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1.
Molecules ; 28(21)2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37959783

RESUMO

Adsorption and separation of Xe/Kr are significant for making high-density nuclear energy environmentally friendly and for meeting the requirements of the gas industry. Enhancing the accuracy of the adsorbate model for describing the adsorption behaviors of Xe and Kr in MOFs and the efficiency of the model for predicting the separation potential (SP) value of Xe/Kr separation in MOFs helps in searching for promising MOFs for Xe/Kr adsorption and separation within a short time and at a low cost. In this work, polarizable and transferable models for mimic Xe and Kr adsorption behaviors in MOFs were constructed. Using these models, SP values of 38 MOFs at various temperatures and pressures were calculated. An optimal neural network model called BPNN-SP was designed to predict SP value based on physical parameters of metal center (electronegativity and radius) and organic linker (three-dimensional size and polarizability) combined with temperature and pressure. The regression coefficient value of the BPNN-SP model for each data set is higher than 0.995. MAE, MBE, and RMSE of BPNN-SP are only 0.331, -0.002, and 0.505 mmol/g, respectively. Finally, BPNN-SP was validated by experiment data from six MOFs. The transferable adsorbate model combined with the BPNN-SP model would highly improve the efficiency for designing MOFs with high performance for Xe/Kr adsorption and separation.

2.
J Environ Sci (China) ; 126: 123-137, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36503742

RESUMO

In this work, hydrothermal technique combined with KOH activation were employed to develop a series of porous carbons (NPCK-x) using tobacco stem as a low-cost carbon source and (NH4)2C2O4 as a novel nitrogen-doping agent. Physicochemical properties of NPCK-x were characterized by Brunauer-Emmett-Teller, field emission scanning electron microscopy, X-ray diffraction, Raman microscope, elemental analysis, and X-ray photoelectron spectroscopy. Results showed that the NPCK-x samples possessed large surface areas (maximum: 2875 m2/g), hierarchical porous structures, and high degree of disorder. N-containing functional groups decomposed during activation process, which could be the dominant reason for appearance of abundant mesopores and well-developed pore structure. Dynamic chlorobenzene adsorption experiments demonstrated that carbon materials with (NH4)2C2O4 modification exhibited higher adsorption capacity (maximum: 1053 mg/g) than those without modification (maximum: 723 mg/g). The reusability studies of chlorobenzene indicated that the desorption efficiency of (NH4)2C2O4 modified porous carbon reached 90.40% after thermal desorption at 100°C under N2 atmosphere. Thomas model fitting results exhibited that the existence of mesopores accelerated the diffusion rate of chlorobenzene in porous carbon. Moreover, Grand Canonical Monte Carlo simulation was conducted to verify that micropores with pore sizes of 1.2-2 nm of the optimized porous carbon were the best adsorption sites for chlorobenzene and mesopores with pore sizes of 2-5 nm were also highly active sites for chlorobenzene adsorption.


Assuntos
Carbono , Clorobenzenos , Adsorção , Porosidade
3.
Int J Nurs Stud ; 152: 104694, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38281450

RESUMO

BACKGROUND: Cancer-related fatigue is one of the most common symptoms in cancer patients, usually accompanied by anxiety, depression and insomnia, which seriously affect patients' quality of life. Progressive muscle relaxation training is widely used for cancer-related fatigue, but the overall effect is unclear. OBJECTIVES: The aim of this study was to summarize the evidence on the effects of progressive muscle relaxation training on cancer-related fatigue and quality of life in cancer patients. DESIGN: Systematic review and meta-analysis. METHODS: Nine electronic databases (PubMed, Excerpta Medica Database (Embase), The Cochrane Library (Cochrane Central Register of Controlled Trials, CENTRAL), Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Chinese Biomedical Literature Database (CBM), Chinese National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP) and Wanfang Database) were explored for randomized controlled trials (RCTs) published before February 2023. This study was reported based on the PRISMA 2020 statement. The Cochrane Collaboration's risk of bias assessment tool was used for methodological assessment, and the GRADE pro online assessment tool was used for evidence evaluation. The data were analyzed with the Review Manager 5.4 software. RESULTS: Twelve studies involving 1047 patients were included. Meta-analysis showed that progressive muscle relaxation training plus routine nursing produced more positive effects than routine nursing in improving cancer-related fatigue [SMD = -1.06, 95 % CI -1.49, -0.62, P < 0.00001], anxiety [SMD = -1.09, 95 % CI -1.40, -0.77, P < 0.00001], depression [SMD = -1.43, 95 % CI -1.76, -1.10, P < 0.00001], and quality of sleep [MD = -1.41, 95 % CI -1.74, -1.08, P < 0.00001]. However, there was no significant difference in improving quality of life [SMD = 0.27, 95 % CI -0.62, 1.15, P = 0.55]. Progressive resistance exercise plus routine nursing improved cancer-related fatigue more than progressive muscle relaxation training plus routine nursing [SMD = 1.11, 95 % CI 0.43, 1.78, P = 0.001]. There was low certainty of evidence that progressive muscle relaxation training improved cancer-related fatigue and quality of sleep, and the evidence that improved quality of life, anxiety and depression was very low. CONCLUSION: Current evidence suggested that progressive muscle relaxation training has the potential to improve cancer-related fatigue, anxiety, depression and quality of sleep in patients with cancer and is a low-load, simple exercise worthy of recommendation for cancer patients in fatigue state. Future research should focus on improving the methodological quality of randomized controlled trials to enhance the persuasive evidence of progressive muscle relaxation training efficacy.


Assuntos
Treinamento Autógeno , Neoplasias , Humanos , Exercício Físico , Fadiga/etiologia , Fadiga/terapia , Neoplasias/complicações , Qualidade de Vida
4.
J Air Waste Manag Assoc ; 71(6): 689-700, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33428540

RESUMO

To eliminate nitrogen oxides (NOx), composite carrier-supported catalysts (Mn-Ce/MWCNT-W) and traditional catalysts (Mn-Ce/MWCNT and W-Mn-Ce/MWCNT) were prepared using an ultrasonic impregnation method that preformed low-temperature ammonia-selective catalytic reduction (SCR) removal of NOx. The promotion effects of MWCNT-W composite carriers for low temperature SCR activities and SO2 tolerance of the catalysts were systematically investigated. Compared to traditional catalyst, Mn-Ce/MWCNT-W catalyst, with a 30% WOx/MWCNT mass ratio, demonstrated improved SCR activity and high N2-selectivity from 100°C to 200°C. A series of characterizations were carried out and it was found that there were more redox sites and the stronger the NH3 adsorption capacity over the composite carrier-supported catalysts than traditional catalysts. Also, with this composite carrier-supported catalyst, the improvement of SCR reaction was considered to be from the abundance of high valence state Mn and well dispersed active components. Notably, compared to traditional catalyst, the composite carrier-supported catalyst exhibited the stronger sulfur resistance. Thus, using MWCNT-W composite carriers to prepare Mn-Ce/MWCNT-W catalysts resulted in excellent NOx conversion and SO2 resistance at low temperatures.Implications: LT NH3-SCR of NOx is an effective way to remove NOx from stationary sources. The physicochemical properties of the support not only affect a catalyst's LT SCR activity but also affect the catalyst's anti-poisoning performance. The modified carriers could promote active component dispersion, which is conducive to SCR reaction. However, for LT SCR reactions, few reports have addressed the design and preparation of composite carrier-supported catalysts. The goal of this study was to design and synthesize Mn-Ce/MWCNT-W catalysts and to observe the influence of composite support in Mn-based catalysts on LT SCR activity and sulfur resistance.


Assuntos
Amônia , Óxidos , Catálise , Oxirredução , Enxofre , Temperatura
5.
RSC Adv ; 10(23): 13855-13865, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35493013

RESUMO

A MnO x @PrO x catalyst with a hollow urchin-like core-shell structure was prepared using a sacrificial templating method and was used for the low-temperature selective catalytic reduction of NO with NH3. The structural properties of the catalyst were characterized by FE-SEM, TEM, XRD, BET, XPS, H2-TPR and NH3-TPD analyses, and the performance of the low-temperature NH3-SCR was also tested. The results show that the catalyst with a molar ratio of Pr/Mn = 0.3 exhibited the highest NO conversion at nearly 99% at 120 °C and NO conversion greater than 90% over the temperature range of 100-240 °C. Also, the MnO x @PrO x catalyst presented desirable SO2 and H2O resistance in 100 ppm SO2 and 10 vol% H2O at the space velocity of 40 000 h-1 and a testing time of 3 h test at 160 °C. The excellent low-temperature catalytic activity of the catalyst could ultimately be attributed to high concentrations of Mn4+ and adsorbed oxygen species on the catalyst surface, suitable Lewis acidic surface properties, and good reducing ability. Additionally, the enhanced SO2 and H2O resistance of the catalyst was primarily ascribed to its unique core-shell structure which prevented the MnO x core from being sulfated.

6.
J Hazard Mater ; 399: 123011, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32535516

RESUMO

A novel MnOx@Eu-CeOx catalyst with multiple protective attributes was designed and fabricated using a chemical precipitation method and tested for its low temperature SCR activity. The subject MnOx@Eu-CeOx nanorod catalyst exhibited superior SCR performance and strong SO2-tolerance. The formation of the composite-shell structure enhanced the catalysts' surface acidity and redox performance, which resulted in excellent SCR performance. Moreover, the TG results suggested that the protective effect of the EuOx-CeOx composite-shell effectively reduced the deposition of the surface sulphates. The XPS, XRD analysis results of the subject catalyst together with theoretical calculations provided strong evidence that there was a strong interaction between Mn and Ce in the MnOx@Eu-CeOx. This significant interaction could provide maximum protection to the core from the effect of SO2, which also contributed to the high SO2 resistance of the catalyst. In situ FT-IR results also indicated that the chemisorbed species on MnOx@Eu-CeOx were much more stable in the presence of SO2 compared to Eu-CeOx/MnOx, which resulted in the deposition of significantly less sulphates. This low temperature SCR catalyst with multiple protective attributes, including composite shell, strong interaction and core-shell structure, is the key to long-term resistance to SO2.

8.
Environ Technol ; 38(8): 1030-1042, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27494642

RESUMO

The low-temperature selective catalytic reduction (SCR) of NOx is a promising technology for removing NOx from flue gases. However, the vulnerability of Mn-based catalysts to SO2 and H2O poisoning makes them unsuitable for industrial application. Herein, catalysts based on the MnOx/SAPO-34 catalysts were prepared by conventional impregnation and an improved molecularly designed dispersion method for use in the low-temperature SCR. The improved molecularly designed catalyst containing 20 wt% of MnOx exhibited high low-temperature NH3-SCR activity. Nearly 90% of the NOx was converted exclusively to N2 at 160°C using this catalyst. The structure and morphological analyses of the catalyst showed that the amorphous MnOx was well dispersed on the surface of the support. The reasons for the high performance of the catalysts were ascertained using surface N2 adsorption, XPS, H2-TPR and NH3-TPD. The results of these analyses indicated that high specific surface area and the redox capability, of the abundant Mn4+ and Mn3+ species, coupled with the surface chemisorbed oxygen and strong acid sites had a significant effect on the SCR reaction. In addition, the effects of SO2 and H2O on activity of the catalysts were also investigated and it was found that the highly dispersed 20 wt% MnOx/SAPO-34 catalyst exhibited better SO2 poisoning resistance than the other impregnated catalysts.


Assuntos
Amônia/química , Compostos de Manganês/química , Óxido Nítrico/química , Óxidos/química , Zeolitas/química , Adsorção , Catálise , Temperatura Baixa , Gases , Hidrogênio/química , Íons , Microscopia Eletrônica de Varredura , Nitrogênio/química , Oxirredução , Dióxido de Enxofre/química , Água/química , Difração de Raios X
9.
Environ Sci Pollut Res Int ; 24(8): 7499-7510, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28116621

RESUMO

Manganese-rich MnSAPO-34 molecular sieves were prepared by one-pot synthesis method for NO x abatement using the ammonia-selective catalytic reduction (NH3-SCR) technology and characterized using ICP, BET, XRD, FE-SEM, H2-TPR, NH3-TPD, XPS, and DR UV-Vis analyses. The experimental results indicate that the Mn content and chemical state, as well as the surface acidity, of the MnSAPO-34 molecular sieves significantly enhance their DeNO x efficiency at low temperatures (ca. 200-300 °C). The manganese-rich MnSAPO-34 was synthesized using a combination of triethylamine and diisopropylamine as the structural directing agents and high Mn loading (n(MnO)/n(P2O5) = 0.4). The resulting catalyst exhibits the highest activity among all of the samples with a NO x conversion value of nearly 95% and a N2 selectivity that is higher than 90% at 220-400 °C. In addition, this catalyst presents higher NO x conversion than the conventional V2O5-WO3/TiO2 catalysts and other SAPO-based catalysts below 300 °C. Furthermore, the analytical results indicate that the manganese species in the catalyst are mainly in the form of a framework Mn(IV), which could play a significant role in the NH3-SCR process as the specific active species. The results suggest that controlling the types and content of the organic amine templates and variations in the surface acidity of the catalysts may significantly enhance the SCR activity at lower temperatures.


Assuntos
Amônia , Manganês/química , Óxido Nítrico , Amônia/análise , Amônia/química , Catálise , Temperatura Baixa , Óxido Nítrico/análise , Óxido Nítrico/química
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