32 research outputs found
H-NMR spin-echo measurements of the static and dynamic spin properties in -(BETS)FeCl
H-NMR spin-echo measurements of the spin-echo decay with a
decay rate 1/ and the frequency shift under applied
magnetic field = 9 T along the a-axis over a temperature
range 2.0180 K are reported for a single crystal of the organic conductor
-(BETS)FeCl. It provides the spin dynamic and static
properties in the paramagnetic metal (PM) and antiferromagnetic insulator (AFI)
states as well as across the PMAFI phase transition. A large slow beat
structure in the spin-echo decay is observed with a typical beat frequency of
7 kHz and it varies across the spectrum. Its origin is attributed to
the HH dipole interactions rather than to the much larger
dipolar field contribution from the Fe electrons (spin = 5/2). A
simple phenomenological model provides an excellent fit to the data. The
dominant H-NMR frequency shift comes from the dipolar field from the 3d
Fe ions, and the Fe Fe exchange interactions ()
( includes the dd exchange interactions through the electrons)
have a substantial effect to the local field at the proton sites expecially at
low temperatures. A good fit is obtained with = - 1.7 K. The data of
the spin-echo decay rate 1/ indicates that there is a significant change
in the slow fluctuations of the local magnetic field at the H-sites on
traversing the PM to AFI phase. This evidence supports earlier reports that the
PMAFI phase transition in -(BETS)FeCl is driven
magnetically and first order.Comment: 9 pages, 10 figures, resubmitted to Phys. Rev. B in response to
comments of Editor and reviewers on March 23, 200
Distribution of macrolide-resistant genes among isolates of macrolideresistant Streptococcus pyogenes and Streptococcus pneumoniae in Serbia
Macrolide resistance in Streptococcus pneumoniae and in group A streptococci
(GAS) is a significant problem worldwide. In Serbia, data on the mechanisms
of resistance and the corresponding resistance genes in streptococci are
largely lacking. Therefore, we analyzed the distribution of macrolide
resistance phenotypes and genotypes in 44 macrolideresistant GAS (MRGAS) and
50 macrolide-resistant S. pneumoniae (MRSP) isolates collected in the same
period. The double disk diffusion test and PCR were used to analyze
resistance phenotypes and resistance genes, respectively. Among MRSP, the
MLSB phenotype dominated, whereas the M phenotype was the most prevalent
among MRGAS isolates. Consequently, in MRSP, the ermB gene was the most
common (n=40, 80%), followed by the mefA gene (n=7,14%). In MRGAS strains,
mefA dominated (n=27,61%), followed by ermA (n=15, 33%) and ermB (n=3, 7%).
In 3 MRSP isolates no resistance genes were detected, while one MRGAS strain
with iMLSB phenotype harbored both ermA and mefA genes
Proton NMR measurements of the local magnetic field in the paramagnetic metal and antiferromagnetic insulator phases of -(BETS)FeCl
Measurements of the H-NMR spectrum of a small ( 4 g) single
crystal of the organic conductor -(BETS)FeCl are reported
with an applied magnetic field = 9 T parallel to the a-axis in
the -plane over a temperature range 2.0 180 K. They provide the
distribution of the static local magnetic field at the proton sites in the
paramagnetic metal (PM) and antiferromagnetic insulator (AFI) phases, along
with the changes that occur at the PMAFI phase transition. The spectra have
six main peaks that are significantly broadened and shifted at low . The
origin of these features is attributed to the large dipolar field from the 3d
Fe ion moments (spin = 5/2). Their amplitude and
dependence are modeled using a modified Brillouin function that includes a
mean field approximation for the total exchange interaction () between
one Fe ion and its two nearest neighbors. A good fit is obtained using
= 1.7 K. At temperatures below the PMAFI transition temperature
= 3.5 K, an extra peak appears on the high frequency side of the
spectrum and the details of the spectrum become smeared. Also, the rms
linewidth and the frequency shift of the spectral distribution are
discontinuous, consistent with the transition being first-order. These
measurements verify that the dominant local magnetic field contribution is from
the Fe ions and indicate that there is a significant change in the
static local magnetic field distribution at the proton sites on traversing the
PM to AFI phase transition.Comment: 11 pages, 7 figures. Revised version of cond-mat/0605044 resubmitted
to Phys. Rev. B in response to comments of Editor and reviewer
YERSINIA ENTEROCOLITICA U MESU SVINJA - RIZIK ZA BEZBEDNOST HRANE
Evropska agencija za bezbednost hrane (EFSA - European Food Safety Authority)objavila je u 2011. godini preporuke za inspekciju trupova svinja. Preporuke se odnosena najznaÄajnije bioloÅ”ke opasnosti po zdravlje ljudi koje se mogu naÄi u mesu.Pored Salmonella spp., Toxoplasma gondii i Trichinella spp., kao bioloÅ”ka opasnostnavodi se i Yersinia enterocolitica. Yersinia enterocolitica, kao i druge bakterije iz familijeEnterobacteriaceae, ima sposobnost opstanka u spoljaÅ”njoj sredini, u koju dospevapreko inficiranih životinja. U Evropi, svinje su najÄeÅ”Äi asimptomatski nosiocipatogenih sojeva Y. enterocolitica za ljude, posebno soja biotipa 4 (serotipa O:3) i netako uÄestalog biotipa 2 (serotip O:9 i O:27). UzroÄnici su najÄeÅ”Äe lokalizovani uoralnoj duplji, posebno u tonzilama, submaksilarnim limfnim Ävorovima, crevima ifecesu svinja. Pravilan postupak sa trupovima svinja, nakon klanja, može znatno dasmanji nivo kontaminacije mesa svinja. UÄestalost Y. enterocolitica kod svinja, kaorezervoara ovog patogena, veoma varira. SluÄajevi jersinioze kod ljudi zabeleženi su,kako u Evropi, tako i u Japanu, SAD, Nigeriji i Brazilu
Cross-Sectional but Not Prospective Association of Accelerometry-Derived Physical Activity With Quality of Life in Children and Adolescents
Objectives: This study aims to quantify the cross-sectional and prospective associations between quality of life (QoL) and moderate-to-vigorous physical activity (MVPA).Methods: This study was based on the Swiss childrenās Objectively measured PHYsical Activity cohort. The primary endpoint is the overall QoL score and its six dimensions. The main predictor is the average time spent in MVPA per day. Linear mixed effects and linear regression models respectively were used to investigate the cross-sectional and prospective associations between MVPA and QoL.Results: There were 352 participants in the study with complete data from baseline (2013ā2015) and follow-up (2019). MVPA was positively associated with overall QoL and physical wellbeing (p = 0.023 and 0.002 respectively). The between-subject MVPA was positively associated with the overall QoL, physical wellbeing, and social wellbeing (p = 0.030, 0.017, and 0.028 respectively). Within-subject MVPA was positively associated with physical wellbeing and functioning at school (p = 0.039 and 0.013 respectively). Baseline MVPA was not associated with QoL 5Ā years later.Conclusion: Future longitudinal studies should employ shorter follow-up times and repeat measurements to assess the PA and QoL association
GM-CSF-Producing Th Cells in Rats Sensitive and Resistant to Experimental Autoimmune Encephalomyelitis
Given that granulocyte macrophage colony-stimulating factor (GM-CSF) is identified as the key factor to endow auto-reactive Th cells with the potential to induce neuroinflammation in experimental autoimmune encephalomyelitis (EAE) models, the frequency and phenotype of GM-CSF-producing (GM-CSF+) Th cells in draining lymph nodes (dLNs) and spinal cord (SC) of Albino Oxford (AO) and Dark Agouti (DA) rats immunized for EAE were examined. The generation of neuroantigen-specific GM-CSF+ Th lymphocytes was impaired in dLNs of AO rats (relatively resistant to EAE induction) compared with their DA counterparts (susceptible to EAE) reflecting impaired CD4+ lymphocyte proliferation and less supportive of GM-CSF+ Th cell differentiation dLN cytokine microenvironment. Immunophenotyping of GM-CSF+ Th cells showed their phenotypic heterogeneity in both strains and revealed lower frequency of IL-17+ IFN-gamma+, IL-17+ IFN-gamma-, and IL-17-IFN-gamma+ cells accompanied by higher frequency of IL-17-IFN-gamma- cells among them in AO than in DA rats. Compared with DA, in AO rats was also found (i) slightly lower surface density of CCR2 (drives accumulation of highly pathogenic GM-CSF+ IFN-gamma+ Th17 cells in SC) on GM-CSF+ IFN-gamma+ Th17 lymphocytes from dLNs, and (ii) diminished CCL2 mRNA expression in SC tissue, suggesting their impaired migration into the SC. Moreover, dLN and SC cytokine environments in AO rats were shown to be less supportive of GM-CSF+ IFN-gamma+ Th17 cell differentiation (judging by lower expression of mRNAs for IL-1 beta, IL-6 and IL-23/p19). In accordance with the (i) lower frequency of GM-CSF+ Th cells in dLNs and SC of AO rats and their lower GM-CSF production, and (ii) impaired CCL2 expression in the SC tissue, the proportion of proinflammatory monocytes among peripheral blood cells and their progeny (CD45(hi) cells) among the SC CD11b+ cells were reduced in AO compared with DA rats. Collectively, the results indicate that the strain specificities in efficacy of several mechanisms controlling (auto) reactive CD4+ lymphocyte expansion/differentiation into the cells with pathogenic phenotype and migration of the latter to the SC contribute to AO rat resistance to EAE
Macrolide-resistant phenotypes of invasive streptococcus pneumoniae isolates in Serbia
Macrolide resistance in Streptococcus pneumoniae has emerged as an important worldwide problem over the past decade. The aim of this study was to investigate macrolide-resistant phenotypes and the antimicrobial susceptibility patterns of invasive pneumococci in Serbia. A total of 68 invasive pneumococcal strains, collected from 2009 to 2011, were sent from regional laboratories to the National Reference Laboratory. Susceptibility testing was performed using the VITEK2 system and phenotypes were determined by triple-test. Overall penicillin and erythromycin nonsusceptibility rates were 26% and 43%, respectively. Resistance rates were higher in children than in adults. Co-resistance to penicillin and erythromycin was detected in 18% strains. Resistance rates to the third generation of cephalosporins, TMP-SXT and tetracycline were 16%, 37% and 29%, respectively. All isolates were fully susceptible to vancomycin, linezolid, fluoroquinolones, telithromycin and rifampicin. Twenty-two isolates (79%) an expressed macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype and M phenotype was found in 21% of macrolide resistant strains. [Projekat Ministarstva nauke Republike Srbije, br. 175039