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- Jonsson, Caroline, 1977, et al.
(author)
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Attachment of L-Glutamate to Rutile (alpha-TiO2): A Potentiometric, Adsorption, and Surface Complexation Study
- 2009
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In: Langmuir. - 0743-7463. ; 25:20, s. 12127-12135
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Journal article (peer-reviewed)abstract
- Interactions between aqueous amino acids and mineral surfaces influence the bioavailability of amino acids in the environment, the viability of Ti implants in humans, and the role of mineral surfaces in the origin of life on Earth. We studied the adsorption Of L-glutamate on the surface of rutile (alpha-TiO2, pH(PPZC) = 5.4) in NaCl solutions using potentiometric titrations and batch adsorption experiments over a wide range of pH values, ligand-to-solid ratios, and ionic strengths. Between pH 3 and 5, glutamate adsorbs strongly, up to 1.4 mu mol m(-2), and the adsorption decreases with increasing ionic strength. Potentiometric titration measurements of proton consumption for the combined glutamate-rutile-aqueous solution system show a strong dependence on glutamate concentration. An extended triple-layer surface complexation model of all the experimental results required at least two reaction stoichiometries for glutamate adsorption, indicating the possible existence of at least two surface glutamate complexes. A possible mode of glutamate attachment involves a bridging-bidentate species binding through both carboxyl groups, which can be thought of as "lying down" on the surface (as found previously for amorphous titanium dioxide and hydrous ferric oxide). Another involves a chelating species which binds only through the gamma-carboxyl group, that is, "standing up" at the surface. The calculated proportions of these two surface glutamate species vary strongly, particularly with pH and glutamate concentration. Overall, our results serve as a basis for a better quantitative understanding of how and under what conditions acidic amino acids bind to oxide mineral surfaces.
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- Sverjensky, D. A., et al.
(author)
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Glutamate surface speciation on amorphous titanium dioxide and hydrous ferric oxide
- 2008
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In: Environmental Science & Technology. - 0013-936X. ; 42:16, s. 6034-6039
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Journal article (peer-reviewed)abstract
- Hydrous ferric oxide (HFO) and titanium dioxide exhibit similar strong attachment of many adsorbates including biomolecules. Using surface complexation modeling, we have integrated published adsorption data for glutamate on HFO over a range of pH and surface coverage with published in situ ATR-FTIR studies of glutamate speciation on amorphous titanium dioxide. The results indicate that glutamate adsorbs on HFO as a deprotonated divalent anion at pH 3-5 and 0.2 mu mol center dot m(-2) in the form of chelating-monodentate and bridging-bidentate species attached to the surface through three or four of the carboxylate oxygens, respectively. The amine group may interact weakly with the surface. However, at similar pH values and higher surface coverages, glutamate adsorbs mainly as a monovalent or divalent anion chelated to the surface by the gamma-carboxylate group. In this configuration the alpha-carboxylate and amine groups might be free to interact above the surface with the free ends of adjacent glutamates, suggesting a possible mechanism for chiral self-organization and peptide bond formation.
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| 9. |
- Arora-Jonsson, Stefan, 1969-, et al.
(author)
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Att styra organisationer med konkurrens
- 2018. - 1
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Book (other academic/artistic)abstract
- Konkurrens är en viktig och vitt spridd styrform i dagens samhälle. Tillhandahållandet av allt från dagligvaror och bilar till sjukvård, skola och tv-program styrs i allt högre grad genom att utförare får konkurrera med varandra. Konkurrens har blivit en så vanlig styrform att den ofta ses som ett ”naturligt tillstånd”, som om det inte finns några alternativ.Huvudbudskapet i denna bok är att konkurrens inte är ett naturligt tillstånd. Konkurrens behöver oftast beslutas och organiseras fram, vilket innebär att saker och ting ofta behöver ändras för att det ska kunna bli konkurrens. Författarna beskriver hur konkurrens faktiskt fungerar, varför konkurrens införs, hur konkurrens skiljer sig från andra mer välkända styrformer och vilka resultat man kan vänta sig vid införandet av konkurrens som styrform. Till exempel förklaras varför konkurrens ofta leder till mer av samma i stället för ökad variation, och hur professioner som läkare och lärare påverkas av att konkurrera.Exemplen i boken kommer framför allt från offentlig sektor, men principerna fungerar lika väl för andra sektorer. Författarna menar att detta är värdefull kunskap för alla som är chefer, medarbetare eller kunder i organisationer som har konkurrensutsatts – vilket inbegriper de flesta i vårt samhälle.
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| 10. |
- Asp, Julia, 1973, et al.
(author)
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Cardiomyocyte clusters derived from human embryonic stem cells share similarities with human heart tissue.
- 2010
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In: Journal of molecular cell biology. - : Oxford University Press (OUP). - 1759-4685 .- 1674-2788. ; 2:5, s. 276-83
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Journal article (peer-reviewed)abstract
- Cardiotoxicity testing is a key activity in the pharmaceutical industry in order to detect detrimental effects of new drugs. A reliable human in vitro model would both be beneficial in selection of lead compounds and be important for reducing animal experimentation. However, the human heart is a complex organ composed of many distinct types of cardiomyocytes, but cardiomyocyte clusters (CMCs) derived from human embryonic stem cells could be an option for a cellular model. Data on functional properties of CMCs demonstrate similarities to their in vivo analogues in human. However, development of an in vitro model requires a more thorough comparison of CMCs to human heart tissue. Therefore, we directly compared individually isolated CMCs to human fetal, neonatal, adult atrial and ventricular heart tissues. Real-time qPCR analysis of mRNA levels and protein staining of ion channels and cardiac markers showed in general a similar expression pattern in CMCs and human heart. Moreover, a significant decrease in beat frequency was noted after addition of Zatebradine, a blocker to I(f) involved in regulation of spontaneous contraction in CMCs. The results underscore the similarities of CMCs to human cardiac tissue, and further support establishment of novel cardiotoxicity assays based on the CMCs in drug discovery.
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