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8th World Conference on Photovoltaic Energy Conversion; 40-43, We investigate TOPCon-like passivating contacts using silicon from electron-beam evaporation (E-Beam evaporation), plasma doping and wet-chemical ozone oxides. Results show iVoc values up to 722 mV for symmetrical lifetime samples and 708 mV for cells using the passivating contact on the rear side. SIMS measurements were performed on samples before and after annealing to investigate the distribution of phosphorous within the samples for different process conditions. Synchrotron-based XPS measurements were performed to investigate compositional changes both for the as-grown oxide and after poly-Si formation and etch-back of the poly-Si layer. A clear decrease in the intensity of the transitional area can be observed between non-annealed and annealed samples, which is assumed to be the reason for the non-existent surface passivation quality of freshly grown silicon oxide layers.

Background Population-based cancer registries are a critical reference source for the surveillance and control of cancer. Cancer registries work extensively with the internationally recognised TNM classification system used to stage solid tumours, but the system is complex and compounded by the different TNM editions in concurrent use. TNM ontologies exist but the design requirements are different for the needs of the clinical and cancer-registry domains. Two TNM ontologies developed specifically for cancer registries were designed for different purposes and have limitations for serving wider application. A unified ontology is proposed to serve the various cancer registry TNM-related tasks and reduce the multiplication effects of different ontologies serving specific tasks. The ontology is comprehensive of the rules for TNM edition 7 as required by cancer registries and designed on a modular basis to allow extension to other TNM editions. Results A unified ontology was developed building on the experience and design of the existing ontologies. It follows a modular approach allowing plug in of components dependent upon any particular TNM edition. A Java front-end was developed to interface with the ontology via the Web Ontology Language application programme interface and enables batch validation or classification of cancer registry records. The programme also allows the means of automated error correction in some instances. Initial tests verified the design concept by correctly inferring TNM stage and successfully handling the TNM-related validation checks on a number of cancer case records, with a performance similar to that of an existing ontology dedicated to the task. Conclusions The unified ontology provides a multi-purpose tool for TNM-related tasks in a cancer registry and is scalable for different editions of TNM. It offers a convenient way of quickly checking validity of cancer case stage information and for batch processing of multi-record data via a dedicated front-end programme. The ontology is adaptable to many uses, either as a standalone TNM module or as a component in applications of wider focus. It provides a first step towards a single, unified TNM ontology for cancer registries.

Featured Application The ontology provides a standalone application for validating cases of multiple primary tumours against the international rules. The ontology can also be incorporated into the suite of ontologies planned for devolving to the local cancer-registry level the validation process of the variables contributing to the common European-harmonised data set and thereby help accelerate the availability of data for pan-European and inter-regional comparison. Population-based cancer registry data provide a key epidemiological resource for monitoring cancer in defined populations. Validation of the data variables contributing to a common data set is necessary to remove statistical bias; the process is currently performed centrally. An ontology-based approach promises advantages in devolving the validation process to the registry level but the checks regarding multiple primary tumours have presented a hurdle. This work presents a solution by modelling the international rules for multiple primary cancers in description logic. Topography groupings described in the rules had to be further categorised in order to simplify the axioms. Description logic expressivity was constrained as far as possible for reasons of automatic reasoning performance. The axioms were consistently able to trap all the different types of scenarios signalling violation of the rules. Batch processing of many records were performed using the Web Ontology Language application programme interface. Performance issues were circumvented for large data sets using the software interface to perform the reasoning operations on the basis of the axioms encoded in the ontology. These results remove one remaining hurdle in developing a purely ontology-based solution for performing the European harmonised data-quality checks, with a number of inherent advantages including the formalisation and integration of the validation rules within the domain data model itself.

In situ phytoremediation of municipal biosolids is a promising alternative to land spreading and landfilling during decommissioning of end-of-life municipal lagoons. Plant root simulator (PRS) probes can be used to examine nutrient availability during phytoremediation, but their use under wetland conditions is limited. This study examined nutrient availability using PRS probes during phytoremediation of biosolids vegetated with cattail. The probes were buried in the sediment for seven sequential 2-wk burial periods beginning in June 2014. Plants were harvested to determine biomass yield and nutrient content. Nitrogen supply rate did not change significantly with sampling period in June and July (4.5 to 5.9 μg cm–² [2 wk]–¹) but increased thereafter to 11.8 μg cm–² (2 wk)–¹. Phosphate supply rate (20.5 to 24.2 μg cm–² [2 wk]–¹) did not differ significantly among sampling times. Cumulative supply rates of the macronutrients N, P, K, Ca and Mg (r = 0.77–0.92) and the micronutrients B, Fe, and Mn (r = 0.7–0.81) were highly correlated with cattail uptake, while the correlation was weaker for Cu (r = 0.42) and Zn (r = 0.40). Maximum attainable biomass yield (0.87 kg m–²) coincided with the period of maximum nutrient uptake, indicating that harvesting cattail between late August and early September maximizes nutrient removal. In situ burial of PRS probes appears to be an effective method of measuring availability of macronutrients but may have limited effectiveness for Cu and Zn.

Spreading biosolids on farmland can be an effective and beneficial option for managing end-of-life municipal lagoons. Where the spreading of biosolids on farmland is restricted or unavailable, in situ phytoremediation could be a sustainable alternative. This study examined nitrogen (N) and phosphorus (P) phytoextraction by cattail ( spp.) from biosolids in a wetland constructed within a lagoon cell previously used for primary treatment of municipal wastewater. The effect of harvesting season as well as harvest frequency on N and P removal were evaluated. Forty-eight 4-m plots within the constructed wetland were used to determine the effect of cattail harvest frequency on plant N and P phytoextraction. Harvesting twice per season resulted in a 50 to 60% decrease in phytoextraction of N and P relative to a single harvest per season, which produced biomass yields of 0.58 to 0.6 kg m per year and accumulated 36.7 g N m and 5.6 g P m over the 4-yr period. Compared with August, harvesting cattails in November or April reduced N and P phytoextraction by 63 to 85%. These results demonstrate that phytoextraction of nutrients is more effective with a single harvest compared with two harvests per season. Additionally, we found that while harvesting in November and April is appealing logistically (since the wetland is frozen and provides easier access to harvest equipment), nutrient removal rates are significantly reduced.

Land spreading of biosolids as a disposal option is expensive and can disperse pathogens and contaminants in the environment. This growth room study examined phytoremediation using switchgrass (Panicum virgatum L.) and cattail (Typha latifolia L.) as an alternative to land spreading of biosolids. Seedlings were transplanted into pots containing 3.9 kg of biosolids (dry wt.). Aboveground biomass (AGB) was harvested either once or twice during each 90-day growth period. Switchgrass AGB yield was greater with two harvests than with one harvest during the first 90-day growth period, whereas cattail yield was not affected by harvest frequency. In the second growth period, harvesting frequency did not affect the yield of either plant species. However, repeated harvesting significantly improved nitrogen (N) and phosphorus (P) uptake by both plants in the first period. Phytoextraction of P was significantly greater for switchgrass (3.9% of initial biosolids P content) than for cattail (2.8%), while plant species did not have a significant effect on N phytoextraction. The trace element accumulation in the AGB of both plant species was negligible. Phytoextraction rates attained in this study suggest that phytoremediation can effectively remove P from biosolids and offers a potentially viable alternative to the disposal of biosolids on agricultural land.

In situ phytoremediation of municipal biosolids is a promising alternative to the land spreading and landfilling of biosolids from end-of-life municipal lagoons. Accumulation and partitioning of dry matter, nitrogen (N), phosphorus (P), and trace elements were determined in aboveground biomass (AGB) and belowground biomass (BGB) of switchgrass (Panicum virgatum L.) to determine the harvest stage that maximizes phytoextraction of contaminants from municipal biosolids. Seedlings were transplanted into 15-L plastic pails containing 3.9 kg (dry wt.) biosolids. Biomass yield components and contaminant concentrations were assessed every 14 days for up to 161 days. Logistic model fits to biomass yield data indicated no significant differences in asymptotic yield between AGB and BGB. Switchgrass partitioned significantly more N and P to AGB than to BGB. Maximum uptake occurred 86 days after transplanting (DAT) for N and 102 DAT for P. Harvesting at peak aboveground element accumulation removed 5% of N, 1.6% of P, 0.2% of Zn, 0.05% of Cd, and 0.1% of Cr initially present in the biosolids. These results will contribute toward identification of the harvest stage that will optimize contaminant uptake and enhance in situ phytoremediation of biosolids using switchgrass.

Proceedings of Manitoba's Undergraduate Science and Engineering Research, Vol 4 (2018): Special Issue: Agriculture

Managing biosolids from end-of-life municipal lagoons is a major challenge for many small communities where landfilling or spreading of biosolids on farmland is restricted. Contaminant removal via phytoextraction may be a viable remediation option for end-of-life lagoons in such communities. This study examined the effect of harvest frequency (once or twice per season) on cattail ( L.) biomass yield and N and P removal under a terrestrial phytoremediation system designed to treat the dewatered secondary cell of a municipal lagoon in Manitoba, Canada. Cattail was harvested once or twice per season from eight vegetation transects, each divided into two plots (2.5 × 2.5 m) to accommodate the two harvest frequencies. Biomass yields were greater for the single harvest (5.7 t ha yr) than for two harvests per season (4.8 t ha yr). This was mirrored by N phytoextraction, which was also greater for the single harvest (71 kg ha yr) than the two-harvest frequency (58 kg ha yr). Phosphorus phytoextraction varied with year of harvest and ranged from 8 to 14 kg ha yr. Cumulative N and P phytoextraction amounts during the 5 yr were 330 kg N ha and 57 kg P ha. A greater fraction of N (51-91 kg ha yr) and P (23-40 kg ha yr) was sequestered in the belowground biomass (11-17 t ha yr) and therefore was not removed by harvesting. These results show that phytoremediation using cattail is a viable option for managing N and P in end-life lagoons.

Municipal biosolids in end-of-life lagoons can release phosphorus (P) to floodwater and contribute to P enrichment of receiving waters if the floodwater is released. Phosphorus release to floodwater is well-documented in agricultural and wetland soils, but information on flooding depth and timing effects on P release from flooded biosolids in end-of life municipal lagoons is currently lacking. This 42-day experiment utilized intact, cattail-(Typha latifolia L.) vegetated biosolids cores (45.7-cm diameter by 60-cm height) to investigate the effects of flooding depth (5, 15, and 25 cm) on P release from biosolids and on P fractionation in pore water, floodwater, and biosolids upon flooding of municipal biosolids. Averaged across flooding depths, TP rapidly increased from the onset of flooding (0.45 mg L−1) to day 14 (1.8 mg L−1) and remained relatively constant thereafter (1.8–1.9 mg L−1). Dissolved reactive P was the major fraction of P in pore water and floodwater. Flooding for more than 3 days resulted in the release of > 0.5 mg L−1 dissolved reactive P (DRP) to floodwater. Phosphorus release was positively correlated with Fe and Mn concentrations in pore water and with water-extractable inorganic P, labile inorganic P, and Fe/Al-bound organic P concentrations in biosolids. Results indicate that P release to floodwater; hence, risk to receiving water bodies, is minimal during the first 3 days of flooding. This suggests that release of floodwater from the lagoon presents minimal adverse impact to receiving surface waters if done during the early stages (

Biomass and contaminant accumulation and partitioning in plants determine the harvest stage for optimum contaminant uptake during phytoremediation of municipal biosolids. This wetland microcosm bioassay characterized accumulation and partitioning of biomass, nutrients (N and P), and trace elements (Zn, Cu, Cr, and Cd) in cattail ( L.) in a growth room. Four cattail seedlings were transplanted into each 20-L plastic pail containing 3.9 kg (dry wt.) biosolids from an end-of-life municipal lagoon. A 10-cm-deep water column was maintained above the 12-cm-thick biosolids layer. Plants were harvested every 14 d over a period of 126 d for determination of aboveground biomass (AGB) and belowground biomass (BGB) yields, along with contaminant concentrations in these plant tissues. Logistic model fits to biomass yield data indicated no significant difference in asymptotic yield between AGB and BGB. Aboveground biomass accumulated significantly greater amounts of N and P and lower amounts of trace elements than BGB. Maximum N accumulation in AGB occurred 83 d after transplanting (DAT), and peak P uptake occurred at 86 DAT. Harvesting at maximum aboveground accumulation removed (percent of the initial element concentration in the biosolids) 4% N, 3% P, 0.05% Zn, 0.6% Cu, 0.1% Cd, and 0.2% Cr. Therefore, under the conditions of this study, phytoremediation would be most effective if cattail is harvested at 86 DAT. These results contribute toward the identification of the harvest stage that will optimize contaminant uptake and enhance in situ phytoremediation of biosolids using cattail.

Bioavailability of phosphorus (P) in soils is controlled by, inter alia, the presence of iron (Fe) and aluminum (Al) oxides, which readily bind with P. Biochar has been suggested for minimizing P sorption to oxides and, therefore, improving P availability to plants. However, the kinetics and temperature dependence of biochar influence on P sorption are poorly understood. The objective of this study was, therefore, to determine the kinetics and thermodynamics of P sorption by goethite as affected by biochar application at 0 and 40 g kg−1 oxide. Batch equilibration tests were run at 15, 25, and 35 °C, and solution P concentrations were measured 0.5, 1, 3, 6, 9, 12, and 24 h after the start of incubation. Sorption of P by the oxides followed pseudo-first-order kinetics. Biochar application enhanced cumulative P sorption by both oxides, and the increase was greater for Al-goethite. Phosphorus sorption increased as temperature increased from 15 to 25 °C but declined at 35 °C. Phosphorus sorption on biochar-ame...

In this paper, we describe the development of an International Space Station experiment, BioRock. The purpose of this experiment is to investigate biofilm formation and microbe–mineral interactions in space. The latter research has application in areas as diverse as regolith amelioration and extraterrestrial mining. We describe the design of a prototype biomining reactor for use in space experimentation and investigations on in situ Resource Use and we describe the results of pre-flight tests.