Additive Manufacturing of Porous Titanium Structures for Use in Orthopaedic Implants

This dissertation explores additive manufacturing of porous titanium structures for possible use as scaffolds in orthopaedics. Such scaffolds should be tailored in terms of mechanical properties and porosity to satisfy specific physical and biological needs. In this thesis, powder metallurgy was combined with additive manufacturing to successfully fabricate porous Ti structures. This study describes physical, chemical, and mechanical characterizations of porous titanium implants made by the proposed powder bed inkjet-based additive manufacturing process to gain insight into the correlation of process parameters and final physical and mechanical properties of the porous structure. A number of processing parameters were investigated to control the mechanical properties and porosity of the structure. In addition, a model was developed based on the microstructural powder compaction to predict the porosity as a function of the developed sinter neck among the particles during the sintering process. The produced samples were characterized through several methods including porosity measurement, compression test, Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), and shrinkage measurements. Additionally, a new method for manufacturing Ti implants includes encapsulated networks of macro-sized channels was introduced. Also, the influence of different orientations and numbers of channels within the additive-manufactured structures were investigated. The characterization test results showed a level of porosity in the samples in the range of 12-43%, which is within the range of cancellous and cortical bone porosity. The compression test results showed that the porous structure’s compressive strength is in the range of 56-1000 MPa, yield strength is in the range of 27-383 MPa, and Young’s modulus is in the range of 0.77-11.46 GPa. This technique of manufacturing porous Ti structures demonstrated a low level of shrinkage with the shrinkage percentage ranging from 1.5-12%. Also, the experimental results demonstrated excellent agreement with the developed model. Moreover, the novel method of fabricating the encapsulated channel show a reduction in the shear strength to 24-30% that is advantageous for bone implants. The results demonstrate that the channel orientation in the structure affect the shrinkage rate in the parts with vertically orientated channels, in which a relatively isotropic shrinkage in vertical and horizontal directions is achieved after sintering

Diversity of active constituents in Cichorium endivia and Cynara cornigera extracts

The present study attempts to explore the phytochemical constituents of different extracts from Cynara cornigera and Cichorium endivia plant materials. The two species studied are native in Egypt. Five different solvents, viz., aqueous, methylene chloride, petroleum ether, ethyl acetate, and n-butanol were used. Phytochemical analysis revealed the presence of phenols, flavonoids, sterols (stigmasterol and beta-sitosterol), terpenes (α-amyrin, ursolic and oleanolic acid), and hydrocarbons (n-alkane), the latter found in low amount. The ethyl acetate and water extracts of C. cornigera root showed lower mass fractions of phenolic compounds ranged from 20 to 81 g/100 g, and higher amounts in ethyl acetate extract of the inflorescences and butanol extract of the root where values ranged from 195 to 399 g/100 g. The β-sitosterol and stigmasterol were present in all plant extracts. Oleanolic and ursolic acids were detected in roots, leaves and inflorescences of C. cornigera and in C. endivia shoot. The ethyl acetate extracts from C. cornigera leaf and inflorescence attained higher chemical diversity than the other extracts. Alternatively, sterols and triterpenes were the major constituents. The high chemical diversity of active constituents justifies the future potential use of the two species at commercial level

Analysis of some plant growth regularsin some medicinal dorment seeds of desert plants in Saudi Arabia.I.Cytokinin content of Rhazya stricta seeds.

Three populationsof Rhazya stricta seeds, non stored (1999 collection), short term stored (1998 collectio) and long- term stored (1982 collection) were used to study their endogenous level of cytokinins. Using appropriate internal standards, an HPLC profile revealed the absence of free zeatin in quiescent seeds of all of the R. Stricta seed populations used. Zeatin ribosides predominated other cytokinins in all three types of seeds. trans-zeatin and dihydrozeatin contents were high in the 1998 collection followed by 1982 and 1999 collections. Isopentyladenine was also detected but in very small amounts, in the samples of seeds tested

Influences of Salinity, Light and Temperature on Seed Germination of Leucaena leucocephala (Lam.) de Wit.

The experiment was investigated to study evaluate the seed germination of Leucaena leucocephala (Lam.) de Wit. under salinity, temperature, light and their interaction on the rate and final percentage of germination. The experiment was carried out in plant physiology laboratory at College of Science, King Saud University, Riyadh, Saudi Arabia. The collected seeds of Leucaena was treated with boiling water for 3 minutes then left to germinate in Petri dishes in growth chamber under the investigated treatments. Seven concentrations of sodium chloride solution had EC of (0, 50, 100, 300, 400, 500 and 600 mM) were applied to seeds as irrigation water and exposed to three temperature degree (20, 30 and 40 oC). Seeds untreated with NaCl germinated well in a wide range of temperatures and in both full light and complete dark. Seed germination decreased significantly with the increase in both NaCl concentration and temperature. Optimal germination percentage occurred at 30 oC. The inhibitory effect of high salinity on final germination percentage was greater at 40 oC than at 20 and 30 oC. However, germination rate was significantly greater at 40 oC than at 20 and 30 oC in lower salinity and the reverse was true at higher salinity. Germination in light was significantly greater than in the dark at lower salinity levels and high temperature

Influences of Salinity, Light and Temperature on Seed Germination of Leucaena leucocephala (Lam.) de Wit.

The experiment was investigated to study evaluate the seed germination of Leucaena leucocephala (Lam.) de Wit. under salinity, temperature, light and their interaction on the rate and final percentage of germination. The experiment was carried out in plant physiology laboratory at College of Science, King Saud University, Riyadh, Saudi Arabia. The collected seeds of Leucaena was treated with boiling water for 3 minutes then left to germinate in Petri dishes in growth chamber under the investigated treatments. Seven concentrations of sodium chloride solution had EC of (0, 50, 100, 300, 400, 500 and 600 mM) were applied to seeds as irrigation water and exposed to three temperature degree (20, 30 and 40 oC). Seeds untreated with NaCl germinated well in a wide range of temperatures and in both full light and complete dark. Seed germination decreased significantly with the increase in both NaCl concentration and temperature. Optimal germination percentage occurred at 30 oC. The inhibitory effect of high salinity on final germination percentage was greater at 40 oC than at 20 and 30 oC. However, germination rate was significantly greater at 40 oC than at 20 and 30 oC in lower salinity and the reverse was true at higher salinity. Germination in light was significantly greater than in the dark at lower salinity levels and high temperature

Computational Optimization of 3D-Printed Concrete Walls for Improved Building Thermal Performance

Three-dimensional printing technologies are transforming various sectors with promising technological abilities and economic outcomes. For instance, 3D-printed concrete (3DPC) is revolutionizing the construction sector with a promise to cut projects’ costs and time. Therefore, 3DPC has been subjected to extensive research and development to optimize the mechanical and thermal performance of concrete walls produced by 3D printing. In this paper, we conduct a comparative investigation of the thermal performance of various infill structures of 3DPC walls. The targeted outcome is to produce an infill structure with optimized thermal performance to reduce building energy consumption without incurring additional material costs. Accordingly, a computational model is developed to simulate the thermal behavior of various infill structures that can be used for 3DPC walls. The concrete composition and the concrete-to-void fraction are maintained constant to focus on the impact of the infill structure (geometric variations). The thermal performance and energy-saving potential of the 3DPC walls are compared with conventional construction materials, including clay and concrete bricks. The results show that changing the infill structure of the 3DPC walls influences the walls’ thermal conductivity and, thereby, the building’s thermal performance. The thermal conductivity of the examined infill structures is found to vary between 0.122 to 0.17 W/m.K, while if these structures are successful in replacing conventional building materials, the minimum annual saving in energy cost will be about $1/m2. Therefore, selecting an infill structure can be essential for reducing building energy consumption

Comparison of Carbohydrate Content, Invertase and α-Amylase Activities in leaves of Medicago sativa L. and Tephrosia appolinea (Del.) link Infected by Uromyces striatus

Healthy and diseased leaves of Medicago stavia L. contained less reducing sugar, sucrose, polysaccharides and total carbohydrates than those Tephrosia appolinea (del.) Link. After infection by Uromyces striatus, total carbohydrates increased in both Medicago sativa and tephrosia appolinea leaves and reducing sugars were unchanged. Sucrose content decreased in M. sativa. The activity of invertase was found to be greater than that of α-Amylase in both plant leaves. Invertase activity increased and α- Amylase activity decreased after rust infection in leaves of both plants. Increased invertase activity and decreased sucrose content on infection suggest the occurrence of either phloem unloading or decreased export of photosynthetic products

Computational Optimization of 3D-Printed Concrete Walls for Improved Building Thermal Performance

Three-dimensional printing technologies are transforming various sectors with promising technological abilities and economic outcomes. For instance, 3D-printed concrete (3DPC) is revolutionizing the construction sector with a promise to cut projects’ costs and time. Therefore, 3DPC has been subjected to extensive research and development to optimize the mechanical and thermal performance of concrete walls produced by 3D printing. In this paper, we conduct a comparative investigation of the thermal performance of various infill structures of 3DPC walls. The targeted outcome is to produce an infill structure with optimized thermal performance to reduce building energy consumption without incurring additional material costs. Accordingly, a computational model is developed to simulate the thermal behavior of various infill structures that can be used for 3DPC walls. The concrete composition and the concrete-to-void fraction are maintained constant to focus on the impact of the infill structure (geometric variations). The thermal performance and energy-saving potential of the 3DPC walls are compared with conventional construction materials, including clay and concrete bricks. The results show that changing the infill structure of the 3DPC walls influences the walls’ thermal conductivity and, thereby, the building’s thermal performance. The thermal conductivity of the examined infill structures is found to vary between 0.122 to 0.17 W/m.K, while if these structures are successful in replacing conventional building materials, the minimum annual saving in energy cost will be about $1/m2. Therefore, selecting an infill structure can be essential for reducing building energy consumption

Essential Oils from Wood, Bark, and Needles of Pinus roxburghii Sarg. from Alexandria, Egypt: Antibacterial and Antioxidant Activities

The essential oils extracted by hydro-distillation of Pinus roxburghii wood, bark, and needles were analyzed by GC/MS, and their antibacterial and antioxidant activities were evaluated. Twenty-two, thirty-one, and twenty-eight compounds were identified in the essential oils of wood, bark, and needles, respectively. The major chemical constituents of wood’s essential oil were caryophyllene (16.75%), thunbergol (16.29%), 3-carene (14.95%), cembrene (12.08%), α-thujene (10.81%), and terpinolen (7.17%). In bark, they were α-pinene (31.29%) and 3-carene (28.05%), and in needles, they were α-pinene (39%) and 3-carene (33.37%). Almost all of the essential oils were active against human pathogen bacteria, and the essential oils from bark and needles were active against the plant pathogen bacteria Ralstonia solanacearum and Pectobacterium carotovorum. Alternatively, Erwinia amylovora was resistant to all tested oils. The total antioxidant activities (TAA%) of the essential oils from wood (82 ± 2.12%), and bark (85 ± 1.24%) were higher than that of tannic acid (81 ± 1.02%), and the TAA% from the essential oil of needles (50 ± 2.24%) was lower than that of tannic acid