Flow behaviors in the downer of a large-scale triple-bed combined circulating fluidized bed system with high solids mass fluxes

The flow behaviors in the downer of a large-scale triple-bed circulating fluidized bed (TBCFB) gasifier cold model, which is composed of a downer (Φ 0.1 m×6.5 m), a bubbling fluidized bed (BFB, 0.75×0.27×3.4 m³), a riser (Φ 0.1 m×16.6 m) and a gas-sealing bed (GSB, Φ 0.158 m×5 m), were investigated. Sand particles with a density of 2600 kg/m³ and an average particle size of 128 μm were used as bed materials. Solids mass fluxes were in the range 113–524 kg/m² s. Average solids holdup in the developed region of the downer increased with increasing solids mass flux. The gas seal between the riser and the downer had a large effect on the solids holdup distribution in the downer. Compared with the solids holdup in the riser, a relatively low solids holdup was formed in the downer even at high solids loadings. A pressure balance model was set up to predict the solids mass flux for this TBCFB system. It was found that the static bed height in the GSB had a great effect on the solids mass flux. The possibilities of achieving a high density solids holdup in a downer were discussed.     

Increased Water Resistance of Bamboo Flour/Polyethylene Composites

Abstract

To improve the water resistance of bamboo flour/high-density polyethylene (HDPE) composites, the effects of plastic content, coupling agents, and the addition of micro-fibrillated cellulose (MFC) on formulations were studied, and their rheological and mechanical properties were evaluated. The composites were prepared by injecting molding with a basic composition of equivalent amounts of bamboo flour and HDPE, and the melting fluidity of the compounds, tensile strength, and tensile modulus of the composites were determined. An increase in water resistance was detected in all three tests. By increasing the plastic content, negative effects such as a decreased tensile modulus were observed. When evaluating the compatibility between bamboo flour and plastic using coupling agents and MFC addition, positive effects were noted for water resistance, melting fluidity, and tensile modulus. We also confirmed that the procedure used to increase the compatibility between bamboo flour and plastic could easily be used for industrial applications by changing the coupling agents. Overall, a novel positive property (increased tensile modulus) and an increased water resistance were observed after MFC addition.     

SO2-Enhanced Nitration of Fluoranthene and Pyrene Adsorbed on Particulate Matter in the Heterogeneous Reaction in the Presence of NO2

Heterogeneous photoreaction of fluoranthene (FL) or pyrene (PY) adsorbed on solid support under 10 ppm NO₂-air in the presence or absence of SO₂ was investigated in order to clarify the effect of SO₂ on nitroarene formation. Formation yield of nitrofluoranthenes (NFs) and nitropyrenes (NPs) were increased by the addition of SO₂ to reaction atmosphere. 1-, 2-, 7-, and 8-NFs were formed in the presence of SO₂ while 1-, 2-, and 7-NF were detected in the absence of SO₂. After the reaction for 4 h, yield of 2-NF in the presence of 10 ppm of SO₂ was 1.5 times as large as that in the absence of SO₂. 1-NP and 1,3-, 1,6-, 1,8-dinitropyrenes (DNPs) were formed both in the presence and in the absence of SO₂. After the reaction for 2 h, yields of 1-NP and DNPs in the presence of 10 ppm of SO₂ were about three times and twice as large as those in the absence of SO₂, respectively. While the yield of 1-NP and degradation rate of PY were hardly affected by the concentration of SO₂, the yield of DNPs increased with the increase in SO₂ concentration. The isomer distributions of NFs and NPs indicated that NFs and NPs were formed by non-electrophilic nitration and electrophilic nitration, respectively.     

Effects of Fe3O4 Magnetic Nanoparticles on A549 Cells

Fe₃O₄ magnetic nanoparticles (MgNPs-Fe₃O₄) are widely used in medical applications, including magnetic resonance imaging, drug delivery, and in hyperthermia. However, the same properties that aid their utility in the clinic may potentially induce toxicity. Therefore, the purpose of this study was to investigate the cytotoxicity and genotoxicity of MgNPs-Fe₃O₄ in A549 human lung epithelial cells. MgNPs-Fe₃O₄ caused cell membrane damage, as assessed by the release of lactate dehydrogenase (LDH), only at a high concentration (100 μg/mL); a lower concentration (10 μg/mL) increased the production of reactive oxygen species, increased oxidative damage to DNA, and decreased the level of reduced glutathione. MgNPs-Fe₃O₄ caused a dose-dependent increase in the CD44⁺ fraction of A549 cells. MgNPs-Fe₃O₄ induced the expression of heme oxygenase-1 at a concentration of 1 μg/mL, and in a dose-dependent manner. Despite these effects, MgNPs-Fe₃O₄ had minimal effect on cell viability and elicited only a small increase in the number of cells undergoing apoptosis. Together, these data suggest that MgNPs-Fe₃O₄ exert little or no cytotoxicity until a high exposure level (100 μg/mL) is reached. This dissociation between elevated indices of cell damage and a small effect on cell viability warrants further study.     

The influence of heat transfer and friction on the impulse of a detonation tube

In the present study, we experimentally and numerically investigated the influence of heat transfer and friction on the performance of a single-shot detonation tube open at one end. Two kinds of specific impulse measurement were carried out with various tube lengths and levels of surface roughness, one by using a ballistic pendulum arrangement and the other by integrating the pressure history measured at the thrust wall. These measurements revealed the degree to which potential impulse can be exploited by the detonation tube after the impulse losses due to various wall loss mechanisms such as heat transfer and friction. The detonation tube obtained 89%, 70%, and 64% of the theoretical ideal impulse for electropolished tubes at a ratio of tube length to diameter (L/D) of 49, 103, and 151, respectively. The impulse losses due to shear stress on the side wall of the detonation tube were found to have a dominant influence on the performance of the detonation tubes of L/D = 103 and 151, but the loss was remarkably small for L/D = 49 relative to that of the longer tubes. In addition to the experiments, a simplified one-dimensional gas-dynamic model was developed by considering heat transfer and friction as wall loss mechanisms and validated by the experimental results. This simplified model was found to predict the experimental results very well, especially in the range of L/D 103–151.     

Physical fitness and psychological benefits of strength training in community dwelling older adults

Previous studies concerning psychological benefits of exercise among the elderly has focused predominantly on the effects of aerobic exercise. In the present study, psychological and behavioral adaptations in response to 12-weeks of strength training were examined in medically healthy but sedentary 42 older adults (mean age = 68 years). The purpose of this study was to evaluate the effects of high and low intensity resistance training intensity on a) muscular fitness, b) psychological affect, and c) neurocognitive functioning. Subjects were randomly assigned to high intensity/low volume (EXH: 2 sets of 8 to 10 repetitions for 75 to 85% of 1 RM), low intensity/high volume (EXL: 2 sets of 14 to 16 repetitions for 55 to 65% of 1 RM), or no exercise control programs. Prior to and following the 12-week program, subjects underwent comprehensive physiological and psychological evaluations. Physiological assessment included measurements of blood pressure, heart rate, arm and leg muscle strength, body composition, and oxygen consumption (VO2max). Psychological measures included evaluations of mood, anxiety, and physical self-efficacy as well as cognitive functioning. The results of this study indicated that both high and low intensity strength programs were associated with marked improvements in physiological fitness and psychological functioning. Specifically, subjects in the strength training programs increased overall muscle strength by 38.6% and reduced percent body fat by 3.0%. Favorable psychological changes in the strength-trained subjects included improvements in positive and negative mood, trait anxiety, and perceived confidence for physical capability. The treatment effects of neurocognitive functioning were not significant. In summary, this study demonstrated that participation in 12-weeks of high or low intensity strength training can improve overall physical fitness, mood, and physical self-efficacy in older adults while cognitive functioning remains constant.     

Classification and characterization of hydrodynamic and transport behaviors of three-phase reactors

According to axial profile of solid concentration, the cocurrent upward threephase reactors with liquid as continuous phase can be classified into three types (a) gassparged slurry reactors, (b) threephase bubble columns, and (c) threephase fluidized beds Comparative study shows that the gas hold up, bubble characteristics and mass transfer are significantly dependent on the type of threephase reactors Three types of reactors exhibit the different hydrodynamic and transport behaviors with particle size, solid concentration and gas holdup The structural analysis of the axial solid distribution indicates the bubble and bubble wake dynamics are the key factors to the hydrodynamic and transport behaviors of three-phase reactors.     

Chemical Synthesis of Side-Chain-Hydroxylated Vitamin D3 Derivatives and Their Metabolism by CYP27B1

1α,25-Dihydroxyvitamin D₃ (abbreviated here as 1,25D₃) is a hormonally active form of vitamin D₃ (D₃), and is produced from D₃ by CYP27 A1-mediated hydroxylation at C25, followed by CYP27B1-mediated hydroxylation at C1. Further hydroxylation of 25D₃ and 1,25D₃ occurs at C23, C24 and C26 to generate corresponding metabolites, except for 1,25R,26D₃. Since the capability of CYP27B1 to hydroxylate C1 of side-chain-hydroxylated metabolites other than 23S,25D₃ and 24R,25D₃ has not been examined, we have here explored the role of CYP27B1 in the C1 hydroxylation of a series of side-chain-hydroxylated D₃ derivatives. We found that CYP27B1 hydroxylates the R diastereomers of 24,25D₃ and 25,26D₃ more effectively than the S diastereomers, but shows almost no activity towards either diastereomer of 23,25D₃. This is the first report to show that CYP27B1 metabolizes 25,26D₃ to the corresponding 1α-hydroxylated derivative, 1,25,26D₃. It will be interesting to examine the physiological relevance of this finding.