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Abstract The current study aims at predicting the strength of the problematic clayey soils treated with combinations of pozzolan of natural sources and lime powder when added as soil additives at a nano scale. Multiple linear regression (MLR), artificial neural networks (ANN) and fuzzy logic (FL) tools were employed in the analytical study. The variables of the present study include the following: nano pozzoaln of natural source (NNP) content, nano lime content (NL), median particle size of NNP, active silica content of NNP (SiO2active), Initial liquid limit (ILL) and initial plastic limit (IPL) of the investigated soils. NNP was added at five percentages, i.e. 0%, 0.5%, 1%, 1.5% and 2%, while NL was added at five percentages, i.e. 0%, 0.3%, 0.6%, 0.9% and 1.2%. Three median particle sizes namely 50, 100 and 500 nm size were studied. Based on the different investigated soils and combinations, 120 soil mixtures were prepared and tested. California bearing ratio (CBR) and plasticity index (PI) were particularly examined. CBR tests were conducted at a soaked condition on specimens compacted to a maximum dry density (MDD) at the optimum moisture content (OMC). PI values were obtained following the Atterberg limits test. Based on the results of the performance criteria of the developed predictive models, it can be concluded that the CBR and PI of the expansive clayey soils can be effectively predicted using ANN and FL techniques. The results obtained by MLR were far from those obtained by both ANN & FL. In addition, ANN tool was slightly more accurate than FL as far as prediction of CBR and PI is concerned. The higher capability of ANN & FL models in predicting CBR & PI values, which generally obtained through time-consuming and expensive tests, could be useful for geotechnical engineers to assess or design a new pavement project. Further, it is recommended to do a re-evaluation of the current study in future, particularly when more data is available in the literature.

The aim of the current study is to estimate the graduation grade point average (GPA) at the Arab International University (AIU). The importance of this study is that it is the first of its kind in Syria, particularly under the conditions of the bitter war, which has not yet come to its end. The sample of the study consists of data collected from AIU registry system, which covers students of six faculties from both sexes over a period of 5 years, i.e., between 2014 and 2018. The variables of the study include the student's high school GPA, the source of the student's certificate, and the gender of the student (GR). MLR and ANN approaches were employed in the analytical study. The correlation coefficients and several statistical criteria were calculated to evaluate the developed models. Based on the results, it can be concluded that the male students were among the key factors affecting the output, i.e., GPA. In addition, ANN tool is more accurate when the estimation of GPA value is concerned. Further, re-evaluation of this study can be done in future particularly when the male student' trepidation disappears as stability and safety return to the country.

This study investigates the relationship between economic policy uncertainty (EPU) and the cost of equity capital (CoEC). It also reveals the moderating role of managerial ability (MA) in the relationship between EPU and CoEC in Saudi Arabia. The study sample consists of listed non-financial firms in Tadawul from 2008 to 2019. We analyzed data using STATA, depending on Pearson correlation analysis, two independent sample t-tests, OLS regression, and OLS with robust standard errors clustered by firm. Our study shows a positive effect of EPU on the CoEC. In addition, the results confirm that MA mitigates the positive effect of EPU on the CoEC. This is the first research to investigate the influence of the relationship between EPU on CoEC in Saudi Arabia, one of the largest emerging economies in the Middle East and Gulf countries. Our findings motivate decision-makers to strengthen their MA and establish a safe and stable investment environment to ensure better financing and investment decisions during uncertain times. Lending agencies, investors, and other stakeholders should consider the MA of corporations when making investment decisions.

The enhancement of electrode materials' properties for improving mercantile supercapacitors' performances is a remarkable research area. Throughout recent years, a significant amount of research has been devoted to improving the electrochemical performance of supercapacitors via the improvement of novel electrode materials. The nanocomposite structure provides a greater specific surface area (SSA) and lower ion/electron diffusion tracks, consequently enhancing supercapacitors' energy density and specific capacitance. These significant properties offer a wide range of potential for the electrode materials to be applied in diverse applications. For instance, their applications are in portable electronic systems such as all-solid-state supercapacitors, flexible/transparent supercapacitors and hybrid supercapacitors. The authors of this paper introduced a multi-criteria model to assess the priority of nanostructured electrode materials (NEMs) for high-performance supercapacitors (HPSCs). This work combines Analytic Hierarchy Process (AHP) with the Evaluation Based on Distance from Average Solution (EDAS) and Grey Relational Analysis (GRA) methods. Herein, the rough concept addresses the uncertainties resulting from the group decision-making process and the vague values of the properties of the NEMs. The modified R-AHP method was employed to find the criteria weights based on the multi-experts' opinions. The results reveal that specific capacitance (SC) and energy density (ED) are the most important criteria. R-AHP was integrated with R-EDAS and R-GRA models to evaluate the fourteen NEMs. The results of the R-EDAS method were compared with those provided by the R-GRA method. The results of the proposed integrated approach confirmed that it results in reliable and reputable ranks that will provide a framework for further applications and help physicists find optimal materials by evaluating various alternatives.

This study focuses on developing and characterizing multifunctional composites based on the diglycidyl ether of bisphenol-A (DGEBA) epoxy matrix. The aim is to enhance fire resistance and electrical conductivity properties for applications in various fields. To achieve this, aluminum tri-hydroxide (ATH) was incorporated as a flame retardant (FR) agent, while polyaniline (PANI) was added to impart electrical conductivity. The composites were categorized into three groups: the first containing flame retardant (FR), the second containing PANI for conductivity, and the third containing both PANI and FR for combined effects. E 60-FP emerged as the optimal multifunctional composite, exhibiting superior mechanical properties among the tested formulations. Thermogravimetric analysis (TGA) results provided valuable insights into the thermal stability of E 60-FP, revealing that it retained 42% of its initial mass at a temperature of 600 °C. Additionally, the composite achieved a V-0 rating in the UL 94 test, confirming its excellent fire resistance. Notably, E 60-FP displayed impressive mechanical strength, with a tensile strength of 7.2 MPa and a tensile modulus of 1117.6 MPa. Its flexural strength and modulus were measured at 31.2 MPa and 2800.2 MPa, respectively. Furthermore, the composite E 60-FP exhibited remarkable electrical conductivity, measuring 6.1 × 10 ^–6 S cm ^−1 . These findings highlight the potential of DGEBA epoxy composites containing PANI and ATH as promising materials for applications requiring fire resistance and electrical conductivity properties.

The addition of supplementary cementitious materials (SCM), particularly at nano level, leads to several benefits, such as the reduced permeability of concrete matrix, which consequently leads to having more durable and sustainable concrete. The dataset presented in the current paper was collected from two series of experiments. The natural pozzolana used in making concrete mixtures is of volcanic origin; i.e. volcanic scoria. The first series was conducted to test nano natural pozzolana-based concrete specimens on water penetration, while the second one was carried out to investigate the chloride ion penetrability of the latter specimens. Concrete specimens were prepared using nano natural pozzolana of two sizes and six replacement levels. Concrete mixes of four water/binder ratios were prepared. All experiments were conducted after five curing times; namely 2, 7, 28, 90 and 180 days. The collected dataset would be beneficial for concrete mix designers, concrete properties analyzers, construction project managers and scientific researchers. An attempt to correlate water permeability with chloride ion penetrability was made.

A glass composition using TeO2-K2TeO3-Nb2O5-BaF2 co-doped with Er2O3/Ho2O3 and Er2O3/Yb2O3 was successfully fabricated. Its thermal stability and physical parameters were studied, and luminescence spectroscopy of the fabricated glasses was conducted. The optical band gap, Eopt, decreased from 2.689 to 2.663 eV following the substitution of Ho2O3 with Yb2O3. The values of the refractive index, third-order nonlinear optical susceptibility (χ(3)), and nonlinear refractive index (n2) of the fabricated glasses were estimated. Furthermore, the Judd–Ofelt intensity parameters Ω t   (t = 2 , 4 , 6) , radiative properties such as transition probabilities (Aed), magnetic dipole-type transition probabilities (Amd), branching ratios (β), and radiative lifetime (τ) of the fabricated glasses were evaluated. The emission cross-section and FWHM of the 4I13/2→4I15/2 transition around 1.54 μm of the glass were reported, and the emission intensity of the visible signal was studied under 980 nm laser excitation. The material might be a useful candidate for solid lasers and nonlinear amplifier devices, especially in the communications bands. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between economic policy uncertainty (EPU) and the cost of equity capital (CoEC). It also reveals the moderating role of managerial ability (MA) in the relationship between EPU and CoEC in Saudi Arabia. The study sample consists of listed non-financial firms in Tadawul from 2008 to 2019. We analyzed data using STATA, depending on Pearson correlation analysis, two independent sample t-tests, OLS regression, and OLS with robust standard errors clustered by firm. Our study shows a positive effect of EPU on the CoEC. In addition, the results confirm that MA mitigates the positive effect of EPU on the CoEC. This is the first research to investigate the influence of the relationship between EPU on CoEC in Saudi Arabia, one of the largest emerging economies in the Middle East and Gulf countries. Our findings motivate decision-makers to strengthen their MA and establish a safe and stable investment environment to ensure better financing and investment decisions during uncertain times. Lending agencies, investors, and other stakeholders should consider the MA of corporations when making investment decisions. [ABSTRACT FROM AUTHOR]

Consistent with Sustainable Development Goal 5 (SGG 5) concerned with gender equality, this study examines the relationship between Board Gender Diversity (BGD) and environmental, social, and corporate governance (ESG) performance. In addition, it investigates the moderating role of governmental ownership concerning this relation by focusing on an emerging market. A sample of 71 Egyptian-listed companies on EGX100 during 2014–2019 has been examined. Both univariate and multivariate analyses are conducted to examine the relationship between BGD and ESG performance and the effect of governmental ownership on this relationship using OLS, 2SLS, and Logistic regressions. The results revealed a positive relation between BGD and ESG performance. In addition, we found that governmental ownership has a moderating effect on the relationship between BGD and ESG performance. This finding indicates that the effect of BGD on ESG performance in emerging markets is conditional on the governmental ownership, which provides a fertile environment for BGD to support ESG issues. The results add to the growing interest regarding the implications of BGD and governmental ownership for ESG performance in emerging economies. This study has significant implications for regulatory bodies, firms, and investors in emerging markets such as Egypt. It ensures that board gender diversity can enhance ESG performance in the case of governmental ownership. In addition, it highlighted the value of enforceable regulations on overseeing private firms' ESG performance. [ABSTRACT FROM AUTHOR]

The thermal and optical properties of 60TeO2-20K2TeO3-10WO3-10Nb2O5 (in mol%) glasses doped with Ho2O3, Er2O3, and Tm2O3 were explored in the present work. The thermal stability, refractive index n, extinction coefficient k, absorption coefficient α, and optical band gap of the glasses were evaluated. The UV–Vis–NIR absorption spectra, the Judd–Ofelt intensity parameter, the spectroscopic quality factor, and the emission and absorption cross-sections were calculated to investigate the effects of Er3+ and Tm3+, respectively, on the band spectroscopic properties of Ho3+ ions. The results showed that the maximum emission cross-section was approximately 8 × 10 − 21   c m 2 , and the values of the full width at half maximum ( F W H M) , quality factor ( σ e × F W H M) , and gain coefficient of Ho3+: 5I7 → 5I8 were also reported. The value of the F W H M × σ e was 1200 × 10 − 28   c m 3 , which showed greater gain characteristics than earlier study results. For 2   μ m mid-infrared solid-state lasers, the glasses that were examined might be a good host material. [ABSTRACT FROM AUTHOR]

The goal of the current paper is to study the effect of natural pozzolana (NP) when ground to a micro and nano size on some concrete properties. Syria is rich in natural pozzolana with an estimated quantity of nearly 1 billion tonnes. Four properties, namely compressive strength, chloride permeability, chloride-induced reinforcement corrosion and acid attack on mortar, have been investigated. Six levels of micro-NP (from 0% to 50%), and nano-NP (from 0% to 5%) were added as cement replacement to produce the studied concrete/mortar mixtures. The results revealed that grinding NP to extremely fine particles has positive effects. The shortcoming related to the lower early compressive strength can be eliminated. Further, much lower chloride permeability and longer corrosion initiation times were clearly observed in the concrete containing nano-NP. The best results were obtained when NP was added at 30% or more at micro-scale and at 3–4% at nano scale. Furthermore, acid resistance particularly at the early ages of exposure was noticeably improved with such additives. SEM technique fitted with EDX analysis was employed in the current research to study the microstructure of the cement paste after being exposed to acid solutions. XRD and TGA techniques were used as well.

The objective of this research was to investigate the effect of adding thermally treated clay on some engineering properties of the untreated expansive clayey soil. Three expansive clayey soil samples obtained from three different sites in the south of Syria have been investigated. They were thermally treated up to three different levels (450°C, 650°C and 850°C) for 3 hours. Three replacement levels of thermally treated clay were used, i.e. 0%, 10% and 20%. The X-ray diffractometer (XRD) technique has been used to detect the crystalline and glassy phase in the clayey samples before and after the thermal treatment. Pozzolanic activity of the thermally treated clayey soil has been studied using the modified Chapelle test and the mechanical strength test at each of the temperature levels. Atterberg limits, compaction, free swell, swelling pressure and linear shrinkage have particularly been investigated. Test results revealed the positive effect of thermally treated clay when added to the natural soil. Plasticity index (PI) was reduced by about 60% when 20% thermally treated clay was added to the natural soil. In addition, 6% lime was added to further investigate the combined effect of lime and calcined clay on the properties of the clayey expansive soil. All investigated properties were significantly improved when 20% thermally treated soil and 6% lime were added together. For instance, swelling pressure and linear shrinkage values were reduced to less than 15% or even much less when compared with those of the natural soil. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis were employed as well.

This study examines the effect of environmental, social, and governance (ESG) performance on auditor choice and audit opinion for Egyptian-listed firms. We use univariate and multivariate analyses of 612 firm-year observations for a sample of 68 firms listed on EGX100 over 2014–2022 using binary logistic regression models. Consistent with the ethical perspective of corporate social responsibility, we found that firms listed in the ESG index are more likely to assign one of the Big4 auditors, and less likely to receive a qualified opinion. Through an additional analysis, we found that COVID-19 moderates the relationship between ESG performance, auditor choice, and audit opinion. Our results confirm the value of ESG performance for audit practices in emerging economies. This research indicates that ESG performance can enhance financial reporting quality. Further, it ensures that binding guidelines and regulations are crucial to oversee corporate ESG performance, especially during crisis times, and enhance investors' protection and firms' sustainability. [ABSTRACT FROM AUTHOR]

Genome size is one of the fundamental cytogenetic features of a species, which is critical for the design and initiation of any genome sequencing projects and can provide essential insights in studying taxonomy, cytogenetics, phylogenesis, and evolutionary studies. However, this key cytogenetic information is almost lacking in the endemic species Reseda pentagyna and the locally rare species Reseda lutea in Saudi Arabia. Therefore, genome size was analyzed by propidium iodide PI flow cytometry and compared to k-mer analysis methods. The standard method for genome size measures (flow cytometry) estimated the genome size of R. lutea and R. pentagyna with nuclei isolation MB01 buffer were found to be 1.91 ± 0.02 and 2.09 ± 0.03 pg/2 °C, respectively, which corresponded approximately to a haploid genome size of 934 and 1.022 Mbp, respectively. For validation, K-mer analysis was performed on both species’ Illumina paired-end sequencing data from both species. Five k-mer analysis approaches were examined for biocomputational estimation of genome size: A general formula and four well-known programs (CovEST, Kmergenie, FindGSE, and GenomeScope). The parameter preferences had a significant impact on GenomeScope and Kmergenie estimates. While the general formula estimations did not differ considerably, with an average genome size of 867.7 and 896. Mbp. The differences across flow cytometry and biocomputational predictions may be due to the high repeat content, particularly long repetitive regions in both genomes, 71% and 57%, which interfered with k-mer analysis. GenomeScope allowed quantification of high heterozygosity levels (1.04 and 1.37%) of R. lutea and R. pentagyna genomes, respectively. Based on our observations, R. lutea may have a tetraploid genome or higher. Our results revealed fundamental cytogenetic information for R. lutea and R. pentagyna, which should be used in future taxonomic studies and whole-genome sequencing.

This paper aims to investigate the effect of volcanic scoria (VS) when added at micro or nano level on some concrete properties. Syria is rich in volcanic scoria with estimated reserves of nearly 1 billion tonnes. Three concrete properties, namely compressive strength, porosity and sulfate resistance, have been examined. Six percentages of micro-VS ranging from 0% to 50%, and nano-VS ranging from 0% to 5% have been used in making the investigated concretes. Test results revealed that the low early compressive strength of micro-VS-based concretes could be overcome by grinding VS to a nano size. In addition, significantly improved durability properties were obtained when VS was used either at micro or nano level. Much lower porosity and expansion values were clearly noted in the VS-based concretes. The efficiency factor (k) using the Bolomey equation and the durability indicator were evaluated to compare the behaviour of the VS-containing concrete with the reference concrete. The efficiency factor decreased with the increase of micro-VS/binder ratio and increased with the increase of nano-VS/binder. The calculated durability indicators showed that micro-VS content of 30% and nano-VS contents of 3 and 4% had approximately the highest indicator values. The replacement level of 30% at micro level and (3 & 4)% at nano level met k value of about 0.44 and 6, respectively, which would be useful for the designers of concrete mix. Based on the analyzed data, some relationships among the investigated properties were extracted. Further, scanning electron microscopy (SEM) technique and thermal gravity analysis (TGA) were employed in the current study to observe the resulting modifications in the microstructure of some VS-containing pastes. Large crystals of ettringite were observed in the pastes containing VS0 versus much smaller ones in the 3% nano-VS containing paste, after 52 weeks of exposure to 5% Na2SO4. Keywords: Volcanic scoria, Nanopozzolan, Compressive strength, Concrete durability, Sulfate attack, Efficiency factor

The role of social media as a marketing platform has become increasingly important as the number of retailers targeting young adults through social networking sites (snss) has grown, making these platforms central to their marketing strategies. A cross-sectional survey was conducted utilizing a self-administered questionnaire for testing the hypothesized research model. The sample group for the research comprised of 370 undergraduate and graduate students selected from four malaysian universities through cluster sampling. The results revealed that consumer intention was positively affected by utilitarian motivation, hedonic motivation, habit, and trust in snss. Multi-group analysis on the effect of usage habit as a moderating variable on the relationships between selected factors and the intention to purchase through snss revealed moderating effects of usage habit impacting relationships between utilitarian motivation and purchase intention (low habit usage β = .265) as compared to high habit usage of (β = .052). The theoretical and practical implications of the findings are offered, suggesting that marketing and online advertising strategists should be aware of the behaviour of online shoppers when planning online marketing campaigns for snss.

The benefits of using natural pozzolan as cement replacement are often associated with shortcomings such as the need to moist-curing for longer time and a reduction of strength at early ages. The objective of the study is to investigate the influence of binder fineness on the mechanical strength development of scoria-based binder mortars. In the study, mortar specimens have been produced with four types of binder: one plain Portland cement (control) and three scoria-based binders with three replacement levels: 25%, 30% and 35%, respectively. All scoria-based binders have been inter-ground into four different Blaine fineness: 2400, 3200, 4200 and 5100 cm2/g. The development of the compressive and flexural tensile strength of all mortar specimens with curing time has been investigated. The effects of the Blaine fineness of the scoria-based blended cement on the compressive and flexural strengths of mortar have been evaluated at curing ages of 2, 7, 28 and 90 days, respectively. Particle size distribution measured by a laser diffractometer has been considered in the study. Test results revealed that there is a decrease in strength with increasing amounts of scoria. In addition, there was found an increase in strength with increasing the Blaine fineness values. No direct relationship between Blaine and particle size distribution was observed. Effects of Blaine fineness on some physical properties of blended cements such as water demand, setting times and soundness have also been investigated. Further, an estimation equation for strength development incorporating the effects of fineness measured either by Blaine or by particle size distribution has been derived by the authors.

Numerous volcanic scoria (VS) cones are found in many places worldwide. Many of them have not yet been investigated, although few of which have been used as a supplementary cementitious material (SCM) for a long time. The use of natural pozzolans as cement replacement could be considered as a common practice in the construction industry due to the related economic, ecologic, and performance benefits. In the current paper, the effect of VS on the properties of concrete was investigated. Twenty-one concrete mixes with three w/b ratios (0.5, 0.6, and 0.7) and seven replacement levels of VS (0%, 10%, 15%, 20%, 25%, 30%, and 35%) were produced. The investigated concrete properties were the compressive strength, the water permeability, and the concrete porosity. Artificial neural networks (ANNs) were used for prediction of the investigated properties. Feed-forward backpropagation neural networks have been used. The ANN models have been established by incorporation of the laboratory experimental data and by properly choosing the network architecture and training processes. This study shows that the use of ANN models provided a more accurate tool to capture the effects of five parameters (cement content, volcanic scoria content, water content, superplasticizer content, and curing time) on the investigated properties. This prediction makes it possible to design VS-based concretes for a desired strength, water impermeability, and porosity at any given age and replacement level. Some correlations between the investigated properties were derived from the analysed data. Furthermore, the sensitivity analysis showed that all studied parameters have a strong effect on the investigated properties. The modification of the microstructure of VS-based cement paste has been observed, as well.

Zinc phosphate (ZnP) baths are widely used for increasing corrosion resistance and surface preparation for painting. Studies on exploiting these baths in the reinforced concrete (RC) are still in the early stages. This is probably due to the shortcomings, such as the alkaline instability and high porosity of the obtained coatings. Use of natural pozzolan (NP) as cement replacement is growing rapidly due to its economic, ecological, and technical benefits. The combined effect of using ZnP baths and NP-based cement on the resistance of concrete against damage caused by corrosion has been investigated. Four phosphating baths were prepared: ZnP, ZnP-Ni, ZnP-Cu, and ZnP-Mn. Steel specimens were phosphated at 55-60°C for 15 min. Concrete specimens were produced with four different levels of NP: 0% (control), 10 %, 20%, and 30%. The investigation was carried out using RC specimens where a constant anodic potential was impressed after 28 and 90 days of concrete curing. The electrochemical behavior of the coated steel has further been evaluated in chloride contaminated Ca(OH)2 saturated solution (CH-Cl) using the open circuit potential (OCP), the potentiodynamic polarization, and the polarization resistance with time. The bond strength between the coated steel and concrete has been evaluated by the pull-out test. Test results showed that concrete containing NP at higher replacement levels and steel specimens treated in bication baths exhibited corrosion initiation times several times longer than the control concrete with uncoated steel. In addition, the best corrosion performance was noted in the steel specimen treated in the ZnP-Cu bath. Its corrosion density was about twentyfold lower with respect to the bare steel, and its inhibition efficiency exceeded 95% in (CH-Cl) solution. In addition, its polarization resistance was about fifteenfold lower with respect to the bare steel. SEM, EDX, and XRD techniques have been employed, as well.

The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction). Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289) and accelerated mortar bar test (ASTM C1260) have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida’a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.