Texas A&M University-Kingsville: AKM Digital Repository
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Evaluation of natural browse fiber sources in Spanish X Boer kid goat diets and supplemental pellets for white-tailed deer
No full textLivestock feeding and wildlife supplementation can be costly. Environmental or economic changes often coincide with inflated cost of feed ingredients. During these times, new or novel ingredients are often sought. As well, the unintended loss of wildlife supplements to non-target species can be financially cumbersome. Juniperus spp. (juniper), an invasive, woody plant species, is found on rangelands throughout the western U.S. Juniper is currently available year-round and cost stable compared to other feed ingredients that fluctuate depending on environmental and marketing conditions. I evaluated the use of ground juniper in Spanish × Boar kid goat diets and supplemental pellets for white-tailed deer (Odocoileus virginiaus).
I used Boer × Spanish kid goats to evaluate the effects of ground woody products in feedlot diets on growth performance and blood serum chemistry. Goats were fed 1 of 6 diets that differed by roughage source: cottonseed hulls or ground wood consisting of redberry, blueberry, one-seed, eastern red cedar Juniperus spp., or Prosopis glandulosa. Collectively, results suggested that ground Juniperus pinchotii, J. ashei, or J. monosperma could effectively be used to completely replace cottonseed hulls in goat feedlot diets
The cloning and expression of C-type lectin-like proteins isolated from the venom gland cDNA library of the Southern Pacific Rattlesnake (Crotalus oreganus helleri, Meek 1905)
No full textAmong the various non-enzymatic constituents of snake venom, those belonging to the C-type lectin superfamily have demonstrated diversity in biological function despite maintaining significant structural homology. Although a vast array of information regarding the hemostasis activities of snake venom C-type lectin-like proteins is available, research regarding cell culture studies is limited. Five unique sequences (CLP-IJ03, CLP-3P09, CLP-3C13, CLP-1K15, and CLP-6A07) encoding Ctype lectin-like proteins were selected from a cDNA library produced from the venom gland of Crotalus oreganus helleri (COH). Because of the intricate nature of many snake venom proteins, a unique expression system was utilized to express these proteins in E. coli. The expression system consisted of the ligation of one of the five genes (CLP-1J03) into the pGEX4T-1 plasmid followed by its co-expression with a chaperone plasmid (pTf16, Takara Bio Inc.) in Origami 2 competent cells. The recombinant protein was expressed and purified using affinity chromatography, verified by Western Blot analysis. The recombinant protein (10μg) had an inhibitory effect of approximately 74% and 36% with and without the GST tag, respectively, on platelet aggregation using whole blood. The native CLP was partially purified from crude venom using a two-step fractionation procedure consisting of anion exchange followed by cation exchange
CFD analysis of the NBSR thermal shield
No full textThis research conducted thermal-hydraulic analysis on a thermal shield of the National Bureau of Standards Reactor (NBSR) using computational fluid dynamics (CFD) techniques with ANSYS 19.2. The NBSR thermal shield is a hollow, cylindrical water-cooled lead-steel structure surrounded by a biological shield made of heavy concrete. At full-power operating conditions, 210 kW of heat load deposits on the thermal shield. To prevent excessive heating of the shield, this heat must be extracted by a water-cooling system and convection with the surroundings. The thermal shield cooling system is comprised of 180 copper tubes (3/8 K type) running with water at 2 gal/min and with an inlet temperature of 308.15 K. Blocking of the coolant flow in embedded flow channels of the shield may cause the shield material to melt. To define the safe operating conditions of the nuclear reactor, the thermal shield model was examined across a range of flow rates with the maximum and minimum flow rates being 4 and 0.5 gal/min, respectively. With consideration of the creep temperature of lead as a threshold, from this research, it is determined that the maximum allowable number of consecutive tubes that can be blocked is 11.
The cooling performance of various water-based Al, Cu, Al2O3, CuO, SiO2, SiC, and TiO2 nanofluids was also studied, but the results showed that water was more effective than nanofluids in cooling the thermal shield. Further, a two-phase boiling analysis was carried out to predict the vapor formation in the shield cooling system, and it was observed that water started vaporizing in the shield’s upper-section tubes when the flow rate was reduced to 0.2 gal/min
Net load balancing-oriented PV solar-based microgrid optimal scheduling considering islanded and grid-connected
No full textThe term net load refers to system demand minus the generation from variable distributed renewable resources. To maintain the balance between variable renewable supply and demand, system should be sufficiently flexible to handle the net load fluctuations. Microgrids (MG) with their decentralized system operations offer solutions to the challenges posed by net load variability resulted from high penetration of renewable generation. Although MG deployment is rapidly growing, there are still many challenges to optimally operate MG when operating in gridconnected or islanded mode. This thesis proposes a net load-oriented MG optimal scheduling model to balance the MG net load considering both islanded and grid connected modes. The proposed optimization methodology is performed considering the net load variation for eight intraseasonal representative days. Case studies demonstrate the effectiveness of the proposed methodology in both grid-connected and islanded modes
Catalytic activity of a new gold(I) complex for alkyne hydrofunctionalization reactions
No full textGold catalysis is gaining increasing importance in synthesis of drugs and natural products. To use gold catalysis as an efficient synthetic tool, the catalyst structure needs to be optimized f or the specific synthetic task. For the rational catalyst design, mechanistic studies are required. Al so ligand structures need to be tailored for new synthetic targets. During the last two decades, numerous gold(I) complexes of the general type LAuX have been developed for a number of alkene and alkyne functionalizations. The ligand X represents typically halides or another ani on such as triflate or a methyl group. There are two types of ligands employed for gold(I)catalyst complexes: phosphines and N- heterocyclic (NHC) ligands.
The phosphine and N-heterocyclic (NHC) ligands possesses different π-acceptor and σ- donor properties and cause distinct selectivity and catalyst stability. Recently, we have developed the synthesis of a new type of gold(I)complex [Au(PPO)Cl ] containing a diphosphine monoxide ligand (PPO). A X- ray structure analysis of this s gold(I) complex reveals the diphosphine ligand is coordinated like a monodentate phosphine, while the oxygen of the phosphine oxide moiety forms a weak int eraction with the gold center. The new gold complex was tested previously f or catalytic activity in alkyne hydration, which shows similar activity to that of nitrogen acycli
A comparative study on solid waste management methods used in the US and Nigeria
No full textSolid waste management practice is a major public health concern because of potential risk to health and the environment if not properly handled. It could be more problematic if the designated governmental bodies do not enact laws to encourage proper waste management practices. This study investigated the differences in solid waste management processes in the United States and Nigeria. Data was collected from the US and Nigeria’s environmental protection agencies, World Bank Global Database (2018), and other relevant studies. The areas
of interest in data collection were; recycling methods, waste separation, energy recovery, and collection and disposal methods. Both descriptive and inferential data analysis methods were used to help analyze and interpret the data using Microsoft Excel.
The t-test analysis conducted to test whether at, α = 0.05 showed significant differences in waste generation and composition in both countries showed as expected. The findings concluded that the US produces more paper waste which are easily recycled and composted and therefore, explains the reason US manages waste better than Nigeria. The rates of solid waste collection also differed significantly between the US and Nigeria. Recommendations to reduce waste from source and to improve the government’s waste legislation can help improve management in Nigeria
Enacting discourses of tutorship: an ethnographic journey
No full textThroughout history, universities have searched for ways to guide students through their studies (Canales Rodríguez & García Robelo, 2015). Indeed, “universities nowadays market themselves with arguments pertaining to…--intensive tutoring…and so on” (Blommaert, 2005, p. 133). In some universities, discourses of companionship frame the construction of co-responsibilities for tutor and tutee (Canales Rodríguez & García Robelo, 2015). Tutors also draw on discourses of “normative validity” (Blommaert, 2010, p. 35); Blommaert illustrates this with an imagined interaction between a tutor (T) and a student (S) where, as Blommaert (2010) argues, “the tutor performs a scale-jump here, in which he moves from the local and situated to the translocal and ‘general’:
“S: I’ll start my dissertation with a chapter reporting on my fieldwork.
T: We start our dissertations with a literature review here” (p. 35)
The capabilities of tutors are often evaluated by judgmental discourses in and around social and communicative skills that include discourses of appropriacy and inappropriacy. Moreover, the enactment of care for their students and their students’ problems, as well as a critical attitude when offering constructive solutions to real-world challenges are additional discourses attributed to tutors (García González & Troyano Rodríguez, 2009).
My research is autoethnographic. I discuss, explore, and analyze tutoring discourses and outcomes with respect to tutoring and the situated practices in tutorials, as well as how tutees and I—a tutor—construct discourses within and across tutoring sessions at a university in northeastern México. I also discuss, explore and analyze the discourses of the university’s Certification Course for Basic Tutor Training.
I collected the data from a group of thirty-one students in a teacher and translation preparation program during four tutorship sessions carried out in one semester from my classroom activities. I also collected data at the end of the semester with the support of a proxy tutor who facilitated a focus group.
There is no evidence that due to tutorship the number of dropouts has decreased; neither is there evidence that the graduation rate has increased. Nevertheless, there is evidence that by promoting caring human interaction, the learning environment in this study was an affirmative learning environment. It also appears that when I as a tutor stimulate human interaction as part of the class, students enjoy each other. These positive experiences create meaning at a university. I believe they have value; they humanize our students, and they humanize the university experience which might otherwise be disenfranchising.
Key words: discourses, tutor, tutorship/tutoring, situated practices, companionshi
Does the Texas primary reading inventory predict third grade reading State of Texas Assessment of Academic Readiness scores?
No full textThe state of Texas requires a reading inventory for all kinder, first, and second grades students, as well as the state assessment in reading for third grade. Educators face numerous challenges when attempting to teach children and meet the rigor on state assessments. In order for students to be successful on state assessments, teachers must ensure students learn to read and demonstrate comprehension. The purpose of this quantitative study is to identify if a relationship exists between the second grade end of year TPRI results and the third-grade reading STAAR test. The Metacognition Teaching Framework allows for the cyclic process and metacognitive reading strategies used when students are aiming to improve their reading skills. This research consisted of an analysis of the quantitative statistical prediction among the student's scores from second grade Texas Primary Reading Inventory (TPRI) and their scores the following year on the third grade reading assessment, State of Texas of Assessment of Academic Readiness (STAAR).
Bi- and multi-variate regressions were analyzed for predictor variables. A statistical significance was found in the multi-variate regression analysis indicating fluency, assessed on TPRI, is a predictor of 3rd grade reading ST AAR test scores. The findings have implications for students nationwide with similar demographics, but more importantly, for students in Texas who traditionally have limited studies that contribute to the predicative analysis utilizing historical archived data scores and ST AAR
Habitat, weather, and raptors as factors in the Northern-Bobwhite and Scaled-Quail population declines
No full textNorthern bobwhite (Colinus virginianus) and scaled quail (Callipepla squamata) have undergone range-wide declines over the last century. Much of the decline for each species can be attributed to loss of habitat, both directly through land conversion and indirectly through the deterioration of rangeland via woody cover encroachment, spread of invasive grasses, and overgrazing. As usable space for quail is lost, and particularly as it becomes fragmented, the influence of external factors such as weather and predation may exert a more profound effect on quail populations. I investigated multiple habitat relationships with bobwhites, specifically, at multiple scales. First, I utilized density surface models to evaluate the relationships between bobwhite density and woody cover metrics in 2 ecoregions of Texas where bobwhite populations remain relatively abundant. Bobwhite density decreased with increasing aggregation and amount of woody cover in both the Rio Grande Plains and Rolling Plains ecoregions, although bobwhite tolerated higher quantities of woody cover in the Rio Grande Plains. Second, I delineated bobwhite use of landscapes invaded by a native grass, tanglehead (Heteropogon contortus), in the Coastal Sand Sheet region of southern Texas. Bobwhite used areas with <20% of tanglehead, and strongly avoided areas with higher coverages at multiple scales. This avoidance is likely due to the strong influence of tanglehead at reducing vegetation characteristics important to bobwhite, specifically forb and grass species richness and functional bare ground. Lastly, I investigated the relative influence of land-use classes (i.e., habitat, cropland, urban areas), weather (i.e., temperature and precipitation), and raptor predation on both bobwhite and scaled populations at broad scales. In regions with extensive amounts of habitat, both bobwhite and scaled quail population indices were most influenced by annual weather patterns. Bobwhites showed a much more pronounced response to weather influences than did scaled quail, however. Altogether, both bobwhite and scaled quail populations are affected by habitat changes at multiple scales, and additionally driven by inter-annual fluctuations in weather patterns
Superintendents' perceptions of charter school effects on traditional public schools in South Texas
No full textThis case study gathered superintendent perceptions of the effect that charter schools had on traditional public school districts in the Rio Grande Valley of South Texas. The study drew perceptions from eight superintendents from across two counties in South Texas. Using qualitative research methods and acting as the human instrument, the researcher gathered, interpreted, and presented the participating superintendents’ lived-experiences, leading to a better understanding of superintendent perceptions of the effects that charter school presence had on their districts. The process of change as described by Fullan (2007) was used as a lens through which the data was analyzed. The study found that lived experiences by superintendents alluded to four major themes. First, competition by charter schools led to traditional public schools’ focus on improvement of their school districts. Second, charter schools’ market themselves effectively. Third, there is an appetite for choice with regard to schooling. And fourth, the most damaging effect is the decrease in enrollment in traditional public schools. Gaining clarity on superintendents’ perceptions informed a sometimes tenuous understanding of the relationships between charter and public schools and created a better informed response to the effect that charter schools have on traditional public schools