Surface-mediated formation of PBDD/Fs from the high-temperature oxidation of 2-bromophenol on a CuO/silica surface

As a model brominated hydrocarbon that may form brominated dioxins, we studied the surface-mediated, oxidative thermal degradation of 2-bromophenol on a supported copper oxide catalyst in a 1 mm i.d., fused silica flow reactor at a constant concentration of 90 ppm over a temperature range from 250 to 550 degrees C. Observed products included: dibenzo-p-dioxin (DD), 1-monobromodibenzo-p-dioxin (1-MBDD), dibromodibenzo-p-dioxin (DBDD), tribromodibenzo-p-dioxin (TrBDD), 4-monobromodibenzofuran (4-MBDF), 2,4,6-tribromophenol, 2,4- and 2,6-dibromophenol, and polybrominated benzenes. The results are compared and contrasted with previous work on surface catalyzed oxidative thermal degradation of 2-chlorophenol as well as our own work with the surface-catalyzed pyrolytic thermal degradation of 2-bromophenol. Typically 20 to 200x higher yields of PBDDs are observed for 2-bromophenol than for the analogous PCDDs for 2-chlorophenol. However the anticipated PBDF, 4,6-DBDF, was not observed and 4-MBDF was observed at very low yields. Surprisingly, the maximum yields of PBDDs were observed at higher temperatures than under pyrolytic conditions. This is attributed to regeneration of the catalytic surface due to the presence of oxygen. Higher yields of polybrominated phenols and polybrominated benzenes were also observed than for the analogous chlorinated phenols and benzenes from the oxidation of 2-chlorophenol. This can be attributed to the ease of bromination over chlorination based on the higher abundance of bromine atoms present for 2-bromophenol than chlorine atoms present for 2-chlorophenol.     

Polybrominated diphenyl ethers (PBDEs) in mussels from selected French coastal sites: 1981-2003

The present study focused on the retrospective analysis of PBDEs in archived blue mussel (Mytilus edulis or Mytilus galloprovincialis) samples collected over the past 22 years (1981-2003) from coastal areas of France. We have found that PBDE levels in mussels from the English Channel increased markedly from 1981 to 1991-1995, doubling approximately every 5-6 years followed by a levelling off and a possible beginning of a decrease. The rate of the decline of hexa- and hepta-BDE congeners was more rapid than the decline of tetra- and penta-BDEs in these mussel samples. The difference in the course of time of lower and higher brominated PBDE concentrations suggests that the congener profile in the mussel samples changes over time. The increase in PBDE concentrations in the mussel samples contrasts with a concomitant constant decrease of chlorobiphenyls (CBs) in the same set of samples. However, pulse inputs of both groups of organohalogen compounds were determined for the mussel samples collected at the mouth of the Seine estuary and were probably related to riverine inundations and a flushing out of the deposited sediments from the internal estuary into the bay of the River Seine, as well as considerable dredging activities taking place during same years. In France, the highest PBDE concentrations were determined in the mussels from the English Channel, more precisely in the bay of the Seine, and the regional differences in PBDE levels were mainly connected to the difference in anthropogenic urban and industrial environmental pressures. Published data comparing PBDE levels in mussels have shown significant differences in concentrations between North/South America and Europe. This observation further confirms that the PBDE levels in the North American environment are higher than in Europe. However, the data used for this comparison of mussel contamination by PBDEs is still relatively sparse.     

Effects of Simulated Sulphuric Acid Deposition On Calluna Vulgaris/Peat Microcosms and Associated Soil Solutions

Calluna vulgaris/peat microcosms have been used in an outdoor simulated acid rain experiment to test a series of hypotheses about sulphuric acid deposition effects upon the growth of Calluna on peat soil, namely: (1) Initially, enhanced acid input will enhance base cation and ammonium concentrations in soil solution. This may enhance uptake of these species, increasing foliar concentrations of base cations and nitrogen, and possibly foliar chlorophyll a and b concentrations. (2) If changes are induced in nutritional status, they may influence plant growth. (3) in the longer term, enhanced ammonium and base cation solubility occurring as a consequence of cation exchange reactions will lead, especially in winter months, to enhanced leaching losses. Hence any positive effects upon plant nutrition will not be sustainable. (4) the peat will acidify significantly over two years, in the shorter term primarily as a consequence of an enhanced mobile anion effect. (5) Acidification may reduce the rate of mineralisation of organic phosphorus and, in a phosphorus-deficient peat soil, this may lead to reduced foliar phosphate concentration and possibly induce phosphorus deficiency.

Most of these hypotheses were supported to some extent by the experimental results. the peat soil solution pH fell immediately in response to the acid treatments, and longer-term acidification continued progressively over the two years of the experiment. in the first year, the treatments significantly influenced the calcium, magnesium, phosphorus and nitrogen status of the leaves from Calluna new shoots, whereas in the second year calcium, potassium and phosphorus were influenced. However, in both years foliar phosphate concentration was enhanced, rather than reduced, in response to increased acid load. Foliar carbon and nitrogen concentrations fell with increasing acidity of     

Knowledge hiding in organizations

Despite the efforts to enhance knowledge transfer in organizations, success has been elusive. It is becoming clear that in many instances employees are unwilling to share their knowledge even when organizational practices are designed to facilitate transfer. Consequently, this paper develops and investigates a novel construct, knowledge hiding. We establish that knowledge hiding exists, we distinguish knowledge hiding from related concepts (knowledge hoarding and knowledge sharing), and we develop a multidimensional measure of this construct. We also identify several predictors of knowledge hiding in organizations. The results of three studies, using different methods, suggest that knowledge hiding is comprised of three related factors: evasive hiding, rationalized hiding, and playing dumb. Each of these hiding behaviors is predicted by distrust, yet each also has a different set of interpersonal and organizational predictors. We draw implications for future research on knowledge management. Copyright © 2010 John Wiley & Sons, Ltd.     

The need to look beyond the production and provision of relief seed: experiences from southern Sudan

Free distribution of seeds in selected areas of southern Sudan has been widespread as a way of increasing food security. Field research in areas targeted for seed relief found that farmer seed systems continue to meet the crop and varietal needs of farmers even following the 1998 famine. Donor investments in seed multiplication of improved sorghum have not been sustained due to a lack of effective demand for the improved seed beyond that created by the relief agencies. The article argues that rather than imposing outside solutions, whether through seed provisioning or seed production enterprises, greater attention needs to be given to building on the strengths of existing farmer systems and designing interventions to alleviate the weaknesses. The case is made to support dynamically the process of farmer experimentation through the informed introduction of new crops and varieties that can potentially reinforce the strength and diversity of local cropping systems.     

Hypomandibular faciocranial dysostosis in consanguineous parents revealed by ultrasound prenatal diagnosis

We report here the fourth case of hypomandibular faciocranial dysostosis (HFD). The diagnosis was made at birth on the association of severe retrognathia, microstomia, severe hypoglossia with glossoptosis, persistent buccopharyngeal membrane, median cleft palate, bifid uvula, down-slanting palpebral fissures, short nose with anteverted nares, laryngeal hypoplasia, and low-set ears. A severe microstomia and micrognathia were detected by ultrasound at 31 weeks of gestation. Interestingly, even though the present case exhibits many facial dysmorphic features characteristic of HFD, craniosynostosis was absent. This report suggests that craniosynostosis is not mandatory for the diagnosis of this condition. Furthermore, we present a new argument for an autosomal recessive mode of inheritance for HFD. Copyright © 2002 John Wiley & Sons, Ltd.     

Fluorescence in situ hybridization (FISH) for rapid detection of aneuploidy: experience in 911 prenatal cases†

Fluorescence in situ hybridization (FISH) was performed with probes specific for chromosomes 13, 18, 21, X and Y on 911 of 11123 (8.2%) amniotic fluid samples submitted to the present authors' laboratory for cytogenetic analysis over an 8-year period. Altogether 3516 hybridizations were performed with an interpretable FISH result on all chromosomes requested in 884/911 (97%) of cases. An uninformative FISH result occurred in 44 hybridizations among 27 cases (3%). Of a total of 89 karyotypically proven cases with aneuploidy that might have been detected by FISH, the overall detection rate was 84%. An inconclusive or incomplete FISH result occurred in 9/89 (10%) of these proven aneuploid cases. In the remaining 80 informative proven aneuploid cases, correct detection of aneuploidy was accomplished in 75/80 (94%) of samples. A false-negative result occurred in the remaining 5/80 (6%) of such informative cases. Eighteen cases had karyotypically proven abnormalities that could not have been detected by the targeted FISH. Aside from these 18 cases, FISH allowed correct detection of normal disomy in 785/804 (98%) of such cases. An incomplete FISH result occurred in 18 normal disomic cases. There was a single possible ‘false-positive’ FISH result for chromosome 21. Interphase FISH analysis of uncultured amniotic fluid cells has been shown to be a useful laboratory tool for rapid fetal aneuploidy screening during pregnancy. As with all clinical laboratory diagnostic tests, incomplete or inconclusive results (or even interpretive errors) occur in a small percentage of cases. Nevertheless, FISH results accompanied by other data and by appropriate counseling provide clinicians and patients with valuable information for clinical decision-making surrounding family planning and pregnancy management. Copyright © 2001 John Wiley & Sons, Ltd.     

Potential impacts of imposing methyl bromide phaseout on US strawberry growers: a case study of a nomination for a critical use exemption under the Montreal Protocol

The Montreal Protocol on Substances that Deplete the Ozone Layer requires developed countries to phaseout methyl bromide production and non-quarantine uses by 2005 and developing countries to do the same by 2015. Exemptions to phaseout have been significant in slowing the process of abatement; many countries have applied for exemptions for some uses, partly on grounds that phaseout is economically infeasible. Data on the US strawberry market are used to investigate grower costs arising from substitution away from methyl bromide, the impact of trends in and characteristics of the demand for fresh strawberries, and characteristics of trade with countries not yet required to eliminate use of the compound. It appears that actual net costs to growers will be much smaller than the simple increase in production costs cited in the US nomination for exemption.