In-season mineral nutrient management of citrus by early (spring/summer) season sampling of leaves, fruitlets, and flowers

Thesis (MScAgric)--Stellenbosch University, 2022.ENGLISH ABSTRACT: Tree nutrient supply must be optimal to ensure the production of high yields of quality fruit. Fertiliser schedules are adjusted based on the results of various diagnostic tools – one such tool is analysis of plant parts. In the South African citrus industry, leaves from fruit bearing shoots are sampled and analysed during autumn, at which time the season’s fertiliser schedule has often been implemented either entirely or with only a small portion outstanding. The results of autumn analyses are used to adjust the fertiliser schedule of the following season. This is a retrospective method of managing tree nutrient status and there is a need for a more proactive method. The latter could potentially be achieved by sampling earlier (spring/summer) in the season, thereby allowing for adjustment of current season fertiliser schedules. In this study, the relationship between early season nutrient concentration in leaves, fruitlets, and flowers and final fruit nutrient concentration at harvest, was evaluated. Five treatments were applied, viz. the normal fertiliser schedule (control), 200% N of the control, 200% P of the control, 200% K of the control, and 200% Mg of the control. The two trial sites used were in separate geographic regions of South Africa; Nelspruit of the Mpumalanga province which has a sub-tropical climate and summer rainfall, in a ‘Midknight’ Valencia orchard and De Wet of the Western Cape province which has a mediterranean-type climate and winter rainfall, in an ‘Orri’ mandarin orchard. Leaf, fruitlet, and flower nutrient analysis results did not indicate significant reactions to the nutrient treatments. However, the N- and K-treatments did induce a response. The N-treatment produced an immediate response in leaf and fruitlet N concentration, which was maintained during the second season. A response to the K-treatment was only observed in leaf K content during the second season. ‘Orri’ mandarins were less responsive to the trial treatments compared to the ‘Midknight’ Valencias, with only the K-treatment producing a response in leaf nutrient content and only during the second season. Correlations between nutrient analysis of different plant parts and final fruit nutrient concentration was not strong. The effect of excessive application rates of nutrients on final fruit quality, and the relationship between early season analysis of leaves, fruitlets, and flowers and that of final fruit quality were also evaluated. The treatments produced significant differences within quality parameters (rind colour, TSS, TA, fruit size) for the control and the N- and K-treatments of both the ‘Midknight’ trial and the ‘Orri’ trial. Most notably, in the ‘Orri’ trial where N was liberally applied and K was moderately applied, the K-treatment response on final fruit quality was strongly expressed during the second season. Nutrient content of leaves from fruit bearing and non-fruit bearing shoots were compared. In both cultivars, leaves from non-fruit bearing shoots had significantly higher concentrations of N, P and K, whereas the Ca levels were higher in the leaves from fruit bearing shoots. Additionally, leaves from non-fruit bearing shoots were more responsive to changes in nutrient supply. This study suggests that the accepted sufficiency ranges of leaf nutrient concentration might be too wide, and that the expected treatment responses might only occur at lower nutrient application rates. It is expected that correlations with final fruit nutrient concentration will be stronger at lower leaf, fruitlet, and flower nutrient concentrations, due to the law of diminishing returns which states that at a certain point additional changes to a system will yield smaller and smaller improvements resulting. In addition, it was found that, a significant change in nutrient concentration within leaves and fruit does not necessarily have to precede a significant fruit quality response, suggesting that current leaf nutrient norms might be too wide to predict nutrient related fruit quality responses under all circumstances.AFRIKAANSE OPSOMMING: Boomvoeding moet optimaal wees om die produksie van hoë opbrengste van goeie kwaliteit vrugte te verseker. Kunsmisskedules word aangepas op grond van die resultate van verskeie diagnostiese hulpmiddels – een so 'n hulpmiddel is ontleding van plantdele. In die Suid-Afrikaanse sitrusbedryf word blare van vrugdraende lote gedurende herfs gemonster en ontleed. Teen hierdie tyd is die seisoen se bemestingsprogram heeltemal óf grootendeels afgehandel. Die resultate van herfsontledings word dus gebruik om die bemestingsprogram vir die volgende seisoen aan te pas. Dit is 'n retrospektiewe benadering om boomvoeding te bestuur en daar is 'n behoefte vir 'n meer proaktiewe metode. Laasgenoemde kan moontlik bewerkstellig word deur vroeër (lente/somer) in die seisoen blare te monster, sodat aanpassings reeds in die huidige seisoen gemaak kan word. In hierdie studie is die verband tussen voedingselementkonsentrasie in blare wat vroeg gemonster word, vruggies en blomme en die finale elementkonsentrasie in die vrugte tydens oes geëvalueer. Vyf behandelings is toegepas, nl. die normale bemestingsprogram deur die produsent gevolg (kontrole), stikstofbemesting teen 200% van die kontrole, fosfaatbemesting teen 200% van die kontrole, kaliumbemesting teen 200% van die kontrole, en magnesiumbemesting teen 200% van die kontrole. Die twee proefpersele wat gebruik was, was in afsonderlike geografiese streke van Suid-Afrika; naamlik in Nelspruit (Mpumalanga) wat 'n sub-tropiese klimaat en somerreënval het is ‘n 'Midknight' Valencia-boord gebruik terwyl daar in De Wet (Wes-Kaap wat 'n mediterreense-tipe klimaat en winterreënval het) 'n 'Orri' mandarynboord gebruik is. Blom minerale voedingselementontledings het nie betekenisvolle reaksies op die bemestingsbehandelings getoon nie. Die N- en K-behandelings het egter wel 'n reaksie in die blare se samestelling geïnduseer. Die N-behandeling het 'n onmiddellike reaksie in blaar- en vrug-N-konsentrasie gelewer, wat ook gedurende die tweede seisoen gehandhaaf is. 'n Reaksie op die K-behandeling is slegs in blare se K-inhoud gedurende die tweede seisoen waargeneem. Die 'Orri' mandaryne het ‘n swakker reaksie op die proefbehandelings getoon in vergelyking met die 'Midknight' Valencias, te wete dat slegs die K-behandeling 'n reaksie in blare se elementinhoude geïnduseer het, en dan ook slegs gedurende die tweede seisoen. Korrelasies tussen elementontledings van verskillende plantdele en finale konsentrasie in die vrugte was swak. Die effek van oormatige toedienings van voedingselemente op vrugkwaliteit, en die verband tussen vroeë seisoen-analise van blare, vruggies en blomme en dié van finale vrugkwaliteit is ook geëvalueer. Die behandelings het beduidende verskille in skilkleur, TSS, TA en vruggrootte tussen die kontrole en die N- en K-behandelings opgelewer vir beide die proefblokke. In die 'Orri'-proef, waar N teen baie hoë hoeveelhede toegedien was en K in matige hoeveelhede, was die effek op die K-behandelingsreaksie op finale vrugkwaliteit opmerklik gedurende die tweede seisoen. Elementinhoud van blare van vrugdraende en nie-vrugdraende lote is vergelyk. In beide kultivars het blare van nie-vrugdraende lote aansienlik hoër konsentrasies N, P en K gehad, terwyl die Ca- vlakke hoër was in die blare van vrugdraende lote. Boonop was blare van nie-vrugdraende lote meer sensitief op veranderinge in voedingstoftoedienings. Hierdie studie dui daarop dat die aanvaarde norme vir blare se elementinhoude te wyd kan wees, en dat behandelingsreaksies waarskynlik eerder by laer kunsmis peile waargeneem sal word. Daar word verwag dat korrelasies met finale vrug elementkonsentrasies sterker sal wees by laer blaar-, vrug- en blomkonsentrasies as gevolg van die wet van afnemende opbrengste wat sê dat op 'n sekere punt, bykomende veranderinge aan 'n stelsel kleiner en kleiner verbeteringe sal oplewer. Daarbenewens is gevind dat 'n beduidende verandering in konsentrasie van voedingstowwe binne blare en vrugte nie noodwendig 'n beduidende vrugkwaliteit-reaksie tot gevolg sal hë nie. Dit dui daarop huidige blaarnorme te wyd kan wees om ‘n verband tussen die boom se voedingstatus en vrugkwaliteit te kan voorspel.Master

Mesenchymal stromal cells secretome restores bioenergetic and redox homeostasis in human proximal tubule cells after ischemic injury

Background: Ischemia/reperfusion injury is the leading cause of acute kidney injury (AKI). The current standard of care focuses on supporting kidney function, stating the need for more efficient and targeted therapies to enhance repair. Mesenchymal stromal cells (MSCs) and their secretome, either as conditioned medium (CM) or extracellular vesicles (EVs), have emerged as promising options for regenerative therapy; however, their full potential in treating AKI remains unknown. Methods: In this study, we employed an in vitro model of chemically induced ischemia using antimycin A combined with 2-deoxy-d-glucose to induce ischemic injury in proximal tubule epithelial cells. Afterwards we evaluated the effects of MSC secretome, CM or EVs obtained from adipose tissue, bone marrow, and umbilical cord, on ameliorating the detrimental effects of ischemia. To assess the damage and treatment outcomes, we analyzed cell morphology, mitochondrial health parameters (mitochondrial activity, ATP production, mass and membrane potential), and overall cell metabolism by metabolomics. Results: Our findings show that ischemic injury caused cytoskeletal changes confirmed by disruption of the F-actin network, energetic imbalance as revealed by a 50% decrease in the oxygen consumption rate, increased oxidative stress, mitochondrial dysfunction, and reduced cell metabolism. Upon treatment with MSC secretome, the morphological derangements were partly restored and ATP production increased by 40–50%, with umbilical cord-derived EVs being most effective. Furthermore, MSC treatment led to phenotype restoration as indicated by an increase in cell bioenergetics, including increased levels of glycolysis intermediates, as well as an accumulation of antioxidant metabolites. Conclusion: Our in vitro model effectively replicated the in vivo-like morphological and molecular changes observed during ischemic injury. Additionally, treatment with MSC secretome ameliorated proximal tubule damage, highlighting its potential as a viable therapeutic option for targeting AKI

Lunchlezing NoorderRuimte

Presentatie t.b.v. de lunchlezing van Kenniscentrum NoorderRuimte over het onderzoek wat gedaan wordt bij het Living Lab van Groningen Airport Eelde

Living lab Groningen Airport Eelde

Het Living Lab Groningen Airport Eelde (LLGAE) wil realiseren dat partners uit overheid, onderzoek, onderwijs, ondernemers en omgeving in gezamenlijkheid en gelijkwaardigheid, werken aan innovatieve oplossingen, experimenten en opgaven in de ruimtelijke en economische context van Groningen Airport Eelde, zodanig dat alle partijen bijdragen aan en profiteren van elkaar.De kennisvragen van LLGAE zijn te groeperen rond vooral de thema’s ruimtelijke inrichting, economische ontwikkeling inclusief recreatie en toerisme, energie en duurzaamheid, en mobiliteit

Direct geomechanical inversion from geodetic data: A new method for a regularised direct inversion to geomechanical parameters using measurements from optical leveling campaigns

Subsidence of the ground surface, caused by hydrocarbon production, compaction of soft ground layers or other subsidence causes, is a timely topic in the Netherlands. Geodetic measurements of the surface can help us improve our knowledge of the subsurface; this process is called geomechanical inversion. Improved knowledge on the subsurface is needed for example to improve deformation predictions and to safeguard subsurface and surface infrastructure. Related works in this domain use derivatives of geodetic measurements as input for their inversion methodologies, but not the measurements themselves. Performing geomechanical inversion with derivatives of geodetic measurements introduces correlations in the covariance matrix of the data, making error propagation into the geomechanical estimates more complex. Defining a direct relationship between measurements and geomechanical estimates and subsequently inverting this relationship, makes the error propagation less complex. This thesis presents a new methodology that can be used to estimate reservoir geomechanical parameters through direct inversion using measurements from optical leveling campaigns. In the context of this thesis, a direct inversion is an inversion of a linear relationship between data and measurements. In this thesis, we propose and test a workflow for the estimation of a simplified set of geomechanical parameters. Part of the workflow is an extensive testing procedure of the geodetic data. A Geertsma nucleus-of-strain model is used to express a source parameter term in function of optical leveling measurements. This source parameter term is a lumped term and consists of a volume term, a pressure term, and several elastic rock parameter terms. This system is inverted using a Tikhonov regularization with a spatial penalty term. The methodology is applied to optical leveling data from a case study (the Norg and Roden gas fields in the northern Netherlands) and shows promising results. The RMS between modeled and measured subsidence for the most promising parameterization is 3.0 mm. The proposed methodology leads to geomechanical estimates with formal quality description, that could improve geomechanical models and subsequently leads to a better understanding of the subsurface and better subsidence predictions. The geomechanical parameter that is estimated is lumped and without additional information, it is impossible to differentiate between individual compaction parameter terms. Feeding the problem more information might also relax the need for regularization but can lead to the introduction of bias. We believe that the framework proposed in this work can be a good starting point for further research that uses geodetic measurements directly as input for a geomechanical inversion

Evaluating the applicability of an alkaline amino acid leaching process for base and precious metal leaching from printed circuit board waste

Thesis (MEng)--Stellenbosch University, 2018.ENGLISH SUMMARY: The recovery of metals from waste printed circuit boards (PCBs), a key component in electronic equipment, is beneficial from both an environmental and economic perspective. Current hydrometallurgical processing routes utilise strong mineral acids and cyanide or halides, which pose environmental hazards. Amino acids have been proposed as alternative lixiviants with a lower environmental impact. This project aimed to evaluate the applicability of the amino acid leaching process for the dissolution of metals from PCB waste. Bench-scale leach tests were performed to determine the rate, extent and selectivity of base and precious metal leaching at different conditions. Glycine, the simplest amino acid, was used as lixiviant. The relatively low solubility of copper in the glycine system limited the pulp density during base metal leach tests to 25 g PCBs/L. When air was used as oxidant, copper dissolution was initially independent of both temperature and glycine concentration. It was suggested that initial copper dissolution in the air system, at 1 M glycine, was limited by oxygen diffusion through the solid-liquid boundary layer. As the reaction progressed, oxygen diffusion through the CuO intermediate was believed to be rate-limiting. Increasing the temperature and glycine concentration in the presence of air, increased the rate of CuO removal through copper-glycine complex formation, which, in turn, reduced the resistance to oxygen diffusion to the reaction surface. When pure oxygen was used as oxidant, increasing the temperature from 25°C to 60°C increased copper dissolution after 22 hours by approximately 50%. Increasing the glycine concentration above 1 M, in the presence of pure oxygen, had no effect on copper dissolution. 81% copper dissolution was achieved after 22 hours at the optimal conditions of 60°C, 1 M glycine, using pure oxygen as oxidant. At these conditions, co-extraction of gold was 1.3%. Precious metal leach tests were performed using the residue from the base metal leach tests as feed, with H2O2 fed continuously as oxidant. Increasing the temperature (up to 90°C), glycine concentration (0.1 M to 0.5 M) and pH (11.5 to 12.5) had no significant effect on gold extraction, with less than 2% gold dissolution achieved after 96 hours. Further tests were performed on pure gold foils to determine whether the presence of copper in the PCBs inhibited gold dissolution. Leaching from gold foils, however, did not improve gold dissolution and it was concluded that gold leaching with glycine is not technically feasible. A suggested flowsheet for metal extraction was validated experimentally. Small pilot-scale leach tests were performed at the optimal conditions identified from the bench-scale base metal leach tests (60°C, 1 M glycine, with pure oxygen as oxidant). Due to poor mass transfer of oxygen into solution in the small pilot-scale leach tests, two stages (each with a duration of 41 – 52 hours) were required to achieve 78% copper dissolution. In a subsequent leaching stage, 38% gold dissolution was achieved after 96 hours, with the addition of 0.04 M NaCN to 0.13 M glycine at 25°C, using air as oxidant. Further optimisation of process variables are required to maximise gold leaching in the glycine-cyanide system.AFRIKAANSE OPSOMMING: Die herwinning van metale vanuit afval gedrukte stroombaan borde (GSBs), ‘n sleutel onderdeel van elektroniese apparaat, is voordelig vanuit beide omgewings en ekonomiese oogpunte. Onlangse hidrometallurgiese prosesroetes gebruik sterk mineraalsure en sianied of haliede, wat omgewingsgevare inhou. Aminosure is al voorgestel as plaasvervanger loogmiddels met ‘n verminderde impak op die omgewing. Hierdie projek het beoog om die toepaslikheid van die aminosuur loogproses op die loging van metale vanuit GSB-afval te evalueer. Kleinskaalse loogtoetse is uitgevoer om die tempo, hoeveelheid en selektiwiteit van basis- en edelmetaal loging onder verskillende omstandighede te bepaal. Glisien, die eenvoudigste aminosuur, is gebruik as loogmiddel. Die betreklike lae oplosbaarheid van koper in die glisienstelsel het die pulpdigtheid tydens basismetaal loogtoetse tot 25 g GSBs/L beperk. Met lug as oksidant was die loging van koper aanvanklik onafhanklik van beide temperatuur en glisien-konsentrasie. Daar is aangevoer dat aanvanklike koper-loging in die lugstelsel, teen 1 M glisien, deur suurstof diffusie deur die grenslaag beperk is. Met die vordering van die reaksie, het die suurstof diffusie deur die CuO-intermediêr tempo-beperkend geword. Verhoging van die temperatuur en ʼn toename in die glisien-konsentrasie in die aanwesigheid van lug het die CuO-verwydering deur koper-glisien kompleks vorming versnel, wat op sy beurt die weerstand teen suurstof diffusie na die reaksie-oppervlak verminder het. Met die gebruik van suiwer suurstof as oksidant het die vehoging in temperatuur van 25°C tot 60°C koper-loging na 22 uur met ongeveer 50% vermeerder. Die vermeerdering van glisien tot bokant 1 M, in die aanwesigheid van suurstof, het geen invloed op koper-loging gehad nie. 81% koper-loging is bereik na 22 uur in die gunstigste toestande van 60°C, 1 M glisien-konsentrasie, met die gebruik van suiwer suurstof as oksidant. In hierdie toestande is die mede-ekstraksie van goud 1.3%. Edelmetaal loogtoetse is uitgevoer deur die oorblyfsels van die basismetaal loogtoetse as voermiddel te gebruik, met ‘n kontinue voer van H2O2 as oksidant. Verhoging van die temperatuur (tot 90°C), glisien-konsentrasie (0.1 M tot 0.5 M) en pH (11.5 tot 12.5) het geen noemenswaardige uitwerking op goud-ekstraksie gehad nie, met minder as 2% goud-loging na 96 uur. Verdere toetse is op suiwer goudfoelie gedoen om te bepaal of die aanwesigheid van koper in die GSBs goud-loging inperk. Die loging vanuit goudfoelie het egter nie die goud-loging verbeter nie en die slotsom is bereik dat goudloging met glisien nie tegnies lewensvatbaar is nie. ‘n Voorgestelde prosesroete vir metaal ekstraksie is eksperimenteel bevestig. Grootskaalse loogtoetse in optimale toestande, bepaal deur die kleinskaalse basismetaal loogtoetse (60°C, 1 M glisien, met suiwer suurstof as oksidant), is uitgevoer. As gevolg van die skamele massa oordrag van suurstof tot in oplossing gedurende die grootskaalse loogtoetse, was twee fases (wat elk 41 – 52 uur duur) nodig om 78% koper-loging te bereik. In ‘n opvolgende loogfase is 38% goud-loging bereik na 96 uur, met die byvoeging van 0.04 NaCN by 0.13 M glisien teen 25°C, met lug as oksidant. Verdere optimering van proses veranderlikes word benodig om die goudloging in die glisien-sianied stelsel te maksimeer

Living lab Groningen Airport Eelde

Het Living Lab Groningen Airport Eelde (LLGAE) wil realiseren dat partners uit overheid, onderzoek, onderwijs, ondernemers en omgeving in gezamenlijkheid en gelijkwaardigheid, werken aan innovatieve oplossingen, experimenten en opgaven in de ruimtelijke en economische context van Groningen Airport Eelde, zodanig dat alle partijen bijdragen aan en profiteren van elkaar. De kennisvragen van LLGAE zijn te groeperen rond vooral de thema’s ruimtelijke inrichting, economische ontwikkeling inclusief recreatie en toerisme, energie en duurzaamheid, en mobiliteit