Novel non intrusive continuous use ZeBox technology to trap and kill airborne microbes.

Preventing nosocomial infection is a major unmet need of our times. Existing air decontamination technologies suffer from demerits such as toxicity of exposure, species specificity, noxious gas emission, environment-dependent performance and high power consumption. Here, we present a novel technology called "ZeBox" that transcends the conventional limitations and achieves high microbicidal efficiency. In ZeBox, a non-ionizing electric field extracts naturally charged microbes from flowing air and deposits them on engineered microbicidal surfaces. The surface's three dimensional topography traps the microbes long enough for them to be inactivated. The electric field and chemical surfaces synergistically achieve rapid inactivation of a broad spectrum of microbes. ZeBox achieved near complete kill of airborne microbes in challenge tests (5-9 log reduction) and [Formula: see text] efficiency in a fully functional stem cell research facility in the presence of humans. Thus, ZeBox fulfills the dire need for a real-time, continuous, safe, trap-and-kill air decontamination technology.

Shear stress rosettes capture the complex flow physics in diseased arteries.

Wall shear stress (WSS) is an important parameter in arterial mechanobiology. Various flow metrics, such as time averaged WSS (TAWSS), oscillatory shear index (OSI), and transWSS, have been used to characterize and relate possible WSS variations in arterial diseases like aneurysms and atherosclerosis. We use a graphical representation of WSS using shear rosettes to map temporal changes in the flow dynamics during a cardiac cycle at any spatial location on the vessel surface. The presence of secondary flows and flow reversals can be interpreted directly from the shape of the shear rosette. The mean WSS is given by the rosette centroid, the OSI by the splay around the rosette origin, and the transWSS by its width. We define a new metric, anisotropy ratio (AR), based on the ratio of the length to width of the shear rosette, to capture flow bi-directionality. We characterized the flow physics in controls and patient specific geometries of the ascending aorta (AA) and internal carotid artery (ICA) that have fundamentally different flow dynamics due to differences in the Reynolds and Womersley numbers. The differences in the flow dynamics are well reflected in the shapes of the WSS rosettes and the corresponding flow metrics.

Formation of a hard surface layer during drying of a heated porous media.

We report surface hardening or crust formation, like caking, during evaporation when a porous medium was heated from above using IR radiation. These crusts had higher strength than their closest counterparts such as sandcastles and mud-peels which essentially are clusters of a partially wet porous medium. Observed higher strength of the crusts was mostly due to surface tension between the solid particles, which are connected by liquid bridges (connate water). Qualitative (FTIR) and quantitative (TGA) measurements confirmed the presence of trapped water within the crust. Based on the weight measurements, the amount of water trapped in the crusts was ~1.5%; trapped water was also seen as liquid bridges in the SEM images. Further, in the fixed particle sizes case, the crust thickness varied slightly (only 10-20 particle diameters for cases with external heating) while with the natural sand whole porous column was crusted; surprisingly, the crust was also found with the hydrophobic glass beads. Fluorescein dye visualization technique was used to determine the crust thickness. We give a power-law relation between the crust thickness and the incident heat flux for various particle sizes. The strength of the crust decreased drastically with increasing hydrophilic spheres diameter while it increased with higher surface temperature.

Intensity and angle-of-arrival spectra of laser light propagating through axially homogeneous buoyancy-driven turbulence.

Frequency spectra obtained from the measurements of light intensity and angle of arrival (AOA) of parallel laser light propagating through the axially homogeneous, axisymmetric buoyancy-driven turbulent flow at high Rayleigh numbers in a long (length-to-diameter ratio of about 10) vertical tube are reported. The flow is driven by an unstable density difference created across the tube ends using brine and fresh water. The highest Rayleigh number is about 8×109. The aim of the present work is to find whether the conventional Obukhov-Corrsin scaling or Bolgiano-Obukhov (BO) scaling is obtained for the intensity and AOA spectra in the case of light propagation in a buoyancy-driven turbulent medium. Theoretical relations for the frequency spectra of log amplitude and AOA fluctuations developed for homogeneous isotropic turbulent media are modified for the buoyancy-driven flow in the present case to obtain the asymptotic scalings for the high and low frequency ranges. For low frequencies, the spectra of intensity and vertical AOA fluctuations obtained from measurements follow BO scaling, while scaling for the spectra of horizontal AOA fluctuations shows a small departure from BO scaling.