| 51. |
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| 52. |
- Heap, Michael J., et al.
(författare)
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The tensile strength of volcanic rocks : Experiments and models
- 2021
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Ingår i: Journal of Volcanology and Geothermal Research. - : Elsevier. - 0377-0273 .- 1872-6097. ; 418
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Tidskriftsartikel (refereegranskat)abstract
- The tensile strength of volcanic rock exerts control over several key volcanic processes, including fragmentation and magma chamber rupture. Despite its importance, there is a paucity of laboratory data for the tensile strength of volcanic rocks, leading to an incomplete understanding of the influence of microstructural parameters, such as pore size and shape (factors that vary widely for volcanic rocks), on their tensile strength. To circumvent problems associated with the variability of natural samples, we provide here a systematic study in which we use elastic damage mechanics code "Rock Failure Process Analysis" to perform numerical experiments to better understand the influence of porosity, pore diameter, pore aspect ratio, and pore orientation on the tensile strength of volcanic rocks. We find that porosity and pore diameter exert a first-order control on the tensile strength of volcanic rocks, and that pore aspect ratio and orientation also influence tensile strength. Tensile strength is reduced by up to a factor of two as porosity is increased from 0.05 to 0.35 or as pore diameter is increased from 1 to 2 mm. Small, but systematic, reductions in tensile strength are observed as the angle between the loading direction and the major axis of an elliptical pore is increased from 0 to 90 degrees. The influence of pore aspect ratio (the ratio of the minor to major axis of an ellipse) depends on the pore angle: when the pore angle is 0 degrees, a decrease in pore aspect ratio, from 1 (a circle) to 0.2, increases the tensile strength, whereas the same decrease in pore aspect ratio does not substantially change the tensile strength when the pore angle is 90 degrees. These latter numerical experiments show that the tensile strength of volcanic rocks can be anisotropic. Our numerical data are in broad agreement with new and compiled experimental data for the tensile strength of volcanic rocks. One of the goals of this contribution is to provide better constrained constitutive models for the tensile strength of volcanic rocks for use in volcano modelling. To this end, we present a series of theoretical and semi-empirical constitutive models that can be used to determine the tensile strength of volcanic rocks, and highlight how tensile strength estimations can influence predictions of magma overpressures and assessments of the volume and radius of a magma chamber. (c) 2021 Elsevier B.V. All rights reserved.
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| 53. |
- Henz Ryen, Astrid, 1986-
(författare)
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Exploring evolutionary and chemical space using chemoinformatic tools and traditional methods in pharmacognosy
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The number of new drugs coming to the market is declining while interest in lead discovery from natural resources is seeing a revival. Although methods for isolation and identification of natural products have advanced tremendously, methods for selection of potential leads have fallen behind. As part of the Marie Curie ITN “MedPlant: Phylogenetic exploration of medicinal plant diversity” this thesis contributed to the exploration of chemical diversity in angiosperms and the development of new tools to analyze and define the chemical potential of a plant.In Paper I, it was demonstrated that physicochemical properties of selected specialized metabolites change in different plant groups. Changes in properties were assessed using ChemGPS-NP and diversity was quantified by calculating the volume occupied by the compounds in chemical space. By discussing the results against the background of possible underlying evolutionary mechanisms, it was concluded that evolutionary processes are reflected in chemical property space. These results hold great value for further studies on the evolution of chemical diversity and biochemical traits in plants. The methods developed can be used e.g. to define and predict the chemical diversity of related taxa, providing a strategy for a guided plant selection in search for new drug leads.In Paper II, the scaffold and molecular diversity of over 5,200 sesquiterpene lactones (STLs) was investigated, using different chemoinformatic tools. Quantity and distribution of skeleton classes was determined and it was shown that different plant families possess specific sets of molecular frameworks, with considerable variation in their frequency. Clustering analysis enabled qualitative division of STLs into smaller groups with similar structural features, pointing out the differentiation of various plant groups. Including the study results, the dataset offers a compelling resource for chemosystematics, natural product research and drug lead discovery focused on STLs. It provides the basis for phylogenetic implementations due to the detailed taxonomic annotation. Since STLs display a source for new drugs, it is of high value for a guided search for plant derived drug leads.In Paper III, Lindera benzoin was subjected to phytochemical and pharmacological investigations. Phytochemical investigations led to the isolation of three new sesquiterpenes. As Native American tribes used this shrub for various medicinal purposes, e.g. cold remedy or diaphoretic, the isolated compounds were evaluated in vitro for their anti-inflammatory activity. In cellular assays, they reduced pro-inflammatory prostaglandin E2 production in A549 cells in a dose-dependent manner, which may rationalize the traditional use of this plant.
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| 54. |
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| 55. |
- Holland, Petter, 1985, et al.
(författare)
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Coupling cell division to metabolic pathways through transcription
- 2018
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Ingår i: Encyclopedia of Bioinformatics and Computational Biology: ABC of Bioinformatics. ; , s. 74-93
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Cellular growth is ensured by alternation of DNA duplication and cell division cycles. This alternation is coordinated by the interplay between enzymatic activities, called kinases, and transcription factors, to keep the cell cycle timing. Here we investigate whether transcription factors may serve as hubs connecting multi-scale cellular networks. A variant of chromatin immunoprecipitation, called ChIP-exo, was performed to identify targets of Forkhead (Fkh) transcription factors across the budding yeast genome. Data analyses indicate that the Fkh-mediated transcriptional program may activate metabolic pathways and synchronize kinase activities to guarantee alternation of DNA duplication and cell division, thereby a timely cell’s cycling.
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| 56. |
- Houlle, Patrice, et al.
(författare)
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Behavior of some Ni-base alloys and stainless steel in plate heat exchanger conditions using chlorinated sea water
- 2009
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Ingår i: European Corrosion Congress 2009, EUROCORR 2009. - 9781615677962 ; , s. 2539-2551
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Konferensbidrag (refereegranskat)abstract
- Many oil and gas offshore facilities use heat exchangers cooled with seawater. Titanium is widely used for seawater plate heat exchangers, but its availability for this market depends on other large demand from other markets like the aerospace industry. Thus, it is vital to find alternative materials in seawater heat exchangers' applications. High-alloyed stainless steels and nickel-base alloys are used for different marine and offshore applications, but have not been widely used for seawater plate heat exchangers. Most of the corrosion data available in the literature on these alloys have been obtained from laboratory experiments. Thus, there is a need to determine the corrosion resistance of these alloys under real service conditions. This is important as heat transfer, flowing and geometrical conditions of plate heat exchangers may be difficult to simulate based upon simple laboratory exposure. Therefore, a test program has been developed to test selected materials in actual plate heat exchanger conditions using natural sea water during one year and more. These materials are nickel-based alloys UNS N06625, N10276, N06059, N06200 and N06686, along with a special steel UNS N08031. The study was performed in chlorinated natural sea water from 30°C up to 60°C. The result data from this test program are presented and discussed in this paper.
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| 57. |
- Joseph, A, et al.
(författare)
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Metabolic and psychiatric effects of acyl coenzyme A binding protein (ACBP)/diazepam binding inhibitor (DBI)
- 2020
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Ingår i: Cell death & disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 11:7, s. 502-
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Tidskriftsartikel (refereegranskat)abstract
- Acyl coenzyme A binding protein (ACBP), also known as diazepam binding inhibitor (DBI) is a multifunctional protein with an intracellular action (as ACBP), as well as with an extracellular role (as DBI). The plasma levels of soluble ACBP/DBI are elevated in human obesity and reduced in anorexia nervosa. Accumulating evidence indicates that genetic or antibody-mediated neutralization of ACBP/DBI has anorexigenic effects, thus inhibiting food intake and inducing lipo-catabolic reactions in mice. A number of anorexiants have been withdrawn from clinical development because of their side effects including an increase in depression and suicide. For this reason, we investigated the psychiatric impact of ACBP/DBI in mouse models and patient cohorts. Intravenously (i.v.) injected ACBP/DBI protein conserved its orexigenic function when the protein was mutated to abolish acyl coenzyme A binding, but lost its appetite-stimulatory effect in mice bearing a mutation in the γ2 subunit of the γ-aminobutyric acid (GABA) A receptor (GABAAR). ACBP/DBI neutralization by intraperitoneal (i.p.) injection of a specific mAb blunted excessive food intake in starved and leptin-deficient mice, but not in ghrelin-treated animals. Neither i.v. nor i.p. injected anti-ACBP/DBI antibody affected the behavior of mice in the dark–light box and open-field test. In contrast, ACBP/DBI increased immobility in the forced swim test, while anti-ACBP/DBI antibody counteracted this sign of depression. In patients diagnosed with therapy-resistant bipolar disorder or schizophrenia, ACBP/DBI similarly correlated with body mass index (BMI), not with the psychiatric diagnosis. Patients with high levels of ACBP/DBI were at risk of dyslipidemia and this effect was independent from BMI, as indicated by multivariate analysis. In summary, it appears that ACBP/DBI neutralization has no negative impact on mood and that human depression is not associated with alterations in ACBP/DBI concentrations.
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| 58. |
- Larché, Nicolas, et al.
(författare)
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Effect of service conditions on the corrosion of nickel-aluminum bronze and copper-nickels alloys in seawater
- 2019
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Ingår i: NACE - International Corrosion Conference SeriesVolume 2019-March, 2019, Article number 13337Corrosion Conference and Expo 2019; Nashville; United States; 24 March 2019 through 28 March 2019. - : National Assoc. of Corrosion Engineers International.
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Konferensbidrag (refereegranskat)abstract
- Nickel-Aluminum Bronze (NAB) and Copper-Nickel alloys (CuNi) are commonly used in seawater environments due to their strength combined with a good corrosion resistance and a high resistance to biofouling. However, localized corrosion failures have been reported and are often attributed to abnormal service conditions. The effect of several service condition parameters on the localized corrosion of NAB (UNS C63000, CuAl10Ni5Fe4) and CuNi alloys 90/10 (UNS C70600) and 70/30 (UNS C71500) have been investigated in natural seawater. The results are compared with that of Aluminum-brass (UNS C68700). It includes flow conditions (flowing, quiescent and stagnant), chlorination, sulphide pollution, and crevice geometries. Exposures in both indoor (laboratory) and outdoor tanks (conditions promoting macro fouling) have been tested in temperate and in tropical seawaters. The corrosion stability of the protective oxide layer of the tested copper-based alloys was mainly affected by sulphide pollution in aerated seawater (general corrosion). Under the tested conditions, localized corrosion under-biodeposit clearly appeared as the critical failure for the tested alloys. The conditions for which biodeposit appeared critical for copper-nickel alloys was investigated.
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| 59. |
- LeBozec, Nathalie, et al.
(författare)
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Effect of climatic parameters on filiform corrosion of coated aluminium alloys AA6016
- 2003
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Ingår i: NACE - International Corrosion Conference Series. - : National Association of Corrosion Engineers International.
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Konferensbidrag (refereegranskat)abstract
- The effects of temperature, relative humidity and wet dry transition on initiation and propagation of filiform corrosion on coated aluminium alloys AA6016 have been studied. The aluminium surfaces were tested in both milled and grinded conditions with chromium, phosphate and titanium-zirconium based pretreatment. A full paint system used for automotive applications (ED coat + top-coat) and an electrodeposited coat (ED coat) were investigated for the different combinations of mechanical finish, surface pretreatment and coating system. In the temperature range between 5 to 50°C, filiform corrosion, or underfilm corrosion in general, increased significantly. The effect of relative humidity and wet-dry cycling on the other hand, seems to be strongly influenced by parameters like pretreatment, coating system, and also temperature. Filiform corrosion was the highest in the range 75 to 95 % relative humidity and a distinct maximum was observed at 85% R.H. for some coating systems. However, filiform corrosion propagated at humidity down to 40-50% R.H. For specimens with chromate and phosphate based surface pretreatments, filiform corrosion was lower after exposure to tests with wet-dry cycles. The samples with titanium-zirconium based pretreatments, on the other hand, had a very poor filiform corrosion resistance in the cyclic test compared to exposures at constant relative humidity. © 2003 by NACE International.
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| 60. |
- LeBozec, Nathalie, et al.
(författare)
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Effect of climatic parameters on filiform corrosion of coated aluminum alloys
- 2004
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Ingår i: Corrosion. - : National Assoc. of Corrosion Engineers International. - 0010-9312 .- 1938-159X. ; 60:6, s. 584-593
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Tidskriftsartikel (refereegranskat)abstract
- The effects of temperature, relative humidity, and wet-dry transition on initiation and propagation of filiform, corrosion on coated aluminum alloy 6016 (AA6016 [UNS A96016]) have been studied. Corrosion products formed in the filament were analyzed using Fourier transform infrared (FTIR)- microspectroscopy. The aluminum surfaces were tested in both milled finish and grinded conditions with chromium, phosphate, and titanium-zirconium-based pretreatment. An electrodeposited coat (ED coat) and a full paint system used for automotive applications (ED coat + topcoat) were investigated for the different combinations of mechanical finish, surface pretreatment, and coating system. In the temperature range between 5°C and 50°C, filiform corrosion, or underfilm corrosion in general, increased significantly. The effect of relative humidity and wet-dry cycling, on the other hand, seems to be strongly influenced by parameters like pretreatment, coating system, and temperature. Filiform corrosion was the highest in the range from 75% to 95% relative humidity (RH), and a distinct maximum was observed at 85% RH for some coating systems. However, filiform. corrosion propagated at humidity down to 40% to 50% RH. For specimens with chromate- and phosphate-based surface pretreatments, filiform, corrosion was lower after exposure to tests with wet-dry cycles. The samples with titanium-zirconium-based pretreatments, on the other hand, had a very poor filiform corrosion resistance in the cyclic test compared to exposures at constant relative humidity. © 2004, NACE International.
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