Nickel-induced magnetic behaviour of nano-structured α-Fe2O3, synthesised by facile wet chemical route

We report the synthesis of pristine and nickel containing iron oxide (α-Fe₂O₃) nanocrystallites by facile environmentally benign wet chemical process. The magnetic behaviour of the samples has been found to change progressively with nickel content. The Mössbauer spectra revealed the precipitation of secondary phase of nickel ferrite (NiFe₂O₄) at ～2?wt% nickel contents. The transmission electron micrographs together with asymmetric magnetic hysteresis loop have confirmed the formation of core–shell structure. The Morin temperature of nanostructured α-Fe₂O₃ as estimated by superconducting quantum interference device has been found to be 257, 245, 247 and 242?K at nickel content of 0, 1, 2 and 4?wt%, respectively. The similar trends of increase/decrease in Morin temperature have been noticed by Mössbauer analysis. Furthermore, below Morin temperature, the temperature range of coexisted antiferromagnetic and ferromagnetic states has been found to increase with increase in nickel content.     

Nose-cone calorimeter: PHENIX forward upgrade

PHENIX is a high rate experiment efficient at measuring rare processes, but has limited acceptance in azimuth and pseudorapidity (η). The Nose Cone Calorimeter (NCC), a W–Si sampling calorimeter in the region of 0.9<η<3, is one of the upgrades which will significantly increase coverage in both azimuth and pseudorapidity. The NCC will expand PHENIX’s precision measurements of electromagnetic probes in η, reconstruct jets, perform a wide scope of correlation measurements, and enhance triggering capabilities. The detector will significantly contribute to measurements of γ-jet correlations, quarkonia production, and low-x nuclear structure functions. This report discusses details of the detector design and its performance concerning a sample of the physics topics which will benefit from the NCC. In view of recent funding difficulties, outlook of the activities is discussed.     

On the 3D Steady Flow of a Second Grade Fluid Past an Obstacle

We study steady flow of a second grade fluid past an obstacle in three space dimensions. We prove existence of solution in weighted Lebesgue spaces with anisotropic weights and thus existence of the wake region behind the obstacle. We use properties of the fundamental Oseen tensor together with results achieved in Koch (Quad Mat 15:59?C122, 2004) and properties of solutions to steady transport equation to get up to arbitrarily small ?? the same decay as the Oseen fundamental solution.     

Isolation of Biogenic Amines Using Paramagnetic Microparticles Off-Line Coupled with Ion Exchange Liquid Chromatography

This study aims at the possibility of single structured paramagnetic microparticles (PMPs), composed of maghemite (γ-Fe₂O₃) core modified with chitosan called MAN8, or tetraethyl orthosilicate covered with Dowex called MAN35, to be helpful for isolation of biogenic amines prior to their further analysis. Primarily, we synthesized and characterized PMPs. To obtain the information about bead morphology, scanning electron microscopy was employed. Furthermore, X-ray fluorescence was employed to carry out the elemental composition analyses. To obtain further insight into interaction between PMP surface and biogenic amines, scanning electron microscope was employed. It was shown that binding of biogenic amines causes increase of relative current response of deprotonated microparticles. We tested the specificity of PMPs to bind biogenic amines on histamine, tyramine, spermine, spermidine, putrescine, and cadaverine. We found that two types of our PMPs were able to selectively bind spermidine, cadaverine, and histamine in the case of MAN35; and histamine, tyramine, and putrescine in the case of MAN8. Finally, we carried out the analyses of real samples obtained from patients suffering from prostate carcinoma, where histamine was determined as the most abundant biogenic amine (10.456–13.654 µg mL⁻¹). The prepared PMPs were able to isolate the biogenic amines from real samples, and thus they may be helpful in construction of biosensors, or Lab-on-a-Chip platforms, enabling less painful, and more rapid diagnosis of prostate cancer.

     

Microporous carbon fibers prepared from cellulose as efficient sorbents for removal of chlorinated phenols

Research on Chemical Intermediates - Cellulose-based microporous carbon fibers (CFs) were evaluated for the adsorption of 2-Chlorophenol (CP), 2,4-Dichlorophenol (DCP), and 2,4,6-Trichlorophenol...     

Development of new classes of plasmon active nano-structures and their application in bio-sensing and energy guiding

Metal nanostructures exhibit special optical resonance modes originating fronl tile subwavelengt.h confinement of conductive electrons in the material. These resonance modes represent a strong research focus due to their application potential in optics and sensing application, in this short review recent achievements of our group in this field are highlighted. A wet-chemistry approach synthesis of advanced metallic nanostruetures will be introduced and their exact positioning and manipulation by electric field is shown. Next. the application of these nanostructures for a detection of small molecules will be described in several examples. Also, it will be shown that inetal nanostruetures can be used for sub-wavelength light focusing and for efficient energy coupling into polymer chains.     

Towards the multireference Brillouin-Wigner coupled-clusters method with iterative connected triples: MR BWCCSDT-alpha approximation

We developed and implemented an approximation of the state-specific Brillouin-Wigner coupled-cluster method with singles, doubles, and triples, called MRBWCCSDT-alpha, for a general number of closed- and open-shell reference configurations. The accuracy of the method is assessed on the calculation of the oxygen molecule in the X3sigma(g-), a1delta(g), and b1sigma(g+) states and the results of this multireference treatment are compared with previous MRBWCCSD results and with those obtained by the doubly ionized similarity transformed equation-of-motion CCSD and multireference configuration interaction methods and with experimental spectroscopic data. Explicit tests of the size-extensivity of the MRBWCCSDT-alpha method with iterative size-extensivity correction are also performed.     

Decay Curve Analysis of Alkali-Silicate Glass Exposed to Electrons

 Binary and ternary potassium, rubidium and caesium glasses were irradiated by an electron beam with energy varying from 10 to 50 keV. Alkali ion X-ray decays were recorded and afterward incubation periods were determined. The incubation period versus electron energy curves revealed thresholds, which are typical for each alkali species. The threshold ratios are proportional to the mass of the alkali species, consistent with the suggested elastic scattering assisted hopping mechanism.     

XRD,SAXS, and PALS investigations of three different polymers reinforced with tetraoctylammonium exchanged montmorillonite

Three different polymer nanocomposites were prepared using clay modified with tetraoctylammonium (4C8) surfactant. The dispersion of clay silicate layers was studied using X-ray diffraction and small-angle scattering. Free-volume cavity sizes were studied with positron annihilation lifetime spectroscopy. Scattering methods confirmed disruption of all polymer lamellae organization upon organoclay addition and the creation of partially intercalated systems for polyamide and polycaprolactone. The presence of organoclay in the polymers enlarges the lower value of average positronium lifetime τ₃ of polyamide and reduces the higher value of τ₃ for polycaprolactone and polyethylene.     

Reflexivity and sets of Fréchet subdifferentiability

We show that the sets of Fréchet subdifferentiability of Lipschitz functions on a Banach space are Borel if and only if is reflexive. This answers a question of L. Zajíček.