In the pathogenesis of several diseases, neo‐angiogenesis is increased (e.g. tumour growth). The ... more In the pathogenesis of several diseases, neo‐angiogenesis is increased (e.g. tumour growth). The peptide L‐glutamyl‐L‐tryptophan (EW/IM862) has been claimed to exhibit inhibitory effects on tumour growth in vivo. However, the potential role of natural peptides with respect to anti‐angiogenic properties is unsettled. The current study explores anti‐angiogenic effects of the dipeptides WL, EW, IW and WE.
This study attempts to simiplify the analysis and appication to engineering design of a previousl... more This study attempts to simiplify the analysis and appication to engineering design of a previously developed model. The experimental data indicate that the rutting parameters (A and m) are generally functions of the dynamic modulus and the applied dynamic stress. The dynamic modulus characterizes the material properties; i.e., it accounts for the water content, the dry density, and the soil structure as far as rutting criteria are concerned. The parameter m is almost constant for normal and dense soils, but may decrease slightly for very wet soils. There is a relation between the parameter A and the dynamic modulus E. The data show a linear relation betwen log A/E and log 1/E that is dependent on the applied dynamic stress level. Analysis of the results obatined by Montoya at different environmental conditions, verifies the uniqueness of the log A/E versus log 1/E relation. That is, the environmental changes are reflected in the dynamic modulus E and consequently in the values of pa...
This study was conducted to obtain data on state subgrade support conditions, develop correlation... more This study was conducted to obtain data on state subgrade support conditions, develop correlations between soil properties, design and rutting parameters and to develop a rutting model for Ohio soils. Nine representative soils selected from a soils survey were evaluated for material characteristics. Laboratory samples of each soil, compacted at various moisture contents and dry densities, were subjected to dynamic uniaxial loading with various dynamic stresses, wetting-drying to assess moisture effects on dynamic modulus and rutting parameters. Undisturbed samples from one project site were subjected to the same test program for comparison. Results indicate: (1) soils' resilient moduli exhibited dependency on moisture and density of in-situ soils; (2) subgrade saturation decreased resilient moduli by a factor of four, being more significant for soils compacted on dry side of optimum; at moisture contents 4% above optimum, moduli approached a minimum level independent of soil typ...
The International Conference on Civil and Architecture Engineering, 2010
In this study the use of marble dust, marble limestone and crushed marble collected during the sh... more In this study the use of marble dust, marble limestone and crushed marble collected during the shaping process of marble blocks has been investigated in the asphalt mixtures as filler material, limestone and sand. Six different asphalt mixes having marble dust, limestone dust filler, crushed marble, sand, limestone aggregate and marble aggregate were prepared. The optimum binder content was then determined by Marshall test procedures. The study showed that marble's wastes, which are in the dust form and crushed form could be used as filler material and sand in asphalt mixtures where they are available. This may reduce the cost of transportation compared to that when using ordinary paving materials.
International Conference on Aerospace Sciences and Aviation Technology, 1999
Two computer programs were reviewed and evaluated, one for linear an alysis (LA) and the other fo... more Two computer programs were reviewed and evaluated, one for linear an alysis (LA) and the other for non-linear analysis (NLA), to identify the most appropOate analysis type for flexible pavement structural analysis. The programs were three-dimensional (3-D) finite element (FE) programs called SAP90 and ANSYS5.3. The comparison items were the maximum surface deflection, the maximum' vertical compressive strain at the top of the subgrade and the maximum horizontal tensile strain at the bottom of the asphalt concrete (AC)'lkOr, which are the most commonly used criteria for pavement design. In addition to these items, maximum tensile stress in AC layer and vertical stress distribution alort the pavement depth were used as the basis for comparison. Three load conditions include horizontal forces (HF) were applied to the flexible pavement models. Non-linear analysis was found to be more realistic for flexible pavement analysis. It satisfied the surface boundary condition and gave more acceptable results when studying shoving and vertical stress distribution under loading center.
The scope of this study is to explore and evaluate the effect of reinforcing the interface betwee... more The scope of this study is to explore and evaluate the effect of reinforcing the interface between the base and asphalt concrete layers in a flexible pavement section with bi-axial geogrids; using both large scale experimental tests and numerical modeling using three-dimensional nonlinear finite elements analysis. A laboratory characterization for each layer of the pavement section according to a laboratory programs that included soil classification, plate loading test, determination of asphalt concrete dynamic modulus for and CBR ratio for different elements in pavement section. A laboratory model of the pavement with and without the geogrid reinforcement, located at the top of the base layer was constructed. A dynamic loading scheme was applied on the experimental pavement model. Concurrently, a numerical model was developed to simulate the effect of such type of reinforcement on the pavement section in terms of the road’s performance enhancement and reduction in rutting. The nume...
A 23-year-old man presented with a 2-year history of a slow growing lesion in the left eye. The l... more A 23-year-old man presented with a 2-year history of a slow growing lesion in the left eye. The lesion consisted of a vascularized, balloon-like mass straddling the limbus nasally (A). Histopathologic examination demonstrates (B) a conjunctival epitheliumwith solar elastosis, consistent with a pterygium (left side), and proliferation of melanocytic cells in the stroma and epithelial-stromal interface, consistent with a compound nevus (right side). It is important to note that, except for a small area on the left (black arrowhead) that demonstrates a normal thickness, the remainder of the conjunctiva shows considerable thickening, which measures as high as 6 times the normal value in some areas. This thickening, which gives the lesion its striking clinical appearance, is due to severe reactive fibrosis and solar elastotic changes. Magnification reveals the nevus component in more detail (C [white arrowheads]). Opinion Viewpoint
The scope of this study is to explore and evaluate the effect of reinforcing the interface betwee... more The scope of this study is to explore and evaluate the effect of reinforcing the interface between the base and asphalt concrete layers in a flexible pavement section with bi-axial geogrids; using both large scale experimental tests and numerical modeling using three-dimensional nonlinear finite elements analysis. A laboratory characterization for each layer of the pavement section according to a laboratory programs that included soil classification, plate loading test, determination of asphalt concrete dynamic modulus for and CBR ratio for different elements in pavement section. A laboratory model of the pavement with and without the geogrid reinforcement, located at the top of the base layer was constructed. A dynamic loading scheme was applied on the experimental pavement model. Concurrently, a numerical model was developed to simulate the effect of such type of reinforcement on the pavement section in terms of the road’s performance enhancement and reduction in rutting. The nume...
The main object of this paper is to provide the design engineer with a simple procedure to predic... more The main object of this paper is to provide the design engineer with a simple procedure to predict rutting in asphalt concrete without the need of a sophisticated test set up which may be difficult to acquire. A rutting model in a power form relating permanent strain and number of load repetitions was adopted. The validity of the model for asphalt concrete using a consolidation device, modified to accommodate asphalt concrete samples, was checked. The effects of asphalt content, temperature and stress level for two aggregate gradations on rutting parameters were investigated. The model was found to be valid for asphalt concrete under the simplified test method. The variations of resilient characteristic of the asphalt concrete, represented by a defined material's modulus, with test and material's variables were studied. A relation between rutting intersection parameter, material's modulus and the stress level was established for the materials used in this study.
... Safwan A. Khedra and Tamer M. Breakahb* aDepartment of Construction and Architectural Enginee... more ... Safwan A. Khedra and Tamer M. Breakahb* aDepartment of Construction and Architectural Engineering, The American University in Cairo, Cairo, Egypt; bDepartment of Civil, Construction, and Environmental Engineering ... 2. The restricted zone In a study by Chowdhury et al. ...
The scope of this study is to explore and evaluate the effect of reinforcing the interface betwee... more The scope of this study is to explore and evaluate the effect of reinforcing the interface between the base and asphalt concrete layers in a flexible pavement section with bi-axial geogrids; using both large scale experimental tests and numerical modeling using three-dimensional nonlinear finite elements analysis. A laboratory characterization for each layer of the pavement section according to a laboratory programs that included soil classification, plate loading test, determination of asphalt concrete dynamic modulus for and CBR ratio for different elements in pavement section. A laboratory model of the pavement with and without the geogrid reinforcement, located at the top of the base layer was constructed. A dynamic loading scheme was applied on the experimental pavement model. Concurrently, a numerical model was developed to simulate the effect of such type of reinforcement on the pavement section in terms of the road's performance enhancement and reduction in rutting. The numerical model was proved to verify simulation of the pavement experimental model when comparing the overall trend of stress distribution throughout the pavement structure.
In the pathogenesis of several diseases, neo‐angiogenesis is increased (e.g. tumour growth). The ... more In the pathogenesis of several diseases, neo‐angiogenesis is increased (e.g. tumour growth). The peptide L‐glutamyl‐L‐tryptophan (EW/IM862) has been claimed to exhibit inhibitory effects on tumour growth in vivo. However, the potential role of natural peptides with respect to anti‐angiogenic properties is unsettled. The current study explores anti‐angiogenic effects of the dipeptides WL, EW, IW and WE.
This study attempts to simiplify the analysis and appication to engineering design of a previousl... more This study attempts to simiplify the analysis and appication to engineering design of a previously developed model. The experimental data indicate that the rutting parameters (A and m) are generally functions of the dynamic modulus and the applied dynamic stress. The dynamic modulus characterizes the material properties; i.e., it accounts for the water content, the dry density, and the soil structure as far as rutting criteria are concerned. The parameter m is almost constant for normal and dense soils, but may decrease slightly for very wet soils. There is a relation between the parameter A and the dynamic modulus E. The data show a linear relation betwen log A/E and log 1/E that is dependent on the applied dynamic stress level. Analysis of the results obatined by Montoya at different environmental conditions, verifies the uniqueness of the log A/E versus log 1/E relation. That is, the environmental changes are reflected in the dynamic modulus E and consequently in the values of pa...
This study was conducted to obtain data on state subgrade support conditions, develop correlation... more This study was conducted to obtain data on state subgrade support conditions, develop correlations between soil properties, design and rutting parameters and to develop a rutting model for Ohio soils. Nine representative soils selected from a soils survey were evaluated for material characteristics. Laboratory samples of each soil, compacted at various moisture contents and dry densities, were subjected to dynamic uniaxial loading with various dynamic stresses, wetting-drying to assess moisture effects on dynamic modulus and rutting parameters. Undisturbed samples from one project site were subjected to the same test program for comparison. Results indicate: (1) soils' resilient moduli exhibited dependency on moisture and density of in-situ soils; (2) subgrade saturation decreased resilient moduli by a factor of four, being more significant for soils compacted on dry side of optimum; at moisture contents 4% above optimum, moduli approached a minimum level independent of soil typ...
The International Conference on Civil and Architecture Engineering, 2010
In this study the use of marble dust, marble limestone and crushed marble collected during the sh... more In this study the use of marble dust, marble limestone and crushed marble collected during the shaping process of marble blocks has been investigated in the asphalt mixtures as filler material, limestone and sand. Six different asphalt mixes having marble dust, limestone dust filler, crushed marble, sand, limestone aggregate and marble aggregate were prepared. The optimum binder content was then determined by Marshall test procedures. The study showed that marble's wastes, which are in the dust form and crushed form could be used as filler material and sand in asphalt mixtures where they are available. This may reduce the cost of transportation compared to that when using ordinary paving materials.
International Conference on Aerospace Sciences and Aviation Technology, 1999
Two computer programs were reviewed and evaluated, one for linear an alysis (LA) and the other fo... more Two computer programs were reviewed and evaluated, one for linear an alysis (LA) and the other for non-linear analysis (NLA), to identify the most appropOate analysis type for flexible pavement structural analysis. The programs were three-dimensional (3-D) finite element (FE) programs called SAP90 and ANSYS5.3. The comparison items were the maximum surface deflection, the maximum' vertical compressive strain at the top of the subgrade and the maximum horizontal tensile strain at the bottom of the asphalt concrete (AC)'lkOr, which are the most commonly used criteria for pavement design. In addition to these items, maximum tensile stress in AC layer and vertical stress distribution alort the pavement depth were used as the basis for comparison. Three load conditions include horizontal forces (HF) were applied to the flexible pavement models. Non-linear analysis was found to be more realistic for flexible pavement analysis. It satisfied the surface boundary condition and gave more acceptable results when studying shoving and vertical stress distribution under loading center.
The scope of this study is to explore and evaluate the effect of reinforcing the interface betwee... more The scope of this study is to explore and evaluate the effect of reinforcing the interface between the base and asphalt concrete layers in a flexible pavement section with bi-axial geogrids; using both large scale experimental tests and numerical modeling using three-dimensional nonlinear finite elements analysis. A laboratory characterization for each layer of the pavement section according to a laboratory programs that included soil classification, plate loading test, determination of asphalt concrete dynamic modulus for and CBR ratio for different elements in pavement section. A laboratory model of the pavement with and without the geogrid reinforcement, located at the top of the base layer was constructed. A dynamic loading scheme was applied on the experimental pavement model. Concurrently, a numerical model was developed to simulate the effect of such type of reinforcement on the pavement section in terms of the road’s performance enhancement and reduction in rutting. The nume...
A 23-year-old man presented with a 2-year history of a slow growing lesion in the left eye. The l... more A 23-year-old man presented with a 2-year history of a slow growing lesion in the left eye. The lesion consisted of a vascularized, balloon-like mass straddling the limbus nasally (A). Histopathologic examination demonstrates (B) a conjunctival epitheliumwith solar elastosis, consistent with a pterygium (left side), and proliferation of melanocytic cells in the stroma and epithelial-stromal interface, consistent with a compound nevus (right side). It is important to note that, except for a small area on the left (black arrowhead) that demonstrates a normal thickness, the remainder of the conjunctiva shows considerable thickening, which measures as high as 6 times the normal value in some areas. This thickening, which gives the lesion its striking clinical appearance, is due to severe reactive fibrosis and solar elastotic changes. Magnification reveals the nevus component in more detail (C [white arrowheads]). Opinion Viewpoint
The scope of this study is to explore and evaluate the effect of reinforcing the interface betwee... more The scope of this study is to explore and evaluate the effect of reinforcing the interface between the base and asphalt concrete layers in a flexible pavement section with bi-axial geogrids; using both large scale experimental tests and numerical modeling using three-dimensional nonlinear finite elements analysis. A laboratory characterization for each layer of the pavement section according to a laboratory programs that included soil classification, plate loading test, determination of asphalt concrete dynamic modulus for and CBR ratio for different elements in pavement section. A laboratory model of the pavement with and without the geogrid reinforcement, located at the top of the base layer was constructed. A dynamic loading scheme was applied on the experimental pavement model. Concurrently, a numerical model was developed to simulate the effect of such type of reinforcement on the pavement section in terms of the road’s performance enhancement and reduction in rutting. The nume...
The main object of this paper is to provide the design engineer with a simple procedure to predic... more The main object of this paper is to provide the design engineer with a simple procedure to predict rutting in asphalt concrete without the need of a sophisticated test set up which may be difficult to acquire. A rutting model in a power form relating permanent strain and number of load repetitions was adopted. The validity of the model for asphalt concrete using a consolidation device, modified to accommodate asphalt concrete samples, was checked. The effects of asphalt content, temperature and stress level for two aggregate gradations on rutting parameters were investigated. The model was found to be valid for asphalt concrete under the simplified test method. The variations of resilient characteristic of the asphalt concrete, represented by a defined material's modulus, with test and material's variables were studied. A relation between rutting intersection parameter, material's modulus and the stress level was established for the materials used in this study.
... Safwan A. Khedra and Tamer M. Breakahb* aDepartment of Construction and Architectural Enginee... more ... Safwan A. Khedra and Tamer M. Breakahb* aDepartment of Construction and Architectural Engineering, The American University in Cairo, Cairo, Egypt; bDepartment of Civil, Construction, and Environmental Engineering ... 2. The restricted zone In a study by Chowdhury et al. ...
The scope of this study is to explore and evaluate the effect of reinforcing the interface betwee... more The scope of this study is to explore and evaluate the effect of reinforcing the interface between the base and asphalt concrete layers in a flexible pavement section with bi-axial geogrids; using both large scale experimental tests and numerical modeling using three-dimensional nonlinear finite elements analysis. A laboratory characterization for each layer of the pavement section according to a laboratory programs that included soil classification, plate loading test, determination of asphalt concrete dynamic modulus for and CBR ratio for different elements in pavement section. A laboratory model of the pavement with and without the geogrid reinforcement, located at the top of the base layer was constructed. A dynamic loading scheme was applied on the experimental pavement model. Concurrently, a numerical model was developed to simulate the effect of such type of reinforcement on the pavement section in terms of the road's performance enhancement and reduction in rutting. The numerical model was proved to verify simulation of the pavement experimental model when comparing the overall trend of stress distribution throughout the pavement structure.
Uploads
Papers by S. Khedr