Ultraviolet radiation and melanogenesis

Light radiation is a part of the electromagnetic radiation, and it consists of the ultraviolet (UV) radiation, visible light, and infrared radiation. UV radiation energy is absorbed in the form of photons in biomolecules (chromophores) and induces various cellular reactions, out of which photochemical and photosensitizing are the most significant. In contact with the skin UV radiation incites protection mechanisms: the most important are stratum corneum thickening and melanin synthesis (melanogenesis). Basic role of melanin is absorption and scattering of UV rays and neutralization of free radicals. In this review physical characteristics of UV radiation, its biological effects, and relation to melanogenesis and carcinogenesis are discussed

Experimental and Discrete Element Model Investigation of Limestone Aggregate Blending Process in Vertical Static and/or Conveyor Mixer for Application in the Concrete Mixture

The numerical model of the granular flow within an aggregate mixture, conducted in the vertical static and/or the conveyor blender, was explored using the discrete element method (DEM) approach. The blending quality of limestone fine aggregate fractions binary mixture for application in self-compacting concrete was studied. The potential of augmenting the conveyor mixer working efficiency by joining its operation to a Komax-type vertical static mixer, to increase the blending conduct was investigated. In addition the impact of the feed height on the flow field in the cone-shaped conveyor mixer was examined using the DEM simulation. Applying the numerical approach enabled a deeper insight into the quality of blending actions, while the relative standard deviation criteria ranked the uniformity of the mixture. The primary objective of this investigation was to examine the behavior of mixture for two types of blenders and to estimate the combined blending action of these two mixers, to explore the potential to augment the homogeneity of the aggregate fractions binary mixture, i.e., mixing quality, reduce the blending time and to abbreviate the energy-consuming

A quick, simplified approach to the evaluation of combustion rate from an internal combustion engine indicator diagram

In this paper a simplified procedure of an internal combustion engine in-cylinder pressure record analysis has been presented The method is very easy for programming and provides quick evaluation of the gas temperature and the rate of combustion. It is based on the consideration proposed by Hohenberg and Killman, but enhances the approach by involving the rate of heat transferred to the walls that was omitted in the original approach. It enables the evaluation of the complete rate Of heat released by combustion (often designated as gross heat release rate or fuel chemical energy release rate), not only the rate of heat transferred to the gas (which is often designated as net heat release rate). The accuracy of the method has been also analyzed and it is shown that the errors caused by the simplifications in the model are very small, particularly if the crank angle step is also small A several practical applications on recorded pressure diagrams taken from both spark ignition and compression ignition engine are presented as well

Cancer Incidence in a Population Living Near a Petrochemical Facility and Oil Refinery

There is growing concern that pollution from petrochemical and oil refinery installations in Pan~evo (Serbia) has increased the incidence of various diseases including cancer. The aim of our study was to investigate cancer incidence in Pan~evo and to compare it with the region of central Serbia. Cancer incidence data were obtained from the corresponding Serbian Cancer Registries. Systematic local monitoring of benzene, toluene and methyl mercaptane in the atmosphere within Pan~evo’s industrial area indicated that the average monthly and yearly concentrations often exceeded permitted levels proposed by EU standards (5 mgm–3). Cancer incidence was lower in Pan~evo than in central Serbia (the standardised incidence for all types of cancers in Pan~evo was 218.3 and in central Serbia it was 241.7 per 100,000 inhabitants). The available data do not allow us to correlate air pollution in Pan~evo with increased cancer incidence

Rare-earth (Gd3+,Yb3+/Tm3+, Eu3+) co-doped hydroxyapatite as magnetic, up-conversion and down-conversion materials for multimodal imaging

Taking advantage of the flexibility of the apatite structure, nano- and micro-particles of hydroxyapatite (HAp) were doped with different combinations of rare earth ions (RE3+ = Gd, Eu, Yb, Tm) to achieve a synergy among their magnetic and optical properties and to enable their application in preventive medicine, particularly diagnostics based on multimodal imaging. All powders were synthesized through hydrothermal processing at T ≤ 200 °C. An X-ray powder diffraction analysis showed that all powders crystallized in P63/m space group of the hexagonal crystal structure. The refined unit-cell parameters reflected a decrease in the unit cell volume as a result of the partial substitution of Ca2+ with smaller RE3+ ions at both cation positions. The FTIR analysis additionally suggested that a synergy may exist solely in the triply doped system, where the lattice symmetry and vibration modes become more coherent than in the singly or doubly doped systems. HAp:RE3+ optical characterization revealed a change in the energy band gap and the appearance of a weak blue luminescence (λex = 370 nm) due to an increased concentration of defects. The "up"- and the "down"-conversion spectra of HAp:Gd/Yb/Tm and HAp:Gd/Eu powders showed characteristic transitions of Tm3+ and Eu3+, respectively. Furthermore, in contrast to diamagnetic HAp, all HAp:RE3+ powders exhibited paramagnetic behavior. Cell viability tests of HAp:Gd/Yb/Tm and HAp:Gd/Eu powders in human dental pulp stem cell cultures indicated their good biocompatibility

Plasma glucose, serum insulin and C-peptide in patients with various stages of chronic renal failure [Glikemija, insulinemija i ce-peptidemija kod bolesnika s razlicitim stepenom bubrezne insuficijencije.]

Plasma glucose, serum insulin and C-peptide were measured in patients with various stages of chronic renal failure (CRF). In this study we observed 50 patients: 26 women and 24 men, between the ages of 17 and 73. Following various stages of CRF our patients were devided into IV groups, with 10 patients in each. V-th group was control group with 10 healthy persons. Plasma glucose, serum insulin and C-peptide were measured in the fasting state and following the 2 hours oral glucose tolerance test (OGTT). In the fasting state, plasma glucose and serum insulin levels were normal in all groups. With deterioration of the renal function plasma glucose and serum insulin increased slower during OGTT but their levels also decreased slower. Fasting levels of C-peptide increased continually with deterioration of renal function in all patients and values were significantly higher than in control group

Dekontaminacija alkidno-karbamidnih boja na metalu kontaminiranih visokotoksičnim jedinjenjima

The paper investigates rates of sorption and desorption of 2,2'-dichlordi-ethylsulphide (sulphur yperite), 1,2,2-trimethylpropyl-methylfluorophosphonate (soman), soman viscous recipe and O-ethyl-S-(2-diisopropyIamino-ethyl) of methyltiophosphonate (VX) on protective alkyd-carbamide paints on metals. Decontamination rates of metal surfaces covered with alkyd-carbamide paint and contaminated by cited contaminants have been..Ispitane su brzine sorpcije i desorpcije 2.2'-dihlordietilsulfida (sunipornog iperita), 1,2,2-trimetilpropil-metil-fluorofosfonata (somana), viskozne recepture somana, 0-etil-S-(2-diizopropilaminoetil) metiltiofosfonata (VX) na zaštitnim bojama alkidno-karbamidnog tipa na metalu. Određene su brzine dekontaminacije metalnih površina obojenih alkidno-karbamidnom bojom i kontaminiranih navedenim kontaminantima. Kao dekontaminanti korišćeni su rastvori: natrijum-hidroksid, kalcijum-hipohlorit u vodi, natrijum-etilat u etanolu i rastvori za dekontaminaciju DS-2 i TD-A. Nađene su optimalne koncentracije aktivnih materija u vodenim rastvorima za dekontaminaciju. Određeni su uticaji temperature dekontaminacionih rastvora na brzinu i efikasnost dekontaminacije

Injectable polydimethylsiloxane-hydroxyapatite composite cement

An injectable polydimethylsiloxane/hydroxyapatite (PDMS/HAp) composite cement was synthesised using linear PDMS and HAp (particles of about 100 nm in size) of different mass fractions. The effect of HAp mass fraction (5-60 mass%) on the hardness of PDMS/HAp composite cement was investigated. The hardness achieved is 25-49degreesShA. Differential scanning calorimetry (DSC) was used to study the cross-linking process and the influence of HAp on the temperature and duration of PDMS/HAp cross-linking. The microstructure of composite cement surfaces after 10 days in vivo tests was observed by scanning electron microscopy (SEM). The presence of well-adhered macrophages, fibroblasts and monocytes was found on the implant surface upon its extraction from the organism

Plasma glucose, serum insulin and C-peptide in patients with various stages of chronic renal failure [Glikemija, insulinemija i ce-peptidemija kod bolesnika s razlicitim stepenom bubrezne insuficijencije.]

Plasma glucose, serum insulin and C-peptide were measured in patients with various stages of chronic renal failure (CRF). In this study we observed 50 patients: 26 women and 24 men, between the ages of 17 and 73. Following various stages of CRF our patients were devided into IV groups, with 10 patients in each. V-th group was control group with 10 healthy persons. Plasma glucose, serum insulin and C-peptide were measured in the fasting state and following the 2 hours oral glucose tolerance test (OGTT). In the fasting state, plasma glucose and serum insulin levels were normal in all groups. With deterioration of the renal function plasma glucose and serum insulin increased slower during OGTT but their levels also decreased slower. Fasting levels of C-peptide increased continually with deterioration of renal function in all patients and values were significantly higher than in control group