The evaluation of surface and wastewater genotoxicity using the Allium cepa test

Screening for mutagens in complex environmental mixtures, such as surface water or industrial wastewater, is gradually being accepted as a routine method in environmental monitoring programs. In the present work, the simplified Alliumcepa root assay was utilized to evaluate the possible cyto- and genotoxic effects of surface and wastewaters collected near the Sava River (Croatia) over a three-month monitoring period. Physicochemical characterization of the water samples included measurements of conductivity, chemical and biological oxygen demand, levels of suspended matter and salts, nitrate, nitrite, ammonium, total nitrogen and total phosphorus. Morphological modifications of the A. cepa roots, inhibition of root growth, cell division and induction of mitotic and chromosomal aberrations were observed. The most highly polluted water samples (industrial effluents) caused an inhibition of root growth of over 50%, a decrease in the mitotic index of over 40%, and a considerable increase in chromosomal aberrations compared to the control. The measured biological effects of some water samples appeared related to the physicochemical characteristics. Therefore, mutagenicity/genotoxicity assays should be included, along with conventional chemical analysis, in water quality monitoring programs. Their use would allow the quantification of mutagenic hazards in surface and wastewaters.     

Electrochemical properties of aluminium alloys containing indium,gallium and thallium

The electrochemical behaviour of aluminium alloyed with small amounts (up to 0.2%) of indium, gallium and thallium has been investigated. It has been found that these additions result in:

1. A considerable shift of the rest potential in the negative direction (to 1.4–1.7 V versus SCE),
2. A significant increase of the passivating current density (up to 0.1–1 Acm^?2) and
3. A considerable decrease in the negative difference effect (increase of the faradaic efficiency to

99.5%) compared to the behaviour of pure aluminium. Except for the gallium alloy, the rate of corrosion of the alloys in neutral salt solutions is also decreased compared to that of pure aluminium. A ternary alloy, Al-0.01 In-0.01 Ga, exhibited a more negative rest potential than the Al-In alloy and a corrosion stability superior to that of the Al-Ga alloy. The negative difference effect was found to depend on the cation of the neutral salt in solution. The lowest effect was obtained in ammonium chloride solutions.     

TEM investigations in the PFN-PFW-PZN perovskite system

Using an analytical electron microscope, the distribution of phases and order-disorder phenomena in the Pb(Fe_1/2Nb_1/2)O₃-Pb(Fe_2/3W_1/3)O₃-Pb(Zn_1/3Nb_2/3)O₃ (PFN-PFW-PZN) perovskite system were examined. It was found that after sintering the solid solution, small cubic pyrochlore particles with chemical composition close to Pb(Fe_0.28Zn_0.01Nb_0.50W_0.21)O_3.4 anda ₀=1.05 nm were present in the 0.8 mol % Pb₂WO₅-0.2 mol % PbO liquid phase. In samples fired at 1000 °C, several 10 nm sized ordered areas with faint F spots in the selected-area electron diffraction pattern and (h+1/2k+1/2l+1/2) lattice fringes were found. Similar features were found in the PZN perovskite monocrystal, leading to the conclusion that local 11 ordering of cations (presumably Zn²⁺ and Nb⁵⁺) in the PFN-PFW-PZN system caused partial decomposition of the perovskite phase at firing temperatures equal to or higher than 850 °C.     

Basic studies of the corrosion of SiC by silicate melts

Three different commercially available SiC materials (one SiSiC and two sintered SSiC) and single crystals of -SiC were corroded at 1000 °C by silicate melts based on Na₂O-2SiO₂ with different additives of Al₂O₃, CaO, Fe₂O₃ and TiO₂. During the corrosion experiments the samples were completely immersed in the melts. Parts of the samples were subsequently leached in H F for weight loss determination and surface change examinations, and other parts of them were prepared as polished cross-sections for SEM-EDXS investigations of SiC-melt interfaces. Corrosion starts by dissolution of a silicon dioxide layer in the silicate melt followed by oxidation of the free silicon phase, and silicon carbide phase, and grain boundary attack. Corrosive attack and corrosion mechanisms are dependent on the composition and structure of the silicon carbide material. An influence of Fe, Al, Ca and Ti addition on the extent of corrosion was observed. In the vicinity of SiC-melt interfaces SiO₂-rich melt regions were found. The unusually high corrosion rate of SiC samples in the case of Fe₂O₃ addition to sodium disilicate was concluded to be the consequence of Fe²⁺-Fe³⁺ transition. Some defects in materials which were introduced during manufacturing or machining corroded much more severely than the defect-free material.On leave from J. Stefan Institute, Ljubljana, Slovenia.     

The impact of education and cooking methods on serum phosphate levels in patients on hemodialysis: 1‐year study

Introduction: Control of serum phosphate is important for patients on hemodialysis. The aim of the study was to determine if education based on phosphorus‐reducing techniques in food preparation and thermal processing, and accordingly prepared and applied diets, will lead to better outcomes than a standard education program to improve phosphate control in patients on hemodialysis. Methods: Forty‐seven patients on hemodialysis were divided between an intervention and a control group. All subjects received training about nutrition for hemodialysis patients by trained dietitian. In addition, subjects in the intervention group received additional training in phosphorus‐reducing techniques in food preparation and received two hospital meals prepared using suggested cooking methods to reduce the phosphate content of food during dialysis treatment. Serum phosphate, serum albumin, and anthropometric parameters were measured, while nPCR was calculated, at the baseline and during the 1‐year study. Findings: No differences in serum phosphate levels were observed between intervention (1.68 mmol/L [1.48–2.03]) and control group (1.88 mmol/L [1.57–2.2]) at baseline (P = 0.130). Although not statistically significant between groups the mean reduction was more apparent in the intervention group (?0.3 mmol/L (?0.4 to 0.1) vs. ?0.2 (?0.5 to 0.1)), and lead to significantly reduction of phosphate binder therapy. During the study, the nPCR and anthropometric status of the patients did not change significantly. Discussion: Providing additional education to hemodialysis patients on the specific cooking methods and accordingly prepared meals may decrease serum phosphate levels without significantly affecting nutritional status which may be useful in helping to prevent and treat hyperphosphatemia.     

Development and characterisation of functional cocoa (Theobroma cacao L.)-based edible films

The aim of this study was to develop functional edible films containing cocoa (Theobroma cacao L.) powder extract using alginate, pectin and chitosan in combination with proteins (whey protein isolate, soya and hemp protein). The films were examined for their physico-chemical (dry matter content, colour, thickness), mechanical (elongation at break (EAB)), bioactive (the content of total polyphenols (TPC), flavan-3-ols (F3olC), antioxidant capacity (AC)) and sensory properties. The plain alginate film exhibited the highest EAB (29.1%). The highest TPC and F3olC were determined in plain alginate (29 mg GAE/g and 2.75 mg (+)-catechin/g) and pectin (29 mg GAE/g and 2.25 mg (+)-catechin/g) films. The addition of proteins resulted in prolonged release of polyphenols and enhanced functional properties; however, the formation of protein–polyphenol complexes caused slight alterations in the bioactive composition of the films. The obtained results indicate a high potential of the developed films as functional, biodegradable form of active food packaging.     

Carbon air electrode with regenerative short time overload capacity. II. Effects of duroquinone and 2-amino-1.4 naphthoquinone

The short time overload capacity of the carbon-air electrode in a strongly alkaline electrolyte can be increased by addition of organic redox substances such as duroquinone (DQ) or 2-amino-1.4-naphthoquinone (ANQ). DQ, however, slowly decomposes in alkalies, while ANQ is quite stable even in 9M KOH. Small amounts of both quinones have a catalytic effect on the oxygen reduction at the carbon-air electrode.