共查询到20条相似文献,搜索用时 11 毫秒
1.
研究具有幂律记忆性的细胞液中双头分子马达的定向输运现象,选取幂函数作为广义Langevin方程的阻尼核函数,建立了分数阶过阻尼耦合Brown马达模型,讨论了阶数及耦合系数对双头分子马达定向输运速度的影响. 仿真结果表明,分数阶过阻尼双头分子马达也会产生定向输运现象,并且在某些阶数下会产生整数阶情形所不具有的反向定向流. 当噪声强度固定时,输运速度随着阶数以及耦合系数的变化均会出现广义随机共振现象. 特别地,研究发现双头分子马达在记忆闪烁棘轮势中具有某些单头分子马达所不具备的运动特性,定向流的大小和方向由噪声与双头间作用力相互耦合控制.
关键词:
分数阶双头分子马达
欠扩散
定向输运
广义随机共振 相似文献
2.
Molecular motors are proteins or protein complexes which
function as transporting engines in biological cells. This paper
models the tether between motor and its cargo as a symmetric linear
potential. Different from Elston and Peskin's work for which
performance of the system was discussed only in some limiting cases,
this study produces analytic solutions of the problem for general
cases by simplifying the transport system into two physical states,
which makes it possible to discuss the dynamics of the motor--cargo
system in detail. It turns out that the tether strength between
motor and cargo should be greater than a threshold or the motor will
fail to transport the cargo, which was not discussed by former
researchers yet. Value of the threshold depends on the diffusion
coefficients of cargo and motor and also on the strength of the
Brownian ratchets dragging the system. The threshold approaches a
finite constant when the strength of the ratchet tends to infinity. 相似文献
3.
分子马达的梯跳运动和在过阻尼溶液中动力学原理尚未揭示清楚, 从分子马达输运特点和实验现象出发, 构建满足朗之万方程的单向能量跃迁模型, 并通过Monte Carlo方法分析了分子马达的随机动力学行为. 结果表明, 在合适的跃迁能量作用下, 分子马达可以利用噪声进行稳定的梯跳运动和有效的输运, 但负载力会减弱分子马达系统的输运能力; 轨道周期势虽影响分子马达速度的大小但不会改变其运动方向, 分子马达运动方向由跃迁能量决定; 另外, 虽然在不同的噪声强度时平均速度不为零, 但是分子马达系统的高效输运对噪声有一定选择性.
关键词:
分子马达
能量跃迁
朗之万方程
噪声强度 相似文献
4.
Takanori Kozai Yuya Kayano Takahito Aoi Noriaki Tsurumachi Shunsuke Nakanishi 《Journal of Raman spectroscopy : JRS》2015,46(4):384-387
We have studied the coherent molecular vibrational dynamics of CH2 stretching modes in polyethylene by time‐resolved femtosecond coherent anti‐Stokes Raman spectroscopy. We observed that the coherent vibrational relaxation of symmetric CH2 stretching modes in polyethylene at room temperature is much faster than that previously measured in polyvinyl alcohol. In addition, it was detected that, at low temperature, the coherent vibrational relaxation of the symmetric stretching modes evidently becomes slower compared with that at room temperature. These temperature‐dependent measurements enable us to discriminate the contribution of pure dephasing mechanism, due to phonons and two‐level systems in polymer, from the contribution of lifetime of the vibrational excited state to the coherent vibrational relaxation of CH2 stretching modes. We conclude that the coherent vibrational relaxation of symmetric CH2 stretching modes at room temperature consists of the contribution of lifetime and approximately 1.5 times larger contribution of pure dephasing. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
Kenichi SUGAWARA 《Physical Therapy Research》2020,23(2):106
For central nervous system disorders'' rehabilitation, it is important to accurately understand motor control and implement an appropriate motor learning process to induce neuroplastic changes. The neurophysiological studies have revealed that neural control mechanisms are crucial during both the onset of muscular activities and muscle release after contraction. When performing various movements during daily activities, muscle relaxation control enables precise force output and timing control. Moreover, surround inhibition is a functional mechanism in the motor system. Surround inhibition of the motor system may be involved in the selective execution of desired movements. This review demonstrates cortical excitability resulting from motor learning, movement control mechanisms including muscle relaxation and the suppression of nontarget muscle groups, and the voluntary drive''s importance that is required for movement. 相似文献
6.
物质分子振动退相时间测量是一种非标记无损分子检测方法, 用超连续谱时间分辨相干反斯托克斯拉曼散射方法可同时获得分子振动谱和退相时间. 实验以苯甲腈和甲醇为样品, 研究当分子环境变化时, 其主要振动谱的振动退相时间变化情况. 将苯甲腈与无水乙醇混合, 测量了苯甲腈分子1017, 2247和3085 cm-1三个典型分子振动的退相时间随环境变化的规律, 并得到了变化后的振动退相时间. 测量了甲醇分子2851, 2960 cm-1两个相邻分子振动的退相时间随环境的变化情况, 给出实验变化规律. 这种方法具有检测分子所处环境变化和分子相互作用的能力, 在生命科学、分子生物学和材料科学等研究领域中具有重要的应用前景. 相似文献
7.
The IR absorption and Raman spectra of the following complex compounds based on thiocyanates and crown ethers have been studied: KSCN-18-crown-6, KSCN-dibenzo-18-crown-6, NaSCN-dibenzo-18-crown-6, and NaSCN-benzo-15-crown-5. The shape of the contour of the spectral line corresponding to the stretching vibration 1(CN) of the thiocyanate ion in the indicated compounds in the temperature interval involving solid and liquid phases have been investigated for the first time. The reorientation parameters and molecular-relaxation characteristics of the thiocyanate ion in the crown compounds have been calculated. It is found that an increase in temperature leads to gradual freeing of cations and to the properties of crown compounds becoming identical to those of pure salt melts.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 23–27, January–February, 2005. 相似文献
8.
9.
During the assembly of many viruses, a powerful molecular
motor packages the genome into a preassembled capsid. The Bacillus
subtilis phage φ 29 is an excellent model system to investigate
the DNA packaging mechanism because of its highly efficient
\textitin vitro DNA packaging activity and the development of a
single-molecule packaging assay. Here we make use of structural and
biochemical experimental data to build a physical model of DNA
packaging by the φ 29 DNA packaging motor. Based on the model,
various dynamic behaviours such as the packaging rate, pause
frequency and slip frequency under different ATP concentrations, ADP
concentrations, external loads as well as capsid fillings are
studied by using Monte Carlo simulation. Good agreement is obtained
between the simulated and available experimental results. Moreover,
we make testable predictions that should guide future experiments
related to motor function. 相似文献
10.
11.
Th. Gomti Devi 《Journal of Raman spectroscopy : JRS》2010,41(10):1261-1265
The vibrational relaxation and molecular reorientational processes in liquids have been studied in some carbonyl‐containing molecules using the acetonitrile (ACN) solvent. The vibrational and reorientational processes have been studied in correspondence with correlation times. The screening effect due to dielectric has been studied and the Onsager reaction field model has been tested. The study shows that repulsive types of intermolecular forces play an important role in complex systems. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
R.F. Nalewajski 《Annalen der Physik》2004,13(4):201-222
The Fisher information contained in a probability distribution is summarized. The corresponding measures of the information distance, relative to the reference probability density, are introduced and discussed. These concepts are designed as analogues of the Kullback‐Leibler directed divergence and Kullback's divergence. For these alternative measures of the missing information the equilibrium (“stockholder”) scheme of Hirshfeld, of a division of the molecular electron density into the subsystem components, is derived from the minimum principle of the local or global entropy deficiency relative to the free‐subsystem (“promolecule”) reference. The local information distance densities are used to describe instantaneous electron distributions in molecular subsystems within a thermodynamic‐like approach to the density fluctuations and irreversible processes. The key concepts of such a local irreversible “thermodynamics” are introduced. They include the corresponding local affinities (forces) and the conjugate fluxes (responses), which together determine the local entropy deficiency source. These quantities depend on the adopted measure of the information distance and selected state‐parameters. For each such representation the relevant Onsager‐type reciprocity relations can be derived, which reflect the symmetries between the linear effects of affinities on fluxes. 相似文献
13.
使用针-板式电极装置,在大气压氮气介质阻挡微放电中,通过对氮分子第二正带系(C3Πu→B3Πg)发射光谱的时间分辨谱线进行分析,根据振动带序发射光谱强度计算得出N2(C,ν)振动温度,并研究了不同压强及放电电压对氮分子(C3Πu)的振动温度时间分辨的影响。实验结果表明:氮分子振动温度的范围为2 000~3 500 K,在每半个放电周期内都呈减小趋势,且正负半周期振动温度差较大,负半周期振动温度始终高于正半周期;振动温度随电压升高而升高,随压强的升高而降低。 相似文献
14.
We present in this work a review concerning wide frequency rangeT 1 proton NMR relaxation studies performed in compounds exhibiting columnar mesophases, namely the Colho mesophase in the case of a liquid crystal of discotic molecules and the øh mesophase in the case of a liquid crystal of biforked molecules. These NMR relaxation studies were performed combining conventional and fast field cycling NMR techniques in a frequency range between 100 Hz and 300 MHz. The possibility of probing such a large frequency range has provided a way to effectively distinguish the influence, on theT 1 relaxation profiles, of the different molecular movements observed in this type of mesophases. In addition, we present a comparison between the molecular dynamics in columnar (øh) and lamellar (SmC) mesophases exhibited by the same biforked compound. 相似文献
15.
16.
Theoretical investigations of spectroscopic parameters and molecular constants for electronic ground state of Cl2 and its isotopes 下载免费PDF全文
The potential energy curve of the Cl 2(X1Σg+) is investigated by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in combination with the largest correlation-consistent basis set, aug-cc-pV6Z, in the valence range. The theoretical spectroscopic parameters and the molecular constants of three isotopes, 35Cl2, 35Cl37Cl and 37Cl2, are studied. For the 35Cl2 (X1Σg+), the values of D0 , De , Re , ωe , ωeχe , αe and Be are obtained to be 2.3921 eV, 2.4264 eV, 0.19939 nm, 555.13 cm-1 , 2.6772 cm-1 , 0.001481 cm-1 and 0.24225 cm-1 , respectively. For the 35Cl37Cl(X1Σg+), the values of D0 , De , Re , ωe , ωeχe , αe and Be are calculated to be 2.3918 eV, 2.4257 eV, 0.19939 nm, 547.68 cm-1 , 2.6234 cm-1 , 0.00140 cm-1 and 0.23572 cm-1 , respectively. And for the 37C2 (X1Σg+), the values of D0 , De , Re , ωe , ωeχe , αe and Be are obtained to be 2.3923 eV, 2.4257 eV, 0.19939 nm, 540.06 cm-1 , 2.5556 cm-1 , 0.00139 cm-1 and 0.22919 cm-1 , respectively. These spectroscopic results are in good agreement with the available experimental data. With the potential of Cl2 molecule determined at the MRCI/aug-cc-pV6Z level of theory, the total of 59 vibrational states is predicted for each isotope when the rotational quantum number J equals zero (J = 0). The theoretical vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J = 0, which are in excellent accordance with the available experimental findings. 相似文献
17.
The nuclear molecular resonances observed in α+12C and α+16O systems are described in a diatomic-like molecular picture using a Morse-type bonding potential. The depths of the bonding
potentials are found to be 11.5 MeV and 11 MeV respectively, with long range of about 15 fm. Both the bound and resonance
states of these potentials are calculated which compare quite well with the observed states. The diatomic-like rotational
and vibrational picture of the quasi-molecular states proposed earlier for12C+12C system system is found to be quite valid for α+12C and α+16O systems. In these two systems, the rotational vibrational characteristics are equally well pronounced as in the12C+12C system. 相似文献
18.
The first accurate studies on the vibrational spectroscopic constants and the corresponding full vibrational energy spectra
of some electronic states of diatomic molecular ions XY+ were performed using algebraic method(AM). The AM is applied on the X1Σ+ state of BeH+, the X2Σ+ state of CO+, the X2Πg state of F
2
+
, the A2Πu state of O
2
+
and the X2Σ
g
+
state of Li
2
+
. The results show that AM can generate accurate vibrational spectroscopic constants as well as accurate full vibrational
energy spectra by using some accurate experimental vibrational energies, and that the AM vibrational energies are better than
other theoretical data.
__________
Translated from Chinese Journal of Atomic and Molecular Physics, 2005, 22 (4) (in Chinese) 相似文献
19.
Phosphorus spin-lattice relaxation was studied in aluminophosphate molecular sieves containing various concentrations of either framework or non-framework cobalt. The behaviour of nuclear magnetisation in the presence of these paramagnetic centres was described successfully in the limit of no spin-diffusion. The diffusionless regime was strongly indicated with non-exponential magnetisation recovery and was therefore easy to recognise. According to the model, spin-lattice relaxation rates depend on the square of cobalt concentration. Measured relaxation rates agreed well with calculations if effective cobalt concentration was considered rather than the average one. The latter was obtained by bulk elemental analysis, while the former was extracted from cobalt concentration depth-profiles measured with Auger electron spectroscopy. These measurements indicated that in impregnated samples containing non-framework cobalt there could be much more cobalt near the crystal surface than within the crystal. Because high cobalt concentration can lead to an invisible phosphorus, only nuclei deep within the crystal contribute to the NMR signal. In such a case, the effective concentration is simply the concentration of cobalt far from the crystal surface. In our case, two impregnated samples with different bulk cobalt concentrations exhibited equal relaxation rates. Previously, such a case was misinterpreted as a case, in which nuclear spin-lattice relaxation was independent of cobalt concentration. AES measurements, however, revealed, that although average concentrations of the two samples were different by a factor of two, their effective concentrations were equal and thus in complete agreement with observed relaxation rates. 相似文献