Radon and moisture impacts from interventions integrated with housing energy retrofits

Energy retrofits can reduce air exchange, raising the concern of whether indoor radon and moisture levels could increase. This pre/post-intervention study explored whether simple radon interventions implemented in conjunction with energy retrofits can prevent increases in radon and moisture levels. Treatment homes (n = 98) were matched with control (no energy retrofits or radon intervention) homes (n = 12). Control homes were matched by geographic location and foundation type. t-tests were used to determine whether post-energy retrofit radon and moisture level changes in treatment homes significantly differed from those in control homes. The radon interventions succeeded in preventing statistically significant increases in first floor radon using arithmetic (p = 0.749) and geometric means (p = 0.120). In basements, arithmetic (p = 0.060) and geometric (p = 0.092) mean radon levels statistically significantly increased, consistent with previous studies which found that basement radon levels may increase even if first floor levels remain unchanged. Changes in infiltration were related to changes in radon (p = 0.057 in basements; p = 0.066 on first floors). Only 58% of the change in infiltration was due to air sealing, with the rest due to weather changes. There was no statistically significant association between air sealing itself and radon levels on the first floor (p = 0.664). Moisture levels also did not significantly increase.     

Mixed-Metal MOF-74 Templated Catalysts for Efficient Carbon Dioxide Capture and Methanation

The vast chemical and structural tunability of metal–organic frameworks (MOFs) are beginning to be harnessed as functional supports for catalytic nanoparticles spanning a range of applications. However, a lack of straightforward methods for producing nanoparticle-encapsulated MOFs as efficient heterogeneous catalysts limits their usage. Herein, a mixed-metal MOF, NiMg-MOF-74, is utilized as a template to disperse small Ni nanoclusters throughout the parent MOF. By exploiting the difference in Ni O and Mg O coordination bond strength, Ni²⁺ is selectively reduced to form highly dispersed Ni nanoclusters constrained by the parent MOF pore diameter, while Mg²⁺ remains coordinated in the framework. By varying the ratio of Ni to Mg in the parent MOF, accessible surface area and crystallinity can be tuned upon thermal treatment, influencing CO₂ adsorption capacity and hydrogenation selectivity. The resulting Ni nanoclusters prove to be an active catalyst for CO₂ methanation and are examined using extended X-ray absorption fine structure and X-ray photoelectron spectroscopy. By preserving a segment of the Mg²⁺-containing MOF framework, the composite system retains a portion of its CO₂ adsorption capacity while continuing to deliver catalytic activity. The approach is thus critical for designing materials that can bridge the gap between carbon capture and CO₂ utilization.     

Interconnectivity and permeability of supercritical fluid-foamed scaffolds and the effect of their structural properties on cell distribution

This study aims to investigate interconnectivity and permeability of scCO₂-foamed scaffolds and the influence of structural scaffold properties on cell distribution. Supercritical fluid technology was utilized to fabricated scaffolds from 37 kDa, 53 kDa and 109 kDa PLGA (85:15). Pore size, pore size distribution and porosity were quantified by MicroCT, and window sizes were measured using SEM. A novel interconnectivity algorithm allowed the quantification of scaffold interconnectivity in three space dimensions. To determine the permeability of porous materials direct perfusion experiments were performed, where a known flow rate was applied to measure the pressure differential across the scaffolds. The permeability was calculated using Darcy's law. Largest pore sizes, porosities, interconnectivities and permeabilities were obtained for scaffolds fabricated from 37 kDa PLGA. These scaffolds showed a heterogeneous pore structure and distribution, whereas homogeneous pore structure, smallest pore sizes, porosities, interconnectivities and permeabilities were observed for scaffolds fabricated from 109 kDa PLGA. The distribution of 3T3 fibroblasts through scCO₂-foamed scaffolds was investigated by MicroCT and MTT staining. Cells were further visualized by fluorescent imaging. Uniform cell distribution was observed on scaffolds fabricated from 109 kDa PLGA and an average of 10% of the total scaffold volume was covered with cells that had adhered onto them.     

Effects of porosity,dry unit weight,cement content and void/cement ratio on unconfined compressive strength of roof tile waste-silty soil mixtures

One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity (η), dry unit weight (γ_d) of molding, cement content (C) and porosity/volumetric cement content ratio (η/C_iv) or void/cement ratio on the unconfined compressive strength (q_u or UCS) of silty soil–roof tile waste (RT) mixtures. Soil samples are molded into four different dry unit weights (i.e. 13 kN/m³, 13.67 kN/m³, 14.33 kN/m³ and 15 kN/m³) using 3%, 6% and 9% cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT–soil mixtures increases in a linear manner. On the other hand, the addition of RT decreases q_u of the samples at a constant percentage of cement, and the decrease in porosity can increase q_u. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio (η/C_iv) where the control variables are the moisture content, crushed tile content, cement content and porosity.     

Waterborne rotavirus: A risk assessment

A risk assessment approach was used to estimate the public health impacts from exposure to human rotavirus in drinking and recreational waters. Rotavirus is the major cause of viral gastroenteritis worldwide and several waterborne outbreaks have been documented. This results in a significant economic impact on society in terms of direct medical costs, loss of work, quality of life and mortality. The virus is common in domestic wastewater and polluted surface waters. Dose-response data in human adult volunteers indicate that it is the most infective of all the enteric viruses, and this was used to develop a microbial risk assessment model to estimate daily and yearly risks of infection, morbidity and mortality for exposure via drinking and recreational waters using existing information on the occurrence of rotavirus. The disease is most severe for the very young, the elderly, and the immunocompromised. Case fatality rates in the United States are 0.01% in the general population, 1% in the elderly, and up to 50% in the immunocompromised. Analysis indicates that significant risks of disease (5 × 10⁻¹−2.45 × 10⁻³) could result for drinking and recreational waters in which rotavirus has been detected. The major limitation in assessing the risks of waterborne rotaviral infections at present is the lack of data on its occurrence in water and the potential for human exposure.     

Managing conservation: the case of the small town

This viewpoint is based around the Council of Europe International Conference on Managing Conservation — The Case of the Small Town, held in Brittany, France in June 1986. The more important questions raised at the conference are discussed, with photographic examples of some of the outstanding restoration carried out in Brittany's historic towns.     

Reviews

READING LANDSCAPE; COUNTRY-CITY-CAPITAL, Simon Pugh, ed., Manchester : Manchester University Press, 1990, pp. 245, £35.00 HB, £9.95 PB, ISBN 0-7190-2979-1, 0-7190-3189-3.

ENVISIONING INFORMATION

by Edward R. Tufte, Cheshire, Connecticut, The Graphics Press, 1990, £30.00.

THE MAKING OF THE AMERICAN LANDSCAPE, Michael P. Conzen, ed., Boston and London: Unwin Hyman, 1990. pp. xvi + 434. ISBN 0-04-917010-4. £14.95 PB.

THE EFFECTS OF THE GREAT STORM: REPORT OF A TECHNICAL COORDINATION COMMITTEE AND THE GOVERNMENT'S RESPONSE, London: HMSO, 1988, 43pp, £5.00, P.B., ISBN 011 752144 2.

THE 1987 STORM: IMPACTS AND RESPONSES, A. J. Grayson (ed.), London: HMSO, 1989, 46pp, £4.00, P.B., ISBN 011 752144 2.

VIEWS OF AMERICAN LANDSCAPES, edited by Mick Gidley and Robert Lawson-Peebles, Cambridge: Cambridge University Press, 1989, £27.50; $39.50, H.B., 228pp.

TAMING THE FLOOD: A HISTORY AND NATURAL HISTORY OF RIVERS AND WETLANDS by Jeremy Purseglove, Oxford: Oxford University Press in association with Channel 4, 1989, 291pp, ISBN 0 19 286091 7, £9.95, P.B.

THE ITALIAN RENAISSANCE GARDEN FROM THE CONVENTIONS OF PLANTING, DESIGN, AND ORNAMENT TO THE GRAND GARDENS OF SIXTEENTH-CENTURY CENTRAL ITALY, Claudia Lazzaro with photographs by Ralph Lieberman, New Haven and London, Yale University Press, 1990, pp. i-ix + 342, £45.00, $65.00, ISBN 0-300-4765-7.

LANDSCAPE OR LAND?, poems for Devon, Mark Beeson and Christopher Southgate, Wheal Press, Devon, ISBN 0-9511588-1-3.     

Escherichia coli, enterococci, and Bacteroides thetaiotaomicron qPCR signals through wastewater and septage treatment

Fecal indicators such as Escherichia coli and enterococci are used as regulatory tools to monitor water with 24 h cultivation techniques for possible input of sewage or feces and presence of potential enteric pathogens yet their source (human or animal) cannot be determined with routine methods. This critical uncertainty has furthered water pollution science toward new molecular approaches. Members of Bacteroides genus, such as Bacteroides thetaiotaomicron are found to have features that allow their use as alternative fecal indicators and for Microbial Source Tracking (MST). The overall aim of this study was to evaluate the concentration and fate of B. thetaiotaomicron, throughout a wastewater treatment facility and septage treatment facility. A large number of samples were collected and tested for E. coli and enterococci by both cultivation and qPCR assays. B. thetaiotaomicron qPCR equivalent cells (mean: 1.8 × 10⁷/100 mL) were present in significantly higher concentrations than E. coli or enterococci in raw sewage and at the same levels in raw septage. The removal of B. thetaiotaomicron target qPCR signals was similar to E. coli and enterococci DNA during the treatment of these wastes and ranged from 3 to 5 log₁₀ for wastewater and was 7 log₁₀ for the septage. A significant correlation was found between B. thetaiotaomicron marker and each of the conventional indicators throughout the waste treatment process for both raw sewage and septage. A greater variability was found with enterococci when compared to E. coli, and CFU and equivalent cells could be contrasted by various treatment processes to examine removal and inactivation via septage and wastewater treatment. These results are compared and contrasted with other qPCR studies and other targets in wastewater samples providing a view of DNA targets in such environments.