The Strengths and Difficulties Questionnaire: a pilot study of a new computer version of the self-report scale.

A computer-based version of the self-report Strengths and Difficulties Questionnaire (SDQ) was developed with colourful graphics illustrating each question. One hundred and two children referred to child and adolescent mental health services were recruited and randomly allocated to complete either the new computer-based version or the paper original. A further 112 children from local schools were recruited and completed the computer-based version of the scale. All children who took part in the study were aged between 8 and 15 years. The paper version of the SDQ is recommended for use in children aged 11 and over and, in this age group, the computer-based questionnaire was able to discriminate between the clinical and community sample (ROC = 0.761, 95 % CI 0.676-0.846). Comparison of the paper-based SDQ and computer-based SDQ within the clinic sample found trends towards better test-retest reliability, inter-rater reliability and significantly better user satisfaction in the computer version compared to the paper-based version. The computer-based SDQ has the added advantage of results being automatically added to a spreadsheet out of view from the user reducing the chance of operator error in coding and entering the data. These preliminary results suggest that the computer-based version of the SDQ may represent a further improvement on the paper SDQ. All versions of the SDQ, including the computer-based version, can be downloaded from the Strengths and Difficulties website address www.sdqinfo.com.

Linking ecological impact to metal concentrations and speciation: a microcosm experiment using a salt marsh meiofaunal community.

Microcosm experiments addressed the impact of a mixture of Cu, Cr, Cd, Pb, and Hg at three concentrations after 36 h, 12 d, and 30 d on a meiofauna-dominated salt marsh community. In addition to analyzing effects on meiofaunal abundances, the study quantified the sediment metal concentrations of all five metals and pore-water concentrations, speciation, and ligand complexation of Cu. Abundances of deposit feeders such as the polychaete Streblospio benedicti, gastropods, and bivalves were impacted at lower metal concentrations than the mainly algal-feeding copepods, ostracods, and nematodes. We suggest that this might be due to bulk ingestion of metal-contaminated sediments resulting in relatively higher metal exposure in the deposit feeders than in the other, nondeposit feeding taxa. Copepod and ostracod abundances decreased only in the highest metal treatment, where levels of inorganic Cu ([Cu']) in pore waters were similar to levels associated with both acute and subacute toxicity in published in vivo toxicity studies of marine copepods. The higher metal treatments yielded disproportionately higher pore-water [Cu] compared with sediment [Cu], suggesting saturation of sediment-associated ligands with increased additions of Cu. Similarly, the higher metal treatments appeared to reach saturation of the organic Cu ligands, with the excess pore-water [Cu] present in the more toxic, inorganic species of Cu. Acid-volatile sulfide (AVS) concentrations at sediment horizons inhabited by meiofauna were low and AVS was not considered a significant metal ligand at these depths. Since meiofauna are predominantly associated with oxic surface sediments, it is doubtful that AVS is a major factor controlling availability of free metal for exposure to these taxa.

Pyrene bioaccumulation, effects of pyrene exposure on particle-size selection, and fecal pyrene content in the oligochaete Limnodrilus hoffmeisteri (Tubificidae, Oligochaeta).

The oligochaete Limnodrilus hoffmeisteri Cleparéde was exposed to sediment-amended pyrene (0-1,196 nmol/g dry wt) for 2, 5, and 10 d to investigate sediment particle-size preference, tissue pyrene bioaccumulation (using biota-sediment accumulation factor, BSAF), fecal pyrene concentrations (using fecal-sediment accumulation factor, FSAF), and pyrene biotransformation. In non-pyrene-amended sediment, L. hoffmeisteri preferentially ingested finer sediment particles (< 3.5 microns). However, pyrene concentrations > 199 nmol/g dry weight resulted in a decreased preference for finer particles, presumably reducing pyrene exposure. Particle selectivity also changed with time such that after 10 d, worms showed an increased preference for finer particles. At high pyrene exposure, tissue pyrene concentrations rapidly attained equilibrium (maximum body residue 4.4 mumol/g wet wt, close to values cited for hydrocarbon critical body residues). Levels of biotransformation were low (mean 14%) and independent of time or pyrene concentration. Biota-sediment accumulation factor showed a negative relationship with sediment pyrene concentration; this trend may be due to reduced availability at high sediment pyrene concentrations or due to reductions in both ingestion rate and selectivity for fine, pyrene-rich particles. Fecal pyrene concentrations were depleted compared to sediment levels, suggesting removal of pyrene during gut passage by absorption. Fecal-sediment accumulation factor showed a negative relationship with increasing sediment pyrene levels.

Directed assembly of multilayers--the case of Prussian blue.

We introduce the concept of 'directed assembly' of multilayers on surfaces: the overall process involves the exposure of a surface to a series of solutions containing, alternately, adsorbable cations and adsorbable anions, and these are gradually built up into well-defined multilayer structures.