College Biology Students\u27 Conceptions Related to the Nature of Biological Knowledge: Implications for Conceptual Change.

Adequate understanding of the nature of science is a major goal of science education. Understanding of the evolutionary nature of biological knowledge is a means of reinforcing biology students\u27 understanding of the nature of science. It provides students with the philosophical basis, explanatory ideals, and subject matter-specific views of what counts as a scientifically-acceptable biological explanation. This study examined 121 college introductory biology and advanced zoology students for their conceptions related to the nature of biological knowledge. A 60-item Likert-scale questionnaire called the Nature of Biological Knowledge Scale and student interviews were used as complementary research instruments. Firstly, the study showed that 80--100% of college biology students have an adequate understanding of scientific methods, and that a similar percentage of students had learned the theory of evolution by natural selection in their biology courses. Secondly, the study showed that at least 60--80% of the students do not understand the importance of evolution in biological knowledge. Yet the study revealed that a statistically significant positive correlation exist among students\u27 understanding of natural selection, divergent, and convergent evolutionary models. Thirdly, the study showed that about 20--58% of college students hold prescientific conceptions which, in part, are responsible for students\u27 lack of understanding of the nature of biological knowledge. A statistically significant negative correlation was found among students\u27 prescientific conceptions about basis of biological knowledge and nature of change in biological processes, and their understanding of natural selection and evolutionary models. However, the study showed that students\u27 characteristics such as gender, age, major, or years in college have no statistically significant influence on students\u27 conceptions related to the nature of biological knowledge. Only students\u27 depth of biological knowledge or course was found to have a statistically significant influence on students\u27 conceptions related to scientific methods, the scope and limits of biological knowledge, the importance of evolution in biology, and students\u27 understanding of homologous and analogous structural features as products of divergent and convergent evolutionary processes. Findings of this study have implications for college biology teaching, student learning, and conceptual change among college biology students

Effect of Processing on Protein and Carotenoids in Weaning Food Formulated From Sweetpotatoes, or Apios Americana.

White flesh sweetpotatoes (Ipomoea batatas (L.) Lam) are a major food crop in developing countries. This study was to evaluate the protein and carotenoid content and quality of various white fleshed African sweetpotatoes and Apios americana tubers for use as a weaning food. The sweetpotato and Apios are not normally considered sources of carotenoids and proteins, but the wide use of sweetpotatoes as a source of carbohydrate and the renewed interest in Apios warrant the study of carotenoids and proteins in these crops. Total carotenoids ranged from 0$\mu{\rm g}$/100g to 260$\mu$g/100g (fresh weight basis) for sweetpotatoes. Apios total carotenoids ranged from 10 to 40$\mu$g/100 (fresh weight basis). Processing reduced total carotenoids in sweetpotatoes, from 20 to 250$\mu$g/100g. The Hunter color values varied both in the raw and processed samples. $\beta$-Carotene, $\alpha$-carotene and canthaxanthin were identified by isocratic reverse phase HPLC. The values for $\beta$-carotene ranged from zero to 146$\mu$g/100g(fresh weight basis) in the sweetpotatoes, and between 2 and 17$\mu$g/100g in the puree. Carotenoids were confirmed by mass spectroscopy. Apios and two other cultivars did not show any carotenoids. The sweetpotatoes protein content ranged from 4.26 to 8.23 percent fresh weight after pureeing and freeze drying. These were formulated into a rat diet by increasing protein content with pigeon peas (Cajanus cajan) and other dietary supplements, in 60:40 ratio (root crop: pigeon peas). The pigeon peas raised the protein content to 10% for protein efficiency ratio (PER) studies. PER for diets was found to range from 1.57 to 1.92 compared to a PER of 2.5 for casein, indicating significant differences (p $\u3c$ 0.05) in protein quality among the different diets. The data, indicates that one sweetpotato cultivar (T1702) would be suitable for formulating weaning food, due to a higher protein content and higher protein quality, shown by amino acid profile and PER. Processing into puree lowered the amino acid contents from raw roots but in varying degrees. There was a significant difference between the amino acids in the sweetpotato cultivars (p $\u3c$ 0.05) and between sweetpotatoes and Apios. In vitro studies showed low digestibility, probably due to trypsin inhibitors. The computed-PER values for all test materials were very low too, suggesting that this is not a very good method of measuring protein quality in root crop based diets. This study shows that some white flesh sweetpotatoes with complimentation may be used as a source of protein for weaning food but not as a source of $\beta$-carotene. Apios, despite its high level of protein, is not a very good weaning food because the amino acids do not seem to be available to facilitate growth in the rats studied. Further studies need to be done to determine how 1-2 year old children perform on such a weaning food

Extraction of carotenoides in whiteflesh sweet-potatoes (Ipomena batats l)

No Abstract

Modelling the deformations of masonry

Bibliography: p. 263-276

Elastic and creep properties of lightweight concrete masonry

Bibliography: p. 99-10

Protein and Amino Acid contents of four whitefleshed African sweetpotatoes and American groundnut

White flesh sweetpotatoes (Ipomoea batatas (L.) Lam) are a major food crop in developing countries. The purpose of this study was to evaluate the protein and amino acid content of four white fleshed African sweetpotato roots and Apios americana tubers (American groundnuts). Although the sweetpotato and Apios are not normally considered sources of proteins, the wide use of sweetpotatoes as a source of carbohydrate and the renewed interest in Apios warrant the study of proteins in these crops. Protein content ranged from 4.26 to 8.23% of fresh weight even after pureeing and freeze-drying. One sweetpotato cultivar T1702 had a higher protein content and quality than the others based on amino acid profile evaluation. Processing into puree reduced most of the amino acids to varying degrees. There was a difference in amino acids among sweetpotato cultivars (P<0.05) and between sweetpotatoes and Apios. Apios had a higher level of protein than the sweetpotatoes before and after processing into puree. Two fractions of proteins were identified, namely a "whitle" and a "chomoplast" protein... white and chromoplast protein fractions. The white protein had a higher percentage of both protein and amino acids.Les patates douces e chaire blanche (Ipomoea batatas (L.) Lam) constituent un aliment de base dans les pays en voie de developpement. Le but de cette recherche est d'evaluer la teneur en proteine et en amino acide de quatre patates douces africaines e chaires blanches et les gousses d'Apios americana. Bien que la patate douce et l'Apios ne sont pas normalement consideres comme sources des proteines, l'utilisation considerable de patate douce comme source de carbohydrate et l'interet renouvele dans le mandat en Apios justifient l'evaluation de proteines dans ces cultures. La patate douce et Apios ont des teneur en proteines variables entre 4,26 et 8,23% de poids frais meme apres avoir ete transforme en puree ou seche. Les donnees indiquent qu' un cultivar de patate douce (T 1702) avait une haute teneur et qualite de proteines, par rapport aux autres patates douces comme indique par le profil d'acides amines. Le fait de transformer la patate douce en puree reduisait le plupart des acides amines avec des degres variables et il y avait une difference significative entre les acides amines dans les cultivars de patate douce (P=0.05)/ et entre la patate douce et l'Apios. L'Apios avait un niveau eleve de 7,7% de proteines que la patate douce quant il est encore brute et de 8,28% lorsque transforme en puree. Deux fractions de proteines ont ete trouve et nomme fractions de proteines chromoplasmes et blanches. La proteine blanche avait un pourcentage eleve de proteines et d'acides amines