An interlaboratory round robin study on the analysis of toxaphene in a cod liver oil standard reference material

An inter-laboratory round robin analysis of toxaphene in a National Institute of Standards Cod Liver Oil #1588 was carried out. Analysis was performed by GC-ECD, electron capture negative ion GCMS (ECNI GCMS) and electron impact GC/MS in high resolution single ion monitoring mode (EI-HRSIM). Results of the analyses by GC-ECD, ECNI and HRSIM were 4.22±2.45 ppm, 3.95±1.57 ppm, and 2.35±0.06 ppm respectively. Due to the wide inter-laboratory variation in workup, GC conditions, detection method, and quantitation algorithms used, no one set of factors stood out as the cause of the variation in results.     

Epimutational effects of electronic cigarettes

Environmental Science and Pollution Research - Electronic cigarettes (e-cigarettes), since they do not require tobacco combustion, have traditionally been considered less harmful than conventional...     

Revisiting nitrous acid (HONO) emission from on-road vehicles: A tunnel study with a mixed fleet

Nitrous acid (HONO) is an important precursor of OH radicals in the atmosphere. In urban areas, emissions from vehicles are the main source of air pollutants, including reactive nitrogen. Previously reported emission ratios of HONO (HONO/NO_x) from vehicles were measured in the late 1990s and need to be updated due to the significant changes in emission control technologies. We measured the emission ratio of a fleet of vehicles (38% diesel on average) from March 11 to 21, 2015, in a road tunnel in Hong Kong. The emission ratio of 1.24% (±0.35%) obtained is greater than the commonly adopted 0.8% or 0.3%. The elevated emission ratio is found to be related to the presence of vehicles equipped with diesel particle filters (DPFs). Positive correlation between HONO and black carbon (BC) shows that HONO and BC were emitted together, while the lack of correlation or even anticorrelation between HONO/NO_x and BC indicates that the BC-mediated conversion of NO₂ to HONO in the dark was insignificant in the immediate vicinity of the emission sources.

Implications: Vehicular emission is a key source for HONO in the urban atmosphere. However, the most commonly used emission ratio HONO/NO_x in modeling studies was measured more than 15 years ago. Our tunnel study suggests that a mixed fleet nowadays has a higher emission ratio, possibly because of the diesel particle filter (DPF) retrofit program and the growing share of Euro IV or more advanced diesel vehicles. Our study also provides new insight into the role of black carbon in HONO formation from vehicles.     

Carbon dioxide mineralization process design and evaluation: concepts,case studies,and considerations

Numerous carbon dioxide mineralization (CM) processes have been proposed to overcome the slow rate of natural weathering of silicate minerals. Ten of these proposals are mentioned in this article. The proposals are described in terms of the four major areas relating to CM process design: pre-treatment, purification, carbonation, and reagent recycling operations. Any known specifics based on probable or representative operating and reaction conditions are listed, and basic analysis of the strengths and shortcomings associated with the individual process designs are given in this article. The processes typically employ physical or chemical pseudo-catalytic methods to enhance the rate of carbon dioxide mineralization; however, both methods have its own associated advantages and problems. To examine the feasibility of a CM process, three key aspects should be included in the evaluation criteria: energy use, operational considerations as well as product value and economics. Recommendations regarding the optimal level of emphasis and implementation of measures to control these aspects are given, and these will depend very much on the desired process objectives. Ultimately, a mix-and-match approach to process design might be required to provide viable and economic proposals for CM processes.     

Public perception of locally unwanted facilities in Hong Kong: implications for conflict resolution

This paper aims to investigate factors affecting public attitude towards the siting of locally unwanted land uses (LULUs) and to explore the possible strategies to resolve such conflicts. Three questionnaire surveys were undertaken in communities with different siting experiences and socio-economic profiles. Over 750 individuals were successfully interviewed in each study district. The three communities were found to share similar risk beliefs but show variations in the level of awareness of and response to LULUs. In communities with a disproportionate share of LULUs, many residents did not trust the government in handling LULU issues and thought that the siting process was unfair. The results of the binary logistic regression analysis show that people are likely to oppose the siting of a LULU in their community if they have a negative siting experience, do not perceive the need, accord a high risk to the facility and have a low level of trust in government. The resolution strategies preferred by the public are greater public participation and effective mitigation of risks and impacts, rather than provision of compensation and incentives. All these call for policy-makers to be sensitive to local concerns, engage the public in the process, communicate risks effectively and foster trust building.     

Droplet digital PCR is a cost-effective method for analyzing long cell-free DNA in maternal plasma: Application in preeclampsia

Objective

Long cell-free DNA (cfDNA) can be found in the plasma of pregnant women and cancer patients. We investigated if droplet digital PCR (ddPCR) can analyze such molecules for diagnostic purposes using preeclampsia as a model.

Method

Plasma samples from ten preeclamptic and sixteen normal pregnancies were analyzed. Two ddPCR assays targeting a single-copy gene, VCP, and one ddPCR assay targeting LINE-1 repetitive regions were used to measure the percentages of long cfDNA >533, 1001, and 170 bp, respectively. The LINE-1 assay was developed as guided by in silico PCR analyses to better differentiate preeclamptic and normal pregnancies.

Results

Preeclamptic patients had a significantly lower median percentage of long cfDNA than healthy pregnant controls, as determined by the LINE-1 170 bp assay (28.9% vs. 35.1%, p < 0.0001) and the VCP 533 bp assay (6.6% vs. 8.7%, p = 0.014). The LINE-1 assay provided a better differentiation than the VCP 533 bp assay (area under ROC curves, 0.94 vs. 0.79).

Conclusion

ddPCR is a cost-effective approach for unlocking diagnostic information carried by long cfDNA in plasma and may have applications for the detection of preeclampsia. Further longitudinal studies with larger cohorts are required to assess the clinical utility of this test.     

Understanding the connections between relationship conflict and performance: The intervening roles of trust and exchange

Research shows that relationship conflict has a negative impact on job performance. There is scant theoretical work, however, explaining the interpersonal dynamics that lead to this outcome. A conceptual model is developed that explores how relationship conflict impacts performance through its effects on trust and exchange. We argue that relationship conflict has a detrimental effect on trust motivating coworkers to rely more on calculus‐based trust than on relationship‐based trust. This, in turn, affects the form of exchange coworkers use with one another, leading them to rely on negotiated exchange to the exclusion of reciprocal exchange. This kind of exchange relationship, finally, affects in‐role, extra‐role, and attitudinal outcomes. The literature shows that superordinate goals can mitigate relationship conflict and we use social and self‐categorization theories to explain and explore this effect on both relationship conflict and trust. How trust and exchange might change over time is also explored. Copyright © 2009 John Wiley & Sons, Ltd.     

Carbon content of common airborne fungal species and fungal contribution to aerosol organic carbon in a subtropical city

Interest in the role and contribution of fungi to atmospheric aerosols and processes grows in the past decade. Substantial data or information such as fungal mass or carbon loading to ambient aerosols is however still lacking. This study aimed to quantify the specific organic carbon content (OC per spore) of eleven fungal species commonly found airborne in the subtropics, and estimated their contribution to organic carbon in aerosols. The specific OC contents showed a size-dependent relationship (r = 0.64, p < 0.05) and ranged from 3.6 to 201.0 pg carbon per spore or yeast cell, giving an average of 6.0 pg carbon per spore (RSD 51%) for spore or cell size less than 10 μm. In accounting for natural variations in the composition and abundance of fungal population, weighted-average carbon content for field samples was adopted using the laboratory determined specific OC values. An average of 5.97 pg carbon per spore (RSD 3.8%) was enumerated from 28 field samples collected at the university campus. The mean fungal OC concentration was 3.7, 6.0 and 9.7 ng m^?3 in PM_2.5, PM_2.5–10 and PM₁₀, respectively. These corresponded to 0.1%, 1.2% and 0.2% of the total OC in PM_2.5, PM_2.5–10 and PM₁₀, respectively. In the study period, rain provided periods with low total OC but high fungal prevalence and fungi contributed 7–32% OC in PM_2.5–10 or 2.4–7.1% OC in PM₁₀. More extensive studies are deserved to better understand the spatial-, temporal- and episodic dependency on the fungal OC contribution to the atmospheric aerosols.