Dietary intakes of vitamins are associated with asthma. However, previous studies mainly explored the association between a single vitamin intake and asthma, which did not take the multivitamins into ...consideration. Herein, this study aims to explore the overall effect of dietary multivitamins consumption on childhood asthma.
Data of children and adolescents (aged 2-17 years old) were extracted from the National Health and Nutrition Examination Survey (NHANES) database in 2015-2018 in this cross-sectional study. Weighted univariate logistic regression analysis was used to screen covariates. The association between multivitamins (including vitamin A, C, D, E, B1, B2, B6, B12, K, niacin, folic acid, and choline) and childhood asthma was explored using univariate and multivariate logistic regression analyses. The evaluation indexes were odds ratio (OR) and 95% confidence interval (CI). We further introduced the Bayesian kernel machine regression (BKMR) to assess the joint effect of the twelve vitamins on childhood asthma, the impact of an individual vitamin as part of a vitamin mixture, and the potential interactions among different vitamins.
Among 4,715 eligible children and adolescents, 487 (10.3%) had asthma. After adjusting for covariates including race, family history of asthma, pregnant smoking, BMI Z-score, energy intake, breast feeding, and low birth weight, we found that for each 1-unit increase in vitamin K consumption, the odds of childhood asthma decreased 0.99 (P=0.028). The overall effect analysis reported a trend of negative relationship between the multivitamins and childhood asthma, especially at the 75th percentile and over. According to the BKMR models, when other vitamins are fixed at the median level, the odds of childhood asthma increased along with the elevated vitamin D (VD) and vitamin B2 (VB2), whereas along with the depressed vitamin C (VC). In addition, no potential interaction has been found between every two vitamins of multivitamins on childhood asthma.
Among children and adolescents who have high-risk of asthma, it may be beneficial to increase dietary consumption of multivitamins. Our findings recommended that children and adolescents should increase the intake of VC-rich foods, whereas control the dietary consumption of VD and VB2 in daily life.
In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite ...the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds（CFBs）. This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work.
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A schematic diagram of the micro-fluidized bed reaction analyzer (MFBRA).
•The pyrolysis kinetics of oil shale and coals were studied by using MFBRA.•The releasing-gas behaviors from ...pyrolysis were different.•Oil shale had higher value of pyrolysis activation energy than coals.•The MFBRA could be a reliable tool for the kinetics of gas-solid reactions.
The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer (MFBRA). The isothermal differential model was first applied to calculate the kinetic parameters of activation energy and frequency factor according to the major gas components during pyrolysis. The results showed that the major gas components released from coal and oil shale under the isothermal condition had different initiating and ending time points, and the difference was more significant under the programmed heating conditions. The shrinking core model allowed better fitting relevance for the coal pyrolysis, while the three-dimension model was more suitable for oil shale pyrolysis, indicating that the gases from the pyrolysis process of coal and oil shale might go through different reaction paths. The activation energy of oil shale pyrolysis was 36.96 kJ·mol−1, larger than the value of pyrolysis of the two coals, which was 21.16 and 32.17 kJ·mol−1, respectively. The above results justified that the oil shale pyrolysis with high ash contents was somehow more difficult to take place in terms of higher activation energy and the MFBRA could be a useful tool to give some insight into the intrinsic kinetics and reaction mechanisms of coal and oil shale pyrolysis.
To investigate the impact of recombinant human interferon α1b (rhIFNα1b) treatment in infants hospitalized with lower respiratory tract infections on subsequent wheezing.
The clinical data of infants ...(n=540) with viral pneumonia, wheezy bronchitis, or bronchiolitis hospitalized in 19 Chinese hospitals from June 2009 to June 2015 were retrospectively analyzed. The parameters relevant to wheezing episodes within the last year were collected by telephone and questionnaires. The rhIFNα1b treatment group (n=253) and control group (n=287) were compared in terms of wheezing episodes within the last year. Moreover, the wheezing group (95 cases) and non-wheezing group (445 cases) were compared.
Out of 540 cases, 95 (17.6%) experienced wheezing episodes, 13.8% (35/253) cases treated with rhIFNα1b, and 20.9% (60/287) cases without rhIFNα1b experienced wheezing episodes within the last year. The rhIFNα1b treatment significantly improved wheezing episodes within the last year, compared with the control peers (p=0.031). Single-factor regression showed statistically significant differences between the wheezing and non-wheezing groups in terms of age, rhIFNα1b use, childhood and family history of allergy, housing situation, and feeding history (p<0.05). Binary logistic regression showed a childhood history of allergy (OR=2.14, p=0.004), no rhIFNα1b use (OR=1.70, p=0.028), and living in a crowded house (OR=1.92, p=0.012) might be risk factors of subsequent wheezing. Accordingly, breastfeeding (OR=0.44, p=0.008) and hospitalization age of ≤1-year-old (OR=0.58, p=0.024) were protective factors.
Early use of rhIFNα1b in infants hospitalized with lower respiratory tract infections and breastfeeding could prevent subsequent wheezing. Living in a crowded house could promote subsequent wheezing.
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•The alkaline dissolution route was first proposed to utilize sFCCc to synthesize PEI/MCM-41 for dilute-source CO2 capture.•The adsorption capacity remained nearly constant in 50 ...temperature swing cycles.•CO2 adsorption kinetics of sFCCc derived MCM-41-supported PEI was analyzed using Avrami model.
The buildup of solid waste as well as the global warming has become one of the major challenges. CO2 capture with solid amine synthesized from solid waste can not only address the issue of large CO2 emissions, but also achieve efficient utilization of solid waste. In this work, spent fluid catalytic cracking catalysts (sFCCc), a type of major wastes in petrochemical industries, are first utilized to synthesize polyethyleneimine (PEI) functionalized ordered mesoporous materials. The as-obtained MCM-41-PEI from sFCCc exhibits an acceptable equilibrium CO2 capacity (qe) of 2.7 mmol/g in simulated flue gases (10 % CO2/N2) at 65 °C, which is higher than one prepared with commercial silicon source. Moreover, the adsorbent displays excellent cyclic stability during 50 TSA cycles in the dry simulated flue gases, where the capacity decreases only by 4.9 %. Additionally, the breakthrough capacity (qb) is significantly improved from 0.6 mmol/g to 1.6 mmol/g under humid conditions (35 °C, 10 % CO2/N2). Interestingly, we discover that the optimal adsorption temperature of MCM-41-PEI with different PEI loadings shifted due to the distinct PEI distribution behavior within the pores. The Avrami model provides a reliable interpretation for the CO2 adsorption behavior of MCM-41-PEI at various test conditions. The synthetic strategy here provides a new route in the treatment of excessive sFCCc resources to achieve valuable adsorbents, which can be applied to dilute source CO2 capture processes.
•Extraction of dibenzothiophene (DBT) from diesel in segmented flow microreactor by using ionic liquid (IL) was investigated.•A fast extraction equilibration time of <120 s was obtained.•Proposed ...correlations predicted well experimental segment lengths.•The mass transfer resistance of the process concentrated primarily in the IL phase.•Relationships between flow, mass transfer and desulfurization performance were discussed.
Conventional hydrodesulfurization technology was limited to treat aromatic heterocyclic sulfur compounds in ultralow-sulfur diesel. Extractive desulfurization (EDS) using ionic liquid (IL) exhibited good performance to address these issues, except for its long extraction time (15–40 min). To address this, microreactor was adopted to intensify the IL-based EDS, where dibenzothiophene was extracted from model diesel (MD) as the continuous phase to 1-butyl-3-methylimidazolium tetrafluoroborate as the dispersed phase under segmented flow (which appeared preferably at capillary numbers lower than 0.01). The effects of temperature, residence time and flow rate ratio on the desulfurization efficiency were investigated. The extraction equilibration time could be shortened from more than 15 min in conventional batch extractors to 120 s in microreactors. The extraction process was modeled according to the two-film model applied within a unit cell of the segmented flow, where the mass transfer resistance was considered primarily on the film side of the IL droplet. The mechanism for the improved EDS performance at higher temperatures or larger IL to MD flow ratios was investigated and validated, which was related to the significant increase in the diffusion coefficient or the specific interfacial area. These findings may shed important insights into the precise manipulation of IL-based EDS for a better process design and reactor optimization.
Industrial reactors often involve change in volumetric flow rate of gas phase due to chemical reactions, which can have significant effects on the gas-solid flow field in the reactor. The common ...method to study these effects usually injects additional gas along the bed height, which can introduce abrupt change in flow hydrodynamics. This work compares such common method and a method with constant change of volumetric flow rate of gas phase using Computational Fluid Dynamics (CFD) simulations. It was found that the common method can significantly influence the particle flow behaviors near the sidewall and weaken the core-annular flow pattern. Such common method can make the radial distribution of the solids holdup more uniform, which derivates from the real industrial conditions. With more cases focusing on different changes of gas velocity and bed expansion ratio, it was demonstrated that the change in volumetric flow rate of gas phase due to chemical reactions should be appropriately treated for providing adequate and accurate information for operation and design of industrial turbulent fluidized bed reactors.
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•Flow behaviors with different variable gas velocity methods were compared.•Effects of additional gas injection on the flow field were discussed.•Flow field distribution with constant and variable gas velocity was studied.•Flow field distribution with different gas-phase expansion ratios was studied.
In turbulent fluidized bed (TFB), the superficial gas velocity usually varies since chemical reactions can change the number of gas moles. However, information from the study without considering the ...variation of gas velocity is usually used to guide the design and operation of industrial TFB reactors. In order to reveal the difference of constant and variable gas velocity and to address the possible effect of without considering variation of gas velocity, experiment and three-dimensional Computational Fluid Dynamics (3D CFD) simulation were performed on the gas-solid flow characteristics in TFB. Results show that the nonuniformity of axial flow field can be overestimated while the nonuniformity of radial flow field can be underestimated without considering the variation of gas velocity for the system in which the number of gas mole increases due to chemical reactions. Such different flow hydrodynamics with and without considering the variation of gas velocity can be more clearly observed at higher solids handle capacity. CFD simulation results indicate that the presence of particle clusters can provide reliable explanations on the different flow behavior at constant and variable gas velocity. The particle tracer information and the residence time distribution (RTD) of gas phase indicate that the back-mixing of gas and solids can be overestimated without considering the variation of gas velocity. Results indicated that the guiding information from the constant gas velocity study can largely misguide the estimation of the conversion process if this guiding information is applied in the actual industrial process with the number change of gas moles in chemical reactions.
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•Flow behaviors at variable gas velocities were studied in turbulent fluidized bed.•Internal flow structures were compared at constant and variable gas velocities.•Particle tracer and gas RTD were analyzed to address solid and gas back-mixing.•Possible effect of without considering variation of gas velocity was discussed.•Considering gas velocity variation was important for guiding TFB design.
•Pyrolysis of coal with and without the addition of CaO were compared.•Pyrolysis kinetics using 2-DAEM and 3-DAEM were separately developed.•2-DAEM was accurate enough for describing the pyrolysis of ...pure coal.•3-DAEM can capture the main characteristics of coal with CaO additive.•CaO can promote the release of volatiles during coal pyrolysis at lower temperature.
The pyrolysis of coal mixing with CaO can produce uniform mixture of residual char and CaO, which can be further converted into calcium carbide for providing alternative way of ethyne production. Therefore, knowledge on the pyrolysis behavior of coal at the presentation of CaO is important for the industrial production of such mixture of residual char and CaO. By comparing the TG/DTG curves of pure coal and mixture coal (with CaO), it was found that the addition of CaO can promote the release of volatiles especially at lower temperature. The Distributed Activation Energy Model (DAEM) were developed for pure coal and mixture coal separately for analyzing their corresponding pyrolysis kinetics. While 2-DAEM with two-Gaussian functions is accurate enough for describing the pyrolysis of pure coal, 3-DAEM is more suitable for capturing the main pyrolysis characteristics of mixture coal. DAEM results show lower average activation energy for the pyrolysis of mixture coal than that of pure coal, further demonstrating the catalysis effect of CaO on coal pyrolysis.
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