Texas A&M University-Kingsville: AKM Digital Repository
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Catalytic fast pyrolysis of Rio Red Grapefruit waste using shape-selective zeolites
No full textThe polymer and plastics industry has undergone rapid growth in the past few decades since these materials continue to displace the use of traditional materials, such as metal and wood, in a variety of applications due to their cost-effectiveness and superior performance. A majority of the resulting products find applications in the packaging sector. Currently, the key monomers used in the synthesis of polymers, such as benzene, toluene, ethylbenzene, and various xylene isomers (BTEX), are derived from fossil-based feedstocks. However, increasing socioenvironmental constraints levied on depleting fossil fuel reserves have provided the motivation for a shift towards clean and renewable feedstocks for the manufacture of these plastic precursors. Recent research in biomass conversion has shown that bio-based lignocellulosic feedstocks can be converted into the aforementioned aromatics over acidic zeolites via catalytic fast pyrolysis (CFP). The cost associated with transportation of bulk quantities of these bio-based feedstocks over long distances to compensate for its low energy density is one of the main hurdles in realizing a biomass pyrolysis process that is economically comparable to its fossil fuel counterpart. Utilization of locally generated agricultural residues and waste materials as feedstocks for CFP could significantly alleviate the costs associated with its transportation. The low-economic-value solid waste produced as a result of the processing of Rio Red grapefruit into juices is one such feedstock that can be utilized for CFP in Texas. However, the potential of Rio Red grapefruit waste (GPW) as a feedstock for CFP has not been previously studied using different catalysts. The development of robust CFP processes using GPW as feedstock necessitates a comprehensive understanding of the effect of its composition on product distribution, catalyst performance, and yields of target molecules. Consequently, a research opportunity exists to develop new experimental protocols to obtain novel data that could provide the basis for future efforts in catalytic material synthesis and reactor design. The primary goal of this research was twofold: (1) to identify the suitable zeolite frameworks and optimal reaction conditions for CFP of GPW that results in maximum yields of BTEX, and (2) to quantify the effect of CFP process conditions on the lifetime of selected zeolites. The results from this work provided the following new information: (i) optimal CFP process conditions for maximum yield of BTEX, over zeolites with different frameworks, were identified using response surface studies. Higher temperatures and longer reaction times maximized the yield of BTEX (ii) Elevated pressures resulted in maximum aromatic yields over small-pore zeolites, (iii) these experiments revealed that the medium-pore zeolites with pore-window diameters in the range of five to six angstroms result in optimal shape-selectivity towards aromatic molecules and exhibit longer catalyst lifetime. These findings will facilitate the development of robust biomass aromatization processes using Rio Red grapefruit waste as the feedstock
Coverage in wireless sensor networks: a survey
No full textWireless Sensor networks (WSNs) can be applied to our everyday lives from surveillance, military, healthcare to agricultural applications. In recent research a critical aspect of WSN is the sensor coverage problem, which has received attention from the research community due to the rapid advancement of technology and the need to expand coverage in WSNs.
In this research, coverage of wireless sensor networks is studied, a taxonomy for coverage is provided to classify research on coverage. The methods and algorithms from previous research were compared and classified using various metrics, such asscalability, energy efficiency, algorithm stability, network connectivity, deployment type and network reliability derived from extensive study of this research.
In this research, it could be determined that algorithms like TEEN and PEGASIS had the highest energy efficiency when using clustering techniques to maximize coverage. These algorithms are classified and compared with each other using metrics derived from this research. The metrics derived are ranked from good to poor and high to low, and the reason for the ranks are explained in the results
Salmonella enterica typhimurium and host microbiota compete for nutrients in physiologically relevant in vitro conditions
No full textSalmonella enterica Typhimurium is an enteric pathogen that causes acute gastritis and diarrhea in the host. Once past the stomach, Salmonella must survive numerous microenvironments in the lumen of the intestine prior to host cell invasion. As invasion occurs, the host responds with a robust inflammatory and cellular response. Throughout, Salmonella utilizes numerous virulence factors to invade and persist during the course of infection. Of these virulence factors, the flagella apparatus and Salmonella Pathogenicity Island -1 and -2 (SPI-1 and -2) are critical for invasion and survival within the lumen or inside the host epithelium. Here, we utilized gfp-reporter constructs and biorelevant media designed to mimic the host lumen conditions to identify environmental factors that induce expression of important virulence functions. Overnight cultures of S. Typhimurium were subcultured into biorelevant media with or without a mature gut flora, representing normal or inflamed intestinal lumen. Cell growth and gfp expression was monitored over a 24-hr time course. Our data indicates that the expression of flagellin (fliC), SPI-1 (invF), or SPI-2 (ssaG) was dependent on unique and specific conditions found in different microenvironments
Estimating White-Tailed deer population sizes using unmanned aerial vehicles
No full textTo successfully manage wildlife populations, estimates of population sizes, adult sex ratios, and recruitment are essential. Aerial surveys are often used to conduct surveys for large mammals; however, they can be expensive, hazardous, and not always practical for small properties. Camera surveys and spotlight counts are alternative survey methods but are labor intensive and generally less accurate. Unmanned aerial vehicles (UAVs) are a quickly growing technology that have yet to be fully evaluated for wildlife population surveys. I evaluated preliminary UAV surveys conducted by contractors on 4 study sites during October 2018 – February 2019 using white-tailed deer (Odocoileus virginianus) as the focal species to assess detection and identification using thermal infrared and red green blue (RGB) optical sensors. Heat signatures were detected on thermal imagery and then species identification was confirmed via RGB optical imagery. I found deer and exotic ungulates were able to be detected in the thermal imagery, however, imagery quality was variable, and identification was difficult. Furthermore, UAV flight specifications lacked consistency, which contributed to the poor image quality. I conducted test flights at a 5th study site and developed a protocol for use in South Texas in order to enhance imagery quality and consistency and address issues identified in preliminary surveys. Finally, I applied this protocol to surveys I conducted across all 5 study sites in February – April 2020. Surveys were repeated ≥ 2 times at each site to evaluate variation between surveys. Distance sampling analyses were applied to the raw count data to develop population estimate sizes. UAV survey results were then compared to estimates from helicopter (n = 4 sites), spotlight (n = 1 site), and camera surveys (n = 3 sites). I found UAV surveys to be a viable method of surveying white-tailed deer in South Texas and the use of distance sampling methodology is recommended over the use of raw count data. Estimates from UAV surveys were comparable to helicopter, spotlight, and camera survey estimates. Additionally, UAV survey estimates were consistent across repeated surveys. Through the use of distance sampling, a number of factors that impact detection probability were revealed including hot spots, hilly terrain, and a high percentage of herbaceous and bare ground. Additionally, determining sex identification from the optical imagery proved challenging and further survey protocol development is needed in order to utilize UAV surveys for calculating sex ratios. A secondary optical camera or conducting surveys when bucks are in velvet may enhance sex identification efforts
Grazing effects on forbs for White-tailed deer and plant species richness
No full textCattle (Bos spp.) grazing has been recommended as a tool to improve wildlife habitat, but available results are inconclusive and sometimes contradictory. Forbs are an important part of a white-tailed deer (Odocoileus virginianus) diet. Consumption of grass by cattle can potentially confer a competitive advantage to forbs resulting in increased forb standing crop. Forb standing crop is also strongly influenced by rainfall and soil properties. My objectives were to: 1) determine the relationship between grass disappearance resulting from herbivory and forb standing crop on the East Foundation ranches located in the Jim Hogg, Kenedy, Starr, and Willacy counties; and 2) determine how large ungulate grazing affected plant species richness. To evaluate cattle grazing effects on grass and forb standing crop and composition, I selected six 2,500 ha study sites located on the East Foundation ranches in south Texas. Fifty 1.5-m2 grazing exclosures were randomly placed in each of the six study sites. During the autumn growing season, I sampled vegetation within exclosures and at an outside paired point. I then stored the collected samples in a portable drying room trailer maintaining a temperature of 45ᵒ C, to obtain the dry mass (kg). Under the conditions this study was conducted grazing had little effect on forbs for deer. Forb standing crop was optimized (666 kg/ha) with no August rainfall and abundant September rainfall in areas with high sand percentages (90%). I found that grazing herbivores avoided low productive sites (<562 kg/ha) and models showed that grazing use was an influence in forb production, but rainfall and sand were more important. Plant species richness was affected by grazing use more than abiotic factors in the reduced data set. My results were strongly influenced by the legacy effect of decades of overgrazing and severe drought during 2011 to 2013. Within the time frame of my study, precipitation and sand percentage were more important drivers of forb dynamics than herbivores
Feasibility analysis of using solar, wind and wave energy to power electric charging station
No full textThe clamor for clean and renewable energy is becoming increasingly important as the world edges closer towards more pivotal infrastructural and technological feats. Due to the highly unpredictable nature of wind and solar energy, wave energy is also introduced as yet another alternative source of energy. This project focuses on coastal areas that have easy access to wave energy. The wave energy converter to be considered here is the Oscillating Water Column Backward Bent Duct Buoy (OWBBDB). The research objective is to investigate the technical feasibility of powering an electrical car charging station by using three forms of renewable energy (solar, wind and wave) as a hybrid system. The energy harnessed, from these sources, is stored in a battery storage system which is then utilized at the charging station. Different scenarios are analyzed in terms of energy generation by the hybrid energy system and the energy usage by the electric car charging station.
Keywords: Renewable Energy, Electrical Charging Station, Feasibility Analysi
Investigation of experiential and developmental changes in fruitless transcripts
No full textThe fruitless (fru) gene of Drosophila melanogaster, encodes a protein with a BTB-Zinc Finger transcription factor domain. The fru gene is responsible for courtship behavior, sex determination, sex discrimination and differentiation of the male abdominal structures. Due to alternative splicing there are 15 alternative transcripts for the fru gene, and they have different regulatory roles. One transcript for the fru gene, fru—RO, has an extended exon even though it has a stop codon in the amino acid sequence. It is possible that the stop codon is edited by ADAR (adenosine deaminase acting on RNA) before splicing can occur. It is not certain when the change occurs but there might be a relationship between RNA editing and the experience of courtship or the development of Drosophila. By using RT-PCR (Reverse Transcriptase - Polymerase Chain Reaction) to produce cDNA (complementary DNA) and sending amplified copies of the cDNA to be sequenced. This process can determine whether editing by ADAR occurs. The ratio of A/G and T/C in the electropherograms indicated that there is no support for the hypothesis that editing occurs during development. In addition, there is no evidence for an editing soon after mating behavior. More data points are required to determine whether the A to I edit does occur at later time points
Analysis and design of horizontal axis wind rotors twister blades
No full textHorizontal axis wind turbines utilize airfoil characteristics such as twist distribution, cord length, and camber to generate lift force that is on the blade plane and perpendicular to the blade axis. The shaft of the electric generator within a horizontal axis wind turbine is mainly driven by the lift force to produce clean and renewable electric power. For each airfoil, there exists an optimal angle of attack to generate the maximum lift force for the airfoil design. When a horizontal axis wind turbine blade is designed with fixed twist, the airfoil and angle of attack are specifically chosen to maximize the torque generated by the blade. In the operation of a horizontal axis wind turbine, the wind speed changes with time, which makes a conventional blade generate less lift force than an optimized blade. To improve the power conversion efficiency of a horizontal axis wind turbine blade, adjusting its angle of attack for individual airfoil segment is needed. In this research, the National Renewable Energy Laboratory (NREL) 5MW offshore reference blade is used to study the effects of the optimized twist configurations across a range of tip speed ratios. The twist configuration of a wind turbine blade is adjusted for a particular tip speed ratio. A twist configuration is chosen such that each blade airfoil has a maximum ratio between lift and drag forces. Three optimal twist configurations are generated in this research for three different tip speed ratios. Four rotors that have the reference and three optimal twist configurations are modeled and simulated. The dynamic torque values and power conversion coefficients of the four rotors under different tip speed ratios are obtained from the simulation data. The results show that the power conversion coefficients of the three rotors that have the optimal twist configurations are significantly above those of the reference rotor
Development and use of a ballistic testing apparatus for composite armor
No full textThe goal of the funded research was to develop composite armor panels for high-performance ballistic threats. With that comes the need to conduct ballistic testing on the composite armor panels during development. With no method of ballistics testing at TAMUK, the objective of this work was to come up with an affordable and effective ballistics testing system. The desire was to have projectile speeds of at least at 100 m/s and impact energy of at least 1000 J. A variety of testing methods were evaluated and after weighing cost, impact velocity, and ease of fabrication, a vacuum cannon was chosen. Although the development of the vacuum cannon test equipment included 26 mm, 76 mm, and 38 mm cannon diameters, it was concluded with a simpler but working 38.1 mm (1.5 in) diameter and 3 m (10 ft) length system that only uses atmospheric pressure. Also, a specimen test stand, a refined projectile consisting of a sabot and penetrator, a sabot catcher, and a safety cage were developed. Test procedures were developed and a data acquisition system was assembled and verified. The current system does not reach either 100 m/s or 1000 J of impact energy, but future improvements including lighter sabots, longer length, and addition of a compressed air boost will greatly increase projectile velocity and energy. Safety features are being added to the current system, after which it will be operational again. The current system can provide useful data for the research grant, and to future users
Some important problems in teaching Spanish-culture children
No full textThe Spanish-culture people of Texas form an exceedingly varied group. The problem of educating their children is generally no different from the problem of education in general. A large number, however, because of language, economic conditions, cultural level, prevailing social attitudes toward them, or other factors, present difficulties which together may be called the “Spanish-culture problem.” The Texas Educational Survey discusses this problem in a chapter entitled “The Non-English-Speaking children and the Public Schools.