OALib Journal期刊

ISSN: 2333-9721




9 ( 1 )

2020 ( 55 )

2019 ( 234 )

2018 ( 209 )


匹配條件: “Mohamed Assaad Abdel-Raouf” ,找到相關結果約11284條。
On Possible Formation of Matter-Antimatter Exotic Molecular Structures  [PDF]
Mohamed Assaad Abdel-Raouf
Open Access Library Journal (OALib Journal) , 2020, DOI: 10.4236/oalib.1106064
Abstract: Possible formation of exotic matter-antimatter molecular structure is considered as one of the most challenging problems at International Laboratories of Particle Physics. In the present work, elaborate computer codes built for investigating four-body systems are employed for calculating the binding energies of exotic molecules composed of electrons, protons, muons, pions and their antiparticles. The results confirm the stability of these molecules against dissociation to their lowest possible channels. Based on these results, it is argued that possible creation of two universes immediately after the Big Bang should be considered. Particularly, it is proposed that an overlapping area might exist between the universe and antiuniverse in which continuous creation and annihilation of simple and complicated particle-antiparticle structures might occur. Antiparticles escaping from this area are considered as the origin of the minimal traces of antiparticles appearing in our universe. Recent interpretations of cosmic-rays and gamma-radiations observed at the edge of our universe could be thought of as evidences for supporting this argument. Furthermore, it is argued that possible formation of matter-antimatter molecular structures could open the gate in front of a new field of chemistry to be referred to as Antimatter Chemistry.
Ab initio Calculations of the Interface States of Polyacetylene-Polyvinylfluoride and Polyethylene - Polyvinylfluoride Quasi-one-dimensional Chains
Mohamed Assad Abdel-Raouf
Physics , 2007,
Abstract: The interface states appearing in polyacetylene-polyvinylfluoride and polyethylene-polyvinylfluoride are determined via an ab initio self consistent field technique based on Green matrix formalism. Different properties of these states are explored. Contrary to the results of the second pair, the results of the first pair showed that the active electronic structure of polyacetylene leads to new states lying in the energy gap of polyvinylfluoride which enhances the doping probability in the first pair. The results emphasize the appearance of bending band phenomenon as a result of the interface of systems considered.
Possible Coexistence of Antihydrogen with Hydrogen, Deuterium and Tritium Atoms
Mohamed Assad Abdel-Raouf
Physics , 2007,
Abstract: Recent productions of large numbers of cold antiprotons as well as the formation of antihydrogens at CERN and Fermilab have raised basic questions about possible coexistence of matter and antimatter in nature. In the present work, previous mathematical considerations are revisited which support the possible coexistence of Antihydrogen with Hydrogen, Deuterium and Tritium atoms. In particular, the main objective of the present work is to present computational treatments which confirm the possible formation of these quasi molecules in laboratory. These treatments are based on a nonadiabatic picture of the system in which generalized basis functions are adjusted within the framework of Rayleigh-Ritz' variational method. Thus, it is ruled out in the present work the Born-Oppenheimer adiabatic picture of the system, which demands the existence of bound states composed of fixed quasi heavy atoms (containing at least two baryons, e.g. protonium (Pn), with mean lifetime 1.0x10^^-6 s) and quasi light atoms (composed of two leptons, e.g. positronium (Ps), with mean lifetime 125x10^^-12 s for para-Ps and 142.05x10^^-9 s for ortho-Ps). Our calculations of the binding energies and internal structure of Antihydrogen-Hydrogen, Antihydrogen-Deuterium and Antihydrogen-Tritium show that these quasi molecules are bound and could be formed in nature. On the other hand, having in mind the adiabatic picture of the systems, our results suggest the possible formation of these molecules as resonant states in Antihydrogen-Atom interaction. Nevertheless, several arguments are accumulated in the conclusion as consequences of the proposed bound states.
Existence of Unexcited and Excited Biexcitons in Molecular Crystals
Mohamed Assad Abdel-Raouf
Physics , 2007,
Abstract: The theory of four-body systems is revisited. It is illustrated that the theory provides a rigorous proof for the formation of ground state (unexcited) biexcitons in molecular crystals. The generalization of the theory predicts the possible existence of excited biexcitons in nature. In order to test the validity of the extended theory on computational level, a very elaborate computer code is constructed for the treatment of arbitrary four-body system with arbitrary electron/hole mass ratio and arbitrary exciton - exciton interaction (VXX). The results, for mass ratio = 1 and VXX is a pure Coulomb force, show that the test is successful. Realization of these conclusions on experimental level should open the door for wide industrial applications.
Wavefunctions of Auger Electrons Emitted from Copper Atoms: A Computational Study
Mohamed Assad Abdel-Raouf
Physics , 2007,
Abstract: An elaborate least-squares variational technique is proposed for obtaining improved continuum wavefunctions of Auger electrons emitted from arbitrary systems the electronic structures of which are determined via one of the computer codes available. A computer program is developed on the basis of this technique for calculating the Auger transition rates using the angular momentum average scheme. The program is employed for investigating the emission of Auger electrons as a consequence of K- shell ionizations of two configurations of copper atoms. A comparison is presented between the improved Auger transitions and the ones determined using conventional Hartree-Fock codes. The results emphasize the argument that (3p to 3d3d) is the dominant transition in both configurations of the copper atoms. There is a minimal change in the values of the Auger transition rates obtained from these configurations. It is anticipated that the improved continuum wavefunctions provide closer results to the experimental ones.
Emission of K -, L - and M - Auger Electrons from Cu Atoms
Mohamed Assad Abdel-Raouf
Physics , 2007,
Abstract: The emission of Auger electrons from the K-, L- and M-sheels of two configurations of copper atoms is investigated in detail within the frame work of the momentum average technique. Ab initio calculations for the bound state wavefunctions of the ionized atoms are performed using a Gaussian computer code. The continuum wavefunctions of the emitted electrons are determined by employing an effective potential variational approach. Slight differences have been noticed between the results of both configurations. The transition rates, energies and widths of all possible Auger electrons are listed in Tables. Slight differences have been noticed between the results of the two types of copper atoms.
Bile reflux measurement and its contribution to the severity of reflux esophagitis
GadEl-Hak Nabil,El-Hemaly Mohamed,Hamdy Emad,AbdEl-Raouf Ahmed
Saudi Journal of Gastroenterology , 2007,
Abstract: Background/Aims: Gastroesophageal reflux disease (GERD) may occur with acid, bile or in a mixed form. Endoscopic injury and mucosal metaplasia are a known sequelae to pathological GERD. The aim of the study was to determine the contribution of acid and duodenogastroesophageal reflux to endoscopic severity in patients with GERD and Barrett′s esophagus (BE). Materials and Methods: Ninety-one patients complaining of reflux symptoms were studied with upper gastrointestinal endoscopy and graded to nonerosive reflux disease (NERD), erosive reflux disease (ERD) and BE. Esophageal manometry and simultaneous ambulatory 24-h esophageal pH and bilirubin monitoring (Bilitec 2000) were performed in all patients. Results: Seventy-one patients (78.0%) had ERD (Savary-Miller (grade I-III), 11 patients (12.1%) had NERD and 9 patients (9.9%) had BE, which were suspected endoscopically and diagnosed by histological esophageal biopsy. Combined 24-h esophageal bilirubin and pH monitoring revealed the following: 39 patients (42.9%) had mixed acid and bile reflux, 16 (17.6%) had pathological acid reflux alone, 18 (19.8%) had bile reflux alone and 18 patients (19.8%) showed no evidences of abnormal reflux. The percentage of the total time of the bilirubin absorbance > 0.14 in 71 patients with ERD was (8.18±11.28%) and in 9 patients with BE was (15.48±30.48%), which was significantly greater than that in 11 patients with NERD (4.48±8.99%), P< 0.05 and P=0.01 respectively. All the BE patients had abnormal esophageal bile reflux (bile alone (3 patients)); and mixed bile and acid (6 patients)); 44 of 71 patients (61.97%) with ERD had abnormal esophageal bile reflux (alone (13 patients) and mixed bile and acid (31 patients)); meanwhile, 15 of them (21.2%) had abnormal acid exposure alone. Despite 11 patients having NERD, four patients (36.4%) had abnormal esophageal bile reflux and two of them had mixed reflux of bile with acid. Conclusion: We believe that the Bilitec method reliably identifies the presence of bilirubin and quantitatively detects the duodenogastroesophageal reflux of bile. Mixed reflux (acid and bile) is the chief pattern of reflux in our GERD patients. Bile reflux either alone or along with acid reflux contributes to the severity of erosive and nonerosive reflux diseases as well as in BE.
Phytofungitoxic Properties in the Aqueous Extracts of Some Plants
Abdel-Raouf M. Khallil
Pakistan Journal of Biological Sciences , 2001,
Abstract: The effects of aqueous extracts of twenty plants on spore germination and vegetative growth of two pathogenic, terrestrial (Alternaria solani) and zoosporic (Saprolegnia parasitica) fungal species was examined. The extract of Eugenia aromatica completely inhibited the spore germination of A.solani and exerted a highly significant depressive effect on the mycelial growth of the two tested species. Also, the extracts of Allium cepa (cloves),Eucalyptus rostrata (leaves) and Capsicum frutescens (fruits) exhibited remarkable inhibitory effects against these two fungi. Some of the tested plant extracts showed a promotive effect either on spore germination or mycelial dry weight. Zoosporic fungus was relatively more sensitive than the terrestrial one.
Distribution Behaviour and Seed Germination of Alkanna orientalis Growing in Saint Catherine Protectorate
Abdel-Raouf A. Moustafa
Pakistan Journal of Biological Sciences , 2002,
Abstract: Seeds of Alkanna were tested to determine the germination behavior and dormancy (if present). Four treatments of temperature (5, 10, 15 & 20), soaking in boiled water (till cooling), chilling (2-5oC for one week) and mechanical scarification by sandpaper (for 5 min) were used to investigate the best germination percent. A set of alternations of temperature and light was applied. The results revealed that greatest germination percent occurred at combination of temperature and light with two degrees of temperature, 5oC with light off and 20oC with light on whereas the lowest germination percent occurred at constant low temperature (5oC). The ordination diagrams revealed that Alkanna orientalis occupies a great position between arrows of soil conditions and landform types which indicates that Alkanna affected by soil texture (fine sand fraction), moisture content and organic matter of the soil and boulders. Soil pH and coarse sand fraction were very close to Alkanna`s position in the ordination diagrams but statistically they did not show any significant meaning. In the meantime, eighteen associated species were distributed clearly between the environmental arrows in three layers around the center of the ordination.
Impact of Grazing Intensity and Human Disturbance on the Population Dynamics of Alkanna orientalis Growing in Saint Catherine Mountains, South Sinai, Egypt
Abdel-Raouf A. Moustafa
Pakistan Journal of Biological Sciences , 2001,
Abstract: The present study aimed to investigate the effect of grazing intensity on dynamics of Alkanna populations that grow in Saint Catherine mountains. Seventy plots (4x4 m2) were selected to represent variation of Alkanna orientalis population under different degrees of grazing and human disturbances. The results showed that four main groups of Alkanna population can be recognized. These groups differ significantly in the percentage of coverage, average of flower buds, flowers, fruits, plant height and grazing intensity and soil organic content. Insignificant variation in the soil moisture content, natality, and mortality were indicated. The impact of grazing and fencing was seen through the comparison between fenced and unfenced populations. The results revealed that the vegetation cover, average of plant height and reproductive organs (floral buds) increased for unfenced population as compared to fenced while percentage of dryness and average number of fruits was higher in fenced population. The results of natality and mortality showed that the four groups of Alkanna populations have different rates of natality occurring at third and fourth groups of populations (heavily grazed), whereas the mortality rate of first group was very high as compared to a very low rate in the fourth group

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