Amino acid uptake by the comatulid crinoid Cenometra bella (Echinodermata) following evisceration

Changes in the rates of utilization of dissolved compounds during the period of visceral mass regeneration were examined in the crinoid Cenometra bella (Hartlaub). Rates of respiraton and incorporation of labelled amino acids increase, reaching a maximum 2 d after evisceration and returning to normal after 14 d. Rates of incorporation of radioisotope into the organic components of the arms and cirri decrease, while incorporation rate into the visceral mass increases. Incorporation rates of amino acid-derived radioactivity into skeletal carbonate and the ash-free dry weight:protein ratio of arms, cirri and oral disc decrease, reaching a minimum 2 d following evisceration.     

Study of the spontaneous ignition of stoichiometric tetrafluoroethylene–air mixtures at elevated pressures

The Ignition Temperature (IT) of stoichiometric tetrafluoroethylene–air mixtures on hot walls was determined in a 3-dm³-reactor. Tests at elevated pressure conditions were performed, namely at 5, 15 and 25 bar(a), showing a decrease of the IT with the initial pressure. Furthermore, the measured ignition temperatures of stoichiometric tetrafluoroethylene–air mixtures were lower than the ignition temperatures required for the decomposition pure tetrafluoroethylene (Minimum Ignition Temperature of Decomposition, MITD) reported in previous works.Equations from the Semenov thermal explosion theory on spontaneous ignition were used to identify approximate combustion kinetics of tetrafluoroethylene from the experimental results. The determined kinetics was used for the prediction of the IT of stoichiometric tetrafluoroethylene-air by simplified calculation methods. A very good agreement with the experimental results was observed.     

Effects of Manual Handling,Posture, and Whole Body Vibrations on Low-Back Pain

To determine the effect of occupational stress on low-back pain (LBP), a cross-sectional study has been carried out, by interviews, on workers exposed to 3 stresses: manual handling (MH, 82 women and 264 men), whole body vibrations (WBV, 274 men), and static postures (278 women). Anthropometric data, occupational stress, LBP severity and frequency, and a psychological evaluation of these groups were compared to those of a control population of 208 workers (104 men and 104 women).

The results show that 30% of the population had never suffered from LBP. Age and the body mass index of the workers were the parameters most closely associated with LBP. Women involved in MH had higher frequency and severity of LBP than their reference population. Men involved in MH or exposed to WBV had higher frequency of painful episodes than their reference population. Workers exposed to one of the stresses were on sick leave for LBP more often, and for longer periods, than workers in the reference group. The results show that individual factors are often decisive in the onset of LBP. Nevertheless, in the more serious LBP cases, occupational stress is an aggravating factor for LBP and its consequences.     

Effects of photodegradation of dissolved organic matter on the binding of benzo(a)pyrene

Dissolved organic matter (DOM) in natural waters can bind various organic pollutants, and the affinity of this binding is strongly influenced by the chemical characteristics of the DOM and water pH. This study examined the effects of photochemically induced alteration of the DOM's chemical properties and water pH on the binding of benzo(a)pyrene (BaP). Time- and pH-series of solar-simulated irradiations were performed on a natural water sample and aqueous DOM solutions prepared from aquatic and soil humic substances. The binding affinity of BaP, expressed as a partition coefficient of a compound to DOM, decreased substantially after the DOM samples were irradiated over environmentally relevant radiation doses and pH ranges. The lowering of the pH due to the photoproduction of acidic products often partly offsets the reduction of the binding affinity caused by direct photoalteration of the DOM's chemical structure. The decrease of the binding affinity, after correction for the photoinduced pH change, was positively correlated with the decrease in the molecular weight and the aromaticity of the DOM in the course of irradiation. Increasing O(2) abundance accelerated the decrease of the binding affinity as a result of enhanced DOM photodegradation. Visible light played a more important role in reducing the molecular weight and aromaticity of the DOM than in reducing the content of dissolved organic carbon (DOC) via photoremineralization while the reverse was true for UV radiation, indicating that photochemical reduction of the binding affinity may occur in natural waters at depths greater than UV radiation can reach. A decrease of the affinity of DOM for binding BaP will increase the free dissolved fraction of BaP and thus its availability and toxicity to aquatic organisms. The results from this study may have similar implications for organic pollutants other than BaP.     

Conceptual evolution of the bioeconomy: a bibliometric analysis

Environment, Development and Sustainability - The growing concern over the change in climatic conditions and the management and conservation of biological resources makes it necessary to create...