LOADING, CHARGING AND THERMAL EFFECTS ON THE MECHANISM OF WATER–CARBON NANOTUBE TRANSMISSION

2013 ◽  
Vol 02 (03n04) ◽  
pp. 1350017 ◽  
Author(s):  
ZHONG-QIANG ZHANG ◽  
HONG-FEI YE ◽  
YONG-GANG ZHENG ◽  
GUANG-GUI CHENG ◽  
JIAN-NING DING ◽  
...  
Keyword(s):  
Thermal Effects ◽  
Slip Velocity ◽  
Electromechanical Coupling ◽  
Transmission Mechanism ◽  
Dynamics Simulation ◽  
Confined Water ◽  
Dynamic Motion ◽  
Starting Process ◽  
A Charge ◽  
Better Than

In this paper, the transmission mechanism of a charge-controlled water–carbon nanotubes (CNTs) fluidic transmitting nanodevice is investigated by using molecular dynamics simulation with the loading, charging and thermal effects on the starting process being considered. The results show that the external load on the driven CNT can slow down the startup speed of the nanotransmission while the transmitting stability is better than that in non-loading transmitting process. The startup speed of the water–CNTs transmission increases with the increase in the charge magnitude on CNTs since the charges on CNT atoms can increase the water–CNT interfacial coupling strength. The control of the water temperature can also affect the startup speed of the driven CNT attributed to the thermal effect on the slip velocity of confined water. The configuration, dynamic motion behaviors and temperature of the confined water in both the starting and steady transmitting processes are studied to understand the thermo-electromechanical coupling effects on the transmission mechanism of the water–CNTs charge-controlled fluidic transmitting nanodevice.

Thermal Considerations in Lens Regulator Systems

1970 ◽  
Vol 28 ◽  
pp. 358-359
Author(s):  
K.C. Newton
Keyword(s):  
Electron Microscope ◽  
Thermal Effects ◽  
Environmental Control ◽  
Reference Networks ◽  
Better Than

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.

The Effect of Magnetic Field on the Hydration of Nanoscopic Hydrophobic N-Alkane Plates

2011 ◽  
Vol 228-229 ◽  
pp. 1007-1011
Author(s):  
Wei Wei Zhang ◽  
Long Qiu Li ◽  
Guang Yu Zhang ◽  
Hui Juan Dong
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Dynamics Simulation ◽  
Free Energy Barrier ◽  
Confined Water ◽  
Magnetic Exposure ◽  
Hydrophobic Solutes ◽  
The Magnetic Field ◽  
Density Of Water ◽  
Induced Adsorption

The effect of an external magnetic field on the hydration behavior of nanoscopic n-octane plates has been extensively investigated using molecular dynamics simulation in an isothermal-isobaric ensemble. The solute plates with different intermolecular spacing have also been considered to examine the effect of the topology of hydrophobic plates on the adsorption behavior of confined water in the presence of an external magnetic field with an intensity ranging from 0.1T to 1 T. The results demonstrate that magnetic exposure decreases the density of water for the plates with intermolecular spacing of a0 = 4 and 5 Å. This suggests that the free energy barrier for evaporation can be lowered by the applied field, and the hydrophobic solutes consisting of condensed n-octane molecules are apt to aggregate in the aqueous solution. In contrast, the magnetic field improves the dissolution or wetting of solutes comprised of loosely packed n-octane plates of a0=7Å. A magnetic-field-induced adsorption-to-desorption translation, which is in agreement with the experimental results provided by Ozeki, has also been observed for the plates with intermolecular spacing of a0 = 6 Å.

Phenylbenzopyrone of flavonoids as a potential scaffold to prevent SARS-CoV-2 replication by inhibiting its MPRO main protease

2021 ◽  
Vol 22 ◽  
Author(s):  
Angamba Meetei Potshangbam ◽  
Potshangbam Nongdam ◽  
A. Kiran Kumar ◽  
R.S. Rathore
Keyword(s):  
Antiviral Drugs ◽  
Dynamics Simulation ◽  
Compound Libraries ◽  
Main Protease ◽  
Enterovirus A71 ◽  
Short Period ◽  
Novel Coronavirus ◽  
Effective Drugs ◽  
Drug Leads ◽  
Better Than

Background: In December 2019, an outbreak of a pneumonia-like illness, Coronavirusdisease-2019 (COVID-19), originating from Wuhan, China was linked to novel coronavirus, now termed SARS-CoV-2. Unfortunately, no effective drugs or vaccines have been reported yet. The main protease (MPRO) remains the most validated pharmacological target for the design and discovery of inhibitors. Objective: The purpose of the study was to find a prospective natural scaffold as an inhibitor for MPRO main protease in SARS-CoV-2 and compare it with repurposed antiviral drugs lopinavir and nelflinavir. Methods: Natural compound libraries were screened for potential scaffold against MPRO main protease. Molecular dynamics simulation, MM-GBSA and principle component analyses of enzyme-ligand complexes were carried out with the top-ranking hits and compared with the repurposed antiviral drugs lopinavir and nelfinavir. Results: The structure-based virtual screening indicated phenylbenzopyrone of flavonoids as one of the top-ranking scaffolds that have the potential to inhibit the main protease with O-glycosidic form performing better than corresponding aglyconic form. Simulation studies indicated that glycosidic form of flavonoid as more suitable inhibitor with compounds rutin, procyanidin B6, baicalin and galloylquercetin, demonstrating high affinity and stability, and rutin emerging as one of the best candidate compound. Interestingly, rutin was reported to have inhibitory activity against similar protease (3Cprotease of enterovirus A71) as well as implicated in lung fibrosis. Conclusion: The present study displaying flavonoids, possessing a potential scaffold for inhibiting main protease activity for all betacoronavirus is an attempt to provide new and safe drug leads within a reasonably short period.

Dynamics Simulation of Capsule Filling Machine Based Virtual Prototype

2011 ◽  
Vol 127 ◽  
pp. 582-587 ◽  
Author(s):  
Gui He Wang ◽  
Yong Guo Zhang ◽  
Tian Biao Yu ◽  
Wan Shan Wang
Keyword(s):  
Lagrange Multiplier ◽  
Geometric Model ◽  
Equations Of Motion ◽  
Virtual Prototype ◽  
Transmission Mechanism ◽  
Lagrange Multiplier Method ◽  
Dynamics Simulation ◽  
Multiplier Method ◽  
Interface Module

Capsule filling machine is the key filling equipment for pharmaceutical capsule preparations. Taking NJP3400 type of capsule filling machine as an example, we analyze its principle and characteristics successfully. First, we built its geometric model with Pro/E software, established the equations of motion of transmission mechanism with Lagrange multiplier method and showed the process of solving the equations with GSTIFF software. With the interface module called mechpro of PRO-ADAMS, the model was imported into ADAMS, and then, we analyze the machine’s strength, displacement, acceleration and the association of these parameters.

Experimental study and molecular dynamics simulation of wall slip in a micro-extrusion flowing process

2011 ◽  
Vol 225 (5) ◽  
pp. 1175-1190 ◽  
Author(s):  
D Zhao ◽  
Y Jin ◽  
M Wang ◽  
M Song
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulation ◽  
Slip Velocity ◽  
Polymer Melts ◽  
Critical Shear Stress ◽  
Wall Slip ◽  
Dynamics Simulation ◽  
Desorption Mechanism ◽  
Adsorption Desorption

Wall slip is one of the most important characteristics of polymer melts’ elasticity behaviours as well as the most significant factor which affects the flow of polymer melts. Based on the traditional Mooney method, through a double-barrel capillary rheometer, the relationship between velocities of wall slip, shear stress, shear rate, diameters of dies, and temperature of polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), and polymethylmethacrylate (PMMA) is explored. The results indicate that the velocities of the wall slip of PP and HDPE increase apparently with shear stress and slightly with temperature. Meanwhile, the rise of temperature results in the decrease of critical shear stress. The wall-slip velocities of PS and PMMA are negative which means that the Mooney method based on the adsorption–desorption mechanism has determinate limitation to calculate the wall-slip velocity. Based on the entanglement–disentanglement mechanism, a new wall-slip model is built. With the new model, the calculation values of velocity of PP and HDPE correspond to the experimental values very well and the velocities of PS and PMMA are positive. The velocities of PS and PMMA increase obviously with the rise of shear stress. The rise of temperature results in the increase of velocity and decrease of critical shear stress. Then, the molecular dynamics simulation is used to investigate the combining energy between four polymer melts and the inside wall. The results show that at the given temperature and pressure, the molecules of PS and PMMA combine with atoms of the wall more tightly than those of PP and HDPE which means when wall slip occurs, the molecules of PS and PMMA near the wall will adsorb to the surface of the wall. However, those of PP and HDPE will be easy to slip. Therefore, the wall-slip mechanism of PP and HDPE is the adsorption–desorption mechanism, and that of PS and PMMA is the entanglement–disentanglement mechanism. According to the different wall-slip mechanisms of four polymers, an all-sided calculation method of wall-slip velocity is raised which consummates the theory of wall slip of polymer melts.

Thermal Effects on the Anchoring of Flexible Pipe Tensile Armors

2015 ◽  
Author(s):  
Olaf O. Otte Filho ◽  
Rafael L. Tanaka ◽  
Rafael G. Morini ◽  
Rafael N. Torres ◽  
Thamise S. V. Vilela
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Effects ◽  
Current Model ◽  
Element Model ◽  
Small Scale ◽  
Flexible Pipe ◽  
System A ◽  
Flexible Pipes ◽  
Better Than

In the design of flexible pipes, predict the anchoring behavior on end fittings is always challenging. In this sense, Prysmian Surflex has developed a finite element model, which should help the end fitting design as well the prediction of the structural behavior and the acceptable maximum loads. The current model considers that the contact between armor-resin is purely cohesive and has been suitable for the design of end fittings [1] and [2]. But tests and new studies [3] and [4] indicate that only cohesive assumption would not be the best approach. Experimental data from prototype tests also show that the current model would not predict acceptable results for loads higher than those used in previous projects. This document will describe a study developed considering the friction and thermal contraction, instead of the cohesive phenomenon in the anchoring behavior analysis. Small scale tests were conducted in order to understand the anchoring relation between the resin and the wire used in the tensile armor. For this purpose, a special test device was developed to simulate an enclosure system. A parametric study was also performed to identify the cooling temperatures, coefficients of friction and contact properties parameters taken from small scale tests. The finite element model considers the thermal effects during exothermic curing. Using the new parameters obtained, a second model was developed. This model consists of only one real shaped bended wire inside an end fitting cavity. To validate the model, samples were tested on laboratory according anchoring design. The results of this round of tests were studied and corroborate the argument that use friction and thermal effects is better than use only the cohesive condition.

Molecular Dynamics Simulation of Rarefied Gaseous Flows in Nano-Channels

2013 ◽  
Vol 446-447 ◽  
pp. 12-17
Author(s):  
Zhi Hong Mao ◽  
Fu Bing Bao ◽  
Yuan Lin Huang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Slip Velocity ◽  
Average Velocity ◽  
Single Layer ◽  
Simulation Method ◽  
Dynamics Simulation ◽  
Channel Height ◽  
Gaseous Flows ◽  
Pressure Driven

Molecular dynamics simulation method was used to study the rarefied gaseous flows in nanochannels. A pressure-driven force was introduced to drive the gas to flow between two parallel walls. The effects of driven force magnitude and channel height were investigated. The results show that a single layer of gaseous molecules is adsorbed on the wall surface. The density of adsorption layer decreases with the increase of channel height, but doesnt vary with driven force. The velocity profile across the channel has the traditional parabolic shape. The average velocity and gas slip velocity on the wall increase linearly with the increase of pressure-driven force. The gas slip velocity decreases linearly with the increase of channel height. The ratio of slip to average velocity decreases linearly with the increase of channel height.

scholarly journals Triboelectricity and friction. VII.—Quantitative results for metals and other solid elements, with silica

1932 ◽  
Vol 138 (836) ◽  
pp. 502-514 ◽  
Keyword(s):  
Constant Pressure ◽  
Differential Treatment ◽  
The Other ◽  
Silica Tube ◽  
Constant Length ◽  
Single Spot ◽  
Quantitative Results ◽  
Charged System ◽  
A Charge ◽  
Better Than

For research in triboelectricity ( i. e. , frictional electricity), metals and silica are pre-eminently suitable; they are hard, chemically simple, and their surfaces can easily be cleansed. Systematic work on these materials is described in a previous paper of this series. We have gone over the ground again using improved apparatus and methods; and the results, which in the earlier paper were little better than qualitative, may now claim quantitative rank. Comparison of the two sets of results shows that they are in substantial qualitative agreement. The process throughout this series of papers is to rub one solid on the other in a machine which maintains constant pressure and constant length of rub; in the present case a metal or other rod is rubbed on a silica tube. The silica is surrounded in part by a metal inductor connected by wire to an electrometer, so that the charge produced by friction on the silica induces a charge on the inductor and electrometer. A reading is taken on the electrometer; and by calibrating the system with known voltages, the electrometer readings are known in volts. Since the capacity of the charged system remains constant, the charges generated vary as the readings in volts. The former method of rubbing the surfaces is shown in fig. 1 ( a ) where the upper rod A in its stroke bears with one spot on a succession of spots of the lower rod B. Thus the single spot in the upper rod rubbed throughout the stroke becomes hotter and more strained than any spot on the lower rod. Such differential treatment of the two surfaces with its complicating effect on the physical action of the friction, we now avoid, as follows: place the lower rod at 45° to the line of run of the upper one, fig. 1 ( b ), so that when A moves forward, a succession of points on it come in contact with a succession of points in B. In this way the treatment of the two surfaces is equalised.

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