25 research outputs found

    Effects of two ecological earthworm species on atrazine degradation performance and bacterial community structure in red soil

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    Vermicomposting is an effective and environmentally friendly approach for eliminating soil organic contamination. Atrazine is one of the most commonly applied triazinic herbicides and frequently detected in agricultural soils. This study investigated the roles and mechanisms of two earthworm species (epigeic Eisenia foetida and endogeic Amynthas robustus) in microbial degradation of atrazine. Both earthworms accelerated atrazine degradation performance from 39.0% in sterile soils to 94.9%–95.7%, via neutralizing soil pH, consuming soil humus, altering bacterial community structure, enriching indigenous atrazine degraders and excreting the intestinal atrazine-degrading bacteria. Rhodoplanes and Kaistobacter were identified as soil indigenous degraders for atrazine mineralization and stimulated by both earthworm species. A. robustus excreted the intestinal Cupriavidus and Pseudomonas, whereas Flavobacterium was released by E. foetida. This study provides a comprehensive understanding of the distinct effects of two earthworm species on soil microbial community and atrazine degradation, offering technical supports to apply vermicomposting in effective soil bioremediation

    Modeling the Performance of Aircraft Utilizing Maintenance Free Operating Periods

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    AbstractMaintenance free operating period (MFOP) philosophy is proposed by the UKMilitary Aerospace industry, which has advantages for both the operation andmaintenance of aircraft. An MFOP is a period of time for which the aircraft will operate without failureandwithout the need for anymaintenance, however, faults and minorplanned, contractually agreed maintenance are permissible.Each MFOP isfollowed by a MaintenanceRecovery Period (MRP) during which maintenance is performed on the aircraft tocorrect any failures which have occurred, carry out servicing and prepare the aircraft forthe next period of operation. There are several advantages to operating aircraft in thismanner. The first is that it will be known, with a high degree of confidence, howmany products will be available for operational purposes at any time. This enablesaccurate, effective mission planning. However, the aircraft must be designed tooperate in this way and be able to carry faults in the MFOP withoutan unacceptable risk. This paper will model the performance of aircraft utilizing maintenance freeoperating periods and explore issues relating to the design and operation of aircraft inthis manner. An example is provided to expatiate on the proposed approach

    Hyperphosphorylation of Tau Protein in Hippocampus of Central Insulin-Resistant Rats is Associated with Cognitive Impairment

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    Background: Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Peripheral insulin resistance increases the risk for memory impairment and the development of AD. Objective: This study aims to assess changes in cognitive functions and the level of hyperphosphorylated tau proteins in central insulin-resistant rats. Methods: An in vivo central insulin-resistant (CIR) animal model was generated through intracerebroventricular injection of streptozotocin (STZ) into insulin-resistant (IR) rats that were induced by feeding a high-glucose/-protein/-fat diet. The Morris water maze test was used to assess changes in cognitive functions, pathological changes in the cornu ammonis 1 (CA1) region of the hippocampus were detected by immunohistochemistry, and the phosphorylation levels of tau proteins at specific sites were determined by Western blot analysis. Results: The escape latency time in the Morris water maze test was significantly prolonged; the number of phosphorylated tau proteins in the CA1 region of the hippocampus was significantly increased; and the phosphorylation levels of tau proteins at Ser199, Thr205, Thr212, Thr217 and Ser396 were significantly elevated in the CIR group compared with the IR and control groups. Conclusion: This study provides direct evidence that CIR plays an important role in AD pathogenesis by facilitating tau hyperphosphorylation

    Development and Field Application of a Diffusive Gradients in Thin-Films Passive Sampler for Monitoring Three Polycyclic Aromatic Hydrocarbon Derivatives and One Polycyclic Aromatic Hydrocarbon in Waters

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    Polycyclic aromatic hydrocarbon (PAH) derivatives are widely present in the environment, and some are more hazardous than their parent PAHs. However, compared to PAHs, PAH derivatives are less studied due to challenges in monitoring as a result of their low concentrations in environmental matrixes. Here, we developed a new passive sampler based on diffusive gradients in thin films (DGT) to monitor PAH derivatives and PAHs in waters. In the laboratory study, the XAD18-DGT device exhibited high adsorption rates and was demonstrated to be suitable for deployment in environmental waters on the timescale of months. The diffusion coefficients, D, were 5.30 × 10−6 cm2 s−1, 4.51 × 10−6 cm2 s−1, 4.03 × 10−6 cm2 s−1 and 3.34 × 10−6 cm2 s−1 for 9-fluorenone (9-FL), 1-chloroanthraquinone (1-CLAQ), 9-nitroanthracene (9-NA) and phenanthrene (Phe), respectively, at 25 °C. The DGT device’s performance was independent of pH, ionic strength, deployment time and storage time, indicating it can be widely used in natural waters. In the field study, the target pollutant concentrations measured by the DGT are in good accordance with those determined via grab sampling. Then, the DGT devices were utilized to quantify PAH derivatives and PAHs in several rivers in Hefei, China. This work demonstrates the feasibility of using the DGT technique to detect trace PAH derivatives and PAHs in waters

    Insecticidal Activity of 11 Bt toxins and 3 Transgenic Maize Events Expressing Vip3Aa19 to Black Cutworm, Agrotis ipsilon (Hufnagel)

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    Black cutworm (BCW), Agrotis ipsilon (Hufnagel), is an occasional pest of maize that can cause considerable economic loss and injury to corn seedlings. This research mainly assessed the susceptibility of BCW neonates to 11 Bt toxins (Cry1Ab, Cry1Ac, Cry1Ah, Cry1F, Cry1Ie, Cry1B, Cry2Aa, Vip3_ch1, Vip3_ch4, Vip3Ca2, Vip3Aa19) by exposing neonates to an artificial diet containing Bt toxins and evaluated the efficacy of three transgenic maize events (C008, C009, C010) expressing Vip3Aa19 toxin against BCW. The toxin-diet bioassay data indicated that Vip3Aa19 protein (LC50 = 0.43 μg/g) was the most active against BCW. Chimeric protein Vip3_ch1 (LC50 = 5.53 μg/g), Cry1F (LC50 = 83.62 μg/g) and Cry1Ac (LC50 = 184.77 μg/g) were less toxic. BCW was very tolerant to the other Bt toxins tested, with LC50 values more than 200 μg/g. Greenhouse studies were conducted with artificial infestations at the whorl stage by placing second-instar BCW larvae into whorl leaf and the fourth-instar larvae at the base of maize seedings. These results suggest that these transgenic maize events expressing Vip3Aa19 can provide effective control for BCW
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