Identification of straight-chain fatty acids in coal extracts and their geochemical relation with straight-chain alkanes

Mono-carboxylic, straight-chain fatty acids are present in extracts of lignite and subbituminous coal (0.4–1.0 wt%, daf basis), but not in those of a bituminous coal. They are removed with nearly equal ease by both solvent and supercritical gas (SCG) extraction. Octacosanoic acid is the major constituent, and values of the carbon preference index (even over odd) lie between 2 and 6. Solvent extraction of the coals also removes small quantities (< 0.08 wt%) of straight-chain alkanes which are closely related in composition to the straight-chain fatty acids and are probably derived from them during maturation. However, previous SCG extraction of the coals yielded much larger quantities of straight-chain alkanes (0.3–0.7 wt%). Pyrolysis experiments with a lignite fatty acid fraction and with tetracosanoic acid show that these acids largely survive SCG extraction and, therefore, are not the main source of the relatively large quantity of straight-chain alkanes in these extracts.     

Contribution of trace metals from atmospheric deposition to stormwater runoff in a small impervious urban catchment

The contribution of atmospheric deposition to emissions of trace metals in stormwater runoff was investigated by quantifying wet and dry deposition fluxes and stormwater discharges within a small, highly impervious urban catchment in Los Angeles. At the beginning of the dry season in spring 2003, dry deposition measurements of chromium, copper, lead, nickel, and zinc were made monthly for 1 year. Stormwater runoff and wet deposition samples also were collected, and loading estimates of total annual deposition (wet+dry) were compared with annual stormwater loads. Wet deposition contributed 1-10% of the total deposition inside the catchment, indicating the dominance of dry deposition in semi-arid regions such as Los Angeles. Based on the ratio of total deposition to stormwater, atmospheric deposition potentially accounted for as much as 57-100% of the total trace metal loads in stormwater within the study area. Despite potential bias attributable to processes that were not quantified in this study (e.g., resuspension out of the catchment or sequestration within the catchment), these results demonstrate atmospheric deposition represents an important source of trace metals in stormwater to waterbodies near urban centers.     

Do landscape factors affect brownfield carabid assemblages?

The carabid fauna of 28 derelict sites in the West Midlands (England) were sampled over the course of one growing season (April-October, 1999). The study aimed to investigate the relationship between carabid assemblages and five measures of landscape structure pertinent to derelict habitat. At each site measurements of landscape features pertinent to derelict habitat were made: (i) the proximity of habitat corridors; (ii) the density of surrounding derelict land; (iii) the distance between the site and the rural fringe; and (iv) the size of the site. Concurrent surveys of the soil characteristics, vegetation type, and land use history were conducted. The data were analysed using a combination of ordination (DCA, RDA), variance partitioning (using pRDA) and binary linear regression. The results suggest that: 1. There is very little evidence that the carabid assemblages of derelict sites were affected by landscape structure, with assemblages instead being principally related to within-site habitat variables, such as site age (since last disturbance), substrate type and vegetation community. 2. No evidence was found to support the hypothesis that sites away from railway corridors are impoverished in their carabid fauna than sites on corridors. 3. There are some suggestions from this study that rarer and non-flying specialist species may be affected by isolation, taking longer to reach sites. We infer from this that older sites with retarded succession, and sites in higher densities of surrounding derelict land may eventually become more species rich and that these sites may be important for maintaining populations of rarer and flightless species. 4. Conservation efforts to maintain populations of these species should focus principally on habitat quality issues, such as maintaining early successional habitats that have a diversity of seed producing annuals and perennial plants and enhancing substrate variability rather than landscape issues.     

Having it All? Housing Reform Under Devolution

This paper aims to make an assessment of housing reform in Scotland since devolution in 1999. It is not concerned with a detailed analysis of any one particular policy but instead looks at whether housing reform is likely to contribute successfully to its own high level goals, which are identified as social justice, social cohesion, economic competitiveness and the empowerment of citizens and communities. It proceeds by examining those goals and the context for their development, and examining how they have been pursued, mainly through legislative change but also by administrative reform and financial inducement. The paper contends that in respect of some goals, especially achieving greater social justice, the reforms are likely to make considerable inroads. However, it also notes that the goals open up areas of conflict that are not fully acknowledged and are not resolved by the reforms.     

便携式照片打印机:让你的生活更轻松

曾几何时,在我们的书桌上少掉几张泛黄的合影照片,总是感觉遗憾。有人说,从现在开始,所有的回忆,包括声音与画面,都注定会被数字化。那么,为了避免这种遗憾,就让便携式照片打印机成为我们“家具”的一部分吧!     

Who will drive technological advance?

Electronic materials and packaging have been inexorably drawn along with the relentless march of technology. The complexity and capability of electronics increases with technology, yet it reduces the size and simplifies the shape of the materials and components that go to make up electronics. Whilst basic research into materials and packaging can be targeted into the areas of concern the main thrust for improvements is, of necessity, controlled by the specific needs of the product and the market.     

Morphologically dependent alternating‐current and direct‐current breakdown strength in silica–polypropylene nanocomposites

In this article, we report the synthesis of a new bimodal surface ligand morphology on silica nanoparticles. Combining grafting‐to and grafting‐from approaches, in this study, we demonstrated the efficacy of anthracene surface modification for improving the dielectric breakdown strength (DBS) under alternating‐current and direct‐current conditions and that of a matrix‐compatible polymer brush for controlling the nanofiller (NF) dispersion. Ligand‐modified spherical colloidal SiO₂ nanoparticles (～14 nm in diameter) were mixed into polypropylene, and the resulting dispersion was improved over the unmodified particles, as shown with transmission electron microscopy. The results suggest that the electronic structure of the anthracene‐modified particle surface was critical to the improvement in DBS. In addition, the DBS of the composite was shown to depend on the dispersion state of the filler and the mode of stress; this indicated that the individually dispersed nanoparticles were not necessarily the optimal morphology for all stress conditions. Additionally, the precise nature of the matrix‐compatible brush was less important than the NF dispersion it produced. The bimodal grafted architectural design has provided a promising solution for the control of the dispersion and surface properties, especially for high‐molecular‐weight polymer matrices. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44347.     

Coke Formation from Aircraft Engine Oils: Part II—Effects of Oil Formulation and Surface Composition

This is the second of two papers giving the results of a study undertaken to determine how aircraft engine oil degrades to form coke on oil-wetted surfaces. In part 2 the authors address the impacts of additives (which is related to oil types) and surface materials upon the oil coking process.

In Part 1 of this study, the authors showed that simple laboratory tests involving thin films of oil heated for specified timesltemperatures in open glass vials produced polymer and coke similar to the deposits seen on failed face seals taken from the operating aircraft engines and polymers isolated from used engine oils. Antioxidants inhibit and delay the coke producing reactions. After the antioxidant package is depleted to approximately 10 percent of the original level, the ester basestock undergoes accelerated oxidation to form oil-soluble polymers. As the oil spends additional time at elevated temperature, these polymers increase in molecular weight and undergo minor compositional changes becoming insoluble in the oil, producing deposits. If the time that a thin oil layer spends on a hot surface at elevated temperature can be limited so that the antioxidant does not deplete completely, coking can be prevented. This shifts the focus from coke minimization to coke prevention.

The authors results in Part 2 indicate that oil choice—which is largely a choice of antioxidant package—makes a large difference in how long oil can remain on a hot surface without forming polymer/coke deposits. For the oils studied in Part 2, the capabilities of the oils' antioxidant packages to inhibit coke formation varied 15 fold.

Surface material choice has minimal effect upon the rate of antioxidant depletion. However, once the antioxidant in the oil in a thin layer has become ineffective in inhibiting accelerated oxidation (approximately 10 percent of original concentration), the material the oil resides upon strongly effects the rate of the polymer/coke formation processes. Stainless steel speeds the process compared to a glass substrate.