Investigation on the Effect of Sulfur and Titanium on the Microstructure of Lamellar Graphite Iron

The goal of this work was to identify the inclusions in lamellar graphite cast iron in an effort to explain the nucleation of the phases of interest. Four samples of approximately the same carbon equivalent but different levels of sulfur and titanium were studied. The Ti/S ratios were from 0.15 to 29.2 and the Mn/S ratios from 4.2 to 48.3. Light and electron microscopy were used to examine the unetched, color-etched, and deep-etched samples. It was confirmed that in irons with high sulfur content (0.12 wt pct) nucleation of type-A and type-D graphite occurs on Mn sulfides that have a core of complex Al, Ca, Mg oxide. An increased titanium level of 0.35 pct produced superfine interdendritic graphite (~10 μm) at low (0.012 wt pct) as well as at high-S contents. Ti also caused increased segregation in the microstructure of the analyzed irons and larger eutectic grains (cells). TiC did not appear to be a nucleation site for the primary austenite as it was found mostly at the periphery of the secondary arms of the austenite, in the last region to solidify. The effect of titanium in refining the graphite and increasing the austenite fraction can be explained through the widening of the liquidus-eutectic temperature interval (more time for austenite growth) and the decrease in the growth rate of the graphite because of Ti absorption on the graphite. The fact that Ti addition produced larger eutectic cells supports the theory that Ti is not producing finer graphite because of a change in the nucleation potential, but because of lower growth rate of the graphite in between the dendrite arms of a larger fraction of austenite. In the presence of high-Ti and S, (MnTi)S star-like and rib-like inclusions precipitate and act as nuclei for the austenite.     

Mid‐infrared spectroscopy and multivariate curve resolution for analyzing human adipose tissue triacylglycerols

The aim of this study was to evaluate use of infrared spectroscopy for measuring adipose tissue triacylglycerols (TAGs) with analysis by multivariate curve resolution (MCR). The mid‐infrared spectrum was measured with an attenuated total reflection accessory from a lipid droplet pressed from adipose tissue. The obtained spectra were characteristic of pure TAG spectra and water and protein contamination could be easily identified from specific spectral regions. MCR analysis of the olefinic (?C? H) stretch (3006 cm^?1), resolved the different contributions of monounsaturated (MUFA) and polyunsaturated (PUFA) double bonds. Similar MCR analysis of the trans (HC?CH? ) region (966 cm^?1), resolved the differing contributions of isolated trans isomers (transFA) and CLA. The PUFA double bond content of 16 subjects was negatively correlated with concentrations of serum total cholesterol R = ?0.498 (p = 0.050) and triacylglycerols R = ?0.609, (p = 0.016). The transFA content exhibited a negative, although non‐significant, correlation to high‐density lipoprotein (HDL)‐cholesterol (R = ?0.483, p = 0.068). The present study shows that MCR analysis of adipose tissue TAG infrared spectra can be used to estimate differences in the fatty acid (FA) profiles in population studies. Infrared spectroscopy in combination with MCR provides a robust method for assessing a FA profile of human adipose tissue. Practical applications: This study has highlighted the use of MCR to enhance the information obtained from infrared spectra. This new approach provides a robust method for assessing a FA profile of human adipose tissue lipids.     

A 14-bit dual-path 2-0 MASH ADC with dual digital error correction

A dual-path 2-0 cascaded delta-sigma (MASH) ADC was implemented with fast digital correction of both DAC errors and MASH mismatch errors. The digital correction techniques greatly reduced the requirements on the analog circuits. The dual-path structure allows fast convergence and improved accuracy for the correction. Using a 20 MHz clock, the prototype chip achieved an 84 dB dynamic range in a 1.25 MHz signal band, when fabricated in CMOS 0.18 μm process.     

Study of interaction between croscarmellose and escitalopram during sample preparation

During routine analysis of an escitalopram tablet formulation, it was seen that there was a systematic deviation between content uniformity (CU - one tablet analysis) and assay analysis (ten pooled tablets). In the presence of the excipients from the tablet, it was found that the extraction of the active pharmaceutical ingredient (API) was incomplete. It was shown that the commonly used tablet disintegrant croscarmellose sodium (crosslinked carboxy-methyl cellulose) had a significant interaction with escitalopram. This was later found to be the explanation for the lower extraction during assay testing. Under normal conditions, the extraction took place in acidic medium which caused protonation of the amine and thereby the interaction of charged species in solution. The interaction of API was studied further with pure croscarmellose and the entire tablet matrix. A range of conditions was considered, including altering extraction volumes, organic solvents, pH of the extraction solvent, and addition of competitive binder in various concentrations. It was seen that arginine was the most effective cationic competitive binder of those tested and that adding it at a suitable concentration level could significantly improve the analytical methods. In the present case, an improvement in recovery was from 98.5% to almost 100% was achieved.     

An Electrically-Driven GaAs Nanowire Surface Plasmon Source

Over the past decade, the properties of plasmonic waveguides have extensively been studied as key elements in important applications that include biosensors, optical communication systems, quantum plasmonics, plasmonic logic, and quantum-cascade lasers. Whereas their guiding properties are by now fairly well-understood, practical implementation in chipscale systems is hampered by the lack of convenient electrical excitation schemes. Recently, a variety of surface plasmon lasers have been realized, but they have not yet been waveguide-coupled. Planar incoherent plasmonic sources have recently been coupled to plasmonic guides but routing of plasmonic signals requires coupling to linear waveguides. Here, we present an experimental demonstration of electrically driven GaAs nanowire light sources integrated with plasmonic nanostrip waveguides with a physical cross-section of 0.08λ(2). The excitation and waveguiding of surface plasmon-polaritons (SPPs) is experimentally demonstrated and analyzed with the help of full-field electromagnetic simulations. Splitting and routing of the electrically generated SPP signals around 90° bends are also shown. The realization of integrated plasmon sources greatly increases the applicability range of plasmonic waveguides and routing elements.     

Degradation of Refractory Bricks Used as Thermal Insulation in Rotary Kilns for Iron Ore Pellet Production

Degradation of bricks in an iron ore pellet producing kiln has been investigated. Lab-scale tests of brick/slag interaction performed under different temperatures, atmospheres, and alkali additions show that addition of alkali dissolves the mullite in the brick and leads to formation of the phase nepheline (Na₂O·Al₂O₃·2SiO₂). At a high temperature, the grain boundary where nepheline is formed disintegrates due to volume expansion. At increased temperature, the nepheline transforms to an amorphous phase. Thus, a wear mechanism is proposed in the kiln using these bricks that involves these chemical reactions in combination with erosion by the continuously flowing slag.     

Mediator-Based Evolutionary Design and Development of Image Meta-Analysis Environments

We discuss how emerging object-relational database mediator technology can be used to integrate academic freeware and commercial-off-the-shelf software components to create a sequence of gradually more complex and powerful, always semantically and syntactically homogeneous, database centered Image Meta-Analysis Environments. We show how this may be done by definition and utilization of a use-case-based evolutionary design and development process. This process allows subsystems to be produced largely independently by several small specialist subprojects, turning the system integration work into a high-level domain modelling task.     

Optical fiber-based devices and applications

Optical fiber technology has undergone tremendous growth and development over the last 40 years. Optical fibers constitute an information super highway and are vital in enabling the proliferating use of the Internet. Optical fiber is also an enabling technology which can find applications in sensing, imaging, biomedical, machining, etc. There have been a few milestones in the advancement of optical fiber technology. Firstly, the invention and development of the laser some 50 years ago made optical communications possible. Secondly, the fabrication of low-loss optical fibers has been a key element to the success of optical communication.