Structural and physical studies of PVC/PVDF doped Nano lithium salt for electrochemical applications

  Polymer blend of poly (vinyl chloride) and poly(vinylidene fluoride) of nominal composition (30PVC/70PVDF) wt:wt were prepared in the form of thin films using casting technique. Samples of the same composition doped with gradient concentration of nano lithium salt (LTO) were prepared and studied. Proposed filler was characterized using Fourier transform infrared spectroscopy (FTIR), UV/vis. optical absorption, X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Electron diffraction (ED).  Obtained data approve the crystalline nano structure of filler with a cubic structure of average size (25-30 nm). Prepared nano composites were then investigated using different spectroscopic methods. XRD reveals the amorphous nature of the base polymer blend with tendency for increase in crystallinity with increasing the content of lithium salt. FTIR shows a preservation of the main vibrational spectral bands in their position with small variation in the area and intensity of some spectral bands related to the interaction between polymer and filler. &nbsp

Red-sea dolomite as a sustainable catalyst in the synthesis of bis-indolyl methanes with molecular docking validation as HIV-1 replication inhibitor

ABSTRACT. Dolomite minerals were collected from the Red Sea Mountains around the Sokhna region. The rock was collected, rinsed, and crushed using a ball mailing machine and used without further purification. The dolomite sample was characterized using FTIR, XRD, SEM/EDAX, and mapping to ensure their composition and homogeneity. The obtained data reveal that the presence of a homogenous crystalline structure of CaMg(CO3)2. The characterized rock was used as a catalyst in the eco-friendly synthesis of bis-indolyl methane derivatives by reacting two moles of unsubstituted indole and various aromatic aldehydes in the presence of Red-Sea Dolomite mineral as an economical, recyclable, easily obtained, and nontoxic catalyst under solvent-free conditions. The molecular docking study explained that the bis-indolyl methane can be considered as a small molecule stimulator of HIV-1 frameshifting and inhibitor of viral replication.                     KEY WORDS: Indole, Dolomite, HIV-1, Catalyst, Frameshifting, Viral replication   Bull. Chem. Soc. Ethiop. 2021, 35(3), 647-657. DOI: https://dx.doi.org/10.4314/bcse.v35i3.1

Monotonic and Cyclic Behavior of Helical Screw Piles Under Axial and Lateral Loading

The main objectives of this research paper are to: investigate the monotonic and cyclic behavior of helical pile foundation systems, develop new helical screw systems suitable for seismic retrofitting of existing foundations and new structures. The proposed new pile configurations proposed include: fiber reinforced polymer grouted helical screw piles (FRP-G-HSP); and reinforced grouted helical screw piles (RG-HSP) with steel fibers added to the grout. The research methodology involved conducting more than one hundred full scale field load tests on twenty three helical screw piles installed in cohesive soil and subjected to axial and lateral monotonic and cyclic loading in which twenty piles are instrumented. The test piles included: seven plain helical screw piles (P-HSP); four grouted helical screw piles (G-HSPs); eight FRP-G-HSPs; and four RG-HSPs. The axial cyclic performance of HSPs and G-HSPs experienced 5-10% capacity reduction after 15 loads cycles. However, their lateral capacity was low due to their slender shaft. The lateral capacity and stiffness of internally and externally grouted FRP-G-HSPs were twice the FRP-HSP with internal grout. The RG-HSP piles axial capacity was more than twice that for P-HSP, with minimal reduction after cyclic loading, and their lateral capacity was more than 3 times the P-HSPs capacity

Structural and optical characteristics of poly(vinyl alcohol)/carboxymethyl cellulose/ curcumin nanocomposites

ABSTRACT. Curcumin nanoparticles (CurNP’s) were successfully synthesized, characterized, and used as a cross-linking dopant of polyvinyl alcohol/ sodium carboxymethyl cellulose (PVA/CMC) semi-natural polymer blend. Synthesized nanocomposite films of (PVA/CMC/CurNP’s) were characterized using Fourier transforms infrared FTIR spectroscopy and tested for their resistance of different bacterial grams. Obtained data shows that studied PVA polymerized and cross-linked with CMC as a result for hydrogen bonding between the carboxylic groups and with the non-substituted hydroxyl groups of the cellulose molecule. The optical energy gap was found to be sensitive for the CurNP’s doping level, and the indirect transition was dominant in the studied samples. The addition of CurNP’s appears to increase the activity index of all samples against both gram-negative and positive bacteria, and their activity increases with increasing dopant level until a specific optimal concentration.                     KEY WORDS: Curcumin nanoparticles, Semi-natural polymer blend, Antibacterial, FTIR, Optical energy gap   Bull. Chem. Soc. Ethiop. 2021, 35(3), 615-624. DOI: https://dx.doi.org/10.4314/bcse.v35i3.1

Synthesis and optimization of Novel Chitosan/Cellulose Acetate Natural Polymer Membrane for water treatment

Chitosan (Ch) and Cellulose Acetate (CA) natural polymer in addition to other samples with different mass fractions of Chitosan/Cellulose Acetate (Ch/CA) were synthesized via simple casting route. Prepared samples were studied using FT-IR and UV/vis spectroscopic techniques. Structural variations due to the process of blending were retraced using X-ray diffraction data (XRD) and morphological investigation using scanning electron microscopy (SEM). Obtained spectral data reveals compatibility and complexation between polymer constituents identified through presence of polymer characteristic peaks with small variation in both intensity and position along with change in the value of optical energy gap from UV optical absorption spectral data. XRD pattern indicate the semicrystalline nature of the studied sample with an observable change in the crystallinity. Moreover, scanning electron microscopic (SEM) micrographs reveals homogenous structure without any evidence for agglomerations nearly in all compositions

Modified Dijkstra Shortest Path Algorithm for SD Networks

This paper uses a modified Dijkstra shortest path method for considering cumulative delays rather than bandwidth in software-defined networks. To implement the proposed method, an open-source Ryu controller is used, and a Mininet tool is used to emulate the topology. The proposed method is compared with the traditional Dijkstra’s algorithm to demonstrate its performance. This comparison shows that the modified Dijkstra’s algorithm provides higher performance of the different cumulative delays. Several experiments were conducted to evaluate the performance of the proposed method using three parameters (bandwidth, transfer rate and jitter). In addition, the cumulative distribution function is calculated using the parameters to show its distribution through the experiment period

Corrosion mechanism and bioactivity of borate glasses analogue to Hench’s bioglass

Bioactive borate glasses (from the system Na2O-CaO-B2O3-P2O5) and corresponding glass-ceramics as a new class of scaffold material were prepared by full replacement of SiO2 with B2O3 in Hench patented bioactive glass. The prepared samples were investigated by differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The DTA data were used to find out the proper heat treatment temperatures for preparation of the appropriate glass-ceramics with high crystallinity. The prepared crystalline glass-ceramics derivatives were examined by XRD to identify the crystalline phases that were precipitated during controlled thermal treatment. The FTIR spectroscopy was used to justify the formation of hydroxyapatite as an indication of the bioactivity potential or activity of the studied ternary borate glasses or corresponding glass-ceramics after immersion in aqueous phosphate solution. The corrosion results are interpreted on the basis of suggested recent views on the corrosion mechanism of such modified borate glasses in relation to their composition and constitution

Effect of aluminum oxide on the structure and conduction behaviors of silver borate glasses

ABSTRACT. The current study focuses on glass preparation and characterization in the glass system of chemical formula xAl2O3 (35-x) Ag2O.65B2O3 (0≤x≤35 mol%), where Ag2O is replaced with Al2O3. To examine a wide range of both structure and morphology of the prepared glasses, nuclear magnetic resonance (NMR) of 27Al nuclei, X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM) are used. In Al2O3-rich glass, the well-formed AlO6, AlO5, and AlO4 structural groups are the well-formed units. In samples of (20 and 30 mol % Al2O3), tetrahedral AlO4 and traces from AlO6 units could be detected. At lower concentrations of Al2O3 (10 mol%), the dominant forming unit is only AlO4 groups containing non-bridging oxygen bonds (NBO). The XRD spectra confirm the amorphous nature of the glasses of Al2O3 ˂20 mol% while glasses of higher Al2O3 concentrations contain crystalline Ag2Al2B2O7 formed due to the higher oxygen packaging of the mixed AlO5 and AlO4 compared with that of glasses containing only AlO4 species only. The morphology of crystalline units is confirmed from TEM to differ from that of an amorphous composition. The increase of activation energy and the hardness number of the glasses led to an increase in the durability of the investigated glasses.   KEY WORDS: Aluminum borate glass, NMR, Coordination of aluminum atom, Conductivity, Crystallization process Bull. Chem. Soc. Ethiop. 2022, 36(3), 597-606.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i3.9                                                       &nbsp

Antecedents and consequences of intellectual capital: a systematic review, integrated framework, and agenda for future research

Data availability: Data available on request from the authors.JEL Classifcation: M40 · G34.This study systematically reviews the fragmented field of Intellectual Capital (IC) to clarify its antecedents and outcomes. Using a hybrid method that combines bibliometric analysis and a framework-based approach, it examines 170 peer-reviewed articles, focusing on key articles, authors, countries, journals, and themes in IC research. The study introduces a comprehensive framework, summarizing the core elements of IC and providing a foundation for future theoretical, empirical, and conceptual research. Six main clusters were identified through co-citation analysis: three related to IC antecedents, particularly board gender diversity, and three concerning IC consequences, notably firm performance. This research maps out existing gaps in the literature and suggests integrated pathways for advancing IC knowledge. It contributes significantly to IC studies by synthesizing a vast array of literature into an integrated framework, offering new insights that both challenge and complement existing narratives. This framework not only elucidates IC's foundational aspects but also sets a strategic direction for future investigations. The findings underscore the evolving nature of IC research and highlight crucial antecedents and consequences. The study bridges academic research with practical applications, emphasizing IC's role in boosting firm competitiveness and value creation. While recognizing its methodological limitations, the study calls for a diversified perspective in future IC research, aiming to deepen the understanding of IC.Not applicable

Molecular structure and optical attributes of (Na-CMC/SA) natural polymer blend

ABSTRACT. Biopolymers are referred to the bio-degradable polymer that is derived from living organisms in nature or synthesized from renewable materials but needs polymerization. There are consisting of monomeric units that bond together through a covalent bond to obtain large molecules. A biopolymeric blend of sodium carboxymethyl cellulose/sodium alginate (Na-CMC/SA) film was prepared by the casting/solvent evaporation method. In addition to the molecular structure, the optical and molecular geometry of the collected films were characterized. XRD of binary blend investigated the interaction and miscibility among two biopolymers. FTIR of the blend spectrum explicated the conferring of the two polymer group’s vibrations. UV/Vis and optical studies appeared a peak in the binary at the wavelength (227 nm) which explained the high combination between two polymers. Molecular geometry clarifies the assignment of vibrational spectra of pure polymers which implied the important role of the (C=O) group as eventful regions for the two polymers.   KEY WORDS: Sodium carboxymethyl cellulose, Sodium alginate, Na-CMC/SA, FTIR, XRD, UV/Vis   Bull. Chem. Soc. Ethiop. 2022, 36(3), 707-716.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i3.19                                                     &nbsp