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The luminescence properties of dysprosium ions in silica xerogel doped with Gd1.6Dy0.4(WO4)3

Grobelna B., Synak A., Bojarski P.

Optica Applicata

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2012

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Vol. 42, nr 2

337-344

EN

The new material consisting of Gd1.6Dy0.4(WO4)3 incorporated into silica xerogel was prepared via the coprecipitation method. The luminescence properties of the studied material were analyzed by means of emission and excitation spectra, including the result of luminescence lifetimes of Dy(III) ion. The enhanced yellow emission due to the excitation energy transfer from WO42- group to Dy(III) ion upon excitation at exc = 240 nm is the main result of this paper.

2

Testing of peptides with moisturizing properties in hydrogel masks on a pig skin

Lubkowska B., Grobelna B., Maćkiewicz Z.

Polish Journal of Applied Chemistry

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2011

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Vol. 55, nr 3-4

105-113

EN

Moisturizing cosmetics, such as hydrogel masks, are very popular skincare products. They have a very simple composition, are easy to use and are not expensive. In this experiment the formula of cosmetic product was improved by inclusion of oligopeptide sequences in hydrogel mask. Peptides as active ingredients in cosmetics showed the ability to transport ions, decrease facial musclc contraction and stimulate human skin fibroblasts. We attempted the synthesis of signal peptides because of the effects they have on the skin surface. A series of skin hydration measurements using a model of pig skin were made. Results confirmed beneficial effects of the additional peptide ingredient on the properties of the mask. Peptides due to their appropriate sequence and in an adequate concentration could induce significant effects of moisturizing on skin.

3

Rola składników aktywnych w procesie starzenia się skóry

Łubkowska B., Grobelna B., Maćkiewicz Z.

Wiadomości Chemiczne

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2010

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[Z] 64, 11-12

1053-1071

EN

Skin is the coating of all human and animal organisms. It is a kind of space where different processes take place. Skin is the largest and the heaviest organ in the body. Also, it is a barrier, that stops water and the part of body, which should be particularly protected [1]. The skin is composed of three main layers: epidermis (Fig. 1), dermis (Fig. 3) and subcutaneous tissue (Fig. 5). Each of these layers has completely different role and is characterized by various properties. Epidermis is the outermost layer of skin. It consists of a living and a dead zone. The living area forms new cells which are the subject to further changes, while in the zone of dead cells they are highly flattened and devoid of nuclei [2]. In the epidermis, exactly in the reproductive output layer there are melanocytes, which are cells responsible for production of the pigment - melanin (Fig. 2). Melanin is responsible for color of hair, eyes and skin. It is formed from tyrosine as a result of numerous biochemical reactions [3]. Biological activity of melanin is determined by the presence of appropriate peptide. The sequences of its active components are: Ser-Tyr, Ser-Met-Glu-His-Phe-Arg, and Trp-Gly-Lys-Pro-Val. It is possible to protect the skin also against the solar radiation. The hormone MSH absorbs and reflects UV radiation. Under the influence of UV radiation the amount of melanin increases, causing temporary changes in skin color [3]. Under the epidermis there is a proper skin, which is composed of elastic fibers, collagen fibers, and the basic substance, which fuses the fiber elements. The elastic fibers are scattered among collagen fibers. Proper skin is the place where a valuable protein - very important in cosmetics - occurs - the native collagen. It is the main protein of connective tissue. Collagen has a very high tensile strength and is a major component of tendons. It is responsible for skin elasticity. Loss of collagen from the skin causes wrinkles [4]. A distinctive layer of skin is the subcutaneous tissue. It combines dermis with muscles. It is composed of fat cells separated by connective tissue. The size and the shape of fat cells vary depending on gender, diet and also age [5]. Skin, like other authorities is aging. These process may be accelerated or delayed under the influence of various endogenous and exogenous elements (Tab. 1). Also genetic predisposition are of significant importance. It seems that, as soon as we age, we inherit from our ancestors. To delay the aging process, it is necessary to properly take care of and protect the skin. There are many ways to delay aging of the skin. The most successful, for example cosmetics with active ingredients such as peptides, will be presented here.

4

The effect of WO42– group in xerogels doped with Ln2–xPrx(WO4)3 where Ln = La, Gd

Grobelna B., Bojarski P.

Optica Applicata

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2010

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Vol. 40, nr 2

359--366

EN

We present a synthesis of highly efficient xerogels doped with Ln 2–x Prx(WO4)3, where Ln = La or Gd as novel phosphors. For comparison, the synthesis of xerogels doped only with Pr(III) and La(III) ions was made. The photoluminescence properties of Pr(III) ions in xerogels were studied by means of luminescence spectroscopy. In particular, an efficient energy transfer from WO42– to Pr(III) ions was observed and demonstrated by their enhanced luminescence intensity. Especially interesting seems to be strong red acceptor emission observed upon excitation at 240 nm (donor excitation). Therefore, 4f–4f emission makes the system usable for red phosphor applications. Additionally, the emission intensity of the materials was improved by reducing concentration of such quenchers as water molecules and OH groups by the thermal treatment.

5

Luminescence based on energy transfer in xerogels doped with Tb2-xEux(WO4)3

Grobelna B.

Optica Applicata

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2008

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Vol. 38, nr 1

39-47

EN

A series of luminescent materials consisting of Tb2-xEux (WO4)3 entrapped in silica xerogel were successfully prepared. The parameter x in the formula changed from 0.4 to 2. Spectroscopic properties such as absorption and luminescence of optically active ions were studied at room temperature. Owing to the energy transfer from the WO42- groups (ligand-metal charge transfer, (LMCT)) the lanthanide ions show their characteristic emissions in Tb2-xEux(WO4)3 entrapped in silica xerogel, i.e., 5D0 › 7FJ (J = 0, 1, 2, 3, 4) transition for Eu3+ ion and 5D4 › 7FJ (J = 6, 5, 4, 3) transition for Tb3+ ion. The energy transfer is effective for the mixed tungstate salt Tb1.35Eu0.65(WO4)3 entrapped in silica xerogel. The Eu(III) emission intensity in the materials under study increases with an increase in the annealing temperature from 600 to 900 °C. This is due to the removal of the effective O -H quenchers from the coordination sphere of the Eu(III) ion.