A variety of ashes used as the binder in geopolymer concrete such as fly ash (FA), ground granulated blast furnace slag (GGBS), rice husk ash (RHA), metakaolin (MK), palm oil fuel ash (POFA), and so ...on, among of them the FA was commonly used to produce geopolymer concrete. However, one of the drawbacks of using FA as a main binder in geopolymer concrete is that it needs heat curing to cure the concrete specimens, which lead to restriction of using geopolymer concrete in site projects; therefore, GGBS was used as a replacement for FA with different percentages to tackle this problem. In this study, Artificial Neural Network (ANN), M5P-Tree (M5P), Linear Regression (LR), and Multi-logistic regression (MLR) models were used to develop the predictive models for predicting the compressive strength of blended ground granulated blast furnace slag and fly ash based-geopolymer concrete (GGBS/FA-GPC). A comprehensive dataset consists of 220 samples collected in several academic research studies and analyzed to develop the models. In the modeling process, for the first time, eleven effective variable parameters on the compressive strength of the GGBS/FA-GPC, including the Activated alkaline solution to binder ratio (l/b), FA content, SiO2/Al2O3 (Si/Al) of FA, GGBS content, SiO2/CaO (Si/Ca) of GGBS, fine (F) and coarse (C) aggregate content, sodium hydroxide (SH) content, sodium silicate (SS) content, (SS/SH) and molarity (M) were considered as the modeling input parameters. Various statistical assessments such as Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R2) were used to evaluate the efficiency of the developed models. The results indicated that the ANN model better predicted the compressive strength of GGBS/FA-GPC mixtures compared to the other models. Moreover, the sensitivity analysis demonstrated that the alkaline liquid to binder ratio, fly ash content, molarity, and sodium silicate content are the most affecting parameter for estimating the compressive strength of the GGBS/FA-GPC.
An impressive amount of investigation has been devoted to enhancing overall thermal and hydrodynamic performance of microchannel heat sinks. The small size of microchannel heat sinks and their ...ability to dissipate heat generated by modern electronics makes them the first choice for the electronic cooling systems in most devices. In this paper, a comprehensive review of available studies regarding non-circular microchannel heat sinks, with emphasis on rectangular microchannels, was presented and analyzed. This review looked into the methodologies used to analyze and optimize the overall performance of microchannel systems along with channel geometries, flow conditions, the coolants used, structural materials, optimization tools and finally, the form in which the final outcome of each study was presented. The review showed that earlier studies (from 1981 to 1999) were largely conducted using experimental or analytical approaches while more recent studies (from 2000 to the end of 2012) showed a dependency on numerical simulations and evolutionary algorithms. In addition, they also showed that laminar was the prevailing flow condition as out of the 69 articles reviewed, 54 employed laminar flows. Furthermore, the use of liquid coolants was preferable over gaseous coolants. Recent developments in nanofluids are providing alternative coolants that are quickly establishing as coolants to be reckoned with.
Background
Although medical school regulation is ubiquitous, the extent to which it should be based on global principles is unclear. In 2010, the Educational Commission for Foreign Medical Graduates ...(ECFMG) announced that from 2023, overseas doctors would only be eligible for certification to practise in the United States if they had graduated from a medical school that was accredited by a ‘recognised’ agency. This policy empowered the World Federation for Medical Education (WFME) to create a recognition programme for regulatory agencies around the world, despite a lack of empirical evidence to support medical school regulation.
Methods
This study employs critical discourse analysis, drawing on the theoretical perspectives of Michel Foucault and Edward Said, to identify discourses that enabled this ‘globalising’ policy decision to take place. The dataset includes a series of 250 documents gathered around three key events: the Edinburgh declaration by WFME in 1988, the first set of global standards for medical schools by WFME in 2003 and the ECFMG ruling about medical school accreditation in 2010.
Findings
Two discourses, endorsement and modernisation, were dominant throughout this entire period and framed the move to globalise medical school regulation in terms of altruism and improving medical education worldwide. A discourse of resistance was present in the earlier period of this study but faded away as WFME aligned itself with ECFMG after 2010. Two further discourses, protection and control, emerged in the later period of this study and framed the ECFMG ruling in terms of nationalism and protecting American interests.
Discussion
This study proposes a new conceptualisation of the relationship between ECFMG and WFME in light of the apparently contradictory policy motivations of altruism and nationalism. It goes on to consider the implications of this association for the legitimacy of WFME as an organisation that represents all of the world's medical schools.
Rashid employs critical discourse analysis to explore the globalisation of medical school regulation and its role in quality improvement.
The emergence of the Asian invasive malaria vector, Anopheles stephensi, has been identified in Khartoum, the capital city of Sudan. This is the first report that confirms the geographical expansion ...of this urban mosquito into Central Sudan. We urgently recommend the launch of a national entomological survey to determine the distribution of this invasive disease vector and to generate essential information about its bionomics and susceptibility to available malaria control measures.
Geopolymers are innovative cementitious materials that can completely replace traditional Portland cement composites and have a lower carbon footprint than Portland cement. Recent efforts have been ...made to incorporate various nanomaterials, most notably nano-silica (nS), into geopolymer concrete (GPC) to improve the composite’s properties and performance. Compression strength (CS) is one of the essential properties of all types of concrete composites, including geopolymer concrete. As a result, creating a credible model for forecasting concrete CS is critical for saving time, energy, and money, as well as providing guidance for scheduling the construction process and removing formworks. This paper presents a large amount of mixed design data correlated to mechanical strength using empirical correlations and neural networks. Several models, including artificial neural network, M5P-tree, linear regression, nonlinear regression, and multi-logistic regression models, were utilized to create models for forecasting the CS of GPC incorporated with nS. In this case, about 207 tested CS values were collected from literature studies and then analyzed to promote the models. For the first time, eleven effective variables were employed as input model parameters during the modeling process, including the alkaline solution to binder ratio, binder content, fine and coarse aggregate content, NaOH and Na
2
SiO
3
content, Na
2
SiO
3
/NaOH ratio, molarity, nS content, curing temperatures, and ages. The developed models were assessed using different statistical tools such as root mean squared error, mean absolute error, scatter index, objective function value, and coefficient of determination. Based on these statistical assessment tools, results revealed that the ANN model estimated the CS of GPC incorporated with nS more accurately than the other models. On the other hand, the alkaline solution to binder ratio, molarity, NaOH content, curing temperature, and ages were those parameters that have significant influences on the CS of GPC incorporated with nS.
The "yue X, yue Y" construction is a construction with a relatively high usage rate of spoken Chinese. It means that there is a certain relationship between two different elements. This article ...analyzes this structure from the perspective of cognitive linguistics construction grammar Analyze to prove that it represents a relationship of "quantity" change, not just the "dependency relationship" that scholars previously said. The two elements in this structure have either a positive or a reverse relationship between "X" and "Y", and this increase or decrease involves the quantity of the two elements, regardless of whether the quantity is measurable The material quality is still the mental energy that can be felt. From the perspective of syntax, this construction can reflect the compactness of Chinese, and from the perspective of pragmatics, it can reflect the economic principles of Chinese. Finally, the thesis also involves the extended usage of the construction "yue lai yue"
Background: Placenta is a transient organ during pregnancy, connects the fetus to the uterine wall. Pregnancy is frequently complicated by gestational diabetes, which might cause morphological ...changes in the placenta (weight, diameter, and cotyledons number); consequently, it may affect both fetus and mother. Aim: The aim of this study was to determine the difference in placental cotyledons number between pregnant with gestational diabetes versus without gestational diabetes, then correlate it with the weight and diameter between groups. Materials and Methods: A comparative study (gestational diabetes Group A and nongestational diabetes Group B) included mothers with a singleton baby delivered at term (37-40 weeks) after acceptance of the informed consent. Women with pregestational diabetes and other chronic diseases and those with intrauterine fetal death were excluded. Postdelivery placentae were accurately prepared and examined in detail. The placental weight, diameter, and cotyledons number were recorded and analyzed by SPSS version 21. The correlation was measured between the two groups in terms of cotyledons count, placental diameter, and weight. Results: The study included 385 participants (128 Group A and 257 Group B). Placental number of cotyledons, weight, and diameter in Group A were higher than in Group B, and the difference was significant (P = 0.000, P = 0.021, and P = 0.000, respectively). In Group A, there was a significant correlation between the placental weight, diameter, and number of its cotyledons (r = 0.23, P = 0.011). Cotyledon count was significantly affected by diabetic control (P = 0.021). Conclusions: Gestational diabetes increases placental cotyledons number, weight, and diameter.
The use of nano-materials to improve the engineering properties of different types of concrete composites including geopolymer concrete (GPC) has recently gained popularity. Numerous programs have ...been executed to investigate the mechanical properties of GPC. In general, compressive strength (CS) is an essential mechanical indicator for judging the quality of concrete. Traditional test methods for determining the CS of GPC are expensive, time-consuming and limiting due to the complicated interplay of a wide variety of mixing proportions and curing regimes. Therefore, in this study, artificial neural network (ANN), multi-expression programming, full quadratic, linear regression and M5P-tree machine learning techniques were used to predict the CS of GPC. In this instance, around 207 tested CS values were extracted from the literature and studied to promote the models. During the process of modeling, eleven effective variables were utilized as input model parameters, and one variable was utilized as an output. Four statistical indicators were used to judge how well the models worked, and the sensitivity analysis was carried out. According to the results, the ANN model calculated the CS of GPC with greater precision than the other models. On the other hand, the ratio of alkaline solution to the binder, molarity, NaOH content, curing temperature and concrete age have substantial effects on the CS of GPC.
To evaluate the effects of post length, post material, and substance loss on the fracture resistance of endodontically treated mandibular premolars.
A total of 96 extracted human mandibular first ...premolars were endodontically treated and divided into 12 test groups (n = 8 each) based on the number of residual walls (one/two), post material (glass-fiber/titanium), and post length (5 mm, 7.5 mm, and 10 mm). After luting the posts, specimens received a composite resin core and a crown preparation with a 1.5-mm ferrule. Cast cobalt-chromium crowns were cemented using glass-ionomer cement. After 1,200,000 chewing cycles with a load of 49 N and simultaneous thermocycling (5°C to 55°C), specimens were quasi-statically loaded at 30 degrees to the longitudinal axis of the tooth until fracture. Fracture loads were analyzed using three-way, two-way, and one-way analysis of variance (α = .05). Fracture modes were examined under a stereomicroscope (×25) and recorded.
Fracture loads ranged from 642 ± 190 N (one wall, glass fiber, 5 mm) to 1,170 ± 130 (two walls, titanium, 7.5 mm). The mean fracture load of titanium posts was significantly higher than that of glass-fiber posts (P < .001), and the 7.5-mm post length exhibited significantly higher fracture loads than groups with 5-mm and 10-mm post length (P = .008).
Teeth restored with titanium posts revealed considerably higher fracture resistance than teeth restored with glass-fiber posts, especially if 7.5-mm-length posts were used.
In the recent decade, supplementary cementing ingredients have become an essential part of various strength ranges of concrete and cement-mortar mix design. Examples are natural materials, ...by-products, industrial wastes, and materials that require less energy and time to generate. Fly ash is one of the most widely utilized additional cementing ingredients. Fly ash is a by-product substance produced by coal combustion. It's being used in cement mortar and concrete as a pozzolanic substance. It has demonstrated significant influence in improving liquid and solid properties of cement mortar, such as compressive strength. Multi Expression Programming (MEP) is employed in this study to estimate the compressive strength (CS) of cement mortar modified with fly ash. The outcomes of this model were compared and evaluated with several other models such as the Nonlinear Regression model (NLR), Artificial Neural Network (ANN), and M5P-tree models that have been used in the construction fields. The input parameters included water/cement ratio (w/c), curing time (t days), and fly ash content (FA %), while the target property was compressive strength up to 360 days of curing. Four hundred fifty (450) data are collected from previous literature on modifying cement mortar with fly ash for that purpose. The water/cement ratio ranged from 0.24 to 1.2, and the fly ash was used to replace cement up to 55% (%wt. of dry cement). Based on the Coefficient of Determination (R
2
), Root Mean Squared Error (RMSE), Scatter Index (SI), Objective (OBJ), Mean Absolute Error (MAE), t-test value, the uncertainty of 95%, Performance Index (ρ), and boxplot for actual and predicted compressive strength. The MEP model performed better than other developed models according to evaluation tools. The compressive strength was also correlated with flexural and splitting tensile strengths using different nonlinear models.
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