Samarium Magnetism Studied on SmPd2Al3 Single Crystal

In this paper, specific features of Sm magnetism in an intermetallic compound have been studied. For this purpose, a high-quality single crystal of SmPd2Al3 was grown and subjected to detailed measurements of specific heat, magnetization, ac susceptibility, and electrical resistivity with respect to temperature and a magnetic field applied along the principal crystallographic directions. SmPd2Al3 magnetism was found to be strongly anisotropic with the easy-magnetization direction along the c axis where the main magnetic features are concentrated. The a-axis response remains weak, paramagneticlike, even in the magnetically ordered state. Ferromagnetism with TC=12.4 K has been indicated by all the measured physical properties. At lower temperatures, three successive order-order phase transitions have been observed on the temperature dependence of the specific heat as three anomalies: at 3.4, 3.9, and 4.4 K, respectively. The low-temperature magnetization data can be understood within a scenario that considers the antiferromagnetic ground state as being gradually destroyed through a series of four metamagnetic transitions at 0.03, 0.35, 0.5, and 0.75 T, as detected in the 1.8 K magnetization data. The experimental data are discussed together with the results of electronic-structure and crystal-field calculations from first principles, which were performed as an important part of the study for comprehension and explanation of the observed behavior of the SmPd2Al3 compound

Representation of a solution of the Cauchy problem for an oscillating system with two delays and permutable matrices

We represent a solution of an inhomogeneous second-order differential equation with two delays by using matrix functions under the assumption that the linear parts are given by permutable matrices.Зображення розв’язку задачi кошi для коливної системи з двома запiзнюваннями та переставними матрицям

Different Sensitivity to Isoprenalin in Mice of Two Strains and Its Changes with Age

. Parameters of locomotor activity of mice of two strains (conventional male [CBA x C57BL] 10 Fi mice and Conventional random breed male ICR mice) are reported together with their per cent mortality after administration of isoprenaIin (ISO) at 400 mg • kg-i, 700 mg . kg-i and 750 mg/kg body mass in mice aged 3 months and at 400 mg . kg-i body mass in animals aged 5 months. Age-dependent changes in body mass and myocardial mass were assessed. It is concluded that mice of the two strains differed in their sensitivity to ISO. The o:served higher resistance of (CBA x C57BL/I0) Fl mice to ISO toxicity can be related to their higher locomotor activity and lower I::ody mass. Isoprenalin, mice, myocardium, staircase test The sensitivity to isoprenalin (ISO) is conditioned by a number of factors the quality of which varies from species to species (Venault et aI. 1986). Of particular importance is the cardiotoxic effect of ISO inducing myocardial lesions of coagulative myocytolysis (COAM) type with subsequent development of necroses In conventional male (CBA x C57BL/I0) Fi mice no significant biochemical or morphological myocardial changes have been found after administration of ISO in doses of 10 to 100 mg. kg-I body mass which are used routinely in rats (Fleckenstein et aI. 1977; Materials and Methods The experimental animals were 60 conventional male (CBA x C57BL/I0) Fl mice (breeding colony of Institute of Biophysics, Czechoslovak Academy of Sciences, Bmo) aged 3 months and having 33.3 ± 1.8 g in body mass and 50 conventional random breed male ICR mice (breeding colony of VELAZ, Prague, Czechoslovakia) aged 3 months and having 37.4 ± 3.0 g in body mass. One week before the experiment the mice were transferred to the laboratory and kept ther

Highly synergistic antimicrobial activity of magainin 2 and PGLa peptides is rooted in the formation of supramolecular complexes with lipids

Magainin 2 and PGLa are cationic, amphipathic antimicrobial peptides which when added as equimolar mixture exhibit a pronounced synergism in both their antibacterial and pore-forming activities. Here we show for the first time that the peptides assemble into defined supramolecular structures along the membrane interface. The resulting mesophases are quantitatively described by state-of-the art fluorescence self-quenching and correlation spectroscopies. Notably, the synergistic behavior of magainin 2 and PGLa correlates with the formation of hetero-domains and an order-of-magnitude increased membrane affinity of both peptides. Enhanced membrane association of the peptide mixture is only observed in the presence of phophatidylethanolamines but not of phosphatidylcholines, lipids that dominate bacterial and eukaryotic membranes, respectively. Thereby the increased membrane-affinity of the peptide mixtures not only explains their synergistic antimicrobial activity, but at the same time provides a new concept to increase the therapeutic window of combinatorial drugs

Light-Induced Nanosecond Relaxation Dynamics of Rhenium-Labeled Pseudomonas aeruginosa Azurins.

Time-resolved phosphorescence spectra of Re(CO)3(dmp)+ and Re(CO)3(phen)+ chromophores (dmp = 4,7-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline) bound to surface histidines (H83, H124, and H126) of Pseudomonas aeruginosa azurin mutants exhibit dynamic band maxima shifts to lower wavenumbers following 3-exponential kinetics with 1-5 and 20-100 ns major phases and a 1.1-2.5 μs minor (5-16%) phase. Observation of slow relaxation components was made possible by using an organometallic Re chromophore as a probe whose long phosphorescence lifetime extends the observation window up to ∼3 μs. Integrated emission-band areas also decay with 2- or 3-exponential kinetics; the faster decay phase(s) is relaxation-related, whereas the slowest one [360-680 ns (dmp); 90-140 ns (phen)] arises mainly from population decay. As a result of shifting bands, the emission intensity decay kinetics depend on the detection wavelength. Detailed kinetics analyses and comparisons with band-shift dynamics are needed to disentangle relaxation and population decay kinetics if they occur on comparable timescales. The dynamic phosphorescence Stokes shift in Re-azurins is caused by relaxation motions of the solvent, the protein, and solvated amino acid side chains at the Re binding site in response to chromophore electronic excitation. Comparing relaxation and decay kinetics of Re(dmp)124K122Cu II and Re(dmp)124W122Cu II suggests that electron transfer (ET) and relaxation motions in the W122 mutant are coupled. It follows that nanosecond and faster photo-induced ET steps in azurins (and likely other redox proteins) occur from unrelaxed systems; importantly, these reactions can be driven (or hindered) by structural and solvational dynamics

Identification of ground instability in the housing estate complex based on georadar and satellite radar interferometry

Procedures of using ground penetrating radar (GPR) and Sentinel-1 satellite synthetic aperture radar (SAR) were tested in the area of housing estates in Hodonín, where there is an intensive decrease in the subsoil and thus a significant cracking of prefabricated houses. Extensive geophysical research of the site provided essential information about active faults in the area. To prove them and define the most active deformation zones (blocks), where the maximum settlement of the subsoil occurs, the processed interferometric (InSAR) data from the Sentinel-1 SAR satellite were used. Results from joint evaluation of geophysical data and InSAR not only confirmed detected deformations but also notified on other locations with tendencies to subsidence in the neighborhood of main faults. The combination of the methods to identify displacement tendencies in urbanized areas is very effective

Amino acid oxidation of the D1 and D2 proteins by oxygen radicals during photoinhibition of Photosystem II

The Photosystem II reaction center is vulnerable to photoinhibition. The D1 and D2 proteins, lying at the core of the photosystem, are susceptible to oxidative modification by reactive oxygen species that are formed by the photosystem during illumination. Using spin probes and EPR spectroscopy, we have determined that both O2 -and HO are involved in the photoinhibitory process. Using tandem mass spectroscopy, we have identified a number of oxidatively modified D1 and D2 residues. Our analysis indicates that these oxidative modifications are associated with formation of HO at both the Mn4O5Ca cluster and the nonheme iron. Additionally, O2 -appears to be formed by the reduction of O2 at either PheoD1 or QA. Early oxidation of D1:332H,which is coordinatedwith theMn1 of the Mn4O5Ca cluster, appears to initiate a cascade of oxidative events that lead to the oxidative modification of numerous residues in the C termini of the D1 and D2 proteins on the donor side of the photosystem. Oxidation of D2:244Y, which is a bicarbonate ligand for the nonheme iron, induces the propagation of oxidative reactions in residues of the D-de loop of the D2 protein on the electron acceptor side of the photosystem. Finally, D1: 130E and D2: 246Mare oxidatively modified by O2 -formed by the reduction of O2 either by PheoD1 -or QA -. The identification of specific amino acid residues oxidized by reactive oxygen species provides insights into the mechanism of damage to the D1 and D2 proteins under light stress

Active Detectors for Plasma Soft X-Ray Detection at PALS

This paper summarizes the work carried out for an experimental study of low-energy nuclear excitation by laser-produced plasma at the PALS Prague laser facility. We describe the adaptation and shielding of single-quantum active radiation detectors developed at IEAP CTU Prague to facilitate their operation inside the laser interaction chamber in the vicinity of the plasma target. The goal of this effort is direct real-time single-quantum detection of plasma soft X-ray radiation with energy above a few keV and subsequent identification of the decay of the excited nuclear states via low-energy gamma rays in a highly radiative environment with strong electromagnetic interference

Resistance to Antibiotics in Strains of Staphylococcus spp., Enterococcus spp. and Escherichia coli Isolated from Rectal Swabs of Pigs

The study aimed at determining the level of resistance of selected bacterial species (Staphylococcus spp., Enterococcus spp., Escherichia coli) isolated from rectal swabs of pigs to antimicrobial agents. The tested strains were isolated from piglets aged 7 to 30 days. Bacterial species were identified by standard microbiological techniques and susceptibility to antibiotics was determined quantitatively by the standard microdilution method. Resistance of the Staphylococcus aureus strain to oxacillin was confirmed by detection of the mecA gene and PBP2a. A total of 115 Staphylococcus spp. isolates were collected. In the case of Staphylococcus aureus, the methicillin-resistant strain (MRSA) was identified. Moreover, higher frequency of coagulase-negative staphylococci with minimum inhibitory concentration of oxacillin ≥ 0.5 mg/l was noticed. Inducible resistance to clindamycin in the Staphylococcus hominis strain was also detected. The strains of Enterococcus spp. (61 isolates) exhibited high resistance to tetracycline (98.5%), erythromycin (86.8%) and chloramphenicol (54.4%). Vancomycin-resistant enterococci were not isolated. In the case of Escherichia coli strains (111 isolates), higher frequency of resistant strains to tetracycline (81.1%) and ampicillin (62.2%) was documented. Resistance to fluoroquinolones and production of broad-spectrum β-lactamases was not noticed. The presented study may be considered as a pilot project assessing the prevalence of resistant bacteria in piglets kept on a single farm. It demonstrated the presence of resistant strains of Staphylococcus spp., including one MRSA strain, Enterococcus spp. and Escherichia coli. These strains may be present as a result of postnatal colonization with both bacterial microflora of dams and environmental microflora