In this work, the crystal structure and hydrogen storage properties of V35Ti30Cr25Fe10, V35Ti30Cr25Mn10, V30Ti30Cr25Fe10Nb5 and V35Ti30Cr25Fe5Mn5 BCC-type high entropy alloys have been investigated. ...It was found that high entropy promotes the formation of BCC phase while large atomic difference (δ) has the opposite effect. Among the four alloys, the V35Ti30Cr25Mn10 alloy shows the highest hydrogen absorption capacity while the V35Ti30Cr26Fe5Mn5 alloy exhibits the highest reversible capacity. The cause of the loss of desorption capacity is mainly due to the high stability of the hydrides. The higher room-temperature desorption capacity of the V35Ti30Cr25Fe5Mn5 alloy is due to higher hydrogen desorption pressure. After pumping at 400 °C, the hydrides can return to the original BCC structure with only a small expansion in the cell volume.
Display omitted
•A series of high entropy alloys (HEAs) with BCC phase structure are prepared.•High ΔS promotes the formation of BCC phase while δ has the opposite effect.•HEAs with high BCC phase ratio show high H2 absorption and desorption capacity.•The cause of the loss of hydrogen desorption capacity is revealed.
In e-commerce, online product reviews significantly influence the purchase decisions of buyers and the marketing strategies employed by vendors. However, the abundance of reviews and their uneven ...quality make distinguishing between useful and useless reviews difficult for potential customers, thereby diminishing the benefits of online review systems. To address this problem, we develop a semi-supervised system called Online Review Quality Mining (ORQM). Embedded with independent component analysis and semi-supervised ensemble learning, ORQM exploits two opportunities: the improvement of classification performance through the use of a few labeled instances and numerous unlabeled instances, and the effectiveness of the social characteristics of e-commerce communities as identifiers of influential reviewers who write high-quality reviews. Three complementary experiments on datasets from Amazon.com show that ORQM exhibits remarkably higher performance in classifying reviews of different quality levels than do other well-accepted state-of-the-art text mining methods. The high performance of ORQM is also consistent and stable even under limited availability of labeled instances, thereby outperforming other baseline methods. The experiments also reveal that (1) the social features of reviewers are important in deriving better classification results; (2) classification results are affected by product type given the different purchase habits of consumers; and (3) reviews are contingent on the inherent nature of products, such as whether they are search goods or experience goods, and digital products or physical products, through which purchase decisions are influenced.
Display omitted
•We develop a semi-supervised system (ORQM) for estimating quality of online reviews.•ORQM includes independent component analysis and semi-supervised ensemble learning.•The system leverages unlabeled instances to improve its classification performance.•Social features contribute most to our system.•Classification results are affected by product type.
The development of photocatalysts based on covalent organic frameworks (COFs) is intriguing research due to their structural flexibility and tremendous catalytic sites. Herein we demonstrate a facile ...strategy to prepare composite materials of combined COFs and inorganic semiconductors with enhanced photocatalytic performances. A new composite photocatalyst (BiOBr/CTF-3D) integrated three-dimensional (3D) covalent triazine framework (CTF-3D) with two-dimensional BiOBr nanoflake was prepared via a simple coprecipitation method. The structural characterizations demonstrated that the amorphous CTF-3D was well modified on the surfaces of BiOBr. The photocatalytic activity of the BiOBr/CTF-3D composite was evaluated by the degradation of colorless antibiotic agents, tetracycline hydrochloride (TC) and ciprofloxacin (CIP), under visible light irradiation. When the mass percent of CTF-3D was 2%, the BiOBr/CTF-3D composite displayed the highest photocatalytic activity. The enhancement of photocatalytic performance was mainly derived from the enlarged optical adsorption range, the efficiently separated photogenerated electron–hole pairs, and the accelerated adsorption and transfer of antibiotic molecules, in the synergistically facilitating photocatalytic process. In addition, a possible photocatalytic mechanism for degrading TC by BiOBr/CTF-3D-2% was tentatively proposed. This work opens up a new strategy to improve the photocatalytic activity of traditional inorganic photocatalysts by modification with COFs materials for solving the pollution of living ecosystems.
Abstract
Improving the water use efficiency in agriculture is an important way to solve the problem of water shortage in agricultural areas and to improve the efficiency of water resource ...utilization. An evaluation indicator system of regional agricultural water use efficiency was constructed using data from 13 cities in Heilongjiang Province from 2013 to 2015. In addition, the comprehensive ranking of agricultural water use efficiency in each year was obtained by using an iterative combination method to correct the evaluation of individual models, including the analytic hierarchy process), matter element model and projection pursuit model (PPM). The results showed that the agricultural water use efficiency in Heilongjiang Province exhibited some regional differences in the 3 years evaluated spatially. And then, factors that influenced agricultural water use efficiency were analysed according to various criteria, and the rankings of cities and strategies were proposed to improve the agricultural water use efficiency according to this analysis. The results of the present study will have important theoretical and practical significance for guiding the scientific and rational formulation of agricultural water use strategies and improving the efficiency of agricultural water use in Heilongjiang Province.
Fast diffusion rate of ions and sufficiently exposed active sites are important for catalysts. As a superior but rarely studied Fenton‐type catalyst, unsatisfactory ion diffusion rate of manganese ...silicate is the exact obstacle for improving its catalytic activity. Here, hierarchical manganese silicate hollow nanotubes (MnSNTs) assembled by tunable secondary structures are precisely fabricated by an efficient hydrothermal method and systematically investigated as Fenton‐type catalysts for the first time. The open end and thin mesoporous walls of the hollow nanotubes help shorten the diffusion pathway of ions and enhance the mass transport. Moreover, the numerous standing small nanosheets endow MnSNTs with higher specific surface area and larger pore volume than the large nanosheets and nanoparticles, and thus expose more active sites for adsorption and catalytic decomposition. MnSNTs are highly efficient in adsorption and catalytic decomposition of cationic dyes with an excellent recycling stability. About 98.1% of methylene blue is catalytically decomposed in 45 min at an ambient temperature of 25 °C. When the temperature increases to 60 °C, only 2 min are required, with a 530% higher kinetic constant than reported.
Hierarchical manganese silicate hollow nanotubes assembled by tunable secondary structures are fabricated and systematically investigated as Fenton‐type catalysts. About 98.1% of methylene blue is decomposed in 45 min at 25 °C. When the temperature increases to 60 °C, only 2 min are required, with a 530% higher kinetic constant than reported.
The role of hydrogen sulphide (H2S) in angiogenesis has been widely demonstrated. Vascular endothelial growth factor (VEGF) plays an important role in H2S‐induced angiogenesis. H2S promotes ...angiogenesis by upregulating VEGF via pro‐angiogenic signal transduction. The involved signalling pathways include the mitogen‐activated protein kinase pathway, phosphoinositide‐3 kinase pathway, nitric oxide (NO) synthase/NO pathway, signal transducer and activator of transcription 3 (STAT3) pathway, and adenosine triphosphate (ATP)‐sensitive potassium (KATP) channels. H2S has been shown to contribute to tumour angiogenesis, diabetic wound healing, angiogenesis in cardiac and cerebral ischaemic tissues, and physiological angiogenesis during the menstrual cycle and pregnancy. Furthermore, H2S can exert an anti‐angiogenic effect by inactivating Wnt/β‐catenin signalling or blocking the STAT3 pathway in tumours. Therefore, H2S plays a double‐edged sword role in the process of angiogenesis. The regulation of H2S production is a promising therapeutic approach for angiogenesis‐associated diseases. Novel H2S donors and/or inhibitors can be developed in the treatment of angiogenesis‐dependent diseases.
Hydrogen sulphide and nitric oxide interact and depend on each other to jointly regulate angiogenesis.
Abstract
We present a study on investigating the propagation characteristics of umbral oscillations in sunspots. In sunspot 1 (located in NOAA AR 12127) with four umbrae, the analysis shows that the ...oscillations in different umbrae are correlated. The weak correlation (<20%) is attributed to the propagation of umbral oscillations across the umbral boundary to its adjacent umbra in the horizontal direction. We speculate that oscillations in two of the umbrae have a common origin in the sub-photosphere, resulting in a stronger correlation (>30%). Additionally, utilizing the TiO (photosphere), H
α
(chromosphere) images provided by BBSO/GST, and the 304 Å (upper chromosphere and lower transition region), 171 Å (upper transition region), 193 Å (corona), and 211 Å (active region corona) images acquired by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO), we analyze the vertical propagation of oscillations in the sunspot umbra. Multi-channel observation shows that the umbral oscillations observed in the lower atmosphere of sunspot 1 cannot be detected in the upper atmosphere. However, in sunspot 2 (located in NOAA AR 12132), oscillations in the lower atmosphere can propagate to the upper atmosphere. Using photospheric magnetic field data provided by the Helioseismic and Magnetic Imager on board SDO, potential field extrapolation of the magnetic field for the two sunspots shows that open magnetic field structures allow sunspot oscillations to propagate to higher heights, while closed magnetic field structures do not.
The pyrolysis of metal-organic frameworks has emerged as a promising route to synthesize metal oxides with diverse phase compositions, morphologies, sizes and surface areas. The ...BiOBr/Bi24O31Br10/TiO2 (BBT) heterostructures have been achieved for the first time by calcining BiOBr/MIL-125(Ti) composite at 500°C in air. The BBT-2 composite exhibited the highest photocatalytic performance for degradation of RhB under visible light irradiation. The enhanced photocatalytic activity is attributed to narrower band-gaps and synergistic effect originating from the well-aligned straddling band-structures between BiOBr, Bi24O31Br10 and TiO2, also result in an faster interfacial charge transfer during the photocatalytic reaction. This work could be conductive to the design of heterostructured photocatalysts contained metal oxide by pyrolytic conversion of metal-organic frameworks for significantly improved photocatalytic performance.
A novel BiOBr/Bi24O31Br10/TiO2 heterostructure was achieved by calcining BiOBr/MIL-125(Ti) composite and exhibited the photocatalytic performance for degradation of RhB. Display omitted
•A novel BiOBr/Bi24O31Br10/TiO2 heterostructure was achieved by calcining BiOBr/MIL-125(Ti) composite.•The heterostructure exhibited the photocatalytic performance for degradation of RhB.•The enhanced photocatalytic activity is attributed to synergistic effect between BiOBr, Bi24O31Br10 and TiO2.•This work could be conductive to the design of heterostructured photocatalysts by pyrolytic conversion of MOF.
To improve photocatalytic activity of 2D BiOBr nanosheets, Bi2S3 nanoparticles were introduced to fabricate the hybrid composite using co-precipitation method. The Bi2S3 loading 15 wt% amount of ...as-prepared composite shows the optimal visible light-driven photocatalytic activity for the degradation of Rhodamine B (RhB), tetracycline hydrochloride (TC) and ciprofloxacin (CIP). Radicals trapping experiments are further conducted to detect the reactive active species generated during the irradiation of BiOBr/Bi2S3-15 photocatalyst. It demonstrated that h+ and ∙O2− play the key role in photocatalytic degradation of pollutants. Photocurrent response, EIS and PL spectra reveal that the enhanced photocatalytic performance of BiOBr/Bi2S3 hybrid material shows higher separation efficiency of the photo-generated electron–holes pairs.
The hybrid material combined Bi2S3 nanoparticles with BiOBr nanosheets shows the enhanced visible light-driven photocatalytic activity for the degradation of RhB, TC and CIP. Display omitted
•The Bi2S3 nanoparticles and BiOBr nanosheets were successfully fabricated together.•The hybrid material shows the enhanced visible light-driven photocatalytic activity.•The hybrid material shows higher separation efficiency of photo-generated electron–holes pairs.•The h+ and ∙O2− play the key role in photocatalytic degradation of pollutants.
PDF
