Brazil nut sorting for aflatoxin prevention: a comparison between automatic and manual shelling methods

The impact of automatic and manual shelling methods during manual/visual sorting of different batches of Brazil nuts from the 2010 and 2011 harvests was evaluated in order to investigate aflatoxin prevention.The samples were tested as follows: in-shell, shell, shelled, and pieces in order to evaluate the moisture content (mc), water activity (Aw), and total aflatoxin (LOD = 0.3 µg/kg and LOQ 0.85 µg/kg) at the Brazil nut processing plant. The results of aflatoxins obtained for the manually shelled nut samples ranged from 3.0 to 60.3 µg/g and from 2.0 to 31.0 µg/g for the automatically shelled samples. All samples showed levels of mc below the limit of 15%; on the other hand, shelled samples from both harvests showed levels of Aw above the limit. There were no significant differences concerning the manual or automatic shelling results during the sorting stages. On the other hand, the visual sorting was effective in decreasing the aflatoxin contamination in both methods.

Flow injection analysis (FIA) determination of lead by hydride generation in banded coral skeletons /

A flow injection hydride generation direct current plasma atomic emission spectrometric (FI-HG-DCP-AES) method was developed for the determination of lead at ng.ml-l level. Potassium ferricyanide (K3Fe(CN)6) was used along with sodium tetrahydroborate(III) (NaBH4) to produce plumbane (PbH4) in an acid medium. The design of a gas-liquid separator (hydride generator) was tested and the parameters of the flow injection system were optimized to achieve a good detection limit and sample throughput. The technique developed gave a detection limit of 0.7 ng.ml-l(3ob). The precision at 20 ng.ml"* level was 1.6 % RSD with 1 1 measurements (n=l 1). Volume of sample loop was 500 |J.l. A sample throughput of 120 h"^ was achieved. The transition elements, Fe(II), FeOH), Cd(n), Co(II), Mn(n), Ni(II) and Zn(n) do not interfere in this method but 1 mg,l'l Cu(II) will suppress 50 % of the signal from a sample containing 20 ng.ml'l Pb. This method was successfully applied to determine lead in a calcium carbonate (CaC03) matrix of banded coral skeletons from Si-Chang Island in Thailand.

Implementing a question-generation strategy with bilingual students: exploring the perspectives of a beginning teacher /

This study examined the challenges associated with the explicit delivery of questiongeneration strategy with 8 Arab Canadian students from the perspective of a bilingual beginning teacher. This study took place in a private school and involved 2 stages consisting of 9 instructional sessions, and individual interviews with the students. Data gathered from these interviews and the researcher's field notes from the sessions were used to gain insights about the participants' understanding and use of explicit instruction. The themes that emerged from the data included "teacher attitude," "students' enhanced metacognitive awareness and strategy use," "listening skills," and "instructional challenges." Briefly, teacher's attitude demonstrated how teacher's beliefs and knowledge influenced her willingness and perseverance to teach explicitly. Students' enhanced metacognitive awareness and strategy use included students' understanding and use of the question-generation strategy. The students' listening skills suggested that culture may influence their response to the delivery of explicit instruction. Here, the cultural expectations associated with being a good listener reinforced students' willingness to engage in this strategy. Students' prior knowledge also influenced their interaction with the question-generation strategy. Time for process versus covering content was a dominant instructional challenge. This study provides first hand information for teachers when considering how students' cultural backgrounds may affect their reactions to explicit strategy instruction.

Arsenic and germanium determination by hydride generation in the D.C. plasma optical emission spectrometer

Modifications to the commercial hydride generator, manufactured by Spectrametrics, resulted in improved operating procedure and enhancement of the arsenic and germanium signals. Experiments with arsenic(III) and arsenic(V) showed that identical reiults could be produced from both oxidation states. However, since arsenic(V) is reduced more slowly than arsenic(III), peak areas and not peak heights must be measured when the arsine is immediately stripped from the system (approximately 5 seconds reaction). When the reduction is allowed to proceed for 20 seconds before the arsine is stripped, peak heights may be used. For a 200 ng/mL solution, the relative standard deviation is 2.8% for As(III) and 3.8% for As(V). The detection limit for arsenic using the modified system is 0.50 ng/mL. Studies performed on As(V) standards show that the interferences from 1000 mg/L of nickel(II), cobalt(II), iron(III), copper(II), cadmium(II), and zinc(II) can be eliminated with the aid of 5 M Hel and 3% L-cystine. Conditions for the reduction of germanium to the corresponding hydride were investigated. The effect of different concentrations of HCl on the reduction of germanium to the covalent hydride in aqueous media by means of NaBH 4 solutions was assessed. Results show that the best response is accomplished at a pH of 1.7. The use of buffer solutions was similarly characterized. In both cases, results showed that the element is best reduced when the final pH of the solution after reaction is almost neutral. In addition, a more sensitive method, which includes the use of (NH4)2S208' has been developed. A 20% increase in the germanium signal is registered when compared to the signal achieved with Hel alone. Moreover, under these conditions, reduction of germanium could be accomplished, even when the solution's pH is neutral. For a 100 ng/mL germanium standard the rsd is 3%. The detection limit for germanium in 0.05 M Hel medium (pH 1.7) is 0.10 ng/mL and 0.09 ng/mL when ammonium persulphate is used in conjunction with Hel. Interferences from 1000 mg/L of iron(III), copper(II), cobalt(II), nickel(II), cadmium(II), lead(II), mercury(II), aluminum(III), tin(IV), arsenic(III), arsenic(V) and zinc(II) were studied and characterized. In this regard, the use of (NH4)ZS20S and Hel at a pH of 1.7 proved to be a successful mixture in the sbppression of the interferences caused by iron, copper, aluminum, tin, lead, and arsenic. The method was applied to the determination of germanium in cherts and iron ores. In addition, experiments with tin(IV) showed that a 15% increase in the tin signal can be accomplished in the presence of 1 mL of (NH4)2S20S 10% (m/V).

Arsenic speciation by ion-exchange chromatography with on- line determination by hydride generation: electronic modification of the D.C. plasma by photon counting

A method using L-cysteine for the determination of arsenous acid (As(III)), arsenic acid (As(V)), monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA) by hydride generation was demonstrated. The instrument used was a d.c. plasma atomic emission spectrometer (OCP-AES). Complete recovery was reported for As(III), As(V), and DMAA while 86% recovery was reported for MMAA. Detection limits were determined, as arsenic for the species listed previously, to be 1.2, 0.8, 1.1, and 1.0 ngemL-l, respectively. Precision values, at 50 ngemL-1 arsenic concentration, were f.80/0, 2.50/0, 2.6% and 2.6% relative standard deviation, respectively. The L-cysteine reagent was compared directly with the conventional hydride generation technique which uses a potassium iodide-hydrochloric acid medium. Recoveries using L-cysteine when compared with the conventional method provided the following results: similar recoveries were obtained for As(III), slightly better recoveries were obtained for As(V) and MMAA, and significantly better recoveries for DMAA. In addition, tall and sharp peak shapes were observed for all four species when using L-cysteine. The arsenic speciation method involved separation by ion exchange .. high perfonnance liquid chromatography (HPLC) with on-line hydride generation using the L.. cysteine reagent and measurement byOCP-AES. Total analysis time per sample was 12 min while the time between the start of subsequent runs was approximately 20 min. A binary . gradient elution program, which incorporated the following two eluents: 0.01 and 0.5 mM tri.. sodium citrate both containing 5% methanol (v/v) and both at a pH of approximately 9, was used during the separation by HPLC. Recoveries of the four species which were measured as peak area, and were normalized against As(III), were 880/0, 290/0, and 40% for DMAA, MMAA and As(V), respectively. Resolution factors between adjacent analyte peaks of As(III) and DMAA was 1.1; DMAA and MMAA was 1.3; and MMAA and As(V) was 8.6. During the arsenic speciation study, signals from the d.c. plasma optical system were measured using a new photon-signal integrating device. The_new photon integrator developed and built in this laboratory was based on a previously published design which was further modified to reflect current available hardware. This photon integrator was interfaced to a personal computer through an AID convertor. The .photon integrator has adjustable threshold settings and an adjustable post-gain device.

Continuous hydride generation in the presence of L- cysteine for the determination of arsenic, bismuth, antimony and tin in steels by inductively coupled plasma atomic emission spectrometry

Arsenic, bismuth, germanium, antimony and tin were simultaneously determined by continuous hydride generation and inductively coupled plasma-atomic emission spectrometry . I Hydrides were introduced into four different types of gas-liquid separators. Two of the gas-liquid separators were available in-house. A third was developed for this project and a fourth was based on a design used by CET AC. The best signal intensity was achieved by the type II frit-based gas-liquid separator, but the modified Cetac design gave promise for the future, due to low relative standard deviation. A method was developed for the determination of arsenic, bismuth, antimony and tin in low-alloy steels. Four standard reference materials from NIST were dissolved in 10 mL aqua regia without heat. Good agreement was obtained between experimental values and certified values for arsenic, bismuth, antimony and tin. The method was developed to provide the analyst with the opportunity to determine the analytes by using simple aqueous standards to prepare calibration lines. Within the limits of the samples analyzed, the method developed is independent of matrix.

Selected topics in fast atom bombardment (FAB) mass spectrometry a)specially designed probe tips and ion generation, b)structures of vitamin B6 schiff base complexes

This thesis can be broken down into two sections. Section one is a study . of the ionization mechanisms and the ion source optimization for Fast Atom Bombardment (FAB) ionization. For this study, several specially designed probe tips were created and tested under various experimental conditions. The aIm of this section is to understand the operating characteristics of a FAB IOn source better. The second section involves the study of several Vitamin B6 Schiff Base complexes using both positive and negative ion FAB MS. This section is an exploration of the usefulness of FAB MS as a structure probe for the metalcoordination complexes of Vitamin B6.

The generation effect and word learning: a test of the effect of the language experience approach versus the text approach in the acquisition of new reading vocabulary

A class of twenty-two grade one children was tested to determine their reading levels using the Stanford Diagnostic Reading Achievement Test. Based on these results and teacher input the students were paired according to reading ability. The students ages ranged from six years four months to seven years four months at the commencement of the study. Eleven children were assigned to the language experience group and their partners became the text group. Each member of the language experience group generated a list of eight to be learned words. The treatment consisted of exposing the student to a given word three times per session for ten sessions, over a period of five days. The dependent variables consisted of word identification speed, word identification accuracy, and word recognition accuracy. Each member of the text group followed the same procedure using his/her partner's list of words. Upon completion of this training, the entire process was repeated with members of the text group from the first part becoming members of the language experience group and vice versa. The results suggest that generally speaking language experience words are identified faster than text words but that there is no difference in the rate at which these words are learned. Language experience words may be identified faster because the auditory-semantic information is more readily available in them than in text words. The rate of learning in both types of words, however, may be dictated by the orthography of the to be learned word.

Locating home : the diverse experiences of recent newcomer youth and first generation youth within Ontario's education system

This study has found that youth who or whose parents had left their home country for fear-based reasons were less involved within their school and wider community than youth who left or whose parents left for reasons concerning their social mobility. Many existing studies focus on the challenges newcomer youth experience within the education system (see Anisef, Brown, Phythian, & Sweet, 2010), however through the use of qualitative methodologies this study expanded on the current literature by further examining why it is some youth are successful in overcoming such challenges, while others are not. This study supported what has been demonstrated in the literature regarding challenges faced by newcomer youth and resources to address such challenges. Despite challenges experienced within the education system, youth planned to complete secondary school and attend a postsecondary institution. However, not all youth anticipated remaining in Canada upon completion of their education, with youth or youth whose parents left their home country for fear-based reasons frequently discussing the possibility of returning to their or their parents' home country. Thus, perhaps these youth were less involved within their school, as their goal was not necessarily to establish or maintain connections within their community as they may have viewed residing in Canada as temporary. This finding has important implications, as there are benefits to involvement in extracurricular activities, which may assist youth in overcoming challenges encountered within the education system. Therefore, it would seem that youth who had or whose parents had left their home country for reasons concerning their social mobility may have be at an advantage within the education system with respect to their involvement in school. Perhaps then this differential involvement may at least partially explain why it is some newcomer youth are able to overcome challenges they experience in the education system, while others are not. Both policy and theoretical implications are discussed.

Automatic evolution of conceptual building architectures

This thesis describes research in which genetic programming is used to automatically evolve shape grammars that construct three dimensional models of possible external building architectures. A completely automated fitness function is used, which evaluates the three dimensional building models according to different geometric properties such as surface normals, height, building footprint, and more. In order to evaluate the buildings on the different criteria, a multi-objective fitness function is used. The results obtained from the automated system were successful in satisfying the multiple objective criteria as well as creating interesting and unique designs that a human-aided system might not discover. In this study of evolutionary design, the architectures created are not meant to be fully functional and structurally sound blueprints for constructing a building, but are meant to be inspirational ideas for possible architectural designs. The evolved models are applicable for today's architectural industries as well as in the video game and movie industries. Many new avenues for future work have also been discovered and highlighted.

Experiences with cultural capital in education : exploring the educational life stories of first-generation postsecondary students

This study used a life history research design to explore first-generation university students' educational life stories and experiences with cultural capital. The project sought to examine how 3 first-generation university students experience cultural capital that is privileged in Ontario's education system and how the interactions between capital acquired through experiences within the home and school and capital privileged by the education system affect these students' educational experiences and perceptions. Using Pierre Bourdieu's (1984; 1986) theory of cultural capital as a framework, 3 firstgeneration, first-year university students participated in two 1- to 2-hour interviews. A focus on each participant's experiences with culture, capital, and education revealed themes corresponding to navigating, utilizing, and confronting familial, institutional, economic, and embodied forms of cultural capital. The study highlights the importance of recognizing how cultural capital influences the education system and how firstgeneration students can recreate normative pathways and achieve academic success despite challenges posed by the cultural capital privileged within the education system. Given cultural capital's effect on academic success, understanding first-generation students' educational life stories sheds light on the complex challenges facing students who confront and deal with privileged culture in the education system.

Explorações educacionais (educational explorations) : schooling experiences of second-generation Portuguese Canadian students

This study explores the stories and experiences of second-generation Portuguese Canadian secondary school students in Southern Ontario, Canada. The purpose of this research was to understand the educational experiences of students, specifically the successes, challenges, and struggles that the participants faced within the education system. Questions were also asked about identity issues and how participants perceived their identities influencing their educational experiences. Six Portuguese Canadian students in grades 9 to 11 were interviewed twice. The interviews ranged from 45 minutes to 90 minutes in length. Data analysis of qualitative, open-ended interviews, research journals, field notes and curricular documents yielded understandings about the participants' experiences and challenges in the education system. Eight themes emerged from data that explored the realities of everyday life for second-generatiop Portuguese Canadian students. These themes include: influences of part-time work on schooling, parental involvement, the teacher is key, challenges and barriers, the importance of peers, Portuguese Canadian identity, lack of focus on identity in curricul:um content, and the dropout problem. Recommendations in this study include the need for more community-based programs to assist students. Furthermore, teachers are encouraged to utilize strategies and curriculum resources that engage learners and integrate their histories and identities. Educators are encouraged to question power dynamics both inside and outside the school system. There is also a need for further research with Portuguese Canadian students who are struggling in the education system as well as an examination of the number of hours that students work.

Creating a Generation of Upstanders: Curriculum Resource to Help Ontario Educators Build Safe Schools

This project focuses on the bullying found in the 21st century elementary classrooms, more specifically in grades 4-8. These grades were found to have high levels of bullying because of major shifts in a student’s life that may place a student of this age at risk for problems with their peer relationships (Totura et al., 2009). Supporting the findings in the literature review, this handbook was created for Ontario grade 4-8 classroom teachers. The resource educates teachers on current knowledge of classroom bullying, and provides them with information and resources to share with their students so that they can create a culture of upstanders. Upstanders are students who stand up for the victims of bullying, and have the self-esteem and strategies to stand up to classroom bullies. These upstanders, with the support of their classroom teachers and their peers, will be a force strong enough to build the government-mandated Safe School environment.