National Institute Of Materials Physics - Romania

Structural analysis of the Eu2+-doped BaCl2 nanocrystals and the doping process was monitored and characterized via electron paramagnetic resonance spectroscopy. Structural analysis has shown a slight distortion of the cell which is reflected in the low value of microstrain and the Eu2+-doping effect is limited to the first order chlorine ions neighbors of Ba2+. Electron paramagnetic resonance measurements have indicated the presence of the Eu2+-dopant ions in the BaCl2 host matrix with a solubility limit of about 2%. From the spectra simulation, the isotropic g-value g(iso) = 1.9951(7), the isotropic hyperfine coupling constant A(iso)= 42.4 MHz and the high-order zero-field splitting parameters from the crystal field B-2(0) = 21 MHz and B-2(2)= -493 MHz were obtained. During X-ray irradiation, defects are produced and stabilized by the Eu2+ dopant ions. The single dominant thermoluminescence peak at 132 degrees C (activation energy E = 1.1 eV) was assigned to the recombination of the F(Cl)-center with Eu2+ related hole centers. (C) 2019 Elsevier B.V. All rights reserved.

VDM 780 Premium is a recently developed Ni-based superalloy designed for working at high service temperatures (above 650 degrees C) while keeping the good workability of alloy 718. VDM 780 Premium is based on the austenitic matrix (gamma phase) strengthened by intermetallic Ni3Al-like precipitates (gamma' phase, fcc L1(2) structure). Other co-precipitates may be formed in function of the applied heat treatment, such as Ni3Nb-based (delta phase, orthorhombic DOa structure) or Ni3Ti-based (eta phase, hexagonal DO24 structure) precipitates. The amount as well as the size and morphology of the different precipitates depend on the heat treatments performed on the alloy, playing an important role in improving the creep properties or the behavior during forging and recrystallization. This work contains a complex study using various techniques of analytical electron microscopy and synchrotron diffraction intended to clarify the structure of the high-temperature phase formed in the newly developed VDM 780 Premium alloy. The atomic structure of the high-temperature plate-like precipitates formed in VDM 780 Premium after two different thermal treatments has been investigated in relation with the surrounding matrix lattice, proving the stacked delta/eta structure of the precipitates. (C) 2019 Published by Elsevier B.V.

The influence of Ag and Au nanoparticles and reduced graphene oxide (RGO) sheets on the photodegradation of alpha-lipoic acid (ALA) was determined by UV-VIS spectroscopy. The ALA photodegradation was explained by considering the affinity of thiol groups for the metallic nanoparticles synthesized in the presence of trisodium citrate. The presence of excipients did not induce further changes when ALA interacts with Ag and Au nanoparticles with sizes of 5 and 10 nm by exposure to UV light. Compared to the Raman spectrum of ALA powder, changes in Raman lines' position and relative intensities when ALA has interacted with films obtained from Au nanoparticles with sizes between 5 and 50 nm were significant. These changes were explained by considering the chemical mechanism of surface-enhanced Raman scattering (SERS) spectroscopy. The photodegradation of ALA that had interacted with metallic nanoparticles was inhibited in the presence of RGO sheets.

Neoplastic disease has multifactorial etiology and insidious evolution which make it unlikely to be detected in early stages and very difficult to treat at later times. The effectiveness of standard therapeutic approaches is limited by severe adverse effects, metastasis, and tumor capacity to develop multidrug resistance. The success of inorganic nanomaterial-based therapeutic agents depends on the degree to which these nanostructures satisfy general requirements for drug safety regarding biocompatibility, biodegradability, and stability and on their antitumor efficacy. Fabrication of such nanomedicines requires adequate assessment and engineering of nanomaterial physicochemical characteristics like particle size, specific surface area, surface charge, hydrodynamic size, and magnetic, optical, and photocatalytic properties. Together with surface functionalization and delivery method, these properties dictate the in vivo "biological identity" of the nanomaterial and its fate with respect to cellular uptake and distribution/accumulation inside the body. We reviewed recent literature on interdisciplinary studies regarding applications of inorganic nanomaterials in the treatment of cancer. The major functions that inorganic nanomaterials can play in cancer therapy are: 1. Nanocarriers for therapeutic agents and active targeting ligands for molecules overexpressed on tumor tissues as well as for altered signal transduction pathways. Inorganic nanomaterial-based therapeutic agents are able to reduce tumor growth acting on neoplastic vasculature (by inhibiting angiogenesis, vasculogenesis, and vasculogenic mimicry) or on malignant cells (blocking activation of overexpressed receptors and their specific signaling pathways, inducing oxidative stress, and reducing multidrug resistance). Moreover, inorganic nanomaterials are able to inhibit tumor invasiveness and metastasis by reducing degradation of extracellular matrix, exosome secretion, and cell proliferation at the secondary site. 2. Contrast agents and medical adhesives in cancer surgery: (i). Vital staining of sentinel lymph nodes (SLNs) where the first metastasis appears - the use of carbon nanoparticles, single-walled and multilayer carbon nanotubes, or superparamagnetic iron oxide nanoparticles was associated with a significantly higher number of harvested SLNs in breast and cervical tumors, lung cancer, papillary thyroid carcinoma, and prostate carcinoma. (ii). Nanoparticle-based medical adhesives used for surgical wound closure aqueous suspensions of iron oxide and silicon dioxide nanoparticles were shown to rapidly connect highly vascularized tissues (e.g., liver). 3. Inorganic sensitizers for radiotherapy - gold nanoparticles were reported to significantly enhance the efficiency of ionizing radiation and induce targeted cancer cell apoptosis, tumor growth inhibition, and increases of survival rates in tumor-bearing mice. 4. Antitumor agents based on specific material properties like surface plasmon resonance (photothermal heating), magnetic responsiveness (magnetic hyperthermia), and photocatalysis (photodynamic therapy) - heat generated by plasmonic (gold-based) or magnetic (iron oxide-based) nanomaterials exposed to laser light or alternating magnetic fields, respectively, was shown to efficiently destroy tumors in mouse models or leads to promising results in clinical trials; the antitumor action of photoactivated TiO2-based nanomedicines was assessed in numerous in vitro and several in vivo studies. 5. Adjuvant therapy (iron replacement therapy) - iron oxide colloids (IOC) are more efficient than free iron in treating iron-deficient anemia associated with cancer. Overall, inorganic-organic therapeutic nanoplatforms provide enhanced treatment efficiency, reduced adverse effects, multiple antitumor action mechanisms, facile cell internalization, and diminished multidrug resistance.

Thin nanostructured films are the state-of-the-art materials for detection of very low limits of toxic gases. The work presents a comparison between the properties of WO3 thin films obtained by two different deposition techniques: Advanced Gas Deposition (AGD) and DC Reactive Sputtering. Films have been characterized by XRD, SEM and XPS. WO3-based sensors have selective sensitivity in H2S detection at operating temperature of 200 degrees C and relative humidity specific to field applications. The potential interferences with CO2, SO2 and NH3 are negligible, highlighting the application potential of WO3.

Indium-doped tin oxide (ITO) thin films were fabricated by radio frequency magnetron sputtering and were subjected to in-situ and ex-situ annealing, at 200 degrees C, 300 degrees C and 400 degrees C, respectively. The in-situ thermal treatment consisted to intentionally heating the samples' substrates, while the ex-situ annealing was performed using an oven, under ambient atmosphere. For the ITO samples subjected to ex-situ annealing, the density of oxygen vacancies increased leading to the decrease of the electrical resistivity. No significant changes were noticed in terms of transmission spectroscopy after the thermal treatment; while by evaluating the Skewness parameter was determined that the annealing improves the planarity of samples' surface.

Dense samples (94-96%) with starting composition (MgB2)(0.99)(X-acac)(0.01) (X-acac denotes Ga or In acetylacetonate) were obtained by spark plasma sintering. The resulting material is a superconducting composite, where carbon substitutes for boron in the crystal structure of MgB2. Added samples show enhanced critical current density at high magnetic fields and this is reflected in high values of irreversibility field (H-irr) at temperatures below 25 K when compared to a pristine sample. More efficient is In-acac addition and it promotes a H-irr of similar to 12.4T (100 A/cm(2) criterion) at 5 K. Carbon substitution for boron in the crystal structure of MgB2 has a strong influence on the pinning force and its related parameters and promotes in the added samples a grain boundary pinning mechanism as the dominant one, whereas the pristine sample with a low amount of carbon shows a major mechanism of point pinning type. However, our analysis indicates on the synergetic effects of the carbon substituting for boron and of the microstructural details on pinning and critical current density. The result strongly emphasizes the significantly different behavior of the additive during processing of the MgB2 samples, although thermal analysis experiments on both additives show very similar decomposition patterns. (C) 2020 The Authors. Published by Elsevier B.V.

The 1600 nm-extended SWIR photoresponse of SiGe/TiO2 multilayers with Ge-rich SiGe nanocrystals (NCs) is demonstrated. The SiGe NCs based multilayers are obtained by magnetron sputtering deposition of TiO2/ 6x(Ge/SiGe/Ge/TiO2) layers on heated p-Si substrate followed by rapid thermal annealing (RTA). Grazing incidence X-ray diffraction and Raman spectroscopy evidence the formation of cubic Ge-rich SiGe NCs and anatase TiO2. ITO/Ge-rich SiGe NCs based multilayer /p-Si heterostructure diodes, fabricated by depositing top ITO and bottom Al contacts, show n-p behavior. Photocurrent-voltage characteristics measured at 100 K under integral light illumination of reverse biased diode present a photocurrent higher with up to 2 orders of magnitude than the dark current. Spectral photocurrent increases with bias voltage increase and presents a bandgap-related cutoff wavelength of similar to 1600 nm due to the high Ge content of SiGe NCs.

Mixtures of B4C, alpha-AlB12 and B powders were reactively spark plasma sintered at 1800 degrees C. Crystalline and amorphous boron powders were used. Samples were tested for their impact behavior by the Split Hopkinson Pressure Bar method. When the ratio R = B4C/alpha-AlB12 >= 1.3 for a constant B-amount, the major phase in the samples was the orthorhombic AlB24C4, and when R < 1 the amount of AlB24C4 significantly decreased. Predictions that AlB24C4 has the best mechanical impact properties since it is the most compact and close to the ideal cubic packing among the Al-B-C phases containing B-12-type icosahedra were partially confirmed. Namely, the highest values of the Vickers hardness (32.4 GPa), dynamic strength (1323 MPa), strain and toughness were determined for the samples with R = 1.3, i.e., for the samples with a high amount of AlB24C4. However, the existence of a maximum, detectable especially in the dynamic strength vs. R, indicated the additional influence of the phases and the composite's microstructure in the samples. The type of boron does not influence the dependencies of the indicated mechanical parameters with R, but the curves are shifted to slightly higher values for the samples in which amorphous boron was used.