| 1. |
- Baresel, Christian, et al.
(författare)
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WEBAP - Vågdriven syrepump för Östersjön
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektets huvudsakliga syfte har varit att utveckla och testa en metod för syresättning av djupvatten i Östersjön genom nedpumpning av syrerikt ytvatten med hjälp av vågdrivna syrepumpar. Inom projektet har två olika pilotanläggningar tagits fram, byggts och varit i drift mellan 2010 och 2013. En vågdriven pump (WEBAP I) testades under 2 år i Hanöbukten utanför Simrishamn och en elektrisk pump (WEBAP II) placerades i Kanholmsfjärden i Stockholms skärgård. Förutom tester for att undersöka den vågdrivna pumpens effektivitet och framtida utformning så har även effekterna av syresättning på omgivande vattens syre- och fosforkoncentrationer studerats under projektet. Med hjälp av modeller studerades uppskalning av tekniken samt beräkningar av åtgärdens klimatavtryck (carbon footprint) med hjälp av förenklad livscykelanalysmetodik (LCA). Projektet har tagit fram olika tekniska alternativ av syrepumpar för olika behov. Den vågdrivna syrepumpen använder sig direkt av vågorna som energi- och syreresurs vilket har flera fördelar, bland annat en enkel och robust konstruktion samt lokalt tillförd energi genom att vågor nyttjas. Den eldrivna pumpen är en nyutveckling som möjliggör att pumpning kan drivas av vind- och solenergi eftersom effektförbrukningen i pumpen är låg. De två testade systemen visade sig kunna pumpa ner stora mängder ytvatten, men ytterligare förbättringar och utveckling krävs för långsiktigt störningsfri funktion. Rapporten ger en del förslag till sådan utveckling.
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| 2. |
- Berglund, Annika, et al.
(författare)
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Higher prehospital priority level of stroke improves thrombolysis frequency and time to stroke unit : the Hyper Acute STroke Alarm (HASTA) study
- 2012
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Ingår i: Stroke. - New York : American Heart Association. - 0039-2499 .- 1524-4628. ; 43:10, s. 2666-2670
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Early initiated treatment of stroke increases the chances of a good recovery. This randomized controlled study evaluates how an increased priority level for patients with stroke, from level 2 to 1, from the Emergency Medical Communication Center influences thrombolysis frequency, time to stroke unit, and whether other medical emergencies reported negative consequences.METHODS: Patients aged 18 to 85 years in Stockholm, Sweden, with symptoms of stroke within 6 hours were randomized from the Emergency Medical Communication Center or emergency medical services to an intervention group, priority level 1, immediate call of an ambulance, or to a control group with standard priority level, that is, priority level 2 (within 30 minutes). Before study start, an educational program on identification of stroke and importance of early initiated treatment was directed to all medical dispatchers and ambulance and emergency department personnel.RESULTS: During 2008, 942 patients were randomized of which 53% (n=496) had a final stroke/transient ischemic attack diagnosis. Patients in the Emergency Medical Communication Center randomized intervention group reached the stroke unit 26 minutes earlier than the control group (P<0.001) after the emergency call. Thrombolysis was given to 24% of the patients in the intervention group compared with 10% of the control subjects (P<0.001). The higher priority level showed no negative effect on other critical ill patients requiring priority level 1 prehospital attention.CONCLUSIONS: This randomized study shows negligible harm to other medical emergencies, a significant increase in thrombolysis frequency, and a shorter time to the stroke unit for patients with stroke upgraded to priority level 1 from the Emergency Medical Communication Center and through the acute chain of stroke care.
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| 3. |
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| 4. |
- Córdova, Armando, et al.
(författare)
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Amino Acid-Catalyzed Neogenesis of Carbohydrates : A Plausible Ancient Transformation
- 2005
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 11:16, s. 4772-4784
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Tidskriftsartikel (refereegranskat)abstract
- Hexose sugars play a fundamental role in vital biochemical processes and their biosynthesis is achieved through enzyme-catalyzed pathways. Herein we disclose the ability of amino acids to catalyze the asymmetric neogenesis of carbohydrates by sequential cross-aldol reactions. The amino acids mediate the asymmetric de novo synthesis of natural L- and D-hexoses and their analogues with excellent stereoselectivity in organic solvents. In some cases, the four new stereocenters are assembled with almost absolute stereocontrol. The unique feature of these results is that, when an amino acid is employed as the catalyst, a single reaction sequence can convert a protected glycol aldehyde into a hexose in one step. For example, proline and its derivatives catalyze the asymmetric neogenesis of allose with >99 % ee in one chemical manipulation. Furthermore, all amino acids tested catalyzed the asymmetric formation of natural sugars under prebiotic conditions, with alanine being the smallest catalyst. The inherent simplicity of this catalytic process suggests that a catalytic prebiotic “gluconeogenesis” may occur, in which amino acids transfer their stereochemical information to sugars. In addition, the amino acid catalyzed stereoselective sequential cross-aldol reactions were performed as a two-step procedure with different aldehydes as acceptors and nucleophiles. The employment of two different amino acids as catalysts for the iterative direct aldol reactions enabled the asymmetric synthesis of deoxysugars with >99 % ee. In addition, the direct amino acid catalyzed C2+C2+C2 methodology is a new entry for the short, highly enantioselective de novo synthesis of carbohydrate derivatives, isotope-labeled sugars, and polyketide natural products. The one-pot asymmetric de novo syntheses of deoxy and polyketide carbohydrates involved a novel dynamic kinetic asymmetric transformation (DYKAT) mediated by an amino acid.
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| 5. |
- Córdova, Armando, et al.
(författare)
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Plausible origins of homochirality in the amino acid catalyzed neogenesis of carbohydrates
- 2005
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 2005, s. 2047-2049
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Tidskriftsartikel (refereegranskat)abstract
- The intrinsic ability of amino acids to catalyze the asymmetric formation of carbohydrates, which enzymes have mediated for millions of years, with significant amplification of enantiomeric excess suggests a plausible ancient catalytic process for the evolution of homochirality.
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| 6. |
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| 7. |
- Engqvist, Anders, et al.
(författare)
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Vattenutbyte i Björnöfjärdssystemet
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vattenutbytet för hela Björnöfjärdssystemet (uppdelat i sina tre delbassänger: Björnöfjärden, Säbyviken samt Torpe-Infjärden) har modellerats för 12-årsperioden 1993 till och med 2004 med CouBa -modellen. Drivningen har utformats som vattenstånds- och täthetsvariationer för den hydrauliska randen mot Nämdöfjärden, vinddriven vertikal omblandning samt sötvattentillrinning. Hypsografiska sund- och bassängdata har omformats till det format som modellen kräver, men har för övrigt inte modifierats t.ex. för den vassbeväxning som föreligger i sunden. Långtidsmedelvärdet för det utbytta volymflödet till hela Björnöfjärdsområdet har beräknats till 0,96 m3/s, vilket är i det närmaste identiskt med tidigare uppskattning baserad på massbalans för salt. Den genomsnittliga uppehållstiden för vattnet (AvA) i Björnöfjärdssystemet har på samma sätt beräknats till cirka 4,5 månad för ytvattnet respektive 3 månader för bottenvattnet. I jämförelse med majoriteten av Östersjöns kustområden är detta att betrakta som ett mycket långsamt vattenutbyte, vilket förklaras av de morfologiska förhållandena med ett smalt och grunt sund mellan Björnöfjärdssystemet och den utanförliggande Nämdöfjärden.
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| 8. |
- Engqvist, Cecilia, et al.
(författare)
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Interactions between single latex particles and silica surfaces studied with AFM
- 2007
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 302:03-jan, s. 197-203
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Tidskriftsartikel (refereegranskat)abstract
- The spreading of single styrene-acrylic latex particles on silicon oxide C surfaces was studied using atomic force microscopy (AFM). Three latexes with different glass transition temperature (Tg) were used and the effects of temperature, time and preparation method were investigated. Particle sizes and shape were measured with AFM and the contact angles were calculated. The observed rate for the spreading of latex particles was low and it took several days before the particles reached steady state, even at temperatures well above their T-g. The experimental particle spreading results deviated with two orders of magnitude from predictions Using the WLF equation for polymer diffusion. The deviation could be attributed to polymer-surface interactions that slowed down the particle spreading. The work of adhesion was calculated using two models. The results from using the regular Young-Dupre equation and a modified version of this equation that also included the mechanical properties (E-modulus and Poisson's ratio) of the latexes, were compared. For soft latex particles the results from the two models agreed well and were of the order of 75 J/m(2), but for glassy latexes the Young-Dupre equation underestimated the work of adhesion.
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| 9. |
- Engqvist, Magnus, 1973-
(författare)
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Direct Amino Acid-Catalyzed Enantioselective α-Oxidation Reactions and Asymmetric de novo Synthesis of Carbohydrates
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ability of amino acids to form nucleophilic enamines with aldehydes and ketones has been used in the development of asymmetric α-oxidation reactions with electrophilic oxidizing agents. Singlet molecular oxygen has for the first time been asymmetrically incorporated into aldehydes and ketones, and the products were isolated as their corresponding diols in good yields and ee’s. Organocatalytic α-oxidations of cyclic ketones with iodosobenzene and N-sulfonyloxaziridine were also possible and furnished after reduction the product diols in generally low yields and in low to good ee’s. Amino acids have also been shown to catalyze the formation of carbohydrates by sequential aldol reactions. For example, proline and hydroxy proline mediate a highly selective trimerisation of α-benzyloxyacetaldehyde into allose, which was obtained in >99 % ee. Non linear effect studies of this reaction revealed the largest permanent nonlinear effect observed in a proline-catalyzed reaction to date. Moreover, polyketides were also assembled in a similar fashion by an amino acid-catalyzed one-pot reaction, and was successful for the trimerisation of propionaldehyde, however the sequential cross aldol reactions suffered from lower selectivities. This problem was overcome by the development of a two-step synthesis that enabled the formation of a range of polyketides with excellent selectivities from a variety of aldehydes. The method furnishes the polyketides via the shortest route reported and in comparable product yields to most multi-step synthesis. All polyketides were isolated as single diastereomers with >99 % ee. Based on the observed amino acid-catalysis, amino acids are thought to have taken part in the prebiotic formation of tetroses and hexoses.
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| 10. |
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