Ocular hypertension in patients with central/hemicentral retinal vein occlusions: cumulative prevalence and management

AIM: To prospectively evaluate the cumulative prevalence and the management of ocular hypertension (OH) in patients with unilateral acute central/hemicentral retinal vein occlusions (C/HCRVOs) over the course of 3y. METHODS: The study included 57 patients with unilateral acute C/HCRVOs. All patients underwent a comprehensive ophthalmological examination of both eyes. OH associated with C/HCRVO in patients showing a score >5% for the risk of conversion to primary open angle glaucoma (POAG) was treated with OH medication. The treatment aimed for a decrease in intraocular pressure (IOP) to 22% reduction from the initial values. The cumulative prevalence of OH and the effectiveness of treatment assessed by the cumulative prevalence of conversion from OH to POAG, were estimated. RESULTS: Fifteen patients had OH associated with C/HCRVOs, the cumulative prevalence of OH was 29.4% (95% confidence interval, 16.9-41.9). The mean value of the risk score of OH conversion to POAG for the 5 subsequent years was 11.7%±5.4%. The IOP significantly decreased from 25.67±2.16 mm Hg to 18.73±2.96 mm Hg. None of the OH patients converted to POAG during the follow-up period. CONCLUSION: The increased cumulative prevalence of OH in C/HCRVO patients indicates that OH is a risk factor for the appearance of venous occlusion. Patients with OH associated with C/HCRVO must be considered to be at high risk for conversion to POAG. Treatment with OH medications prevented conversion to POAG during the 3-year follow-up

3_D surface stereometry of Ag/DLC nanocomposite prepared by RF-PECVD

In this study, a stereometric analysis of the three-dimensional (3-D) surfaces of the Ag/diamond-like carbon (DLC) nanocomposite films was done. The nanocomposite thin films were fabricated by Radio Frequency Plasma-Enhanced Chemical Vapour Deposition (RF-PECVD). The 3-D surface microtexture was studied by high-resolution Atomic Force Microscopy (AFM) records combined with statistical analyses. More detailed information about surface statistical parameters and topographic features of analyzed samples were performed. The statistical parameters relating to the segmented motifs consistent with ISO 25178-2: 2012 have been generated using MountainsMap® Premium software. The analysis was performed by modeling Ag/DLC nanocomposite surface microtexture based on motif analysis (detection of essential characteristics in terms of surface dimensions, volume, curvature, shape) to be included in computer interactive simulation algorithms

Multifractal characterization of epitaxial silicon carbide on silicon

The purpose of this study was to investigate the topography of silicon carbide films at two steps of growth. The topography was measured by atomic force microscopy. The data were processed for extraction of information about surface condition and changes in topography during the films growth. Multifractal geometry was used to characterize three-dimensional micro- and nano-size features of the surface. X-ray measurements and Raman spectroscopy were performed for analysis of the films composition. Two steps of morphology evolution during the growth were analyzed by multifractal analysis. The results contribute to the fabrication of silicon carbide large area substrates for micro- and nanoelectronic applications

Evaluation of Topographical Co-Cr-Mo Alloy Surface Changes After Various Finishing Treatments

Svrha: Kvantificiran je utjecaj triju različitih postupaka završne obrade površine kobalt-krom-molibdenovom (Co-Cr-Mo) legurom s pomoću parametara stereometrijske analize. Materijal i metode: Izliveno je 18 uzoraka ekstra tvrde legure (Wironit®, BEGO, Bremen, Njemačka). Uzorci su podijeljeni u tri skupine (n = 6 uzoraka u svakoj), ovisno o primijenjenoj tehnici poliranja i to kako slijedi: A skupina – samo elektropolirani uzorci (EP); B skupina – nakon EP-a površina je dodatno mehanički polirana gumenim diskovima, pastom za poliranje i rotirajućom četkom (RP); C skupina – nakon EP-a, završno mehaničko poliranje obavljeno je gumenim diskovima, pastom za poliranje i rotirajućim kolutom od jelenje kože (RPDL). Svi uzorci analizirani su mikroskopom atomskih sila (AFM-om) u kontaktnom načinu rada, na zraku i pri sobnoj temperaturi. Rezultati: Procjena mikroteksture površine uzoraka učinjena s pomoću 3D parametara za procjenu hrapavosti. Najniži parametri površine nađeni su u RP skupini, a najviši u EP skupini. Zaključci: Opisani eksperimenti mogu koristiti proizvođačima da identificiraju najpovoljnije parametre i njihove raspone za postizanje optimalnih svojstava površine.Purpose: To quantify the influence of three different finishing treatments on the cobalt-chromiummolybdenum (Co-Cr-Mo) alloy surface based on stereometric analysis parameters. Materials and methods: Eighteen specimens were casted from an extra-hard alloy (Wironit®, BEGO, Bremen, Germany). The samples were distributed into three groups (n = 6 samples per group) dependent on different polishing techniques applied, as follows: A group, only electropolished (EP) samples; B group, after EP, an additional mechanical polishing process was applied to the surface by rubber discs and a polishing paste (RP); C group, after EP, an additional mechanical polishing process was completed by rubber discs, polishing paste and finally by a rotating deer leather wheel (RPDL). Samples were imaged by atomic force microscopy (AFM) in a contact mode, in air, at room temperature. Results: The evaluation of the microtexture of the sample surface was made based on the 3-D roughness parameters. The lowest statistical surface roughness parameters were found in the RP samples, whereas the highest values were obtained from the EP samples. Conclusions: The experiments described can help manufacturers identify the most appropriate parameters and their ranges within which optimal surface characteristics can be achieved

Preparation of PVDF-CNT composite

Limitations of ceramic piezomaterials (brittleness, toxicity of lead-containing samples, difficulties of complicated shapes preparations, etc.) call for the research in the field of piezoelectric polymers. One of them is polyvinylidene fluoride (PVDF). It could be prepared in various forms: thin films, bulk samples, fibers. PVDF fibers attract the most attention because of high flexibility, lightweight, mechanical stability, chemical inertness. Properties of PVDF fibers can be tuned using dopant material: ceramic particles, metal nanoparticles, graphite materials as graphene oxide or carbon nanotubes (CNT)

Surface morphology and X-ray photoelectron spectroscopy of BiFeO3 thin films deposited on top of Ta2O5/Si layers

In this study a comparison of the topography of BiFeO3 (BFO) thin films deposited on tantalum pentoxide substrates of different thicknesses is provided. The Ta2O5 substrates had a roughness increasing with the film thickness. The relationship between substrates of different topography but the same composition with the quality of the growing bismuth ferrite film is estimated. For the first time the topography estimation of BFO on Ta2O5 is presented. The difference in temperature expansion coefficients leads to intensive evaporation of bismuth ferrite from the surface during annealing. XPS analysis is provided for asdeposited and annealed BFO layers

A brief introduction and current state of polyvinylidene fluoride as an energy harvester

This review summarizes the current trends and developments in the field of polyvinylidene fluoride (PVDF) for use mainly as a nanogenerator. The text covers PVDF from the first steps of solution mixing, through production, to material utilization, demonstration of results, and future perspective. Specific solvents and ratios must be selected when choosing and mixing the solution. It is necessary to set exact parameters during the fabrication and define whether the material will be flexible nanofibers or a solid layer. Based on these selections, the subsequent use of PVDF and its piezoelectric properties are determined. The most common degradation phenomena and how PVDF behaves are described in the paper. This review is therefore intended to provide a basic overview not only for those who plan to start producing PVDF as energy nanogenerators, active filters, or sensors but also for those who are already knowledgeable in the production of this material and want to expand their existing expertise and current overview of the subject

Crack resistance of bismuth ferrite films obtained on a flexible substrate

Ultrathin BiOx and FeOx layers were obtained by Atomic Layer Deposition (ALD) on the surface of a flexible Kapton substrate (poly (4,4’-oxydiphenylene-pyromellitimide)) at a temperature of 250 °C. The layer thickness was 50 - 100 nm. Surface morphology, electrical polarization, and mechanical properties were investigated by Atomic Force Microscope, Piezoelectric Force Microscopy and Force Modulation Microscopy. Chemical analysis was performed by X-ray Photoelectron Spectroscopy, where the formation of Bi2O3 and Fe2O3 phases, as well as intermediate phases in the Bi-Fe-O system, was observed. With a small increase in the Bi content of the film, the BFO / Kapton structure becomes more crack resistant. Modification of the Kapton surface with bismuth and iron oxides showed that such a composition exhibits multiferroic behavior