Liquid chromatographic aqueous product characterization of high-energy electron beam irradiated 2-chlorobiphenyl solutions

Polychlorinated biphenyls (PCBs) are of environmental concern due to their toxic nature. Ionizing radiation has been suggested as a means to remediate PCB-contaminated samples in complex matrices. A set of experiments was performed to qualitatively and quantitatively determine the aromatic degradation products of 2-monochlorobiphenyl (2-MCB) in an aqueous system exposed to ionizing radiation. The degradation of 2-MCB was observed in aqueous samples that were exposed to radiation from a linear accelerator electron beam source. Analytical measurements performed by liquid chromatography (LC) equipped with an ultraviolet (UV) detector revealed that biphenyl, o-hydroxybiphenyl, p-hydroxybiphenyl, phenol, chlorobenzene, and other unidentified products were created after 2-MCB irradiation. These results suggest that sensitive and selective analytical methods will be required to account for all degradation products during ionizing radiation of aqueous PCB-contaminated samples.     

Fetal ear measurements in the prenatal detection of trisomy 21

Although prominent fetal nuchal folds, short long bones, echogenic bowel, and renal pelviectasis have been shown to be associated with trisomy 21, none has acceptable diagnostic efficacy. Diminished fetal ear lengths measured by ultrasound have recently been reported as yet another potential morphological marker for the prenatal detection of trisomy 21. To investigate this further, we measured ear lengths and widths of normal (n = 107) and trisomy 21 (n = 25) second-trimester formalin-preserved fetuses. The normal ear growth characteristics are described and compared with those of trisomy 21 fetuses. The normal fetal ear shape, not unlike that of the neonates, manifested a marked variation. When the ear lengths and widths were regressed against gestational age, the slopes of the regression lines for the two groups were found to be different (P < 0·001). However, despite the statistically significant difference between the ear sizes of normal and trisomy 21 fetuses, the wide range of normal variation seen at each gestational age means that the fetal ear measurements are not diagnostically helpful.     

Second-trimester echogenic small bowel: An increased risk for adverse perinatal outcome

2267 singleton fetuses who had one ultrasound examination between 15 and 21 weeks' gestation were prospectively evaluated for echogenic small bowel. Thirty-two cases of echogenic small bowel were detected—a prevalence of 1·4 per cent. Echogenic fetal small bowel was divided into two grades: grade 1, where the small bowel was more echogenic than the liver; and grade 2, where the small bowel had the echogenicity of bone. In contrast to 19/23 fetuses with grade 1 small bowel echogenicity, only 2/9 fetuses with grade 2 echogenic bowel had a normal pregnancy outcome (Fisher's exact test; P⩽0·01). Complications associated with second-trimester echogenic small bowel included in utero cytomegalovirus infection, second-trimester growth restriction, intrauterine fetal demise, and chromosomal abnormalities. Second-trimester fetal echogenic small bowel is associated with an increased risk of an adverse outcome. The prevalence of perinatal and neonatal complications is significantly greater when small bowel echogenicity approaches that of bone.     

A challenge to the assumed generalizability of prediction and countermeasure for risky driving: different factors predict different risky driving behaviors

In road safety, it may be debated whether all risky behaviors are sufficiently similar to be explained by similar factors. The often assumed generalizability of the factors that influence risky driving behaviors has been inadequately tested. Study 1 (N=116) examined the role of demographic, personality and attitudinal factors in the prediction of a range of risky driving behaviors, for young drivers. Results illustrated that different driving behaviors were predicted by different factors (e.g., speeding was predicted by authority--rebellion, while drink driving was predicted by sensation seeking and optimism bias). Study 2 (N=127) examined the generalizability of these results to the general driving population. Study 1 results did not generalize. Predictive factors remained behavior-specific, but different predictor-behavior relationships were observed in the community sample. Overall, results suggest that future research and practice should focus on a multi-factor framework for specific risky driving behaviors, rather than assuming generalizability across behaviors and driving populations.     

Temperature, salinity and growth rate dependences of Mg/Ca and Sr/Ca ratios of the skeleton of the sea urchin Paracentrotus lividus (Lamarck): an experimental approach

The skeletal Mg/Ca ratio of echinoderms is known to increase with temperature but the relation has never been established in controlled experimental conditions. The present study investigated the effect of temperature, salinity and growth rate on Mg/Ca and Sr/Ca ratios in calcite skeletons of juvenile sea urchins grown in experimental conditions. Mg/Ca ratio was positively related to temperature, increasing until a plateau at high but field occurring temperatures. It was not linked to salinity nor growth rate. We suggest that this plateau is due to properties of the organic matrix of mineralization and recommend to take it into account for the use of Mg/Ca as proxy of seawater Mg/Ca. Skeletal Sr/Ca ratio was mainly dependent on temperature and growth rate, as usually observed in calcite skeletons.     

Molecular phylogenies help resolve taxonomic confusion with Asian <Emphasis Type="Italic">Crassostrea</Emphasis> oyster species

Identification of oyster species is still largely based on phenotypic characters that are highly plastic. Prompted by the proposed introduction of the Asian oyster species Crassostrea ariakensis into the Chesapeake Bay region of the U.S.A., this study uses molecular genetic information to understand the taxonomic framework surrounding C. ariakensis and to confidently distinguish among various sympatric oyster species. Putative samples of C. ariakensis and other species of cupped oysters from across Asia were collected and phylogenetic analyses were conducted on DNA sequences of both nuclear (ITS-1) and mitochondrial (COI) regions. Trees generated based on the two independent molecular datasets were highly congruent, and indicate that many oysters collected for this study as C. ariakensis were originally misidentified. Results also indicate that C. ariakensis, C. hongkongensis and C. nippona are distinct, but closely related species. There is strong support in both analyses for a close relationship between C. gigas and C. sikamea, as well as between C. belcheri and C. gryphoides, and between C. iredalei and C. madrasensis. The parsimony analyses based on these DNA markers, however, did not provide evidence to support C. angulata as a distinct species from C. gigas. Overall, the results emphasize the need for rigorous species identification, and additional extensive and intensive sampling to more accurately determine relationships among Crassostrea species, define their geographic distributions, and establish existing sympatry patterns.     

Cellular response of mouse splenocytes to heavy metals exposure

Among the environmental contaminants recognised for their toxicity and their global presence, heavy metals are certainly a major concern. They can elicit a number of immunomodulatory effects leading ultimately to an enhanced susceptibility (sensitivity) of immune cells to microbial agents and the appearance of neoplastic diseases and autoimmune phenomena. Heavy metals also provoke changes in the function(s) of immune cells. A striking biological effect of heavy metals is the induction of intracellular thiols (cysteine, glutathione, metallothioneins). Thiols are involved in many physiological processes, including protection from free radical damage and detoxification of chemicals. The purpose of this study was to assess the differences of susceptibility (sensitivity) in both pre-activated (concanavalin A was used) and non-pre-activated cells in the presence of heavy metals. Five were evaluated on murine splenocytes. The lymphoblastic proliferation test was performed for lymphocytes and a phagocytosis test for macrophages. Data showed that the levels of thiols in the pre-activated cells are greater than non-pre-activated cells following exposure to various heavy metals; macrophages were more resistant than lymphocytes to the toxic effects of heavy metals, and pre-activated cells were more resistant than cells at rest. One possible explanation is that macrophages produce more thiols than lymphocytes and this provides an increased protection from the deleterious effects of heavy metals.     

[Case Study] CityCenter and Cosmopolitan Construction Projects, Las Vegas, Nevada: Lessons learned from the use of multiple sources and mixed methods in a safety needs assessment

Problem

The present study describes a response to eight tragic deaths over an eighteen month times span on a fast track construction project on the largest commercial development project in U.S. history.

Methods

Four versions of a survey were distributed to workers, foremen, superintendents, and senior management. In addition to standard Likert-scale safety climate scale items, an open-ended item was included at the end of the survey.

Results

Safety climate perceptions differed by job level. Specifically, management perceived a more positive safety climate as compared to workers. Content analysis of the open-ended item was used to identify important safety and health concerns which might have been overlooked with the qualitative portion of the survey.

Discussion

The surveys were conducted to understand workforce issues of concern with the aim of improving site safety conditions. Such efforts can require minimal investment of resources and time and result in critical feedback for developing interventions affecting organizational structure, management processes, and communication.

Summary

The most important lesson learned was that gauging differences in perception about site safety can provide critical feedback at all levels of a construction organization.

Impact on the Industry

Implementation of multi-level organizational perception surveys can identify major safety issues of concern. Feedback, if acted upon, can potentially result in fewer injuries and fatal events.     

Bioconcentration of polycyclic aromatic hydrocarbons by the freshwater oligochaete Lumbriculus variegatus

Tissue residues of the PAHs, anthracene, fluorene, fluoranthene and pyrene were determined in Lumbriculus variegatus at four time intervals during both a 96-h exposure period to monitor uptake, and a 96-h clean water period to assess depuration. Mean BCFs were 2390, 1210, 452 and 1920 for fluoranthene, anthracene, fluorene and pyrene, respectively. BCFs were positively correlated with the octanol/water partition coefficient values of the four PAHs. Depuration occurred most rapidly for fluorene, followed by anthracene and fluoranthene. No apparent depuration of pyrene was observed during the 96-h depuration period. Because of rapid depuration of some PAHs, it appears that the 24 h clean water gut clearance period recommended in conjunction with sediment bioaccumulation tests with L. variegatus has potential to result in an under-estimation of bioaccumulation of some chemicals.     

An axenic plant culture system for optimal growth in long-term studies

The symbiotic co-evolution of plants and microbes leads to difficulties in understanding which of the two components is responsible for a given environmental response. Plant-microbe studies greatly benefit from the ability to grow plants in axenic (sterile) culture. Several studies have used axenic plant culture systems, but experimental procedures are often poorly documented, the plant growth environment is not optimal, and axenic conditions are not rigorously verified. We developed a unique axenic system using inert components that promotes plant health and can be kept sterile for at least 70 d. Crested wheatgrass (Agropyron cristatum cv. CDII) plants were grown in sand within flow-through glass columns that were positively pressured with filtered air. Plant health was optimized by regulating temperature, light level, CO2 concentration, humidity, and nutrients. The design incorporates several novel aspects, such as pretreatment of the sand with Fe, graduated sand layers to optimize the air-water balance of the root zone, and modification of a laminar flow hood to serve as a plant growth chamber. Adaptations of several sterile techniques were necessary for maintenance of axenic conditions. Axenic conditions were verified by plating and staining leachates as well as a rhizoplane stain. This system was designed to study nutrient and water stress effects on root exudates, but is useful for assessing a broad range of plant-microbe-environment interactions. Based on total organic C analysis, 74% of exudates was recovered in the leachate, 6% was recovered in the bulk sand, and 17% was recovered in the rhizosphere sand. Carbon in the leachate after 70 d reached 255 microg d(-1). Fumaric, malic, malonic, oxalic, and succinic acids were measured as components of the root exudates.