Behaviour of Al–Ga alloy during cathodic polarization

The effect of the addition of small quantities of gallium to high-purity aluminium (99.999 wt%) on its electrochemical behaviour at high cathodic potentials (up to −2.0 V versus SCE), has been investigated using the potentiostatic pulse method. After cathodic polarization, anodic current was traced versus time to determine the quantity of charge necessary for oxidation of substances formed. Anodic current responses to the return to the E _OCP were also recorded in the period of 1 s. Time responses of the cathodic and anodic currents were analyzed. The cyclic voltammetry method was used to determine the hydration potential. The range of low and high cathodic potentials (LCP, HCP) was defined for all the samples. It has been established that the oxide film retains its properties in the LCP range, while in the HCP range cathodic breakdown and hydration of the oxide take place. Electrochemical methods complemented the SEM and EDAX analysis before and after the cathode pulse of −1.9 V versus SCE.     

Characterisation of Serbian unifloral honeys according to their physicochemical parameters

The characterisation of three unifloral Serbian honeys (acacia, sunflower and linden) was carried out based on some common physicochemical parameters (water content, electrical conductivity, free acidity, optical rotation and pH). A total of 201 honey samples, collected during the 2009 harvesting season, were analysed. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used to highlight the data structure and to find the relationships between the physicochemical parameters and the botanical origin of honey. The variables that best discriminated the samples were electrical conductivity (ranging from 0.10 to 0.76 mS/cm), free acidity (ranging from 7.80 to 42.70 meq/kg) and pH (ranging from 3.17 to 5.85). LDA resulted in a classification model with a high predictive power, allowing further assessment of unknown samples of the three unifloral honeys. Determination of geographic origin of acacia honey samples based on physicochemical properties and chemometrics was attempted.     

Contribution of activation products to occupational exposure following treatment using high-energy photons in radiotherapy

When high-energy photon beams are used for irradiation in radiotherapy, neutrons that are the result of photonuclear reactions create activation products that affect the occupational dose of radiotherapy staff. For the assessment of activation products in situ gamma spectroscopy was performed parallel to dose-rate measurements following irradiation, by using a high-energy photon beam from a linear accelerator Elekta Precise (Elekta, Stockholm, Sweden) used in radiotherapy. The major identified activation products were the following radioisotopes: (28)Al, (24)Na, (56)Mn, (54)Mn, (187)W, (64)Cu and (62)Cu. Based on the typical workload and dose-rate measurement, the assessed additional annual occupational dose ranged from 1.7 to 0.25 mSv. As the measured dose rate arising from the activation products rapidly decreases as a function of time, the assessed additional dose is negligible after 10 min following irradiation. To keep the occupational dose as low as reasonably achievable, it is recommended to delay entrance to the therapy room at least 2-4 min, when high-energy photons are used. This would reduce the effective dose by 30%.     

Biocompatibility of mesoporous SBA-16/hydroxyapatite nanocomposite and dentin demineralized particles on human dental pulp stem cells

In the present work, a biomaterial (SBA-16/HA) based on the growth of hydroxyapatite (HA) particles within an organized silica structure SBA-16 (Santa Barbara Amorphous-16) was developed to evaluate its application to act as a porous microenvironment promoting attachment and viability of human dental pulp stem cells of healthy deciduous teeth (SHED). First, SHED were isolated and their phenotypes were evaluated by flow cytometry. The samples of SBA-16/HA were characterized by X-ray diffraction (XRD), small and wide angle X-ray scattering (SWAXS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) equipped with energy dispersive spectra detector (EDS). Afterward, cells were cultured in the eluates of the above-mentioned biomaterial aged for 24 hr, 7. and 14 days. Bio-Oss® and dentin particles are involved for comparison and cells are cultured in the eluates of these two materials also. Thiazolyl Blue Tetrazolium bromide assay-MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide assay) was used for the determination of cell viability. The results obtained by all aforementioned characterization methods of SBA-16/HA, revealed a uniform spherical mesoporous structure, an intrinsic characteristic of this material. This material displayed excellent biocompatibility on SHEDs, and even proliferative potential, indicating that SBA-16/HA could potentially serve as a suitable substrate for bone regeneration. Contrary to SBA-16/HA, dentin particles showed low cytotoxicity at all time points, compared to control and Bio-Oss®groups. Our results substantiate the idea that SBA-16/HA has a beneficial effect on SHEDs, thus paving the way toward developing new material for bone replacement.     

Pressureless sintering of internally synthesized SiC-TiB2 composites with improved fracture strength

SiC-TiB₂ particulate composites were fabricated by converting TiO₂ to TiB₂ through the reaction between TiO₂, B₄C and C. The presence of initially very fine, in-situ created, TiB₂ particles increased driving force for sintering and enabled fabrication of a dense composite utilizing pressureless sintering and the liquid phase created between Al₂O₃ and Y₂O₃ additives. The effect of volume fraction of the in-situ formed TiB₂ on density, microstructure and flexural strength was discussed. It was found that the presence of TiB₂ particles suppressed the growth of SiC grains and enhanced fracture strength. The fracture strength of samples containing 12 vol% TiB₂ was more than 30% higher than that of the monolithic SiC. The effect of SiC grain size on fracture strength was also analyzed.     

Changes of phenolic compounds and antioxidant capacity in cocoa beans processing

A number of studies have shown that the consumption of cocoa and chocolate products has positive health effects on humans. The object of this research was to monitor changes of total and individual phenolics and antioxidant capacity during the cocoa bean manufacturing. The loss of cocoa phenolics and their antioxidant activity vary with the degree of technological process. The process of roasting and cocoa nib alkalisation had the major influence on phenolic compounds as well as on antioxidant capacity. The roasting treatment resulted in 14% loss of the total phenolics content, while alkalisation resulted in 64% loss of total phenolics content. Procyanidins B1 and B2 as well as (?)‐epigallocatechin were the unstable components, while caffeic acid derivate showed the greatest stability in all technological process. Furthermore, PCA showed that phenolic contents, antioxidant capacity and non‐fat cocoa solids parts of the samples were classified in groups according technological conditions.     

Neutron fluence-to-dose conversion coefficients for embryo and fetus

A problem of concern in radiation protection is the exposure of pregnant women to ionising radiation, because of the high radiosensitivity of the embryo and fetus. External neutron exposure is of concern when pregnant women travel by aeroplane. Dose assessments for neutrons frequently rely on fluence-to-dose conversion coefficients. While neutron fluence-to-dose conversion coefficients for adults are recommended in International Commission on Radiological Protection publications and International Commission on Radiological Units and Measurements reports, conversion coefficients for embryos and fetuses are not given in the publications. This study undertakes Monte Carlo calculations to determine the mean absorbed doses to the embryo and fetus when the mother is exposed to neutron fields. A new set of mathematical models for the embryo and fetus has been developed at Health Canada and is used together with mathematical phantoms of a pregnant female developed at Oak Ridge National Laboratory. Monoenergetic neutrons from 1 eV to 10 MeV are considered in this study. The irradiation geometries include antero-posterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT) and isotropic (ISO) geometries. At each of these standard irradiation geometries, absorbed doses to the fetal brain and body are calculated; for the embryo at 8 weeks and the fetus at 3, 6 or 9 months. Neutron fluence-to-absorbed dose conversion coefficients are derived for the four age groups. Neutron fluence-to-equivalent dose conversion coefficients are given for the AP irradiations which yield the highest radiation dose to the fetal body in the neutron energy range considered here. The results indicate that for neutrons <10 MeV more protection should be given to pregnant women in the first trimester due to the higher absorbed dose per unit neutron fluence to the fetus.     

The physicochemical characterization and in vitro/in vivo evaluation of natural surfactants-based emulsions as vehicles for diclofenac diethylamine

Two sugar-based emulsifiers, cetearyl alcohol & cetearyl glycoside and sorbitan stearate & sucrose cocoate, known as potential promoters of lamellar liquid crystals/gel phases, were investigated in order to formulate an optimal vehicle for amphiphilic drug—diclofenac diethylamine (DDA).

Physico-chemical characterization and study of vehicle's physical stability were performed. Then, the in vitro DDA liberation profile, dependent on the mode of drug incorporation to the system, and the in vivo, short-term effects of chosen samples on skin parameters were examined.

Droplets size distribution and rheological behavior indicated satisfying physical stability of both types of vehicles. Unexpectedly, the manner of DDA incorporation to the system had no significant influence on DDA release. In vivo study pointed to emulsion's favorable potential for skin hydration and barrier improvement, particularly in cetearyl glycoside-based vehicle.     

The Effects of a Meldonium Pre-Treatment on the Course of the Faecal-Induced Sepsis in Rats

Sepsis is a life-threatening condition caused by the dysregulated and overwhelming response to infection, accompanied by an exaggerated pro-inflammatory state and lipid metabolism disturbance leading to sequential organ failure. Meldonium is an anti-ischemic and anti-inflammatory agent which negatively interferes with lipid metabolism by shifting energy production from fatty acid oxidation to glycolysis, as a less oxygen-demanding pathway. Thus, we investigated the effects of a four-week meldonium pre-treatment on faecal-induced sepsis in Sprague-Dawley male rats. Surprisingly, under septic conditions, meldonium increased animal mortality rate compared with the meldonium non-treated group. However, analysis of the tissue oxidative status did not provide support for the detrimental effects of meldonium, nor did the analysis of the tissue inflammatory status showing anti-inflammatory, anti-apoptotic, and anti-necrotic effects of meldonium. After performing tissue lipidomic analysis, we concluded that the potential cause of the meldonium harmful effect is to be found in the overall decreased lipid metabolism. The present study underlines the importance of uninterrupted energy production in sepsis, closely drawing attention to the possible harmful effects of lipid-mobilization impairment caused by certain therapeutics. This could lead to the much-needed revision of the existing guidelines in the clinical treatment of sepsis while paving the way for discovering new therapeutic approaches.