National Institute Of Materials Physics - Romania

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91. Aminopropyl-silica functionalized with halogen-reactive compounds for antimicrobial applications
Authors: Zarafu, I; Al Taweel, AAJ; Limban, C; Popa, M; Marutescu, L; Chifiriuc, MC; Pircalabioru, GG; Culita, D; Ghica, C; Ionita, P

Published: FEB 1 2020, MATERIALS CHEMISTRY AND PHYSICS, 241, 122353, DOI: 10.1016/j.matchemphys.2019.122353

Aminopropyl-silica nanoparticles S0 were obtained and further functionalized with eight halogen-reactive organic compounds 1-8, leading to the S1-S8 hybrid organic-inorganic materials, with spherical morphology and having a 50-200 nm size, as showed TEM analysis. These were further characterized by IR and DLS. Biological assays were performed using five microbial strains, belonging to species frequently encountered in the aetiology of human infections (Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia toll and Candida albicans). The obtained materials exhibited promising antimicrobial properties, being active against planktonic, but particularly on biofilm-embedded cells. Among the tested hybrid nanomaterials, S6 seemed to exhibit the most promising antimicrobial profile.
92. Investigations of BaCl2:Eu2+ nanophosphor using electron paramagnetic resonance, structural analysis and thermoluminescence
Authors: Secu, CE; Rostas, AM

Published: JAN 30 2020, JOURNAL OF ALLOYS AND COMPOUNDS, 815, 152400, DOI: 10.1016/j.jallcom.2019.152400

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.
93. HRTEM analysis of the high-temperature phases of the newly developed high-temperature Ni-base superalloy VDM 780 Premium
Authors: Ghica, C; Solis, C; Munke, J; Stark, A; Gehrmann, B; Bergner, M; Rosler, J; Gilles, R

Published: JAN 25 2020, JOURNAL OF ALLOYS AND COMPOUNDS, 814, 152157, DOI: 10.1016/j.jallcom.2019.152157

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.
94. Cytotoxicity, Antioxidant, Antibacterial, and Photocatalytic Activities of ZnO-CdS Powders
Authors: Zgura, I; Preda, N; Enculescu, M; Diamandescu, L; Negrila, C; Bacalum, M; Ungureanu, C; Barbinta-Patrascu, ME

Published: JAN 1 2020, MATERIALS, 13, 182, DOI: 10.3390/ma13010182

In this work, ZnO-CdS composite powders synthesized by a simple chemical precipitation method were thoroughly characterized. The morphological, structural, compositional, photocatalytical, and biological properties of the prepared composites were investigated in comparison with those of the pristine components and correlated with the CdS concentration. ZnO-CdS composites contain flower-like structures, their size being tuned by the CdS amount added during the chemical synthesis. The photocatalytic activity of the composites was analyzed under UV irradiation using powders impregnated with methylene blue; the tests confirming that the presence of CdS along the ZnO in composites can improve the dye discoloration. The biological properties such as antioxidant capacity, antibacterial activity, and cytotoxicity of the ZnO, CdS, and ZnO-CdS composites were evaluated. Thus, the obtained composites presented medium antioxidant effect, biocidal activity against Escherichia coli, and no toxicity (at concentrations less than 0.05 mg/mL for composites with a low CdS amount) for human fibroblast cells. Based on these results, such composites can be used as photocatalytic and/or biocidal additives for photoactive coatings, paints, or epoxy floors, which in their turn can provide a cleaner and healthier environment.
95. Reduced Graphene Oxide Sheets as Inhibitors of the Photochemical Reactions of alpha-Lipoic Acid in the Presence of Ag and Au Nanoparticles
Authors: Toulbe, N'ghaya; Stroe, Malvina S; Daescu, Monica; Cercel, Radu; Mogos, Alin; Dragoman, Daniela; Socol, Marcela; Mercioniu, Ionel; Baibarac, Mihaela

Published: Nov 11 2020, , DOI: 10.3390/nano10112238

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.
96. Photoluminescence as a Valuable Tool in the Optical Characterization of Acetaminophen and the Monitoring of Its Photodegradation Reactions
Authors: Daescu, Monica; Matea, Adelina; Negrila, Catalin; Serbschi, Constantin; Ion, Alina C; Baibarac, Mihaela

Published: Oct 07 2020 , , DOI: 10.3390/molecules25194571

97. Enhanced critical current density at high magnetic fields in MgB2 with Ga/In acetylacetonate processed by spark plasma sintering
Authors: Batalu, D; Aldica, G; Burdusel, M; Grigoroscuta, M; Pasuk, I; Kuncser, A; Ionescu, AM; Badica, P

Published: MAY-JUN 2020, JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, 9, DOI: 10.1016/j.jmrt.2020.01.109

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.
98. Attempts to improve the self-cleaning effect of the textile materials
Authors: Dumitrescu, I; Iordache, OG; Mitran, CE; Perdum, E; Sandulache, IM; Secareanu, LO; Sobetkii, A; Diamandescu, L

Published: 2020, INDUSTRIA TEXTILA, 71, DOI: 10.35530/IT.071.03.1626

The objective of this study is to investigate the methods to create durable self-cleaning textiles by coating fabrics with TiO2-(1%)Fe-N-graphene (2%). To improve the adherence of the nanoparticles, the polyester/cotton woven fabrics were pre-treated with polyacrylic acid (PA), carboxymethylcellulose (CMC) and polyethylene polyamine resin (EZF). The pre-treated materials were immersed in a doped TiO2 for 30 minutes at 40 degrees C and dried at 125 degrees C. The finished fabrics were stained with methylene blue dye and exposed to visible light. The SEM images show the presence of particles on polymers layers firmly attached on the material surface. The treatments determine the decrease of the exothermic peak (452.48 degrees C), characteristic of the cellulose decomposition, demonstrating an increase of the thermal conductivity of the materials. The doped TiO2-graphene induces a double degradation of methylene blue in comparison with untreated material and the materials treated with CMC, polyacrylic acid and cationic polymer. The effect is maintained after washing.
99. DEPOSITION AND CHARACTERIZATION OF THIN FILMS BASED ON NANOSTRUCTURED WO3 AS SENSORIAL ELEMENTS FOR DETECTION O F H2S
Authors: Sobetkii, A; Olaru, MT; Cindemir, U; Osterlund, L; Stanoiu, A; Simion, CE; Bejan, SE; Irimescu, RE

Published: 2020, REVISTA ROMANA DE MATERIALE-ROMANIAN JOURNAL OF MATERIALS, 50, DOI:

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.
100. Therapeutic Use of Inorganic Nanomaterials in Malignant Diseases
Authors: Lupu, AR; Popescu, T; Stojanovic, M

Published: 2020, ENVIRONMENTAL NANOTECHNOLOGY, VOL 3, 27, DOI: 10.1007/978-3-030-26672-1_2

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.

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