Study of the Kuznets environmental curve hypothesis from a global perspective 1960–2019: a semi-parametric panel data proposal

Environmental Science and Pollution Research - This work uses parametric and semiparametric panel data analysis methodologies to test the hypothesis of the environmental Kuznets curve, in 186...     

Immediate one-step lime precipitation process for the valorization of winery wastewater to agricultural purposes

Environmental Science and Pollution Research - The winery wastewater (WW) of the Village of Vidigueira, in south of Portugal, presented an acid pH (4.26 ± 0.029), a high content of chemical...     

Perceptions of the Importance and Control of Professional Problems in the Clinical Setting

The objective of this study was to identify the relative importance of culturally relevant professional problems and the degree of control over them, as perceived by dentists and dental students in Mexico City, Mexico. The dentists and students ranked 13 problems according to importance and then according to the perceived degree of control over each one. Novice clinicians were less secure about their ability to cope with the legal, financial, and clinical performance problems, whereas experienced clinicians were more concerned about occupational hazards and the dental market and culture. Both reported similar perceptions of their control of the problems. This preliminary information should support introducing into dental schools relevant practice-management courses, targeting continuing education efforts, and instituting professional counseling measures to meet the challenges posed by these problems.     

Carotenoid-based bill and eye ring coloration as honest signals of condition: an experimental test in the red-legged partridge (<Emphasis Type="Italic">Alectoris rufa</Emphasis>)

Carotenoid pigments cannot be synthesized by vertebrates but must be ingested through the diet. As they seem to be a limited resource, carotenoid-based ornaments are particularly interesting as possible honest signals of individual quality, in particular of foraging efficiency and nutritional status. Some studies have demonstrated the condition dependence of carotenoid-based plumage in birds. However, many other carotenoid-pigmented bare parts (i.e. skin, caruncles, bills, cere, and tarsi) are present in birds but, in comparison with plumage, little is known about these traits as indicators of individual quality. Here, we show that the eye ring pigmentation and bill redness of the red-legged partridge (Alectoris rufa) are positively associated to body condition and recent changes in body mass. Also, we found a negative relationship between these two traits and heterophil-to-lymphocyte ratio, an indicator of physiological stress (the relationship with bill redness being significant only for males). In an experiment, we found that after a period of reduction in food intake (with the consequent loss of body mass), food-restricted birds showed lower eye ring pigmentation than ad-libitum-fed birds. Therefore, different ornaments seem to reflect changes in body condition but at different speeds or intensities (eye ring, a fleshy ornament, appears to respond more rapidly to changes in the nutritional status than a keratinized structure as the bill). These results indicate that carotenoid-based ornaments are condition-dependent traits in the red-legged partridge, being therefore susceptible to be employed as honest signals of quality in sexual selection.     

On the origin of fiber calcite crystals in moonmilk deposits

In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber calcite crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals, extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes.     

Sorption of As, Cd and Tl as influenced by industrial by-products applied to an acidic soil: equilibrium and kinetic experiments

In situ stabilization of toxic elements in contaminated soils by the addition of amendments is being considered as an effective technique for remediation. In this paper, we performed both kinetics and equilibrium-based sorption experiments of three toxic elements (As, Cd and Tl) in soils amended with two by-products (phosphogypsum and sugar foam, rich in gypsum and calcium carbonate, respectively) to ascertain the feasibility of their application for improving the sorption capacity of As, Cd and Tl from the soil at 25, 35 and 50 °C. Kinetic studies indicated that the sorption follows a pseudo-second-order (PSO) kinetics and the sorption is a two-step diffusion process where both film and intraparticle diffusion played important roles in the sorption mechanisms of the elements. The Langmuir isotherms applied for sorption studies showed that the estimated maximum sorption capacity of the elements in control and amended soils decreased in the order of Cd > As > Tl. Using the thermodynamic equilibrium parameters obtained at different temperatures, the thermodynamic constants of sorption (ΔG, ΔH and ΔS) were also evaluated, indicating spontaneous and endothermic nature of the process, except Tl which was exothermic. An optimal scaling procedure was undertaken to determine the relationships between the kinetic and equilibrium sorption parameters. By means of statistical analysis it was seen that these inter-parametric relationships are dependent on the element nature.     

Retention of Cd, Zn and Co on hydroxyapatite filters

This study qualifies and quantifies the immobilization of Cd, Zn and Co, (used as models of bivalent metal ions due to their relevant toxicity) in filters of synthetic hydroxyapatite (HAP) [Ca5(PO4)3OH]. They were flushed with solutions containing Cd (1 x 10(-5)M), Zn and Co (1 x 10(-4)M) at constant pH (8.6) and ionic strength (0.01 M). The concentration of these metal ions in the outlet was measured by ICP-OEM spectroscopy. The software PHREEQC (version 2.4.2) was used to model sorption process and the potential effect of salinity (KCl), pH, alkalinity (NaHCO3) and hardness (CaCl2) over the efficiency of the treatment. Results showed an excellent retention capacity of HAP for Cd, Zn and Co. Sorption data were successfully described considering a mix model of surface complexation onto phosphate surface groups, ionic exchange in surface calcium sites and the precipitation of ZnO. Co exchange and surface complexation constants (Kex and Kc) were taken from previous experiments, while KexCd=0.32 and KcCd=0.63 were estimated from our modeling results. Predictive values of metal ion sorption show that: (a) an increase in hardness does not play a significant role in the retention capacity of these metals on HAP; (b) an increase in alkalinity promotes the precipitation of MeCO3 which could alter the hydrodynamic of the column; (c) a decrease in pH and an increase in salinity inhibit ZnO precipitation enhancing Zn and Cd adsorption and decreasing Co retention on HAP.     

Improved weighted ensemble learning for predicting the daily reference evapotranspiration under the semi-arid climate conditions

Environmental Science and Pollution Research - Evapotranspiration is an important quantity required in many applications, such as hydrology and agricultural and irrigation planning. Reference...