The aim of this study was to prepare and characterize the glasses made of x(Fe
O
∙V
O
)∙(100 - x)P
O
∙CaO with x ranging of 0-50%. The contribution of Fe
O
and V
O
amount on the structure of P
O
·CaO ...matrix was investigated. The vitreous materials were characterized by XRD (X-ray diffraction analysis), EPR (Electron Paramagnetic Resonance) spectroscopy, and magnetic susceptibility measurements. A hyperfine structure typical for isolated V
ions was noticed to all spectra containing low amount of V
O
The XRD spectra show the amorphous nature of samples, apart x = 50%. An overlap of the EPR spectrum of a broad line without the hyperfine structure characteristic of clustered ions was observed with increasing V
O
content. The results of magnetic susceptibility measurements explain the antiferromagnetic or ferromagnetic interactions expressed between the iron and vanadium ions in the investigated glass.
The fabrication of composite magnetorheological elastomers (MRECs) based on silicone rubber, carbonyl iron microparticles (10% vol.) and polyurethane elastomer doped with 0%, 10% and 20% volume ...concentration TiO2 microparticles is presented. The obtained MRECs have the shape of thin foils and are used as dielectric materials for manufacturing plane capacitors. Using the plane capacitor method and expression of capacitance as a function of magnetic field intensity, combined with linear elasticity theory, the static magnetoelastic model of the composite is obtained and analyzed.
Preliminary small-angle neutron scattering investigations on aqueous suspensions of several cobalt doped ferrites (CoxFe3-xO4, x=0; 0.5; 1) nanoparticles prepared by chemical co-precipitation method, ...are reported. The measurements were accomplished at the YuMO instrument in function at the IBR-2 reactor. Results of intermediary data treatment are presented and discussed.
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•Magnetic microfibers from iron oxides were adopted for MR application.•Electrical capacity and electrical resistance of MR suspensions were examined.•Magnetic microfibers exhibit ...typical MR behavior from rheological test.
Four types of magnetorheological (MR) suspensions with four different amounts of iron oxide microfibers were prepared. Electrical devices made with these MR suspensions were introduced into a static magnetic field, being superimposed over AC field with a standard frequency of 1 kHz to measure their both equivalent electrical capacity and equivalent electrical resistance. The components of the complex dielectric permittivity obtained are influenced by the amounts of microfibers, and the relative dielectric permittivity and dielectric loss coefficient increase with magnetic field strength. The obtained effects are due to the species of iron oxides in the microfibers used in the manufacture of MR suspensions. The viscoelastic characteristics of MR suspensions were examined by steady shear flow and dynamic oscillatory tests using a rheometer under different magnetic field strengths. The Ms value of the iron micro-fibers was 22.7Am2kg, and the shear stress curves were fitted well using Herschel-Bulkley equation to find the yield stress, which was up to 98 Pa in a magnetic field of 257 kA/m.
The crystallographic texture of the whole valves of bivalve mollusks from the family Unionidae
Linnaeus, 1758 and
Linnaeus, 1758 is studied using pole figures measured using neutron diffraction. The ...use of neutron diffraction, in contrast to X-rays, makes it possible to study the valves without destroying them. Thus, we can discuss the study of the global texture of the entire valve. It was revealed that the pole figures of aragonite in the valves repeat their shape. The pole density maxima for
from the Danube Delta and the Gulf of Finland in the Baltic Sea, living at different salinities and temperatures, differs by 0.41 mrd. The maximum value of the crystallographic texture for
from the Danube Delta was also measured (5.07 mrd). In terms of texture sharpness, it surpasses the shell of marine bivalve mollusks, which are partially or completely composed of aragonite. Although
and
Linnaeus, 1758 have different microstructures, their pole figures are very similar in isolines pattern, but differ in pole density maxima. No relationship was found between the crystallographic texture and the microstructure in
. In addition, we report good qualitative agreement between aragonite X-ray pole figures of
Lea, 1834 from the Czech river Luznice, and neutron pole figures of
from the Danube Delta.
CTX-M betalactamases have shown a rapid spread in the recent years among Enterobacteriaceae and have become the most prevalent Extended Spectrum Beta-Lactamases (ESBLs) in many parts of the world. ...The introduction and dissemination of antibiotic-resistant genes limits options for treatment, increases mortality and morbidity in patients, and leads to longer hospitalization and expensive costs. We aimed to identify the beta-lactamases circulating encoded by the genes
,
and
in
and
strains. Furthermore, we established the associated resistance phenotypes among patients hospitalized in the Intensive Care Unit (ICU) from County Clinical Emergency Hospital of Craiova, Romania.
A total of 46 non-duplicated bacterial strains (14 strains of
and 32 strains of
), which were resistant to ceftazidime (CAZ) and cefotaxime (CTX) by Kirby-Bauer disk diffusion method, were identified using the automated VITEK2 system. Detection of ESBL-encoding genes and other resistance genes was carried out by PCR.
strains were resistant to 3rd generation cephalosporins and moderately resistant to quinolones, whereas
strains were resistant to penicillins, cephalosporins, and sulfamides, and moderately resistant to quinolones and carbapenems. Most
strains harbored
gene (13/14 strains), a single strain had the
gene, but 11 strains harbored
gene. The
gene was not detected. We detected
(A) gene in six strains and
(B) in one strain. In
strains we detected
in 23 strains,
-
in all strains and
in 14 strains. The colistin resistance gene
was not detected. The tetracycline gene
(A) was detected in 11 strains, but the gene
(B) was not detected in any strains.
The development in antibiotic resistance highlights the importance of establishing policies to reduce antibiotic use and improving the national resistance surveillance system in order to create local antibiotic therapy guidelines.
•Natural convection flow inside vertical cylinders fluctuates in a periodic way.•Axial heat transfer occurred primarily by advection.•Radial heat transfer occurred primarily by conduction.•Three ...dimensional vortices improve heat transfer.
Vertical cylindrical enclosures are used in the crystal growth industry as crystal growth reactors. Gallium nitride crystals are grown in ammonothermal growth reactors that requires temperatures in the range of 600–1000 K (620–1340 °F) and pressures in the range of 1000–6000 bar (14,504–87,022 psi). The process conditions make any experimental measurements difficult, in particular, flow pattern visualization and velocity measurements. A geometrically similar transparent reactor and similar fluid dynamic conditions for crystal growth were used in the process of experimental observation and measurement of the flow. Boundary and fluid temperatures along with velocity vectors were recorded. The flow proved to be oscillating in nature with steady and uniform time-averaged patterns. Fluid temperatures showed a higher standard deviation in the mixing region suggesting that the fluctuations are stronger at this location. Flow patterns and fluid temperatures indicated that the heat transfer between the two sections is driven by conduction and advection.
Titanium-based composites-titanium and silver (TiAg) and titanium and carbon (TiC)-were synthesized by the Thermionic Vacuum Arc (TVA) method on substrates especially for gear wheels and camshaft ...coating as mechanical components of irrigation pumps. The films were characterized by surface morphology, microstructure, and roughness through X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Small-Angle Neutron Scattering (SANS). The silver (Ag) films crystallized into a cubic system with lattice a = 4.0833 Å at room temperature, indexed as cubic Ag group Fm3m. The crystallites were oriented in the 111 direction, and mean grain size was
= 265 Å. The TiC structure revealed a predominant cubic TiC phase, with a = 0.4098 as a lattice parameter determined by Cohen's method. Average roughness (Ra) was 8 nm for the as-grown 170 nm thick TiAg film, and 1.8 nm for the as-grown 120 nm thick TiC film. Characteristic SANS contribution was detected from the TiAg layer deposited on a substrate of high-quality stainless steel with 0.45% carbon (OLC45) in the range of 0.015 Å
≤ Q ≤ 0.4 Å
, revealing the presence of sharp surfaces and an averaged triaxial ellipsoidal core-shell object.
Colloidal suspensions of silver nanoparticles (AgNPs) with surface modified by capping with citrate ions were synthesized by chemical reduction method. Transmission and Scanning Electron Microscopy ...as well as darkfield Optical Microscopy provided information on the nanoparticle morphology, with fine symmetrical grains and log-normal fitted size distribution. Small Angle X-ray Scattering method allowed theoretical confirmation of colloidal silver nanoparticle fine granularity, based on measurements in the native fluid sample. UV–Vis spectrophotometry allowed studying the Localized Surface Plasmon Resonance band versus the stability of the citrate-AgNP sample after storage and after UV-C exposure. The colloidal AgNP impact on Phanerochaete chrysosporium environmental microorganisms was studied by specific biochemical investigations. Silver released from the colloidal suspension of AgNPs was supposed to induce changes in some antioxidant enzymes and in some enzymes of Krebs’ cycle. Catalase activity was moderately changed (an increase with over 50%) as well as superoxide dismutase activity, while the diminution of the activities of four dehydrogenases synthesized in the fungus mycelium was emphasized also: a decrease with about 60% for malate dehydrogenase, with over 50% for isocitrate dehydrogenase and succinate dehydrogenase and with about 40% for alpha-ketoglutarate dehydrogenase. These findings suggested the nano-toxicological issues of citrate-AgNPs impact on the environmental beneficial microorganisms.
•Ferrihydrite NPs are not affecting the organization of DPPC liposome membranes•Cholesterol present in the membrane can modulate NPs effect on membrane organization•Co and Cu doped NPs affect more ...the membranes as compared with Ferrihydrite NPs
In recent years was observed an increased interest towards the use of metal nanoparticles for various biomedical applications, such as therapeutics, delivery systems or imaging. As biological membranes are the first structures with which the nanoparticles interact, it is necessary to understand better the mechanisms governing these interactions. In the present paper we aim to characterize the effect of three different ferrihydrite nanoparticles (simple or doped with cooper or cobalt) on the fluidity of model lipid membranes. First we evaluated the physicochemical properties of the nanoparticles: size and composition. Secondly, their effect on lipid membranes was also evaluated using Laurdan, TMA-DPH and DPH fluorescence. Our results can help better understand the mechanisms involved in nanoparticles and membrane interactions.
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