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. METHODS AND MATERIAL: Twenty healthy patients were examined with a CLSM device in vivo at the marginal edge of the eyelid. Twenty-two samples of full-thickness eyelid wedges from 22 patients treated surgically with ectropion were collected, of which 11 freshly excised samples were imaged on the incision surface with CLSM ex vivo and 11 eyelids underwent conventional histological preparation. The represented structures on CLSM images were compared to Meibomian acini on histological sections in terms of area, longest and shortest diameter, as well as depth and density. RESULTS: On in vivo CLSM images, Meibomian orifices, epidermal cells, and dermal connective tissue could be identified, the latter in a cross-sectional view of the dermal papillae surrounded by basal cells of the epidermis, forming reflective ring-like structures. All morphological parameters of these structures differed from Meibomian acini measured on histological sections. In contrast, the CLSM images of the incision surface showed acinar units with the same morphology as the Meibomian acini seen in the histological images and no statistically significant difference was found between the corresponding parameters. CONCLUSION: The morphological appearance of Meibomian acini differs from the structures that were previously presumed as Meibomian glands on CLSM images. In vivo imaging of Meibomian glands by commonly used in vivo CLSM cannot be performed.

Dynamic dielectric response of electrorheological fluids in drag flow.

We have determined the response time of dilute electrorheological fluids (ER) in drag flow from the dynamic dielectric response. On the basis of a kinetic rate equation a new formula was derived to approximate the experimental time-dependent dielectric permittivity during the temporal evolution of the microstructure. The dielectric response time was compared to the standard rheological response time extracted from the time-dependent shear stress, and a good agreement was obtained. We found that the dielectric method is more sensitive to detect any transient during the chain formation process. The experimental saturation value of the dielectric permittivity corresponding to the equilibrium microstructure was estimated on the basis of formulas derived from the Clausius-Mossotti equation.

Linear and nonlinear magnetic properties of ferrofluids.

Within a high-magnetic-field approximation, employing Ruelle's algebraic perturbation theory, a field-dependent free-energy expression is proposed which allows one to determine the magnetic properties of ferrofluids modeled as dipolar hard-sphere systems. We compare the ensuing magnetization curves, following from this free energy, with those obtained by Ivanov and Kuznetsova [Phys. Rev. E 64, 041405 (2001)] as well as with new corresponding Monte Carlo simulation data. Based on the power-series expansion of the magnetization, a closed expression for the magnetization is also proposed, which is a high-density extension of the corresponding equation of Ivanov and Kuznetsova. From both magnetization equations the zero-field susceptibility expression due to Tani et al. [Mol. Phys. 48, 863 (1983)] can be obtained, which is in good agreement with our MC simulation results. From the closed expression for the magnetization the second-order nonlinear magnetic susceptibility is also derived, which shows fair agreement with the corresponding MC simulation data.

Comparison between theory and simulations for the magnetization and the susceptibility of polydisperse ferrofluids.

The influence of polydispersity on the magnetization of ferrofluids is studied based on a previously published magnetization equation of state (Szalai and Dietrich, 2011 J. Phys.: Condens. Matter 23 326004) and computer simulations. The polydispersity of the particle diameter is described by the gamma distribution function. Canonical ensemble Monte Carlo simulations have been performed in order to test these theoretical results for the initial susceptibility and the magnetization. The results for the magnetic properties of the polydisperse systems turn out to be in quantitative agreement with our present simulation data. In addition, we find good agreement between our theory and experimental data for magnetite-based ferrofluids.

An analytic solution for the magnetization of two-dimensional ferrofluids based on the mean spherical approximation.

An analytic formula is derived for the magnetization of a two-dimensional dipolar hard disk fluid using a variational functional series expansion of the free energy as a function of the orientational distribution function. The excess term expressing the effect of the intermolecular forces is calculated on the basis of the mean spherical approximation. Comparison with our own Monte Carlo simulation data shows excellent agreement for large external fields and for the zero-field susceptibility. At intermediate field strengths, the agreement is satisfactory for moderate dipole moments and densities.

Structure of electrorheological fluids: a dielectric study of chain formation.

A dielectric measurement method has been proposed to apply to the study of the microstructure of electrorheological (ER) fluids. To test our measurement method the dielectric permittivity increment caused by pair and chain formation was measured in dilute Brownian ER fluids composed of silicone oil and nanosized silica particles. The critical values of the electric field required to induce structure formation were experimentally determined from the electric field dependence of the measured permittivity increment. From the electric field induced time evolution of the relative permittivity of ER fluids, the characteristic times of the pair and chain formation were calculated. Our experimental results for the time constants are in good agreement with the corresponding theoretical data obtained from the Eyring theory.

Magnetization of multicomponent ferrofluids.

The solution of the mean spherical approximation (MSA) integral equation for isotropic multicomponent dipolar hard sphere fluids without external fields is used to construct a density functional theory (DFT), which includes external fields, in order to obtain an analytical expression for the external field dependence of the magnetization of ferrofluidic mixtures. This DFT is based on a second-order Taylor series expansion of the free energy density functional of the anisotropic system around the corresponding isotropic MSA reference system. The ensuing results for the magnetic properties are in quantitative agreement with our canonical ensemble Monte Carlo simulation data presented here.

Phase transitions and ordering of confined dipolar fluids.

We apply a modified mean-field density functional theory to determine the phase behavior of Stockmayer fluids in slit-like pores formed by two walls with identical substrate potentials. Based on the Carnahan-Starling equation of state, a fundamental-measure theory is employed to incorporate the effects of short-ranged hard-sphere-like correlations while the long-ranged contributions to the fluid interaction potential are treated perturbatively. The liquid-vapor, ferromagnetic-liquid-vapor, and ferromagnetic-liquid-isotropic-liquid first-order phase separations are investigated. The local orientational structure of the anisotropic and inhomogeneous ferromagnetic liquid phase is also studied. We discuss how the phase diagrams are shifted and distorted upon varying the pore width.

Nonlinear dielectric effect of dipolar fluids.

The nonlinear dielectric effect for dipolar fluids is studied within the framework of the mean spherical approximation (MSA) of hard core dipolar Yukawa fluids. Based on earlier results for the electric field dependence of the polarization our analytical results show so-called normal saturation effects, which are in good agreement with corresponding NVT ensemble Monte Carlo (MC) simulation data. The linear and the nonlinear dielectric permittivities obtained from MC simulations are determined from the fluctuations of the total dipole moment of the system in the absence of an applied electric field. We compare the MSA based theoretical results with the corresponding Langevin and Debye-Weiss behaviors and with actual experimental data.

Heat capacities of dipolar fluids: ferromagnetic colloids.

The heat capacities of ferrofluids are investigated using a thermodynamic perturbation theory approach and the NVT and NpT Monte Carlo simulation methods. The systems studied are considered as one-, three-, and five-component dipolar mixtures modeled by the Stockmayer interaction potential. The isochoric and isobaric heat capacities are calculated and compared with the data determined for a monodisperse equivalent of the system.

Magnetization of two-dimensional magnetic fluids.

The influence of polydispersity on the magnetization of two-dimensional dipolar discs with short-range repulsive interaction is studied by means of Monte Carlo simulations and a high field approximation perturbation theory. Within the framework of perturbation theory an analytical expression is derived for the magnetization of monodisperse and polydisperse systems. The theoretical predictions are in good agreement with the corresponding Monte Carlo simulation data.

Magnetization and susceptibility of ferrofluids.

A second-order Taylor series expansion of the free energy functional provides analytical expressions for the magnetic field dependence of the free energy and of the magnetization of ferrofluids, here modeled by dipolar Yukawa interaction potentials. The corresponding hard core dipolar Yukawa reference fluid is studied within the framework of the mean spherical approximation. Our findings for the magnetic and phase equilibrium properties are in quantitative agreement with previously published and new Monte Carlo simulation data.

Spatial bistability: a source of complex dynamics. From spatiotemporal reaction-diffusion patterns to chemomechanical structures.

We show experimentally and theoretically that reaction systems characterized by a slow induction period followed by a fast evolution to equilibrium can readily generate "spatial bistability" when operated in thin gel reactors diffusively fed from one side. This phenomenon which corresponds to the coexistence of two different stable steady states, not breaking the symmetry of the boundary conditions, can be at the origin of diverse reaction-diffusion instabilities. Using different chemical reactions, we show how stationary pulses, labyrinthine patterns or spatiotemporal oscillations can be generated. Beyond simple reaction-diffusion instabilities, we also demonstrate that the cross coupling of spatial bistability with the size responsiveness of a chemosensitive gel can give rise to autonomous spatiotemporal shape patterns, referred to as chemomechanical structures.

Comment on "Algebraic perturbation theory for polar fluids: A model for the dielectric constant"

Kalikmanov [Phys. Rev. E 59, 4085 (1999)] proposed a perturbation theory method to calculate the dielectric constant of dipolar hard sphere fluids using an infinitely long cylindrical container to avoid the depolarization. We demonstrate that while the method is very helpful, his theory appears to be incomplete because of the incorrect calculation of the corresponding three-body integrals. It is shown that with the correct consideration of these terms the theory is consistent with the results of earlier work in low-density limit, and at high densities the method yields the equation of Tani et al. [Mol. Phys. 48, 863 (1983)] for the dipolar hard sphere fluid dielectric constant.

[Use of polyurethane foil for wound covering]. / Poliuretán fólia használata sebfedésre.

The authors account of the application of the Omiderm folie in connection with 29 cases. The transparent polyurethan skin substitute was used in dermatological diseases when presenting extensive shortage of tissue or for covering the half-thick skin's donor areas and for the treatment of deep second degree burns. The advantages of the application of the wound covering folie is being valued and the authors are calling attention to the most common complications being noticed during the application. The Omiderm is being judged as a suitable alternative bandage and skin substitute.

[Reverse ulnar artery flap in the repair of an electric burn injury]. / Fordított a. ulnaris szigetlebeny alkalmazása elektromos égés esetén.

Authors used to cover the defect of the wrist region in consequence of electric burn reverse ulnar artery island flap with success. The method described was used in one case and it is suggested in similar circumstances.

[Significance of the comparison between clinical and pathological diagnosis in health care quality control]. / A klinikai és kórbonctani diagnózisok összevetésének jelentösége az egészségügyi munka minöségének ellenörzésében.

Authors studied concordance of clinical and pathological diagnosis and significance of history taking, of physical, radiological, laboratory and morphological examinations and of their evaluation in development of diagnostic differences in 4041 autopsy cases, with international methods. Possibilities of use of method in clinico-pathological work are presented.

Experiences in the Ebrimycin gel treatment of burns.

Ebrimycin gel has been used for the local treatment of burns of 50 partly hospitalized patients, partly outpatients. According to the observations the product may be successfully used by the exposure method for the treatment of superficial facial burns and by the occlusive dressing method for the treatment of small burns which are infected by Gram-positive bacteria.