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1.
J Am Chem Soc ; 146(20): 13974-13982, 2024 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-38723620

RESUMEN

It has been reported that it was selective to produce ammonia on metallic cobalt in the electrocatalytic nitric oxide reduction reaction (eNORR), where hexagonal close-packed (hcp) cobalt outperforms face-centered cubic (fcc) cobalt. However, hydroxylamine is more selectively produced on a cobalt single-atom catalyst (Co-SAC). Herein, we uncover the structural sensitivity over hcp-Co, fcc-Co, and Co-SAC in eNORR by employing a recently developed constant potential simulation method and microkinetic modeling. It was found that the superior activity for ammonia production on hcp-Co can be attributed to its facile electron and proton transfer and a stronger lateral suppression effect from NO* over fcc-Co. The exceptional hydroxylamine selectivity on Co-SAC is due to the modified electronic structure, namely, a positively charged active center. It was found that it is more favorable to produce NOH* over hcp-Co and fcc-Co, while HNO* is more preferable on Co-SAC, which are firmly correlated with the vertical and strong NO adsorption on the former and the moderate adsorption on the latter. In other words, a key factor for selectivity control is the first step of NO* protonation. Therefore, the local structure and electronic structure of the catalysts can be critical in regulating the activity and selectivity in eNORR.

2.
Angew Chem Int Ed Engl ; 63(3): e202316903, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-37997556

RESUMEN

Proton exchange membrane water electrolysis is a highly promising hydrogen production technique for sustainable energy supply, however, achieving a highly active and durable catalyst for acidic water oxidation still remains a formidable challenge. Herein, we propose a local microenvironment regulation strategy for precisely tuning In-RuO2 /graphene (In-RuO2 /G) catalyst with intrinsic electrochemical activity and stability to boost acidic water oxidation. The In-RuO2 /G displays robust acid oxygen evolution reaction performance with a mass activity of 671 A gcat -1 at 1.5 V, an overpotential of 187 mV at 10 mA cm-2 , and long-lasting stability of 350 h at 100 mA cm-2 , which arises from the asymmetric Ru-O-In local structure interactions. Further, it is unraveled theoretically that the asymmetric Ru-O-In structure breaks the thermodynamic activity limit of the traditional adsorption evolution mechanism which significantly weakens the formation energy barrier of OOH*, thus inducing a new rate-determining step of OH* absorption. Therefore, this strategy showcases the immense potential for constructing high-performance acidic catalysts for water electrolyzers.

3.
Angew Chem Int Ed Engl ; 63(46): e202411542, 2024 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-39132837

RESUMEN

Electrooxidation of biomass-derived glycerol which is regarded as a main byproduct of industrial biodiesel production, is an innovative strategy to produce value-added chemicals, but currently showcases slow kinetics, limited Faraday efficiency, and unclear catalytic mechanism. Herein, we report high-efficiency electrooxidation of glycerol into formate via a Cu doped NiCo alloy catalyst supported on nickel foam (Cu-NiCo/NF) in a coupled system paired with nitrate reduction. The designed Cu-NiCo/NF delivers only 1.23 V vs. RHE at 10 mA cm-2, and a record Faraday efficiency of formate of 93.8 %. The superior performance is ascribed to the rapid generation of NiIII-OOH and CoIII-OOH species and favorable coupling of surface *O with reactive intermediates. Using Cu-NiCo/NF as a bifunctional catalyst, the coupled system synchronously produces NH3 and formate, showing 290 mV lower than the coupling of hydrogen evolution reaction, together with excellent long-term stability for up to 144 h. This work lays out new guidelines and reliable strategies from catalyst design to system coupling for biomass-derived electrochemical refinery.

4.
Environ Sci Technol ; 57(51): 21888-21897, 2023 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-38081063

RESUMEN

In contrast to numerous studies on oxygen species, the interaction of volatile organic compounds (VOCs) with oxides is also critical to the catalytic reaction but has hardly been considered. Herein, we develop a highly efficient Pt atom doped spinel CoMn2O4 (Pt-CoMn) for oxidation of toluene at low temperature, and the toluene conversion rate increased by 18.3 times (129.7 versus 7.1 × 10-11 mol/(m2·s)) at 160 °C compared to that of CoMn2O4. Detailed characterizations and density functional theory calculations reveal that the local electron environment of the Co sites is changed after Pt doping, and the formed electron-deficient Co sites in turn strengthen the interaction with toluene. Adsorbed toluene will react with lattice oxygen in Pt-CoMn and CoMn catalysts and convert into benzoate intermediates, and the consumption rate of benzoate is closely related to the activation of gaseous oxygen. Significantly, the abundant bulk defects of Pt-CoMn help to open the reaction channel in the CoMn spinel, which acts as an oxygen pump to promote the transformation of bulk lattice oxygen into surface lattice oxygen at lower temperatures, thus accelerating the conversion rate of benzoate intermediates into CO2 and enhancing low-temperature combustion of toluene. Pt-CoMn developed here emphasizes the regulation of VOCs adsorption strength and lattice oxygen transformation processes on CoMn2O4 by adjusting the local electron environment, which will provide new guidance for the design of efficient oxide catalysts for catalytic oxidation.


Asunto(s)
Electrones , Oxígeno , Adsorción , Óxidos , Tolueno , Benzoatos , Catálisis
5.
Bioorg Chem ; 140: 106762, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37572533

RESUMEN

EZH2 is a member of PcG and can induce the occurrence of cancer when it is highly expressed. As an EZH2 inhibitor, Tazemetostat (EPZ6438) can inhibit the methylation catalytic activity of EZH2. However, many studies have shown that inhibition of EZH2 alone does not efficiently block tumor development. Therefore, in this study, proteolytic targeting chimera technology was employed to enhance the antiproliferative potency of EPZ6438 by degrading the oncogenic activity of EZH2. Several PROTACs have been synthesized by combining EPZ6438 with four E3 ligase ligands based on VHL, CRBN, MDM2, and cIAP E3 ligase systems. In our study, compound E-3P-MDM2 is the most active PROTAC molecule. It degraded EZH2 of the SU-DHL-6 cells in a concentration and dose-dependent manner and also degraded both EED and SUZ12 protein without affecting their mRNA levels, then significantly inhibited the expression of H3K27me3. The in vitro antiproliferative activity of E-3P-MDM2 was much stronger than that of EPZ6438.


Asunto(s)
Linfoma , Neoplasias , Humanos , Quimera Dirigida a la Proteólisis , Linfoma/metabolismo , Neoplasias/metabolismo , Núcleo Celular/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Proteolisis , Proteína Potenciadora del Homólogo Zeste 2/metabolismo
6.
Angew Chem Int Ed Engl ; 62(43): e202310973, 2023 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-37667678

RESUMEN

Full understanding to the origin of the catalytic performance of a supported nanocatalyst from the points of view of both the active component and support is significant for the achievement of high performance. Herein, based on a model electrocatalyst of single-iridium-atom-doped iron (Fe)-based layered double hydroxides (LDH) for oxygen evolution reaction (OER), we reveal the first completed origin of the catalytic performance of such supported nanocatalysts. Specially, besides the activity enhancement of Ir sites by LDH support, the stability of surface Fe sites is enhanced by doped Ir sites: DFT calculation shows that the Ir sites can reduce the activity and enhance the stability of the nearby Fe sites; while further finite element simulations indicate, the stability enhancement of distant Fe sites could be attributed to the much low concentration of OER reactant (hydroxyl ions, OH- ) around them induced by the much fast consumption of OH- on highly active Ir sites. These new findings about the interaction between the main active components and supports are applicable in principle to other heterogeneous nanocatalysts and provide a completed understanding to the catalytic performance of heterogeneous nanocatalysts.

7.
Angew Chem Int Ed Engl ; 62(25): e202217701, 2023 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-37071488

RESUMEN

The oxide-zeolite (OXZEO) catalyst design concept has been demonstrated in an increasing number of studies as an alternative avenue for direct syngas conversion to light olefins. We report that face-centered cubic (FCC) MnGaOx -Spinel gives 40 % CO conversion, 81 % light olefins selectivity, and a 0.17 g gcat -1 h-1 space-time yield of light olefins in combination with SAPO-18. In comparison, solid solution MnGaOx (characterized by Mn-doped hexagonal close-packed (HCP) Ga2 O3 ) with a similar chemical composition gives a much inferior activity, i.e., the specific surface activity is one order of magnitude lower than the spinel oxide. Photoluminescence (PL), in situ Fourier-transform infrared (FT-IR), and density functional theory (DFT) calculations indicate that the superior activity of MnGaOx -Spinel can be attributed to its higher reducibility (higher concentration of oxygen vacancies) and the presence of coordinatively unsaturated Ga3+ sites, which facilitates the dissociation of the C-O bond via a more efficient ketene-acetate pathway to light olefins.


Asunto(s)
Alquenos , Óxido de Aluminio , Espectroscopía Infrarroja por Transformada de Fourier , Óxidos
8.
J Am Chem Soc ; 144(27): 12127-12137, 2022 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-35762495

RESUMEN

Embedding metal species into zeolite frameworks can create framework-bond metal sites in a confined microenvironment. The metals sitting in the specific T sites of zeolites and their crystalline surroundings are both committed to the interaction with the reactant, participation in the activation, and transient state achievement during the whole catalytic process. Herein, we construct isolated Co-motifs into purely siliceous MFI zeolite frameworks (Co-MFI) and reveal the location and microenvironment of the isolated Co active center in the MFI zeolite framework particularly beneficial for propane dehydrogenation (PDH). The isolated Co-motif with the distorted tetrahedral structure ({(≡SiO)2Co(HO-Si≡)2}, two Co-O-Si bonds, and two pseudobridging hydroxyls (Co···OH-Si) is located at T1(7) and T3(9) sites of the MFI zeolite. DFT calculations and deuterium-labeling reactions verify that the isolated Co-motif together with the MFI microenvironment collectively promotes the PDH reaction by providing an exclusive microenvironment to preactivate C3H8, polarizing the oxygen in Co-O-Si bonds to accept H* ({(≡SiO)CoHδ- (Hδ+O-Si≡)3}), and a scaffold structure to stabilize the C3H7* intermediate. The Co-motif active center in Co-MFI goes through the dynamic evolutions and restoration in electronic states and coordination states in a continuous and repetitive way, which meets the requirements from the series of elementary steps in the PDH catalytic cycle and fulfills the successful catalysis like enzyme catalysis.

9.
Strahlenther Onkol ; 198(10): 949-957, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-35635557

RESUMEN

BACKGROUND: There is sparse research reporting effective interventions for preventing nausea and emesis caused by concurrent chemoradiotherapy (CCRT) in locally advanced head and neck squamous cell carcinoma (LA-HNSCC). METHODS: Treatment-naïve LA-HNSCC patients received intensity-modulated radiotherapy with concomitant cisplatin 100 mg/m2 (33 mg/m2/days [d]1-3) every 3 weeks for two cycles. All patients were given oral aprepitant 125 mg once on d1, then 80 mg once on d2-5; ondansetron 8 mg once on d1; and dexamethasone 12 mg once on d1, then 8 mg on d2-5. The primary endpoint was complete response (CR). Pursuant to δ = 0.2 and α = 0.05, the expected CR rate was 80%. RESULTS: A total of 43 patients with LA-HNSCC were enrolled. The median age was 53 years, and 86.0% were male. All patients received radiotherapy and 86.0% of patients completed both cycles as planned. The overall CR rate was 86.0% (95% confidence interval [CI]: 72.1-94.7). The CR rates for cycles 1 and 2 were 88.4% (95% CI: 74.9-96.1) and 89.2% (95% CI: 74.6-97.0). The complete protection rate in the overall phase was 72.1% (95% CI: 56.3-84.7). The emesis-free and nausea-free responses in the overall phase were 88.4% (95% CI: 74.9-96.1) and 60.5% (95% CI: 44.4-75.0), respectively. The adverse events related to antiemetics were constipation (65.1%) and hiccups (16.3%), but both were grade 1-2. There was no grade 4 or 5 treatment-related toxicity with antiemetic usage. CONCLUSION: The addition of aprepitant into ondansetron and dexamethasone provided effective protection from nausea and emesis in patients with LA-HNSCC receiving radiotherapy and concomitant high-dose cisplatin chemotherapy.


Asunto(s)
Antieméticos , Neoplasias de Cabeza y Cuello , Carcinoma de Células Escamosas de Cabeza y Cuello , Antieméticos/efectos adversos , Aprepitant/efectos adversos , Quimioradioterapia/efectos adversos , Cisplatino/efectos adversos , Dexametasona/efectos adversos , Quimioterapia Combinada/efectos adversos , Femenino , Neoplasias de Cabeza y Cuello/terapia , Humanos , Masculino , Persona de Mediana Edad , Náusea/inducido químicamente , Náusea/prevención & control , Ondansetrón/efectos adversos , Estudios Prospectivos , Carcinoma de Células Escamosas de Cabeza y Cuello/terapia , Vómitos/inducido químicamente , Vómitos/prevención & control
10.
BMC Cancer ; 22(1): 1235, 2022 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-36447152

RESUMEN

PURPOSE: Concurrent chemoradiotherapy (CCRT) is a standard treatment choice for locally advanced hypopharyngeal carcinoma. The aim of this study was to investigate whether induction chemotherapy (IC) followed by CCRT is superior to CCRT alone to treat locally advanced hypopharyngeal carcinoma. METHODS AND MATERIALS: Patients (n = 142) were randomized to receive two cycles of paclitaxel/cisplatin/5-fluorouracil (TPF) IC followed by CCRT or CCRT alone. The primary end point was overall survival (OS). The secondary end points included the larynx-preservation rate, progression-free survival (PFS), distant metastasis-free survival (DMFS), and toxicities. RESULTS: Ultimately, 113 of the 142 patients were analyzed. With a median follow-up of 45.6 months (interquartile range 26.8-57.8 months), the 3-year OS was 53.1% in the IC + CCRT group compared with 54.8% in the CCRT group (hazard ratio, 1.004; 95% confidence interval, 0.573-1.761; P = 0.988). There were no statistically significant differences in PFS, DMFS, and the larynx-preservation rate between the two groups. The incidence of grade 3-4 hematological toxicity was much higher in the IC+ CCRT group than in the CCRT group (54.7% vs. 10%, P < 0.001). CONCLUSIONS: Adding induction TPF to CCRT did not improve survival and the larynx-preservation rate in locally advanced hypopharyngeal cancer, but caused a higher incidence of acute hematological toxicities. TRIAL REGISTRATION: ClinicalTrials.gov , number NCT03558035. Date of first registration, 15/06/2018.


Asunto(s)
Quimioradioterapia , Neoplasias Hipofaríngeas , Quimioterapia de Inducción , Humanos , Quimioradioterapia/efectos adversos , Quimioradioterapia/métodos , Neoplasias Hipofaríngeas/terapia , Quimioterapia de Inducción/efectos adversos , Quimioterapia de Inducción/métodos , Laringe , Supervivencia sin Progresión
11.
Clin Oral Investig ; 26(1): 513-521, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34145479

RESUMEN

OBJECTIVES: Residual pockets are a risk factor of periodontitis progression. This study evaluated the efficacy of periodontal endoscopy (PE) during scaling and root planning (SRP) of residual pockets in chronic periodontitis patients after initial periodontal treatment. MATERIALS AND METHODS: A single-blinded, randomized controlled clinical trial was conducted in systemically healthy subjects presenting at least three residual pockets with a probing depth (PD) ≥ 5 mm in each quadrant. Subjects were randomly allocated to one of two trial groups using a computer-generated program: SRP + PE (test group) or SRP alone (control group). Clinical parameters (PD, clinical attachment level (CAL), bleeding on probing (BOP), and plaque index (PLI)) were then measured at baseline, 3-, and 6-month follow-up. RESULTS: A total of 1629 sites in 37 patients were examined. Both treatments significantly improved all clinical outcomes (PD, CAL, BOP, and PLI) from baseline to 6 months (P < 0.05), although greater reductions in PD and PLI were observed in the test group at both 3- (PD: 3.45 ± 0.56 vs. 4.14 ± 0.59 mm; PLI: 0.55 ± 0.23 vs. 0.73 ± 0.27) and 6-month follow-up (PD: 3.12 ± 0.63 vs. 4.0 ± 0.68 mm; PLI: 0.49 ± 0.21 vs. 0.72 ± 0.28, respectively; P = 0.001 for PD and P = 0.021 for PLI). No significant differences in CAL or BOP were observed. CONCLUSIONS: SRP + PE resulted in significant reductions in PD and PLI compared to SRP alone in residual pockets with a PD ≥ 5 mm. CLINICAL RELEVANCE: The findings highlight the benefits of SRP + PE, supporting use as an alternative strategy in nonsurgical periodontal treatment.


Asunto(s)
Periodontitis Crónica , Periodontitis Crónica/terapia , Índice de Placa Dental , Raspado Dental , Endoscopía , Estudios de Seguimiento , Humanos , Aplanamiento de la Raíz
12.
J Am Chem Soc ; 143(31): 12038-12052, 2021 08 11.
Artículo en Inglés | MEDLINE | ID: mdl-34319735

RESUMEN

The industrially important methanol-to-hydrocarbons (MTH) reaction is driven and sustained by autocatalysis in a dynamic and complex manner. Hitherto, the entire molecular routes and chemical nature of the autocatalytic network have not been well understood. Herein, with a multitechnique approach and multiscale analysis, we have obtained a full theoretical picture of the domino cascade of autocatalytic reaction network taking place on HZSM-5 zeolite. The autocatalytic reaction is demonstrated to be plausibly initiated by reacting dimethyl ether (DME) with the surface methoxy species (SMS) to generate the initial olefins, as evidenced by combining the kinetic analysis, in situ DRIFT spectroscopy, 2D 13C-13C MAS NMR, electronic states, and projected density of state (PDOS) analysis. This process is operando tracked and visualized at the picosecond time scale by advanced ab initio molecular dynamics (AIMD) simulations. The initial olefins ignite autocatalysis by building the first autocatalytic cycle-olefins-based cycle-followed by the speciation of methylcyclopentenyl (MCP) and aromatic cyclic active species. In doing so, the active sites accomplish the dynamic evolution from proton acid sites to supramolecular active centers that are experimentally identified with an ever-evolving and fluid feature. The olefins-guided and cyclic-species-guided catalytic cycles are interdependently linked to forge a previously unidentified hypercycle, being composed of one "selfish" autocatalytic cycle (i.e., olefins-based cycle with lighter olefins as autocatalysts for catalyzing the formation of olefins) and three cross-catalysis cycles (with olefinic, MCP, and aromatic species as autocatalysts for catalyzing each other's formation). The unraveled dynamic autocatalytic cycles/network would facilitate the catalyst design and process control for MTH technology.

13.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 38(12): 1180-1184, 2021 Dec 10.
Artículo en Zh | MEDLINE | ID: mdl-34839502

RESUMEN

OBJECTIVE: Patients with 22q11.2 microduplications have highly variable clinical phenotypes. The clinical manifestations and prognosis of 19 fetuses carrying 22q11.2 microduplications were analyzed. METHODS: The fetuses were analyzed by single nucleotide polymorphism array (SNP array), which was followed by parental validation. Pregnancy outcome and clinical features of the newborns were analyzed in order to delineate genotype-phenotype correlation. RESULTS: Two fetuses were identified by karyotyping analysis of amniotic fluid samples. SNP array revealed that all have carried a 468.8 kb~3.4 Mb duplication in 22q11.2 region. Two couples have refused parental verification. Seven cases were inherited from the mother, 6 were from the father, and 4 cases were de novo in origin. Three couples opted termination of the pregnancy. One fetus perished at birth. Five newborns showed delayed growth, the remaining 10 were normal. CONCLUSION: The prenatal phenotype of fetuses carrying 22q11.2 microduplications are nonspecific, and the phenotypes of survivors may become more diverse along with increased age. Professional evaluation and long-term follow-up should be recommended.


Asunto(s)
Asesoramiento Genético , Diagnóstico Prenatal , Femenino , Feto , Humanos , Recién Nacido , Cariotipificación , Fenotipo , Embarazo
14.
J Am Chem Soc ; 142(38): 16429-16436, 2020 09 23.
Artículo en Inglés | MEDLINE | ID: mdl-32862644

RESUMEN

Nonoxidative dehydrogenation is promising for production of light olefins from shale gas, but current technology relies on precious Pt or toxic Cr catalysts and suffers from thermodynamically oriented coke formation. To solve these issues, the earth-abundant iron catalyst is employed, where Fe species are effectively modulated by siliceous zeolite, which is realized by the synthesis of Fe-containing MFI siliceous zeolite in the presence of ethylenediaminetetraacetic sodium (FeS-1-EDTA). Catalytic tests in ethane dehydrogenation show that this catalyst has a superior coke resistance in a 200 h run without any deactivation with extremely high activity and selectivity (e.g., 26.3% conversion and over 97.5% selectivity to ethene in at 873 K, close to the thermodynamic equilibrium limitation). Multiple characterizations demonstrate that the catalyst has uniformly and stably isolated Fe sites, which improves ethane dehydrogenation to facilitate the fast desorption of hydrogen and olefin products in the zeolite micropores and hinders the coke formation, as also identified by density functional calculations.

15.
J Am Chem Soc ; 142(40): 17167-17174, 2020 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-32924478

RESUMEN

Encapsulation of metal nanocatalysts by support-derived materials is well known as a classical strong metal-support interaction (SMSI) effect that occurs almost exclusively with active oxide supports and often blocks metal-catalyzed surface reactions. In the present work this classical SMSI process has been surprisingly observed between metal nanoparticles, e.g., Ni, Fe, Co, and Ru, and inert hexagonal boron nitride (h-BN) nanosheets. We find that weak oxidizing gases such as CO2 and H2O induce the encapsulation of nickel (Ni) nanoparticles by ultrathin boron oxide (BOx) overlayers derived from the h-BN support (Ni@BOx/h-BN) during the dry reforming of methane (DRM) reaction. In-situ surface characterization and theory calculations reveal that surface B-O and B-OH sites in the formed BOx encapsulation overlayers work synergistically with surface Ni sites to promote the DRM process rather than blocking the surface reactions.

16.
Phys Chem Chem Phys ; 22(9): 5293-5300, 2020 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-32096531

RESUMEN

Transition metals and zeolites are extremely different catalysts used for methanol conversion. Zeolites are able to catalyze methanol conversion to hydrocarbons like gasoline and olefins, while transition metals show the selectivity of syngas. It is quite important to establish a general description from a catalysis point of view for a variety of catalysts. In this work, we have employed density functional theory calculations to correlate adsorption energies for all intermediates over a set of transition metals and zeolites. We have successfully unveiled the difference in chemical reactivity and catalytic activity for zeolites and transition metals; a comparative description has been finally established between the acidity (and porous effects) of zeolites and electronic (and geometrical) effects over transition metals. The hydrogen adsorption strength was suggested to be a general descriptor for both transition metal and zeolite catalysts. In addition, it was found that some zeolites with the same ammonia adsorption strength, which was always used to describe the acidity in experimental studies, are likely to have different theoretical acidity (hydrogen bonding strength). This eventually opens one more dimension for rational selection and design of zeolites for catalysis application.

17.
Proc Natl Acad Sci U S A ; 114(23): 5930-5934, 2017 06 06.
Artículo en Inglés | MEDLINE | ID: mdl-28533413

RESUMEN

Confined microenvironments formed in heterogeneous catalysts have recently been recognized as equally important as catalytically active sites. Understanding the fundamentals of confined catalysis has become an important topic in heterogeneous catalysis. Well-defined 2D space between a catalyst surface and a 2D material overlayer provides an ideal microenvironment to explore the confined catalysis experimentally and theoretically. Using density functional theory calculations, we reveal that adsorption of atoms and molecules on a Pt(111) surface always has been weakened under monolayer graphene, which is attributed to the geometric constraint and confinement field in the 2D space between the graphene overlayer and the Pt(111) surface. A similar result has been found on Pt(110) and Pt(100) surfaces covered with graphene. The microenvironment created by coating a catalyst surface with 2D material overlayer can be used to modulate surface reactivity, which has been illustrated by optimizing oxygen reduction reaction activity on Pt(111) covered by various 2D materials. We demonstrate a concept of confined catalysis under 2D cover based on a weak van der Waals interaction between 2D material overlayers and underlying catalyst surfaces.

18.
Angew Chem Int Ed Engl ; 59(24): 9711-9718, 2020 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-32189423

RESUMEN

NO removal from exhausted gas is necessary owing to its damage to environment. Meanwhile, the electrochemical ammonia synthesis (EAS) from N2 suffers from low reaction rate and Faradaic efficiency (FE). Now, an alternative route for ammonia synthesis is proposed from exhaust NO via electrocatalysis. DFT calculations indicate electrochemical NO reduction (NORR) is more active than N2 reduction (NRR). Via a descriptor-based approach, Cu was screened out to be the most active transition metal catalyst for NORR to NH3 owing to its moderate reactivity. Kinetic barrier calculations reveal NH3 is the most preferred product relative to H2 , N2 O, and N2 on Cu. Experimentally, a record-high EAS rate of 517.1 µmol cm-2 h-1 and FE of 93.5 % were achieved at -0.9 V vs. RHE using a Cu foam electrode, exhibiting stable electrocatalytic performances with a 100 h run. This work provides an alternative strategy to EAS from exhaust NO, coupled with NO removal.

19.
Angew Chem Int Ed Engl ; 59(50): 22408-22413, 2020 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-32886835

RESUMEN

Developing copper-free catalysts for CO2 conversion into hydrocarbons and oxygenates is highly desirable for electrochemical CO2 reduction reaction (CO2 RR). Herein, we report a cobalt phthalocyanine (CoPc) and zinc-nitrogen-carbon (Zn-N-C) tandem catalyst for CO2 RR to CH4 . This tandem catalyst shows a more than 100 times enhancement of the CH4 /CO production rate ratio compared with CoPc or Zn-N-C alone. Density functional theory (DFT) calculations and electrochemical CO reduction reaction results suggest that CO2 is first reduced into CO over CoPc and then CO diffuses onto Zn-N-C for further conversion into CH4 over Zn-N4 site, decoupling complicated CO2 RR pathway on single active site into a two-step tandem reaction. Moreover, mechanistic analysis indicates that CoPc not only generates CO but also enhances the availability of *H over adjacent N sites in Zn-N4 , which is the key to achieve the high CH4 production rate and understand the intriguing electrocatalytic behavior which is distinctive to copper-based tandem catalysts.

20.
Oncologist ; 24(9): e914-e920, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-30996008

RESUMEN

PURPOSE: Complex brain metastases (BMs), such as large lesions, lesions within or close to eloquent locations, or multiple recurrent/progressive BMs, remain the most challenging forms of brain cancer because of decreased intracranial control rates and poor survival. In the present study, we report the results from a single institutional phase II trial of concurrent temozolomide (TMZ) with hypofractionated stereotactic radiotherapy (HFSRT) in patients with complex brain metastases, including assessment of its feasibility and toxicity. PATIENTS AND METHODS: Fifty-four patients with histologically proven primary cancer and complex BMs were enrolled between 2010 and 2015. All the patients were treated with concurrent HFSRT and TMZ (administrated orally at a dosage of 75 mg/m2 per day for at least 20 days). The primary endpoint was overall survival (OS). RESULTS: The median follow-up time was 30.6 months. The local control rates at 1 and 2 years were 96% and 82%, respectively. The median OS was 17.4 months (95% confidence interval [CI], 12.6-22.2), and the OS rates at 1 and 2 years were 65% (95% CI, 52%-78%) and 33% (19%-47%). Only six patients (15.8%) died of intracranial disease. The median brain metastasis-specific survival was 46.9 months (95% CI, 35.5-58.4). Treatment-related grade 3-4 adverse events were rare and included one grade 3 hematological toxicity and two grade 3 liver dysfunctions. CONCLUSION: Treatment using HFSRT concurrent with TMZ was well tolerated and could significantly extend OS compared with historical controls in complex BMs. Large randomized clinical trials are warranted. Trial registration ID: NCT02654106. IMPLICATIONS FOR PRACTICE: The treatment using hypofractionated stereotactic radiotherapy concurrent with temozolomide appeared to be safe and could significantly extend overall survival compared with historical control in complex brain metastases. Large randomized clinical trials are warranted to verify our results.


Asunto(s)
Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/radioterapia , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/patología , Temozolomida/administración & dosificación , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/secundario , Terapia Combinada , Supervivencia sin Enfermedad , Fraccionamiento de la Dosis de Radiación , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/clasificación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Metástasis de la Neoplasia , Radiocirugia/efectos adversos , Temozolomida/efectos adversos , Resultado del Tratamiento
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