Quantification and Visualization of Fungal Degradation of Polyurethane Foam in Homes

People spend 90% of their time in the indoor environment including homes. Homes contain many exposures that can cause harm to human health, and one harmful exposure potentially comes from the degradation of polyurethanes. This deterioration of the polymer causes the release of a carcinogenic compound called 2,4-diaminotoluene (2,4-DAT). Polyurethane foam is a common household material and is used to make many items such as mattresses, couches, insulation, and carpet backing. It is uncertain if growth of fungi on this foam can cause biodegradation to occur, which could potentially result in the release of 2,4-DAT. The goal of this study is to better understand under what conditions one common fungal species, Aureobasidium pullulans, degrades polyurethane foam. We tested the effects of nutrient availability, foam age, and relative humidity levels on the ability of Aureobasidium pullulans to degrade polyurethane foam. The effects of nutrient availability on fungal degradation were evaluated by incubating polyurethane foam with different agars and comparing weight loss of foam samples as a result. The effects of foam age were tested by obtaining 2 foam types; one new and one already used in a home and incubating them to compare weight loss as a result. The effects of relative humidity (RH) on fungal degradation of foam were evaluated by incubating foam at varying equilibrium relative humidity (ERH) levels and performing quantitative polymerase chain reaction (qPCR) to quantify fungal growth. Polyurethane foam incubated with Aureobasidium pullulans was observed under a scanning electron microscope (SEM) in order to visually observe the growth of fungi on polyurethane foam. The ideal conditions for fungal degradation were foam type 1 with an additional carbon source and high RH level. The peak weight loss of foam from fungal degradation was found to be 56% and fungal growth was highest at 100% ERH. Spore chains and fruiting bodies were observed via microscopy wrapped around the foam after incubation indicating Aureobasidium pullulans can grow and reproduce on polyurethane foam given appropriate conditions. This information can be used in the future to prevent fungal degradation of polyurethane foam and potentially decrease carcinogen exposure.OSU OUR&CI Undergraduate Research Apprenticeship ProgramOSU College of Engineering Research Distinction ScholarshipNo embargoAcademic Major: Environmental Engineerin

Foam used during EPB tunnelling in saturated sand, parameters determining foam consumption

The amount of foam injected during drilling with an EPB-shield in saturated sand is quite often based on experience and/or empiric relations. A method is presented in to calculate the amount of foam needed to create a muck with limited or no grain stress. The results show that, as expected, the volume of the foam to be injected is much larger in dry soil compared to saturated soil. In saturated soil the amount of foam to be injected depends on various parameters. The permeability of the soil in front of the EPB-shield appears very important. This paper describes the dependencies and shows that recommended foam injection ratio’s from literature may be too small when used in permeable sandy soil. The FIR of the foam in a mixture may be much smaller than of the original foam

Identification and quantification of cell gas evolution in rigid polyurethane foams by novel GCMS methodology

Producción CientíficaThis paper presents a new methodology based on gas chromatography-mass spectrometry (GCMS) in order to separate and quantify the gases presented inside the cells of rigid polyurethane (RPU) foams. To demonstrate this novel methodology, the gas composition along more than three years of aging is herein determined for two samples: a reference foam and foam with 1.5 wt% of talc. The GCMS method was applied, on one hand, for the accurate determination of C5H10 and CO2 cell gases used as blowing agents and, on the other hand, for N2 and O2 air gases that diffuse rapidly from the surrounding environment into foam cells. GCMS results showed that CO2 leaves foam after 2.5 month (from 21% to 0.03% for reference foam and from 17% to 0.03% for foam with 1.5% talc). C5H10 deviates during 3.5 months (from 28% up to 39% for reference foam and from 29% up to 36% for foam with talc), then it starts to leave the foam and after 3.5 year its content is 13% for reference and 10% for foam with talc. Air diffuses inside the cells faster for one year (from 51% up to 79% for reference and from 54% up to 81% for foam with talc) and then more slowly for 3.5 years (reaching 86% for reference and 90% for foam with talc). Thus, the fast and simple presented methodology provides valuable information to understand the long-term thermal conductivity of the RPU foams.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (grants MAT2015-69234-R and RTC-2016-5285-5)Junta de Castilla y Leon (grant VA275P18)Agencia austriaca para la promoción de la investigación (grant 850697

The Feynman propagator for quantum gravity: spin foams, proper time, orientation, causality and timeless-ordering

We discuss the notion of causality in Quantum Gravity in the context of sum-over-histories approaches, in the absence therefore of any background time parameter. In the spin foam formulation of Quantum Gravity, we identify the appropriate causal structure in the orientation of the spin foam 2-complex and the data that characterize it; we construct a generalised version of spin foam models introducing an extra variable with the interpretation of proper time and show that different ranges of integration for this proper time give two separate classes of spin foam models: one corresponds to the spin foam models currently studied, that are independent of the underlying orientation/causal structure and are therefore interpreted as a-causal transition amplitudes; the second corresponds to a general definition of causal or orientation dependent spin foam models, interpreted as causal transition amplitudes or as the Quantum Gravity analogue of the Feynman propagator of field theory, implying a notion of ''timeless ordering''.Comment: 8 pages; to appear in the Proceedings of the DICE 2004 Workshop "From Decoherence and Emergent Classicality to Emergent Quantum Mechanics

4-dimensional Spin-foam Model with Quantum Lorentz Group

We study the quantum group deformation of the Lorentzian EPRL spin-foam model. The construction uses the harmonic analysis on the quantum Lorentz group. We show that the quantum group spin-foam model so defined is free of the infra-red divergence, thus gives a finite partition function on a fixed triangulation. We expect this quantum group spin-foam model is a spin-foam quantization of discrete gravity with a cosmological constant.Comment: 23 pages, 3 figures, references adde

Glass foam granulate as growing medium for tomato and cucumber

Glass foam granulate was evaluated for use as a horticultural rooting medium with laboratory tests and cultivation experiments. The laboratory tests included moisture characteristics, rehydration rate and pH buffering analyses. Cucumbers and later on tomatoes were propagated in rockwool propagation cubes and planted on slabs of Growstones™ glass foam granulate. They were compared with cucumber respectively tomatoes grown on rockwool slabs. Lab results show that the coarse nature of the glass foam granulate (0.5-5 cm) limits the maximum moisture content to 50%. The rehydration rate is very high, reaching more than 80% of container capacity in 5 min. The tested material initially reacts with water, raising the pH to over 10 pH units. Based on lab results a recipe for rinsing the material prior to cultivation was calculated. Cucumber cultivation results show an equal production to plants grown on rockwool. The first yield on glass foam granulate is 1-2 days earlier. The susceptibility to Pythium is significantly lower than on rockwool. The wax layer on cucumbers grown on glass foam granulate is perceptibly thicker as consequence of an elevated silicon level of 0.25 to 1.6 mmol L-1 in the slab solution. Tomatoes on glass foam granulate show smaller stem diameters and recovered faster from blossom end rot. Yield levels on glass foam granulate and rockwool are equal. In conclusion growing on glass foam granulate is equally productive as rockwool growing. The material is drier and thus less susceptible to Pythium and more generative in nature. Glass foam granulate can be irrigated with small and frequent irrigation cycles and the material must be rinsed with an acid solution before planting. Small amounts of silicon are released into the nutrient solution

Absorption and rheological phenomena during foam application on textiles

A simple rheological model has been used to describe foam flow through moving textile assemblies. The validity of this model was tested, and the nature and the relative magnitude of deviations from the model evaluated for several different substrates. Neglecting foam degeneration during transport, the model was found to represent a valuable means of evaluating some rheological and geometrical deviations. The model can be used in a semi-quantitative way to describe absorbency during foam application. Liquid absorption experiments done off-line, absorption during foam application and some earlier results could be described using different theoretical approaches. Some rheological anomalies have been discussed