the nonlinear effects, which are due to the onset of superconductivity in disconnected grains. The existence of a two-step transition, typical for granular superconductors, should be taken into consideration if the normal-phase susceptibility data are compared with the theoretical predictions in the vicinity of {ital T}{sub {ital c}}.
We have previously described the identification of BTF-37, an autonomously transferable chromosomal element isolated from
Bacteroides fragilis clinical isolate LV23. In this study, we determined that ...BTF-37 harbors a 16
kb conjugal transfer-encoding region that contains an almost identical copy of a previously identified
Bacteroides sp. conjugation-specific gene
bctA. BctA has been shown to be required for conjugation in other
Bacteroides sp. strains, but no information is available regarding its function. We now report strain distribution and gene expression profiles of
bctA. The
bctA gene was present in conjugative transposon-harboring
B. fragilis strains, but not on a non-transferable
B. fragilis plasmid. We also showed that recombinant BctA predominantly localized to the bacterial membrane, and that its N-terminal 32 amino acids were cleaved in an
Escherichia coli protein expression system, indicating the presence of a signal sequence. Expression of
bctA consistently increased ~3-fold upon pre-exposure of conjugating
B. fragilis LV23 to subinhibitory concentrations of tetracycline. Maximum expression occurred 60
min post-tetracycline induction, which also coincided with the time at which highest conjugation frequencies were seen for strain LV23. Based on localization, signal sequence and tetracycline inducibility, our results indicate that BctA is indeed an important member of the
Bacteroides conjugal apparatus, since its gene is regulated by conditions that specifically control conjugation.
Acetyl (
Ia) and pivaloyl (
Ib) triesters of the 1
N,3
N,5
N-trihydroxy-1,3,5-triazin-2,4,61
H,3
H,5
H-trione (
I) were synthesised. The spectrophotometric and potentiometric investigation of
I ...revealed a weak acidic properties of triprotonic acid (p
K
a1=5.23, p
K
a2=6.32, and p
K
a3=7.93). The MS and TGA analyses of
I indicated on hydroxyisocyanate as possible degradation product. The chelating ability of
I with Fe(III)-ion was preliminary explored. IR measurements of aqueous solutions of
I in the presence of Fe(III) ion showed the possible chelating ability of all hydroxamic moieties. The chemical structures and properties of investigated compounds were derived from the results of IR,
1H and
13C NMR, UV and MS spectrometric data, as well as thermogravimetric and potentiometric analysis.
The influence of different corrosion media on stainless steel is presented in this paper. The experiments were performed in two types of medium: one was prepared according to the ICK 01.89 standard ...and the other was sea water. The weight difference between the samples before and after the experiments was the basis for a calculation of the corrosion rate.
We report a fast-track computationally-driven discovery of new SARS-CoV2 Main Protease (M\(^{pro}\)) inhibitors whose potency range from mM for initial non-covalent ligands to sub-\(\mu\)M for the ...final covalent compound (IC50=830 +/- 50 nM). The project extensively relied on high-resolution all-atom molecular dynamics simulations and absolute binding free energy calculations performed using the polarizable AMOEBA force field. The study is complemented by extensive adaptive sampling simulations that are used to rationalize the different ligands binding poses through the explicit reconstruction of the ligand-protein conformation spaces. Machine Learning predictions are also performed to predict selected compound properties. While simulations extensively use High Performance Computing to strongly reduce time-to-solution, they were systematically coupled to Nuclear Magnetic Resonance experiments to drive synthesis and to in vitro characterization of compounds. Such study highlights the power of in silico strategies that rely on structure-based approaches for drug design and allows to address the protein conformational multiplicity problem. The proposed fluorinated tetrahydroquinolines open routes for further optimization of M\(^{pro}\) inhibitors towards low nM affinities.
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