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Результаты 3611-3620 из 4,936
The research of synthesis and bioactivity of the novel indanedione anticoagulant rodenticides Полный текст
2019
Chen, Feng | Zhang, Tong | Qu, Chuang | Wang, Jinming | Su, Hua | Shi, Ruofan | Zhu, Xingyu
Three new anticoagulant rodenticides R₁, R₂, and R₃ were designed. The containing fluorine acute toxicity groups was added to 1,3-indandione derivative. Analysis method of synthesized anticoagulant rodenticides were IR, ¹H NMR. Acute bioactivity of the new rodenticides was evaluated, including the coefficient of absorb food and median lethal dose (LD₅₀). Average coefficient of absorbed food for R₁ was 0.54 and LD₅₀ of R₁ was 2.15 mg/kg. Average coefficient of absorbed food for R₂ was 0.59 and the acute oral LD₅₀ of R₂ was 2.65 mg/kg. Average feeding coefficient of R₃ was 0.68 and the acute oral LD₅₀ of R₃ was 3.12 mg/kg. Experiments showed that rat’s death peak was at about 72 h and rodenticides had good characteristics of acute medicine. The LD₅₀ of three new fluoride anticoagulant rodenticides showed that they had good palatability for big white rats, and they had a strong poison effect on rodent. The result of all experiments proved that the synthesis of 1,3-indan diketone used as parent compound of new anticoagulant rodenticides could replace the current 4-hydroxyl coumarin as parent compound of the second-generation anticoagulant rodenticides. 1,3-Indan diketone would be widely used as parent compound of anticoagulant rodenticides.
Показать больше [+] Меньше [-]Occurrence, seasonal variation and environmental impact of phosphorus flame retardants in a large scale wastewater treatment plant Полный текст
2019
Liu, Zhineng | Deng, Mingjun | Wu, Qihang | Kuo, Dave T. F. | Zeng, Lixi | Wang, Zhu | Zhang, Ying | Liu, Xinyu | Liu, Shengyu | Liang, Junyan | Hu, Xiaodong | Mai, Bixian
The occurrence, seasonal variation and emission of nine widely used phosphorus flame retardants (PFRs) were investigated in a wastewater treatment plant (WWTP) located in Guangzhou, China, over 1 year. Results showed that PFRs were widely detected in wastewater and sewage sludge. Tris(2-chloroisopropyl) phosphate (TCIPP) was the most dominant PFRs in influent, effluent, and sludge. Significant seasonal variation of total PFRs in the influent was observed (p < 0.05). However, no significant seasonal variation found in chlorinated and alkyl PFRs. The emission of PFRs was comparable with the previously reported values of decabromodiphenyl ether in WWTPs. Risk quotient for PFRs showed low eco-toxicity risk in effluent for aquatic organisms. Since the removal efficiency of total PFRs was less than 30% and the use of PFRs had been increasing, continuous monitoring of the environmental impact on the receiving water is still needed.
Показать больше [+] Меньше [-]Study of organochlorine pesticides and heavy metals in soils of the Juarez valley: an important agricultural region between Mexico and the USA Полный текст
2019
Núñez-Gastélum, José A. | Hernández-Carreón, Stephanie | Delgado-Ríos, Marcos | Flores-Marguez, Juan Pedro | Meza-Montenegro, María M. | Osorio-Rosas, Claudia | Cota-Ruiz, Keni | Gardea-Torresdey, Jorge L.
The Juarez Valley is an important agricultural region in northern Mexico, conveniently organized into three modules (I to III). For decades, their soils have been exposed to organochlorine pesticides (OCPs) and also have been irrigated with wastewaters, which may contain heavy metals. Nowadays, there is very limited information regarding the presence of OCPs and heavy metals in these soils. Thus, the aim of this study was to diagnose these soils for OCPs and heavy metal content by using gas chromatography coupled with electron micro-capture detector and atomic absorption spectrometry, respectively. The results indicated that 4,4′-dichlorodiphenyldichloroethylene and 4,4′-dichlorodiphenyltrichloroethane were primarily disseminated across the three modules since they were found in 100% and 97% of the analyzed soils, respectively. According to international regulations, none of the determined OCP concentrations are out of the limits. Additionally, the Cu, Zn, Fe, Pb, and Mn were found in all sampled soils from the three modules. The highest concentration of Fe was found in module II (1902.7 ± 332.2 mg kg⁻¹), followed by Mn in module III (392.43 ± 74.43 mg kg⁻¹), Zn in module I (38.36 ± 26.57 mg kg⁻¹), Pb in module II (23.48 ± 6.48 mg kg⁻¹), and Cu in module I (11.04 ± 3.83 mg kg⁻¹) (p ≤ 0.05). These values did not exceed the limits proposed by international standards. The Cd was detected in most of the analyzed soils and all their values, with an average of 2 mg kg⁻¹, surpassed the Mexican standards (0.35 mg kg⁻¹). This study has mapped the main OCPs and heavy metals in the Juarez Valley and can serve as a starting point to further monitor the behave of xenobiotics. Since these recalcitrant compounds might be bio-accumulated in biological systems, further analytical methods, as well as remediation techniques, should be developed.
Показать больше [+] Меньше [-]Effects of combined traffic noise on the synaptic ultrastructure and expressions of p-CaMKII and NMDAR1 in the hippocampus of young SD rats Полный текст
2019
Di, Guoqing | Liu, Guangxiang | Xu, Yaqian | Kim, Hakbong
In order to explore the effects of combined traffic noise (CTN) on learning and memory function, young Sprague-Dawley (SD) rats were exposed to CTN from highway and high-speed railway for 52 days, whose day-night equivalent continuous A-weighted sound pressure level (Ldₙ) was 70 dB(A) (corresponding sound pressure level was 80 dB). The synaptic ultrastructure and the expressions of phosphorylated calcium/calmodulin-dependent protein kinase II (p-CaMKII) and N-methyl-D-aspartate receptor 1 (NMDAR1 or NR1) in the hippocampus were tested by transmission electron microscopy (TEM) and Western blot, respectively. Results showed that there was no significant difference in the synaptic ultrastructure and the expressions of p-CaMKII and NR1 in the hippocampus of young rats between the experimental group and control group. Compared with single high-speed railway noise (HSRN) with Ldₙ of 70 dB(A), CTN had less influences on learning and memory function, which was closely related to smaller intermittency of CTN and less anxiety caused by CTN. In comparison with white noise with a sound pressure level of 80 dB, CTN had less impacts on learning and memory function, which was mainly associated with CTN’s smaller R-weighted sound pressure level based on rats’ auditory sensitivity.
Показать больше [+] Меньше [-]Lanthanum ferrite nanoparticles modification onto biochar: derivation from four different methods and high performance for phosphate adsorption Полный текст
2019
Yang, Bei | Feng, Yanfang | Yu, Yingliang | He, Shiyin | Liu, Hao | Xue, Lihong | Yang, Linzhang
To effectively remove phosphate pollution and convectively reuse phosphate resource, straw biochar was firstly functionalized with lanthanum ferrite (LaFeO₃) via four different methods, including one-step co-precipitation (S-C), two-step co-precipitation (B-C), one-step impregnation (S-E), and two-step impregnation (B-E). LaFeO₃/biochar was characterized systematically by a series of characterization methods. The influence of preparation methods, operation conditions on adsorption process, and the regenerability were studied. The products prepared by four methods displayed different physical morphology and chemical analysis proved chemical composition were similar. LaFeO₃/biochar exhibited high adsorption capacity, the pseudo-second-order and Sips models were fitted for the adsorption equilibrium. The LaFeO₃/biochar exhibited outstanding phosphate adsorption performance with pH values ranging from 2.3 to 10.6; La ions release was similarly negligible, when pH value was higher than 5.27. The adsorption mechanism was studied and inferred that La species is the key to adsorption ability. The results obtained provide better understanding of the adsorption phenomena and indicate the available preparation technologies and potential usefulness of LaFeO₃/biochar for removing phosphate pollution. Graphical abstract “.”
Показать больше [+] Меньше [-]Acute toxicity testing of TiO2-based vs. oxybenzone-based sunscreens on clownfish (Amphiprion ocellaris) Полный текст
2019
Barone, Alexandra N. | Hayes, Caitlyn E. | Kerr, James J. | Lee, Ryan C. | Flaherty, Denise B.
Given the prevalence of skin cancer, sunscreens are recommended by dermatologists including the American Academy of Dermatology to protect skin from harmful ultraviolet rays. Unfortunately, this leads to an estimated 14,000 tons of sunscreen entering waterways each year. Many of the chemicals in sunscreens, such as oxybenzone and benzophenone-2, are indicated to have adverse effects on corals and other aquatic life. As an eco-conscious alternative, physical barrier sunscreens, such as non-nano-titanium dioxide (TiO₂), have been suggested as a replacement. This study examines the impact of a non-nano-TiO₂-based sunscreen over a nationally sold brand of sunscreen containing oxybenzone, on clownfish (Amphiprion ocellaris). Animals were evaluated for mortality, swimming behavior, and feeding behavior. Our data indicate that at an exposure level of 100 mg/L oxybenzone-containing sunscreen had a negative impact on mortality, leading to 25% death by the end of the 97-h testing period. Negative impacts on behavior were even more dramatic for the 100 mg/L oxybenzone-containing sunscreen, with 100% of the animals failing to feed over the first 49 h of testing and 100% of animals demonstrating abnormal swimming behavior over the entire testing period. By comparison, the non-nano-(TiO₂) sunscreen at 100 mg/L had little (6.7%) negative impact on mortality and feeding. While swimming behavior was disrupted during the first 25 h of testing (26.7% abnormal movement), animals recovered well over the remainder of the testing period (out to 97 h).
Показать больше [+] Меньше [-]Para-aminopropiophenone (PAPP) in canid pest ejectors (CPEs) kills wild dogs and European red foxes quickly and humanely Полный текст
2019
Allen, Benjamin L.
Lethal control remains an important approach to mitigating the impacts of predators on livestock and threatened fauna. This occurs in Australia, where wild dogs (Canis familiaris) and European red foxes (Vulpes vulpes) are commonly subjected to broad-scale poisoning programs. Ongoing refinement of lethal tools has led to the recent development of manufactured poison baits containing para-aminopropiophenone (PAPP). Canid pest ejectors (CPEs) have also been recently registered for use and are a target-specific poison delivery device; yet, there has been no confirmation that PAPP delivered via ejectors will provide similar efficacy to PAPP delivered via manufactured baits. We tested the efficacy of PAPP in ejectors on wild dogs (1000-mg dose) and foxes (400-mg dose). Time-to-death, physical signs of poisoning and other related factors were assessed. Ten of 11 (91%) wild dogs used in controlled trials died within 3 h after PAPP administration; the mean time to unconsciousness was 65 min and the mean time to death was 84 min. Three of four (75%) foxes also died within 3 h after PAPP administration; their mean time to unconsciousness was 78 min, and their mean time to death was 121 min. Carcasses of eight deceased wild dogs and one fox were found during field trials, with distances between the nearest triggered ejector and the deceased animal ranging from 30 to 200 m. The presence of de-oxygenated blood in all necropsied carcasses and photographic evidence of triggered ejectors unequivocally demonstrated that using powdered PAPP in ejectors produces rapid anoxia and death in both wild dogs and foxes. Although anxiety and accompanying behaviours were observed in wild dogs (but not foxes), the use of PAPP offers a humane, additional option for the control of wild canids.
Показать больше [+] Меньше [-]Synergistic oxidative impact of aluminum chloride and sodium fluoride exposure during early stages of brain development in the rat Полный текст
2019
Kinawy, Amal A.
Aluminum is widely used in industry and in cooking utensils, especially in countries with low economic and social standards. Fluoride is also used in industry, a major component of toothpaste and is added to the drinking water in many countries to fight teeth decay and cavities. Consequently, the coexistence of aluminum and fluoride is highly probable. Growing evidence indicates that environmental pollutants during the early stages of embryonic development may reprogram the offspring’s brain capabilities to encounter oxidative stress during the rest of their postnatal life. This study investigated the impact of sodium fluoride (NaF, 0.15 g/L) and aluminum chloride (AlCl₃, 500 mg/L) added, individually or in combination, to the deionized drinking water starting from day 6 of gestation until just after weaning, or until the age of 70 days postnatal life. A significant decline was observed in tissue contents of vitamin C, reduced glutathione, GSH/GSSH ratio, and the total protein, as well as in the activities of Na⁺/K⁺-ATPase and superoxide dismutase (SOD) in almost all cases. On the contrary, lipid peroxidation and NO, as total nitrate, exhibited a significant increase in comparison with the corresponding control. Based on the present results, administration of Al and NaF, alone or in combination abated the quenching effects of the antioxidant system and induced oxidative stress in most brain regions under investigation. In conclusion, aluminum and fluoride are very noxious environmental pollutants that interfere with the proper functions of the brain neurons and their combination together aggravates their hazard.
Показать больше [+] Меньше [-]Environmental performance of Chinese listing manufacturing enterprise: from investment perspective Полный текст
2019
Hu, Dan | Feng, Chenpeng | Liang, Liang | Wu, Peng | Du, Yuneng
With decades of high-speed economic miracle, China inevitably encountered with environmental pressure and sustainable development problem. As the main carrier of the environmental responsibility, Chinese government set series of regulations and standards to supervise and guide enterprise to fulfill this challenge emission reduction task. Based on data envelopment analysis (DEA) approach, this paper focuses on air pollutant highly emission manufacturing tycoons to figure out “whether the yearly billions environmental input really worth it?” during 2014 to 2016. Unlike previous studies mainly from consumption perspective and got macro-regional evidence, we choose micro-enterprise to analyze individual environmental performance and draw general conclusions. Possible suggestions are also proposed for various industries and some salient enterprises.
Показать больше [+] Меньше [-]Aryl hydrocarbon receptor-mediated potencies in field-deployed plastics vary by type of polymer Полный текст
2019
Schönlau, Christine | Larsson, Maria | Lam, Monika M. | Engwall, Magnus | Giesy, John P. | Rochman, Chelsea | Kärrman, Anna
Plastic is able to sorb environmental pollutants from ambient water and might act as a vector for these pollutants to marine organisms. The potential toxicological effects of plastic-sorbed pollutants in marine organisms have not been thoroughly assessed. In this study, organic extracts from four types of plastic deployed for 9 or 12 months in San Diego Bay, California, were examined for their potential to activate the aryl hydrocarbon receptor (AhR) pathway by use of the H4IIE-luc assay. Polycyclic aromatic hydrocarbons (PAH), including the 16 priority PAHs, were quantified. The AhR-mediated potency in the deployed plastic samples, calculated as bio-TEQ values, ranged from 2.7 pg/g in polyethylene terephthalate (PET) to 277 pg/g in low-density polyethylene (LDPE). Concentrations of the sum of 24 PAHs in the deployed samples ranged from 4.6 to 1068 ng/g. By use of relative potency factors (REP), a potency balance between the biological effect (bio-TEQs) and the targeted PAHs (chem-TEQs) was calculated to 24–170%. The study reports, for the first time, in vitro AhR-mediated potencies for different deployed plastics, of which LDPE elicited the greatest concentration of bio-TEQs followed by polypropylene (PP), PET, and polyvinylchloride (PVC).
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