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1.
Front Nutr ; 9: 920791, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36337652

RESUMO

Background: Observational studies have suggested a potential non-linear association between sleep duration and hyperuricemia. However, the causal nature and sex-specific differences are poorly understood. We aimed to determine the shape of sex-specific causal associations between sleep duration and hyperuricemia in the UK Biobank. Methods: Logistic regression was used to investigate the observational association between self-reported sleep duration and hyperuricemia among 387,980 white British participants (mean age: 56.9 years and 46.0% males). Linear and non-linear Mendelian Randomization (MR) analyses were performed to assess the causal association between continuous sleep duration and hyperuricemia. The causal effects of genetically predicted short (<7 h) and long (>8 h) sleep durations on hyperuricemia were further estimated, respectively. Results: Traditional observational analysis suggested U- and J-shaped associations between sleep duration and hyperuricemia in females and males, respectively. Linear MR did not support the causal effect of sleep duration on hyperuricemia. Non-linear MR demonstrated an approximately U-shaped causal association between continuous sleep duration and hyperuricemia in overall participants and females, but not in males. Genetically predicted short sleep duration was significantly associated with hyperuricemia in females (OR [95% CI]: 1.21 [1.08-1.36]; P = 0.001), but not in males (1.08 [0.98-1.18]; P = 0.137). By contrast, genetically predicted long sleep duration was not significantly associated with the risk of hyperuricemia in either females or males. Conclusion: Genetically predicted short sleep duration is a potential causal risk factor for hyperuricemia for females but has little effect on males. Long sleep duration does not appear to be causally associated with hyperuricemia.

2.
J Am Chem Soc ; 144(45): 20931-20938, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36382467

RESUMO

A hybrid catalyst with integrated single-atom Ni and nanoscale Cu catalytic components is reported to enhance the C-C coupling and ethylene (C2H4) production efficiency in the electrocatalytic CO2 reduction reaction (eCO2RR). The single-atom Ni anchored on high-surface-area ordered mesoporous carbon enables high-rate and selective conversion of CO2 to CO in a wide potential range, which complements the subsequent CO enrichment on Cu nanowires (NWs) for the C-C coupling to C2H4. In situ surface-enhanced infrared absorption spectroscopy (SEIRAS) confirms the substantially improved CO enrichment on Cu, once the incorporation of single-atom Ni occurs. Also, in situ X-ray absorption near-edge structure (XANES) demonstrates the structural stability of the hybrid catalyst during eCO2RR. By modulating hybrid compositions, the optimized catalyst shows 66% Faradaic efficiency (FE) in an alkaline flow cell with over 100 mA·cm-2 at -0.5 V versus reversible hydrogen electrode, leading to a five-order enhancement in C2H4 selectivity compared with single-component Cu NWs.

3.
J Oral Pathol Med ; 2022 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-36273268

RESUMO

BACKGROUND: Accumulating evidence shows that high expression of casein kinase 2 (CK2) and phosphorylated acetyl CoA carboxylase (pACC) in patients with squamous cell carcinoma of the head and neck (SCCHN) correlates with decreased survival rates. Computational analysis has shown that ACC is a potential substrate for CK2, and its inhibition can suppress ACC phosphorylation in vitro. CX-4945, also known as silmitasertib, is an orally administered, highly specific, ATP-competitive inhibitor of CK2 and is under clinical investigation as a treatment for malignancies. We hypothesize that inhibition of CK2 by CX-4945 can reduce CK2-downstream phosphorylation of ACC as a therapeutic strategy against SCCHN. METHODS: Three aggressive SCCHN cell lines (OSC-19, FaDu and HN31) were cultured to investigate the anticancer mechanism of the CK2 inhibitor, CX-4945. Cell cycle analysis, Annexin V/PI staining, and cleavage of PARP were performed to detect apoptosis. Western blot, electron microscopy and analysis of acidic vesicular organelle development were used to detect autophagy. Interference with cellular metabolism by CX-4945 treatment was determined by Seahorse XF24 Extracellular Flux Analyzer and mass spectrometry. RESULTS: Cellular metabolism was impeded by CX-4945 in aggressive SCCHN cells by Seahorse XF24 Extracellular Flux Analyzer and mass spectrometry, and consequently time- and dose-dependent lipid droplet accumulation and non-apoptotic cell death were observed. The lipogenic enzyme ACC was demonstrated to be associated with CK2, and its repressive phosphorylation could be removed by the CK2 inhibitor CX-4945. Overexpression of ACC resulted in impaired cell survival following transient transfection. CONCLUSION: The findings demonstrate that CK2 inhibition impairs normal cellular energy metabolism and may be an attractive therapy for treating aggressive SCCHN.

4.
ACS Mater Au ; 2(5): 614-625, 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36124003

RESUMO

Achieving kinetic control to synthesize metastable compounds is a challenging task, especially in solid-state reactions where the diffusion is slow. Another challenge is the unambiguous crystal structure determination for metastable compounds when high-quality single crystals suitable for single-crystal X-ray diffraction are inaccessible. In this work, we report an unconventional means of synthesis and an effective strategy to solve the crystal structure of an unprecedented metastable compound LiNi12B8. This compound can only be produced upon heating a metastable layered boride, HT-Li0.4NiB (HT: high temperature), in a sealed niobium container. A conventional heating and annealing of elements do not yield the title compound, which is consistent with the metastable nature of LiNi12B8. The process to crystallize this compound is sensitive to the annealing temperature and dwelling time, a testament to the complex kinetics involved in the formation of the product. The unavailability of crystals suitable for single-crystal X-ray diffraction experiments prompted solving the crystal structure from high-resolution synchrotron powder X-ray diffraction data. This compound crystallizes in a new structure type with space group I4/mmm (a = 10.55673(9) Å, c = 10.00982(8) Å, V = 1115.54(3) Å3, Z = 6). The resulting complex crystal structure of LiNi12B8 is confirmed by scanning transmission electron microscopy and solid-state 11B and 7Li NMR spectroscopy analyses. The extended Ni framework with Li/Ni disorder in its crystal structure resulted in the spin-glass or cluster glass type magnetic ordering below 24 K. This report illustrates a "contemporary twist" to traditional methodologies toward synthesizing a metastable compound and provides a recipe for solving structures by combining the complementary characterization techniques in the cases where the traditionally used single-crystal X-ray diffraction method is nonapplicable.

5.
Anal Chem ; 94(27): 9793-9800, 2022 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-35772106

RESUMO

Fluorescence anisotropy has been widely used in developing biosensors and immunoassays, by virtue of the self-reference and environment-sensitive properties. However, fluorescence anisotropic chemical sensors on inorganic ions are limited by the total anisotropy change. To this end, we demonstrate here fluorescence anisotropic ion-selective optodes based on the homo-FRET (Förster resonance energy transfer) of the crowded chromoionophores. The conventional fluorescence on-off mode is transformed into the anisotropic mode. Variation of the target ion concentration changes the inter-chromoionophore distance in the organic sensing phase, leading to different extents of homo-FRET and steady-state anisotropy. A theoretical model is developed by coupling homo-FRET and anisotropy. Anisotropic detections of pH, K+, and Na+ are demonstrated as examples based on the different ionophores for H+, K+, and Na+, respectively. Further, fluorescence imaging of the nano-optodes, plasticized poly(vinyl chloride) sensing films, and live cells are demonstrated using a homemade fluorescence anisotropic imaging platform. The results form the basis of an ion-selective analytical method operating in the fluorescence anisotropic mode, which could potentially be applied to other fluorescence on-off probes based on homo-FRET.


Assuntos
Técnicas Biossensoriais , Transferência Ressonante de Energia de Fluorescência , Anisotropia , Técnicas Biossensoriais/métodos , Polarização de Fluorescência/métodos , Transferência Ressonante de Energia de Fluorescência/métodos , Íons
6.
Solid State Nucl Magn Reson ; 120: 101807, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35709566

RESUMO

Due to their high gyromagnetic ratio, there is considerable interest in measuring distances and correlations involving protons, but such measurements are compounded by the simultaneous recoupling of chemical shift anisotropy (CSA). This secondary recoupling adds additional modulations to the signal intensities that ultimately lead to t1-noise and signal decay. Recently, Venkatesh et al. demonstrated that the addition of CSA refocusing periods during 1H-X dipolar recoupling led to sequences with far higher stability and performance. Herein, we describe a related effort and develop a symmetry-based recoupling sequence that continually refocuses the 1H CSA. This sequence shows superior performance to the regular and t1-noise eliminated D-HMQC sequences in the case of spin-1/2 nuclei and comparable performance to the later for half-integer quadrupoles.


Assuntos
Prótons , Anisotropia
7.
J Phys Chem Lett ; 13(18): 4125-4132, 2022 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-35506614

RESUMO

Supported noble metals offer key advantages over homogeneous catalysts for in vivo applications of parahydrogen-based hyperpolarization. However, their performance is compromised by randomization of parahydrogen spin order resulting from rapid hydrogen adatom diffusion. The diffusion on Pt surfaces can be suppressed by introduction of Sn to form Pt-Sn intermetallic phases. Herein, an unprecedented pairwise selectivity of 19.7 ± 1.1% in the heterogeneous hydrogenation of propyne using silica encapsulated Pt-Sn intermetallic nanoparticles is reported. This high level of selectivity exceeds that of all supported metal catalysts by at least a factor of 3. Moreover, the pairwise selectivity for alkyne hydrogenation is about 2 times higher than for alkene hydrogenation, an observation attributed to the higher coverage of the former and its effect on diffusion. Lastly, PtSn@mSiO2 nanoparticles exhibited improved coking resistance, and any loss of activity is shown to be fully reversible through high-temperature oxidation-reduction cycling.


Assuntos
Nanopartículas , Platina , Hidrogenação , Espectroscopia de Ressonância Magnética , Dióxido de Silício , Estanho
8.
ACS Omega ; 7(14): 12158-12170, 2022 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-35449975

RESUMO

Widespread application of TiO2 for degradation of antibiotics is restricted by mainly the low photodegradation efficiency under solar irradiation. To expand the application of TiO2, the key factors that should be improved are visible-light response, yield of electrons and holes, and durability. Herein, we report a visible-light responsive and durable sugarcane-bagasse-derived biochar supported hydrogenated TiO2 (HSCB/H2-TiO2) photocatalyst with higher electron production fabricated by a facile one-pot hydrogenation. Mild hydrogenation temperature preserved the lotus-stem-like structure of sugarcane bagasse and gave the photocatalyst great separability. The superior durability of HSCB/H2-TiO2 was demonstrated by 12 rounds of repeated degradation of methylene blue (MB). In addition, the electron paramagnetic resonance (EPR) results demonstrated that the biochar skeleton contains abundant persistent free radicals (PFRs), which can provide excess electrons to form more •O2 -. Meanwhile, radical quenching experiment and EPR radical trapping results also revealed that •O2 - was the most dominant species for enrofloxacin (ENR) degradation. Thus, the as-fabricated photocatalyst shows excellent solar-driven degradation of ENR, and 95.6% of ENR was degraded in 180 min under simulated solar irradiation. Possible ENR degradation pathways and mechanism are also proposed based on the identified intermediates.

9.
J Chem Phys ; 156(12): 124112, 2022 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-35364862

RESUMO

Solid-state nuclear magnetic resonance can be enhanced using unpaired electron spins with a method known as dynamic nuclear polarization (DNP). Fundamentally, DNP involves ensembles of thousands of spins, a scale that is difficult to match computationally. This scale prevents us from gaining a complete understanding of the spin dynamics and applying simulations to design sample formulations. We recently developed an ab initio model capable of calculating DNP enhancements in systems of up to ∼1000 nuclei; however, this scale is insufficient to accurately simulate the dependence of DNP enhancements on radical concentration or magic angle spinning (MAS) frequency. We build on this work by using ab initio simulations to train a hybrid model that makes use of a rate matrix to treat nuclear spin diffusion. We show that this model can reproduce the MAS rate and concentration dependence of DNP enhancements and build-up time constants. We then apply it to predict the DNP enhancements in core-shell metal-organic-framework nanoparticles and reveal new insights into the composition of the particles' shells.

10.
Environ Technol ; : 1-14, 2022 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-35389823

RESUMO

In order to overcome the shortcomings in the traditional Fenton process, Fe(III)-EDDS-activated persulfate advanced oxidation process under irradiation is carried out as a promising technology. The photodegradation of sulfadiazine (SD) in Fe(III)-EDDS-activated persulfate system was investigated in this paper. The results showed that SD could be effectively degraded in Fe(III)-EDDS/S2O82-/hv system. The effects of Fe(III):EDDS molar ratio, the concentration of Fe(III)-EDDS, and the concentration of S2O82- on SD degradation were explored. At neutral pH, when Fe(III):EDDS = 1:1, Fe(III)-EDDS = 0.1 mM, S2O82- = 1.5 mM, the best SD degradation was achieved. The experiment of external influence factors showed that the degradation of SD could be obviously inhibited by the presence of CO32-, SO42-, whereas the degradation of SD was almost unaffected by the addition ofCl-. The degradation of SD could be slightly inhibited by the presence of humic acid and NO3-. The effect of pH on SD degradation was investigated, and SD could be degraded effectively in the pH range of 3-9. ESR proved that 1O2, ·OH, SO4-, and O2- were produced in the process. SO4- and ·OH were identified as the main radicals while O2·- also played non-ignorable role. Eleven intermediate products of SD were analysed. The C = N, S-N, and S-C bonds of SD were attacked by radicals firstly, leading to a series of reactions that eventually resulted in the destruction of SD molecules and the formation of small organic molecules.

11.
J Clin Ultrasound ; 50(7): 1004-1012, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35394661

RESUMO

Fetal mediastinal teratomas represent only 10% of congenital teratomas in children and 2.6% of all mediastinal masses in children. Teratomas have multifactorial etiology, such as chromosomal abnormalities. Fetal mediastinal teratomas are rare. Mediastinal teratomas can cause hydrops fetalis, fetal demise, and neonatal respiratory distress; therefore, accurate perinatal management and interventions are very important. We describe a case of fetal mediastinal teratoma wherein the cystic fluid in the fetal tumor was aspirated and confirmed by surgical pathology after birth at the authors' center. The teratoma in this case was characterized by a large single cystic mass with clear borders in the anterosuperior mediastinum, which grew rapidly and was closely related to the thymus. The infant was healthy at birth, and the tumor was surgically removed the age of 1 year. The postoperative course was uneventful, and the patient was in good health 6 years postoperatively. This case and literature review suggests that ultrasound examination can accurately diagnose fetal mediastinal teratomas, which is beneficial to provide an accurate basis for fetal prenatal intervention and treatment. Additionally, an important ultrasound feature of a fetal unicystic mediastinal teratoma is a saddle-shaped mass with clear boundaries, which provided an accurate reference for the diagnosis of a fetal cystic mediastinal teratoma by prenatal ultrasonography.


Assuntos
Neoplasias do Mediastino , Teratoma , Criança , Feminino , Humanos , Hidropisia Fetal/etiologia , Lactente , Recém-Nascido , Neoplasias do Mediastino/diagnóstico por imagem , Neoplasias do Mediastino/cirurgia , Mediastino , Gravidez , Teratoma/diagnóstico por imagem , Teratoma/cirurgia , Ultrassom , Ultrassonografia Pré-Natal
12.
Small ; 18(16): e2107799, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35229465

RESUMO

The electrochemical carbon dioxide reduction reaction (CO2 RR) is a transformative technology to reduce the carbon footprint of modern society. Single-site catalysts have been demonstrated as promising catalysts for CO2 RR, but general synthetic methods for catalysts with high surface area and tunable single-site metal composition still need to be developed to unambiguously investigate the structure-activity relationship crossing various metal sites. Here, a generalized coordination-condensation strategy is reported to prepare single-atom metal sites on ordered mesoporous carbon (OMC) with high surface areas (average 800 m2  g-1 ). This method is applicable to a broad range of metal sites (Fe, Co, Ni, Cu, Pt, Pd, Ru, and Rh) with loadings up to 4 wt.%. In particular, the CO2 RR to carbon monoxide (CO) Faradaic efficiency (FE) with Ni single-site OMC catalyst reaches 95%. This high FE is maintained even under large current density (>140 mA cm-2 ) and in a long-term study (14 h), which suits the urgently needed large-scale applications. Theoretical calculations suggest that the enhanced activity on single-atom Ni sites results from balanced binding energies between key intermediates, COOH and CO, for CO2 RR, as mediated by the coordination sphere.

13.
Small ; 18(14): e2105226, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35182021

RESUMO

Tailoring the structure of metal components and interaction with their anchored substrates is essential for improving the catalytic performance of supported metal catalysts; the ideal catalytic configuration, especially down to the range of atomic layers, clusters, and even single atoms, remains a subject under intensive study. Here, an Ir-on-MXene (Mo2 TiC2 Tx ) catalyst with controlled morphology changing from nanoparticles down to flattened atomic layers, and finally ultrathin layers and single atoms dispersed on MXene nanosheets at elevated temperature, is presented. The intermediate structure, consisting of mostly Ir atomic layers, shows the highest activity toward the hydrogen evolution reaction (HER) under industry-compatible alkaline conditions. In addition, the better HER activity of Ir atomic layers than that of single atoms suggests that the former serves as the main active sites. Detailed mechanism analysis reveals that the nanoparticle re-dispersion process and Ir atomic layers with a moderate interaction to the substrate associate with unconventional electron transfer from MXene to Ir, leading to suitable H* adsorption. The results indicate that the structural design is important for the development of highly efficient catalysts.


Assuntos
Irídio , Nanopartículas , Adsorção , Catálise , Hidrogênio
14.
J Am Chem Soc ; 144(12): 5323-5334, 2022 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-35195400

RESUMO

A catalytic architecture, comprising a mesoporous silica shell surrounding platinum nanoparticles (NPs) supported on a solid silica sphere (mSiO2/Pt-X/SiO2; X is the mean NP diameter), catalyzes hydrogenolysis of melt-phase polyethylene (PE) into a narrow C23-centered distribution of hydrocarbons in high yield using very low Pt loadings (∼10-5 g Pt/g PE). During catalysis, a polymer chain enters a pore and contacts a Pt NP where the C-C bond cleavage occurs and then the smaller fragment exits the pore. mSiO2/Pt/SiO2 resists sintering or leaching of Pt and provides high yields of liquids; however, many structural and chemical effects on catalysis are not yet resolved. Here, we report the effects of Pt NP size on activity and selectivity in PE hydrogenolysis. Time-dependent conversion and yields and a lumped kinetics model based on the competitive adsorption of long vs short chains reveal that the activity of catalytic material is highest with the smallest NPs, consistent with a structure-sensitive reaction. Remarkably, the three mSiO2/Pt-X/SiO2 catalysts give equivalent selectivity. We propose that mesoscale pores in the catalytic architecture template the C23-centered distribution, whereas the active Pt sites influence the carbon-carbon bond cleavage rate. This conclusion provides a framework for catalyst design by separating the C-C bond cleavage activity at catalytic sites from selectivity for chain lengths of the products influenced by the structure of the catalytic architecture. The increased activity, selectivity, efficiency, and lifetime obtained using this architecture highlight the benefits of localized and confined environments for isolated catalytic particles under condensed-phase reaction conditions.


Assuntos
Nanopartículas Metálicas , Platina , Carbono/química , Nanopartículas Metálicas/química , Platina/química , Polienos , Dióxido de Silício/química
15.
BMC Endocr Disord ; 22(1): 3, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34983464

RESUMO

OBJECTIVES: To assess whether recurrent gestational diabetes mellitus (GDM) and newly diagnosed GDM share similar risk factors. METHODS: The study recruited a cohort of 10,151 multipara women with singleton pregnancy who delivered between 2016 and 2019 in Beijing, China. The prevalence of recurrent GDM and associated risk factors were analyzed between women with and without prior GDM history. RESULTS: Eight hundred and seventy-five (8.6%) multipara women had a diagnosis of GDM during previous pregnancies. The prevalence of GDM and pre-gestational diabetes mellitus were 48.34% (423/875) and 7.89% (69/875) if the women were diagnosed with GDM during previous pregnancies, as compared to 16.00% (1484/9276) and 0.50% (46/9276) if the women were never diagnosed with GDM before. In women without a history of GDM, a variety of factors including older maternal age, higher pre-pregnancy body mass index (PPBMI), prolonged interval between the two pregnancies, higher early pregnancy weight gain, family history of type 2 diabetes mellitus (T2DM), maternal low birth weight, and higher early pregnancy glycemic and lipid indexes were generally associated with an increased risk of GDM at subsequent pregnancy. In women with a history of GDM, higher PPBMI, higher fasting glucose level and maternal birthweight ≥4000 g were independent risk factors for recurrent GDM. CONCLUSIONS: GDM reoccurred in nearly half of women with a history of GDM. Risk factors for recurrent GDM and newly diagnosed GDM were different. Identifying additional factors for GDM recurrence can help guide clinical management for future pregnancies to prevent GDM recurrence.


Assuntos
Diabetes Gestacional/epidemiologia , Paridade , Adulto , Pequim/epidemiologia , Estudos de Coortes , Feminino , Humanos , Gravidez , Recidiva , Fatores de Risco
16.
J Am Chem Soc ; 144(3): 1087-1093, 2022 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-35007081

RESUMO

Enantioselective [3 + 2] annulation of N-heteroarenes with alkynes has been developed via a cobalt-catalyzed dearomative umpolung strategy in the presence of chiral ligand and reducing reagent. A variety of electron-deficient N-heteroarenes, including quinolines, isoquinolines, quinoxaline, and pyridines, and internal or terminal alkynes are employed in this reaction, showing a broad substrate scope and good functionality tolerance. Annulation of electron-rich indoles with alkynes is also developed. This protocol provides a straightforward access to a variety of N-spiroheterocyclic molecules in excellent enantioselectivities (76 examples, up to 99% ee).

17.
Nanoscale ; 14(5): 1787-1795, 2022 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-35029611

RESUMO

Multicolor microbeads are widely used in flow cytometry for various cellular and immunoassays. However, they are limited by their large size of around one to tens of micrometers. Nanomaterials for multiplexed analysis are emerging as valuable tools in high-throughput assays and fluorescence cell barcoding. We present barcoding and related cellular studies based on mass-produced organosilane-derived multifunctional nanospheres with a uniform size. Functional groups including thiols, amines, and azides were integrated in one step from various organosilanes without additional orthosilicates. Fluorescent nanobarcodes (NBs) were achieved through flexible physical adsorption and chemical ligation of spectrally separated fluorescent dyes. Live cells labeled with the NBs were readily distinguished by flow cytometry. The NBs have a small and uniform size (ca. 27 nm in diameter), excellent biocompatibility, rapid cellular uptake, and low dye leakage. The fluorescent nanospheres were applied for long-term cell tracking during multiple rounds of cell division and monitored over 48 hours. While most nanospheres were endolysosome-targeting, modification with fluorescein isothiocyanate (FITC) surprisingly lighted up the cell nucleus. This work lays the foundation of a unique family of functional nanomaterials promising for multiplex detection and other chemical and biological applications.


Assuntos
Nanosferas , Nanoestruturas , Citometria de Fluxo , Fluoresceína , Corantes Fluorescentes
18.
Sci Adv ; 8(4): eabl9478, 2022 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-35089786

RESUMO

Catalytic dehydrogenation enables reversible hydrogen storage in liquid organics as a critical technology to achieve carbon neutrality. However, oxidant or base-free catalytic dehydrogenation at mild temperatures remains a challenge. Here, we demonstrate a metal-free carbocatalyst, nitrogen-assembly carbons (NCs), for acceptorless dehydrogenation of N-heterocycles even at ambient temperature, showing greater activity than transition metal-based catalysts. Mechanistic studies indicate that the observed catalytic activity of NCs is because of the unique closely placed graphitic nitrogens (CGNs), formed by the assembly of precursors during the carbonization process. The CGN site catalyzes the activation of C─H bonds in N-heterocycles to form labile C─H bonds on catalyst surface. The subsequent facile recombination of this surface hydrogen to desorb H2 allows the NCs to work without any H-acceptor. With reverse transfer hydrogenation of various N-heterocycles demonstrated in this work, these NC catalysts, without precious metals, exhibit great potential for completing the cycle of hydrogen storage.

19.
Nanotechnology ; 33(16)2022 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-34963107

RESUMO

Bulk heterojunction is one key concept leading to breakthrough in organic photovoltaics. The active layer is expectantly formed of distinct morphologies that carry out their respective roles in photovoltaic performance. The morphology-performance relationship however remains stymied, because unequivocal morphology at the nanoscale is not available. We used scattering-type scanning near-field optical microscopy operating with a visible light source (visibles-SNOM) to disclose the nanomorphology of P3HT:PCBM and pBCN:PCBM blends. Donor and acceptor domain as well as intermixed phase were identified and their intertwined distributions were mapped. We proposed energy landscapes of the BHJ active layer to shed light on the roles played by these morphologies in charge separation, transport and recombination. This study shows that visibles-SNOM is capable of profiling the morphological backdrop pertaining to the operation of high performance organic solar cells.

20.
Environ Technol ; : 1-13, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34913858

RESUMO

It has proved that the photo-Fenton system modified by polycarboxylic acid is effective against the degradation of organic pollutants. Still, its effect and impact on actual water bodies are not clear. Therefore, this study mainly discussed the effect of actual water elements on the degradation of 2,4-Dichlorophenol in photo-Fenton system modified by Nitrilotriacetic acid (NTA) and its mechanism in pure water. The specific research contents were: the effect of initial concentration of 2,4-Dichlorophenol on its degradation efficiency; the effect of organic matters on the degradation of 2,4-Dichlorophenol; the effect of cations and anions; the effect of different actual water bodies. And the main results were as follows: In the effect of initial concentration, when the concentration of 2,4-Dichlorophenol was 20 mg·L-1, the degradation efficiency was the best (reached 100%). But, with the increase of initial concentration, the degradation efficiency of the system became worse and worse; the coexistence of the same kind of organic compounds can inhibit each other's degradation, and the degradation rate of pollutants in the mixed system was slower than that in the single system; the addition of anions and cations inhibited the degradation of 2,4-Dichlorophenol, and the degradation efficiency varied with the concentration of ions, in which the effect of anions was more complex; the degradation efficiency of 2,4-Dichlorophenol in three kinds of actual water bodies was lower than in deionized water, especially in PPMW. However, the degradation rates of DSTP and NLW were the fastest in the first 20 min.

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