National Institute Of Materials Physics - Romania

This paper presents the effect of Mn2+ substitution for Co2+, in CoFe2O4 embedded in SiO2 matrix, on the structural, surface, morphological and magnetic properties. X-ray diffraction (XRD) and Mossbauer spectroscopy indicate the presence of a nanocrystalline mixed cubic spinel. In all cases, for the nanocomposites (NCs) heat-treated at 200 degrees C, a single, low crystalline ferrite phase was remarked, while for the other heat-treatment temperatures up to 1200 degrees C and with increasing Mn content, the secondary phase of alpha-Fe2O3 appears, accompanied also by the secondary phase of SiO2 at 1200 degrees C. The Fourier transform infrared (FT-IR) spectroscopy confirms the consumption of starting metallic nitrates, the formation of Co-O, Mn-O, Fe-O bonds in ferrites@SiO2 matrix. The Mossbauer spectra show the characteristic magnetic patterns of Co and Mn spinels. According to the atomic force microscopy (AFM) analysis, the particle size increases from 15 to 80 nm with the increase of Mn content. The specific surface area varies in the range 150-450 m(2)/g due to the substitution of Co2+ ion with Mn2+ ion and decreases with increasing heat treatment temperature, reaching values below 1 m(2)/g at 1200 degrees C. All NCs have pores within the mesoporous range, with high dispersion of pores' sizes. Furthermore, the release of fine nanoparticles in aqueous environment is facilitated by the powders' mesoporous structure preserved at 200, 500 and 800 degrees C heat treatment temperatures. The porous network collapse after heat treatment at 1200 degrees C leads to releasing of bigger nanoparticles, in good agreement with AFM observation. Magnetization, coercivity and anisotropy evolve proportionally with the particle size for the NCs heat-treated at 800 degrees C (M-s = 18.9-36.3 emu/g; M-R = 3.05-14.1 emu/g, H-c = 31.83-53.2 kA/m, K= 0.378.10(-3) -1.21.10(-3) erg/cm(-1)) and inverse proportionally for those heat-treated at 1200 degrees C (M-s = 30.7-19.4 emu/g; M-R = 11.60 7.20 emu/g, H-c= 127.3-15.9 kA/m, K= 2.45.10(-3)-0.19.10(-3) erg/cm(-1)). The NCs with high Mn content heat-treated at 1200 degrees C show superparamagnetic behavior, while those with low Mn content display ferrimagnetic behavior. (C) 2021 Elsevier B.V. All rights reserved.

Anodization was used to obtain a nanotubular TiO2 photoanode on F-SnO2 glass. Subsequent annealing in the CH4 atmosphere promoted the C-doping and improved the crystallinity of the TiO2 nanotubes. The pulsed laser deposition was applied to cover the nanotubes with Bi2O3, serving as a hole transport material. X-ray photoelectron spectroscopy analyses of the doped samples reveal a shift in the valence band's maximum position towards lower binding energy as compared to those observed for the undoped samples (annealed in the air). The doping positively affects the absorption by shifting the absorption edge to 567 nm. I-V measurements under illumination show that the C-doping of TiO2 increases the current density following the absorbance results. The highest open circuit voltage was reached for the samples with the 300 degrees C-deposited Bi2O3 layer, pointing to better quality of the p-n junction, hence of the contact between Bi2O3 and TiO2. This in situ annealing provided the formation of close contact between Bi2O3 and TiO2, which enabled a faster charge transport as compared to the contact obtained with no annealing or even with post annealing.

Anode materials are key to determining the energy density, cyclability and of life recyclability for Li-ion energy storage systems. High surface area materials, such as MXenes, can be manufactured with improved electrochemical properties that remove the need for polymeric binders or hazardous chemicals that pose a challenge to recycle Li-ion batteries. However, there remains a challenge to produce Li-ion anode materials that are binder free and poses energy storage characteristics that match the current carbon-based electrodes. Here we show the synthesis of N-doped MXene-TiO2 hybrid anode materials using an aqueous route. N-doped TiO2-MXene was modified using a single step continuous hydrothermal process. Capacity tests indicate an improvement from the initial specific energy capacity of 305 mAhg(-1) to 369 mAhg(-1) after 100 cycles at a charge rate of 0.1 C and a Coulombic efficiency of 99.7%. This compares to 252 mAhg(-1) for the unmodified MXene which exhibited significant capacity fade to 140 mAhg(-1). The ability to manufacture a Li-ion anode that does not require toxic chemicals for processing into an electrode and exhibits good energy storage characteristics in a binder free system is a significant step forward for energy storage applications.

In this work, thermoelectric properties of the nanocomposite materials produced via ball milling followed by spark plasma sintering from In0.2Yb0.2Co4Sb12 double filled skutterudite (SKT) with silicon and tungsten carbide inclusions are investigated. The nanocomposites with low volume ratios of beta-SiC and '-WC have a significantly increased power factor, while the lattice thermal conductivity is lowered only for beta-SiC composites. The power factor enhancement in '-WC/SKT composite compensates the increase of its thermal conductivity, and as a consequence, the maximum value of the figure of merit, 0.97, is attained for 0.33 v% 'WC at 450 degrees C, with 15% higher than that of the simple skutterudite sample. (c) 2021 Elsevier B.V. All rights reserved.

The interaction of radiation with matter takes place through energy transfer and is accomplished especially by ionized atoms or molecules. The effect of radiation on biological systems involves multiple physical, chemical and biological steps. Direct effects result in a large number of reactive oxygen species (ROS) within and outside and inside of the cells as well, which are responsible for oxidative stress. Indirect effects are defined as alteration of normal biological processes and cellular components (DNA, protein, lipids, etc.) caused by the reactive oxygen species directly induced by radiation. In this work, a classical design of an electrochemical (EC) three-electrodes system was employed for analyzing the effects of proton beam radiation on melanoma B16 cell line. In order to investigate the effect of proton radiation on the B16 cells, the cells were grown on the EC surface and irradiated. After optimization of the experimental set-up and dosimetry, the radiobiological experiments were performed at doses ranging between 0 and 2 Gy and the effect of proton beam irradiation on the cells was evaluated by the means of cyclic voltammetry and measuring the open circuit potential between working and reference electrodes.

We revisit the theoretical description of the ultrastrong light-matter interaction in terms of exactly solvable effective Hamiltonians. A perturbative approach based on polaronic and spin-dependent squeezing transforma-tions provides an effective Hamiltonian for the quantum Rabi model up to the second order in the expansion parameter. The model consistently includes both rotating and counter-rotating terms, going therefore beyond the rotating-wave approximation. Analytical and numerical results show that the proposed Hamiltonian performs better than the Bloch-Siegert model when calculating operator averages (e.g., the mean photon number and number of excitations). This improvement is due to a refined calculation of the dressed states within the present model. Regarding the frequency shift induced by the qubit-photon interaction, we find a different sign from the Bloch-Siegert value. This influences the structure of the eigenstates in a nontrivial way and ensures the correct calculation of the number of excitations associated with a given dressed state. As a consistency check, we show that the exactly solvable independent boson model is reproduced as a special limit case of the perturbative Hamiltonian.

Detailed tests and analysis of ageing effects of high irradiation dose on Multi-Strip Multi-Gap Resistive Plate Counters (MSMGRPC) based on low resistivity glass electrodes, foreseen to be used for the most forward polar angles covered by the Time-of Flight (ToF) sub-detector of the Compressed Baryonic Matter (CBM) experiment at Facility for Antiprotons and Ion Research (FAIR) - Darmstadt are reported. The tests were performed at a multi-purpose irradiation facility of IFIN-HH based on( 60)Co source. MSMGRPC efficiency, cluster size, surface and volume resistivity of the glass electrodes after irradiation are measured and compared with their values before irradiation. The results of a comprehensive analysis of the composition and properties of the deposited layers on the glass electrodes, based on different methods, i.e. Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), foil Elastic Recoil Detection Analysis (ERDA), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Terahertz Time Domain Spectroscopy (THz-TDS), are presented.

Magnetic ceramic nanoparticles system xNd(2)O(3)-(1-x)alpha-Fe2O3 (x = 0.1, 0.3 and 0.5) was synthesized by mechanochemical activation starting from hematite and neodymium oxide precursors and characterized by X-ray diffraction (XRD) and Mossbauer spectroscopy. Rietveld refinement of XRD data evidenced the formation of neodymium orthoferrite NdFeO3 as an end-product with a particle size of about 22 nm, determined using the Scherrer method for x = 0.5. The Mossbauer spectra were typically analyzed considering 2 sextets, corresponding to hematite and neodymium orthoferrite and a doublet, representing superparamagnetic particles (SPM). The recoilless fractions were determined using our dual absorber method and were found consistent with a decrease in particle size as consequence of the ball milling process performed.

Detailed tests and analysis of ageing effects of high irradiation dose on Multi-Strip Multi-Gap Resistive Plate Counters (MSMGRPC) based on low resistivity glass electrodes, foreseen to be used for the most forward polar angles covered by the Time-of Flight (ToF) sub-detector of the Compressed Baryonic Matter (CBM) experiment at Facility for Antiprotons and Ion Research (FAIR) - Darmstadt are reported. The tests were performed at a multi-purpose irradiation facility of IFIN-HH based on Co-60 source. MSMGRPC efficiency, cluster size, surface and volume resistivity of the glass electrodes after irradiation are measured and compared with their values before irradiation. The results of a comprehensive analysis of the composition and properties of the deposited layers on the glass electrodes, based on different methods, i.e. Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), foil Elastic Recoil Detection Analysis (ERDA), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Terahertz Time Domain Spectroscopy (THz-TDS), are presented.

In an attempt to increase the biological activity of the 1,2,4-triazolo[1,5-a]pyrimidine scaffold through complexation with essential metal ions, the complexes trans-[Cu(mptp)(2)Cl-2] (1), [Zn(mptp)Cl-2(DMSO)] (2) (mptp: 5-methyl-7-phenyl-1,2,4-triazolo[1,5-a]pyrimidine), [Cu-2(dmtp)(4)Cl-4]center dot 2H(2)O (3) and [Zn(dmtp)(2)Cl-2] (4) (dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine), were synthesized and characterized as new antiproliferative and antimicrobial species. Both complexes (1) and (2) crystallize in the P2(1)/n monoclinic space group, with the tetrahedral surroundings generating a square-planar stereochemistry in the Cu(II) complex and a tetrahedral stereochemistry in the Zn(II) species. The mononuclear units are interconnected in a supramolecular network through pi-pi interactions between the pyrimidine moiety and the phenyl ring in (1) while supramolecular chains resulting from C-H center dot center dot center dot pi interactions were observed in (2). All complexes exhibit an antiproliferative effect against B16 tumor cells and improved antibacterial and antifungal activities compared to the free ligands. Complex (3) displays the best antimicrobial activity against all four tested strains, both in the planktonic and biofilm-embedded states, which can be correlated to its stronger DNA-binding and nuclease-activity traits.