Correlating chemistry and mass transport in sustainable iron production.

Steelmaking contributes 8% to the total CO2 emissions globally, primarily due to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable performance because the dominant gas-solid reduction mechanism is set by the defects and pores inside the mm- to nm-sized oxide particles that change significantly as the reaction progresses. While these governing dynamics are essential to establish continuous flow of iron and its ores through reactors, the direct link between agglomeration and chemistry is still contested due to missing measurements. In this work, we directly measure the connection between chemistry and agglomeration in the smallest iron oxides relevant to magnetite ores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we resolve the formation and consumption of wüstite (Fe1-xO)-the step most commonly attributed to whiskering. Using X-ray diffraction, we resolve crystallographic anisotropy in the rate of the initial reaction. Complementary imaging demonstrated how the particles self-assemble, subsequently react, and grow into elongated "whisker" structures. Our insights into how morphologically uniform iron oxide particles react and agglomerate in H2 reduction enable future size-dependent models to effectively describe the multiscale aspects of iron ore reduction.

A portable rotating disc as blood rheometer.

Abnormalities in biophysical properties of blood are often strong indicators of life threatening infections. However, there is no existing device that integrates the sensing of blood hematocrit (or equivalently, packed cell volume), viscosity, and erythrocyte sedimentation rate (ESR) in a unified paradigm for point-of-care diagnostics. In an effort to develop a rapid, integrated, accurate, portable, and inexpensive sensing platform to diagnose the corresponding pathophysical parameters, we develop a simple and portable spinning disk capable of yielding these results in a few minutes instead of the traditional duration of hours. The device requires only 40 µl of unprocessed freshly drawn blood treated with an anticoagulant ethylenediaminetetraacetic acid, instead of the traditional requirement of 2 ml of blood for just the ESR measurement and still more for hematocrit determination. In contrast to the sophisticated instrumentation required to determine these parameters by the previously proposed microfluidic devices, our device requires minimal infrastructure. The measurement of hematocrit is accomplished by means of a simple 15 cm ruler. Additionally, a simple measurement of the blood flow rate enables the determination of the ESR value. The rapidity, ease, accuracy, portability, frugality, and possible automation of the overall measurement process of some of the most important parameters of blood under infection pinpoint its utility in extreme point-of-care settings.