Elisabeth Hansen

The isotropic-nematic interface in suspensions of Na-fluorohectorite synthetic clay.

Colloidal suspensions of Na-fluorohectorite synthetic clay platelets in saline water exhibit coexisting isotropic and nematic phases, due to gravitational separation of the polydisperse particles. We study the ordering of the platelets at the interfaces between various coexisting phases. Four different experimental techniques are employed: visual observation of birefringence, synchrotron wide angle and small-angle X-ray scattering, and magnetic resonance imaging. We find that at the narrow isotropic sol-nematic sol interface the platelets are lying horizontally, i.e. with their mean platelet normal along the vertical direction. The experiments indicate that the platelets align homeotropically both at the isotropic sol-nematic sol interface and at the nematic sol-wall interface. We further investigate the complex alignment effect of a horizontally applied magnetic field in the nematic sol, and we compare it with the adjacent nematic gel.

Swelling transition of a clay induced by heating.

Clays are of paramount importance for soil stability, but also in applications ranging from oil recovery to composites and hydrogels. Generically, clays are divided into two subclasses: macroscopically swelling, ‘active’ clays that have the capacity for taking up large amounts of water to form stable gels, and ‘passive’ or non-swelling clays; the former stabilize soils whereas the latter are known to lead to landslides. However, it has been unclear so far what mechanisms underlie clay swelling. Here, we report the first observation of a temperature-induced transition from a passive to an active, swelling clay. We propose a simple description of the swelling transition; while net attractive interactions are dominant at low temperatures so that the clay particles remain attached to each other in stacks, at higher temperatures it is energetically favourable for the clay to swell due to the entropy that is gained by counterions which are liberated during swelling.

X-ray Studies of Carbon Dioxide Intercalation in Na-Fluorohectorite Clay at Near-Ambient Conditions

We show experimentally that gaseous CO(2) intercalates into the interlayer space of the synthetic smectite clay Na-fluorohectorite at conditions not too far from ambient. The mean interlayer repetition distance of the clay when CO(2) is intercalated is found to be 12.5 Å for the conditions -20 °C and 15 bar. The magnitude of the expansion of the interlayer upon intercalation is indistinguishable from that observed in the dehydrated-monohydrated transition for H(2)O, but the possibility of water intercalation is ruled out by a careful analysis of the experimental conditions and repeating the measurements exposing the clay to nitrogen gas. The dynamics of the process is observed to be dependent on the pressure, with a higher intercalation rate at increased pressure. The rate of CO(2) intercalation at the studied conditions is found to be several orders of magnitude slower than the intercalation rate of water or humidity at ambient pressure and temperature.

INSULIN SENSITIVITY AFTER MAXIMAL AND ENDURANCE RESISTANCE TRAINING

Hansen, E, Landstad, BJ, Gundersen, KT, Torjesen, PA, and Svebak, S. Insulin sensitivity after maximal and endurance resistance training. J Strength Cond Res 26(2): 327–334, 2012—The purpose of the study was to compare the effects of maximal resistance training (MRT) vs. endurance resistance training (ERT) on improvements in insulin levels and glucose tolerance in overweight individuals at risk of developing type 2 diabetes. Eighteen participants with baseline values suggesting impaired glucose tolerance were randomly assigned to 1 of 2 groups. Group 1 engaged in supervised MRT (Bernstein inverted pyramid system: 5 × 3–4, 60–85% 1 repetition maximum [1RM]), 3 d·wk−1 over 4 months, whereas members of group 2 acted as controls. Later, group 2 engaged in supervised ERT (3 × 12–15, 45–65% 1RM), 3 d·wk−1 over a 4 month period with the 2 prebaselines as controls. Both interventions consisted of 8 exercises that included the entire body. Glucose (fasting and 2-hour test), insulin and C-peptide measures were assessed from pre to post in both groups. The MRT led to reduced blood levels of 2-hour glucose (p = 0.044) and fasting C-peptide (p = 0.023) and decreased insulin resistance (p = 0.040). The ERT caused a significant reduction in the blood levels of insulin (p = 0.023) and concomitant positive effects on % insulin sensitivity (p = 0.054) and beta-cell function (p = 0.020). The findings indicate that both MRT and ERT lead to decreased insulin resistance in people with a risk of developing type 2 diabetes; MRT led to a greater increase in glucose uptake capacity (in muscles), whereas ERT led to greater insulin sensitivity, supporting the recommendation of both MRT and ERT as primary intervention approaches for individuals at a risk of developing type 2 diabetes.

Motivation for lifestyle changes to improve health in people with impaired glucose tolerance

AIM To identify factors that could have motivational significance for lifestyle change to facilitate the reduction of Impaired Glucose Tolerance (IGT) and, consequently, the risk of having type 2 diabetes. METHODS Eighteen people living in a municipality in central Norway participated in the study. A large-scale public health screening study had defined them as people with IGT. The participants took part in a semi-structured interview that focused on four aspects of everyday lifestyle: (1) structure and rhythm, (2) physical health, (3) physical activity and (4) social relations. RESULTS The interviews showed that the participants in the study changed their priorities regarding daily living. Results indicated four domains of motivational factors that appeared as significant for lifestyle changes. The participants attributed great significance to their physical health and were strongly motivated to prevent disease development by improvement of everyday structure and rhythm, reduction of sickness risk, activity level and social relation. Research indicates, however, that lasting lifestyle changes take time and that health care support must be adapted to the individual in light of their social setting. CONCLUSION Persons with IGT appear to benefit from lifestyle changes along four dimensions of motivational significance: Structure and rhythm, Sickness concerns, Activity levels, Social relations. This means that attention needs to be more carefully tailored the individual along these four dimensions than has been the case in traditional health care.

Cultural activity participation and associations with self-perceived health, life-satisfaction and mental health: the Young HUNT Study, Norway

BackgroundLeisure time activities and culture participation may have health effects and be important in pulic health promotion. More knowledge on how cultural activity participation may influence self-perceived health, life-satisfaction, self-esteem and mental health is needed.MethodsThis article use data from the general population-based Norwegian HUNT Study, using the cross-sectional Young-HUNT3 (2006–08) Survey including 8200 adolescents. Data on cultural activity participation, self-perceived health, life-satisfaction, self-esteem, anxiety and depression were collected by self-reported questionnaires.ResultsBoth attending meetings or training in an organisation or club, and attending sports events were positively associated with each of the health parameters good self-percieved health, good life-satisfaction, good self-esteem, and low anxiety and depression symptoms. We found differences according to gender and age (13–15 years versus 16–19 years old) for several culture activities, where girls aged 16–19 years seemed to benefit most from being culturally active. The extent of participation seemed to matter. Those who had frequent participation in cultural activities reported better health outcomes compared to inactive adolecents.ConclusionsThe results from this study indicate that participation in cultural activities may be positively associated with health, life-satisfaction and self-esteem in adolescents and thus important in public health promotion. Possible sex and age differences should be taken into account.

The relative importance of aerobic capacity, physical activity and body mass index in impaired glucose tolerance and Type 2 diabetes

Aim To investigate the relative importance of aerobic capacity, physical activity and body mass index (BMI) for discriminating between people with Impaired Glucose Tolerance (IGT) or Type 2 diabetes and healthy controls. Methods Variables included scores on estimated VO2-max (ml/kg/min) by walking the UKK walking-test, responses to questions on self-reported physical activity and BMI. Design Participants were recruited into groups of IGT, Type 2 diabetes and healthy controls (N=64). Statistical analyses were performed by multifactor ANOVA, bivariate correlations and logistic regression. Results Obesity, as indicated by BMI, was most evident in the IGT and Type 2 diabetes groups when jointly compared with the healthy controls (p=0.004, OR ≥ 16.00). However, when separately compared with the healthy controls, BMI scores strongly discriminated between the IGT versus healthy controls but failed to distinguish between Type 2 diabetes and healthy controls. Scores for aerobic capacity and level of physical activity failed to distinguish between healthy controls and IGT as well as Type 2 diabetes status. Conclusion BMI was significantly associated with IGT whereas aerobic capacity and level of physical activity were not predictive of group status for IGT and Type 2 diabetes. The results indicated that primary health care should focus on all means for weight reduction, including physical activity and other life style changes, in order to prevent individuals from escalating into IGT in order to prevent risk of Type 2 diabetes.

Mueller matrix imaging of nematic textures in colloidal dispersions of Na-fluorohectorite synthetic clay

A Mueller Matrix Imaging Ellipsometer system is operated in transmission and used to study nematic textures in colloidal dispersions of synthetic Na-fluorohectorite clay platelets in solution. It is clearly observed that the anisometric particles organize into phases with strong birefringence, which results in a strong retardance. The Mueller matrix imaging technique supplies an image of the retardance matrix, even in the presence of other effects such as light scattering and diattenuation. The spatial variation of the absolute value of the retardance, the orientation of the fast axis of the retardance, the total diattenuation and the orientation of the diattenuation are presented. In particular, from knowledge of the anisotropic shape of the particles, the orientation of the particles within ordered domains, and the density of the particles within the domains are spatially determined. The experiments are based on adding synthetic clay particles into a solution contained in a thin rectangular glass container. Upon letting gravitation act on the sample, different phases appear after a few weeks. One phase contains nematic textures and we are able to determine the ordering and also estimate the density of the domains/texture within the phase, in addition to estimating the local order within a domain with an image resolution of 12 μm.

Motivation for Life Style Changes to Improve Health in People with Impaired Glucose Tolerance

RESULTS One third reported being the initiator of the planning process and 60% assessed that they had an essential role in the process. The role of medical doctors was also regarded important, but collaboration with other professionals was rare. Although 40 % were highly satisfi ed with the planning process, need for more individual solutions, comprehensiveness and use of wider expertise was regarded important. Of those who regarded their own role essential in the process 41% (vs. 27 %) felt that rehabilitation was organized very well and according to their personal needs and wishes and 50% (vs. 37%) felt that rehabilitation helped extremely signifi cantly to realize their own life goals.