RESUMEN
Establishing effective charge transfer channels between two semiconductors is key to improving photocatalytic activity. However, controlling hetero-structures in situ and designing binding modes pose significant challenges. Herein, hydrolytic SnCl2·2H2O is selected as the metal source and loaded in situ onto a layered carbon nitriden supramolecular precursor. A composite photocatalyst, S4-Sn-N2, with electron pathways of SnS2 and tubular carbon nitriden (TCN) is prepared through pyrolysis and vulcanization processes. The contact interface of SnS2-TCN is increased significantly, promoting the formation of S4-Sn-N2 micro-structure in a Z-scheme charge transfer channel. This structure accelerates the separation and transport of photogenerated carriers, maintains the stronger redox ability, and improves the stability of SnS2 in this series of heterojunctions. Therefore, the catalyst demonstrated exceptional photocatalytic hydrogen production efficiency, achieving a reaction rate of 86.4 µmol h-1, which is 3.15 times greater than that of bare TCN.
RESUMEN
The photocatalytic efficiency of polymeric carbon nitride is hampered by high carrier recombination rate and low charge transfer. Herein, these issues are addressed by constructing 1D strip-like carbon nitride with a large π-electron conjugated system from carbon-doping, realizing the synchronization control of its electronic structure and morphology. Nicotinic acid, a monomer with the carboxyl group and pyridine ring, and melamine are selected for assembling the strip-like supramolecular via hydrogen bond under hydrothermal process. Both peripheral pyridine unit and hydrogen bond have significant effect on self-assembly process of nicotinic acid and melamine along one dimension to form a strip-like precursor. Subsequently, 1D thin porous strip-like carbon nitride is obtained by calcination treatment of precursor. The as-prepared 1D strip-like carbon nitride with effective π delocalization from carbon-doping and porous structure can accelerate charges and mass transfer and provide extra active sites. Both theoretical and experimental results demonstrate that carbon doping (pyridine heterocycle) narrows the bandgap via manipulating the band position and increases the π electron density. Thus, the 1D porous thin strip-like carbon nitride realizes compelling hydrogen evolution rate (126.2 µmol h-1 ), far beyond (≈18 fold) the value of polymeric carbon nitride (PCN) (7.2 µmol h-1 ) under visible light irradiation.
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Bone mineral density (BMD) changes were reported to be associated with excessive fluoride exposure and abnormal expression of RUNX2. However, whether the alteration of methylation status, a most commonly used marker for the alteration of gene expression in epidemiological investigation, of RUNX2 is associated with low-to-moderate fluoride exposure and BMD changes has not been reported. Our study aims to explore the role of RUNX2 promoter methylation in BMD changes induced by low-to-moderate fluoride exposure. A total of 1124 adults (413 men and 711 women) were recruited from Kaifeng City in 2017. We measured BMD using ultrasound bone densitometer. Concentrations of urinary fluoride (UF) were measured using ion-selective electrode, and the participants were grouped into control group (CG) and excessive fluoride group (EFG) according to the concentration of UF. We extracted DNA from fasting peripheral blood samples and then detected the promoter methylation levels of RUNX2 using quantitative methylation-specific PCR. Relationships between UF concentration, RUNX2 promoter methylation and BMD changes were analyzed using generalized linear model and logistic regression. Results showed in EFG (UF concentration > 1.6 mg/L), BMD was negatively correlated with UF concentration (ß: -0.14; 95%CI: -0.26, -0.01) and RUNX2 promoter methylation (ß: -0.13; 95%CI: -0.22, -0.03) in women. The methylation rate of RUNX2 promoter increased by 2.16% for each 1 mg/L increment in UF concentration of women in EFG (95%CI: 0.37, 3.96). No any significant associations between UF concentration, RUNX2 promoter methylation, and BMD were observed in the individuals in CG. Mediation analysis showed that RUNX2 promoter methylation mediated 18.2% (95% CI: 4.2%, 53.2%) of the association between UF concentration and BMD of women in EFG. In conclusion, excessive fluoride exposure (>1.6 mg/L) is associated with changes of BMD in women, and this association is mediated by RUNX2 promoter methylation.
Asunto(s)
Densidad Ósea/efectos de los fármacos , Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Exposición a Riesgos Ambientales/análisis , Fluoruros/toxicidad , Contaminantes Químicos del Agua/toxicidad , Absorciometría de Fotón , Adulto , Anciano , Densidad Ósea/genética , China , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Estudios Transversales , Metilación de ADN/efectos de los fármacos , Femenino , Fluoruros/orina , Humanos , Masculino , Persona de Mediana Edad , Regiones Promotoras Genéticas , Encuestas y Cuestionarios , Contaminantes Químicos del Agua/orinaRESUMEN
A facile, specific, seed-assisted strategy for the synthesis of EU-1/ZSM-48 co-crystalline zeolites in the presence of hexamethonium ions (HM2+ ) has been developed. EU-1/ZSM-48 co-crystalline zeolites with various phase proportions, with EU-1 in the range of 25â wt %-86â wt %, were obtained by adding high-silica EU-1 seeds (SiO2 /Al2 O3 ratio of 300) and adjusting the synthesis parameters. Not only can the phase proportions of EU-1/ZSM-48 co-crystalline zeolites be controlled, but also the stability period for co-crystallization of the two phases can be extended through varying the amount of EU-1 seeds and the HM2+ template. Moreover, with the increase of the EU-1 proportion in the EU-1/ZSM-48 co-crystalline, the framework SiO2 /Al2 O3 ratios of EU-1 phase promotes steadily. Major differences in acidity and textural properties of the EU-1/ZSM-48 co-crystalline zeolites (Coz) were found with varying phase proportions, due to their distinct topological structures, crystal morphology and asymmetry between the EU-1 and ZSM-48 phases. For instance, the EU-1/ZSM-48 zeolite containing 75â wt % of EU-1 (Coz-75) possesses specific acidity and mesoporous characteristics, showing an excellent catalytic activity and stability in n-hexane cracking reaction. Compared to EU-1, ZSM-48, and a mechanical mix of the two zeolites (Mix-75), Coz-75 resulted in the highest hexane conversion and yields of light olefins, with a propylene yield, in particular, up to 38.3â wt %, which is 6.3 % more than that of the Mix-75 sample.
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OBJECTIVE: To observe the impacts of electro-acupuncture (EA) and psychological intervention (PI) on impulsive behavior among internet addiction (IA) adolescents. METHODS: Thirty-two IA adolescents were allocated to either EA (16 cases) or PI (16 cases) group by a randomized digital table. Subjects in the EA group received EA treatment and subjects in the PI group received cognition and behavior therapy. All adolescents underwent 45-d intervention. Sixteen healthy volunteers were recruited into a control group. Barratt Impulsiveness Scale (BIS-11) scores, Young's Internet Addiction Test (IAT) as well as the ratio of brain N-acetyl aspartate (NAA) to creatine (NAA/Cr) and choline (Cho) to creatine (Cho/Cr) were recorded by magnetic resonance spectroscopy before and after intervention respectively. RESULTS: The IAT scores and BIS-11 total scores in both EA and PI group were remarkably decreased after treatment (P<0.05), while EA group showed more significant decrease in certain BIS-11 sub-factors (P<0.05). Both NAA/Cr and Cho/Cr were significantly improved in EA group after treatment (P<0.05); however, there were no significant changes of NAA/Cr or Cho/Cr in PI group after treatment (P>0.05). CONCLUSIONS: Both EA and PI had significantly positive effect on IA adolescents, especially in the aspects of psychological experiences and behavioral expressions, EA might have an advantage over PI in terms of impulsivity control and brain neuron protection. The mechanism underlying this advantage might be related to the increased NAA and Cho levels in prefrontal and anterior cingulate cortices.
Asunto(s)
Conducta Adictiva/terapia , Trastornos Disruptivos, del Control de Impulso y de la Conducta/terapia , Electroacupuntura , Internet , Adolescente , Ácido Aspártico/metabolismo , Colina/metabolismo , Creatina/metabolismo , Humanos , Espectroscopía de Resonancia Magnética , Estándares de Referencia , Adulto JovenRESUMEN
The investigation on the modification of NaY zeolite on LaHY and AEHY (AE refers Ca and Sr and the molar ratio of Ca and Sr is 1:1) zeolites was proformed by XRD, N2-physisorption (BET), XRF, XPS, NH3-TPD, Py-IR, hydrothermal stability, and catalytic cracking test. These results indicate that HY zeolite with ultra low content Na can be obtained from NaY zeolite through four exchange four calcination method. The positioning capability of La(3+) in sodalite cage is much better than that of AE(2+) and about 12 La(3+) can be well coordinated in sodalite cages of one unit cell of Y zeolite. Appropriate acid amount and strength favor the formation of propylene and La(3+) is more suitable for the catalytic cracking of cyclohexane than that of AE(2+). Our results not only elaborate the variation of the strong and weak acid sites as well as the Brönsted and Lewis acid sites with the change of exchanged ion content but also explore the influence of hydrothermal aging of LaHY and AEHY zeolites and find the optimum ion exchange content for the most reserved acid sites. At last, the coordination state and stabilization of ion exchanged Y zeolites were discussed in detail.