Predicting Chicago's Land Use Pattern

The planning of community facilities requires accurate quantitative estimates of the area, type, intensity, and location of land uses required by the growth of urban activities. The distribution of these activities and the intensity of their use of land are highly related to accessibility as measured by distance from the CBD. This paper outlines a procedure whereby area-wide estimates of future population and economic activity can be distributed to small subareas so that measures of local land requirements may be obtained.     

Polychlorinated naphthalenes in air and snow in the Norwegian Arctic: a local source or an Eastern Arctic phenomenon?

PCNs were measured in air and snow during separate field campaigns at Ny-Alesund (April 2001) and Troms? (February/March 2003) in the Norwegian Arctic. Air concentrations ranged from 27 to 48 and 9 to 47 pg sigmaPCN m(-3) for Ny-Alesund (n=6) and Troms? (n=10), respectively. These concentrations (including the tri-chlorinated naphthalenes) greatly exceeded concentrations previously measured in the Canadian Arctic, but did fall within the upper range of concentrations observed over the eastern Arctic Ocean and regional seas. Local sources appear to be affecting concentrations observed at both sites, with the presence of several hexa-chlorinated naphthalenes at Troms? probably attributed to local/regional sources. Use of air mass back trajectories at Troms? revealed that background air concentrations in the Norwegian Arctic are likely to range between <9 and 20 pg sigmaPCN m(-3) and that contemporary concentrations derived close to potential sources (i.e. arctic towns) may equal or exceed those of PCBs. The mean concentration in surface snow was 350 and 240 pg sigmaPCN L(-1) (meltwater) (or 0.014 and 0.01 pg g(-1) (snow)) at Ny-Alesund and Troms?, respectively. The wide variation in concentrations observed between fresh snowfalls could be explained by different snow densities (as a surrogate of snow surface area), rather than attributed to varying air concentrations. A statistically significant inverse relationship was found between snow density and concentrations of tri- to penta-chlorinated homologues and compliments similar findings for the polychlorinated biphenyls (PCBs). This suggests that the vapour-sorbed quantity changes rapidly with snow ageing/compaction; with implications for the fate of these chemicals in the Arctic.     

Cobalt powdersintering industry (stone cutting diamond wheels): a study of environmental-biological monitoring, workplace improvement and health surveillance

This communication deals with an aspect of occupational hygiene in a factory producing granite cutting diamond wheels by sintering, in moulds, of fine cobalt powder. The factory has been studied between 1988 and 1991; the Department of Preventive and Occupational Medicine of the Local Sanitary Unit of Reggio Emilia has followed the evolution of the local exhaust ventilation equipment supplied by the employer in that period. At the same time, the following measurements and observations were carried out: (a) cobalt exposure by personal sampling, (b) airborne cobalt measurements by area sampling, (c) biological monitoring of cobalt in urine, (d) health surveillance.     

Modelling air pollution for epidemiologic research--part II: predicting temporal variation through land use regression

Over recent years land use regression (LUR) has become a frequently used method in air pollution exposure studies, as it can model intra-urban variation in pollutant concentrations at a fine spatial scale. However, very few studies have used the LUR methodology to also model the temporal variation in air pollution exposure. The aim of this study is to estimate annual mean NO₂ and PM₁₀ concentrations from 1996 to 2008 for Greater Manchester using land use regression models. The results from these models will be used in the Manchester Asthma and Allergy Study (MAAS) birth cohort to determine health effects of air pollution exposure.The Greater Manchester LUR model for 2005 was recalibrated using interpolated and adjusted NO₂ and PM₁₀ concentrations as dependent variables for 1996-2008. In addition, temporally resolved variables were available for traffic intensity and PM₁₀ emissions. To validate the resulting LUR models, they were applied to the locations of automatic monitoring stations and the estimated concentrations were compared against measured concentrations.The 2005 LUR models were successfully recalibrated, providing individual models for each year from 1996 to 2008. When applied to the monitoring stations the mean prediction error (MPE) for NO₂ concentrations for all stations and years was -0.8 μg/m³ and the root mean squared error (RMSE) was 6.7 μg/m³. For PM₁₀ concentrations the MPE was 0.8 μg/m³ and the RMSE was 3.4 μg/m³.These results indicate that it is possible to model temporal variation in air pollution through LUR with relatively small prediction errors. It is likely that most previous LUR studies did not include temporal variation, because they were based on short term monitoring campaigns and did not have historic pollution data. The advantage of this study is that it uses data from an air dispersion model, which provided concentrations for 2005 and 2010, and therefore allowed extrapolation over a longer time period.     

Bioaccumulation potential of polycyclic aromatic hydrocarbons in Daphnia pulex

The bioaccumulation potentials by aquatic biota from aqueous solution were determined for seven polycyclic aromatic hydrocarbons (PAH). The PAH were tested usingDaphnia pulex and consisted of the following compounds: naphthalene, anthracene, phenanthrene, pyrene, 9-methylanthracene, benz(a)anthracene and perylene. Bioaccumulation kinetics were described as a first order approach to equilibrium in a two-compartment model (water and Daphnia), using a two-stage technique to estimate uptake and elimination rates, while accounting for decreasing aqueous concentrations. Estimates of equilibrium concentration factors were obtained by two methods: (1) evaluating the kinetic model as t tends to infinity and (2) direct measurement of concentration factor at t =24 h.Estimations of equilibrium concentration factors obtained by the two methods were in good agreement, and increased dramatically with increasing molecular weight within the series of compounds. The calculated n-octanol-water partition coefficient was shown to be a good predictor of bioaccumulation potential of PAH in Daphnia. PAH were concentrated from a high of about 10,000-fold for benz(a)anthracene to a low of about 100-fold for naphthalene.     

Indentation deformation and cracking behavior of hydrated aluminoborate glasses

Aluminoborate glasses have recently been found to feature high resistance to crack initiation during indentation due to a highly flexible network structure. In cesium aluminoborate glasses, it has been found that the use of a simple post-treatment, namely aging in a humid atmosphere, can further improve this resistance. To better understand the mechanical properties of this glass family upon humid aging, we here study the effect of aging conditions on the structure and mechanical properties of Li,K,Cs-aluminoborate glasses. As expected, we find that higher humidity and longer aging time cause more pronounced permeation of atmospheric water into the glasses. Due to their denser structure and stronger modifier-oxygen bonds, the humid aging has a relatively smaller effect on the mechanical properties of Li- and K-containing glasses relative to Cs-containing glasses, with the latter achieving an ultrahigh crack resistance. We find that the humid aging leads to the formation of a hydration layer in the Cs-aluminoborate glass surface, with a thickness of around 26 μm upon aging at 23 °C with 40% relative humidity for 7 days. Moreover, a remarkable indentation behavior, that is, the observation of μm-sized shear bands inside the imprint of the Cs-glass upon aging at 60% relative humidity is reported. Taken as a whole, the work provides guidelines for how to control the humid aging rate as a function of relative humidity and temperature to form a hydration layer and thus achieve improved crack resistance in such glasses.     

Multilayer Glass Quality Improvement during Production

Glass and Ceramics - Selective quality control of manufactured multilayer windshields was conducted. Deviations of curved products from a specified shape were brought to light. Linear regression...     

Tribological Characteristics of Aqueous Graphene Oxide,Graphitic Carbon Nitride,and Their Mixed Suspensions

The tribological performance of graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and their mixed (g-C₃N₄/GO) aqueous suspensions was investigated. The 0.06 wt% GO, 0.06 wt% g-C₃N₄, and 0.06 wt% 1:1 g-C₃N₄/GO suspensions reduced the coefficient of friction (COF) by 37, 26 and 37% and wear mark radius by 19.1, 16.0 and 19.6%, respectively, in comparison with water. Pure g-C₃N₄ and GO suspensions showed unstable lubrication in the tests with relatively high loads and speeds, while the g-C₃N₄/GO mixed suspension had superior tribological performance in all tested conditions. This is because in the mixed suspension g-C₃N₄ agglomerates became smaller, and GO nanosheets exhibited fewer wrinkles and less stacking, which enabled the formation of a layer of tribo-composite film. As a result, the friction, wear and tribo-corrosion were reduced during sliding.