404 research outputs found

    Process for attaching molecular wires and devices to carbon nanotubes and compositions thereof

    Get PDF
    The present invention is directed towards processes for covalently attaching molecular wires and molecular electronic devices to carbon nanotubes and compositions thereof. Such processes utilize diazonium chemistry to bring about this marriage of wire-like nanotubes with molecular wires and molecular electronic devices

    Process for derivatizing carbon nanotubes with diazonium species and compositions thereof

    Get PDF
    Methods for the chemical modification of carbon nanotubes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications, and sensor devices. The methods of derivatization include electrochemical induced reactions, thermally induced reactions, and photochemically induced reactions. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes

    Process for making polymers comprising derivatized carbon nanotubes and compositions thereof

    Get PDF
    The present invention incorporates new processes for blending derivatized carbon nanotubes into polymer matrices to create new polymer/composite materials. When modified with suitable chemical groups using diazonium chemistry, the nanotubes can be made chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as mechanical strength) to the properties of the composite material as a whole. To achieve this, the derivatized (modified) carbon nanotubes are physically blended with the polymeric material, and/or, if desired, allowed to react at ambient or elevated temperature. These methods can be utilized to append functionalities to the nanotubes that will further covalently bond to the host polymer matrix, or directly between two tubes themselves. Furthermore, the nanotubes can be used as a generator of polymer growth, wherein the nanotubes are derivatized with a functional group that is an active part of a polymerization process, which would also result in a composite material in which the carbon nanotubes are chemically involved

    Factors associated with fatigue in acquired immunodeficiency syndrome patients with antiretroviral drug adverse reactions: a retrospective study

    Get PDF
    AbstractObjectiveTo retrospectively study the prevalence of fatigue and factors associated with fatigue among acquired immunodeficiency syndrome (AIDS) patients with antiretroviral drug adverse reactions.MethodsData were collected from case report forms (CRFs) for a project funded by the 11th National 5-year Special Science and Technology Program on Major Infectious Diseases. Fatigue was defined by patient self-report. The outcomes were the prevalence of fatigue and the potential risk factors of fatigue. Univariate and multivariate logistic regression analyses were conducted to identify the factors associated with fatigue.ResultsAmong the 228 subjects, the prevalence of fatigue was 86.8%. In univariate analysis, the significant differences in demographic characteristics between patients with and without fatigue were: gender [OR=2.29; 95% CI (1.05-4.98)], education level [OR=0.40; 95% CI (0.18-0.85)], anemia [OR=3.80; 95% CI (1.27-11.31)], time of HIV diagnosis [OR= 0.29; 95% CI (0.13-0.65)], and route of infection [OR=0.14; 95% CI (0.06-0.32)]. Abnormal taste and rapid pulse were more commonly seen in patients with fatigue (P<0.05), while abdominal distension and lumbar soreness were encountered less often in patients with fatigue (P<0.05). Multivariate analysis showed that the four main factors associated with fatigue were anemia [OR=3.50; 95% CI (1.01-12.15)], route of infection [OR=3.40; 95% CI (1.21-9.58); P=0.02<0.05], lumbar soreness [OR=0.06; 95% CI (0.02-0.18); P=0.000<0.05], and rapid pulse [OR=10.58; 95% CI (2.16-51.75); P=0.004<0.05].ConclusionThis study demonstrated that fatigue is common (86.8% prevalence) in AIDS patients with antiretroviral drug adverse reactions, and that anemia, route of infection (i.e., non-commercial blood donation) and rapid pulse were risk factors, while lumbar soreness was a protective factor related to fatigue. More attention should be paid to fatigue and more efforts should be made to find ways to prevent, control and eliminate this symptom in AIDS patients with antiretroviral drug adverse reactions

    Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

    Get PDF
    Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes

    Lending and Borrowing across Borders: Issues and Challenges with International Resource Sharing

    Get PDF
    This article reports on a survey of U.S. libraries regarding international interlibrary loan. The survey was conducted by the ALA RUSA STARS International Interlibrary Loan Committee

    Diffusive Pseudo-Conformal Mapping: Anisotropy-Free Transformation Thermal Media with Perfect Interface Matching

    Full text link
    Transformation media provide a fundamental paradigm for field regulation, but their tricky anisotropy challenges fabrication. Though optical conformal mapping has been utilized to eliminate anisotropy, two key factors still hinder its development in thermotics, i.e., the distinct diffusion nature and inevitable interface mismatching. Here, we put forth the concept of diffusive pseudo-conformal mapping, overcoming the inherent difference between diffusion and waves and achieving perfect interface matching. The proposed mapping directly leads to heat guiding and expanding functions with anisotropy-free transformation thermal media, whose feasibility is confirmed by experiments or simulations. Besides diverse applications, we provide a unified perspective for two distinct types of prevailing bilayer cloaks by uncovering their profound ties with pseudo-conformal mapping. These results greatly simplify the preparation of transformation thermotics and have implications for regulating other diffusion and wave phenomena

    Lending and Borrowing Across Borders: Issues and Challenges with International Resource Sharing

    Get PDF
    The charge of the RUSA Sharing and Transforming Access to Resources Section (STARS) International Interlibrary Loan Committee is to evaluate trends in international interlibrary loan (ILL) and resource sharing, to develop materials and resources for international ILL practitioners, and to promote international ILL resource sharing efforts. In 2006, the committee decided to survey U.S. libraries regarding their international ILL activities as a way to gather information on the current environment and identify strategies for improving international ILL. The survey was deployed in the spring of 2007. In the fall of 2008, the committee members drafted an executive summary, which was approved by the RUSA STARS Executive Committee and posted to the STARS website (www.ala.org/ala/mgrps/ divs/rusa/sections/stars/section/internationill/ILLReport ExecSummary.pdf). Specifically, the survey sought to determine what types of U.S. libraries participate in international ILL services as borrowers and lenders, to what extent libraries work internationally, and what tools and services survey participants use to go global. The results of the survey will help guide the committee in developing tools to resolve issues that may hinder international resource sharing and uncover opportunities to promote and expand both the use of and the participation in global ILL services. This article intends to reflect on changes in the resource-sharing environment since 1998, provide an overview of current practice, and lay the foundation for future International Interlibrary Loan Committee efforts

    Unraveling the complexities of the Last Glacial Maximum climate: the role of individual boundary conditions and forcings

    Get PDF
    In order to quantify the relative importance of individual boundary conditions and forcings, including greenhouse gases, ice sheets, and Earth’s orbital parameters, on determining Last Glacial Maximum (LGM) climate, we have performed a series of LGM experiments using a state-of-the-art climate model AWI-ESM, in which different combinations of boundary conditions and forcings have been applied following the protocol of Paleoclimate Modelling Intercomparison Project phase 4 (PMIP4). In good agreement with observational proxy records, a general colder and drier climate is simulated in our full-forced LGM experiment as compared to the present-day simulation. Our simulated results from non-full-forced sensitivity simulations reveal that both the greenhouse gases and ice sheets play a major role in defining the anomalous LGM surface temperature compared to today. Decreased greenhouse gases in LGM as compared to present day leads to a non-uniform global cooling with polar amplification effect. The presence of LGM ice sheets favors a warming over the Arctic and northern Atlantic oceans in boreal winter, as well as a cooling over regions with the presence of ice sheets. The former is induced by a strengthening in the Atlantic meridional overturning circulation (AMOC) transporting more heat to high latitudes, whilst the latter is due to the increased surface albedo and elevation of ice sheets. We find that the Northern Hemisphere monsoon precipitation is influenced by the opposing effects of LGM greenhouse gases and ice sheets. Specifically, the presence of ice sheets leads to significant drying in the Northern Hemisphere monsoon regions, while a reduction in greenhouse gases results in increased monsoon rainfall. Based on our model results, continental ice sheets exert a major control on atmospheric dynamics and the variability of El Niño–Southern Oscillation (ENSO). Moreover, our analysis also implies a nonlinearity in climate response to LGM boundary conditions and forcings
    • …
    corecore