| 1. |
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| 2. |
- Andersson, S. Peter, et al.
(författare)
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Relaxation Studies of Poly(propylene glycol) under High Pressure
- 1998
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 31:9, s. 2999-3006
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pressure on the relaxation processes in poly(propylene glycol) of number-average molecular weights 400 and 4000 g mol-1 (PPG-400 and PPG-4000) has been investigated using dielectric spectroscopy as well as thermal conductivity and heat capacity measurements. The relaxations associated with segmental motions within the polymer chain (α relaxation) and whole chain motions (α' relaxation) have been studied in the temperature range 200-400 K for pressures up to 2 GPa. The two processes display slightly different sensitivities to pressure, and as a consequence, are better separated at high pressures. As a result, high-pressure data exhibit the α' relaxation also in PPG-400, whereas previous investigations at atmospheric pressure have detected it only in PPG of molecular weights above about 1000 g mol-1. At atmospheric pressure, the values for (∂T/∂p)τ=1s of the alpha relaxation are, respectively, 140 and 192 K GPa-1 for PPG-400 and PPG-4000, where τ is the relaxation time. Because of the difference in (∂T/∂p)τ, the relaxation of the α motions and therefore the glass-transition temperature exhibits a more significant dependence on molecular weight at high pressures. At 295 K and 0.3 GPa, the activation volumes for the α and α' processes of PPG-4000 are about the same (approximate to 45 cm3 mol-1). At the same conditions, the activation volume for the α process of PPG-400 is about half of that for PPG-4000. An analysis of the α relaxation in terms of the strong-fragility classification shows that the degree of fragility of both PPG-400 and PPG-4000 increases slightly with increasing pressure.
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| 3. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity, heat capacity, and compressibility of atactic poly(propylene) under high pressure
- 1997
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Ingår i: International journal of thermophysics. - : Springer Science and Business Media LLC. - 0195-928X .- 1572-9567. ; 18:3, s. 845-864
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and the heat capacity per unit volume of atactic poly(propylene) have been measured in the temperature range 90–420 K at pressures up to 1.5 GPa using the transient hot-wire method. The bulk modulus has been measured in the range 200–295 K and up to 0.7 GPa. These data were used to calculate the volume dependence of λ, g=−[∂λ/λ)/(∂V/V)]T, which yielded the following values for the glassy state (T<256 K at atmospheric pressure): 3.80±0.19 at 200 K, 3.74±0.19 at 225 K, 3.90±0.20 at 250 K, 3.77±0.19 at 271 K, and 3.73±0.19 at 297 K. The resultant value for g of the liquid state was 3.61±0.15 at 297 K. Values for g which are calculated at 295 K, using theoretical models of λ(T), agree to within 12% with the experimental value for the glassy state.
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| 4. |
- Andersson, S. Peter, et al.
(författare)
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Thermal conductivity of amorphous Teflon (AF 1600) at high pressure
- 1997
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Ingår i: International journal of thermophysics. - : Springer Nature. - 0195-928X .- 1572-9567. ; 18:1, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity, λ, of amorphous Teflon AF 1600 [poly(1,3-dioxole-4,5-difluoro-2,2-bis(trifluoromethyl)-co-tetrafluoroethylene)] has been measured at pressures up to 2 GPa in the temperature range 93–392 K. At 295 K and atmospheric pressure, we obtained λ=0.116 W·m−1·K−1. The bulk modulus was measured up to 1.0 GPa in the temperature range 150–296 K and the combined data yielded the following values of g=(∂ln λ/∂ln V)T :2.8±0.2 at 296 K, 3.0±0.2 at 258 K, 3.0±0.2 at 236 K, 3.4±0.2 at 200 K, and 3.4±0.2 at 150 K.
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| 5. |
- Andersson, S. Peter, et al.
(författare)
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Volume dependence of thermal conductivity and bulk modulus for poly(propylene glycol)
- 1998
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Ingår i: Journal of Polymer Science Part B. - : John Wiley & Sons. - 0887-6266 .- 1099-0488. ; 36:2, s. 345-355
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and heat capacity per unit volume of poly(propylene glycol) PPG (0.4 and 4.0 kg.mol-1 in number-average molecular weight) have been measured in the temperature range 150-295 K at pressures up to 2 GPa using the transient hot-wire method. At 295 K and atmospheric pressure, λ = 0.147 W m-1K-1 for PPG (0.4 kg.mol-1) and λ = 0.151 W m-1K-1 for PPG (4.0 kg.mol-1). The temperature dependence of λ is less than 4 x 10-4 W m-1K-2 for both molecular weights. The bulk modulus has been measured in the temperature range 215-295 K up to 1.1 GPa. At atmospheric pressure, the room temperature bulk moduli are 1.97 GPa for PPG(0.4 kg.mol-1) and 1.75 GPa for PPG (4.0 kg.mol-1). These data were used to calculate the volume dependence of λ, g = -((∂λ/λ)/(∂V/V))T. At room temperature and atmospheric pressure (liquid phase) we find g = 2.79 for PPG (0.4 kg.mol-1) and g = 2.15 for PPG (4.0 kg.mol-1). The volume dependence of g, (∂g /∂ log V)T varies between -19 to -10 for both molecular weights. Under isochoric conditions, g is nearly independent of temperature. The difference in g between the glassy state and liquid phase is small and just outside the inaccuracy of g of about 8%. The theoretical model for λ by Horrocks and McLaughlin yields an overestimate of g by up to 120%.
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| 6. |
- Andersson, S. Peter, et al.
(författare)
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Volume dependence of thermal conductivity and isothermal bulk modulus up to 1 GPa for poly(vinyl acetate)
- 1998
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Ingår i: Journal of Polymer Science Part B. - : John Wiley & Sons. - 0887-6266 .- 1099-0488. ; 36:9, s. 1451-1463
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Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity λ and heat capacity per unit volume of poly(vinyl acetate) (260 kg mol-1 in weight average molecular weight) have been measured in the temperature range 150-450 K at pressures up to 1 GPa using the transient hot-wire method, which yielded λ = 0.19 W m-1 K-1 at atmospheric pressure and room temperature. The bulk modulus K has been measured in the temperature range 150-353 K up to 1 GPa. At atmospheric pressure and room temperature, K = 4.0 GPa and (∂K/∂p)T = 8.3. The volume data were used to calculate the volume dependence of λ,g = -((∂λ/λ)/(∂V/V))T.The values for g of the liquid and glassy states were 3.0 and 2.7, respectively, and g of the latter was almost independent of volume and temperature. Theoretical models can predict the value for g of the glassy state to within 25%.
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| 7. |
- Rafati, Nima, et al.
(författare)
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Large Deletions at the SHOX Locus in the Pseudoautosomal Region Are Associated with Skeletal Atavism in Shetland Ponies
- 2016
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Ingår i: G3. - : Oxford University Press (OUP). - 2160-1836. ; 6:7, s. 2213-2223
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Tidskriftsartikel (refereegranskat)abstract
- Skeletal atavism in Shetland ponies is a heritable disorder characterized by abnormal growth of the ulna and fibula that extend the carpal and tarsal joints, respectively. This causes abnormal skeletal structure and impaired movements, and affected foals are usually killed. In order to identify the causal mutation we subjected six confirmed Swedish cases and a DNA pool consisting of 21 control individuals to whole genome resequencing. We screened for polymorphisms where the cases and the control pool were fixed for opposite alleles and observed this signature for only 25 SNPs, most of which were scattered on genome assembly unassigned scaffolds. Read depth analysis at these loci revealed homozygosity or compound heterozygosity for two partially overlapping large deletions in the pseudoautosomal region (PAR) of chromosome X/Y in cases but not in the control pool. One of these deletions removes the entire coding region of the SHOX gene and both deletions remove parts of the CRLF2 gene located downstream of SHOX. The horse reference assembly of the PAR is highly fragmented, and in order to characterize this region we sequenced bacterial artificial chromosome (BAC) clones by single-molecule real-time (SMRT) sequencing technology. This considerably improved the assembly and enabled size estimations of the two deletions to 1602180 kb and 60280 kb, respectively. Complete association between the presence of these deletions and disease status was verified in eight other affected horses. The result of the present study is consistent with previous studies in humans showing crucial importance of SHOX for normal skeletal development.
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| 8. |
- Tonpheng, Bounphanh, 1959-, et al.
(författare)
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Tensile strength and young's modulus of polyisoprene/single-wall carbon nanotube composites increased by high pressure cross-linking
- 2010
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Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 43:18, s. 7680-7688
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Tidskriftsartikel (refereegranskat)abstract
- High-viscosity liquid cis-1,4 polyisoprene (PI), with up to 20 wt % single-wall carbon nanotubes (SWCNTs), has been cross-linked by high pressure and high temperature (HP&HT) treatment at 513 K and pressures in the range 0.5 to 1.5 GPa to yield densified network polymer composites. A composite with 5 wt % SWCNTs showed 2.2 times higher tensile strength σUTS (σUTS = 17 MPa), 2.3 times higher Young’s modulus E (E = 220 MPa) and longer extension at break than pure PI. The improvement is attributed to SWCNT reinforcement and improved SWCNT−PI interfacial contact as a result of the HP&HT cross-linking process, and reduced brittleness despite a higher measured cross-link density than that of pure PI. The latter may originate from an effect similar to crazing, i.e., bridging of microcracks by polymer fibrils. We surmise that the higher cross-link densities of the composites are due mainly to physical cross-links/constraints caused by the SWCNT−PI interaction, which also reflects the improved interfacial contact, and that the CNTs promote material flow by disrupting an otherwise chemically cross-linked network. We also deduce that the PI density increase at HP&HT cross-linking is augmented by the presence of CNTs.
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| 9. |
- Ali, Imran, et al.
(författare)
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Exposure to polychlorinated biphenyls and prostate cancer : population-based prospective cohort and experimental studies
- 2016
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Ingår i: Carcinogenesis. - : Oxford University Press. - 0143-3334 .- 1460-2180. ; 37:12, s. 1144-1151
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Tidskriftsartikel (refereegranskat)abstract
- Polychlorinated biphenyls (PCBs) are highly persistent environmental pollutants and are undesirable components of our daily food. PCBs are classified as human carcinogens, but the evidence for prostate cancer is limited and available data are inconsistent. We explored the link between non-dioxin-like PCB and grade of prostate cancer in a prospective cohort as well as in cell experiments. A population-based cohort of 32496 Swedish men aged 45-79 years was followed prospectively through 1998-2011, to assess the association between validated estimates of dietary PCB exposure and incidence of prostate cancer by grade (2789 cases, whereof 1276 low grade, 756 intermediate grade, 450 high grade) and prostate cancer mortality (357 fatal cases). In addition, we investigated a non-dioxin-like PCB153-induced cell invasion and related markers in normal prostate stem cells (WPE-stem) and in three different prostate cancer cell lines (PC3, DU145 and 22RV1) at exposure levels relevant to humans. After multivariable-adjustment, dietary PCB exposure was positively associated with high-grade prostate cancer, relative risk (RR) 1.35 [95% confidence interval (CI): 1.03-1.76] and with fatal prostate cancer, RR 1.43 (95% CI: 1.05-1.95), comparing the highest tertile with the lowest. We observed no association with low or intermediate grade of prostate cancer. Cell invasion and related markers, including MMP9, MMP2, Slug and Snail, were significantly increased in human prostate cancer cells as well as in prostate stem cells after exposure to PCB153. Our findings both from the observational and experimental studies suggest a role of non-dioxin-like PCB153 in the development of high-grade and fatal prostate cancer.
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| 10. |
- Alm, Ove, et al.
(författare)
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A multiple coaxial wire for pressure calibration
- 1974
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 45:4, s. 594-595
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Tidskriftsartikel (refereegranskat)abstract
- A single wire containing several metals suitable for pressure calibration has been produced by extrusion. Coaxial combinations of Ce-Bi-TI and Ce-Bi-Ba have been prepared by the procedure described.
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| 11. |
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| 12. |
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| 13. |
- Almgren, Torbjörn, 1959, et al.
(författare)
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Diabetes in treated hypertension is common and carries a high cardiovascular risk: results from a 28-year follow-up.
- 2007
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Ingår i: Journal of hypertension. - 0263-6352. ; 25:6, s. 1311-7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The objective of this study was to analyse predictive factors for development of type 2 diabetes during life-long therapy for hypertension and the alleged additional cardiovascular risk this constitutes. METHODS: The study group (n = 754) comprised the hypertensive subgroup of a randomized population sample of 7500 men, aged 47-54 years, screened for cardiovascular risk factors and followed for 25-28 years. The patients were treated with thiazide diuretics and beta-adrenergic blocking drugs with the addition of hydralazin during the first decade. Calcium antagonists were substituted for hydralazin and, if needed, angiotensin-converting enzyme inhibitors were added when these drugs became available. RESULTS: A total of 148 (20.4%) treated hypertensive patients developed diabetes during 25 years, and in multivariate Cox regression analysis body mass index, serum triglycerides and treatment with beta-blockers were positively related with this complication. New-onset diabetes implied a significantly increased risk for stroke [hazard ratio (HR): 1.67; 95% confidence interval (95% CI): 1.1-2.6; P < 0.05], myocardial infarction (OR: 1.66; 95% CI: 1.1-2.5; P < 0.05) and mortality (OR: 1.42; 95% CI: 1.1-1.9; P < 0.05). The greatest risk for stroke was new-onset diabetes, followed by smoking (OR: 1.46; 95% CI: 1-2.2; P = 0.07) and the greatest risk for myocardial infarction was new-onset diabetes, followed by smoking (HR: 1.64; 95% CI: 1.1-2.4; P < 0.01). The greatest risk for mortality was smoking (HR: 1.73; 95% CI: 1.3-2.2; P < 0.005). Achieved systolic and diastolic blood pressure were not predictive of cardiovascular complications or death. The mean observation time from onset of diabetes mellitus to a first stroke was 9.1 years and to a first myocardial infarction 9.3 years. CONCLUSION: Diabetes in treated hypertensive patients is alarmingly common and carries a high risk for cardiovascular complications and mortality.
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| 14. |
- Almgren, T., et al.
(författare)
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Stroke and coronary heart disease in treated hypertension -- a prospective cohort study over three decades
- 2005
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Ingår i: J Intern Med. - 0954-6820. ; 257:6, s. 496-502
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare cardiovascular mortality and morbidity in middle-aged hypertensive men with initially nonhypertensive men derived from the same random population sample, and to study stroke morbidity in these men in relation to cardiovascular risk factors during 25-28 years of follow-up. DESIGN: Prospective, population-based observational study in men where the main intervention effort was directed towards treatment of hypertension in a special outpatient clinic. SUBJECTS AND METHODS: A total of 754 hypertensive men aged 47-55 years at screening were compared with 6740 men with normal blood pressure. The hypertensive men got stepped care treatment with either beta-blockers, thiazide diuretics, or combination treatment including vasodilating agents during the whole observational period. Data on cause-specific mortality and morbidity, and all cause mortality were obtained from patient files and the national registers on mortality and hospital admissions respectively. MAIN OUTCOME MEASURES: Baseline and change of cardiovascular risk factors during the first 15 years of follow-up and all cause mortality, and mortality and morbidity from stroke and coronary heart disease during 25-28 years. RESULTS: Treated hypertensive men had their blood pressure reduced with 21/15 mmHg during the first 5 years of the study and mean blood pressure levels were then rather constant. A minor reduction of serum cholesterol was also observed and a significant reduction in the prevalence of smoking. Treated hypertensive men suffered a substantial increased incidence of cardiovascular complications that escalated during the latter course of the study. Their total incidence of stroke was doubled; they had 50% more myocardial infarctions (MIs); mortality from coronary heart disease was doubled and all cause mortality was increased by a third, compared with nonhypertensive. In multiple regression analysis the incidence of stroke was significantly related to smoking and diabetes at entry and in time-dependent Cox's regression analysis it was significantly related only to smoking. There was no relationship observed between achieved systolic or diastolic blood pressure and the risk of stroke or MI nor was there any relationship between the change in blood pressure and such cardiovascular complications. CONCLUSION: In spite of a substantial reduction of their blood pressure, treated hypertensive middle-aged men had a highly increased risk of stroke, MI and mortality from coronary heart disease compared with nonhypertensive men of similar age. The increased risk of cardiovascular complications escalated during the latter course of the study.
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| 15. |
- Andersson, Anders, et al.
(författare)
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A transcriptional timetable of autumn senescence
- 2004
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 5:4, s. R24-
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Tidskriftsartikel (refereegranskat)abstract
- Background We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence. Results On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates. Conclusions We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.
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| 16. |
- Andersson, Bengt Olof, et al.
(författare)
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The reference step method for DC voltage at 1 mV and 10 mV
- 2014
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Ingår i: CPEM Digest (Conference on Precision Electromagnetic Measurements). - : Institute of Electrical and Electronics Engineers Inc.. - 9781479952052 ; , s. 520-521
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Konferensbidrag (refereegranskat)abstract
- We have investigated the performance of a method called the Reference Step Method at low voltage levels. The method has been evaluated earlier at voltage levels from 0.1 V to 1 kV with excellent results. The advantages of this method are that it uses commonly available equipment and can be fully automated. We have made comparisons with three other low-voltage methods and the differences show that the uncertainties can be less than 30 μV/V at 1 mV and 3 μV/V at 10 mV, making it possible to use this method to perform automated calibration of calibrators with sufficient accuracy for calibration of high-end instruments.
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| 17. |
- Andersson, Christin, et al.
(författare)
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Differential CSF biomarker levels in APOE-epsilon4-positive and -negative patients with memory impairment.
- 2007
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Ingår i: Dementia and geriatric cognitive disorders. - Basel : S. Karger AG. - 1420-8008 .- 1421-9824. ; 23:2, s. 87-95
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the relationships between episodic memory, APOE genotype, CSF markers (total tau, T-tau; phospho-tau, P-tau; beta-amyloid, Abeta42) and longitudinal cognitive decline. METHODS: 124 memory clinic patients were retrospectively divided into 6 groups based on (i) episodic memory function (Rey Auditory Verbal Learning Test, RAVLT): severe, moderate or no impairment (SIM, MIM or NIM), and (ii) APOE genotype (epsilon4+ or epsilon4-). CSF marker levels and cognitive decline were compared across groups. RESULTS: Episodic memory function, according to RAVLT scores, was significantly correlated with CSF marker levels only among epsilon4+ subjects and not among epsilon4- subjects. When comparing the 6 subgroups, SIM epsilon4+ and MIM epsilon4+ groups showed significantly lower Abeta42 levels than the other groups. T-tau and P-tau levels were significantly increased in SIM epsilon4+ when compared to all the other groups, including the SIM epsilon4- group. However, both SIM epsilon4+ and SIM epsilon4- declined cognitively during the follow-up. CONCLUSION: It remains to be determined whether APOE genotype affects the expression of biomarkers in CSF, or whether the different biomarker patterns reflect different types of disease processes in patients with progressive cognitive dysfunction.
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| 18. |
- Andersson, Christin, et al.
(författare)
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Identifying patients at high and low risk of cognitive decline using Rey Auditory Verbal Learning Test among middle-aged memory clinic outpatients
- 2006
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 21:4, s. 251-259
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate whether application of cutoff levels in an episodic memory test (Rey Auditory Verbal Learning Test, RAVLT) is a useful method for identifying patients at high and low risk of cognitive decline and subsequent dementia. METHODS: 224 patients with memory complaints (mean age = 60.7 years, mean MMSE = 28.2) followed-up at a memory clinic over approximately 3 years were assigned retrospectively to one of three memory groups from their baseline results in RAVLT [severe (SIM), moderate (MIM) or no impairment (NIM)]. These groups were investigated regarding cognitive decline. RESULTS: Patients assigned to SIM showed significant cognitive decline and progressed to dementia at a high rate, while a normal performance in RAVLT at baseline (NIM) predicted normal cognition after 3 years. Patients with MIM constituted a heterogeneous group; some patients deteriorated cognitively, while the majority remained stable or improved. CONCLUSIONS: The application of cutoff levels in RAVLT at baseline showed that patients with severely impaired RAVLT performance were at a high risk of cognitive decline and progression to dementia, while patients with normal RAVLT results did not show cognitive decline during 3 years. Furthermore, the initial degree of memory impairment was decisive in the cognitive prognosis 3 years later.
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| 19. |
- Andersson, Christin, et al.
(författare)
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Increasing CSF phospho-tau levels during cognitive decline and progression to dementia
- 2008
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 29:10, s. 1466-1473
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Little is known about longitudinal changes of cerebrospinal fluid (CSF) biomarkers during cognitive decline in neurodegenerative disease progression. OBJECTIVE: To investigate longitudinal changes in CSF biomarkers--total-tau (T-tau), phospho-tau (P-tau) and beta-amyloid (Abeta42)--during cognitive decline. METHODS: Forty memory clinic patients (47.5% females), aged 61.3+/-7.6 (S.D.) years, non-demented at baseline, underwent lumbar puncture and neuropsychological testing at two occasions. Baseline mean MMSE-score was 28.3+/-1.8. Patients were divided into three groups based on baseline memory functioning; severely impaired (SIM), moderately impaired (MIM) and no impairment (NIM). RESULTS: There was a significant increase in P-tau in the SIM-group during follow-up, while P-tau in MIM and NIM did not change. Eighty-three percent of the SIM-patients converted to dementia (80% AD), while most MIM- and NIM-patients remained non-demented. T-tau- and Abeta42-levels did not change in any of the memory groups during follow-up. CONCLUSION: Increasing P-tau levels during cognitive decline and conversion to dementia suggest that P-tau may be useful as a longitudinal marker of the neurodegenerative process.
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| 20. |
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| 21. |
- Andersson, Jens A, et al.
(författare)
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Intelligent debugger
- 1976
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Ingår i: Elteknik. - 0013-6425.
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Tidskriftsartikel (refereegranskat)
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| 22. |
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| 23. |
- Andersson, Lars, et al.
(författare)
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Dr Ulf Glendor has left us at age 71 OBITUARY
- 2020
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Ingår i: Dental Traumatology. - : John Wiley & Sons. - 1600-4469 .- 1600-9657. ; 36:3, s. 217-217
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 24. |
- Andersson, Magnus, et al.
(författare)
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A sticky chain model of the elongation and unfolding of escherichia coli P pili under stress
- 2006
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 90:5, s. 1521-1534
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Tidskriftsartikel (refereegranskat)abstract
- A model of the elongation of P pili expressed by uropathogenic Escherichia coli exposed to stress is presented. The model is based upon the sticky chain concept, which is based upon Hooke’s law for elongation of the layer-to-layer and head-to-tail bonds between neighboring units in the PapA rod and a kinetic description of the opening and closing of bonds, described by rate equations and an energy landscape model. It provides an accurate description of the elongation behavior of P pili under stress and supports a hypothesis that the PapA rod shows all three basic stereotypes of elongation/unfolding: elongation of bonds in parallel, the zipper mode of unfolding, and elongation and unfolding of bonds in series. The two first elongation regions are dominated by a cooperative bond opening, in which each bond is influenced by its neighbor, whereas the third region can be described by individual bond opening, in which the bonds open and close randomly. A methodology for a swift extraction of model parameters from force-versus-elongation measurements performed under equilibrium conditions is derived. Entities such as the free energy, the stiffness, the elastic elongation, the opening length of the various bonds, and the number of PapA units in the rod are determined.
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| 25. |
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| 26. |
- Andersson, Magnus, 1975-
(författare)
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Construction of force measuring optical tweezers instrumentation and investigations of biophysical properties of bacterial adhesion organelles
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optical tweezers are a technique in which microscopic-sized particles, including living cells and bacteria, can be non-intrusively trapped with high accuracy solely using focused light. The technique has therefore become a powerful tool in the field of biophysics. Optical tweezers thereby provide outstanding manipulation possibilities of cells as well as semi-transparent materials, both non-invasively and non-destructively, in biological systems. In addition, optical tweezers can measure minute forces (< 10-12 N), probe molecular interactions and their energy landscapes, and apply both static and dynamic forces in biological systems in a controlled manner. The assessment of intermolecular forces with force measuring optical tweezers, and thereby the biomechanical structure of biological objects, has therefore considerably facilitated our understanding of interactions and structures of biological systems. Adhesive bacterial organelles, so called pili, mediate adhesion to host cells and are therefore crucial for the initial bacterial-cell contact. Thus, they serve as an important virulence factor. The investigation of pili, both their biogenesis and their expected in vivo properties, brings information that can be of importance for the design of new drugs to prevent bacterial infections, which is crucial in the era of increased bacterial resistance towards antibiotics. In this thesis, an experimental setup of a force measuring optical tweezers system and the results of a number of biomechanical investigations of adhesive bacterial organelles are presented. Force measuring optical tweezers have been used to characterize three different types of adhesive organelles under various conditions, P, type 1, and S pili, which all are expressed by uropathogenic Escherichia coli. A quantitative biophysical force-extension model, built upon the structure and force response, has been developed. It is found, that this model describes the biomechanical properties for all three pili in an excellent way. Various parameters in their energy landscape, e.g., bond lengths and transition barrier heights, are assessed and the difference in behavior is compared. The work has resulted in a method that in a swift way allows us to probe different types of pili with high force and high spatial resolution, which has provided an enhanced understanding of the biomechanical function of these pili.
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| 27. |
- Andersson, Magnus, et al.
(författare)
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Dynamic Force Spectroscopy of E. coli P Pili
- 2006
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 91:7, s. 2717-2725
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Tidskriftsartikel (refereegranskat)abstract
- Surface organelles (so-called pili) expressed on the bacterial membrane mediate the adhesion of Escherichia coli causing urinary tract infection. These pili possess some extraordinary elongation properties that are assumed to allow a close bacterium-to-host contact even in the presence of shear forces caused by urine flow. The elongation properties of P pili have therefore been assessed for low elongation speeds (steady-state conditions). This work reports on the behavior of P pili probed by dynamic force spectroscopy. A kinetic model for the unfolding of a helixlike chain structure is derived and verified. It is shown that the unfolding of the quaternary structure of the PapA rod takes place at a constant force that is almost independent of elongation speed for slow elongations (up to ~0.4 μm/s), whereas it shows a dynamic response with a logarithmic dependence for fast elongations. The results provide information about the energy landscape and reaction rates. The bond length and thermal bond opening and closure rates for the layer-to-layer bond have been assessed to ~0.76 nm, ~0.8 Hz, and ~8 GHz, respectively. The results also support a previously constructed sticky-chain model for elongation of the PapA rod that until now had been experimentally verified only under steady-state conditions.
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| 28. |
- Andersson, Malin E, 1978, et al.
(författare)
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Signs of neuroaxonal injury in preeclampsia-A case control study.
- 2021
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral injury is a common cause of maternal mortality due to preeclampsia and is challenging to predict and diagnose. In addition, there are associations between previous preeclampsia and stroke, dementia and epilepsy later in life. The cerebral biomarkers S100B, neuron specific enolase, (NSE), tau protein and neurofilament light chain (NfL) have proven useful as predictors and diagnostic tools in other neurological disorders. This case-control study sought to determine whether cerebral biomarkers were increased in cerebrospinal fluid (CSF) as a marker of cerebral origin and potential cerebral injury in preeclampsia and if concentrations in CSF correlated to concentrations in plasma.CSF and blood at delivery from 15 women with preeclampsia and 15 women with normal pregnancies were analysed for the cerebral biomarkers S100B, NSE, tau protein and NfL by Simoa and ELISA based methods. MRI brain was performed after delivery and for women with preeclampsia also at six months postpartum.Women with preeclampsia demonstrated increased CSF- and plasma concentrations of NfL and these concentrations correlated to each other. CSF concentrations of NSE and tau were decreased in preeclampsia and there were no differences in plasma concentrations of NSE and tau between groups. For S100B, serum concentrations in preeclampsia were increased but there was no difference in CSF concentrations of S100B between women with preeclampsia and normal pregnancy.NfL emerges as a promising circulating cerebral biomarker in preeclampsia and increased CSF concentrations point to a neuroaxonal injury in preeclampsia, even in the absence of clinically evident neurological complications.
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| 29. |
- Andersson, Martin E, et al.
(författare)
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Structural and mutational studies of the carboxylate cluster in iron-free ribonucleotide reductase R2.
- 2004
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Ingår i: Biochemistry. - 0006-2960. ; 43:24, s. 7966-72
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Tidskriftsartikel (refereegranskat)abstract
- The R2 protein of ribonucleotide reductase features a di-iron site deeply buried in the protein interior. The apo form of the R2 protein has an unusual clustering of carboxylate side chains at the empty metal-binding site. In a previous study, it was found that the loss of the four positive charge equivalents of the diferrous site in the apo protein appeared to be compensated for by the protonation of two histidine and two carboxylate side chains. We have studied the consequences of removing and introducing charged residues on the local hydrogen-bonding pattern in the region of the carboxylate cluster of Corynebacterium ammoniagenes and Escherichia coli protein R2 using site-directed mutagenesis and X-ray crystallography. The structures of the metal-free forms of wild-type C. ammoniagenes R2 and the mutant E. coli proteins D84N, S114D, E115A, H118A, and E238A have been determined and their hydrogen bonding and protonation states have been structurally assigned as far as possible. Significant alterations to the hydrogen-bonding patterns, protonation states, and hydration is observed for all mutant E. coli apo proteins as compared to wild-type apo R2. Further structural variations are revealed by the wild-type apo C. ammoniagenes R2 structure. The protonation and hydration effects seen in the carboxylate cluster appear to be due to two major factors: conservation of the overall charge of the site and the requirement of electrostatic shielding of clustered carboxylate residues. Very short hydrogen-bonding distances between some protonated carboxylate pairs are indicative of low-barrier hydrogen bonding.
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| 30. |
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| 31. |
- Andersson, Magnus, et al.
(författare)
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Force measuring optical tweezers system for long time measurements of P pili stability
- 2006
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Ingår i: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV. - : SPIE. - 081946130X - 9780819461308 ; , s. 608810-
-
Konferensbidrag (refereegranskat)abstract
- A force-measuring optical tweezers instrumentation and long time measurements of the elongation and retraction of bacterial fimbriae from Uropathogenic E. coli (UPEC) under strain are presented. The instrumentation is presented in some detail. Special emphasis is given to measures taken to reduce the influence of noise and drifts in the system and from the surrounding, which makes long term force measurements possible. Individual P pili from UPEC bacteria were used as a biological model system for repetitive unfolding and refolding cycles of bacterial fimbriae under equilibrium conditions. P pili have evolved into a three-dimensional helix-like structure, the PapA rod, that can be successively and significantly elongated and/or unfolded when exposed to external forces. The instrumentation is used for characterization of the force-vs.-elongation response of the PapA rod of individual P pili, with emphasis on the long time stability of the forced unfolding and refolding of the helical structure of the PapA rod. The results show that the PapA rod is capable of withstanding extensive strain, leading to a complete unfolding of the helical structure, repetitive times during the life cycle of a bacterium without any noticeable alteration of the mechanical properties of the P pili. This function is believed to be importance for UPEC bacteria in vivo since it provides a close contact to a host cell (which is an initial step of invasion) despite urine cleaning attempts.
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| 32. |
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| 33. |
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| 34. |
- Andersson, Magnus, et al.
(författare)
-
Physical Properties of Biopolymers Assessed by Optical Tweezers : Analysis of folding and refolding of bacterial pili
- 2008
-
Ingår i: ChemPhysChem. - : Wiley-VCH Verlagsgesellschaft. - 1439-4235 .- 1439-7641. ; 9:2, s. 221-235
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial adhesion to surfaces mediated by specific adhesion organelles that promote infections, as exemplified by the pili of uropathogenic E. coli, is studied mostly at the level of cell-cell interactions and thereby reflects the averaged behavior of multiple pili. The role of pilus rod structure has therefore only been estimated from the outcome of experiments involving large numbers of organelles at the same time. It has, however, lately become clear that the biomechanical behavior of the pilus shafts play an important, albeit hitherto rather unrecognized, role in the adhesion process. For example, it has been observed that shafts from two different strains, even though they are similar in structure, result in large differences in the ability of the bacteria to adhere to their host tissue. However, in order to identify all properties of pilus structures that are of importance in the adhesion process, the biomechanical properties of pili must be assessed at the single-molecule level. Due to the low range of forces of these structures, until recently it was not possible to obtain such information. However, with the development of force-measuring optical tweezers (FMOT) with force resolution in the low piconewton range, it has lately become possible to assess forces mediated by individual pili on single living bacteria in real time. FMOT allows for a more or less detailed mapping of the biomechanical properties of individual pilus shafts, in particular those that are associated with their elongation and contraction under stress. This Mi- nireview presents the FMOT technique, the biological model system, and results from assessment of the biomechanical properties of bacterial pili. The information retrieved is also compared with that obtained by atomic force microscopy.
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| 35. |
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| 36. |
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| 37. |
- Andersson, Ove, et al.
(författare)
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A high-pressure study of PMMA-based gels with and without TiO2 nano-particle filler: a filler induced change in the activation volume
- 2005
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 50:16-17, s. 3217-3223
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Tidskriftsartikel (refereegranskat)abstract
- The ionic conductivity σ of PMMA-based gels with and without nano-particle filler has been investigated at elevated pressure up to 0.9 GPa and in the temperature range 220-330 K to determine the effect of pressure and to obtain the activation volume. Both gels had molar ratios: EC:PC:LiClO 4 :PMMA 53.9:22:5.2:18.9, and one gel contained 8 wt.% TiO 2 nano-particles. At room temperature and atmospheric pressure, the conductivity of the gel with filler is almost the same as that for the gel without filler. At increasing pressure p, σ(p) for both gels exhibits an abrupt change, which is associated with a transition, and consequently there is a pressure induced change in the activation volume for both gels. The activation volume ΔV * in low-pressure state is the same for the gels with and without filler and about 14 cm 3 mol -1 at room temperature, which is typical liquid-like behaviour. In the high-pressure state, ΔV * = 42 and 45.3 cm 3 mol -1 at 294 K for the gels with and without filler, respectively. The results show that the ionic movements are restricted by the rigid environment of the high-pressure state and that the filler affects ΔV * under this condition. In particular, the filler appears to improve the cation transport number as a results of a decreased mobility of large-sized ions in the rigid environment of the high-pressure state. © 2004 Elsevier Ltd. All rights reserved.
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| 38. |
- Andersson, Ove, et al.
(författare)
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A low-temperature high-pressure apparatus with a temperature control system
- 1992
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Ingår i: High Pressure Research. - : Informa UK Limited. - 0895-7959 .- 1477-2299. ; 10:4, s. 599-606
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Tidskriftsartikel (refereegranskat)abstract
- A low-temperature high-pressure apparatus was designed using commercial cryogenic equipment. Pressures up to 1 GPa and temperatures down to 40 K can be obtained in a volume of up to 30 cm3. The apparatus is of the piston-cylinder type with a piston diameter of 45 mm, and the pressure can be varied at all temperatures, An adaptive temperature control system keeps the temperature inside the pressure cylinder constant to within ±0.1 K.
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| 39. |
- Andersson, Ove, et al.
(författare)
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A Second Glass Transition in Pressure Collapsed Type II Clathrate Hydrates
- 2018
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:15, s. 4376-4384
-
Tidskriftsartikel (refereegranskat)abstract
- Type II clathrate hydrates (CHs) M-17 H2O, with M = tetrahydrofuran (THF) or 1,3-dioxolane, are known to collapse, or amorphize, on pressurization to similar to 1.3 GPa in the temperature range 77-140 K. On heating at 1 GPa, these pressure-amorphized CH states show a weak, stretched sigmoid-shaped, heat-capacity increase because of a glass transition. Here we use thermal conductivity and heat capacity measurements to show that also type II CH with M = cyclobutanone (CB) collapses on isothermal pressurization and undergoes a similar, weak, glass transition upon heating at 1 GPa. Furthermore, we reveal for both THF CH and CB CH a second, much more pronounced, glass transition at temperatures above the thermally weak glass transition on heating in the 0.2-0.7 GPa range. This result suggests the general occurrence of two glass transitions in water-rich (94 mol %) pressure-collapsed CHs. Because of a large increase in dielectric permittivity concurrently as the weak heat capacity increase, the first glass transition must be due to kinetic unfreezing of water molecules. The thermal features of the second glass transition, measured on isobaric temperature cycling, are typical of a glass liquid glass transition, which suggests that pressure-amorphized CHs transform reversibly to liquids.
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| 40. |
- Andersson, Ove, et al.
(författare)
-
Amorphous-like thermal conductivity and high mechanical stability of cyclopentane clathrate hydrate
- 2024
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 26:22, s. 16017-16025
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity κ of cyclopentane clathrate hydrate (CP CH) of type II was measured at temperatures down to 100 K and at pressures up to 1.3 GPa. The results show that CP CH displays amorphous-like κ characteristic of many crystalline clathrate hydrates, e.g., tetrahydrofuran (THF) CH. The magnitude of κ is 0.47 W m−1 K−1 near the melting point of 280 K at atmospheric pressure, and it is almost independent of pressure and temperature T: ln κ = −0.621−40.1/T at atmospheric pressure (in SI-units). This is slightly less than κ of type II CHs of water-miscible solvents such as THF. Intriguingly, unlike other water-rich type II clathrate hydrates of water-miscible molecules M (M·17 H2O), CP CH does not amorphize at pressures up to 1.3 GPa at 130 K and also remains stable up to 0.5 GPa at 240 K. This shows that CP CH is mechanically more stable than the previously studied water-rich type II CHs, and suggests that repulsive forces between CP and the H2O cages increase the mechanical stability of crystalline CP CH. Moreover, we show that κ of an ice-CH mixture, which often arises for CHs that form naturally, is described by the average of the parallel and series heat conduction models to within 5% for ice contents up to 22 wt%. The findings provide a better understanding of the thermal and stability properties of clathrate hydrates for their applications such as gas storage compounds.
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| 41. |
- Andersson, Ove, et al.
(författare)
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An ice phase of lowest thermal conductivity
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:20, s. 9612-9617
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Tidskriftsartikel (refereegranskat)abstract
- On pressurizing at temperatures near 130 K, hexagonal and cubic ices transform implosively at 0.8–1 GPa. The phase produced on transformation has the lowest thermal conductivity among the known crystalline ices and its value decreases on increase in temperature. An ice phase of similar thermal conductivity is produced also when high-density amorphous ice kept at 1 GPa transforms on slow heating when the temperature reaches ∼155 K. These unusual formation conditions, the density and its distinguished thermal conductivity, all indicate that a distinct crystal phase of ice has been produced.
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| 42. |
- Andersson, Ove, et al.
(författare)
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Chirality and the thermophysical properties of molecular solid phases under pressure: (+)- and (±)-camphor
- 1990
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Ingår i: Molecular Physics. - : Taylor & Francis Group. - 0026-8976 .- 1362-3028. ; 70:6, s. 1065-1083
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal conductivity λ, heat capacity per unit volume pcP and P-T phase diagrams are investigated for both (+)- and (±)-camphor. The transient hotwire method is used at temperatures in the range 100–430 K and at pressures up to 1·75 GPa. We detect solid phases I-IV for (+)-camphor and I′-V′ for (±)-camphor. We conclude that λ is independent of enantiomeric composition for plastic-crystal phase pairs I-I′, II-II′ and IV-IV′. Phase V′ also appears to be a plastic-crystal phase. Non-plastic phases III and III′ show a variation of λ with T that differ considerably from that expected for a simple crystal, with the greatest such difference being observed for the racemic compound III′. An unannealed specimen of the racemic compound III′ is probably chirally disordered and shows a variation of λ with T for T < 130 K, which may indicate phonon-assisted fracton hopping.
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| 43. |
- Andersson, Ove, et al.
(författare)
-
Collapse of an ice clathrate under pressure observed via thermal conductivity measurements
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 78, s. 174201-
-
Tidskriftsartikel (refereegranskat)abstract
- Irreversible transformation of the tetrahydrofuran ice clathrate at 130 K was studied by measuring thermal conductivity k with increase in pressure p. Initially, k increases slowly with p up to 0.75 GPa where it levels off, is roughly constant up to 0.95 GPa, then decreases up to 1.05 GPa. Pressure collapses the clathrate structure, plausibly beginning with lattice distortion, and k increases at 1.05 GPa in a sharp sigmoid-shape manner due to large densification until the transformation is complete at 1.25 GPa. This is the opposite of that found for ice whose k decreases first slowly with increase in p and then rapidly in an inverted sigmoidshape manner [O. Andersson and H. Suga, Phys. Rev. B 65, 140201 (2002)]. At 1.08 GPa and 131 K, k increases with time t (s) according to exp(t /2945), which is also the opposite of the collapse of ice [G. P. Johari and O. Andersson, Phys. Rev. B 70, 184108 (2004)]. The difference in its behavior is attributed to strong phonon scattering from the tetrahydrofuran guest molecules. k of the collapsed clathrate is 30% less than that for the collapsed ice, which is comparable with the 25% lesser k of the tetrahydrofuran-water solution from k of water at ambient pressure. On depressurizing at 130 K, k decreases progressively more rapidly and k of the collapsed state at 0.3 GPa is slightly lower than that of the as-made clathrate, showing that its original structure is not recovered.
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| 44. |
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| 45. |
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| 46. |
- Andersson, Ove
(författare)
-
Dielectric relaxation of the amorphous ices
- 2008
-
Ingår i: Journal of Physics. - : Institute of Physics (IOP). - 0953-8984 .- 1361-648X. ; 20
-
Tidskriftsartikel (refereegranskat)abstract
- The dielectric properties of the low and high density amorphous ices are discussed in terms of those for supercooled water and crystalline ices, and also used to evaluate the transition behaviour upon pressure cycling at 130 K. The dielectric relaxation of the high density amorphous ice is described well by the symmetrical Cole–Cole function with an almost pressure independent relaxation time τ ∼ 2 s at 133 K and a relaxation time distribution factor of 0.7. At the high to low density amorphous ice transition, the dielectric relaxation time increases by about two orders of magnitude despite a ∼30% decrease in density, and τ of the low density amorphous ice is in the range 102–103 s at 130 K. The relaxation time behaviour of the high density amorphous ice is similar to that of supercooled liquid water, whereas τ of the low density amorphous ice appears to be prolonged by the ice rules, in correspondence to that of the crystalline ices.
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| 47. |
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| 48. |
- Andersson, Ove, et al.
(författare)
-
Effect of pressure on thermal conductivity and pressure collapse of ice in a polymer-hydrogel and kinetic unfreezing at 1 GPa
- 2011
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 134:12, s. 124903-
-
Tidskriftsartikel (refereegranskat)abstract
- We report a study of aqueous solutions of poly(vinylalcohol) and its hydrogel by thermal conductivity,κ, and specific heat measurements. In particular, we investigate (i) the changes in the solution and the hydrogel at 0.1 MPa observed in the 350-90 K range and of the frozen hydrogel at 130 K observed in the range from 0.1 MPa to 1.3 GPa, and (ii) the nature of the pressure collapse of ice in the frozen hydrogel and kinetic unfreezing on heating of its high density water at 1 GPa. The water component of the polymer solution on cooling either first phase separates and then freezes to hexagonal ice or freezes without phase separation and the dispersed polymer chains freeze-concentrate in nanoscopic and microscopic regions of the grain boundaries and grain junctions of the ice crystals in the frozen state of water in the hydrogel. The change in κ with temperature at 1 bar is reversible with some hysteresis, but not reversible with pressure after compression to 0.8 GPa at 130 K. At high pressures the crystallized state collapses showing features of. and specific heat characteristic of formation of high density amorphous solid water. The pressure of structural collapse is 0.08 GPa higher than that of ice at 130 K. The slowly formed collapsed state shows kinetic unfreezing or glass-liquid transition temperature at 140 K for a time scale of 1 s. Comparison with the change in the properties observed for ice shows that κ decreases when the polymer is added.
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| 49. |
- Andersson, Ove, et al.
(författare)
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Effects of pressure and temperature on the thermal conductivity of Sn2P2S6
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 83:13
-
Tidskriftsartikel (refereegranskat)abstract
- The thermal conductivity kappa of the ferroelectric, paraelectric, and incommensurate phases of polycrystalline Sn2P2S6 has been measured in the 0.1-0.7 GPa range. The thermal conductivity kappa of the ferroelectric phase decreases with increasing pressure p. This unusual behavior, which is found in only a few other phases, is attributed to a negative Gruneisen parameter. The temperature T dependence of kappa for the ferroelectric phase (kappa similar to T-1) is well described by the Debye model for kappa, with three-phonon Umklapp scattering serving as the dominant scattering mechanism near and above the Debye temperature (similar to 100 K) up to a few tenths of degrees below the ferro- to paraelectric phase transition, where kappa(T) gradually changes and becomes temperature independent upon further heating. The thermal conductivity of the paraelectric and incommensurate phases was temperature independent and indistinguishable. Possible causes for the unusually weak T dependence at high temperatures and implications of the p dependence of kappa are discussed.
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| 50. |
- Andersson, Ove, et al.
(författare)
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Evidence suggesting kinetic unfreezing of water mobility in two distinct processes in pressure-amorphized clathrate hydrates
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 24:34, s. 20064-20072
-
Tidskriftsartikel (refereegranskat)abstract
- Type II clathrate hydrates (CHs) with tetrahydrofuran (THF), cyclobutanone (CB) or 1,3-dioxolane (DXL) guest molecules collapse to an amorphous state near 1 GPa on pressurization below 140 K. On subsequent heating in the 0.2-0.7 GPa range, thermal conductivity and heat capacity results of the homogeneous amorphous solid show two glass transitions, first a thermally weak glass transition, GT1, near 130 K; thereafter a thermally strong glass transition, GT2, which implies a transformation to an ultraviscous liquid on heating. Here we compare the GTs of normal and deuterated samples and samples with different guest molecules. The results show that GT1 and GT2 are unaffected by deuteration of the THF guest and exchange of THF with CB or DXL, whereas the glass transition temperatures (Tgs) shift to higher temperatures on deuteration of water; Tg of GT2 increases by 2.5 K. These results imply that both GTs are associated with the water network. This is corroborated by the fact that GT2 is detected only in the state which is the amorphized CH's counterpart of expanded high density amorphous ice. The results suggest a rare transition sequence of an orientational glass transition followed by a glass to liquid transition, i.e., kinetic unfreezing of H2O reorientational and translational mobility in two distinct processes.
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