RÉSUMÉ
Pathogenic bacteria are the main cause of bacterial infectious diseases, which have posed a grave threat to public health. Single-atom nanozymes have emerged as promising candidates for antibacterial applications, but their activities need to be further improved. Considering diatomic nanozymes exhibit superior metal loading capacities and enhanced catalytic performance, a new interlayer coupling diatomic nanozyme (IC-DAN) is constructed by modulating the coordination environment in an atomic-level engineering. It is well demonstrated that IC-DAN exhibited superior peroxidase-mimetic activity in the presence of H2O2 to yield abundant âOH and possessed high photothermal conversion ability, which synergistically achieves efficient antibacterial therapy. Therefore, IC-DAN shows great potential used as antibacterial agent in clinic and this study open a new route to developing high-performance artificial enzymes.
Sujet(s)
Antibactériens , Nanostructures , Myeloperoxidase , Antibactériens/pharmacologie , Catalyse , Peroxyde d'hydrogène/métabolisme , Nanostructures/composition chimique , Myeloperoxidase/métabolismeRÉSUMÉ
It is crucial to rationally design and synthesize atomic-scale transition metal-doped carbon catalysts with high electrocatalytic activity to achieve a high-efficient oxygen reduction reaction (ORR). Herein, an electrocatalyst comprised of Fe-Fe dual atom pairs and N-doped concave carbon are reported (N-CC@Fe DA) that achieves ultrahigh electrocatalytic ORR activity. The catalyst is prepared by a gaseous doping approach, with zeolitic imidazolate framework-8 (ZIF-8) as the carbon framework precursor and cyclopentadienyliron dicarbonyl dimer as the Fe-Fe atom pair precursor. The catalyst exhibits high cathodic ORR catalytic performance in an alkaline Zn/air battery and proton exchange membrane fuel cell (PEMFC), yielding peak power densities of 241 mW cm-2 and 724 mW cm-2, respectively, compared to 127 mW cm-2 and 1.20 W cm-2 with conventional Pt/C catalysts as cathodes. The presence of Fe atom pairs coordinate with N atoms is revealed by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) analysis, and Density Functional Theory (DFT) calculation results show that the Fe-Fe pair structure is beneficial for adsorbing oxygen molecules, activating the OâO bond, and desorbing OH* intermediates formed during oxygen reduction, resulting in a more efficient oxygen reaction. The findings may provide a new pathway for preparing ultra-high-performance doped carbon catalysts with Fe-Fe atom pair structures.
RÉSUMÉ
Since the successful clinical trial of AuroShell for photothermal therapy, there is currently intense interest in developing gold-based core-shell structures with near-infrared (NIR) absorption ranging from NIR-I (650-900 nm) to NIR-II (900-1700 nm). Here, we propose a seed-mediated successive growth approach to produce gold nanoshells on the surface of the nanoscale metal-organic framework (NMOF) of UiO-66-NH2 (UiO = the University of Oslo) in one pot. The key to this strategy is to modulate the proportion of the formaldehyde (reductant) and its regulator / oxidative product of formic acid to harness the particle nucleation and growth rate within the same system. The gold nanoshells propagate through a well-oriented and controllable diffusion growth pattern (points â facets â octahedron), which has not been identified. Most strikingly, the gold nanoshells prepared hereby exhibit an exceedingly broad and strong absorption in NIR-II with a peak beyond 1300 nm and outstanding photothermal conversion efficiency of 74.0%. Owing to such superior performance, these gold nanoshells show promising outcomes in photoacoustic (PA), computed tomography (CT), and photothermal imaging-guided photothermal therapy (PTT) for breast cancer, as demonstrated both in vitro and in vivo.
Sujet(s)
Nanocoquilles , Nanocoquilles/composition chimique , Thérapie photothermique , Or/composition chimique , Imagerie multimodale , PhotothérapieRÉSUMÉ
Enhanced imaging techniques using contrast agents enable high-resolution structural imaging to reveal space-occupying lesions but rarely provide detailed molecular information. To this end, we report a structural and molecular fusion magnetic resonance imaging (MRI) nanoprobe for differential diagnosis between benign and malignant tumors. This fusion nanoprobe, termed FFT NPs, follows a working mechanism involving a T1-/T2-weighted magnetic resonance tuning effect (MRET) between a magnetic Fe3O4 core and a paramagnetic Fe-tannic acid (Fe-TA) shell. The FFT NPs with an "always-on" inert T2 signal provide structural MRI (sMRI) contrast of tumors while affording an activated T1 signal in the presence of ATP, which is overproduced during the rapid growth of malignant tumors to enable molecular MRI (mMRI) of tumor lesions. We propose the use of the ratiometric mMRI:sMRI intensity to assist in the differential diagnosis of malignant 4T1 tumors from benign L929 fibroblast tumors. Furthermore, the dissociated FFT NPs were found to be able to catalyze H2O2 conversion in 4T1 tumors to generate excess reactive oxygen species (ROS) for chemodynamic therapy. The described fusion nanoprobe strategy enables the differential diagnosis of tumors from a combined spatial and molecular perspective with one-stop MRI imaging with potential applications in precision intervention.
Sujet(s)
Peroxyde d'hydrogène , Tumeurs , Humains , Diagnostic différentiel , Études de suivi , Imagerie par résonance magnétique/méthodes , Tumeurs/imagerie diagnostique , Tumeurs/traitement médicamenteux , Tumeurs/anatomopathologie , Produits de contraste/composition chimiqueRÉSUMÉ
Improving the activity and durability of carbon-based catalysts is a key challenge for their application in fuel cells. Herein, we report a highly active and durable Co/N co-doped carbon (CoNC) catalyst prepared via pyrolysis of Co-doped zeolitic-imidazolate framework-8 (ZIF-8), which was synthesized by controlling the feeding sequence to enable Co to replace Zn in the metal-organic framework (MOF). The catalyst exhibited excellent oxygen reduction reaction (ORR) performance, while the half-wave potential decreased by only 8 mV after 5,000 accelerated stress test (AST) cycles in an acidic solution. Furthermore, the catalyst exhibited satisfactory cathodic catalytic performance when utilized in a hydrogen/oxygen single proton exchange membrane (PEM) fuel cell and a Zn-air battery, yielding maximum power densities of 530 and 164 mW cm-2, respectively. X-ray absorption spectroscopy (XAS) and high-angle annular dark field-scanning transmission electron microscopy (HAAD-STEM) analyses revealed that Co was present in the catalyst as single atoms coordinated with N to form Co-N moieties, which results in the high catalytic performance. These results show that the reported catalyst is a promising material for inclusion into future fuel cell designs.
RÉSUMÉ
The molecular basis enabling the adaptation of animals to spatially heterogeneous environments is a critical clue for understanding the variation, formation, and maintenance of biodiversity in the context of global climate change. Mountain dragons (Agamidae: Diploderma) thrive in the Hengduan Mountain Region, a biodiversity hotspot and a typical spatially heterogeneous environment. Here, we compare the liver and muscle metabolome and gut microbiome of 11 geographical populations from three Diploderma species (D. iadinum, D. yulongsense, and D. vela) after 7 days acclimation in the same laboratory conditions. Amino acid metabolism, particularly the products of the glutathione cycle, accounted for major interspecies variations, implying its significance in genetic differentiation among mountain dragons. Notably, the cold-dwelling D. vela and D. yulongense populations tended to have higher glycerophosphate, glycerol-3-phosphocholine, and kinetin levels in their liver, higher carnosine levels in their muscle, and higher Lachnospiraceae levels in their gut. Phylogeny, net primary productivity (NPP), and the temperature had the highest explanation rate to the variations in muscle metabolome, liver metabolome, and gut microbiome, respectively, suggesting heterogeneity of biological systems in response to climatic variations. Therefore, we suggested that the organ heterogeneity in environmental responsiveness might be substantial for mountain dragons to thrive in complicated environments.
RÉSUMÉ
OBJECTIVE: To determine the value of conventional ultrasound combined with contrast-enhanced ultrasound (CEUS) in Breast Imaging Reporting and Data System (BI-RADS) Category 4 lesions as detected by MRI. METHODS: A total of 176 breast lesions from 171 patients were detected by MRI and categorised as BI-RADS 4. All patients also underwent ultrasound and CEUS scans. The combination of ultrasound-BI-RADS and CEUS 5-point scoring system created the Rerated BI-RADS (referred to as CEUS-BI-RADS). The diagnostic performances of ultrasound and CEUS-BI-RADS were then compared. A χ2 test was used to compare the CEUS features of mass-like and non-mass-like enhancement types of MRI-BI-RADS 4 lesions. RESULTS: There were 167 (167/176) breast lesions detected by ultrasound, with a detection rate of 94.89%, while all were subsequently detected by "second-look" ultrasound combined with CEUS, with a detection rate of 100%. The areas under the receiver operating characteristic curves for ultrasound and CEUS-BI-RADS were 0.810 and 0.940, respectively. The diagnostic efficiency of CEUS-BI-RADS was significantly higher than that of ultrasound alone (z = 3.264, p = 0.001). For both mass-like and non-mass-like enhancement types of MRI-BI-RADS 4 lesions, CEUS-BI-RADS demonstrated satisfactory sensitivity and accuracy. Moreover, 29 (29/176) category 4 lesions were downgraded to 3 by CEUS-BI-RADS. CONCLUSION: Ultrasound combined with CEUS can allow reclassification, reduce biopsy rates, and facilitate pre-surgical localisation for biopsy or surgery for MRI-BI-RADS 4 lesions. ADVANCES IN KNOWLEDGE: For MRI-BI-RADS Category 4 lesions with a wide range of malignancies, ultrasound combined with CEUS is a promising diagnostic approach with high clinical utility.
Sujet(s)
Tumeurs du sein , Échographie mammaire , Tumeurs du sein/imagerie diagnostique , Produits de contraste , Femelle , Humains , Imagerie par résonance magnétique , Études rétrospectives , Sensibilité et spécificité , Échographie/méthodes , Échographie mammaire/méthodesRÉSUMÉ
OBJECTIVE: HIV positive (HIV+) individuals with otherwise normal hearing ability show central auditory processing deficits as evidenced by worse performance in speech-in-noise perception compared with HIV negative (HIV-) controls. HIV infection and treatment are also associated with lower neurocognitive screening test scores, suggesting underlying central nervous system damage. To determine how central auditory processing deficits in HIV+ individuals relate to brain alterations in the cortex involved with auditory processing, we compared auditory network (AN) functional connectivity between HIV+ adults with or without speech-in-noise perception difficulties and age-matched HIV- controls using resting-state fMRI. DESIGN: Based on the speech recognition threshold of the hearing-in-noise test, twenty-seven HIV+ individuals were divided into a group with speech-in-noise perception abnormalities (HIV+SPabnl, 38.2 ± 6.8 years; 11 males and 2 females) and one without (HIV+SPnl 34.4 ± 8.8 years; 14 males). An HIV- group with normal speech-in-noise perception (HIV-, 31.3 ± 5.2 years; 9 males and 3 females) was also enrolled. All of these younger and middle-aged adults had normal peripheral hearing determined by audiometry. Participants were studied using resting-state fMRI. Independent component analysis was applied to identify the AN. Group differences in the AN were identified using statistical parametric mapping. RESULTS: Both HIV+ groups had increased functional connectivity (FC) in parts of the AN including the superior temporal gyrus, middle temporal gyrus, supramarginal gyrus, and Rolandic operculum compared to the HIV- group. Compared with the HIV+SPnl group, the HIV+SPabnl group showed greater FC in parts of the AN including the middle frontal and inferior frontal gyri. CONCLUSIONS: The classical auditory areas in the temporal lobe are affected by HIV regardless of speech perception ability. Increased temporal FC in HIV+ individuals might reflect functional compensation to achieve normal primary auditory perception. Furthermore, increased frontal FC in the HIV+SPabnl group compared with the HIV+SPnl group suggest that speech-in-noise perception difficulties in HIV-infected adults also affect areas involved in higher-level cognition, providing imaging evidence consistent with the hypothesis that HIV-related neurocognitive deficits can include central auditory processing deficits.
Sujet(s)
Cortex auditif , Infections à VIH , Perception de la parole , Adulte , Audiométrie , Seuil auditif/physiologie , Femelle , Infections à VIH/complications , Humains , Mâle , Adulte d'âge moyen , Bruit , Perception de la parole/physiologieRÉSUMÉ
Heterogeneous environment adaptation is critical to understand the species evolution and response to climate change. However, how narrow-range species adapt to micro-geographic heterogeneity has been overlooked, and there is a lack of insights from metabolism and commensal microbiota. Here, we studied the environmental adaptation for 3 geographic populations (>40 km apart) of Diploderma vela, a lizard endemic to dry-hot valleys of the Hengduan Mountain Region. The climatic boundary caused a cooler, droughtier, and barren environment for northernmost population (RM) than the middle (QZK) and southernmost populations (FS). Correspondingly, significant divergences in liver and muscle metabolism and commensal microbiota were detected between RM and QZK or FS individuals, but not between QZK and FS individuals. Phospholipid composition, coenzyme level (i.e. pyridoxal and NAD+ ), and cholesterol metabolism (e.g. androgen and estriol synthesis) constituted the major metabolic difference between RM and QZK/FS groups. FS and QZK individuals kept abundant Proteobacteria and antifungal strains, while RM individuals maintained more Firmicutes and Bacteroidota. Strong associations existed between varied host metabolite and gut microbes. How were these interpopulation variations associated to the environment adaptation were discussed. These results provided some novel insights into the environmental adaptation and implicated the consequence of climate change on narrow-range species.
Sujet(s)
Lézards , Microbiote , Acclimatation , Adaptation physiologique , Animaux , SymbioseRÉSUMÉ
Recent studies have highlighted the underestimated diversity of the genus Diploderma Hallowell, 1861 in the Hengduan Mountain Region in Southwest China, but much of the region remains poorly surveyed for reptile diversity. In this study we describe two new species of Diploderma from the upper Jinsha and middle Yalong River Valley, based on evaluations of morphological, genetic, and distribution data. The two new species are morphologically most similar to D. angustelinea and D. vela, but they can be diagnosed from both recognized taxa and all remaining congeners by a suite of morphological features, particularly the distinct coloration of gular spots. Additionally, both new species either render other recognized species paraphyletic or are allopatric with respect to their morphologically similar congeners. Furthermore, we rediscover D. brevicaudum in the wild for the first time, which was known from historical museum specimens only. We estimate the phylogenetic position of D. brevicaudum within the genus Diploderma based on mitochondrial genealogy, and we provide an expanded diagnosis and comparisons against closely related congeners and provide a detailed description of coloration in life based on newly collected specimens. Our discoveries of the new Diploderma species further highlight the urgent conservation needs of the currently neglected hot-dry valley ecosystems in the Hengduan Mountain Region of China.
Sujet(s)
Écosystème , Lézards , Animaux , Chine , Phylogenèse , SerpentsRÉSUMÉ
PURPOSE: Neuroimaging elucidations have shown structural and functional brain alterations in HIV-infected (HIV+) individuals when compared to HIV-negative (HIV-) controls. However, HIV- groups used in previous studies were not specifically considered for sexual orientation, which also affects the brain structures and functions. The current study aimed to characterize the brain alterations associated with HIV infection while controlling for sexual orientation. METHODS: Forty-three HIV+ and 40 HIV- homosexual men (HoM) were recruited and underwent resting-state MRI scanning. Group differences in gray matter volume (GMV) were assessed using a voxel-based morphometry analysis. Brain regions with the altered GMV in the HIV+ HoM group were then taken as regions of interest in a seed-based analysis to identify altered functional connectivity. Furthermore, the amplitude of low-frequency fluctuation (ALFF) and regional homogeneity values were compared between the two groups to evaluate the HIV-associated functional abnormalities in local brain regions. RESULTS: HIV+ HoM showed significantly increased GMV in the bilateral parahippocampal gyrus and amygdala, and decreased GMV in the right inferior cerebellum, compared with the HIV- HoM. The brain regions with increased GMV were hyper-connected with the left superior cerebellum, right lingual gyrus, and left precuneus in the HIV+ HoM. Moreover, the ALFF values of the right fusiform gyrus, and left parahippocampal gyrus were increased in the HIV+ HoM. The regional homogeneity values of the right anterior cingulate and paracingulate gyri, and left superior cerebellum were decreased in the HIV+ HoM. CONCLUSION: When the study population was restricted to HoM, HIV+ individuals exhibited structural alterations in the limbic system and cerebellum, and functional abnormalities in the limbic, cerebellum, and visual network. These findings complement the existing knowledge on the HIV-associated neurocognitive impairment from the previous neuroimaging studies by controlling for the potential confounding factor, sexual orientation. Future studies on brain alternations with the exclusion of related factors like sexual orientation are needed to understand the impact of HIV infection on neurocognitive function more accurately.
RÉSUMÉ
The hypoxic microenvironment in solid tumors severely limits the efficacy of photodynamic therapy (PDT). Therefore, the development of nanocarriers co-loaded with photosensitizers and oxygen, together with imaging guidance ability, is of great significance in cancer therapy. However, previously reported synthetic methods for these multi-functional probes are complicated, and the raw materials used are toxic. Methods: Herein, the human endogenous protein, hemoglobin (Hb), was used for the simultaneous biomimetic synthesis of Gd-based nanostructures and co-loading of Chlorine e6 (Ce6) and oxygen for alleviating the hypoxic environment of tumors and accomplishing magnetic resonance imaging (MRI)-guided enhanced PDT. The Gd@HbCe6-PEG nanoprobes were synthesized via a green and protein biomimetic approach. The physicochemical properties, including relaxivity, oxygen-carrying/release capability, and PDT efficacy of Gd@HbCe6-PEG, were measured in vitro and in vivo on tumor-bearing mice after intravenous injection. Morphologic and functional MRI were carried out to evaluate the efficacy of PDT. Results: The results demonstrated the successful synthesis of compact Gd@HbCe6-PEG nanostructures with desired multi-functionalities. Following treatment with the nanoparticles, the embedded MR moiety was effective in lighting tumor lesions and guiding therapy. The oxygen-carrying capability of Hb after biomimetic synthesis was confirmed by spectroscopic analysis and oxygen detector in vitro. Further, tumor oxygenation for alleviating tumor hypoxia in vivo after intravenous injection of Gd@HbCe6-PEG was verified by photoacoustic imaging and immunofluorescence staining. The potent treatment efficacy of PDT on early-stage was observed by the morphologic and functional MR imaging. Importantly, rapid renal clearance of the particles was observed after treatment. Conclusion: In this study, by using a human endogenous protein, we demonstrated the biomimetic synthesis of multi-functional nanoprobes for simultaneous tumor oxygenation and imaging-guided enhanced PDT. The therapeutic efficacy could be quantitatively confirmed at 6 h post PDT with diffusion-weighted imaging (DWI).
Sujet(s)
Antinéoplasiques/administration et posologie , Nanoparticules métalliques/administration et posologie , Tumeurs/traitement médicamenteux , Photothérapie dynamique/méthodes , Nanomédecine théranostique/méthodes , Animaux , Antinéoplasiques/synthèse chimique , Antinéoplasiques/pharmacocinétique , Matériaux biomimétiques/administration et posologie , Matériaux biomimétiques/synthèse chimique , Matériaux biomimétiques/pharmacocinétique , Lignée cellulaire tumorale/transplantation , Chlorophyllides , Imagerie par résonance magnétique de diffusion , Modèles animaux de maladie humaine , Femelle , Gadolinium/administration et posologie , Gadolinium/composition chimique , Technologie de la chimie verte , Hémoglobines/administration et posologie , Hémoglobines/composition chimique , Humains , Injections veineuses , Nanoparticules métalliques/composition chimique , Souris , Sondes moléculaires/administration et posologie , Sondes moléculaires/synthèse chimique , Sondes moléculaires/pharmacocinétique , Tumeurs/imagerie diagnostique , Oxygène/administration et posologie , Oxygène/composition chimique , Techniques photoacoustiques , Porphyrines/administration et posologie , Porphyrines/composition chimique , Hypoxie tumorale/effets des médicaments et des substances chimiques , Microenvironnement tumoral/effets des médicaments et des substances chimiquesRÉSUMÉ
Asymptomatic patients and infected patients with normal chest CT imaging are considered carriers of SARS-CoV-2. Before a diagnosis of coronavirus disease 2019 (COVID-19) is made, these patients with negative chest CT findings may be ignored, causing the possibility of virus transmission. For patients with suspected infections, reliable epidemiological information and clinical symptoms, clinical management is necessary even when the chest CT is negative.
Sujet(s)
Infections à coronavirus/imagerie diagnostique , Pneumopathie virale/imagerie diagnostique , Tomodensitométrie , Adulte , Betacoronavirus/isolement et purification , COVID-19 , Infections à coronavirus/complications , Femelle , Fièvre/virologie , Humains , Pandémies , Pneumopathie virale/complications , Réaction de polymérisation en chaine en temps réel , SARS-CoV-2 , Facteurs tempsRÉSUMÉ
The objective of this study was to evaluate whether combination antiretroviral therapy (cART) has an effect on the clinical manifestations, radiological characteristics, and disease severity of human immunodeficiency virus (HIV)-associated Talaromyces marneffei infection. The clinical manifestations, chest computed tomography (CT) images, and disease severity were compared between 14 patients with culture-confirmed T. marneffei infections who received cART and 38 patients who did not receive cART. Clinical manifestations included high fever (>38°C), cough, shortness of breath, chills, and skin rash. Chest CT scans were evaluated for the presence of ground-glass opacities, consolidation, miliary nodules, nodules, masses, cavitation, pericardial effusion, pleural effusion, mediastinal lymphadenitis, and the distribution of parenchymal abnormalities. Disease severity was estimated by clinical manifestations and chest CT findings. Fever (>38°C), cough, shortness of breath, and chills were significantly less frequent in patients who received cART than in those who did not receive cART (P < 0.05). The frequencies of miliary nodules, mediastinal lymphadenitis, and the proportion of diffuse lesions were significantly lower in patients who received cART than in those who did not receive cART (P < 0.05). The disease severity was significantly decreased in patients who received cART compared with patients who did not receive cART (P < 0.001). T. marneffei-infected patients who received cART had fewer clinical manifestations and decreased disease severity compared with those who did not receive this treatment. The use of cART is associated with modified chest CT characteristics in HIV-associated T. marneffei infections.
Sujet(s)
Infections opportunistes liées au SIDA/traitement médicamenteux , Thérapie antirétrovirale hautement active/méthodes , Infections à VIH/traitement médicamenteux , Mycoses/complications , Talaromyces/effets des médicaments et des substances chimiques , Thorax/imagerie diagnostique , Infections opportunistes liées au SIDA/diagnostic , Adulte , Chine/épidémiologie , Toux/étiologie , Exanthème , Femelle , Fièvre/étiologie , Infections à VIH/complications , Infections à VIH/microbiologie , Humains , Mâle , Adulte d'âge moyen , Mycoses/épidémiologie , Mycoses/microbiologie , Radiographie thoracique , Indice de gravité de la maladie , Talaromyces/isolement et purification , TomodensitométrieRÉSUMÉ
The aim of our study was to evaluate the therapeutic effect of antiviral drugs on coronavirus disease 2019 (COVID-19) pneumonia. Patients confirmed with COVID-19 pneumonia were enrolled and divided into seven groups according to the treatment option. Information including age, sex, and duration from illness onset to admission, clinical manifestations, and laboratory data at admission, and length of hospital stay were evaluated. The chest computed tomography (CT) imaging obtained at admission and after a 5-day treatment cycle were assessed. The clinical symptoms and laboratory tests at discharge were also assessed. At admission, no significant differences were found among the groups, including the duration from illness onset to admission, clinical symptoms, and main laboratory results. No significant differences were found among the groups in terms of the proportion of patients with pneumonia resolution (P = .151) after treatment or the length of hospital stay (P = .116). At discharge, 7 of 184 (4%) patients had a mild cough while their other symptoms had disappeared, and the proportion of patients with abnormal liver function and with increased leukocytes, neutrophils or erythrocyte sedimentation rate among the 184 patients were close to those at admission. According to the results, the inclusion of antiviral drugs in therapeutic regimens based on symptomatic treatment had no significant additional impact on the improvement in COVID-19 patients. In addition, the results of chest CT imaging, clinical manifestations, and laboratory tests at discharge were not completely consistent.
Sujet(s)
Antiviraux/usage thérapeutique , Traitements médicamenteux de la COVID-19 , Pneumopathie virale/traitement médicamenteux , COVID-19/virologie , Chine , Femelle , Hospitalisation , Humains , Durée du séjour , Mâle , Adulte d'âge moyen , Pandémies , Pneumopathie virale/virologie , Études rétrospectives , SARS-CoV-2/effets des médicaments et des substances chimiquesRÉSUMÉ
Developing efficient non-precious-metal catalysts to accelerate the sluggish oxygen reduction reaction (ORR) is highly desired but remains a great challenge. Herein, using 2D bimetallic Zn/Fe-MOF as the precursor and g-C3N4 as the nitrogen source and stabilizer, porous carbon nanosheets doped with large amounts of single/paired Fe atoms (3.89 wtâ¯%) and N (10.28 wtâ¯%) are successfully prepared. It is found that the addition of g-C3N4 plays a key role in achieving a high loading of Fe single/paired atoms, and the 2D nanosheet structure gives the materials a high surface area and highly porous structure, resulting in outstanding ORR catalytic activity in both alkaline and acidic solutions. Our optimal sample achieved half-wave potentials in alkaline and acid media of up to 0.86 and 0.79 V (vs reversible hydrogen electrode (RHE)), respectively, values 20 mV higher than a commercial Pt/C catalyst in an alkaline medium and only 60 mV lower than Pt/C in an acidic medium. Moreover, its ORR durability was superior to that of commercial Pt/C in both electrolytes. We found that almost all the doped Fe in the sample existed as single or paired atoms coordinated with N. This work may provide an effective strategy for preparing high-performance catalysts bearing single/paired atoms by using MOFs as precursors.
RÉSUMÉ
Highly active catalyst for the hydrogen oxidation/evolution reactions (HOR and HER) plays an essential role for the water-to-hydrogen reversible conversion. Currently, increasing attention has been concentrated on developing low-cost, high-activity, and long-life catalytic materials, especially for acid media due to the promise of proton exchange membrane (PEM)-based electrolyzers and polymer electrolyte fuel cells. Although non-precious-metal phosphide (NPMP) catalysts have been widely researched, their electrocatalytic activity toward HER is still not satisfactory compared to that of Pt catalysts. Herein, a series of precious-metal phosphides (PMPs) supported on graphene (rGO), including IrP2-rGO, Rh2P-rGO, RuP-rGO, and Pd3P-rGO, are prepared by a simple, facile, eco-friendly, and scalable approach. As an example, the resultant IrP2-rGO displays better HER electrocatalytic performance and longer durability than the benchmark materials of commercial Pt/C under acidic, neutral, and basic electrolytes. To attain a current density of 10 mA cm-2, IrP2-rGO shows overpotentials of 8, 51, and 13 mV in 0.5 M dilute sulfuric acid, 1.0 M phosphate-buffered saline (PBS), and 1.0 M potassium hydroxide solutions, respectively. Additionally, IrP2-rGO also exhibits exceptional HOR performance in the 0.1 M HClO4 medium. Therefore, this work offers a vital addition to the development of a number of PMPs with excellent activity toward HOR and HER.
RÉSUMÉ
Arginine-glycine-aspartic acid (RGD) peptide sequences exist in a variety of biological extracellular matrices and can specifically bind the cell-surface integrin αvß3, which is overexpressed in cancer cells and plays important roles in tumor growth and invasion. Quantum dots (QDs) have been applied in the field of cell biology and can be physically conjugated to the surface of cancer cells for imaging. In this research, we developed QDs-RGD nanoparticles and investigated its application in pancreatic cancer cell imaging and its influence on the biological behavior of pancreatic cancer cells. The results of flow cytometric analysis showed that the αvß3 receptor was markedly overexpressed on pancreatic cancer cells. In cellular uptake studies, the fluorescence signal of QDs-RGD nanoparticles in pancreatic cancer cells was higher than that of QDs without RGD conjugation, as determined by an inverted fluorescence microscope. Furthermore, the biological behavior of pancreatic cancer cells was affected by QDs-RGD nanoparticles, which inhibited proliferation, migration and invasion and induced G2-phase cell cycle arrest. With integrin αvß3 as a target, QDs-RGD nanoparticles can generate high-quality images of pancreatic cancer cells and have immense potential for use in the targeted diagnosis and therapy of pancreatic cancer.
Sujet(s)
Tumeurs du pancréas , Boîtes quantiques , Humains , Intégrine alphaVbêta3 , Imagerie optique , Tumeurs du pancréas/imagerie diagnostique , PeptidesRÉSUMÉ
BACKGROUND: An efficient and accurate approach to quantify the steatosis extent of liver is important for clinical practice. For the purpose, we propose a specific designed ultrasound shear wave sequence to estimate ultrasonic and shear wave physical parameters. The utilization of the estimated quantitative parameters is then studied. RESULTS: Shear wave attenuation, shear wave absorption, elasticity, dispersion slope and echo attenuation were simultaneously estimated and quantified from the proposed novel shear wave sequence. Then, a regression tree model was utilized to learn the connection between the space represented by all the physical parameters and the liver fat proportion. MR mDIXON quantification was used as the ground truth for liver fat quantification. Our study included a total of 60 patients. Correlation coefficient (CC) with the ground truth were applied to mainly evaluate different methods for which the corresponding values were - 0.25, - 0.26, 0.028, 0.045, 0.46 and 0.83 for shear wave attenuation, shear wave absorption, elasticity, dispersion slope, echo attenuation and the learning-based model, respectively. The original parameters were extremely outperformed by the learning-based model for which the root mean square error for liver steatosis quantification is only 4.5% that is also state-of-the-art for ultrasound application in the related field. CONCLUSIONS: Although individual ultrasonic and shear wave parameters were not perfectly adequate for liver steatosis quantification, a promising result can be achieved by the proposed learning-based acoustic model based on them.
Sujet(s)
Acoustique , Stéatose hépatique/imagerie diagnostique , Apprentissage machine , Modèles biologiques , Résistance au cisaillement , Adulte , Sujet âgé , Stéatose hépatique/métabolisme , Femelle , Humains , Traitement d'image par ordinateur , Mâle , Adulte d'âge moyen , Fantômes en imagerie , Triglycéride/métabolisme , Échographie , Jeune adulteRÉSUMÉ
Efficient, low-cost catalysts are desirable for the sluggish oxygen reduction reaction (ORR). Herein, UIO-66-NH2 -derived multi-element (Fe, S, N) co-doped porous carbon catalyst is reported, Fe/N/S-PC, with an octahedral morphology, a well-defined mesoporous structure, and highly dispersed doping elements, synthesized by a double-solvent diffusion-pyrolysis method (DSDPM). The morphology of the UIO-66-NH2 precursor is perfectly inherited by the derived carbon material, resulting in a high surface area, a well-defined mesoporous structure, and atomic-level dispersion of the doping elements. Fe/N/S-PC demonstrates outstanding catalytic activity and durability for the ORR in both alkaline and acidic solutions. In 0.1 m KOH, its half-potential reaches 0.87 V (vs reversible hydrogen electrode (RHE)), 30 mV more positive than that of a 20 wt% Pt/C catalyst. In 0.1 m HClO4 , it reaches 0.785 V (vs RHE), only 65 mV less than that of Pt/C. The catalyst also exhibits excellent performance in acidic hydrogen/oxygen proton exchange membrane fuel cells. A membrane electrode assembly (MEA) with the catalyst as the cathode reaches 700 mA·cm-2 at 0.6 V and a maximum power density of 553 mW·cm-2 , ranking it among the best MEAs with a nonprecious metal catalyst as the cathode.