Dynamics of pH Oscillators in Continuous Stirred Tanks in Series.

Complex reaction networks with positive and negative feedback can produce diverse nonlinear phenomena in open reactors, such as multistability and oscillations. pH oscillators driven by hydrogen or hydroxide autocatalytic processes show sustained oscillations in continuously stirred tank reactors (CSTR) but only a sharp pH switch in batch. Here, we present a numerical study on the dynamics of pH oscillators in a series of CSTRs.

Radical chain mechanism for the SO -SO -Cu(ii) flow system explains high-amplitude pH oscillations in the NHOH-modified version.

Peroxodisulfate is well known as an important reagent in analytical, environmental and other branches of chemistry, as well as in industrial processes. One of the most studied oxidative reactions peroxodisulfate participates in as an oxidizer is the Cu(ii)-catalyzed peroxodisulfate-thiosulfate reaction. When carried out in a flow reactor, this system shows oscillatory dynamics characterized by periodic changes in the Pt-potential and [O] while it only displays variation in the pH with a few tenths of unit magnitude.

Presentation of Meibomian Acini Compared to Dermal Papillae of the Eyelid Margin, Using Confocal Laser Scanning Microscopy and Corresponding Histology.

Background: Numerous studies have investigated the eyelid margin using confocal laser scanning microscopy (CLSM) and have presented morphological alterations of the examined structures, which were presumed to be Meibomian acini. However, recent data confirm that these structures are the cross-sections of dermal papillae of the dermoepidermal junction. This study aims to present the morphological appearance of Meibomian acini examined by confocal laser scanning microscopy in comparison to dermal papillae, and to reveal the corresponding patterns with specific histological sections.

Structuring liquids through solvent-assisted interfacial association of oppositely charged polyelectrolytes and amphiphiles.

Hypothesis: Sculpting liquids into different shapes is usually based on the interfacial interactions of functionalized nanoparticles or polymers with specific ligands, leading to exciting material properties due to the combination of the mobility of liquid components with the solid-like characteristic of the arrested liquid/liquid interface. There is an intense interest in novel structured liquids produced from simple compounds with versatile application potentials. Complexes of oppositely charged commercial polyelectrolytes and traditional aliphatic surfactants are good candidates for this goal since they reveal rich structural features and could adsorb at various interfaces.

Autocatalytic flow chemistry.

Autocatalysis is a crucial process of nonequilibrium self-organization in nature and is assumed to play a role in the origin of life. The essential dynamical phenomena of an autocatalytic reaction network are bistability and the development of propagating front when combined with diffusion. The presence of bulk fluid motion may widen the range of emerging behavior in those systems.

Appearance and suppression of Turing patterns under a periodically forced feed.

Turing instability is a general and straightforward mechanism of pattern formation in reaction-diffusion systems, and its relevance has been demonstrated in different biological phenomena. Still, there are many open questions, especially on the robustness of the Turing mechanism. Robust patterns must survive some variation in the environmental conditions.

The Assessment of Acute Chorioretinal Changes Due to Intensive Physical Exercise in Senior Elite Athletes.

Regular physical exercise is known to lower the incidence of age-related eye diseases. We aimed to assess the acute chorioretinal alterations in older adults following intense physical strain. Seventeen senior elite athletes were recruited who underwent an aerobic exercise on a cycle ergometer and macular scanning by optical coherence tomography.

Application and comparison of thermistors and fiber optic temperature sensor reference for ILP measurement of magnetic fluids in double cell magnetic hyperthermia.

One of the simplest way to characterize the heating efficiency of magnetic fluids used in hyperthermia treatment is the calorimetric measurement of the specific loss power with direct temperature detection. However, the performance of metallic sensors in an alternating magnetic field is degraded by the self-heating of the probes, and electromagnetic interference can be also significant. In our double cell differential thermometric system these disturbing effects can be compensated.

The assessment of acute chorioretinal changes due to intensive physical exercise in young adults.

Purpose: There is abundant evidence on the benefits of physical activity on cardiovascular health. However, there are only few data on the acute effects of physical exercise on the retina and choroid. Our aim was the in vivo examination of chorioretinal alterations following short intense physical activity by spectral domain optical coherence tomography (SD-OCT).

Synthesis of zeolitic imidazolate framework-8 and gold nanoparticles in a sustained out-of-equilibrium state.

The design and synthesis of crystalline materials are challenging due to the proper control over the size and polydispersity of the samples, which determine their physical and chemical properties and thus applicability. Metal - organic frameworks (MOFs) are promising materials in many applications due to their unique structure. MOFs have been predominantly synthesized by bulk methods, where the concentration of the reagents gradually decreased, which affected the further nucleation and crystal growth.

Reaction-diffusion phenomena in antagonistic bipolar diffusion fields.

Operating natural or artificial chemical systems requires nonequilibrium conditions under which temporal and spatial control of the process is realizable. Open reaction-diffusion systems provide a general way to create such conditions. A key issue is the proper design of reactors in which the nonequilibrium conditions can be maintained.

Reaction-Diffusion Dynamics of pH Oscillators in Oscillatory Forced Open Spatial Reactors.

Studying the effect of coupling and forcing of oscillators is a significant area of interest within nonlinear dynamics and has provided evidence of many interesting phenomena, such as synchronization, beating, oscillatory death, and phase resetting. Many studies have also reported along this line in reaction-diffusion systems, which are preferably explored experimentally by using open reactors. These reactors consist of one or two homogeneous (well-stirred) tanks, which provide the boundary conditions for a spatially distributed part.

Factors influencing haze formation and corneal flattening, and the impact of haze on visual acuity after conventional collagen cross-linking: a 12-month retrospective study.

Background: Our aim was to determine associations of pachymetry, keratometry, and their changes with haze formation and corneal flattening after collagen cross-linking, and to analyse the relationship between postoperative haze and visual outcome.

Methods: Retrospective analysis was performed on 47 eyes of 47 patients with keratoconus using the Pentacam HR Scheimpflug camera before and 1, 3, 6 and 12 months after cross-linking. Corneal backscattered light values in grey scale unit were recorded in the anterior, center and posterior corneal layers and in four concentric rings.

Induced permittivity increment of electrorheological fluids in an applied electric field in association with chain formation: A Brownian dynamics simulation study.

We report Brownian dynamics simulation results for the relative permittivity of electrorheological (ER) fluids in an applied electric field. The relative permittivity of an ER fluid can be calculated from the Clausius-Mosotti (CM) equation in the small applied field limit. When a strong field is applied, however, the ER spheres are organized into chains and assemblies of chains in which case the ER spheres are polarized not only by the external field but by each other.

The Predictive Role of Thyroid Hormone Levels for Early Diabetic Retinal Changes in Experimental Rat and Human Diabetes.

Purpose: In diabetic subjects, early visual functional alterations such as color vision deficiencies (CVDs) are known to precede clinically apparent diabetic retinopathy. Prominent photoreceptor outer segment degeneration and an increase in the number of retinal dual cones (co-expressing S- and M-opsins simultaneously) have been described in diabetic rat models, suggesting a connection with the development of CVDs. As cone opsin expression is controlled by thyroid hormones, we investigated the diabetic retina in association with thyroid hormone alterations.

[Congenital ptosis repair using posterior approach levator plication].

Unlabelled: Összefoglaló. Bevezetés: Szemhéjcsüngésnek (ptosis vagy blepharoptosis) nevezzük azt az állapotot, amikor a felső szemhéj abnormálisan alacsony pozícióban van. A szemhéjcsüngésnek lehetnek veleszületett és szerzett formái.

[Meibomian gland dysfunction and dry eye: Diagnosis and treatment].

Összefoglaló. A szárazszem-panaszok hátterében gyakran áll Meibom-mirigy-diszfunkció, melynek felismerése kiemelten fontos a hatékony kezelés érdekében. A Meibom-mirigyek kóros működése miatt a termelt lipid nem oszlik el megfelelően a szemfelszínen, így a könnyfilm párolgása fokozódik.

[Monocanalicular silicone stent implantation in children with congenital nasolacrimal duct obstruction].

Unlabelled: Összefoglaló. Bevezetés: Csecsemőkorban a könnyezés gyakori oka a könnycsatorna veleszületett elzáródása, mely az esetek nagy részében 1 éves korra spontán oldódik. Célkitűzés: Retrospektív tanulmányunk célja a monocanalicularis szilikonsztent (Masterka®) implantációjával kapcsolatos eredményeink bemutatása.

Chemical Oscillations With Sodium Perborate as Oxidant.

The peroxo compounds HO and KSO represent one of the major constituents in many oscillatory chemical systems. In this contribution we demonstrate that beside HO and S the sodium perborate (NaBO·HO) can act as alternative oxidizing agent in oscillatory reactions. So far the HO has been successfully substituted with NaBO in two oscillators: in the BO -S -Cu(II) flow system potential and pH oscillations, in the strongly alkaline Cu(II)-catalyzed BO -SCN batch reaction, which are rather different in their chemistry and dynamics, potential oscillations were observed.

A simple hydrogel device with flow-through channels to maintain dissipative non-equilibrium phenomena.

The development of autonomous chemical systems that could imitate the properties of living matter, is a challenging problem at the meeting point of materials science and nonequilibrium chemistry. Here we design a multi-channel gel reactor in which out-of-equilibrium conditions are maintained by antagonistic chemical gradients. Our device is a rectangular hydrogel with two or more channels for the flows of separated reactants, which diffuse into the gel to react.

Cataract blindness in Hungary.

Aim: To estimate the prevalence of blindness and visual impairment resulting from cataract in the population aged ≥50y in Hungary, and to assess the cataract surgical services.

Methods: A rapid assessment of avoidable blindness (RAAB) was conducted. A total of 3523 eligible people were randomly selected and examined.

The Effect of Physical Exercise on the Retina and Choroid.

There is only limited information available on the effects of physical exercise on the posterior pole. Retinal circulation is autoregulated similarly to the brain vasculature in order to provide constant flow and thus constant nutrition of the inner retinal structures while the choroid is mostly controlled by the sympathetic nervous system. The available data show that physical exercise may indeed have a positive effect on the retina and visual function.

Turing Patterns and Waves in Closed Two-Layer Gel Reactors.

Reaction-diffusion waves and stationary Turing patterns are observed in closed two-layer gel reactors, where the two compartments are initially filled with complementary sets of reactants of the chlorine dioxide-iodine-malonic acid-poly(vinyl alcohol) reaction. The asymmetrical loading generates concentration gradients and the patterns form at the interface between the two parts. These easy-to-perform experiments allow us to study a wide range of dynamical phenomena without requiring a specific reactor design or the use of sophisticated equipment.

Magnetic field response of aqueous hydroxyapatite based magnetic suspensions.

During the biomedical and biotechnological applications of hydroxyapatite based magnetic biomaterials the response to various magnetic fields (i.e. change in flow behavior) plays a pivotal role in manipulating these materials.

Design of localized spatiotemporal pH patterns by means of antagonistic chemical gradients.

Spatially localized moving and stationary pH patterns are generated in two-side-fed reaction-diffusion systems. The patterns are sandwiched between two quiescent zones and positioned by the antagonistic gradients of the reactants of the self-activatory process. Spatial bistability, spatiotemporal oscillations, and formation of stationary Turing patterns have been predicted by numerical simulations and observed in experiments performed by using different hydrogen ion autocatalytic chemical systems.