Solid-state magnetic resonance is a unique technique that can reveal the dynamics of complex biological systems with atomic resolution. Longitudinal relaxation is a mechanism that returns ...longitudinal nuclear magnetization to its thermal equilibrium by incoherent processes. The measured longitudinal relaxation rate constant however represents the combination of both incoherent and coherent contributions to the change of nuclear magnetization. This work demonstrates the effect of magic angle spinning rate on the longitudinal relaxation rate constant in two model compounds: L-histidine hydrochloride monohydrate and glycine serving as proxies for isotopically-enriched biological materials. Most notably, it is demonstrated that the longitudinal N15 relaxation of the two nitrogen nuclei in the imidazole ring in histidine is reduced by almost three orders of magnitude at the condition of rotational resonance with the amine, while the amine relaxation rate constant is increased at these conditions. The observed phenomenon may have radical implications for the solid-state magnetic resonance in biophysics and materials, especially in the proper measurement of dynamics and as a selective serial transfer step in dynamic nuclear polarization.
A new one‐pot multicomponent reaction of equimolar amounts of malononitrile and benzaldehyde in ethanol for the synthesis of hexahydropyrido2,3‐dpyrimidine derivatives through a sequence of ...Knoevenagel condensation, Michael addition, and Addition of Nucleophile, Ring Opening, and Ring Closure process is described.
A convenient one-pot two-step strategy for synthesis of the novel tricyclic system 9-chloro-4-methyl-6,11-dihydro-5
H
-benzo
b
pyrimido4,5-
e
1,4diazepine have been synthesized through the ...heterocyclization reaction of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine with 4-chloro-o-phenylenediamine under basic conditions. Various derivatives were obtained via treatment with secondary amines. Also, the inhibitory effects of the synthesized compound against bromodomain-containing protein 4 (BRD4) have been evaluated by molecular docking. The results reveal that among the studied compounds (
5f
) is a more potent inhibitor against this enzyme.
Graphical abstract
Tuberculosis (TB) remains one of the most afflictive bacterial infections globally. In high burden TB countries, surveillance, diagnosis and treatment of drug resistant TB (RR and X/MDRTB) display a ...crucial public health challenge. Therefore, we need new TB vaccines; diagnostic and therapeutic strategies to briskly prevent disease promotion; reduce drug-resistant TB and protect everyone from disease. The study identified various potent membrane and cell wall M. tuberculosis glycolipoproteins that are relevant for diagnostics, drug and vaccine discovery. A M. tuberculosis Proskauer and Beck broth culture was extracted for total proteins by ammonium sulfate method. After ConA-Affinity Chromatography reputed glycoproteins were collected followed by 2DE gel electrophoresis and LC Mass spectrometry. A total of 293 glycoproteins were identified using GlycoPP and IEDB database. Probable conserved trans-membrane protein (Rv0954), LpqN (Rv0583), PPE68 (Rv3873), Phosphate-binding protein (Rv0932c), PPE61 (Rv3532) and LprA (Rv1270c), had the highest glycosylation percentage value with 13.86%, 11.84%, 11.68%, 11.1%, 10.59% and10.2%, respectively. Our study discloses several dominant glycoproteins that play roles in M. tuberculosis survival, and immunogenicity. These include glycoproteins involved in antigenicity, transport and biosynthesis of M. tuberculosis cell envelope, pathogen-host interaction and drug efflux pumps, which are considered as a feasible drug targets or TB new vaccine candidates.
Problem Definition: The wooden door of the tomb of four kings in Lahijan is one of the woodcarvings works available in the National Museum of Iran, which has a special value in terms of antiquity and ...beauty, as well as the inscriptions used in it. This door belongs to the Kiya dynasty that ruled in the northern regions of Iran at the same time as the Safavid period. Several prestigious artworks have been left from the Kiya period, including the woodcarving technique, one of which is the tomb of four kings of Lahijan and its ancient door. The present research seeks to answer the question of what are the motifs of the mentioned door and also the themes used in it and also identify the themes and contents of this historical work.Objective: The aim of this research is to get acquainted with the Kiya’s art in the northern region of Iran and also to get acquainted with the visual and architectural elements of the region.Research Method: The present study has been conducted based on the library resources and historical perspective in a descriptive-analytical manner.Results: The plant motifs including arabesque and khatai have been used with remarkable elegance and variety in the decorations of the door of the tomb of four kings, all of which are the common motifs of the Safavid period. The most used line in inscriptions is the thuluth. Moreover, the themes of the inscriptions also include historical prayers and poetry. In general, by examining the characteristics of this work, it can be stated that the Kiaya government, like the Safavid rulers of their time, have perfectly considered the visual principles of the motifs
The Monte Carlo radiation transport code MCNP6 has been used to model dosimetry for biological pathogen samples placed within a MultiRad 225 irradiation chamber, in order to inform virus deactivation ...protocols. Full characterisations of the photon spectra generated by the chamber's x-ray tube were achieved for both 190 and 220 kV potentials, with and without aluminium and copper beam filters of different thicknesses. Dose rate maps to air and water within the chamber were then derived, along with corresponding conversion coefficient data. The maps were determined for samples located both on a shelf and on a dry ice refrigeration chamber, at different distances from the source. The potential depth-dose profiles through samples were also investigated. The optimum choice of filter for use in virus inactivation procedures will rely on a compromise between dose homogeneity and dose rate.
We present a systematic study of crude oil–brine–rock interactions in tight chalk cores at reservoir conditions. Flooding experiments are performed on outcrops (Stevns Klint) as well as on reservoir ...core plugs from Dan field, the Ekofisk and Tor formations. These studies are carried out in core plugs with reduced pore volumes, i.e., short core samples and aged with a dynamic ageing method. The method was evaluated by three different oil compositions. A series of synthetic multicomponent brines and designed fluid injection scenarios are investigated; injection flow rates are optimized to ensure that a capillary-dominant regime is maintained. Changes in brine compositions and fluid distribution in the core plugs are characterized using ion chromatography and X-ray computed tomography, respectively. First, we show that polar components in the oil phase play a major role in wettability alteration during ageing; this controls the oil production behavior. We also show that, compared to seawater, both formation water and ten-times-diluted seawater are better candidates for enhanced oil recovery in the Dan field. Finally, we show that the modified flow zone indicator, a measure of rock quality, is likely the main variable responsible for the higher oil recoveries observed in Tor core samples.
A new methodology for the synthesis of 4-(1-(pyrimidin-4-yl)ethyl)-12H-pyrimido4′,5′:5,61,4thiazino2,3-bquinoxaline derivatives 5a-g was introduced. Condensation of ...5-bromo-4-1-(5-bromo-2,6-dichloropyrimidin-4-yl)ethyl-2-chloro-6-methylpyrimidine 2 and 3-aminoquinoxaline-2-thiol 3 gave either regioisomers 4 or 4′. The computational and spectral data of both regioisomers confirmed the occurrence of the S/N type Smiles rearrangement during the course of the reaction. Treatment of the foregoing compound with various secondary amines gave several new 4-(1-(pyrimidin-4-yl)ethyl)-12H-pyrimido4′,5′:5,61,4thiazino2,3-bquinoxaline derivatives 5a-g. The newly synthesized compounds were evaluated for their potential antibacterial activity and the results exhibit two of the derivatives are moderately valuable compounds in comparison with three reference drugs.
This paper presents the method for identification of the dynamic parameters and coefficients of friction of planar robots. The dynamic equations of the robot are directly differentiated in order to ...find the identification Jacobian members. The set of base inertial parameters are determined symbolically and the identification procedure is developed with respect to them. A polynomial model is adopted for the joint frictions and the identification Jacobian is expressed in an extended form which allows identification of the friction coefficients along with the robot inertial parameters. The method has been applied to the robot under study and the practical results proved remarkable improvement in the robot model.
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