Raman investigations of the radiation-induced modifications in iPP-VGCNF nanocomposites: The nanofillers’ tale

Nanocomposites of isotactic polypropylene loaded by various amounts of vapor-grown carbon nanotubes ranging from 0 to 20% wt. were obtained by extrusion. Raman investigations on these nanocomposites are reported. The nanocomposites were irradiated using a 60Co, with an integral dose of 1 kGy/h up to integral doses of 9 kGy, 18 kGy, and 27 kGy, in air, at room temperature. Raman measurements were performed by using a Bruker Senterra confocal Raman spectrometer operating at 785 nm. The research is focused on the information contained within the D and G Raman lines of these nanocomposites as a function of nanotube loading for various integral doses. The experimental data revealed the graduate silencing of the molecular motions assigned to the polymeric matrix due to the nanofiller and ionizing radiation. Based on experimental data, it is concluded that the positions of the D and G lines exhibit faint shifts due to the irradiation and that (on average) these shifts are consistent with the changes of the positions of D and G lines upon the increase of the loading with vapor-grown carbon nanofibers. Raman data suggest that the irradiation relaxes the pressure exerted on the nanofiller by the polymeric matrix, indicating a path to improve the physical features of polymer-carbon nanostructure nanocomposites. The research demonstrates the capability of Raman spectroscopy to sense the modifications of molecular vibrations in polymer-based nanocomposites, for both the polymeric matrix and the nanofiller

Variants of the arterial vascularization of the hip

Catedra de anatomie a omului, Universitatea de Stat de Medicină și Farmacie ,,Nicolae Testemițanu”, Chișinău, Republica Moldova, Conferința Ştiinţifică Internaţională ”Probleme actuale ale morfologiei” dedicată celor 70 de ani de la fondarea Universității de Stat de Medicină și Farmacie „Nicolae Testemiţanu”, Chişinău, 15-16 octombrie 2015Abstract Background: The variability of the arterial vessels of the thigh has a primordial importance in different surgical interventions such as angioplasty or other various catheterizations Material and methods: Varied anatomic studies from different periods of time and from different countries was analyzed and stored in order to create some schemes of variants of thigh vascularization by using bioinformatics studies. Results: Femoral artery, deep femoral artery, medial and lateral circumflex femoral arteries have a large range of differentiation starting with different directions and origins which vary from person to person. Besides this their framework differ from one limb to another, for example the medial circumflex femoral artery has 3 more popular anatomic variants of origin, there are from femoral artery, from deep femoral artery or it has a common trunk with deep femoral artery, other data about are exposed in context. Conclusions: Surgical interventions involving hip should be done being in consideration the anatomical variants of the blood vessels supply. Even more nowadays new methods of catheterization through different vessels are available

Complex Risks from Old Urban Waste Landfills: Sustainability Perspective from Iasi, Romania

Landfills continue to represent the most frequent managerial practice for municipal solid wastes and an increasing and complex problem globally. In certain countries, a transition to an open society and free market is superimposed on the transition to sustainability, resulting in even higher complexity of management. This paper proposes an approach for problem-structuring of landfills in complex transitions: sustainability or unsustainability of a management approach is determined by a set of sustainability filters that are defined by sets of indicators and prioritized according the systemic concept of sustainability, which says that economy is embedded in society, which is embedded in nature. The writers exercise this approach with an old landfill in Iasi, Romania, and conclude for unsustainability, because the ecological sustainability filter is not successfully passed. Social and economic sustainability filters are also discussed in relation with the ecological sustainability indicators. The described approach allows a coherent, transdisciplinary synthesis of knowledge scattered across various disciplines, a pervasive problem in landfill management. The case study helps distinguish between generally true and context-dependent aspects.Peer reviewe

Photostimulated luminescence in BaX2 : Eu2+ (X=Br, Cl) X-ray storage phosphors

The photostimulated luminescence (PSL) effect in BaX2 :Eu (2+) (X=Br, Cl) is comparable to that observed in BaFBr:Eu2+ which is used in commercial X-ray storage phosphor screens. After X- irradiation the PSL stimulation spectra of BaX2 :Eu (2+) (X=Br, Cl) single crystals are identical to the F centre absorption spectra, i.e. the F centres are the PSL-active electron trap centres. The nature of the hole centres is still unknown. The PSL response time of about 0.70 mus is within experimental error of 0.02 mus identical to the Eu2+ radiative lifetime, whereas in BaCl2 :Eu2+ the PSL response time is 0.60 mus, and thus longer than the Eu2+ radiative lifetime of 0.47 mus

Defect structures and (ferro)magnetism in Zn1-xFexO nanoparticles with the iron concentration level in the dilute regime (x = 0.001 – 0.01) prepared from acetate precursors

Zn1-xFexO nanoparticles with the iron concentrations level in the dilute regime (x = 0.001–––0.01) were produced by a sol–gel route from acetate precursors along with an un-doped and 3 at.% Fe-doped reference. The X-ray diffraction of the un-doped and 0.1–1 at.% Fe-doped samples reveal the reflections for only the ZnO wurtzite structure. Fe doping enhances the a-axis lattice constant, the unit cell volume and the microstrain. Iron doping reduces the average crystallite/particle size (confirmed by Scanning Electron Microscopy), improving the surface-to-volume ratio or the concentration of defective surface sites. XPS identifies the iron in both Fe3+ and Fe2+ states. XPS and 57Fe Mossbauer spectroscopy indicate a broad distribution (distortion) of Fe3+ sites on the surface of ZnO nanoparticles. The blue shift and broadening of the UV emission, and quenching of defect-related photoluminescence in the Fe-doped samples verify the presence of iron in the ZnO lattice and surface intrinsic defects. 0.1–1 at.% Fe-doped ZnO show room temperature ferromagnetism, RTFM, characteristic of dilute magnetic semiconductors, DMS. The magnetization measurements with temperature evidence an antiferromagnetic alignment and an increase of ferromagnetic contribution with Fe doping up to 1 at.%. Zn0.97Fe0.3O reference is a superparamagnetic ZnO/ZnFe2O4 nanocomposite with a blocking temperature of 20 K; HRTEM shows (ultra)fine ZnFe2O4 particles at the surface of ZnO nanoparticles. The analysis of experimental data of 0.1–1 at.% Fe-doped ZnO was done in terms of iron coupling with intrinsic defects, which can generate surface Fe3+ states with geometries similar to the Fe3+ in inverse spinel ZnFe2O4. The superexchange interaction (resembling that in the inverse spinel ZnFe2O4) between the Fe3+ sites with distorted configuration resulting in ferrimagnetism was hypothesised as a possible mechanism of RTFM. Experimental (structural, local chemical, magnetic, optical) and interpretation results can be used to optimize the processing conditions for Fe-doped ZnO to serve as an effective DMS, e.g. for spintronic applications