Clinoptilolite is a natural zeolite which can be used favorably in heavy metal removal. The main mechanisms for metal removal via clinoptilolite are adsorption and ion exchange. Several sources propose to keep the normality constant to obtain equilibrium isotherms for ion exchange systems, while many studies use constant sorbent mass with varying normalities of the sorbate. The objective of this study is to investigate the prevailing mechanisms of clinoptilolite during cadmium removal and the impact of the methodology for obtaining equilibrium isotherms. Batch Cd2+ removal experiments were conducted by using the two different methodologies (i.e. keeping the sorbent mass constant vs. keeping the normality constant) with clinoptilolite in as-received (AsC) and conditioned form (CnC), an ion exchange resin and granulated activated carbon. Exchangeable and framework cations, conductivity and pH were monitored during experiments. The equilibrium results were then fitted to isotherm models. The prevailing mechanisms for Cd2+ removal with clinoptilolite are discussed considering all monitored parameters and isotherm model fits. Use of the methodology was seen to have an effect on the overall Cd2+-clinoptilolite interaction. For example, differences between methodologies are observed regarding maximum sorbed Cd2+ and the distribution of exchangeable cations. Conductivity profiles provided a good indication of presence of ion exchange and demonstrated that it is more dominating for CnC than for AsC. The Cd2+ removal capacities observed in this study (0.65 meq/g for AsC and 1.46 meq/g for CnC) are the highest recorded for a clinoptilolite sample, as can be found in the literature.

This thesis applies T.M. Scanlon's version of contractualism to the problem of future generations. I begin by analyzing Rawls' contractarian account of just savings and find that there is no plausible composition of the original position that can deal with the inclusion of future people. I then examine Scanlon's contractualism and some objections to it before moving on to applying it to future people. I argue that the disanalogies between the intra- and inter-generational contexts do not preclude including future people in the contractualist framework, and that the theory avoids the non-identity problem. Part II of the thesis applies contractualism to three intergenerational topics and develops principles governing them: resource conservation, procreation, and population size. To conclude, I address how to deal with the fact that, in the case of future generations, we often have imperfect knowledge of what they will need, how our actions will affect them, and how many of them there will be.

The thesis argues that two ways in which we can consider empathy’s role in ethics are fundamentally flawed because they fail to take into account the myriad ways in which empathy can be affected and influenced by our motivations. I apply what I call ‘the motivation objection’ to these two views. This has three aspects: (1) reliability: because empathy can be affected and influenced by our motivations, empathizing does not always lead to the right results; (2) function: because it can be affected and influenced by our motivations, empathy is not sufficient for various functions; (3) circularity: because it can be affected and influenced by our motivations, empathy cannot be used to define or explain certain aspects of morality in a non-circular way. The two ways of considering empathy’s role in ethics are what I call constitutive views, according to which empathy in some way constitutes, or is the foundation for, morality, and instrumental views, according to which empathy is of instrumental value in morality. I apply the motivation objection to three constitutive views, two historical and one contemporary, each of which is a sentimentalist theory of morality with empathy (or sympathy, in the case of the historical theories) at its heart. These are the sentimentalist moral theories of David Hume, Adam Smith and Michael Slote. I then apply the motivation objection to instrumental views of empathy’s role in ethics, before defending one particular instrumental view, according to which empathy can play a positive role in morality when integrated with virtue, and the virtue of compassion in particular.

The marginal glass-forming alloys have attracted much attention due to unique products of devitrification with a very high number density of nuclei up to 10^23 m^-3. Among these alloy systems, utmost interest is given to Al-RE and Al-TM-RE alloys with excellent lightweight mechanical (fracture strength close to 1 GPa) and chemical properties attributed to the presence of an extremely high density of nanocrystals embedded in an amorphous matrix. Classical nucleation theory fails in explaining this abnormal nucleation behavior, several other mechanisms have been proposed / however, there is still no agreement on the exact nucleation mechanism. Al-Tb system was investigated in liquid and solid amorphous states with a collective study of ab-initio MD and RMC simulations and state of art X-rays and e-beam techniques. Regions of pure Al clusters in the solid and liquid states were detected with the sizes extending up to 1-2 nm length. Al clusters interconnecting regions lead to formation of RE rich MRO structure which gave rise to the pre-peak in S(Q)-Q data in liquid and solid states. Specimens having MRO were crystallized within a controlled atmosphere and temperature and investigated using a combined study of TEM, HRTEM, SEM, XRD and DSC. HRTEM investigations and JMA results indicated different mechanism of nucleation. Therefore the kinetics of highly populated nuclei formation was found too complicated to be explained by well-known JMA approach. Mechanical tests were applied to determine the effects of morphology and populations of nanocrystals embedded in amorphous matrix. The tensile tests and the subsequent fracture surface analysis indicated brittle type of failure and the formation of shear bands, respectively. Relatively high hardness and tensile strength were detected by nanocrystallization.

Endo-b-1,4 xylanases (EC. 3.2.1.8) are typically produced as a mixture of different hydrolytic enzymes such as b-1,4-xylosidase (EC. 3.2.1.37) , a-Larabinofuranosidases (EC. 3.2.1.55), and feruloyl esterase (EC 3.1.1.73) that hydrolyze xylan molecule, which constitutes 20-30% of the weight of wood and agricultural wastes. Thus, xylan, a renewable biomass, can be utilized as a substrate for the preparation of many products such as fuels, solvents and pharmaceuticals. Besides, xylanolytic enzymes themselves are also used in food,feed, textile industries and pre-bleaching of kraft. In the first part of the study, xylanolytic systems of a soil isolate Bacillus pumilus SB-M13 and a thermophilic fungus Scytalidium thermophilum were investigated. Production rate and type of xylanolytic changed depending on the carbon source and the microorganism. However, xylanolytic enzyme production was found to be sequential, in synergy and under the control of carbon catabolite repression for both microorganisms. In the second part, B. pumilus SB-M13 b-1,4 xylanase was purified and biochemically characterized. The enzyme was stable at alkaline pHs and highest activity was observed at 60&deg / C and pH 7.5. Enzyme Km and kcat values were determined as 1.87 mg/ml and 43,000 U/mg, respectively. B. pumilus SB-M13 and S .thermophilum a-L-arabinofuranosidases were also purified and biochemically characterized. Although produced from a mesophilic microorganism, B. pumilus SB-M13 arabinofuranosidase was quite thermostable. Moreover, unlike other fungi, S. thermophilum produced alkaline stable arabinofuranosidases. Both enzymes were multimeric, alkaline stable and most active at 70&deg / C and pH 7.0. However, when compared to S. thermophilum, catalytic power of B. pumilus SB-M13 arabinofuranosidase was higher.

The analytical and numerical modeling of CO2 sequestration in deep saline aquifers having different properties was studied with diffusion and convection mechanisms. The complete dissolution of CO2 in the aquifer by diffusion took thousands, even millions of years. In diffusion dominated system, an aquifer with 100 m thickness saturated with CO2 after 10,000,000 years. It was much earlier in convective dominant system. In diffusion process, the dissolution of CO2 in aquifer increased with porosity increase / however, in convection dominant process dissolution of CO2 in aquifer decreased with porosity increase. The increase in permeability accelerated the dissolution of CO2 in aquifer significantly, which was due to increasing velocity. The dissolution process in the aquifer realized faster for the aquifers with lower dispersivity. The results of convective dominant mechanism in aquifers with 1md and 10 md permeability values were so close to that of diffusion dominated system. For the aquifer having permeability higher than 10 md, the convection mechanism began to dominate gradually and it became fully convection dominated system for 50 md and higher permeability values. These results were also verified with calculated Rayleigh number and mixing zone lengths. The mixing zone length increased with increase in porosity and time in diffusion dominated system. However, the mixing zone length decreased with increase in porosity and it increased with increase in dispersivity and permeability higher than 10 md in convection dominated system.

Main purpose of this study was to find the optimum conditions to produce a charge material for ferromanganese production or steelmaking with high content of iron and manganese carbides from Denizli-Tavas manganese ore by carbothermic reduction and investigate the effects of temperature, time, amount of active carbon addition and CaO addition on this reduction. The ore was calcined and then mixed with active carbon and CaO. Experiments were performed in a horizontal tube furnace that can be heated up to 1700 &ordm / C with MoSi2 heating elements. After each experiment weight loss data were obtained and converted to percentage reduction. X-Ray, SEM-EDS and chemical analyses were done in order to determine whether or not carbide phases have been obtained, and calculate the composition of the product. Considering the experimental results, the optimum conditions found for reduction of Denizli-Tavas manganese ore were 1250 &deg / C, 4 hours, 100% of stoichiometric amount of active carbon and 5% CaO addition. Under the optimum conditions 83.85% reduction of calcined ore was obtained.

The design and production of efficient metal-hydrides for hydrogen storage is a long standing subject. Over the years, many different types of intermetallic hydride systems were studied and some of them came out to be operable. However, none of them meet all the storage criteria perfectly. In this study, total energies, hydrogen storage capacity and stability of AB (A = Al, Be, Cu, Fe, Ni, Sb, V and B = Ti) type intermetallics were investigated with the goal of spotting a potential hydrogen storage material. The relation between thermodynamic properties and the atomic and the electronic structure of hydrides are also pointed out. For this task, first principles pseudopotential method within the generalized gradient approximation (GGA) to density functional theory (DFT) was used. Calculations correctly predict experimentally determined structures except for CuTiH. Moreover, the atomic and cell parameter were found within the allowable error interval for DFT. In CuTi intermetallic, a structure having considerably lower formation energy than experimentally found mono-hydride was determined. This contradiction may be due to metastability of the experimental phase and high activation energy for the hydrogen movement in the system. It was found that AlTi and SbTi are not suitable candidates for hydrogen storage since their hydrides are too unstable. For the other intermetallic systems, the stability of the hydrides decreases in the order of VTi, CuTi, NiTi, BeTi, FeTi. For VTi, FeTi and NiTi, a change in metallic coordination around hydrogen from octahedron to tetrahedron is predicted when tetra-hydride (MTiH4) is formed. Additionally, at this composition, FeTi and NiTi have hydride structures with positive but near-zero formation energy which may be produced with appropriate alteration in chemical makeup or storage parameters. VTi is a promising intermetallic by means of storage capacity in that even VTiH6 is found to have negative formation energy but the hydrides are too stable which can be a problem during hydrogen desorption.

In presplit blasting operations airborne energy called air blast overpressure or impulsive sound is produced. The air blast induced by blasting may vary significantly at or around an open pit mine depending on several parameters such as the amount of charge detonated, the physical distance between the blast and the monitoring locations and the weather conditions. Therefore evaluation and assessment of noise condition at or around an open pit mine is necessary. The objective of this research study is to monitor and record the noise and to investigate and assess the noise conditions that will be induced from presplit blasting operations at Kisladag Gold Mine. In this research study, several parameters such as the amount of charge, the physical distance to the location of monitoring device or residential structures and the weather condition parameters such as wind direction, wind speed were recorded, analyzed and evaluated. It is observed that with increasing charge per delay air overpressure increases, whereas with increasing scaled distances it decreases. It is also understood that wind speed and the direction are effective in air overpressure propagation also, but this subject needs further investigation. It is concluded that according to the U.S. regulations there is no damage risk to the structures and no disturbance to the inhabitants at present. Due to the uncertainties in weather conditions, in order not to take any risks, the charge amount per delay should be kept at 35 kg or less for presplit blasting at the mine.

In this thesis 10x10 reconfigurable reflectarray is designed at 26.5 GHz where the change in the progressive phase shift between elements is obtained with RF MEMS switches in the transmission lines of unit elements composed of aperture coupled microstrip patch antenna (ACMPA). The reflectarray is illuminated by a horn antenna, and the reflected beam is designed to switch between broadside and 40&deg / by considering the position of the horn antenna with respect to the reflectarray. In the design, the transmission line analysis is applied for matching the ACMPA to the free space. The full wave simulation techniques in HFSS are discussed to obtain the phase design curve which is used in determining two sets of transmission line lengths for each element, one for the broadside and the other for switching to the 40&deg / at 26.5 GHz. The switching between two sets of transmission line lengths is sustained by inserting RF MEMS switches into the transmission lines in each element. Two types of RF MEMS switches, series and shunt configurations, are designed for the switching purpose in the reflectarray. The phase errors due to nonideal phase design curve and type of the RF MEMS switch are reduced. The possible mutual coupling effects of the bias lines used to actuate the RF MEMS switches are also eliminated by the proper design. To show the validity of the design procedure, a prototype of 20x20 reflectarray composed of ACMPA elements is designed at 25GHz and produced using Printed Circuit Board (PCB) technology. The measurement results of the prototype reflectarray show that the main beam can be directed to the 40&deg / as desired. The process flow for the production of the reconfigurable reflectarray is suggested in terms of integration of the wafer bonding step with the in-house standard surface micromachined RF MEMS process.