Evaluation of performance reference compounds in polyethylene-based passive air samplers

Polyethylene-based passive air samplers (PSDs) were loaded with performance reference compounds (PRCs) and deployed in a wind tunnel to examine the effects of wind speed on sampler performance. PRCs could be loaded reproducibly into PSDs, with coefficients of variation only exceeding 20% for the more volatile compounds. When PSDs were exposed to low (0.5-1.5 m s(-1)) and high (3.5-4.5 m s(-1)) wind speeds, PRC loss rate constants generally increased with increasing wind speed and decreased with increasing sampler/air partition coefficients. PSD-based air concentrations calculated using PRC loss rate constants and sampler/air partition coefficients and air concentrations measured using active samplers compared closely. PRCs can be used to account for the effect of differences in wind speeds on sampler performance and measure air concentrations with reasonable accuracy. (c) 2006 Elsevier Ltd. All rights reserved.

Community-based programmes to prevent falls in children: A systematic review

Objective: We systematically reviewed the literature to examine the evidence for the effectiveness of community-based interventions to reduce fall-related injury in children aged 0-16 years. Methods: We performed a comprehensive search of the literature using the following study selection criteria: community-based intervention study; target population was children aged 0-16 years; outcome measure was fall-related injury rates; and either a community control or historical control was used in the study design. Quality assessment and data abstraction were guided by a standardized procedure and performed independently by two authors. Results: Only six studies fitting the inclusion criteria were identified in our search and only two of these used a trial design with a contemporary community control. Neither of the high quality evaluation studies showed an effect from the intervention and while authors of the remaining studies reported effective falls prevention programmes, the pre- and post-intervention design, uncontrolled for background secular trends, makes causal inferences from these studies difficult. Conclusion: There is a paucity of research studies from which evidence regarding the effectiveness of community-based intervention programmes for the prevention of fall-related injury in children could be based.

Gingerol content of diploid and tetraploid clones of ginger (Zingiber officinale Roscoe)

Ginger (Zingiber officinale, Roscoe), a monocotyledonous, sterile cultigen, is widely used as a spice, flavoring agent, and herbal medicine. The pungency of fresh ginger is due to a series of homologous phenolic ketones of which [6]-gingerol is the major one. The gingerols are thermally unstable and can be converted to their corresponding shogaols, which are present in dried ginger, Fresh rhizomes of 17 clones of Australian ginger, including commercial cultivars and experimental tetraploid clones, were assayed by HPLC for gingerols and shogaols. [6]-Gingerol was identified as the major pungent phenolic compound in all samples, while [8]- and [10]-gingerol occurred in lower concentrations. One cultivar known as Jamaican contained the highest concentrations of all three gingerols and was the most pungent of the clones analyzed. Gingerols were stable in ethanolic solution over a 5-month period when stored at 4 degrees C. Shogaols were not identified in the extracts prepared from fresh rhizomes at ambient temperature, confirming that these compounds are not native constituents of fresh ginger, In contrast to previous findings, this study did not find significant differences in gingerol concentrations between the tetraploid clones and their parent diploid cultivar.

Electronic nose evaluation of onion headspace volatiles and bulb quality as affected by nitrogen, sulphur and soil type

Edaphic factors affect the quality of onions (Allium cepa). Two experiments were carried out in the field and glasshouse to investigate the effects of N (field: 0, 120 kg ha(-1); glasshouse: 0, 108 kg ha(-1)), S (field: 0, 20 kg ha(-1); glasshouse: 0, 4.35 kg ha(-1)) and soil type (clay, sandy loam) on onion quality. A conducting polymer sensor electronic nose (E-nose) was used to classify onion headspace volatiles. Relative changes in the E-nose sensor resistance ratio (%dR/R) were reduced following N and S fertilisation. A 2D Principal Component Analysis (PCA) of the E-nose data sets accounted for c. 100% of the variations in onion headspace volatiles in both experiments. For the field experiment, E-nose data set clusters for headspace volatiles for no N-added onions overlapped (D-2 = 1.0) irrespective of S treatment. Headspace volatiles of N-fertilised onions for the glasshouse sandy loam also overlapped (D-2 = 1.1) irrespective of S treatment as compared with distinct separations among clusters for the clay soil. N fertilisation significantly (P < 0.01) reduced onion bulb pyruvic acid concentration (flavour) in both experiments. S fertilisation increased pyruvic acid concentration significantly (P < 0.01) in the glasshouse experiment, especially for the clay soil, but had no effect on pyruvic acid concentration in the field. N and S fertilisation significantly (P < 0.01) increased lachrymatory potency (pungency), but reduced total soluble solids (TSS) content in the field experiment. In the glasshouse experiment, N and S had no effect on TSS. TSS content was increased on the clay by 1.2-fold as compared with the sandy loam. Onion tissue N:water-soluble SO42- ratios of between five and eight were associated with greater %dR/R and pyruvic acid concentration values. N did not affect inner bulb tissue microbial load. In contrast, S fertilisation reduced inner bulb tissue microbial load by 80% in the field experiment and between 27% (sandy loam) and 92% (clay) in the glasshouse experiment. Overall, onion bulb quality discriminated by the E-nose responded to N, S and soil type treatments, and reflected their interactions. However, the conventional analytical and sensory measures of onion quality did not correlate with %dR/R.