501 research outputs found
Stability of a monotonic solution of a non-autonomous multidimensional delay differential equation of arbitrary (fractional) order
We are concerned here with the existence of monotonic and uniformly asymptotically stable solution of an initial-value problem of non-autonomous delay differential equations of arbitrary (fractional) orders
A Critical Role of Fuel Molar Ratio in the Microwave Combustion Synthesis of Nano Size α-Al2O3
Nano size highly crystalline α-Al2O3 powders have been synthesized by the microwave combustion approach. A study of the evolution of crystalline phase of obtained powders and the morphology of the particles were accomplished through X-ray diffraction and High resolution transmission electronic microscopy. The effect of metal to fuel molar ratios on the crystal structure, particle size, and morphology of the powders was examined. Microwave combustion gave finer particles with very small agglomerate size as revealed by TEM analysis. Also the results obtained allow the identification of the highly crystalline single-phase αAl2O3 powder was obtained after microwave combustion at 900 w for 5 min with metal/fuel molar ratio as 1:3. Keywords: Microwave Combustion, Mixed Oxide, Synthesis, Characterization.
Removal of Heavy Metals via Adsorption using Natural Clay Material
Removal of heavy metals from its solution has been investigated by using adsorption clay material from El-Hammam district (Alexandria), with high silica content ~ 53 wt % was selected to verify this purpose. The clay material has been characterized by applying different techniques; x-ray analyses to investigate the crystalline structure (x-ray diffraction), the constitutes of the clay material (x-ray florescence) and thermal analysis to trace the structure changes that accompanying the thermal treatment.FeCl2, Ni(NO3)2.6H2O, and ZnCl2 solutions have been used as metal model compounds to evaluate the adsorption efficiency of the clay material. Results indicated that the adsorption of heavy metals from its single metal solutions followed the order Fe> Zn > Ni. Key words: Adsorption, Adsorbent, Bentonite, Montmorillonite, Heavy metal
Characterizations of Mappings Via Z-Open Sets
The aim of this paper we introduce Z-irresolute, Z-open, Z-closed, pre-Z-open and pre-Z-closed mappings and investigate properties and characterizations of these new types of mappings
Generalized ψ
The aim of this work is to introduce ψ-operations on fuzzy topological spaces and to use them to study fuzzy generalized ψρ-closed sets and fuzzy generalized ψρ-open sets. Also, we introduce some characterizations and properties for these concepts. Finally we show that certain results of several publications
on the concepts of weakness and strength of fuzzy generalized closed sets are considered as corollaries of the results of this research
Adsorptive Power Evaluation of the Nano-Crystalline Mo-W Bimetallic Oxides
Novel nanosized molybdenum-tungsten bimetallic oxides were prepared by modified Pechini method based on the low temperature polymerization-complexation steps. The physical properties of the prepared nanoparticles were characterized by: X-ray diffraction (XRD), Fourier transformer inferred spectroscopy (FT-IR), differential thermal analyses (DCS), and high resolution transmission electron microscopy (HRTEM). The influence of metal molar ratios (Mo/W) on the morphology and the crystallization the samples was also investigated. The adsorptive power of prepared samples was evaluated through the removal of dimethyl disulfide sulfur compound (in cyclohexane as fuel). The results indicate that all the prepared Mo-W oxide materials are nanoparticles with diameter ranging between 1 and 70 nm. And the smallest nanosize particles enhanced the adsorptive power of the prepared nanostructured Mo-W bimetallic oxide. Keywords : Mixed Oxide, Synthesis, Characterization, Sulfur Adsorption
A Direct Substrate-Substrate Interaction Found in the Kinase Domain of the Bifunctional Enzyme, 6-Phosphofructo-2-kinase/Fructose-2,6-bisphosphatase
To understand the molecular basis of a phosphoryl transfer reaction catalyzed by the 6-phosphofructo-2-kinase domain of the hypoxia-inducible bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3), the crystal structures of PFKFB3{radical dot}AMPPCP{radical dot}fructose-6-phosphate and PFKFB3{radical dot}ADP{radical dot}phosphoenolpyruvate complexes were determined to 2.7 Å and 2.25 Å resolution, respectively. Kinetic studies on the wild-type and site-directed mutant proteins were carried out to confirm the structural observations. The experimentally varied liganding states in the active pocket cause no significant conformational changes. In the pseudo-substrate complex, a strong direct interaction between AMPPCP and fructose-6-phosphate (Fru-6-P) is found. By virtue of this direct substrate-substrate interaction, Fru-6-P is aligned with AMPPCP in an orientation and proximity most suitable for a direct transfer of the γ-phosphate moiety to 2-OH of Fru-6-P. The three key atoms involved in the phosphoryl transfer, the β,γ-phosphate bridge oxygen atom, the γ-phosphorus atom, and the 2-OH group are positioned in a single line, suggesting a direct phosphoryl transfer without formation of a phosphoenzyme intermediate. In addition, the distance between 2-OH and γ-phosphorus allows the γ-phosphate oxygen atoms to serve as a general base catalyst to induce an associative phosphoryl transfer mechanism. The site-directed mutant study and inhibition kinetics suggest that this reaction will be catalyzed most efficiently by the protein when the substrates bind to the active pocket in an ordered manner in which ATP binds first. © 2007 Elsevier Ltd. All rights reserved
On Z- generalized closed sets in topology
In this paper, we introduce and study the notion of generalized Z-closed sets. Also, the notion of generalized Z-open sets and some of its basic properties are introduced discussed. Further, we introduce the notion of generalized Z-closed functions. Moreover, some characterizations and properties of it are investigated. Keywords: gZ-closed sets, Z-T1/2-spaces, gZ-continuous and ZgZ-continuous functions
An Efficient Firefly Algorithm for Optimizing Task Scheduling in Cloud Computing Systems
As user service demands change constantly, task scheduling becomes an extremely significant study area within the cloud environment. The goal of scheduling is distributing the tasks on available processors in order to achieve the shortest possible makespan while adhering to priority constraints. In heterogeneous cloud computing resources, task scheduling has a large influence on system performances. The various processes in the heuristic-based algorithm of scheduling will result in varied makespans when heterogeneous resources are utilized. As a result, a smart method of scheduling must be capable of establishing precedence efficacy for each task to decrease makespan time. In our study, we develop a novel efficient method of scheduling tasks according to the firefly algorithm to tackle an essential task and schedule a heterogeneous cloud computing problem. We evaluate the performance of our algorithm by putting it through three situations with changing amounts of processors and numbers of tasks. The findings of the experiment reveal that our suggested technique found optimal solutions substantially more frequently in terms of makespan time when compared with other methods
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