Ahmed Fekri

Novel superabsorbent membranes made of PVA and Ziziphus spina-christi cellulose for agricultural and horticultural applications

Novel superabsorbent membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs) from Ziziphus spina-christi fibers (ZSP-fibers), glutaraldehyde (GLA) and glycerin (G) were prepared using a Hydraulic Lamination Hot Press machine. Crosslinking of PVA was used to improve the agricultural and horticultural applications. The plasticizer was used to increase the plasticity of the superabsorbent membranes. Ziziphus spina-christi fibers are a new source from which to isolate pure cellulose via mechanical and chemical treatment. These membranes were characterized using FTIR, XRD, SEM, TS and DSC. The superabsorbent membranes showed a greater equilibrium swelling capacity compared with the neat hydrogel. Moreover, the water transport mechanism of all the superabsorbent membranes was Fickian diffusion type. The influence of various factors, such as loading values (1, 3, 5, 7 or 10 wt% from CNCs), time, solution pH, saline solutions and the reswelling capability, on the swelling behavior of the superabsorbent membranes was also investigated. The superabsorbent membranes exhibited a good pH-dependent swelling reversibility and a high water retention capability, making them a more efficient water-saving material. The biodegradability of the superabsorbent membranes was evaluated under environmental changes. The superabsorbent membranes were also investigated for any antimicrobial activities against pathogenic bacteria like Candida albicans (fungus), Bacillus subtilis (G +ve), Staphylococcus aureus (G +ve), Proteus vulgaris (G −ve) and Erwinia carotovora (G −ve). The results showed that the design of innovative bioactive superabsorbent membranes is promising for agricultural and horticultural applications.

Chemical and biology aging of novel green membranes made of PVA and wood flour fibers reinforced with nanosilica manufactured by compression molding process

ABSTRACT The purpose of this work was to improve the biodegradable properties of polyvinyl alcohol (PVA)/nanowood flour membranes consisting of nanosilica which were manufactured by compression molding process. Cross-linking of PVA was used to improve the mechanical properties and prevent high solubility of the obtained transient membranes. Plasticizer used to increase the plasticity of transient membranes. The biodegradability of transient membranes was evaluated under UV accelerated weathering as well as soil burial test. The transient membranes were characterized by Fourier transform infrared spectra and X-ray diffraction to study the chemical structure. Mechanical strength was appointed to characterize and reveal the mechanical, thermal analysis and the structural properties of such transient membranes. Scanning electron microscope was used to characterize the morphology of transient membranes. Swelling test and weight loss due to biodegradation were also evaluated. The results showed that the developed transient membranes can be used as food packaging bags due to biodegradability (weight loss) under irradiation and during burial soil which making them environmentally friendly.

Utility involving thioacetoacetanilides as precursors for synthesis of new thiazole, thiadiazole and thiophene derivatives with antimicrobial activity

ABSTRACT The behavior of thioacetoacetanilide (1) and/or α-arylhydrazono-thioacetoacetanilides 4 toward many different α-halocarbonyl compounds was demonstrated. Thus, reactions of 1 with α-bromoketones (bromoacetone and phenacyl bromide) and hydrazonoyl bromides afforded the corresponding thiazole, thiophene and 1,3,4-thiadiazole derivatives, respectively. The synthesis and reactivity of thiazolidin-5-one 2 toward aromatic diazonium chlorides and aromatic aldehydes were described. Most of the synthesized compounds were screened for their antibacterial and antifungal activities and showed accepted antimicrobial activities with respect to the control drugs. GRAPHICAL ABSTRACT

Characterization and swelling–deswelling properties of porous superabsorbent hydrogel membranes made of PVA and Ziziphus spina-christi fibers reinforced with nanosilica manufactured by compression moulding process

Novel superabsorbent membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals originated from Ziziphus spina-christi fibers, nanosilica, glutaraldehyde, and glycerin (G) were manufactured by compression moulding process. Ziziphus spina-christi fibers are a new source to isolate pure cellulose nanocrystals via mechanical and chemical treatment. Ziziphus spina-christi fibers were used to improve water-saving irrigation systems. Glycerin was used to increase the elasticity of superabsorbent membranes. These membranes were characterized by FTIR, XRD, SEM, mechanical testing, and thermal analysis. Superabsorbent membranes showed greater equilibrium swelling capacity compared with neat cross-linked PVA. Moreover, water transport mechanism of all superabsorbent membranes followed Fickian diffusion type. Superabsorbent membranes exhibited good pH-dependent swelling reversibility and high-water retention capacity, making it more efficient water-saving material. The superabsorbent membranes were also investigated for antimicrobial activities against pathogenic bacteria like Candida albicans (fungus), Bacillus subtilis (G+ve), Staphylococcus aureus (G+ve), Proteus vulgaris (G−ve), and Erwinia carotovora (G−ve). The results showed that design of innovative bioactive superabsorbent membranes is promising for the water reservoir, which might be most profitable in agricultural applications.

Aging of novel membranes made of PVA and cellulose nanocrystals extracted from Egyptian rice husk manufactured by compression moulding process

Abstract Novel membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs) originated from Rice Husk (RH), Glutaraldehyde (GLA) and Glycerine (G) were manufactured by the compression moulding process. Rice husk is a new source to isolate pure cellulose nanocrystals via mechanical and chemical treatment. The biodegradability of the membranes has been evaluated using UV accelerated weathering as well as a soil burial test. The morphology of membranes (PVA/RH-CNCs) was characterized by using the Scanning Electron Microscope (SEM). The chemical structure of the membranes (PVA/RH-CNCs) was characterised by Fourier-Transformation Infrared (FTIR) spectroscopy as well as wide-angle X-ray diffraction. The mechanical properties of the membranes were evaluated using standard techniques. Swelling and weight loss resulting from biodegradation were also evaluated. The results showed that the developed transient membranes can be used as food packaging bags owing to biodegradability (weight loss) under irradiation and during soil burial.

Bivalent transition metal complexes of 3-(2-(4-(dimethylamino)benzylidene)hydrazinyl)-3-oxo-N-(thiazol-2-yl)propanamide: Structural, spectral, DFT, ion-flotation and biological studies

Abstract Co(II), Pb(II), Hg(II) and Cd(II) complexes of the 3-(2-(4-(dimethylamino)benzylidene)hydrazinyl)-3-oxo-N-(thiazol-2-yl)propanamide (H2L) were synthesized. The prepared compounds were interpreted by elemental analysis: C, H, N, M, Cl; physical measurements as molar conductance; and magnetic susceptibility spectroscopic techniques as IR, UV–visible, 1H NMR, MS spectra. The computational studying was estimated to approve the geometry of the isolated solid compounds. Also, Pb(II) and Cd(II) were separated using a simple, rapid and inexpensive quantitative flotation method prior to their determinations using atomic absorption spectrophotometric (AAS). The main parameters influencing the flotation process were examined (ca. initial pH, metal ion, surfactant and ligand concentrations, presence of foreign ions, and temperature). Furthermore, the biological activity (antimicrobial, anti-oxidant and cytotoxic) of the investigated compounds was tested.

Aging of membranes prepared from PVA and cellulose nanocrystals by use of thermal compression

Abstract Novel membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals (CNCs), nanosilica (NS), glutaraldehyde (GLA) and glycerine (G) were prepared using a compression moulding process. Rice husk is selected to isolate pure cellulose nanocrystals via mechanical and chemical treatment. The biodegradability of the membranes has been evaluated using UV accelerated weathering as well as a soil burial test. The chemical structure of the membranes were characterised by Fourier-Transformation Infrared (FTIR) spectroscopy. The microstructure of the membranes was characterised by using Scanning Electron Microscope (SEM). The mechanical properties of the membranes were evaluated using standard techniques. The swelling and weight loss resulting from biodegradation were also evaluated. The results showed that the developed membranes can be used as food packaging bags owing to biodegradability (weight loss) under irradiation and during soil burial. The membranes are environmentally friendly.

Eco-friendly synthesis, characterization, and drug-likeness properties of new uracils and their biological evaluation

Abstract Several pyridopyrimidine derivatives have been synthesized through different synthetic processes. The different physicochemical factors for their synthesis were also discussed. A comparison between the conventional and microwave-assisted synthesis was conducted by comparing total time of reaction and its yield percentage. Most of the produced uracils were established for their anti-inflammatory, analgesic, and antioxidant activities. Compounds 1 and 3 were demonstrated as the best results against DNA damage, whereas compounds 2a and 2b exhibited an effective anti-inflammatory activity. Moreover, the Lipinski rule parameters were calculated for the synthesized compounds. The results indicated that compounds 1, 2a and 5 have good potential for subsequent development bioactivity.

Sulfones in heterocyclic synthesis: advances in the chemistry of phenyl sulfonylacetophenone

The present review provides a survey on the structural features, synthetic methodologies, and reactions of phenyl sulfonylacetophenone, considered to be one of the most important synthons in the field of synthetic organic chemistry. β-Ketosulfone is an active C–H acid which has been widely used as a nucleophile in many organic transformations. It has been used for synthesis of five- and six-membered ring systems containing one or two heteroatoms. In addition, it has been used as a starting material for synthesis of fused heterocycles, cyclopropane, cyclopentene, and cyclohexanone derivatives. β-Ketosulfone has been used for synthesis of γ- and δ-ketosulfones, 1,4-diketones, amides, ethers, and substituted benzene derivatives due to its high synthetic importance. It is a reactive intermediate in electrophilic reactions such as halogenation, alkylation, arylation, heteroarylation, and coupling reactions, and is involved in other types of reaction such as Diels–Alder condensation with aldehydes and desulfonylation. The mechanistic pathways of these reactions and their important synthetic applications are discussed herein.

Square wave voltammetric investigations on 2,2-Dimethyl-1,3-dioxan-5-phenylazo-4,6-dione

Abstract The mostly advanced polarographic mode of measurement, square wave (SW), was applied for studying reduction of for 2,2-Dimethyl-1,3-dioxan-4,6-dione (Meldrum acid) and its 5-phenyl-azo substituent in 40% v/v ethanolic universal buffer (pH~ 2–12). At more negative potentials, a 2e pH-dependent wave (dEp/dpH = 31 mv) was assigned to one carbonyl group, while at more positive potentials a 4e pH-dependent wave (dEp/dpH = 71 mv) was assigned to the azomethine group. Based on the polarographic data and acid-base pKa values were determined spectrophotometrically. The reduction mechanism pathway was suggested. The azomethine group proved to be in the azo form since the nitro group of the p-NO2 derivative is reduced at a more negative potential than the azomethine linkage. Fair Ep-σ correlation was obtained with positive p values (~0.2–0.3), indicating that the substituents facilitate the reduction process at the dropping electrode.