Improving Metribuzin Tolerance in Lentil (Lens culinaris)

Weeds are a major limitation to lentil (Lens culinaris Medik.) production worldwide with grain yield losses of up to 87% from weed competition. In broad-acre mechanized lentil production systems, weed control relies on herbicide application; however, limited options exist. This study identified, characterised and validated novel tolerance in lentil to the photosystem II (PSII) inhibitor herbicide, metribuzin. Field research involving variable sowing dates, induced shade treatments and metribuzin rate were conducted to understand soil and weather factors responsible for herbicide phytotoxicity in lentil. Analysis of soil and weather factors around the time of herbicide application to the cultivar PBA Flash suggested a combination of factors were involved. Heavy rainfall within 10 days of application, particularly on light textured soils or where soil moisture was low, was most strongly linked to plant damage. A higher level of selective tolerance to metribuzin than that currently present in commercial lentil cultivars is required. Two methods, germplasm screening using a hydroponic sand assay and field screening of a large mutated population of PBA Flash, were used to identify lines with improved tolerance to metribuzin compared to current cultivars. Dose response experiments found germplasm line SP1333 had GR50 (the rate required to reduce dry weight (DW) 50%) values up to four-fold that of PBA Flash. However, GR50 values were greater than 25-fold that of PBA Flash in mutant selections M009 and M043. A field study in Canada with 20 Canadian and Australian genotypes confirmed the improved tolerance level of the mutants. Dose response analysis of five PSII inhibiting herbicides and DNA sequencing of the psbA chloroplast gene was undertaken to quantify the spectrum and mechanism of herbicide tolerance in M009 and M043. Compared to PBA Flash, metribuzin tolerance was increased 33-fold in M043 and 10-fold in M009, but no additional tolerance to other herbicides. Nucleotide sequencing of the psbA gene of both mutants identified a substitution at position 751 compared to PBA Flash. The resulting deduced amino acid sequence indicated an Ala251Thr substitution as responsible for the metribuzin tolerance. The substitution is unique in mutagenised higher plants and is the first report of an induced psbA target site mutation in higher plants. Reciprocal F1, F2 and F3 populations developed from M009 and M043 with PBA Flash identified a maternal inheritance pattern, but with paternal leakage in approximately 20% of F1 phenotypes. Reciprocal BC1F2 and BC1F3 populations were developed to identify any fitness cost associated with the tolerance. Field experiments identified reductions in net assimilation rate, DW and grain yield (GY) in tolerant lines with a fitness cost of 20 to 40%. This finding is comparable with the fitness cost measured in triazine tolerant (TT) canola due to tolerance to the PSII inhibiting triazine herbicides. Agronomic field experiments over two years at contrasting sites in South Australia compared the plant growth and GY of M009 and M043 with PBA Flash and SP1333 to post-emergent metribuzin. Clear differences existed in the responses of M009 and M043 compared with PBA Flash and SP1333 to metribuzin rate across sites. This finding confirmed that the mutant genotypes have an agronomically useful level of tolerance to metribuzin in southern Australia. However, DW was generally reduced linearly with metribuzin rate in both M043 and M009 suggesting a level of herbicide sensitivity at higher rates on some soil types. All three lentil genotypes with improved metribuzin tolerance are in use as parents in Australian breeding programs. The higher level of tolerance and superior agronomic performance of M043 makes it the genotype of choice. Knowledge of the genetic controls of inheritance and associated fitness cost of the target site provided by this study will aid plant breeders in rapid and effective incorporation of the tolerance into agronomically accepted plant types. The potential of developing a metribuzin tolerant lentil industry in Australia, similar to that which has occurred in TT canola, now exists.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 201

Gradient Optics of subwavelength nanofilms

Propagation and tunneling of light through subwavelength photonic barriers, formed by dielectric layers with continuous spatial variations of dielectric susceptibility across the film are considered. Effects of giant heterogeneity-induced non-local dispersion, both normal and anomalous, are examined by means of a series of exact analytical solutions of Maxwell equations for gradient media. Generalized Fresnel formulae, visualizing a profound influence of gradient and curvature of dielectric susceptibility profiles on reflectance/transmittance of periodical photonic heterostructures are presented. Depending on the cutoff frequency of the barrier, governed by technologically managed spatial profile of its refractive index, propagation or tunneling of light through these barriers are examined. Nonattenuative transfer of EM energy by evanescent waves, tunneling through dielectric gradient barriers, characterized by real values of refractive index, decreasing in the depth of medium, is shown. Scaling of the obtained results for different spectral ranges of visible, IR and THz waves is illustrated. Potential of gradient optical structures for design of miniaturized filters, polarizers and frequency-selective interfaces of subwavelength thickness is considered

Conditions for the occurrence of acicular ferrite transformation in HSLA steels

For the class of steels collectively known as high strength low alloy (HSLA), an acicular ferrite (AF) microstructure produces an excellent combination of strength and toughness. The conditions for the occurrence of the AF transformation are, however, still unclear, especially the effects of austenite deformation and continuous cooling. In this research, a commercial HSLA steel was used and subjected to deformation via plane strain compression with strains ranging from 0 to 0.5 and continuous cooling at rates between 5 and 50 °C s −1 . Based on the results obtained from optical microscopy, scanning electron microscopy and electron backscattering diffraction mapping, the introduction of intragranular nucleation sites and the suppression of bainitic ferrite (BF) laths lengthening were identified as the two key requirements for the occurrence of AF transformation. Austenite deformation is critical to meet these two conditions as it introduces a high density of dislocations that act as intragranular nucleation sites and deformation substructures, which suppress the lengthening of BF laths through the mechanism of mechanical stabilisation of austenite. However, the suppression effect of austenite deformation is only observed under relatively slow cooling rates or high transformation temperatures, i.e., conditions where the driving force for advancing the transformation interface is not sufficient to overcome the austenite deformation substructures

Minimising treatment-associated risks in systemic cancer therapy

Aim of the review To review the consequences of drug-related problems (DRP) in systemic cancer therapy and identify specific contributions of the pharmacist to minimise treatment-associated risks. Method Searches in PubMed, Embase and the Cochrane Library were conducted. Bibliographies of retrieved articles were examined for additional references. Only papers in English between 1980 and 2007 were included. Results In systemic cancer therapy there is an enormous potential for DRP due to the high toxicity and the complexity of most therapeutic regimens. The most frequently reported DRP can be classified into adverse effects, drug–drug interactions, medication errors, and non-adherence. Pharmacists have enhanced efforts to assure quality and safety in systemic cancer therapy together with other health care providers. In consequence, oncology pharmacy has evolved as a novel specialist discipline. The endeavour to merge and co-ordinate individual activities and services of the pharmacist has led to pharmaceutical care concepts which aim at offering novel solutions to the various DRP. Conclusion Pharmaceutical care for cancer patients should be developed within research projects and integrated into disease management programs in order to ensure broad implementation

Crystallographic reconstruction study of the effects of finish rolling temperature on the variant selection during bainite transformation in C-Mn high-strength steels

The effect of finish rolling temperature (FRT) on the austenite- () to-bainite () phase transformation is quantitatively investigated in high-strength C-Mn steels. In particular, the present study aims to clarify the respective contributions of the conditioning during the hot rolling and the variant selection (VS) during the phase transformation to the inherited texture. To this end, an alternative crystallographic reconstruction procedure, which can be directly applied to experimental electron backscatter diffraction (EBSD) mappings, is developed by combining the best features of the existing models: the orientation relationship (OR) refinement, the local pixel-by-pixel analysis and the nuclei identification and spreading strategy. The applicability of this method is demonstrated on both quenching and partitioning (Q&P) and as-quenched lath-martensite steels. The results obtained on the C-Mn steels confirm that the sample finish rolled at the lowest temperature (829{\deg}C) exhibits the sharpest transformation texture. It is shown that this sharp texture is exclusively due to a strong VS from parent brass {110}, S {213} and Goss {110} grains, whereas the VS from the copper {112} grains is insensitive to the FRT. In addition, a statistical VS analysis proves that the habit planes of the selected variants do not systematically correspond to the predicted active slip planes using the Taylor model. In contrast, a correlation between the Bain group to which the selected variants belong and the FRT is clearly revealed, regardless of the parent orientation. These results are discussed in terms of polygranular accommodation mechanisms, especially in view of the observed development in the hot-rolled samples of high-angle grain boundaries with misorientation axes between and

In situ induction of dendritic cell–based T cell tolerance in humanized mice and nonhuman primates

Administration of an ICAM-1–specific antibody arrests dendritic cells in a semi-immature state and facilitates antigen-specific T cell tolerance to islet allografts in humanized mice and Rhesus monkeys

Crop Updates 2005 - Lupins and Pulses

This session covers sixty five papers from different authors: 1. 2004 LUPIN AND PULSE INDUSTRY HIGHLIGHTS, Peter White Department of Agriculture 2. BACKGROUND, Peter White Department of Agriculture 2004 REGIONAL ROUNDUP 3. Northern Agricultural Region, Martin Harries, Department of Agriculture 4. Central Agricultural Region, Ian Pritchard, Department of Agriculture 5. Great Southern and Lakes, Rodger Beermier, Department of Agriculture 6. Esperance Port Zone, Mark Seymour, Department of Agriculture, and David Syme, The Grain Pool of WA LUPIN AND PULSE PRODUCTION AGRONOMY AND GENETIC IMPROVEMENT 7. Lupin, Martin Harries, Department of Agriculture 8. Narrow-leafed lupin breeding, Bevan Buirchell, Department of Agriculture 9. Yellow lupin breeding in Western Australia, Kedar Adhikari, Mark Sweetingham and Bevan Buirchell, Department of Agriculture 10. WALAB2000 - First Anthracnose resistant albus lupins, Kedar Adhikari, Bevan Buirchell, MarkSweetingham and Geoff Thomas, Department of Agriculture 11. Improving lupin grain quality and yield through genetic manipulation of key physiological traits, Jon Clements1 and Bevan Buirchell2,1CLIMA, The University of Western Australia 2Department of Agriculture 12. Lupin alkaloids in four Australian species, Shao Fang Wang, Chemistry Centre (WA), CLIMA, The University of Western Australia 13. Improving lupin tolerance to herbicides of metribuzin, isoxaflutole and carfentrazone-ethyl, Ping Si1, Mark Sweetingham12, Bevan Buirchell12, David Bowran2 and Huaan Yang12 , 1CLIMA, The University of Western Australia, 2Department of Agriculture 14. Combined cultural and shielded sprayer herbicide application for weed management, Martin Harries and Mike Baker Department of Agriculture 15. Field testing of lupin seed of various sources with and without post maturity, pre harvest rain for field establishment, Martin Harries, Wayne Parker, Mike Baker, Department of Agriculture 16. Lupin seed rate by wide row spacing, Martin Harries, Bob French, Damien Owen D’arcy, Department of Agriculture 17. How environment influences row spacing response in lupins, Bob French, Department of Agriculture 18. The effect of wider row spacing on lupin architecture, growth and nutrient uptake dynamics, Bill Bowden and Craig Scanlan, Department of Agriculture 19. Fertiliser placement and application rate in wide rows, Martin Harries, Damien Owen D’arcy, Department of Agriculture 20. The pros and cons of cowing lupins in ‘wide’ rows, Wayne Parker, Bob French and Martin Harries, Department of Agriculture 21. Investigation into the influence of row orientation in lupin crops, Jeff Russell1 and Angie Roe2, 1Department of Agriculture, 2Farm Focus Consultants 22. Making the most of Mandelup, Greg Shea and Chris Matthews, Department of Agriculture 23. The effect of wild radish density and lupin cultivars on their competition at Merredin, Shahab Pathan, Abul Hashem and Bob French, Department of Agriculture 24. The potential of pearl lupin (Lupinus mutabilis) for southern Australia, Jon Clements1, Mark Sweetingham2, Bevan Buirchell2, Sofia Sipsas2, Geoff Thomas2, John Quealy1, Roger Jones2, Clive Francis1, Colin Smith2 and Gordon Francis1, 1CLIMA, University of Western Australia 2Department of Agriculture 25. Field pea, Mark Seymour, Department of Agriculture 26. Breeding highlights, Tanveer. Khan and Bob French, Department of Agriculture 27. Variety evaluation, Tanveer Khan, Kerry Regan, Jenny Garlinge and Rod Hunter, Department of Agriculture 28. Large scale field pea variety trials, Martin Harries, Department of Agriculture 29. Kaspa demonstrations, Rodger Beermier, Mark Seymour, Ian Pritchard, Graham Mussell, Department of Agriculture 30. Field pea harvesting demonstration at Merredin, Glen Riethmuller, Greg Shea and Bob French, Department of Agriculture 31. Does Kaspa respond differently to disease, fungicides, time of sowing or seed rate, Mark Seymour, Department of Agriculture 32. Field pea response to foliar Manganese in mallee district, Mark Seymour, Department of Agriculture 33. Kaspa harvesting observations 2004, Mark Seymour, Ian Pritchard, Glen Riethmuller, Department of Agriculture 34. ‘Blackspot Manager’ for understanding blackspot of peas and ascochyta blight management, Moin Salam and Jean Galloway, Department of Agriculture 35. 250,000 ha of field pea in WA – Is it sustainable? Larn McMurray1 and Mark Seymour2, 1South Australian Research and Development Institute, 2Department of Agriculture 36. Desi chickpea, Wayne Parker, Department of Agriculture 37. Breeding highlights, Tanveer Khan1,2 and Kadambot Siddique2,1Department of Agriculture, 2CLIMA, The University of Western Australia 38. Variety evaluation, Tanveer Khan, Kerry Regan, Jenny Garlinge and Rod Hunter, Department of Agriculture 39. Large scale variety testing of desi chickpeas, Martin Harries, Greg Shea, Mike Baker, Dirranie Kirby, Department of Agriculture 40. Desi variety chickpea trial, Martin Harries and Murray Blyth, Department of Agriculture 41. Seeding rates and row spacing of chickpea desi, Martin Harries, MurrayBlyth, Damien Owen D’arcy, Department of Agriculture 42. Molecular characterisation of chickpea wild relatives, Fucheng Shan, Heather Clarke and Kadambot Siddique, CLIMA, The University of Western Australia 43. Plant phosphorus status has a limited influence on the concentration of phosphorus-mobilising carboxylates in the rhizosphere of chickpea, Madeleine Wouterlood, Hans Lambers and Erik Veneklaas, The University of Western Australia 44. Kabuli chickpea, Kerry Regan, Department of Agriculture, and CLIMA, The University of Western Australia 45. ‘Kimberly Large’ A high quality and high yielding new variety for the Ord River Irrigation Area, Kerry Regan1,2, Kadambot Siddique2, Peter White1,2, Peter Smith1 and Gae Plunkett1,1Department of Agriculture, 2CLIMA, University of Western Australia 46. Development of ascochyta resistant and high quality varieties for Australia, Kadambot Siddique1, Kerry Regan1,2, Tim Pope1 and Mike Baker2, 1CLIMA, The University of Western Australia 2Department of Agriculture 47. Towards double haploids in chickpeas and field pea, Janine Croser, Julia Wilson and Kadambot Siddique, CLIMA, The University of Western Australia 48. Crossing chickpea with wild Cicer relatives to introduce resistance to disease and tolerance to environmental stress, Heather Clarke and Kadambot Siddique, CLIMA, The University of Western Australia 49. Faba bean, Peter White, Department of Agriculture 50. Germplasm evaluation, Peter White1,2, Kerry Regan1,2, Tim Pope2, Martin Harries1, Mark Seymour1, Rodger Beermier1 and Leanne Young1, 1Department of Agriculture, 2CLIMA, The University of Western Australia 51. Lentil, Kerry Regan, Department of Agriculture, and CLIMA, The University of Western Australia 52. Variety and germplasm evaluation, Kerry Regan1,2, Tim Pope2, Leanne Young1, Martin Harries1, Murray Blyth1 and Michael Materne3, 1Department of Agriculture, 2CLIMA, University of Western Australia, 3Department of Primary Industries, Victoria 53. Lathyrus species, Kadambot Siddique1, Kerry Regan2, and Colin Hanbury2, 1CLIMA, the University of Western Australia, 2Department of Agricultur

Serotonerge Modulation und ihr Einfluss auf die Signalverarbeitung auf zellulärer Ebene in Neuronen der tiefen Kleinhirnkerne

Deep cerebellar nuclei (DCN) neurons generate the final output of cerebellum and receive abundant modulatory serotonergic inputs from brainstem neurons. The aim of this present study was to elucidate the influence of serotonin on signal processing performed by DCN neurons. Since signal processing is determined by the interplay between intrinsic and synaptic properties, the impact of serotonin on intrinsic as well as synaptic properties was investigated. To this end whole-cell patch clamp recordings were performed in rat cerebellar slices. Serotonin caused a persistent membrane depolarization at current clamp recordings, which was mediated by an increase of tonic cationic currents and a concomitant decrease of tonic potassium currents. At the same time, serotonin influenced the waveform of action potentials that showed a reduced depolarization slope and peak amplitude, both indicating a reduced availability of voltage-gated sodium channels. However, serotonin showed a complicated effect at dynamic clamp recordings where the neuronal response depended on the average activity level before drug application. Spike rate was reduced by serotonin for depolarized high activity states and unaltered or slightly increased for hyperpolarized low activity states. The spike timing precision was not altered, showing that the response of DCN neurons to input transients was not affected by serotonin. The overall synaptic shunting level of the simulated synaptic inputs had also an impact as it shifted the degree of depolarization induced by serotonin. Therefore, the effect of serotonin on DCN activity was influenced twofold by background synaptic activity, first via its impact on the mean activity level and second via its shunting strength. Due to the functional relevance of inhibitory transmission between Purkinje cells and DCN neurons, its modulation by serotonin was the second focus of this study. Two previous studies have described frequency dependent short-term depression of this synapse in response to repetitive activation with multiple spike trains. Using dynamic clamp in the present study revealed that short-term depression might stabilize the membrane potential close to the activation threshold thereby significantly extended the working range of DCN neurons into regimes of high inhibitory input activity. Short-term depression did not change spike timing precision showing that responses to input transients were unaltered. Serotonin reduced the amplitude of evoked inhibitory postsynaptic currents potentially by reducing the release probability of presynaptic GABAA vesicles. However, short-term depression was not altered by serotonin at all tested frequencies, neither for the initial nor the steady-state phase. The time course of recovery from depression was not influenced by serotonin either. Overall these results indicate that serotonin altered the input-output transfer function of DCN neurons. Therefore, serotonin might act in concert with short-term depression as a high-pass filter, making the response of DCN neurons less dependent on the mean level of inhibitory input while retaining their sensitivity to transient changes in input activity and synchronized input.Neurone der tiefen Kleinhirnkerne (DCN) erzeugen die Ausgangsaktivität des Kleinhirns und erhalten vielfältigen modulatorischen Input von Neuronen des Hirnstamms. Das Ziel der vorliegenden Arbeit war, den Einfluss von Serotonin auf die Signalverarbeitung in DCN Neuronen aufzuklären. Da die Signalverarbeitung durch das Zusammenspiel intrinsischer und synaptischer Eigenschaften bestimmt wird, wurde die Wirkung von Serotonin sowohl auf intrinsische als auch auf synaptische Eigenschaften untersucht. Zu diesem Zweck wurden Whole-Cell Patch Clamp Ableitungen in Gewebeschnitten des Kleinhirns von Ratten durchgeführt. Serotonin verursachte eine dauerhafte Depolarisation des Membranpotentials in Current Clamp Ableitungen, die durch eine Zunahme anhaltender kationischer Ströme und eine gleichzeitige Abnahme anhaltender Kaliumströme verursacht wurde. Zugleich beeinflusste Serotonin den Potentialverlauf von Aktionspotentialen, der eine verringerte Anstiegssteilheit und eine verringerte maximale Amplitude aufwies, was auf eine reduzierte Verfügbarkeit an spannungsabhängigen Natriumkanälen hinweist. In Dynamic Clamp Ableitungen war die Wirkung von Serotonin jedoch komplizierter, da die neuronale Antwort vom Aktivitätsniveau vor der Substanzapplikation abhing. Die Aktionspotentialfrequenz wurde durch Serotonin verringert für depolarisierte hohe Aktivitätsniveaus und sie war unverändert oder wurde leicht reduziert für niedrige Aktivitätsniveaus. Die zeitliche Präzision der Aktionspotentiale war unverändert, was zeigt, dass Serotonin die Reaktion von DCN Neuronen auf Änderungen der Eingangsaktivität nicht beeinflusst. Der Shunting Effekt des simulierten synaptischen Inputs hatte ebenfalls einen Einfluss, da seine Gesamtstärke einen Einfluss auf die durch Serotonin verursachte Depolarisation hatte. Daher wurde die Wirkung von Serotonin auf die Aktivität von DCN Neuronen in zweifacher Weise durch die synaptische Hintergrundaktivität beeinflusst, zum einen durch ihre Wirkung auf das mittlere Aktivitätsniveau, zum anderen durch die Stärke des Shunting Effekts. Aufgrund der funktionellen Bedeutung der hemmenden Übertragung zwischen Purkinjezellen und DCN Neuronen war ihre Modulation durch Serotonin der zweite Schwerpunkt dieser Arbeit. Zwei frühere Studien haben die frequenzabhängige kurzzeitige Reduktion der synaptischen Übertragungsstärke (Short-Term Depression) mittels wiederholter Aktivierung während Aktionspotentialfolgen untersucht. Mithilfe von Dynamic Clamp wurde in der vorliegenden Arbeit gezeigt, dass das Membranpotential durch Short-Term Depression vermutlich nahe der Aktivierungsschwelle stabilisiert wird, wodurch der Arbeitsbereich von DCN Neuronen beträchtlich in Bereiche erhöhter hemmender Eingangsaktivität ausgedehnt sein könnte. Short-Term Depression hat die zeitliche Präzision der Aktionspotentiale nicht beeinflusst, was zeigt, dass die Antwort auf Inputtransienten nicht verändert wurde. Serotonin hat die Amplitude von hemmenden postsynaptischen Strömen verringert womöglich durch eine Reduktion der Freisetzungswahrscheinlichkeit für präsynaptische GABAA Vesikel. Die Short-Term Depression wurde durch Serotonin jedoch bei keiner der getesteten Frequenzen verändert, weder in der frühen Phase noch in der späten Gleichgewichtsphase. Der Zeitverlauf der Erholung von der Depression war in seinem Zeitverlauf durch Serotonin ebenfalls nicht beeinflusst. Zusammengefasst weisen diese Ergebnisse darauf hin, dass durch Serotonin die Eingangs-Ausgangs-Übertragungsfunktion von DCN Neuronen verändert wurde. Serotonin könnte in Zusammmenarbeit mit der Short-Term Depression als Hochpassfilter wirken, wodurch die Reaktion von DCN Neuronen weniger vom mittleren Niveau der hemmenden Eingangsaktivität abhängen würde während ihre Empfindlichkeit gegenüber vorübergehenden Änderungen der Eingangsaktivität und synchronisierter Eingangsaktivität unverändert erhalten bliebe

Modeling of Soot Formation in Turbulent Diffusion Flames Impinging on a Cold Surface

Thesis (Ph.D.)--University of Washington, 2022Soot is well known to be hazardous to both health and the environment. Over 40% of the world's population relies on biomass-fueled stoves for cooking, and these stoves are a significant source of soot. Especially problematic is the direct exposure to soot experienced by the user during cooking. The biomass-fired cookstove application often involves the impingement of a diffusion flame on the relatively cold cookware surface. Earlier experimental work showed that soot emissions increased substantially during flame impingement. This study seeks an improved understanding of the mechanisms responsible for this observation. The work primarily uses modeling as the tool to identify the mechanism. The approach focuses on two areas. The first is the development of an improved model for the oxidation of soot by O2 that includes a more realistic temperature dependence than has heretofore been presented in the literature. This is hoped to address the problem of overprediction of soot oxidation that appears in many modeling results. The second part consists of a broader study of reactive soot dynamics during the impingement process. Detailed soot models reflect the four processes governing soot dynamics: nucleation, surface growth, coagulation, and oxidation. Several studies have reported that the modeling of soot oxidation by O2 is inaccurate as it tends to overpredict the oxidation rate resulting in an underprediction of emissions. One of the challenges with modeling the oxidation process is that as the particle ages in the flame, it becomes more crystalline in structure and becomes less reactive to oxidation. The parameter α is widely used to represent this aging process wherein the soot surface reactivity ranges from α = 0 (nonreactive) to α = 1 (fully reactive). The surface deactivation process has been modeled primarily by using in-flame soot measurements for developing functional forms and parameters to describe the decay of surface reactivity, α. Among these, the model developed by Appel et al. has been widely used. Several studies indicate that the aging process should depend on both temperature and exposure time. Nevertheless, the time-temperature history of the particle is not directly taken into account in the model of Appel et al. A more recent model proposed by Khosousi et al. introduces a new parameter called the thermal age which incorporates the temperature-time history of the particle into the aging process. The model is, however, empirically based and does not reflect the non-linear temperature dependence one would expect of the physics of such a process. The present work presents a new soot aging model that is based on the framework of the well-studied problem of coal char oxidation deactivation. With a more fundamental framework, including the more realistic Arrhenius temperature dependence for the deactivation rate, the present model provides a better basis for approaching a wider range of flames. The new model is configured to provide the same parameter α so that it can be easily applied to existing soot models. The new approach is implemented in the fixed-pivot sectional soot model, with the model showing improved agreement with literature flame data. As mentioned above, soot emissions were found to increase substantially in cookstove experiments when the flame impinged on the cooking pot. Pundle et al. studied this phenomenon by examining emissions when an ethylene/air turbulent diffusion flame impinged on a cold pot surface compared to the system without the pot. The ethylene flame was used because it is a sooting flame with an extensive free flame database. (This particular study was the first in the literature to examine the problem of soot emissions resulting from flame impingement.) The present study computationally examines this configuration to identify the mechanisms leading to emission enhancement. The study uses a computational fluid dynamics code, a detailed chemical kinetic mechanism that includes soot precursor species, the laminar flamelet model to provide the turbulence/chemistry coupling problem, and the sectional model to simulate the soot dynamics. To reflect the experimental setup, the computational flame impinges on a surface at 373 K. The presence of the surface potentially affects soot behavior via (1) heat extraction by the surface leading to quenching of the chemical reactions, and (2) distortion of the flow field/mixing rates caused by the presence of the surface. To test this, runs were made in which the surface was assumed to be adiabatic, thus eliminating the heat extraction component. Very broadly, the insertion of the adiabatic surface leads to (1) an enhancement of local soot concentrations upstream of the surface, and (2) a decrease in soot concentrations as the flow diverges around the surface. In both cases, this results primarily from the alteration of the flow field. The initial increase in soot concentrations results from the surface causing an enhancement of the local turbulent scalar dissipation rate. The increased mixing rate leads to enhanced C2H2 concentrations which increase soot concentrations by promoting the surface growth process. The later decrease in soot concentrations occurs when the surface forces the flame to spread around itself forming a thinner concentration boundary layer which allows more O2 to diffuse in. This process enhances the O2 oxidation process at the location of the surface causing a sharp decrease in the in-flame integrated soot flux. The net result, however, is an enhanced emission. One concern in the cookstove literature is that adopting emission control strategies may lead to a reduced particle size for the remaining emissions, this potentially increasing the health impacts. This was experimentally examined by Pundle et al. who obtained size distribution measurements as part of the surface impingement work. The particle number density grows in all size ranges as the surface moves away from the fuel nozzle. This behavior occurs when the surface is located near the fuel nozzle (< 245 mm). However, there is no difference in the shape of the size distribution nor in the peak diameter. As the surface moves further away, the 245-mm case has fewer small-sized particles than the 300-mm case. The coagulation process is found to be responsible for the observed behavior as the 300-mm case has more space for particles to disperse resulting in lower concentration and lower coagulation process