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61.
Edina Rusen Bogdan Marculescu Nicoleta Preda Cristina Bucur Lucian Mihut 《Polymer Bulletin》2008,61(5):581-592
Summary The effect of fullerene on the radical polymerization of N-vinylpyrrolidone with lauroyl peroxide
in toluene was investigated kinetically. C60 was found to act both as inhibitor
and as retarder because the polymerization rate and the molecular weight of resulting poly(vinylpyrrolidone)
is decreasing with the increase of the fullerene concentration (0-6.94 x 10-4
mol l-1). The water-soluble poly(vinylpyrrolidone)-modified fullerene C60
compound was characterized by differential scanning calorimetric, Infrared and Raman spectroscopy, UV
absorption and photoluminescence. Based on the results obtained by optical measurements, it is argued
that by the covalent attachment of the polymeric radicals to fullerene cage the extended electronic
conjugation system of the C60 is broken leading to the appearance of a polyene
structure. 相似文献
62.
V. Mihalache A. Totovana V. Sandu S. Popa G. Aldica A. Iyo 《Journal of Superconductivity and Novel Magnetism》2005,18(4):461-467
Using the transport and magnetization measurements, the influence of neutron irradiation at a fluence of 5 × 1017 n cm−2 on (B0.65C0.35)Ba1.4Sr0.6Ca2Cu3O
z
has been investigated. The neutron irradiation was found to decrease critical temperature and transport critical current
density, increase the residual and normal state resistivity, and improve the intragranular critical current density with 1.6
× 105 A/cm2 (at 77.3 K and in the applied field up to 160 kA m) and ΔM
irr/ΔM
nonirr ratio (up to factor of 3) at highest field used for investigation. The field dependence of this ratio, which is below the
unity at very low field but higher than 1 at high fields, correlated with the shape of the hysteretic loops as well as with
the change of the transport parameters after irradiation suggests the role of the irradiation-induced effects on the grain
edges. We discuss these effects in the framework of the Bean-Livingstone surface barriers and geometrical barriers. 相似文献
63.
M. V. Popa E. Vasilescu P. Drob I. Demetrescu B. Popescu D. Ionescu C. Vasilescu 《工业材料与腐蚀》2003,54(4):215-221
Long‐term monitoring (for 8000 exposure hours) of titanium and its implant alloys (Ti‐5Al‐4V, Ti‐6Al‐4Fe) interactions with Ringer's solutions of different pH‐values (2.5, 4.35, 6.98), simulating various conditions that can appear at the contact between implant and tissues was carried out in this paper. All data were statistics treated using Medcalc program. In vitro electrochemical behaviour of titanium and its alloys reveals their self‐passivation in Ringer's solutions. Monitoring of the open circuit potentials with time and pH have shown that the passive films on the implant materials studied were very stable for all tested periods. Interactions due to the non‐uniformity of the physiological electrolyte pH can not produce any form of local corrosion. The tested materials present low corrosion rates which attest their very good stability for 8000 exposure hours in simulated biological environment. Surface topography characterisation using atomic force microscopy (AFM) data, correlated with the electrochemical parameters, were arguments for the stability of the samples in studied bioliquids. 相似文献
64.
Loredana Stan Teodor Malutan Irina Volf Marcel Popa Camelia E. Tincu Corneliu S. Stan 《International journal of molecular sciences》2022,23(24)
In this work, three new polymer aerogels based on 2-hydroxy ethyl methacrylate (HEMA) complexes with Eu(III), Tb(III) and La(III) are prepared and investigated. The polymer aerogels present strong photoluminescence with emissions located in the red, green and blue regions of the visible spectrum. Depending on the water content used during the preparation path, the consistency of the photoluminescent aerogels varies from rigid, regularly shaped monoliths to a flexible, fibrous material with very low density. The morpho-structural investigation was performed by FT-IR, XPS and SEM. Thermal behavior was also evaluated, while steady-state fluorescence spectroscopy, absolute PLQY and lifetime were used for the investigation of their luminescent properties. The impressive photoluminescent emission located in the red, green and blue areas of the visible spectrum is preserved irrespective of the selected porosity. Their photo-emissive properties, tunable porosity and the convenience of the preparation path could be some arguments for applications as photonic conversion mediums in special-purpose optoelectronic devices or sensors. 相似文献
65.
Nikitas Siannas Christina Zacharaki Polychronis Tsipas Dong Jik Kim Wassim Hamouda Cosmin Istrate Lucian Pintilie Martin Schmidbauer Catherine Dubourdieu Athanasios Dimoulas 《Advanced functional materials》2024,34(8):2311767
Synapses play a vital role in information processing, learning, and memory formation in the brain. By emulating the behavior of biological synapses, electronic synaptic devices hold the promise of enabling high-performance, energy-efficient, and scalable neuromorphic computing. Ferroelectric memristive devices integrate the characteristics of both ferroelectric and memristive materials and present a far-reaching potential as artificial synapses. Here, it is reported on a new ferroelectric device on silicon, a field-effect memristor, consisting of an epitaxial ultrathin ferroelectric Hf0.5Zr0.5O2 film sandwiched between an epitaxial highly doped oxide semiconductor SrTiO3-δ and a top metal. Upon a low voltage of less than 2 V, the field-effect modulation in the semiconductor enables to access multiple states. The device works in a large time domain ranging from milliseconds down to tens of nanoseconds. By gradually switching the polarization by identical pulses, the ferroelectric diode devices can dynamically adjust the synaptic strength to mimic short- and long-term memory plasticity. Ionic contributions due to redox processes in the oxide semiconductor beneficially influence the device operation and retention. 相似文献
66.
Oana Baldasici Loredana Balacescu Daniel Cruceriu Andrei Roman Carmen Lisencu Bogdan Fetica Simona Visan Andrei Cismaru Ancuta Jurj Lucian Barbu-Tudoran Valentina Pileczki Laurian Vlase Oana Tudoran Ovidiu Balacescu 《International journal of molecular sciences》2022,23(20)
Neo-adjuvant therapy (NAT) is increasingly used in the clinic for the treatment of breast cancer (BC). Pathological response to NAT has been associated with improved patients’ survival; however, the current techniques employed for assessing the tumor response have significant limitations. Small EVs (sEVs)-encapsulated miRNAs have emerged as promising new biomarkers for diagnosis and prediction. Therefore, our study aims to explore the predictive value of these miRNAs for the pathological response to NAT in BC. By employing bioinformatic tools, we selected a set of miRNAs and evaluated their expression in plasma sEVs and BC biopsies. Twelve miRNAs were identified in sEVs, of which, miR-21-5p, 221-3p, 146a-5p and 26a-5p were significantly associated with the Miller–Payne (MP) pathological response to NAT. Moreover, miR-21-5p, 146a-5p, 26a-5p and miR-24-3p were independent as predictors of MP response to NAT. However, the expression of these miRNAs showed no correlation between sEVs and tissue samples, indicating that the mechanisms of miRNA sorting into sEVs still needs to be elucidated. Functional analysis of miRNA target genes and drug interactions revealed that candidate miRNAs and their targets, can be regulated by different NAT regimens. This evidence supports their role in governing the patients’ therapy response and highlights their potential use as prediction biomarkers. 相似文献
67.
68.
Liliana Olenic Gheorghe Mihailescu Stela Pruneanu Ioan Bratu Alexandru R. Biris Dan Lupu Grigore Sigartau Lucian B. Tudoran 《Particulate Science and Technology》2005,23(1):79-83
Gold colloidal nanoparticles (GNPs) were prepared by reducing a complex of Au+. Na3Au(SO3)2 with sodium citrate. The procedure provides control of the dimension of nanoparticles produced, which is a function of reaction time and concentration of reactants. The nanoparticles were separated by centrifugation and their characteristics and dimensions were studied using UV-Vis and IR spectroscopy and transmission electronic microscopy (TEM). 相似文献
69.
To reduce the low-field electrical conductivity of interpolysilicon dielectrics used in electrically erasable programmable read-only (EEPROM) memories devices, the roughness of the poly-SiO2 interface until now has been decreased in two ways: (1) by increasing the temperature of oxidation and doping of polysilicon combined with low-pressure chemical vapor deposition (LPCVD) of silicon (undoped or in-situ doped) in the amorphous phase, or (2) by the use of LPCVD high-temperature oxide (HTO) deposited over polycrystalline silicon. The advantages of both methods are combined, and electrical conduction results for an interpoly structure based on LPCVD smooth surface polysilicon and LPCVD HTO SiO2 are presented. The data are interpreted in terms of the Fowler-Nordheim mechanism 相似文献
70.