Differential transformation method (DTM) for solving SIS and SI epidemic models

In this paper, the differential transformation method (DTM) is employed to find the semi-analytical solutions of SIS and SI epidemic models for constant population. Firstly, the theoretical background of DTM is studied and followed by constructing the solutions of SIS and SI epidemic models. Furthermore, the convergence analysis of DTM is proven by proposing two theorems. Finally, numerical computations are made and compared with the exact solutions. From the numerical results, the solutions produced by DTM approach the exact solutions which agreed with the proposed theorems. It can be seen that the DTM is an alternative technique to be considered in solving many practical problems involving differential equations

An examination of teacher collaboration in professional learning communities and collaborative teaching practices

The present study aims to examine the influence of teacher collaboration within professional learning communities (PLCs) and collaborative teaching practices on both the professional growth and academic achievement of students. The study employed a mixed-methods research design that  incorporated both qualitative and quantitative research methodologies. This research comprises both survey responses and interview transcripts obtained from K-12 educators who are currently engaged in Professional Learning Communities (PLCs) or collaborative teaching methodologies. The findings of this study have the potential to enhance the existing literature on teacher collaboration and furnish educators, policymakers, and researchers with valuable perspectives to steer optimal strategies for promoting effective teacher collaboration in Professional Learning Communities (PLCs) and collaborative teaching approaches. The objective of the research is to investigate the influence of teacher collaboration within Professional Learning Communities (PLCs) and collaborative teaching practices on the development of professional skills and academic achievements of students. The results of this study underscore the importance of recognizing the advantageous effects that collaborative teaching methodologies can have on the academic achievements of students. This necessitates the provision of adequate time for collaborative activities, encouraging supportive leadership within educational institutions, and allocating sufficient resources for collaboration

The reality of the changing process of accounting policies in Jordanian touristic companies

This study aimed at recognizing the reality of the changing process of accounting polices in Jordanian touristic companies, the factories affecting it, the parties who takes part in taking the decision of changing, and if the decision is realistic and objective. This study is an explorative-analytical one, the researcher analysis 83 forms of the study sample.The main result was that the rules and regulations has no role in stopping changing the accounting policies. Administrations and different departments don't participate in changing the accounting policies, and the new administration makes the change only because it wants to. These companies make these changing to win borrowers, and there is a clear shortage in the foundation of the relative importance and lack of understanding qualitative characteristic for the information which leads to the changing of the accounting policies. The study strongly recommended organizing the process of the changing accounting polices in Jordanian touristic companies. Make the administrations and different departments in the foundation participate in the process of the changing accounting polices. And make use of the experience and capabilities of the outer parts specially offices of consultancy and auditing. And Jordanian touristic companies should equip it self with the clear foundation about the relative importance and try to understand the qualitative characteristic of information. All this with enough coordination with different administration in other Jordanian touristic companies when there is a change in the accounting polices. Key Words: tourism sector, accounting polices, touristic companies

Energy and exergy analysis of combined cooling and power system using variable mode adsorption chiller

Adsorption cooling is a promising technology to recover low-temperature waste heat from a diesel genset. In this paper, an advanced adsorption chiller working in variable mode is proposed for the combined cooling and power cycle (CCP) to recover waste heat from the water jacket in the diesel genset. The chiller works on three modes based on the ambient temperature for better heat utilization. In this study, three modes were investigated: single-stage cycle mode, short-duration, and medium-duration mass recovery modes. The results show that the energy and exergy efficiency for a single-stage cycle mode is higher at an ambient temperature lower than 35 °C . In comparison, the mass recovery mode has a higher energy and exergy efficiency at an ambient temperature higher than 35 °C. The annual energy and exergy efficiency for the CCP was investigated when the chiller works with variable modes based on the ambient temperature under DUBAI weather conditions as a case study. The results show an improvement of 14.7% and 14% of the energy and exergy efficiency, respectively, for CCP with a variable mode adsorption chiller compared to diesel genset alone. The results also show the CCP with variable mode adsorption chiller has a slight improvement on both energy and exergy efficiency compared to CCP with a single-stage adsorption chiller at the same ambient conditions

Energy and Exergy Analyses of Adsorption Chiller at Various Recooling-Water and Dead-State Temperatures

We conducted energy and exergy analyses of an adsorption chiller to investigate the effect of recooling-water temperatures on the cooling capacity and Coefficient of Performance (COP) with variable cycle modes. We investigated both the effect of the recooling-water temperature and the dead state temperature on the exergy destruction in the chiller components. Our results show that there is an optimum reheat cycle mode for each recooling-water temperature range. For the basic single stage cycle, the exergy destruction is mainly accrued in the desorber (49%), followed by the adsorber (27%), evaporator (13%), condenser (9%), and expansion valve (2%). The exergy destruction for the preheating process is approximately 35% of the total exergy destruction in the desorber. By contrast, the precooling process is almost 58% of the total exergy destruction in the adsorber. The exergy destruction decreases when increasing the recooling-water and the dead state temperatures, while the exergy efficiency increases. Nonetheless, the exergy efficiency decreases with an increase in the recooling-water temperature at fixed dead state temperatures. The effect of the mass recovery time in the reheat cycle on exergy destruction was also investigated, and the results show that the exergy destruction increases when the mass recovery time increases. The exergy destruction in the adsorbent beds was the most sensitive to the increase in mass recovery time

Performance Analysis of Variable Mode Adsorption Chiller at Different Recooling Water Temperatures

Adsorption cooling can recover waste heat at low temperature levels, thereby saving energy and reducing greenhouse gas emissions. An air-cooled adsorption cooling system reduces water consumption and the technical problems associated with wet-cooling systems; however, it is difficult to maintain a constant recooling water temperature using such a system. To overcome this limitation, a variable mode adsorption chiller concept was introduced and investigated in this study. A prototype adsorption chiller was designed and tested experimentally and numerically using the lumped model. Experimental and numerical results showed good agreement and a similar trend. The adsorbent pairs investigated in this chiller consisted of silicoaluminophosphate (SAPO-34)/water. The experimental isotherm data were fitted to the Dubinin–Astakhov (D–A), Freundlich, Hill, and Sun and Chakraborty (S–C) models. The fitted data exhibited satisfactory agreement with the experimental data except with the Freundlich model. In addition, the adsorption kinetics parameters were calculated using a linear driving force model that was fitted to the experimental data with high correlation coefficients. The results show that the kinetics of the adsorption parameters were dependent on the partial pressure ratio. Four cooling cycle modes were investigated: single stage mode and mass recovery modes with duration times of 25%, 50%, and 75% of the cooling cycle time (denoted as short, medium, and long mass recovery, respectively). The cycle time was optimized based on the maximum cooling capacity. The single stage, short mass recovery, and medium mass recovery modes were found to be the optimum modes at lower (44 °C) recooling temperatures. Notably, the recooling water temperature profile is very important for assessing and optimizing the suitable working mode

Assessment of antioxidant potential, cytotoxicity, and anticancer activity of methanolic extracts from selected wild medicinal plants

Introduction: Medicinal plants are considered an important source of human health because of their therapeutic capabilities in treating various diseases. This study aimed to evaluate the phytochemical profile, antioxidant, and cytotoxic activities of the methanolic extracts of three wild medicinal plants (Ruta graveolens, Peganum harmala and Citrullus colocynthis). Methods: The total phenolic content was determined according to the Folin–Ciocalteu method. The total flavonoid contents were measured by the aluminum chloride colorimetric method. The antioxidant activity was estimated based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays. The phytochemical analysis was performed using liquid chromatography-mass spectrometry method. The cytotoxicity and anticancer activity of each plant extract was investigated against fibroblast and MDA-MB-231 breast cancer cell lines, respectively, using Giemsa staining assay. Results: R. graveolens extract exhibited the highest concentrations of total phenols (25.5 ± 0.5 mg GA/g dry extract) and flavonoids (9.8 ± 0.5 mg Rutin/g dry extract). Additionally, it demonstrated the most robust antioxidant capacity, as demonstrated by both DPPH (100.8 ± 0.56 mg GA/g dry extract) and FRAP (91.2 ± 1.33 mg GA/g dry extract) assays. Within this plant, Rutin constituted 13.7 % of the total compounds. Furthermore, R. graveolens displayed the most significant anticancer activity, with statistical significance at p< 0.01. Notably, it exhibited the lowest cytotoxicity against the fibroblast cell line, even at the highest tested concentration of 100 μg/ml. In contrast, both P. harmala and C. colocynthis demonstrated substantial anticancer potential (p< 0.01); however, they both exhibited significant cytotoxicity against the fibroblast cell line (p<0.01). Conclusion: R. graveolens extract holds promise as a potential reservoir of safe and effective antioxidant and anticancer compounds for human use

Experimental study on lightweight concrete using lightweight expanded clay aggregate (leca) and expanded perlite aggregate (epa)

In pursuit of reducing the dead-weight of precast concrete structures, one approach is by adopting lightweight concrete. EN 13369:2013 specifies a minimum cube compressive strength of at least 18 MPa for the lightweight concrete to be eligible for use in reinforced precast concrete products. This study conducts an experiment using LECA and EPA to produce lightweight concrete for structural use. Density, concrete quality, and strength of various mixes are observed by conducting cube compressive test and UPV test. Two phases of experiments were conducted, where the first phase variable is the percentage of LECA replacing the normal coarse aggregate, while the second phase variable is the percentage of EPA replacing the sand proportion. The optimum concrete mix is found to be the mix with 60% LECA and 50% EPA replacements, which achieved D1.8 lightweight density category that surpasses the specified minimum cube compressive strength and falls under the good quality concrete type according to the UPV rating. In summary, the inclusion of LECA and EPA into the concrete mix will decrease the cube compressive strength, lower the density, escalate the slump value and the travelling time of the ultrasonic pulse, but at the same time able to produce lightweight structural concrete

The Ability of Rhizopus stolonifer MR11 to Biosynthesize Silver Nanoparticles in Response to Various Culture Media Components and Optimization of Process Parameters Required at Each Stage of Biosynthesis

One of the most important roles for nanotechnology concerns is the development of optimizable experimental protocols for nanomaterials synthesis. The formation of silver nanoparticles (AgNPs) was supported by Rhizopus stolonifer MR11, which was isolated from olive oil mill soil samples. The ability of R. stolonifer MR11 to biosynthesize silver nanoparticles in response to various components of different culture media was tested. Furthermore, the conditions under which the reducing biomass filtrate was obtained, as well as the conditions of the bio-reduction reaction of AgNO3 into AgNPs, were investigated. The fungal biomass filtrate of the strain Rhizopus stolonifer MR11 was capable of converting silver nitrate into AgNPs, as evidenced by the color change of the fungal filtrates. UV-Vis spectrophotometer, TEM, Zeta potential, Zeta sizer, FT-IR, and XRD analyses were used to characterize the AgNPs. TEM analysis revealed that the silver nanoparticles were 1–35 nm in size. R. stolonifer MR11 produced the maximum AgNPs when grown for 18 hours at 36 °C in media with starch and yeast extract as the sole carbon and nitrogen sources, respectively. The reducing biomass filtrate was obtained by incubating 5 g mycelial biomass in deionized water with a pH of 6 for 48 hours at 30 °C. The optimal reduction conditions of the biosynthesis reaction were determined by adding 1.0 mM AgNO3 to a pH 5 buffered mycelial filtrate and incubating it for 72 hours at 33 °C. The current study’s findings highlighted the importance of process parameters at each stage for optimal AgNPs biosynthesis