2,610 research outputs found
Studies examining the infectivity of Human Immunodeficiency Virus (HIV) on human immune cells
Human immunodeficiency virus (HIV) establishes a latent infection in cells to ensure a persistent infection throughout an infected individual’s life. HIV can establish this latent infection in a variety of cells. Highly Active Anti-Retroviral Treatment (HAART) is a selection of drugs used to inhibit the production of new HIV and new infections and can effectively diminish virus population in blood. However, due to the pathological mechanism of the virus, it is not possible yet to completely eradicate virus as it remains immunologically invisible in latent cellular reservoirs. The cellular reservoirs where HIV evades the immune system are not known completely. Current research efforts are focused on identifying the cellular populations where HIV remains latent and determine how those latent reservoirs are established. By identifying latent cellular reservoirs where HIV resides strategies can be developed to target and kill infected cells or prevent emergence of virus. We hypothesized that primary, skin, human mast cells may represent a previously unknown latent reservoir for HIV. Because mast cells can be activated through IgE-and non-IgE-dependent stimulation, we further hypothesized activated mast cells may be more vulnerable to infection. Our experimentations suggest that skin-derived mast cells are not susceptible to HIV infection and are not an inducible reservoir for HIV.One strategy for inhibiting viral replication has been with fullerenes. Fullerenes are carbon spheres that can be functionalized for use in various biological systems. Fullerenes functionalized with large dendrimeric moieties have been shown previously to inhibit viral replication in vitro, but the majority of investigations that have explored fullerenes as an inhibitor of HIV were assessed computationally. Based on these previous studies we hypothesized that certain functionalized fullerenes will suppress HIV infectivity and/or replication. We hypothesized that these fullerenes may interact with HIV protease and performed molecular modeled docking studies to investigate this idea. We also performed in vitro dose response assays on certain fullerene derivatives and our findings suggest they were effective at suppressing the virus
Testing the effect of fullerene and its derivatives on the environment
The paper points to the increasing use of products containing nanomaterials and warns
that the public which uses such products often fails to be adequately informed about their
potential hazards. The specifi c subject of the paper is fullerene and its bromo derivative.
The contradictory opinions regarding the hazards associated with this material are
discussed, and its potential environmental impacts are investigated experimentally
Polaron Excitations in Doped C60: Effects of Disorders
Effects on C by thermal fluctuations of phonons, misalignment of
C molecules in a crystal, and other intercalated impurities (remaining
C, oxygens, and so on) are simulated by disorder potentials. The
Su-Schrieffer-Heeger--type electron-phonon model for doped C is solved
with gaussian bond disorders and also with site disorders. Sample average is
performed over sufficient number of disorder configurations. The distributions
of bond lengths and electron densities are shown as functions of the disorder
strength and the additional electron number. Stability of polaron excitations
as well as dimerization patterns is studied. Polarons and dimerizations in
lightly doped cases (C) are relatively stable against disorders,
indicated by peak structures in distribution functions. In more heavily doped
cases, the several peaks merge into a single peak, showing the breakdown of
polaron structures as well as the decrease of the dimerization strength.
Possibility of the observation of polaronic lattice distortions and electron
structures in doped C is discussed.Comment: Note: This manusript was accepted for publication in Physical Review
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Decay and fusion as two different mechanisms of stability loss for the (C_20)_2 cluster dimer
The thermal stability of the (C_20)_2 cluster dimer consisting of two C_20
fullerenes is examined using a tight-binding approach. Molecular dynamics
simulations of the (C_20)_2 dimer at temperatures T = 2000 - 3500 K show that
the finite lifetime \tau of this metastable system is determined by two
fundamentally different processes, the decay of one of the C_20 fullerenes and
the fusion of two C_20 fullerenes into the C_40 cluster. The activation
energies for these processes Ea = 3.4 and 2.7 eV, respectively, as well as
their frequency factors, have been determined by analyzing the dependence of
\tau on T.Comment: Slightly modified version of the paper to appear in JETP Let
Structure and Stability of Two-Dimensional Complexes of C_20 Fullerenes
Two-dimensional complexes of C_20 fullerenes connected to each other by
covalent bonds have been studied. Several isomers with different types of
intercluster bonds have been revealed. The lifetimes of the (C_20)_MxM systems
with M = 2 and 3 have been directly calculated at T = 1800 - 3300 K making use
of molecular dynamics. It has been shown that these complexes lose their
periodic cluster structure due to either coalescence of two fullerenes C_20 or
decay of C_20 fullerenes. The activation energies of these processes exceed 2
eV.Comment: 17 pages, 5 figure
MasterChem: Cooking 2D-polymers
2D-polymers are still dominated by graphene and closely related materials such as boron nitride, transition metal sulphides and oxides. However, the rational combination of molecules with suitable design is already showing the high potential of chemistry in this new research field. The aim of this feature article is to illustrate, and provide some perspectives, the current state-of-the-art in the field of synthetic 2D-polymers showing different alternatives to prepare this novel type of polymers based on the rational use of chemistry. This review comprises a brief revision of the essential concepts, the strategies of preparation following the two general approaches, bottom-up and top-down, and a revision of the promising seminal properties showed by some of these nanomaterials.Financial support from Spanish MINECO (MAT2013-46753-C2-1-P and MAT2013-46502-C2-2-P). D. R. thanks the Spanish MECD for a FPU gran
Adsorption of Sodium and Cesium on Aggregates of C60
We explore the formation of C60 sodium and C60 cesium complexes in superfluid helium nanodroplets. Anomalies in mass spectra of these doped droplets reveal anomalies in the stability of ions. (C60) m Cs+ n ions ( m ≤ 6) are particularly abundant if they contain n = 6m + 1 cesium atoms; (C60) m Cs2+ n dications ( m ≤ 3 or 5) are abundant if n = 6m + 2. These findings are consistent with the notion that alkali metal atoms (A) transfer their valence electrons into the three-fold degenerate lowest unoccupied orbital of C60, resulting in particularly stable C60A6 building blocks. However, (C60) 4CsCs2+ n dications display an entirely different pattern; instead of an expected anomaly at n = 6 × 4 + 2 = 26 we observe a strong odd-even alternation starting at n = 6. Also surprising is the effect of adding one H2O or CO2 molecule to (C60) m Cs n mono- or dications; anomalies shift by two units as if the impurity were acting as an acceptor for two valence electrons from the alkali metal atoms
Diffraction of complex molecules by structures made of light
We demonstrate that structures made of light can be used to coherently
control the motion of complex molecules. In particular, we show diffraction of
the fullerenes C60 and C70 at a thin grating based on a standing light wave. We
prove experimentally that the principles of this effect, well known from atom
optics, can be successfully extended to massive and large molecules which are
internally in a thermodynamic mixed state and which do not exhibit narrow
optical resonances. Our results will be important for the observation of
quantum interference with even larger and more complex objects.Comment: 4 pages, 3 figure
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