Thermodynamics of inclusion formation in Fe-Cr-Ti-N alloys

The thermodynamics of titanium in Fe-Cr alloys and of inclusion formation in Fe-Cr-N-Ti alloys was investigated. A metal-nitride-gas equilibration technique was used to measure the activity of titanium. The equilibrium titanium content of the metal that is in equilibrium with pure solid titanium nitride and nitrogen gas at 1 atm was determined. The activity coefficients of titanium it(f_Ti) relative to 1 wt pct standard state in Fe were calculated for Fe-Cr alloys from the experimental results. The first-order interaction coefficient between titanium and chromium, e _Ti ^Cr , was determined to be 0.024 at 1873 K. The solubility of nitrogen in Fe-Cr alloys was measured and was found to increase with chromium content, which is in agreement with previous work. Thermodynamic calculations were made in order to predict under what conditions titanium nitride will form in 409 stainless steel and was compared with inclusions found in plant samples. The inclusion stability diagrams for 304 stainless steel and Fe-18 pct Cr and Fe-9 pct Cr alloys were computed.     

Power generation expansion planning with adaptive simulated annealing genetic algorithm

In this paper, an adaptive simulated annealing genetic algorithm is proposed to solve generation expansion planning of Turkey's power system. Least‐cost planning is a challenging optimization problem due to its large‐scale, long‐term, nonlinear, and discrete nature of power generation unit size. Genetic algorithms have been successfully applied during the past decade, but they show some limitations in large‐scale problems. In this study, simulated annealing is used instead of mutation operator to improve the genetic algorithm. The improved algorithm is applied to the power generation system with seven types of generating units and a 20‐year planning horizon. The planning horizon is divided into four equal periods. The new algorithm provides approximately 6.6 billion US$ (3.2%) cheaper solution than GA and also shows faster convergence. Copyright © 2006 John Wiley & Sons, Ltd.     

Better visualization of retinoblastoma metastases with Tc-99m sestamibi versus Tl-201

Tc-99m sestamibi has been shown to accumulate in several primary malignant tumors, but data regarding its use in the detection of distant metastases are limited. Despite its physical limitations, Tl-201 now has a definite place in the routine evaluation of certain primary and metastatic tumors. This report describes the value of Tc-99m sestamibi and its superiority to Tl-201 in the visualization of distant metastases in a 2-year-old girl with bilateral retinoblastoma. Three sites of soft tissue and bone metastasis were demonstrated by Tc-99m sestamibi imaging. Of these metastases, the one in the parieto-occipital region showed evident Tl-201 uptake, while the other two in the right arm and chest wall showed only slightly increased uptake, which could hardly be spotted without the confirmation of a later Tc-99m sestamibi scan. The scintigraphic findings were confirmed with histopathologic examination. Tc-99m sestamibi scan is effective and superior to Tl-201 in the detection of distant soft tissue and bone metastases from retinoblastoma.     

The rate of formation of SiO by the reaction of CO or H2 with silica and silicate slags

The rate of formation of SiO(g) by the reaction of CO and H₂ with silica or silicate slags containing SiO₂, CaO, and A1₂O₃ has been measured. The rate with hydrogen for both pure silica and silica in slags is controlled by gas phase mass transport. The rate changed with flow conditions, sample size, and gas properties as predicted by the appropriate mass transfer equations. In particular, the rate is faster in H₂-He than in H₂-Ar gas mixtures with the same hydrogen pressure, which proves conclusively the rate is controlled by gas phase mass transport. The rate of formation of SiO by the reaction of silica with CO did not change with flow conditions or particle size and the rate was the same in CO-He and CO-Ar with the same pressure of CO. In addition, the calculated rate with CO for mass transfer is considerably faster than was observed. These observations strongly indicate the rate is controlled by chemical kinetics on the surface. Similar results were obtained for the rate of reaction of CO with silica in slags and the rate was found to be proportional to the activity of SiO₂ and CO pressure. The present results are discussed in relationship to silicon transfer in slag-metal reactions.     

Estimating Motion From MRI Data

Magnetic resonance imaging (MRI) is an ideal imaging modality to measure blood flow and tissue motion. It provides excellent contrast between soft tissues, and images can be acquired at positions and orientations freely defined by the user. From a temporal sequence of MR images, boundaries and edges of tissues can be tracked by image processing techniques. Additionally, MRI permits the source of the image signal to be manipulated. For example, temporary magnetic tags displaying a pattern of variable brightness may be placed in the object using MR saturation techniques, giving the user a known pattern to detect for motion tracking. The MRI signal is a modulated complex quantity, being derived from a rotating magnetic field in the form of an induced current. Well-defined patterns can also be introduced into the phase of the magnetization, and could be thought of as generalized tags. If the phase of each pixel is preserved during image reconstruction, relative phase shifts can be used to directly encode displacement, velocity and acceleration. New methods for modeling motion fields from MRI have now found application in cardiovascular and other soft tissue imaging. In this review, we shall describe the methods used for encoding, imaging, and modeling motion fields with MRI.     

Two germ-line mutations affecting the same nucleotide at codon 257 of p53 gene, a rare site for mutations

Codon 257 of the p53 gene is an extremely rare target for somatic mutations (accounting for only two of 1600 published mutations). We report here two constitutional mutations both affecting the second nucleotide of codon 257. A thymine to adenine transversion resulting in an amino acid change from leucine to glutamine was found in one proband who developed multiple independent malignant tumors (osteosarcoma, phyllodes tumor, soft-tissue sarcoma). Her mother died of early-onset breast cancer. In the other case, a deletion resulting in a frameshift in the C-terminal coding region of p53 was found in a woman who was diagnosed with breast cancer at age 34. This woman belongs to a family with features of Li-Fraumeni syndrome. In both cases, the p53 mutations identified in the proband was found in other members of the family. Codon 257, even if rarely mutated in somatic cells, may thus be an important target for germ-line mutations.     

Modification of petroleum coke by different additives and the impact on anode properties

Anodes, which provide the carbon required for aluminum production, are made from dry aggregates (petroleum coke, rejected anodes, and butts) with coal tar pitch as the binder. Good quality anodes require good interaction between coke and pitch, and this relies on good wetting properties. The objectives of this work are to analyze the wetting properties of four different cokes with and without modification using an additive and to test the effect of the modified coke on anode properties. A FTIR study was done to identify functional groups in non‐modified and modified coke samples since they play an important role on coke‐pitch interactions. The wetting tests were done using the sessile‐drop method to measure the contact angle between coke and pitch. The results showed that the additive improved the wettability of all four cokes by pitch. The least wettable coke was chosen to produce anodes. For anode production, the entire dry aggregate is modified. The additive was mixed with the dry aggregate using two different approaches (one day earlier and 5 min before mixing). The anodes were characterized before and after baking. The early treatment with the additive was found to be better for the modification of dry aggregate.