The influence of some biological antioxid ants on the light emission from the oxytetracycline oxidation reaction

The effect of the Superoxide radical (O₂ ^–)‐, hydroxyl radical (HO')‐inhibitors, singlet oxygen (¹O₂)‐quenchers and catalase on the light emission during autoxidation reaction of oxytetracycline was measured. The influence of the ¹O₂‐quenchers was investigated quantitatively and the rate constants were established.     

Crafting a job on a daily basis: Contextual correlates and the link to work engagement

This study focused on daily job crafting and explored its contextual determinants and one motivational outcome (i.e., work engagement). Job crafting was conceptualized as “seeking resources,” “seeking challenges,” and “reducing demands.” Participants were 95 employees from several organizations who completed a 5‐day diary survey. As hypothesized, we found a 3‐factor structure for the job crafting instrument, both at the general and day levels. We hypothesized and found that the combination of high day‐level work pressure and high day‐level autonomy (active jobs) was associated with higher day‐level seeking resources and lower day‐level reducing demands. Furthermore, we found that day‐level seeking challenges (but not resources) was positively associated with day‐level work engagement, whereas day‐level reducing demands was negatively associated with day‐level work engagement. Findings suggest that job crafting is a daily employee behavior with implications for management practice and future research. Copyright © 2012 John Wiley & Sons, Ltd.     

The impact of iron limitation on the physiology of the Antarctic diatom Chaetoceros simplex

Iron availability strongly governs the growth of Southern Ocean phytoplankton. To investigate how iron limitation affects photosynthesis as well as the uptake of carbon and iron in the Antarctic diatom Chaetoceros simplex, a combination of chlorophyll a fluorescence measurements and radiotracer incubations in the presence and absence of chemical inhibitors was conducted. Iron limitation in C. simplex led to a decline in growth rates, photochemical efficiency and structural changes in photosystem II (PSII), including a reorganisation of photosynthetic units in PSII and an increase in size of the functional absorption cross section of PSII. Iron-limited cells further exhibited a reduced plastoquinone pool and decreased photosynthetic electron transport rate, while non-photochemical quenching and relative xanthophyll pigment content were strongly increased, suggesting a photoprotective response. Additionally, iron limitation resulted in a strong decline in carbon fixation and thus the particulate organic carbon quotas. Inhibitor studies demonstrated that, independent of the iron supply, carbon fixation was dependent on internal, but not on extracellular carbonic anhydrase activity. Orthovanadate more strongly inhibited iron uptake in iron-limited cells, indicating that P-type ATPase transporters are involved in iron uptake. The stronger reduction in iron uptake by ascorbate in iron-limited cells suggests that the re-oxidation of iron is required before it can be taken up and further supports the presence of a high-affinity iron transport pathway. The measured changes to photosystem architecture and shifts in carbon and iron uptake strategies in C. simplex as a result of iron limitation provide evidence for a complex interaction of these processes to balance the iron requirements for photosynthesis and carbon demand for sustained growth in iron-limited waters.     

Evaluating 22 EU member states’ ‘waste culture’ using Hofstede’s and Schwartz’s cultural dimensions

The issue of municipal solid waste (MSW) arisings has received great attention recently since it is not only a by-product of economic activity but also serves as an input to the economy through material or energy recovery. The main focus of this study is cultural formation and especially the current picture of waste culture and public perception across European Union (EU) member states. Thus, this study will first evaluate environmental efficiency with data envelopment analysis (DEA) based on five parameters: waste, gross domestic product (GDP), labour, capital, and population density for 22 EU Member States and for the years 2005, 2010 and 2015 in order to evaluate which Member States are more efficient. Then the efficiency results are contrasted to Hofstede’s and Schwartz’s cultural dimensions on STATA with the use of regression modelling. Results show that for year 2005 no significant relationship is noticed for both cultural models, whereas for years 2010 and 2015 there appears to be a significant connection. The above-mentioned findings can be associated with the financial crisis that has hit Europe after 2008 making people more sceptical, while EU legislations have laid out some important directives in the field of waste management. Finally, along with the factors above, EU has faced severe environmental challenges due to waste arisings, as well as accidents and injuries for people working in this sector, which in turn have widely modified EU’s waste culture as supported by this study’s results.     

Automated fluorimetric sensor for hydrazine determination in water samples based on the concept of zone fluidics

Environmental Science and Pollution Research - In the present study, we report an automated fluorescence sensor for the determination of hydrazine in various water samples based on the concept of...     

Mortality of the scleractinian coral <Emphasis Type="Italic">Cladocora caespitosa</Emphasis> during a warming event in the Levantine Sea (Cyprus)

A mortality event of Cladocora caespitosa corals and the extent of bleaching, necrosis and pigmented areas in the colonies were studied at the southeastern coast of Cyprus during a prolonged period of higher than average sea temperature anomalies (summer/autumn 2012). With the use of scuba diving and image analysis software, we monitored the extent of mortality of 29 colonies of C. caespitosa by measuring and comparing the area percentage of healthy tissue, affected tissue (bleached, necrotic) and older mortality events (encrusted skeleton). In September 2012, on average, 24 % of the colonies surface area was affected (bleaching and/or necrosis). In October 2012, C. caespitosa showed on average 26.3 % of the colony surface area affected, evidence of continuing deterioration. At the same time, 10 % (3 of 29) of the colonies showed an increase in the pigmentation of previously bleached polyps in small and marginal areas (6–8 %). Irrespective of the amount, the regaining of pigments recorded is considered an important find. Corals and marine organisms in general in the Levantine Sea are affected greatly by warming events, to the extent where a very small percentage of polyps/colonies show resilience under thermal stress. Natural bleaching of C. caespitosa, even though limited to a few colonies and very small portions of tissue/polyps, was documented for the first time in the Levantine Sea. We conclude that temperature anomalies are associated with the mortality event. Whether prolonged higher temperature is the direct cause, or whether it acts synergistically with other factors should be the subject of further investigations.     

Heterogeneity in the photoprotective capacity of three Antarctic diatoms during short-term changes in salinity and temperature

The Antarctic marine ecosystem changes seasonally, forming a temporal continuum of specialised niche habitats including open ocean, sea ice and meltwater environments. The ability for phytoplankton to acclimate rapidly to the changed conditions of these environments depends on the species’ physiology and photosynthetic plasticity and may ultimately determine their long-term ecological niche adaptation. This study investigated the photophysiological plasticity and rapid acclimation response of three Antarctic diatoms—Fragilariopsis cylindrus, Pseudo-nitzschia subcurvata and Chaetoceros sp.—to a selected range of temperatures and salinities representative of the sea ice, meltwater and pelagic habitats in the Antarctic. Fragilariopsis cylindrus displayed physiological traits typical of adaptation to the sea ice environment. Equally, this species showed photosynthetic plasticity, acclimating to the range of environmental conditions, explaining the prevalence of this species in all Antarctic habitats. Pseudo-nitzschia subcurvata displayed a preference for the meltwater environment, but unlike F. cylindrus, photoprotective capacity was low and regulated via changes in PSII antenna size. Chaetoceros sp. had high plasticity in non-photochemical quenching, suggesting adaptation to variable light conditions experienced in the wind-mixed pelagic environment. While only capturing short-term responses, this study highlights the diversity in photoprotective capacity that exists amongst three dominant Antarctic diatom species and provides insight into links between ecological niche adaptation and species’ distribution.