| 1. |
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| 2. |
- Borgani, Riccardo, et al.
(författare)
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Background-Force Compensation in Dynamic Atomic Force Microscopy
- 2017
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Ingår i: Physical Review Applied. - : AMER PHYSICAL SOC. - 2331-7019. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Background forces are linear long-range interactions of the cantilever body with its surroundings that must be compensated for in order to reveal tip-surface force, the quantity of interest for determining material properties in atomic force microscopy. We provide a mathematical derivation of a method to compensate for background forces, apply it to experimental data, and discuss how to include background forces in simulation. Our method, based on linear-response theory in the frequency domain, provides a general way of measuring and compensating for any background force and it can be readily applied to different force reconstruction methods in dynamic AFM.
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| 3. |
- Brandner, Birgit D., et al.
(författare)
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Solvent segregation and capillary evaporation at a superhydrophobic surface investigated by confocal Raman microscopy and force measurements
- 2011
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Ingår i: SOFT MATTER. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 7:3, s. 1045-1052
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Tidskriftsartikel (refereegranskat)abstract
- Wetting of water, a 1 : 1 water/ethanol mixture and an aqueous dodecylbenzene sulfonic acid surfactant solution on hydrophobic and superhydrophobic surfaces were studied using confocal Raman microscopy. The superhydrophobic surfaces were prepared by immersion of a glass substrate in a silica particle/fluoropolymer formulation followed by silanization. Preparation of hydrophobic surfaces was done in the same way with the exception that the silica particles were excluded from the formulation. The hydrophobic and superhydrophobic surfaces were characterized with respect to surface roughness using AFM, and by contact angle measurements using different liquids. Confocal Raman microscopy measurements in a 1 : 1 water/ethanol mixture showed an enrichment of ethanol close to the superhydrophobic surface, which could not be observed for the hydrophobic surface. Unexpectedly, the Raman spectrum of a pure water film in close proximity to the superhydrophobic surface displayed some differences compared to that of bulk water and indicated a stronger hydrogen-bonding close to the superhydrophobic surface. Evidence for capillary evaporation next to the superhydrophobic surface was also found, and this results in very long-range capillary attraction between one superhydrophobic surface and a hydrophobic colloidal probe as shown by AFM colloidal probe force measurements. Addition of a surfactant or ethanol suppresses capillary evaporation.
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| 4. |
- Glimelius, Bengt, et al.
(författare)
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U-CAN : a prospective longitudinal collection of biomaterials and clinical information from adult cancer patients in Sweden.
- 2018
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Ingår i: Acta Oncologica. - : Taylor & Francis. - 0284-186X .- 1651-226X. ; 57:2, s. 187-194
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Tidskriftsartikel (refereegranskat)abstract
- Background: Progress in cancer biomarker discovery is dependent on access to high-quality biological materials and high-resolution clinical data from the same cases. To overcome current limitations, a systematic prospective longitudinal sampling of multidisciplinary clinical data, blood and tissue from cancer patients was therefore initiated in 2010 by Uppsala and Umeå Universities and involving their corresponding University Hospitals, which are referral centers for one third of the Swedish population.Material and Methods: Patients with cancer of selected types who are treated at one of the participating hospitals are eligible for inclusion. The healthcare-integrated sampling scheme encompasses clinical data, questionnaires, blood, fresh frozen and formalin-fixed paraffin-embedded tissue specimens, diagnostic slides and radiology bioimaging data.Results: In this ongoing effort, 12,265 patients with brain tumors, breast cancers, colorectal cancers, gynecological cancers, hematological malignancies, lung cancers, neuroendocrine tumors or prostate cancers have been included until the end of 2016. From the 6914 patients included during the first five years, 98% were sampled for blood at diagnosis, 83% had paraffin-embedded and 58% had fresh frozen tissues collected. For Uppsala County, 55% of all cancer patients were included in the cohort.Conclusions: Close collaboration between participating hospitals and universities enabled prospective, longitudinal biobanking of blood and tissues and collection of multidisciplinary clinical data from cancer patients in the U-CAN cohort. Here, we summarize the first five years of operations, present U-CAN as a highly valuable cohort that will contribute to enhanced cancer research and describe the procedures to access samples and data.
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| 5. |
- Huang, Hui, et al.
(författare)
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Local surface mechanical properties of PDMS-silica nanocomposite probed with Intermodulation AFM
- 2017
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Ingår i: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 150, s. 111-119
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical properties of polymeric nanocomposites are strongly affected by the nature of the interphase between filler and matrix, which can be controlled by means of surface chemistry. In this report, we utilize intermodulation atomic force microscopy (ImAFM) to probe local mechanical response with nanometer-scale resolution of poly(dimethylsiloxane) (PDMS) coatings with and without 20 wt% of hydrophobic silica nanoparticles. The data evaluation is carried out without inferring any contact mechanics model, and is thus model-independent. ImAFM imaging reveals a small but readily measurable inhomogeneous mechanical response of the pure PDMS surface layer. The analysis of energy dissipation measured with ImAFM showed a lowering of the viscous response due to the presence of the hydrophobic silica nanoparticles in the polymer matrix. An enhanced elastic response was also evident from the in-phase stiffness of the matrix, which was found to increase by a factor of 1.5 in presence of the nanoparticles. Analysis of dissipation energy and stiffness in the immediate vicinity of the nanoparticles provides an estimate of the interphase thickness. Because the local stiffness varies significantly near the nanoparticle, AFM height images contain artifacts that must be corrected in order to reveal the true surface topography. Without such a correction the AFM height images erroneously show that the stiff particles protrude from the surface, whereas corrected images show that they are actually embedded in the matrix and likely covered with a thin layer of polymer.
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| 6. |
- Jafarzadeh, Shadi, et al.
(författare)
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Active corrosion protection by conductive composites of polyaniline in a UV-cured polyester acrylate coating
- 2016
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Ingår i: Progress in organic coatings. - : Elsevier. - 0300-9440 .- 1873-331X. ; 90, s. 154-162
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Tidskriftsartikel (refereegranskat)abstract
- Polyaniline doped with phosphoric acid (PANI-PA) was synthesized and characterized by impedance and Raman spectroscopy. Exposure to UV-light resulted in a slight decrease in the PANI's electrical conductivity and no significant change in the oxidation state (of an emeraldine salt). Composite coatings containing 0, 1, 3 and 5 wt.% PANI-PA in a UV-curable polyester acrylate (PEA) resin were prepared and applied on polished carbon steel. Closely packed PANI-PA particles of several tens of nanometers were observed inside the composite coating by scanning electron microscopy, and a connected conductive network across the film was detected by Peak Force TUNA atomic force microscopy. The evolution of open circuit potential and impedance data during long-term exposure to 3 wt.% NaCl electrolyte revealed that the short-term barrier-type corrosion protection provided by the insulating PEA coating can be turned into a long-term and active protection by addition of as little as 1 wt.% PANI-PA to the formulation. Stable ennoblement in the corrosive media was observed for the coatings containing conducting polymer up to 3 wt.%. However, higher content of PANI-PA (5 wt.%) led to poorer protective properties, probably due to the hydrophilicity of PANI-PA facilitating water transport in the coating and the presence of potentially weaker spots in the film. An iron oxide layer was found to fully cover the metal surface beneath the coatings containing PANI-PA after final failure observed by electrochemical testing.
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| 7. |
- Jafarzadeh, Shadi, et al.
(författare)
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Nanoscale Electrical and Mechanical Characteristics of Conductive Polyaniline Network in Polymer Composite Films
- 2014
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:21, s. 19168-19175
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Tidskriftsartikel (refereegranskat)abstract
- The presence and characteristics of a connected network of polyaniline (PANI) within a composite coating based on polyester acrylate (PEA) has been investigated. The bulk electrical conductivity of the composite was measured by impedance spectroscopy. It was found that the composite films containing PANI have an electrical conductivity level in the range of semiconductors (order of 10–3 S cm–1), which suggests the presence of a connected network of the conductive phase. The nanoscopic distribution of such a network within the cured film was characterized by PeakForce tunneling atomic force microscopy (AFM). This method simultaneously provides local information about surface topography and nanomechanical properties, together with electrical conductivity arising from conductive paths connecting the metallic substrate to the surface of the coating. The data demonstrates that a PEA-rich layer exists at the composite–air interface, which hinders the conductive phase to be fully detected at the surface layer. However, by exposing the internal structure of the composites using a microtome, a much higher population of a conductive network of PANI, with higher elastic modulus than the PEA matrix, was observed and characterized. Local current–voltage (I–V) spectroscopy was utilized to investigate the conduction mechanism within the nanocomposite films, and revealed non-Ohmic characteristics of the conductive network.
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| 8. |
- Jafarzadeh, Shadi, et al.
(författare)
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Toward Homogeneous Nanostructured Polyaniline/Resin Blends
- 2011
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 3:5, s. 1681-1691
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Tidskriftsartikel (refereegranskat)abstract
- The high interest in applications of conducting polymers, especially polyaniline (PANI), makes it important to overcome limitations for effective usage due to poor processability and solubility. One promising approach is to make blends of PANT in polymeric resins. However, in this approach other problems related to the difficulty of achieving a homogeneous PANI dispersion arise. The present article is focused on this general problem, and we discuss how the synthesis method, choice of dopant and solvent as well as interfacial energies influence the dispersibility. For this purpose, different synthesis methods and dopants have been employed to prepare nanostructures of polyaniline. Dynamic light scattering analysis of dispersions of the synthesized particles in several solvents was employed in order to understand how the choice of solvent affects PANT aggregation. Further information on this subject was achieved by scanning electron microscopy studies of PANT powders dried from various solutions. On the basis of these results, acetone was found to be a suitable dispersion medium for PANI. The polymer matrix used to make the blends in this work is a UV-curing solvent-free resin. Therefore, there is no low molecular weight liquid in the system to facilitate the mixing process and promote formation of homogeneous dispersions. Thus, a good compatibility of the components becomes crucial. For this reason, surface tension and contact angle measurements were utilized for characterizing the surface energy of the PANI particles and the polyester acrylate (PEA) resin, and also for calculating the interfacial energy between these two components that revealed good compatibility within the PANI/PEA blend. A novel technique, based on centrifugal sedimentation analysis, was employed in order to determine the PANT particle size in PEA resin, and high dispersion stability of the PANI/PEA blends was suggested by evaluation of the sedimentation data.
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| 9. |
- Shovsky, Alexander, et al.
(författare)
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Cationic poly(N -isopropylacrylamide) block copolymer adsorption investigated by dual polarization interferometry and lattice mean-field theory
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:39, s. 14028-14038
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Tidskriftsartikel (refereegranskat)abstract
- A series of cationic diblock copolymers, poly(N-isopropylacrylamide) 48-block-poly((3-acrylamidopropyl)trimethylammonium chloride) X, abbreviated as PNIPAAM48-b-PAMPTMA+ X (X = 0, 6, 10, 14, and 20), has been synthesized, and their adsorption onto silicon oxynitride from aqueous solution has been investigated using dual polarization interferometry. The polymer adsorption was modeled by using a lattice mean-field theory, and a satisfactory consistency between theory and experiments was found in terms of surface excess and layer thickness. Both theory and experiments show that the adsorption is limited by steric repulsion for X < Xmax and by electrostatic interactions for X > X max. Modeling demonstrates that significant surface charge regulation occurs due to adsorption. Both the nonionic and cationic block exhibit nonelectrostatic affinity to silicon oxynitride and thus contribute to the driving force for adsorption, and modeling is used for clarifying how changes in the nonelectrostatic affinity affects the surface excess. The segments of the nonionic and cationic blocks seem less segregated when both have a nonelectrostatic affinity for the surface compared to the case where the segments had no surface affinity. Adsorption kinetics was investigated experimentally. Two kinetic regimes were observed: the adsorption rate is initially controlled by the mass transfer rate to the surface and at higher coverage is limited by the attachment rate.
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| 10. |
- Albert, Malin, et al.
(författare)
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Aetiology and outcome in hospitalized cardiac arrest patients.
- 2023
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Ingår i: European Heart Journal Open. - 2752-4191. ; 3:4
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To study aetiologies of in-hospital cardiac arrests (IHCAs) and their association with 30-day survival.METHODS AND RESULTS: Observational study with data from national registries. Specific aetiologies (n = 22) of IHCA patients between April 2018 and December 2020 were categorized into cardiac vs. non-cardiac and six main aetiology categories: myocardial ischemia, other cardiac causes, pulmonary causes, infection, haemorrhage, and other non-cardiac causes. Main endpoints were proportions in each aetiology, 30-day survival, and favourable neurological outcome (Cerebral Performance Category scale 1-2) at discharge. Among, 4320 included IHCA patients (median age 74 years, 63.1% were men), approximate 50% had cardiac causes with a 30-day survival of 48.4% compared to 18.7% among non-cardiac causes (P < 0.001). The proportion in each category were: myocardial ischemia 29.9%, pulmonary 21.4%, other cardiac causes 19.6%, other non-cardiac causes 11.6%, infection 9%, and haemorrhage 8.5%. The odds ratio (OR) for 30-day survival compared to myocardial ischemia for each category were: other cardiac causes OR 1.48 (CI 1.24-1.76); pulmonary causes OR 0.36 (CI 0.3-0.44); infection OR 0.25 (CI 0.18-0.33); haemorrhage OR 0.22 (CI 0.16-0.3); and other non-cardiac causes OR 0.56 (CI 0.45-0.69). IHCA caused by myocardial ischemia had the best favourable neurological outcome while those caused by infection had the lowest OR 0.06 (CI 0.03-0.13).CONCLUSION: In this nationwide observational study, aetiologies with cardiac and non-cardiac causes of IHCA were evenly distributed. IHCA caused by myocardial ischemia and other cardiac causes had the strongest associations with 30-day survival and neurological outcome.
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| 11. |
- An, Junxue, et al.
(författare)
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Influence of Glycosylation on Interfacial Properties of Recombinant Mucins : Adsorption, Surface Forces, and Friction
- 2017
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Ingår i: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 33:18, s. 4386-4395
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Tidskriftsartikel (refereegranskat)abstract
- Interfacial properties of two brush-with-anchor mucins, C-P55 and C-PSLex, have been investigated at the aqueous solution/poly(methyl methacrylate) (PMMA) interface. Both are recombinant mucin-type fusion proteins, produced by fusing the glycosylated mucin part of P-selectin glycoprotein ligand-1 (PSLG-1) to the Fc part of a mouse immunoglobulin in two different cells. They are mainly expressed as dimers upon production. Analysis of the O-glycans shows that the C-PSLex mucin has the longer and more branched side chains, but C-P55 has slightly higher sialic acid content. The adsorption of the mucins to PMMA surfaces was studied by quartz crystal microbalance with dissipation. The sensed mass, including the adsorbed mucin and water trapped in the layer, was found to be similar for these two mucin layers. Atomic force microscopy with colloidal probe was employed to study surface and friction forces between mucin-coated PMMA surfaces. Purely repulsive forces of steric origin were observed between mucin layers on compression, whereas a small adhesion was detected between both mucin layers on decompression. This was attributed to chain entanglement. The friction force between C-PSLex-coated PMMA is lower than that between C-P55-coated PMMA at low loads, but vice versa at high loads. We discuss our results in terms of the differences in the glycosylation composition of these two mucins.
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| 12. |
- An, Junxue
(författare)
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Polymers in Aqueous Lubrication
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this thesis work was to gain understanding of the layer properties and polymer structures that were able to aid lubrication in aqueous media. To this end, three types of polyelectrolytes: a diblock copolymer, a train-of-brushes and two brush-with-anchor mucins have been utilized. Their lubrication ability in the boundary lubrication regime has been examined by Atomic Force Microscopy with colloidal probe. The interfacial behavior of the thermoresponsive diblock copolymer, PIPOZ60-b-PAMPTAM17,on silica was studied in the temperature interval 25-50 ˚C. The main finding is that adsorption hysteresis, due to the presence of trapped states, is important when the adsorbed layers are in contact with a dilute polymer solution. The importance of trapped states was also demonstrated in the measured friction forces, where significantly lower friction forces, at a given temperature, were encountered on cooling than on the preceding heating stage, which was attributed to increased adsorbed amount. On the heating stage the friction force decreased with increasing temperature despite the worsening of the solvent condition, and the opposite trend was observed when using pre-adsorbed layers (constant adsorbed amount) as a consequence of increased segment-segment attraction.The second part of the studies was devoted to the interfacial properties of mucins on PMMA. The strong affinity provided by the anchoring group of C-PSLex and C-P55 together with their more extended layer structure contribute to the superior lubrication of PMMA compared to BSM up to pressures of 8-9 MPa. This is a result of minor bridging and lateral motion of molecules along the surface during shearing. We further studied the influence of glycosylation on interfacial properties of mucin by utilizing the highly purified mucins, C-P55 and C-PSLex. Our data suggest that the longer and more branched carbohydrate side chains on C-PSLex provide lower interpenetration and better hydration lubrication at low loads compared to the shorter carbohydrate chains on C-P55. However, the longer carbohydrates appear to counteract disentanglement less efficiently, giving rise to a higher friction force at high loads.
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| 13. |
- Bartenstein, J. E., et al.
(författare)
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Polymersomes at the solid-liquid interface : Dynamic morphological transformation and lubrication
- 2018
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Ingår i: Journal of Colloid and Interface Science. - : Academic Press. - 0021-9797 .- 1095-7103. ; 512, s. 260-271
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Tidskriftsartikel (refereegranskat)abstract
- Polymersomes are hollow spheres self-assembled from amphiphilic block copolymers of certain molecular architecture. Whilst they have been widely studied for biomedical applications, relatively few studies have reported their interfacial properties. In particular, lubrication by polymersomes has not been previously reported. Here, interfacial properties of polymersomes self-assembled from poly(butadiene)-poly(ethylene oxide) (PBD-PEO; molecular weight 10,400 g mol−1) have been studied at both hydrophilic and hydrophobic surfaces. Their morphology at silica and mica surfaces was imaged with quantitative nanomechanical property mapping atomic force microscopy (QNM AFM), and friction and surface forces they mediate under confinement between two surfaces were studied using colloidal probe AFM (CP-AFM). We find that the polymersomes remained intact but adopted flattened conformation once adsorbed to mica, with a relatively low coverage. However, on silica these polymersomes were unstable, rupturing to form donut shaped residues or patchy bilayers. On a silica surface hydrophobized with a 19 nm polystyrene (PS) film, the polymer vesicles formed a more stable layer with a higher surface coverage as compared to the hydrophilic surface, and the interfacial structure also evolved over time. Moreover, friction was greatly reduced on hydrophobized silica surfaces in the presence of polymersomes, suggesting their potential as effective aqueous lubricants.
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| 14. |
- Bastardo Zambrano, Luis Alejandro, et al.
(författare)
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Deuterium isotope effects on the interaction between hyperbranched polyethylene imine and an anionic surfactant
- 2005
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 109:33, s. 16196-16202
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Tidskriftsartikel (refereegranskat)abstract
- Solvent isotope effects on the interaction between the hyperbranched cationic polyelectrolyte, polyethylene imine (PEI), and the anionic surfactant sodium dodecyl sulfate (SDS) were investigated using potentiometric titration and eletrophoretic mobility measurements. In the basic pH range, a significantly higher fraction of the amine groups was found to be protonated when the PEI was dissolved in D2O compared to H2O at the same pH/pD. The difference in polymer charge in the two solvents decreases gradually with decreasing pH, and it completely diminishes at around pH = 4. Electrophoretic mobility measurements of PEI/SDS complexes at different pH values correlated very well with these observations. At pH/pD approximate to 9 a much higher mobility of the PEI/SDS complexes was found in D2O than in H2O at low surfactant concentrations, and the charge neutralization point shifted to a considerably larger surfactant concentration in heavy water. These results can be explained by the significantly higher charge density of the PEI in D2O compared to H2O. However, at the natural pH/pD as well as at pH = 4 and pD = 4 conditions the PEI molecules have roughly equal charge densities, which result in very similar charged characteristics (mobilities) of the PEI/SDS complexes as well as the same charge neutralization SDS concentration. It can be concluded that extreme care must be taken in the general analysis of those experiments in which weak polyelectrolyte/surfactant aggregates are investigated in heavy water, and then these observations are correlated with structures of the same system in water.
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| 15. |
- Bastardo Zambrano, Luis Alejandro, et al.
(författare)
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Interactions between mucin and alkyl sodium sulfates in solution : a light scattering study
- 2002
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 18:10, s. 3848-3853
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Tidskriftsartikel (refereegranskat)abstract
- The properties of negatively charged mucin in aqueous solutions and its interaction with anionic sodium alkyl sulfates with different hydrocarbon chain lengths were studied by means of dynamic light scattering. It was observed that mucin forms aggregates in aqueous solutions with a hydrodynamic radius above 500 nm. These aggregates dissolve when sodium dodecyl sulfate or sodium decyl sulfate is present at sufficiently high concentration, above about 0.2 cmc (critical micellar concentration). On the other hand, sodium octyl sulfate is not very effective in dissolving the mucin aggregates. The hydrodynamic radius of the dissolved mucin, decorated with some associated surfactant, is found to be in the range of 40-90 nm. The observation that the dissolving power of the sodium alkyl sulfates decreases with decreasing surfactant chain length suggests that the association between the surfactant and mucin is hydrophobically driven. The kinetics of the dissolution process depends on the surfactant concentration, a higher surfactant concentration giving rise to a more rapid dissolution of the aggregates. It was also observed that when the ionic strength is increased, the surfactant concentration needed to dissolve the mucin aggregates decreases. This can be explained by reduction of repulsive electrostatic forces by the salt.
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| 16. |
- Berglund, Ellinor, et al.
(författare)
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Effect of Smartphone Dispatch of Volunteer Responders on Automated External Defibrillators and Out-of-Hospital Cardiac Arrests : The SAMBA Randomized Clinical Trial
- 2023
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Ingår i: JAMA cardiology. - : American Medical Association (AMA). - 2380-6583 .- 2380-6591. ; 8:1, s. 81-88
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Tidskriftsartikel (refereegranskat)abstract
- Importance Smartphone dispatch of volunteer responders to nearby out-of-hospital cardiac arrests (OHCAs) has emerged in several emergency medical services, but no randomized clinical trials have evaluated the effect on bystander use of automated external defibrillators (AEDs).Objective To evaluate if bystander AED use could be increased by smartphone-aided dispatch of lay volunteer responders with instructions to collect nearby AEDs compared with instructions to go directly to patients with OHCAs to start cardiopulmonary resuscitation (CPR).Design, Setting, and Participants This randomized clinical trial assessed a system for smartphone dispatch of volunteer responders to individuals experiencing OHCAs that was triggered at emergency dispatch centers in response to suspected OHCAs and randomized 1:1. The study was conducted in 2 main Swedish regions: Stockholm and Västra Götaland between December 2018 and January 2020. At study start, there were 3123 AEDs in Stockholm and 3195 in Västra Götaland and 24 493 volunteer responders in Stockholm and 19 117 in Västra Götaland. All OHCAs in which the volunteer responder system was activated by dispatchers were included. Excluded were patients with no OHCAs, those with OHCAs not treated by the emergency medical services, and those with OHCAs witnessed by the emergency medical services.Interventions Volunteer responders were alerted through the volunteer responder system smartphone application and received map-aided instructions to retrieve nearest available public AEDs on their way to the OHCAs. The control arm included volunteer responders who were instructed to go directly to the OHCAs to perform CPR.Main Outcomes and Measures Overall bystander AED attachment, including those attached by volunteer responders and lay volunteers who did not use the smartphone application.Results Volunteer responders were activated for 947 patients with OHCAs. Of those, 461 were randomized to the intervention group (median [IQR] age of patients, 73 [61-81] years; 295 male patients [65.3%]) and 486 were randomized to the control group (median [IQR] age of patients, 73 [63-82] years; 312 male patients [65.3%]). Primary outcome of AED attachment occurred in 61 patients (13.2%) in the intervention arm vs 46 patients (9.5%) in the control arm (difference, 3.8% [95% CI, −0.3% to 7.9%]; P = .08). The majority of AEDs were attached by lay volunteers who were not using the smartphone application (37 in intervention arm, 28 in control). There were no significant differences in secondary outcomes. Among the volunteer responders using the application, crossover was 11% and compliance to instructions was 31%. Volunteer responders attached 38% (41 of 107) of all AEDs and provided 45% (16 of 36) of all defibrillations and 43% (293 of 666) of all CPR.Conclusions and Relevance In this study, smartphone dispatch of volunteer responders to OHCAs to retrieve nearby AEDs vs instructions to directly perform CPR did not significantly increase volunteer AED use. High baseline AED attachement rate and crossover may explain why the difference was not significant.Trial Registration ClinicalTrials.gov Identifier: NCT02992873
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| 17. |
- Berglund, Ellinor, et al.
(författare)
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Wellbeing, emotional response and stress among lay responders dispatched to suspected out-of-hospital cardiac arrests
- 2022
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Ingår i: Resuscitation. - : Elsevier Ireland Ltd. - 0300-9572 .- 1873-1570. ; 170, s. 352-360
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Tidskriftsartikel (refereegranskat)abstract
- Background: Systems for smartphone dispatch of lay responders to perform cardio-pulmonary resuscitation (CPR) and bring automated external defibrillators to out-of-hospital cardiac arrests (OHCAs) are advocated by recent international guidelines and emerging worldwide. Objectives: This study aimed to investigate the emotional responses, posttraumatic stress reactions and levels of wellbeing among smartphone-alerted lay responders dispatched to suspected OHCAs. Methods: Lay responders were stratified by level of exposure: unexposed (Exp-0), tried to reach (Exp-1), and reached the suspected OHCA (Exp-2). Participants rated their emotional responses online, at 90 minutes and at 4–6 weeks after an incident. Level of emotional response was measured in two dimensions of core affect: “alertness” – from deactivation to activation, and “pleasantness” – from unpleasant to pleasant. At 4–6 weeks, WHO wellbeing index and level of posttraumatic stress (PTSD) were also rated. Results: Altogether, 915 (28%) unexposed and 1471 (64%) exposed responders completed the survey. Alertness was elevated in the exposed groups: Exp-0: 6.7 vs. Exp-1: 7.3 and Exp-2: 7.5, (p < 0.001) and pleasantness was highest in the unexposed group: 6.5, vs. Exp-1: 6.3, and Exp-2: 6.1, (p < 0.001). Mean scores for PTSD at follow-up was below clinical cut-off, Exp-0: 9.9, Exp-1: 8.9 and Exp-2: 8.8 (p = 0.065). Wellbeing index showed no differences, Exp-0: 78.0, Exp-1: 78.5 and Exp-2: 79.9 (p = 0.596). Conclusion: Smartphone dispatched lay responders rated the experience as high-energy and mainly positive. No harm to the lay responders was seen. The exposed groups had low posttraumatic stress scores and high-level general wellbeing at follow-up. © 2021
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| 18. |
- Blomberg, Eva, et al.
(författare)
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Globotriose- and oligo(ethylene glycol)-terminated self-assembled monolayers : Surface forces, wetting, and surfactant adsorption
- 2006
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:24, s. 10038-10046
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Tidskriftsartikel (refereegranskat)abstract
- A set of oligo( ethylene glycol)-terminated and globotriose-terminated self-assembled monolayers (SAMs) has been prepared on gold substrates. Such model surfaces are well defined and have good stability due to the strong binding of thiols and disulfides to the gold substrate. They are thus very suitable for addressing questions related to effects of surface composition on wetting properties, surface interactions, and surfactant adsorption. These issues are addressed in this report. Accurate wetting tension measurements have been performed as a function of temperature using the Wilhelmy plate technique. The results show that the nonpolar character of oligo( ethylene glycol)-terminated SAMs increases slightly but significantly with temperature in the range 20-55 degrees C. On the other hand, globotriose-terminated SAMs are fully wetted by water at room temperature. Surface forces measurements have been performed and demonstrated that the interactions between oligo( ethylene glycol)-terminated SAMs are purely repulsive and similar to those determined between adsorbed surfactant layers with the same terminal headgroup. On the other hand, the interactions between globotriose-terminated SAMs include a short-range attractive force component that is strongly affected by the packing density in the layer. In some cases it is found that the attractive force component increases with contact time. Both these observations are rationalized by an orientation- and conformation-dependent interaction between globotriose headgroups, and it is suggested that hydrogen-bond formation, directly or via bridging water molecules, is the molecular origin of these effects.
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| 19. |
- Chen, Chengdong, et al.
(författare)
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Heating-Induced Enhancement of Corrosion Protection of Carbon Steel by a Nanocomposite Film Containing Mussel Adhesive Protein
- 2017
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 164:4, s. C188-C193
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Tidskriftsartikel (refereegranskat)abstract
- Application of protective coatings on metals may involve a thermal treatment process. In this study, the effect of thermal treatment up to 200?C on the corrosion protection was investigated for nanocomposite films composed of mussel adhesive protein (MAP), CeO2 nanoparticles and Na2HPO4 deposited on carbon steel. The morphology and microstructure of the pre-formed nanocomposite film were characterized by scanning electron microscopy/energy dispersive spectroscopy and atomic force microscopy (AFM). The changes in the chemical structure of the nanocomposite film due to the thermal treatment were investigated by infrared reflection absorption spectroscopy. The corrosion protection of the unheated and heated nanocomposite films on carbon steel was evaluated by electrochemical impedance spectroscopy and details of the corrosion process were elucidated by in-situ AFM measurements in 0.1 M NaCl solution. The results show a certain increase in the corrosion protection with time of the nanocomposite film for carbon steel. The analyses reveal that thermal treatment leads to a reduction of water molecules in the nanocomposite film, and an enhanced cross-linking and cohesion of the film due to oxidation of catechols to o-quinones. As a result, the film becomes more compact and gives improved corrosion protection for carbon steel.
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| 20. |
- Claesson, Andreas, et al.
(författare)
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Simulation and education Outline and validation of a new dispatcher-assisted cardiopulmonary resuscitation educational bundle using the Delphi method
- 2024
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Ingår i: Resuscitation Plus. - : ELSEVIER. - 2666-5204. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is time-dependent. To date, evidence-based training programmes for dispatchers are lacking. This study aimed to reach expert consensus on an educational bundle content for dispatchers to provide DA-CPR using the Delphi Method: An educational bundle was created by the Swedish Resuscitation Council consisting of three parts: e-learning on DA-CPR, basic life support training and audit of emergency out-of-hospital cardiac arrest calls. Thereafter, a two-round modified Delphi study was conducted between November 2022 and March 2023; 37 experts with broad clinical and/or scientific knowledge of DA-CPR were invited. In the first round, the experts participated in the e-learning module and answered a questionnaire with 13 closed and open questions, whereafter the e-learning part of the bundle was revised. In the second round, the revised e-learning part was evaluated using Likert scores (20 items). The predefined consensus level was set Results: Delphi rounds one and two were assessed by 20 and 18 of the invited experts, respectively. In round one, 18 experts (18 of 20, 90%) stated that they did not miss any content in the programme. In round two, the scale-level content validity index based on the average method (S-CVI/AVE, 0.99) and scale-level content validity index based on universal agreement (S-CVI/UA, 0.85) exceeded the threshold level of 80%. Conclusion: Expert consensus on the educational bundle content was reached using the Delphi method. Further work is required to evaluate its effect in real-world out-of-hospital cardiac arrest calls.
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| 21. |
- Claesson, Per M, et al.
(författare)
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Surfaces coated with ethyl(hydroxyethyl) cellulose : Temperature effects on adsorption and interaction
- 1995
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Ingår i: Cellulose and Cellulose Derivatives. - : Woodhead Publishing Limited. ; , s. 425-433
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Bokkapitel (refereegranskat)abstract
- The temperature dependence of the forces acting between hydrophobic surfaces coated by a layer of ethyl(hydroxyethyl) cellulose, (EHEC), has been studied as a function of separation and temperature. Both the situation where the adsorbed amount is kept constant and where the adsorbed amount is allowed to vary with temperature have been explored. In both cases the surface interaction is very temperature sensitive due to the temperature dependent interactions between ethylene oxide groups and water. The results are discussed in terms protein repellency of EHEC coated surfaces and in terms of EHEC as a steric stabilizer.
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| 22. |
- Dobryden, Illia, et al.
(författare)
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Bioinspired Adhesion Polymers : Wear Resistance of Adsorption Layers.
- 2019
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 35:48, s. 15515-15525
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Tidskriftsartikel (refereegranskat)abstract
- Mussel adhesive polymers owe their ability to strongly bind to a large variety of surfaces under water to their high content of 3,4-dihydroxy-l-phenylalanine (DOPA) groups and high positive charge. In this work, we use a set of statistical copolymers that contain medium-length poly(ethylene oxide) side chains that are anchored to the surface in three different ways: by means of (i) electrostatic forces, (ii) catechol groups (as in DOPA), and (iii) the combination of electrostatic forces and catechol groups. A nanotribological scanning probe method was utilized to evaluate the wear resistance of the formed layers as a function of normal load. It was found that the combined measurement of surface topography and stiffness provided an accurate assessment of the wear resistance of such thin layers. In particular, surface stiffness maps allowed us to identify the initiation of wear before a clear topographical wear scar was developed. Our data demonstrate that the molecular and abrasive wear resistance on silica surfaces depends on the anchoring mode and follows the order catechol groups combined with electrostatic forces > catechol groups alone > electrostatic forces alone. The devised methodology should be generally applicable for evaluating wear resistance or "robustness" of thin adsorbed layers on a variety of surfaces.
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| 23. |
- Ejenstam, Lina, et al.
(författare)
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The effect of superhydrophobic wetting state on corrosion protection : The AKD example
- 2013
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 412, s. 56-64
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion is of considerable concern whenever metal is used as construction material. In this study we address whether superhydrophobic coatings could be used as part of an environmentally friendly corrosion-protective system, and specific focus is put on how the wetting regime of a superhydrophobic coating affects corrosion inhibition. Superhydrophobic alkyl ketene dimer (AKD) wax coatings were produced, using different methods resulting in hierarchical structures, where the coatings exhibit the same surface chemistry but different wetting regimes. Contact angle measurements, ESEM, confocal Raman microscopy, open circuit potential and electrochemical impedance spectroscopy were used to evaluate the surfaces. Remarkably high impedance values of 1010Ωcm2 (at 10-2Hz) were reached for the sample showing superhydrophobic lotus-like wetting. Simultaneous open circuit potential measurements suggest that the circuit is broken, most likely due to the formation of a thin air layer at the coating-water interface that inhibits ion transport from the electrolyte to the metal substrate. The remaining samples, showing superhydrophobic wetting in the rose state and hydrophobic Wenzel-like wetting, showed less promising corrosion-protective properties. Due to the absence of air films on these surfaces the coatings were penetrated by the electrolyte, which allowed the corrosion reaction to proceed.
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| 24. |
- Elfwén, Ludvig, et al.
(författare)
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Coronary angiography in out-of-hospital cardiac arrest without ST elevation on ECG-Short- and long-term survival.
- 2018
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Ingår i: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 200, s. 90-95
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The potential benefit of early coronary angiography in out-of-hospital cardiac arrest (OHCA) patients without ST elevation on ECG is unclear. The aim of this study was to evaluate the association between early coronary angiography and survival in these patients.METHODS: Nationwide observational study between 2008 and 2013. Included were patients admitted to hospital after witnessed OHCA, with shockable rhythm, age 18 to 80 years and unconscious. Patients with ST-elevation on ECG were excluded. Patients that underwent early CAG (within 24 hours) were compared with no early CAG (later during the hospital stay or not at all). Outcomes were survival at 30 days, 1 year, and 3 years. Multivariate analysis included pre-hospital factors, comorbidity and ECG-findings.RESULTS: In total, 799 OHCA patients fulfilled the inclusion criteria, of which 275 (34%) received early CAG versus 524 (66%) with no early CAG. In the early CAG group, the proportion of patients with an occluded coronary artery was 27% and 70% had at least one significant coronary stenosis (defined as narrowing of coronary lumen diameter of ≥50%). The 30-day survival rate was 65% in early CAG group versus 52% with no early CAG (P < .001). The adjusted OR was 1.42 (95% CI 1.00-2.02). The one-year survival rate was 62% in the early CAG group versus 48% in the no early CAG group with the adjusted hazard ratio of 1.35 (95% CI 1.04-1.77).CONCLUSION: In this population of bystander-witnessed cases of out-of-hospital cardiac arrest with shockable rhythm and ECG without ST elevation, early coronary angiography may be associated with improved short and long term survival.
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| 25. |
- Fan, Ke, et al.
(författare)
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Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation
- 2016
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm(-2) (57 mA cm(-2) after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.
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| 26. |
- Forslund, Mattias, et al.
(författare)
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Micro-galvanic corrosion effects on patterned copper-zinc samples during exposure in humidified air containing formic acid
- 2013
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 160:9, s. C423-C431
-
Tidskriftsartikel (refereegranskat)abstract
- Corrosion in indoor atmospheric environments is often triggered by carboxylic acids, especially at higher relative humidity. Microgalvanic effects can lead to severe corrosion, particularly important in miniature devices with small-sized metallic components. To elucidate the mechanism of micro-galvanic corrosion effects, well-defined zinc-copper patterned samples were investigated during exposure to 100 ppb formic acid (HCOOH) and 80% relative humidity at 20°C. The corrosion effects were monitored quantitatively with in situ infrared absorption spectroscopy, and the corrosion products characterized with scanning electron microscopy, confocal Raman microscopy, and atomic force microscopy. The nature of corrosion on zinc on the patterned samples was compared with that on pure zinc and turned out to result, not only in several times higher corrosion kinetics, but also in different corrosion products with respect to distribution, morphology, and composition. Local electrochemical and chemical gradients across the copper-zinc borders resulted in characteristic hemispherically shaped corrosion products at the zinc-copper junction, and in the formation of zinc formate dihydrate (Zn(HCOO)2 · 2H 2O) and crystalline zinc oxide (ZnO), phases not identified on pure zinc. In all, the micro-galvanic effects on the patterned samples resulted in accelerated corrosion kinetics and in structurally more developed corrosion products.
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| 27. |
- Fredman, David, et al.
(författare)
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Objective classification and comparison of OHCA and AED locations using geographic information systems
- 2015
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Ingår i: Resuscitation. - : Elsevier BV. - 0300-9572 .- 1873-1570. ; 96, s. 21-21
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Tidskriftsartikel (refereegranskat)abstract
- The Utstein registry template stress recording of out-of-hospital cardiac arrest (OHCA) location and suggest eight data options with additional subcategories. The subjectivity in categorization of OHCA locations by emergency medical services (EMS) makes objective regional and international comparisons hard.
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| 28. |
- Fredman, David, et al.
(författare)
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Use of a geographic information system to identify differences in automated external defibrillator installation in urban areas with similar incidence of public out-of-hospital cardiac arrest : A retrospective registry-based study
- 2017
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Ingår i: BMJ Open. - : BMJ Publishing Group Ltd. - 2044-6055. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Objectives Early defibrillation in out-of-hospital cardiac arrest (OHCA) is of importance to improve survival. In many countries the number of automated external defibrillators (AEDs) is increasing, but the use is low. Guidelines suggest that AEDs should be installed in densely populated areas and in locations with many visitors. Attempts have been made to identify optimal AED locations based on the incidence of OHCA using geographical information systems (GIS), but often on small datasets and the studies are seldom reproduced. The aim of this paper is to investigate if the distribution of public AEDs follows the incident locations of public OHCAs in urban areas of Stockholm County, Sweden. Method OHCA data were obtained from the Swedish Register for Cardiopulmonary Resuscitation and AED data were obtained from the Swedish AED Register. Urban areas in Stockholm County were objectively classified according to the pan-European digital mapping tool, Urban Atlas (UA). Furthermore, we reclassified and divided the UA land cover data into three classes (residential, non-residential and other areas). GIS software was used to spatially join and relate public AED and OHCA data and perform computations on relations and distance. Results Between 1 January 2012 and 31 December 2014 a total of 804 OHCAs occurred in public locations in Stockholm County and by December 2013 there were 1828 AEDs available. The incidence of public OHCAs was similar in residential (47.3%) and non-residential areas (43.4%). Fewer AEDs were present in residential areas than in non-residential areas (29.4% vs 68.8%). In residential areas the median distance between OHCAs and AEDs was significantly greater than in non-residential areas (288 m vs 188 m, p<0.001). Conclusion The majority of public OHCAs occurred in areas classified in UA as 'residential areas' with limited AED accessibility. These areas need to be targeted for AED installation and international guidelines need to take geographical location into account when suggesting locations for AED installation.
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| 29. |
- Frise, Anton, et al.
(författare)
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Adsorption isotherms of cationic surfactants on silica particles measured by NMR spectroscopy
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present here a new method that employs NMR spectroscopy to quantify the adsorbed amount of surfactant on the surface of particles and thereby provide the adsorption isotherm. As demonstration, the adsorption isotherms for a series of cationic surfactants on silica particles are obtained. Those results are in general agreement with previous observations and the overall appearances of adsorption isotherms exemplify the interplay between electrostatic and hydrophobic interactions. Compared to other available methods, the experimental error is comparable or smaller in a very wide range of surfactant concentrations and there exist other potential advantages.
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| 30. |
- Hansson, P. M., et al.
(författare)
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Effect of local curvature on the interaction between hydrophobic surfaces
- 2010
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Ingår i: Nanotechnology 2010: Advanced Materials, CNTs, Particles, Films and Composites - Technical Proceedings of the 2010 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2010. - 9781439834015 ; , s. 61-64
-
Konferensbidrag (refereegranskat)abstract
- Surface structure, including roughness and chemical heterogeneities, is known to be of importance for the surface interaction forces observed between hydrophobic and superhydrophobic surfaces. In this study, silica particles have been used to prepare structured particulated surfaces with a controlled roughness using Langmuir-Blodgett deposition or a drop coating technique. The surfaces were characterized by SEM and AFM. The AFM colloidal probe technique was employed for probing the interaction between a micro-size hydrophobic particle and hydrophobic surfaces with a sintered and silanized nano-sized silica particle monolayer. These measurements indicate that the adhesion force is increased by a decrease in particle size. Larger roughness gives larger crevices on the surface and more air/vapor accumulation but the capillary growth is impaired since the three-phase line (solid-liquid-air) has to move over a longer distance with an increase in the size of the surface features.
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| 31. |
- Hansson, Petra M., et al.
(författare)
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Effect of surface depressions on wetting and interactions between hydrophobic pore array surfaces
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:30, s. 11121-11130
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Tidskriftsartikel (refereegranskat)abstract
- The surface structure is known to significantly affect the long-range capillary forces between hydrophobic surfaces in aqueous solutions. It is, however, not clear how small depressions in the surface will affect the interaction. To clarify this, we have used the AFM colloidal probe technique to measure interactions between hydrophobic microstructured pore array surfaces and a hydrophobic colloidal probe. The pore array surfaces were designed to display two different pore spacings, 1.4 and 4.0 ÎŒm, each with four different pore depths ranging from 0.2 to 12.0 ÎŒm. Water contact angles measured on the pore array surfaces are lower than expected from the Cassie-Baxter and Wenzel models and not affected by the pore depth. This suggests that the position of the three-phase contact line, and not the interactions underneath the droplet, determines the contact angle. Confocal Raman microscopy was used to investigate whether water penetrates into the pores. This is of importance for capillary forces where both the movement of the three-phase contact line and the situation at the solid/liquid interface influence the stability of bridging cavities. By analyzing the shape of the force curves, we distinguish whether the cavity between the probe and the surfaces was formed on a flat part of the surface or in close proximity to a pore. The pore depth and pore spacing were both found to statistically influence the distance at which cavities form as surfaces approach each other and the distance at which cavities rupture during retraction.
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| 32. |
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| 33. |
- Hansson, Petra M., 1983-, et al.
(författare)
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Hydrophobic pore array surfaces : Wetting and interaction forces in water/ethanol mixtures
- 2013
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 396, s. 278-286
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between and wetting behavior of structured hydrophobic surfaces using different concentrations of water/ethanol mixtures have been investigated. Silica surfaces consisting of pore arrays with different pore spacings and pore depths were made hydrophobic by silanization. Their static and dynamic contact angles were found to be independent of the pore depth while fewer pores on the surface, i.e. a closer resemblance to a flat surface, gave a lower contact angle. As expected, a higher amount of ethanol facilitated wetting on all the surfaces tested. Confocal Raman microscopy measurements proved both water and ethanol to penetrate into the pores. AFM colloidal probe force measurements clearly showed that formation of air cavitation was hindered between the hydrophobic surfaces in presence of ethanol, and an increase in ethanol concentration was followed by a smaller jump-in distance and a weaker adhesion force. On separation, an immediate jump-out of contact occurred. The measured forces were interpreted as being due to capillary condensation of ethanol between the surfaces giving rise to very unstable cavities immediately rupturing on surface separation.
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| 34. |
- Hansson, Petra M., et al.
(författare)
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Robust Hydrophobic Surfaces Displaying Different Surface Roughness Scales While Maintaining the Same Wettability
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:13, s. 8153-8159
-
Tidskriftsartikel (refereegranskat)abstract
- A range of surfaces coated with spherical silica particles, covering the size range from nanometer to micrometer, have been produced using Langmuir-Blodgett (LB) deposition. The particles were characterized both in suspension and in the Langmuir trough to optimize the surface preparation procedure. By limiting the particle aggregation and surface layer failures during the preparation steps, well-defined monolayers with a close-packed structure have been obtained for all particle sizes. Thus, this procedure led to structured surfaces with a characteristic variation in the amplitude and spatial roughness parameters. In order to obtain robust surfaces, a sintering protocol and an AFM-based wear test to determine the stability of the deposited surface layer were employed. Hydrophobization of the LB films followed by water contact angle measurements showed, for all tested particle sizes, the same increase in contact angle compared to the contact angle of a flat hydrophobic surface. This indicates nearly hexagonal packing and gives evidence for nearly, complete surface wetting of the surface features.
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| 35. |
- Hasselqvist-Ax, Ingela, et al.
(författare)
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Dispatch of Firefighters and Police Officers in Out-of-Hospital Cardiac Arrest : A Nationwide Prospective Cohort Trial Using Propensity Score Analysis.
- 2017
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Ingår i: Journal of the American Heart Association. - 2047-9980. ; 6:10
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Dispatch of basic life support-trained first responders equipped with automated external defibrillators in addition to advanced life support-trained emergency medical services personnel in out-of-hospital cardiac arrest (OHCA) has, in some minor cohort studies, been associated with improved survival. The aim of this study was to evaluate the association between basic life support plus advanced life support response and survival in OHCA at a national level.METHODS AND RESULTS: This prospective cohort study was conducted from January 1, 2012, to December 31, 2014. People who experienced OHCA in 9 Swedish counties covered by basic life support plus advanced life support response were compared with a propensity-matched contemporary control group of people who experienced OHCA in 12 counties where only emergency medical services was dispatched, providing advanced life support. Primary outcome was survival to 30 days. The analytic sample consisted of 2786 pairs (n=5572) derived from the total cohort of 7308 complete cases. The median time from emergency call to arrival of emergency medical services or first responder was 9 minutes in the intervention group versus 10 minutes in the controls (P<0.001). The proportion of patients admitted alive to the hospital after resuscitation was 31.4% (875/2786) in the intervention group versus 24.9% (694/2786) in the controls (conditional odds ratio, 1.40; 95% confidence interval, 1.24-1.57). Thirty-day survival was 9.5% (266/2786) in the intervention group versus 7.7% (214/2786) in the controls (conditional odds ratio, 1.27; 95% confidence interval, 1.05-1.54).CONCLUSIONS: In this nationwide interventional trial, using propensity score matching, dispatch of first responders in addition to emergency medical services in OHCA was associated with a moderate, but significant, increase in 30-day survival.CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02184468.
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| 36. |
- He, Yunjuan, et al.
(författare)
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Nano-scale mechanical and wear properties of a corrosion protective coating reinforced by cellulose nanocrystals : initiation of coating
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Organic coatings are commonly used for protection of substrate surfaces like metals and wood. In most cases they fulfil their purpose by acting as a barrier against unwanted substances such as oxygen, water or corrosive ions. However, with time coatings fail due to degradation caused by chemical reactions or wear by wind, water, impact of solid particles or sliding motions against other solid objects. In this work we focus on a nanocomposite coating having a hydroxyacrylate-melamine matrix and being reinforced by a small amount (0.5 wt.%) of cellulose nanocrystals. This nanocomposite is of interest as it has shown favourable corrosion protection properties on carbon steel. Here we investigate the nanomechanical and nanowear properties of the coating in air and in water, and we also explore how these properties are affected by exposure to a corrosive 0.1 M NaCl solution. Our data show that the nanomechanical properties of the coating surface is strongly affected by the environment (air or water), and that exposure to the corrosive solution affects the coating surface well before any deterioration of the corrosion protective properties are found. We suggest that our experimental methodology constitutes a powerful way to investigate and understand the initiation of coating degradation.
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| 37. |
- Heydari, Golrokh, et al.
(författare)
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Hydrophobic Surfaces : Topography Effects on Wetting by Supercooled Water and Freezing Delay
- 2013
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:42, s. 21752-21762
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Tidskriftsartikel (refereegranskat)abstract
- Hydrophobicity, and in particular superhydrophobicity, has been extensively considered to promote ice-phobicity. Dynamic contact angle measurements above 0 degrees C have been widely used to evaluate the water repellency. However, it is the wetting properties of supercooled water at subzero temperatures and the derived work of adhesion that are important for applications dealing with icing. In this work we address this issue by determining the temperature-dependent dynamic contact angle of microliter-sized water droplets on a smooth hydrophobic and a superhydrophobic surface with similar surface chemistry. The data highlight how the work of adhesion of water in the temperature interval from about 25 degrees C to below -10 degrees C is affected by surface topography. A marked decrease in contact angle on the superhydrophobic surface is observed with decreasing temperature, and we attribute this to condensation below the dew point. In contrast, no significant wetting transition is observed on the smooth hydrophobic surface. The freezing temperature and the freezing delay time were determined for water droplets resting on a range of surfaces with similar chemistry but different topography, including smooth and rough surfaces in either the Wenzel or the Cassie-Baxter state as characterized by water contact angle measurements at room temperature. We find that the water freezing delay time is not significantly affected by the surface topography and discuss this finding within the classical theory of heterogeneous nucleation.
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| 38. |
- Heydari, Golrokh, et al.
(författare)
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Wetting hysteresis induced by temperature changes : supercooled water onhydrophobic surfaces
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The state and stability of supercooled water on (super)hydrophobic surfaces is crucial for low temperature applications and for obtaining anti-icing and de-icing properties. Surface characteristics such as topography and chemistry are expected to affect wetting hysteresis during temperature cycling experiments, and also the freezing delay of supercooled water. We utilized stochastically rough wood surfaces that were further modified to render them hydrophobic or superhydrophobic. Liquid flame spraying (LFS) was utilized to create a multi-scale roughness by depositing titaniumdioxide nanoparticles. The coating was subsequently made non-polar by applying a thin plasma polymer layer. As flat reference samples modified silica surfaces with similar chemistries were utilized. With these sets of surfaces we test the hypothesis that superhydrophobic surfaces also should retard ice formation. Wetting hysteresis was evaluated using contact angle measurements during a freeze-thaw cycle from room temperature to freezing occurrence at -7 °C, and then back to room temperature. Further, the delay in freezing of supercooled water droplets was studied at temperatures of -4 °C and -7 °C. The hysteresis in contact angle observed during a cooling-heating cycle is found to be small on flat hydrophobic surfaces. However, significant changes in contact angles during a cooling-heating cycle are observed on the rough surfaces, with a higher contact angle observed on cooling compared to during the subsequent heating. This hysteresis is lower for hydrophobic wood samples with multi-scale roughness compared to those with predominantly micro-scale features. Condensation and subsequent frost formation at sub-zero temperatures induce the hysteresis. The freezing delay data suggests that the multi-scale roughness reduces the penetration of supercooled water into surface depressions, and enhances the freezing delay at low degrees of supercooling. However, the flat surface is even more efficient in enhancing the freezing delay than the rougher surfaces, which can be rationalized considering heterogeneous nucleation theory. Thus, our data suggests that molecular flat surfaces, rather than rough superhydrophobic surfaces, are beneficial for retarding ice formation under conditions that allow condensation and frost formation to occur.
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| 39. |
- Jafarzadeh, Shadi, et al.
(författare)
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Direct measurement of colloidal interactions between polyaniline surfaces in a uv-curable coating formulation : The effect of surface hydrophilicity/ hydrophobicity and resin composition
- 2014
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 30:4, s. 1045-1054
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Tidskriftsartikel (refereegranskat)abstract
- The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different characteristics (hydrophilic and hydrophobic) were synthesized directly on spherical polystyrene particles of 10 μm in diameter. Surface forces were measured between core/shell structured polystyrene/polyaniline particles (and a pure polystyrene particle as reference) mounted on an atomic force microscope cantilever and a pressed pellet of either hydrophilic or hydrophobic polyaniline powders, in resins of various polymer:monomer ratios. A short-range purely repulsive interaction was observed between hydrophilic polyaniline (doped with phosphoric acid) surfaces in polyester acrylate resin. In contrast, interactions between hydrophobic polyaniline (doped with n-decyl phosphonic acid) were dominated by attractive forces, suggesting less compatibility and higher tendency for aggregation of these particles in liquid polyester acrylate compared to hydrophilic polyaniline. Both observations are in agreement with the conclusions from the interfacial energy studies performed by contact angle measurements.
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| 40. |
- Jafarzadeh, Shadi
(författare)
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Functional composite coatings containing conducting polymers
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic coatings are widely used to lower the corrosion rate of metallic structures. However, penetration of water, oxygen and corrosive ions through pores present in the coating results in corrosion initiation and propagation once these species reach the metal substrate. Considering the need for systems that offer active protection with self-healing functionality, composite coatings containing polyaniline (PANI) conducting polymer are proposed in this study. In the first phase of my work, PANI was synthesized by various methods and characterized. The rapid mixing synthesis method was chosen for the rest of this study, providing PANI with high electrical conductivity, molecular structure of emeraldine salt, and morphology of spherical nanoparticles. PANIs doped with phosphoric and methane sulfonic acid revealed hydrophilic nature, and I showed that by incorporating a long-chain alkylphosphonic acid a hydrophobic PANI could be prepared. The second phase of my project was dedicated to making homogenous dispersions of PANI in a UV-curable resin based on polyester acrylate (PEA). Interfacial energy studies revealed the highest affinity of PEA to PANI doped with phosphoric acid (PANI-PA), and no attractive or long-range repulsive forces were measured between the PANI-PA surfaces in PEA.This is ideal for making conductive composites as, along withno aggregation tendency, the PANI-PA particles might come close enough to form an electrically connected network. Highly stable PEA/PANI-PA dispersions were prepared by pretreatment of PANI-PA in acetone followed by mixing in PEA in small portions under pearl-milling. The third phase of my project dealt with kinetics of the free radical polymerization that was utilized to cure the PEA/PANI-PA mixture. UV-vis absorption studies suggested a maximum allowed PANI-PA content of around 4 wt.% in order not to affect the UV curing behavior in the UV-C region. Real-time FTIR spectroscopy studies, using a laboratory UV source, revealed longer initial retardation of the photocuring and lower rates of crosslinking reactions for dispersions containing PANI-PA of higher than 3 wt.%. The presence of PANI-PA also made the formulations more sensitive to changes in UV light intensity and oxygen inhibition during UV curing. Nevertheless, curing of the dispersions with high PANI-PA content, of up to 10 wt.%, was demonstrated to be possible at either low UV light intensities provided the oxygen replenishment into the system was prevented, or by increasing the UV light intensity to very high levels. In the last phase of my project, the PEA and PEA/PANI-PA coatings, cured under high intensity UV lamps, were characterized. SEM analysis showed small PANI-PA particles to be closely packed within the matrix, and the electrical conductivity of the composite films was measured to be in the range of semiconductors. This suggested the presence of a connected network of PANI-PA, as confirmed by investigations of mechanical and electrical variations at the nanoscale by PeakForce TUNA AFM. The data revealed the presence of a PEA-rich layer at the composite-air interface, and a much higher population of the conductive network within the polymer matrix. High current signal was correlated with a high elastic modulus, consistent with the level measured for PANI-PA, and current-voltage studies on the conductive network showed non-Ohmic characteristics. Finally, the long-term protective property of the coatings was characterized by OCP and impedance measurements. Short-term barrier-type corrosion protection provided by the insulating PEA coating was turned into a long-term and active protection by addition of as little as 1 wt.% PANI-PA. A large and stable ennoblement was induced by the coatings containing PANI-PA of up to 3 wt.%. Higher content of PANI-PA led to poorer protection, probably due to the hydrophilicity of PANI-PA facilitating water transport in the coating and the presence of potentially weaker spots in the film. An iron oxide layer was found to fully cover the metal surface beneath the coatings containing PANI-PA after final failure observed by electrochemical testing.
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| 41. |
- Jafarzadeh, Shadi, et al.
(författare)
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UV-curable acrylate-based nanocomposites : Effect of polyaniline additives on the curing performance
- 2013
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Ingår i: Polymers for Advanced Technologies. - : Wiley. - 1042-7147 .- 1099-1581. ; 24:7, s. 668-678
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Tidskriftsartikel (refereegranskat)abstract
- Composites of nanostructured polyaniline (PANI) conducting polymer in a polyester acrylate (PEA) formulation were made to provide conductive organic coatings. The effect of the presence and amount of PANI on the photocuring performance of the ultraviolet (UV)-curable acrylate system has been investigated employing real-time Fourier transform infrared spectroscopy as the main technique. Longer initial retardation of the radical polymerization and lower rates of cross-linking reactions were observed for dispersions containing PANI of higher than 3wt.%. The PEA/PANI samples were more affected than the neat PEA resin by the changes in UV light intensity and oxygen accessibility during UV curing. Samples with higher PANI content, of up to 10wt.%, were tested and could be partially cured even at UV light intensities as low as 2mW cm-2 when the oxygen replenishment into the system was inhibited. Thermal analysis revealed that the presence of PANI did not induce any significant change in Tg of the cured system, meaning that early decrease in mobility and vitrification is not the reason for lower ultimate conversion of the dispersions with higher PANI content compared with the neat PEA resin. Curing under strong UV lamps, of 1.5W cm-2 intensity, made it possible to reach high degrees of conversion on films with similar mechanical properties independent of the PANI content.
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| 42. |
- Krivosheeva, Olga, et al.
(författare)
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Kinetic and Equilibrium Aspects of Adsorption and Desorption of Class II Hydrophobins HFBI and HFBII at Silicon Oxynitride/Water and Air/Water Interfaces
- 2013
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 29:8, s. 2683-2691
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Tidskriftsartikel (refereegranskat)abstract
- Hydrophobins are relatively small globular proteins produced by filamentous fungi. They display unusual high surface activity and are implied as mediators of attachment to surfaces, which has resulted in high scientific and technological interest. In this work we focus on kinetic and equilibrium aspects of adsorption and desorption properties of two representatives of class II hydrophobins, namely HFBI and HFBII, at a negatively charged hydrophilic solid/water interface and at the air/water interface. The layers formed at the air/liquid interface were examined in a Langmuir trough, whereas layers formed at the solid/liquid interface were studied using dual polarization interferometry (DPI) under different flow conditions. For comparison, another globular protein, lysozyme, was also investigated. It was found that both the adsorbed amount and the adsorption kinetics were different for HFBI and HFBII, and the adsorption behavior of both hydrophobins on the negatively charged surface displayed some unusual features. For instance, even though the adsorption rate for HFBI was slowed down with increasing adsorbed amount as expected from packing constraints at the interface, the adsorption kinetics curves for HFBII displayed a region indicating adsorption cooperativity. Further, it was found that hydrophobin layers formed under flow partly desorbed when the flow was stopped, and the desorption rate for HFBII was enhanced in the presence of hydrophobins in solution.
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| 43. |
- Krivosheeva, Olga, et al.
(författare)
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Salt- and pH-induced desorption : Comparison between non-aggregated and aggregated mussel adhesive protein, Mefp-1, and a synthetic cationic polyelectrolyte
- 2013
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 408, s. 82-86
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Tidskriftsartikel (refereegranskat)abstract
- Mussel adhesive proteins are of great interest in many applications due to their ability to bind strongly to many types of surfaces under water. Effective use such proteins, for instance the Mytilus edulis foot protein - Mefp-1, for surface modification requires achievement of a large adsorbed amount and formation of a layer that is resistant towards desorption under changing conditions. In this work we compare the adsorbed amount and layer properties obtained by using a sample containing small Mefp-1 aggregates with that obtained by using a non-aggregated sample. We find that the use of the sample containing small aggregates leads to higher adsorbed amount, larger layer thickness and similar water content compared to what can be achieved with a non-aggregated sample. The layer formed by the aggregated Mefp-1 was, after removal of the protein from bulk solution, exposed to aqueous solutions with high ionic strength (up to 1 M NaCl) and to solutions with low pH in order to reduce the electrostatic surface affinity. It was found that the preadsorbed Mefp-1 layer under all conditions explored was significantly more resistant towards desorption than a layer built by a synthetic cationic polyelectrolyte with similar charge density. These results suggest that the non-electrostatic surface affinity for Mefp-1 is larger than for the cationic polyelectrolyte.
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| 44. |
- Li, Jing, et al.
(författare)
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Towards the mechanism of electrochemical activity and self-healing of 1 wt% PTSA doped polyaniline in alkyd composite polymer coating : Combined AFM-based studies
- 2016
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 6:23, s. 19111-19127
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Tidskriftsartikel (refereegranskat)abstract
- A composite solvent-borne alkyd coating with 1 wt% p-toluene sulfonic acid (PTSA) doped polyaniline (PANI) was prepared. The mechanisms of electrochemical activity and self-healing properties of the composite coating were investigated by in situ atomic force microscopy (AFM), intermodulation AFM (ImAFM), electrochemical controlled (EC)-AFM combined with cyclic voltammetry (CV), Kelvin force microscopy (KFM), and Fourier transform infrared spectroscopy (FTIR), as well as open-circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) methods. The ImAFM demonstrates the multiphase structure of the composite coating and a high compatibility between the doped PANI and alkyd matrix. The CV and EC-AFM results reveal a high electrochemical activity of the doped PANI in the composite coating as well as reversible redox reactions between the emeraldine salt (ES) and leuco emeraldine base (LB) forms. The Volta potential mapping of KFM demonstrates a strong self-healing ability of the doped PANI in air conditions. The good electrochemical connection between the fine network of PANI in the composite coating and metal surface underneath enable the occurrence of reversible redox reaction between the ES/LB forms of doped PANI and a concomitant release of dopant anions both in air and in 3 wt% NaCl solution as demonstrated by OCP and EIS results. These therefore lead to the strong passivation and self-healing effect of the composite coated on the carbon steel surface.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Liu, Xiaoyan, et al.
(författare)
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Association of anionic surfactant and physisorbed branched brush layers probed by neutron and optical reflectometry
- 2015
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 440, s. 245-252
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Tidskriftsartikel (refereegranskat)abstract
- Pre-adsorbed branched brush layers were formed on silica surfaces by adsorption of a diblock copolymer consisting of a linear cationic block and an uncharged bottle-brush block. The charge of the silica surface was found to affect the adsorption, with lower amounts of the cationic polyelectrolytedepositing on less charged silica. Cleaning under basic conditions rendered surfaces more negatively charged (more negative zeta-potential) than acid cleaning and was therefore used to increase polyelectrolyte adsorption. The structure of adsorbed layers of the diblock copolymer was as determined by neutron reflectometry found to be about 70 nm thick and very water rich (97%). Interactions between the anionic surfactant sodium dodecylsulfate (SDS) and such pre-adsorbed diblock polymer layers were studied by neutron reflectometry and by optical reflectometry. Optical reflectometry was also used for deducing interactions between the individual blocks of the diblock copolymer and SDS at the silica/aqueous interface. We find that SDS is readily incorporated in the diblock copolymer layer at low SDS concentrations, and preferentially co-localized with the cationic block of the polymer next to the silica surface. At higher SDS concentrations some desorption of polyelectrolyte/surfactant complexes takes place.
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| 49. |
- Liu, Xiaoyan, et al.
(författare)
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Electrostatically anchored branched brush layers
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:44, s. 15537-15547
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Tidskriftsartikel (refereegranskat)abstract
- A novel type of block copolymer has been synthesized. It consists of a linear cationic block and an uncharged bottle-brush block. The nonionic bottle-brush block contains 45 units long poly(ethylene oxide) side chains. This polymer was synthesized with the intention of creating branched brush layers firmly physisorbed to negatively charged surfaces via the cationic block, mimicking the architecture (but not the chemistry) of bottle-brush molecules suggested to be present on the cartilage surface, and contributing to the efficient lubrication of synovial joints. The adsorption properties of the diblock copolymer as well as of the two blocks separately were studied on silica surfaces using quartz crystal microbalance with dissipation monitoring (QCM-D) and optical reflectometry. The adsorption kinetics data highlight that the diblock copolymers initially adsorb preferentially parallel to the surface with both the cationic block and the uncharged bottle-brush block in contact with the surface. However, as the adsorption proceeds, a structural change occurs within the layer, and the PEO bottle-brush block extends toward solution, forming a surface-anchored branched brush layer. As the adsorption plateau is reached, the diblock copolymer layer is 46-48 nm thick, and the water content in the layer is above 90 wt %. The combination of strong electrostatic anchoring and highly hydrated branched brush structures provide strong steric repulsion, low friction forces, and high load bearing capacity. The strong electrostatic anchoring also provides high stability of preadsorbed layers under different ionic strength conditions.
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| 50. |
- Liu, Xiaoyan, et al.
(författare)
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Low friction and high load bearing capacity layers formed by cationic-block-non-ionic bottle-brush copolymers in aqueous media
- 2013
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 9:22, s. 5361-5371
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Tidskriftsartikel (refereegranskat)abstract
- Efficient lubricants should be able to build surface layers that result in low friction and high load bearing capacity. In this work we show how this can be achieved in aqueous media by means of adsorption of a diblock copolymer consisting of a cationic anchor block without side chains and an uncharged and hydrophilic bottle-brush block that protrudes into solution. Surface and friction forces were measured between negatively charged silica surfaces coated with adsorbed layers of the cationic diblock copolymer, utilizing the atomic force microscope colloidal probe technique. The interactions between the surfaces coated with this copolymer in water are purely repulsive, due to a combination of steric and electrostatic double-layer forces, and no hysteresis is observed between forces measured on approach and separation. Friction forces between the diblock copolymer layers are characterized by a low friction coefficient, μ ≈ 0.03-0.04. The layers remain intact under high load and shear due to the strong electrostatic anchoring, and no destruction of the layer was noted even under the highest pressure employed (about 50 MPa). Addition of NaCl to a concentration of 155 mM weakens the anchoring of the copolymer to the substrate surface, and as a result the friction force increases.
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