Fundamental Investigation of Reactive-Convective Transport: Implications for Long-Term Carbon dioxide (CO2) Sequestration

The density-driven convection coupled with chemical reaction is the preferred mechanism for permanently storing CO2 in saline aquifers. This study uses a 2D visual Hele-Shaw cell to evaluate and visualize the density-driven convection formed due to gravitational instabilities, also known as Rayleigh-Taylor instability. The primary goal of the experiments is to understand the various mechanisms for the mass transfer of gaseous CO2 into brine with different initial ionic concentrations and flow permeability. Moreover, the impact of CO2 flow rates, injection locations, reservoir dipping angle, and permeability heterogeneity is also investigated. We observed that the presence of salts resulted in earlier onset of convection and a larger convective finger wavelength than the case with no dissolved salts. In addition, experimental data showed a higher lateral mixing between CO2 fingers when dipping is involved. The visual investigation also revealed that the CO2 dissolution rate, measured by the rate of the convective fingers advance, depends on the type and concentration of the ions present in the brine. The CO2 dissolution for solutions with varying salt dissolved, indicated by the area of the pH-depressed region, is observed to be 0.38-0.77 times compared to when no salt is present. Although convective flow is slowed down in the presence of salts, the diffusive flux is enhanced, as observed from both qualitative and quantitative results. Moreover, the reduced formation permeability, introduced by using a flow barrier, resulted in numerous regions not being swept by the dissolved CO2, indicating an inefficient dissolution. We also investigated the effect of discrete high conductivity fractures within the flow barriers, which showed an uneven vertical sweep and enhanced flow channeling. Lastly, the parameters regarding CO2 leakage risk during storage are identified and discussed

Trails of Media Trial: Impacts on Judiciary and Society in Bangladesh

The media is supposed to be a light bearer of truth and justice as people tend to trust the circulations of media. However, using this as an advantage, the media often brings delicate judicial issues on a trial which results in the suffering of the victim. The key objective of this research was to explore the impacts of the trials of media on the justice system and society of Bangladesh. Primary data were collected using qualitative tools like In-Depth Interviews to understand the rigor of the research problem. At the same time, secondary data such as several case studies were collected to depict the history of media trials in Bangladesh. The research found the capability of media trials to impact the judicial system and society of Bangladesh adversely through indirect influence on the juror, evasion of privacy of the personnel associated with the cases, and misuse of social media. The research opted for effective policies to be formed by the government to regulate media influence on judicial cases so that media trials cannot impact the system. Keywords: Media trial, Press, Judiciary, Justice System, Impact, Society. DOI: 10.7176/NMMC/106-0

Physics-Based Proxy Modeling of CO₂ Sequestration in Deep Saline Aquifers

The geological sequestration of CO2 in deep saline aquifers is one of the most effective strategies to reduce greenhouse emissions from the stationary point sources of CO2. However, it is a complex task to quantify the storage capacity of an aquifer as it is a function of various geological characteristics and operational decisions. This study applies physics-based proxy modeling by using multiple machine learning (ML) models to predict the CO2 trapping scenarios in a deep saline aquifer. A compositional reservoir simulator was used to develop a base case proxy model to simulate the CO2 trapping mechanisms (i.e., residual, solubility, and mineral trapping) for 275 years following a 25-year CO2 injection period in a deep saline aquifer. An expansive dataset comprising 19,800 data points was generated by varying several key geological and decision parameters to simulate multiple iterations of the base case model. The dataset was used to develop, train, and validate four robust ML models—multilayer perceptron (MLP), random forest (RF), support vector regression (SVR), and extreme gradient boosting (XGB). We analyzed the sequestered CO2 using the ML models by residual, solubility, and mineral trapping mechanisms. Based on the statistical accuracy results, with a coefficient of determination (R2) value of over 0.999, both RF and XGB had an excellent predictive ability for the cross-validated dataset. The proposed XGB model has the best CO2 trapping performance prediction with R2 values of 0.99988, 0.99968, and 0.99985 for residual trapping, mineralized trapping, and dissolution trapping mechanisms, respectively. Furthermore, a feature importance analysis for the RF algorithm identified reservoir monitoring time as the most critical feature dictating changes in CO2 trapping performance, while relative permeability hysteresis, permeability, and porosity of the reservoir were some of the key geological parameters. For XGB, however, the importance of uncertain geologic parameters varied based on different trapping mechanisms. The findings from this study show that the physics-based smart proxy models can be used as a robust predictive tool to estimate the sequestration of CO2 in deep saline aquifers with similar reservoir characteristics

Dielectrophoresis spectroscopy for nucleotide identification in DNA

DNA sequence with a known physical position on a chromosome is called a genetic marker, so the causal gene may identify with genetic markers in different kinds of hereditary diseases. DNA segments near one another on a chromosome often inherit the other concurrently; as a result, the inheritance of a neighboring gene that has not yet been discovered but whose general position is tracked by using genetic markers. So, Genetic markers can play a significant role in biological research because they can contribute to identifying many diseases. Single nucleotide polymorphism, or SNP (pronounced “snip”), is the variation of a single nucleotide in a DNA due to genetic disorders. For example, in a specific region of DNA, an SNP may displace the nucleotide cytosine (C) with the nucleotide thymine (T). SNPs, or single nucleotide polymorphisms, are one of the most common genetic variations that assist in detecting many human diseases such as Migraine, Cancer, Schizophrenia, Sickle Cell Anemia, Alzheimer's Disease, etc. Hyperchromicity, Short Oligonucleotide Analysis Program (SOAP), quantitative PCR techniques, Fluorescence Polarization Melting Curve Analysis, SNP Microarrays, Intercalating Dyes, and many other techniques are commonly used to identify SNPs nowadays. However, those methods are not much reliable, a bit costly, time-consuming, and difficult to use, whereas dielectrophoresis can be an excellent way to detect SNP easily. A non-uniform electric field generated by electrodes interacts with polarizable suspended particles to regulate and alter particle movement; this process is known as dielectrophoresis (DEP). Cell transfer, in vitro fertilization, and biological testing are a few uses for dielectrophoresis, particularly in the biomedical industry. Cell fusion using dielectrophoresis has also improved crossbreeding, cancer treatment, and scientific research. Most notably, dielectrophoresis is used to classify changes in the electrical characteristics of cells. In this phenomenon, when a dielectric particle is exposed to a non-uniform electric field, a force is produced on it, and this DEP force may be utilized to recognize the variations in a single location in a DNA sequence. DEP is less time-consuming, cheap, and reliable than other processes to detect SNPs easily

Recent trends and future potential of microwave-assisted fish drying

Microwave (MW) offers a unique heating mechanism, which volumetrically pushes internal moisture to the surface during the drying of water-rich foods such as fish. However, due to the uneven power distribution, the continuous application of MW energy causes excessive localized heating, resulting in the deterioration of food quality. Incorporation of other drying techniques such as convective, vacuum, osmotic, and freeze-drying with MW has been attempted in the past to solve these shortcomings and applied in different drying systems. This paper investigates the current trends in microwave-assisted drying (MWAD) methods for fish. The available literature on MWAD methods is critically analyzed in terms of energy consumption and change in nutritional components as well as other properties. Additionally, this review explores the potential of MWAD methods for fish drying. This article shows that pulsed microwave convective drying (PMCD) can be implemented in fish drying effectively. Considering the critical need for improving energy efficiency and quality retention in fish drying, PMCD would be a highly promising drying method.</p

Improved Switching Technique to Mitigate THD and Power Loss of NPC Inverters

Total harmonic distortion (THD) and power loss have a substantial effect on the power quality of multilevel inverter (MLIs). They are both directly impacted by the switching method of pulse width modulation (PWM). Nevertheless, traditional PWM methods designed for MLIs have challenges that result in higher THD and problems with power loss. A modified level-shifted carrier-based switching technique is presented in this work. The main goal of the proposed PWM technique is to reduce power losses and THD of neutral-point-clamped (NPC) inverters. The software platforms PLECS and MATLAB/Simulink are used thoroughly to model and simulate the whole system. Moreover, an experimental test at a reduced scale is conducted to verify the results of the simulation study, validating the feasibility of the suggested PWM technique

A Probabilistic Generative Model for Fault Analysis of a Transmission Line with SFCL

The fault analysis of a transmission line (TL) are the key factors for the rapid restoration of the power network. Due to the recent expansion of the power system as well as the increased generation capacity, the magnitude of the fault current increases beyond the interruption capability of the existing circuit breaker. In this turn, the superconducting fault current limiters (SFCLs) come in handy which limits the fault current and facilitates the tripping operation without upgrading the breaker rating. Besides, the SFCLs affect the three-phase signals which, in turn, negatively affect the transmission line protection scheme. This paper proposes an unsupervised framework for fault detection and classification of a transmission line with SFCLs. The proposed scheme receives 1/2 cycle post-fault three-phase signals and hierarchically extracts the fault information for fault analyzing purposes. The effectiveness of the proposed approach is justified in terms of overall and individual accuracy. Further assessment of the model\u27s performance against noise and measurement error is also carried out in order to confirm the high reliability of the proposed model

Natural Sunlight Driven Photocatalytic Removal of Toxic Textile Dyes in Water Using B-Doped ZnO/TiO₂ Nanocomposites

A novel B-doped ZnO/TiO2 (B–ZnO/TiO2) nanocomposite photocatalyst was prepared using a mechanochemical–calcination method. For the characterization of the synthesized B–ZnO/TiO2 photocatalyst, XRD, FESEM-EDS, FTIR, UV-Vis DRS, BET, PL, and XPS techniques were used. The bandgap energy of B–ZnO/TiO2 was reduced, resulting in enhanced visible-light absorption. Significant PL quenching confirmed the reduction in the electron–hole recombination rate. Furthermore, reduced crystallite size and a larger surface area were obtained. Hence, the B–ZnO/TiO2 photocatalyst exhibited better photocatalytic activity than commercial TiO2, ZnO, B–ZnO, and ZnO/TiO2 in the removal of methylene blue (MB) dye under natural sunlight irradiation. The effects of various parameters, such as initial concentration, photocatalyst amount, solution pH, and irradiation time, were studied. Under optimal conditions (MB concentration of 15 mg/L, pH 11, B–ZnO/TiO2 amount of 30 mg, and 15 min of operation), a maximum MB removal efficiency of ~95% was obtained. A plausible photocatalytic degradation mechanism of MB with B–ZnO/TiO2 was estimated from the scavenger test, and it was observed that the •O2− and •OH radicals were potential active species for the MB degradation. Cyclic experiments indicated the high stability and reusability of B–ZnO/TiO2, which confirmed that it can be an economical and environmentally friendly photocatalyst