| 1. |
- Fernández-Nieves, A., et al.
(författare)
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Microgel Suspensions: Fundamentals and Applications
- 2011
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- Providing a vital link between chemistry and physics on the nanoscale, this book offers concise coverage of the entire topic in five major sections, beginning with synthesis of microgel particles and continuing with their physical properties. The phase behavior and dynamics of resulting microgel suspensions feature in the third section, followed by their mechanical properties. It concludes with detailed accounts of numerous industrial, commercial and medical applications.Edited by David Weitz, Professor at Harvard and one of the world's pre-eminent experts in the field.
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| 2. |
- Sillrén, Per, 1982, et al.
(författare)
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A statistical model of hydrogen bond networks in liquid alcohols
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 136:9, s. 094514-094521
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Tidskriftsartikel (refereegranskat)abstract
- We here present a statistical model of hydrogen bond induced network structures in liquid alcohols. The model generalises the Andersson-Schulz-Flory chain model to allow also for branched structures. Two bonding probabilities are assigned to each hydroxyl group oxygen, where the first is the probability of a lone pair accepting an H-bond and the second is the probability that given this bond also the second lone pair is bonded. The average hydroxyl group cluster size, cluster size distribution, and the number of branches and leaves in the tree-like network clusters are directly determined from these probabilities. The applicability of the model is tested by comparison to cluster size distributions and bonding probabilities obtained from Monte Carlo simulations of the monoalcohols methanol, propanol, butanol, and propylene glycol monomethyl ether, the di-alcohol propylene glycol, and the tri-alcohol glycerol. We find that the tree model can reproduce the cluster size distributions and the bonding probabilities for both mono- and poly-alcohols, showing the branched nature of the OH-clusters in these liquids. Thus, this statistical model is a useful tool to better understand the structure of network forming hydrogen bonded liquids. The model can be applied to experimental data, allowing the topology of the clusters to be determined from such studies.
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| 3. |
- Sjöström, Johan, 1978, et al.
(författare)
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Dielectric secondary relaxation of water in aqueous binary glass-formers
- 2010
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 12:35, s. 10452-10456
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Tidskriftsartikel (refereegranskat)abstract
- Glassy aqueous binary mixtures generally exhibit a water induced dielectric relaxation. The characteristic time-scale of this relaxation follows an Arrhenius temperature dependence with a nearly universal activation energy. We here demonstrate for a series of model aqueous mixtures that the relaxation time also follows a remarkably general exponential dependence on the weight fraction of water. By comparison to literature data we show that this behaviour is shared by a wide range of molecular systems. Neither the detailed nature of the water molecules' glassy environment nor the details of the route of formation of the glassy state has a significant effect on the observed behaviour.
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| 4. |
- Sjöström, Johan, 1978, et al.
(författare)
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Effects of Water Contamination on the Supercooled Dynamics of a Hydrogen-Bonded Model Glass Former
- 2011
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:8, s. 1842-1847
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Tidskriftsartikel (refereegranskat)abstract
- Broad-band dielectric spectroscopy is a commonly used tool in the study of glass-forming liquids. The high sensitivity of the technique together with the wide range of probed time scales makes it a powerful method for investigating the relaxation spectra of liquids. One particularly important class of glass-forming liquids that is often studied using this technique consists of liquids dominated by hydrogen (H) bond interactions. When investigating such liquids, particular caution has to be taken during sample preparation due to their often highly hygroscopic nature. Water can easily be absorbed from the atmosphere, and dielectric spectroscopy is a very sensitive probe of such contamination due to the large dipole moment of water. Our knowledge concerning the effects of small quantities of water on the dielectric properties of these commonly investigated liquids is limited. We here demonstrate the effects due to the presence of small amounts of water on the dielectric response of a typical H-bonded model glass former, tripropylene glycol. We show how the relaxation processes present in the pure liquid are affected by addition of water, and we find that a characteristic water induced relaxation response is observed for water contents as low as 0.15 wt %. We stress the importance of careful purification of hygroscopic liquids before experiments and quantify what the effects are if such procedures are not undertaken.
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| 5. |
- Sjöström, Johan, 1978, et al.
(författare)
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Hydrogen Bond Induced Nonmonotonic Composition Behavior of the Glass Transition in Aqueous Binary Mixtures
- 2011
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:33, s. 10013-10017
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Tidskriftsartikel (refereegranskat)abstract
- The glass transition temperature, T(g), of a binary mixture commonly varies monotonically between the T(g)s of its two components. However, mixtures of strongly associating liquids can instead exhibit a nonmonotonic T(g) variation. The origins of such nonideal mixing behavior have often been correlated with composition dependent structural variations. For binary mixtures between a hydrogen- (H-) bonded liquid and water, however, such behavior is generally not well understood. The ubiquity and importance of aqueous mixtures both in nature and in man-made applications stresses the needed for a better understanding. We here demonstrate nonmonotonic T(g) variations in binary mixtures of n-propylene glycol monomethyl ethers (nPGMEs) and water, where the composition dependent T(g) show maxima within an intermediate composition range. We show that these T(g) maxima correspond to crossovers in the composition dependence of the step amplitude in the isobaric heat capacity at T(g). We further demonstrate that the observed effects are caused by H-bond interactions involving the nPGME hydroxyl group. We can account for our obervations using a simple model based on two effects due to the added water: (i) an H-bond induced formation of effective relaxing entities and (ii) a plasticizing effect at high water contents.
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| 6. |
- Burman, Pia, et al.
(författare)
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Deaths Among Adult Patients With Hypopituitarism: Hypocortisolism During Acute Stress, and De Novo Malignant Brain Tumors Contribute to an Increased Mortality
- 2013
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Ingår i: Journal of Clinical Endocrinology & Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 98:4, s. 1466-1475
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Tidskriftsartikel (refereegranskat)abstract
- Context: Patients with hypopituitarism have an increased standardized mortality rate. The basis for Objective: To investigate in detail the cause of death in a large cohort of patients with hypopituitarism Design and Methods: All-cause and cause-specific mortality in 1286 Swedish patients with Main Outcome Measures: Standardized mortality ratios (SMR) were calculated, with stratification for Results: An excess mortality was found, 120 deaths vs 84.3 expected, SMR 1.42 (95% confidence Conclusion: Two important causes of excess mortality were identified: first, adrenal crisis in response
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| 7. |
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| 9. |
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| 10. |
- Mattsson, Johan, 1969, et al.
(författare)
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Effects of hydrogen bonding on supercooled liquid dynamics and the implications for supercooled water
- 2009
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 79:17, s. 174205-
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Tidskriftsartikel (refereegranskat)abstract
- The supercooled state of bulk water is largely hidden by unavoidable crystallization, which creates an experimentally inaccessible temperature regime - a "no man's land." We address this, and circumvent the crystallization problem by systematically studying the supercooled dynamics of hydrogen bonded oligomeric liquids (glycols), where water corresponds to the chain ends alone. This approach permits a "dilution of water" by altering the hydrogen bond concentration via variations in chain length. We observe a dynamic crossover in the temperature dependence of the structural relaxation time for all glycols, consistent with the common behavior of most supercooled liquids. We find that the crossover becomes more pronounced for increasing hydrogen bond concentrations, which leads to the prediction of a marked dynamic transition for water within "no man's land" at T similar to 220 K. Interestingly, the predicted transition thus takes place at a temperature where a so called "strong-fragile" transition has previously been suggested. Our results, however, imply that the dynamic transition of supercooled water is analogous to that commonly observed in supercooled liquids. Moreover, we find support also for the existence of a secondary relaxation of water with behavior analogous to that of the secondary relaxation observed for the glycols.
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