In the T-zone, a thinner lipid coat resulted in relatively high TEWL and pH levels changing toward alkaline. In the U-zone, thinner lipid coat was accompanied by lower TEWL and pH changing toward alkaline. We also observed that lower values of lipid coat up to 100 μg/cm were associated with higher pH values ranging toward the basic character pH 5.6-9.0).
Concrete is one of the main materials used for gamma and neutron shielding. While in case of gamma rays an increase in density is usually efficient enough, protection against neutrons is more complex. The aim of this paper is to show the possibility of using the Monte Carlo codes for evaluation and optimization of concrete mix to reach better neutron shielding. Two codes (MCNPX and SPOT -written by authors) were used to simulate neutron transport through a wall made of different concretes. It is showed that concrete of higher compressive strength attenuates neutrons more effectively. The advantage of heavyweight concrete (with barite aggregate), usually used for gamma shielding, over the ordinary concrete was not so clear. Neutron shielding depends on many factors e.g. neutron energy, barrier thickness and atomic composition. All this makes a proper design of concrete as a very important issue for nuclear power plant safety assurance.
Background: Laxity and rhytides are manifestations of photodamage on the face and chest. Nonablative radiofrequency (RF) is one of the most common procedures used for skin rejuvenation.Aim: The aim of this study was to assess the elasticity of face and chest skin after multipolar radiofrequency.Patients/Methods: Thirty women, aged 43-68, were included in the study. Twenty women were postmenopausal and 10 were premenopausal. They received 4 treatment sessions with an application of nonablative radiofrequency in 2-week intervals.Biomechanical properties of the skin were measured with the use of a Cutometer. Results:The objective evaluation in a cutometric analysis showed a statistically significant improvement between measurements taken in the pretreatment period and 3 months after the treatment. Conclusions:The study is an objective confirmation that RF treatment improves skin elasticity. The method may appear to be beneficial for women of any age and skin types. It is a noninvasive treatment with a low risk of complications. K E Y W O R D S chest rejuvenation, face rejuvenation, nonablative radiofrequency 1 | BACKGROUND Aging of the face, neck, and chest (décolletage) is a multifactorial process caused by the cumulative effects of intrinsic and environmental factors. It results in wrinkles, skin laxity, dyschromia, teleangiectasias, atrophy, and roughness of the epidermis. The growing demand to maintain a youthful appearance has led to an increase in the number of dermatological and surgical procedures aiming at delaying the process of skin aging. Advances in understanding skin biology have led to the development of many skin rejuvenation technologies, but there is an increased interest in nonablative treatment which tend to have minimal downtime and almost no complications. One such method is radiofrequency (RF). A RF device generates heat by transferring electrical energy, in the form of electromagnetic waves, from the electric field of the RF device to electrically charged particles in the tissue. 1 The heat leads to thermal damage of the collagen by breaking some cross-links, making the triple helix structure unwind. Some collagen fibers undergo denaturation, but then neocollagenesis occurs, increasing dermal thickness. Remodeling of collagen bundles and formation of new collagen lasts for months after the treatment. 2-6 Zelickson et al 2 showed increased expression of messenger RNA for collagen type 1 after RF treatment on abdomen skin. Kaplan and Gat 3 noted an induction of new collagen synthesis (focal thickening of collagen fibers) in skin biopsies done after the RF therapy. Several types of RF devices are available on the esthetic market.Among the most common are monopolar, bipolar, multipolar, and fractional bipolar ones. A monopolar RF device has only one active electrode, which remains in contact with the skin, and one grounding
Abstract. The process of design of building composites, like concrete is a complex one and involves many aspects like physical and mechanical properties, durability, shielding efficiency, costs of production and dismantlement etc. There are plenty of parameters to optimize and computer tools can help to choose the best solution. A computer aided design plays an important role nowadays. It becomes more accurate, faster and cheaper, so laboratories often apply computer simulation methods prior to field testing. In case of nuclear engineering, the radiation shielding problems are of much importance, because safety of such facilities is a key point. In this article the most effective methods for neutron shielding studies based on Monte-Carlo simulations of neutron transport and nuclide activation studies in concrete are presented. Two codes: MCNPX and CINDER'90 are extensively used to compare the shielding efficiency of commonly used concretes and to study the influence of concentration of B, Ba and Fe elements on shielding efficiency.
Concrete has been used as a shield against high-energy photons and neutrons since the beginning of use of nuclear reaction in energy, medicine and research. From that time the progress in concrete technology is huge -very good concrete used in 60's was about 30 MPa compressive strength, and now the recommendation of ETC-C is to use in EPR nuclear power plant the concrete at least class C45/55 for airplane resistant shell or class C40/50 for other structures. The Monte Carlo computer simulations indicate that an increase in density of the shielding member has a minor effect on the weakening of neutron transport and, therefore, the optimal composition of a shielding concrete against gamma radiation is different than the optimal composition of shielding concrete against neutron radiation. Neutron stopping is a two-step effect: slowing down of fast neutrons and absorption of thermal ones. Both result from the atomic composition of the barrier. The paper presents an analysis of neutrons transport through concrete cement mortar and polymer cement composites mortar based on specially designed experiments which allows for measuring fast neutron attenuation and thermal neutron capture separately. The aim of experiments was to find an influence of the cement type, polymer addition and moisture content on both aspects of neutron shielding properties of a composite. The experimental results were confirmed in MCNP simulations. There was found an influence of cement type on fast neutron attenuation due to differences in chemical composition. Next an important improvement of both fast neutron attenuation and thermal neutron capture due to polymer modification of concrete. The last was fond of clear linear relationship between fast neutron attenuation to the hydrogen content which shows the possibility of using this phenomenon in building material investigation like measurement of moisture content or polymer content in the polymer cement composites.
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