The ever-increasing occurrence and persistence of pharmaceutically active compounds (PhACs) in soils, sediments, drinking water supplies and wastewater effluents are a matter of serious environmental ...concern for governments and researchers worldwide. Nanofiltration as tertiary treatment method can be a viable and practical tool to remove these pollutants from aquatic environments. However, organic matter present in water sources can foul the membrane surface during operation, thus being potentially able to affect the membrane performance. Therefore, fouling mechanisms could heavily influence on the removal efficiencies. The purpose of this study was to investigate the implementation of three nanofiltration membranes (TFC-SR2, NF-270 and MPS-34) and to study both the rejection of trace PhACs and the fouling mechanisms for each membrane as a function of feed solution pH. Fouling mechanisms were predicted by Hermia's model adapted to cross-flow configurations. Results demonstrated that higher removals were obtained at slightly alkaline pH, especially for anionic trace PhACs. At the same conditions, more severe fouling was observed, which resulted in strong flux declines and an increase in hydrophobicity. This indicates that the attached organic matter on the membrane surface acts as a secondary selective barrier for separation.
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•Rejection of eight PhACs and triclosan by three nanofiltration membranes was studied.•Fouling mechanisms were assessed by using Hermia's models.•Effect of both feed solution pH and fouling on the removal of PhACs was analysed.•Gel layer formation demonstrated to be the predominant fouling mechanism.•Rejection of anionic PhACs was strongly pH-dependent.
•Hydrophilicity and permeation properties were affected by adding of Al2O3 and PEG.•The combination of both additives was tested in PES, PS and PEI membranes.•Membranes modified with PEG/Al2O3 showed ...the best antifouling property.•All prepared membranes were synthesized by phase inversion method.•All prepared membranes showed similar MWCO, around 30kDa.
The influence of the modification by additives in the characteristics of several ultrafiltration polymeric membranes was studied. Three asymmetric membranes with similar pore size (molecular weight cut-off (MWCO) of around 30kDa) but different materials and pore microstructures – polysulfone, polyethersulfone and polyetherimide – were used. Effects of two different hydrophilic additives on membrane structure and the resulting performance were compared to determine the material with the best antifouling properties. Polyethyleneglycol (PEG) and alumina (Al2O3) were employed as additives in the phase-inversion method, N,N-Dimethylacetamide and deionized water were used as solvent and coagulant, respectively. Membranes were characterized in terms of hydraulic permeability, membrane resistance, MWCO profile and hydrophilicity (by membrane porosity and contact angle). The cross-sectional and membrane surface were also examined by microscopic techniques. Membrane antifouling properties were analysed by the experimental study of fouling/rinsing cycles using feed solutions of PEG of 35kDa. Permeation and morphological studies showed that the addition of PEG/Al2O3 results in formation of a hydrophilic finger-like structure with macrovoids, whereas the addition of Al2O3 results in the formation of a hydrophilic structure with a dense top layer with Al2O3 nanoparticles and a porous sponge-like sublayer. Furthermore, polyethersulfone/PEG/Al2O3 membranes displayed superior antifouling properties and desirable ultrafiltration performance.
•Rejection of ten PhACs by ceramic fine ultrafiltration membranes was studied.•Effect of feed solution pH on the removal of PhACs was analysed.•Results demonstrated that rejection of anionic PhACs ...was strongly pH-dependent.•The formed foulant layer on the membrane acted as a secondary membrane.
This study investigates the influence of feed solution pH and fouling on the rejection of ten selected pharmaceutically active compounds (PhACs) with different physicochemical characteristics (molecular weight, water solubility, log KOW, pKa, dipole moment, etc.) by three multichannel ceramic ultrafiltration membranes, ranging from 1 to 8kDa, in order to improve their removal from water. For this purpose, the comparison between filtration of PhACs in deionised water (Feed I) and in real wastewater effluent (Feed II) was performed, demonstrating that the variation of pH and the formation of a foulant layer altered the separation mechanism and hence the rejection values of each PhAC varied. Higher rejections of most of the PhACs were higher at slightly alkaline pH, especially for anionic compounds in the filtration with real wastewater. In these conditions, flux decline was more severe. The formed fouling layer onto the hydrophilic membrane surface acted as a secondary barrier for separation with different properties like hydrophobicity and charge. Electrostatic interactions were the main separation mechanism in the filtration of PhACs in deionised water, while the hydrophobic/hydrophilic interactions played a crucial role in the filtration experiments with real wastewater effluent. Thus, the reported results indicated that the rejection of pharmaceutically active compounds was strongly pH-dependent, except for hydrophilic neutral compounds (acetaminophen and caffeine), which showed a pH-independent behaviour with low rejection values.
The uncertain future of protected lands and waters Golden Kroner, Rachel E; Qin, Siyu; Cook, Carly N ...
Science (American Association for the Advancement of Science),
05/2019, Letnik:
364, Številka:
6443
Journal Article
Recenzirano
Odprti dostop
Protected areas are intended to safeguard biodiversity in perpetuity, yet evidence suggests that widespread legal changes undermine protected area durability and efficacy. We documented these legal ...changes-protected area downgrading, downsizing, and degazettement (PADDD) events-in the United States and Amazonian countries and compiled available data globally. Governments of the United States and Amazonian countries enacted 269 and 440 PADDD events, respectively. Between 1892 and 2018, 73 countries enacted 3749 PADDD events, removing 519,857 square kilometers from protection and tempering regulations in an additional 1,659,972 square kilometers; 78% of events were enacted since 2000. Most PADDD events (62%) are associated with industrial-scale resource extraction and development, suggesting that PADDD may compromise biodiversity conservation objectives. Strategic policy responses are needed to address PADDD and sustain effective protected areas.
In today's world, the corporate image of the largest companies is closely linked to their performance in the field of corporate social responsibility and the disclosure of information on that topic, ...specifically, on climate change. Since the Board of Directors is the body responsible for this process, the aim of this article is to show the role that companies' Boards of Directors play in the accountability process vis-à-vis stakeholders in relation to one specific aspect which has enormous significance in environmental information: practices used to monitor greenhouse gas emissions. In order to achieve this, we shall verify certain business characteristics, in addition to the size and activity of the Board of Directors, and we shall take different dependence models into consideration. These models will include variables related to the level of independence and diversity of the Board of Directors, which interact with dummy variables representing the company's litigation risks regarding environmental behavior and the institutional macro-context of the organization's country of origin. The results make it clear that Boards of Directors are basically focused on the traditional responsibility of creating economic value, instead of dealing with today's broader business world concepts, which include social responsibility. This focus, therefore, does not favor the accountability process before other stakeholders, if this makes it more difficult to protect the interests of shareholders.
Inorganic nanoparticles have been applied as additive in membrane synthesis for improving different properties from the base polymer such as hydrophilicity, fouling resistance or permselectivity. To ...investigate the changes caused by the presence of the inorganic nanoparticles in the formation of the membrane structure, two different metallic compounds with opposite hydrophilicity were used as additives: hydrophilic zinc oxide (ZnO) and hydrophobic tungsten disulphide (WS2). For this purpose, the effect of these metal nanoparticles at ultra-low concentrations (0.05 and 0.25wt% metal nanoparticles/polymer ratio) in the preparation of flat-sheet membranes based on polyethersulphone (PES) by immersion-precipitation method was investigated. N-methyl-2-pyrrolidone (NMP) was used as solvent. The influence of both metal nanoparticles on the characteristics and permselective properties of PES membranes was studied with microscopic observations, contact angle measurements, and filtration experiments. Although the incorporation of metal nanoparticles could turn the system into thermodynamically unstable, the demixing process during formation of membranes was slightly delayed, suppressing the macrovoid formation (remarkably using WS2). Regardless the nature of the metal nanoparticles, results showed an overall improvement in membrane hydrophilicity and permselectivity by adding metal nanoparticles compared to the control PES membrane, demonstrating that the behaviour of both metal nanoparticles at ultra-low concentrations was very similar.
•Phase-inversion PES membranes were modified by hydrophilic ZnO and hydrophobic WS2.•Structural changes were observed using SEM, AFM and cloud point measurements.•The presence of both metal nanoparticles delayed the demixing process.•Membrane permselectivity was improved using both metal nanoparticles.
Many studies have examined the direct relationship between the two corporate practices: corporate social responsibility (CSR) and earnings management (EM); however, the results remain heterogeneous. ...To achieve the consensus, this study builds upon the classical agency theory and examines the role of managerial entrenchment in creating organizational facades related to CSR and EM. More specifically, it examines the relationship between CSR performance and EM in the presence of managerial entrenchment and the direct effect of managerial entrenchment on CSR decoupling. In doing so, this article provides evidence of a previously underappreciated yet fundamentally important aspect, that is, managerial entrenchment, that may significantly affect the quality of earnings as well as the level of alignment between CSR disclosure and performance. Our analyses of longitudinal data of an international sample for the period of 2007–2016 supports that managerial entrenchment significantly moderates the relationship between CSR performance and EM. Furthermore, our study reveals that entrenched managers decouple CSR disclosure and performance.
Tacrine and PBT2 (an 8-hydroxyquinoline derivative) are well-known drugs that inhibit cholinesterases and decrease β-amyloid (Aβ) levels by complexation of redox-active metals, respectively. In this ...work, novel tacrine−8-hydroxyquinoline hybrids have been designed, synthesized, and evaluated as potential multifunctional drugs for the treatment of Alzheimer’s disease. At nano- and subnanomolar concentrations they inhibit human acetyl- and butyrylcholinesterase (AChE and BuChE), being more potent than tacrine. They also displace propidium iodide from the peripheral anionic site of AChE and thus could be able to inhibit Aβ aggregation promoted by AChE. They show better antioxidant properties than Trolox, the aromatic portion of vitamin E responsible for radical capture, and display neuroprotective properties against mitochondrial free radicals. In addition, they selectively complex Cu(II), show low cell toxicity, and could be able to penetrate the CNS, according to an in vitro blood−brain barrier model.
Tacrine-melatonin hybrids were designed and synthesized as new multifunctional drug candidates for Alzheimer's disease. These compounds may simultaneously palliate intellectual deficits and protect ...the brain against both beta-amyloid (A beta) peptide and oxidative stress. They show improved cholinergic and antioxidant properties, and are more potent and selective inhibitors of human acetylcholinesterase (hAChE) than tacrine. They also capture free radicals better than melatonin. Molecular modeling studies show that these hybrids target both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. At sub-micromolar concentrations they efficiently displace the binding of propidium iodide from the PAS and could thus inhibit A beta peptide aggregation promoted by AChE. Moreover, they also inhibit A beta self-aggregation and display neuroprotective properties in a human neuroblastoma line against cell death induced by various toxic insults, such as A beta(25-35), H(2)O(2), and rotenone. Finally, they exhibit low toxicity and may be able to penetrate the central nervous system according to an in vitro parallel artificial membrane permeability assay for the blood-brain barrier (PAMPA-BBB).
Aim
To examine the effects of expert HIV patients acting as teachers to Spanish nursing students both on their HIV‐related knowledge, attitudes and practices and on their approach to the care model ...as well as to explore their learning experience.
Design
Non‐randomized, single‐arm study with quantitative before and after measurements and qualitative data.
Methods
The intervention consisted of five 90‐min workshops led by two women living with HIV. Thirty‐four nursing students participated, and quantitative and qualitative data were gathered from February to June 2018. We used the Patient‐Practitioner Orientation Scale (PPOS) and the KAP questionnaire on HIV/AIDS to collect quantitative data.
Results
Statistically significant differences were found in the global score for care orientation and its two dimensions, caring and sharing. About the changes resulting from the workshops, the quantitative results—more patient‐centred care perception and better attitudes towards people living with HIV—match the qualitative findings in all the aspects studied, except in sharing.
Conclusion
Incorporating expert patients as teachers in the nursing bachelor's degree resulted in more patient‐centred care and improved knowledge, attitudes and practices. The workshops conducted by qualified expert patients showed transformative learning power, as the participants improved professional and personal aspects.
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