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1.
Abstract Molecular dynamics techniques have been used to model the processes associated with the deposition of alkanes on a hematite surface, and the subsequent growth of an alkane crystal. First we have obtained a relaxed (0001)-hematite surface; this is believed to be the most common surface exhibited on the pipeline walls. Subsequently, the adsorption of two different linear alkanes has been examined: C12 and C28. The principal adsorption site for both has been determined and consisted of the molecule lying between two parallel rows of iron atoms. The subsequent addition of alkane molecules generates a crystalline structure, which corresponds closely with C28 crystal growth along the (010) direction. 相似文献
2.
Pierre Kirschbaum Niemma M. Buckanie Frank-J. Meyer zu Heringdorf 《Plasmonics (Norwell, Mass.)》2012,7(2):229-233
The influence of C60 adsorption on the properties of surface plasmon polaritons on small Ag islands is discussed. Under illumination with UV light as well as under illumination with femtosecond laser pulses, a decrease of the photoemission yield with increasing C60 coverage is observed. With angular resolved measurements, changes of the band structure during deposition are studied. Based on these experiments, an increase of the work function with increasing coverage is measured. In two photon photoemission, the surface plasmons are imaged as a periodic moiré pattern, the wavelength of which changes because of a modified effective surface dielectric function. Our findings imply that the wavelength of the plasmon wave becomes shorter as a result. Finally, a decrease of the intensity of the moiré pattern maxima compared with the intensity of the first maximum with increasing C60 coverage has been observed. Accordingly, the damping of the plasmon wave becomes stronger. 相似文献
3.
H. Shen 《Molecular simulation》2013,39(1):59-64
By the quantum-molecular dynamics (QMD) technique based on the Roothaan–Hall equation and the Newton motion law, geometrical deformation and failure behavior of C60 fullerene dimer (2C60) as well as single C60 fullerene under applied external electric field are simulated. Further, the effects of the electric field direction on the electric field-induced deformation, polarization-charge distribution and dipole moment of the fullerene molecules are discussed systemically. It is found that the geometrical configuration and failure behavior of the 2C60 molecule are sensitive to the electric field direction, that when the electric field direction is parallel to the bridging C–C bonds of the 2C60 molecule the 2C60 fails easily, and that when the electric field direction is perpendicular to the 2C60 fails difficultly and has the same polarization and failure mechanism as the single C60. 相似文献
4.
Thin films of binary C60/Ti composites, with various concentrations of Ti ranging from ~ 25% to ~ 70%, were deposited on microscopic glass coverslips and were tested for their potential use in bone tissue engineering as substrates for the adhesion and growth of bone cells. The novelty of this approach lies in the combination of Ti atoms (i.e., widely used biocompatible material for the construction of stomatological and orthopedic implants) with atoms of fullerene C60, which can act as very efficient radical scavengers. However, fullerenes and their derivatives are able to generate harmful reactive oxygen species and to have cytotoxic effects. In order to stabilize C60 molecules and to prevent their possible cytotoxic effects, deposition in the compact form of Ti/C60 composites (with various Ti concentrations) was chosen. The reactivity of C60/Ti composites may change in time due to the physicochemical changes of molecules in an air atmosphere. In this study, we therefore tested the dependence between the age of C60/Ti films (from one week to one year) and the adhesion, morphology, proliferation, viability, metabolic activity and potential DNA damage to human osteosarcoma cells (lines MG-63 and U-2 OS). After 7 days of cultivation, we did not observe any negative influence of fresh or aged C60/Ti layers on cell behavior, including the DNA damage response. The presence of Ti atoms resulted in improved properties of the C60 layers, which became more suitable for cell cultivation. 相似文献
5.
E. M. Eropkina E. V. Ilyinskaya E. V. Litasova M. Yu. Eropkin L. B. Piotrovsky M. A. Dumpis O. I. Kiselev 《Biophysics》2012,57(3):343-349
In view of contradictory data on the toxicity of fullerenes for living organisms we studied the effect of water-soluble complexes of C60 with N-polyvinylpyrrolidone (C60/PVP) and γ-cyclodextrin (C60/γ-CD) on MA-104 cells in culture. Both complexes proved to be nontoxic for cultured cells in the dark in a wide range of concentrations. Both complexes provoke changes of cell ultrastructure that reflect enhancement of metabolic activity. At the same time only the exposition with C60/PVP leads to substantial growth of the number and size of mitochondria. However, the effect of two studied water-soluble forms of C60 under intense UV irradiation of cells proved to be opposite: C60/PVP had a cytoprotective action while C60/γ-CD caused a significant growth of phototoxicity. Possible reasons of the differences in the action of different forms of C60 on living organisms are discussed. 相似文献
6.
The structures and stabilities of C60On, where n=1-6, 9, have been calculated using the AM1 Hamiltonian and the program mopac 6.0, and by the density functional technique B3LYP/6-31G* at the AM1 geometry using Gaussian 98. Modes of oxygen addition considered were ethers, epoxides, ketones and ketenes. It is confirmed that in C60O a carbon-carbon bond on a pent-hex edge is replaced by an ether linkage. For higher levels of oxygen addition the replacement of a carbon-carbon bond by two ketone groups becomes important. Particularly stable structures are formed if the additions are on the same, or adjacent, C6 rings of the C60 structure where the oxygen atoms cooperate in opening up large holes in the molecule. Molecules of greatest stability have a mixture of ether oxygen atoms on pent-hex edges and diketone additions on hex-hex edges. A particularly important stable structure is the mixed ether/ketone isomer of C60O6 in which a hinged C5O2 hatch lid containing two ketone oxygen atoms is opened revealing a hatch 4-5 Å in diameter. An even larger hole of approximately 6 Å in diameter is opened up in a particularly stable isomer of C60O9 which contains three ether and six ketone groups. Removal of the oxygen atoms from these structures and reoptimisation leads to hatch closing and C60 is reformed. 相似文献
7.
Several models of microbial surface colonization have been devised to quantitate growth and attachment rates on surfaces. One of these, the surface growth rate equation, is based on the assumption that the number of microcolonies of a given size (Ci) reaches a constant value (Cmax) that is equal to the attachment rate (A) divided by the specific growth rate (Μ). In this study, a computer simulation was used to determine the time required to reach Cmax. It was shown that Ci approaches Cmax asymptotically. The time required is dependent solely upon the growth rate and size of microcolonies. The number of one-celled microcolonies reaches 95% of Cmax after 4.3 generations. At low growth rates, a relatively long incubation period is required. Alternate methods that shorten the incubation time are considered. 相似文献
8.
James A. Raiford Caleb C. Boyd Axel F. Palmstrom Eli J. Wolf Benjamin A. Fearon Joseph J. Berry Michael D. McGehee Stacey F. Bent 《Liver Transplantation》2019,9(47)
Metal‐halide perovskites show promise as highly efficient solar cells, light‐emitting diodes, and other optoelectronic devices. Ensuring long‐term stability is now a major priority. In this study, an ultrathin (2 nm) layer of polyethylenimine ethoxylated (PEIE) is used to functionalize the surface of C60 for the subsequent deposition of atomic layer deposition (ALD) SnO2, a commonly used electron contact bilayer for p–i–n devices. The enhanced nucleation results in a more continuous initial ALD SnO2 layer that exhibits superior barrier properties, protecting Cs0.25FA0.75Pb(Br0.20I0.80)3 films upon direct exposure to high temperatures (200 °C) and water. This surface modification with PEIE translates to more stable solar cells under aggressive testing conditions in air at 60 °C under illumination. This type of “built‐in” barrier layer mitigates degradation pathways not addressed by external encapsulation, such as internal halide or metal diffusion, while maintaining high device efficiency up to 18.5%. This nucleation strategy is also extended to ALD VOx films, demonstrating its potential to be broadly applied to other metal oxide contacts and device architectures. 相似文献
9.
Marina Yu. Skorkina Evgenia A. Sladkova Elena A. Shamray Olga V. Cherkashina Maxim P. Evstigneev Anatoly S. Buchelnikov Yuriy I. Prylutskyy Uwe Ritter 《European biophysics journal : EBJ》2015,44(6):493-498
The influence of aqueous solution of pristine C60 fullerene (C60FAS) on functional activity of lymphocytes from a healthy person was studied for the first time. By means of atomic force microscopy, it was found that C60FAS in a concentration of 0.1 mg/ml increases the stiffness of the lymphocyte membrane by 41 % (p < 0.05) and lowers the functional activity of the plasmalemma surface, thereby constraining the use of its membrane material in physiological reactions using a hypotonic model in vitro. However, a cell retains the ability to regulate its volume and demonstrates relative resistance to hypo-osmotic stress. The resistance of lymphocytes in hypo-osmotic medium is facilitated by activation of the nucleus by C60 fullerene particles, which regulates the implementation of two consistent phases of an increase and decrease of cell volume, thereby retaining cell viability. All these indicate the impact of C60 fullerene on the cellular nucleus. 相似文献
10.
In this article, development of nanogold (NG) containing fullerene C60 nanofluids (NFs) with poly (vinyl pyrrolidone) PVP polymer in water via a wet chemical route is reported and studied their rheo-optical properties. An inclusion of NG into a C60:PVP nanofluid thus results in a gold (Au) surface plasmon resonance (SPR) enhanced π?→?π* C60 (sp2) electron transition over 250–450 nm of absorption spectrum in water. Evolution of a broad Au-SPR band in the 450–750 nm region signifies that a controlled Au3+?→?Au reduction reaction had occurred on it and was carried in C60:PVP NFs. The average maximum wavelength value has thus varied along with a molar extinction coefficient in a function of the Au-uploads and shape and size of the flocculates in the resulting Au:C60-PVP NFs. A systematic rheological study performed on the Au:C60-PVP NFs in water by varying the NG content up to 85.0 μM reveals a non-Newtonian behavior with an enhanced yield stress is a signature of Bingham flow. NG of different shapes serves as filler in C60:PVP NFs so as it adapts tailored shear viscosity. The shear viscosity relaxes slowly to the base value on increasing the shear rate from 10 to 100 s?1 as it leads to breaking up of soft Au:C60-PVP assemblies into a fine structures. Synthesis of Au:C60-PVP NFs with various Au-contents could be potential nanostructure hybrid composite materials for development of photovoltaic nanodevices. 相似文献
11.
Rebecca Bullard-Dillard Kim E. Creek Walter A. Scrivens James M. Tour 《Bioorganic chemistry》1996,24(4):376-385
This paper describes thein vivobehavior and potential metabolism of C60and a more water-soluble quaternary ammonium salt-derivatized C60. In both cases, a14C-labeled fullerene core was utilized for the target molecules that were intravenously injected into female Sprague–Dawley rats. The14C-labeled C60(*C60) was rapidly (within 1 min) cleared from the circulation and the majority of the *C60accumulated in the liver (90–95%). *C60was not eliminated from the liver over the 120-h period of this study. Our results also suggest that C60is not metabolized by the typical oxidative patterns characteristic of other polycyclic aromatics. Therefore, although not acutely toxic, use of C60, or its derivatives that could be cleaved back to the parent C60in vivo, would likely lead to long-term fullerene accumulation in the liver. The uptake of *C60and14C-labeled ammonium salt-derivatized C60(1)by human keratinocytesin vitroshowed that while both *C60and1are readily taken up by cells,1accumulates more slowly. Additionally, while C60, at rather high concentrations (2.0 μM) and over extended periods of time (8 days), is able to inhibit the growth of human keratinocytes by about 50%, this effect showed little, if any, photoinducability. 相似文献
12.
Maili Lehto Topi Karilainen Tomasz Róg Oana Cramariuc Esa Vanhala Jarkko Tornaeus Helena Taberman Janne J?nis Harri Alenius Ilpo Vattulainen Olli Laine 《PloS one》2014,9(12)
In vitro toxicological studies together with atomistic molecular dynamics simulations show that occupational co-exposure with C60 fullerene may strengthen the health effects of organic industrial chemicals. The chemicals studied are acetophenone, benzaldehyde, benzyl alcohol, m-cresol, and toluene which can be used with fullerene as reagents or solvents in industrial processes. Potential co-exposure scenarios include a fullerene dust and organic chemical vapor, or a fullerene solution aerosolized in workplace air. Unfiltered and filtered mixtures of C60 and organic chemicals represent different co-exposure scenarios in in vitro studies where acute cytotoxicity and immunotoxicity of C60 and organic chemicals are tested together and alone by using human THP-1-derived macrophages. Statistically significant co-effects are observed for an unfiltered mixture of benzaldehyde and C60 that is more cytotoxic than benzaldehyde alone, and for a filtered mixture of m-cresol and C60 that is slightly less cytotoxic than m-cresol. Hydrophobicity of chemicals correlates with co-effects when secretion of pro-inflammatory cytokines IL-1β and TNF-α is considered. Complementary atomistic molecular dynamics simulations reveal that C60 co-aggregates with all chemicals in aqueous environment. Stable aggregates have a fullerene-rich core and a chemical-rich surface layer, and while essentially all C60 molecules aggregate together, a portion of organic molecules remains in water. 相似文献
13.
Miles C. Barr Rachel M. Howden Richard R. Lunt Vladimir Bulović Karen K. Gleason 《Liver Transplantation》2012,2(11):1404-1409
Organic photovoltaics devices typically utilize illumination through a transparent substrate, such as glass or an optically clear plastic. Utilization of opaque substrates, including low cost foils, papers, and textiles, requires architectures that instead allow illumination through the top of the device. Here, we demonstrate top‐illuminated organic photovoltaics, employing a dry vapor‐printed poly(3,4‐ethylenedioxythiophene) (PEDOT) polymer anode deposited by oxidative chemical vapor deposition (oCVD) on top of a small‐molecule organic heterojunction based on vacuum‐evaporated tetraphenyldibenzoperiflanthene (DBP) and C60 heterojunctions. Application of a molybdenum trioxide (MoO3) buffer layer prior to oCVD deposition increases the device photocurrent nearly 10 times by preventing oxidation of the underlying photoactive DBP electron donor layer during the oCVD PEDOT deposition, and resulting in power conversion efficiencies of up to 2.8% for the top‐illuminated, ITO‐free devices, approximately 75% that of the conventional cell architecture with indium‐tin oxide (ITO) transparent anode (3.7%). Finally, we demonstrate the broad applicability of this architecture by fabricating devices on a variety of opaque surfaces, including common paper products with over 2.0% power conversion efficiency, the highest to date on such fiber‐based substrates. 相似文献
14.
The Roles of Structural Order and Intermolecular Interactions in Determining Ionization Energies and Charge‐Transfer State Energies in Organic Semiconductors
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Kenneth R. Graham Guy O. Ngongang Ndjawa Sarah M. Conron Rahim Munir Koen Vandewal John J. Chen Sean Sweetnam Mark E. Thompson Alberto Salleo Michael D. McGehee Aram Amassian 《Liver Transplantation》2016,6(22)
The energy landscape in organic semiconducting materials greatly influences charge and exciton behavior, which are both critical to the operation of organic electronic devices. These energy landscapes can change dramatically depending on the phases of material present, including pure phases of one molecule or polymer and mixed phases exhibiting different degrees of order and composition. In this work, ultraviolet photoelectron spectroscopy measurements of ionization energies (IEs) and external quantum efficiency measurements of charge‐transfer (CT) state energies (ECT) are applied to molecular photovoltaic material systems to characterize energy landscapes. The results show that IEs and ECT values are highly dependent on structural order and phase composition. In the sexithiophene:C60 system both the IEs of sexithiophene and C60 shift by over 0.4 eV while ECT shifts by 0.5 eV depending on molecular composition. By contrast, in the rubrene:C60 system the IE of rubrene and C60 vary by ≤ 0.11 eV and ECT varies by ≤ 0.04 eV as the material composition varies. These results suggest that energy landscapes can exist whereby the binding energies of the CT states are overcome by energy offsets between charges in CT states in mixed regions and free charges in pure phases. 相似文献
15.
Somayeh F. Rastegar Nasser L. Hadipour Mohammad Bigdeli Tabar Hamed Soleymanabadi 《Journal of molecular modeling》2013,19(9):3733-3740
The ability of pristine graphene (PG) and Al-doped graphene (AlG) to detect toxic acrolein (C3H4O) was investigated by using density functional calculations. It was found that C3H4O molecule can be adsorbed on the PG and AlG with adsorption energies about ?50.43 and – v30.92 kcal mol?1 corresponding to the most stable configurations, respectively. Despite the fact that interaction of C3H4O has no obvious effects on the of electronic properties of PG, the interaction between C3H4O and AlG can induce significant changes in the HOMO/LUMO energy gap of the sheet, altering its electrical conductivity which is beneficial to sensor designing. Thus, the AlG may be sensitive in the presence of C3H4O molecule and might be used in its sensor devices. Also, applying an external electric filed in an appropriate orientation (almost stronger than 0.01 a.u.) can energetically facilitate the adsorption of C3H4O molecule on the AlG. 相似文献
16.
Ziyang Lu Qinghua Liang Bo Wang Ying Tao Yufeng Zhao Wei Lv Donghai Liu Chen Zhang Zhe Weng Jiachen Liang Huan Li Quan‐Hong Yang 《Liver Transplantation》2019,9(7)
Uncontrolled dendrites resulting from nonuniform lithium (Li) nucleation/growth and Li volume expansion during charging cause serious safety problems for Li anode‐based batteries. Here the coating of nickel foam with graphitic carbon nitride (g‐C3N4) to have a 3D current collector (g‐C3N4@Ni foam) for dendrite‐free Li metal anodes is reported. The lithiophilic g‐C3N4 coupled with the 3D framework is demonstrated to be highly effective for promoting the uniform deposition of Li and suppressing the formation of dendrites. Both density functional theory calculations and experimental studies indicate the formation of a micro‐electric field resulting from the tri‐s‐triazine units of g‐C3N4, which induces numerous Li nuclei during the initial nucleation stage, effectively guiding the following Li growth on the 3D Ni foam to be well distributed. Furthermore, the 3D porous framework is favorable for absorbing any volume change and stabilizing the solid–electrolyte interphase layer during repeated Li plating/stripping. As such, a Li metal anode based on the g‐C3N4@Ni foam has a remarkable electrochemical performance with a high Coulombic efficiency (98% retention after 300 cycles), an ultralong lifespan up to 900 h, as well as a low overpotential (<15 mV at 1.0 mA cm?2) at a Li deposition of 9.0 mA h cm?2. 相似文献
17.
Global forest carbon uptake due to nitrogen and phosphorus deposition from 1850 to 2100 总被引:1,自引:0,他引:1
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Rong Wang Daniel Goll Yves Balkanski Didier Hauglustaine Olivier Boucher Philippe Ciais Ivan Janssens Josep Penuelas Bertrand Guenet Jordi Sardans Laurent Bopp Nicolas Vuichard Feng Zhou Bengang Li Shilong Piao Shushi Peng Ye Huang Shu Tao 《Global Change Biology》2017,23(11):4854-4872
Spatial patterns and temporal trends of nitrogen (N) and phosphorus (P) deposition are important for quantifying their impact on forest carbon (C) uptake. In a first step, we modeled historical and future change in the global distributions of the atmospheric deposition of N and P from the dry and wet deposition of aerosols and gases containing N and P. Future projections were compared between two scenarios with contrasting aerosol emissions. Modeled fields of N and P deposition and P concentration were evaluated using globally distributed in situ measurements. N deposition peaked around 1990 in European forests and around 2010 in East Asian forests, and both increased sevenfold relative to 1850. P deposition peaked around 2010 in South Asian forests and increased 3.5‐fold relative to 1850. In a second step, we estimated the change in C storage in forests due to the fertilization by deposited N and P (?Cν dep), based on the retention of deposited nutrients, their allocation within plants, and C:N and C:P stoichiometry. ?Cν dep for 1997–2013 was estimated to be 0.27 ± 0.13 Pg C year?1 from N and 0.054 ± 0.10 Pg C year?1 from P, contributing 9% and 2% of the terrestrial C sink, respectively. Sensitivity tests show that uncertainty of ?Cν dep was larger from P than from N, mainly due to uncertainty in the fraction of deposited P that is fixed by soil. ?CP dep was exceeded by ?CN dep over 1960–2007 in a large area of East Asian and West European forests due to a faster growth in N deposition than P. Our results suggest a significant contribution of anthropogenic P deposition to C storage, and additional sources of N are needed to support C storage by P in some Asian tropical forests where the deposition rate increased even faster for P than for N. 相似文献
18.
Hiroki Tsumoto Syo Kawahara Yuki Fujisawa Takayoshi Suzuki Hidehiko Nakagawa Kohfuku Kohda Naoki Miyata 《Bioorganic & medicinal chemistry letters》2010,20(6):1948-1952
Water-soluble [60]fullerene (C60) derivatives were synthesized to examine their bioactivities. PC12 cells were used as a model of nerve cells and the bioactivities of synthesized C60 derivatives together with some reported ones were tested. Among the compounds tested, C60/(γ-CyD)2, C60-bis(γ-CyD) (5) containing C60-mono(γ-CyD) (5′), and C60/PVP were sufficiently soluble in water and showed an enhancing effect on the neurite outgrowth of NGF-treated PC12 cells. 相似文献
19.
Abstract. We evaluated the use of soil organic carbon (SOC) isotopes to describe grass-tree dynamics at locations at the savanna-C4 grassland ecotone and within a temperate semiarid Quercus savanna in southeastern Arizona, USA. SOC will not describe grass-tree dynamics at locations within the savanna because isotope composition near the soil surface does not correspond with the overlying vegetation and recent C3 carbon has been deposited at deep soil depths with no C4analog. In contrast, SOC can describe grass-tree dynamics at the savanna-grassland ecotone because isotope composition near the soil surface corresponds with overlying vegetation and significant deep soil deposition of C3 carbon was not apparent. At the ecotone, trees became established in the last 700–1700 years. There is no evidence to suggest an unstable grass-tree mixture at the ecotone since that time. 相似文献
20.
Abstract We report here the parallel implementation of an original algorithm allowing a fast calculation of the distance matrix D of a graph representing a given chemical structure (molecule, polymer, crystal, etc.). Our algorithm fits perfectly in the SIMD parallel architecture of the Connection Machines CM-200 as we shall show. After discussing the performances of the parallel evaluation of D, we will end with a relevant application concerning C60 and C70 fullerenes. The present study applies to a generic globally connected graph without any restriction on the local connectivity of each graph's vertex. 相似文献