| 1. |
- Fytagoridis, Anders, et al.
(författare)
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Deep Brain Stimulation of the Caudal Zona Incerta : Tremor Control in Relation to the Location of Stimulation Fields
- 2016
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Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger. - 1011-6125 .- 1423-0372. ; 94:6, s. 363-370
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Tidskriftsartikel (refereegranskat)abstract
- Background: The caudal zona incerta (cZi) and posterior subthalamic area (PSA) are an emerging deep brain stimulation (DBS) target for essential tremor (ET). Objectives: To evaluate the efficacy of tremor control in relation to the anatomical locations of stimulation fields in 50 patients with ET and DBS of the cZi. Methods: A total of 240 contacts were evaluated separately with monopolar stimulation, and amplitudes were optimized for improvement of tremor and hand function. Stimulation fields, i.e., volumes of neural activation, were simulated for each optimized setting and assembled into probabilistic stimulation maps (PSMs). Results: There were differences in the anatomical distribution of PSMs associated with good versus poor tremor control. The location of PSMs which achieved good and excellent tremor control corresponded well with the PSM for the clinically used settings, and they were located within the superior part of the PSA. Conclusions: PSMs may serve as a useful tool for defining the most efficacious anatomical location of stimulation. The best tremor control in this series of cZi DBS was achieved with stimulation of the superior part of the PSA, which corresponds to the final part of the cerebellothalamic projections before they reach the ventral lateral thalamus.
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| 2. |
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| 3. |
- Bagge, Joakim, et al.
(författare)
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Impact of stationary-phase pore size on chromatographic performance using oligonucleotide separation as a model
- 2020
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1634, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- A combined experimental and theoretical study was performed to understand how the pore size of packing materials with pores 60-300 angstrom in size affects the separation of 5-50-mer oligonucleotides. For this purpose, we developed a model in which the solutes were described as thin rods to estimate the accessible surface area of the solute as a function of the pore size and solute size. First, an analytical investigation was conducted in which we found that the selectivity increased by a factor of 2.5 when separating 5- and 15-mer oligonucleotides using packing with 300 angstrom rather than 100 angstrom pores. We complemented the analytical investigation by theoretically demonstrating how the selectivity is dependent on the column's accessible surface area as a function of solute size. In the preparative investigation, we determined adsorption isotherms for oligonucleotides using the inverse method for separations of a 9- and a 10-mer. We found that preparative columns with a 60 angstrom-pore-size packing material provided a 10% increase in productivity as compared with a 300 A packing material, although the surface area of the 60 angstrom packing is as much as five time larger.
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| 4. |
- Björnsson, Lovisa, et al.
(författare)
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Bioolja från befintliga kraftvärmeverk-en systemstudie : Sammanfattning av ett forskningssamarbete mellan Lunds Tekniska Högskola, Karlstad universitet och Kraftringen Energi
- 2021. - Rapport 123
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Rapport (populärvet., debatt m.m.)abstract
- Samhällets pågående omställning mot minskade utsläpp av växthusgaser kräver bland annat stora mängder fasta biobränslen och flytande biodrivmedel. Den svenska biobränslepotentialen domineras av bi- och restprodukter från skogen, som sågspån från sågverken och grenar och toppar (sk grot) från avverkning av skog. Att omvandla trä till flytande bränslen med hög omvandlingseffektivitet är utmanande, och kräver kommersialisering av ny och innovativ teknik. Behovet av flytande biodrivmedel i transportsektorn har därför hittills framför allt tillgodosetts genom import. Ett utökat och resurseffektivt utnyttjande av den inhemska potentialen av biomassa från skogen skulle kunna vara en viktig komponent i att nå både målet om ett fossilfritt samhälle och mål om miljömässig hållbarhet och spårbarhet för råvaran. Kraftvärmesektorn är i stora delar redan fossilfri och hanterar redan idag inhemska fasta bio-bränslen från skogen. I befintliga kraftvärmeverk finns potential för ökad nyttjandegrad av anläggningen, en befintlig infrastruktur för bränslehantering och möjlighet till värmeavsättning i fjärrvärmenät. Detta skapar förutsättningar för att i tillägg till el och värme komplettera med processer för produktion av flytande energibärare från inhemska, spårbara och hållbara biobränslen från skogen.I denna skrift sammanfattas ett forskningsprojekt där möjligheten att vidareutveckla en befintlig kraftvärmeanläggning genom integrerad produktion av pyrolysolja undersökts. Vi har ställt oss frågor som: Kan vi åstadkomma inhemsk produktion av flytande bränsle från skogsbaserade fasta biobränslen genom att kraftvärmeproduktion kombineras med pyrolysoljeproduktion? Kan detta förbättra konkurrenskraften för kraftvärmeverket vid ett framtida vikande behov av fjärrvärme inom bostadssektorn? Vad innebär möjligheten att bli producent av pyrolysolja både för egen förbrukning och för andra marknader som transportsektorn, för kraftvärmeverket och för klimatet?
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| 5. |
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| 6. |
- Cilpa-Karhu, Geraldine, et al.
(författare)
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Three complementary techniques for the clarification of temperature effect on low-density lipoprotein–chondroitin-6-sulfate interaction
- 2013
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 443:2, s. 139-147
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Tidskriftsartikel (refereegranskat)abstract
- Abstract A rigorous processing of adsorption data from quartz crystal microbalance technology was successfully combined with the data obtained by partial filling affinity capillary electrophoresis and molecular dynamics for the clarification of the temperature effect on the interaction of a major glycosaminoglycan chain chondroitin-6-sulfate (C6S) of proteoglycans with low-density lipoprotein (LDL) and with a peptide fragment of apolipoprotein B-100 (residues 3359–3377 of LDL, PPBS). Two experimental techniques and computational atomistic methods demonstrated a nonlinear pattern of the affinity of C6S at temperatures above 38.0 °C to both LDL and PPBS. The temperature affects the interaction of C6S with LDL and PPBS by influencing the structural behavior of glycosaminoglycan C6S and/or that of LDL.
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| 7. |
- Elhamili, Anisa, et al.
(författare)
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Optimizing the extraction, separation and quantification of tricyclic antidepressant drugs in human plasma with CE-ESI-TOF-MS using cationic coated capillaries
- 2011
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 32:6-7, s. 647-658
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the extraction and CE-ESI-TOF-MS analysis of tricyclic antidepressant (TCA) drugs imipramine, desipramine, clomipramine and norclomipramine in human plasma has been optimized. The CE capillaries were modified with ω-iodo-alkyl ammonium salt (M7C4I coating) to reduce analyte adsorption to the silica wall. The use of a strong cation exchange (SCX) solid-phase extraction (SPE) column specifically designed for the extraction of basic drug species from biofluids gave very clean extracts with high and reproducible recoveries. The extraction recoveries were ranging between 87 and 91% with % RSD values of 0.5-1.7% (n=3). The obtained strong cation exchange-SPE extracts of the TCA in human plasma only contained the analytes of interest. The optimized CE separation conditions were obtained by adding ACN and acetic acid to the sample while using an aqueous BGE. The CE-ESI-TOF-MS analysis was performed within 6min for all TCA analytes under the optimized condition with peak efficiencies up to 1.4×105plates/m and an average % RSD of the migration times of the analytes of 0.3% (n=5). The presented method can readily be used for the extraction and quantification of basic drug species in human biological fluids and in pharmaceutical formulations.
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| 8. |
- Enmark, Martin, 1984-, et al.
(författare)
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A closer study of peak distortions in supercritical fluid chromatography as generated by the injection
- 2015
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1400, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- Abstract In SFC the sample cannot be dissolved in the mobile phase, so it is often dissolved in pure modifier, or another liquid, sometimes resulting in serious distortions of the eluted peak profiles already at moderately high injection volumes. It is suspected the reasons for these effects are solvent strength mismatch and/or viscosity mismatch. This study presents a systematic and fundamental investigation of the origin of these peak deformations due to the injection solvent effects in SFC, using both systematic experiments and numerical modeling. The first set of experiments proved that the injection volume and the elution strength of the sample solution had a major impact of the shapes of the eluted peaks. Secondly, the sample band elution profile was numerically modeled on a theoretical basis assuming both un-retained and retained co-solvent injection plugs, respectively. These calculations quantitatively confirmed our first set of experiments but also pointed out that there is also an additional significant effect. Third, viscous fingering experiments were performed using viscosity contrast conditions imitating those encountered in SFC. These experiments clearly proved that viscous fingering effects play a significant role. A new method for determination of adsorption isotherms of solvents was also developed, called the “Retention Time Peak Method” (RTPM). The RTPM was used for fast estimation of the adsorption isotherms of the modifier and required using only two experiments.
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| 9. |
- Enmark, Martin, et al.
(författare)
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A Deeper Investigation of Strange Preparative Band Shapes of a Simple Racemic Solute on tris-(3, 5- dimethylphenyl)carbamoyl Cellulose as Chiral Stationary Phase
- 2011
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Konferensbidrag (refereegranskat)abstract
- The adsorption equilibria of racemic methyl mandelate on a tris-(3, 5-dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) has a peculiar behavior. The preparative band shape of the more retained enantiomer was very unusual with an inflection point at low concentrations whereas the less retained enantiomer shows normal type I adsorption behavior. For a deeper understanding of this separation adsorption isotherms were determined and further analyzed with Scatchard plots combined with adsorption energy distribution calculations. The less retained enantiomer was best described by Tóth adsorption isotherm while the second enantiomer was best described with a bi-Moreau adsorption isotherm. The Moreau model is an extension of the Langmuir model including non-ideal adsorbate-adsorbate interactions; here the unusual model provided an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated by synthetically generated raw adsorption slope data. It was demonstrated that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-ideal adsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature
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| 10. |
- Enmark, Martin, et al.
(författare)
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A Deeper Understanding of a Complex Adsorption Behavior in a Common Chiral, Separation System
- 2011
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Konferensbidrag (refereegranskat)abstract
- The adsorption equilibria of racemic methyl mandelate on a tris-(3,5-dimethylphenyl)carbamoyl cellulose chiral stationary phase (CSP) was investigated. This separation has previously been performed and analyzed on a methylcellulose tribenzoate coated CSP. In that case, both enantiomers could be described with a bi-Langmuir adsorption isotherm, convex upwards (type I). In our case, two fundamentally different properties were observed. First, the elution order was reversed. Furthermore, only the less retained enantiomer shows type I adsorption behavior, while the adsorption isotherm of the more retained compound contained an inflection point at low concentration. To analyze these differences, adsorption isotherms were determined and further analyzed using Scatchard plots and adsorption energy distribution calculations. The less retained enantiomer was best described by Tóth adsorption isotherm while the second enantiomer was best described with a bi-Moreau adsorption isotherm. The Moreau model is an extension of the Langmuir model including non-ideal adsorbate-adsorbate interactions; here the unusual model provided an explanation to the non-ideal adsorption of the more retained enantiomer. Furthermore, the possibility of using the Moreau model as a local model for adsorption in AED calculations was evaluated by synthetically generated raw adsorption slope data. It was demonstrated that the AED accurately could predict the number of adsorption sites for the generated data. The adsorption behavior of both enantiomers was also studied at several different temperatures and it was found to be exothermic; in addition, the non-idealadsorbate-adsorbate interaction strength decreases with increasing temperature. Stochastic analysis of the adsorption process could identify a single kinetic site for each enantiomer. The average amount of adsorption/desorption events increases and the sojourn time decreases with increasing temperature.
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