Diatom frustules enhancing the efficiency of gel polymer electrolyte based dye-sensitized solar cells with multilayer photoelectrodes

The incorporation of nanostructures that improve light scattering and dye adsorption has been suggested for dye-sensitized solar cells (DSSCs), but the manufacture of photonic and nanostructured materials with the desired properties is not an easy task. In nature, however, the process of light-harvesting for photosynthesis has, in some cases, evolved structures with remarkable wavelength-sensitive light-trapping properties. The present work is focused on enhancing the efficiency of quasi solid-state DSSCs by capitalizing on the light trapping properties of diatom frustules since they provide complex 3-dimensional structures for scattering and trapping light. This study reports a promising approach to prepare TiO2 nanocrystal (14 nm) based photo-electrodes by utilizing the waveguiding and photon localization effects of nanostructured diatom frustules for enhancing light harvesting without deteriorating the electron conduction. Single and double-layered photo-electrodes were prepared with different frustule/nanocrystal combinations and conformations on transparent conductive oxide substrates. This study clearly reports impressive efficiency and short circuit current density enhancements of about 35% and 39%, respectively, due to the incorporation of diatom frustules extracted from a ubiquitous species. The SEM images obtained in this work reveal that the produced thin films had a remarkable surface coverage of evenly distributed frustules within the TiO2 nanoparticle layer. To the best of our knowledge, this study reports the first quasi solid-state DSSC based on a photo-electrode with incorporated bio-formed nanostructures

Allogeneic bone marrow transplantation in second remission of childhood acute lymphoblastic leukemia: a population-based case control study from the Nordic countries

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldThis study compares allogeneic BMT with conventional chemotherapy for childhood ALL in second remission. Seventy-five children were transplanted between July 1981 and December 1995. For each patient two control patients matching the following criteria were selected from the Nordic database of ALL: (1) time of diagnosis, (2) T vs. non-T ALL, (3) site of relapse, (4) initial risk group, (5) sex and (6) relapse or =6 months after cessation of therapy. The minimal time of follow-up was 24 months. Mortality rate in CR2, leukemic relapse rate and the proportion in continued second remission were 16/75 (21%), 22/75 (29%) and 37/75 (50%), respectively. P2.-EFS for the BMT group was significantly better than that for the control group (0.40 vs. 0.23, P = 0.02). Children transplanted for bone marrow relapses in particular had a higher P2.-EFS (0.35 vs. 0.15 for the control group, P<0.01). Also, children grafted for early BM relapses had a higher P2.-EFS (0.32 vs. 0.11 for the control group P = 0.01). The outcome was similar when children were transplanted after early or late relapse. Also, there was no difference in outcome between the BMT and the chemotherapy group for children with late relapses. We conclude that allogeneic BMT with an HLA-identical sibling donor or other family donor should be performed in children relapsing in bone marrow during therapy or within 6 months of discontinuing therapy

Groundwater nitrate reduction versus dissolved gas production: A tale of two catchments

peer-reviewedAt the catchment scale, a complex mosaic of environmental, hydrogeological and physicochemical characteristics combine to regulate the distribution of groundwater and stream nitrate (NO3−). The efficiency of NO3− removal (via denitrification) versus the ratio of accumulated reaction products, dinitrogen (excess N2) & nitrous oxide (N2O), remains poorly understood. Groundwater was investigated in two well drained agricultural catchments (10 km2) in Ireland with contrasting subsurface lithologies (sandstone vs. slate) and landuse. Denitrification capacity was assessed by measuring concentration and distribution patterns of nitrogen (N) species, aquifer hydrogeochemistry, stable isotope signatures and aquifer hydraulic properties. A hierarchy of scale whereby physical factors including agronomy, water table elevation and permeability determined the hydrogeochemical signature of the aquifers was observed. This hydrogeochemical signature acted as the dominant control on denitrification reaction progress. High permeability, aerobic conditions and a lack of bacterial energy sources in the slate catchment resulted in low denitrification reaction progress (0–32%), high NO3− and comparatively low N2O emission factors (EF5g1). In the sandstone catchment denitrification progress ranged from 4 to 94% and was highly dependent on permeability, water table elevation, dissolved oxygen concentration solid phase bacterial energy sources. Denitrification of NO3 − to N2 occurred in anaerobic conditions, while at intermediate dissolved oxygen; N2O was the dominant reaction product. EF5g1 (mean: 0.0018) in the denitrifying sandstone catchment was 32% less than the IPCC default. The denitrification observations across catchments were supported by stable isotope signatures. Stream NO3− occurrence was 32% lower in the sandstone catchment even though N loading was substantially higher than the slate catchment.Teagasc Walsh Fellowship Programm

Integrated climate-chemical indicators of diffuse pollution from land to water

Management of agricultural diffuse pollution to water remains a challenge and is influenced by the complex interactions of rainfall-runoff pathways, soil and nutrient management, agricultural landscape heterogeneity and biogeochemical cycling in receiving water bodies. Amplified cycles of weather can also influence nutrient loss to water although they are less considered in policy reviews. Here, we present the development of climate-chemical indicators of diffuse pollution in highly monitored catchments in Western Europe. Specifically, we investigated the influences and relationships between weather processes amplified by the North Atlantic Oscillation during a sharp upward trend (20102016) and the patterns of diffuse nitrate and phosphorus pollution in rivers. On an annual scale, we found correlations between local catchment-scale nutrient concentrations in rivers and the influence of larger, oceanic-scale climate patterns defined by the intensity of the North Atlantic Oscillation. These influences were catchment-specific showing positive, negative or no correlation according to a typology. Upward trends in these decadal oscillations may override positive benefits of local management in some years or indicate greater benefits in other years. Developing integrated climate-chemical indicators into catchment monitoring indicators will provide a new and important contribution to water quality management objectives

Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr 4 NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC), 3.17wt.% propylene carbonate (PC), 19.0 wt.% of Pr 4 NI, and 1.9wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 x 10 -3 S cm -1. The dye-sensitized solar cell (DSSC) fabricated with this electrolyte exhibits an efficiency of 3.5% with.. SC of 7.38mAcm -2,.. OC of 0.72V, and fill factor of 0.66. When various amounts of lithium iodide (LiI) were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr 4 NI : LiI is 2 : 1. This cell has.. SC,.. OC and fill factor of 7.25mAcm -2, 0.77V and 0.67, respectively

Field scale phosphorus balances and legacy soil pressures in mixed-land use catchments

peer-reviewedReducing legacy soil phosphorus (P) is recognised as an effective measure to mitigate diffuse P losses from agricultural landscapes and alleviate trophic pressure to freshwaters systems. Accounting for the distribution of P within farms is critical in identifying fields of agronomic underperformance and/or environmental risk to water as a consequence of inadequately managed re-cycling of P. There is also a need to understand how P use and legacy soil P evolves under the Nitrates Action Programme (NAP) regulations from the European Union (EU) Nitrates Directive. In an Irish case study the aim was to provide a systematic and detailed audit of P balance and soil P responses and trends in two mixed land use agricultural catchments (Arable A and B) across a four year study period. Driven by increased mineral P inputs the field balances in the Arable A catchment had an average surplus P, ranging from 1.9 to 7.5 kg ha−1 yr−1. However, between the study period 2010 to 2013, the average soil test P (STP) levels declined, with the area of excessive soil P concentrations decreasing by 8%. Similarly, in the Arable B catchment the average annual P inputs increased the surplus field P from -0.42 to 25.5 kg ha−1 yr−1, but the area of excessive soil P concentrations increased by 4%. In part, this increase is attributed to some fields receiving excess applications of organic nutrient forms above crop requirements. Whilst, the legacy soil P declined in the Arable A catchment indicating a response to NAP, for both catchments it is evident that the distribution of P sources within farms was poor and P inputs often did not match crop and soil P requirements at the field scale. This study highlights the need for improved support to knowledge transfer mechanisms that can deliver better farm and soil specific nutrient management planning strategies. Without this consideration, achieving the dual benefits of improvement to water quality and increased crop output from agricultural landscapes will be restricted.Department of Agricultural, Food and the Marine in Irelan

Demonstration of lightweight gamma spectrometry systems in urban environments

Urban areas present highly complex radiation environments; with small scale features resulting from different construction materials, topographic effects and potential anthropogenic inputs from past industrial activity or other sources. Mapping of the radiation fields in urban areas allows a detailed assessment of exposure pathways for the people who live and work there, as well as locating discrete sources of activity that may warrant removal to mitigate dose to the general public. These areas also present access difficulties for radiometric mapping using vehicles or aircraft. A lightweight portable gamma spectrometry system has been used to survey sites in the vicinity of Glasgow to demonstrate the possibilities of radiometric mapping of urban areas, and to investigate the complex radiometric features such areas present. Variations in natural activity due to construction materials have been described, the presence of 137Cs used to identify relatively undisturbed ground, and a previously unknown NORM feature identified. The effect of topographic enclosure on measurements of activity concentration has been quantified. The portable system is compared with the outputs that might be expected from larger vehicular or airborne systems. For large areas airborne surveys are the most cost effective approach, but provide limited spatial resolution, vehicular surveys can provide sparse exploratory data rapidly or detailed mapping of open areas where off-road access is possible. Backpack systems are ideally suited to detailed surveys of small areas, especially where vehicular access is difficult