Herein, we report a theoretical and experimental study of the water‐gas shift (WGS) reaction on Ir1/FeOx single‐atom catalysts. Water dissociates to OH* on the Ir1 single atom and H* on the ...first‐neighbour O atom bonded with a Fe site. The adsorbed CO on Ir1 reacts with another adjacent O atom to produce CO2, yielding an oxygen vacancy (Ovac). Then, the formation of H2 becomes feasible due to migration of H from adsorbed OH* toward Ir1 and its subsequent reaction with another H*. The interaction of Ir1 and the second‐neighbouring Fe species demonstrates a new WGS pathway featured by electron transfer at the active site from Fe3+−O⋅⋅⋅Ir2+−Ovac to Fe2+−Ovac⋅⋅⋅Ir3+−O with the involvement of Ovac. The redox mechanism for WGS reaction through a dual metal active site (DMAS) is different from the conventional associative mechanism with the formation of formate or carboxyl intermediates. The proposed new reaction mechanism is corroborated by the experimental results with Ir1/FeOx for sequential production of CO2 and H2.
Two sites are better than one: A redox mechanism with dual metal active site was found for the water‐gas shift (WGS) reaction on the Ir1/FeOx single‐atom catalyst by theoretical and experimental studies. The Ir1 and Fe atoms jointly facilitate the creation of an oxygen vacancy at the Fe species neighbouring the Ir1 atom, leading to sequential production of CO2 and H2.
Lactate dehydrogenase (LDH) is associated with the prognosis of many diseases, but the relationship between LDH and the poor prognosis (recurrence and death) of acute ischemic stroke (AIS) has not ...been fully clarified. This study aimed to investigate the association between admission LDH level and poor prognosis in patients with AIS. This retrospective study enrolled AIS patients treated in Taizhou Hospital of Zhejiang Province from July 2019 to December 2019. Poor prognosis included AIS recurrence and all-cause death at 3, 6, and 18 months. The correction between LDH and poor prognosis or all-cause death was assessed. Lasso Cox expression and multivariate Cox expression analyses were used to evaluate the association of LDH with the risk of poor prognosis and all-cause death, respectively. A nomogram was constructed to evaluate the predictive Values of LDH for the poor prognosis and all-cause death of AIS. 732 patients were included in the study. Multivariate analysis shows that admission LDH levels were significantly correlated with poor prognosis odds ratio (OR),1.003; 95% confidence interval (95% CI), 1.001-1.005; P = 0.001 and all-cause death (OR, 1.005; 95% CI, 1.000-1.009; P = 0.031). The correlation analysis showed that admission LDH level was positively correlated with National Institutes of Health Stroke Scale (NIHSS) score and modified Rankin Scale (mRS) score. Time-dependent receiver operating characteristic (td-ROC) curves analysis showed that the AUC values of admission LDH level for predicting prognosis of AIS patients in 3-month, 6-month, 12-month and 18-month were 0.706 (95% CI, 0.604-0.810), 0.653 (95% CI, 0.583-0.723), 0.616 (95% CI, 0.556-60676) and 0.610 (95% CI, 0.552-0.680), respectively. And td-ROC also showed that the AUC values of admission LDH level for predicting all-cause death of AIS patients in 3-month, 6-month,12-month and 18-month were 0.861 (95% CI, 0.764-0.958), 0.824 (95% CI, 0.753-0.890), 0.726 (95% CI, 0.633-0.819) and 0.715 (95% CI, 0.622-0.807), respectively. The nomograms were constructed to create the predictive models of the poor prognosis and all-cause death of AIS. Higher LDH levels are independently associated with poor prognosis and all-cause death of AIS.
COVID-19 has become a major global public health burden, currently causing a rapidly growing number of infections and significant morbidity and mortality around the world. Early detection with fast ...and sensitive assays and timely intervention are crucial for interrupting the spread of the COVID-19 virus (SARS-CoV-2). Using a mismatch-tolerant amplification technique, we developed a simple, rapid, sensitive and visual reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for SARS-CoV-2 detection based on its
gene. The assay has a high specificity and sensitivity, and robust reproducibility, and its results can be monitored using a real-time PCR machine or visualized via colorimetric change from red to yellow. The limit of detection (LOD) of the assay is 118.6 copies of SARS-CoV-2 RNA per 25 μL reaction. The reaction can be completed within 30 min for real-time fluorescence monitoring, or 40 min for visual detection when the template input is more than 200 copies per 25 μL reaction. To evaluate the viability of the assay, a comparison between the RT-LAMP and a commercial RT-qPCR assay was made using 56 clinical samples. The SARS-CoV-2 RT-LAMP assay showed perfect agreement in detection with the RT-qPCR assay. The newly-developed SARS-CoV-2 RT-LAMP assay is a simple and rapid method for COVID-19 surveillance.
Direct conversion of methane to high value‐added oxygenates under mild conditions has attracted extensive interest. However, the over‐oxidation of target products is usually unavoidable due to the ...easily excessive activation of C−H bond on the sites of supported metal species. Here, we identified the most efficient Zr‐oxo nodes of UiO‐66 metal‐organic frameworks (MOFs) catalysts for the selective oxidation of methane with H2O2. These nodes were modified by three types of benzene 1, 4‐dicarboxylates (NH2‐BDC, H2BDC, and NO2‐BDC). Detailed characterizations and DFT calculations revealed that these ligands can effectively tune the electronic properties of Zr‐oxo nodes and the H2BDC ligand led to optimal electronic density of Zr‐oxo nodes in UiO‐66. Thus the UiO‐66‐H catalyst promoted the formation of ⋅OH species that adsorbed on Zr‐oxo nodes, and facilitated the activation of methane with a lower energy barrier and subsequent conversion to hydroxylation oxygenates with 100 % selectivity.
UiO‐66 metal‐organic frameworks (MOFs) catalysts modified with various ligands can directly convert CH4 into oxygenates with 100 % selectivity by using H2O2 as an oxidant under mild conditions. The Zr‐oxo nodes have different electronic properties that affected the anchoring of ⋅OH species to form effective Zroxo−⋅OH sites. These sites promote the activation of the C−H bond of CH4.
ABSTRACT
Drought and low temperature are two key environmental factors that induce adult citrus flowering. However, the underlying regulation mechanism is poorly understood. The bZIP transcription ...factor FD is a key component of the florigen activation complex (FAC) which is composed of FLOWERING LOCUS T (FT), FD, and 14‐3‐3 proteins. In this study, isolation and characterization of CiFD in citrus found that there was alternative splicing (AS) of CiFD, forming two different proteins (CiFDα and CiFDβ). Further investigation found that their expression patterns were similar in different tissues of citrus, but the subcellular localization and transcriptional activity were different. Overexpression of the CiFD DNA sequence (CiFD‐DNA), CiFDα, or CiFDβ in tobacco and citrus showed early flowering, and CiFD‐DNA transgenic plants were the earliest, followed by CiFDβ and CiFDα. Interestingly, CiFDα and CiFDβ were induced by low temperature and drought, respectively. Further analysis showed that CiFDα can form a FAC complex with CiFT, Ci14‐3‐3, and then bind to the citrus APETALA1 (CiAP1) promoter and promote its expression. However, CiFDβ can directly bind to the CiAP1 promoter independently of CiFT and Ci14‐3‐3. These results showed that CiFDβ can form a more direct and simplified pathway that is independent of the FAC complex to regulate drought‐induced flowering through AS. In addition, a bHLH transcription factor (CibHLH96) binds to CiFD promoter and promotes the expression of CiFD under drought condition. Transgenic analysis found that CibHLH96 can promote flowering in transgenic tobacco. These results suggest that CiFD is involved in drought‐ and low‐temperature‐induced citrus flowering through different regulatory patterns.
In citrus, alternative splicing of the transcription factor gene CiFD produces two different proteins, CiFDα and CiFDβ At low temperature, CiFDα forms a complex with CiFLOWERING LOCUS T and Ci14‐3‐3 to activate the expression of CiAPETALA1. Under drought conditions, CiFDβ directly binds to the CiAPETALA1 promoter to induce flowering.
Abstract Circumstantial evidence suggests that most tumours are heterogeneous and contain a small population of cancer stem cells (CSCs) that exhibit distinctive self-renewal, proliferation and ...differentiation capabilities, which are believed to play a crucial role in tumour progression, drug resistance, recurrence and metastasis in multiple malignancies. Given that the existence of CSCs is a primary obstacle to cancer therapy, a tremendous amount of effort has been put into the development of anti-CSC strategies, and several potential approaches to kill therapeutically-resistant CSCs have been explored, including inhibiting ATP-binding cassette transporters, blocking essential signalling pathways involved in self-renewal and survival of CSCs, targeting CSCs surface markers and destroying the tumour microenvironment. Meanwhile, an increasing number of therapeutic agents (e.g. small molecule drugs, nucleic acids and antibodies) to selectively target CSCs have been screened or proposed in recent years. Drug delivery technology-based approaches hold great potential for tackling the limitations impeding clinical applications of CSC-specific agents, such as poor water solubility, short circulation time and inconsistent stability. Properly designed nanocarrier-based therapeutic agents (or nanomedicines) offer new possibilities of penetrating CSC niches and significantly increasing therapeutic drug accumulation in CSCs, which are difficult for free drug counterparts. In addition, intelligent nanomedicine holds great promise to overcome pump-mediated multidrug resistance which is driven by ATP and to decrease detrimental effects on normal somatic stem cells. In this review, we summarise the distinctive biological processes related to CSCs to highlight strategies against inherently drug-resistant CSCs. We then focus on some representative examples that give a glimpse into state-of-the-art nanomedicine approaches developed for CSCs elimination. A perspective on innovative therapeutic strategies and the potential direction of nanomedicine-based CSC therapy in the near future is also presented.
MADS-box genes are involved in various developmental processes including vegetative development, flower architecture, flowering, pollen formation, seed and fruit development. However, the function of ...most MADS-box genes and their regulation mechanism are still unclear in woody plants compared with model plants. In this study, a MADS-box gene (CiMADS43) was identified in citrus. Phylogenetic and sequence analysis showed that CiMADS43 is a GOA-like Bsister MADS-box gene. It was localized in the nucleus and as a transcriptional activator. Overexpression of CiMADS43 promoted early flowering and leaves curling in transgenic Arabidopsis. Besides, overexpression or knockout of CiMADS43 also showed leaf curl phenotype in citrus similar to that of CiMADS43 overexpressed in Arabidopsis. Protein–protein interaction found that a SEPALLATA (SEP)-like protein (CiAGL9) interacted with CiMADS43 protein. Interestingly, CiAGL9 also can bind to the CiMADS43 promoter and promote its transcription. Expression analysis also showed that these two genes were closely related to seasonal flowering and the development of the leaf in citrus. Our findings revealed the multifunctional roles of CiMADS43 in the vegetative and reproductive development of citrus. These results will facilitate our understanding of the evolution and molecular mechanisms of MADS-box genes in citrus.
Exosomes are discrete populations of small (40-200 nm in diameter) membranous vesicles that are released into the extracellular space by most cell types, eventually accumulating in the circulation. ...As molecular messengers, exosomes exert a broad array of vital physiologic functions by transporting information between different cell types. Because of these functional properties, they may have potential as biomarker sources for prognostic and diagnostic disease. Recent research has found that exosomes have potential to be utilized as drug delivery agents for therapeutic targets. However, basic researches on exosomes and researches on their therapeutic potential both require the existence of effective and rapid methods for their separation from human samples. In the current absence of a standardized method, there are several methods available for the separation of exosomes, but very few studies have previously compared the efficiency and suitability of these different methods. This review summarized and compared the available traditional and novel methods for the extraction of exosomes from human samples and considered their advantages and disadvantages for use in clinical laboratories and point-of-care settings.
Supported noble metal nanoparticles (including nanoclusters) are widely used in many industrial catalytic processes. While the finely dispersed nanostructures are highly active, they are usually ...thermodynamically unstable and tend to aggregate or sinter at elevated temperatures. This scenario is particularly true for supported nanogold catalysts because the gold nanostructures are easily sintered at high temperatures, under reaction conditions, or even during storage at ambient temperature. Here, we demonstrate that isolated Au single atoms dispersed on iron oxide nanocrystallites (Au
1
/FeO
x
) are much more sinteringresistant than Au nanostructures, and exhibit extremely high reaction stability for CO oxidation in a wide temperature range. Theoretical studies revealed that the positively charged and surface-anchored Au1 atoms with high valent states formed significant covalent metal-support interactions (CMSIs), thus providing the ultra-stability and remarkable catalytic performance. This work may provide insights and a new avenue for fabricating supported Au catalysts with ultra-high stability.
The electroreduction of water for sustainable hydrogen production is a critical component of several developing clean-energy technologies, such as water splitting and fuel cells. However, finding a ...cheap and efficient alternative catalyst to replace currently used platinum-based catalysts is still a prerequisite for the commercialization of these technologies. Here we report a robust and highly active catalyst for hydrogen evolution reaction that is constructed by in situ growth of molybdenum disulfide on the surface of cobalt diselenide. In acidic media, the molybdenum disulfide/cobalt diselenide catalyst exhibits fast hydrogen evolution kinetics with onset potential of -11 mV and Tafel slope of 36 mV per decade, which is the best among the non-noble metal hydrogen evolution catalysts and even approaches to the commercial platinum/carbon catalyst. The high hydrogen evolution activity of molybdenum disulfide/cobalt diselenide hybrid is likely due to the electrocatalytic synergistic effects between hydrogen evolution-active molybdenum disulfide and cobalt diselenide materials and the much increased catalytic sites.
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