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1.
Plant Cell ; 36(6): 2176-2200, 2024 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-38345432

RESUMEN

Phosphorus is indispensable in agricultural production. An increasing food supply requires more efficient use of phosphate due to limited phosphate resources. However, how crops regulate phosphate efficiency remains largely unknown. Here, we identified a major quantitative trait locus, qPE19, that controls 7 low-phosphate (LP)-related traits in soybean (Glycine max) through linkage mapping and genome-wide association studies. We identified the gene responsible for qPE19 as GLYCEROPHOSPHORYL DIESTER PHOSPHODIESTERASE2 (GmGDPD2), and haplotype 5 represents the optimal allele favoring LP tolerance. Overexpression of GmGDPD2 significantly affects hormone signaling and improves root architecture, phosphate efficiency and yield-related traits; conversely, CRISPR/Cas9-edited plants show decreases in these traits. GmMyb73 negatively regulates GmGDPD2 by directly binding to its promoter; thus, GmMyb73 negatively regulates LP tolerance. GmGDPD2 physically interacts with GA 2-oxidase 1 (GmGA2ox1) in the plasma membrane, and overexpressing GmGA2ox1 enhances LP-associated traits, similar to GmGDPD2 overexpression. Analysis of double mutants for GmGDPD2 and GmGA2ox1 demonstrated that GmGDPD2 regulates LP tolerance likely by influencing auxin and gibberellin dose-associated cell division in the root. These results reveal a regulatory module that plays a major role in regulating LP tolerance in soybeans and is expected to be utilized to develop phosphate-efficient varieties to enhance soybean production, particularly in phosphate-deficient soils.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Glycine max , Fosfatos , Proteínas de Plantas , Glycine max/genética , Glycine max/metabolismo , Fosfatos/metabolismo , Fosfatos/deficiencia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Sitios de Carácter Cuantitativo/genética , Plantas Modificadas Genéticamente , Estudio de Asociación del Genoma Completo
2.
Plant Physiol ; 192(2): 1099-1114, 2023 05 31.
Artículo en Inglés | MEDLINE | ID: mdl-36932694

RESUMEN

Soybean (Glycine max) is a major grain and oil crop worldwide, but low phosphorus (LP) in soil severely limits the development of soybean production. Dissecting the regulatory mechanism of the phosphorus (P) response is crucial for improving the P use efficiency of soybean. Here, we identified a transcription factor, GmERF1 (ethylene response factor 1), that is mainly expressed in soybean root and localized in the nucleus. Its expression is induced by LP stress and differs substantially in extreme genotypes. The genomic sequences of 559 soybean accessions suggested that the allelic variation of GmERF1 has undergone artificial selection, and its haplotype is significantly related to LP tolerance. GmERF1 knockout or RNA interference resulted in significant increases in root and P uptake efficiency traits, while the overexpression of GmERF1 produced an LP-sensitive phenotype and affected the expression of 6 LP stress-related genes. In addition, GmERF1 directly interacted with GmWRKY6 to inhibit transcription of GmPT5 (phosphate transporter 5), GmPT7, and GmPT8, which affects plant P uptake and use efficiency under LP stress. Taken together, our results show that GmERF1 can affect root development by regulating hormone levels, thus promoting P absorption in soybean, and provide a better understanding of the role of GmERF1 in soybean P signal transduction. The favorable haplotypes from wild soybean will be conducive to the molecular breeding of high P use efficiency in soybean.


Asunto(s)
Glycine max , Factores de Transcripción , Glycine max/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Fósforo/metabolismo , Genotipo , Fenotipo , Raíces de Plantas/genética , Raíces de Plantas/metabolismo
3.
Environ Sci Technol ; 58(28): 12633-12642, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-38958591

RESUMEN

As the number of coastal nuclear facilities rapidly increases and the wastewater from the Fukushima Nuclear Plant has been discharged into the Pacific Ocean, the nuclear environmental safety of China's marginal seas is gaining increased attention along with the heightened potential risk of nuclear accidents. However, insufficient work limits our understanding of the impact of human nuclear activities on the Yellow Sea (YS) and the assessment of their environmental process. This study first reports the 129I and 127I records of posthuman nuclear activities in the two YS sediments. Source identification of anthropogenic 129I reveals that, in addition to the gaseous 129I release and re-emission of oceanic 129I discharged from the European Nuclear Fuel Reprocessing Plants (NFRPs), the Chinese nuclear weapons testing fallout along with the global fallout is an additional 129I input for the continental shelf of the YS. The 129I/127I atomic ratios in the North YS (NYS) sediment are significantly higher than those in the other adjacent coastal areas, attributed to the significant riverine input of particulate 129I by the Yellow River. Furthermore, we found a remarkable 129I latitudinal disparity in the sediments than those in the seawaters in the various China seas, revealing that sediments in China's marginal seas already received a huge anthropogenic 129I from terrigenous sources via rivers and thus became a significant sink of anthropogenic 129I. This study broadens an insight into the potential impacts of terrigenous anthropogenic pollution on the Chinese coastal marine radioactive ecosystem.


Asunto(s)
Sedimentos Geológicos , Monitoreo de Radiación , Ríos , Sedimentos Geológicos/química , Ríos/química , China , Contaminantes Radiactivos del Agua/análisis , Océanos y Mares , Humanos , Radioisótopos de Yodo/análisis
4.
Environ Sci Technol ; 57(49): 20773-20780, 2023 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-37906162

RESUMEN

Iodine is a crucial nutrient for public health, and its presence in the terrestrial atmosphere is a key factor in determining the prevalence of iodine deficiency disorders. While oceanic iodine emissions decrease at lower sea surface temperatures, the primary contributors to atmospheric iodine can vary from oceanic sources in the summer to other sources in winter. However, the specific sources and their respective contributions have remained unexplored. Fortunately, the atomic ratio of 129I to 127I significantly differs between nuclear activity and fossil fuels like coal and petroleum, which formed millions to billions of years ago. This distinction makes 129I a valuable tool for identifying iodine sources. In our study, we analyzed iodine isotopes and incorporated additional indicators such as element content in PM2.5 samples. Our findings reveal, for the first time, that in winter inland areas, fuel oil, alongside coal combustion, is a significant source of atmospheric iodine. This research enhances our comprehension of the impact of human activities on iodine levels in the environment. This understanding is crucial not only for addressing iodine deficiency-related health concerns but also for comprehending stratospheric ozone depletion, a phenomenon closely associated with atmospheric iodine.


Asunto(s)
Contaminantes Atmosféricos , Yodo , Petróleo , Humanos , Combustibles Fósiles/análisis , Contaminantes Atmosféricos/análisis , Carbón Mineral , Monitoreo del Ambiente
5.
Environ Sci Technol ; 57(26): 9732-9743, 2023 07 04.
Artículo en Inglés | MEDLINE | ID: mdl-37345322

RESUMEN

Microplastics (MPs) are emerging pollutants, and limited research has focused on their exposure to terrestrial wildlife and transport mode on the remote Tibetan Plateau (TP). Therefore, we investigated MPs in the southern soil and feces of Equus kiang (Tibetan wild ass), a species peculiar to the TP, which is known as the "third pole." We found that MP median abundances were 102 and 4.01 particles/g of dry feces and soil, respectively. In both media, the MP morphology mainly comprised ∼50 µm slender fibrous particles. In total, 29 MP types were identified in the feces, compared to 26 types in the soil. Among them, the acrylate copolymer (35.9%) and polyurethane (24.9%) were predominant in the feces, while polyurethane (22.5%) and silicone (20.4%) were predominant in the soil. After ingesting MPs at one location, E. kiang may become a source of MP pollution when moving to other meadows on the TP. The potential MP transport flux of a herd of 20 kiangs has been estimated at 1736 particles m-2 a-1. A unique "source-sink-source" MP transport model comprising an "atmospheric deposition-vegetation-feces-atmosphere" cycle on the TP was observed based on atmospheric transport simulations and terrestrial food chain transfer processes. Owing to human settlements in south and East Asia adjacent to the TP, atmospheric long-distance transmission is an essential route for MPs to enter the TP.


Asunto(s)
Microplásticos , Plásticos , Animales , Humanos , Tibet , Suelo , Poliuretanos , China , Equidae , Heces , Monitoreo del Ambiente
6.
Sci Total Environ ; 926: 171777, 2024 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-38499094

RESUMEN

The transport and deposition pathways of anthropogenic radionuclides at the global scale, particularly volatile 129I, remain somewhat elusive due to a dearth of comprehensive investigations. To gain a better understanding of the transport dynamics and deposition mechanism of anthropogenic 129I in the terrestrial environment, one hundred surface soil samples collected from northeast China were analyzed for 129I and 127I concentrations in this study. Our findings reveal that 129I/127I atomic ratios in the mid-eastern Inner Mongolia (MIM) were approximately an order of magnitude higher than the rest of the investigated area. This is, besides the global fallout and the long-range transport of 129I released from the European nuclear reprocessing plants via westerly winds, possibly attributed to the dust with high 129I levels from the East Asian arid regions. In addition to the significant dust-induced 129I input, the unique meteorological conditions and topographical features in the MIM synergistically contribute to the pronounced accumulation and deposition of 129I in this region. This study will provide novel insights into the transport and deposition mechanism of anthropogenic radionuclides, which is significant for the assessment of anthropogenic nuclear activities on the environment in the future.

7.
An Bras Dermatol ; 99(2): 189-195, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38061964

RESUMEN

BACKGROUND: The development of rosacea is suggested to be closely associated with lipid metabolism, inflammation, and anxiety/depression. Gamma linolenic acid (GLA) is a key factor participating in lipid metabolism, which is also confirmed to regulate the inflammatory response. However, the associations of serum GLA levels with rosacea severity and psychological status still remain unclear. OBJECTIVE AND LIMITATIONS OF THE STUDY: The present study aimed to investigate the associations of gamma linolenic acid (GLA), a key factor participating in lipid metabolism and the inflammatory response, with rosacea severity and psychological status. The present study still had some limitations. First, this study is a cross-sectional study and does not provide longitudinal evidence about the relationship between GLA and rosacea; Second, the cohort in this study is also relatively small, and a larger cohort is needed in further investigation to reveal the potential role of lipid metabolism in the pathogenesis of rosacea. METHODS: A total of 62 rosacea patients were consecutively recruited. Patient's Self-Assessment (PSA) scale and Clinician Erythema Assessment (CEA) as well as 7-item Generalized Anxiety Disorder (GAD-7) and 9-item Patient Health Questionnaire (PHQ-9) were conducted to evaluate the degree of erythema severity and anxiety/depression, respectively. Serum GLA levels were determined by gas chromatography mass. RESULTS: Lower levels of serum GLA in rosacea patients were observed (p<0.001), and subgroup analysis revealed that patients with higher-level GLA had lower scores of PSA, CEA, GAD-7 and PHQ-9. Moreover, Spearman correlation analysis uncovered that serum GLA levels were negatively associated with PSA, CEA, GAD-7 as well and PHQ-9 scores, respectively. Linear regression model found that serum GLA levels at baseline were a predictive factor for prognosis of clinical outcomes after 1-month conventional treatment. CONCLUSION: The present study indicates that lower levels of serum GLA in rosacea patients are negatively associated with the degree of erythema and anxiety/depression status.


Asunto(s)
Rosácea , Ácido gammalinolénico , Humanos , Ácido gammalinolénico/uso terapéutico , Depresión/etiología , Estudios Transversales , Índice de Severidad de la Enfermedad , Rosácea/complicaciones , Rosácea/psicología , Eritema/etiología , Eritema/tratamiento farmacológico , Ansiedad/etiología
8.
Sci Rep ; 14(1): 6331, 2024 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-38491005

RESUMEN

In this study we aimed to investigate the prevalence of SARS-CoV-2 infection in psoriasis patients, and outcomes of SARS-CoV-2 infection and associated risk factors. A cross-sectional survey was conducted from February 2023 to March 2023. Information was obtained with online questionnaire about psoriasis patients on demographic characteristics, clinical characteristics, SARS-CoV-2 infection and outcomes, vaccination, and routine protection against COVID-19. Logistic regression analysis was used to explore risk factors with SARS-CoV-2 infection and exacerbation of psoriasis. A total of 613 participants were recruited. 516 (84.2%) were infected, and associated factors were sex, working status, routine protection against COVID-19, COVID-19 vaccination, impaired nail, infection exacerbate psoriasis, and severity of psoriasis. Among the patients infected with SARS-CoV-2, 30 (5.8%) required hospitalization, 122 (23.6%) had psoriasis exacerbation due to SARS-CoV-2 infection, and associated factors were subtype of psoriasis, discontinuation of psoriasis treatment during SARS-CoV-2 infection, response following COVID-19 vaccination, and severity of psoriasis. Booster dose vaccination contributed a low probability of COVID-19 sequelae. COVID-19 vaccine's effectiveness was unsatisfactory, while booster dose vaccination reduced the occurrence of COVID-19 sequelae in psoriasis patients of Southwest China. Patients treated with psoriasis shown to be safe, without a higher incidence of SARS-CoV-2 infection or COVID-19hospitalization compared to untreated patients. Stopping treatment during SARS-CoV-2 infection led to psoriasis exacerbation, so psoriasis treatment could be continued except severe adverse reaction.


Asunto(s)
COVID-19 , Psoriasis , Humanos , COVID-19/epidemiología , Estudios Transversales , Prevalencia , SARS-CoV-2 , Vacunas contra la COVID-19 , China/epidemiología , Progresión de la Enfermedad , Psoriasis/complicaciones , Psoriasis/epidemiología
9.
Anal Chem ; 85(7): 3715-22, 2013 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-23472747

RESUMEN

A rapid and simple method was developed for speciation analysis of (129)I in seawater by selective coprecipitation of carrier-free iodide and accelerator mass spectrometry (AMS) measurement of (129)I. Iodide was separated from seawater and other species of iodine by coprecipitation of AgI with Ag2SO3, AgCl, and AgBr by addition of only 100 mg/L Ag(+) and 0.3 mmol/L NaHSO3 at pH 4.2-5.5. The separation efficiency of iodide was more than 95%, and crossover between (129)IO3(-) and (129)I(-) fractions is less than 3%. Iodate and total inorganic iodine were converted to iodide by use of NaHSO3 at pH 1-2 and then separated by the same method as for iodide. Ag2SO3 in the coprecipitate was removed by washing with 3 mol/L HNO3 and the excess AgCl and AgBr was removed by use of diluted NH3, and finally a 1-3 mg precipitate was obtained for AMS measurement of (129)I. The recovery of iodine species in the entire procedure is higher than 70%. Six seawater samples collected from the Norwegian Sea were analyzed by this method as well as a conventional anion-exchange chromatographic method; the results from the two methods show no significant difference (p = 0.05). Because only one separation step and fewer chemicals are involved in the procedure, this method is suitable for operation on board sampling vessels, as it avoids the transport of samples to the laboratory and storage for a longer time before analysis, therefore significantly improving the analytical capacity and reliability of speciation analysis of (129)I. This improvement can stimulate oceanographic tracer studies of (129)I.

10.
Environ Sci Technol ; 47(7): 3091-8, 2013 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-23461388

RESUMEN

The Fukushima nuclear accident in March 2011 has released a large amount of radioactive pollutants to the environment. Of the pollutants, iodine-129 is a long-lived radionuclide and will remain in the environment for millions of years. This work first report levels and inorganic speciation of (129)I in seawater depth profiles collected offshore Fukushima in June 2011. Significantly elevated (129)I concentrations in surface water were observed with the highest (129)I/(127)I atomic ratio of 2.2 × 10(-9) in the surface seawater 40 km offshore Fukushima. Iodide was found as the dominant species of (129)I, while stable (127)I was mainly in iodate form, reflecting the fact that the major source of (129)I is the direct liquid discharges from the Fukushima NPP. The amount of (129)I directly discharged from the Fukushima Dai-ichi nuclear power plant to the sea was estimated to be 2.35 GBq, and about 1.09 GBq of (129)I released to the atmosphere from the accident was deposited in the sea offshore Fukushima. A total release of 8.06 GBq (or 1.2 kg) of (129)I from the Fukushima accident was estimated. These Fukushima-derived (129)I data provide necessary information for the investigation of water circulation and geochemical cycle of iodine in the northwestern Pacific Ocean in the future.


Asunto(s)
Yodo/análisis , Monitoreo de Radiación , Agua de Mar/química , Accidente Nuclear de Fukushima , Radioisótopos de Yodo , Japón , Plantas de Energía Nuclear
11.
Heliyon ; 9(5): e16174, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37215874

RESUMEN

Talent agglomeration greatly promotes the development of cities as a special form of talent allocation. However, excessive agglomeration of talent also leads to talent crowding and overqualification, which undermines the effectiveness of employing human resources and stimulates talent urban withdrawal. Based on the data from 327 questionnaires, data analysis was performed using Mplus 8.0 and HLM 6.08, this study explores the internal mechanism between overqualification and talent's intention of urban withdrawal from the perspective of talent crowding. The following conclusions were drawn: (1) Overqualification is positively correlated with talents' intention of urban withdrawal. (2) Psychological contract breach plays a mediating effect between overqualification and the talents' intention of urban withdrawal. (3) Relational mobility is negatively correlated with talents' intention of urban withdrawal. (4) Relational mobility plays a moderating role in the relationship between overqualification and talents' intention of urban withdrawal. (5) Urban livability is negatively correlated with talents' intention of urban withdrawal. (6) Urban livability plays a moderating role in the relationship between overqualification and talents' intention of urban withdrawal. The results can further improve the human resource management theory and serve as a foundation for developing and implementing population management policies in cities.

12.
Sci Total Environ ; 864: 160937, 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36528106

RESUMEN

Radionuclides, such as 210Pb, 137Cs and 239,240Pu, have been widely used for dating recent sediments in terrestrial and marine environments, while 129I, as an important artificial radionuclide in the environment, is also a potential tracer for sediment dating and environmental process studies. However, they were not always successfully applied to sediment dating because of their different sources, half-lives, environmental behaviour and measurement techniques. The dating applicability of these nuclides in a sedimentary environment with rapid accumulation on land was investigated for sinkhole sediment from the southern Chinese Loess Plateau. Our results showed that 210Pb and 137Cs could not be adequately used for dating the sediments due to the difficulties in accurately measuring 137Cs and excess 210Pb (210Pbex) signals caused by the dilution effect of rapid accumulation. 129I is not an ideal dating tracer because of its multisource feature causing no remarkable peak value in the sediment cores. The depth distribution of 239,240Pu in the sediment core showed a single peak corresponding to its maximum fallout in 1963 from the atmospheric nuclear weapons test, suggesting that Pu isotopes have significant advantages in dating recent sediments. The sensitive inductively coupled plasma-mass spectrometry (ICP-MS) measurement technique enables the determination of very low levels of 239Pu and 240Pu and makes 239,240Pu a suitable tracer for dating the rapidly accumulated sediment. Based on the 239,240Pu mass balance equation estimation and field observations, we proposed the water-eroded input from soil surrounding the sinkhole as another vital source of the sediments in addition to the aeolian contribution.

13.
Front Artif Intell ; 6: 1213620, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37928449

RESUMEN

Background: Due to the lower reliability of laboratory tests, skin diseases are more suitable for diagnosis with AI models. There are limited AI dermatology diagnostic models combining images and text; few of these are for Asian populations, and few cover the most common types of diseases. Methods: Leveraging a dataset sourced from Asia comprising over 200,000 images and 220,000 medical records, we explored a deep learning-based system for Dual-channel images and extracted text for the diagnosis of skin diseases model DIET-AI to diagnose 31 skin diseases, which covers the majority of common skin diseases. From 1 September to 1 December 2021, we prospectively collected images from 6,043 cases and medical records from 15 hospitals in seven provinces in China. Then the performance of DIET-AI was compared with that of six doctors of different seniorities in the clinical dataset. Results: The average performance of DIET-AI in 31 diseases was not less than that of all the doctors of different seniorities. By comparing the area under the curve, sensitivity, and specificity, we demonstrate that the DIET-AI model is effective in clinical scenarios. In addition, medical records affect the performance of DIET-AI and physicians to varying degrees. Conclusion: This is the largest dermatological dataset for the Chinese demographic. For the first time, we built a Dual-channel image classification model on a non-cancer dermatitis dataset with both images and medical records and achieved comparable diagnostic performance to senior doctors about common skin diseases. It provides references for exploring the feasibility and performance evaluation of DIET-AI in clinical use afterward.

14.
Front Psychol ; 13: 969013, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36304877

RESUMEN

Hindrance stress is a stimulus factor in the workplace that has a certain impact on the innovative behavior of employees. Most existing studies focus on the analysis of individual-level factors, ignoring the important role of organizational-level factors. This study uses multiple linear models to empirically analyze the interaction mechanisms among hindrance stress, proactive personality, employment relationship atmosphere, and employee innovative behavior factors in the workplace. This study found the following: (1) Hindrance stress negatively affects employees' innovative behavior. (2) A proactive personality positively affects employees' innovative behavior. (3) A proactive personality plays a moderating role in the relationship between hindrance stress and employees' innovative behavior. (4) The employment relationship atmosphere has a positive impact on employees' innovative behavior. (5) The employment relationship atmosphere plays a moderating role in the relationship between hindrance stress and employees' innovative behavior. This study enriches theoretical knowledge in the field of human resources and provides guidance for business managers on the effective encouragement of employees' innovative behavior.

15.
Plant Sci ; 320: 111283, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35643608

RESUMEN

Purple acid phosphatase (PAP) is an important plant acid phosphatase, which can secrete to the rhizosphere to decompose organophosphorus, promote phosphorus use efficiency, plant growth and development. However, little is known about the functions of intracellular PAP in plants, especially for soybean. Our previous study integrating QTL mapping and transcriptome analysis identified an promising low phosphorus (LP)-induced gene GmPAP17. Here, we determined that GmPAP17 was mainly expressed in roots and had a strong response to LP stress. Furthermore, and the relative expression in the root of LP tolerant genotypes NN94-156 was significantly greater than that of LP sensitive genotype Bogao after LP stress treatment. The overexpression of GmPAP17 significantly enhanced both acid phosphatase activity and growth performance of hairy roots under LP stress condition, it was vice versa for RNAi interference of GmPAP17, indicating that GmPAP17 plays an important role in P use efficiency. Moreover, yeast two-hybrid and bimolecular fluorescence complementation analysis showed that GmRAP2.2 was involved in the regulation network of GmPAP17. Taken together, our results suggest that GmPAP17 is a novel plant PAP that functions in the adaptation of soybean to LP stress, possibly through its involvement in P recycling in plants.


Asunto(s)
Glycine max , Fósforo , Fosfatasa Ácida/genética , Fosfatasa Ácida/metabolismo , Mapeo Cromosómico , Fósforo/metabolismo , Glycine max/metabolismo
16.
Talanta ; 224: 121882, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33379091

RESUMEN

236U in the environment mainly originates from human nuclear activities. Based on the unique properties of uranium, 236U can be used as a powerful tracer for investigation of oceanographic and environmental processes. This requires sensitive measuement of 236U in various environmental samples. Due to the ultra-low radioactive level of 236U in the environment, its measurement is only possible by mass spectrometry. Because of the low atomic ratio of 236U/235U down to 10-7-10-5 in the environment, the interferences of 235U1H+ and peak tailings of 235U and 238U are critical challenges in the measurement of 236U by ICP-MS. This work developed a sensitive ICP-MS/MS method for measurement of ultra-low 236U by employing reaction cell technique and sequential quadrupole mass separators. By using 0.6 mL min-1 CO2 - 7 mL min-1 helium as collision/reaction gas to convert U+ and UH+ to UO+, the interferences of UH+ (UOH+/UO+ ratio) were significantly reduced to less than 2.4 × 10-7. A minimum detectable 236U/238U ratio of 3.0 × 10-10 was achieved, which is one order of magnitude better than reported values. By using collision focusing with helium in the reaction cell and APEX sample introduction system, the measurement sensitivity for 236U (236UO+) was improved to 7.5 × 106 cps ppb-1. In combination with an effective chemical separation of uranium from sample matrix and interferences using total borate fusion following extraction chromatography with UTEVA resin, a detection limit of 7.2 × 10-16 g g-1 for 236U was achieved. The developed method was verified by analysis of certified reference materials and by comparison with AMS measurement method. Soil samples collected from Northwest China were successfully analyzed. 236U/238U ratios down to 9 × 10-10 were measured in these samples, and the sources of 236U in different sits were discussed.

17.
Anal Chem ; 82(18): 7713-21, 2010 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-20735008

RESUMEN

Separation of carrier free iodine from low iodine level samples and accurate measurement of ultralow level (129)I in micrograms of iodine target are essential but a bottleneck in geological dating of terrestrial system and tracer research using naturally produced (129)I. In this work, we present a carrier free method using coprecipitation of AgI with AgCl for preparing micrograms of iodine target, associated with combustion using a tube furnace for separating iodine from solid samples and anion exchange chromatography for preconcentrating iodine from a large volume of water. An accelerator mass spectrometry was used to measure ultralow level (129)I in micrograms of iodine target. The recovery of iodine in the entire separation procedure is higher than 80% and 65% for solid and water samples, respectively. One microgram iodine in the target (AgI-AgCl) can produce a stable (127)I signal for AMS measurement of (129)I/(127)I, and a detection limit of this method for (129)I is calculated to be 10(5) atoms. This will allow us to accurately determine (129)I in prenuclear geological samples of low iodine concentration with (129)I/(127)I of 10(-12), such as loess, soil, coral, rock, sediment, and groundwater. Some samples with low iodine content have been successfully analyzed, and the lowest value of the (129)I/(127)I ratio of 2 × 10(-11) was observed in 23.5 and 63.5 m loess samples collected in the Loess Plateau, China. The developed method sheds light on a wide application in earth science.

18.
Chemosphere ; 252: 126524, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32217409

RESUMEN

129I released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been observed in the atmospheric, terrestrial and oceanic environments, and it also entered the marine sediments via dispersion by sea water movement and deposition around Japan. However, there have been few studies of marine sediment cores in contrast to the large number of studies on seawater. In this work, a sediment core collected near FDNPP was analyzed for 129I. It is observed that the 129I/127I atomic ratios in this sediment core are comparable to those in the seawater and sediments collected from offshore Fukushima after the accident, but 2 orders of magnitude higher than those in seawater in this region before the accident, suggesting the significant amount of 129I has been transferred and incorporated to the offshore shallow sediments. The difference in environmental behavior between 129I and 137Cs is discussed based on their depth distributions in the sediment core in comparison with the grain size distribution of sediments. The peak concentrations of iodine isotopes were found in a relatively deeper layer than radiocesium. Radiocesium follows the distribution of fine grains in the sediment core, implying its high association to fine grains.


Asunto(s)
Accidente Nuclear de Fukushima , Radioisótopos de Yodo/análisis , Monitoreo de Radiación , Contaminantes Radiactivos del Agua/análisis , Radioisótopos de Cesio , Sedimentos Geológicos , Japón , Plantas de Energía Nuclear , Océanos y Mares , Agua de Mar , Movimientos del Agua
19.
ACS Omega ; 5(28): 17471-17478, 2020 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-32715232

RESUMEN

In this contribution, biochar from municipal sludge was used as a novel matrix for the synthesis of a series of calcium-based heterogeneous catalysts toward biodiesel production. Their catalytic activity was investigated in terms of catalyst loading and calcination temperature during preparation, in addition to the transesterification parameters including the methanol/oil molar ratio, reaction time, and catalyst amount. The highest biodiesel yield up to 93.77% was achieved with the 30Ca/A-SBC-700, and it maintained as high as 84.9% even after 10 cycles of a consecutively alternating catalysis and regeneration process. It was revealed that the porous municipal sludge biochar and autologous SiO2 were accountable for the superior stability of the present catalyst. This work may provide a new path to value-added valorization of sludge waste and also a renewable and efficient catalyst for biodiesel production at a low cost.

20.
Environ Pollut ; 245: 443-452, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30458374

RESUMEN

With the increased numbers of nuclear power plants constructed along the east coast of China, it is important to know radioactive sources and transport pathways between land and sea, in order to better understand the impact of these nuclear facilities to the marine environment. Two sediment cores collected from the East China Sea dated to 1959-2010 were analyzed for long-lived radioactive 129I and stable 127I. It was observed that 129I levels (129I/127I ratio of (15.0-75.0) × 10-12) were significantly increased compared to the pre-nuclear value (129I/127I = 1.5 × 10-12). Some 129I peaks were observed in layers of 1959, 1966, 1971 and 1976 (1977), corresponding to the atmospheric nuclear weapon tests at Pacific Proving Grounds and Lop Nor. The high values of 129I after the late 1970s are attributed to the releases from the European reprocessing plants. In addition to ocean current transport, the atmospheric dispersion through the interaction of the Westerlies with East Asia monsoon is the important pathway of large-scale transport of pollutants from high latitude West Europe to middle latitude East Asia. Riverine input is the main transport pathway of radioactive pollutants released from Lop Nor to the East China Sea through the atmospheric dispersion, deposition and runoff processes.


Asunto(s)
Monitoreo del Ambiente , Sedimentos Geológicos/química , Radioisótopos de Yodo/análisis , Contaminantes Radiactivos del Suelo/análisis , Contaminantes Radiactivos del Agua/análisis , Asia , China , Europa (Continente) , Asia Oriental , Medio Oriente
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