277 research outputs found
Phase equilibria and methane enrichment of clathrate hydrates of mine ventilation air + tetrabutylphosphonium bromide
This paper reports the experimentally measured phase equilibrium conditions for the clathrate hydrates formed from simulated mine ventilation air (0.50 vol % CH + 99.50 vol % air) in the presence of 0, 5, 20, 37.1, and 50 wt % of tetrabutylphosphonium bromide (TBPB). These equilibrium conditions were measured at the temperature range of 281.62-292.49 K and pressure range of 1.92-18.55 MPa by using an isochoric equilibrium step-heating pressure search method. The results showed that addition of TBPB allowed the hydrate dissociation condition for mine ventilation air to become milder, and at a given temperature, the lowest hydrate dissociation pressure was achieved at 37.1 wt % TBPB, corresponding to the stoichiometric composition for TBPB·32H O. For each TBPB concentration tested, the semilogarithmic plots of hydrate dissociation pressure versus reciprocal absolute temperature can be satisfactorily fitted to two straight lines intersecting at 6.5 MPa. The slopes of these fitted straight lines are indifferent to changes in TBPB concentration. Gas composition analysis by gas chromatography also found that in the presence of 37.1 wt % TBPB, CH could be enriched approximately 3.5-fold in the hydrate phase
Phase equilibrium measurements for clathrate hydrates of flue gas (CO2 + N2 + O2) in the presence of tetra-n-butyl ammonium bromide or tri-n-butylphosphine oxide
This paper reports the measured hydrate phase equilibria of simulated flue gas (12.6 vol% CO2, 80.5 vol% N2, 6.9 vol% O2) in the presence of tetra-n-butyl ammonium bromide (TBAB) or tri-n-butylphosphine oxide (TBPO), at (0, 5 and 26) wt%, respectively. The measurements of the phase boundary between (hydrate + liquid + vapor) (H + L + V) phases and (liquid + vapor) (L + V) phases were performed within the temperature range (275.97 to 293.99) K and pressure range (1.56 to 18.78) MPa with using the isochoric step-heating pressure search method. It was found that addition of TBAB or TBPO allowed the incipient equilibrium hydrate formation conditions for the flue gas to become milder. Compared to TBAB, TBPO was largely more effective in reducing the phase equilibrium pressure
Thermodynamic stability conditions, methane enrichment, and gas uptake of ionic clathrate hydrates of mine ventilation air
Abatement of methane from mine ventilation air (MVA) is a significant challenge faced by coal mining industry. A promising method for methane capture from gas mixture is clathrate hydrate formation. In search of suitable and cost-effective low-dosage promoters for hydrate-based methane capture processes, this paper reports the pressure requirement for the hydrate formation of simulated MVA (0.5vol% CH+99.5vol% air) and its potential for methane extraction, in the presence of tri-n-butyl phosphine oxide (TBPO) or tetra-n-butyl ammonium bromide (TBAB) at three different initial loadings (5wt%, 15wt%, and 26wt%). An isochoric equilibrium step-heating pressure search method was used to measure the hydrate phase equilibrium conditions at the temperature range of (277.61-295.54) K and pressure range of (0.23-19.11) MPa. It was found that at a given initial loading, TBPO was largely more effective than TBAB in reducing the pressure requirement for hydrate formation of MVA. At a given temperature, the equilibrium pressures of the clathrate hydrates were indifferent to the change in the initial loading of TBPO from 5wt% to 26wt%, in contrast to those of TBAB. Gas composition analysis by gas chromatography confirmed that CH could be significantly enriched in the ionic clathrate hydrates, and the highest methane enrichment ratio obtained in the present work was 300%, with TBPO at initial loading of 5wt%. At this relatively low loading, within a given period of 5h, TBPO also led to higher gas uptake compared with TBAB. The advantages of TBPO as a promoter of MVA hydrate were discussed
Ti4O7/g-C3N4 for Visible Light Photocatalytic Oxidation of Hypophosphite: Effect of Mass Ratio of Ti4O7/g-C3N4
Hypophosphite wastewater treatment is still a critical issue in metallurgical processes and the oxidation of hypophosphite to phosphate followed by the precipitation of phosphate is an important strategy for hypophosphite wastewater treatment. Herein, Ti4O7/g-C3N4 photocatalysts with various mass ratios (Ti4O7 (m): g-C3N4 (m) = 0.5, 0.2, 0.1, and 0.05) were synthesized by a hydrolysis method and the effect of the mass ratio of Ti4O7 (m): g-C3N4 (m) on Ti4O7/g-C3N4 visible light photocatalytic oxidation of hypophosphite was evaluated. The as-prepared Ti4O7/g-C3N4 were characterized and confirmed by SEM, XPS, XRD and FTIR. Moreover, the specific surface area and the distribution of pore size of Ti4O7/g-C3N4 was also analyzed. Our results showed that Ti4O7/g-C3N4 exhibited remarkably improved photocatalytic performance on hypophosphite oxidation compared with g-C3N4 and meanwhile 1:2-Ti4O7/g-C3N4 with a mass ratio of 0.5 showed the best photocatalytic performance with the highest oxidation rate constant (17.7-fold and 91.0-fold higher than that of pure g-C3N4 and Ti4O7, respectively). The enhanced performance of photocatalytic oxidation of hypophosphite was ascribed to the heterojunction structure of Ti4O7/g-C3N4 with broader light absorption and significantly enhanced efficiency of the charge carrier (e−-h+) generation and separation. Additionally, the generated ·OH and ·O2- radicals contributed to the hypophosphite oxidation during the photocatalytic system
Protective effect of grifolin against brain injury in an acute cerebral ischemia rat model
Purpose: To evaluate the protective effects of grifolin against brain injury in an acute cerebral ischemia rat model.Methods: Rats were assigned to five groups: control, negative control, and grifolin (50, 100, and 200 mg/kg, p.o.) treated groups, which received the drug for 2 weeks. All the animals were sacrificed at the end of the protocol, and tissue homogenates were prepared from isolated brain tissue. Glutathione peroxidase (GPX), superoxide dismutase (SOD), malondialdehyde (MDA), and nitric oxide (NO), as oxidative stress indicators, were determined for the tissue homogenates of the ischemic rats. Inflammatory mediators (cytokines and nuclear factor kappa B p65, NF κB), DNA damage, and ATP and caspase 3 levels in the tissue homogenates were also assessed.Results: Treatment with grifolin increased SOD and GPX significantly and decreased MDA and NO levels in tissue homogenates of the cerebral ischemic rats compared with those in the negative control group (p < 0.05). Treatment with grifolin also attenuated the altered levels of inflammatory mediators (cytokines and NF-κB), caspase 3, and ATP levels in the tissue homogenate of cerebral ischemic rats (p < 0.05). The results of comet assay on the tissue homogenate suggest that treatment with grifolin reduced or prevented damage.Conclusions: The results show that treatment with grifolin protects against neuronal damage in acute cerebral ischemic rats via its anti-inflammatory and anti-oxidant properties.Keywords: Neuroprotection, Cerebral ischemia, Brain injury, DNA, Grifolin, Anti oxidan
Interactions in Aqueous Mixtures of Cationic Hydroxyethyl Cellulose and Different Anionic Bile Salts
publishedVersio
An energy-balanced heuristic for mobile sink scheduling in hybrid WSNs
Wireless sensor networks (WSNs) are integrated
as a pillar of collaborative Internet of Things (IoT)
technologies for the creation of pervasive smart environments.
Generally, IoT end nodes (or WSN sensors) can be
mobile or static. In this kind of hybrid WSNs, mobile sinks
move to predetermined sink locations to gather data
sensed by static sensors. Scheduling mobile sinks energyefficiently
while prolonging the network lifetime is a
challenge. To remedy this issue, we propose a three-phase
energy-balanced heuristic. Specifically, the network region
is first divided into grid cells with the same geo-graphical
size. These grid cells are assigned to clusters through an
algorithm inspired by the k-dimensional tree algorithm,
such that the energy consumption of each clus-ter is
similar when gathering data. These clusters are adjusted
by (de)allocating grid cells contained in these clusters,
while considering the energy consumption of sink
movement. Consequently, the energy to be consumed in
each cluster is approximately balanced considering the
energy consumption of both data gathering and sink movement.
Experimental evaluation shows that this technique
can generate an optimal grid cell division within a limited
time of iterations and prolong the network lifetime.This work was supported in part by the National Natural Science
Foundation of China under Grant 61379126, Grant 61401107, Grant
61572060, and Grant 61170296; in part by the Scientific Research
Foundation for Returned Scholars, Ministry of Education of China; and
in part by the Fundamental Research Funds for the Central Universities.
Paper no. TII-15-0703.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=9424hb2017Electrical, Electronic and Computer Engineerin
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