Teacher rating forms: Critique and reformulation of previous validation designs.

Maintains that typical teacher rating form (TRF) validation studies are adequately designed to determine TRF validity only when it is assessed on the empirical, or criterion-related, validity model. The construct validity model, however, is more appropriate for assessing TRF validity, and this model requires different validation designs. The strongest construct validity design requires random assignment of students to a multisection course, which is not typically done. Where random assignment is impossible, repeated measurements correlational designs (panel designs) are recommended. (French abstract) (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Starch–lipid and starch–lipid–protein complexes: A comprehensive review

Physical interactions often occur between major food components during food processing. These interactions may involve starch, lipids, and proteins forming V‐type starch–lipid complexes or ternary starch–lipid–protein complexes of larger molecular size and greater structural order. Complexes between starch and lipids have been the subject of intensive research for over half a century, whereas the study of starch–lipid–protein complexes is a relatively new field with only a limited amount of knowledge being gained so far. The formation of these complexes can significantly affect the functional and nutritional properties of finished food products in terms of flavor, texture, shelf life, and digestibility. This article provides a comprehensive review of starch–lipid and starch–lipid–protein complexes, including their classification, factors affecting their formation and structure, and preparative and analytical methods. The review also considers how complexes affect the physicochemical and functional properties of starch, including digestibility, and potential applications in the food industry.     

Effect of Temperature and Soluble Solids Content on the Viscosity of Beetroot (Beta vulgaris) Juice Concentrate

The study investigates the viscosity of clarified beetroot juice as dependent on temperature and soluble solids content. Rheological research was carried out using a rotational rheometer with a system of coaxial cylinders. Flow curves were obtained in the temperature range from 10 to 60°C and at the soluble solids content of 50° to 67.1°Bx. The concentrate under study showed a Newtonian behaviour. Dynamic viscosity ranged from 5.2 to 320 mPa·s and depended on soluble solids content and temperature of measurement. The effect of temperature was described using an Arrhenius equation. Activation energy values were between 24.68 and 39.96 kJ/mol. The effect of soluble solids content was described employing a power-law function and an exponential function. In addition, two equations were proposed to describe the combined effect of temperature and soluble solids content on the viscosity of beetroot juice concentrate.     

Cadmium concentration in durum wheat grain (Triticum turgidum) as influenced by nitrogen rate,seeding date and soil type

BACKGROUND: Cadmium (Cd) is a trace element that has been associated with various human health problems. Cd enters plants, either by direct absorption through leaves or by uptake from soils, allowing Cd into the food chain. Nitrogen (N) fertilizer management is important in optimizing crop yield and protein content of durum wheat, but may influence Cd availability and hence Cd concentration in crops, with the effects being strongly influenced by environmental conditions and crop cultivar. RESULTS: In field studies, Cd and protein concentration in durum wheat grain differed between cultivars and were strongly affected by N application, with only minor effects of N occurring on concentration and uptake of P and Zn. Protein content increased significantly with N application in five of six site‐years, with the response being generally independent of cultivar and seeding data. Cd concentration also increased with N application in five of six seeding dates, with the response being greater in AC Melita than Arcola in three of the six site‐years. There were large differences in Cd concentration from year to year and with seeding date, indicating a strong environmental influence. CONCLUSIONS: This study shows that different cultivars accumulate different levels of Cd in the grain and that seeding date and nitrogen fertilizer management can influence grain Cd concentration, with the magnitude of effects varying with environmental factors. In the future we may be able to manipulate management practices to optimize protein concentration and minimize Cd concentration in durum wheat, which could help to address the health and safety concerns of consumers. © Society of Chemical Industry and Her Majesty the Queen in right of Canada     

Glycemic effect of potatoes

Potatoes are the world’s third largest food crop and the most extensively consumed root vegetable. They have high starch content and are a major source of dietary carbohydrate in human nutrition. This review article considers potatoes as a food crop, the properties of potato starch, and methods of preparing potatoes domestically for consumption, before considering the effects of potatoes on postprandial glycemia. Potatoes have been classified as a food that causes high postprandial glycemia, which over the long term may increase the risk of obesity and chronic diseases such as type-2 diabetes and cardiovascular disease. Methods for measuring the glycemic effects of potatoes are considered. In vivo methods, such as the glycemic index are discussed and compared with in vitro tests that measure the breakdown of available carbohydrates in potatoes. The potential for developing potato varieties that have more slowly-digestible starch, and hence a lower glycemic effect, is considered.     

Effect of d-isomer concentration on the coloration properties of poly(lactic acid)

Poly(lactic acid) (PLA) fibre is derived from annually renewable crops, it is 100% compostable and its life cycle potentially reduces the earth's carbon dioxide level. In this work PLA fabrics containing variable concentrations of the d- and l-isomers have been studied to ascertain their dyeability, the characteristics of those dyed polymers, and their subsequent performance and properties. Comparison of poly(lactic acid) fabrics with varying d-isomer content revealed differences in melting temperature; by virtue of a higher d-isomer concentration, ‘high d-’ fibres have greater fibre entropy which causes a decrease in melting temperature. As a result of greater fibre entropy, high d- fibres have more amorphous and less crystalline regions in the polymer, with respect to low d- fibres, hence, high d- fabrics display greater dye exhaustion and colour strength in comparison with their low d- counterpart in all dyes and all concentrations. In application of a dye mixture for a black shade, high d- fibres are able to be dyed to an excellent black shade, whereas low d- fibres appear very brown, due to lower exhaustion of the blue component of the mix. In terms of wash fastness, there is very little difference between high d- fibres and low d- fibres; this is because the glass transition temperature for both fibres is very similar.     

Strain rate sensitivity of flow stress at large strains

Measurements of the strain rate sensitivity of flow stress are critically assessed. Results depend on strain and on the range of strain rates employed. Changes in strain hardening and transients in the flow stress are discussed.     

Concerted diurnal patterns in riverine nutrient concentrations and physical conditions

Several long-term sets of hourly nitrate concentration data were obtained through deployment of a nitrate sensor in an upper reach of the River Taw, a small moorland-fed river in the South West of the UK. Examination of the data obtained during periods of low flow and the absence of rainfall in the catchment revealed the presence of marked diurnal cycles, which were in concert and negatively correlated with diurnal cycles in water temperature. After verifying that these cycles were natural, an intensive 90-h field monitoring campaign was conducted, in which river water was sampled hourly and immediately analysed in the laboratory for molybdate-reactive phosphorus (P), nitrate, nitrite, ammonium, and pH. Coincident measurements of water temperature, river discharge and solar energy were also taken at, or close to, the site. All measurements revealed diurnal patterns and all patterns were concerted. The cycles of P, nitrate, nitrite, and discharge had two maxima and minima per 24 h, while the cycle of water temperature had one, with a maximum at 20.00 and a minimum at 08.00. The amplitudes of the cycles of P and nitrate were each about 30% of the mean values, while the amplitude of the nitrite cycle was as great as 80% of the mean value on occasions. Both biological and physical mechanisms for the cycling could operate through water temperature and/or incident radiation to account for the observed phenomenon, but there remains uncertainty of which is the more important. The observations have important implications for both the accuracy of pollution assessment in rivers and the physiological rhythms of riverine organisms.     

Modeling China's energy consumption behavior and changes in energy intensity

China's demand for energy has grown to fuel its rapidly expanding industrial, commercial and consumer sectors. At the same time, China has become the second largest consumer of petroleum products having surpassed Japan for the first time in 2003. The environmental consequences of a continuation of these trends will have global implications. Government policies and consumers have become more environmentally aware, but the ability of governments to formulate policies has been hindered by the lack of data on inter-factor and inter-fuel substitution possibilities. In this paper Allen partial elasticities of factor and energy substitution, and price elasticities of energy demand are calculated for China's industrial economy using a two-stage translog cost function approach for the period 1995–2004. The results suggest that energy is substitutable with both capital and labor. Coal is significantly substitutable with electricity and slightly complementary with oil, while oil and electricity are slightly substitutable. China's energy intensity is increasing during the study period and the major driver appears to be due to the increased use of energy-intensive technology.