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To investigate the delayed release characteristics of CO gas in the initial stage of the low-temperature oxidation of coal, closed oxygen consumption experiments were conducted on coal samples taken from the Hongqingliang coal mine, and the corresponding relationship between the CO concentration and time in the initial stage of the experimental reaction was analyzed. A physical adsorption model of the macromolecules in coal for O2 and CO was established, and the difference in the competitive adsorption between the CO and O2 gas molecules on the coal surface was analyzed from a microscopic perspective using the grand canonical ensemble Monte Carlo simulation. The results showed a delayed CO release phenomenon in the initial stage of the reaction in all the experiments, and the delayed time of CO release was negatively correlated with the temperature; the relationship between the adsorption amounts of CO and O2 in the molecular structure model of coal was CO > O2. With increasing temperature, the adsorption capacity of the two gases decreased. Under the same conditions, there was competitive adsorption of the mixture of CO and O2 by coal, with the adsorption capacity of CO being much greater than that of O2. The adsorption of CO gas molecules by coal played an inhibitory role in the release of CO gas in the initial oxidation stage. The study results are expected to help understand the CO generation characteristics in the goaf of coal seam working faces and thus prevent coal mine disasters. [ABSTRACT FROM AUTHOR]

This paper examines whether Chinese manufacturing firms survive longer if they innovate. More particularly, it focuses on whether R&D has a greater effect on firm survival than new product innovations. It compares dichotomous and continuous measures of R&D and innovation output, various duration models, heterogeneity in the effects of innovation depending on the industrial environment, and it examines whether risk modifies the effect of innovation on the hazard rate. The analysis is based on data from the National Bureau of Statistics of China, including over 100,000 firms in each year over the period 1999–2006 from all provinces and manufacturing industries in China. It is found that both R&D and product innovation, be it in terms of incidence or intensities, increase the chance of firm survival. As opposed to previous studies, the results indicate that R&D has a greater marginal effect on survival than innovation output and that various measures of risk actually increase the effect of R&D/innovation on survival. [ABSTRACT FROM AUTHOR]

In this paper, based on the exponential integrator, a new Jacobi-type iteration method is proposed for solving linear system A x = b . The traditional Jacobi iteration method can be viewed as a special case of the new method. The convergence and two comparison theorems of the new Jacobi-type method are established for linear system with different type of coefficient matrices. The convergence of the traditional Jacobi iteration method follows immediately from these results. It is shown that for the linear system with coefficient matrix that is M-matrix or nonnegative matrix, the new method is convergent. Under suitable conditions, the spectral radius of iteration matrix for new method is much smaller than traditional Jacobi method for the case of nonnegative coefficient matrix. Numerical experiments are carried out to show the effectiveness of the new method when dealing with the nonnegative matrix system. [ABSTRACT FROM AUTHOR]

In this work, a metallic probe with a sharp tip and two half-circular nanostructures on its base is introduced and investigated. The proposed design aims at improving the detection performance of a probe for scattering scanning near-field optical microscopy in terms of enhanced signal-to-noise ratio. Under the premise of processing feasibility, the structure of the probe is designed and optimized with three-dimensional finite-difference time-domain method. And then the performance and optical property of the probe are theoretically investigated and experimentally demonstrated using a scanning near-field optical microscope with aperture probe. It is indicated that a tightly confined optical field with significantly reduced far-field background can be achieved at the tip apex of the probe. [ABSTRACT FROM AUTHOR]

To isolate the focused near-field excitation at the probe apex from the contribution of the far-field illumination, a novel metallic probe which consisted of a taper cylinder tip and a couple of curved nanoslits on the probe base was designed. The local field enhancement and confinement performance varying with the structure parameters of the probe and the type of substrates were investigated by means of finite-difference time-domain simulation. With the optimized probe working in probe-substrate coupling mode, the local electric field intensity at the probe apex can be effectively enhanced by more than 500 times compared to the incident field. [ABSTRACT FROM AUTHOR]

Raman spectroscopy is a powerful technique in chemical information characterization. However, this spectral method is subject to two obstacles in nano-material detection. One is diffraction limited spatial resolution, and the other is its inherent small Raman cross section and weak signaling. To resolve these problems, a new approach has been developed, denoted as tip-enhanced Raman spectroscopy (TERS). TERS is capable of high-resolution and high-sensitivity detection and demonstrated to be a promising spectroscopic and micro-topographic method to characterize nano-materials and nanostructures. In this paper, the principle and experimental system of TERS are discussed. The latest application of TERS in molecule detection, biological specimen identification, nanao-material characterization, and semi-conductor material determination with some specific experimental examples are presented. [ABSTRACT FROM AUTHOR]

Background and aims: Mineral cycling plays a critical role in wetland ecosystem functions and can be affected by environmental changes, such as CO enrichment. Learning the responses of mineral bioavailability in wetlands to elevated CO under field conditions will provide enormous benefits to the assessment of climate change impacts on wetland ecosystems. Methods: A free-air CO enrichment (FACE) experiment was conducted in a rice ecosystem in Jiangsu, China, with two nitrogen (N) application levels. Responses of K, Ca, Mg, Fe, Mn, Zn, and Si in this ecosystem were investigated in situ. Results: CO enrichment increased rice biomass Ca, Mg, Fe, Mn, Zn, and Si regardless of N application levels. Dissolved mineral contents in surface water and available mineral contents in the 0-15 cm soil layer were higher in the FACE plots than in the ambient under both N levels. Elevated CO reduced the pH values of the 0-15 cm soil layer and surface water, but increased the cation exchange capacity of the soil layer. The effects of N treatment and its interaction with CO enrichment were mostly insignificant on the above parameters. Conclusions: Our results indicate that CO enrichment can enhance mineral bioavailability in a rice ecosystem through accelerating mineral transformation from the bio-inactive reservoirs to the bioactive ones. [ABSTRACT FROM AUTHOR]

Scanning near-field optical microscopy (SNOM) is an ideal experimental measuring system in nano-optical measurements and characterizations. Besides microscopy with resolution beyond the diffraction limit, spectroscope with nanometer resolution and other instruments with novel performances have been indispensable for researches in nano-optics and nanophotonics. This paper reviews the developing history of near-field optical (NFO) measuring method and foresees its prospects in future. The development of NFO measurements has gone through four stages, including optical imaging with super resolution, near-field spectroscopy, measurements of nanooptical parameters, and detections of near-field interactions. For every stage, research objectives, technological properties and application fields are discussed. [ABSTRACT FROM AUTHOR]

The photovoltaic performance of axial and radial pin junction GaAs nanocone array solar cells is investigated. Compared with the cylinder nanowire arrays, the nanocone arrays not only improve the whole optical absorption but more importantly enhance the effective absorption (absorption in the depletion region). The enhanced effective absorption is attributed to the downward shift and extension of the absorption region induced by the shrinking top, which dramatically suppresses the absorption loss in the high-doped top region and enhances the absorption in the depletion region. The highest conversion efficiencies for axial and radial GaAs nanocone solar cells are 20.1% and 17.4%, obtained at a slope angle of 5° and 6°, respectively, both of which are much higher than their cylinder nanowire counterparts. The nanocone structures are promising candidates for high-efficiency solar cells. [ABSTRACT FROM AUTHOR]