Superconductivity in the PbO-type structure α-FeSe Hsu, Fong-Chi; Luo, Jiu-Yong; Yeh, Kuo-Wei ...
Proceedings of the National Academy of Sciences - PNAS,
09/2008, Letnik:
105, Številka:
38
Journal Article
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The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides LaO₁₋xFx FeAs by Kamihara et al. Kamihara Y, Watanabe T, ...Hirano M, Hosono H (2008) Iron-based layered superconductor LaO1-xFx FeAs (x = 0.05-0.12) with Tc = 26 K. J Am Chem Soc 130:3296-3297. was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type α-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors.
Antimicrobial peptides, such as bacteriocin, produced by probiotics have become a promising novel class of therapeutic agents for treating infectious diseases. Selected lactic acid bacteria (LAB) ...isolated from fermented foods with probiotic potential were evaluated for various tests, including exopolysaccharide production, antibiotic susceptibility, acid and bile tolerance, antibacterial activity, and cell adhesion and cytotoxicity to gastric cell lines. Six selected LAB strains maintained their high viability under gastrointestinal conditions, produced high exopolysaccharides, showed no or less cytotoxicity, and adhered successfully to gastric cells. Furthermore, three strains, Weissella confusa CYLB30, Lactiplantibacillus plantarum CYLB47, and Limosilactobacillus fermentum CYLB55, demonstrated a strong antibacterial effect against drug-resistant Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica serovar Choleraesuis, Enterococcus faecium, and Staphylococcus aureus. Whole genome sequencing was performed on these three strains using the Nanopore platform; then, the results showed that all three strains did not harbor genes related to toxins, superantigens, and acquired antimicrobial resistance, in their genome. The bacteriocin gene cluster was found in CYLB47 genome, but not in CYLB30 and CYLB55 genomes. In SDS-PAGE, the extract of CYLB30 and CYLB47 bacteriocin-like inhibitory substance (BLIS) yielded a single band with a size of less than 10 kDa. These BLIS inhibited the growth and biofilm formation of drug-resistant P. aeruginosa and methicillin-resistant S. aureus (MRSA), causing membrane disruption and inhibiting adhesion ability to human skin HaCaT cells. Moreover, CYLB30 and CYLB47 BLIS rescued the larvae after being infected with P. aeruginosa and MRSA infections. In conclusion, CYLB30 and CYLB47 BLIS may be potential alternative treatment for multidrug-resistant bacteria infections.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•We report 3+2 cycloaddition reactions of alkyne with the ruthenium azido complex.•The stable triazolato and tetrazolato products obtained in all cases were N(2)-bound.•We report that during ...protonation of ruthenium azido complex, methylene insertion accidentally took place, to yield unusual boron-methylated product.•Their structures are elucidated by IR, NMR and X-ray crystallography.
Herein, we report on the reactivity of an Ru(II) azido complex allowing the facile synthesis of further interesting complexes. Starting from the parent chlorido complex (HN=CPh2)Ru−Cl {1, Ru = Tp(PPh3)Ru; Tp = HB(pz)3, pz = pyrazolyl)} the title complex (HN=CPh2)Ru−N3 (2) was obtained upon reaction with NaN3. The N(2)-bound 4,5-bis-(methoxycarbonyl)-1,2,3-triazolato complex (HN=CPh2)Ru−{N3C2(CO2Me)2} (3) was obtained from reaction of 2 with dimethyl acetylene dicarboxylate (DMAD). Protonation of 3 with HCl afforded the N-coordinated triazolato complex {HN3C2(CO2Me)2}Ru−Cl (4). Reaction of CS2 with 2 produced the thiocyanato complex (HN=CPh2)Ru−NCS (5). The Ru tetrazolato complex (HN=CPh2)Ru−N4CC(CN)=C(CN)2 (6) was prepared from 2 and tetracyanoethylene (TCNE). The reaction of 2 with HX gave the 17-electron Ru(III) complexes (Cl)Ru−X (7a, X = Cl; 7b, X = Br) and the Ru(II) complexes containing the methyl tris(pyrazolyl)borate ligand MeTp(PPh3)(HN=CPh2)Ru−X (8a, X = Cl; 8b, X = Br), as a result of an unusual methylene insertion into the B−H bond of the Tp ligand with the CH2Cl2 solvent as the assumed source for the methylene. The structures of 4, 5, 7a, 7b and 8b had been determined by X-ray diffraction analysis.
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Myopia is regarded as a worldwide epidemic ocular disease, has been proved related to inflammation. CD55, also known as decay-accelerating factor (DAF) can modulate the activation of complement ...through inhibiting the formation of complement 3 convertase and its dysregulation is involved in various inflammatory diseases. To investigate the association between CD55 and myopia, and to test whether CD55 can inhibit myopia development by suppressing inflammation in the eye, we use three different animal models including monocular form-deprivation myopia, myopia induced by TNF-α administration and allergic conjunctivitis animal model to reveal the CD55 in myopia development. The tears of thirty-eight participants with different spherical equivalents were collected and CD55 in the tears were also analyzed. Complement 3 and complement 5 levels increased while CD55 levels decreased in allergic conjunctivitis and myopic eyes. After anti-inflammatory drugs administration, CD55 expression was increased in monocular form-deprivation myopia model. We also found inflammatory cytokines TGF-β, IL-6, TNF-α, and IL-1β may enhance complement 3 and complement 5 activation while CD55 level was suppressed contrary. Moreover, lower CD55 levels were found in the tears of patients with myopia with decreased diopter values. Finally, CD55-Fc administration on the eyelids can inhibit the elongation of axial length and change of refractive error. CD55-Fc application also suppress myopia development subsequent to complement 3 and complement 5 reduction and can lower myopia-specific (MMP-2 and TGF-β) cytokine expression in TNF-α induced myopia animal model. This suggests that CD55 can inhibit myopia development by suppression of complement activation and eventual down-regulation of inflammation.
•CD55-Fc administration kept down the elongation of axial length and the change if refractive error in myopic eyes.•CD55 expression decreased in tears pf patients with higher spherical equivalent.•Activation of complementary system and inflammatory cytokines were involved in myopia development.•CD55 can inhibit myopia development via suppressing the complementary system and downregulating the inflammation.
Quercetin, a flavonoid abundantly present in plants, is widely used as a phytotherapy in prostatitis and prostate cancer. Although quercetin has been reported to have a number of therapeutic effects, ...the cellular target(s) responsible for its anti-cancer action has not yet been clearly elucidated. Here, employing affinity chromatography and mass spectrometry, we identified heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) as a direct target of quercetin. A specific interaction between quercetin and hnRNPA1 was validated by immunoblotting and in vitro binding experiments. We found that quercetin bound the C-terminal region of hnRNPA1, impairing the ability of hnRNPA1 to shuttle between the nucleus and cytoplasm and ultimately resulting in its cytoplasmic retention. In addition, hnRNPA1 was recruited to stress granules after treatment of cells with quercetin for up to 48 h, and the levels of cIAP1 (cellular inhibitor of apoptosis), an internal ribosome entry site translation-dependent protein, were reduced by hnRNPA1 regulation. This is the first report that anti-cancer effects of quercetin are mediated, in part, by impairing functions of hnRNPA1, insights that were obtained using a chemical proteomics strategy.
Multilevel resistive switching (RS) of gadolinium oxide (Gd x O y ) memristors treated by hydrogen plasma immersion ion implantation (PIII) was investigated. Hydrogen ions were implanted at the Pt/Gd ...x O y interface to modify the oxygen-vacancy distribution, which was examined by the X-ray photoelectron spectroscopy. After the hydrogen PIII treatment, a forming process is needed to operate the Gd x O y memristors and the RS mechanism is changed from Schottky emission to space-charge-limited conduction. Superior multilevel RS properties such as data retention for more than 10 4 s at 85°C, and sequentially cycling test for more than 10 3 times with a resistance ratio of approximately one order of magnitude between each state are realized, making the future high-density flash memory possible.
A phase transition was observed in the tetragonal FeSe superconductor under high pressure at around 2.55GPa using X-ray scattering and Raman spectrum. From X-ray powder diffraction (XRD) experiments, ...the slope of the unit cell volume versus pressure curve change slightly at around 2.55–4GPa, and the Bragg peaks of FeSe tetragonal phase disappear when the pressure reaches 11.4GPa. We also found the superconducting transition temperature Tc increases and reaches a maximum value of ∼37K at ∼3–4GPa. The compressibility value (dV/dP) shows an abrupt change from 2.39(Å3/GPa) to 0.94(Å3/GPa) from pressure values of 0–2.55GPa to 2.55–11.4GPa. A similar phase transition was also observed in the Raman spectra under pressure.
This study investigated the effect of nitriding surface treatment on the corrosion resistance of commercial dental alloy, in the form of helical nickel–titanium (Ni–Ti) files, when treated with 5.25% ...sodium hypochlorite (NaOCl) solution. The surface of dental helical Ni–Ti files was modified using nitriding treatment at 200
°C, 250
°C and 300
°C in an NH
3-containing environment. The surface morphology and chemical composition of the Ni–Ti files were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance of the Ni–Ti files when treated with a clinical solution of 5.25% NaOCl was evaluated using the linear polarization method and by potentiodynamic polarization curve measurement. The nitriding treatments at different temperatures created titanium nitride (TiN) on the surface of the helical Ni–Ti files. The Ni–Ti files nitrided at 200
°C and 250
°C showed higher polarization resistance and higher passive film breakdown potential together with a lower passive current than untreated files. The presence of TiN on dental Ni–Ti files significantly increased the corrosion resistance of the files in the presence of 5.25% NaOCl solution.
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