60 research outputs found
Endohedral Metallofullerene Derivatives
Trimetallic nitride endohedral metallofullerene derivatives and their preparation are described. The trimetallic nitride endohedral metallofullerene derivatives have the general formula A(sub 3-n)X(sub n)@C(sub m)(R) where n ranges from 0 to 3, A and X may be trivalent metals and may be either rare earth metal or group IIIB metals, m is between about 60 and about 200, and R is preferably an organic group. Derivatives where the R group forms cyclized derivatives with the fullerene cage are also described
Encapsulated Molecules in Carbon Nanotubes: Structure and Properties
We encapsulate a number of fullerenes inside single-walled carbon nanotubes (SWNTs) including La2@C80 and ErxSc3-xN@C80(x=0-3). The structural properties of these nanoscopic hybrid materials are described using high resolution transmission electron microscopy and electron diffraction. It is found that the encapsulated fullerenes selfassemble into long, one-dimensional chains. The thermal stability of these supramolecular assemblies are studied and large variations are found. The behavior is nominally consistent with the mass of the encapsulated metallofullerenes
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High Blocking Temperature of Magnetization and Giant Coercivity in the Azafullerene Tb 2 @C 79 N with a Single-Electron Terbium–Terbium Bond
The azafullerene Tb 2 @C 79 N is found to be a single-molecule magnet with a high 100-s blocking temperature of magnetization of 24 K and large coercivity. Tb magnetic moments with an easy-axis single-ion magnetic anisotropy are strongly coupled by the unpaired spin of the single-electron Tb−Tb bond. Relaxation of magnetization in Tb 2 @C 79 N below 15 K proceeds via quantum tunneling of magnetization with the characteristic time τ QTM =16 462±1230 s. At higher temperature, relaxation follows the Orbach mechanism with a barrier of 757±4 K, corresponding to the excited states, in which one of the Tb spins is flipped. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA
Optimization of Control Strategies for Non-Domiciliated Triatoma dimidiata, Chagas Disease Vector in the Yucatán Peninsula, Mexico
Chagas disease is the most important vector-borne disease in Latin America. Residual insecticide spraying has been used successfully for the elimination of domestic vectors in many regions. However, some vectors of non-domestic origin are able to invade houses, and they are now a key challenge for further disease control. We developed a mathematical model to predict the temporal variations in abundance of non-domiciliated vectors inside houses, based on triatomine demographic parameters. The reliability of the predictions was demonstrated by comparing these with different sets of insect collection data from the Yucatan peninsula, Mexico. We then simulated vector control strategies based on insecticide spraying, insect, screens and bednets to evaluate their efficacy at reducing triatomine abundance in the houses. An optimum reduction in bug abundance by at least 80% could be obtained by insecticide application only when doses of at least 50 mg/m2 were applied every year within a two-month period matching the house invasion season by bugs. Alternatively, the use of insect screens consistently reduced bug abundance in the houses and offers a sustainable alternative. Such screens may be part of novel interventions for the integrated control of various vector-borne diseases
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Expedition Inspiration Fund for Breast Cancer Research Meeting 2003
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44216/1/10549_2004_Article_5139058.pd
Characterization of the Dispersal of Non-Domiciliated Triatoma dimidiata through the Selection of Spatially Explicit Models
Chagas disease is one of the most important neglected diseases in Latin America. Although insecticides have been successfully sprayed to control domiciliated vector populations, this strategy has proven to be ineffective in areas where non-domiciliated vectors immigrating from peridomestic or sylvatic ecotopes can (re-)infest houses. The development of strategies for the control of non-domiciliated vectors has thus been identified by the World Health Organization as a major challenge. Such development primarily requires a description of the spatio-temporal dynamics of infestation by these vectors, and a good understanding of their dispersal. We combined for the first time extensive spatio-temporal data sets describing house infestation dynamics by Triatoma dimidiata inside one village, and spatially explicit population dynamics models. The models fitted and predicted remarkably the observed infestation dynamics. They thus provided both key insights into the dispersal of T. dimidiata in this area, and a suitable mathematical background to evaluate the efficacy of various control strategies. Interestingly, the observed and modelled patterns of infestation suggest that interventions could focus on the periphery of the village, where there is the highest risk of transmission. Such spatial optimization may allow for reducing the cost of control, compensating for repeated interventions necessary for non-domiciliated vectors
Polarizability Effects Dominate the Chromatographic Retention Behavior of Spheroidal and Elipsoidal Metallofullerene Nanospheres
The
chromatographic retention behavior of spherical and elipsodial
metallofullerenes provides a unique class for studying subtle intermolecular
dispersive (London effect) and inductive (Debye effect) solution-state/solid-phase
interactions. The known trimetallic nitride endohedral metallofullerene
A<sub>3</sub>N@C<sub>80</sub> isomers are nearly spherical A<sub>3</sub>N@C<sub>80</sub>-<i>I</i><sub><i>h</i></sub> and
ellipsoidal A<sub>3</sub>N@C<sub>80</sub>-<i>D</i><sub>5<i>h</i></sub>. These metallofullerene isomers are readily available
with group IIIB and lanthanide trimetallic nitride clusters (A<sub>3</sub>N)<sup>6+</sup>. In the current study, chromatographic HPLC
retention behavior is monitored for two different HPLC stationary
phases, pentabromobenzyl and pyrenylethyl and augmented by density
functional theory computational results. Although dipole moments,
lanthanide contraction, and charge transfer from the internal cluster
(A<sub>3</sub>N)<sup>6+</sup> are important factors controlling chromatographic
retention, our results suggest that the fullerene cage polarizability
is the dominant factor controlling chromatographic separation of A<sub>3</sub>N@C<sub>80</sub>-<i>I</i><sub><i>h</i></sub> and elipsodial A<sub>3</sub>N@C<sub>80</sub>-<i>D</i><sub>5<i>h</i></sub> isomers. Our study suggests that computational
dipole moment and polarizability data allow accurate prediction of
chromatographic retention behavior for fullerenes and metallofullerenes
and can be extended to other π conjugated aromatic systems
Size distribution of different nanoparticles.
<p>PEGylated DSPC lipsome (black), SWNH(-CH<sub>2</sub>-CH<sub>2</sub>-COOH)<sub>x</sub> (red), paclitaxel loaded SWNH(-CH<sub>2</sub>-CH<sub>2</sub>-COOH)<sub>x</sub> (green), DSPC NsiL (blue), and DSPC NsiL without paclitaxel (light blue). Sizes are shown in diameters (mean ± S.D., n = 45).</p
Study of NPs cytotoxicity by cell viability test.
<p>a, SK-BR-3 cells; b, BT-20 cells. Cells were treated with 640, 320, 160 and 80 µg/ml NPs (in lipid concentration). NsLDO and LipoDO are DOTAP NsL and PEGylated DOTAP liposomes, respectively. NsLDS and LipoDS are DSPC NsL and PEGylated DSPC liposomes, respectively. SWHN indicates SWNH(-CH<sub>2</sub>-CH<sub>2</sub>-COOH)<sub>x</sub>.</p
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