Layer In Absence Research Articles

Linear and whorled nevoid hypermelanosis.

Linear and whorled nevoid hypermelanosis is a congenital disorder mostly sporadic and rarely associated with mosaic trisomy of 7, 14, 18, 20 and X chromosome (1). It presents as widespread streaky hyperpigmented macules along Blaschko’s lines mostly on the trunk and limbs and do not cross the midline. The usual onset is within first few weeks of life with progression during the initial years of life. However, the pigmentation can gradually fade with time. Few cases are associated with developmental and growth delay, facial and body asymmetry, ventricular septal defects (2) and pseudohermaphroditism (1).The diagnosis is confirmed by histopathology which reveals increased pigmentation of the basal layer in absence of pigment incontinence.

Distribution of solid-phase reduction of iron in a layer of ilmenite concentrate

Processing of titanium-containing ores with extraction of all the major elements is an urgent task of minerals rational use. It is shown that none of the existing processing schemes allows extracting of all the major useful elements at the same time from titanium-containing iron ores, i.e. – iron, titanium and vanadium. This problem can be solved using selective extraction of these elements based on new ideas about electronic reduction mechanism. Propagation of the process of solid-phase selective reduction of iron with the powder of carbon-containing material deep into the layer of grains of ilmenite concentrate from the surface of its contact was experimentally studied. The results of determining the amount of metal phase released as it moves away from the concentrate – reducing agent contact boundary are presented. Based on the results concerning amount of precipitated metal phase, a conclusion was made about diffusion processes in a layer of concentrate grains contacting only between themselves, limiting process of iron reduction. It is shown that near the plane of contact of solid reducing agent with the layer of concentrate grains, the rate of iron reduction is higher than the rate of high iron content phase precipitation from ilmenite. In depth of ilmenite concentrate layer, process of iron reduction is preceded by formation of iron-containing silicate phase from concentrate grains, where iron is reduced earlier than in ilmenite grains. Formation of iron-containing silicate phase contributes ilmenite grains sintering. It was concluded that in the concentrate layer in contact with solid reducing agent layer in absence of contact of each ilmenite grain with solid reducing agent, the point contact of grains and presence of voids between them in the layer do not prevent propagation of reduction process in the layer of grains contacting with each other only.

Numerical simulation of conjugate heat transfer and surface radiative heat transfer using the [formula omitted] thermal radiation model: Parametric study in benchmark cases.

A parametric investigation of radiative heat transfer is carried out, including the effects of conjugate heat transfer between fluid and solid media. The thermal radiation is simulated using the P1-model. The numerical model and the thermal coupling strategy, suitable for a transient solver, is described. Such numerical coupling requires that the radiative equation is solved several times at each iteration; hence, the computational cost of the radiative model is a crucial issue. The P1-model is adopted because of its particularly fast computation. First, a collection of benchmark cases is presented and used to carefully validate the radiation model against literature results and to analyse the model prediction limits. Despite the simplicity of the model, it satisfactorily reproduces the thermal radiation effects. Some lack of accuracy is identified in particular cases. Second, a number of benchmark cases are described and adopted to investigate fluid–solid thermal interaction in the presence of radiation. Three cases are designed, to couple radiation with: pure conduction, conduction and forced convection, conduction and natural convection. In all the cases, the surface radiative heat transfer strongly influences the system thermodynamics, leading to a significant increase of the fluid–solid interface temperature. The main non-dimensional numbers, related to the mutual influence of the different heat transfer modes, are introduced and employed in the analyses. A new conduction-radiation parameter is derived in order to study the conductive boundary layer in absence of convective heat transfer.

35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: from Fuego to Eyjafjallajökull, and beyond

Abstract. Lidar measurements at Garmisch-Partenkirchen (Germany) have almost continually delivered backscatter coefficients of stratospheric aerosol since 1976. The time series is dominated by signals from the particles injected into or formed in the stratosphere due to major volcanic eruptions, in particular those of El Chichon (Mexico, 1982) and Mt Pinatubo (Philippines, 1991). Here, we focus more on the long-lasting background period since the late 1990s and 2006, in view of processes maintaining a residual lower-stratospheric aerosol layer in absence of major eruptions, as well as the period of moderate volcanic impact afterwards. During the long background period the stratospheric backscatter coefficients reached a level even below that observed in the late 1970s. This suggests that the predicted potential influence of the strongly growing air traffic on the stratospheric aerosol loading is very low. Some correlation may be found with single strong forest-fire events, but the average influence of biomass burning seems to be quite limited. No positive trend in background aerosol can be resolved over a period as long as that observed by lidar at Mauna Loa. We conclude that the increase of our integrated backscatter coefficients starting in 2008 is mostly due to volcanic eruptions with explosivity index 4, penetrating strongly into the stratosphere. Most of them occurred in the mid-latitudes. A key observation for judging the role of eruptions just reaching the tropopause region was that of the plume from the Icelandic volcano Eyjafjallajökull above Garmisch-Partenkirchen (April 2010) due to the proximity of that source. The top altitude of the ash above the volcano was reported just as 9.3 km, but the lidar measurements revealed enhanced stratospheric aerosol up to 14.3 km. Our analysis suggests for two or three of the four measurement days the presence of a stratospheric contribution from Iceland related to quasi-horizontal transport, differing from the strong descent of the layers entering Central Europe at low altitudes. The backscatter coefficients within the first 2 km above the tropopause exceed the stratospheric background by a factor of four to five. In addition, Asian and Saharan dust layers were identified in the free troposphere, Asian dust most likely even in the stratosphere.

Characterization of ion transport in the active layer of RO and NF polyamide membranes

The classic methods for characterizing transport of individual ions in membranes, such as steady-state streaming potential and membrane potential, apply in a straightforward way only to thick single-layer membranes. Application of these techniques to industrial composite RO and NF membranes has been largely unsuccessful, since these membranes have a multilayer structure, in which the in situ-prepared active layer is only a tiny fraction of the total diffusion resistance [1,2]. As a result of the polarization in the supporting layers, the “salt” phenomenological parameter, e.g., the permeability ws and reflection coefficient s deducible from filtration experiments, cannot be split into individual parameters of ions. Still more difficult is splitting the ionic permeabilities into the partitioning and diffusional factors. Such information could be however highly useful, both from the fundamental viewpoint of understanding the ion exclusion in membranes and from a practical viewpoint of developing predictive models of electrolyte separation for multicomponent salt mixtures. It has been pointed out that non-steady-state techniques, e.g., potential transients after rapidly changing the concentration or pressure gradient across the membrane, should have advantages over steady-state measurements [2,3]. The use of transients allows observation of different phenomena at various timescales and getting separate information on the partitioning and diffusion components of the permeability (cf. the popular time lag method). A novel technique presented in this study combines the use of a single layer in absence of external polarization with the use of a non-steady-state technique. The measurements employ a free-standing single layer of polyamide isolated from a genuine commercial membrane and placed on a solid electrode, which is characterized by means of electrochemical impedance spectroscopy (EIS) [4]. This approach effectively eleiminates both the polarization in support and ion coupling, which has been the main problems so far, and is capable of producing a comprehensive picture of ion transport in the polyamide layer.

The theoretical simulation of magnetized electron beam effects on radially polarized of an annular cylindrical piezoelectric crystal

By using the equilibrium equations for a hollow cylindrical piezoelectric layer in absence of body forces and taking into the account a magnetized electron beam in hollow region of this system the effects of thermal pressure, electrostatic self field and the strength of external magnetic field of a non-relativistic magnetized electron beam column on radially polarized of an annular cylindrical piezoelectric crystal in the steady state are simulated. The electrostatic potential profile in piezoelectric layer due to the mechanical pressure and electrostatic self field of electron beam are studied. Furthermore the graphs of the difference of potential Δ ϕ between inner and outer surfaces of piezoelectric versus to electron temperature, density of beam and the strength of external magnetic field are presented.

Shear layer oscillation along a perforated surface: A self-excited large-scale instability

Self-sustained oscillations of a free-shear flow, i.e., a jet, mixing layer, or wake, can arise from its impingement upon a downstream boundary; these oscillations are well documented. The present experiments demonstrate the existence of analogous oscillations for the case of a shear layer along a perforated plate. The spectrum of the pressure fluctuation at impingement shows sharply defined peaks. Moreover, the predominant frequency of oscillation exhibits a variation with either impingement length or inflow velocity that is remarkably similar to the case of the corresponding free-shear layer in absence of the perforated plate. Quantitative imaging yields patterns of large-scale vorticity concentrations and streamline topology, which have similar features for the shear layer along the perforated plate and the free-shear layer in absence of the plate. All of these observations indicate existence of a feedback mechanism for the shear layer along the perforated plate of finite length.

Carcinoma-associated retinopathy in breast carcinoma and carcinoid tumor

Carcinoma-associated retinopathy (CAR) is a rare paraneoplastic syndrome characterized by diffuse retinal photoreceptor degeneration in the presence of an epithelial tumor. We report on three patients, who developed paraneoplastic retinopathy in the presence of breast carcinoma and a cervical carcinoid tumor. In addition to biomicroscopic, psychophysical, electrophysiological and angiographic examinations, serum samples were obtained for immunohistochemical staining of human retina. Ring-shaped visual field defects with statokinetic dissociation and abnormal rod and cone responses were found. Immunohistochemical findings included reactions at the level of the inner segments of the photoreceptors, the outer nuclear layer and the outer plexiform layer in absence of anti-recoverin antibodies. CAR should be considered in the differential diagnosis of visual loss in presence of tumors other than small-cell carcinoma of the lung. The presence of antiretinal antibodies is compatible with a tumor-induced immune response to epitopes shared by both the tumor and retinal tissue. Apparently, various retinal proteins may function as autoantigens.

Ohmic potential drop during alkaline water electrolysis

Advanced alkaline water electrolysis may be an attractive method of producing hydrogen in the future. Large energy losses in water electrolysis are caused by evolution of gas bubbles. The main aim of this investigation is to obtain a dimensionless correlation for the increase of ohmic resistance between working electrode and diaphragm due to the presence of gas bubbles. The ohmic potential drop across the solution layer between diaphragm and working electrode, distance from the rear of the working electrode to the back wall of the compartment of the working electrode, the height in the electrolytic cell, the electrode type, nature of the electrode surface and of the gas evolved. From the experimental results the dimensionless correlation has been deduced as ▪ where Δ R wm * denotes the increase in resistance of solution layer between diaphragm and working electrode due to bubbles, divided by the resistance of this layer in absence of bubbles, Re Reynolds number, h * reduced height in the electrolytic cell, d wm * reduced distance between the working electrode and the diaphragm, n empirical experimental constant depending on nature of electrode surface, nature of gas evolved and whether or not the bubbles can enter a chamber behind the working electrode, K empirical constant depending on nature of both electrode surface and gas evolved. A remarkable result is that Δ R wm * is independent of current density in the current density range from 1–10 kA m −2.