Assessment of Phosphorus Input from Urban Areas in the Passaúna River and Reservoir

Elevated phosphorus loads play an important role in the deterioration of water quality and can subsequently pose a threat to the aquatic organisms in a river or a standing water body. The accurate assessment of total phosphorus (TP) fluxes from a catchment is of high importance to the well-being of the entire river ecosystem. In this study, we assessed the yearly input of TP from the urban areas of the Passaúna catchment in southern Brazil. The catchment drains into the eponymous reservoir, which provides drinking water for more than 800,000 inhabitants of the Curitiba Metropolitan region. The protection of the water quality in the river as well as in the reservoir is of paramount importance, yet high phosphorous inputs have been detected. For adequate protection, the catchment emissions need to be accurately assessed. Initially, the TP concentration in the river sediment was determined in order to assess the relationship between the TP export of the urban areas and the TP stock of the river. It was found that in areas with a higher share of urban land cover and especially in areas with a lack of sewage treatment, the TP concentration in the sediment reached up to 6700 mg/kg. The assessment of the overall TP input from urban areas was based on a regionalized emission-modeling approach, combined with data from long-term water quality monitoring of the river. The monitoring station established upstream of the Passaúna Reservoir inflow provided an initial assessment and the necessary output for the validation and calibration of the model. From the drainage basin of the monitoring station, an overall TP input of 2501 kg/a (0.31 kg/(ha a)) was measured between 1 May 2018 and 1 May 2019 (3508 kg TP/a or 0.23 kg/(ha a) when extrapolating the overall catchment of the Passaúna Reservoir). The monitoring data indicated that the TP input increases during the wet months of the year. The sediment stock of the river also plays an important role in the interannual budget of TP. During the timespan of one year, many deposition–resuspension events happen. The resuspended material is included in the baseflow and hinders the differentiation between urban and nonurban input. After calibration, the model was able to predict the yearly input of TP from the urban areas of the Passaúna catchment. In addition, the share of inhabitants who are not connected to the sewer system was assessed. Overall, the combination of monitoring and modeling in this study offers a valuable overview of the TP dynamics of the system, while the model ensures reproducibility with high accuracy at the same time

Comparing C-60 and C-70 as acceptor in organic solar cells : Influence of the electronic structure and aggregation size on the photovoltaic characteristics

The difference in aggregation size of the C-60 and C-70 fullerenes affect the photovoltaic performance of devices assembled in the so-called bilayer architecture with poly [2,7-(9,9- dioctyl- dibenzosilole)- alt-4,7- bis(thiophen-2-yl)benzo- 2,1,3- thiadiazole] (PSiF-DBT) as the electron donor material. Despite the better performance of the C-70 devices, which is related to the high absorption coefficient in the visible range and the superior charge transport properties, the short-circuit current variation upon annealing treatment at 100 degrees C is approximately twice bigger when the C-60 is the acceptor. We attribute this effect to the tendency of C-60 in form smaller aggregate domains relatively to the C-70. The increased roughness on the polymeric surface after annealing results in an enhanced donor/acceptor contact area and assists the fullerene diffusion deeper inside the polymeric layer. This effect leads to a better mixing between donor and acceptor species and create a interpenetrating layer close to the so-called bulk heterojunction. Since C-60 forms smaller aggregates, this mechanism is more pronounced for this molecule. Therefore, a significant variation in the performance of the C-60 devices is observed after this kind of treatment. Density Functional Theory calculations of the potential energy of interaction between two fullerene molecules and X-Ray measurements gives evidences to support this idea. In addition, combining spectrally resolved external quantum efficiency measurements with optical modeling our results also indicate the occurrence of the bilayer interfacial mixing for PSiF-DBT/C-60.Peer reviewe

Manual therapy for chronic migraine: a pragmatic randomised controlled trial study protocol

Introduction Chronic migraine is a largely refractory condition affecting between 1 and 2.2% of the overall population worldwide, with females more affected than males. There are also high health and socioeconomic costs associated both for the individual and society. The mainstay of chronic migraine management is pharmacological, but the options available have limited efficacy and there are often unwanted side effects. There is some evidence for manual therapy as a treatment option for migraine, but its effectiveness for chronic migraine is unknown. Therefore, we have designed a pragmatic randomised control trial to investigate whether adding manual therapy to the tertiary specialist treatment of chronic migraine improves patient-reported outcomes. Methods A pragmatic, randomised controlled trial in a hospital tertiary headache clinic. Participants will be randomised into one of two groups: treatment as usual or treatment as usual plus manual therapy. The primary outcome measure will be a change in the Headache Impact Test score. Secondary outcomes will also be measured over the 12-week study period including changes in headache frequency, migraine specific quality of life and reductions in relevant medicine consumption. The manual therapy group will have five treatment sessions each lasting 30 min. The recruitment target of 64 participants will allow power at 80% with p = 0.05 using minimal clinical difference for Headache Impact Test of 3.7 and includes provision for a 10% dropout rate. Recruitment will take place between August 2018 and February 2019. The results will form part of a doctoral study and be published in peer-reviewed journals and presented at national/international conferences. Discussion Current pharmacological approaches have limited effects in the management of chronic migraine and there is a requirement to improve treatment options and reduce the health and economic burden of the condition. Manual therapy has been shown to be effective in other chronic pain conditions as well as other primary headaches. This study will explore the effectiveness of manual therapy as an adjunctive approach to the management of chronic migraine. Trial registration The trial has received a favourable opinion from the UK Health Research Authority (IRAS 228901) and is registered at ClinicalTrials.gov.number NCT03395457. Registered 1st March 2018

Biodeterioration Affecting Efficiency and Lifetime of Plastic-Based Photovoltaics

The low environmental impact of electricity generation using solar cells crucially depends on high energy-conversion efficiencies, long lifetimes, and a minimal energy and material demand during production. Emerging thin-film photovoltaics such as perovskites on plastic substrates could hold promises to fulfill all these requirements. Under real-world operating conditions, photovoltaic operation is challenged by biological stressors, which have not been incorporated for evaluation in any test. Such stressors cause biodeterioration, which impairs diverse, apparently inert materials such as rock, glass, and steel and therefore could significantly affect the function and stability of plastic-based solar cells. Given that different photovoltaic technologies commonly use similar materials, the biodeterioration mechanisms reviewed here may possibly affect the efficiency and lifetimes of several technologies if they occur sufficiently faster (during the expected lifetime of photovoltaics). Once the physical integrity of uppermost module layers is challenged by biofilm growth, microbially mediated dissolution and precipitation reactions of photovoltaic functional materials are very likely to occur. The biodeterioration of substrates and seals also represents emission points for the release of potentially harmful photovoltaic constituents to the environment. Upon exposure to the natural environment, not even diamonds are forever. In real-world operating conditions, photovoltaics are affected by biodeterioration through biofilm growth that impairs diverse, apparently inert materials, such as rock, glass, and steel. Biodeterioration goes beyond obstructing incoming light and affecting energy conversion; it challenges the physical integrity of substrates. This phenomenon may thus heavily degrade primarily plastic-based thin-film photovoltaics. Following initial degradation, functional layers can undergo microbially mediated dissolution and precipitation, thereby affecting the lifetimes of such solar cells. Biofilm development also influences how potentially harmful photovoltaic constituents (e.g., lead from perovskites) are released to the environment. Despite the considerable potentiality of these detrimental effects, however, they are yet to be systematically studied. Given that different types of solar cells commonly use similar materials, the biodeterioration mechanisms reviewed here may affect several technologies. This paper provides a comprehensive review of the colonization of photovoltaics by sub-aerial biofilms and their potential negative impacts on photovoltaics. We discuss why abiotic laboratory tests for PV efficiency and lifetime poorly reflect the stress PVs suffer in outdoor conditions. We then summarize the knowledge on soiling as well as microbial-, algal-, and fungal growth on PVs. This is followed by a discussion of the physical mechanisms that affect PV efficiency via soiling and photon competition as well as chemical and biological mechanisms (plastic degradation, microbially induced dissolution, and precipitation reactions) that can affect active layers and thus the lifetime of PVs in the field. Solar cells are subjected to various physical, chemical, and biological stressors in the field. Here, a perspective on the potential detrimental effects of biofilm growth on solar cells is given. Soiling and photon competition affect the photovoltaic performance of all cells, while a suite of biochemical mechanisms (“biodeterioration”) may affect the efficiency and lifetime of plastic-based solar cells in particular. Further, biodeterioration might provide a pathway for the entry of harmful solar cell components to the environment.</p

Conformational Change on a Bithiophene-Based Copolymer Induced by Additive Treatment: Application in Organic Photovoltaics

In recent years the use of solvent additives for fabrication of polymer-based solar cells has become an important procedure to induce morphological changes at the system nanoscale, a critical step to improve device performance. Yet the actual effects of those additives on the polymer’s backbone conformations (with coupled variations on the electronic structure) remain very elusive. By combining different experimental and theoretical techniques, we show that the use of the solvent additive 1,8-diiodooctane (DIO) might influence the conformation of poly­[(9,9-dioctylfluorenyl-2,7-diyl)-<i>co</i>-bithiophene] (F8T2) chains resulting in improved properties of the film. We correlate this conformational variation with the photovoltaic response of F8T2:fullerene­(C₆₀) devices prepared using different DIO concentrations. We find that the efficiency of the devices increases more than 100%, and the hole mobility in the F8T2 films increases almost 1 order of magnitude with the use of DIO. A comparison between experimental data and the properties of the calculated structures suggests that the additive induces a higher density of syn conformers in the bithiophene unit of the copolymer backbone, planarizing the polymer’s geometry. The simulations indicate that this transition is very likely mediated by the electrostatic interaction between the iodine atom of the DIO and the heteroatoms of the bithiophene moiety. The higher degree of electronic delocalization and the enhancement of the interchain interactions improve the transport and the photovoltaic features of F8T2 layers. The use of solvent additive treatments to control conformational variations of the backbone might be a promising strategy to improve the optoelectronic properties of polymer-based devices