Social Commerce Among Micro and Small Medium Enterprises Before and During the COVID19: A Systematic Literature Review

Social commerce (SC) is a relatively new tool that businesses are using to conduct business using social media (SM). The findings of prior literature are inconclusive. This paper reviews the literature to identify the current status and to identify the determinant of SC. A systematic literature review was conducted. A total of 41 articles were reviewed. A comparison between before and during COVID19 was conducted. The findings showed the number of studies has not increased during COVID-19. The technology acceptance model (TAM) and Technology-Organization- Environment (TOE) are used widely in the literature. The most important factors identified in this study are divided into before COVID19 and during COVID19. Perceived usefulness and perceived ease of use were important in both periods. New variables that were considered important during COVID19 is the organizational readiness, trust, security, and E- word of mouth (EWOM). More research is needed to understand the factors that contribute to SC adoption in different nations. Variables such as trust, environmental uncertainty, and perceived value can be included in future work. Developing a digital ecosystem for SC is a direction for future work. Understanding the important factors can contribute to the advancement of SC

Optička svojstva tankih slojeva bismut sulfida Bi2S3

Thin films of bismuth sulfide (Bi2S3) were grown by two deposition techniques, by thermal evaporation and by chemical deposition. The thermally deposited reactions consisted in depositing the individual elements, namely bismuth and sulfur, sequentially from a tungsten boat source and allowing the layers to interdiffuse to form the compound during the heat-treatment. The chemical deposition was based on the reaction between the triethanolamine compex of Bi3+ ions and thiourea in basic media. Scanning electron microscope and X-ray diffraction analysis were made on as-deposited and on annealed films to determine their structure. The different electronic transitions and the optical constants are determined from the transmision and reflection data of these thin films for normal incidence. The optical gaps of Bi2S3 films show a remarkable dependence on the preparation method.Tanki su slojevi bismut sulfida (Bi2S3) načinjeni dvjema metodama, vakuumskim naparavanjem i kemijskim taloženjem. Ti su se slojevi istraživali sustavno-pretražnom elektronskom mikroskopijom i difrakcijom rentgenskog zračenja, prije i nakon termičkog opuštanja. Našao se je niz elektronskih prijelaza i odredile se optičke konstante na osnovi transmisijskih i refleksijskih podataka za okomitu upadnu svjetlost. Optički procijepi Bi2S3 pokazuju priličnu ovisnost o metodi pripremanja

Optička svojstva tankih slojeva bismut sulfida Bi2S3

Thin films of bismuth sulfide (Bi2S3) were grown by two deposition techniques, by thermal evaporation and by chemical deposition. The thermally deposited reactions consisted in depositing the individual elements, namely bismuth and sulfur, sequentially from a tungsten boat source and allowing the layers to interdiffuse to form the compound during the heat-treatment. The chemical deposition was based on the reaction between the triethanolamine compex of Bi3+ ions and thiourea in basic media. Scanning electron microscope and X-ray diffraction analysis were made on as-deposited and on annealed films to determine their structure. The different electronic transitions and the optical constants are determined from the transmision and reflection data of these thin films for normal incidence. The optical gaps of Bi2S3 films show a remarkable dependence on the preparation method.Tanki su slojevi bismut sulfida (Bi2S3) načinjeni dvjema metodama, vakuumskim naparavanjem i kemijskim taloženjem. Ti su se slojevi istraživali sustavno-pretražnom elektronskom mikroskopijom i difrakcijom rentgenskog zračenja, prije i nakon termičkog opuštanja. Našao se je niz elektronskih prijelaza i odredile se optičke konstante na osnovi transmisijskih i refleksijskih podataka za okomitu upadnu svjetlost. Optički procijepi Bi2S3 pokazuju priličnu ovisnost o metodi pripremanja

Enhancement of On-grid PV System under Irradiance and Temperature Variations Using New Optimized Adaptive Controller

Solar Energy is one of the key solutions to future electrical power generation. Photovoltaic Plants (PV) are fast growing to satisfy electrical power demand. Different maximum power point tracking techniques (MPPT) are used to maximize PV systems generated power. In this paper, on grid PV system model in MATLAB SIMULINK is tested under sudden irradiance and cell temperature variations. Incremental Conductance MPPT is used to maximize generated power from the PV system with the help of new adaptive controller to withstand these heavy disturbances. The new adaptive controller is tuned for optimal operation using two different optimization techniques (Invasive weed and Harmony search).Optimization results for the two techniques are compared. .A robustness test is made to check system stability to withstand different random irradiance and cell temperature patterns without failure to track the maximum power point.Finally, a brief comparison is made with a previous literature and the new adaptive controller gives better results

A Framework for Research Supervision

One of the main challenges that are encountered in research development is the management of research activities. Supervisors often have difficulties in managing schedules, issues and supervision of different research activities. This is compounded by students’ poor research skills. Consequently, in this paper, we propose a knowledge management framework to point out, track, and monitor various research supervision activities. The proposed framework consists of two layers, abstract and detail. The abstract layer consists of six stages which are; basement stage, review stage, data collection stage, data analysis stage, development stage, and testing and validation stage. These stages, according to our framework, are mandatory; in other words, any research must go through the stages. To complete the task of each stage, a number of steps are defined, which constitute the detail layer. A supervisor is able to pick up appropriate steps (and not all suggested steps) from the detail layer since the complexity varies from one research to another. We discuss the results of our findings in conceiving the framework. Keywords: research development, development stage, research activities, supervision managemen

Kinetic Spectrophotometric Determination of Certain Cephalosporins in Pharmaceutical Formulations

A simple, reliable, and sensitive kinetic spectrophotometric method was developed for determination of eight cephalosporin antibiotics, namely, Cefotaxime sodium, Cephapirin sodium, Cephradine dihydrate, Cephalexin monohydrate, Ceftazidime pentahydrate, Cefazoline sodium, Ceftriaxone sodium, and Cefuroxime sodium. The method depends on oxidation of each of studied drugs with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 610 nm. The initial rate and fixed time (at 3 minutes) methods are utilized for construction of calibration graphs to determine the concentration of the studied drugs. The calibration graphs are linear in the concentration ranges 5–15 μg mL−1 and 5–25 μg mL−1 using the initial rate and fixed time methods, respectively. The results are validated statistically and checked through recovery studies. The method has been successfully applied for the determination of the studied cephalosporins in commercial dosage forms. Statistical comparisons of the results with the reference methods show the excellent agreement and indicate no significant difference in accuracy and precision

Effect of drilling and wellbore geometry parameters on wellbore temperature profile: Implications for geothermal production

Prediction of the wellbore fluids and formation temperatures is crucial during drilling operation, especially for high temperature wells, such as geothermal applications. This work presents the applications of an improved comprehensive drilling simulator for predicting the wellbore system temperature during the drilling process. A fully transient numerical model of the wellbore temperature is developed for drilling and geothermal production applications. The model describes the dynamic behaviour of the thermal state of the wellbore during circulation and static conditions. The developed model is implemented with the commercial virtual drilling simulator through an application programming interface. This implementation allows the coupling of the thermal model with other physical models, which leads to more advanced and realistic simulations. The model has been previously validated through a direct comparison with field data from geothermal well located in the Hanover area in Germany. The results showed a good agreement between the predicted outlet fluid temperature and the measured one. Furthermore, an analysis of the effect of various parameters on the wellbore system temperature is performed. This analysis showed the impact of these parameters on the wellbore temperature profile including the critical areas such as the casing setting point and bottom hole assembly. This information may lead to enhancing the wellbore stability by monitoring the thermal stresses, especially in high-temperature wells. Moreover, predicting the drill bit temperature can result in increasing the lifetime of the bit by adjusting the operating conditions to keep the bit temperature within the specified range. Based on these results, the enhanced drilling simulator with the transient temperature model showed to be a suitable tool for effective well planning.Document Type: Original articleCited as: Abdelhafiz, M. M., Oppelt, J., Mahmoud, O., Hegele, L. A. Effect of drilling and wellbore geometry parameters on wellbore temperature profile: Implications for geothermal production. Advances in Geo-Energy Research, 2023, 8(3): 170-180. https://doi.org/10.46690/ager.2023.06.0