Nanocrystalline Transition Metal Ferrites Synthesis, Characterization and Surface Functionalization

In this thesis, a new synthetic methodology for the high yield synthesis of spineltype transition metal ferrite nanoparticles has been developed. This approach is based on the complexation of the first-row transition metal cations with diethylene glycol (DEG) followed by the hydrolysis of the resulting chelate iron alkoxide complexes in the presence of an alkaline hydroxide. Due to the passivation of their surfaces with DEG molecules, the as-prepared nanoparticles are stable against agglomeration and can be easily dispersed in polar protic solvents (water, alcohols, etc.). Alternatively, a postsynthesis passivation with carboxylate ions can render the iron oxide nanocrystals highly dispersible in non-polar solvents. Optimization of the reaction conditions suggested that the size of the nanocrystals could be controlled by changing the complexing strength of the reaction medium. This hypothesis was verified in the case of the Fe3O4 nanoparticles: their sizes vary from 5.7 nm when the reaction is performed in neat diethylene glycol to 16.8 nm in N-methyl diethanolamine (NMDEA), whereas a 1:1 (%wt) mixture of these solvents yields nanocrystals with an average size of and 12.7 nm. A detailed characterization by using a wide variety of techniques, including powder X-Ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and 1H-NMR spectrometry was performed in order to elucidate the composition and the morphology of the variable-sized iron oxide nanoparticles. Both finite size and interparticle interaction effects were identified to influence the magnetic behavior of the oleate-capped nanosized particles. At low temperatures the Fe3O4 nanocrystals exhibit a ferromagnetic behavior with blocking temperatures which increase with the average particle size, whereas at room temperature, except for the largest nanoparticles, they undergo a superparamagnetic relaxation. We exploited the high surface reactivity of the 10 nm Fe3O4 nanoparticles to attach 2-3 nm gold grains to their surfaces through a simple, two-step chemically controlled procedure. By chemically bonding bioactive molecules to the attached Au nanoparticles these novel nanoarchitectures open up new opportunities for the implementation of the magnetic nanoparticles as a platform for various applications in the biomedical field

Disparities regarding life quality in Central and Eastern European Countries

The analysis of social indicators and the analysis of life quality are very important in order to know, in time, the changes of the main social and economic phenomena that characterize a society. To monitor the social system is a priority of modern societies because it helps to identify in time the changes of unemployment main aspects, health of population, person’s level of security, educational level, life satisfaction, and even the subjective part of life quality. The increase of life quality has to be a purpose of social and economic politics. Taking into consideration the progress and especially the life standard attained by the developed countries of the world, each country that presents deficiencies in social politics has to identify the best measures as an answer to the existing social needs. This research aims to study the disparities regarding life quality in the following Central and Eastern European Countries: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Austria, Latvia, Lithuania, FYR Macedonia, Poland, Romania, Moldavia, Slovakia, Slovenia, Serbia and Montenegro, Turkey, Ukraine, Russia, Belarus. The paper is structured as it follows: (1) introduction, (2) description of variables, (3) analysis of life quality in the Central and Eastern European Countries and (4) conclusion. The methodological approach is based on cluster analysis and the variables were selected taking into account theoretical, conceptual and practical reasons, trying to be relevant for the investigated problems and in straight connection with the analysis objectives. We try also to balance the number of the socio-economic demographic variables with the variables of the living level. From the analysis, in both cases, (with four or two groups), the revealed image is the same. There is a class of countries with a high level of life quality, characterized by a high socio-economic standard, and consequently good life conditions, and a class made of low socio-economic standard countries with low GDP, due to the inefficiency of economical politics or to the hell of civil wars and with big problems regarding corruption, civil and political liberties, life satisfaction, infant mortality and unemployment. This research offers a better understanding of macroeconomics politics effects that are promoted at the level of this region as well as their improvement.cluster analysis, life quality, matrix, dendrogram, Ward algorithm

Magnetic Characterization of Nanocrystalline Nickel Ferrite Films Processed by a Spin-Spraying Method

Highly crystalline nickel ferrite films with different chemical compositions were processed via the spin-spraying method and their morphological, structural and magnetic properties were subsequently investigated. Regardless of the chemical composition, films with variable thicknesses are constructed by 200–400 nm spherical grains grown in the direction normal to the substrate surface. Magnetization measurements show that the spinel ferrite films present a hysteretic behaviour at room temperature with a randomly oriented in-plane easy axis and an anisotropy constant K1 ≈ −2.5 × 104 erg cm−3 Furthermore, the absence of an angular dependence of the coercivity for the in-plane measurement of magnetization coupled with the ‘M’-shaped angular dependence of the out-of-plane measurement, indicates that the anisotropy of this film is predominantly crystalline shape anisotropy

Disparities regarding life quality in Central and Eastern European Countries

The analysis of social indicators and the analysis of life quality are very important in order to know, in time, the changes of the main social and economic phenomena that characterize a society. To monitor the social system is a priority of modern societies because it helps to identify in time the changes of unemployment main aspects, health of population, person’s level of security, educational level, life satisfaction, and even the subjective part of life quality. The increase of life quality has to be a purpose of social and economic politics. Taking into consideration the progress and especially the life standard attained by the developed countries of the world, each country that presents deficiencies in social politics has to identify the best measures as an answer to the existing social needs. This research aims to study the disparities regarding life quality in the following Central and Eastern European Countries: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Austria, Latvia, Lithuania, FYR Macedonia, Poland, Romania, Moldavia, Slovakia, Slovenia, Serbia and Montenegro, Turkey, Ukraine, Russia, Belarus. The paper is structured as it follows: (1) introduction, (2) description of variables, (3) analysis of life quality in the Central and Eastern European Countries and (4) conclusion. The methodological approach is based on cluster analysis and the variables were selected taking into account theoretical, conceptual and practical reasons, trying to be relevant for the investigated problems and in straight connection with the analysis objectives. We try also to balance the number of the socio-economic demographic variables with the variables of the living level. From the analysis, in both cases, (with four or two groups), the revealed image is the same. There is a class of countries with a high level of life quality, characterized by a high socio-economic standard, and consequently good life conditions, and a class made of low socio-economic standard countries with low GDP, due to the inefficiency of economical politics or to the hell of civil wars and with big problems regarding corruption, civil and political liberties, life satisfaction, infant mortality and unemployment. This research offers a better understanding of macroeconomics politics effects that are promoted at the level of this region as well as their improvement

Synthesis and magnetic properties of CoPt–poly(methylmethacrylate) nanostructured composite material

We have prepared nanometer-sized CoPt particles dispersed in a poly~methyl methacrylate~PMMA!matrix, as a novel nanostructured magnetic plastic, through a soft chemical processing route. In this work, CoPt nanoparticles were successfully synthesized from a solution phase reduction system in the presence of capping ligands and stabilizing agents at high temperature. The CoPt nanoparticles were annealed at 400 °C for 3 h, and were subsequently re-dispersed inmethylmethacrylate~monomer! . The polymerization was induced by a UV source and the hardness of final product was adjusted by varying the amount of monomeric cross-link agent. Annealed bare CoPt nanoparticles as a ‘‘core’’ material and CoPt–PMMA composite material were characterized by using energy dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction, indicating that we are able to prepare CoPt nanoparticles with 10 nm in diameter ~after annealing by employing this high temperature colloidal processing method. Magnetic investigation of this CoPt–PMMA material indicates an intrinsic coercivity of 300 Oe at 300 K and 1665 Oe at 5 K

Synthesis and magnetic properties of CoPt–poly(methylmethacrylate) nanostructured composite material

We have prepared nanometer-sized CoPt particles dispersed in a poly~methyl methacrylate~PMMA!matrix, as a novel nanostructured magnetic plastic, through a soft chemical processing route. In this work, CoPt nanoparticles were successfully synthesized from a solution phase reduction system in the presence of capping ligands and stabilizing agents at high temperature. The CoPt nanoparticles were annealed at 400 °C for 3 h, and were subsequently re-dispersed inmethylmethacrylate~monomer! . The polymerization was induced by a UV source and the hardness of final product was adjusted by varying the amount of monomeric cross-link agent. Annealed bare CoPt nanoparticles as a ‘‘core’’ material and CoPt–PMMA composite material were characterized by using energy dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction, indicating that we are able to prepare CoPt nanoparticles with 10 nm in diameter ~after annealing by employing this high temperature colloidal processing method. Magnetic investigation of this CoPt–PMMA material indicates an intrinsic coercivity of 300 Oe at 300 K and 1665 Oe at 5 K

Towards One Key to One Lock: Catalyst Modified Indium Oxide Nanoparticle Thin Film Sensor Array for Selective Gas Detection

Homogeneous In2O3 nanoparticles (NPs) were self-assembled into thin film sensor arrays on a single chip, with further surface modification by noble metal catalysts. The NP film sensor arrays show clear current responses when exposed to different target gases, and both sensitivity and selectivity were greatly improved. Particularly, the sensors modified with Au, Pd, and Pt nanocatalysts demonstrated higher sensitivity to H2S, H-2 and CO, respectively, making the gas discrimination direct and simple, like one key to one lock . The particle size dependence of the noble metal modifiers to the sensitivity was further investigated by tuning the sputtering parameters. Three different trends of sensitivities were observed, each attributed to different mechanisms. The modified nanoparticle film sensor was also fabricated on flexible substrates and the sensing performance was investigated at different bending angles

Towards One Key to One Lock: Catalyst Modified Indium Oxide Nanoparticle Thin Film Sensor Array for Selective Gas Detection

Homogeneous In2O3 nanoparticles (NPs) were self-assembled into thin film sensor arrays on a single chip, with further surface modification by noble metal catalysts. The NP film sensor arrays show clear current responses when exposed to different target gases, and both sensitivity and selectivity were greatly improved. Particularly, the sensors modified with Au, Pd, and Pt nanocatalysts demonstrated higher sensitivity to H2S, H-2 and CO, respectively, making the gas discrimination direct and simple, like one key to one lock . The particle size dependence of the noble metal modifiers to the sensitivity was further investigated by tuning the sputtering parameters. Three different trends of sensitivities were observed, each attributed to different mechanisms. The modified nanoparticle film sensor was also fabricated on flexible substrates and the sensing performance was investigated at different bending angles

Impact of safety-related dose reductions or discontinuations on sustained virologic response in HCV-infected patients: Results from the GUARD-C Cohort

BACKGROUND: Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. METHODS: A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the impact of sr-RD on SVR24 (HCV RNA <50 IU/mL) were conducted in 951 Caucasian, noncirrhotic genotype (G)1 patients assigned to peginterferon alfa-2a/ribavirin for 48 weeks. The probability of SVR24 was identified by a baseline scoring system (range: 0-9 points) on which scores of 5 to 9 and <5 represent high and low probability of SVR24, respectively. RESULTS: SVR24 rates were 46.1% (754/1634), 77.1% (279/362), 68.0% (514/756), and 51.3% (203/396), respectively, in G1, 2, 3, and 4 patients. Overall, 16.9% and 21.8% patients experienced 651 sr-RD for peginterferon alfa and ribavirin, respectively. Among Caucasian noncirrhotic G1 patients: female sex, lower body mass index, pre-existing cardiovascular/pulmonary disease, and low hematological indices were prognostic factors of sr-RD; SVR24 was lower in patients with 651 vs. no sr-RD by Week 4 (37.9% vs. 54.4%; P = 0.0046) and Week 12 (41.7% vs. 55.3%; P = 0.0016); sr-RD by Week 4/12 significantly reduced SVR24 in patients with scores <5 but not 655. CONCLUSIONS: In conclusion, sr-RD to peginterferon alfa-2a/ribavirin significantly impacts on SVR24 rates in treatment-naive G1 noncirrhotic Caucasian patients. Baseline characteristics can help select patients with a high probability of SVR24 and a low probability of sr-RD with peginterferon alfa-2a/ribavirin