Sorption kinetic studies of medical grade activated carbon prepared from papaya seeds

The aim of this investigation was to determine the adsorption behavior and kinetics of methylene blue in aqueous solution on activated carbons prepared from papaya seeds by way of the two stage activation method in self-generated atmosphere using a muffle furnace. The optimised activated carbon, AK7, had a sorption kinetic that complied with the pseudo-second order kinetics and was fitted well to Langmuir isotherm model. The highest adsorption capacity of 97.09 mg g-1was obtained when the samples (AK7) were subjected to activation temperature of 500oC for 60 minutes with the percentage of methylene blue removal efficiency of 99.5%

Reduced Augmentation Implicit Low-rank (RAIL) integrators for advection-diffusion and Fokker-Planck models

This paper introduces a novel computational approach termed the Reduced Augmentation Implicit Low-rank (RAIL) method by investigating two predominant research directions in low-rank solutions to time-dependent partial differential equations (PDEs): dynamical low-rank (DLR), and step and truncation (SAT) tensor methods. The RAIL method, along with the development of the SAT approach, is designed to enhance the efficiency of traditional full-rank implicit solvers from method-of-lines discretizations of time-dependent PDEs, while maintaining accuracy and stability. We consider spectral methods for spatial discretization, and diagonally implicit Runge-Kutta (DIRK) and implicit-explicit (IMEX) RK methods for time discretization. The efficiency gain is achieved by investigating low-rank structures within solutions at each RK stage using a singular value decomposition (SVD). In particular, we develop a reduced augmentation procedure to predict the basis functions to construct projection subspaces. This procedure balances algorithm accuracy and efficiency by incorporating as many bases as possible from previous RK stages and predictions, and by optimizing the basis representation through SVD truncation. As such, one can form implicit schemes for updating basis functions in a dimension-by-dimension manner, similar in spirit to the K-L step in the DLR framework. We also apply a globally mass conservative post-processing step at the end of each RK stage. We validate the RAIL method through numerical simulations of advection-diffusion problems and a Fokker-Planck model, showcasing its ability to efficiently handle time-dependent PDEs while maintaining global mass conservation. Our approach generalizes and bridges the DLR and SAT approaches, offering a comprehensive framework for efficiently and accurately solving time-dependent PDEs with implicit treatment

An Analysis Of Energy Generating System Concerns

A primary focus of this research project was to collect and analyze data pertaining to operating and maintenance concerns being experienced by owners and operators of energy generating systems and the vendors who supply these systems.  An important purpose in collecting the information from these various groups was to provide some direction to research (both funded and unfunded) relating to specific energy generating system problems currently being experienced or anticipated in the future

Observation of Flow Regime Transition in a CFB Riser Using an LDV

The solids flow in a circulating fluidized bed (CFB) riser is often described to have a core-annular structure. For a given superficial gas velocity, at the initial introduction of solids into a riser a flow structure of dilute upflow regime exists. Continuing to increase the solids flow in the riser transitions the flow structure to the core-annular flow regime. However, with further increase of solids flow a condition is reached, depending on the superficial gas velocity, where all the solids across the riser cross section flow upwards, even those at the wall. When the solids flux, solids fraction and gas velocity are relatively high, such a condition is described as the dense phase suspense upflow (DSU) regime. In this paper we report our observations of these flow regime transitions by using a laser Doppler velocimeter (LDV) to monitor the upward and downward particle flow velocities at and near the riser wall of the National Energy Technology Laboratory’s 30.4 centimeters diameter CFB cold flow model. The particles were high density polyethylene (PPE) spheres with a Sauter mean diameter of 861 micron and a density of 800 kg/m3. Three superficial gas velocities of 6.55 m/s, 10.67 m/s and 13.72 m/s were used in this study. For the case of superficial gas velocity 6.55 m/s, the experimental data show that the transition from dilute upflow to core-annular flow occurred when the solids flux was about 7 kg/m2-s and the transition from core-annular flow to dense suspension upflow was about 147 kg/m2-s. As the superficial gas velocity was increased to 10.67 m/s the corresponding flow regime transitions were at 34 kg/m2-s and 205 kg/m2-s, respectively. For the case of superficial gas velocity of 13.72 m/s the data showed no distinct transition of flow regimes. The particles were all upflow for the range of solids fluxes from 10 kg/m2-s to 286 kg/m2-s

Chemical Authentication and Speciation of Salvia Botanicals: An Investigation Utilizing GC/Q-ToF and Chemometrics

Members of the genus Salvia are used as culinary herbs and are prized for their purported medicinal attributes. Since physiological effects can vary widely between species of Salvia, it is of great importance to accurately identify botanical material to ensure safety for consumers. In the present study, an in-depth chemical investigation is performed utilizing GC/Q-ToF combined with chemometrics. Twenty-four authentic plant samples representing five commonly used Salvia species, viz. S. apiana, S. divinorum, S. mellifera, S. miltiorrhiza, and S. officinalis, are analyzed using a GC/Q-ToF technique. High-resolution spectral data are employed to construct a sample class prediction (SCP) model followed by principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA). This model demonstrates 100% accuracy for both prediction and recognition abilities. Additionally, the marker compounds present in each species are identified. Furthermore, to reduce the time required and increase the confidence level for compound identification and the classification of different Salvia species, a personal compound database and library (PCDL) containing marker and characteristic compounds is constructed. By combining GC/Q-ToF, chemometrics, and PCDL, the unambiguous identification of Salvia botanicals is achieved. This high-throughput method can be utilized for species specificity and to probe the overall quality of various Salvia-based products

Undergraduate Students’ Accuracy & Confidence in Detecting Errors in Biological Models Related to GPA

Research Questions 1. Does students’ abilities to Accurately detect errors relate to their GPA? 2. Which concepts affect student ability to Accurately and Confidently detect errors? GPA was positively related to accuracy but was unrelated to confidence (Fig. 1) Subject areas affected students’ accuracy and confidence § Students were more accurate on ecology & evolution models (Fig. 2) § Students were more confident in ecology models and less confident in physiology models (Fig. 2) Variation in student ability and subject area competency can provide teachers with places to focus and improve science understanding. Similar to the work of Clark et al 2020, this study gives merely a foundation on how certain principles affect the neural aspects of how students engage in reasoning about biology

Transient Characterization of Type B Particles in a Transport Riser

Simple and rapid dynamic tests were used to evaluate fluid dynamic behavior of granular materials in the transport regime. Particles with densities ranging from 189 to 2,500 kg/m3 and Sauter mean size from 61 to 812 μm were tested in a 0.305 m diameter, 15.5 m height circulating fluidized bed (CFB) riser. The transient tests involved the abrupt stoppage of solids flow for each granular material over a wide range gas flow rates. The riser emptying time was linearly related to the Froude number in each of three different operating regimes. The flow structure along the height of the riser followed a distinct pattern as tracked through incremental pressures. These results are discussed to better understand the transformations that take place when operating over various regimes. During the transients the particle size distribution was measured. The effects of pressure, particle size, and density on test performance are also presented

Synthesis and Characterization of MoTe2 Thin Films for Photoelectro-chemical Cell Applications

Thin films of transition metal chalcogenides, molybdenum ditelluride (MoTe2) have been electrodeposited cathodically on indium tin oxide-coated conducting glass substrates from ammonaical solution of H2MoO4 and TeO2. These MoTe2 thin films are useful as photovoltaic cell and photoelectro-chemical (PEC) solar cell. The electrode potential was varied while the bath temperature was maintained at 40±1 ºC and deposition time of 30 minutes. X-ray diffraction analysis showed the presence of highly textured MoTe2 films with polycrystalline nature. Compositional analysis by EDX gives their stoichiometric relationships. Scanning electron microscope (SEM) was used to study surface morphology and shows that the films are smooth, uniform and useful for device fabrication. The optical absorption spectra showed that the material has an indirect band-gap value of 1.91-2.04 eV with different electrode potential. Besides, the film exhibited p-type semiconductor behavior

Synthesis and Characterization of MoTe2 Thin Films for Photoelectro-chemical Cell Applications

Thin films of transition metal chalcogenides, molybdenum ditelluride (MoTe2) have been electrodeposited cathodically on indium tin oxide-coated conducting glass substrates from ammonaical solution of H2MoO4 and TeO2. These MoTe2 thin films are useful as photovoltaic cell and photoelectro-chemical (PEC) solar cell. The electrode potential was varied while the bath temperature was maintained at 40±1 ºC and deposition time of 30 minutes. X-ray diffraction analysis showed the presence of highly textured MoTe2 films with polycrystalline nature. Compositional analysis by EDX gives their stoichiometric relationships. Scanning electron microscope (SEM) was used to study surface morphology and shows that the films are smooth, uniform and useful for device fabrication. The optical absorption spectra showed that the material has an indirect band-gap value of 1.91-2.04 eV with different electrode potential. Besides, the film exhibited p-type semiconductor behavior