Proton-transfer salts of diphenylphosphinic acid with substituted 2-aminopyridine:crystal structure, spectroscopic and DFT studies

Three proton-transfer salts of diphenylphosphinic acid (DPPA) with 2-amino-5-(X)-pyridine (AMPY, X = Cl, CN or CH3), namely, 2-amino-5-chloropyridinium diphenylphosphinate, C5H6ClN2+·C12H10O2P― (1, X = Cl), 2-amino-5-cyano-pyridinium diphenylphosphinate, C6H6N3+·C12H10O2P― (2, X = CN), and 2-amino-5-methylpyridinium diphenylphosphinate, C6H9N2+·C12H10O2P― (3, X = CH3), have been synthesized and characterized by FT–IR and 1H NMR spectroscopy, and X-ray crystallography. The crystal structures of compounds 1–3 were determined in the space group P1 for 1 and 2, and C2/c for 3. All three compounds contain N—H· · ·O hydrogen-bonding interactions due to proton transfer from the O P—OH group of DPPA as donor to the pyridine N atom of AMPY as acceptor. The proton transfer of compounds 1–3 was also verified by 1H NMR and FT–IR spectroscopy. The stoichiometry of all three proton-transfer salts was determined to be 1:1 and the Benesi–Hildebrand equation was applied to determine the formation constant (KCT) and the molar extinction coefficient ("CT) in each case. Theoretical density functional theory (DFT) calculations were performed to investigate the optimized geometries, the molecular electrostatic potentials (MEP) and the highest occupied molecular orbitals (HOMO) and lowest unoccupied molecular orbitals (LUMO) of all three proton-transfer salts. The results showed good agreement between the experimental data and the DFT computational analysis.</p

Population genomics of an icefish reveals mechanisms of glacier-driven adaptive radiation in Antarctic notothenioids

Background Antarctica harbors the bulk of the species diversity of the dominant teleost fish suborder—Notothenioidei. However, the forces that shape their evolution are still under debate. Results We sequenced the genome of an icefish, Chionodraco hamatus, and used population genomics and demographic modelling of sequenced genomes of 52 C. hamatus individuals collected mainly from two East Antarctic regions to investigate the factors driving speciation. Results revealed four icefish populations with clear reproduction separation were established 15 to 50 kya (kilo years ago) during the last glacial maxima (LGM). Selection sweeps in genes involving immune responses, cardiovascular development, and photoperception occurred differentially among the populations and were correlated with population-specific microbial communities and acquisition of distinct morphological features in the icefish taxa. Population and species-specific antifreeze glycoprotein gene expansion and glacial cycle-paced duplication/degeneration of the zona pellucida protein gene families indicated fluctuating thermal environments and periodic influence of glacial cycles on notothenioid divergence. Conclusions We revealed a series of genomic evidence indicating differential adaptation of C. hamatus populations and notothenioid species divergence in the extreme and unique marine environment. We conclude that geographic separation and adaptation to heterogeneous pathogen, oxygen, and light conditions of local habitats, periodically shaped by the glacial cycles, were the key drivers propelling species diversity in Antarctica.info:eu-repo/semantics/publishedVersio

Etiologic Diagnosis of Lower Respiratory Tract Bacterial Infections Using Sputum Samples and Quantitative Loop-Mediated Isothermal Amplification

Etiologic diagnoses of lower respiratory tract infections (LRTI) have been relying primarily on bacterial cultures that often fail to return useful results in time. Although DNA-based assays are more sensitive than bacterial cultures in detecting pathogens, the molecular results are often inconsistent and challenged by doubts on false positives, such as those due to system- and environment-derived contaminations. Here we report a nationwide cohort study on 2986 suspected LRTI patients across P. R. China. We compared the performance of a DNA-based assay qLAMP (quantitative Loop-mediated isothermal AMPlification) with that of standard bacterial cultures in detecting a panel of eight common respiratory bacterial pathogens from sputum samples. Our qLAMP assay detects the panel of pathogens in 1047(69.28%) patients from 1533 qualified patients at the end. We found that the bacterial titer quantified based on qLAMP is a predictor of probability that the bacterium in the sample can be detected in culture assay. The relatedness of the two assays fits a logistic regression curve. We used a piecewise linear function to define breakpoints where latent pathogen abruptly change its competitive relationship with others in the panel. These breakpoints, where pathogens start to propagate abnormally, are used as cutoffs to eliminate the influence of contaminations from normal flora. With help of the cutoffs derived from statistical analysis, we are able to identify causative pathogens in 750 (48.92%) patients from qualified patients. In conclusion, qLAMP is a reliable method in quantifying bacterial titer. Despite the fact that there are always latent bacteria contaminated in sputum samples, we can identify causative pathogens based on cutoffs derived from statistical analysis of competitive relationship

Transcriptomic and Phenotypic Analysis of CRISPR/Cas9-Mediated <em>gluk2</em> Knockout in Zebrafish

As a subtype of kainite receptors (KARs), GluK2 plays a role in the perception of cold in the periphery sensory neuron. However, the molecular mechanism for gluk2 on the cold stress in fish has not been reported. In this article, real-time PCR assays showed that gluk2 was highly expressed in the brain and eyes of adult zebrafish. To study the functions of gluk2, gene knockout was carried out using the CRISPR/Cas9 system. According to RNA-seq analysis, we selected the differentially expressed genes (DEGs) that had significant differences in at least three tissues of the liver, gill, intestine, skin, brain, and eyes. Gene Ontology (GO) enrichment analysis revealed that cry1ba, cry2, per1b, per2, hsp70.1, hsp70.2, hsp70l, hsp90aa1.1, hsp90aa1.2, hspb1, trpv1, slc27a1b, park2, ucp3, and METRNL were significantly enriched in the ‘Response to temperature stimulus’ pathway. Through behavioral phenotyping assay, the gluk2−/− larval mutant displayed obvious deficiency in cold stress. Furthermore, TUNEL (TdT-mediated dUTP Nick-End Labeling) staining proved that the gill apoptosis of gluk2−/− mutant was increased approximately 60 times compared with the wild-type after gradient cooling to 8 °C for 15 h. Overall, our data suggested that gluk2 was necessary for cold tolerance in zebrafish

Preparation and X-ray photoelectron spectroscopic characterization of Sn-doped C12A7:e(-) electride nanoparticles

Understanding the chemistry of dopants in electride nanoparticles is essential and challenging owing to the active nature of the electride and the low atomic concentration of the dopants. In this work, we developed conductive Sn-doped C12A7:e(-) electride nanoparticles by a modified sol-gel method, and performed a comprehensive X-ray photoelectron spectroscopic characterization on the surface chemistry of the doped electride nanoparticles. The resulting electride Ca12Al(14-x)Snx:e(-) (x = 1) exhibited an electron concentration of 1.65 x 10(21) cm(-3) and a specific area of 53.9 m(2)/g. XPS results showed that Sn was in the form of Sn4+ at the surface of the doped C12A7:e(-) nanoparticles. The depth distribution of elements was investigated by XPS Ar+ ion and Ar cluster ion sputtering. Results showed that Sn was enriched at the surface and sputtering partially reduced Sn4+ to metallic Sn, and Ar cluster ion sputtering showed much weaker effect on the reduction of Sn4+ than the Ar+ ion sputtering. The chemical states and distribution of elements Ca, Al, O did not show obvious change after sputtering. The present study provides novel insights on the chemical states analysis of doped-C12A7:e(-) nanoparticles

Controller Design and Analysis of Spacecraft Automatic Levelling and Equalizing Hoist Device based on Hanging Point Adjustment

Spacecraft Automatic Levelling and Equalizing Hoist Device (SALEHD) is a kind of hoisting device developed for eccentric spacecraft level-adjusting, based on hanging point adjustment by utilizing XY-workbench. To make the device automatically adjust the spacecraft to be levelling, the controller for SALEHD was designed in this paper. Through geometry and mechanics analysis for SALEHD and the spacecraft, the mathematical model of the controller is established. And then, the link of adaptive control and the link of variable structure control were added into the controller to adapt the unknown parameter and eliminate the interference of support vehicle. The stability of the controller was analysed, through constructing Lyapunov energy function. It was proved that the controller system is asymptotically stable, and converged to origin that is equilibrium point. So the controller can be applied in SALEHD availably and safely

Effect of ammonia stress on nitrogen metabolism of Ceratophyllum demersum

The objective of the present study was to determine the effect of total ammonia N concentration and pH on N metabolism of Ceratophyllum demersum and to evaluate stress as a result of inorganic N enrichment in the water column on submerged macrophytes. Carefully controlled pH values distinguished between the effects of un-ionized NH3 and ionized NH4+. The results showed that the most obvious consequence of ammonia addition was an overall increase in ammonia content and decrease in nitrate content in all tissues of fertilized plants. The activities of nitrate reductase and glutamine synthetase were inhibited by long-term ammonia addition. At the same time, ammonia addition significantly decreased soluble protein content and increased free amino acid content in all treatments. Another clear effect of ammonia addition was a decrease in carbon reserves. Therefore, the authors concluded that increased ammonia availability could affect plant survival and lead to a decline in C. demersum proliferation through a decrease in their carbon reserves. This interaction between N and C metabolism helps to explain changes in benthic vegetation as a result of steadily increasing coastal water eutrophication