Urban wastelands: On the frontline between air pollution sources and residential areas.

In urban areas, particulate matter (PM) represents an increasing threat to human health. The ability of plants in parks and along roads in cities to accumulate PM has already been demonstrated, but nothing is known about the effect of wasteland vegetation on air quality, despite a significant proportion of greenery in polluted areas being on wastelands. The aim of this study was to document the accumulation of PM and trace elements (TE) by wasteland species (Robinia pseudoacacia L., Populus × canescens (Aiton) Sm., Acer negundo L., Solidago gigantea (Aiton) and Poaceae) growing on Central European urban wastelands with differing levels of air pollution. On average, the largest amounts of PM accumulated on the foliage of R. pseudoacacia and S. gigantea, and the smallest amounts accumulated on P. × canescens leaves. However, accumulation of PM depended more on the distance from the emission source than on species selection, and was higher on the polluted wasteland where the plants' gas exchange was the lowest. The results also suggest that in order to effectively accumulate PM from the air, it is critical to have the correct configuration of plants, with the wasteland vegetation having a layered structure and layers differing in PM retention, as shown in this study using the examples of R. pseudoacacia (a tall tree with low PM retention) and S. gigantea (below-tree vegetation with high PM retention). P. × canescens accumulated the highest concentrations of Cd and Zn, S. gigantea accumulated the highest concentration of Cu, and Poaceae accumulated the highest concentrations of Cr and Ni. These findings have implications for urban vegetation management in areas where there is no organised greenery, and offer proof that vegetation in wasteland areas should be maintained since it is an excellent tool for reducing concentrations of PM at its place of origin.

Thus far but no further: predatory mites do not migrate effectively into strawberry plantations.

Enhancing the performance of predatory mites is often regarded as the best biological control approach towards the spider mite Tetranychus urticae, the main pest of strawberry plantations. Optimizing the colonization of plantations by predators from adjacent areas such as field margins is seen as an important component of conservation biocontrol. We have investigated the factors contributing to enhancing the numbers of predatory mites (Acari: Phytoseidae), such as management of the field margins, vegetation composition and the effect of the presence of woody species. We also tested the penetration of the phytoseiids from the field margins into the crop. In a study carried out in 14 open-field extensively managed strawberry plantations in Poland we found phytoseiids to be abundant in field margins; 14 taxa were discovered. However, only two species Amblyseius andersoni and Euseius finlandicus dispersed a modest distance into the crop. We found that the diversity and densities of the predatory mites were enhanced somewhat by the management type of the field margins; especially the spontaneous vegetation favoured the presence of phytoseiids. However, despite the predatory mites being rather retained in the field margins also significant reduction in numbers of their prey T. urticae was recorded over the course of the year. The low penetration of predatory mites into the main part of the field, indicates that conservation biological control measures in the field margin might not be sufficient on their own to enhance the impact of predatory mites within the main part of the fields.

Oxidative fabrication of patterned, large, non-flaking CuO nanowire arrays.

We report a simple and fast approach to fabricate large, non-flaking arrays of CuO nanowires by oxidizing thin copper substrates in air. Oxidative CuO nanowire growth is commonly accompanied by oxide layer flaking due to stress at the copper-copper oxide interface. Using thin substrates is shown to prevent this flaking by introducing favourable material thickness ratios in the samples after oxidation. Additionally, thin foils allow larger scale topographic patterns to be transferred from an underlying mould to realize non-flat, nanowire-decorated surfaces. Further patterning is possible by electrodeposition of a nickel layer, which restricts nanowire growth to specific areas of the sample.

A bio-originated porous template for the fabrication of very long, inorganic nanotubes and nanowires.

A biopolymer-based template assembly constructed around the spines of the bristle worm Aphrodita aculeata (sea mouse) was used to fabricate very high aspect ratio nanowires and nanotubes using established methods adopted from nanofabrication in porous membranes. The easily available bio-originated template contains more than 100 000 highly ordered, very high aspect ratio nanochannels, each about 150 to 200 nm in diameter but up to a centimetre in length. Their parallel, hexagonal arrangement in the spine constitutes a photonic crystal, which gives the animal its colourful, iridescent appearance. Around the nanochannels, the spines consist of a chitin/protein composite material, which has been shown to withstand the chemical and thermal conditions needed for established template-assisted nanofabrication strategies. A template preparation procedure was developed and the template was used to fabricate copper and nickel nanowires by electrodeposition and aluminium oxide nanotubes by atomic layer deposition. Due to their high thermal and chemical stability, decomposition of the filled templates proved to be difficult, and different approaches to obtain separated nanostructures are described and discussed. Alongside this, the presented system of parallel nanowires or nanotubes in a biopolymer matrix might be utilized in applications, where such separated structures are not needed. Comparing to porous membranes, the presented template allows us to increase the maximum length of nanotubes and nanowires produced using nanochannel-based templates by at least one order of magnitude.

Optical image correlator realized with a hybrid liquid-crystal-photoconducting polymer structure.

A joint Fourier-transform optical correlator for image recognition based on a novel hybrid photoconducting polymer-nematic liquid-crystal structure is described. The optically addressed active element that we have designed is capable of performing real-time image processing 20 times/s, at light-intensity levels of 10mW/cm(2) with dc operating voltage of the order of 10 V. We present the results of correlation of simple objects as well as complicated photographs. The sensitivity, durability, and reliability of the presented system open possibilities for many applications.

The radiographic characteristics of histiocytosis X. A study of 29 cases that involve the jaws.

The purpose of this study was to provide an objective analysis of the radiographic characteristics of histiocytosis X as it affects the jaws. The original radiographs of 29 cases were reviewed independently and objectively by three observers. The results suggest that seven characteristics, either alone or in combination, are useful in the identification of histiocytosis X. These include the appearance of solitary "intraosseous" lesions, the multiplicity of "alveolar bone" lesions, the "scooped-out" effect in the alveolar process, the well-defined periphery, sclerosis in the alveolar bone lesions, periosteal new bone formation, and slight root resorption.

The effectiveness of the thyroid shield in dental radiology.

The effectiveness of the thyroid shield in reducing patient exposure during routine dental radiographic examinations was studied. A nonscreen film and two film-screen combinations were used as dosimeters and to show the spatial distribution of x-ray exposure. The error in the absolute accuracy of the film dosimeter and the error in the reproducibility of the film-screen combinations were less than +/- 10%. Measurements of thyroid exposure and exposure distribution, with and without the shield, were made on a Rando phantom and on patients. In the phantom study, the reduction by the shield of exposure to the thyroid from primary beam and from scatter was found to be highly dependent on the position of the primary beam relative to the thyroid gland but independent of kVp. Exposure reduction by the shield varied from 5% to 56% for a complete-mouth survey, 2% to 18% for a bitewing survey, and 10% to 79% for a panoramic survey. In the patient study, thyroid skin exposures measured on adults were 33% to 84% lower in offices in which the shield was used as compared to offices in which it was not used. Thyroid skin exposures measured on children were 63% to 92% lower. In accordance with the ALARA principle, these results support the routine use of the thyroid shield for all dental radiography.