Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 252
Filtrar
1.
J Org Chem ; 89(10): 6929-6936, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38717970

RESUMO

This study reports selective dual amino acylation and C-H bromination of aniline compounds enabled by Cu/O2 catalyst systems. This method involves crucial oxidation-induced C-CN bond cleavage of α-methylene nitriles to generate an acylcyanide intermediate that is facilely intercepted by anilines. After amino acylation, the Cu(II) precatalyst in combination with NBS generates Cu(III)-Br in situ that engages in selective electrophilic para- or ortho-C-H bromination. The substrate scope, mechanistic aspects, and late-stage functionalization of biologically active anilines are studied. This study shows the synthetic potential of oxidative C-CN bond activation of nitriles for the development of valuable reactions.

2.
DNA Cell Biol ; 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38700464

RESUMO

Megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome (MPPH), a type of overgrowth syndrome, is characterized by progressive megalencephaly, cortical brain malformations, and distal limb anomalies. Previous studies have revealed that the overactivity of the phosphatidylinositol 3-kinase-Protein kinase B pathway and the increased cyclin D2 (CCND2) expression were the main factors contributing to this disease. Here, we present the case of a patient who exhibited megalencephaly, polymicrogyria, abnormal neuronal migration, and developmental delay. Serum tandem mass spectrometry and chromosome examination did not detect any metabolic abnormalities or copy number variants. However, whole-exome sequencing and Sanger sequencing revealed a de novo nonsense mutation (NM_001759.3: c.829C>T; p.Gln277X) in the CCND2 gene of the patient. Bioinformatics analysis predicted that this mutation may disrupt the structure and surface charge of the CCND2 protein. This disruption could potentially prevent polyubiquitination of CCND2, leading to its resistance against degradation. Consequently, this could drive cell division and growth by altering the activity of key cell cycle regulatory nodes, ultimately contributing to the development of MPPH. This study not only presents a new case of MPPH and expands the mutation spectrum of CCND2 but also enhances our understanding of the mechanisms connecting CCND2 with overgrowth syndromes.

3.
Chem Asian J ; : e202400297, 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38700937

RESUMO

A protocol has been developed for the synthesis of α­aryl-oxindoles from isatin and Grignard reagents in the presence of diphenyl phosphite for the first time. This reaction was conveniently carried out under mild conditions in a one-pot fashion with moderate to excellent yields.

4.
Sci Total Environ ; 927: 172039, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38552977

RESUMO

Alpine grassland is the main vegetation on the Qinghai-Tibetan Plateau (QTP) and exhibits high sensitivity to extreme weather events. With global warming, extreme weather events are projected to become more frequent on the QTP. However, the impact of these extreme weather events on the carbon cycle of alpine grassland remains unclear. The long-term in-situ carbon fluxes data was collected from 2013 to 2022 at an alpine grassland site to examine the impact of extreme low air temperature (ELT) and reduced moisture (including air and soil) on carbon fluxes during the growing season. Our findings indicated that a significant increase in net ecosystem production (NEP) after 2019, with the average NEP increasing from 278.91 ± 43.27 g C m-2 year-1 during 2013-2018 to 415.45 ± 45.29 g C m-2 year-1 during 2019-2022. The ecosystem carbon use efficiency (CUE) increased from 0.38 ± 0.06 during 2013-2018 to 0.62 ± 0.11 during 2019-2022. By combining concurrently measured environmental factors and remote sensing data, we identified the factors responsible for the abrupt change in the NEP after 2019. This phenomenon was caused by an abrupt decrease in ecosystem respiration (Reco) after 2019, which resulted from the inhibition imposed by ELT and reduced moisture. In contrast, gross primary production (GPP) remained stable from 2013 to 2022, which was confirmed by the remotely sensed vegetation index. This study highlights that combined extreme weather events associated with climate change can significantly impact the NEP of alpine grassland, potentially affecting different carbon fluxes at different rates. These findings provide new insights into the mechanisms governing the carbon cycle of alpine grassland.


Assuntos
Ciclo do Carbono , Monitoramento Ambiental , Pradaria , Tibet , Mudança Climática , Temperatura Baixa , Ecossistema
5.
ACS Sens ; 9(1): 195-205, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38166241

RESUMO

A NO2 sensor with a detection limit down to the ppb level based on pristine SnO2 has been developed through a facile poly(acrylic acid)-mediated hydrothermal method. SnO2 particles of solid microsphere, hollow microsphere, and nanosphere morphologies were synthesized, with respective constitutional crystallite of size ∼2 µm in length and 10-20 nm and ∼7 nm in diameter. All sensors show great selectivity to NO2. The hollow microsphere sensor exhibits the best performance, with medium specific surface area (SSA), followed by the nanosphere sensor with the largest SSA. This is attributed to the superposition of two opposite effects on sensor response with increased SSA: more adsorption sites and fewer electrons to be taken out with overly small crystallite that may reach complete depletion. O2 is found to speed up the response and recovery times but reduce the response because O adsorbates facilitate the adsorption/desorption of NO2 thermodynamically, and the two oxidizing gases compete in harvesting electrons from SnO2. The adverse effect of humidity can be minimized by operating the sensor at 110 °C. The response of the hollow microsphere sensor to 50 ppb of NO2 is 8.8 (Rg/Ra) at room temperature, and it increases to 15.1 at 110 °C. These findings are useful for developing other oxidizing gas semiconductor sensors.


Assuntos
Nanosferas , Oxigênio , Dióxido de Nitrogênio , Microesferas , Gases
6.
J Colloid Interface Sci ; 660: 974-988, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38286057

RESUMO

Metal-organic frameworks (MOFs) have been regarded as a potential candidate with great application prospects in the field of gas sensing. Although plenty of previous efforts have been made to improve the sensitivity of MOF-based nanocomposites, it is still a great challenge to realize ultrafast and high selectivity to typical flammable gases in a wide range. Herein, porous xPd-NPs@ZnO were prepared by optimized heat treatment, which maintained the controllable morphology and high specific surface area of 471.08 m2g-1. The coupling effects of photoexcitation and thermal excitation on the gas-sensing properties of nanocomposites were systematically studied. An ultrafast high response of 88.37 % towards 200 ppm H2 was realized within 1.2 s by 5.0Pd-NPs@ZnO under UV photoexcitation. All xPd-NPs@ZnO exhibited favorable linearity over an extremely wide range (0.2-4000 ppm H2) of experimental tests, indicating the great potential in quantitative detection. The photoexcited carriers enabled the nanocomposites a considerable response at lower operating temperatures, which made diverse applications of the sensors. The mechanisms of high sensing performances and the photoexcitation enhancement were systematically explained by DFT calculations. This work provides a solid experimental foundation and theoretical basis for the design of controllable porous materials and novel photoexcited gas detection.

7.
Ann Clin Lab Sci ; 53(6): 819-824, 2024 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-38182154

RESUMO

OBJECTIVE: Deep learning has been shown to be useful in detecting breast cancer metastases by analyzing whole slide images (WSI) of sentinel lymph nodes; however, it requires extensive analysis of all the lymph node slides. Our deep learning study attempts to provide a rapid screen for metastasis by analyzing only a small set of image patches to detect changes in tumor environment. METHODS: We designed a convolutional neural network to build a diagnostic model for metastasis detection. We obtained WSIs of Hematoxylin and Eosin-stained slides from 34 cases with equal distribution in positive/negative categories. Two WSIs were selected from each case for a total of 69 WSIs. From each WSI, 40 image patches (100x100 pixels) were obtained to yield 2720 image patches, from which 2160 (79%) were used for training, 240 (9%) for validation, and 320 (12%) for testing. Interobserver variation was also examined among 3 users. RESULTS: The test results showed excellent diagnostic results: accuracy (91.15%), sensitivity (77.92%), and specificity (92.09%). No significant variation in results was observed among the 3 observers. CONCLUSION: This preliminary study provided a proof of concept for conducting a rapid screen for metastasis rather than an exhaustive search for tumors in all fields of all sentinel lymph nodes.


Assuntos
Neoplasias da Mama , Aprendizado Profundo , Melanoma , Linfonodo Sentinela , Neoplasias Cutâneas , Humanos , Feminino , Neoplasias da Mama/diagnóstico
8.
Eur Radiol ; 34(4): 2716-2726, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37736804

RESUMO

OBJECTIVES: To investigate if delta-radiomics features have the potential to predict the major pathological response (MPR) to neoadjuvant chemoimmunotherapy in non-small cell lung cancer (NSCLC) patients. METHODS: Two hundred six stage IIA-IIIB NSCLC patients from three institutions (Database1 = 164; Database2 = 21; Database3 = 21) who received neoadjuvant chemoimmunotherapy and surgery were included. Patients in Database1 were randomly assigned to the training dataset and test dataset, with a ratio of 0.7:0.3. Patients in Database2 and Database3 were used as two independent external validation datasets. Contrast-enhanced CT scans were obtained at baseline and before surgery. The delta-radiomics features were defined as the relative net change of radiomics features between baseline and preoperative. The delta-radiomics model and pre-treatment radiomics model were established. The performance of Immune-Related Response Evaluation Criteria in Solid Tumors (iRECIST) for predicting MPR was also evaluated. RESULTS: Half of the patients (106/206, 51.5%) showed MPR after neoadjuvant chemoimmunotherapy. For predicting MPR, the delta-radiomics model achieved a satisfying area under the curves (AUCs) values of 0.768, 0.732, 0.833, and 0.716 in the training, test, and two external validation databases, respectively, which showed a superior predictive performance than the pre-treatment radiomics model (0.644, 0.616, 0.475, and 0.608). Compared with iRECIST criteria (0.624, 0.572, 0.650, and 0.466), a mixed model that combines delta-radiomics features and iRECIST had higher AUC values for MPR prediction of 0.777, 0.761, 0.850, and 0.670 in four sets. CONCLUSION: The delta-radiomics model demonstrated superior diagnostic performance compared to pre-treatment radiomics model and iRECIST criteria in predicting MPR preoperatively in neoadjuvant chemoimmunotherapy for stage II-III NSCLC. CLINICAL RELEVANCE STATEMENT: Delta-radiomics features based on the relative net change of radiomics features between baseline and preoperative CT scans serve a vital support tool in accurately identifying responses to neoadjuvant chemoimmunotherapy, which can help physicians make more appropriate treatment decisions. KEY POINTS: • The performances of pre-treatment radiomics model and iRECIST model in predicting major pathological response of neoadjuvant chemoimmunotherapy were unsatisfactory. • The delta-radiomics features based on relative net change of radiomics features between baseline and preoperative CT scans may be used as a noninvasive biomarker for predicting major pathological response of neoadjuvant chemoimmunotherapy. • Combining delta-radiomics features and iRECIST can further improve the predictive performance of responses to neoadjuvant chemoimmunotherapy.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Área Sob a Curva , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Carcinoma Pulmonar de Células não Pequenas/terapia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/terapia , Terapia Neoadjuvante , Radiômica , Estudos Retrospectivos
9.
Int J Biol Macromol ; 254(Pt 2): 127858, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37924917

RESUMO

Rosmarinic acid (RA) and salvianolic acid B (SAB) are main phenolic acids in Salvia miltiorrhiza Bunge have been widely used in the treatment of cardiovascular and cerebrovascular diseases due to their excellent pharmacological activity. RA is a precursor of SAB, and tyrosine transaminase (TAT, EC 2.6.1.5) is a crucial rate-limiting enzyme in their metabolism pathway. This study identified a novel TAT gene, SmTAT3-2, and found that it is a new transcript derived from unconventional splicing of SmTAT3. We used different substrates for enzymatic reaction with SmTAT1, SmTAT3 and SmTAT3-2. Subcellular localization of SmTAT1 and SmTAT3-2 was completed based on submicroscopic techniques. In addition, they were overexpressed and CRISPR/Cas9 gene edited in hairy roots of S. miltiorrhiza. Revealed SmTAT3-2 and SmTAT1 showed a stronger affinity for L-tyrosine than SmTAT3, localized in the cytoplasm, and promoted the synthesis of phenolic acid. In overexpressed SmTAT3-2 hairy roots, the content of RA and SAB was significantly increased by 2.53 and 3.38 fold, respectively, which was significantly higher than that of overexpressed SmTAT1 strain compared with EV strain. These findings provide a valuable key enzyme gene for the phenolic acids metabolism pathway and offer a theoretical basis for the clinical application.


Assuntos
Salvia miltiorrhiza , Tirosina Transaminase , Tirosina Transaminase/genética , Salvia miltiorrhiza/genética , Salvia miltiorrhiza/química , Genes tat , Hidroxibenzoatos/metabolismo , Ácido Rosmarínico , Raízes de Plantas/química , Regulação da Expressão Gênica de Plantas
10.
Anal Chem ; 95(50): 18635-18643, 2023 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-38064655

RESUMO

Cr(III) is a common oxidation state of chromium, and its presence in the environment can occur naturally or as a result of human activities, such as industrial processes, mining, and waste disposal. This article explores the application of machine learning algorithms for the intelligent decision recognition and quantification of Cr(III) in chromium speciation. Three different machine learning models, namely, the Decision Tree (DT) model, the PCA-SVM (Principal Component Analysis-Support Vector Machine) model, and the LDA (Linear Discriminant Analysis) model, were employed and evaluated for accurate and efficient classification of chromium concentrations based on their fluorescence responses. Furthermore, stepwise multiple linear regression analysis was utilized to achieve a more precise quantification of trivalent chromium concentrations through fluorescence visualization. The results demonstrate the potential of machine learning algorithms in accurately detecting and quantifying Cr(III) in chromium speciation with implications for environmental and industrial applications in chromium detection and quantification. The findings from this research pave the way for further exploration and implementation of these models in real-world scenarios, offering valuable insights into various environmental and industrial contexts.

11.
J Org Chem ; 88(24): 16735-16741, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-38050841

RESUMO

This study reports sequential dehydrogenation and transfer oxygenation of 1,2-diarylepoxides by high-valent phenCu(III)(CF3)3 and DMSO to produce 1,2-diketones. The Cu(III)-CF3 compound serves as a CF3 radical source to abstract the hydrogen atom of the epoxide ring. The resulting ether α-carbon radical undergoes ring-opening rearrangement to give a ketone α-carbon radical intermediate, which is oxygenated by DMSO with the release of Me2S. The combination of a Cu(III)-CF3 compound and DMSO may be exploited to develop other novel oxidation reactions.

12.
Heliyon ; 9(10): e20419, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37780764

RESUMO

The spatial unit of urban agglomerations is extremely important for reducing negative externalities in large cities. Although there is a large body of literature on reducing negative externalities within a single city, few studies have focused on the important role of urban agglomerations. To offer a new method for reducing negative externalities in large cities and fill in this gap in the literature, our paper examines the effect of spatial functional division in urban agglomerations on negative externalities in large cities by applying the concept of spatial functional division to data on 19 urban agglomerations and data on negative externalities from 35 large cities in China. We first show that spatial functional division in urban agglomerations can significantly reduce negative externalities. The robustness of the results was confirmed using the instrumental variable approach, alternative indicators, and other robustness checks. Furthermore, we identified the productivity improvement mechanisms in large cities that generate the observed mitigatory effects of spatial functional division in urban agglomerations on negative externalities in large cities. The heterogeneous analyzes indicate that spatial functional division in urban agglomerations has a stronger mitigatory effect on negative externalities in large cities in the context of higher inter-city connectivity, greater polycentricity, and official approval regarding urban agglomerations' regional planning. Our findings emphasize the importance of urban agglomerations for reducing negative externalities in large cities, particularly in China, where urban agglomerations have been rapidly developing and spatial functional division in urban agglomerations has been continuously improving.

13.
Gen Physiol Biophys ; 42(5): 417-429, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37702447

RESUMO

Myocardial fibrosis is an underlying cause of many cardiovascular diseases. Novel insights into the epigenetic control of myocardial fibrosis are now emerging. The current work is focused on investigating the biological role of DNA methyltransferase 1 (DNMT1) in myocardial fibrosis as well as the underlying mechanism. Our findings revealed that DNMT1 expression levels were upregulated, whereas miR-133b expression levels were decreased in a rat model of myocardial fibrosis following myocardial infarction. In vitro, the expression levels of DNMT1 increased and those of miR-133b decreased after Ang-II treatment in cardiac fibroblasts. DNMT1 knockdown inhibited Ang-II-induced cardiac myofibroblast activation, and DNMT1 overexpression increased the proliferation and collagen generation of cardiac myofibroblasts. Furthermore, DNMT1 expression levels decreased, while miR-133b expression levels increased after treatment with 5-Aza (5-Azacytidine, a known inhibitor of DNA methylation) in Ang-II-induced cardiac fibroblasts. BSP (Bisulfite sequencing PCR) results showed a marked decrease in methylation levels in the miR-133b promoter region upon overexpression of DNMT1, whereas knockdown of DNMT1 blocked increased methylation levels in the miR-133b promoter region in Ang-II-induced cardiac fibroblasts. Finally, 5-Aza treatment reduced the progression of myocardial fibrosis after myocardial infarction in rats in vivo. Collectively, our results suggest that DNMT1 mediates CTGF expression in cardiac fibroblast activation by regulating the methylation of miR-133b. The present work reveals the unique role of the DNMT1/miR-133b/CTGF axis in myocardial fibrosis, thus suggesting its great therapeutic potential in the treatment of cardiac diseases.


Assuntos
MicroRNAs , Infarto do Miocárdio , Animais , Ratos , Azacitidina/farmacologia , Metilação de DNA , Fibrose , Coração , MicroRNAs/genética , Infarto do Miocárdio/genética
14.
Hortic Res ; 10(6): uhad070, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37293531

RESUMO

Seedless grapes are increasingly popular throughout the world, and the development of seedless varieties is a major breeding goal. In this study, we demonstrate an essential role for the grapevine MADS-box gene VvMADS28 in morphogenesis of the ovule. We found that VvMADS28 mRNA accumulated in the ovules of a seeded cultivar, 'Red Globe', throughout the course of ovule and seed development, especially within the integument/seed coat. In contrast, in the seedless cultivar 'Thompson Seedless', VvMADS28 was expressed only weakly in ovules, and this was associated with increased levels of histone H3 lysine 27 trimethylation (H3K27me3) within the VvMADS28 promoter region. RNAi-mediated transient suppression of VvMADS28 expression in 'Red Globe' led to reduced seed size associated with inhibition of episperm and endosperm cell development. Heterologous overexpression of VvMADS28 in transgenic tomatoes interfered with sepal development and resulted in smaller fruit but did not obviously affect seed size. Assays in yeast cells showed that VvMADS28 is subject to regulation by the transcription factor VvERF98, and that VvMADS28 could interact with the Type I/ Mß MADS-domain protein VvMADS5. Moreover, through DNA-affinity purification-sequencing (DAP-seq), we found that VvMADS28 protein specifically binds to the promoter of the grapevine WUSCHEL (VvWUS) gene, suggesting that maintenance of the VvMADS28-VvMADS5 dimer and VvWUS expression homeostasis influences seed development. Taken together, our results provide insight into regulatory mechanisms of ovule and seed development associated with VvMADS28.

15.
Nat Commun ; 14(1): 3245, 2023 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-37277342

RESUMO

Producing functional soft fibers via existing spinning methods is environmentally and economically costly due to the complexity of spinning equipment, involvement of copious solvents, intensive consumption of energy, and multi-step pre-/post-spinning treatments. We report a nonsolvent vapor-induced phase separation spinning approach under ambient conditions, which resembles the native spider silk fibrillation. It is enabled by the optimal rheological properties of dopes via engineering silver-coordinated molecular chain interactions and autonomous phase transition due to the nonsolvent vapor-induced phase separation effect. Fiber fibrillation under ambient conditions using a polyacrylonitrile-silver ion dope is demonstrated, along with detailed elucidations on tuning dope spinnability through rheological analysis. The obtained fibers are mechanically soft, stretchable, and electrically conductive, benefiting from elastic molecular chain networks via silver-based coordination complexes and in-situ reduced silver nanoparticles. Particularly, these fibers can be configured as wearable electronics for self-sensing and self-powering applications. Our ambient-conditions spinning approach provides a platform to create functional soft fibers with unified mechanical and electrical properties at a two-to-three order of magnitude less energy cost under ambient conditions.

16.
Environ Sci Technol ; 57(26): 9603-9614, 2023 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-37342920

RESUMO

Tetracycline pollution in soil irreversibly damages the biosafety of plants by inhibiting the mitochondrial function. Some traditional Chinese medicine (TCM) plants, such as Salvia miltiorrhiza Bunge, have a strong tolerance to mitochondrial damage. We comprehensively compared the doxycycline (DOX) tolerances of two ecotypes of S. miltiorrhiza in the Sichuan and Shandong provinces and found that the Sichuan ecotype had a lower yield reduction, more stable accumulation of medicinal ingredients, higher mitochondrial integrity, and a more robust antioxidant system. The synergetic response networks under DOX pollution of both ecotypes were constructed using RNA sequencing and ultrahigh-performance liquid chromatography-tandem mass spectrometry. The differentiation of the downstream pathways of aromatic amino acids (AAAs) produced variations in the DOX tolerance of S. miltiorrhiza in different regions. The Sichuan ecotype maintained redox homeostasis and xylem development by activating salvianolic acid and indole biosynthesis, while the Shandong ecotype balanced chemical and mechanical defenses by regulating the flavonoid biosynthesis. Rosmarinic acid, a downstream AAA molecule, maintains the mitochondrial homeostasis of plant seedlings under DOX pollution by targeting the ABCG28 transporter. We also highlight the significance of downstream AAA small molecules in guiding the development of bio-based environmental pollution remediation agents.


Assuntos
Salvia miltiorrhiza , Salvia miltiorrhiza/química , Salvia miltiorrhiza/genética , Salvia miltiorrhiza/metabolismo , Doxiciclina/farmacologia , Doxiciclina/análise , Doxiciclina/metabolismo , Ecótipo , Multiômica , Poluição Ambiental , Raízes de Plantas/química , Raízes de Plantas/metabolismo
17.
Int Wound J ; 20(8): 3249-3254, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37132096

RESUMO

A meta-analysis investigation was executed to measure the influence of multiple arterial grafts (MAGs) compared with single arterial graft (SAG) for coronary artery bypass grafting (CABG) on sternal wound complications (SWCs). A comprehensive literature inspection till February 2023 was applied and 1048 interrelated investigations were reviewed. The seven chosen investigations enclosed 11 201 individuals with CABG in the chosen investigations' starting point, 4870 of them were using MAGs, and 6331 were using SAG. Odds ratio (OR) in addition to 95% confidence intervals (CIs) were utilised to compute the value of the effect of the MAGs compared with SAG for CABG on SWCs by the dichotomous approaches and a fixed or random model. MAGs had significantly higher SWC (OR, 1.38; 95% CI, 1.10-1.73, P = .005) compared with those with SAG in CABG. MAGs had significantly higher SWC compared with those with SAG in CABG. However, care must be exercised when dealing with its values because of the low number of selected investigations for the meta-analysis.


Assuntos
Ponte de Artéria Coronária , Doença da Artéria Coronariana , Humanos , Doença da Artéria Coronariana/cirurgia , Resultado do Tratamento
18.
Angew Chem Int Ed Engl ; 62(27): e202304754, 2023 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-37126395

RESUMO

Understanding the nature of single-atom catalytic sites and identifying their spectroscopic fingerprints are essential prerequisites for the rational design of target catalysts. Here, we apply correlated in situ X-ray absorption and infrared spectroscopy to probe the edge-site-specific chemistry of Co-N-C electrocatalyst during the oxygen reduction reaction (ORR) operation. The unique edge-hosted architecture affords single-atom Co site remarkable structural flexibility with adapted dynamic oxo adsorption and valence state shuttling between Co(2-δ)+ and Co2+ , in contrast to the rigid in-plane embedded Co1 -Nx counterpart. Theoretical calculations demonstrate that the synergistic interplay of in situ reconstructed Co1 -N2 -oxo with peripheral oxygen groups gives a rise to the near-optimal adsorption of *OOH intermediate and substantially increases the activation barrier for its dissociation, accounting for a robust acidic ORR activity and 2e- selectivity for H2 O2 production.

19.
Adv Mater ; 35(24): e2207916, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37119438

RESUMO

Self-sensing actuators are critical to artificial robots with biomimetic proprio-/exteroception properties of biological neuromuscular systems. Existing add-on approaches, which physically blend heterogeneous sensor/actuator components, fall short of yielding satisfactory solutions, considering their suboptimal interfaces, poor adhesion, and electronic/mechanical property mismatches. Here, a single homogeneous material platform is reported by creating a silver-polymer framework (SPF), thus realizing the seamless sensing-actuation unification. The SPF-enabled elastomer is highly stretchable (1200%), conductive (0.076 S m-1 ), and strong (0.76 MPa in-strength), where the stretchable polymer matrix synthesis and in situ silver nanoparticles reduction are accomplished simultaneously. Benefiting from the multimodal sensing capability from its architecture itself (mechanical and thermal cues), self-sensing actuation (proprio-deformations and external stimuli perceptions) is achieved for the SPF-based pneumatic actuator, alongside an excellent load-lifting attribute (up to 3700 times its own weight), substantiating its advantage of the unified sensing-actuation feature in a single homogenous material. In view of its human somatosensitive muscular systems imitative functionality, the reported SPF bodes well for use with next-generation functional tissues, including artificial skins, human-machine interfaces, self-sensing robots, and otherwise dynamic materials.


Assuntos
Complexos de Coordenação , Nanopartículas Metálicas , Humanos , Polímeros , Prata , Elastômeros
20.
Plant Dis ; 2023 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-36880858

RESUMO

Aconitum carmichaelii Debeaux is used as a traditional Chinese medicine with antiarrhythmic, antiinflammatory and other pharmacological functions. It is widely cultivated in China. According to our survey, about 60% of A. carmichaelii in Qingchuan, Sichuan, suffered from root rot, reducing yields by 30% in the past five years. Symptomatic plants exhibited stunted growth, dark brown roots, reduced root biomass, and fewer root hairs. The disease caused root rot and plant death in 50% of the infected plants. In October 2019, ten symptomatic 6-month-old plants were collected from fields in Qingchuan. Diseased pieces of the roots were surface sterilized with sodium hypochlorite solution (2%), rinsed three times in sterile water, plated on potato dextrose agar (PDA), and incubated at 25°C in the dark. Six single-spore isolates of a Cylindrocarpon-like anamorp were obtained. The colonies on PDA were 35 to 37 mm diam after seven days with regular margins. The plates were covered with felty aerial mycelium, white to buff, and the reverse side chestnut near center with a ochre to yellowish leading edge. On spezieller nährstoffarmer agar (SNA), macroconidia were 1 to 3 septate, straight or slightly curved, cylindrical, with rounded ends, and varied in size: 1-septate 15.1 to 33.5 × 3.7 to 7.3 µm (n=250), 2-septate 16.5 to 48.5 × 3.7 to 7.6 µm (n=85), and 3-septate 22.0 to 50.6 × 4.9 to 7.4 µm (n=115). Microconidia were ellipsoid to ovoid, and 0 to 1 septate; aseptate spores were 4.5 to 16.8 × 1.6 to 4.9 µm (n=200), and 1-septate spores were 7.4 to 20.0 × 2.4 to 5.1 µm (n=200). The chlamydospores were brown, thick-walled, globose to subglobose, 7.9 to 15.9 µm (n=50). The morphology of these isolates was consistent with the previous description of Ilyonectria robusta (Cabral et al. 2012). Isolate QW1901 was characterized by sequencing the ITS, TUB, H3, and tef1α loci using previously reported primer pairs: ITS1/ITS4 (White et al. 1990), T1/Bt-2b (O'Donnell and Cigelnik 1997), CYLH3F/CYLH3R (Crous et al. 2004), and EF1/EF2 (O'Donnell et al. 1998). A Blastn search of the sequences of ITS, TUB, H3, and tef1α showed that QW1901 shared 99.26, 97.89, 97.79, and 99.17 % identities, respectively, with the ex-type strain of I. robusta (CBS308.35). The ITS, TUB, H3, and tef1α sequences were deposited in GenBank under accession nos. MW534715, and MW880180 to MW880182, respectively. A phylogenetic tree was constructed from a neighbor-joining analysis on the alignment of the combined ITS, TUB, H3, and tef1α sequence. QW1901 was clustered with the ex-type strain of I. robusta. To confirm the pathogenicity of I. robusta, bare roots of healthy 6-month-old A. carmichaelii were inoculated with mycelial plugs of 7-day-old QW1901 colonies selected randomly (Lu et al. 2015). Five needle-wound lateral roots and five intact roots were inoculated as replicates with pathogen-free agar plugs as a control. Then, all plants were grown in sterile soil in a growth chamber at 20±1°C and watered regularly. Pathogenicity assays were repeated twice. After 20 days of cultivation, infected plants exhibited symptoms similar to those observed in the field. All control plants remained asymptomatic. Sequencing confirmed the re-isolation of I. robusta from the inoculated plants, satisfying Koch's hypothesis. Ilyonectria robusta has been reported to cause root rot of plants such as Codonopsis tangshen and Panax ginseng ( Lu et al. 2015; Zheng et al. 2021), and has also been reported to be isolated from Aconitum kongboense in China (Wang et al. 2015). However, this is the first report of the pathogen causing root rot of A. carmichaelii. Management measures, such as growing disease-free seedlings in sterile soil, should be used to minimize the risk of this pathogen.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...