265 research outputs found

    3-Methyl-2,6-dinitro-N-(3-pent­yl)-4-[(2,3,4-tri-O-acetyl-β-d-xylos­yl)amino­methyl]­aniline

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    In the title compound, C24H34N4O11, the hexopyranosyl ring adopts a chair conformation. The four substituents are in equatorial positions. The mol­ecule shows an intra­molecular N—H⋯O hydrogen bond

    Modulation of Field Emission Resonance on photodetachment of negative ions on surface

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    The interaction between the field emission resonance states and the photodetached electron in an electric field is studied by semiclassical theory. An analytical expression of the photodetachment cross section is derived in the framework. It is found that the Stark shifted image state modulates the photodetachment cross section by adding irregular staircase or smooth oscillation in the spectrum. When the photodetached electron is trapped in Stark shifted image potential well, the detachment spectrum displays an irregular staircase structure which corresponds to the modified Rydberg series. While the photodetached electron is not bound by the surface potential well, the cross secton contains only a smooth oscillation due to the reflection of electronic wave by the field or the surface.Comment: 30 pages, 6 figure

    Entrained Collective Rhythms of Multicellular Systems: Partial Impulsive Control Strategy

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    This paper is concerned with the study of entrained collective rhythms of multicellular systems by using partial impulsive control strategy. The objective is to design an impulsive controller based on only those partially available cell states, so that the entrained collective rhythms are guaranteed for the multicellular systems with cell-to-cell communication mechanism. By using the newly developed impulsive integrodifferential inequality, the sufficient conditions are derived to achieve the entrained collective rhythms of multicellular systems. A synthetic multicellular system with simulation results is finally given to illustrate the usefulness of the developed results

    Nonindustrial Family Forest Landowners' Stated Willingness-to-Participate in Forest Cooperatives in Southern China

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    Forest landowner cooperatives have emerged as a formal institution capable of fostering professional forest management. There are many reasons to motivate participation in forest cooperatives. For instance, cooperatives could ease nonindustrial family forest landowners (NIFFLs) access to financial assistance and enhance market entrance opportunities. In China, various forms of forest cooperatives supported by government agencies are developing rapidly in an effort to facilitate forest management at a large scale. However, the development of forest cooperatives is still in its early stages. An understanding of NIFFLs' attitudes towards the development of cooperatives is instrumental for crafting policies and organizational structures that motivate landowners' participation. Three hundred and ten NIFFLs from Fujian and Jiangxi provinces in Southern China were interviewed to elicit their attitudes and willingness-to-participate in forest cooperatives. Logistic regression was used to evaluate landowner, household, forest resource, and institutional factors associated with NIFFLs' stated decision to participate in a forest cooperative. Results show that NIFFLs' stated willingness-to-participate in forest cooperatives was associated with demographic characteristics like education, forest-related income, size of forestland, and attitudes toward land tenure reform and cooperatives. This paper outlines suggestions on how to further develop forest cooperatives in Southern China

    Surface Chemical Modification of Multiwalled Carbon Nanotubes by a Wet-Mechanochemical Reaction

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    A wet-mechanochemical reaction for surface modification of multiwalled carbon nanotubes (CNTs) has been developed. In the treatment, CNTs reacted with potassium hydroxide in alcohol solvent at room temperature under mechanical milling. The results from Fourier transmission infrared spectroscopy demonstrate that the nonreactive surfaces of CNTs have been modified successfully by multiple hydroxyl groups. Functionalized carbon nanotubes exhibit higher zeta potential values indicating their high dispersibility in polar solvents. XRD studies corroborate that the surface functionalization does not affect the basic crystal domain size of CNTs. TEM observations reveal that CNTs have been cut into shorter ones by the milling. Shortened CNTs with functionalized surfaces show good dispersion properties

    Effects of experimental parameters on elemental analysis of coal by laser-induced breakdown spectroscopy

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    The purpose of this work is to improve the precision of the elemental analysis of coal using laser-induced breakdown spectroscopy (LIBS). The LIBS technique has the ability to allow simultaneous elemental analysis and on-line determination, so it could be used in the elemental analysis of coal. Organic components such as C, H, O, N and inorganic components such as Ca, Mg, Fe, Al, Si, Ti, Na, and K of coal have been identified. The precision of the LIBS technique depends strongly on the experimental conditions, and the choice of experimental parameters should be aimed at optimizing the repeatability of the measurements. The dependences of the relative standard deviation (RSD) of the LIBS measurements on the experimental parameters including the sample preparation parameters, lens-to-sample distance, sample operation mode, and ambient gas have been investigated. The results indicate that the precision of LIBS measurements for the coal sample can be improved by using the optimum experimental parameters

    Photochemical control of bacterial gene expression based ontransencoded genetic switches

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    Controlling gene expression by light with fine spatiotemporal resolution not only allows understanding and manipulating fundamental biological processes but also fuels the development of novel therapeutic strategies. In complement to exploiting optogenetic tools, photochemical strategies mostly rely on the incorporation of photo-responsive small molecules into the corresponding biomacromolecular scaffolds. Therefore, generally large synthetic effort is required and the switching of gene expression in both directions within a single system remains a challenge. Here, we report a trans encoded ribo-switch, which consists of an engineered tRNA mimicking structure (TMS), under control of small photo-switchable signalling molecules. The signalling molecules consist of two amino glycoside molecules that are connected via an azobenzene unit. The light responsiveness of our system originates from the photo-switchable noncovalent interactions between the signalling molecule and the TMS switch, leading to the demonstration of photochemically controlled expression of two different genes. We believe that this modular design will provide a powerful platform for controlling the expression of other functional proteins with high spatiotemporal resolution employing light as a stimulus

    Influences of graphene oxide support on the electrochemical performances of graphene oxide-MnO2 nanocomposites

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    MnO2 supported on graphene oxide (GO) made from different graphite materials has been synthesized and further investigated as electrode materials for supercapacitors. The structure and morphology of MnO2-GO nanocomposites are characterized by X-ray diffraction, X-ray photoemission spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and Nitrogen adsorption-desorption. As demonstrated, the GO fabricated from commercial expanded graphite (denoted as GO(1)) possesses more functional groups and larger interplane gap compared to the GO from commercial graphite powder (denoted as GO(2)). The surface area and functionalities of GO have significant effects on the morphology and electrochemical activity of MnO2, which lead to the fact that the loading amount of MnO2 on GO(1) is much higher than that on GO(2). Elemental analysis performed via inductively coupled plasma optical emission spectroscopy confirmed higher amounts of MnO2 loading on GO(1). As the electrode of supercapacitor, MnO2-GO(1) nanocomposites show larger capacitance (307.7 F g-1) and better electrochemical activity than MnO2-GO(2) possibly due to the high loading, good uniformity, and homogeneous distribution of MnO2 on GO(1) support
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