Atomistic Simulation of Na+ and Cl- Ions Binding Mechanisms to Tobermorite 14Å as a Model for Alkali Activated Cements

The production of ordinary Portland cement (OPC) is responsible for ~8% of all man-made CO2 emissions. Unfortunately, due to the continuous increase in the number of construction projects, and since virtually all projects depend on hardened cement from the hydration of OPC as the main binding material, the production of OPC is not expected to decrease. Alkali-activated cement produced from the alkaline activation of byproducts of industries, such as iron and coal industries, or processed clays represents a potential substitute for OPC. However, the interaction of the reaction products of AAC with corrosive ions from the environment, such as Cl-, remains largely unexamined. In this study, we present the details of preparing undoped and 5% Na-doped tobermorite 14Å structures as molecular models for the disordered alkali-doped calcium-alumino-silicate-hydrate (C-(N)-A-S-H, where N represents sodium and A represents aluminum) structure, which is the main reaction product in Ca-rich AAC. Moreover, we examined the ability of these structures to hinder the ingress of solvated Na+ and Cl- ions using molecular dynamics simulations. We adopted a core-shell model for these simulations to represent the polarizability of oxygen ions and a flexible model to represent water molecules. The combined interatomic interactions adopted in this work accurately predicted lattice parameters and basic mechanical properties similar to those obtained from different experimental and computational studies for the tobermorite 14Å structure. Moreover, these interactions could predict lattice parameters similar to those predicted by the ClayFF force field, a widely used force field to describe cementitious materials. By examining the structural, energetic, and dynamic properties of interfacial water molecules and solvated Na+ and Cl- ions, we showed that introducing Na+ ions as dopants to the bulk tobermorite 14Å structure had a positive impact on enhancing the adsorption of solvated Cl- ions. This positive impact is twofold; first, new and stable adsorption sites have been introduced on the surface of the 5% Na-doped system because of the charge balancing mechanism taking place while substituting Ca2+ ions with Na+ ions. Second, introducing the 5% Na+ ions led to slower dynamics for all species in this system. The slow dynamics originated from the excess Na+ ions in this system, and that NaCl is a structure-making salt. These results suggest that the presence of Na in Ca-rich AAC results in more resistance to chloride-induced corrosion due to an increased ability to hinder the movement of Cl- ions. In addition to the effectiveness of these types of cement to resist Cl- ions diffusivity, these results from molecular-scale simulations also encourage the usage of sustainable AACs, which directly reduce the immense volume of greenhouse emissions produced annually from the OPC industry

Accurate Spectral Algorithms for Solving Variable-order Fractional Percolation Equations

A high accurate spectral algorithm for one-dimensional variable-order fractional percolation equations (VO-FPEs) is considered.We propose a shifted Legendre Gauss-Lobatto collocation (SL-GLC) method in conjunction with shifted Chebyshev Gauss-Radau collocation (SC-GR-C) method to solve the proposed problem. Firstly, the solution and its space fractional derivatives are expanded as shifted Legendre polynomials series. Then, we determine the expansion coefficients by reducing the VO-FPEs and its conditions to a system of ordinary differential equations (SODEs) in time. The numerical approximation of SODEs is achieved by means of the SC-GR-C method. The under-study’s problem subjected to the Dirichlet or non-local boundary conditions is presented and compared with the results in literature, which reveals wonderful results

Deep HMResNet Model for Human Activity-Aware Robotic Systems

Endowing the robotic systems with cognitive capabilities for recognizing daily activities of humans is an important challenge, which requires sophisticated and novel approaches. Most of the proposed approaches explore pattern recognition techniques which are generally based on hand-crafted features or learned features. In this paper, a novel Hierarchal Multichannel Deep Residual Network (HMResNet) model is proposed for robotic systems to recognize daily human activities in the ambient environments. The introduced model is comprised of multilevel fusion layers. The proposed Multichannel 1D Deep Residual Network model is, at the features level, combined with a Bottleneck MLP neural network to automatically extract robust features regardless of the hardware configuration and, at the decision level, is fully connected with an MLP neural network to recognize daily human activities. Empirical experiments on real-world datasets and an online demonstration are used for validating the proposed model. Results demonstrated that the proposed model outperforms the baseline models in daily human activity recognition.Comment: Presented at AI-HRI AAAI-FSS, 2018 (arXiv:1809.06606

Classification of Periodontal Diseases – Old is Gold or New is Bold? A Survey Study in Egypt

Background: A consensus was reached for a new classification system for periodontal and peri-implant diseases and conditions and was proposed by a group of world experts in 2017. Since then, there have been ongoing debates among periodontists regarding the application of the new classification. This study aims to shed light on the current understanding of the new classification among Egyptian periodontists. Methods: This cross-sectional survey study was performed using an anonymous manually distributed questionnaire in various universities in Egypt. The validated questionnaire included 15 questions – 13 multiple choice questions with a Likert scale and two open ended questions, in addition to demographic data of the participant. Qualitative data were presented as frequencies and percentages, and binary and ordinal logistic regression analyses were performed. Results: The clarity of the new classification was the only significant predictor for satisfaction. An increase in clarity scores was directly associated with an increase in satisfaction scores (odds ratio = 5.521, 95% CI = 2.198 – 8.844, P-value = 0.001). Only 24.2% of the participants actually applied the new classification. There was a high approval rate on the introduction of “health on reduced periodontium” and the classification of peri-implant conditions. However, there was a huge dissatisfaction with applying the staging and grading system as well as the omission of aggressive periodontitis. Conclusions: This survey has identified important gaps between theory and practice and bridging these gaps by revising the controversial points would help develop a clearer, simpler system for clinicians to improve patients’ oral health

Changes in dietary habits during Covid-19 lockdown in Egypt: the Egyptian COVIDiet study

Purpose COVID-19 lockdown changed social habits and lifestyle, including dietary habits, of people worldwide. However, limited information is available about these changes in Egypt. This cross-sectional study investigates the effects of COVID-19 lockdown on dietary habits among the Egyptian populations. Methods An online questionnaire, based on sociodemographic data and dietary adherence in accordance with the validated PREDIMED MedDiet Adherence Screener (MEDAS), was used all over the Egyptian governorates. The dietary changes were statistically evaluated for significance in relation to age, gender, body mass index (BMI), education level and governorates. Results A total of 1010 participants (76% aged below 36 years, 77% female, 22% obese, and 62% universitylevel education) answered the questionnaire. Respondents ≤ 20 years had a significant increase in weight and consumption of carbonated beverages, commercial pastries, fried and fast food. Egyptians > 50 years old had a significant decrease in physical activity. Underweight people (less than 3% of participants) increased their fast food intake with a prominent rise in weight. However, obese people increased cooking frequency and increased eating times with a decrease in physical activity. Male participants reported increased intake of carbonated beverages and fast food, while female participants increased the intake of homemade pastries with a significant decrease in physical activity. Approximately 50% of participants with postgraduate education reported decreased intake of fast food and carbonated beverages as well as decreased body weight. Residents of Cairo showed a significant increase in vegetable intake, and fried food intake with a decrease in seafood consumption. Participants from the Delta region had a significant increase in pastries intake. Conclusion The findings of this study explored the need for increasing awareness about healthy lifestyle in future lockdown periods

SYNCHRONOUS FLUORESCENCE SPECTROSCOPY COUPLED WITH CONTINUOUS WAVELET TRANSFORMS AND SAVITZKY-GOLAY DERIVATIZATION TECHNIQUE FOR THE SIMULTANEOUS DETERMINATION OF TADALAFIL AND DAPOXETINE HCl.

Objective: A novel combination of Tadalafil (TAD) and Dapoxetine HCl (DAP) has been recently introduced into the market for the treatment of premature ejaculation. The aim of this work is the development and validation of simple, sensitive and accurate analytical methods for the determination of TAD and DAP in their binary mixture without prior separation.Methods: Synchronous fluorescence spectroscopic (SFS) methods coupled with continuous wavelet transforms (CWT) and Savitzky-Golay (SAVGOL) derivatization technique have been developed.Results: Under optimum conditions, TAD and DAP were determined in the concentration ranges of 0.01–3 µg/ml and 0.01–1.2 µg/ml, respectively.Conclusion: The developed methods have the requisite accuracy, selectivity, sensitivity and precision and were satisfactorily applied for the simultaneous determination of TAD and DAP in bulk powder and pharmaceutical preparations. The results obtained for the analysis of both drugs in their pure forms by the proposed methods were statistically compared to those obtained by applying a reported high performance liquid chromatographic method (HPLC) method. The statistical comparison showed that there is no significant difference between the proposed methods and the reported one with respect to accuracy and precision.Keywords: Synchronous fluorescence spectroscopy, Tadalafil, Dapoxetine HCl, Continuous wavelet transforms, Savitzky-Golay techniqu

Family of ruled surfaces generated by equiform Bishop spherical image in Minkowski 3-space

The study of a family of equiform Bishop spherical image ruled surfaces created by some specific curves such as spherical image in Minkowski 3-space using equiform Bishop frame of that curve is presented in this paper. We also offer the necessary criteria for these surfaces to be equiform Bishop developable and equiform Bishop minimum in relation to equiform Bishop curvatures, as well as when the curve is enclosed in a plane. Finally, we provide an example, such as these surfaces