Observation of a Griffiths-like phase in the paramagnetic regime of ErCo_2

A systematic x-ray magnetic circular dichroism study of the paramagnetic phase of ErCo2 has recently allowed to identify the inversion of the net magnetization of the Co net moment with respect to the applied field well above the ferrimagnetic ordering temperature, Tc. The study of small angle neutron scattering measurements has also shown the presence of short range order correlations in the same temperature region. This phenomenon, which we have denoted parimagnetism, may be related with the onset of a Griffiths-like phase in paramagnetic ErCo2. We have measured ac susceptibility on ErCo2 as a function of temperature, applied field, and excitation frequency. Several characteristics shared by systems showing a Griffiths phase are present in ErCo2, namely the formation of ferromagnetic clusters in the disordered phase, the loss of analyticity of the magnetic susceptibility and its extreme sensitivity to an applied magnetic field. The paramagnetic susceptibility allows to establish that the magnetic clusters are only formed by Co moments as well as the intrinsic nature of those Co moments

Molecular genetics of naringenin biosynthesis, a typical plant secondary metabolite produced by Streptomyces clavuligerus

Background: Some types of flavonoid intermediates seemed to be restricted to plants. Naringenin is a typical plant metabolite, that has never been reported to be produced in prokariotes. Naringenin is formed by the action of a chalcone synthase using as starter 4-coumaroyl-CoA, which in dicotyledonous plants derives from phenylalanine by the action of a phenylalanine ammonia lyase. Results: A compound produced by Streptomyces clavuligerus has been identified by LC-MS and NMR as naringenin and coelutes in HPLC with a naringenin standard. Genome mining of S. clavuligerus revealed the presence of a gene for a chalcone synthase (ncs), side by side to a gene encoding a P450 cytochrome (ncyP) and separated from a gene encoding a Pal/Tal ammonia lyase (tal). Deletion of any of these genes results in naringenin non producer mutants. Complementation with the deleted gene restores naringenin production in the transformants. Furthermore, naringenin production increases in cultures supplemented with phenylalanine or tyrosine. Conclusion: This is the first time that naringenin is reported to be produced naturally in a prokariote. Interestingly three non-clustered genes are involved in naringenin production, which is unusual for secondary metabolites. A tentative pathway for naringenin biosynthesis has been proposedThis work was supported by Grant BIO2012-34723 from the Spanish Ministry of Economy and Competitivity. R. Álvarez-Álvarez received a FPU fellowship from the Spanish Ministry of Education, Culture and Sport

Surface phase transitions in BiFeO3 below room temperature

We combine a wide variety of experimental techniques to analyze two heretofore mysterious phase transitions in multiferroic bismuth ferrite at low temperature. Raman spectroscopy, resonant ultrasound spectroscopy, EPR, X-ray lattice constant measurements, conductivity and dielectric response, specific heat and pyroelectric data have been collected for two different types of samples: single crystals and, in order to maximize surface/volume ratio to enhance surface phase transition effects, BiFeO3 nanotubes were also studied. The transition at T=140.3K is shown to be a surface phase transition, with an associated sharp change in lattice parameter and charge density at the surface. Meanwhile, the 201K anomaly appears to signal the onset of glassy behaviour

HIV coinfection predicts failure of ledipasvir/sofosbuvir in treatment-naïve noncirrhotic patients with HCV genotype

The efficacy of licensed direct-acting antiviral (DAA) regimens is assumed to be the same for hepatitis C virus (HCV)–monoinfected patients (HCV-Mono) and HIV/HCV-coinfected patients (HCV-Co). However, the high sustained viral response (SVR) rates of DAA regimens and the small number of HIV-infected patients included in registration trials have made it difficult to identify predictors of treatment failure, including the presence of HIV. Methods. We compared treatment outcomes for ledipasvir/sofosbuvir (LDV/SOF) against HCV G1 in treatment-naïve HCV-Mono and HCV-Co without cirrhosis in a prospective registry of individuals receiving DAAs for HCV. Results. Up to September 2017, a total of 17 269 patients were registered, and 1358 patients (1055 HCV-Mono/303 HCV-Co) met the inclusion criteria. Significant differences between HCV-Mono and HCV-Co were observed for age, gender, and G1 subtype distribution. Among HCV-Co, 99.0% were receiving antiretroviral therapy. SVR rates for LDV/SOF at 8 weeks did not differ significantly between HCV-Mono and HCV-Co (96.9% vs 94.0%; P = .199). However, the SVR rate for LDV/SOF at 12 weeks was significantly higher for HCV-Mono than HCV-Co (97.2% vs 91.8%; P = .001). A multivariable logistic regression model including age, sex, liver stiffness, G1 subtype, HCV-RNA, HIV, and treatment duration showed the factors associated with treatment failure to be male sex (adjusted odds ratio [aOR], 2.49; 95% confidence interval [CI], 1.27–4.91; P = .008) and HIV infection (aOR, 2.23; 95% CI, 1.13–4.38; P = .020). Conclusions. The results of this large prospective study analyzing outcomes for LDV/SOF against HCV G1 in treatment-naïve noncirrhotic patients suggest that HIV infection is a predictor of treatment failure in patients with chronic hepatitis C.This work was supported by the Spanish AIDS Research Network (RD16/0025/0017), which is included in the Spanish I+D+I Plan and is co-financed by ISCIII-Subdirección General de Evaluacion and European Funding for Regional Development (FEDER), and the Fondo de Investigación de Sanidad en España (FIS)/Instituto de Salud Carlos III (Spanish Health Research Funds; PI17/00657)

Іншомовні аспекти фахової між культурної комунікації в сучасній вітчизняній і зарубіжній науковій літературі

У статті розглядаються основні напрямки сучасних вітчизняних і зарубіжних наукових досліджень з іншомовної фахової міжкультурної комунікації. Aspects of the professional foreign language of intercultural communication in modern domestic and foreign scientific literature. The paper discusses the main directions of current domestic and foreign scientific research in the field of professional foreign language intercultural communication

Visualizing chemical states and defects induced magnetism of graphene oxide by spatially-resolved-X-ray microscopy and spectroscopy

[[abstract]]This investigation studies the various magnetic behaviors of graphene oxide (GO) and reduced graphene oxides (rGOs) and elucidates the relationship between the chemical states that involve defects therein and their magnetic behaviors in GO sheets. Magnetic hysteresis loop reveals that the GO is ferromagnetic whereas photo-thermal moderately reduced graphene oxide (M-rGO) and heavily reduced graphene oxide (H-rGO) gradually become paramagnetic behavior at room temperature. Scanning transmission X-ray microscopy and corresponding X-ray absorption near-edge structure spectroscopy were utilized to investigate thoroughly the variation of the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups, as well as the C 2p(σ*)-derived states in flat and wrinkle regions to clarify the relationship between the spatially-resolved chemical states and the magnetism of GO, M-rGO and H-rGO. The results of X-ray magnetic circular dichroism further support the finding that C 2p(σ*)-derived states are the main origin of the magnetism of GO. Based on experimental results and first-principles calculations, the variation in magnetic behavior from GO to M-rGO and to H-rGO is interpreted, and the origin of ferromagnetism is identified as the C 2p(σ*)- derived states that involve defects/vacancies rather than the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups on GO sheets.[[notice]]補正完

Exocytotic catecholamine release is not associated with cation flux through channels in the vesicle membrane but Na+ influx through the fusion pore

Release of charged neurotransmitter molecules through a narrow fusion pore requires charge compensation by other ions. It has been proposed that this may occur by ion flow from the cytosol through channels in the vesicle membrane, which would generate a net outward current. This hypothesis was tested in chromaffin cells using cell-attached patch amperometry that simultaneously measured catecholamine release from single vesicles and ionic current across the patch membrane. No detectable current was associated with catecholamine release indicating that <2% of cations, if any, enter the vesicle through its membrane. Instead,we show that flux of catecholamines through the fusion pore, measured as an amperometric foot signal, decreases when the extracellular cation concentration is reduced. The results reveal that the rate of transmitter release through the fusion pore is coupled to net Na+ influx through the fusion pore, as predicted by electrodiffusion theory applied to fusion-pore permeation,and suggest a prefusion rather than postfusion role for vesicular cation channels

Cirrhosis-associated immune dysfunction

The term cirrhosis-associated immune dysfunction (CAID) comprises the distinctive spectrum of immune alterations associated with the course of end-stage liver disease. Systemic inflammation and immune deficiency are the key components of CAID. Their severity is highly dynamic and progressive, paralleling cirrhosis stage. CAID involves two different immune phenotypes: the low-grade systemic inflammatory phenotype and the high-grade systemic inflammatory phenotype. The low-grade systemic inflammatory phenotype can be found in patients with compensated disease or clinical decompensation with no organ failure. In this phenotype, there is an exaggerated immune activation but the effector response is not markedly compromised. The high-grade systemic inflammatory phenotype is present in patients with acute-on-chronic liver failure, a clinical situation characterized by decompensation, organ failure and high short-term mortality. Along with high-grade inflammation, this CAID phenotype includes intense immune paralysis that critically increases the risk of infections and worsens prognosis. The intensity of CAID has important consequences on cirrhosis progression and correlates with the severity of liver insufficiency, bacterial translocation and organ failure. Therapies targeting the modulation of the dysfunctional immune response are currently being evaluated in preclinical and clinical studies