Проблематика переходу до інформаційного суспільства

Аналізуються фундаментальні передумови, що є первинними в процесі творення інформаційного суспільства. Обґрунтовується теза, що електронна готовність та електронне залучення є основоположними факторами переходу суспільства від індустріального до інформаційного устрою. Подано основні характеристики цих понять та наголошено на їх значенні

Defining inclusion criteria and endpoints for clinical trials: a prospective cross-sectional study in CRB1-associated retinal dystrophies

Purpose: To investigate the retinal structure and function in patients with CRB1-associated retinal dystrophies (RD) and to explore potential clinical endpoints. Methods: In this prospective cross-sectional study, 22 patients with genetically confirmed CRB1-RD (aged 6–74 years), and who had a decimal best-corrected visual acuit

Clinical characterization of 66 patients with congenital retinal disease due to the deep-intronic c.2991+1655A>G mutation in CEP290

PURPOSE. To describe the phenotypic spectrum of retinal disease caused by the c.2991+1655A>G mutation in CEP290 and to compare disease severity between homozygous and compound heterozygous patients. METHODS. Medical records were reviewed for best-corrected visual acuity (BCVA), age of onset, fundoscopy descriptions. Foveal outer nuclear layer (ONL) and ellipsoid zone (EZ) presence was assessed using spectral-domain optical coherence tomography (SD-OCT). Differences between compound heterozygous and homozygous patients were analyzed based on visual performance and visual development. RESULTS. A total of 66 patients were included. The majority of patients had either light perception or no light perception. In the remaining group of 14 patients, median BCVA was 20/195 Snellen (0.99 LogMAR; range 0.12–1.90) for the right eye, and 20/148 Snellen (0.87 LogMAR; range 0.22–1.90) for the left. Homozygous patients tended to be more likely to develop light perception compared to more severely affected compound heterozygous patients (P = 0.080) and are more likely to improve from no light perception to light perception (P = 0.022) before the age of 6 years. OCT data were available in 12 patients, 11 of whom had retained foveal ONL and EZ integrity up to 48 years (median 23 years) of age. CONCLUSIONS. Homozygous patients seem less severely affected compared to their compound-heterozygous peers. Improvement of visual function may occur in the early years of life, suggesting a time window for therapeutic intervention up to the approximate age of 17 years. This period may be extended by an intact foveal ONL and EZ on OCT

The spectrum of structural and functional abnormalities in female carriers of pathogenic variants in the RPGR gene

PURPOSE. The purpose of this study was to investigate the phenotype and long-term clinical course of female carriers of RPGR mutations. METHODS. This was a retrospective cohort study of 125 heterozygous RPGR mutation carriers from 49 families. RESULTS. Eighty-three heterozygotes were from retinitis pigmentosa (RP) pedigrees, 37 were from cone-/cone-rod dystrophy (COD/CORD) pedigrees, and 5 heterozygotes were from pedigrees with mixed RP/CORD or unknown diagnosis. Mutations were located in exon 1-14 and in ORF15 in 42 of 125 (34%) and 83 of 125 (66%) subjects, respectively. The mean age at the first examination was 34.4 years (range, 2.1 to 86.0 years). The median follow-up time in heterozygotes with longitudinal data (n = 62) was 12.2 years (range, 1.1 to 52.2 years). Retinal pigmentary changes were present in 73 (58%) individuals. Visual symptoms were reported in 51 (40%) cases. Subjects with both symptoms and pigmentary fundus changes were older than the other heterozygotes (P = 0.01) and had thinner foveal outer retinas (P = 0.006). Complete expression of the RP or CORD phenotype was observed in 29 (23%) heterozygotes, although usually in milder forms than in affected male relatives. Best-corrected visual acuity (BCVA) was <20/40 and <20/400 in at least one eye in 45 of 116 (39%) and 11 of 116 (9%) heterozygotes, respectively. Myopia was observed in 74 of 101 (73%) subjects and was associated with lower BCVA (P = 0.006). Increasing age was associated with lower BCVA (P = 0.002) and decreasing visual field size (P = 0.012; I4e isopter). CONCLUSIONS. RPGR mutations lead to a phenotypic spectrum in female carriers, with myopia as a significantly aggravating factor. Complete disease expression is observed in some individuals, who may benefit from future (gene) therapeutic options

2p3d Resonant X-ray emission spectroscopy of cobalt compounds

This manuscript demonstrates that 2p3d resonant X-ray emission spectroscopy (RXES) yields unique information on the chemically relevant valence electrons of transition metal atoms or ions. Experimental data on cobalt compounds and several theories were used hand-in-hand. In chapter 1 2p3d RXES was situated within the scientific disciplines of chemistry, catalysis and spectroscopy. It was emphasized that the technique measures many-electron effects in great detail and that it allows investigating their role in the chemical bond. Prior to any RXES measurements, a novel, general organometallic route was developed in chapter 2 to obtain CoxNi1-x and CoxFe1-x alloy metal nanoparticles with a fully tunable composition and a size of 4 to 10 nm. A combined ultraviolet-visible (UV/Vis), 2p X-ray absorption spectroscopy (XAS) and 2p3d RXES study of 3d-orbitals in cobalt carboxylates was presented in chapter 3. Using cobalt(II) carboxylates, it was shown that 2p3d RXES reveals more and more intense d-d excitations than UV/Vis spectroscopy and that 2p XAS cannot discriminate the compounds. Ligand field multiplet (LFM) theory was applied to explain why the technique is highly sensitivity to the metal ion ligand field. In chapter 4 a total experimental 2p3d RXES resolution better than 100 meV full-width-at-half-maximum was exploited to investigate CoO nanocrystals with an average diameter of 4.2 nm and a CoO single crystal. The RXES data allowed the first X-ray observation of the CoO 4T1g(4F) manifold that occurs within the first 120 meV above the ground state. LFM modeling was performed to assess the tetragonal crystal field splitting, spin-orbit and superexchange parameters. Chapter 5 reports 2p3d RXES measurements on 8.4 and 5.0 nm cobalt and 3.6 nm cobalt-nickel nanoparticles coated with oleate molecules that exhibit low energy resonant Raman features at 0.3 and 0.75 eV. In combination with time-dependent density functional theory (TD-DFT) and LFM calculations these are ascribed to d-d excitations of cobalt ions in two different, but both possible, chemical environments. A consequence of the first discussed model would be that 2p3d RXES is a unique tool for the selective identification of surface metal-adsorbate interactions. In chapter 6 both 2p XAS and 2p3d RXES spectra of cobalt nanoparticle batches with average diameters of 4.0, 4.2, 5.0, 8.4 and 15.2 nm are reported. Most 2p XAS data cannot conclusively distinguish whether the nanoparticles are oxidized or metallic. In contrast, the high-energy resolution 2p3d RXES spectra clearly reveal particle oxidation. Chapters 7a, 7b and 8 are not dealing with RXES measurements, but use XAS and electron energy loss spectroscopy (EELS) in combination with scanning transmission microscopes to demonstrate synergetic possibilities resulting from X-ray and electron spectromicroscopes. Two dimensional and tomographic scanning transmission X-ray microscopy (STXM) is shown to be an attractive and complementary imaging tool to probe the interior of colloidal, photonic crystals. High angle annular dark field scanning transmission electron microscopy (STEM) combined with EELS is used to directly visualize and quantify the organic and inorganic components of lipid-coated silica nanoparticles that contain smaller semiconductor quantum dots; particles that are of interest as multimodal medical contrast agent

Formation of nematic liquid crystals of sterically stabilized layered double hydroxide platelets

Colloidal platelets of hydrotalcite, a layered double hydroxide, have been prepared by coprecipitation at pH 11−12 of magnesium nitrate and aluminum nitrate at two different magnesium to aluminum ratios. Changing the temperature and ionic strength during hydrothermal treatment, the platelets were tailored to different sizes and aspect ratios. Amino-modified polyisobutylene molecules were grafted onto the platelets following a convenient new route involving freeze-drying. Organic dispersions in toluene were prepared of the particles with the largest size and highest aspect ratio. The colloidal dispersions prepared in this way showed isotropic−nematic phase transitions above a limiting concentration in a matter of days. The number density at the transition and the width of the biphasic region were determined and compared to theory. The orientation of the platelets in nematic droplets (tactoids) and at the isotropic−nematic interface were analyzed by polarization microscopy. It was observed that sedimentation induces a nematic layer in samples that are below the limiting concentration for isotropic−nematic phase separation. No nematic phase was observed in the initial aqueous suspensions of the ungrafted particles

Lipid-coated silica nanoparticles for biomedical applications

Silica particles as a nanoparticulate carrier material for contrast agents have received considerable attention the past few years, since the material holds great promise for biomedical applications. A key feature for successful application of this material in vivo is biocompatibility, which may be significantly improved by appropriate surface modification. In this study we report a novel strategy to coat silica particles with a dense monolayer of paramagnetic and PEGylated lipids. The silica nanoparticles carry a quantum dot in their centre and are made target-specific by the conjugation of multiple (alpha)v(beta)3-specifc RGD-peptides. We demonstrate their specific uptake by endothelial cells in vitro using fluorescence microscopy, quantitative fluorescence imaging and magnetic resonance imaging. The lipid coated silica particles introduced here represent a new platform for nanoparticulate multimodality contrast agents

Structure, stability, and formation pathways of colloidal gels in systems with short-range attraction and long-range repulsion

We study colloidal gels formed upon centrifugation of dilute suspensions of spherical colloids (radius 446 nm) that interact through a long-range electrostatic repulsion (Debye length ≈ 850 nm) and a short-range depletion attraction (∼12.5 nm), by means of confocal scanning laser microscopy (CSLM). In these systems, at low colloid densities, colloidal clusters are stable. Upon increasing the density by centrifugation, at different stages of cluster formation, we show that colloidal gels are formed that significantly differ in structure. While significant single-particle displacements do not occur on the hour time scale, the different gels slowly evolve within several weeks to a similar structure that is at least stable for over a year. Furthermore, while reference systems without long-range repulsion collapse into dense glassy states, the repulsive colloidal gels are able to support external stress in the form of a centrifugal field of at least 9g

Oxygen Binding to Cobalt and Iron Phthalocyanines As Determined from in Situ X ray Absorption Spectroscopy

Cobalt phthalocyanine (CoPc) and iron phthalocyanine (FePc) are possible oxygen reduction catalysts in fuel cells, but the exact functioning and deactivation of these catalysts is unknown. The electronic structure of the CoPc and FePc has been studied in situ under hydrogen and oxygen atmospheres by a combination of ambient-pressure X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The results show that when oxygen is introduced, the iron changes oxidation state while the cobalt does not. The data show that oxygen binds in an end-on configuration in CoPc, while for FePc side-on binding is most likely