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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.
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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 CompletoRESUMEN
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.
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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/metabolismoRESUMEN
Carbonic anhydrases (CAs), as zinc metalloenzymes, are ubiquitous in nature and play essential roles in diverse biological processes. Although CAs have been broadly explored and studied, comprehensive characteristics of CA gene family members in the soybean (Glycine max) are still lacking. A total of 35 CA genes (GmCAs) were identified; they distributed on sixteen chromosomes of the soybean genome and can be divided into three subfamilies (α-type, ß-type, and γ-type). Bioinformatics analysis showed that the specific GmCA gene subfamily or clade exhibited similar characteristics and that segmental duplications took the major role in generating new GmCAs. Furthermore, the synteny and evolutionary constraints analyses of CAs among soybean and distinct species provided more detailed evidence for GmCA gene family evolution. Cis-element analysis of promoter indicated that GmCAs may be responsive to abiotic stress and regulate photosynthesis. Moreover, the expression patterns of GmCAs varied in different tissues at diverse developmental stages in soybean. Additionally, we found that eight representative GmCAs may be involved in the response of soybean to low phosphorus stress. The systematic investigation of the GmCA gene family in this study will provide a valuable basis for further functional research on soybean CA genes.
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Anhidrasas Carbónicas , Glycine max , Glycine max/genética , Glycine max/metabolismo , Filogenia , Familia de Multigenes , Anhidrasas Carbónicas/genética , Anhidrasas Carbónicas/metabolismo , Biología Computacional , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estrés Fisiológico/genética , Genoma de PlantaRESUMEN
Foam is used as an efficient means of dust suppression in underground coal mines. The poor performance of conventional adding device of foaming agent restricts its wide application. The objective of this study is to propose and investigate a new parallel jet adding device (PJAD). Experimental results show that PJAD requires a greater water flow to produce negative pressure than the single stage jet adding device (SJAD) and is harder to generate cavitation. PJAD consumes a less pressure loss than SJAD and realizes any adding proportion below 1%, which is especially suitable for precision addition of foaming agent. A foaming system used for dust suppression is put forward with PJAD adding foaming agent. Field application indicates that foam achieves a far better dust suppression effect than the roadheader water spraying, and the foam cost is significantly reduced due to the low adding proportion of foaming agent. The marked dust suppression effect makes us believe that the proposed PJAD will greatly promote the large-scale application of foam technology used for dust suppression in underground coal mines.
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Minas de Carbón/instrumentación , Minas de Carbón/métodos , Polvo/prevención & control , Invenciones , Exposición Profesional/prevención & control , Sustancias Viscoelásticas/farmacología , Contaminantes Atmosféricos/farmacocinética , Contaminación del Aire/prevención & control , Aire Comprimido , Diseño de Equipo , Humanos , Práctica Profesional , Sustancias Viscoelásticas/administración & dosificación , Sustancias Viscoelásticas/químicaRESUMEN
Polysaccharide has been widely used in medical and health field because of its function of immune regulation. The aim of present study was to use protein chip to test the 200 cytokines secreted by macrophages which were induced by the polysaccharides of Tricholoma matsutake (TMP-A) to study the role of TMP-A acting on macrophages and its mechanism, further understanding the mechanism of the TMP-A effect on immune activity. The results of the analysis indicated that among all of these cytokines, including IL-1ß, IL-10, IL-23, TNF-α, CD40L, G-CSF, etc. there are 73 up-regulated and 43 down-regulated cytokines. The KEGG analysis indicated that T. matsutake polysaccharide can influence the immune response of macrophages through a series of signaling pathways, and the three major signaling pathways are Jak-STAT signaling pathway, PI3K-Akt signaling pathway and NF-kappa B signaling pathway. Those three signaling pathway are closely related to the pathogenesis of many diseases. The results showed that TMP-A can activate immune cells to regulate the immunity.
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Adyuvantes Inmunológicos/farmacología , Antineoplásicos/farmacología , Citocinas/análisis , Polisacáridos Fúngicos/farmacología , Análisis por Matrices de Proteínas/métodos , Tricholoma/química , Animales , Citocinas/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Ratones , FN-kappa B/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Células RAW 264.7 , Transducción de Señal/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacosRESUMEN
BACKGROUND/AIMS: Recombinant adeno-associated virus (rAAV) is now in the clinic, yet production of rAAV remains problematic. We previously determined that human papillomavirus type 16 (HPV16) E1 protein boosts rAAV yields and E1 enhances AAV Rep78's replication-related biochemistries. Here, we deletion-mapped the helper domain within E1 to help glean its mechanism of action. METHODS: Rep78-E1 interaction was analyzed by Gal4-based yeast two-hybrid (Y2H)-cDNA assay. rAAV DNA replication was studied by AAV/helper plasmid transfection into HEK293 cells and Southern blot. Gene expression analysis was made of AAV and E1 plasmid transfection, cDNA generation, and then quantitative polymerase chain reaction. NCBI protein BLAST was used for the homology analysis. RESULTS: Gal4-Y2H- cDNA assay found in vivo Rep78-E1-binding activity across E1, but the carboxyl-third (amino acids [aa] 421-649) of E1 contained the predominant DNA replication helper domain. The amino-half of E1 (aa 1-337) inhibited transcription of rep (p5 promoter) and cap (p40, trending lower) from non-replicating helper plasmid by quantitative (q)RT-PCR. CONCLUSIONS: The aa 421-649 helper domain of HPV16 E1 includes the ATP-binding/helicase region of E1 which boosts rAAV production and has homology with the analogous region of parvovirus NS-1/Rep78 by NCBI protein BLAST, suggesting these biochemistries are responsible for the mechanism of action in E1 helper function.
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Dependovirus/fisiología , Proteínas Oncogénicas Virales/metabolismo , Replicación Viral/efectos de los fármacos , Southern Blotting , Análisis Mutacional de ADN , Perfilación de la Expresión Génica , Células HEK293 , Humanos , Proteínas Oncogénicas Virales/genética , Técnicas del Sistema de Dos HíbridosRESUMEN
Objective: To evaluate the transmission risk and features of schistosomiasis by analyzing the data concerning positive rates of anti-schistosome antibody using catalytic models. Methods: Cross-sectional survey was conducted in seven villages with different endemicity of schistosomiasis in Jiangxi (Caohui, Xinhua, Jingtou villages), Anhui (Yuye, Tieguai, Longshang villages) and Hubei (Hebei village) Provinces in 2008. Serum samples were collected and indirect hemagglutination assay was performed to detect anti-schistosome antibodies in serum. Antibody positive rate was calculated and differences among villages and age groups as well as between genders were analyzed. Data of antibody positive rate based on age strata for each village were analyzed by two-stage catalytic model and reversible and two-stage compound catalytic model. Parameters of each model were estimated through the maximum likelihood method. Seroconversion rate and sero-negative conversion rate were estimated in the two-stage catalytic model. Seroconversion rate, seroreversion rate and sero-negative conversion rate were estimated in reversible and two-stage compound catalytic model. The fitting effect was evaluated through correlation analysis and chi-square tests. The best fitted models and parameters were used to analyze the transmission risk and characteristics of schistosomiasis. Results: A total of 6 428 individuals were examined with an average schistosomiasis antibody positive rate of 39.80%ï¼2 485/6 428ï¼. In terms of age, the peak of antibody positive rate in Caohui, Xinhua, Jingtou, Yuye, Tieguai, Longshang, and Hebei villages occurred in the age group of 46-50 ï¼82.86%, 58/70ï¼, 31-35 ï¼60.78%, 31/51ï¼, 31-35 ï¼68.42%, 26/38ï¼, 41-45ï¼55.04%, 71/129ï¼, 51-55 ï¼62.38%, 63/101ï¼, 56-60 ï¼31.43%, 33/105ï¼, and 16-20 ï¼21.88%, 7/32ï¼ years old, respectively. In general, the antibody positive rate showed a trend of increase followed by a decrease with increasing age in each village. The best model for the data of Caohui, Xinhua and Jingtou and Yuye village was the two-stage catalytic model. The estimated seroconversion rate in these villages was 0.049 5, 0.044 0, 0.055 7, and 0.034 4 respectively, all higher than the corresponding sero-negative conversion rate of 0.005 9, 0.019 6, 0.015 5, and 0.017 8. The best model for the data of Longshang, Tieguai and Hebei villages was the reversible and two-stage compound model. The seroconversion rate in these villages was 0.062 9, 0.168 1, and 0.039 4 respectively, the seroreversion rate was 0.168 8, 0.121 1, and 0.152 2, and the sero-negative conversion rate was 0.001 7, 0.000 2, and 0.090 9. Conclusions: The catalytic model based on antibody positive rate by age strata could reflect the transmission rate and risk quantitatively and may provide guidance for making control strategies.
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Schistosoma , Esquistosomiasis , Animales , Anticuerpos Antihelmínticos , Biocatálisis , China , Estudios Transversales , Pruebas de Hemaglutinación , Humanos , Medición de RiesgoRESUMEN
BACKGROUND: Inflammation is a key etiologic component in atherogenesis and transforming growth factor beta 1 (TGFß1) is a well known anti-inflammatory cytokine which potentially might be used to limit it. Yet TGFß1 is pleiomorphic, causing fibrosis, cell taxis, and under certain circumstances, can even worsen inflammation. SMAD3 is an important member of TGFß1's signal transduction pathway, but is a fully intracellular protein. OBJECTIVES: With the hope of attenuating TGFß1's adverse systemic effects (eg. fibrosis) and accentuating its anti-inflammatory activity, we proposed the use of human (h)SMAD3 as an intracellular substitute for TGFß1. STUDY DESIGN: To test this hypothesis adeno-associated virus type 2/8 (AAV)/hSMAD3 or AAV/Neo (control) was tail vein injected into the low density lipoprotein receptor knockout (LDLR-KO) mice, then placed on a high-cholesterol diet (HCD). RESULTS: The hSMAD3 delivery was associated with significantly lower atherogenesis as measured by larger aortic cross sectional area, thinner aortic wall thickness, and lower aortic systolic blood velocity compared with Neo gene-treated controls. HSMAD3 delivery also resulted in fewer aortic macrophages by immunohistochemistry for CD68 and ITGAM, and quantitative reverse transcriptase polymerase chain reaction analysis of EMR and ITGAM. Overall, aortic cytokine expression showed an enhancement of Th2 response (higher IL-4 and IL-10); while Th1 response (IL-12) was lower with hSMAD3 delivery. While TGFß1 is often associated with increased fibrosis, AAV/hSMAD3 delivery exhibited no increase of collagen 1A2 or significantly lower 2A1 expression in the aorta compared with Neo-delivery. Connective tissue growth factor (CTGF), a mediator of TGFß1/SMAD3-induced fibrosis, was unchanged in hSMAD3-delivered aortas. In the liver, all three of these genes were down-regulated by hSMAD3 gene delivery. CONCLUSION: These data strongly suggest that AAV/hSMAD3 delivery gave anti-atherosclerosis therapeutic effect without the expected undesirable effect of TGFß1-associated fibrosis.
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Aorta/patología , Aterosclerosis/prevención & control , Colesterol en la Dieta/administración & dosificación , Dependovirus/genética , Receptores de LDL/genética , Proteína smad3/genética , Células Th2/inmunología , Transfección , Animales , Aterosclerosis/inmunología , Fibrosis , Vectores Genéticos , Ratones , Ratones NoqueadosRESUMEN
The diagnosis of Schistosoma japonicum (Sj) infection in low prevalence areas of the People's Republic of China is challenging due to the sensitivity of the detection methods, leading to an underestimation of the disease burden. We compared the sensitivities of the miracidium hatching test (MHT) with the modified Kato-Katz method (KK) and the combination of the two methods (KK-MHT) to detect Sj infection in low prevalence areas of China. The stool samples of 3,853 residents from 8 villages with a light to moderate prevalence (0-23%) of Sj infection were examined by KK, MHT and KK-MHT. The findings were inconsistent. The KK-MHT conbination gave more positives than either the KK or MHT alone. Using the KK-MHT, we determined the missed rates with the KK (mR(K)) and MHT (mR(H)) to be 30.1% and 10.2%, respectively. At light prevalence sites (infection rate < 10%) the mR(K) was 60.6%, significantly higher than the mR(K) of 22.3% found at moderate prevalence sites (10-23%). However, the mR(H) at the light and moderate prevalence sites were 11.54% and 9.90%, respectively (p > 0.05). The combination KK-MHT had the best sensitivity in low Sj prevalence areas in China and the KK method alone was the least sensitive. Using KK alone as a screening method will result in an underestimation of Sj infection disease burden.
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Recuento de Huevos de Parásitos/métodos , Schistosoma japonicum/aislamiento & purificación , Esquistosomiasis Japónica/diagnóstico , Animales , China/epidemiología , Ensayo de Inmunoadsorción Enzimática , Heces/parasitología , Humanos , Prevalencia , Esquistosomiasis Japónica/epidemiología , Esquistosomiasis Japónica/parasitología , Sensibilidad y Especificidad , Encuestas y CuestionariosRESUMEN
OBJECTIVE: To analyze the progress of implementation of integrated strategy with emphasis on the control of infectious sources and effectiveness for joint-project of schistosomiasis control in Hubei province. METHODS: Data on the endemic status and implementation of each integrated intervention in 6 collaborated counties including Gongan, Hanchuan, Honghu, Jiangling, Xiantao and Yangxin during 2009-2013 were collected and analyzed. 18 administrative villages with a history of endemic schistosomisis from 6 counties were selected for field survey. Individuals aged 6-65 years received screening test by IHA, and feces of antibody positive inhabitants were collected and tested by miracidia hatching technique. Hatching technique was conducted to determine the infection rate of schistosomiasis in cattle if there was any cattle existed. RESULTS: Various interventions were conducted with adaption to the local situation by the Departments of Agriculture, Water Conservancy, Forestry, and Health. The total number of cattle decreased from 75 388 at the beginning of 2009 to 1 805 at the end of 2013 in 6 counties with a reduction rate of 97.5%, while the prevalence in cattle reduced to 0-0.3% in 2013. Snail-infested areas were stable but areas with infected snails decreased significantly, and no infected snails were found in 2012-2013. Meanwhile, the infection rate of human beings on county level were less than 1%. No infected snails and cattle were found in 18 selected villages and the prevalence in inhabitants was in the range of 0-0.8%. CONCLUSION: Cooperation between provincial government and the Ministries of Health and Agruiculture accelerates the process to reach the criteria of transmission control of schistosomiasis in Hubei Province. However, sustainable effort in needed as the current endemic situation of schistosomiasis is stillunstable.
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Esquistosomiasis/epidemiología , Adolescente , Adulto , Anciano , Animales , Bovinos , Niño , China/epidemiología , Enfermedades Transmisibles , Heces , Necesidades y Demandas de Servicios de Salud , Humanos , Persona de Mediana Edad , Prevalencia , Caracoles , Adulto JovenRESUMEN
This study investigates the correlation between previous coal mine safety policies and accidents in China. Data on coal mine accidents and government regulatory information from 2008 to 2021 are collected. The characteristics of coal mine accidents are analyzed, and safety policy indexes are identified. An ordinary least squares (OLS) regression model is established to quantitatively analyze the correlation between accidents and safety policy. The study finds that safety policies have some impact on accident occurrence in coal mines. Although there has been a decrease in accidents and deaths over time, higher mortality rates are observed during periods of increased production intensity and on weekends. Gas accidents are the most common, followed by roof and flood accidents. The study concludes that national safety policies with wider coverage and a stronger system are effective in preventing accidents, but caution should be exercised to avoid reduced vigilance with decreasing death rates.
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Minas de Carbón , Accidentes de Trabajo/prevención & control , Carbón Mineral , Políticas , ChinaRESUMEN
Music-oriented auditory attention detection (AAD) aims at determining which instrument in polyphonic music a listener is paying attention to by analyzing the listener's electroencephalogram (EEG). However, the existing linear models cannot effectively mimic the nonlinearity of the human brain, resulting in limited performance. Thus, a nonlinear music-oriented AAD model is proposed in this paper. Firstly, an auditory feature and a musical feature are fused to represent musical sources precisely and comprehensively. Secondly, the EEG is enhanced if music stimuli are presented in stereo. Thirdly, a neural network architecture is constructed to capture nonlinear and dynamic interactions between the EEG and auditory stimuli. Finally, the musical source most similar to the EEG in the common embedding space is identified as the attended one. Experimental results demonstrate that the proposed model outperforms all baseline models. On 1-s decision windows, it reaches accuracies of 92.6% and 81.7% under mono duo and trio stimuli, respectively. Additionally, it can be easily extended to speech-oriented AAD. This work can open up new possibilities for studies on both brain neural activity decoding and music information retrieval.
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Música , Humanos , Percepción Auditiva , Electroencefalografía , Encéfalo , Redes Neurales de la Computación , Estimulación Acústica/métodosRESUMEN
The electric power sector is the primary contributor to carbon emissions in China. Considering the context of dual carbon goals, this paper examines carbon emissions within China's electricity sector. The research utilizes the LMDI approach for methodological rigor. The results show that the cumulative contribution of economies scale, power consumption factors and energy structure are 114.91%, 85.17% and 0.94%, which contribute to the increase of carbon emissions, the cumulative contribution of power generation efficiency and ratio of power dissipation to generation factor are -19.15% and -0.01%, which promotes the carbon reduction. The decomposition analysis highlights the significant influence of economic scale on carbon emissions in the electricity industry, among the seven factors investigated. Meanwhile, STIRPAT model, Logistic model and GM(1,1) model are used to predict carbon emissions, the average relative error between actual carbon emissions and the predicted values are 0.23%, 8.72% and 7.05%, which indicates that STIRPAT model is more suitable for medium- to long-term predictions. Based on these findings, the paper proposes practical suggestions to reduce carbon emissions and achieve the dual carbon goals of the power industry.
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Carbono , Electricidad , China , Carbono/análisis , Industrias , Centrales Eléctricas , Modelos TeóricosRESUMEN
The limitations of solvent residues, unmanageable film growth regions, and substandard performance impede the extensive utilization of metal-organic framework (MOF) films for biosensing devices. Here, we report a strategy for ion design in gas-phase synthesized flexible MOF porous film to attain universal regulation of biosensing performances. The key fabrication process involves atomic layer deposition of induced layer coupled with lithography-assisted patterning and area-selective gas-phase synthesis of MOF film within a chemical vapor deposition system. Sensing platforms are subsequently formed to achieve specific detection of H2O2, dopamine, and glucose molecules by respectively implanting Co, Fe, and Ni ions into the network structure of MOF films. Furthermore, we showcase a practical device constructed from Co ions-implanted ZIF-4 film to accomplish real-time surveillance of H2O2 concentration at mouse wound. This study specifically elucidates the electronic structure and coordination mode of ion design in MOF film, and the obtained knowledge aids in tuning the electrochemical property of MOF film for advantageous sensing devices.
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Técnicas Biosensibles , Dopamina , Técnicas Electroquímicas , Peróxido de Hidrógeno , Estructuras Metalorgánicas , Técnicas Biosensibles/métodos , Estructuras Metalorgánicas/química , Peróxido de Hidrógeno/análisis , Peróxido de Hidrógeno/química , Técnicas Electroquímicas/métodos , Animales , Ratones , Dopamina/análisis , Dopamina/química , Glucosa/análisis , Glucosa/aislamiento & purificación , Glucosa/química , Cobalto/química , Níquel/química , Iones/químicaRESUMEN
The Whirly (WHY) gene family, functioning as transcription factors, plays an essential role in the regulation of plant metabolic responses, which has been demonstrated across multiple species. However, the WHY gene family and its functions in soybean remains unclear. In this paper, we conducted genome-wide screening and identification to characterize the WHY gene family. Seven WHY members were identified and randomly distributed across six chromosomes. The phylogenetic evolutionary tree of WHY genes in soybean and other species was divided into five clades. An in-depth analysis revealed that segmental duplications significantly contributed to the expansion of GmWHYs, and the GmWHY gene members may have experienced evolutionary pressure for purifying selection in soybeans. The analysis of promoter Cis-elements in GmWHYs suggested their potential significance in addressing diverse stress conditions. The expression patterns of GmWHYs exhibited tissue-specific variations throughout the different stages of soybean development. Additionally, six GmWHY genes exhibited different responses to low phosphate stress. These findings will provide a theoretical basis and valuable reference for the future exploration of WHY gene function.
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Regulación de la Expresión Génica de las Plantas , Glycine max , Familia de Multigenes , Fosfatos , Filogenia , Proteínas de Plantas , Estrés Fisiológico , Glycine max/genética , Glycine max/metabolismo , Estrés Fisiológico/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fosfatos/metabolismo , Genoma de Planta , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Regiones Promotoras Genéticas , Evolución MolecularRESUMEN
BACKGROUND: The study burnout of medical students is more and more serious, which directly affects the study style of university and the learning quality of students. This has aroused the high attention of researchers and universities. This study aimed to explore the mechanism of the influence of school climate on academic burnout among medical students in Chinese cultural context. METHODS: 2411 medical students (50.52% female; mean age = 19.55, SD = 1.41, rang = 17-24 years) were investigated with psychological environment questionnaire, collective self-esteem scale, psychological capital scale and academic burnout scale. The data were analyzed by using a moderated mediation model with SPSS and the Process 4.0 macro. RESULTS: The results revealed that: (1) school climate had a significant negative predictive effect on academic burnout among medical students controlling for gender, grade and age (B = -0.40, p < 0.001). (2) Collective self-esteem played a partial mediating role in school climate and academic burnout (indirect effect = -0.28, 95% CI = [-0.32,-0.25], accounting for 52.83%). (3) The first and second half of the indirect effect of school climate on medical students' academic burnout were moderated by psychological capital (B = 0.03, p < 0.01; B = -0.09, p < 0.001).High level of psychological capital can enhance the link between school climate and collective self-esteem as well as the link between self-esteem and academic burnout. CONCLUSION: Creating a good school atmosphere and improving the level of collective self-esteem and psychological capital are beneficial to improve the academic burnout of medical students.
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Agotamiento Profesional , Estudiantes de Medicina , Humanos , Femenino , Adulto Joven , Adulto , Masculino , Estudiantes de Medicina/psicología , Agotamiento Psicológico , Agotamiento Profesional/psicología , Instituciones Académicas , AprendizajeRESUMEN
Revealing the characteristics of spontaneous combustion and re-combustion of oxidized coal is of great significance for the coal fire prevention and control. Synchronous Thermal Analyzer (STA) and Fourier Transform Infrared Spectrometer (FTIR) were used to measure the thermal kinetics and microscopic characteristics of coal samples with different oxidation degrees (unoxidized, 100 â, 200 â and 300 â oxidized coal). It is found that the characteristic temperatures decrease first and then increase with the increasing degree of oxidation. The ignition temperature of 100 â-O coal (oxidized at 100 â for 6 h) is relatively the lowest at 334.1 â. Pyrolysis and gas-phase combustion reactions dominate the weight loss process, while solid-phase combustion reactions are relatively minor. The gas-phase combustion ratio of 100 â-O coal is the highest at 68.56%. With the deepening of coal oxidation degree, the relative content of aliphatic hydrocarbons and hydroxyl groups gradually decreases, while that of oxygen-containing functional groups (C-O, C = O, COOH, etc.) increases first and then decreases, reaching the highest value of 42.2% at 100 â. Moreover, the 100 â-O coal has the minimum temperature at the point of maximum exothermic power of 378.5 â, the highest exothermic power of -53.09 mW/mg and the maximum enthalpy of -18,579 J/g. All results show that 100 â-O coal has the highest risk of spontaneous combustion than the other three coal samples. This suggests that there is a maximum point of spontaneous combustion risk in the range of pre-oxidization temperatures of oxidized coal.
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Carbón Mineral , Oxígeno , Cinética , Temperatura , TermodinámicaRESUMEN
As an organic-rich and mineral-rich mixture, the permittivity of oxidized lignite is dependent on several factors in the terahertz (THz) band. In this study, thermogravimetric experiments were conducted to determine the characteristic temperatures of three types of lignite. The microstructural characteristics of lignite after treatment at 150, 300, and 450 °C were investigated by Fourier transform infrared spectroscopy and X-ray diffraction. The results show that the changes in the relative contents of CO and SiO are contrary to those of OH and CH3/CH2 with temperature variation. The relative content of CO is unpredictable at 300 °C. The aromaticity and crystallite diameter show a regular variation with temperature. The microcrystalline structure of coal tends to undergo graphitization with temperature. The variation of crystallite height is random at 450 °C. The uniform variation in microstructural characteristics of different types of lignite with oxidation temperature proves the feasibility of identifying oxidized lignite by THz spectroscopy. Based on orthogonal experiment results, the influence of the coal type, particle diameter, oxidation temperature, and moisture content on the permittivity of oxidized lignite in the THz band was arranged in an order. The order of the factors' sensitivity for real part of permittivity is oxidation temperature > moisture content > coal type > particle diameter. Similarly, the order of the factors' sensitivity for imaginary part of permittivity is oxidation temperature > moisture content > particle diameter > coal type. The results reveal the capability of THz technology to characterize the microstructure of oxidized lignite and provide guidance for minimizing error in THz technology.
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This paper systematically studied the coupling effect of ambient pressure and tunnel slope on temperature distribution and smoke propagation in full-scale tunnel fires under natural ventilation by FDS. The downstream length (longitudinal length from fire source center to tunnel downstream exit) was also considered. The concept of "height difference of stack effect" was put forward when analyzing the mutual effect of tunnel slope and downstream length on smoke movement. The results show that the maximum smoke temperature beneath the ceiling decreases with the increasing ambient pressure or tunnel slope. The longitudinal smoke temperature decays faster with the decreasing ambient pressure or slope in inclined tunnel. The induced inlet airflow velocity increases with the increasing height difference of stack effect, while decreases with the increasing ambient pressure. And the smoke backlayering length decreases with the increasing height difference of stack effect. Taking heat release rate (HRR), ambient pressure, tunnel slope and downstream length into account, the prediction models of dimensionless induced inlet airflow velocity and smoke backlayering length in inclined tunnel fires at high altitude were developed, which agree well with our and others' results. The outcomes of current study are great meaningful to fire detection and smoke control in inclined tunnel fires at high altitude.
Asunto(s)
Incendios , Humo , Humo/análisis , Temperatura , CalorRESUMEN
In order to solve the problems of coal spontaneous combustion, poor inerting effect of traditional nitrogen injection, and waste of resources in goaf, based on the response surface methodology and Box-Behnken combination test principle, the self-developed continuous and precise nitrogen injection and fire-fighting equipment was used to study the best possible combination of nitrogen injection position (20-90 m), nitrogen injection amount (10-70 m3/min), and air supply volume (2100-2500 m3/min), aiming to minimize the width of the oxidation zone and CO concentration in goaf. The optimal key parameters of continuous precise nitrogen injection were determined as follows: nitrogen injection position 54.17 m, nitrogen injection amount 31.04 m3/min, and air supply 2484.81 m3/min. Under this condition, the width of the oxidation zone was 29.21 ± 0.3 m and the CO concentration was 28.1 ± 4.4 ppm, which were similar to the predicted results of the model (the width of the oxidation zone was 29.41 m; CO concentration was 27.28 ppm). The reliability of the model was verified. These preliminary studies have achieved the purpose of rapid control of the fire in the whole region of the goaf and provided valuable lessons for similar nitrogen injection fire prevention and extinguishing technologies in goaf.