| 1. |
- Björklund, Sebastian, et al.
(författare)
-
Alcohols react with MCM-41 at room temperature and chemically modify mesoporous silica
- 2017
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Mesoporous silica has received much attention due to its well-defined structural order, high surface area, and tunable pore diameter. To successfully employ mesoporous silica for nanotechnology applications it is important to consider how it is influenced by solvent molecules due to the fact that most preparation procedures involve treatment in various solvents. In the present work we contribute to this important topic with new results on how MCM-41 is affected by a simple treatment in alcohol at room temperature. The effects of alcohol treatment are characterized by TGA, FTIR, and sorption calorimetry. The results are clear and show that treatment of MCM-41 in methanol, ethanol, propanol, butanol, pentanol, or octanol at room temperature introduces alkoxy groups that are covalently bound to the silica surface. It is shown that alcohol treated MCM-41 becomes more hydrophobic and that this effect is sequentially more prominent going from methanol to octanol. Chemical formation of alkoxy groups onto MCM-41 occurs both for calcined and hydroxylated MCM-41 and the alkoxy groups are hydrolytically unstable and can be replaced by silanol groups after exposure to water. The results are highly relevant for mesoporous silica applications that involve contact or treatment in protic solvents, which is very common.
|
|
| 2. |
- Björklund, Sebastian, et al.
(författare)
-
Humidity scanning quartz crystal microbalance with dissipation monitoring setup for determination of sorption-desorption isotherms and rheological changes
- 2015
-
Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 86:5
-
Tidskriftsartikel (refereegranskat)abstract
- A new method to determine water sorption-desorption isotherms with high resolution in the complete range of water activities (relative humidities) is presented. The method is based on quartz crystal microbalance with dissipation monitoring (QCM-D). The QCM-D is equipped with a humidity module in which the sample film is kept in air with controlled humidity. The experimental setup allows for continuous scanning of the relative humidity from either dry to humid conditions or vice versa. The amount of water sorbed or desorbed from the sample is determined from the resonance frequencies of the coated quartz sensor, via analysis of the overtone dependence. In addition, the method allows for characterization of hydration induced changes of the rheological properties from the dissipation data, which is closely connected to the viscoelasticity of the film. The accuracy of the humidity scanning setup is confirmed in control experiments. Sorption-desorption isotherms of pig gastric mucin and lysozyme, obtained by the new method, show good agreement with previous results. Finally, we show that the deposition technique used to coat the quartz sensor influences the QCM-D data and how this issue can be used to obtain further information on the effect of hydration. In particular, we demonstrate that spin-coating represents an attractive alternative to obtain sorption-desorption isotherms, while drop-coating provides additional information on changes of the rheological properties during hydration.
|
|
| 3. |
- Björklund, Sebastian, et al.
(författare)
-
Hydration-Induced Phase Transitions in Surfactant and Lipid Films
- 2016
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:21, s. 5223-5232
-
Tidskriftsartikel (refereegranskat)abstract
- For several surfactant and lipid systems, it is crucial to understand how hydration influences the physical and chemical properties. When humidity changes, it affects the degree of hydration by adding or removing water molecules. In many cases, this process induces transitions between liquid crystalline phases. This phenomenon is of general interest for numerous applications simply because of the fact that humidity variations are ubiquitous. Of particular interest are hydration-induced phase transitions in amphiphilic films, which in many cases appear as the frontier toward a vapor phase with changing humidity. Considering this, it is important to characterize the film thickness needed for the formation of 3D liquid crystalline phases and the lyotropic phase behavior of this kind of film. In this work, we study this issue by employing a recently developed method based on the humidity scanning quartz crystal microbalance with dissipation monitoring (HS QCM-D), which enables continuous scanning of the film hydration. We investigate five surfactants films (DDAO, DTAC, CTAC, SDS, and n-octyl beta-D-glucoside) and one lipid film (monoolein) and show that HS QCM-D enables the fast characterization of hydration-induced phase transitions with small samples. Film thicknesses range from tens to hundreds of nanometers, and clear phase transitions are observed in all cases. It is shown that phase transitions in films occur at the same water activities as for corresponding bulk samples. This allows us to conclude that surfactant and lipid films, with a thickness of as low as 50 nm, are in fact assembled as 3D-structured liquid crystalline phases. Furthermore, liquid crystalline phases of surfactant films show liquidlike behavior, which decreases the accuracy of the absorbed water mass measurement. On the other hand, the monoolein lipid forms more rigid liquid crystalline films, allowing for an accurate determination of the water sorption isotherm, which is also true for the sorption isotherms corresponding to the solid surfactant phases.
|
|
| 4. |
- Björklund, Sebastian, et al.
(författare)
-
The effects of polar excipients transcutol and dexpanthenol on molecular mobility, permeability, and electrical impedance of the skin barrier
- 2016
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 479, s. 207-220
-
Tidskriftsartikel (refereegranskat)abstract
- In the development of transdermal and topical products it is important to understand how formulation ingredients interact with the molecular components of the upper layer of the skin, the stratum corneum (SC), and thereby influence its macroscopic barrier properties. The aim here was to investigate the effect of two commonly used excipients, transcutol and dexpanthenol, on the molecular as well as the macroscopic properties of the skin membrane. Polarization transfer solid-state NMR methods were combined with steady-state flux and impedance spectroscopy measurements to investigate how these common excipients influence the molecular components of SC and its barrier function at strictly controlled hydration conditions in vitro with excised porcine skin. The NMR results provide completely new molecular insight into how transcutol and dexpanthenol affect specific molecular segments of both SC lipids and proteins. The presence of transcutol or dexpanthenol in the formulation at fixed water activity results in increased effective skin permeability of the model drug metronidazole. Finally, impedance spectroscopy data show clear changes of the effective skin capacitance after treatment with transcutol or dexpanthenol. Based on the complementary data, we are able to draw direct links between effects on the molecular properties and on the macroscopic barrier function of the skin barrier under treatment with formulations containing transcutol or dexpanthenol.
|
|
| 5. |
- Björklund, Sebastian, et al.
(författare)
-
Water vapor sorption-desorption hysteresis in glassy surface films of mucins investigated by humidity scanning QCM-D
- 2019
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 545, s. 289-300
-
Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: Investigating the origin of water sorption-desorption hysteresis in glassy biopolymers is important for understanding the properties of biological barriers, such as the mucus epithelium. In general, hysteresis is a result of a complex interplay between diffusion of water and relaxation of the polymer matrix. Our hypothesis is that for thin films, typical for quartz crystal microbalance with dissipation monitoring (QCM-D) experiments performed in gas phase with defined relative humidity, the diffusion limitation is eliminated and hysteresis results only from relaxation of the polymer matrix. Experiments: We use a recently developed humidity scanning (HS) QCM-D method to obtain water sorption-desorption isotherms of mucin films under controlled conditions where water diffusion is not the limiting factor, neither in the vapor phase nor in the glassy mucin film. Findings: We present new results on the water sorption-desorption behavior of glassy mucin films with nanoscale thicknesses. Despite the fact that water diffusion is not the limiting factor, the sorption-desorption branches show clear hysteresis effects that are similar to those typically observed in bulk samples. The hydration-induced glass transition, resolved from monitoring the rheological behavior of the films, is shown to be in excellent agreement with the onset of the sorption-desorption hysteresis. We suggest that the hysteresis effect is related to a difference in dynamical and structural properties of the glassy materials depending on the hydration history of the films.
|
|
| 6. |
- Cancino-Montecinos, Sebastian, et al.
(författare)
-
Cognitive dissonance leads to an abstract mindset
- 2016
-
Ingår i: Book of abstract. ; , s. 38-38
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study investigated the effects of cognitive dissonance on abstract thinking. According to action-identification theory, whenever people try to understand a situation in a new way, they activate an abstract mindset. Based on this premise, dissonance was hypothesized to put people in an abstract mindset. The induced compliance paradigm, in which participants are asked to write a counter-attitudinal essay under either low choice (producing little dissonance) or high choice (producing more dissonance), was employed. Results showed that dissonance did in fact activate a more abstract mindset, and this effect was more pronounced for participants having a more concrete mindset to begin with. This suggests that increasing abstraction, as a reaction to cognitive conflict, is a way for people to resolve inconsistencies.
|
|
| 7. |
- Cancino-Montecinos, Sebastian, et al.
(författare)
-
Dissonance and abstraction : Cognitive conflict leads to higher level of construal
- 2018
-
Ingår i: European Journal of Social Psychology. - : Wiley. - 0046-2772 .- 1099-0992. ; 48:1, s. 100-107
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effects of cognitive conflict on abstract thinking. According to action-identification theory, an ambiguous and unfamiliar situation might propel an individual to a more abstract mindset. Based on this premise, cognitive conflict was hypothesized to put people in an abstract mindset. The induced compliance paradigm, in which participants are asked to write a counter-attitudinal essay under either low choice (producing little dissonance) or high choice (producing more dissonance), was employed. Results showed that an abstract mindset was in fact activated in the induced compliance paradigm, and this effect was more pronounced for participants having a more concrete mindset to begin with. The results suggest that the experience of cognitive conflict is closely related to increased abstraction.
|
|
| 8. |
- Cancino-Montecinos, Sebastian, et al.
(författare)
-
Dissonance reduction as emotion regulation: Attitude change is related to positive emotions in the induced compliance paradigm.
- 2018
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203.
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to clarify how positive and negative emotions are related to the common attitude-change effect in cognitive dissonance research. Drawing on appraisal theories of emotion, and emotion-regulation research, we predicted that negative emotions would be inversely related to attitude change, whereas positive emotions would be positively related to attitude change in the induced compliance paradigm. In two studies, participants (N = 44; N = 106) wrote a counter-attitudinal essay under the perception of high choice, and were later asked to state their emotions in relation to writing this essay, as well as to state their attitude. Results confirmed the predictions, even when controlling for baseline emotions. These findings untangled a previously unresolved issue in dissonance research, which in turn shows how important emotion theories are for the understanding of cognitive dissonance processes.
|
|
| 9. |
- Cancino-Montecinos, Sebastian, et al.
(författare)
-
The effects of cognitive dissonance on abstract thinking : Dissonance leads to an abstract mindset
- 2016
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this study, we investigated how individuals’ abstract thinking increases when experiencing dissonance. Dissonance theory holds that people reduce dissonance by accommodating their attitudes in order to fit their most recent behavior. This process resembles the reasoning of action-identification theory (AIT), which postulates that people usually try to understand their actions in a meaningful and coherent way, and also that actions can take on new meanings when people move from a low-level to a high-level understanding of the action. Thus, acting inconsistently threatens the coherent understanding of ones action; and in order to regain a sense of consonance, people will try to find a new meaning of their action (e.g., via attitude change). However, this occurs when moving to a high-level understanding (i.e., thinking more abstractly) of ones action. However, the effect of dissonance on abstraction should be stronger for individuals with low level of abstraction to begin with – since AIT holds that people who naturally tend to think abstractly already have high-level understandings of their actions. We predicted that: (1) dissonance puts people in a more abstract mindset, and (2) this effect will be more apparent for individuals low in abstraction. First, we established participants’ natural tendencies to abstract thinking with the Gestalt Completion Test (GCT). This variable was later split into low and high GCT. Several days later, we employed the induced compliance paradigm, in which participants were asked to write a counter-attitudinal essay under either low choice or high choice. High-choice participants usually experience more dissonance. We also created a neutral condition (to serve as a comparison to the other conditions) in which individuals were asked to write a pro-attitudinal essay. After the induced compliance manipulation, the Behavior Identification Form (BIF) was used to measure abstraction. The sample consisted of 125 non-psychology students. A 3 (condition: high-choice vs. low-choice vs. neutral) ˙ 2 (GCT: low vs. high) between subjects factorial ANOVA showed that participants in the high-choice condition (who experienced more dissonance) did exhibit a more abstract mindset, and level of GCT moderated this effect. The following simple effects analysis showed a significant effect for the low-GCT groups: (F(2, 119) = 6.607, p = .002, η2 = .100) and the pairwise comparisons revealed that high-choice participants exhibited a significantly more abstract mindset (M = 16.65, SD = 4.54) compared to both the low-choice participants (M = 13.18, SD = 4.45) p = .013, d = .77 and the neutral participants (M = 12.25, SD = 4.71) p < .001, d = .95. No significant effects were found when comparing the high-GCT groups (p = .398). The present study demonstrated that dissonance activates abstract thinking, which is thought to facilitate people’s understanding their recent actions. This finding has important implication for the future study of consequences of cognitive conflicts, and also the study of how abstraction enables people to find new meanings of their own actions. Hence, investigation on these mechanisms could shed more light on how people regulate their thoughts, emotions and behavior in real time.
|
|
| 10. |
- Ericson, Petter, 1986-
(författare)
-
Order-preserving graph grammars
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The field of semantic modelling concerns formal models for semantics, that is, formal structures for the computational and algorithmic processing of meaning. This thesis concerns formal graph languages motivated by this field. In particular, we investigate two formalisms: Order-Preserving DAG Grammars (OPDG) and Order-Preserving Hyperedge Replacement Grammars (OPHG), where OPHG generalise OPDG.Graph parsing is the practise of, given a graph grammar and a graph, to determine if, and in which way, the grammar could have generated the graph. If the grammar is considered fixed, it is the non-uniform graph parsing problem, while if the grammars is considered part of the input, it is named the uniform graph parsing problem. Most graph grammars have parsing problems known to be NP-complete, or even exponential, even in the non-uniform case. We show both OPDG and OPHG to have polynomial uniform parsing problems, under certain assumptions.We also show these parsing algorithms to be suitable, not just for determining membership in graph languages, but for computing weights of graphs in graph series.Additionally, OPDG is shown to have several properties common to regular languages, such as MSO definability and MAT learnability. We moreover show a direct corresponcence between OPDG and the regular tree grammars.Finally, we present some limited practical experiments showing that real-world semantic graphs appear to mostly conform to the requirements set by OPDG, after minimal, reversible processing.
|
|
