| 1. |
- Bivehed, Erik, et al.
(författare)
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DNA integrity under alkaline conditions : An investigation of factors affecting the comet assay
- 2023
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Ingår i: Mutation research. Genetic toxicology and environmental mutagenesis. - : Elsevier. - 1383-5718 .- 1879-3592. ; 891
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pH on DNA integrity was assessed using a three-step approach. The comet assay was used on a whole genome level, with three different protocols: neutral (no alkaline unwinding), flash (pH 12.5 with 2.5 min unwinding), and the conventional alkaline protocol (pH>13 with 40 min unwinding). Real-time quantitative PCR (RT-qPCR) was then used to study the isolated DNA, revealing that gene amplification decreased with increasing pH, indicating DNA degradation. Specially designed molecular beacons were used to examine DNA at the molecular level, with or without alkali-labile site (ALS) insertions. At pH 12.5, fluorescence in the hairpins with ALS started to increase after 30 min, while at pH> 13, this increase was already observed after 5 min, indicating a significant increase in DNA strand breaks. Liquid chromatography analysis was also used, demonstrating that the hairpins remained intact up to pH 10, even after 1 h exposure, whereas, at pH 12.5, partial conversion into strand breaks occurred after 30 min. At pH> 13, the hairpins were almost completely degraded after 30 min. The flash protocol effectively detects DNA single- and double-strand breaks and identified these damages after 2.5 min of alkaline treatment at pH 12.5. When the hairpins were exposed to pH 12.5 for 60 min, ALS were converted to strand breaks, demonstrating the sensitivity of this approach to detect changes in DNA structure. These findings indicate that pH poses a substantial risk to DNA integrity, leading to significantly higher background levels of DNA damage compared to conditions closer to neutrality. Our study demonstrates the importance of understanding the influence of pH on DNA stability and provides insights into risks associated with alkaline environments, especially at pH> 13.
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| 2. |
- Bivehed, Erik, et al.
(författare)
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Evaluation of Potential DNA-Damaging Effects of Nitenpyram and Imidacloprid in Human U937-Cells Using a New Statistical Approach to Analyse Comet Data
- 2020
-
Ingår i: Exposure and Health. - : Springer Nature. - 2451-9766 .- 2451-9685. ; 12:3, s. 547-554
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Tidskriftsartikel (refereegranskat)abstract
- Even if the two neonicotinoids nitenpyram and imidacloprid have been considered safe for humans, their potential genotoxicity still remains a matter of discussion. The DNA-damaging effects of these two compounds were therefore evaluated in a lymphoma cell line of human origin (U-937) using the comet assay after 3-h exposure to up to 50 mu M, with or without metabolic activation using S9 from human liver. The comet data were analysed using a traditional one-way ANOVA after pooling the data on cellular level, and a new alternative approach we have called Uppsala Comet Data Analysis Strategy (UCDAS). UCDAS is a proportional odds model tailored to continuous outcomes, taking the number of pooled cultures, slides and cells into consideration in the same analysis. To the best of our knowledge, the UCDAS approach when analysing comet data has never been presented before. Without metabolic activation, no increase in DNA damage was observed in the neonicotinoide-exposed cells. Nitenpyram was also without DNA-damaging effects when S9 was added. However, in the presence of S9, imidacloprid was found to increase the level of DNA damage. Whereas the ANOVA showed an increase (P<0.001) both at 5 and 50 mu M, UCDAS showed an increase only at the lowest concentration (P<0.001). Based on these findings, the two neonicotinoids seem to be of little concern when it comes to their potential genotoxicity. However, since the U-937 cells were rather resistant to our positive controls, they may not be the best cells to use when evaluating potential genotoxicity of chemicals.
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| 3. |
- Bivehed, Erik, 1990-
(författare)
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Evolving the Methodology for Detection of Primary DNA Damage : Development, adaptation and assessment of the single cell gel electrophoresis (comet) assay
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Deoxyribonucleic acid (DNA) is one of the most important molecules in nature. It is the fundamental carrier of evolutionary information and constitutes the genetic blueprint of all living organisms. Being the sole source of information, it is vital for the cell to transmit the correct genetic information from generation to generation. DNA damage is a critical precursor to cancer development, highlighting the need for tests to predict genotoxicity and mutagenicity of various agents, including pharmaceuticals and environmental factors. This thesis focuses on enhancing the single cell gel electrophoresis (comet assay) for assessing primary DNA damage.The work was concentrated around several fundamental aspects of the methodology where a novel statistical approach, Uppsala Comet Data Analysis Strategy (UCDAS), was developed for data evaluation. A proportional odds model tailored to continuous outcomes was used, accommodating the experimental design's hierarchy, large zero values, and avoiding data transformation. A revisit of the formulation of the electrophoresis medium led to the introduction of a low conductive lithium hydroxide-based solution, enabling higher field strengths, significantly reducing runtimes and increasing sensitivity compared to the conventional comet assay. A lot of work was done on the investigation of the pH's impact on DNA integrity, revealing elevated background DNA damage at higher pH levels. Extended unwinding at pH >13, typical of the most commonly used versions of alkaline comet assays, jeopardizes the integrity of DNA, resulting in greater background DNA damage than at lower pH values. The study underscores pH's significance for DNA stability, highlighting risks associated with extremely alkaline conditions.A new method was developed, the Polymerase Assisted DNA Damage Assay (PADDA), to label and quantify single- and double-strand DNA breaks selectively in comet heads and tails after exposure to established DNA-damaging agents. This approach also allowed detection of DNA damage inside comet heads, an ability lacking in traditional comet assays.In conclusion, this research enhances DNA damage assessment methodologies, introducing new statistical innovations, novel electrophoresis mediums, and a novel technique for the selective detection and quantification of single- and double-strand breaks. These advancements deepen our understanding of DNA damage's complexities and underscore the crucial role of pH in influencing DNA stability and its implications for genotoxicity assessment.
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| 4. |
- Bivehed, Erik, et al.
(författare)
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Flash-comet : Significantly improved speed and sensitivity of the comet assay through the introduction of lithium-based solutions and a more gentle lysis
- 2020
-
Ingår i: Mutation research. Genetic toxicology and environmental mutagenesis. - : ELSEVIER. - 1383-5718 .- 1879-3592. ; 858
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of primary DNA-damage is one way to identify potential genotoxic agents and for this purpose the Comet assay has, for the last decades, been used to monitor DNA single strand and double strand breaks in individual cells. Various attempts have been made to modify the different steps in the in vitro protocol for the Comet assay in order to improve its sensitivity. However, to the best of our knowledge, nobody has tried to replace the traditionally used NaOH-based electrophoresis solution (pH > 13), with another type of solution. In the present paper, using TK-6 cells exposed to different concentrations of H2O2 or ionizing radiation, we present evidence clearly showing that a low-conductive LiOH-based electrophoresis solution at pH 12.5, and a more gentle lysis procedure, significantly improved both the speed and sensitivity of the assay. The new approach, which we call the Flash-comet, is based on a lysis buffer at pH 8.5, an unwinding time of 2.5 min in a LiOH solution without EDTA at pH 12.5, and an electrophoresis time of 1 min at 150 V (5 V/cm) using the same solution.
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| 5. |
- Bivehed, Erik, et al.
(författare)
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Flash-comet assay
- 2020
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Ingår i: MethodsX. - : ELSEVIER. - 1258-780X .- 2215-0161. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- In the present paper, we present a substantially revised protocol of the widely used SCGE assay performed under alkaline conditions. In our updated version of the comet assay, which we call the Flash-comet, LiOH is used instead of NaOH during the unwinding and electrophoresis. This allows a higher voltage during the electrophoresis (5 V/cm instead of 0.7 V/cm), making it possible to reduce the unwinding time from 20 to 40 to 2.5 min, and the electrophoresis time from 10 to 20 to 1 min. Still, the Flash-comet was found to detect DNA strand breaks and alkali-labile sites with a higher degree of sensitivity than the conventional protocol in cells that had been exposed to H2O2 or ionizing radiation. In order to prevent alkaline hydrolysis of DNA, the wash and lysis solutions have been modified in the Flash-comet protocol. By using an alkaline LiOH-based medium, the Flash-comet allows for much shorter times for both unwinding and electrophoresis than the conventional comet assay without compromising the sensitivity. The reduced run-times of the unwinding and electrophoresis steps in the Flash-comet should also reduce the risk of laboratory-induced alkaline hydrolysis of DNA when evaluating the potential DNA-damaging effects of different types of xenobiotics.
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| 6. |
- Bivehed, Erik, et al.
(författare)
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Visualizing DNA single- and double-strand breaks in the Flash comet assay by DNA polymerase-assisted end-labelling
- 2024
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Ingår i: Nucleic Acids Research. - : Oxford University Press. - 0305-1048 .- 1362-4962. ; 52:4
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Tidskriftsartikel (refereegranskat)abstract
- In the comet assay, tails are formed after single-cell gel electrophoresis if the cells have been exposed to genotoxic agents. These tails include a mixture of both DNA single-strand breaks (SSBs) and double-strand breaks (DSBs). However, these two types of strand breaks cannot be distinguished using comet assay protocols with conventional DNA stains. Since DSBs are more problematic for the cells, it would be useful if the SSBs and DSBs could be differentially identified in the same comet. In order to be able to distinguish between SSBs and DSBs, we designed a protocol for polymerase-assisted DNA damage analysis (PADDA) to be used in combination with the Flash comet protocol, or on fixed cells. By using DNA polymerase I to label SSBs and terminal deoxynucleotidyl transferase to label DSBs with fluorophore-labelled nucleotides. Herein, TK6-cells or HaCat cells were exposed to either hydrogen peroxide (H2O2), ionising radiation (X-rays) or DNA cutting enzymes, and then subjected to a comet protocol followed by PADDA. PADDA offers a wider detection range, unveiling previously undetected DNA strand breaks. Graphical Abstract
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| 7. |
- Fridell, Kent, et al.
(författare)
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Multifunktionella urbana dagvattenanläggningar : Referensanläggningar
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Föreliggande rapport är en sammanställning över ett antal av de dagvattenanläggningar och de forskningsstudier som pågått inom ramen för Formas-projektet Multifunktionella urbana dagvattenanläggningar. Projektets mål var att snabba på implementeringen och erfarenhetsspridningav de nya konstruktionslösningarna och verktygen för stadsplanering, projektering och anläggning som togs fram inom Vinnova-projektet Klimat säkrade Systemlösning för Urbana ytor. Ett projekt vars huvudsyfte varit att ta fram och utvärdera nya dagvattenanläggningar och systemlösningar som främjar lokalt omhändertagande av dagvatten och har integrerats i stadsmiljö. De anläggningar som tas upp i rapporten är öppen överbyggnad med tät eller dränerande beläggning, regnbäddar och träd i hårdgjord yta. Totalt omnämns fem projekt från tre kommuner och ett privat företag, från södra till mellersta Sverige. Inom varje projekt finns flera anläggningar och som kan bestå av olika konstruktioner och utformning. Syftet med rapporten är att ge en samlad bild över de dagvattenanläggningar och forskningsstudier som ingår i projektet Multifunktionella urbana dagvattenanläggningar. Rapporten riktar sig till de med intresse av att anlägga hållbara dagvattensystem i urbana områden. I befintlig bebyggelse likväl som i vid nyexploatering.
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| 8. |
- Gummesson, Christina, et al.
(författare)
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Entrustable professional activities (EPAs) for undergraduate medical education : development and exploration of social validity
- 2023
-
Ingår i: BMC Medical Education. - : BioMed Central (BMC). - 1472-6920. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The development of entrustable professional activities (EPAs) as a framework for work-based training and assessment in undergraduate medical education has become popular. EPAs are defined as units of a professional activity requiring adequate knowledge, skills, and attitudes, with a recognized output of professional labor, independently executable within a time frame, observable and measurable in its process and outcome, and reflecting one or more competencies. Before a new framework is implemented in a specific context, it is valuable to explore social validity, that is, the acceptability by relevant stakeholders.Aim: The aim of our work was to define Core EPAs for undergraduate medical education and further explore the social validity of the constructs.Method and material: In a nationwide collaboration, EPAs were developed using a modified Delphi procedure and validated according to EQual by a group consisting of teachers nominated from each of the seven Swedish medical schools, two student representatives, and an educational developer (n = 16). In the next step, social validity was explored in a nationwide survey. The survey introduced the suggested EPAs. For each EPA, the importance of the EPA was rated, as was the rater’s perception of the present graduates’ required level of supervision when performing the activity. Free-text comments were also included and analyzed.Results: Ten Core EPAs were defined and validated. The validation scores for EQual ranged from 4.1 to 4.9. The nationwide survey had 473 responders. All activities were rated as “important” by most responders, ranging from 54 to 96%. When asked how independent current graduates were in performing the ten activities, 6 to 35% reported “independent”. The three themes of the free text comments were: ‘relevant target areas and content’; ‘definition of the activities’; and ‘clinical practice and learning’.Conclusion: Ten Core EPAs were defined and assessed as relevant for Swedish undergraduate medical education. There was a consistent gap between the perceived importance and the certainty that the students could perform these professional activities independently at the time of graduation. These results indicate that the ten EPAs may have a role in undergraduate education by creating clarity for all stakeholders.
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| 9. |
- Hellman, Fredrik, 1967-, et al.
(författare)
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Användning av sekundära ballastråvaror och koppling till funktion och dimensionering
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 424-424
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Behovet av ballastmaterial ökar snabbt med pågående förtätning och växande städer med tillhörande infrastruktur, inte bara i Sverige. Det är i och kring städerna som det blir allt svårare att skaffa fram bergmaterial av alla slag. För ett mer cirkulärt och hållbart byggande av anläggningsinfrastruktur såsom hårdgjorda ytor i våra städer och bättre nyttjande av förnybara råvaror krävs därför att man ökar användningen av alternativa ballastmaterial såsom tex slaggrus, krossad betong och fräsasfalt. Det krävs att man tar fram förtroendeskapande, vetenskapligt baserat underlag och regelverk för dimensionering av hårdgjorda ytor. Det måste dessutom vara lätt att använda denna typ av produkter. Kunskap från tidigare utförda projekt kommer att kunna användas för att ta fram tabeller för olika trafikklasser och användningsområden. Projektet har tagit materialparametrar så att man enkelt kan modellera funktion och livslängd.Materialparmetrar tas fram i labbtester tex triaxialförsök och standardmetoder. Vi utvärderar modellerade resultat och funktion med uppmätta resultat Projektet använder dimensioneringsverktyget ERAPave för slaggrus och andra alternativa ballastmaterial för trafikbelastade hårdgjorda. Försöken görs för att kunna förbättra och få större förståelse för svagheter och styrkor i konstruktionslösningarna och utvärdera dessa. Slutsatserna från laboratorie och fullskaleförsök visar att de uppmätta tekniska egenskaperna i många fall är utanför de krav som normalt ställs på tradionella obundna bergmaterial exempelvis styvhet, packningsegenskaper och kornkurva. Detta försvårar upphandling av dessa material. Man behöver vara medveten om skillnaderna och kunna hantera dessa i upphandling. Resultat från detta projekt och flera tidigare projekt visar att funktionen oftast är tillräckligt bra. I många fall har de också en långsam styvhetstillväxt (tex betong kross och slaggrus).
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| 10. |
- Hellman, Fredrik, 1967-, et al.
(författare)
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Dimensionering, bärighet och infiltration : Uppföljning av Blå-Grön-Grå (BGG) konstruktioner
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Pågående klimatförändringar innebär att vi kan vänta oss mer extrema vädersituationer med större dagvattenmängder att hantera än vad vi är vana vid och våra system är utformade för. För ett medelscenario uppskattas att regnen i ett 100-årsperspektiv kommer att öka i storleksordningen 20–30 procent. I tätbebyggt område är en stor del av ytorna täta och regnvatten har ingen naturlig infiltrationsmöjlighet. Problemet är att när städerna förtätas och infiltrationsytor försvinner så leds mer och mer vatten ner i dagvattensystemet. När det blir fullt trycks vatten tillbaka upp till ytan. Och vid intensivare regn blir resultatet i värsta fall översvämningar, vattenfyllda källare, skador på kringliggande byggnader och många andra negativa konsekvenser som i dagsläget är betydligt svårare att kvantifiera. I Sverige används över 60 miljoner ton bergmaterial till vägar, gator och torgytor per år. Det är mer än 40 miljoner kubikmeter material, eller nästan 70 st fyllda Globen. Den absoluta majoriteten av materialet används till täta konstruktioner som förvärrar problemen och ökar avrinningen. Ett sätt att minska risken för översvämningar, förenkla hanteringen av dagvatten samt att tillgodose goda betingelser för växtlighet är att använda BGG (Blå-Grön-Grå)-konstruktioner. Gemensamt för dessa är ett de förstärkningslager med stor hålrumsandel som medför att dagvatten kan infiltrera och magasineras i vägkonstruktionen. Det öppna förstärkningslagret förbättrar även livsbetingelserna för växtlighet.
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| 11. |
- Islam, Azim Ullah Shamsul, et al.
(författare)
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Myrcene Attenuates Renal Inflammation and Oxidative Stress in the Adrenalectomized Rat Model
- 2020
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 25:19
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Tidskriftsartikel (refereegranskat)abstract
- Physiological Glucocorticoids are important regulators of the immune system. Pharmacological GCs are in widespread use to treat inflammatory diseases. Adrenalectomy (ADX) has been shown to exacerbate renal injury through inflammation and oxidative stress that results in renal impairment due to depletion of GCs. In this study, the effect of myrcene to attenuate renal inflammation and oxidative stress was evaluated in the adrenalectomized rat model. Rats were adrenalectomized bilaterally or the adrenals were not removed after surgery (sham). Myrcene (50 mg/kg body weight, orally) was administered post ADX. Myrcene treatment resulted in significant downregulation of pro-inflammatory cytokines (IL-1 beta, IL-6, and TNF-alpha) compared to untreated ADX rats. In addition, myrcene resulted in significant downregulation of immunomodulatory factors (IFN gamma and NF-kappa B) and anti-inflammatory markers (IL-4 and IL-10) in treated ADX compared to untreated ADX. Myrcene significantly increased the antioxidant molecules (CAT, GSH, and SOD) and decreased MDA levels in treated ADX compared to untreated. Moreover, myrcene treatment reduced the expression of COX-2, iNOS, KIM-1, and kidney functional molecules (UREA, LDH, total protein, and creatinine) in ADX treated compared to ADX untreated. These results suggest that myrcene could be further developed as a therapeutic drug for treatment of kidney inflammation and injury.
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| 12. |
- Kosgahakumbura, Lakmini, et al.
(författare)
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Screening for antibacterial and cytotoxic activities of Sri Lankan marine sponges through microfractionation : Isolation of bromopyrrole alkaloids from Stylissa massa
- 2024
-
Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Sri Lanka is a biodiversity hotspot and one of the richest geographical locations of marine sponges in the Indian ocean. However, the most extensive taxonomical study on Sri Lankan sponge biodiversity dates back similar to 100 years and only a limited number of studies have been conducted on sponge natural products. In the current study, 35 marine sponge specimens (collected from 16 sponge habitats around Sri Lanka) were identified, microfractionated and evaluated for antibacterial and anticancer assays. In total, 30 species were characterized, of which 19 species gave extracts with antibacterial and/or cytotoxic activities. Microfractionated organic extract of Aciculites orientalis gave the most potent antibacterial activity against Staphylococcus aureus and strongest lymphoma cell toxicity was exhibited by the organic extract of Acanthella sp. Guided by the molecular ion peaks in the bioactive fractions, large-scale extraction of Stylissa massa led to the isolation of three bromopyrrole alkaloids, sceptrin, hymenin and manzacidin A/C. Of these, sceptrin exhibited broad spectrum antibacterial activity against both Escherichia coli and S. aureus (MIC of 62.5 mu M against both species). Based on natural product literature, seven promising species were identified as understudied. Their further exploration may lead to the discovery of structurally novel compounds.
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| 13. |
- Lind, Hans, et al.
(författare)
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Hydrogen Evolution Reaction for Vacancy-Ordered i-MXenes and the Impact of Proton Absorption into the Vacancies
- 2021
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Ingår i: Advanced Sustainable Systems. - : Wiley. - 2366-7486. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- A study of the hydrogen evolution reaction (HER) for Mo-, W-, and Nb-based MXenes is presented, where W1.33C MXene with ordered vacancies is chosen for further investigation. The electrochemical measurements show that if the W1.33C MXene is subjected to high cathodic potentials, it greatly improves the activity and onset potential for the HER. The enhancement continues to improve independent of whether the potential is kept fixed at a certain cathodic potential or if the potential is scanned repeatedly. Interestingly, the improvement disappears if the material is subjected to anodic potential. Based on these observations, the hydrogen interaction with the MXene surface as well as in the vacancies is investigated by means of first-principles calculations. These show that the adsorption energy of hydrogen is sensitive to both surface coverage and vacancy occupancy, and that, for certain structures with hydrogen in the vacancies, thermoneutral values of hydrogen adsorption can be obtained. Based on the calculations it is argued that under high cathodic potentials, protons can transfer to the vacancies and stay there in a metastable state as hydrogen atoms, while at anodic potential the process is reversed. The first-principles results provide a rationale for the strongly enhanced HER activity observed experimentally on W1.33C MXene.
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| 14. |
- Rahman, Mohammad Shafiqur, 1978-, et al.
(författare)
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Alternative and recycled materials as pavement unbound layers
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 425-426
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Waste materials and biproducts from various industries can be a good alternative source of pavement materials. This will reduce the demand for natural aggregates. Instead of dumping as landfill, using these materials in pavements will significantly contribute to obtaining climate neutrality and circular economy. However, based on the sources, the properties of these materials can vary widely. Knowledge and experience regarding the suitability and performance of these waste materials in pavements is not as extensive as conventional materials. Hence, prior to employing in pavement constructions, it is necessary to investigate the mechanical properties of these materials in a systematic manner and to create guidelines for their usage. In this study, recycled materials from four different sources were investigated as alternatives for pavement constructions. Two of the materials were coarse fractions of the bottom ash from two incineration plants. The other two materials were crushed concrete from demolished constructions and material from road scalpings. Both laboratory and full-scale accelerated tests were conducted. The objectives were to compare their relative performances and to obtain and calibrate the material properties for further design using a pavement design tool ERAPave. The laboratory investigations were based on repeated load triaxial (RLT) testing. From the RLT tests, the stiffness and permanent deformation properties as well as the model parameters used in ERAPave for each of these materials were evaluated. For the full-scale accelerated tests, four instrumented test structures were built where all the layers were identical except for the subbase layers which were composed of each of the alternative materials. These structures were then tested employing a heavy vehicle simulator (HVS). During the passages of the wheel of the HVS, development of the surface rutting as well as deformations and stresses in the different layers were registered. In both laboratory and full-scale tests, results indicated that the crushed concrete performed the best which is comparable to well-graded crushed rock aggregates. Material from road scalpings demonstrated the weakest performance followed by the two bottom ash materials.
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| 15. |
- Schouenborg, Björn, et al.
(författare)
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Cirkulära anläggningsmaterial i urban miljö
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 422-423
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- För att åstadkomma ett hållbart byggande av anläggningsinfrastruktur i urban miljö krävs att man implementerar cirkulär ekonomi även för vägbyggnadsmaterial. Projektet tar ett helhetsgrepp (med systemperspektiv) om problematiken för snabbare implementering av alternativa material som fullgoda ersättare för traditionellt krossberg. En kort översikt ges om projektet som utgörs av tre olika steg, varav det sista avslutas under 2025. Vi ser på hela värdekedjan för att skapa en trygghet i användning av restmaterial för t ex vägbyggnation. Fokus är på urban miljö där tillgängliga volymer räcker för de aktuella byggprojekten och transportsträckorna blir korta. Labtester, fullskaletester och testytor används för att skapa dimensioneringsunderlag och rekommendationer om vilka metoder som är relevanta för att verifiera materialens och konstruktionernas funktion. Parallellt analyseras påverkan på klimat och miljö, samt tillstånds- och anmälningsärenden som ofta är flaskhalsar för implementering. Affärsmodeller och regelverk analyseras och förbättringar föreslås. Projektet har hittills fokuserat på slaggrus, krossad betong och fräsasfalt samt krossad asfalt som restmaterial. Fullskaleförsök med VTI's HVS (Heavy Vehicle Simulation) har genomförts och kalibrerats med det nya dimensioneringsverktyget EraPave och labförsök med lovande resultat. Flera testytor är anlagda och ytterligare planeras. Parallella analyser av gamla pilotvägar är påbörjade. Klimatpåverkansanalyser visar på en god potential att sänka CO2-påverkan genom användning av t ex slaggrus som förstärkningslager. Utvärdering av tillstånds- och anmälningsprocesser har gett uppslag till konkreta åtgärder. Omfattande försöksverksamhet har visat att de undersökta restmaterialen är fullgoda ersättare för traditionellt krossberg i en rad urbana hårdgjorda ytor så som gator, parkeringsplatser och GC-banor. De genomförda fullskaleförsöken görs på så kort tid att självbindande/-härdande egenskaper inte kunnat tillgodoräknas vilket gör att resultaten i en verklig konstruktion förväntas bli än bättre. En analys av provningsresultaten och existerande regelverk indikerar tydligt att vi måste gå mot mer funktionsorienterade provningsmetoder och krav. Projektresultaten indikerar att det är möjligt att skapa dimensioneringsverktyg och vägledningsdokument som bl a hjälper kommuner med planering, konsulter med projektering och entreprenörer (och materialleverantörer) med produktframtagning, kvalitetskontroll och utförande. Det finns ett utbildningsbehov hos de som ansvarar för miljöhandläggning, inte minst för att få en mer geografisk homogenitet i beslut men även för att öka förutsägbarhet och minska onödigt långa ärendetider på grund icke relevanta frågor.
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| 16. |
- Singh, Aadesh P., 1982, et al.
(författare)
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Hydrogen induced interface engineering in Fe2O3-TiO2 heterostructures for efficient charge separation for solar-driven water oxidation in photoelectrochemical cells
- 2021
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 11:8, s. 4297-4307
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor heterostructure junctions are known to improve the water oxidation performance in photoelectrochemical (PEC) cells. Depending on the semiconductor materials involved, different kinds of junctions can appear, for instance, type II band alignment where the conduction and valence bands of the semiconductor materials are staggered with respect to each other. This band alignment allows for a charge separation of the photogenerated electron-hole pairs, where the holes will go from low-to-high valance band levels and vice versa for the electrons. For this reason, interface engineering has attracted intensive attention in recent years. In this work, a simplified model of the Fe2O3-TiO2 heterostructure was investigated via first-principles calculations. The results show that Fe2O3-TiO2 produces a type I band alignment in the heterojunction, which is detrimental to the water oxidation reaction. However, the results also show that interstitial hydrogens are energetically allowed in TiO2 and that they introduce states above the valance band, which can assist in the transfer of holes through the TiO2 layer. In response, well-defined planar Fe2O3-TiO2 heterostructures were manufactured, and measurements confirm the formation of a type I band alignment in the case of Fe2O3-TiO2, with very low photocurrent density as a result. However, once TiO2 was subjected to hydrogen treatment, there was a nine times higher photocurrent density at 1.50 V vs. the reversible hydrogen electrode under 1 sun illumination as compared to the original heterostructured photoanode. Via optical absorption, XPS analysis, and (photo)electrochemical measurements, it is clear that hydrogen treated TiO2 results in a type II band alignment in the Fe2O3-H:TiO2 heterostructure. This work is an example of how hydrogen doping in TiO2 can tailor the band alignment in TiO2-Fe2O3 heterostructures. As such, it provides valuable insights for the further development of similar material combinations. This journal is
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| 17. |
- Singh, Aadesh P., 1982, et al.
(författare)
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Improved Water Oxidation Performance of Ultra-thin Planar Hematite Photoanode: Synergistic Effect of In/Sn doping and an Overlayer of Metal Oxyhydroxides
- 2020
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Ingår i: Journal of Photochemistry and Photobiology A: Chemistry. - : Elsevier BV. - 1010-6030. ; 401
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Tidskriftsartikel (refereegranskat)abstract
- Hematite is a promising photoanode candidate with many favorable material properties, such as stability and suitable band-gap. However, there are some severe challenges, including high losses due to charge recombination and slow oxidation kinetics, which can be addressed by doping and addition of co-catalysts. Here, the effects of temperature driven diffusion of substrate impurities (doping) and subsequent surface modification by metal oxy-hydroxides (co-catalysts) have been studied for enhanced water-oxidation performance in photoelectrochemical (PEC) measurements. Diffusion of indium and tin from the indium-doped tin oxide (ITO) substrate into planar films of α-Fe2O3 photoanodes results in a photocurrent density (Jph) of 0.09 mA/cm2, corresponding to an approximate 9-fold enhancement over the control pristine α-Fe2O3 (0.01 mA/cm2) at 1.23 VRHE. A thin amorphous FeOOH coating over the In/Sn co-doped α-Fe2O3 photoanode improves the water oxidation performance further, with a 211 % enhancement in Jph at 1.23 VRHE and a 0.21 V cathodic shift in onset potential. Thin layers of NiOOH and FeNiOOH co-catalysts exhibit 100 and 155 % enhancement in Jph, respectively. Characterization and electrochemical measurements reveal that the enhanced performance is a result of reduced bulk recombination by temperature driven In/Sn substrate impurity doping and improved surface oxidation kinetics by the metal oxy-hydroxide overlayer. Especially deposition of FeOOH onto In/Sn co-doped α-Fe2O3 significantly reduces resistance at the semiconductor/electrolyte interface, leading to the shift in onset potential. Further, the results indicate that all the samples exhibit a quantitative correlation between the cathodic shift in photocurrent onset potential (Vonset) and flat band potential (Vfb).
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| 18. |
- Singh, Aadesh P., 1982, et al.
(författare)
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Synergies of co-doping in ultra-thin hematite photoanodes for solar water oxidation: In and Ti as representative case
- 2020
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 10:55, s. 33307-33316
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Tidskriftsartikel (refereegranskat)abstract
- Solar energy induced water splitting in photoelectrochemical (PEC) cells is one of the most sustainable ways of hydrogen production. The challenge is to develop corrosion resistant and chemically stable semiconductors that absorb sunlight in the visible region and, at the same time, have the band edges matching with the redox level of water. In this work, hematite (alpha-Fe2O3) thin films were prepared onto an indium-doped tin oxide (ITO; In:SnO2) substrate by e-beam evaporation of Fe, followed by air annealing at two different temperatures: 350 and 500 degrees C. The samples annealed at 500 degrees C show anin situdiffusion of indium from the ITO substrate to the surface of alpha-Fe2O3, where it acts as a dopant and enhances the photoelectrochemical properties of hematite. Structural, optical, chemical and photoelectrochemical analysis reveal that the diffusion of In at 500 degrees C enhances the optical absorption, increases the electrode-electrolyte contact area by changing the surface topology, improves the carrier concentration and shifts the flat band potential in the cathodic direction. Further enhancement in photocurrent density was observed byex situdiffusion of Ti, deposited in the form of nanodisks, from the top surface to the bulk. Thein situIn diffused alpha-Fe(2)O(3)photoanode exhibits an improved photoelectrochemical performance, with a photocurrent density of 145 mu A cm(-2)at 1.23 V-RHE, compared to 37 mu A cm(-2)for the photoanode prepared at 350 degrees C; it also decreases the photocurrent onset potential from 1.13 V to 1.09 V. However, the In/Ti co-doped sample exhibits an even higher photocurrent density of 290 mu A cm(-2)at 1.23 V(RHE)and the photocurrent onset potential decreases to 0.93 V-RHE, which is attributed to the additional doping and to the surface becoming more favorable to charge separation.
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| 19. |
- Ståhle, Alexander, et al.
(författare)
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Designguide för Smarta gator
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Designguiden för smarta gator konkretiserar hur de fyra megatrenderna urbanisering, digitalisering, samhällsförändringar och miljöförändringar leder till nya krav och utformningsprinciper för framtidens gator. Guiden är tänkt att fungera som en inspiration och ett underlag för att förnya svensk gatupolicy på nationell, regional och kommunal nivå.Guiden innehåller utöver en inledning följande kapitel: en historisk tillbakablick (gatans utveckling), gatans användning, gatans delar, gatans design, designprocessen, guidens genomförande.
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| 20. |
- Valter, Mikael, 1991, et al.
(författare)
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Solvent Effects for Methanol Electrooxidation on Gold
- 2021
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:2, s. 1355-1360
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Tidskriftsartikel (refereegranskat)abstract
- A detailed understanding of the methanol electrooxidation reaction mechanism is important for the further development of methanol fuel cells. By modeling the reaction on Au(111) using density functional calculations, we investigate the impact of solvent models, focusing on the potential-determining step and the theoretical limiting potential. Both implicit solvent effects, in the form of VASPsol, and explicit solvation by water molecules are investigated. The use of explicit water molecules changes the energetics of the reaction intermediates, and it requires the addition of six water molecules to reach converged results. An important observation is that the configuration space of the explicit water molecules needs to be treated carefully. Upon comparison of the most simple vacuum model with a more advanced combined solvent model, it is clear that there are some pronounced differences; for instance, both implicit solvent effects and explicit solvation stabilize HCOOH and destabilize CO2. There are, however, qualitative agreements between the models; for instance, the first deprotonation step of methanol is found to be the potential-determining step, although the more accurate model put forth aldehyde and formate formation as possible competitive steps. The results are experimentally validated by using cyclic voltammetry.
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