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Vascular toxicity induced by xenobiotics is associated with dysfunctions or damage to endothelial cells, changes in vascular permeability or dysregulation of the vascular redox state. The aim of this study was to determine whether per os administration of zearalenone (ZEN) influences selected hemostatic parameters in prepubertal gilts. This study was performed on female gilts divided into a control group which received placebo and an experimental group which received ZEN at a dose of 5.0 µg·kg−1 b.w. × day−1. On days 14, 28 and 42, blood samples were collected from the animals for analyses of hematological, coagulation and fibrinolysis parameters, nitric oxide, von Willebrand factor antigen content and catalase activity. The results demonstrated that the treatment of gilts with ZEN at a dose below no observable adverse effect level did not affect the primary hemostasis and the blood coagulation cascade. However, ZEN could have temporarily affected the selected indicators of endothelial cell function (increase of von Willebrand factor, decrease of nitric oxide levels) and the oxidative status plasma (decrease of catalase activity) of the exposed gilts. In summary, these results suggest that the adaptive response to ZEN-exposure can induce a transient imbalance in the vascular system by acting on vascular endothelial cells.

Bisphenol A, a substance commonly used in plastic manufacturing, is relatively well known as an endocrine disruptor, which may bind to estrogen receptors and has multidirectional negative effects on both human and animal organisms. Previous studies have reported that BPA may act on the reproductive organs, but knowledge concerning BPA-induced changes within the nerves located in the uterine wall is extremely scant. The aim of this study was to investigate the impact of various doses of BPA on the parasympathetic nerves located in the corpus and horns of the uterus using a single and double immunofluorescence method. The obtained results have shown that BPA may change not only the expression of vesicular acetylcholine transporter (VAChT-a marker of parasympathetic nervous structures) in the uterine intramural nerve fibers, but also the degree of colocalization of this substance with other neuronal factors, including substance P (SP), vasoactive intestinal polypeptide (VIP), galanin (GAL), and calcitonin gene-related peptide (CGRP). Moreover, BPA caused changes in the density of the overall populations of fibers immunoreactive to the particular neuropeptides mentioned above. The characteristics of the changes clearly depended on the part of the uterus, the neuronal factors studied, and the dosage of BPA. The mechanisms of the observed fluctuations are probably connected with the neurotoxic and/or pro-inflammatory activity of BPA. Moreover, the results have shown that even low doses of BPA are not neutral to living organisms. Changes in the neurochemical characterization of nerves supplying the uterine wall may be the first subclinical sign of intoxication with this substance.

Reaching environmental targets set by the European Union (EU) requires a constant renovation of the existing building stock to nearly Zero Energy Buildings (NZEB) in a cost-optimal manner. Studies show that the renovation rate of the existing building stock is more than two times less than what is necessary to reach the targets. Furthermore, the majority of performed renovations across the EU reach just a small amount of energy savings, whereas NZEB renovations are rarely achieved. This paper proposes a methodology for the evaluation of renovation measures, aiming to provide decision support related to the selection of what to renovate and to what extent. The proposed method is rooted in the well-established cost-optimal methodology, yet it suggests a pre-step to package evaluation. This is done by means of a simplified cost-effective parameter (CEP), linking cost, lifetime, and energy savings. The methodology is demonstrated using a case study building in Denmark. The results show that the CEP provides good grounds for the compilation of single actions to packages. Further developments could focus on the sensitivity of the model inputs and integration of additional evaluation parameters to cost, such as environmental, architectural, comfort, risk, etc.

The aim of the study was to determine the effect of repeated hot thermal stress and cold water immersion on the endocrine system of young adult men with moderate and high levels of physical activity (PA). The research was conducted on 30 men aged 19–26 years (mean: 22.67 ± 2.02) who attended four sauna sessions of 12 min each (temperature: 90−91°C; relative humidity: 14–16 %). Each sauna session was followed by a 6-min cool-down break during which the participants were immersed in cold water (10−11°C) for 1 min. Testosterone (TES), cortisol (COR), dehydroepiandrosterone sulfate (DHEA-S), and prolactin (PRL) levels were measured before and after the sauna bath. The participants’ PA levels were evaluated using the International Physical Activity Questionnaire. Serum COR levels decreased significantly ( p < .001) from 13.61 to 9.67 µg/ml during 72 min of sauna treatment. No significant changes ( p >.05) were noted in the concentrations of the remaining hormones: TES increased from 4.04 to 4.24 ng/ml, DHEA-S decreased from 357.5 to 356.82 µg/ml, and PRL decreased from 14.50 to 13.71 ng/ml. After sauna, a greater decrease in COR concentrations was observed in males with higher baseline COR levels, whereas only a minor decrease was noted in participants with very low baseline COR values ( r =−0.673, p

Marine fish are a good source of unsaturated fatty acids, high nutritional value protein, vitamins and minerals. Baltic herring is one of the most frequently caught fish in Poland(1). It was demonstrated that the fishing season has an effect on the content of individual fatty acid fractions(2).The aim of the study was to analyse the fatty acid profile of Baltic herring flaps originating from two fishing seasons.The study material were flaps of Baltic herring (Clupea harengus) originating from two fishing seasons (April-June following spawning and October-December prior to spawning). For each fishing season, six batches of raw material were examined (n = 6). From each batch, flaps were taken from ten fish. The flaps were comminuted and thoroughly mixed to prepare an experimental sample from which adequate weights of analytical samples were taken. The quantitative and qualitative analysis of the fatty acid composition was conducted following the cold muscle lipid extraction with a mixture of chloroform : methanol (2:1). Fatty acid methylation was carried out with a chloroform : methanol : sulphuric acid mixture (100:100:1). The separation of fatty acids was performed by gas chromatography. A one-factor variance analysis method with Duncan's test (P ≤ 0.05) was used to evaluate the variation of mean values.The fishing season does not significantly affect the content of saturated and unsaturated fatty acids. Differences were found during the analysis of the individual groups of unsaturated acids. The amount of monounsaturated fatty acids in herring before spawning (25.27%) was significantly lower than that after spawning (35.91%) (P ≤ 0.05). The content of polyunsaturated fatty acids before spawning (43.99%) was significantly higher than that after spawning (33.49%) (P ≤ 0.05). Most changes in the fatty acid profile occur in the highly unsaturated fatty acids (HUFA). The most important change due to the health-promoting properties for humans is an increase in the amount of EPA from 6.24% to 9.84% after and before spawning, respectively. Analogous changes were demonstrated for DHA, whose amount increased from 9.64% to 24.56%. The obtained results demonstrate a more favourable fatty acid profile in herring caught before spawning.

Meat semi-finished products that are portioned or not, meat with the addition of a different composition of spices and oil are a common element of the commercial offer in the convenient ready to cook food segment. During the refrigeration storage in this complex system of meat, oil and spices, there is a number of physicochemical changes, including hydrolytic and oxidative changes of the oil(1). The products of these reactions become integral components of the meat subjected to heat treatment. As a result of heating, secondary oxidation products of lipids may be formed which constitute a serious health risk(2). The study was aimed at determination of the effect of spices containing antioxidants and sulfur-organic compounds on hydrolytic and oxidative changes in the oil that formed the base of the marinade in which meat was kept. Pork neck was minced and formed into burgers (250 g), rapeseed oil (120 g) and spices (5 g) were used. Four research groups were analyzed meat / oil / spices system with rosemary, oregano, garlic or onion. Oil samples were collected on the third, fifth and eighth day of refrigerated storage. The control sample was the oil from the meat / oil system only. The quality of the oil was evaluated on the basis of the acid value, peroxide value and TBARS index. In the oil with onion, garlic, rosemary and oregano the hydrolytic changes on the 8th day of storage were significantly lower compared to the control. On the basis of the average peroxide value in oil marinades with the addition of rosemary and oregano, significantly lower values of this indicator were found when using rosemary (3.61 meq O2/kg) in comparison with oregano (6.01 meq O2/kg). The average of TBARS index in marinade with onions and garlic was lower by 31% and 48%, respectively. Also the use of rosemary and oregano was effective in blocking the formation of secondary oxidation products (rosemary even three times higher than that of oregano).

Among the poultry species, goose meat is relatively hard and cohesive and characterised by the highest chewiness and gumminess. Therefore, it can be assumed that goose meat ageing can improve its quality(1,2).The aim of the study was to determine the effect of ageing time of goose breast muscle on selected technological properties.The study material consisted musclus pectoralis of Polish White Kołuda oat geese, slaughtered at 15–17 weeks of age, weighing 6–7 kg. After slaughter, carcasses were cooled and breast muscles were cut out, vacuum packed and stored at 4°C ± 1°C. Analyses were performed 1, 7, 14, 21 days post mortem on eight breast muscles on each of the days (n = 8).The following parameters were determined: pH, muscle surface and cross-section colour, natural drip, free water, water absorption, thermal drip and shear force. A one-factor variance analysis method with Duncan's test (P ≤ 0.05) was used to evaluate the variation of mean values.It was demonstrated that muscle pH increases with an increase in the cool storage period. This parameter considerably increased from day 14 of ageing. Muscle colour changes were observed only on its surface between day 1 and 21. The ageing period had an effect on the meat hydration properties. Natural drip volume increased with an increase in the storage period and corresponded with the free water volume. A significantly greater volume of natural drip (1.77%) and a lower volume of free water (8.98%) were observed on day 21. Water absorption significantly increased on day 7 of ageing and remained constant until the end of the ageing time. A similar relationship was found while evaluating the shear force. A rapid drop in shear force was observed, which reflected an increase in meat tenderness by almost 5N between day 1 and 7 of the experiment. Based on the results, it can be concluded that the analysed raw material featured the most favourable technological properties on day 7 of ageing and that an extension of the ageing process was unjustified.

This paper investigates moisture related performance of a regenerator heat exchanger located in a decentralized ventilation unit for residential building application. The decentralized ventilation solutions have recently become a more and more popular alternative to centralized ventilation systems. Due to the small space available and in order to avoid maintenance of these types of units, they are equipped with regenerator heat exchanger in some cases. In the recent past and also presently, Building Regulations (BR) and European directives have increased demands for heat recovery efficiency in air handling units (AHUs). In the case of regenerator heat exchanger, the higher the heat recovery efficiency obtained the higher risk that condensation might occur. This condensation might form small droplets on the surface of the regenerator that might not be possible to drain in the short switching time of the regenerator and consequently might be evaporated in the next cycle back to the building and cause elevated humidity conditions in the indoor spaces. Due to the fact that the traditionally used dilution equation must not be used to solve moisture balance in the room with regenerator heat exchanger and infiltration, this paper presents a new calculation methodology that takes into account infiltration, condensation in the regenerator, and back evaporation to the room. The paper compares humidity levels in the room ventilated with regenerator heat exchanger and ordinary counter-flow exchanger. Theoretical calculations indicate that the ability of a ventilation system with regenerator to remove moisture from the room is very dependent on moisture loads in the room, air change rate, and infiltration rate.

Zearalenone (ZEN) widely contaminates animal feed of plant origin. The recommended safe concentrations of ZEN in feeds for various animal species are set mainly based on the mycotoxin’s hormonal properties (NOEL). Our growing knowledge about biologically active concentrations of ZEN, molecular mechanisms and cells/tissues targeted by ZEN indicates that the harmful effects exerted by this mycotoxin on animals may be far greater than previously believed. This experiment was performed on pre-pubertal gilts divided into a control group (n=9) and an experimental group (ZEN, n=9). The control group received placebo, whereas the experimental group was administered ZEN at a dose of 0.1 mg/kg feed (equivalent to 5 μg/kg BW/day) for 42 days. On days 14, 28 and 42 blood samples were collected from the animals to determine the concentrations of selected zearalenols, serum biochemical and haematological parameters. Conjugated ZEN was found in the blood serum of the experimental gilts. Changes in the analysed biochemical parameters included a transient increase in albumin and cholesterol levels. A statistically significant increase in the concentrations of neutrophilic and acidophilic granulocytes was observed in the white blood cell system. The results indicate that long-term per os exposure of pre-pubertal gilts to low doses of ZEN (below NOEL) has a modulatory effect on liver function and white blood cells.

This study evaluated the effect of dietary organic and inorganic selenium supplementation on chemical, mineral and fatty acid composition of ostrich meat. Forty ostriches were raised in two groups (OSe and IOSe, diets supplemented with an organic form and an inorganic form of selenium, respectively). The form of selenium had no influence on chemical composition of ostrich muscle. Although, there were no significant differences in total content of SFA, MUFA and PUFA, the content of LA and EPA was higher in the muscles of ostriches which were put on a diet supplemented with an organic form of selenium, what resulted in lower n-6/n-3 fatty acids ratio in OSe group (9.99) in comparison to IOSe group (11.70). The results of the study indicate that dietary organic selenium supplementation improves the quality of the ostrich meat as related to the health promoting properties (LA, EPA and selenium content) of meat.

Electroretinography (ERG) in the form of full-field, flash ERG is the most commonly used technique in veterinary ophthalmology for diagnosing the functioning of the outer retina. Under light stimulation spatially distributed different cell types within the retina produce time-varying electric responses. These are recorded in the form of ERG traces consisting of a series of positive and negative wavelets. The possibility of selective stimulation of individual types of retinal cells and the analysis of constituent components of ERGs are the basis for determining the source of abnormalities and diagnosis of various types of dysfunction. In many cases, the ERG allows diagnosis of hereditary retinal disorders in dogs before the appearance of behavioural and ophthalmoscopic symptoms. This review is an introduction to the electrophysiology of vision, intended for small animal practitioners, and aimed at presenting the benefits of ERG for early ophthalmic diagnostics in dogs.

Surface pressure vs. concentration, π − c, and electric surface potential, ΔV − c, isotherms at free surface of aqueous solutions of selected amphiphiles were analyzed with respect to (i) size of the head group, (ii) length of paraffinic chain and (iii) presence of branched chain of the comparable number of C atoms. The Frumkin isotherm was fitted to the measured π − c dependencies and the results were examined as a function of concentration normalized with respect to the concentration of the half surface coverage, cn = c/cΘ/2, derived from the best fit Frumkin parameters. The largest variation in shape of the π vs. cn isotherms was found between amphiphiles possessing different head groups substituted with comparable paraffin chains (C8–C9). Their isotherms in the high coverage region (Θ > 50%) exhibited notably diverse slopes, dπ/d log cn, indicating significantly different surface excess of the amphiphiles. The minimum “cross-sectional areas” calculated from the fitted parameter Γ∞, as Amin = 1/NΓ∞, are slightly higher than the hard-core cross-sectional area of the most bulky part of free molecule which indicates a residual hydration of the saturated monolayers. The identical value of Amin = 27.7 A2/molec. found for the n-alkanols series (C4–C9) is significantly greater than minimum cross-section area of hard core of the fully extended chain, ca. 21.3 A2. On the other hand, the Amin area found for glucopyranosides (ca. 45 A2/molec.) correlates with smaller cross-section of the “ellipsoidal” head group (ca. 40 A2), suggesting its nearly perpendicular inclination to the interface plane in the saturated monolayer. The normalized electric surface potential isotherms, ΔV/ΔVmax vs. cn, deviate from the Frumkin Θ − cn dependencies, in particular, in the higher coverage range, Θ > 50%, which implies change of the effective dipole moment, μ⊥, and/or the local permittivity, ɛs, with Θ.

The objective of this study was to determine the effect of diets with a different n-6/n-3 PUFAs ratio (7.31, 4.43, and 0.99), resulting from the addition of different dietary oils: soybean, rapeseed, and linseed (diets S, R, and L, respectively), on the fatty acid (FA) profile, oxidative status, and sensory properties of turkey breast meat. After 15 wk of feeding, breast meat yield and chemical properties of the meat were similar in all groups. Raw breast meat of R turkeys had a significantly higher content of all-trans-retinol and atocopherol, compared with S and L. The physicochemical properties of breast meat, including pH, color, drip loss, and cooking loss, did not differ significantly. Cooked meat samples differed significantly with respect to the concentrations of oleic acid, linoleic acid (S and R>L), and linolenic acid (S and R

The aim of this study was to estimate changes in selected biochemical indicators during nutritional muscular dystrophy of calves and to use electrocardiography technique in early diagnosis of this disease. The study was performed on 24 Holstein-Friesian calves of both sexes, divided into two groups. The first one was experimental group of 12 calves with symptoms of nutritional muscular dystrophy and the second one was control group of 12 clinically healthy calves administered a single i.m. injection of vitamin E + selenium preparation on the second day after birth. Blood samples were collected from all animals 3 × at 7-day intervals, starting on day 5. Blood serum was subjected to biochemical analyses to determine Se and vitamin E concentrations, aspartate aminotransferase, creatine kinase and lactate dehydrogenase activity levels. The activity of glutathione peroxidase was determined in whole blood samples. Electrocardiographic assessment was performed on day 19 in all calves. In the group of calves with symptoms of nutritional muscular dystrophy, serum Se and vitamin E concentrations were significantly (P ≤ 0.01) lower than in control, the same was true for the activity of glutathione peroxidase (P ≤ 0.01). The changes were accompanied by an increase (P ≤ 0.01) in the activity of aspartate aminotransferase, creatine kinase and lactate dehydrogenase. The electrocardiograms of experimental animals revealed elevated heart rate, accelerated sinus rhythm, increased P wave amplitude, shorter PR, QT and ST interval, narrower QRS complex, shorter T wave duration and insignificantly increased T wave amplitude; these results were indicative of arrhythmia which is observed at early stages of cardiomyopathy. This study is the first one in which electrocardiography technique was used to diagnose nutritional muscular dystrophy in calves. Cattle, selenium deficiency, biochemistry, arrhythmia Selenium is a bio-element that plays a very important role in higher organisms. Selenium is nutritionally related to vitamin E and sulphur amino acids. Selenium and vitamin E deficiencies may lead to nutritional muscular dystrophy (NMD), also known as white muscle disease. The disorder affects lambs, foals, goatlings, calves and piglets, and is less frequently observed in mature animals. The disease involves hyaline degeneration of muscle cells in various skeletal muscles, including the diaphragm and the heart. In most calves, the disease appears at the age of 4–6 weeks. There are three main forms of nutritional muscular dystrophy: peracute, acute and subacute. The peracute form of the disease affects mainly the heart muscle of newborn calves. It is accompanied by arrhythmia, increased heart rate, weaker pulse, acute dyspnoea at rest, blue coloring of the mucosa and great breathing difficulty. In its acute form, the disease affects skeletal and intercostal muscles, the diaphragm and the heart. Calves have incorrect posture with widely spread limbs, hunched up back, neck extended forward with limited ability to move. In calves the subacute form of nutritional muscular dystrophy is most frequently encountered. The animals have

The effect of partial or complete substitution (2.5% and 5%, respectively) of flaxseed oil for soybean oil on the fatty acid profile, oxidative stability and sensory quality of turkey breast meat was studied. Turkeys were fed experimental diets for 3, 4, 5 or 6 weeks before being slaughtered at 16 weeks of age. The percentages of α-linolenic acid and eicosapentaenoic acid in the total fatty acid pool of meat were determined by dietary intake and feeding duration. Even a prolonged dietary treatment with 5% flaxseed oil did not significantly increase the thiobarbituric acid reactive substances content of the turkey meat and did not have a detrimental effect on the sensory properties. The recommended n-6 : n-3 polyunsaturated fatty acids ratio (

We have previously demonstrated that hexanoyl-D-erythro-sphingosine (C(6)-ceramide), an anti-mitogenic cell-permeable lipid metabolite, limited vascular smooth muscle growth by abrogating trauma-induced Akt activity in a stretch injury model of neointimal hyperplasia. Furthermore, ceramide selectively and directly activated protein kinase C zeta (PKC zeta) to suppress Akt-dependent mitogenesis. To further analyze the interaction between ceramide and PKC zeta, the ability of ceramide to localize within highly structured lipid microdomains (rafts) and activate PKC zeta was investigated. Using rat aorta vascular smooth muscle cells (A7r5), we now demonstrate that C(6)-ceramide treatment results in an increased localization and phosphorylation of PKC zeta within caveolin-enriched lipid microdomians to inactivate Akt. In addition, ceramide specifically reduced the association of PKC zeta with 14-3-3, a scaffold protein localized to less structured regions within membranes. Pharmacological disruption of highly structured lipid microdomains resulted in abrogation of ceramide-activated, PKC zeta-dependent Akt inactivation, whereas molecular strategies suggest that ceramide-dependent PKC zeta phosphorylation of Akt3 at Ser(34) was necessary for ceramide-induced vascular smooth muscle cell growth arrest. Taken together, these data demonstrate that structured membrane microdomains are necessary for ceramide-induced activation of PKC zeta and resultant diminished Akt activity, leading to vascular smooth muscle cell growth arrest.

The objective of the present research was to investigate the influence of chemical modification and method of preservation of separated myofibrillar proteins on their physico-chemical properties. Myofibrillar proteins were the subject to succinylation or acylation and after modification one part of each preparation was lyophilised, the second part was spray dried and the third part was frozen. The chemical composition of protein preparations did not change significantly after any method of treatment. The process of chemical modification influenced the water-holding capacity and protein digestibility in vitro. Modified samples absorbed less water than standards and also were less susceptible to enzymatic hydrolysis. The shape of sorption isotherms of modified proteins was typical for hygroscopic products and hysteresis loops were observed.

Owing to its high protein and low fat content, turkey meat is regarded as dietetic. It also has a beneficial composition in terms of amino acid and mineral content. The study involved an analysis of selected elements: zinc, magnesium, calcium, sodium, potassium and phosphorus in breast muscles of male turkeys BIG 6 fed on fodder with various content of oatmeal (0%; 5% and 10%). The content of selected elements was determined in previously mineralised samples: zinc, magnesium and calcium – by AAS, using a UNICAM 939AAA Solar flame atomic absorption spectrometer; sodium and potassium – by flame photometry with a Carl Zeiss Jena FLAPHO 4 flame photometer, and phosphorus – by colorimetric measurement with the hydroquinone reagent at a wavelength of 610 nm. The results were processed with a single-factor analysis of variance with the Statistica 8pl computer program, and the significance of differences was determined with Duncan’s test. Oatmeal application in the analysed doses in turkey feeding has been shown to reduce the content of the elements under study in turkey meat. The differences for the analysed elements have not been shown to be statistically significant (P = 0.05), except for sodium, whose content – unlike that of other elements – grew with the oatmeal content in the fodder

Two muscles, breast and thigh, were excised from 3 pigeon meat-type breeds (Europigeon, Wroclawski, King) and were analyzed for proximate analysis, cholesterol content, and fatty acid (FA) profile. Among the breeds considered, the lowest protein content of breast muscle was found in Kings (21.73%), whereas the highest fat (7.07%) and ash (1.11%) content of breast muscle (P

Influence of frothers (α-terpineol or n-amyl alcohol) on the floatability of chalcocite and quartz mixtures, with potassium ethyl xanthate as a collector at pH 5.5–6, was investigated with a Hallimond tube. Activation of quartz by the presence of chalcocite was observed and interpreted as due to copper ionic species originating from chalcocite oxidation products. Best selectivity of separation between chalcocite and quartz was obtained when the frother concentration was kept sufficiently low. Collector—frother interactions during formation of three-phase mineral grain/solution/gas bubble contacts were observed.

The results of potassium ethyl xanthate (EtXK) consumption measurements by synthetic chalcocite (Cu 2 S grain-sized classes of 60–75 μm and 120–200 μm, respectively) are presented. These measurements were done in a modified circulation apparatus in an argon or oxygen atmosphere at pH=9.5. The experimental results were compared with theoretical results predicted by a mathematical model based on the assumption that the EtX − ions were immobilized as a result of a chemical reaction (or reactions), e.g., of an ion-exchange type, taking place within the oxidation product layer (OPL), formed on the Cu 2 S surface. The experimental and theoretical results are in good agreement especially for small values of Q 0 ( Q 0 is the initial mass of the EtX − in solution per mass unit of Cu 2 S). In this case both the theoretical and experimental results show that the EtX − concentration in solution decays exponentially with time.

The results obtained from measurements of potassium ethyl xanthate (EtXK) sorption by synthetic chalcocite (Cu 2 S) and the results of chalcocite floatability measurements are presented. Five chalcocite samples, denoted as Cu 2 S A, B, C, D and E, were used for the measurements. Chalcocite samples of 60–75 μm were prepared in the same manner but were kept under conditions which differed in their degree to prevent surface oxidation by atmospheric oxygen. Chalcocite surface oxidation has a strong effect both on xanthate sorption and on chalcocite floatability. The maximal amount of xanthate abstracted ( Q max ) by chalcocite samples from deoxygenated solutions after a long sorption period increases with increasing oxidation of the samples. The Q max values give information concerning the total amount of surface oxidation products. Chalcocite decreases its floatability with increasing surface oxidation. Most oxidized chalcocite samples required an about 100 times greater collector consumption to obtain the same flotation results than the least-oxidized samples studied.

The method of the deposition kinetic measurements of very fine particles (size 0.1 – 5 μm) under well-defined hydrodynamic flow conditions has been presented. The proposed method, based on the rotating disc principle, enables direct and quantitative determination of the particle coating density by means of microscope counts. Our method is a modification of the method previously described by Marshall and Kitchener [12], Hull and Kitchener [10] and Clint et al. [5], used by them for measurements of colloid particle interaction with smooth surfaces. The experimental apparatus has been briefly described and the results of the particle deposition rate measurements from CaCO 3 and BaSO 4 suspensions (average particle diameters were 1.25 and 0.86 μm, respectively) onto glass and Cu 2 S disc surfaces have been presented. The influence of such parameters as deposition time, suspension concentration, disc angular velocity, particle densities, and additions of dispersing agents on the particle deposition kinetics has been discussed. The experimental results have been compared with our previous theoretical predictions and a satisfactory conformability has been found, at least for dilute and stable suspensions.

The interfacial impedance of non-stoichiometric cuprous sulphide electrodes in solutions of indifferent electrolytes was measured in order to study the electrical double layer (e.d.l.) at the sulphide-aqueous solution interface. A significaint dispersion of impedance components was observed, which was ascribed to the influence of roughness and inhomogeneity of the surface. The measured capacitive part of the impedance is influenced both by the solution side and by the solid-body side of the e.d.l.

The surface tension of aqueous solutions of 2-alkyl- 1,3-dioxolanes (alkyl: CH3 … n-C6H13) as well as their adsorption at the aqueous solution-mercury interface have been measured over a wide range of concentrations. The investigated alkyldioxolanes fit the Traube rule. From the log c vs hydrocarbon chain length plots (for a constant surface tension of aqueous solutions equal to 55 mN m−1) it is evident that the studied alkyldioxolanes have a higher surface activity than aliphatic alcohols, alkyl monoethers of ethylene glycol, and 1,2-diols with the same hydrocarbon chain length. The effective length of the hydrocarbon chain in alkyldioxolanes is shorter by 1.5, 1.0, and 3.0-CH2-groups as compared with that in aliphatic alcohols, alkyl monoethers of ethylene glycol, and 1,2-diols, respectively. The surface activity of studied compounds at the aqueous solution—mercury interface is higher by 2.5-CH2-groups as compared with corresponding aliphatic alcohols. The change of standard free energy of adsorption per methylene group in hydrocarbon chain for the water-air interface, −Δ G° CH 2 , as determined by Temkin's isotherm equation is 2.4 kJ mole−1 this value is lower than that for aliphatic alcohols. At the aqueous solution-mercury interface the −Δ G° CH 2 value calculated from both Temkin's and Frumkin's equations is equal to 3.5 kJ mole−1 and corresponds to the value for aliphatic alcohols determined by other authors. From the values of surface area per molecule at the water-air interface calculated using the simple form of Gibbs' equation one may conclude that the 1,3-dioxolane ring is oriented parallel to this interface.

The role of individual foam films in the stabilization of steady-state foams (froths) obtained under dynamic conditions was studied. n -Amyl alcohol (AmOH) was chosen as the frothing agent. It was assumed that the stability of such foams is determined by the stability of the bubbles in the top layer, because the liquid content in the foam volume is high and the gas bubbles do not contact one another. The role of the foam films was found through parallel investigations of steady-state foams, single foam films, and foam bubbles at the surface of a solution at appropriately chosen geometrical parameters and at the same composition of the solution. The results showed that the bubbles in the surface layer of the stationary froths rupture at relatively large thickness (larger than 300 nm) where the specific thermodynamic and kinetic properties of the foam films are not yet operative.

The temperature dependence of the equilibrium constant of the formation of ammonium sulphite from SO2, NH3, and H2O given by theoretical equation derived by Wolfkowitsch and Zirlin has been confirmed by calculations based on the accessible experimental data. Substitution of SO2 by CO2 in solid ammonium sulphite can take place when partial pressure of CO2 exceeds at least 104 times that of SO2. Untersuchungen uber die Kinetik und den Mechanismus der Bindung von Schwefeldioxid und von Stickoxiden durch gasformiges Ammoniak. II. Thermodynamische Gleichgewichte im System SO2, NH3, H2O und CO2 Die Abhangigkeit der Gleichgewichtskonstanten der Ammoniumsulfitbildung aus SO2, NH3 und H2O von der Temperature, die mit der von Wolfkowitsch und Zirlin theoretisch abgeleiteten Gleichung berechnet wurde, konnte durch Auswertung experimenteller Daten bestatigt werden. SO2 kann im festen Ammoniumsulfit durch CO2 ersetzt werden falls der Partialdruck von CO2 mindestens 104mal groser ist als der Partialdruck von SO2.

The modification of a Hallimond tube enabling flotation of very fine particles at low recovery by mechanical entrainment is described. Flotation yields of closely sized fractions of quartz and chalcocite are presented.

The flotation and adsorption properties of two ionic collectors (n-dodecylamine andn-dodecanoic acid) are compared on the bases of results of mercury flotation in the model flotation apparatus and electrochemical measurements of the double layer capacity.

The flotation and sorption properties of chalcocite and quartz in potassium ethyl xanthate (EtXK), frothers (α-terpineol and n-amyl alcohol), and (xanthate + frother) mixed solutions were investigated. Surface tension and frothing properties of the solutions were also measured. Floatability and sorption properties of the minerals investigated strongly depended on any controlled or uncontrolled change occurring at the mineral surface. Surface oxidation of chalcocite was shown to be an especially important parameter. The frothers studied showed some collecting properties in respect to chalcocite and quartz and influenced the xanthate sorption on chalcocite. Comparison of the flotation recoveries in frother solutions respectively with and without xanthate indicated an occurrence of noticeable collector-frother interactions during formation of the bubble/chalcocite grain aggregate. No such interactions were found for quartz. Influence of the frothers on floatability of the minerals was observed at different frother concentrations but at close values of surface pressure (π) and of retention time (rt).

The results obtained in earlier potential measurements at galena electrodes under various experimental conditions and measurements of local potentials on polished mineral plates of natural galena and copper sulphide specimens shown the presence of corrosive micro-cells on the mineral surface. The measured local potentials had a mixed potential character. The results obtained seemed to agree with the following electrochemical scheme of reactions involving xanthate ion (X−) reactions with the freshly ground sulphide mineral in an aerated water suspension. The fast surface reaction of binding of xanthate ions 2X − + H 2 O + 1 2 O 2 + srufac → 2 X-surface + 20 H − can be followed by a slow formation of metal xanthate (MeX) as a bulk product 2 2X−surface + Me 2 S → S 0 − surface + 2 MeX(bulk) The formation of excess elementary sulphur at the surface (S0-surface) must be balanced by a slow diffusion of metal ions in the crystal lattice, changing the character and number of lattice defects in the mineral.

Es wurde festgestellt, das in Abhangigkeit von den Partialdrucken von SO2, H2O und NH3 in der Gasphase verschiedene feste Produkte gebildet werden. Bevorzugt ist dabei Bildung des Produktes, das moglichst kleine Mengen der im Unterschus vorhandenen Substanz enthalt. Die experimentell ermittelten Grenzwerte der Stabilitat fester Substanzen bestatigten die Ergebnisse fruher durchgefuhrter thermodynamischer Berechnungen. Bedingungen, unter welchen die Stickoxide vom Ammoniak am effektivsten gebunden werden, wurden bestimmt. Studies on Kinetics and Mechanism of the Reaction of Sulphur Dioxide and Nitrogen Oxides with Gaseous Ammonia It was found that depending on the partial pressure of SO2, H2O, and NH3 different solid products were formed. Formation of the product containing the smallest amount of the substrate of the lowest partial pressure is favoured. The measured stability limits of the solid products confirmed the former thermodynamic calculations. The conditions for effective binding of NOx with ammonia were established.

Es wurde ein Schema der im System H2O, SO2, NOX und NH3 verlaufenden Reaktionen vorgeschlagen, und das angenommene Modell ist experimentell bestatigt worden. Wasserdampf beeinflust den Verlauf der Reaktionen im untersuchten System stark. In Anwesenheit von Wasserdampf verlaufen die Reaktionen schneller, und der erreichte Umsetzungsgrad ist bedeutend groser als im Falle trockener Gasgemische. In Anwesenheit von Wasserdampf und NOX wird das SO2 oxydiert, so das nach Einfuhrung des Ammoniaks das bestandige Ammoniumsulfat als festes Reaktionsprodukt gebildet wird. Studies on Kinetics and Mechanism of the Reaction of Sulphur Dioxide and Nitrogen Oxides with Gaseous Ammonia. III. Influence of Water Vapour on the Kinetics and the Mechanism of the Reaction The scheme of the reactions in the system H2O, SO2, NOX, NH3 has been proposed and experimentally confirmed. Water vapour strongly influenced the course of reactions in the above system, the reactions proceeded faster and their yields were much greater than those in the mixture of dry gases. In the presence of nitrogen oxides and water vapour the oxidation of sulphur dioxide occurs resulting in the formation of stable ammonium sulphate after the addition of ammonia.

When solutions of cupric perchlorate (10−6 to 10−2 M) are mixed with solutions containing nonequivalent quantities (concentrations) of xanthate (O-alkyl-dithiocarbonate) ions, clear solutions containing soluble nonionic and ionic complexes are obtained, despite the fact that the solubility product for a given metal xanthate salt may be exceeded by several orders of magnitude. Ultraviolet and visible (UV and VIS) spectroscopy, and dc and ac differential polarography have been employed to study these complex species. The spectral changes taking place on the addition of potassium ethyl xanthate to cupric perchlorate solutions, and also turbidity measurements, indicate that copper xanthate complexes are formed before the precipitation of cuprous ethyl xanthate, Cu(S2 COC 2 H 5). In very dilute solutions containing near equivalent concentrations of the reactants, a spectrum containing three broad maxima (235, 285, and 375 nm) is obtained and is interpreted as due to a nonionic cupric complex, Cu(S2 CO...

Xanthate solutions of pH 6–10, prepared from "aged" potassium ethyl xanthate crystals, KEtX, were investigated spectrophotometrically in the region 190–400 mμ and showed coexistence of xanthate ions, EtX−, dixanthogen, (EtX)2, and carbon disulphide, CS2. Optical density measurements on the spectra of dixanthogen solutions led to the evaluation of: molar absorptivities of dixanthogen at wavelengths corresponding to the two main bands in the xanthate ion spectrum, i.e. at 301 mμ—6130 liter/mole cm, and at 226 mμ—18,400 liter/mole cm; the solubility of dixanthogen, ca. 1.3 × 10−5 mole/liter; and the equilibrium constant, k = 3 × 1010, of the reaction 2(EtX)2 + 4OH− → 4EtX− + 2H2O + O2, for solutions saturated with air at atmospheric pressure. Simultaneous reactions leading to decomposition of xanthate and/or dixanthogen species to alcohol and carbon disulphide have been detected by a strong band at 206.5 mμ due to CS2 (with an estimated molar absorptivity of the order of 60,000–70,000 liter/mole cm).

Summary Electrooxidation of potassium ethyl xanthate in 0.1 M NaF has been studied by cyclic voltammetry on a natural copper sulphide electrode. The electrode submerged in 0.1 M NaF undergoes a corrosion process. Faradaic current, reaching 15 μA cm−2, recorded for the supporting electrolyte in the potential range from −540 to −140 mV vs. SCE, depends on the oxygen content of the solution. It equals zero at about −200 mV for oxygen-free solutions. Cyclic voltammograms obtained for 2–20×10−5 M EtXk solutions on copper sulphide were compared with those obtained on the mercury electrode. Adsorption prepeaks, connected with strong, two-step adsorption of xanthate ion oxidation products, leading to a surface coverage of about one monolayer, were found for both electrodes. The shift of the prepeak potential with respect to the potentials of the bulk product formation is a measure of the standard free energy changes of electrosorption of the xanthate oxidation process. Electrosorption of xanthate emphasizes the role of surface processesiin the binding of the flotation collector.

Mercury floatability was studied in model systems containing carboxylic acids (n-octanoic, n-nonanoic and n-dodecanoic), in 0.1 M KCl solutions of various pH. Surface pressure and three-phase contact angle on mercury were measured for solutions of octanoic and nonanoic acids at various pH. Contribution of neutral acid molecules and acid-soap complexes to the effective mercury floatability is discussed.

Mercury floatability in solutions of carboxylic acids (n octanoic, n-nonanoic and n-dodecanoic) of various pH (2–12), with and without addition of 0.1 M KCl, was studied in model flotation apparatus. Results were related to the size distribution of gas hubbies forming under standard conditions of flotation tests. High mercury floatability was obtained not only in solutions of good mercury hydrophobization but also at low mercury hydrophobization and optimal size of bubbles.Hence, this parameter should also be taken into account when correlations between various physicochemical properties of the system and flotation recovery are drawn.

The acidic decomposition of potassium ethylxanthate, butylxanthate and hexylxanthate was studied in micellar solutions of hexadecyl- tetradecyl- and dodecyl-trimethylammonium bromides and in micellar solutions of sodium dodecylfulfate. In micellar solutions of cationic surfactants the stabilization of alkylxanthates was observed. The same effect was found for potassium ethylxanthate in micellar solutions of the anionic surfactant. However, a catalysis of potassium hexylxanthate decomposition and the mixed effect /first inhibition, next catalysis/ of potassium butylxanthate decomposition were found. The results show the effects of electrostatic and dispersion forces. The posiibility of comicellization was considered and the quantitative analysis was started.