| 61. |
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| 62. |
- Andersson, Ove
(författare)
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Thermal conductivity of normal and deuterated water, crystalline ice, and amorphous ices
- 2018
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 149:12
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Tidskriftsartikel (refereegranskat)abstract
- The effect of deuteration on the thermal conductivity kappa of water, crystalline ice, and amorphous ices was studied using the pressure induced amorphization of hexagonal ice, ice Ih, to obtain the deuterated, D2O, forms of low-density amorphous (LDA), high-density amorphous (HDA), and very-high density amorphous (VHDA) ices. Upon deuteration, kappa of ice Ih decreases between 3% and 4% in the 100-270 K range at ambient pressure, but the effect diminishes on densification at 130 K and vanishes just prior to amorphization near 0.8 GPa. The unusual negative value of the isothermal density rho dependence of kappa for ice Ih, g = (d ln kappa/d ln rho)(T) = -4.4, is less so for deuterated ice: g = -3.8. In the case of the amorphous ices and liquid water, kappa of water decreases by 3.5% upon deuteration at ambient conditions, whereas K of HDA and VHDA ices instead increases by up to 5% for pressures up to 1.2 GPa at 130 K, despite HDA's and VHDA's structural similarities with water. The results are consistent with significant heat transport by librational modes in amorphous ices as well as water, and that deuteration increases phonon-phonon scattering in crystalline ice. Heat transport by librational modes is more pronounced in D2O than in H2O at low temperatures due to a deuteration-induced red-shift of librational mode frequencies. Moreover, the results show that kappa of deuterated LDA ice is 4% larger than that of normal LDA at 130 K, and both forms display an unusual temperature dependence of kappa, which is reminiscent of that for crystals (kappa similar to T (-1)), and a unique negative pressure dependence of kappa, which likely is linked to local-order structural similarities to ice Ih.
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| 63. |
- Andersson, Ove, et al.
(författare)
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Thermal Properties and Transition Behavior of Host –Guest Compounds under High Pressure
- 2014
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Ingår i: Current inorganic chemistry. - : Bentham Science Publishers Ltd.. - 1877-9441. ; 4:1, s. 2-18
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The thermal properties and transition behavior of the host-guest inclusion compounds: urea, thiourea, Dianin’s compound, clathrate hydrates and hydroquinone have been reviewed. In particular, we summarize their thermal conductivities, heat capacities and transitions at high pressures. Two of the systems: urea inclusion compounds and clathrate hydrates, show unusual glass-like thermal conductivity k, i.e. their k is low and only weakly dependent on temperature despite their crystalline structure. Moreover, results for k of Dianin’s compound with guests such as ethanol and CCl4 indicate a change from glass-like k at atmospheric pressure to crystalline-like k at elevated pressure, whereas k of hydroquinone and thiourea inclusion compounds appears not to have been studied. Despite the technological and fundamental importance of the unusual glass-like k, e.g. the use of inclusion compounds as structural model systems for finding improved thermoelectrical materials, the origin of the glass-like k is not established. More specifically, the commonly employed rattling model, in which rattling guest motions cause resonance scattering of the acoustic host phonons, has recently been challenged, and we discuss alternative models. Heat capacity studies of these compounds reveal numerous transitions, which are associated with guest and host disorder-order transitions upon cooling and pressurization. A transition in hydroquinone may be of second order, or have only a small first-order component, which can explain discrepancies in the observed transition behavior. On pressurization at low temperatures, clathrate hydrates collapse to an amorphous state, which appears to be a glassy state of a water solution with perfectly spaced solute molecules.
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| 64. |
- Andersson, Ove, et al.
(författare)
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Time-dependent amorphization of ice at 0.8-0.9 GPa
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP. - 0021-9606 .- 1089-7690. ; 121:8, s. 3936-3938
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Tidskriftsartikel (refereegranskat)abstract
- Thermal conductivity measurements show that ice continues to amorphize for several days when kept at a fixed pressure p in the 0.79–0.88 GPa range, and fixed temperature T in the 127–130 K range. Thermal conductivity k decreases according to a stretched exponential in time, and its limiting long time value k() varies with p and T. At 0.8 GPa and 128 K, k() remains 2.5 times the value observed for high-density amorph. Consequences of these findings for our understanding of amorphization are discussed.
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| 65. |
- Andersson, Ove, et al.
(författare)
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Transitions in pressure-amorphized clathrate hydrates akin to those of amorphous ices
- 2019
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 151:1
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Tidskriftsartikel (refereegranskat)abstract
- Type II clathrate hydrates (CHs) were studied by thermal and dielectric measurements. All CHs amorphize, or collapse, on pressurization to 1.3 GPa below 135 K. After heating to 160 K at 1 GPa, the stability of the amorphous states increases in a process similar to the gradual high density to very high density amorphous ice (HDA to VHDA) transition. On a subsequent pressure decrease, the amorphized CHs expand partly irreversibly similar to the gradual VHDA to expanded HDA ice transformation. After further heating at 1 GPa, weak transition features appear near the HDA to low density amorphous ice transition. The results suggest that CH nucleation sites vanish on heating to 160 K at 1 GPa and that a sluggish partial phase-separation process commences on further heating. The collapsed CHs show two glass transitions (GTs), GT1 and GT2. GT1 is weakly pressure-dependent, 12 K GPa(-1), with a relaxation time of 0.3 s at 140 K and 1 GPa; it is associated with a weak heat capacity increase of 3.7 J H2O-mol(-1) K-1 in a 18 K range and an activation energy of only 38 kJ mol(-1) at 1 GPa. The corresponding temperature of GT2 is 159 K at 0.4 GPa with a pressure dependence of 36 K GPa(-1); it shows 5.5 times larger heat capacity increase and 4 times higher activation energy than GT1. GT1 is observed also in HDA and VHDA, whereas GT2 occurs just above the crystallization temperature of expanded HDA and only within its similar to 0.2-0.7 GPa stable pressure range.
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| 66. |
- Andersson, Ove, et al.
(författare)
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Transitions in pressure collapsed clathrate hydrates
- 2015
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 119:9, s. 3846-3853
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Tidskriftsartikel (refereegranskat)abstract
- Type II clathrate hydrates (CHs), or ice clathrates, are inclusion compounds in which a hydrogen-bonded cage-like structure of H2O accommodates molecules of suitable size, known as guest molecules. CHs have similar local geometrical arrangements of the hydrogen-bonded water network as ice and both are known to collapse to amorphous states on isothermal pressurization at temperatures below about 140 K. Moreover, the collapsed CH states undergo a glass, or glass-like, transition at 140 K on heating at 1 GPa, which is identical to that of collapsed ice, or high density amorphous ice. Here we use thermal conductivity and dielectric measurements to study the transition behavior of two type II CHs with tetrahydrofuran and 1,3 dioxolane, respectively, as guest molecules. After their collapsed states have been heated to well above the glass transition at 1 GPa, we find transitions corresponding to the high to low density amorphous ice transition of ice with only slightly shifted temperature-pressure (T-p) coordinates compared to those of pure water. Thus, collapsed CHs show the same transition behaviors as cold water, which provide the basis for the model that explains the unusual temperature and pressure behaviors of waters properties in terms of two distinct types of liquid water. Collapsed CHs are, however, more stable than collapsed ice and can therefore be studied in a wider T-p interval. The results suggest sluggish homogenizing and phase separation processes, which affect the transition behaviors of collapsed CHs.
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| 67. |
- Andersson, Ove, et al.
(författare)
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Tricritical Lifshitz point in the temperature-pressure-composition diagram for (PbySn1-y)2 P2(SexS1-x)6 ferroelectrics
- 2009
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 80, s. 174107-
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Tidskriftsartikel (refereegranskat)abstract
- The heat capacity of Sn2P2S6 ferroelectric crystals has been measured under quasihydrostatic pressures up to 0.7 GPa. The analysis of the heat-capacity and literature data for the birefringence shows that the tricritical point of Sn2P2S6 is in the 0.20–0.25 GPa range. Moreover, in the approximation of a linear change in the free-energy expansion coefficients, with respect to concentration and pressure, thermodynamic trajectories have been constructed for (PbySn1−y)2 P2(SexS1−x)6 solid solutions. We have thereby identified the region of the T-p-y-x diagram for (PbySn1−y)2 P2(SexS1−x)6 showing the tricritical Lifshitz point.
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| 68. |
- Andersson, Ove, et al.
(författare)
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Unusual Grüneisen and Bridgman parameters of low-density amorphous ice and their implications on pressure induced amorphization
- 2005
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 122:12, s. 124710-
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Tidskriftsartikel (refereegranskat)abstract
- The low-temperature limiting value of the Grüneisen parameter for low-frequency phonons and the density dependence of the thermal conductivity (Bridgman parameter) of low-density amorphous (LDA) ice, high-density amorphous (HDA) ice, hexagonal ice Ih, and cubic ice Ic were calculated from high-pressure sound velocity and thermal conductivity measurements, yielding negative values for all states except HDA ice. LDA ice is the first amorphous state to exhibit a negative Bridgman parameter, and negative Grüneisen parameters are relatively unusual. Since Ih, Ic, and LDA ice all transform to HDA upon pressurization at low temperatures and share the unusual feature of negative Grüneisen parameters, this seems to be a prerequisite for pressure induced amorphization. We estimate that the Grüneisen parameter increases at the ice Ih to XI transition, and may become positive in ice XI, which indicates that proton-ordered ice XI does not amorphize like ice Ih on pressurization.
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| 69. |
- Andersson, Patiyan, 1978-, et al.
(författare)
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Genome-wide analysis of penile cancer using high-density single nucleotide polymorphism arrays
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The availability of genome-wide high-density single nucleotide polymorphism (SNP) arrays makes it possible to in a structured manner study chromosome aberrations in penile cancer where little is known of disruptive genetic events. In this study 19 penile squamous cell carcinomas were analyzed using the 250k NspI SNP array from Affymetrix. We find major regions of frequent copy number gain in chromosome arms 3q, 5p and 8q, and slightly less frequent in 1p, 16q and 20q. The chromosomal regions of most frequent copy number losses were 3p, 4q, 11p and 13q. We identified four candidate genes residing in the major chromosomal regions of aberration. Eight tumours showed copy number gain of the PIK3CA gene located to 3q26.3. Five of the remaining tumours carried an activating mutation of the PIK3CA gene and these tumours showed very few chromosomal aberrations. Collectively, disruption of the PIK3CA gene was found in 13/19 samples, and presence of active phosphorylated AKT was confirmed immunohistochemically in these tumours indicating an active signalling pathway. We found copy number gain of the hTERT gene (5p15.33) in 7 samples and of the Myc gene (8q24.21) in 7 samples. Copy number loss of the tumoursuppressor gene FHIT (3p14.2) was observed in 8 samples, the same 8 samples that showed copy number gain of the PIK3CA gene. In total the PI3K/AKT and RAS/MAPK pathways were found to be activated through mutation or amplification in 64% of the cases, indicating the significance of these pathways in the aetiology of penile cancer.
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| 70. |
- Andersson, Sten-Ove, et al.
(författare)
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Doctors’ and Nurses’ Perceptions of Military Pre-hospital Emergency Care
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study was to identify physicians’ and nurses’ perceptions of military prehospital emergency care before and after an international mission. A qualitative empirical study with a phenomenographic approach was used. The aim is to identify the area of knowledge, pre-hospital care in a military environment, in terms of expressions from doctors and nurses focussing on the variation in how learning of pre-hospital care is perceived. The result of the study is a set of descriptive categories on a collective level, showing the variation in how doctors and nurses perceived the phenomenon of military pre-hospital emergency care. The results after predeployment training can be categorized as (1) to learn military medicine, (2) to take care of the casualty and (3) to have safety awareness. The results after an international mission can be categorized as (1) to collaborate with others, (2) to deliver general health care, and (3) to improve competence in military medicine. Possible implications of the results from the present study are the following; (I) better conditions for doctors and nurses to provide appropriate military medical care by clarification and better understanding of professions in the mission area (doctors, nurses, officers), since they may have different goals for their actions, (II) to pay attention to all aspects of military health care during predeployment training, including general health care in the mission area, (III) to implement new knowledge in military medicine in the predeployment training, and (IV) to train for the reality all doctors and nurses are about to meet. These results indicate that the training should be developed in order to optimize the prepare physicians and nurses for international assignments. This may result in increased safety for the provider of care, while at the same time minimizing suffering and enhancing the possibility of survival of the injured.
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