An investigation into the sustainable design of green roofs in relation to their hydrological performance

It became paramount for resilient cities to mitigate negative effects of climate change such as extreme weather, heat waves or flooding. Implementation of green roofs in urban regions could help to improve local microclimate through evapotranspirationfrom green roof surfaces and vegetation, and mitigate flood risk by providing additional storage for stormwater surface runoff. This research investigates the sustainable design of green roofs using conventional and alternative materials, in relation to their hydrological performance under UK climatic conditions. The assessment of the hydrological performance of green roofs was performed by means of laboratory-based and in-situ experiments. This research has identified and selected the alternative materials, suitable for the use in extensive green roof systems. Subsequently, the properties of these materials were assessed using appropriate British Standards, showing that properties-based, as opposed to type-based, selection of the materials is of high importance to the sustainable green roof design. The in-situ experiment demonstrated high retention performance across eight green roof designs with median retention above 99% and cumulative retention for the entire monitoring period of 4 years ranging from 61.5% to 77.9%. The highest retention was recorded for the green roof design of the deepest substrate (100mm) and drainage layer (40mm). Green roofs investigated in the laboratory under extreme rainfall events demonstrated much lower hydrological performance (6% - 11.5% of median retention) than these assessed insitu. However, their maximum retention capacity ranged from 61% to 78%, given specific conditions such as long inter-event dry period prior to the extreme rainfalls. The green roofs made of alternative materials performed as well as or better than the conventional green roofs in regards to retention. The preliminary multiple linear regression models confirmed the significance of the rainfall depth and temperature in predicting runoff depth and retention as well as porosity of the substrate material and water absorption of drainage layer material. These models could be the basis for further development of tools for accurate prediction of green roof responses to rainfall events in order to assist green roof designers, standardisation bodies, specifiers, manufacturers, and contractors

Forcing Adsorption of a Tethered Polymer by Pulling

We present an analysis of a partially directed walk model of a polymer which at one end is tethered to a sticky surface and at the other end is subjected to a pulling force at fixed angle away from the point of tethering. Using the kernel method, we derive the full generating function for this model in two and three dimensions and obtain the respective phase diagrams. We observe adsorbed and desorbed phases with a thermodynamic phase transition in between. In the absence of a pulling force this model has a second-order thermal desorption transition which merely gets shifted by the presence of a lateral pulling force. On the other hand, if the pulling force contains a non-zero vertical component this transition becomes first-order. Strikingly, we find that if the angle between the pulling force and the surface is beneath a critical value, a sufficiently strong force will induce polymer adsorption, no matter how large the temperature of the system. Our findings are similar in two and three dimensions, an additional feature in three dimensions being the occurrence of a reentrance transition at constant pulling force for small temperature, which has been observed previously for this model in the presence of pure vertical pulling. Interestingly, the reentrance phenomenon vanishes under certain pulling angles, with details depending on how the three-dimensional polymer is modeled

IUPAC-NIST solubility data series. 81. Hydrocarbons with water and seawater - Revised and updated. Part 8. C9 hydrocarbons with water

The mutual solubility and related liquid-liquid equilibria of C9 hydrocarbons with water are exhaustively and critically reviewed. Reports of the experimental determination of solubility in 18 chemically distinct binary systems that appeared in the primary literature prior to the end of 2002 are compiled. For 8 systems, sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction, as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Date Series, a new method based on the evaluation of the all experimental data for a given homologous series of aliphatic and aromatic hydrocarbons was used

IUPAC-NIST solubility data series. 81. Hydrocarbons with water and seawater-revised and updated. Part 5. C7 hydrocarbons with water and heavy water

The mutual solubility and related liquid-liquid equilibria of C7 hydrocarbons with water and heavy water are exhaustively and critically reviewed. Reports of experimental determination of solubility in 23 chemically distinct binary systems that appeared in the primary literature prior to end of 2002 are compiled. For 9 systems sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a new method based on the evaluation of the all experimental data for a given homologous series of aliphatic and aromatic hydrocarbons was used

Geometrical Properties of Two-Dimensional Interacting Self-Avoiding Walks at the Theta-Point

We perform a Monte Carlo simulation of two-dimensional N-step interacting self-avoiding walks at the theta point, with lengths up to N=3200. We compute the critical exponents, verifying the Coulomb-gas predictions, the theta-point temperature T_theta = 1.4986(11), and several invariant size ratios. Then, we focus on the geometrical features of the walks, computing the instantaneous shape ratios, the average asphericity, and the end-to-end distribution function. For the latter quantity, we verify in detail the theoretical predictions for its small- and large-distance behavior.Comment: 23 pages, 4 figure

Oxysterols Increase Inflammation, Lipid Marker Levels and Reflect Accelerated Endothelial Dysfunction in Experimental Animals

Objective. Oxidized cholesterol derivatives are thought to exert atherogenic effect thus adversely affecting vascular endothelium. The aim of the study was to assess the effect of 5α,6α-epoxycholesterol on experimentally induced hypercholesterolemia in rabbits, and the levels of homocysteine (HCY), asymmetric dimethylarginine (ADMA), paraoxonase-1 (PON-1), and inflammatory parameters (IL-6, TNF-α, CRP). Material and methods. The rabbits were divided into 3 groups, 8 animals each, and fed with basic fodder (C), basic fodder plus cholesterol (Ch) or basic fodder plus 5α,6α-epoxycholesterol, and unoxidized cholesterol (ECh). Serum concentrations of studied parameters were determined at 45-day intervals. The study was continued for six months. Results. We demonstrated that adding 5α,6α-epoxycholesterol to basic fodder significantly affected lipid status of the experimental animals, increasing total cholesterol and LDL cholesterol levels, as well as HCY and ADMA levels, whilst leaving the PON-1 activity unaffected. Additionally, the ECh group presented with significantly higher concentrations of inflammatory biomarkers (IL-6, TNF-α, and CRP). In the Ch group, lower yet significant (as compared to the C group) changes of levels of studied parameters were observed. Conclusion. Exposure of animals with experimentally induced hypercholesterolemia to 5α,6α-epoxycholesterol increases dyslipidaemia, endothelial dysfunction, and inflammatory response

5α,6α-Epoxyphytosterols and 5α,6α-Epoxycholesterol Increase Oxidative Stress in Rats on Low-Cholesterol Diet

Objective. Cholesterol oxidation products have an established proatherogenic and cytotoxic effect. An increased exposure to these substances may be associated with the development of atherosclerosis and cancers. Relatively little, though, is known about the effect of phytosterol oxidation products, although phytosterols are present in commonly available and industrial food products. Thus, the aim of the research was to assess the effect of 5α,6α-epoxyphytosterols, which are important phytosterol oxidation products, on redox state in rats. Material and Methods. The animals were divided into 3 groups and exposed to nutritional sterols by receiving feed containing 5α,6α-epoxyphytosterols (ES group) and 5α,6α-epoxycholesterol (Ech group) or sterol-free feed (C group). The levels of malondialdehyde (MDA), conjugated dienes (CD), and ferric reducing antioxidant potential (FRAP) were assayed in the plasma; anti-7-ketocholesterol antibodies and activity of paraoxonase-1 (PON1) were determined in serum, whereas the activity of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), S-glutathione transferase (GST), and superoxide dismutase (SOD) were assayed in RBCs. Results. During the experiment, the levels of lipid peroxidation products increased, such as CD and anti-7-ketocholesterol antibodies. At the same time, the plasma levels of FRAP and serum activity of PON1 decreased alongside the reduced activity of GPx, GR, and SOD in RBCs. There was no effect of the studied compounds on the plasma MDA levels or on the activity of CAT and GST in RBCs. Conclusions. Both 5α,6α- epoxyphytosterols and 5α,6α-epoxycholesterols similarly dysregulate the redox state in experimental animal model and may significantly impact atherogenesis

5α,6α-Epoxyphytosterols and 5α,6α-Epoxycholesterol Increase Nitrosative Stress and Inflammatory Cytokine Production in Rats on Low-Cholesterol Diet

Objective. Oxidized cholesterol derivatives are compounds with proven atherogenic and mutagenic effects. However, little is known about the effect of oxidized plant sterol derivatives (oxyphytosterols), whose structure is similar to the one of oxycholesterols. Our previous studies indicate that they have a similar profile of action, e.g., both exacerbate disorder of lipid metabolism and oxidative stress in experimental animals. The aim of the present study was to assess the effect of epoxycholesterol and epoxyphytosterols (mainly sitosterol) on the severity of nitrosative stress and the concentration of selected proinflammatory cytokines in blood and liver tissue of rats on a low-cholesterol diet. Material and Methods. Forty-five male Wistar rats were fed with feed containing 5α,6α-epoxyphytosterols (ES group, n: 15), 5α,6α-epoxycholesterol (ECh group, n: 15), and oxysterol-free feed (C group, n: 15) for 90 days (daily dose of oxysterols: 10 mg/kg). At the end of the experiment, nitrotyrosine, TNF-α, IL-1β, IL-6, and lipid metabolism parameters were determined in blood serum. Furthermore, nitrotyrosine, TNF-α, cholesterol, and triglyceride content were determined in liver homogenates. Results. Serum nitrotyrosine, IL-1β, and TNF-α concentrations as well as TNF-α content in the liver were significantly higher in both groups exposed to oxysterols (ECh and ES groups) as compared to the C group. The serum IL-6 level and nitrotyrosine content in the liver were significantly higher in the ECh group, as compared to the C and ES groups. There was evidence to support the dyslipidemic effect of studied compounds. Conclusions. The results indicate that oxidized plant sterols have a similar toxicity profile to that of oxycholesterols, including nitrosative stress induction, proinflammatory effect, and impaired lipid metabolism

Winding angle distributions for two-dimensional collapsing polymers

9 pages, 5 figures, (this version: email address corrected

Exact solution of a model of a vesicle attached to a wall subject to mechanical deformation

Area-weighted Dyck-paths are a two-dimensional model for vesicles attached to a wall. We model the mechanical response of a vesicle to a pulling force by extending this model. We obtain an exact solution using two different approaches, leading to a q-deformation of an algebraic functional equation, and a q-deformation of a linear functional equation with a catalytic variable, respectively. While the non-deformed linear functional equation is solved by substitution of special values of the catalytic variable (the so-called "kernel method"), the q-deformed case is solved by iterative substitution of the catalytic variable. Our model shows a non-trivial phase transition when a pulling force is applied. As soon as the area is weighted with non-unity weight, this transition vanishes.Comment: extended revision, 12 pages, 6 figure