Novel RNA genosensor based on highly stable gold nanoparticles decorated phosphorene nanohybrid with graphene for highly sensitive and low-cost electrochemical detection of coconut cadang-cadang viroid.

Coconut cadang-cadang viroid (CCCVd) is an infectious single-stranded RNA (ssRNA) pathogen, which leads directly to the death of a large number of coconut palm trees and heavy economic loss to coconut farmers. Herein, a novel electrochemical impedance RNA genosensor is presented based on highly stable gold nanoparticles (AuNPs) decorated phosphorene (BP) nanohybrid with graphene (Gr) for highly sensitive, low-cost, and label-free detection of CCCVd. BP-AuNPs are environmentally friendly prepared by ultrasonic-assisted liquid-phase exfoliation of black phosphorus, accompanying direct reduction of chloroauric acid. Gr/BP-AuNPs are facilely prepared by the in situ growth of AuNPs onto the BP surface and its nanohybrid with Gr to improve environmental stability of BP. Gr/BP-AuNP-based RNA genosensor is fabricated by immobilizing the thiol-functionalized single-stranded DNA (ssDNA) oligonucleotide probe onto the surface of Gr/BP-AuNP-modified glassy carbon electrode via gold-thiol interactions, which served as an electrochemical genosensing platform for the label-free impedance detection of CCCVd by hybridization between the functionalized ssDNA probe and the complementary CCCVd ssRNA sequence in a wide linear range from 1.0 × 10-11 to 1.0 × 10-7 M with a low limit of detection of 2.8 × 10-12 M. This work supplies an experimental support and theoretical direction for the fabrication of RNA biosensors based on graphene-like materials and potential application for a specific diagnosis of plant RNA viral disease in Arecaceae planting industry.

Assessment of Aging Impact on Wax Crystallization in Selected Asphalt Binders.

For a better understanding of the changing trend in crystalline components of asphalt binders, asphalt binders originating from the SHRP Materials Reference Library with different oxidation degrees (unaged, 20 h PAV, and 60 h PAV) were prepared. The native asphalt binders and their oxidized residues were characterized by liquid-state nuclear magnetic resonance (NMR) spectroscopy and high-temperature gas chromatography (HTGC). The results showed that, compared with other carbon types, the content of internal methylene carbons of long paraffinic chains between different SHRP binders was quite different. The NMR average length of a long paraffinic internal methylene chain showed a good correlation with the wax content obtained at -20 °C using the methyl ethyl ketone (MEK) precipitation method and also the recently developed variable-temperature Fourier-transform infrared spectroscopy (VT-FTIR) method. In most cases, the average length of straight internal methylene carbons of a long paraffinic chain terminated by a methyl group increased with the oxidation of the asphalt binder. However, the difference caused by oxidation was significantly smaller than the difference caused by the source of the asphalt binder. In general, oxidation will make the n-alkanes distributed in asphalt binder fall within a narrower range. The carbon number of n-alkanes in the asphalt binder generally grew with oxidation.

Is flow control in a space-constrained drainage network effective? A performance assessment for combined sewer overflow reduction.

Recurring combined sewer overflows (CSOs) can have a significant impact on the ecological condition of receiving water bodies. There are several structural measures, like adding retention basins and switching to low impact development solutions, that have been proposed to reduce the number of sewage overflows. Besides, several flow control strategies have been discussed in scientific literature that take advantage of the space within urban drainage networks, which is assumed to be adequate, for temporary storage. The adequacy of such storage space, however, is not a universally valid assumption as a large fraction of drainage networks frequently operate close to their design discharge. In this paper, we investigate the efficacy of flow control for a space-constrained drainage network. We employ a low-cost, heuristic real time control strategy with the use of flow control devices (FCDs) and available in-sewer space to reduce the magnitude of CSOs. We consider the performance of the proposed control strategy and discuss the effect of FCD location on CSO reduction. Our results, based on over 300 rainfall-event simulations, show that the flow control strategy using limited sewer capacity is more efficient during relatively small rainfall events, where the CSO is large enough to enable reduction using the chosen control rules. The CSO is reduced, to varying degrees, for around 80% of rainfall events with peak intensity between 10 and 20 mm h-1. For larger rainfall events, the flow control is more unstable in response to abrupt water release during control operation, which seems to be unavoidable because of the water accumulation effect and the transition to pressurized pipe flow in space-constrained networks. We also found that the flow control performance is highly sensitive to the FCD location - as it depends on the interplay of the peak rainfall intensity and the water level condition immediately upstream of the FCD. The efficacy of a location for flow control is determined by the unfilled capacity (i.e., effective in-sewer storage potential) in the pipe upstream of the FCD during the rainfall peak; furthermore, the location also has to be resistant to the water accumulation effect. Using our analysis, we substantiate two anticipated caveats to flow control strategies when the storage space is limited in a drainage network: diminished performance in CSO reduction and the appearance of additional control-related challenges, which are otherwise mitigated in more spacious networks.

Different activation methods in sulfate radical-based oxidation for organic pollutants degradation: Catalytic mechanism and toxicity assessment of degradation intermediates.

With the continuous development of industrialization, a growing number of refractory organic pollutants are released into the environment. These contaminants could cause serious risks to the human health and wildlife, therefore their degradation and mineralization is very critical and urgent. Recently sulfate radical-based advanced oxidation technology has been widely applied to organic pollutants treatment due to its high efficiency and eco-friendly nature. This review comprehensively summarizes different methods for persulfate (PS) and peroxymonosulfate (PMS) activation including ultraviolet light, ultrasonic, electrochemical, heat, radiation and alkali. The reactive oxygen species identification and mechanisms of PS/PMS activation by different approaches are discussed. In addition, this paper summarized the toxicity of degradation intermediates through bioassays and Ecological Structure Activity Relationships (ECOSAR) program prediction and the formation of toxic bromated disinfection byproducts (Br-DBPs) and carcinogenic bromate (BrO3-) in the presence of Br-. The detoxification and mineralization of target pollutants induced by different reactive oxygen species are also analyzed. Finally, perspectives of potential future research and applications on sulfate radical-based advanced oxidation technology in the treatment of organic pollutants are proposed.

Diversity of Blastocystis subtypes in dogs in different geographical settings.

BACKGROUND: Blastocystis is a ubiquitous, globally distributed intestinal protist infecting humans and a wide range of animals. Several studies have shown that Blastocystis is a potentially zoonotic parasite. A 1996 study reported a 70% Blastocystis prevalence in Brisbane pound dogs while another study found that pet dogs/cats of 11 symptomatic Blastocystis infected patients harboured at least one Blastocystis subtype (ST) in common with the patient. These results raised the possibility that dogs might be natural hosts of Blastocystis. In this study, we aimed to investigate this hypothesis by estimating the prevalence of Blastocystis carriage and characterising the diversity of STs in dogs from three different environmental settings and comparing these STs with the range that humans harbour. METHODS: Two hundred and forty faecal samples from dogs from three different geographical regions with varying levels of socio-economic development and sanitation, namely i) 80 pet and pound dogs from Brisbane, Australia, ii) 80 semi-domesticated dogs from Dong Village, Cambodia and iii) 80 stray dogs from the densely populated cities of Sikkim, Delhi and Mumbai in India, were screened for Blastocystis using PCR and subtyped based on the "barcode region" of the small subunit ribosomal RNA (SSU rRNA) gene. RESULTS: The prevalence of Blastocystis in dogs from Brisbane and Cambodia was 2.5% (2/80) and 1.3% (1/80), respectively, in contrast to 24% (19/80) in stray dogs from India. Stray dogs in India carried a diverse range of Blastocystis STs including ST 1, 4, 5 and 6 while the dogs from Brisbane carried only ST1 and one Cambodian dog carried ST2. CONCLUSION: The results suggest there is geographical variation in Blastocystis prevalence and STs between dog populations as reported in human studies. In addition, the greater diversity of STs and higher prevalence of Blastocystis in Indian stray dogs compared to pet/pound and community dogs in Australia and Cambodia could reflect close proximity to humans and other animals and exposure to their faeces. It appears that dogs are not natural hosts for Blastocystis but rather are transiently and opportunistically infected with a diversity of STs.