Nanocapsule for Safe and Effective Methane Storage

A nanocapsule for safe and effective methane storage is investigated by the method of molecular dynamics. The mass content of methane in the nanocapsule reaches the value of 14.5 mass%. The nanocapsule consists of two parts: a locking chamber and a storage area. The locking chamber is the nanotube (10.10), open at one end, with a K@C601+endohedral complex inside it. The storage area is a nanotube (20.20). The locking chamber and the storage area are joined with each other and form T-junction. The locking chamber is opened at the methane filling and the discharge stages, and it is closed at the storage stage. Thanks to the locking chamber, methane molecules are stored in the nanocapsules under normal external conditions. Opening and closing of the locking chamber are carried out by the K@C601+endohedral complex displacement, which is done by the electric field action. The specific structure of the nanocapsule allows two aims to be reached: a high methane mass content and significant level of safety

Restricted three body problems at the nanoscale

In this paper, we investigate some of the classical restricted three body problems at the nanoscale, such as the circular planar restricted problem for three C60 fullerenes, and a carbon atom and two C60 fullerenes. We model the van der Waals forces between the fullerenes by the Lennard-Jones potential. In particular, the pairwise potential energies between the carbon atoms on the fullerenes are approximated by the continuous approach, so that the total molecular energy between two fullerenes can be determined analytically. Since we assume that such interactions between the molecules occur at sufficiently large distance, the classical three body problems analysis is legitimate to determine the collective angular velocity of the two and three C60 fullerenes at the nanoscale. We find that the maximum angular frequency of the two and three fullerenes systems reach the terahertz range and we determine the stationary points and the points which have maximum velocity for the carbon atom for the carbon atom and the two fullerenes system

Temperature Sensitive Nanocapsule of Complex Structural Form for Methane Storage

The processes of methane adsorption, storage and desorption by the nanocapsule are investigated with molecular-dynamic modeling method. The specific nanocapsule shape defines its functioning uniqueness: methane is adsorbed under 40 MPa and at normal temperature with further blocking of methane molecules the K@C601+ endohedral complex in the nanocapsule by external electric field, the storage is performed under normal external conditions, and methane desorption is performed at 350 K. The methane content in the nanocapsule during storage reaches 11.09 mass%. The nanocapsule consists of tree parts: storage chamber, junction and blocking chamber. The storage chamber comprises the nanotube (20,20). The blocking chamber is a short nanotube (20,20) with three holes. The junction consists of the nanotube (10,10) and nanotube (8,8); moreover, the nanotube (8,8) is connected with the storage chamber and nanotube (10,10) with the blocking chamber. The blocking chamber is opened and closed by the transfer of the K@C601+ endohedral complex under electrostatic field action

Nested boron nitride and carbon-boron nitride nanocones

In this letter we extend previously established results for nested carbon nanocones to both nested boron nitride and carbon-boron nitride nanocones. Based purely on mechanical principles and classical mathematical modelling techniques, we determine the energetically favourable structures for nested boron nitride and carbon-boron nitride nanocones. While only three apex angles for boron nitride tend to occur, we also consider the other two angles corresponding to the equivalent carbon nanocones. Two nanocones are assumed to be located co-axially in a vacuum environment. The Lennard-Jones parameters for boron nitride and carbon-boron nitride systems are calculated using the standard mixing rule. For the boron nitride cones, numerical results indicate that the interspacing between two cones is approximately 3.4 Aring which is comparable with the experimental results. For the hybrid carbon-boron nitride cones, the numerical results essentially depend on the outer cone angle, and the interspacing distance is also obtained to be approximately 3.4 Aring. Moreover, the equilibrium position is such that one cone is always inside the other, and therefore nested double-cones are possible in practice.D. Baowan and J.M. Hil

Modelling selective separation of trypsin and lysozyme using mesoporous silica

The selective separation of biomolecules is a critical process in food, biomedical and pharmaceutical industries. Due to its size and properties, mesoporous silica offers many advantages as a separation media for biomolecules such as proteins and enzymes. In this paper, we investigate mathematically the separation of proteins trypsin and lysozyme using mesoporous silica materials. These proteins are modelled as densely packed spheres, while the silica pore is assumed to have a cylindrical structure. The Lennard-Jones potential together with a continuum approximation is employed to determine the interaction among the proteins and the interaction between a protein and a silica pore. For these systems, the total interaction energies are obtained analytically as functions of the protein size and the pore dimensions. We find that the pore radii which give rise to the maximum adsorption energies for trypsin and lysozyme are 21.74 A and 17.74 A, respectively. Since the binding energy between any two protein molecules is found to be three orders of magnitude lower than the adsorption energy of the protein into the silica pore, proteins prefer to be separated and stay inside the pore. Further, we find that using silica pores with radii in the range between 17.23 A and 21.24 A allows the entrance of only lysozyme, as such separating lysozyme from trypsin. These results agree with previous experimental study, confirming that mesoporous silica pores may be used to separate trypsin-lysozyme mixture

Gigahertz Oscillators Constructed from Carbon Nanocones Inside Carbon Nanotubes

In the production of carbon nanotubes usually only a small amount of carbon nanocones are produced, and for this reason, carbon nanocones seem to have received much less attention than other carbon nanostructures. Most of the research on carbon nanocones deals with their electronic structure since they are the ideal candidate for the probes of scanning tunneling microscopes. Here, we examine their oscillatory properties inside carbon nanotubes. Such calculations are necessary as a preliminary to creating such future nano-devices. We adopt the Lennard-Jones potential function together with the usual continuum approximation to determine the suction energy for a carbon nanocone entering a single-walled carbon nanotube. We show that a carbon nanocone located co-axially will be sucked into a carbon nanotube when the difference between the cone base radius and the tube radius exceeds 2.5 Å and this is irrespective of the direction of the vertex. We also show that the maximum suction energy occurs when these radii differ by 3.0 Å. We then examine the oscillatory behaviour of a nanocone once it is inside a nanotube and we obtain pulse-like forces at both ends of the tube which maintain the oscillatory motion along the tube length. On neglecting frictional effects and approximating the pulse-like forces by Dirac delta functions, Newton's second law is employed to determine the oscillation frequency. This is shown to be in the order of 15 to 90 gigahertz, which is the same order of magnitude which has been obtained for oscillating co-axial carbon nanotubes.Duangkamon Baowan, James M. Hil

Quantitative assessment of the normal cerebral microvasculature by endothelial barrier antigen (EBA) immunohistochemistry: application to focal cerebral ischemia

Cerebrovascular endothelium participates importantly in the pathophysiology of ischemic injury. Endothelial barrier antigen (EBA) is a protein located in the luminal plasma membrane of normal central and peripheral nervous-system endothelium. In this study, we assessed the sensitivity and specificity of EBA as a quantitative marker of normal endothelium and characterized alterations of EBA immunohistochemistry following focal cerebral ischemia. Anesesthetized, non-ischemic control rats ( N=6) were studied. Other animals ( N=5) received 90 min of middle cerebral artery occlusion (MCAo) followed by 3-day survival. Brains were prepared by perfusion-fixation and paraffin-embedding. For EBA immunohistochemistry, a monoclonal antibody (1:2000 dilution) was used. Adjacent sections were reacted for activated microglia by isolectin immunochemistry. Morphometric image-analysis was carried out in standardized microscopic fields. In control brains, pial and parenchymal blood vessels of all sizes were distinctly and selectively immunolabeled for EBA; background staining was absent. EBA-positive vascular profiles occupied 4.3±0.36% (mean±S.D.) of the microscopic field. The mean area of each identified profile was 51±13 μm 2. The low coefficients of variation for both numbers of profiles (17%) and fractional areas (8%) denoted high inter-animal consistency. In brains with prior MCAo, numbers of EBA-immunoreactive vascular profiles in infarcted cortex and striatum were reduced by 39 and 46%, respectively, and their fractional areas were decreased by 63 and 76%, respectively, compared to contralateral hemisphere. Activated microglia were prominent in zones of frank infarction and in adjacent paramedian cortex; the latter region, however, showed normal-appearing EBA-immunostaining. EBA-immunohistochemistry provides a sensitive and specific index of normal cerebrovascular endothelial structures of all sizes. The technique lends itself well to quantitative morphometry and is applicable to perfusion-fixed paraffin-embedded material. EBA immunoreactivity declines in zones of ischemic infarction

Equilibrium locations for nested carbon nanocones

Potentially, carbon nanostructures are very important as ideal components to create many novel nano-devices. Such devices including nano-oscillators, ultra-fast optical filters and nano-bearings, are based on the unique mechanical and electronic properties of carbon nano-structures. Common carbon nanostructures used are usually C60-fullerenes, carbon nanotubes, carbon nano-bundles and carbon nanotori. In the synthesis and production of carbon nanostructures, carbon nanocones tend to occur less frequently, and it is known that five different size cones may occur, depending on the number of pentagons in the atomic network. However, the simple geometric structure of carbon nanocones certainly facilitates calculations for their potential energy. Here, the Lennard–Jones potential energy function and the usual continuum approximation are employed to determine the energy for two such nested carbon nanocones which are located co-axially. We show graphically the energy profiles for any two carbon nanocones arising from the five possible structures. For both two distinct cones and two identical cones, we find that the equilibrium location moves further away from the vertex as the number of pentagons is increased. However, we observe that the equilibrium position occurs such that one cone is always inside the other, and therefore, we might expect that nested double-cones are formed according to these results.Duangkamon Baowan and James M. Hil