•A multi-phase composite anode is developed through a one-step reduction of La0.65Li0.05Sr0.3Fe0.8Ni0.2O3-δ.•The FeNi alloy nanoparticles and decorated carbonate endow the anode with excellent ...catalytic activity and coke-resistance.•The mechanism of carbon tolerance enhancement by in-situ formation of carbonate on the anode surface is proposed.•The high performance of the composite anode in SOFC using CO and C2H6 as fuel is demonstrated.
Solid oxide fuel cells (SOFCs) are a kind of clean and efficient device to convert chemical energy in fuels into electricity. However, since anodes with high catalytic activity and carbon tolerance are still underdeveloped, the consequent serious performance degradation of the cells under operational conditions significantly confines their commercial applications. Here we propose a new strategy to remove carbon deposition by in-situ formation of alkali metal carbonate on the anode surface. A multi-phase composite anode, which is composed of an orthorhombic single perovskite main phase, a Ruddlesden-Popper (RP) layered perovskite second phase, and an in-situ exsolved FeNi alloy minor phase, is developed by one-step reduction of La0.65Li0.05Sr0.3Fe0.8Ni0.2O3-δ (LLSFN0.05) at a high temperature. The deficiencies of the RP phase and A-site caused by Li dopant would increase oxygen bulk diffusion, and FeNi nanoparticles would boost the catalytic activity. Moreover, when dealing with carbon fuel, lithium carbonate can be synthesized on the anode surface, serving as a good oxygen ion conductor and an efficient catalyst for coke removal by gasification. A single cell with our reduced LLSFN0.05 anode exhibited maximum power densities of 596, 467, and 424 mW cm−2 at 750 ℃ with H2, CO, and wet C2H6 as the fuel, respectively. In addition, the cells could have a long-term stable operation for over 80 h using CO as the fuel at 200 mA cm−2. This study provides a new material design strategy to develop a highly active and coke-resistant anode.
Abstract
Reverberation mapping (RM) is a widely used method for probing the physics of broad-line regions (BLRs) in active galactic nuclei (AGNs). There is increasing preliminary evidence that the RM ...behaviors of broad emission lines are influenced by BLR densities; however, the influences have not been investigated systematically from a theoretical perspective. In this paper, we adopt a locally optimally emitting cloud model and use CLOUDY to obtain the one-dimensional transfer functions of the prominent UV and optical emission lines for different BLR densities. We find that the influences of BLR densities to RM behaviors mainly have three aspects. First, rarefied BLRs (with low gas densities) may show anomalous responses in RM observations. Their emission-line light curves inversely respond to the variations in continuum light curves, which may have been observed in some UV RM campaigns. Second, the different BLR densities in AGNs may result in correlations between the time lags and equivalent widths of emission lines, and may contribute to the scatters of the radius–luminosity relationships. Third, the variations in BLR densities may explain the changes in time lags in individual objects for different years. Some weak emission-line quasars are probably extreme cases of rarefied BLRs. We predict that their RM observations may show anomalous responses.
•Pyrolysis and acetic acid modification synergistically enhance the kinetics of coal electrochemical reaction.•Nano Ag-infiltrated anode shows lower resistance and improved kinetics.•An HDCFC using ...the modified char as fuel demonstrates a maximum power density of 403 mW cm−2 at 750 °C.•The HDCFC can achieve a high fuel conversion and Faradic efficiency.
Hybrid direct coal fuel cells (HDCFCs) have the potential to convert coal into electrical power in a clean and efficient manner. However, the related coal pretreatment method and the anode activity should both be improved, before the HDCFCs could match the performance of other direct coal fuel cells such as those based on solid oxide. In this study, we pyrolysed bituminous coal at 800 °C followed by modification with acetic acid, in order to remove organic volatiles and reintroduce surface functional groups, respectively. The result was a modified char that was highly pure and with high oxidation activity. Further, the Ni-(Y2O3)0.08(ZrO2)0.92 anode was infiltrated with Ag nanoparticles as an effective catalyst to promote the electro-oxidation of carbon. Under optimised conditions, the HDCFC with Ag-infiltrated anode and modified char as fuel demonstrated a maximum power density (403 mW cm−2 at 750 °C) that exceeds previous results for coal-based fuels. The cell also showed stable operation for 14 h, with a fuel conversion of 97.22% and Faradic efficiency of 61.06% using 0.4 g modified char.
Background:
Medical students are affected by high levels of general anxiety disorder. However, few studies have specifically focused on the applicability of universal anxiety screening tools in this ...sample. This study was aimed to evaluate the psychometric property of the 7-item Generalized Anxiety Disorder Scale (GAD-7) among Chinese medical university students.
Methods:
A questionnaire survey was conducted among 1,021 medical postgraduates from six polyclinic hospitals. Internal consistency and convergent validity of the GAD-7 were evaluated. Factor analyses were used to test the construct validity of the scale. An item response theory (IRT) framework was used to estimate the parameters of each item. Multi-group confirmatory analyses and differential item function analyses were used to evaluate the measurement equivalence of the GAD-7 across age, gender, educational status, and residence.
Results:
Cronbach's α coefficient was 0.93 and the intraclass correlation coefficients ranged from 0.71 to 0.87. The GAD-7 summed score was significantly correlated with measures of depression symptoms, perceived stress, sleep disorders, and life satisfaction. Parallel analysis and confirmatory factor analysis supported the one-factor structure of the GAD-7. Seven items showed appropriate discrimination and difficulty parameters. The GAD-7 showed good measurement equivalence across demographic characteristics. The total test information of the scale was 22.85, but the test information within the range of mild symptoms was relatively low.
Conclusions:
The GAD-7 has good reliability, validity, and measurement invariance among Chinese medical postgraduate students, but its measurement precision for mild anxiety symptoms is insufficient.
We presented an antibiotic-loaded γ-cyclodextrin metal-organic framework that delivered antibiotics suitable for the treatment of bacterial infections. The γ-cyclodextrin metal-organic framework was ...developed using γ-cyclodextrin and potassium ion via the ultrasonic method. The antibiotic (florfenicol and enrofloxacin) was primarily encapsulated into the pore structures of γ-CD-MOF, which allowed the sustained release of antibiotics over an extended period of time in vitro and in vivo. Notably, antibiotics-loaded γ-CD-MOF showed much superior activity against bacteria than free antibiotics (lower MIC value) and displayed better long-lasting activity (longer antibacterial time). The antibiotics-loaded γ-CD-MOF showed nontoxic and perfect biocompatibility to mammalian cells and tissues both in vitro and in vivo. These materials thus represent a novel drug-delivery device suitable for antibiotic therapy. This research is of great significance for reducing the generation of bacterial resistance and providing new ideas for the application of γ-CD-MOF.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The field production profile over the yearly horizon is planned for a balance between economy, security, and sustainability of energy. An optimal drilling schedule is required to achieve the planned ...production profile with minimized drilling frequency and summation. In this study, we treat each possible production process of each well as a dependent time series and the basic unit. Then we ensemble all of them into a tensor. Based on formulated tensor calculation and Lasso regularization, a linear mathematical optimization model for well drilling schedule was developed. The model is aimed at minimizing production profile error while optimizing drilling frequency and summation. Although the model proposed in this work requires more memory consumption to be solved using a computer, it is assured as a linear model and could be numerically globally solved in a stable and efficient way using gradient descent, avoiding complex nonlinear programming problems. Main input data and parameters involved in the model are analyzed in detail to understand the effects of different production parameters on the drilling schedule and production profile. The proposed model in this work can evaluate the manual drilling schedule and automatically generate an optimized drilling schedule for the gas field, significantly reducing development plan formulation time.
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Curcumin (Cur) is a strong natural antioxidant, who can prevent multiple diseases such as anti-cancer, anti-inflammatory, have a resistance to alzheimer's disease and various ...malignant diseases. But it has poor oral bioavailability due to its poor aqueous solubility, as well as instability. While its novel derivatives (CB and FE), showed better anti-tumor activity, better anti-oxidant activity and better stability than the original drug (Cur). The aim of this study was to study the intestinal transport of Cur, CB and FE using an in vitro Caco-2 cell monolayer model. The results showed that Cur had a lower permeability coefficient (1.13×10−6±0.11×10−6cm/s) for apical-to-basolated (AP-BL) transport at 25μM, while the transport rate for AP to BL flux of CB (3.18×10−6±0.31×10−6cm/s) and FE (5.28×10−6±0.83×10−6cm/s) were significantly greater than that of Cur. The efflux ratio (ER) value at the concentration of 25μM was 1.31 for Cur, 1.26 for CB and 1.33 for FE, suggesting there was no active efflux involved in the translocation across the Caco-2 cell monolayers for the three compounds. Furthermore, the transport flux of CB and FE was in a concentration dependent manner, suggesting the intestinal transport mechanism in them was passive transport. In summary, the results demonstrated that both the intestinal permeability of CB and FE across Caco-2 cell monolayers was significantly improved compare to Cur. Thus they might show a higher oral bioavailability in vivo, and show the potential application in clinic or nutraceutical.
The measurement of turbulence is necessary to quantify the vertical, diapycnal transport of heat, water and substances influencing climate, nutrient supply and marine ecosystems. As specialist ...instrumentation and ship-time are required to conduct microstructure measurements to quantify turbulence intensity, there is a need for more inexpensive and easy measurement methods. This study demonstrated that the turbulent energy dissipation rate,
ε
, estimated from fast-response thermistors Fastip Probe model 07 (FP07) with the depth-average of a > 10 m depth interval well agreed with those from current shear probes to a range of 10
–11
W/kg (m
2
s
−3
) in the two casts of the most accurate and stable free-fall vertical microstructure profiler, VMP6000 in the Oyashio water. This range cannot be measured with velocity shear probes equipped in smaller profilers in which the lower limit of
ε
> O (10
–10
) W/kg. These results extend turbulence measurements using the FP07 to 10
–11
W/kg. They may be especially useful for turbulence observations in deep oceans where
ε
is generally weak (< 10
–10
W/kg). As FP07 are much less sensitive to instrument vibrations than current shear and may be attached to various observational platforms such as temperature-conductivity-depth (CTD) profilers and floats. The CTD-attached FP07 observations near the VMP6000 profiles demonstrated their capabilities in the
ε
range of 10
–11
–10
–8
W/kg by data screening using a
W
sd
>
0.1
(
W
-
0.3
)
criterion (1 s mean lowering rate
W
m/s and its standard deviation
W
sd
) under rough conditions where the cast-mean
W
sd
>
0.07 m/s and the standard deviation of
W
sd
in each cast
σ
>0.05 m/s.
Abstract
Strong iron lines are a common feature of the optical spectra of active galactic nuclei (AGNs) and quasars from
z
∼ 6−7 to the local universe, and Fe/Mg ratios do not show cosmic evolution. ...During active episodes, accretion disks surrounding supermassive black holes (SMBHs) inevitably form stars in the self-gravitating part, and these stars accrete with high accretion rates. In this paper, we investigate the population evolution of accretion-modified stars (AMSs) to produce iron and magnesium in AGNs. The AMSs, as a new type of star, are allowed to have any metallicity but without significant loss from stellar winds, since the winds are choked by the dense medium of the disks and return to the core stars. Mass functions of the AMS population show a pile-up or cutoff pile-up shape in top-heavy or top-dominant forms if the stellar winds are strong, consistent with the narrow range of supernovae (SNe) explosions driven by the known pair-instability. This provides an efficient way to produce metals. Meanwhile, SN explosions support an inflated disk as a dusty torus. Furthermore, the evolving top-heavy initial mass functions lead to bright luminosity in infrared bands in dusty regions. This contributes a new component in infrared bands, which is independent of the emissions from the central part of accretion disks, appearing as a long-term trending of the NIR continuum compared to optical variations. Moreover, the model can be further tested through reverberation mapping of emission lines, including LIGO/LISA detections of gravitational waves and signatures from spatially resolved observations of GRAVITY+/VLTI.
Existing fractured gas reservoir development techniques are mainly based on dual medium numerical-simulation models, which can, to a certain extent, effectively simulate natural fractures with high ...fracture density; however, these models have some limitations, particularly in terms of simulating the fracture morphology and distribution. Considering carbonate gas reservoirs with complex fractures, in this paper, we establish a numerical-simulation model of embedded discrete-fracture seepage in horizontal wells of carbonate gas reservoirs, in order to compare and study the development effect of carbonate gas reservoirs under different horizontal well fracture parameters. The fracture distribution and structure in carbonate gas reservoirs is obtained using an ant-tracking approach based on 3D seismic bodies, and a numerical-simulation model based on the embedded discrete-fractures model is solved using the open-source program MRST. We considered the following parameters: half fracture length, fracture permeability, and horizontal segment length. By changing the fracture parameters of horizontal wells and comparing the gas-production trends, technical optimization in gas reservoir development can be realized. The results show that the embedded discrete-fracture model can effectively solve the difficult problem of characterizing fluid seepage in fractures of different scale in carbonate gas reservoirs. Although gas production increases with increasing fracture length, fracture conductivity, horizontal section length, and natural fracture conductivity, the contributions of these parameters to gas well production capacity are greatly influenced by the natural fractures.
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