268 research outputs found
Rietveld refinement of the mixed boracite Fe1.59Zn1.41B7O13Br
The structural characterization of the new iron–zinc heptaÂborate bromide with composition Fe1.59Zn1.41B7O13Br, prepared by chemical transport is reported. A rigid-body model with constrained generalized coordinates was defined in order to hold the positions of the B atoms at reasonable interÂatomic distances that typically would reach unacceptable values because of the weak scattering power of boron. There are three independent sites for the B atoms of which two are tetraÂhedrally coordinated. The bond-valence sum around the third B atom, located on a threefold rotation axis, was calculated considering two cases of coordination of boron with oxygens: trigonal-planar and tetrahedral. The contribution of the fourth O atom to the bond-valence sum was found to be only 0.06 v.u., indicating the presence of a very weak bond in the right position to have a distorted tetraÂhedral coordination in favour of the trigonal-planar coordination for the third B atom. X-ray fluorescence (XRF) was used to determinate the Fe/Zn ratio
Genotypic and phenotypic properties of Candida parapsilosis sensu strictu strains isolated from different geographic regions and body sites
<p>Abstract</p> <p>Background</p> <p><it>Candida parapsilosis </it>is known to show limited genetic variability, despite different karyotypes and phenotypes have been described. To further investigate this aspect, a collection of 62 <it>sensu strictu </it><it>C. parapsilosis </it>independent isolates from 4 geographic regions (Italy, n = 19; New Zealand, n = 15; Argentina, n = 14; and Hungary, n = 14) and different body sites (superficial and deep seated) were analysed for their genetic and phenotypic traits. Amplification fragment length polymorphism (AFLP) analysis was used to confirm species identification and to evaluate intraspecific genetic variability. Phenotypic characterisation included clinically relevant traits, such as drug susceptibility, in vitro biofilm formation and aspartyl protease secretion.</p> <p>Results</p> <p>AFLP genotyping showed little variation among isolates, when the presence/absence of bands was considered. However, when AFLP profiles were compared by relative intensity for each fragment, a significant level of variation and geographical clustering was observed. All isolates were found to be susceptible to commonly used antifungals, although a reduced susceptibility to echinocandins was observed in all isolates. <it>C. parapsilosis </it>isolates from different geographic origins varied in the number of biofilm producers, with a higher prevalence of producers isolated in Hungary and Argentina. The frequency of secreted proteinase producers also varied in isolates obtained from different areas, with a higher number of proteinase producers found in Italy and New Zealand. Interestingly, biofilm production and proteinase secretion were negatively correlated. This finding could be explained by assuming that proteinase activity plays a role in detachment and release from a mature biofilm, via degradation of <it>C. parapsilosis </it>adhesins and/or extracellular matrix components, as observed for other microorganisms.</p> <p>Conclusions</p> <p>The low number of polymorphic AFLP bands (18 out of 80) obtained for <it>C. parapsilosis </it>isolates is in agreement with the limited sequence variability described for this species. However, when band intensity was included in the analysis, geographical clustering was observed. Expression of virulence factors varied among strains isolated from different geographical regions, with biofilm and proteinase producers more frequently isolated from Hungary and Italy, respectively.</p
Effects of a 12-Week Suspension versus Traditional Resistance Training Program on Body Composition, Bioimpedance Vector Patterns, and Handgrip Strength in Older Men: A Randomized Controlled Trial
This investigation aimed to compare the effects of suspension training versus traditional resistance exercise using a combination of bands and bodyweight on body composition, bioimpedance vector patterns, and handgrip strength in older men. Thirty-six older men (age 67.4 ± 5.1 years, BMI 27.1 ± 3.3 kg/m2) were randomly allocated into suspension training (n = 12), traditional training (n = 13), or non-exercise (n = 11) groups over a 12-week study period. Body composition was assessed using conventional bioelectrical impedance analysis and classic and specific bioelectric impedance vector analysis, and handgrip strength was measured with a dynamometer. Results showed a significant (p < 0.05) group by time interaction for fat mass, fat-free mass, total body water, skeletal muscle index, classic and specific bioelectrical resistance, classic bioelectrical reactance, phase angle, and dominant handgrip strength. Classic and specific vector displacements from baseline to post 12 weeks for the three groups were observed. Handgrip strength increased in the suspension training group (p < 0.01, ES: 1.50), remained stable in the traditional training group, and decreased in the control group (p < 0.01, ES: -0.86). Although bodyweight and elastic band training helps to prevent a decline in muscle mass and handgrip strength, suspension training proved more effective in counteracting the effects of aging in older men under the specific conditions studied
Identification of distinct lymphocyte subsets responding to subcellular fractions of Mycobacterium bovis bacille calmette-Guerin (BCG)
In order to investigate the ability of Mycobacterium bovis BCG vaccination to induce immune responses toward different classes of mycobacterial antigens and the cell populations involved in such responses, proliferation of distinct human lymphocyte subsets from BCG-vaccinated donors in response to different subcellular fractions of BCG was analysed and compared with that of not sensitized subjects. Proliferation of different cell subsets was evaluated by flow cytometric determination of bromodeoxyuridine incorporated into DNA of dividing cells and simultaneous identification of cell surface markers. Although a certain degree of variability was observed among different donors, after 6 days of in vitro stimulation BCG-vaccinated subjects displayed, as a mean, a stronger blastogenic response to all the classes of antigens compared with non-sensitized ones. PPD, culture filtrates and membrane antigens induced a predominant proliferation of CD4(+) T cells. In contrast, preparations enriched in cytosolic antigens elicited strong proliferation of gamma delta(+) T cells which, as a mean, represented 55% of the proliferating cells. Although to a lesser extent, proliferation of gamma delta(+) T cells was also elicited by preparations enriched in membrane and cell wall antigens. In response to the latter preparation proliferation of CD4(+) T cells and CD16(+)/CD3(-) (natural killer (NK)) cells was observed, as well. In particular, cell wall antigens were found to induce significantly higher levels of proliferation of NK cells compared with all the other classes of antigens
In vitro bactericidal activity of human beta-defensin 3 against multidrug-resistant nosocomial strains
The antimicrobial activity of human beta-defensin 3 (hBD-3) against multidrug-resistant clinical isolates of Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii was evaluated. A fast bactericidal effect (within 20 min) against all bacterial strains tested was observed. The presence of 20% human serum abolished the bactericidal activity of hBD-3 against gram-negative strains and reduced the activity of the peptide against gram-positive strains
Intraocular pressure changes following the use of silicone oil or Densiron® 68 as endotamponade in pars plana vitrectomy
OBJECTIVE: To compare the effects of standard silicone oil 5700 (SSO) and heavy silicone oil (HSO) such as Densiron(®) 68 on intraocular pressure (IOP).
MATERIALS AND METHODS: Retrospective case series including 180 eyes (105 treated with SSO and 75 with HSO). IOP was measured before surgery, 1 day after, and then at 1-, 3-, 6-, and 12-month follow-ups.
RESULTS: In the SSO group, a significant increase in IOP occurred in 14% of the eyes (15/105) at 1 day postoperatively, and persisted in 11.4% (12/105) at 1-month follow-up. In the HSO group, a persistent elevated IOP was recorded in 20% of the eyes (15/75) at 1 day postoperatively, and in 16% (12/75) at 1-month follow-up. At 12-month follow-up, mean IOP was 16.7 ± 8.7 mmHg and 19.7 ± 3.8 mmHg, respectively, in the SSO and HSO groups. The difference between the 2 groups was always not significant.
CONCLUSION: Overall, the use of Densiron 68 was not associated with higher IOP values as compared with SSO
Retrieval of phase relation and emission profile of quantum cascade laser frequency combs
The major development recently undergone by quantum cascade lasers has
effectively extended frequency comb emission to longer-wavelength spectral
regions, i.e. the mid and far infrared. Unlike classical pulsed frequency
combs, their mode-locking mechanism relies on four-wave mixing nonlinear
processes, with a temporal intensity profile different from conventional
short-pulses trains. Measuring the absolute phase pattern of the modes in these
combs enables a thorough characterization of the onset of mode-locking in
absence of short-pulses emission, as well as of the coherence properties. Here,
by combining dual-comb multi-heterodyne detection with Fourier-transform
analysis, we show how to simultaneously acquire and monitor over a wide range
of timescales the phase pattern of a generic frequency comb. The technique is
applied to characterize a mid-infrared and a terahertz quantum cascade laser
frequency comb, conclusively proving the high degree of coherence and the
remarkable long-term stability of these sources. Moreover, the technique allows
also the reconstruction of electric field, intensity profile and instantaneous
frequency of the emission.Comment: 20 pages. Submitted to Nature Photonic
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