A PERTURBATION METHOD FOR A SET OF QUASI-LINEAR OSCILLATORY SYSTEMS WITH VARIABLE NATURAL FREQUENCY

El-Naggar, A.,Ahmed, I. Department of Mathematics 1985 Kyungpook mathematical journal Vol.25 No.2

Antipseudomonal Activity and Nephrotoxicity of Cephradine-Netilmicin Combination

El Emam, M.A.,El Naggar, W.A.,Ibrahiem, T.M. The Pharmaceutical Society of Korea 1989 Archives of Pharmacal Research Vol.12 No.2

The effects of intraperitoneal injection of cephradine in a dose of 75 mg/kg and netilmicin in dose of 50 mg/kg and their combination on creatinine and urea serum levels of rabbits were studied as well as the antipseudomonal activity against three multiresistant clinicial isolates. The antibacterial activity was investigated by two methods: Checkerboard titration method and time-kill studies. Finally, the antibacterial activity of the sera obtained from the rabbits receiving the used drugs in the previous regimen was studied using time-kill study method against Pseudomonas aeruginosa isolates. Results obtained from this study indicated that both creatinine and urea serum levels of the rabbits receiving both drugs were not significantly different from those of the rabbits receiving either cephradine or netilmicin alone. At the same time the in vitro antibactrial activity (either of the prepared solutions of the used drugs and their combination or of the sera obtained from the rabbits receiving these drugs as mentioned before) showed a synergistic effect against the tested strains of Pseudomonas aeruginosa

Vertical and torsional soil reactions for radially inhomogeneous soil layer

El Naggar, M. Hesham Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.10 No.4

The response of an embedded body to dynamic loads is greatly influenced by the reactions of the soil to the motion of the body. The properties of the soil surrounding embedded bodies (e.g., piles) may be different than those of the far-field for a variety of reasons. It may be weakened or strengthened according to the method of installation of piles, or altered due to applying one of the soil strengthening technique (e.g., electrokinetic treatment of soil, El Naggar et al. 1998). In all these cases, the shear strength of the soils and its shear modulus vary gradually in the radial direction, resulting in a radially inhomogeneous soil layer. This paper describes an analysis to compute vertical and torsional dynamic soil reactions of a radially inhomogeneous soil layer with a circular hole. These soil reactions could then be used to model the soil resistance in the analysis of the pile vibration under dynamic loads. The soil layer is considered to have a piecewise, radial variation for the complex shear modulus. The model is developed for soil layers improved using the electrokinetic technique but can be used for other situations where the soil properties vary gradually in the radial direction (strengthened or weakened). The soil reactions (impedance functions) are evaluated over a wide range of parameters and compared with those obtained from other solutions. A parametric study was performed to examine the effect of different soil improvement parameters on vertical and torsional impedance functions of the soil. The effect of the increase in the shear modulus and the width of the improved zone is investigated.

Effect of Salicylate on Antibacterial Activity of Different Antibiotics

El-Naggar, Wael A. The Pharmaceutical Society of Korea 1992 Archives of Pharmacal Research Vol.15 No.1

Susceptibility of Psudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis to gentimicin and ceforaxime was affected by salicylaye. In presence of salicylaye (15 mM) and gentamicin (1.0 .mu.g/ml), log efficiency of plating (log E. O. P. s) for the tested bacteria were -1.24, -2.17 and -1.66 respectively. The activity of cefotaxime against Bacillus subtilis was reduced (log E. O. P. = 1.33). The highest potentiating effects of salicylaye were shown when using gentamicin against Staphylococcus aureus, cefotaxime against Ps. aeruginosa, log E. O. P.s were -3.0, and -2.4 respectively. On the other hand, no significant effects were detected with cefotaxime against Staphylococcus aureus (log E. O. P. = -0.04). No significant killing was shown in presence of gentamicin or salicylaye alone. There was no significant effect for salicylaye on MICs (By broth dilution) could be observed except in case of gentamicin against Staphyloccus aureus, which was reduced from 0.02 .mu.g/ml to 0.0012 .mu.g/ml. These results raise the concern that high concentrations of salicylaye in patients might interfere with antibiotic therapies.

Biochar composition-dependent impacts on soil nutrient release, carbon mineralization, and potential environmental risk: A review

El-Naggar, Ali,El-Naggar, Ahmed Hamdy,Shaheen, Sabry M.,Sarkar, Binoy,Chang, Scott X.,Tsang, Daniel C.W.,Rinklebe, Jö,rg,Ok, Yong Sik Academic Press 2019 Journal of Environmental Management Vol. No.

<P><B>Abstract</B></P> <P>Biochar application has multiple benefits for soil fertility improvement and climate change mitigation. Biochar can act as a source of nutrients and sequester carbon (C) in the soil. The nutrient release capacity of biochar once applied to the soil varies with the composition of the biochar, which is a function of the feedstock type and pyrolysis condition used for biochar production. Biochar has a crucial influence on soil C mineralization, including its positive or negative priming of microorganisms involved in soil C cycling. However, in various cases, biochar application to the soil may cause negative effects in the soil and the wider environment. For instance, biochar may suppress soil nutrient availability and crop productivity due to the reduction in plant nutrient uptake or reduction in soil C mineralization. Biochar application may also negatively affect environmental quality and human health because of harmful compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins, and dibenzofurans (PCDD/DF). In this review, we discuss the linkage between biochar composition and function, evaluate the role biochar plays in soil fertility improvement and C sequestration, and discuss regulations and concerns regarding biochar's negative environmental impact. We also summarize advancements in biochar production technologies and discuss future challenges and priorities in biochar research.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nutrient contents in biochar highly dependent on the feedstock type. </LI> <LI> Pyrolysis temperature alters the proportion of aromatic and aliphatic C fractions. </LI> <LI> Chemical and physical properties of biochar affect the nutrient release from biochar. </LI> <LI> Application of unsuitable biochar can negatively affect environmental quality and human health. </LI> <LI> Biochar can be a potential source of polycyclic aromatic hydrocarbons and polychlorinated dibenzodioxins. </LI> </UL> </P>

Release dynamics of As, Co, and Mo in a biochar treated soil under pre-definite redox conditions

El-Naggar, Ali,Shaheen, Sabry M.,Hseu, Zeng-Yei,Wang, Shan-Li,Ok, Yong Sik,Rinklebe, Jö,rg Elsevier 2019 The Science of the total environment Vol.657 No.-

<P><B>Abstract</B></P> <P>This study assessed the impact of pre-definite redox potential (E<SUB>H</SUB>) on the release dynamics and distribution of As, Co, and Mo between the dissolved and colloidal phases as well as their potential mobility and phytoavailability in the sediment phase of a mining soil treated with rice hull biochar (BC). The experiment was conducted from controlled moderately-reducing to oxidizing conditions using an automated biogeochemical microcosm system. Arsenic and Mo were more abundant in the dissolved phase due to their predominant in potential mobile fractions, while Co was more abundant in the colloidal phase due to its association with Fe-(hydr)oxides. Biochar increased the dissolved and colloidal concentrations of As, the dissolved concentration of Co, and the colloidal concentration of Mo under oxidizing condition. On the other hand, the application of BC decreased the dissolved concentration of Mo and the colloidal concentration of Co in the first redox cycle under reducing-acidic condition, due to lower pH values, and chemistry of sulfide-sulfate and Fe/Mn oxides. The phytoavailability of As and Co were higher than their potential mobility in the sediment phase, while the same trend was not discerned for Mo. The potential mobility and phytoavailability of As and Co were high under oxic-acidic conditions. The potential mobility and phytoavailability of Mo might be increased under oxic condition due to the dissolution of Fe and Mn oxides under lower pH conditions, especially in the BC treated soil. Application of such rice hull BC to soil might stimulate the release of As, Co, and Mo under flooding conditions, which might increase the environmental and health risks in such wetland ecosystems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The E<SUB>H</SUB> showed a converse relation with pH in biochar treated and non-treated soils. </LI> <LI> Arsenic and Mo were abundant in the dissolved phase, but Co in the colloidal phase. </LI> <LI> Biochar increased the dissolved As and Co under oxidizing conditions. </LI> <LI> Biochar decreased the dissolved Mo under acidic conditions in the first redox cycle. </LI> <LI> Potential mobility and phytoavailability were higher under low pH and high E<SUB>H</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Influence of soil properties and feedstocks on biochar potential for carbon mineralization and improvement of infertile soils

El-Naggar, Ali,Lee, Sang Soo,Awad, Yasser Mahmoud,Yang, Xiao,Ryu, Changkook,Rizwan, Muhammad,Rinklebe, Jö,rg,Tsang, Daniel C.W.,Ok, Yong Sik Elsevier 2018 Geoderma Vol.332 No.-

<P><B>Abstract</B></P> <P>The impact of biochar (BC) application on soil varies with BC feedstock and soil type. The objective of this study was to investigate the linkage between the properties and surface functionality of various BCs and their role in the rehabilitation of two infertile soils. Sandy loam (SL) and sandy (S) soils were collected from agricultural areas in Korea and Vietnam, respectively. The BCs of amur silvergrass residue (AB), paddy straw (PB), and umbrella tree (UB) were applied to the soils at a rate of 30 t ha<SUP>−1</SUP> and incubated at 25 °C for 90 d. Soil carbon (C) mineralization was investigated by a periodic measurement of CO<SUB>2</SUB> efflux. Soil texture strongly influenced the CO<SUB>2</SUB> efflux more than the BC type as indicated by 2–4 folds increase in cumulative CO<SUB>2</SUB>-C efflux from the SL soil compared to that from the S soil. For the PB-, AB-, and UB-treated S soils, the values of cation exchange capacity (CEC) were increased by 906%, 180%, and 130%, respectively, compared to that of the control; however, for the PB-treated SL soil, only a 13% increase in CEC was found. The pH in the PB-treated S soil sharply increased by 4.5 units compared to that in the control, due to a high concentration of readily soluble compounds in the PB and the low buffering capacity of the S soil. The S soil was more sensitive to the addition of BCs than the SL soil. A more prominent improvement in soil fertility can be achieved by BC application to the sandy soil having low clay, nutrient, and organic matter contents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The influence of biochar varied strongly according to the types of feedstock/soil. </LI> <LI> The paddy straw biochar caused an abrupt increase in pH in the sandy soil. </LI> <LI> The CO<SUB>2</SUB> efflux rates depend more on soil texture than type of biochar. </LI> <LI> The sandy soil was more sensitive to the addition of biochar than the sandy loam soil. </LI> <LI> Biochar significantly improved the physicochemical properties of the sandy soil. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Multi-Objective Optimal Predictive Energy Management Control of Grid-Connected Residential Wind-PV-FC-Battery Powered Charging Station for Plug-in Electric Vehicle

El-naggar, Mohammed Fathy,Elgammal, Adel Abdelaziz Abdelghany The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

Electric vehicles (EV) are emerging as the future transportation vehicle reflecting their potential safe environmental advantages. Vehicle to Grid (V2G) system describes the hybrid system in which the EV can communicate with the utility grid and the energy flows with insignificant effect between the utility grid and the EV. The paper presents an optimal power control and energy management strategy for Plug-In Electric Vehicle (PEV) charging stations using Wind-PV-FC-Battery renewable energy sources. The energy management optimization is structured and solved using Multi-Objective Particle Swarm Optimization (MOPSO) to determine and distribute at each time step the charging power among all accessible vehicles. The Model-Based Predictive (MPC) control strategy is used to plan PEV charging energy to increase the utilization of the wind, the FC and solar energy, decrease power taken from the power grid, and fulfil the charging power requirement of all vehicles. Desired features for EV battery chargers such as the near unity power factor with negligible harmonics for the ac source, well-regulated charging current for the battery, maximum output power, high efficiency, and high reliability are fully confirmed by the proposed solution.

Meroparamycin Production by Newly Isolated Streptomyces sp. Strain MAR01: Taxonomy, Fermentation, Purification and Structural Elucidation

El-Naggar Moustafa Y.,El-Assar Samy A.,Abdul-Gawad Sahar M. The Microbiological Society of Korea 2006 The journal of microbiology Vol.44 No.4

Twelve actinomycete strains were isolated from Egyptian soil. The isolated actinomycete strains were then screened with regard to their potential to generate antibiotics. The most potent of the producer strains was selected and identified. The cultural and physiological characteristics of the strain identified. the strain as a member of the genus Streptomyces. The nucleotide sequence of the 16S rRNA gene (1.5kb) of the most potent strain evidenced a 99% similarity with Streptomyces spp. and S. aureofaciens 16S rRNA genes, and the isolated strain was ultimately identified as Streptomyces sp. MAR01. The extraction of the fermentation broth of this strain resulted in the isolation of one major compound, which was active in vitro against gram-positive, gram-negative representatives and Candida albicans. The chemical structure of this bioactive compound was elucidated based on the spectroscopic data obtained from the application of MS, IR, UV, $^1H$ NMR, $^{13}C$ NMR, and elemental analysis techniques. Via comparison to the reference data in the relevant literature and in the database search, this antibiotic, which had a molecular formula of $C_{19}H_{29}NO_2$ and a molecular weight of 303.44, was determined to differ from those produced by this genus as well as the available known antibiotics. Therefore, this antibiotic was designated Meroparamycin.

Solid-State Fermentation for the Production of Meroparamycin by Streptomyces sp. strain MAR01

El Naggar,Moustafa Y.,Samy A. El Assar,Sahar M. Abdul Gawad 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.5