Investigation of the postcure reaction and surface energy of epoxy resins using time-of-flight secondary ion mass spectrometry and contact-angle measurements

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to investigate correlations between the molecular changes and postcuring reaction on the surface of a diglycidyl ether of bisphenol A and diglycidylether of bisphenol F based epoxy resin cured with two different amine-based hardeners. The aim of this work was to present a proof of concept that ToF-SIMS has the ability to provide information regarding the reaction steps, path, and mechanism for organic reactions in general and for epoxy resin curing and postcuring reactions in particular. Contact-angle measurements were taken for the cured and postcured epoxy resins to correlate changes in the surface energy with the molecular structure of the surface. Principal components analysis (PCA) of the ToFSIMS positive spectra explained the variance in the molecular information, which was related to the resin curing and postcuring reactions with different hardeners and to the surface energy values. The first principal component captured information related to the chemical phenomena of the curing reaction path, branching, and network density based on changes in the relative ion density of the aliphatic hydrocarbon and the C₇H₇O⁺ positive ions. The second principal component captured information related to the difference in the surface energy, which was correlated to the difference in the relative intensity of the C_xH_yN_z⁺ ions of the samples. PCA of the negative spectra provided insight into the extent of consumption of the hardener molecules in the curing and postcuring reactions of both systems based on the relative ion intensity of the nitrogen-containing negative ions and showed molecular correlations with the sample surface energy.

Electrowetting measurements with mercury showing mercury/mica interfacial energy depends on charging

We demonstrate that the interfacial energy between mercury and mica is a function of charge on the mercury surface, decreasing with increasing positive charge. The contact angle of mercury on mica has been measured as a function of potential applied to the mercury, which forms the working electrode of a cell containing either KC1 or NaF electrolyte solution. At high negative applied potentials, a stable aqueous film exists between the mercury and mica surface. As potential is made less negative, the film collapses and mercury partial1 wets the mica at a critical potential, close to the electrocapillary maximum. Upon increasing the potential further (making the Hg surface more and more positive), the contact angle measured within the mercury continually decreases. Electrowetting with mercury is not unexpected since its interfacial tension with the aqueous phase is known to be a function of applied potential. However, the observed decrease goes against the trend expected from the Young equation if only this effect is considered. To explain the data we must allow the mercury/mica interfacial tension also to vary with applied potential. This variation indicates that the mercury surface is positively charged by contact with mica, consistent with known contact electrification between these two materials. The inherent charges at the mercury interfaces with mica and electrolyte solution result in contact angle changes of some tens of degrees with a change in applied potential of half a volt orders of magnitude less than the potentials required to effect comparable changes in other electrowetting systems.

Effects of beacon administration on energy expenditure and substrate utilisation in Psammomys obesus (Israeli sand rats)

Objective: To investigate whether beacon administration affects substrate utilisation, physical activity levels or energy expenditure in Psammomys obesus. Design: Pairs of age- and sex-matched Psammomys obesus were randomly assigned to either beacon-treated (15 µg/day for 7 days (i.c.v.)) or control (i.c.v. saline) groups. Measurements: Indirect calorimetry on day 0 and day 7 to measure oxygen consumption and carbon dioxide production, which were used to calculate fat oxidation, carbohydrate oxidation and total energy expenditure. Physical activity in the calorimeter was measured using an infrared beam system. Food intake and body weight were measured daily. Results: The administration of beacon significantly increased body weight compared to saline-treated control animals. This body weight gain was primarily due to increased body fat content. Average daily food intake tended to be higher in beacon-treated Psammomys obesus, but no effect of beacon administration on substrate oxidation, activity or energy expenditure was detected. Conclusion: The effects of beacon on body weight are due to increased food intake, with no detectable effect on nutrient partitioning, physical activity or energy expenditure.

Operating experiences with an advanced fabric energy storage system in Australia

Despite their proven track record in the cold climate countries of northern Europe, there are no reports in the research literature of experiences using advanced fabric energy storage (FES) systems in countries where cooling rather than heating is the main priority. This paper reports some of the experiences with the first known advanced FES system in Australia made over the first full calendar .year of operation. It is located in a three storey building on a university campus in Victoria and has been in operation since mid-2002. Temperature, energy use and operational mode data were recorded during 2003. Airflow measurements through the FES have been made in five areas of the building. On-going operating problems still exist with the system and this has prevented a conclusive evaluation of its suitability for the southern Australian climate.

Dietary intake measurements

To provide a concise summary of field and laboratory methods for the measurement of dietary intake with particular reference to the assessment of energy and protein intake and to the pitfalls and difficulties that may be encountered in practice when implementing the methods both in the field and under laboratory conditions.

Location based power control for energy critical sensors in a disconnected network

This paper provides a location based power control strategy for disconnected sensory nodes deployed for long term service. Power conservation is of importance particularly when sensors communicate with a mobile robot used for data collection. The proposed algorithm uses estimations from a Robust Extended Kalman Filter (REKF) with RSSI measurements, in implementing a sigmoid function based power control algorithm which essentially approaches a desired power emission trajectory based on carrier-to-interference ratios(CIR) to ensure interferenceless reception. The more realistic modelling we use incorporates physical dynamics between the mobile robot and the sensors together with the wireless propagation parameters between the transmitter and receiver to formulate a sophisticated and effective power control strategy for the exclusive usage of energy critical disconnected nodes in a sensory network increasing their life span.

Energy expenditure and the body cell mass in Cystic Fibrosis

Poor nutritional status in patients with cystic fibrosis (CF) is associated with severe lung disease, and possible causative factors include inadequate intake, malabsorption, and increased energy requirements. Body cell mass (which can be quantified by measurement of total body potassium) provides an ideal standard for measurements of energy expenditure. The aim of this study was to compare resting energy expenditure (REE) in patients with CF with both predicted values and age-matched healthy children and to    determine whether REE was related to either nutritional status or pulmonary function. REE was measured by indirect calorimetry and body cell mass by scanning with total body potassium in 30 patients with CF (12 male, mean AGE = 13.07 ± 0.55 y) and 18 healthy children (six male, mean AGE = 12.56 ± 1.25 y). Nutritional status was expressed as a percentage of predicted total body potassium. Lung function was measured in the CF group by spirometry and expressed as the percentage of predicted forced expiratory volume in 1 s. Mean REE was significantly increased in the patients with CF compared with healthy children (119.3 ± 3.1% predicted versus 103.6 ± 5% predicted, P < 0.001) and, using multiple regression techniques, REE for total body potassium was significantly increased in patients with CF (P = 0.0001). There was no relation between REE and nutritional status or pulmonary disease status in the CF group. In conclusion, REE is increased in children and adolescents with CF but is not directly related to nutritional status or pulmonary disease.

Energy use and thermal comfort in a rammed earth office building

A two-storey rammed earth building was built on the Thurgoona Campus of Charles Sturt University in Albury-Wodonga, Australia, in 1999. The building is novel both in the use of materials and equipment for heating and cooling. The climate at Wodonga can be characterised as hot and dry, so the challenge of providing comfortable working conditions with minimal energy consumption is considerable. This paper describes an evaluation of the building in terms of measured thermal comfort and energy use. Measurements, confirmed by a staff questionnaire, found the building was too hot in summer and too cold in winter. Comparison with another office building in the same location found that the rammed earth building used more energy for heating. The thermal performance of three offices in the rammed earth building was investigated further using simulation to predict office temperatures. Comparisons were made with measurements made over typical weeks in summer and winter. The validated model has been used to investigate key building parameters and strategies to improve the thermal comfort and reduce energy consumption in the building. Simulations showed that improvements could be made by design and control strategy changes.

Objective and subjective measurements of office meeting rooms

This research is a preliminary investigation of the objective measurements ofthelmal comfort and C02 levels as well as subjective user evaluation surveys in six meeting rooms. The ongoing objective measurements were taken via thelmal comfort carts while the surveys evaluated parameters of temperature, lighting, air quality, meeting effectiveness etc. The outcomes are of particular interest since some of the objective measurements clearly to not support those of the users. In fact, the investigation has triggered off further interest in refining questionnaires to develop more precise indicators of 'discomfort'.
Furthelmore, meeting rooms present a challenge when it comes to conditioning spaces (HV AC design) which are sporadic in use and often with high occupancy for short periods. This paper investigates meeting rooms in four different buildings and their conditioning control concepts are discussed in relation to measured results.

Formation of defects in boron nitride by low energy ion bombardment

Formation of defects in hexagonal and cubic boron nitride (h -BN and c -BN, respectively) under low-energy argon or nitrogen ion-bombardment has been studied by near-edge x-ray absorption fine structure (NEXAFS) around boron and nitrogen K -edges. Breaking of B-N bonds for both argon and nitrogen bombardment and formation of nitrogen vacancies, VN, has been identified from the B K -edge of both h -BN and c -BN, followed by the formation of molecular nitrogen, N2, at interstitial positions. The presence of N 2 produces an additional peak in photoemission spectra around N 1s core level and a sharp resonance in the low-resolution NEXAFS spectra around N K -edge, showing the characteristic vibrational fine structure in high-resolution measurements. In addition, several new peaks within the energy gap of BN, identified by NEXAFS around B and N K -edges, have been assigned to boron or nitrogen interstitials, in good agreement with theoretical predictions. Ion bombardment destroys the cubic phase of c -BN and produces a phase similar to a damaged hexagonal phase. © 2009 American Institute of Physics.

Bipolar disorder and adiposity : a study using whole body dual energy X-ray absorptiometry scans

Objective: Previous research has demonstrated a relationship between adiposity and bipolar disorder, although data are derived predominantly from patient samples and use indirect methods of assessing adiposity. This study investigated the association between bipolar disorder and several indices of adiposity, including body fat mass as measured by dual energy X-ray absorptiometry (DXA), in a community-based sample.

Methods: In this study, 21 women with bipolar disorder and 523 healthy controls were drawn from an age-stratified, random, community-based sample of women (20–93 years) participating in the Geelong Osteoporosis Study. Bipolar disorder was diagnosed utilising a semi-structured clinical interview. Anthropometric measurements (weight, height, waist and hip circumference) were taken and fat mass was determined from whole body DXA scans (Lunar DPX-L).

Results: Those with bipolar disorder tended to have greater adiposity. Age-adjusted mean (95% CI) values for bipolar versus controls according to adiposity indices were weight 75.6 (68.9–82.3) versus 72.6 (71.3–74.0) kg, waist circumference 89.8 (84.1–95.6) versus 87.3 (86.1–88.5) cm, waist:hip ratio 0.85 (0.82–0.87) versus 0.84 (0.83–0.84), body mass index 27.6 (25.1–30.1) versus 27.5 (27.0–28.0) kg/m2, fat mass 31.4 (26.5–36.3) versus 28.6 (27.5–29.5) kg and %body fat 40.4 (36.9–43.9) versus 38.0 (37.3–38.7)%; all p > 0.05. Further adjustment for height, smoking, alcohol, psychotropic medication, energy intake or physical activity did not influence these patterns.

Conclusion: Although a pattern suggestive of greater adiposity among those with bipolar disorder was observed, no significant differences were detected. We cannot exclude the possibility of a type II error. Further research with a larger sample may produce more conclusive results.

Large-scale mechanical peeling of boron nitride nanosheets by low-energy ball milling

Mechanical cleavage by Scotch tape was the first method to produce graphene and is still widely used in laboratories. However, a critical problem of this method is the extremely low yield. We have tailored ball milling conditions to produce gentle shear forces that produce high quality boron nitride (BN) nanosheets in high yield and efficiency. The in-plane structure of the BN nanosheets has not been damaged as shown by near edge X-ray absorption fine structure measurements. The benzyl benzoate acts as the milling agent to reduce the ball impacts and milling contamination. This method is applicable to any layered materials for producing nanosheets.

The influence of body build on estimates of body composition from anthropometric measurements in premenopausal women

Objective: To assess the influence of body build on the bias and limits of agreement for estimates of body fat obtained from anthropometric prediction equations when compared with the same data obtained by dual energy X-ray absorptiometry (DEXA).

Survey design and subjects: Ninety-one premenopausal women, aged between 20 and 54 years, were chosen to represent a range of skeletal body build (relative silting height 0.50-0.56) and body fatness [body mass index (BMI) 18-34 kg/m²]. Measurements of weight, sitting height, stature, skinfold thickness, waist, umbilical and hip circumference and total body resistance and reactance were made on all subjects by standard techniques after an overnight fast. A DEXA measurement of total body fat, fat-free soft tissue and total body bone mineral mass was also obtained within 2 weeks of the anthropometric assessment.

Results: At the group level the mean difference (bias) between DEXA and the anthropometric estimates of body fat was similar for all three anthropometric estimates ranging from 2.7 kg with impedance to 1.8 kg with skinfold thickness. The 95% limits of agreement were also similar, ranging from ±5.3 kg with body mass index to ±4.1 kg with impedance. Umbilical circumference, BMI and the amount of bone mineral expressed as a proportion of the fat-free soft-tissue mass were all significantly (P < 0.01) correlated with the level of bias between DEXA and the anthropometric estimates of body fat. This was not the case for relative sitting height or measures of body fat distribution. Regression equations which included BMI or umbilical circumference in combination with the predicted estimates of body fat essentially eliminated the association between the level of bias in predicted body fat and the level of body fatness. They also reduced the 95% limits of agreement between DEXA and the anthropometric estimates of body fat.

Conclusions: Using DEXA estimates of body fat as the standard of reference our results suggest that the comparability and precision of body fat estimates derived from age- and/or sex-specific anthropometric prediction equations based on skinfolds and BMI, but not impedance, can be improved by adjusting for differences in BMI and umbilical circumference respectively.

Novel carbon materials for thermal energy harvesting

To decrease the consumption of fossil fuels, research has been done on utilizing low grade heat, sourced from industrial waste streams. One promising thermoenergy conversion system is a thermogalvanic cell; it consists of two identical electrodes held at different temperatures that are placed in contact with a redox-based electrolyte [1, 2]. The temperature dependence of the direction of redox reactions allows power to be extracted from the cell [3, 4]. This study aims to increase the power conversion efficiency and reduce the cost of thermogalvanic cells by optimizing the electrolyte and utilizing a carbon based electromaterial, reduced graphene oxide, as electrodes. Thermal conductivity measurements of the K3Fe(CN)6/K4Fe(CN)6 solutions used, indicate that the thermal conductivity decreases from 0.591 to 0.547 W/m K as the concentration is increased from 0.1 to 0.4 M. The lower thermal conductivity allowed a larger temperature gradient to be maintained in the cell. Increasing the electrolyte concentration also resulted in higher power densities, brought about by a decrease in the ohmic overpotential of the cell, which allowed higher values of short circuit current to be generated. The concentration of 0.4 MK3Fe(CN)6/K4Fe(CN)6 is optimal for thermal harvesting applications using R-GO electrodes due to the synergistic effect of the reduction in thermal flux across the cell and the enhancement of power output, on the overall power conversion efficiency. The maximum mass power density obtained using R-GO electrodes was 25.51 W/kg (three orders of magnitude higher than platinum) at a temperature difference of 60 _C and a K3Fe(CN)6/K4Fe(CN)6 concentration of 0.4 M.