Changes in ion doping levels and their effects on polarisation mechanisms are crucial for characterising the dielectric properties and understanding the colossal permittivity response of CaCu3Ti4O12 (CCTO) ceramics. However, the specific correlation among the ion doping levels, polarisation mechanism, and dielectric performance of CCTO-based ceramics is yet to be elucidated. In this study, (Na1/2Nd1/2)xCa1-xCu3Ti4O12 ceramics with various doping levels (x = 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.35, 0.4, 0.45, and 0.5) are successfully synthesised via a high-temperature solid-state reaction method. The microstructures, ion valence states, and dielectric properties of the ceramics are investigated comprehensively. The results show that as the doping level increases, trace amounts of Ti3+ and Cu+ ions emerged within the ceramics, thus enhancing the semiconducting properties of the grains. Simultaneously, Na, Nd, and Cu accumulate at the grain boundaries, thereby strengthening the internal-barrier-layer capacitance effect and improving the dielectric properties of the ceramics. However, in (Na1/2Nd1/ 2)xCa1-xCu3Ti4O12 ceramics with x >= 0.4, the presence of CuO impurities affect the activation energy of the grain boundary, resulting in higher dielectric loss in these ceramics. The (Na1/2Nd1/2)0.1Ca0.9Cu3Ti4O12 ceramic exhibit an exceptionally high dielectric constant of 25,233 and a low dielectric loss of 0.074 at room temperature and 1 kHz, thus demonstrating its good dielectric stability. Our results provide guidance for understanding the colossal dielectric mechanism of dielectric ceramics.

A series of single phase (Na1/2Eu1/2)xCa1−xCu3Ti4O12 (x = 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.35, 0.4 and 0.45) ceramics with different doping amounts were successfully prepared by high temperature solid-state reaction method. The microstructure, ion valence, and dielectric properties of the ceramics were systematically studied. The results indicated that with the increase of Na+ and Eu3+ ions concentration in (Na1/2Eu1/2)xCa1−xCu3Ti4O12 ceramics, Na and Eu elements accumulated at the grain boundaries of ceramics, thereby increasing the insulation of grain boundaries and effectively reducing the dielectric loss of the ceramics. However, the presence of Cu+ in (Na1/2Eu1/2)xCa1−xCu3Ti4O12 (x ≥ 0.3) ceramics with high doping content could affect the polarization mechanism inside the ceramics and improve their dielectric properties. The dielectric constant of (Na1/2Eu1/2)0.3Ca0.7Cu3Ti4O12 ceramics was as high as 25 282, with a dielectric loss of 0.061 (at room temperature and 10 Hz), and it had good dielectric stability.

A defect chemistry and energy band engineering design strategy for Ba0.85Ca0.15Zr0.1Ti0.9O3-based lead-free ferroelectric ceramics with an ultrahigh breakdown strength is reported.

Pyraclostrobin is a new broad-spectrum methoxyacrylic acid fungicide. Cyazofamid is a new selective foliar spray acaricide. Here, we studied the degradation rate and final residues of pyraclostrobin and cyazofamid in grape and evaluated their dietary risk to consumers. The average recoveries of pyraclostrobin ether ester, cyazofamid and cyazofamid metabolite (CCIM) in grapes were 84-94%, 92-98% and 99-104%, respectively. The relative standard deviations (RSDs) were 6.0-20.3%, 2.4-10.5% and 1.3-4.0%, respectively, and the LOQs were all 0.05 mg/kg. The digestion dynamics of the experimental sites were in accordance with the first-order kinetic equation. The degradation half-lives of pyraclostrobin ether ester and cyazofamid were 17.8 d-28.9 d and 4.3 d-7.8 d, respectively. The final residues of pyraclostrobin ether ester, cyazofamid and CCIM in grapes were <0.05-1.88 mg/kg, <0.05-0.31 mg/kg and <0.05-0.47 mg/kg, respectively. Using probability models, the total chronic risk values for pyraclostrobin and cyazofamid were calculated to be 0.112-189.617% and 0.021-1.714%, respectively. The results of the contribution analysis indicate that pyraclostrobin poses a much greater risk to Chinese consumers than cyazofamid, especially to children and adolescents, who have a significantly greater risk than adults. This suggests that more consideration should be given to the cumulative risk of compounds for vulnerable groups in the future.

Na 1/2 Eu 1/2 Cu 3 Ti 4 O 12 and Na 1/2 Sm 1/2 Cu 3 Ti 4 O 12 dielectric ceramics were synthesized at different sintering temperatures (950, 975 and 1000 °C) by a solid-state reaction method. Phase structure, cation valence state, and dielectric properties of all sintered ceramics were systematically investigated. When the preparation temperature was changed, the Cu + ion concentration of (Na + , Eu 3+ ) co-doped ceramics changed faster than that of (Na + , Sm 3+ ) co-doped ceramics. Abnormally high dielectric constants of ~ 3.17 × 10 4 and ~ 1.06 × 10 4 (at 10 Hz and 303 K) were achieved in Na 1/2 Sm 1/2 Cu 3 Ti 4 O 12 and Na 1/2 Eu 1/2 Cu 3 Ti 4 O 12 ceramics prepared at 950 °C, respectively. However, Na 1/2 Sm 1/2 Cu 3 Ti 4 O 12 and Na 1/2 Eu 1/2 Cu 3 Ti 4 O 12 prepared in high sintering temperature (1000 °C) exhibited a good frequency stability of dielectric permittivity. It was demonstrated that an increasing number of charge carriers induced by the increase of sintering temperature could lead to a competitive coexistence of two polarization mechanisms (surface barrier layer capacitor and internal barrier layer capacitor), further changing the dielectric properties of CaCu 3 Ti 4 O 12 -based ceramics.

Na1/2Eu1/2Cu3Ti4O12 and Na1/2Sm1/2Cu3Ti4O12 dielectric ceramics were synthesized at different sintering temperatures (950, 975 and 1000 °C) by a solid-state reaction method. Phase structure, cation valence state, and dielectric properties of all sintered ceramics were systematically investigated. When the preparation temperature was changed, the Cu+ ion concentration of (Na+, Eu3+) co-doped ceramics changed faster than that of (Na+, Sm3+) co-doped ceramics. Abnormally high dielectric constants of ~ 3.17 × 104 and ~ 1.06 × 104 (at 10 Hz and 303 K) were achieved in Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 ceramics prepared at 950 °C, respectively. However, Na1/2Sm1/2Cu3Ti4O12 and Na1/2Eu1/2Cu3Ti4O12 prepared in high sintering temperature (1000 °C) exhibited a good frequency stability of dielectric permittivity. It was demonstrated that an increasing number of charge carriers induced by the increase of sintering temperature could lead to a competitive coexistence of two polarization mechanisms (surface barrier layer capacitor and internal barrier layer capacitor), further changing the dielectric properties of CaCu3Ti4O12-based ceramics.

In this study, the crystal structure as well as electron transport of TiN thin films were evaluated. We used DC reactive magnetron sputtering to deposit a thin layer of polycrystalline titanium nitride (TiN) on a Si (100) substrate starting from elemental Ti in a nitrogen atmosphere. The influence of nitrogen flow rate on the crystal structure, surface morphology, and electron transport of TiN were investigated systematically. It was found that the preferred orientation and conductivity of TiN thin films exhibit strong nitrogen flow rate dependence. The preferred orientation changed from (111) to (200) initially and then changed back to (111) as the nitrogen flow rate increases. However, an increase in the (200) phase leads to higher conductivity and lower surface roughness. At the optimized deposition conditions, ultra-thin (around 30 nm) TiN thin films with a low resistivity of 101.8 μ C·cm and a surface roughness of less than or equal to 0.51 nm were obtained. These superior performances, along with low running costs, suggest that TiN thin films have great potential for use as electrodes in microelectronic devices.

Metalaxyl-M and azoxystrobin have been used to control various fungal diseases on scallion and other crops. In view of the adverse toxic effects of both on the mammalian liver, it is necessary to conduct a cumulative risk assessment of their dietary exposure to consumers. The residues of metalaxyl-M and azoxystrobin on scallion were determined by a quick, easy, cheap, effective, rugged, and safe method (QuEChERS) combined with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). The half-lives were about 1.15 and 3.89 days, respectively, and the final residues after a seven-day harvest interval were <0.001–0.088 mg/kg and 0.190–4.687 mg/kg, respectively. The cumulative dietary risk quotient of the two fungicides to Chinese consumers calculated by the probability model is 13.94%~41.25%. According to the results of the contribution analysis, the risk posed by azoxystrobin is much greater than that of metalaxyl-M. Although metalaxyl-M and azoxystrobin do not pose a cumulative risk to Chinese consumers, the risk to children and adolescents is significantly higher than that to adults. This suggests that in future research, more consideration should be given to the cumulative risk of compounds to vulnerable groups.

新烟碱类杀虫剂是全球主要的杀虫剂种类之一,约占全球市场份额25％以上.随着新烟碱类农药在全球大量使用,此类杀虫剂对包括蜜蜂在内的非靶标生物造成的负面影响受到高度关注,引发了是否需要限制新烟碱类农药使用的讨论.噻虫嗪是市场份额最大的新烟碱类杀虫剂品种,欧盟于2018年全面取消了噻虫嗪在永久性温室之外的使用登记,并于2022年拟撤销噻虫嗪在所有农产品上的最大残留限量.本文系统回顾了欧盟噻虫嗪登记及残留限量政策调整概况,分析了相关政策调整对噻虫嗪农药和农产品出口贸易可能产生的影响,从世界贸易组织(WTO)规则角度探讨了欧盟全面取消噻虫嗪最大残留限量是否合规,并提出我国作为新烟碱类农药生产和使用大国应对国际新烟碱类农药管理政策变化的措施建议.

三唑类杀菌剂是当前使用较为广泛的杀菌剂品种,氯氟醚菌唑作为新型三唑类杀菌剂,目前已向全球50个国家和组织递交登记材料,其对于60多种作物病害表现出优异的防效和抗逆性.氯氟醚菌唑在弥补传统三唑类杀菌剂缺陷的同时,还降低了对动植物与生态环境的潜在危害,体现出了广阔的应用前景.旨在对氯氟醚菌唑的化学合成、生物活性、生态毒性、环境行为以及代谢特征进行综述,以期对氯氟醚菌唑的合理使用与有效管理提供科学参考.

Benziothiazolinone is the first independently developed fungicide in China. It has been used to effectively control fungal diseases in a variety of fruits, vegetables, and crops. In this study, the degradation behavior and final residue of benziothiazolinone in apples is discussed, and the dietary risk to consumers was evaluated. High-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) was used to determine benziothiazolinone residues in apple samples from eight different regions of China. The average recovery of benziothiazolinone in apples was 85.5–100.2%, and the relative standard deviation (RSD) was 0.8–14.9%. The limits of the method of quantification of benziothiazolinone in apples was 0.01 mg/kg. Under good agricultural practices (GAP) conditions, the final residues of benziothiazolinone in apples were below 0.01 mg/kg, lower than the maximum residual limit (MRL) of China. Although the degradation half-lives of benziothiazolinone were 23.9 d–33.0 d, the risk quotient (RQ) of benziothiazolinone was 15.5% by calculating the national estimated daily intake and comparing it with the acceptable daily intake. These results suggested that under GAP conditions, the intake of benziothiazolinone from apples exhibits an acceptably low health risk on consumers.

新烟碱类农药自20世纪80年代上市以来便受到广泛应用.呋虫胺作为典型的第三代新烟碱类杀虫剂,因其高效、广谱等优点在全球二十多个国家登记使用.近年来,随着呋虫胺的大量使用,其对非靶标生物的潜在危害,以及在农业生产中大量投入导致的环境风险引起了人们的重点关注.因此,阐明呋虫胺的生物活性和生态毒理,揭示其环境行为归趋,这对于呋虫胺的生态风险评价与科学合理使用具有重要意义.笔者旨在综述呋虫胺对靶标害虫的生物活性、对非靶标生物的生态毒理,及其在生态环境中的耗散动力学规律,并对其应用前景进行展望,以期为呋虫胺的合理使用和科学管理提供有效参考.

Understanding the enantioselective fate of chiral neonicotinoid dinotefuran is of vital importance for accurate dietary exposure assessment and food safety regulation. The study investigated the enantioselectivity in respect to dissipation, metabolism, and removal, of dinotefuran from tomato cultivation to tomato paste processing. The chiral analytical method of dinotefuran, UF and DN was developed in tomato using ultrahigh performance supercritical fluid chromatography/tandem mass spectrometry. Under greenhouse cultivation R-dinotefuran preferentially degraded (T1/2, 9.1-12.6 days), resulting in relative enrichment of S-dinotefuran (T1/2, 10.3-13.3 days) by foliage and root uptake pathways. (-)-UF generated at a faster rate and was more persistent than its antipode in tomato by foliage treatment. Furthermore, changes in the enantiomeric removal and enantioselectivity orientation of dinotefuran and metabolites were evaluated during home canning of tomato paste, including washing, peeling, homogenization, simmering, and sterilization. Peeling played the key role in reducing S-dinotefuran by 67.3% and R-dinotefuran by 69.9% with processing factor of 0.313 and 0.287, respectively. Simmering was the most effective way to remove UF enantiomers (Pf, 0.336-0.421) by elevated temperature. This study sheds light on the chiral profiles of the fate of dinotefuran from cultivation to processing, providing scientific importance to protect human health from hazardous effects.

Tracing the herbicide bixlozone and its metabolites in food is necessary to assess their risks to human health. In the study, a rapid and effective analytical method using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for the simultaneous determination of bixlozone and its metabolites (2,4-dichlorobenzoic acid, 3-hydroxy-propanamide-bixlozone, and 5'-hydroxy-bixlozone) in plant and animal samples (tomato, cucumber, apple, wheat flour, meat, milk, and egg) was developed based on ultra-performance liquid chromatography-tandem mass spectrometry. The method was validated based on the linearity (R2  > 0.99), sensitivity (limit of quantification = 0.01 mg/kg), recovery (70.2%-115.1%), and precision (intra-day 1.2%-17.6%, inter-day 0.3%-16.0%). Detection was achieved within 6.0 min. The method is reliable for the determination of four target compounds in all seven matrices. The satisfactory validation criteria and successful application show that the proposed methodology is suitable for the detection of four target compounds in real matrices. This article is protected by copyright. All rights reserved.

Elucidating the enantiomeric chemistry and enantioselective fate of the novel chiral triazole fungicide mefentrifluconazole is of vital importance for agroecosystem safety and human health. The absolute configuration of mefentrifluconazole was identified firstly as S-(+)-mefentrifluconazole and R-(-)-mefentrifluconazole on a cellulose tris(3-chloro-4-methylphenylcarbamate) chiral phase. A baseline resolution (Rs, 2.51), favorable retention (RT ≤ 2.24 min), and high sensitivity (LOQ, 0.5 μg/kg) of enantiomer pair were achieved by reversed-phase liquid chromatography tandem mass spectrometry combined with a 3D response surface strategy. Nationwide field trials were undertaken to clarify the enantiomer occurrence, enantioselective dissipation, terminal concentrations, and storage stability of S-mefentrifluconazole and R-mefentrifluconazole in watermelon across China. The original deposition of the sum of enantiomer pair was estimated to be 14.4-163.7 μg/kg, and terminally decreased to < LOQ-59.3 μg/kg 10 days after foliage application. S-mefentrifluconazole preferentially degraded (T1/2, 3.3-6.0 days), resulting in the relative enrichment of R-mefentrifluconazole (T1/2, 3.9-6.6 days) in watermelon. A probabilistic model is recommended for the dietary risk assessment, although both acute (%ARfD, 0.435-22.188%) and chronic (%ADI, 1.697-9.658%) risks are acceptable for associated population. The long-term exposures should be continuously emphasized given the increasing applications and persistent fate of mefentrifluconazole, especially for urban children.

世界贸易组织( WTO )动植物卫生检疫措施委员会的部分成员国再次指控欧盟对农用化学品的监管措施及其建立的最大残留限量( MRL)扰乱了国际贸易. 继去年提出类似指控后,美国在哥伦比亚、哥斯达黎加、厄瓜多尔和巴拉圭等国家的支持下表示,对欧盟在没有明确的科学依据或对人体健康没有显著影响的情况下,继续将多项MRL 降低到"贸易限制水平",感到"失望".这些国家对欧盟"基于危害"的农药监管法规感到"担忧".

Atrazine is one of the most used herbicides in China. It is a persistent organic pollutant but has been widely used on Chinese farmlands for a long time. To assess its dietary and ecological risks to human and environment, in this study, atrazine residues were extracted with acetonitrile and then plant samples were detected with gas chromatography coupled with mass spectrometry (GC-MS) and soil samples were determined with gas chromatography coupled with nitrogen-phosphorus detector (GC-NPD). The limit of quantification (LOQ) of the method was 0.01 mg/kg for all matrices. The recoveries ranged from 82.0 to 105.4% for plant samples and 75.6 to 85.6% for soil samples. The final residues of atrazine in all plant samples were lower than LOQ. Dietary risk assessment suggested that under good agricultural practices (GAP) conditions, intake of atrazine from apples, grapes, and tea would exhibit an acceptably low health risk on consumers. However, the final residues of atrazine in soil samples were <0.01–9.2 mg/kg, and the half-lives were 2.0–9.1 days. Based on the species sensitivity distribution (SSD) model, the potential affected fraction (PAF) of atrazine in soil samples ranges from 0.01 to 65.8%. Atrazine residues in 43.1% soil samples were higher than 0.11 mg/kg, which was the hazardous concentration for 5% of species (HC5) of atrazine in soil. These results suggested that the ecological risks of atrazine in apples, grapes, and tea garden soil would exhibit a high risk on environmental species even under the same GAP conditions. This study could provide guidance for comprehensive risk assessment of atrazine properly used in apple, grape, and tea gardens.

Nucleic acids detection has significant meanings in disease diagnosis, monitoring of environment and so on. However, only trace concentration of nucleic acids exists in specimen. Ultrasensitive nucleic acids detection is required based on the strategies of signal amplification. Currently, DNA nanotechnologies are employed to amplify the detecting signal, mainly including DNA hybridization-based sensors and DNA circuits-based sensors. DNA circuits-based sensors have higher sensitive than that of DNA hybridization-based sensors, which attract the attention of researchers. With this view, we present an overview of DNA circuits-based amplification strategies for nucleic acids detection with fluorescent sensors and electrochemical sensors, respectively. It mainly contains duplex specific nuclease (DSN)-based DNA circuits and strand displace reaction (SDR)-based DNA circuits, which enable nucleic acids to trigger DNA circuits without consumption. The strategies can multiply the increase of the signal of nucleic acids with simple operation. Meanwhile, this review discusses the current challenges and future outlook of DNA circuits in sensors. We envision that our review provides implications to promote the development of DNA circuits-based biosensors for nucleic acids detection.

A rapid, sensitive, and effective multiresidue analytical method was established to investigate the degradation rate and final residues of bifenthrin, bifenazate, and its metabolite bifenazate-diazene in apples, and the dietary risk of consumers was evaluated. The residues of bifenthrin, bifenazate, and bifenazate-diazene in apple samples from 12 different apple-producing areas of China were determined by high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). The average recoveries of the three compounds in apples were 88.4-104.6%, and the relative standard deviations (RSDs) were 1.3-10.5%. The limit of quantification (LOQ) for each compound was 0.01 mg/kg. Although the degradation half-lives of bifenthrin, bifenazate, and bifenazate-diazene were 17.8-28.9, 4.3-7.8, and 5.0-5.8 days, under good agricultural practice (GAP) conditions, the final residues of bifenthrin, bifenazate, and the sum of bifenazate and its metabolite bifenazate-diazene in apples were <0.01-0.049, < 0.01-0.027, and <0.02-0.056 mg/kg, respectively, which were lower than the maximum residue limit (MRL) in China. By comparing the deterministic model with the probabilistic model, the results of the probabilistic model at the P95 level (12.91-48.9% for bifenthrin, 17.48-52.01% for bifenazate including its metabolite) were selected as reasonable assessment criteria for chronic dietary risk, and the acute risk was at the P99.9 level (3.00-15.59% for bifenthrin). Although the exposure risk calculated by both the deterministic model and the probabilistic model was less than 100%, the risk to children is significantly higher than that of the general population. This suggests that in future research and policy making, we should pay more attention to the risk of vulnerable groups such as children.

农业生产中,呋虫胺以外消旋体的形式销售和使用,在进入生态环境后出现对映体选择性降解、吸收、代谢、排泄等.不区分对映体间差异的传统风险评估给呋虫胺的合理使用与生态安全带来了诸多隐患.研究指出S-呋虫胺既是高毒体也是高活体,其生态毒性为R-呋虫胺的13.9～145.9倍,但R-呋虫胺也表现出较高的杀虫活性,且作物中优先降解,开发高比例的R体农药有利于维持杀虫活性的同时降低对非靶生物和生态环境的负效应.本文旨在综述呋虫胺对映体选择性生物活性、生态毒性及环境行为研究进展,为其科学难题的解决提供新思路,也为其科学有效管理提供理论依据.