| 1. |
- Albèr, Cathrine, et al.
(författare)
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Hydration of Hyaluronan : Effects on Structural and Thermodynamic Properties
- 2015
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 119:11, s. 4211-4219
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan (HA) is a frequently occurring biopolymer with a large variety of functions in nature. During the past 60 years, there have been numerous reports on structural and dynamic behavior of HA in water. Nevertheless, studies covering a wider concentration range are still lacking. In this work, we use isothermal scanning sorption calorimetry for the first time to investigate hydration-induced transitions in HA (sodium hyaluronate, 17 kDa). From this method, we obtain the sorption isotherm and the enthalpy and the entropy of hydration. Thermotropic events are evaluated by differential scanning calorimetry (DSC), and structure analysis is performed with X-ray scattering (SWAXS) and light and scanning electron microscopy. During isothermal hydration, HA exhibits a glass transition, followed by crystallization and subsequent dissolution of HA crystals and formation of a one-phase solution. Structural analysis reveals that the crystal may be indexed on an orthorhombic unit cell with space group P212121. Crystallization of HA was found to occur either through endothermic or exothermic processes, depending on the temperature and water content. We propose a mechanism of crystallization that explains this phenomenon based on the interplay between the hydrophobic effect and strengthening of hydrogen bonds during formation of crystals. The combined results were used to construct a binary phase diagram for the HA–water system.
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| 2. |
- Ali, Abdullah, 1985-, et al.
(författare)
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Dehydration affects drug transport over nasal mucosa
- 2019
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Ingår i: Drug Delivery. - : Taylor & Francis. - 1071-7544 .- 1521-0464. ; 26:1, s. 831-840
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Tidskriftsartikel (refereegranskat)abstract
- Formulations for nasal drug delivery often rely on water sorption to adhere to the mucosa, which also causes a higher water gradient over the tissue and subsequent dehydration. The primary aim of this study was therefore to evaluate mucosal response to dehydration and resolve the hypothesis that mucoadhesion achieved through water sorption could also be a constraint for drug absorption via the nasal route. The effect of altering water activity of the vehicle on Xylometazoline HCl and Cr-EDTA uptake was studied separately using flow through diffusion cells and excised porcine mucosa. We have shown that a modest increase in the water gradient over mucosa induces a substantial decrease in drug uptake for both Xylometazoline HCl and Cr-EDTA. A similar result was obtained when comparing two different vehicles on the market; Nasoferm (Nordic Drugs, Sweden) and BLOX4 (Bioglan, Sweden). Mucoadhesion based on water sorption can slow down drug uptake in the nasal cavity. However, a clinical study is required to determine whether prolonged duration of the vehicle or preventing dehydration of the mucosa is the most important factor for improving bioavailability.
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| 3. |
- Andersson, Alf, et al.
(författare)
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Inline Process Control – a concept study of efficient in-line process control and process adjustment with respect to product geometry
- 2016
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Ingår i: Swedish Production Symposium 2016 SPS 2016. - Lund, Sweden.
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Konferensbidrag (refereegranskat)abstract
- All manufacturing processes have variation which may violate the fulfillment of assembly, functional, geometrical or esthetical requirements and difficulties to reach desired form in all areas. The cost for geometry defects rises downstream in the process chain. Therefore, it is vital to discover these defects as soon as they appear. Then adjustments can be done in the process without losing products or time. In order to find a solution for this, a project with the overall scope “development of an intelligent process control system” has been initiated. This project consists of five different work packages: Inline measurement, Process Evaluation, Corrective actions, Flexible tooling and demonstrator cell. These work packages address different areas which are necessary to fulfill the overall scope of the project. The system shall both be able to detect geometrical defects, propose adjustments and adjust simple process parameters. The results are demonstrated in a demo cell located at Chalmers University of Technology. In the demonstrator all the different areas have been verified in an industrial case study – assembly of GOR Volvo S80. Efficient offline programming for robot based measurement, efficient process evaluation based on case base reasoning (CBR) methodology, flexible fixtures and process adjustments based on corrective actions regarding in going part positioning.
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| 4. |
- Cao, Zhen, et al.
(författare)
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Pool boiling of HFE-7200 on nanoparticle-coating surfaces: Experiments and heat transfer analysis
- 2018
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310 .- 1879-2189. ; 133, s. 548-560
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, an electrophoretic deposition method was employed to modify copper surfaces withCu-Zn (100 nm) nanoparticles. Pool boiling heat transfer of HFE-7200 on the modified surfaces was experimentally studied. The results showed that the heat transfer coefficient on the modified surfaces was significantly enhanced compared with that on a smooth surface, e.g., a maximum 100% enhancement,while the maximum superheat on the modified surfaces was around 20 K lower than that on the smooth surface. However, the critical heat flux (CHF) was not improved considerably, and supplementary tests indicated that the wickability of HFE-7200 was almost the same on the modified surfaces and the smooth surface. The departure diameters of bubbles were recorded by a high speed camera, which were compared with several models in literature. Active nucleation site sizes were evaluated by the Hsu nucleation theory and active nucleation site densities were estimated by appropriate correlations.In addition, a heat transfer model, considering natural convection, re-formation of thermal boundary layer and microlayer evaporation, was formulated to predict the heat transfer on the modified surfaces and the smooth surface. A relatively good prediction was achieved.
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| 5. |
- Danielsson, Ravi, et al.
(författare)
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Tracing Aluminium-based Adjuvants : Their Interactions with Immune Competent Cells and their Effect on Mitochondrial Activity
- 2018
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Ingår i: Open Immunology Journal. - : Bentham eBooks. - 1874-2262. ; 8, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies revealing the immune stimulatory properties of aluminium-based adjuvants (ABAs) have been impaired by the absence of simple and reliable methods of tracing the adjuvants and their effect on biochemical processes upon endocytosis. Objective: To verify that labelling of ABAs with lumogallion doesn’t affect the physicochemical properties of the adjuvant; tracing cellular interaction with aluminium adjuvants; explore their effect on metabolic activity upon endocytosis. Methods: Physicochemical characterization by Z-potential and size distribution of ABAs labelled with lumogallion. Cellular interactions with ABAs by flow cytometry and confocal microscopy. Metabolic activity explored by measuring transformation of tetrazolium into formazan. Results: No or minor change of zeta potential and average particle size of lumogallion labelled aluminium oxyhydroxide, AlO(OH) and aluminium hydroxyphosphate, Al(OH)x(PO4 )y. Both phagocytosing and non-phagocytosing leukocytes became associated with ABAs at concentrations expected after in vivo administration of a vaccine. The ABAs were relatively toxic, affecting both lymphocytes and monocytes, and Al(OH)x(PO4 )y was more toxic than AlO(OH). Endocytosed aluminium adjuvant particles were not secreted from the cells and remained intracellular throughout several cell divisions. The presence of ABAs increased the mitochondrial activity of the monocytic cell line THP-1 and peripheral monocytes, as based on the transformation of tetrazolium into formazan. Conclusion: Lumogallion labelled ABAs is a valuable tool tracing interactions between ABAs and cells. Labelled ABAs can be traced intracellularly and ABAs are likely to remain intracellular for a long period of time. Intracellular ABAs increase the mitochondrial activity and the presence of intracellular Al ions is suggested to cause an increased mitochondrial activity. Keywords: Aluminium based adjuvant, Lumogallion, Mitochondrial activity, MTT assay, Phagocytosis, ABAS, Zeolites.
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| 6. |
- Falco, Cigdem Yucel, et al.
(författare)
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Chitosan-Dextran Sulfate Hydrogels as a Potential Carrier for Probiotics
- 2017
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Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 172, s. 175-183
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Tidskriftsartikel (refereegranskat)abstract
- Physical and chemical (crosslinked with genipin) hydrogels based on chitosan and dextran sulfate were developed and characterized as novel bio-materials suitable for probiotic encapsulation. The swelling of the hydrogels was dependent on the composition and weakly influenced by the pH of the media. The morphology analysis supports the swelling data showing distinct changes in microstructure depending on the composition. The viability and culturability tests showed approx. 3.6 log CFU/mL decrease of cells (L. acidophilus as model) incorporated into chemical hydrogels when compared to the number of viable native cells. However, the live/dead viability assay evidenced that a considerable amount of viable cells were still entrapped in the hydrogel network and therefore the viability is most likely underestimated. Overall, the developed systems are robust and their structure, rheology and swelling properties can be tuned by changing the blend ratio, thus constituting appealing bio-matrices for cell encapsulation.
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| 7. |
- Pankratov, Dmitry, et al.
(författare)
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Supercapacitive Biosolar Cell Driven by Direct Electron Transfer between Photosynthetic Membranes and CNT Networks with Enhanced Performance
- 2017
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 2:11, s. 2635-2639
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Tidskriftsartikel (refereegranskat)abstract
- Integrating photosynthetic cell components with nanostructured materials can facilitate the conversion of solar energy into electric power for creating sustainable carbon-neutral energy sources. With the aim at exploring efficient photoinduced biocatalytic energy conversion systems, we have used an amidated carbon nanotube (aCNT) networked matrix to integrate thylakoid membranes (TMs) for construction of a direct electron transfer-driven biosolar cell. We have evaluated the resulting photobioelectrochemical cells systematically. Compared to the carboxylated CNT (cCNT)-TMs system, the aCNT-TMs system enabled a 1.5-fold enhancement in photocurrent density. This system offers more advantages including a reduced charge-transfer resistance, a lower open-circuit potential, and an improved cell stability. More remarkably, the average power density of the optimized cells was 250 times higher than that of reported analogue systems. Our results suggest the significance of physical and electronic interactions between the photosynthetic components and the support nanomaterials and may offer new clues for designing improved biosolar cells.
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| 8. |
- Parunova, Yulia, et al.
(författare)
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Potentially implantable biocathode with the function of charge accumulation based on nanocomposite of polyaniline/carbon nanotubes
- 2016
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Ingår i: Russian journal of electrochemistry. - : Springer. - 1023-1935 .- 1608-3342. ; 52:12, s. 1166-1171
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Tidskriftsartikel (refereegranskat)abstract
- A potentially implantable biocathode with the function of charge accumulation based on a nanobiocomposite including multiwall carbon nanotubes, polyaniline, and bilirubin oxidase is developed. The regularities of the functioning of the obtained electrode are studied in air-satd. phosphate buffer soln., pH 7.4 (PB), and also in phosphate buffer soln. contg. redox-active blood components (BMB). The open circuit potential of the biocathode is 0.33 and 0.08 V vs. the SCE in PB and BMB, resp.; it is completely restored after at least three self-charge/discharge cycles with connection to resistors with different resistance. Bioelectrocatalytic c.d. of oxygen redn. is 0.50 and 0.42 mA cm-2 with the residual activity of 78 and 60% of the initial value after 12 h of continuous operation in PB at 25°C and in BMB at 37°C, resp.
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| 9. |
- Stenbæk, Jonas, et al.
(författare)
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An alternative anionic bio-sustainable anti-fungal agent : Investigation of its mode of action on the fungal cell membrane
- 2017
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 497, s. 242-248
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Tidskriftsartikel (refereegranskat)abstract
- The potential of a lactylate (the sodium caproyl lactylate or C10 lactylate), a typical food grade emulsifier, as an anionic environmental friendly anti-fungal additive was tested in growth medium and formulated in a protective coating for exterior wood. Different laboratory growth tests on the blue stain fungus Aureobasidium pullulans were performed and its interactions on a model fungal cell membrane were studied. Promising short term anti-fungal effects in growth tests were observed, although significant but less dramatic effects took place in coating test on wood panels. Scanning electron microscope analysis shows clear differences in the amount of fungal slime on the mycelium of Aureobasidium pullulans when the fungus was exposed of C10 lactylate. This could indicate an effect on the pullulan and melanin production by the fungus. Moreover, the interaction studies on model fungal cell membranes show that C10 lactylate affects the phospholipid bilayer in a similar manner to other negative charged detergents. (C) 2017 Elsevier Inc. All rights reserved.
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| 10. |
- Wu, Zan, et al.
(författare)
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Pool boiling heat transfer of n -pentane and acetone on nanostructured surfaces by electrophoretic deposition
- 2019
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Ingår i: Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2018, vol 8b. - : Amer Soc Mechanical Engineers. - 9780791852125
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Konferensbidrag (refereegranskat)abstract
- This work aims to investigate pool boiling heat transfer enhancement by using nanostructured surfaces. Two types of nanostructured surfaces were employed, gold nanoparticlecoated surfaces and alumina nanoparticle-coated surfaces. The nanostructured surfaces were fabricated by an electrophoretic deposition technique, depositing nanoparticles in a nanofluid onto smooth copper surfaces under an electric field. N -pentane and acetone were tested as working fluids. Compared to the smooth surface, the pool boiling heat transfer coefficient has been increased by 80% for n -pentane and acetone. Possible mechanisms for the enhancement in heat transfer are qualitatively provided. The increase in active nucleation site density due to multiple micro/nanopores on nanoparticle-coated surfaces is likely the main contributor. The critical heat flux on nanostructured surfaces are approximately the same as that on the smooth surface because both smooth and modified surfaces show similar wickability for the two working fluids.
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