Watching Iron Nanoparticles Rust: An In Situ X-ray Absorption Spectroscopic Study

NSERCPeer ReviewedIron nanoparticles and iron oxide nanoparticles are among the most commonly studied nanomaterials because of their applications in fields ranging from catalysis to ferrofluids. However, many synthetic methods give iron nanoparticles with large size distributions, and it is difficult to follow the kinetics of iron nanoparticle oxidation reactions and the relative speciation of iron oxidation states in real time. Herein, we introduce a simple approach of controlling the sizes of Fe@FexOy nanoparticles and a novel method for following Fe@FexOy nanoparticle oxidation in situ in liquid solutions by Fe K- and L-edge X-ray absorption near-edge structure (XANES) spectroscopy. XANES results show that these Fe@FexOy nanoparticles have similar XANES spectra before exposure to air. In situ XANES measurements allow for quantitative oxidation kinetics of different nanoparticle sizes to be followed; results show that the rate of Fe(0) oxidation increases with a decrease in average nanoparticle size. However, the rate of Fe core size depletion was found to be ca. 0.02 nm/min for all the nanoparticle systems studied. This suggests similar oxidation mechanisms are at work for all the particle sizes studied. This work shows that in situ liquid cell XANES can be used to follow oxidation state and coordination environment changes in Fe NP dispersions

Flexible versus simple trade-in strategy for remanufacturing

Some enterprises recently start to offer the flexible trade-in option to attract customers from competitors, in contrast to the simple one that only allows them to return used products to the same manufacturers for new. Based on analytical and numerical analyses, this study compares the environmental impacts of two trade-in strategies (simple versus flexible) in combination with different carbon tax policies. From the perspective of consumer switching behaviour, a Hotelling model with two market segments is established. Under the flexible trade-in strategy, the carbon emission of enterprises turns out to be significantly higher than that under the simple trade-in strategy. An appropriate carbon tax policy, especially with preferential tax rates on green products, is capable of guiding enterprises to choose a more environment-friendly trade-in strategy included in the model. The findings fill the research gap in comparing the pros and cons of simple and flexible trade-in strategies in terms of sustainable development, and provide managers and policy-makers the insights on how to promote the healthy development of the remanufacturing industry with trade-in strategizing and carbon taxation

Sharing economy of electric vehicle private charge posts

The increasing popularity of electric vehicles (EVs) leads to heightened demand for the charging infrastructure. More and more EV drivers install private charge posts, which can now be shared with others through certain mobile apps. This emerging phenomenon is becoming a prominent part of the sharing economy. To examine the impacts of post sharing on EV charging market, this study establishes game theory models on consumer choices among private, public, and shared options. Such peer-to-peer sharing and collaborative consumption redistribute the installation and operation costs of private charge posts in proportion to their increased utilization. Numerical analyses suggest that the sharing mode provides a win-win solution for charge post owners and non-owner consumers, as well as electricity distributors and public charging infrastructure operators. In the case of China, the estimated saving for charge post owners is between 20% and 50%, which can be translated into more non-government investment in the EV industry chain. The findings provide supporting evidence for policy-makers to promote private charge post sharing, especially with certain consumer subsidization at a reasonable level

Exempting battery electric vehicles from traffic restrictions: Impacts on market and environment under Pigovian taxation

In busy metropolitan areas, traffic restrictions based on the last digits of license plates effectively ease traffic jams and improve air quality. Recently, policy-makers in China exempted battery electric vehicles (BEV) from traffic restrictions to promote their diffusion in place of conventional vehicles (CV). To examine the impacts of such an exemption on consumers and manufacturers as well as the environment, this study models the duopoly competition between BEV and CV manufacturers as a Cournot game. The numerical analyses compare three traffic restriction policies concerning BEV and CV, and reveal the pros and cons of each. In particular, the BEV-exempted policy promotes customer adoption, industry development, and environment protection with the least consumer surplus loss. As supplementary measures, relevant vehicle purchase tax and carbon tax may make such a policy more effective, respectively, in short and long terms

Monitoring human cytomegalovirus infection with nested PCR: comparison of positive rates in plasma and leukocytes and with quantitative PCR

<p>Abstract</p> <p>Background</p> <p>Human cytomegalovirus (HCMV) infection poses a significant health threat to immunocompromised individuals. Here we performed this study to set up a highly sensitive nested PCR method applicable for detecting HCMV infection in high-risk individuals. In this work, 106 blood specimens from 66 patients with potential HCMV infection were obtained. Total DNA was extracted separately from plasma and peripheral blood leukocytes (PBL) of each sample. HCMV DNA was detected in parallel by nested PCR and quantitative real-time PCR (qRT-PCR), and the results were compared.</p> <p>Results</p> <p>Serial dilution test revealed that the detection limit of nested PCR was 180 copies/ml. The nested PCR showed a higher positive rate than qRT-PCR (34.9% vs. 12.3%, p < 0.001). The positive rate of nested PCR based on PBL DNA was significantly higher than that based on plasma DNA (34.9% vs. 18.9%, p = 0.002). Of the 14 patients with serial samples, 11 were positive for HCMV DNA in PBL while only 7 were positive in plasma. Moreover, for each patient, nested PCR using PBL DNA also detected more positive samples than that using plasma DNA.</p> <p>Conclusion</p> <p>Combined use of nested PCR with PBL DNA is highly sensitive in defining HCMV infection. This assay is particularly useful in the case of quantification not essential.</p

Impact of agricultural activities on pesticide residues in soil of edible bamboo shoot plantations

Edible bamboo shoot is one of the most important vegetables in Asian countries. Intensive agricultural management measures can cause many negative influences, such as soil acidification and excessive pesticide residues. In the present study, more than 300 soil samples were collected from edible bamboo shoot plantations in six areas throughout Zhejiang province, China, to investigate the soil pesticide pollution and its change after different agricultural activities. Thirteen organic chemicals were detected; nine less than that detected during a similar study executed in 2003–2004. All the detected residues were far below the Chinese national environmental standards for agricultural soils. The pesticide residues in bamboo plantations showed a decline over the past decade. Organic materials used for mulching and plantation’s background of being formerly a paddy field are two important factors increasing the pesticide residues. Conversely, lime application to acidified soil and mulching with uncontaminated new mountain soil could decrease the residues significantly. Our results indicated that the current agricultural activities are efficient in reducing pesticide residues in the soil of bamboo shoot plantations and should be further promoted

miR-181a increases FoxO1 acetylation and promotes granulosa cell apoptosis via SIRT1 downregulation.

Oxidative stress impairs follicular development by inducing granulosa cell (GC) apoptosis, which involves enhancement of the transcriptional activity of the pro-apoptotic factor Forkhead box O1 (FoxO1). However, the mechanism by which oxidative stress promotes FoxO1 activity is still unclear. Here, we found that miR-181a was upregulated in hydrogen peroxide (

Growth of single-walled carbon nanotubes from well-defined POSS nanoclusters structure

High-quality single-walled carbon nanotubes (SWNTs) with narrow diameter distribution can be generated from well-defined Si8O12 nanoclusters structure which form from thermal decomposition of chemically modified polyhedral oligomeric silsesquioxane (POSS). The nanosized SixOy particles were proved to be responsible for the SWNT growth and believed to be the reason for the narrow diameter distribution of the as-grown SWNTs. This could be extended to other POSS. The SWNTs grown from the nanosized SixOy particles were found to be semiconducting enriched SWNTs (s-SWNTs). A facile patterning technology, direct photolithography, was developed for generating SWNT pattern, which is compatible to industrial-level fabrication of SWNTs pattern for device applications. The metal-free growth together with preferential growth of s-SWNTs and patterning in large scale from the structure-defined silicon oxide nanoclusters not only represent a big step toward the control growth of SWNTs and fabrication of devices for applications particularly in nanoelectronics and biomedicine but also provide a system for further studying and understanding the growth mechanism of SWNTs from nanosized materials and the relationship between the structure of SWNT and nonmetal catalysts