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Antimicrobial and Nanocarrier Properties of Carbon Dots (CDs) Synthesized from Different Materials
No full textMultidrug resistance (MDR) in pathogens is a serious public health issue. In this prospect, the use of carbon dots as an antimicrobial agent is promising as they lead to nonspecific and random oxidative damages to the biomolecules such as proteins, lipids, and nucleic acids. Moreover, CDs are excellent candidates for gene delivery owing to their unique features like a facile synthesis, ease of functionalization, non-toxicity, and greater biocompatibility. The efficient way of introducing exogenous DNA into bacterial cells is fundamental in many microbiology and molecular activities such as cloning, mutant generation, DNA library construction. Heat shock and electroporation are two major techniques of gene delivery in bacterial cells, however, both techniques are time and resource-consuming. Thus, to develop efficient, easy, less time-consuming, and safe gene delivery methods, we used carbon dots as a non-viral method of gene delivery. In this study, we synthesized four carbon dots: amine-coated carbon dots (NH2-FCDs), carboxylate carbon dots (COOH-FCDs), carbon dots from L-arginine, and glucose (N-CDs), and carbon dots using citric acid and polyethyleneimine (PEI). We studied their antimicrobial effects in six different bacteria viz E. coli, Pectobacterium carotovorum, Agrobacterium tumefaciens, Agrobacterium rhizogenes, Pseudomonas syringae, and Salmonella enterica.Further, we studied the plasmid/gene delivery efficiency of carbon dots inside Escherichia coli, Pectobacterium carotovorum, and Salmonella enterica. We incubated CDs, cells, and plasmids carrying red fluorescent protein (RFP) as a reporter gene and ampicillin resistance gene as selectable markers. We used the agar well diffusion method for the antimicrobial study and calculated the inhibition zones in each bacterium. Transformed colonies were counted using ImageJ software and data were analyzed using R-software. Our findings showed that amine-coated carbon dots (NH2-FCDs) showed the highest inhibition in bacteria whereas carbon dots prepared from citric acid and polyethyleneimine (PEI) were non-inhibitory to the cells. Salmonella and E. coli were more resistant against CDs compared to Agrobacterium, Pseudomonas, and Pectobacterium. Different incubation times were also required for complete inhibition of bacteria according to the source of carbon dots. Similarly, our study demonstrated that among all these CDs, only carboxylate carbon dots (COOH-FCDs) were able to deliver plasmid DNA into E. coli cells
Perceptions of Teachers and Administrators regarding the Effectiveness and Implementation of the RTI Framework in K-4th Grade Elementary Schools of a Rural Eastern Tennessee School District
No full textThe implementation of Response to Intervention (RTI) has increased over the years and provided students with the support needed to close the learning gap and succeed in school. The purpose of this study was to evaluate the perceptions of the effectiveness of the RTI framework in a rural school district in Tennessee. The study included kindergarten through fourth-grade educators in nine elementary schools in a rural eastern Tennessee school district. The researcher analyzed the differences in participant responses based on the position they held at their respective schools and years of experience in education
Teachers’ Perceptions of Their Responsibility to Cultivate the Self-Efficacy of K-12 Students
No full textThe purpose of this study was to gain insight into the views of Kindergarten through 12th grade (K-12) teachers regarding the responsibility they have for cultivating the self-efficacy of K-12 students. The study encompassed the four primary sources of self-efficacy beliefs: mastery experiences, vicarious experiences, verbal persuasion, and emotional and physiological state, as theorized by Canadian-American psychologist Albert Bandura (Alexander, 2019). Specifically, the study examined K-12 teachers’ perceptions of their responsibility in cultivating self-efficacy in K-12 school students. The target population was K through 12th grade teachers in the Orange County School District The primary data collection source was based on a cross-sectional survey research design. One hundred and nineteen teachers participated in this research study (33.6% with 0-9 years, 33.6% with 10-20 years, and 32.8% with 21 or more years of teaching experience).This quantitative study provided an understanding of teachers’ beliefs in the benefits of student self-efficacy. In addition, the study determined if teaching experience impacts teachers’ beliefs in the benefits of student self-efficacy training. This research adds to the current body of research pertaining to Social Emotional Learning, specifically in the area of learner self-efficacy. This research provides administrators, both district and local, with feedback on the benefits of learner self-efficacy and how to best meet their teachers’ needs as they promote and develop learner self-efficacy. One-way analysis of variance (ANOVA) was used to determine whether there were any statistically significant differences among groups based on years of teaching experience (0-9 years, 10-20 years, and 21 years or more). A Shapiro-Wilks test of normality was conducted and indicated that responses in all three groups were significant, which means they are all significantly different from normal, or not normally distributed. This study utilized a quantitative method and employed a descriptive and inferential design
Evaluating Escherichia Coli Nissle as a Potential Probiotic for Broiler Chickens
No full textAntibiotics have been used therapeutically as feed additive in poultry feeding and they have been reported to improve poultry performance. Consequently, their overuse has been associated with antimicrobial resistance in poultry and poultry products, which is transferable to the consumer, a risk to human health. Alternatives to antibiotics, such as the probiotic Escherichia coli strain nissle 1917 (EcN) have been evaluated for use in humans. There is, however, limited research on the potential use EcN as a probiotic in poultry. The aim of this study was to assess the effect of EcN on growth performance of broiler chickens. In a completely randomized design, a total of 200 1-day-old broiler chicks were fed four dietary treatments comprising a standard corn-soy (SCS) control, SCS + soy protein, SCS + 108 cfu/g EcN, and SCS + 109 cfu/g EcN from hatch to 8 weeks of age (WOA). The EcN was encapsulated in soy protein, premixed in wheat middlings and homogeneously mixed in the SCS diets. Feed and water were provided ad libitum, birds were weighed weekly and body weight gain (BWG), feed consumption (FC) and feed conversion ratio (FCR) were determined weekly. Data were analyzed by one-way ANOVA using the General Linear Model of SAS and means were separated by the Least Square Means option. The birds fed diets containing 109 cfu/g EcN exhibited mean BWG that were 15% higher than those of birds fed the control diets at 1-8 WOA (P\u3c0.05). The FC was higher and FCR was significantly lower (P\u3c0.05) in birds fed the 109 cfu/g EcN. Broilers fed 108 cfu/g EcN had improved BWG and FCR at 1-4 WOA (P\u3c0.05), however differences in these parameters among treatments were not significant at 5-8 WOA (P\u3e0.05). Therefore, feeding 108 cfu/g EcN had slight improvement of BWG and FCR of broilers at 1-4 WOA, whereas feeding 109 cfu/g EcN significantly increased BWG and reduced FCR of broiler chickens at 1-8 WOA
Development of Resilient Software System for Cyber-Security Enhancement of Aviation Cyber-Physical Systems
No full textThe aviation industries recently have shown an interest in transferring their commercial aircraft into fully connected and network aircraft systems. This desire will lead to transforming aircraft in general and commercial aircraft in specific, into Aviation Cyber-Physical Systems (ACPS). However, like any Cyber-Physical system, ACPS is vulnerable to cyber-attacks that adversaries can mount through the communication network infrastructure. Adversaries can gain unauthorized access to the aircraft’s connected physical devices, such as sensors, actuators, or the control system through the communication network. This dissertation research work developed a security software system for detecting and defending the communication network of ACPS from two major cyber-attacks: Distributed Denial of Service (DDoS) and Fault Data Injection (FDI) Attacks. A novel security strategy (method) was developed to detect and defend against the cyber-attacks mentioned above. The system of interest (SOI) of this research comprises three subsystems: Communication Network Simulator (CNS), Attacks Detection and Classification (ADC), and Defense Against Attacks (DAA). CNS subsystem was developed to simulate dynamics of the communication network based on a discrete-event approach. This allows for establishing an aircraft networked control system (NCS) via a communication network to ensure implementation of the closed-loop control architecture. The CNS was developed using the SimEvents MATLAB/Simulink toolbox. The developed CNS was tested and validated on the selected aircraft associated with an adaptive control system, which produced the expected results. ADC subsystem was developed to detect DDoS and FDI attacks of the communication network of ACPS based on the signal’s classification approach. In the ADC, an Artificial Immune System (AIS) algorithm was developed and implemented to detect and drop malicious communication packets of the aircraft network traffic produced by both cyber-attacks. The detection accuracy of the AIS algorithm reached 96% based on true positive and true negative detection rates. The DAA subsystem was developed and implemented to defend the communication network of the ACPS against both DDoS and FDI cyber-attacks. A nonlinear autoregressive neural network with external inputs (NARX) was developed and used to reconstruct or estimate the network dropped packets. The estimation accuracy of the NARX reached 0.99, using the correlation coefficient (R-value) metric
A Phenomenological Study of Female International Students in Graduate Programs in the College of Education at a Public HBCU in the United States
No full textFemale international students negotiate multiple identities as non-native learners and women in a society with different cultural, social, and gender expectations than their home countries. However, a review of literature on international students reveals a lack of comprehensive discussion on gender and the international graduate school experiences. The purpose of this study is to explore the lived experiences of female international students pursuing a graduate degree in the college of education. This study aims to provide an understanding of how gender and immigration status can be significant factors in understanding the international students’ experiences. This study seeks to add to the literature by examining how female international students describe and make meaning of lived educational experiences during graduate degree completion in the context of the intersection of being international and a woman. A purposive sample of seven female international students from the three departments in the college of education (i.e., educational leadership, teaching and learning, and psychology) was studied using a qualitative design. This study employed a phenomenological approach to investigate the lived experiences of female international students pursuing graduate degrees in the college of education. In-depth semi-structured interviews with the seven participants and reflective journals were used to generate rich, detailed descriptions of the phenomenon. Data were analyzed using Moustaka’s (1994) phenomenological phases: (a) bracketing, (b) horizonalization, (c) clustering into themes, (d) textual description, (e) structural description, and (f) essence of the experience. Data analysis from the interviews illuminated five major themes across participants: (a) Coming to America, (b) Influence of cultural background, (c) Gender matters, (d) Support system, and (e) Being an international student. This study utilized a theoretical perspective based upon two theories: (a) feminist standpoint theory as a framework to gather the students’ narratives about graduate studies, and (b) intersectionality theory as a framework to view the intersection of being international and a woman in the United States
A Study of the Binding of Organic Compounds to Melanins
No full textMelanins (MNs) constitute a ubiquitous class of dark-colored pigments which can be found in all kingdoms of life. Despite many decades of intense research and computer modeling, there is no consensus on the precise chemical structure of these biomolecules, nor a precise explanation for their dark color, exhibited by their broad-range, monotonic absorbance profile over the entire ultraviolet and visible region of the electromagnetic spectrum. In this project, we study the binding of organic compounds to MNs synthesized from different precursors (catechol, pyrogallol, dopamine or L-DOPA) and co-precipitated on CaCO3 or Ca3(PO4)2. The MN-coated CaCO3 or Ca3(PO4)2 materials are washed, dried by freeze drying and characterized by FT-IR spectroscopy. The affinity of various organic compounds (acetaminophen, hydrocortisone, caffeine, theophylline, vanillin, carvone and others) have been evaluated using RP-HPLC analyses to determine the percent (%) binding of the compounds onto the MN-coated CaCO3 or Ca2(PO4)3 minerals. Preliminary results indicate that L-DOPA or dopamine based MNs bind organic compounds more strongly compared to catechol or pyrogallol based MNs. In addition, when given enough time (up to 48h) significant binding levels (\u3e 80%) by select organic compounds onto dopamine or L-DOPA based MNs can be achieved
The Emission Spectrum of the Hot Jupiter WASP-79b from HST/WFC3
Get PDFHere we present a thermal emission spectrum of WASP-79b, obtained via Hubble Space Telescope Wide Field Camera 3 G141 observations as part of the PanCET program. As we did not observe the ingress or egress of WASP-79b\u27s secondary eclipse, we consider two scenarios: a fixed mid-eclipse time based on the expected occurrence time, and a mid-eclipse time as a free parameter. In both scenarios, we can measure thermal emission from WASP-79b from 1.1 to 1.7 μm at 2.4σ confidence consistent with a 1900 K brightness temperature for the planet. We combine our observations with Spitzer dayside photometry (3.6 and 4.5 μm) and compare these observations to a grid of atmospheric forward models that span a range of metallicities, carbon-to-oxygen ratios, and recirculation factors. Given the strength of the planetary emission and the precision of our measurements, we found a wide range of forward models to be consistent with our data. The best-match equilibrium model suggests that WASP-79b\u27s dayside has a solar metallicity and carbon-to-oxygen ratio, alongside a recirculation factor of 0.75. Models including significant H− opacity provide the best match to WASP-79b\u27s emission spectrum near 1.58 μm. However, models featuring high-temperature cloud species—formed via vigorous vertical mixing and low sedimentation efficiencies—with little day-to-night energy transport also match WASP-79b\u27s emission spectrum. Given the broad range of equilibrium chemistry, disequilibrium chemistry, and cloudy atmospheric models consistent with our observations of WASP-79b\u27s dayside emission, further observations will be necessary to constrain WASP-79b\u27s dayside atmospheric properties