Thermal treatment of weddellite—a Raman and infrared emission spectroscopic study

Thermal transformations of natural calcium oxalate dihydrate known in mineralogy as weddellite have been undertaken using a combination of Raman microscopy and infrared emission spectroscopy. The vibrational spectroscopic data was complimented with high resolution thermogravimetric analysis combined with evolved gas mass spectrometry. TG–MS identified three mass loss steps at 114, 422 and 592 °C. In the first mass loss step water is evolved only, in the second and third steps carbon dioxide is evolved. The combination of Raman microscopy and a thermal stage clearly identifies the changes in the molecular structure with thermal treatment. Weddellite is the phase in the temperature range up to the pre-dehydration temperature of 97 °C. At this temperature, the phase formed is whewellite (calcium oxalate monohydrate) and above 114 °C the phase is the anhydrous calcium oxalate. Above 422 °C, calcium carbonate is formed. Infrared emission spectroscopy shows that this mineral decomposes at around 650 °C. Changes in the position and intensity of the C=O and C---C stretching vibrations in the Raman spectra indicate the temperature range at which these phase changes occur.

Purity evaluation and influence of carbon nanotube on carbon nanotube/graphite thermal stability

High resolution thermogravimetry has been used to evaluate the carbonaceous content in a commercial sample of single-walled carbon nanotube (SWNT). The content of SWNTs in the sample was found to be at least 77mass% which was supported by images obtained with scanning and transmission electron microscopies (SEM and TEM). Furthermore, the influence of SWNT addition on the thermal stability of graphite in mixtures of SWNT/graphite at different proportions was investigated. The graphite stability decreased with the increased of SWNT content in the overall range of composition. This behavior could be due to the close contact between these carbonaceous species as determined by SEM analysis.

Defining the flammability of cylindrical metal rods through characterization of the thermal effects of the ignition promoter

All relevant international standards for determining if a metallic rod is flammable in oxygen utilize some form of “promoted ignition” test. In this test, for a given pressure, an overwhelming ignition source is coupled to the end of the test sample and the designation flammable or nonflammable is based upon the amount burned, that is, a burn criteria. It is documented that (1) the initial temperature of the test sample affects the burning of the test sample both (a) in regards to the pressure at which the sample will support burning (threshold pressure) and (b) the rate at which the sample is melted (regression rate of the melting interface); and, (2) the igniter used affects the test sample by heating it adjacent to the igniter as ignition occurs. Together, these facts make it necessary to ensure, if a metallic material is to be considered flammable at the conditions tested, that the burn criteria will exclude any region of the test sample that may have undergone preheating during the ignition process. A two-dimensional theoretical model was developed to describe the transient heat transfer occurring and resultant temperatures produced within this system. Several metals (copper, aluminum, iron, and stainless steel) and ignition promoters (magnesium, aluminum, and Pyrofuze®) were evaluated for a range of oxygen pressures between 0.69 MPa (100 psia) and 34.5 MPa (5,000 psia). A MATLAB® program was utilized to solve the developed model that was validated against (1) a published solution for a similar system and (2) against experimental data obtained during actual tests at the National Aeronautics and Space Administration White Sands Test Facility. The validated model successfully predicts temperatures within the test samples with agreement between model and experiment increasing as test pressure increases and/or distance from the promoter increases. Oxygen pressure and test sample thermal diffusivity were shown to have the largest effect on the results. In all cases evaluated, there is no significant preheating (above about 38°C/100°F) occurring at distances greater than 30 mm (1.18 in.) during the time the ignition source is attached to the test sample. This validates a distance of 30 mm (1.18 in.) above the ignition promoter as a burn length upon which a definition of flammable can be based for inclusion in relevant international standards (that is, burning past this length will always be independent of the ignition event for the ignition promoters considered here. KEYWORDS: promoted ignition, metal combustion, heat conduction, thin fin, promoted combustion, burn length, burn criteria, flammability, igniter effects, heat affected zone.

Upper body musculoskeletal disorders among Australian occupational therapy students

Although upper body musculoskeletal disorders (MSDs) represent an increasingly important issue for university students, few if any studies have targeted the occupational therapy faculty. Given this dearth of information, it was considered necessary to investigate a cross-section of Australian occupational therapy students by means of an established questionnaire survey. Completed replies were obtained from 95.7%, 100% and 97.7% (n = 44, 55 and 48) of students in the first, second and fourth years of a large occupational therapy school in northern Queensland, Australia.---------- The 12-month period prevalence of MSDs was as follows: neck (67.4%), shoulder (46.3%) and upper back (39.5%). Three-quarters of all students (75.5%) reported an MSD occurring in at least one of these body regions. Over half (56.5%) reported an MSD over 2 days' duration in the past year. Almost 40% (39.5%) reported an MSD that had affected their daily life, while one-quarter (25.2%) needed some type of treatment.---------- Logistic regression indicated that students aged over 21 years were almost four times more likely to report shoulder-related MSD (OR 3.7, 95%CI: 1.4-10.2). Year of study in the occupational therapy course was another important MSD correlate, with adjusted odds ratios ranging from 3.3 at the upper back (OR 3.3, 95%CI: 1.2-9.6) to 10.9 at the neck (OR 10.9, 95%CI: 3.2-43.8). Computer usage also incurred a certain degree of risk, with students who spent over 5 hours per week on the computer having an increased risk of MSD at the neck (OR 5.0, 95%CI: 1.3-21.5) and shoulder (OR 4.7, 95%CI: 1.4-18.3).---------- Overall, this study suggests that Australian occupational therapy students have a large burden from MSDs in the upper body region, even more so than other student groups and some working populations. Since the distribution of MSD risk is not uniform among them, interventions to help reduce these conditions need to be carefully targeted. Further longitudinal investigations would also be useful in determining the mechanisms and contributory factors for MSDs among this unique student population.

Self-esteem and self-talk enhancement in upper primary school children

Not all programmes aimed at enhancing children's self-esteem have been successful. This article evaluates the impact of two programmes and offers activities which can be used in the classroom.

Gender and grade differences in upper elementary school children’s descriptive and evaluative self-statements and self-esteem

Gender and developmental differences in self-description, self-evaluation and self-esteem were investigated using 957 elementary school children in grades 3 to 7. Gender differences were found for six of the seven descriptive statements and for five of the seven evaluative statements. The major gender stereotypical findings from previous studies were replicated. Boys reported higher scores than girls on descriptive and evaluative statements about their physical abilities and mathematics, while girls reported higher scores on descriptive and evaluative statements about reading. Declines over time were noted for all self-evaluations except having good relations with peers and for global self-esteem, providing some support for the notion that the decline in self-concepts and self-esteem may be attributed to the children's perceptions of themselves becoming more accurate and less egocentric in line with their cognitive capacity to integrate external feedback realistically.