Studies of the kinetics and mechanisms of perfluoroether reactions on iron and oxidized iron surfaces

Polymeric perfluoroalkylethers are being considered for use as lubricants in high temperature applications, but have been observed to catalytically decompose in the presence of metals. X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) were used to explore the decomposition of three model fluorinated ethers on clean polycrystalline iron surfaces and iron surfaces chemically modified with oxygen. Low temperature adsorption of the model fluorinated ethers on the clean, oxygen modified and oxidized iron surfaces was molecular. Thermally activated defluorination of the three model compounds was observed on the clean iron surface at remarkably low temperatures, 155 K and below, with formation of iron fluoride. Preferential C-F bond scission occurred at the terminal fluoromethoxy, CF3O, of perfluoro-1-methoxy-2-ethoxy ethane and perfluoro-1-methoxy-2-ethoxy propane and at CF3/CF2O of perfluoro-1,3-diethoxy propane. The reactivity of the clean iron toward perfluoroalkylether decomposition when compared to other metals is due to the strength of the iron fluoride bond and the strong electron donating ability of the metallic iron. Chemisorption of an oxygen overlayer lowered the reactivity of the iron surface to the adsorption and decomposition of the three model fluorinated ethers by blocking active sites on the metal surface. Incomplete coverage of the iron surface with chemisorbed oxygen results in a reaction which resembles the defluorination reaction observed on the clean iron surface. Perfluoro-1-methoxy-2-ethoxy ethane reacts on the oxidized iron surface at 138 K, through a Lewis acid assisted cleavage of the carbon oxygen bond, with preferential attack at the terminal fluoromethoxy, CF3O. The oxidized iron surface did not passivate, but became more reactive with time. Perfluoro-1-methoxy-2-ethoxy propane and perfluoro-1,3-diethoxy propane desorbed prior to the observation of decomposition on the oxidized iron surface

Food consumption patterns, socio- demographic status and nutritional risks of women in low and middle income communities in Kwandengezi, KwaZulu-Natal, South Africa

Food consumption patterns have changed dramatically in recent times. Traditional diets are replaced by “westernised diets” causing nutritional risks like malnutrition. Unemployment and lack of nutrition education have an impact on communities, in terms of the foods being purchased and consumed. This research seeks to establish a true reflection of the nutritional status, food intake patterns of the communities participating in the study and influencing factors. This is to estimate if the low income community, the north section is in a more disadvantaged situation when compared to the middle income community, the south section. The objective was to determine the socio-demographic status, food consumption patterns and nutritional risk of a lowincome and middle-income community that reside in KwaNdengezi Township in KwaZulu-Natal, South Africa.The research being undertaken consists of descriptive and theoretical studies. Upon consention, participants data were collected by means of an interview setting. A set of questionnaires included, Socio-demographic, Food Frequency and 24-Hour Recall questions. The anthropometric measurements were taken in order to determine the body mass index status. Both sections of the township were affected by unemployment. The education status of the participants showed concern as both sections had fewer graduates. The mean Food Variety Scores (FVS) (±SD) for all items consumed from various food groups during seven days, indicated a medium where both sections had a good dietary diversity score ranging from 7-9 food groups, which summarize the food group diversity as being in the majority in the north section. The results of energy distribution of macronutrients from the average of the 24-hr recall when compared to the WHO dietary factor goals showed that the participants’ diet was well balanced, in relation to macronutrient intake for both sections but was lacking in micronutrient intake. Overweight and obesity tests showed disturbing results with majority of women caregivers in both sections found to be obese, showing risks of obesity related illnesses (NCDs). More nutrition knowledge should be geared towards educating the most vulnerable and poverty stricken communities. The micronutrient intake must be promoted at lower and middle income communities.. The government should devise and implement projects that empower women so that they are not codependent.&nbsp

Factors Associated with Blockages to Outdoor Recreation Participation: A State Survey

Data from a random sample of Ohio residents were used in an attempt to isolate factors that were hypothesized to be related to outdoor recreation blockages. The study revealed that socio-demographic variables failed to explain the variance in factor scores created to measure blockages to outdoor recreation. Findings from descriptive statistics and the factor analyses are discussed in a planning context

Transfer of Rocks between Planetary Systems: Panspermia Revisited

Motivated by the recent discovery of interstellar objects passing through the solar system, and by recent developments in dynamical simulations, this paper reconsiders the likelihood for life bearing rocks to be transferred from one planetary system to another. The astronomical aspects of this lithopanspermia process can now be estimated, including the cross sections for rock capture, the velocity distributions of rocky ejecta, the survival times for captured objects, and the dynamics of the solar system in both its birth cluster and in the field. The remaining uncertainties are primarily biological, i.e., the probability of life developing on a planet, the time required for such an event, and the efficiency with which life becomes seeded in a new environment. Using current estimates for the input quantities, we find that the transfer rates are enhanced in the birth cluster, but the resulting odds for success are too low for panspermia to be a likely occurrence. In contrast, the expected inventory of alien rocks in the solar system is predicted to be substantial (where the vast majority of such bodies are not biologically active and do not interact with Earth).Comment: 18 pages, 3 figures, to appear in Astrobiolog

Detection of Diatomic Carbon in 2I/Borisov

2I/Borisov is the first-ever observed interstellar comet (and the second detected interstellar object (ISO)). It was discovered on 2019 August 30 and has a heliocentric orbital eccentricity of ~3.35, corresponding to a hyperbolic orbit that is unbound to the Sun. Given that it is an ISO, it is of interest to compare its properties—such as composition and activity—with the comets in our solar system. This study reports low-resolution optical spectra of 2I/Borisov. The spectra were obtained by the MDM Observatory Hiltner 2.4 m telescope/Ohio State Multi-Object Spectrograph (on 2019 October 31.5 and November 4.5, UT). The wavelength coverage spanned from 3700 to 9200 Å. The dust continuum reflectance spectra of 2I/Borisov show that the spectral slope is steeper in the blue end of the spectrum (compared to the red). The spectra of 2I/Borisov clearly show CN emission at 3880 Å, as well as C2 emission at both 4750 and 5150 Å. Using a Haser model to covert the observed fluxes into estimates for the molecular production rates, we find Q(CN) = 2.4 ± 0.2 × 10²⁴ s⁻¹, and Q(C₂) = (5.5 ± 0.4) × 10²³ s⁻¹ at the heliocentric distance of 2.145 au. Our Q(CN) estimate is consistent with contemporaneous observations, and the Q(C₂) estimate is generally below the upper limits of previous studies. We derived the ratio Q(C₂)/Q(CN) = 0.2 ± 0.1, which indicates that 2I/Borisov is depleted in carbon-chain species, but is not empty. This feature is not rare for the comets in our solar system, especially in the class of Jupiter-family comets

The impact of a nutrition programme on the dietary intake patterns of primary school children

Objective: The aim of this study was to improve the dietary intake patterns and food choices of children aged 9-13 years in a periurbancommunity.Methods: Two schools were randomly selected from within this periurban community. A nutrition education programme was implementedover one school term, with the testing of nutrition knowledge occurring pre- and post-intervention, and in the long term, with the experimentalgroup only. A validated 24-hour recall questionnaire was completed pre- and post-intervention by both the control (n = 91) and experimentalgroups (n = 81), and in the long term, by the experimental group. Food models were used to assist in the estimation of portion sizes andidentification of food items. The questionnaire was analysed using the computer software programme FoodFinder 3, with means and standarddeviations calculated for macro- and micronutrients, and comparisons made with dietary reference intakes for specific age groups. A list wasdrawn up of the 20 most commonly consumed food items, based on weights consumed. Paired t-tests were conducted to assess significancein dietary intake and food choices after the intervention. Correlations between knowledge and dietary choices were determined among theexperimental group in the long-term measurements.Results: Correlations linked protein intake to knowledge of proteins, and vitamin C intake to knowledge of fruit and vegetables. Fruit andvegetable intake remained very low. Refined sugars and fat were still consumed among the experimental group. The diet for both groups wasbased on carbohydrates.Conclusions: The objective of changing the dietary intake patterns of the children was not achieved. The intake of legumes, fruit and vegetables remained low. The lack of variety in intake results in a diet that does not meet the daily requirements of children

Analysis of finger movement coordination during the Variable Dexterity Test and comparative activities of daily living

Background/Aims: This study aimed to analyse and compare finger coordination patterns during the performance of the Variable Dexterity Test (VDT) and comparative daily tasks. Methods: An optoelectronic system was used to record the joint angles of 10 healthy participants performing the VDT and daily tasks. Joint angles from digits 1 to 5 were cross-correlated across the tasks, providing a measure of the degree of finger movement coordination. Results: Correlation coefficients showed identifiable coordination patterns among the finger movements under analysis. Low correlation coefficients suggested the presence of independent finger movements during the performance of the selected tasks. Conclusions: Finger movement coordination patterns observed during activities of daily living are comparable with the patterns observed during performance of the Variable Dexterity Test for the three grasping patterns analysed in the stud

A descriptive analysis of a five-county attitude study: outdoor recreation and industrialization

Exact date of working paper unknown