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1
Content available Research of acoustical impedance of human skin
EN
This paper presents the methodology of measuring acoustic impedance of human skin and discusses the results of the tests. Measurement of the acoustic impedance of human skin is a complex issue. The most difficult thing is related to the nature of the object of research. Cooperation of volunteer participating in the experiment is crucial in collecting accurate data. Appropriate measuring conditions must be provided because of the length of time required to conduct measurement. The Kundt tube method has been used as a research technique applied for evaluation of the material impedance. It was assumed that the results would differ with regard to different points chosen for measurement, located on the body of volunteer as well as with regard to the features of the skin structure of the volunteers participating in this experiment. Results have revealed that for different people similar parameters have been obtained. Moreover, results are alike for various measured points localized on person’s body.
2
EN
Skin drug delivery systems are a constant source of interest because of the benefits that they offer to overcome many drawbacks associated with other modes of drug delivery (i.e. oral, intravenous, etc.). Because of the impermeable nature of the skin, designing a suitable drug delivery vehicle that penetrates the skin barrier is challenging. Skin drug delivery can be subdivided into topical and transdermal (Fig.1). In a topical administration the drug is intended to act at skin level, this is indicated for the treatment of skin diseases. The aim of transdermal administration is getting a systemic release and in this case the skin represents a barrier not a target. The availability of drugs or other active substances through the skin depends basically on two consecutive steps: the release of these drugs or substances from vehicle or carrier and their subsequent permeation through the skin. Hence, studies on the specific properties of vehicles or carriers, such as their rheological behaviours, are of great interest in the field of pharmaceutical products. The objective of the present study is to systematically characterize a nonlinear rheological behaviour and flow properties of drugs and drug carriers into topical and transdermal administration. To this aim, one- and threedimensional rheological models are presented, which may be used to describe drug release through the skin and through the extracellular and interstitial matrix structures. Finally, the rheological measurements of some commercial creams and ointments were made.
3
Content available Fractal model of transdermal drug delivery
EN
Skin, separating the vital organs of a human body, is a desirable route for drug delivery. However, the intact skin is normally permeable only for drug molecules with a low molecular weight. The stratum corneum (SC), being the outermost layer of the skin and the epidermis being the second – more permeable – layer of the skin, play an essential function in transdermal drug delivery. Physical and chemical methods of skin poration are used to enhance transdermal drug delivery. Each poration leads to an irregular system of pores which are connected with a system of micro-capillaries passing through the epidermis. Both the systems by their irregularity form a fractal porous matrix. Drugs administrated by this matrix can be either suspensions and solutions or creams and gels, therefore they have to be modelled as non-Newtonian fluids. To analyse the fluid flow through the porous matrix the model of the epidermis is assumed as gobbet-andmortar with the tortuous mortar of variable thickness and after transition from the mortar to the tube one considered classical and fractal capillary flows of selected non-Newtonian fluids. Fractal expressions for the flow rate, velocity and permeability of fluids flow in a porous matrix are derived based on the fractal properties of the epidermis and capillary model. Each parameter in the proposed expressions does not contain any empirical constant and has a clear physical meaning and the proposed fractal models relate the flow properties of considered fluids with the structural parameters of the epidermis as a porous medium. The presented analytical expressions will help understand some of the physical principles of transdermal drug delivery.
4
Content available Drug diffusion transport through human skin
EN
The stratum corneum (SC) forms the outermost layer of the human skin and is essentially a multilamellar lipid milieu punctuated by protein-filled corneocytes that augment membrane integrity and significantly increase membrane tortuosity. The lipophilic character of the SC, coupled with its intrinsic tortuosity, ensure that it almost always provides the principal barrier to the entry of drug molecules into the organism. Drugs can be administered either as suspensions or as solutions and the formulation can range in complexity from a gel or and ointment to a multilayer transdermal path. In this paper, we discuss theoretical principles used to describe transdermal release and we show that relatively simple membrane transport models based on the appropriate solution to the Fick’s second law of diffusion can be used to explain drug release kinetics into such a complex biological membrane as the human skin. To apply the Fick’s law we introduced into our considerations a brick-and-mortar model with two factors of tortuosity. Assuming that the mortar thickness is variable we also introduced the hindrance factor allowing us to model this variability. Having the modified Fick’s equation we presented its general solution and two special cases of this solution frequently applicable in permeation experiments. It seems that the solutions presented herein better approximate the real conditions of drug delivery then these well known.
5
PL
Celem prac przedstawionych w niniejszym artykule była poprawa precyzji detekcji ludzkiej skóry w obrazach cyfrowych na podstawie barwy. Wcześniejsze badania autorów wskazywały na możliwość znacznej redukcji błędów segmentacji poprzez zastosowanie analizy obszarów spójnych. W ramach prezentowanych prac zastosowany został mechanizm wieloskalowej analizy ekstremów lokalnych w obrazie transformacji falkowej, pozwalający na wybranie tych obszarów spójnych, które istotnie przedstawiają ludzką skórę. Przedstawione wyniki badań eksperymentalnych potwierdziły skuteczność proponowanych rozwiązań.
EN
This paper is focused on improving color-based human skin detection in digital images. Our earlier works indicated that the segmentation errors can be significantly reduced using blob detection. The main contribution of this work is the multiscale analysis of local extrema in the wavelet domain, which allows selecting the blobs that indeed represent the human skin. The experimental results have confirmed that the proposed method is effective and reduces the segmentation error.
6
Content available remote Modelling of light and human skin interaction using Kubelka-Munk theory
EN
The numerical analysis of thermal processes and light distribution in human skin is presented. The Kubelka-Munk theory has been used for modeling diffused light in tissue, while the Arrhenius scheme for modeling coagulation changes in human skin. At the stage of numerical realization, the boundary element method has been used. In the final part of the paper, the results obtained are presented.
PL
W artykule omówiono szkodliwe działanie naturalnego promieniowania nadfioletowego na skórę. Promieniowanie nadfioletowe (UV) to niewidzialne promieniowanie elektromagnetyczne o długości fali od 200 do 400 nm, które - obok promieniowania podczerwonego i światła widzialnego wchodzi w skład docierającego do ziemi promieniowania słonecznego. Spośród wszystkich rodzajów promieniowania słonecznego właśnie promieniowanie nadfioletowe ma największy wpływ na organizm ludzki, a skutki jego oddziaływania na organizm człowieka mogą być zarówno korzystne, jak i bardzo szkodliwe.
EN
This article discusses harmful impact of ultraviolet (UV) radiation on human skin. UV radiation is an invisible electromagnetic radiation in the 200 - 400 nm wave range which, in addition to infrared radiation and daylight, makes up the sunlight that reaches the Earth. From among all types of radiation it is ultraviolet radiation that has the greatest impact on the human body. Exposure to to UV radiation may be both positive and seriously harmful.
PL
Na podstawie analizy dostępnych materiałów i dokumentów dotyczących statusu prawnego i praktycznego stosowania środków ochrony skóry (ŚOS) w UE i wybranych krajach opracowano w CIOP-PIB projekt wytycznych w zakresie wymagań, doboru i stosowania tych preparatów. W artykule przedstawiono: cel i zakres wytycznych, formułowane definicje, charakterystykę stosowanych środków ochrony skóry oraz identyfikację zagrożeń i ocenę ryzyka na stanowiskach pracy w odniesieniu do skóry.
EN
Skin protection measures (SPMs) - barrier creams/gels - are a way of protecting workers' hands against hazardous substances at workplaces where gloves cannot be used. To reduce the risk of developing irritant and allergic contact dermatitis in hand care and in industry, preventive measures are recommended. SPMs are very often misused as skin care products but for users safety and reliability of the preparation are most important. That is why only tested, effective, clearly marked preparations should be offered on the market. The developed draft guidelines include definitions of SPMs, current legal and technical requirements, marking, assortment and use.
EN
This paper reviews wetting phenomena in relation to different types of solids and human skin in the presence of surfactants. Wettability of solids by surfactants is important for many technological applications. The addition of surfactants is necessary to achieve a better wettability of a given solid. In the first part of this article the definition of a contact angle and an interfacial tension along with methods of their determination is presented. Next, a relationship between a liquid--air, a solid-air and a solid-liquid interfacial tensions and wettability of solids is shown. Three types of wetting are discussed in this work: a spreading wetting, an adhesional wetting, and an immersional wetting. Wettability forces of hard surface and powders are also described in this part of the article. In the third part of the article main aspects related to the solids critical surface tension of wetting are presented. Different problems of solids' wetting critical surface tension are described, since there is still no unambiguous method to determine this value. Later, based on the Lucassen-Reynolds equation we described the dependence between the adsorption of surfactants at the interfaces, mainly in a solid-water-air systems and wetting of solids, because they are both strongly related. From this equation the slope of a plot of ?LVcos? (adhesion tension) versus ?LV (surface tension) gives us the information about the surface concentration of the surfactant at water-air and a solid-water interfaces in a solid--water-air system including both non-polar (low-energy) and polar (high-energy) solids. We have also shown that in the case of hydrophobic solids, for several types of surfactants, there is a constant negative slope of ?LV cos?-?LV curve. However, for high-energy polar solids the positive slope of this curve is observed and there is no linear dependence between adhesional and surface tension. Thus, for a high energy solid-aqueous surfactant solution-air systems it is difficult to establish synonymous mutual relationships between the adsorption of surfactant at a solid-air, a solid-liquid and a liquid-air interfaces and wettability of high-energy hydrophilic solids. At the end we presented main problems dealing with wettability of human skin surface, which is the most important factor of the skin protective function. It minimizes water loose, prevents entry of a foreign matter and chemicals, and defines smoothness and elasticity of the skin. Surprisingly, this subject has received a little attention in the literature. The human skin surface, after the extraction of sebum (skin surface lipids) belongs to hydrophobic surfaces (low-energy) in terms of critical surface tension and polar and dispersion components of a free surface energy. El-Shimi and Goddard compared the skin surface with polymer surfaces such as polyvinylchloride, polytetrafluoroethylene and polyethylene, but we have to remember that the human skin is a living matter and in the presence of sebum becomes hydrophilic. In order to remove this fatty film from the skin surface cleansing products, which contain many various surfactants, are used. Good wetting and cleansing effects of such products depend on surfactants ability to adsorb on the skin surface and reduce an interfacial tension at water-skin interface in skin-water-air system.
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