Microwave assisted heterogeneous catalysis: effects of varying oxygen concentrations on the oxidative coupling of methane

The oxidative coupling of methane was investigated over alumina supported La2O3/CeO2 catalysts under microwave dielectric heating conditions at different oxygen concentrations. It was observed that, at a given temperature using microwave heating, selectivities for both ethane and ethylene were notably higher when oxygen was absent than that in oxygen/methane mixtures. The differences were attributed to the localised heating of microwave radiation resulting in temperature inhomogeneity in the catalyst bed. A simplified model was used to estimate the temperature inhomogeneity; the temperature at the centre of the catalyst bed was 85 °C greater than that at the periphery when the catalyst was heated by microwaves in a gas mixture with an oxygen concentration of 12.5% (v/v), and the temperature difference was estimated to be 168 °C in the absence of oxygen

New Terms for the Compact Form of Electroweak Chiral Lagrangian

The compact form of the electroweak chiral Lagrangian is a reformulation of its original form and is expressed in terms of chiral rotated electroweak gauge fields, which is crucial for relating the information of underlying theories to the coefficients of the low-energy effective Lagrangian. However the compact form obtained in previous works is not complete. In this letter we add several new chiral invariant terms to it and discuss the contributions of these terms to the original electroweak chiral Lagrangian.Comment: 3 pages, references adde

Low-loss narrowband filtering switch based on coaxial resonators

© 2013 IEEE. In this paper, a narrowband filtering switch with low loss and high selectivity is presented based on coaxial resonators for the first time. PIN diodes mounted on the printed circuit boards are embedded into a coaxial filter to enable ON and OFF states. In the ON-state, the PIN diodes are turned OFF, which do not introduce the loss and affect the linearity. Two transmission zeros are generated by a novel feeding structure, which improves the skirt selectivity. In the OFF-state, the PIN diodes are turned on. Then, lumped capacitors are loaded to the coaxial resonators so that the resonant frequencies of the resonators are changed. The passband at the operating frequency cannot be formed, resulting in high isolation. For demonstration, the coaxial-resonator-based filtering switch is designed and fabricated. Good agreement between simulated and measured results verifies the proposed ideas. Comparison with other reported filtering switches is given. The proposed filtering switch shows the advantages of high Q-factor, relatively compact size, and wide stopband responses, which is attractive in wireless systems

Density functional theory studies of hydrogen bonding vibrations in sI gas hydrates

Abstract To analyze the vibrational modes of water and methane in structure I gas hydrates, we constructed a 178-atom supercell with two small cages of type 512 and six large cages of type 51262. We applied the density functional theory method to simulate the vibrational spectrum and normal modes of methane hydrates. In accord with our previous studies, we confirmed that two groups of hydrogen bond (H-bond) peaks (at around 291 and 210 cm−1) in the translational bands come from two kinds of intermolecular H-bond vibrational modes. This is the first investigation of H-bond vibrations in methane hydrates. The partial modes of CH4 were extracted. We found that the CH4 phonons in the translational region are below 180 cm−1 so that the influence of methane on the H-bond is insignificant. We proposed a new method to decompose gas hydrates via direct application of terahertz radiation to the H-bonds. Herein, we confirmed that CH4 molecules do not absorb this energy.</jats:p

Promotion of ganoderic acid production in Ganoderma sinense by the addtion of an ether extract from Eupolyphaga sinensis, a medicinal insect

To screen stimulators from Chinese medicinal insects for mycelial growth and ganoderic acid (GA) production by Ganoderma sinense, the fungus was inoculated into the media with and without supplementation of a medicinal insect extract. The results show that all the water and ether extracts from the medicinal insects had no significant stimulatory effect on the biomass production (P &gt; 0.05), and the extracts of Hydrotrechus remigator and Mylabris phalerata significantly inhibited the mycelial growth. However, the ether extract of Eupolyphaga sinensis at a concentration of 60 mgL-1 led to a significant increase in GA concentration from 187.6 ± 8.32 to 251.3 ± 11.27 mgL-1 (P &lt; 0.01). Analysis of fermentation kinetics of G. sinense suggests that glucose concentration in the E. sinensis extract treatment group decreased more quickly as compared to the control group in the last 4 days of fermentation process, while the GA biosynthesis was promoted at the same period. However, the culture pH profile was not affected by the addition of the ether extract of E. sinensis.Key words: Medicinal fungus, Ganoderma sinense, submerged fermentation, Eupolyphaga sinensis, ganoderic acid

Self-concept of gifted children aged 9 to 13 years old

Ninety-four gifted children and 200 nongifted children (aged 9 to 13 years old) were involved in the present study. Their self-concept was assessed by the Revised Song-Hattie Self-Concept Inventory (Zhou &amp; He, 1996). Academic self-concepts pertaining to abilities, school achievements, and grade concepts and nonacademic self-concepts pertaining to family, peers, body, and self-confidence concepts, as well as self-concept in general, were considered in the present study. The findings indicated that the development of self-concept in gifted children was different from that of nongifted children.Specifically, the self-concept scores in general of nongifted children increased from 11 to 13 years old, while those of gifted children decreased for the same age period. Both academic and nonacademic self-concepts are discussed in the present study

Band structure engineering in (Bi1-xSbx)2Te3 ternary topological insulators

Three-dimensional (3D) topological insulators (TI) are novel quantum materials with insulating bulk and topologically protected metallic surfaces with Dirac-like band structure. The spin-helical Dirac surface states are expected to host exotic topological quantum effects and find applications in spintronics and quantum computation. The experimental realization of these ideas requires fabrication of versatile devices based on bulk-insulating TIs with tunable surface states. The main challenge facing the current TI materials exemplified by Bi2Se3 and Bi2Te3 is the significant bulk conduction, which remains unsolved despite extensive efforts involving nanostructuring, chemical doping and electrical gating. Here we report a novel approach for engineering the band structure of TIs by molecular beam epitaxy (MBE) growth of (Bi1-xSbx)2Te3 ternary compounds. Angle-resolved photoemission spectroscopy (ARPES) and transport measurements show that the topological surface states exist over the entire composition range of (Bi1-xSbx)2Te3 (x = 0 to 1), indicating the robustness of bulk Z2 topology. Most remarkably, the systematic band engineering leads to ideal TIs with truly insulating bulk and tunable surface state across the Dirac point that behave like one quarter of graphene. This work demonstrates a new route to achieving intrinsic quantum transport of the topological surface states and designing conceptually new TI devices with well-established semiconductor technology.Comment: Minor changes in title, text and figures. Supplementary information adde

A coliform-targeted metagenomic method facilitating human exposure estimates to Escherichia coli-borne antibiotic resistance genes.

This is the author accepted manuscript. The final version is available from Oxford University Press via the DOI in this record.Background: Antimicrobial resistance and the spread of antibiotic resistance genes (ARGs) pose a threat to human health. Community-acquired infections resistant to treatment with first-line antibiotics are increasing, and there are few studies investigating environmental exposures and transmission. Aim: Our objective is to develop a novel targeted metagenomic method to quantify the abundance and diversity of ARGs in a faecal indicator bacterium, and to estimate human exposure to resistant bacteria in a natural environment. Approach: Sequence data from Escherichia coli metagenomes from 13 bathing waters in England were analysed using the ARGs Online Analysis Pipeline to estimate the abundance and diversity of resistance determinants borne by this indicator bacterium. These data were averaged over the 13 sites and used along with data on the levels of E. coli in English bathing waters in 2016 and estimates of the volume of water that water users typically ingest in an average session of their chosen activityto quantify the numbers of ARGs that water users ingest. Findings: Escherichia coli in coastal bathing waters were found to harbour on average 1.24 ARGs per cell. Approximately 2.5 million water sports sessions occurred in England in 2016 that resulted in water users ingesting at least 100 E. coli-borne ARGs.This work was supported by the University of Exeter and the Chinese University of Hong Kong

Atomic Layer Deposition of ZnO on Multi-walled Carbon Nanotubes and Its Use for Synthesis of CNT-ZnO Heterostructures.

In this article, direct coating of ZnO on PECVD-grown multi-walled carbon nanotubes (MWCNTs) is achieved using atomic layer deposition (ALD). Transmission electron microscopy investigation shows that the deposited ZnO shell is continuous and uniform, in contrast to the previously reported particle morphology. The ZnO layer has a good crystalline quality as indicated by Raman and photoluminescence (PL) measurements. We also show that such ZnO layer can be used as seed layer for subsequent hydrothermal growth of ZnO nanorods, resulting in branched CNT-inorganic hybrid nanostructures. Potentially, this method can also apply to the fabrication of ZnO-based hybrid nanostructures on other carbon nanomaterials.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

On the discovery of continuous truth: a semi-supervised approach with partial ground truths

In many applications, the information regarding to the same object can be collected from multiple sources. However, these multi-source data are not reported consistently. In the light of this challenge, truth discovery is emerged to identify truth for each object from multi-source data. Most existing truth discovery methods assume that ground truths are completely unknown, and they focus on the exploration of unsupervised approaches to jointly estimate object truths and source reliabilities. However, in many real world applications, a set of ground truths could be partially available. In this paper, we propose a semi-supervised truth discovery framework to estimate continuous object truths. With the help of ground truths, even a small amount, the accuracy of truth discovery can be improved. We formulate the semi-supervised truth discovery problem as an optimization task where object truths and source reliabilities are modeled as variables. The ground truths are modeled as a regularization term and its contribution to the source weight estimation can be controlled by a parameter. The experiments show that the proposed method is more accurate and efficient than the existing truth discovery methods