Processing and fundamental characterization of carbon fibers and cellulose nanocrystals derived from bagasse

Amina Abdel Meguid Attia,Maged Shafik Antonious,Mona Abdel Hamid Shouman,Ahmed Ali Ahmed Nada,Khadiga Mohamed Abas 한국탄소학회 2019 Carbon Letters Vol.29 No.2

Lignocellulosic materials such as agricultural residues have been identified as potential sustainable sources that can replace petroleum-based polymers. This study focused on the conversion of lignin extracted from bagasse to carbon fiber (CF) and cellulose nanocrystal (CNC). The highest extraction of lignin yield was achieved at 100 °C using 10% NaOH for 12 h. Carbon fibers were obtained by electro-spinning of bagasse lignin blended with polyvinyl alcohol (PVA) (11 wt/v %) followed by thermo-stabilization (250 °C) in an oxidizing atmosphere and further carbonization in an inert atmosphere (850 °C). Conventional hydrolysis process was used to extract cellulose nanocrystal from bagasse pulp. Morphological (scanning electron microscopy, SEM), spectral (Fourier transform infrared, FTIR) spectroscopy, elemental analysis, thermal characterization and surface area measurements have been carried out. Figures originated by SEM showed that CF ranges from 145 to 204 nm, while stabilized bagasse cellulose nanocrystal (SCNC) appeared as rod-shape like structure in the range of length 600–800 nm and diameter 5.33–19 μm. Characterization results revealed that CF exhibits microporous structure, while bagasse lignin and SCNC display mesoporous structure. In addition, the results proved that SCNC exhibits a percentage removal 71.56% for methylene blue dye in an aqueous solution.

Local stability analysis and <i>H</i> _∞ performance for Lipschitz digital filters with saturation nonlinearity and external interferences

Shams, Amina,Rehan, Muhammad,Tufail, Muhammad,Ahn, Choon Ki,Ahmed, Waqas Elsevier 2018 Signal processing Vol.153 No.-

<P><B>Abstract</B></P> <P>This paper proposes a novel method to analyze the local stability of Lipschitz nonlinear digital filtering schemes under saturation overflow nonlinearity. Conditions for the stability analysis and robust performance estimation are provided in the form of matrix inequalities by utilizing Lyapunov theory, local saturation overflow arithmetic, and Lipschitz condition. The proposed criterion ascertains (local) asymptotic stability in the absence of perturbations. Under the effects of external interferences, a condition for the local stability, ensuring the <I>H</I> <SUB>∞</SUB> performance objective, is developed. The proposed approach offers a less conservative and more accurate estimate of <I>H</I> <SUB>∞</SUB> performance index than the global method by utilizing a bound on the interferences energy. Moreover, the proposed criterion, in contrast to the existing global methods, can be employed to choose an adequate word length of a digital hardware for the specified values of tolerable perturbations energy, <I>H</I> <SUB>∞</SUB> performance index, and fixed-point resolution. It is worth mentioning that analysis approaches have not been completely reported in the literature, in which local stability criteria for nonlinear discrete-time filtering prototypes under both overflow and disturbances have been developed. A detailed stability analysis for a nonlinear recurrent neural network is performed for demonstrating the effectiveness of the proposed scheme.</P>

Impact of Air Convection on H<SUB>3</SUB>PO<SUB>4</SUB>-Activated Biomass for Sequestration of Cu (II) and Cd (II) Ions

Badie S. Girgis,Ahmed A. Elkady,Amina A. Attia,Nady A. Fathy,M. A. Abdel Wahhab 한국탄소학회 2009 Carbon Letters Vol.10 No.2

Crushed, depitted peach stones were impregnated activated with 50% H3PO4 followed by pyrolysis at 500℃. Two activated carbons were produced, one under its own evolved gases during pyrolysis, and the second conducted with air flow throughout the carbonization stage. Physicochemical properties were investigated by several procedures; carbon yield, ash content, elemental chemical analysis, TG/DTG and FTIR spectra. Porosity characteristics were determined by the conventional N2 adsorption at 77 K, and data analyzed to get the major texture parameters of surface area and pore volume. Highly developed activated carbons were obtained, essentially microporous, with slight effect of air on the porous structure. Oxygen was observed to be markedly incorporated in the carbon matrix during the air treatment process. Cation exchange capacity towards Cu (II) and Cd (II) was tested in batch single ion experimental mode, which proved to be slow and a function of carbon dose, time and initial ion concentration. Copper was up taken more favorably than cadmium, under same conditions, and adsorption of both cations was remarkably enhanced as a consequence of the air treatment procedure. Sequestration of the metal ions was explained on basis of the combined effect of the oxygen functional groups and the phosphorous-containing compounds; both contributing to the total surface acidity character.

Impact of Some Environmental Factors on Growth and Production of Ochratoxin A of/by Aspergillus tubingensis, A. niger, and A. carbonarius Isolated from Moroccan Grapes

Atar Selouane,Driss Bouya,Ahmed Lebrihi,C. Decock,Amina Bouseta 한국미생물학회 2009 The journal of microbiology Vol.47 No.4

The effects of temperature, water activity (aw), incubation time, and their combinations on radial growth and ochratoxin A (OTA) production of/by eight Aspergillus niger aggregate strains (six A. tubingensis and two A. niger) and four A. carbonarius isolated from Moroccan grapes were studied. Optimal conditions for the growth of most studied strains were shown to be at 25°C and 0.95 aw. No growth was observed at 10°C regardless of the water activity and isolates. The optimal temperature for OTA production was in the range of 25°C~30°C for A. carbonarius and 30°C~37°C for A. niger aggregate. The optimal aw for toxin production was 0.95~0.99 for A. carbonarius and 0.90~0.95 for A. niger aggregate. Mean OTA concentration produced by all the isolates of A. niger aggregate tested at all sampling times shows that maximum amount of OTA (0.24 µg/g) was produced at 37°C and 0.90 aw. However, for A. carbonarius, mean maximum amounts of OTA (0.22 µg/g) were observed at 25°C and 0.99 aw. Analysis of variance showed that the effects of all single factors (aw, isolate, temperature and incubation time) and their interactions on growth and OTA production were highly significant.

Anogeissus leiocarpus (DC.) Guill and Perr ameliorates pentylenetetrazole-induced seizure/cognitive impairment in rats via inhibition of oxidative stress

Hauwa Adamu Audu,Amina Ahmed,Joseph Vandi Zirahei,Nathan Isaac Dibal,Samaila Musa Chiroma 경희대학교 융합한의과학연구소 2023 Oriental Pharmacy and Experimental Medicine Vol.23 No.4

The study investigates the role of Anogeissus leiocarpus methanol stem bark extract (ALSE) on seizure, oxidative stress and cognitive performance in pentylenetetrazole (PTZ)-induced epilepsy in rat model. Thirty Wistar rats were allocated into five groups (n = 6). Groups 1 and 2 received normal saline intra-peritoneal (i.p) every day and PTZ (i.p) at 35 mg/kg every other day respectively. Groups 3–5 were given ALSE orally at (250 mg/kg and 500 mg/kg) and Diazepam at 4 mg/kg (i.p) respectively. Groups 3–5 were given PTZ (i.p) at 35 mg/kg every other day for 30 days, 30 min after ALSE and Diazepam administration. The rats were observed for seizure activities and also evaluated for cognitive functions. The rats were euthanized thereafter and the brain histology and oxidative stress biomarkers were evaluated. PTZ induction resulted into increased seizure activities leading to the development of kindling, oxidative stress, cognitive impairment and histological aberration of the hippocampus. However, pretreatment with ALSE decreased seizure activities, reversed oxidative stress and cognitive impairment and preserved hippocampal histology relative to the PTZ alone treated rats. Conclusively, ALSE was found to increase seizure latency, prevented cognitive decline, and decreased seizure activities induced by PTZ-kindling in rats. Additionally, ALSE ameliorates PTZ-induced oxidative stress and histological aberrations of the hippocampus. Hence, this study proposed that ALSE might be a promising tool for ameliorating seizure in epilepsy.

Enhancing the Opacity of the Modified Natural Thickening Agent with Different Metal Oxides for Covering Dark Dyed Fabrics

Fedaa Saad,Mohamed M. Mosaad,Hanan A. Othman,Amina L. Mohamed,Ahmed G. Hassabo 한국섬유공학회 2022 Fibers and polymers Vol.23 No.9

Most natural thickeners do not have a full coverage degree when printing on dark dyed fabrics (brown/navy/black). Therefore, some materials are added to improve their coverage. It is common practice that printing is done on dyed orundyed fabrics. The dyed fabrics are of different shades, so the printing process faces a problem, as most of the naturalthickeners do not have full coverage, especially those extracted from aloe vera and flax seeds when printing on fabrics dyedwith dark colors. Therefore, in this study the effect of adding zinc oxide and titanium oxide to the printing paste was studied. The result confirmed that, adding metal salts to printing paste using aloe vera gel or flaxseeds gum as thickener increases thewhiteness index of these pastes as well as the printed fabric. In addition, using light dye in these printing paste provides goodcovering of dark color with good appearance of the new light color used. Furthermore, the mechanical and physicalcharacteristics of printed textiles with various thickeners and metal oxide (14 %) have been evaluated and provide improvingboth tensile strength and elongation at break and had no effect on the angle of crease recovery of printed textiles across allprinting paste formulations.

Synthesis, structural, TD-DFT, and optical characteristics of indole derivatives

Almutlaq N.,Elshanawany Mahmoud M.,Sayed Mostafa,Younis Osama,Ahmed Mostafa,Wachtveitl Josef,Braun Markus,Tolba Mahmoud S.,Al-Hossainy Ahmed F.,Abozeed Amina A. 한국물리학회 2023 Current Applied Physics Vol.45 No.-

New compounds of (E)-1-(3-chloro-1H-indol-2-yl)-N-(4-methoxyphenyl)methanimine [Indol-M] and (E)-1-(4- (((3-chloro-1H-indol-2-yl)methylene)amino)phenyl)ethan-1-one [Indol-A] were synthesized and subsequently converted to thin films via physical vapor deposition technique. Numerous characterization techniques were used including FTIR, nuclear magnetic resonance, X-ray diffraction, scanning electron microscope, and optical spectroscopy. Additionally, the optimization using TD-DFTD/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) was performed. The XRD and FTIR spectra recorded experimentally were confirmed by TD-DFT calculations, proving their molecular structure. As determined by XRD, the crystallite size of [Indol-M]TF and [Indol-A]TF is 72.26 and 62.05 nm, respectively. SEM image depicts a one-dimensional morphological structure made up of tightly packed nanorods. The direct optical energy bandgaps computed using Tauc’s equation for the [Indol-M]TF and [Indol-A]TF are 4.49 eV and 3.31 eV, respectively. As predicted by CASTEP TD-DFT, the optical properties agree well with the experimental values. [Indol-M]TF and [Indol-A]TF present good candidates for optoelectronics and solar cell applications.