1 Oct 2020

Comparison of Antifungal Efficiencies of Photocatalytic and Antimicrobial-Infused Coatings: Evaluation of Five Antimicrobial Coatings Using Standard Test Methods

Abstract: New buildings are being constructed and existing buildings retrofitted to be more energy efficient to meet increasingly stringent Department of Defense (DoD) energy standards. Although these standards save energy and lower operational costs, they also limit fresh air within a structure and can cause a buildup of harmful substances in indoor environments. Of particular concern are molds, which can put building occupants at risk and damage infrastructure. One possible solution to this increasing Army problem is to coat building materials with photocatalytic paints, which have the ability to both destroy microorganisms as well as the toxic byproducts they produce. This work compared two next-generation photocatalytic coatings against three more traditional antimicrobial-infused coatings for their ability to resist fungal contamination using three accelerated test conditions. Under each test condition the photocatalytic coatings were found to perform poorly compared to the antimicrobial-infused coatings. Moreover, the control coating, which contained no active antimicrobial (standard latex paint), performed as well as or better than all the antimicrobial coatings tested. This suggested that there may be little benefit to using antimicrobial coatings to inhibit fungal colonization over a standard latex paint; however, further testing is required to confirm this perception.

11 Aug 2020

PUBLICATION NOTICE: The Urban Ground-to-Ground Radio-Frequency Channel: Measurement and Modeling in the Ultrahigh Frequency Band

ABSTRACT:  Ground-to-ground radio communication and sensing within the urban environment is challenging because line of sight between transmitter and receiver is rarely available. Therefore, radio links are often critically reliant on reflection and scattering from built structures. Little is known about the scattering strength of different buildings or whether such differences are important to the urban ground-to-ground channel. We tested the hypotheses that (1) diffuse scattering from built structures significantly impacts the urban channel and (2) scattering strength of urban structures varies with surface roughness and materials.  We tested these hypotheses by measuring urban channels in Concord, New Hampshire, and Boston, Massachusetts, and via channel-modeling efforts with three-dimensional representations of the urban environment. Direct comparison between measured and modeled channels suggest that both of these hypotheses are true. Further, it appears that ray-tracing approaches underestimate the complexity of urban channels because these approaches lack the physical processes to correctly assess the power incident on and scattered from built structures. We developed a radio-geospatial model that better accounts for incident power on both directly visible and occluded buildings and show that our model predictions com-pare more favorably with measured channels than those channels predicted via typical ray-tracing approaches.