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Micropropagation of Douglas Maple (Acer glabrum Torr. var. douglasii Hook. Dipple [Aceraceae])
No full textDouglas maple (Acer glabrum Torr. var. douglasii Hook. Dipple [Aceraceae]) is a potentially valuable landscape species with significant propagation issues. Micropropagation has potential to resolve these issues and allow production of marketable plants at commercial quantities. A research project was initiated to refine procedures for successful tissue culture multiplication of Douglas maple. A series of experiments were designed to optimize factors that impact propagation efficiency and efficacy, including: explant establishment, cytokinin type and concentration for enhancing multiplication, length of subculture period, explant density in culture, light intensity, nutrient formulation of culture medium, rooting methods and their effect on acclimatization, and auxin type and concentration for rooting explants. Establishment (decontamination and initiating shoot growth) was accomplished by surface sterilizing explants with a 20% bleach solution (v/v) and then culturing on medium made with DKW medium salts and zeatin. This surface sterilization method resulted in 46% contamination-free explants and many shoots. Cytokinin compound and concentration optimization was conducted to maximize shoot growth during multiplication. Three experiments were conducted, in which, benzyl-adenine (BA), kinetin, meta-topolin (MT), thidiazuron (TDZ) and zeatin were all tested at various concentrations. The cytokinin concentration and compound producing the longest average shoots (39 mm (1.54 in) in a 31 day subculture was 2 µM MT. An experiment testing shoot growth rates was conducted to optimize subculture length. Two different genotypes were tested over 6 weeks in culture. The shoot growth of the fastest growing genotype was modeled linearly by Y = (1.456) X – 7.937, where X = days in culture, and Y = shoot length (mm), indicating that a subculture of 6+ weeks is best for resource and time efficiency. An explant density experiment was conducted to maximize resource efficiency. Explant densities at 4, 6 and 8 explants per tissue culture vessel (GA-7) failed to significantly affect shoot length, number of nodes or dry weights, meaning 8 explants per vessel is likely more efficient. A light intensity experiment tested 3 light intensities (7, 17 and 37 µmols•m-2•s-1 (0.65, 1.58 and 3.44 µmols•ft-2•s-1) photosynthetic photon flux) for their effect on shoot health. The highest and lowest light intensities were significantly different from each other in average dry weight (lowest light treatment had lowest weight), and plants exposed to the highest light intensity exhibited interveinal chlorosis. Deficiency symptoms such as chlorosis and shoot tip necrosis of Douglas maple plantlets grown on Driver Kuniyuki Walnut (DKW) medium salts prompted nutrient experimentation. Informal experimentation with 2x iron (relative to Fe content in DKW medium salts) remediated the chlorosis issue. Standard commercial salts (DKW, Murashige and Skoog (MS) and Woody Plant Medium (WPM) medium salts) with supplemental iron were tested for their ability to rapidly grow shoots, increase node number, and increase dry weights. The DKW medium was statistically superior at promoting shoot growth and the most number of nodes. Another experiment tested various fortifications to DKW medium with supplemental iron and was primarily focused on remediating the shoot tip necrosis. Additional boric acid (12.0 mg/l (0.0016 oz/l)) significantly improved shoot length (51 mm (2.01 in)) in comparison to control DKW medium with supplemental iron (29 mm (1.14 in)), and also reduced necrosis issues over time. A final nutrient experiment tested whether nutrient ratios within Acer glabrum sap were appropriate for formulating medium. The sap nutrient ratio medium performed slightly worse than the other control treatments included in this experiment, but not statistically worse. Sap-based nutrient ratio formulation showed potential, though much experimentation is still needed to improve the methods and strategies. In vitro and ex vitro rooting procedures were tested for their ability to root high percentages of explants, and to efficiently acclimatize plantlets. The in vitro rooting factors tested were: auxin type (indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or both in combination), light vs dark, apical vs nodal explants, half vs full strength DKW medium salts, IBA concentration (0, 1, 2, 4 and 8 µM), and the length of the explant (2.0 to 3.0 cm (0.79 to 1.18 in), or 3.5 to 4.5 cm (1.38 to 1.77 in)). The best in vitro rooting treatment, which was 1 µM IBA in half-strength DKW regardless of explant length, yielded 75% survival after rooting and acclimatization. Ex vitro rooting treatments included explant length as a covariate and a treatment (concentrations of IBA (0.1 and 0.3%) in talcum based rooting powders, and a control (water) group). The most successful treatments were 0.1 and 0.3% IBA talcum powder, both yielding a 92% survival rate after rooting and acclimatization. Ex vitro rooting methods were deemed better because of better time and resource efficiency (1 month of vitro culture subtracted), and higher survival rates after rooting and acclimatization. A second ex vitro experiment involving another Douglas maple genotype further validated the effectiveness of ex vitro rooting using 0.1% IBA talcum powder. Overall, these experiments have optimized micropropagation methods such that an estimated 12 fold multiplication of explants can be achieved every 6 week subculture, and only 8% of plantlets fail to survive after the rooting and acclimatization stages.masters, M.S., Plant, Soil and Entomological Sciences -- University of Idaho - College of Graduate Studies, 2019-1
Inter-disciplinary approaches in food safety to expand mycotoxin detection, compare bacterial transfer rates, and forecast fungal inoculum under climate change
No full textFood safety research is complex and interdisciplinary as it involves considerations from pre-production through final home preparation of a food product which passes a long chain of food processing where each stage has potential opportunities for the contamination. The aim of this dissertation was to develop novel methods which could generalize to future food safety issues regarding contamination. This goal was approached by (1) extending a protocol for detection of ochratoxin A into food matrices where phenolic compounds are present, (2) investigation into how bacterial transfer is affected by both hand washing and glove use, (3) interpreting sources of variability in a fungal inoculum source capable of producing deoxynivalenol, and (4) forecasting future shifts in fungal inoculum under climate change. Ochratoxin A (OTA) is a fungal metabolite and putative carcinogen which can contaminate a variety of foods such as cereals, wine, and nuts. Commercial ELISA kits are known to give false-positive results for OTA concentrations when phenolic compounds are present. Pistachios represent a food matrix rich in phenolic compounds potentially contaminated with OTA, and polyvinylpolypyrrolidone (PVPP) was incorporated during extraction of OTA using a commercial ELISA protocol. HPLC methods were used to confirm that PVPP does not interact with OTA and the cross-reactivity of extracts also decreased with increasing PVPP application. To assess bacterial transfer from hands to gloves and to compare bacterial transfer rates to food with different soap washing times and glove use, participants’ hands were artificially contaminated with a ~109 CFU inoculum of Enterobacter aerogenes B199A. Different soap rubbing times (0, 3, and 20 s), glove use, and tomato dicing activities were followed. Different soap rubbing times did not significantly change the amount of bacteria recovered from participants’ hands. Both glove use and adequate hand washing are necessary to reduce bacterial cross-contamination as increasing soap washing time decreased the incidence of bacterial contamination recovered from outside glove surfaces (p < 0.05) and dicing tomatoes with bare hands after 20 s of soap rubbing transferred significantly (p < 0.01) less bacteria to tomatoes compared with bare hands after 0 s of soap rubbing. The plant pathogen Fusarium culmorum represents an inoculum source capable of contaminating grains with deoxynivalenol (DON) in the Inland Northwest (INW) region of the United States. A multilevel modelling approach utilizing varying intercepts for different sampling quadrats, fields, and iterations in the dataset was performed to characterize variability in isolation frequency of F. culmorum collected during a two-year soil survey. Differences in the isolation frequency of F. culmorum varied the most by sampled field followed by quadrat and iteration, respectively. Higher relative elevation within the sampling region of a field limited the amount of F. culmorum recovered. Isolation records were extended to incorporate the soil dilution factor and used to construct a multilevel climate model. Varying intercepts and slopes were assigned to each unique agricultural field and a weather-based proxy for soil moisture, termed atmospheric water balance (AWB) was used as a predictor variable. Values of AWB derived from downscaled global climate models were used to forecast future shifts in the proportion of F. culmorum across all sampled fields. Population densities of F. culmorum are forecasted to remain constant during the winter and spring but decrease over the summer and fall under climate change, with the magnitude differing across fields.doctoral, Ph.D., Food Science -- University of Idaho - College of Graduate Studies, 2019-1
An Analysis of the Nuclear Characteristics of a Molten Salt Microreactor
No full textThis work evaluates several neutronics-related performance characteristics of a proposed molten salt micro-reactor. The Molten Salt Nuclear Battery is a liquid fuel molten salt system designed to be entirely self-contained, circulate the fuel and salt through natural convection, and provide 10 MW of thermal power for up to 10 years of continuous operation. Areas of investigation include candidate neutron reflecting and absorbing materials, control rod design and optimization, criticality control, neutron flux profile characterization, reactor operation and fuel burnup, fission product production, and radioactive dose in close proximity following shutdown. The primary means of investigation was simulation with the MCNP and ORIGEN codes. The analysis shows that the proposed design can meet the desired operational parameters and that control of the reactor is achievable with the optimized control rods, while also quantifying other essential nuclear characteristics. Assumptions and simplifications used in the simulations and the avenues of further research are discussed.masters, M.S., Nuclear Engineering -- University of Idaho - College of Graduate Studies, 2019-0
MAGNETIC RESONANCE IMAGE-BASED NUMERICAL MODELING OF CEREBROSPINAL FLUID DYNAMICS: APPLICATION TO FILTRATION AND INTRATHECAL DRUG DELIVERY
No full textCerebrospinal fluid (CSF) plays a vital role in the immunological support, structural protection and metabolic homeostasis of the central nervous system (CNS). The CSF is a promising route with many potentially important roles for CNS therapeutics such as: a) direct delivery of large drug molecules to the CNS tissue that is not possible via blood injection due to the blood brain barrier and b) CSF filtration, termed Neurapheresis therapy, to remove unwanted solutes in CNS diseases such as alzheimer’s disease, meningitis, subarachnoid hemorrhage and leptomeningeal metastasis. While many studies have shown increasing importance of the role of CSF in CNS system homeostasis, there is a need to understand the impact of realistic geometry on CSF flow patterns. An anatomically accurate and validated CFD model will allow testing and optimization of CNS biomedical technologies such as CSF filtration devices. Such a simulator could reduce cost of non-human primate studies and lead to more rapid application of these technologies for clinical use. In this dissertation, CSF dynamics in monkeys and humans was investigated in four stages as following: First, a magnetic resonance imaging (MRI) protocol was developed and applied to quantify subject-specific CSF space geometry and flow and define the CFD domain and boundary conditions in non-human primates. An algorithm was implemented to reproduce the axial distribution of unsteady CSF flow by non-uniform deformation of the dura surface. Results showed that maximum difference between the MRI measurements and CFD simulation of CSF flow rates was <3.6%. CSF flow along the entire spine was laminar with a peak Reynold’s number of ~150 and average Womersley number of ~5.4. Maximum CSF flow rate was present at the C4-C5 vertebral level. Deformation of the dura ranged up to a maximum of 134 μm. Geometric analysis indicated that total spinal CSF space volume was ~8.7 ml. Average hydraulic diameter, wetted perimeter and SAS area was 2.9 mm, 37.3 mm and 27.24 mm2, respectively. CSF pulse wave velocity along the spine was quantified to be 1.2 m/s. Second, a geometric and hydrodynamic characterization of CSF in eight cynomolgus monkeys (Macaca fascicularis) was presented at baseline and two-week follow-up. Results showed that CSF flow along the entire spine was laminar with a Reynolds number ranging up to 80 and average Womersley number ranging from 4.1-7.7. Maximum CSF flow rate occurred ~25 mm caudal to the foramen magnum. Peak CSF flow rate ranged from 0.3-0.6 ml/s at the C3-C4 level. Geometric analysis indicated that average intrathecal CSF volume below the foramen magnum was 7.4 ml. The average surface area of the spinal cord and dura was 44.7 and 66.7 cm2 respectively. Subarachnoid space cross-sectional area and hydraulic diameter ranged from 7-75 mm2 and 2-3.7 mm, respectively. Stroke volume had the greatest value of 0.14 ml at an axial location corresponding to C3-C4. The third objective of this dissertation was to investigate the impact of spinal cord nerve roots (NR) on CSF dynamics. A subject-specific computational fluid dynamics (CFD) model of the complete spinal subarachnoid space (SSS) with and without anatomically realistic NR and non-uniform moving dura wall deformation was constructed. This CFD model allowed detailed investigation of the impact of NR on CSF velocities that is not possible in vivo using MRI or other non-invasive imaging methods. Results showed that NR altered CSF dynamics in terms of velocity field, steady-streaming and vortical structures. Vortices occurred in the cervical spine around NR during CSF flow reversal. The magnitude of steady-streaming CSF flow increased with NR, in particular within the cervical spine. This increase was located axially upstream and downstream of NR due to the interface of adjacent vortices that formed around NR. Average value for steady streaming velocity was 0.11 ± 0.12 and 0.05 ± 0.04 mm/s (mean ± stdev) for the model with versus without NR (120% greater with NR). The region of greatest difference in steady streaming velocity values was the cervical spine that had up to 5X larger value of steady streaming velocity with NR compared to without. In fourth step, we formulated a subject-specific computational fluid dynamics (CFD) model to parametrically investigate the impact of a novel dual-lumen catheter-based CSF filtration system, the Neurapheresis therapy system (Minnetronix Neuro, Inc., St. Paul, MN), on intrathecal CSF dynamics. The operating principle of this system is to remove CSF from one location along the spine (aspiration port), externally filter the CSF routing the retentate to a waste bag, and return permeate (uncontaminated CSF) to another location along the spine (return port). The CFD model allowed parametric simulation of how the Neurapheresis system impacts intrathecal CSF velocities and steady-steady streaming under various Neurapheresis flow settings ranging from 0.5 to 2.0 ml/min and with a constant retentate removal rate of 0.2 ml/min. simulation of the Neurapheresis system were compared to a lumbar drain simulation with a typical CSF removal rate setting of 0.2 ml/min. Results showed that the Neurapheresis system at a maximum flow of 2.0 ml/min increased average steady-streaming CSF velocity 2X in comparison to lumbar drain (0.190 ± 0.133 versus 0.093 ± 0.107 mm/s, respectively). This affect was localized to the region within the Neurapheresis flow-loop. The mean velocities introduced by the flow-loop were relatively small in comparison to normal cardiac-induced CSF velocities. Finally, a subject-specific multiphase CFD model was constructed based on high-resolution anatomic MRI. The dual-lumen Neurapheresis catheter geometry was added to the model within the posterior spinal subarachnoid space (SAS). Neurapheresis flow aspiration and return rate was 2.0 and 1.8 (mL/min), versus 0.2 (mL/min) drainage for lumbar drain. An in vitro CSF model was constructed with an identical fluid domain geometry. A detailed comparison of numerical and in vitro results was performed by the Bland-Altman correlation analysis. Neurapheresis therapy was found to have a larger impact on steady streaming in comparison to lumbar drain. Steady-streaming in the cranial SAS was ~50X smaller than in the spinal SAS for both cases. Results showed that 85% of the spinal SAS was cleared within one hour with the Neurapheresis flow loop in comparison to 50% clearance after 24-hour with lumbar drain. Clearance was maximized between the aspiration and the return ports with the Neurapheresis therapy. However, intracranial clearance for the Neurapheresis therapy was similar to lumbar drain (66% clearance). Quantitative comparison of Neurapheresis therapy results showed that the speed of clearance match with less than 4% error after 24-hour (50% CFD vs 46% in vitro).doctoral, Ph.D., Biological & Agricultural Engineering -- University of Idaho - College of Graduate Studies, 2019-1
Perceptions of Social Media Use by Idaho Educators: Information for Policy Development
No full textThe purpose of this study was to gather perceptions from Pre K-12 public school educators in Idaho regarding their social media use and their opinions about social media use policy. The results of the study were intended to provide educational leaders in Idaho with information to facilitate policy development or revision. A survey was designed using Survey Monkey. Survey items were developed during the literature review and piloted before hand. These items were categorized as social media use for education, social media policy development, and balance between administrative control and individual rights. The survey was distributed to large, medium, and small school districts from Northern, Central, and Southern Idaho. Five hundred and two people completed the survey in its entirety. Data was then organized and analyzed though the lens of each demographic allowing for comparisons to be made and patterns to be identified. The demographics included sample totals, geographical regions of Idaho divided into three areas (North, Central and South), the sizes of the districts that participated (Small, Medium and Large), grade level work assignments of participants (Elementary K-5, Middle School 6-8, High School 9-12, District Office Employees), and social media use by participants (those that use social media, those that use it sporadically, and those that did not use social media). Results should be applied as representation of the larger population of Idaho educators with caution. However, from those that participated in the study there were clear results of the distinct perceptions between digital natives and digital immigrants, the identified need for training, the tension that exists between administrative control and individual liberties, and perceptions of what should be included in a social media policy.doctoral, D.Ed., Leadership and Counseling -- University of Idaho - College of Graduate Studies, 2019-1
The impact of starch on wheat falling number and the evolvement of starch structure in the developing endosperm of soft white winter wheat
No full textThe United States Pacific Northwest is known to produce premium soft white wheat with consistent quality; however, the unexpected low falling number issue resulted in a 140 million loss in 2014 and 2016, respectively. Wheat with a low falling number is considered poor-quality due to the elevation of α-amylase activity, which leads to a quick liquefaction of starch and decreases flour paste viscosity. The primary causes of low falling number are pre-harvest sprouting and late maturity α-amylase, both triggered by unusual weather pattern (e.g. pre-harvest rain and temperature shock). We hypothesize that weather impacts starch structural development and influences starch functionality (e.g., viscosity). Our previous study supports this hypothesis and reveals a starch developmental change in some low falling number wheat. To identify a solution for the low falling number issue, we conducted a comprehensive review (Chapter 1) regarding the impact of starch and its interaction with other molecules on wheat falling number, which lead to another hypothesis that plant growing conditions play an important role in influencing starch structure evolvement. However, it was difficult to directly identify how environmental stress triggers the starch structural changes because it is not known how starch structure evolves during grain development in soft white wheat. Thus, we conducted a study to close this knowledge gap, and we investigated the evolvement of starch structure in developing kernels (Chapter 2). We systematically measured starch structural characteristics, including starch content, starch granule size distribution, the ratio of amylose to amylopectin, the development in the structure of amylopectin, and starch gelatinization temperature and enthalpy change. We divided the development of starch structure into three stages: the initial stage (Day 7 to Day 10 after anthesis), rapid accumulation stage (Day 14 to Day 28 after anthesis), and the maturity stage (Day 35 to Day 42 after anthesis). During the rapid accumulation stage, starch quantity increased rapidly, starch granule size distribution became a bimodal distribution, and starch crystalline structure gradually became more organized. After the plant reached physiological maturity (Day 35 after anthesis), starch structure continued developing during the starch maturity stage. Our findings suggest that when environmental stress occurs during the rapid accumulation stage, it can critically change starch structure and impact starch functionality. Future work to identify the genetic controls of the development of starch structure during the rapid accumulation stage will be helpful to develop a new wheat variety with a high resistance to weather changes and may help solve the low falling number issue.masters, M.S., Food Science -- University of Idaho - College of Graduate Studies, 2019-0
Process-Structure Linkages in Materials via Deep Learning from Phase-Field Simulation Data
No full textMaterial microstructure is key to understanding processing-structure-property relationships. However, limitations in computational descriptions of microstructure present a challenge in being able to predict property changes under noisy processing conditions. Correctly modeling microstructure and being able to produce reliable material property predictions would enable efficient strategies for material optimization. Such strategies are shown to drastically reduce the amount of experiments needed to reach an optimal material. This in turn would decrease the time to market required to develop new materials, a key goal of the material genome initiative. In this work, a general mechanism for linking processing, structure, and properties is developed through the use of Deep Learning. Two separate models have been developed. The first model, the encoder-decoder model, is used to link processing conditions to microstructure, while the second model, the predictor model, is used to predict material properties given the current material microstructure. The trained encoder-decoder model is shown to predict the non-trivial evolution of ferroelectric domains in bi-crystalline lead titanate perovskites. In addition to small constant inputs such as the processing temperature, the encoder-decoder can account for spatial input conditions, such as the arrangement of grains in a polycrystalline material. The predictor model uses the ferroelectric microstructure to predict the ferroelectric switching constant, the coercive field. It is demonstrated that the predictor model is able to model the coercive field property using only the microstructure with a similar level of accuracy as state-of-the-art machine learning methods that have been trained directly on input processing conditions. Even if the input conditions are unknown or noisy, the microstructure can often be observed accurately. Further, the model has been demonstrated on more complicated environments with stochastic poly-crystalline systems. It is shown that the model is able to sufficiently capture and reproduce key characteristic features of the microstructure, despite never being explicitly programmed to do so. The overall volume fractions of domains is maintained, the formation of domain walls occur along directions expected analytically, and the polarization is reduced along grain boundaries in the presence of a secondary phase.masters, M.S., Chemical and Materials Science Engineering -- University of Idaho - College of Graduate Studies, 2019-0