Quasiparticle scattering in two dimensional helical liquid

We study the quasiparticle interference (QPI) patterns caused by scattering off nonmagnetic, magnetic point impurities, and edge impurities, separately, in a two dimensional helical liquid, which describes the surface states of a topological insulator. The unique features associated with hexagonal warping effects are identified in the QPI patterns of charge density with nonmagnetic impurities and spin density with magnetic impurities. The symmetry properties of the QPI patterns can be used to determine the symmetry of microscopic models. The Friedel oscillation is calculated for edge impurities and the decay of the oscillation is not universal, strongly depending on Fermi energy. Some discrepancies between our theoretical results and current experimental observations are discussed.Comment: 12 pages, appendices added. Accepted for publication in Physical Review B (submitted, October 2009

Synthesis and optical properties of composite films from P3HT and sandwich-like Ag-C-Ag nanoparticles

This document is the Accepted Manuscript of the following article: Lingpeng Yan, Yamin Hao, Xiaoting Feng, Yongzhen Yang, Xuguang Liu, Yongkang Chen, and Bingshe Xu, ‘Synthesis and optical properties of composite films from P3HT and sandwich-like Ag–C–Ag nanoparticles’, RSC Advances, Vol. 5(97): 79860-79867, 2015, DOI: https://doi.org/10.1039/C5RA16854F. Content in the UH Research Archive is made available for personal research, educational, and non-commercial purposes only. Unless otherwise stated, all content is protected by copyright, and in the absence of an open license, permissions for further re-use should be sought from the publisher, the author, or other copyright holder.Sandwich-like Ag-C-Ag nanoparticles (Ag-C-Ag NPs) were synthesized under mild hydrothermal conditions in a one-step method. With this approach, Ag was not only encapsulated in the centre of an individual carbon nanosphere, but was also uniformly dispersed within the carbon matrix up to the sphere's shell. Then, poly(3-hexylthiophene):Ag-C-Ag NPs (P3HT:Ag-C-Ag NPs) composite films were prepared by a spin coating method with a chlorobenzene solution of Ag-C-Ag NPs and P3HT. Both morphology and microstructure of Ag-C-Ag NPs were investigated by field emission scanning electron microscopy and high resolution transmission electron microscopy. The possible formation mechanism was proposed. The results have indicated that the Ag-C-Ag NPs present many functional groups and their energy levels match with those of P3HT. It has been observed that an introduction of Ag-C-Ag NPs to P3HT can induce broad and high-absorbing spectra as well as great photoluminescence quenching of P3HT. It is evident that sandwich-like Ag-C-Ag NPs have a great potential to be a new acceptor material in photovoltaic devices.Peer reviewe

Social trust, interpersonal trust and self-rated health in China: a multi-level study

Background: Trust is important for health at both the individual and societal level. Previous research using Western concepts of trust has shown that a high level of trust in society can positively affect individuals’ health; however, it has been found that the concepts and culture of trust in China are different from those in Western countries and research on the relationship between trust and health in China is scarce. Method: The analyses use data from the national scale China General Social Survey (CGSS) on adults aged above 18 in 2005 and 2010. Two concepts of trust (“out-group” and “in-group” trust) are used to examine the relationship between trust and self-rated health in China. Multilevel logistical models are applied, examining the trust at the individual and societal level on individuals’ self-rated health.Results: In terms of interpersonal trust, both “out-group” and “in-group” trust are positively associated with good health in 2005 and 2010. At the societal level, the relationships between the two concepts of trust and health are different. In 2005, higher “out-group” social trust (derived from trust in strangers) is associated with better health; however, higher “in-group” social trust (derived from trust in most people) is associated with poor health in 2010. The cross-level interactions show that lower educated individuals (no education or only primary level), rural residents and those on lower incomes are the most affected groups in societies with higher “out-group” social trust; whereas people with lower levels of educational attainment, a lower income, and those who think that most people can be trusted are the most affected groups in societies with higher “in-group” social trust.Conclusion: High levels of interpersonal trust are of benefit to health. Higher “out-group” social trust is associated with better health; while higher “in-group” social trust is associated with poor health. Individuals with different levels of educational attainment are affected by trust differently

Picocyanobacteria and deep-ocean fluorescent dissolved organic matter share similar optical properties

Marine chromophoric dissolved organic matter (CDOM) and its related fluorescent components (FDOM), which are widely distributed but highly photobleached in the surface ocean, are critical in regulating light attenuation in the ocean. However, the origins of marine FDOM are still under investigation. Here we show that cultured picocyanobacteria, Synechococcus and Prochlorococcus, release FDOM that closely match the typical fluorescent signals found in oceanic environments. Picocyanobacterial FDOM also shows comparable apparent fluorescent quantum yields and undergoes similar photo-degradation behaviour when compared with deep-ocean FDOM, further strengthening the similarity between them. Ultrahigh-resolution mass spectrometry (MS) and nuclear magnetic resonance spectroscopy reveal abundant nitrogen-containing compounds in Synechococcus DOM, which may originate from degradation products of the fluorescent phycobilin pigments. Given the importance of picocyanobacteria in the global carbon cycle, our results indicate that picocyanobacteria are likely to be important sources of marine autochthonous FDOM, which may accumulate in the deep ocean

Exploitation contradictions concerning multi-energy resources among coal, gas, oil, and uranium: A case study in the ordos basin (Western North China Craton and Southern Side of Yinshan Mountains)

The particular “rich coal, meager oil, and deficient gas” energy structure of China determines its high degree of dependence on coal resources. After over 100 years of high-intensity mining activities in Northeast China, East Region, and the Southern Region, coal mining in these areas is facing a series of serious problems, which force China’s energy exploitation map to be rewritten. New energy bases will move to the western and northern regions in the next few years. However, overlapping phenomena of multiple resources are frequently encountered. Previous exploitation mainly focused on coal mining, which destroys many mutualistic and accompanying resources, such as uranium, gas, and oil. Aiming at solving this unscientific development mode, this research presents a case study in the Ordos Basin, where uranium, coal, and gas/oil show a three-dimensional overlapping phenomenon along the vertical downward direction. The upper uranium and lower coal situation in this basin is remarkable; specifically, coal mining disturbs the overlaying aquifer, thus requiring the uranium to be leached first. The technical approach must be sufficiently reliable to avoid the leakage of radioactive elements in subsequent coal mining procedures. Hence, the unbalanced injection and extraction of uranium mining is used to completely eradicate the discharged emissions to the environment. The gas and oil are typically not extracted because of their deep occurrence strata and their overlapping phenomenon with coal seams. Use of the integrated coal and gas production method is recommended, and relevant fracturing methods to increase the gas migrating degree in the strata are also introduced. The results and recommendations in this study are applicable in some other areas with similarities

Sustainable composite super absorbents made from polysaccharides

Compared to traditional super absorbent polymers using raw materials from petrochemical industry, natural polymer absorbents are more favorable because they are sustainable and biodegradable. In this study, composite absorbents were developed by crosslinking carrageenan with sodium alginate using calcium chloride. Effect of composition on absorption was tested. Absorption was improved by increasing carrageenan content. The super absorbent exhibited the maximal swelling ratio of 13.1 g/g in 0.9% saline water in just 5 min. The maximal tensile strength was reached with a value of 12.8 MPa. Water contact angle revealed that carrageenan is more hydrophobic than sodium alginate. Presence of sulfate groups might be a key factor promoting absorption. The scanning electron microscopic images showed that the composite material had a structure with alginate arranged at the outside surface. These results demonstrate that a sustainable and biodegradable absorbent was successfully developed with a matrix of properties for potential application in diapers

Unraveling the Complexity of Dwarf Galaxy Dynamics: A Study of Binary Orbital Motions

We investigate the impact of binary orbital motions on the dynamical modeling of dwarf galaxies with intrinsic line-of-sight velocity dispersions ( σvr ) of 1–9 km s−1. Using dwarf galaxies from the auriga level-2 and level-3 simulations, we apply the Jeans Anisotropic Multi-Gaussian Expansion modeling to tracer stars before and after including binaries to recover the dynamical masses. The recovered total masses within the half-mass radius of tracers, M(< r half), are always inflated due to binary motions, with greater inflations occurring for smaller σvr . However, many dwarf galaxies experience central density deflated due to binary motions, with little dependence on σvr . This is due to the negative radial gradients in the velocity dispersion profiles, with the fractional inflation in σvr due to binaries more significant in outskirts. An extreme binary fraction of 70% can lead to central density deflation of up to 10%–20% at 3 km s−1 < σvr < 8 km s−1, with M( < r half) inflated by 4% at 9 km s−1 and up to 15% at 3 km s−1. A lower binary fraction of 36% leads to similar deflations, with the inflations decreasing to approximately 10% at 3 km s−1 and becoming statistically insignificant. The choice of binary orbit distribution models does not result in significant differences, and observational errors tend to slightly weaken the deflations in the recovered central density. Two observations separated by 1 yr to exclude binaries lead to almost zero inflations/deflations for a binary fraction of 36% over 3 km s−1 < σvr<9 km s−1. For σvr∼1 km s−1 to 3 km s−1, a binary fraction of 70% (36%) still results in 60% (30%) to 10% (1%) of inflations in M( < r half), even with two-epoch observation