Norfolk State University
  • Norfolk, United States
Recent publications
The electrochemical performances of cathode materials depend on crystallinity and structural stability. We report improved electrochemical performances of Li2FeMn3O8 (LFMO) cathode materials synthesized using the chemical solution combustion method and the obtained powders are calcined at various temperatures such as 600 °C, 700 °C, and 900 °C. The LLCZN/PEO/LiPF6 is used as a solid electrolyte during the assembly of the coin cells. The calcining temperatures improve the crystallinity and structural stability, thereby improving the electrochemical performances of the LFMO because of the mutual diffusion region at the electrode/solid electrolyte interface. Among these, the LFMO calcined at 900 °C shows the best electrochemical performance. At 0.1 mA cm⁻², the discharge capacity at the 150th cycle is 133 mAh g⁻¹ with a Coulombic efficiency of approximately 97% and a retention rate of 85% for the 900 °C calcined sample. While the 700 °C calcined sample is 126 mAh g⁻¹ after 150th cycles of the galvanostatic charge-discharge test, the Coulombic efficiency is maintained at about 95% and the capacity retention rate is 83%. The 600 °C calcined temperature exhibited 101 mAh g⁻¹ with a Coulombic efficiency of 92% and a retention rate of 73% after the 150th discharge cycle. The findings suggest that the chemical solution combustion approach might be a viable way of producing nanosized LFMO as an active cathode material for lithium-ion batteries (LIB).
One of the greatest advantages of organic/polymeric semiconductors is their ease of tunability of optoelectronic, electronic, and optical properties pre- and post-synthesis. Chemical doping has numerous advantages in comparison to the other routes due to being quick, cost-effective, and highly controllable. For dopants to ionize the host material, the frontier orbital offset should be carefully engineered to enable efficient charge transfer between dopant and host material. This work directly studies different frontier orbital levels between poly(3-hexylthiophene-2,5-diyl) (P3HT) and a variety of molecular dopants. Results show that the electrical conductivity decreases as the LUMO of the dopant increases; this could be explained by the increased energy barrier for electron transfer from the HOMO of the P3HT to the LUMO of the dopant acceptors. Among the several dopants investigated, this study reveals that the Seebeck coefficients decrease as the frontier orbital offsets (between P3HT HOMO and acceptor LUMO) decrease and the electrical conductivity increases. Optimal offsets are also identified where certain parameters exhibit the highest or lowest values.
Background: Disabilities may play a different role in determining people’s physical activity (PA) and physical inactivity (PI) levels when they go through multiple lifetime transitions (e.g., graduation, marriage) between adolescence and young adulthood. This study investigates how disability severity (i.e., no, minimal, mild, and moderate/severe disability and/or limitation) is associated with changes in PA and PI engagement levels, focusing on adolescence and young adulthood, when the patterns of PA and PI are usually formed. Methods: The study employed data from Waves 1 and 4 of the National Longitudinal Study of Adolescent Health, which covers a total of 15,701 subjects. We first categorized subjects into 4 disability groups: no, minimal, mild, or moderate/severe disability and/or limitation. We then calculated the differences in PA and PI engagement levels between Waves 1 and 4 at the individual level to measure how much the PA and PI levels of individuals changed between adolescence and young adulthood. Finally, we used two separate multinomial logistic regression models for PA and PI to investigate the relationships between disability severity and the changes in PA and PI engagement levels between the two periods after controlling for multiple demographic (age, race, sex) and socioeconomic (income level, education level) variables. Results: We showed that individuals with minimal disabilities were more likely to decrease their PA levels than those without disabilities during transitions from adolescence to young adulthood. Our findings also revealed that individuals with moderate to severe disabilities tended to have higher PI levels than individuals without disabilities when they were young adults. Furthermore, we found that people above the poverty level were more likely to increase their PA levels to a certain degree compared to people in the group below or near the poverty level. Conclusions: Our study partially indicates that individuals with disabilities are more vulnerable to unhealthy lifestyles due to a lack of PA engagement and increased PI time compared to people without disabilities. We recommend that health agencies at the state and federal levels allocate more resources for individuals with disabilities to mitigate health disparities between those with and without disabilities.
Purpose: The purpose of this study is to explore existing frameworks and practices for addressing discrimination in supervision as well as patterns of discriminatory treatment in supervision identified in social work and related fields. Methods: The project employed a rapid review guided by the methods of Search, Appraisal, Synthesize, and Analysis (SALSA) and Preferred Reporting Items for Systematic Reviews and Meta Analysis (PRISMA). Results: The authors found evidence that discrimination in supervision is a documented problem that occurs in related fields. It revealed a range of social identities that have been the target of discrimination. It also found opportunities for social work to build on existing regulatory frameworks to address critical gaps. Conclusion: It is critical that social work take steps to fill the gap in social work professional standards and regulations and ensure that social workers from disadvantaged backgrounds have equal opportunity and access to training and licensure.
The renormalization group (RG) method of Chen, Goldenfeld, Oono et al. offers a comprehensive approach to formally computing asymptotic expansions of the solutions to singular perturbation problems. A renormalization group formalism developed recently for the Michaelis–Menten (MM) model is extended to competitive systems. We will first revisit the singular perturbation analysis for the standard quasi‐steady‐state approximation (sQSSA) of enzyme‐substrate‐inhibitor kinetics. Our result shows that the RG method leads to a new prediction for the concentrations of substrate, inhibitor, and complexes, which can reproduce or surpass the results of matched asymptotics.
When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon–nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure1–3, and mapping out the strength and the isospin structure (neutron–proton (np) versus proton–proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements3–5. Two-nucleon knockout or ‘triple coincidence’ reactions have been used to measure the relative contribution of np-SRCs and pp-SRCs by knocking out a proton from the SRC and detecting its partner nucleon (proton or neutron). These measurements6–8 have shown that SRCs are almost exclusively np pairs, but they had limited statistics and required large model-dependent final-state interaction corrections. Here we report on measurements using inclusive scattering from the mirror nuclei hydrogen-3 and helium-3 to extract the np/pp ratio of SRCs in systems with a mass number of three. We obtain a measure of the np/pp SRC ratio that is an order of magnitude more precise than previous experiments, and find a marked deviation from the near-total np dominance observed in heavy nuclei. This result implies an unexpected structure in the high-momentum wavefunction for hydrogen-3 and helium-3. Understanding these results will improve our understanding of the short-range part of the nucleon–nucleon interaction. A comparison of electron scattering from the mirror nuclei hydrogen-3 and helium-3 reveals that proton–proton pairs have a much larger contribution to short-range correlations in helium-3 than in heavier nuclei, implying an unexpected nuclear structure.
Photoinduced voltages associated with surface plasmon polariton excitations are studied both theoretically and experimentally in various plasmonic systems as the function of material, wavelength, and type of structure. Experimental photovoltage normalized to the absorbed power shows a general decrease upon an increase in the wavelength, enhancement in the nanostructured samples, and a strong variation in the magnitude as a function of the material, which are not in line with the theoretical predictions of the simple plasmonic pressure approach. The results can be used for clarification of the mechanisms and further development of an adequate theoretcial approach to the plasmon drag effect.
Resilience-enhancing stress model (RESM) narrative interviews involve social workers facilitating a cocreated client narrative, developing a plot, uncovering important themes, interpreting events, and reimaging a new and more positive story. This is accomplished through the four phases of the RESM helping process. This chapter describes these phases and the interview skills that can be applied.KeywordsInterview skillsRESM phasesThird-space relationshipMeaning-making
An intelligent sensing framework using Machine Learning (ML) and Deep Learning (DL) architectures to precisely quantify dielectrophoretic force invoked on microparticles in a textile electrode-based DEP sensing device is reported. The prediction accuracy and generalization ability of the framework was validated using experimental results. Images of pearl chain alignment at varying input voltages were used to build deep regression models using modified ML and CNN architectures that can correlate pearl chain alignment patterns of Saccharomyces cerevisiae(yeast) cells and polystyrene microbeads to DEP force. Various ML models such as K-Nearest Neighbor, Support Vector Machine, Random Forest, Neural Networks, and Linear Regression along with DL models such as Convolutional Neural Network (CNN) architectures of AlexNet, ResNet-50, MobileNetV2, and GoogLeNet have been analyzed in order to build an effective regression framework to estimate the force induced on yeast cells and microbeads. The efficiencies of the models were evaluated using Mean Absolute Error, Mean Absolute Relative, Mean Squared Error, R-squared, and Root Mean Square Error (RMSE) as evaluation metrics. ResNet-50 with RMSPROP gave the best performance, with a validation RMSE of 0.0918 on yeast cells while AlexNet with ADAM optimizer gave the best performance, with a validation RMSE of 0.1745 on microbeads. This provides a baseline for further studies in the application of deep learning in DEP aided Lab-on-Chip devices.
Optical tweezer is a non-contact tool to trap and manipulate microparticles such as biological cells using coherent light beams. In this study, we utilized a dual-beam optical tweezer, created using two counterpropagating and slightly divergent laser beams to trap and deform biological cells. Human embryonic kidney 293 (HEK-293) and breast cancer (SKBR3) cells were used to characterize their membrane elasticity by optically stretching in the dual-beam optical tweezer. It was observed that the extent of deformation in both cell types increases with increasing optical trapping power. The SKBR3 cells exhibited greater percentage deformation than that of HEK-293 cells for a given trapping power. Our results demonstrate that the dual-beam optical tweezer provides measures of cell elasticity that can distinguish between various cell types. The non-contact optical cell stretching can be effectively utilized in disease diagnosis such as cancer based on the cell elasticity measures.
Sensing and communication technology has been used successfully in various event monitoring applications over the last two decades, especially in places where long-term manual monitoring is infeasible. However, the major applicability of this technology was mostly limited to terrestrial environments. On the other hand, underwater wireless sensor networks (UWSNs) opens a new space for the remote monitoring of underwater species, faunas along with communicating with underwater vehicles, submarines etc. However, as opposed to terrestrial radio communication, underwater environment brings new challenges for reliable communication due to the high conductivity of the aqueous medium which leads to major signal absorption. In this paper, we provide a detailed technical overview of different underwater communication technologies, namely acoustic, magnetic and visual light, along with their potentials and challenges in submarine environments. Detailed comparison among these technologies have also been laid out along with their pros and cons using real experimental results.
Social media connects people in a myriad of ways, yet when prevented from staying connected, an experience of missing out on information and events perceived to be integral to one's well-being may ensue. Relatedness, a core construct of self-determination theory, is a primary influencer of motivation, and therefore being cut off from others has a negative impact on one's quality of life. Across diverse groups of people, social media is utilized for a variety of purposes directly related to connectedness, which implies inherent differences in how one's fear of missing out (FoMO) manifests in everyday life. This study employed the previously validated Fear of Missing Out Scale (FoMOS) with a nonclinical sample of African American and Caucasian college students in the United States, with a particular focus on validity of the measure with an African American cohort due to a lack of empirical evidence pertaining to with this demographic. Factor analyses yielded inconsistent findings from the FoMOS initial validation study, and results indicated differences in self-reported FoMO between the two racial groups. We speculate that observed group-based differences are at least partially the result of how individuals from each group understood and internalized the conceptual meaning of FoMO, supporting a hypothesis of practical differences in how anxieties related to missing out manifest. This may be due to individual or group-based differences in motivations for, or general purpose of, using social media.
Bacteriophages (also called phages) are viruses of bacteria that have numerous applications in medicine, agriculture, ecology, and molecular biology. With the increasing interest in phages for their many uses, it is now especially important to make phage discovery more efficient and economical. Using the host Mycobacterium smegmatis mc²155, which is a model organism for phage discovery research and is closely related to important pathogens of humans and other animals, we investigated three procedures that are an integral part of phage discovery: enrichment of environmental samples, phage isolation and detection (which can also be used for host range determination), and phage purification. Enrichment in 6-well plates was successful with most environmental samples, and enrichment in 24- and 96-well plates was successful with some environmental samples, demonstrating that larger sample volumes are preferred when possible, but smaller sample volumes may be acceptable if the starting concentration of phages is sufficiently high. Measuring absorbance in multi-well plates was at least as sensitive as the traditional plaque assay for the detection of phages. We also demonstrated a technique for the purification of single phage types from mixed cultures in liquid medium. Multi-well techniques can be used as alternatives or complementary approaches to traditional methods of phage discovery and characterization depending on the needs of the researcher in terms of time, available resources, host species, phage-bacteria matches, and specific goals. In the future, these techniques could be applied to the discovery of phages of aquatic mycobacteria and other hosts for which few phages have currently been isolated.
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956 members
Krishnan Prabhakaran
  • Department of Biology
Kathleen S Thomas
  • Department of Health, Physical Education and Exercise Science
Marilyn Lewis
  • "Ethelyn R. Strong" School of Social Work
Carl Emery Bonner
  • Center for Materials Research
Norfolk, United States