Nitrogen fertilization is important in attaining high yielding, quality tobacco. However, practices that use excessive N can be uneconomical, threaten the environment and produce leaves that are high in nitrates. Leaves high in nitrates have been positively correlated with leaves that are high in tobacco specific nitrosamines (TSNA), which are considered potent carcinogens. Competition from cheaper, foreign leaf, increasing costs of fertilizers and new market structures which show purchasers seeking low TSNA leaf demand that producers become more efficient in their N use. The objective of this study is an examination of burley (TN 90) and dark (KY 171) tobacco cultural practices with the hypothesis that optimizing growing conditions will enhance N efficiency. This experiment took place during 2005 and 2006 in the traditional tobacco growing regions of Springfield (Dickson silt loam) and Greeneville, TN (Lindside silt loam). Experimental isolated growing condition variables. Irrigation treatments isolate the importance of soil moisture. Fertigation, while using irrigation practices, isolates the effects of synchronizing crop N demand with N supply. Plasticulture, using fertigation protocol, isolates the importance of soil temperature. Season long measurements of soilwater tension, soil temperature and leaf nitrates were used to evaluate the ability of each practice to keep plants in optimal N uptake and utilization growing conditions. Results showed that the most dramatic and consistent treatment effects were found in the TSNA analysis. Even during a season characterized by precipitation being sufficient in volume and timing to meet plant water demands, irrigation was successfully able to decrease TSNA concentration by about 30%. During drier growing seasons, TSNA was reduced by 50% or more. Measurements of leaf nitrates taken with a Horiba monitor were able to consistently detect treatment and N rate differences. The last sample taken around eight weeks after transplanting correlated strongly with TSNA content (0.81). This tool could prove effective in characterizing optimal N management. Cultural practices that offer control over soil water tension, nitrate content in leaves and soil temperatures can be effective in increasing the ability of the plant to uptake and utilize N towards achieving high yielding, high GRI quality and low TSNA leaf.

<p> The ability to solve problems in creative and innovative ways is more critical than ever in today&rsquo;s rapidly-changing society. To support these demands, the educational curricula in the U.S. and other countries adopted engineering design as a learning platform to promote students&rsquo; creativity, communication and design skills, and innovative problem-solving abilities. When using engineering design, many educators use a variety of engineering design process models. However, little is known about the problem-solving processes in terms of design cognition. Therefore, in this study, the researcher examined the problem-solving patterns of students who engage in engineering design using a cognitive pattern approach. </p><p> This study was conducted as part of the NSF-funded Science Learning through Engineering Design (SLED) project for elementary science students&rsquo; grades three to six. The researcher adopted the sequential analysis method to identify students' problem-solving patterns. Sequential analysis is a statistical research method to detect behavioral or psychological patterns by analyzing repeated cognitive events. The researcher sampled a total of 48 Concurrent Think-Aloud (CTA)sessions to examine the statistical significance of the sequential analysis. Two coders independently conducted data coding using Halfin&rsquo;s codes and confirmed a high range of inter-rater reliability with 97.22 % overall agreements and .86 Kappa coefficients. </p><p> The first research question aimed to identify the common cognitive strategies used by elementary science students in engineering design. The researchers pooled 48 CTA sessions to investigate the common cognitive strategies. The results indicated that the students largely concentrated on idea generation (DE) and sketching (MO) while less emphasized on questioning (QH), predicting (PR), managing (MA), and analyzing (AN). Moreover, the researcher confirmed that the upper level graders showed higher frequencies of cognitive strategies than lower graders. </p><p> The second research question aimed to investigate the common problem-solving sequential patterns of the engineering design process. After pooling the 48 CTA sessions, the researcher analyzed the statistical significances of two-event sequential patterns using GSEQ software. The statistical analysis yielded 14 significant two-event sequential patterns at the right-tailed 0.05 level and two-sided z distribution. Using the significant sequential patterns, the researcher built a pattern-based design process model. The model illustrates various iterations between the problem and solution strategies. The iterations in the problem strategies showed recursive cycles between defining the problem, analyzing, and managing. The solution focused iterations often began with questioning and proceeded to designing and modeling or designing and predicting. Moreover, the pattern model shows that managing and questioning played a key role in bridging problem and solution strategies. </p><p> The third research question was to identify how the cognitive strategies vary by design tasks. The researcher compared eight engineering design tasks used in the SLED project and confirmed that the structure of design problems was associated with the students&rsquo; problem-solving strategies. The results of data analysis showed that the participant students commonly emphasized on <i>Designing</i> and <i>Modeling</i> strategies. However, the researcher found that the modeling-driven design tasks required accurate mechanical designing lead students&rsquo; high concentrations on the <i> Modeling</i> strategy. </p><p> The last research question was to identify the differences of cognitive problem-solving patterns by design tasks. The study analyzed eight engineering design tasks and each task pooled six CTA sessions. The results confirmed that higher graders&rsquo; design tasks showed more complicated design pathways than younger graders&rsquo; design tasks. Additionally, the researcher found that each design task yielded distinct problem-solving pattern models. </p><p> Based on these results, the researcher suggested that engineering and technology educators need to highlight the multiple pathways of the engineering design process. The results showed many alternative problem-solving pathways rather than the standardized process models. The researcher also proposed that when adopting an engineering design approach in elementary curriculum, the program developers need to align its design procedure with learners&rsquo; sequential patterns of the design process. Engineering design problems provide rich opportunities to develop the cognitive abilities of young students. Additionally, the researcher encourages engineering and technology education programs to adopt multiple design process models aligned with the corresponding design problem types.</p><p>

<p> From a sociocultural point of view, this qualitative case study explored how upper-level, female undergraduate engineering students perceived the possibility of or experience with stereotype threat as shaping their experiences. The study also investigated how these students explained their reasons for choosing their engineering major, the challenges they encountered in the major, and their reasons for persevering in spite of those challenges. Using Steele and Aronson&rsquo;s (1995) stereotype threat theory as a framework, and considering the documented underrepresentation of females in engineering, the study sought to examine how stereotype threat shaped the experiences of these students and if stereotype threat could be considered a valid reason for the underrepresentation. </p><p> The study was conducted at a large, four-year public university. First, students in the College of Engineering and Engineering Technology completed the Participant Screening Survey. Based on responses from the survey, six female engineering students from the college were identified and invited to participate in the study. The participants came from the following majors: Electrical Engineering, Industrial and Systems Engineering, and Mechanical Engineering. After receiving the study consent letter and agreeing to participate, the students were involved in a 90-minute focus group meeting, a 45-minute one-on-one interview, and a 30-minute follow-up interview. </p><p> After conducting the data collection methods, the data were then transcribed, analyzed, and coded for theme development. The themes that emerged coincided with each research question. The themes highlighted the complex interactions and experiences shared by the female engineering majors. </p><p> The female students were enveloped in an environment where there existed an increased risk for activating stereotype threat. In addition, the female students described feeling pushed to prove to themselves and to others that the negative stereotype that &lsquo;females are bad at engineering&rsquo; was untrue. The findings illustrated the need for systematic changes at the university level. Intervention recommendations were provided. In regards to female underrepresentation in science fields, including engineering, stereotype threat certainly had the potential to cause the female students to question themselves, their abilities, their choice of an academic major, and subsequently remove themselves from a hostile learning or working environment. Thus, educational institutions and workplace organizations are responsible for not only educating themselves regarding stereotype threat, but also for taking steps to alleviate the pernicious effects of stereotype threat.</p><p>

Two manifolds were designed to determine phosphate concentrations. The linear range for the 2-channel manifold was 0 to 30 mg L-1, and that for the 3-channel manifold was 0 to 400 mg L-1. Optimized conditions for the determination of arsenic with molybdenum-blue method were 0.5% w/v ascorbic acid, 0.4 M sulfuric acid in the molybdate solution and 80°C reaction temperature. A method for determination of arsenic using pervaporation flow injection hydride generation with visible spectrophotometry was developed. The method was sensitive for low arsenic concentrations (≤ 10 μg L-1), with sensitivity decreasing as arsenic concentration increased. There was no heating required, and the pervaporation membrane transferred only arsine. The analytical performance of two arsenic test kits was assessed. The Alpha Environmental kit cannot be recommended for arsenic measurement in water. The Hach kit was reliable for measuring arsenic concentrations greater than 70 μg L-1. A modified reaction tube was constructed that allowed NaBH4 solution to be delivered into the reaction mixture to replace zinc powder in the Hach kit, with no loss of gases. A more quantitative way of measuring arsenic using the Hach kit was developed by measuring the B-value of the color of jpeg images of test strips taken by a desktop scanner. Leersia oryzoides grown in soil amended with 110 mg kg-1arsenic extracted up to 305 μg g-1 and 272 μg g-1 arsenic into its shoots and roots respectively, giving a shoot:root quotient (SRQ) of 1.12 and phytoextraction coefficients (PEC) up to 1.3 in greenhouse experiments. Five supervised arsenic-related projects were reported. All except one of these reports fell short of the standards acceptable for a publishable manuscript. Factors such as high expectations, competitive entrance requirements and good motivation were responsible for the publishable report. For the remaining reports, problems with working in a team, relatively low expectations and lack of motivation were responsible. A laboratory-based research subject was successfully investigated in middle school classrooms. The program had been run for four consecutive years. Collaboration with the classroom teacher ensured that the program agreed with the school curriculum. All participants recommended continuation of this program.

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<p>The dramatic underrepresentation of Alaska Natives in science, technology, engineering and mathematics (STEM) degrees and professions calls for rigorous research in how students access these fields. Research has shown that students who complete advanced mathematics and science courses while in high school are more academically prepared to pursue and succeed in STEM degree programs and professions. There is limited research on what motivates precollege students to become more academically prepared before they graduate from high school. In Alaska, Alaska Native precollege students regularly underperform on required State of Alaska mathematics and science exams when compared to non-Alaska Native students. Research also suggests that different things may motivate Alaska Native students than racial majority students. Therefore there is a need to better understand what motivates Alaska Native students to take and successfully complete advanced mathematics and science courses while in high school so that they are academically prepared to pursue and succeed in STEM degrees and professions. </p><p> The Alaska Native Science &amp; Engineering Program (ANSEP) is a longitudinal STEM educational enrichment program that works with Alaska Native students starting in middle school through doctoral degrees and further professional endeavors. Research suggests that Alaska Native students participating in ANSEP are completing STEM degrees at higher rates than before the program was available. ANSEP appears to be unique due to its longitudinal approach and the large numbers of Alaska Native precollege, university, and graduate students it supports. ANSEP provides precollege students with opportunities to take advanced high school and college-level mathematics and science courses and complete STEM related projects. Students work and live together on campus during the program components. Student outcome data suggests that ANSEP has been successful at motivating precollege participants to successfully complete advanced high school and college-level mathematics and science courses prior to high school graduation. </p><p> This study was designed to examine the motivations of Alaska Native high school students who participated in the ANSEP Precollege components to take advanced mathematics and science courses in high school or before college. Participants were 30 high school or college students, 25 of whom were Alaska Native, who were currently attending or had attended Alaska Native Science &amp; Engineering Program (ANSEP) Precollege components in high school. Self-determination theory was used as this study&rsquo;s theoretical framework to develop the semi-structured interview questions and also analyze the interviews. A thematic approach was used to analyze the interviews. The results of this study indicated that ANSEP helped the Alaska Native high school students gain a sense of autonomy, competence, and relatedness in order to be motivated to take advanced mathematics and science courses in high school or before college. In particular, Alaska Native high school students described that relatedness was an important element to them being motivated to take advanced mathematics and science courses. More specifically, participants reported that the Alaska Native community developed at the ANSEP Building and the relationships they developed with their Alaska Native high school peers and staff played an influential role in the motivation of these students. These findings are important because research suggests that autonomy and competence are more important elements than relatedness because they generate or maintain intrinsic motivation. Alaska Native high school students reported that ANSEP was more successful in helping them gain a sense of competence and relatedness than at helping them gain a sense of autonomy. More specifically, the reason the participants did not feel ANSEP developed their sense of autonomy was because ANSEP restricted their actions during the ANSEP Precollege study sessions. </p><p> My study implies that Alaska Native students need to feel like they belong in order to be motivated to take and succeed at taking advanced mathematics and science courses. Educators and STEM program leaders should incorporate elements of belonging into the educational environments they develop for their Alaska Native students. Future research should be conducted to determine if other racial minority students need to feel like they belong in order to be motivated to take and succeed at taking advanced mathematics and science courses. </p><p> My study also indicated that Alaska Native students were motivated to take advanced mathematics and science courses by knowing ANSEP would support them in future programming because of its longitudinal approach. Funding agencies of STEM programs should consider funding programs that provide a longitudinal approach to help Alaska Native students&rsquo; sense of competence grow. Future research should include studying other STEM programs to determine if they are motivating their students to take and succeed in advanced mathematics and science courses. </p>

Titanium and its alloy (Ti-6Al-4V) are widely used in aerospace industries because of their light weight, high specific strength, and corrosion resistance. This study conducted a comparative experimental analysis of the machinability of Ti-6Al-4V for conventional flood coolant machining and sustainable dry machining. The effect of cutting speed, feed rate, and depth of cut on machining performance has been evaluated for both conditions. The machining time and surface roughness were found to be lower in dry machining compared to flood coolant machining. The tool wear was found to be unpredictable, and no significant difference was observed for dry and coolant machining. In a comparison of all the parameters, sustainable dry machining was found to provide better performance in machining Ti-6Al-4V. This study also investigated the machinability of Ti-6Al-4V using coated and uncoated tungsten carbide tools under dry conditions. Tool wear is a serious problem in the machining of titanium alloys in dry conditions. Heat dissipation from the toolworkpiece interface a difficult challenge in dry machining, resulting in the alloying of the workpiece to the tool surface. Dry machining with the coated tool was comparatively faster, and resulted in less tool wear than uncoated tools. Using the Titanium aluminum nitride TiAlN coated carbide tool during dry machining provided a smoother surface finish with lower average surface roughness. The conclusion, therefore, is that the tool coating was found to be effective for the dry machining of titanium alloys.