Rights to some articles appeared in this disseration are reserved by the ELSEVIER B.V., John Wiley & Sons, Inc. and Pesticide Science Society of Japan.If any of these materials you wish to use, authorisation from sources must be obtain. / 京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13023号 / 論農博第2833号 / 新制||農||1043(附属図書館) / 学位論文||H28||N4968(農学部図書室) / 32951 / (主査)教授 佐久間 正幸, 教授 松浦 健二, 教授 奥野 哲郎 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Climate change is leading to in an increase in frequency and severity of wildfires, which in turn can result in the formation of runoff-initiated post-wildfire debris flows. This type of debris flows is, like most debris flows, triggered by heavy precipitation events. Debris flows have the potential to cause much damage, and therefore it is important to analyse when and where the risk of these flows exists. This study aims to identify shared characteristics of basins that experienced post-wildfire debris flows in order to improve future risk analyses regarding such flows. These characteristics were studied through the analysis of 42 basins in 10 burned areas across western North America, which experienced a total of 67 post-wildfire debris flows between 2000 and 2018. Literature research and existing databases revealed the bedrock, soil texture and the timing of the flows compared to the wildfires. Spatial analysis using ArcMap allowed for the analysis of the burn severity of the basins, the hypsometry of the basins, and the mean slope of the basins. Analysis of these characteristics revealed the importance of the hypsometric integral, the soil texture, and the mean slope angle of the basins. In general, the hypsometric integral tends to fall between 0.50 and 0.60 and only soils with a coarse texture were identified for the basins. The mean slope angle of the basins is commonly between 25-30o, with a wider range of slopes being able to generate debris flows shortly after the fire. If multiple basins in a small area are burned, those with steeper slope angles have a higher potential to generate debris flows, while basins with steeper slopes do not have a higher risk on large regional scales. In order to generate post-wildfire debris flows the basin also needs to be burned at a large extent at low to medium severity, resulting in an extensive and strong water-repellent layer required to generate the runoff that is needed to generate a debris flow. Seasonal wetting during winters and drying of the soil during summers can reduce or enhance runoff respectively as well. As a result, post-wildfire debris flows occur mostly during the late summer months shortly after a wildfire when precipitation is increasing through summer storms, or a year later when the soil is dried and primed during the summer followed by such a summer storm. Fires during winter and thus outside the traditional wildfire season can lead to post-wildfire debris flows during winter as well due to the strength of the fresh water-repellent layer. Climate change which will lead to more fires during late autumn and winter months can thereby result in post-wildfire debris flows during winter, rather than only during the summer months following wildfires in the traditional fire season. / Jordskred uppstår när en sammanhängande jordmassa kommer i snabb rörelse. Det är en typ av naturolyckor som kan skada både infrastruktur och människor. Sannolikheten att ett jordskred inträffar ökar efter skogsbränder. Samtidigt kan klimatförändringar leda till en ökning av skogsbränder vilket i sin tur kan leda till en ökad risk för jordskred i framtiden. Syftet med det här projektet är att bidra till bedömningen av risken av jordskred till följd av skogsbänder i västra Nordamerika och att identifiera andra områden som också har en stor risk att drabbs av skred efter skogsbränder genom att identifiera riskfaktorer. Under projektets gång skapades en databas med områden där jordskred inträffade efter skogsbränder i västra Nordamerika. Den vetenskapliga litteraturen visade några egenskaper av skred och områdena, t.ex. när branden och skredet hände, vilken berggrund finns i området och texturen av jordarten i området. Dessutom användandes GIS (Geographical Information System) med satellitbilder och DEM (Digital Elevation models), som visade information om brandskador samt de geomorfologiska karaktärerna av områden. Resultaten visade att formationen av jordskred kräver omfattande låga till måttliga brandskador som resulterar i ett starkt vattenavvisande jordlager. Detta jordlager minskar infiltrationskapaciteten av jorden och resulterar i mer ytavrinning vilket orsakar skred till följd av brand. Även en grov textur av jordlagret är viktig eftersom den också bidrar till ett starkt vattenavvisande jordlager. Dessutom kan askpartiklar bli fångade in i stora porer i jord med en grov textur vilket minskar infiltrationskapaciteten och ökar ytavrinningen. Det finns alltså två krav för att ett jordskred ska inträffa efter en skogsbrand: i) omfattande låga-måttliga brandskador, och ii) en grov textur av jorden. Vidare finns det några ytterligare egenskaper som ökar risken för skred efter skogsbränder om de två kraven är uppfyllda. Den hypsometriska integralen (ett sätt att uttrycka hypsometrin av en dal) ligger oftast mellan 0.50-0.60 vilket är normal för en geomorfologiskt sett mogna område. Dessutom hade de flesta områdena i projektet en medellutning mellan 25o och 30o. Dock fanns det även tillfällen där värdena låg utanför dessa intervaller. Därför kan dessa värden i sig inte användas som riskfaktorer, utan borde de även kombineras med de övriga egenskaperna som beskrivs i den här undersökningen. Det är också relevant att veta när jordskred inträffar till följd av skogsbränder. Resultaten visade att skred kan hända strax efter skogsbränder i slutet av sommaren när det finns kraftigt regn. Det är då som det vattenavvisande jordlagret är som starkast. Det vattenavvisande lagret minskar i styrkan under året, men det är också möjligt att det inträffar ett jordskred under sommaren året efter en skogsbrand. Då är jorden torr i slutet av sommaren när kraftigt regn inträffar efter torra månader. Torr jorden bidrar även till en minskad infiltrationskapacitet. Regn i vinter gör jorden blöt vilket ökar infiltrationskapaciteten av jorden. Dessutom sker det även skogsbränder utanför den traditionella skogsbrandsäsongen nuförtiden, t.ex. tidigt i vintern. I så fall kan jordskred också inträffa under samma vinter strax efter skogsbranden, därför att det vattenavvisande jordlagret som skapas i branden fortfarande är starkt då. Som nämnts tidigare finns det en riskprofil som kan användas för att identifiera områden som har en hög risk för jordskred efter skogsbränder, men möjligheten att ett jordskred inträffar under vintern istället för (slutet av) sommaren bör även iakttas. Risken växer nämligen i samband med klimatförändringar som leder till mer skogsbränder; inte bara under sommaren, utan även under vintern.

Development of repellent surfaces which can supress bacteria adhesion, blood contamination and thrombosis, and non-specific adhesion on diagnostic devices has been a topic of intense research as these characteristics are in high demand. This thesis focused on design and development of omniphobic surfaces based on hierarchical structures and their application for preventing pathogenic contamination and biosensing. First, a flexible hierarchical heat-shrinkable wrap featuring micro and nanostructures, was developed with straightforward scalable methods which can be applied to existing surfaces. These surfaces reduced biofilm formation of World Health Organization-designated priority pathogens as well as minimized risk of spreading contamination from intermediate surfaces. This is due to the broad liquid repellency and the presence of reduced anchor points for bacterial adhesion on the hierarchical surfaces. Next, the developed surfaces were applied to minimize blood contamination and clot formation as well as facile integration of hydrophilic patterns. This led to droplet compartmentalization and was utilized for detection of Interleukin 6 in a rapid dip-based assay. Furthermore, in a review article the need for anti-viral or virus repellent surfaces and future perspectives were discussed as the global COVID-19 pandemic surged and attracted interest toward innovative technologies for suppressing the spread of pathogens. To address the pressing issue of non-specific adhesion in diagnostics devices, an omniphobic liquid infused electrochemical biosensor was developed. This was achieved by electroplating gold nanostructures on fluorosilanized gold electrodes. These electrodes demonstrated rapid and specific detection of Escherichia coli within an hour in complex biological liquids (blood, urine, etc.) without dilutions or amplification steps from clinical patient samples which are major bottle necks when rapid detection systems are sought for at the point of care. / Thesis / Doctor of Philosophy (PhD) / Repellent surfaces have a variety of applications in healthcare, for coating medical devices (e.g. indwelling implants, stethoscopes, and other external devices.), coating hospital surfaces for blood and pathogen repellency, and for developing anti-fouling diagnostic devices. Furthermore, they can be applied in the food sector for limiting contaminations, and in public areas on high-touch surfaces to eliminate the spread of infection. Therefore, there is a need for repellent surface which can be easily applied to surfaces with various form factors while having an easy fabrication method. Featuring hierarchical structures on a heat-shrinkable material, a repellent wrap was designed to be integrated on existing surfaces and repel pathogens and suppress the spread of infection as an intermediate surface. Similar concept was used for designing blood repellent surfaces which were patterned with hydrophilic regions for a rapid dip-based biosensing platform. Finally, surface textures on conductive materials with liquid infused repellent coatings were investigated for electrochemical biosensing in complex biological liquids.

Yes / This study examines the feasibility of using colloidal silica nanoparticles as active agents in high concentration waterborne polymer latex formulations. We showed that distributing the silica throughout the waterborne emulsion formed a composite coating material with a hydrophilic surface that consequently reduced exterior dirt pickup. Two grades of silica nanoparticles were studied, one using sodium stabilisation and another using epoxysilane modification to introduce glycidox-ypropyltrimethoxysilane surface functionality. Rheological study of the waterborne latex on mixing showed that there was an immediate pH responsive interaction between the silica sols and the polymer latex. Once loading of sodium charge stabilised silica NPs exceeded the volume required for heteroflocculation to occur the mixture demonstrated the potential to gel on standing – a process which took weeks, or months, to occur depending on the pH and relative concentrations used. At least fifty percent silane modification to the NP surface was found to be necessary to maintain a stable colloidal dispersion for long term storage of the waterborne latex. Despite this both grades of silica were found to imbue reductions in dirt pickup when applied to exterior masonry concrete studies over a 3-month weathering test / This work was supported by the Royal Society of Chemistry [E21-8346952505].

Flera olika arter I Sverige kan ge skador på skogen på olika vis. Där hjortviltet är en stor skadegörare på framförallt yngre tallplanteringar. Varje år kommer Skogsstyrelsen ut med information om beteskadenivåerna i landet i form av en älgbetesinventeringsrapport (ÄBIN). Skogsstyrelsen uppmanar varje år till att det ska skjutas mer älg för att få ner skadenivåerna till 5 % som är det nationella målet. Betesskador på tallplantor i tidig ålder medför en tillväxtförlust och nedklassning av framtida virke vilket påverkar den ekonomiska aspekten. Av alla olika betesskador så står toppskottsbetet för ca 75 % av skadorna, där en åtgärd för att minska betesskador är att använda viltskyddsmedel på plantorna. Syften med studien var att undersöka om det var effektivt att använda viltskyddsmedel för att minska toppskottsskador på tallplantorna, samt att undersöka om mängden RASE i bestånden hade någon påverkan på skadenivåerna på tallplantorna. Studien genomfördes som ett fältexperiment där 4 bestånd på två olika geografiska platser i norra Dalsland inventerades. På varje plats så inventerades två olika bestånd av tall med medelhöjden 1-4 meter, där ett bestånd var behandlat med viltskyddsmedel och det andra inte. Skadenivåerna mättes i 2,82 m2 stora cirkelprovytor med ett provyteförband på 60 m. provytorna lades ut objektivt i ett rutnät på analoga kartor innan inventeringen. I varje provyta så mättes stamantal, andel RASE stammar och antal toppskottsskadade tallplantor.  Resultaten visade en signifikant skillnad mellan tallbestånden, där de viltskyddsbehandlade plantorna var mindre betade på båda de olika områdena i norra Dalsland. RASE plantor hittades endast på det ena området, och där var den totala skadefrekvensen högre på tallplantorna både på de behandlade och obehandlade plantorna.  En slutsats i studien är att viltskyddsmedel har god effekt för att skydda yngre tallplantor från att bli toppsskottsskadade av hjortviltet. Men också att andelen RASE plantor i tallbestånden inte verkade ha en minskad effekt på toppskottsskadorna på tallen, det såg snarare ut som att skadorna ökade när RASE andelen var högre. Det skulle eventuellt kunna innebära att fodertillgången är för låg till storleken på hjortviltstammen i landskapet.

The primary focus of this study is the reduction of sensitivity to contamination of the battery pack surfaces. During the project, information on adhesion mechanisms that cause particles to accumulate on surfaces has been collected through literature research. This has been done to create a fundamental understanding regarding the factors that affect dust and particle accumulation. In addition, an in-depth study of articles concerning the modification of surface structure has been carried out. In connection with the literature study, an experimental analysis was carried out where a number of surfaces provided by Scania were examined to understand their structure and properties. This was done in order to identify suitable surface treatments/methods that could be applied. The experimental results show that all the surfaces consist of only micro-level structures. Two of the samples showed increased risk for dust accumulation due to one of them having a step profile and the other having a wavy surface structure with peaks and valleys. Previous research suggests that surfaces that are structured on the micro- and nano-level are essential to achieve dust- and particle-free/repellent surfaces. By structuring surfaces at the micro- and nano-level, a so-called hierarchical structure inspired by the natural self-cleaning mechanisms of the lotus leaf can be achieved. This results in surfaces with a high water contact angle and low surface energy, which contribute to minimized adhesion forces and in turn particle repellent surfaces.

Textile processing methods such as conventional exhaustion dyeing, pre-treatments and printing consume high amounts of water and use partly toxic and hazardous chemicals which are non-degradable. These chemicals (e.g. excess amount of dye, additives and catalysts) remain partially in the waste-water which is drained out and ends up polluting the environment. The supercritical carbon dioxide dyeing technology presents an eco-friendly and water-free method with reduced use of chemicals and energy. The benefits of such technology are currently not overcoming the relative high investment costs which impede its full implementation into the textile industry. This study presents an approach to extent the application of the eco-friendly supercritical carbon dioxide technology. It combines the well-studied supercritical carbon dioxide dyeing process for polyester with the functionalisation process to obtain water repellent surface properties. As water repellent (substance) environmentally benign silicones are used. Results showed that the simultaneous dyeing and functionalisation process was feasible assessed by the compatibility of the dye and silicone in the system. Silicone and dye did not interfere in each other’s functionality (colour strength and water contact angle). Further the process temperature and silicone molecular weight showed no influence on the colour strength of the fabric whereas the water contact angle (water repellence) increased with increasing temperature. The resulting polyester fabric showed acceptable colour strength yet did not obtain sufficient water repellent properties despite the increase in water contact angle of the treated samples to the untreated reference sample. The poor water repellence is suggested to be caused by the hydrophobic functional groups of the silicones oriented towards each other rather than toward the outer fabric surface. Overall the thesis is promoting research which combines eco-friendly technologies including environmental benign chemicals for the textile industry. Silicones are widely used in textile processing not only as water repellents, but also as anti-foaming agents, lubricants and softeners. Therefore a water-free and eco-friendly application method can benefit a wide range of finishing processes.

<p>A computer model based on minimization of the free energy, capable to predict contact angles and spreading transitions between Wenzel and Cassie mode for drops placed on surfaces with different topography were implemented in matlab. Simulations were compared with experiments documented in the literature. These showed that reported transitions between Cassie and Wenzel mode can be explained by minimization of the free energy. In this report, a study on the possibility of constructing water repellent paper surfaces with a combination of treatment with octadecyltrichlorosilane and topography changes, is included.</p>

A computer model based on minimization of the free energy, capable to predict contact angles and spreading transitions between Wenzel and Cassie mode for drops placed on surfaces with different topography were implemented in matlab. Simulations were compared with experiments documented in the literature. These showed that reported transitions between Cassie and Wenzel mode can be explained by minimization of the free energy. In this report, a study on the possibility of constructing water repellent paper surfaces with a combination of treatment with octadecyltrichlorosilane and topography changes, is included.

The report is a comparative study between spruce plantations where 4 plants are treated with deer repellents and 4 plantations are untreated. The study aims to provide a base for the Forest Society's future decisions regarding the use of wildlife-repellents.  The report indicates that wildlife-repellents work reasonably well for its purpose, the treated stocks were virtually untouched during the planting year and next year while the untreated stocks have been heavily grazed during these years.  Growth difference between grazed plants and ungrazed plants found to be virtually non-existent (0, 01 m) of the treated stocks and 0, 07 m in the untreated plants. Because of the growth differences are so small between grazed and no grazed plants, it seems like the treatment of deer-repellent are unnecessary. Unless you know in particularly that the area has a specific problem whit severe deer-grazing.