Viewing the noise propagation mechanism in a unidirectional transition cascade from the perspective of stability

Noise and noise propagation are inevitable and play a constructive role in various biological processes. The stability of cell homeostasis is also a critical issue. In the unidirectional transition cascade of colon cells, stem cells (SCs) are the source. They differentiate into transit-amplifying cells (TACs), and TACs differentiate into fully differentiated cells (FDCs). Two differentiation processes are irreversible. The stability factor is introduced so that the noise propagation mechanism from the perspective of stability is studied according to the noise propagation formulas. It is found that the value of the stability factor corresponding to the minimum noise in FDCs may be the best choice to enable colon cells to maintain high stability and low noise of the cascade. Moreover, for the source cell, the total noise only includes intrinsic noise; for the downstream cell with self-proliferation capability, the total noise mainly depends on its intrinsic noise and transmitted noise from upstream cells, and its intrinsic noise is dominant. For the downstream cell without self-proliferation capability, the total noise is mainly determined by transmitted noises from upstream cells, and there is a minimum value. This work provides a new approach for studying the mechanism of noise propagation while considering the stability of cell homeostasis in biological systems.     

Impact of Thermal Fluctuations on Logarithmic Corrected Massive Gravity Charged Black Hole

We investigate the influence of the first-order correction of entropy caused by thermal quantum fluctuations on the thermodynamics of a logarithmic corrected charged black hole in massive gravity. For this black hole, we explore the thermodynamic quantities, such as entropy, Helmholtz free energy, internal energy, enthalpy, Gibbs free energy and specific heat. We discuss the influence of the topology of the event horizon, dimensions and nonlinearity parameter on the local and global stability of the black hole. As a result, it is found that the holographic dual parameter vanishes. This means that the thermal corrections have no significant role to disturb the holographic duality of the logarithmic charged black hole in massive gravity, although the thermal corrections have a substantial impact on the thermodynamic quantities in the high-energy limit and the stability conditions of black holes.     

CaTiO3基微波介质陶瓷的频率温度稳定性

通过对克劳修斯-莫索蒂方程的近似, 分析了钙钛矿结构微波介质陶瓷频率温度系数 (τ_f) 的主要影响因素, 发现改变材料介电响应中离子位移极化和电子位移极化的比例, 可调节频率温度系数的正负与大小. 通过电子结构计算和容忍因子分析, 预测引入(Zn_1/3Nb_2/3)⁴⁺对具有正温度系数 的CaTiO₃进行B位取代将提高材料电子极化响应比例, 调节τ_f由正变负. 采用偏铌酸盐为前驱体, 通过固相反应法合成了Ca[(Zn_1/3Nb_2/3)_xTi_(1-x)]O₃钙钛矿结构陶瓷, 并对其进行结构分析和性能测试, 实验结果与理论分析一致, 获得了具有近零频率温度系数的Ca[(Zn_1/3Nb_2/3)_0.7Ti_0.3]O₃介质陶瓷材料. 关键词： B位复合钙钛矿陶瓷 谐振频率温度稳定性 极化机理 6八面体倾斜')" href="#">BO₆八面体倾斜     

短波长自由电子激光器电子运动特性研究

短波长自由电子激光器的电子束在摇摆器中的传输通道长而狭窄, 须得电子具有良好的运动特性, 避免在传输过程中产生横向发散. 本文研究短波长自由电子激光器中超相对论电子在磁场具有横向分布的平面摇摆器中的三维运动特性, 用逐次逼近法推导相对论运动方程的解析表达式, 非线性数值计算模拟传输过程, 采用科尔莫 戈罗夫熵 方法分析运动的稳定性. 结果表明: 摇摆器磁场除使电子做周期性摇摆运动外, 还迭加了偏离轴线的横向漂移运动, 在没有外置的磁场聚焦系统情况下, 电子将偏离轴线横向发散; 但是, 恰当选取电子的横向初始速度, 可有效地防止电子运动的横向发散, 即使没有外置的磁场聚焦系统, 也能在长达10 m 的摇摆器中顺利传输, 横向位移范围不超过0.09 mm, 而且其运动是稳定的. 关键词： 短波长自由电子激光器 平面摇摆器 超相对论电子运动 运动稳定性     

铀的结构相变及力学性能的第一性原理计算

基于密度泛函理论, 分别计算了α, γ铀的晶格常数、平衡态体积、体弹模量及其导数等, 与实验和其他第一性原理计算结果符合较好; 并根据焓-压强曲线得到了两相的相变压强～111GPa. 通过体心立方结构理想拉伸强度的计算, 分析其在极端加载条件下的结构行为. 另外, 计算了小应变情况下U-Nb (6.25at.%) 的能量-应变关系, 发现对应于剪切模量c’的应变会使得该结构的能量降低, 揭示了该结构的力学不稳定性. 关键词： 铀 相变 理想强度 结构稳定性     

一阶Lagrange系统的梯度表示

研究一阶Lagrange系统的梯度表示. 给出一阶Lagrange系统可成为梯度系统的条件. 利用梯度系统的性质研究系统的稳定性. 给出例子说明结果的应用. 关键词： 一阶Lagrange系统 梯度系统 稳定性     

Towards a unified view of fluids

It has traditionally been believed that, unlike normal fluids whose structural properties are determined primarily by the intermolecular short-range repulsive interactions, the properties of polar and associating fluids are strongly affected by the long-range Coulombic interactions. In the course of investigations to determine the primary driving forces governing the behaviour of various (non-simple) fluids, and hence to gain a deeper understanding of the molecular mechanisms leading to the development of theoretically based simple models and theory, extensive and systematic computer simulations have been performed on typical quadrupolar (carbon dioxide), dipolar (acetone and acetonitrile), and associating (hydrogen fluoride, methanol, and water) fluids using the available realistic effective pair potentials and their variants involving forces of different ranges. In addition to the main structural characteristics (one- and two-dimensional site–site correlation functions, local g factors, and radial slices through the full pair correlation function), the dielectric constants and the thermodynamic properties (internal energy and pressure) of both the homogeneous liquid and supercritical fluid phases, and vapor–liquid equilibria have also been considered. Furthermore, in the case of water, the diffusion coefficient and viscosity have also been considered along with water at the interface. All the obtained results lead to the unambiguous conclusion that the structure, defined in terms of the complete set of site–site correlation functions, for both polar and associating pure fluids is governed by the same molecular mechanism as for normal fluids, i.e. by the short-range interactions (which, however, may be both repulsive and attractive), whereas the long-range part of the electrostatic forces, regardless of their strength, plays only a marginal role and may be treated as a perturbation only. The consequences of these findings for theory and applications are also discussed.     

The Mechanical Properties,Compatibility, and Thermal Stabilities of POE-Graft-Methyl Methacrylate and Acrylonitrile(POE-g-MAN)/ Styrene-Acrylonitrile Copolymer (SAN Resin) Blends

POE-graft-methyl methacrylate and acrylonitrile (POE-g-MAN) was prepared by graft copolymerization of methyl methacrylate (MMA) and acrylonitrile (AN) onto polyethylene-octene copolymers (POE) with suspension polymerization. POE-g-MAN/SAN resin blends (AOMS) were prepared by blending POE-g-MAN with styrene-acrylonitrile copolymer (SAN resin). The mechanical properties, compatibility, and thermal stabilities of AOMS were studied. The notched impact strength of the blends reached 54.0 kJ/m² when the AN/(MMA + AN) ratio (f_AN) of POE-g-MAN, benzoyl peroxide dosage, and POE content in AOMS were 15 wt%, 1.0 wt%, and 25 wt%, respectively. Transmission electron microscopy analysis showed that the highest toughness occurred when the size of POE-g-MAN particles and the surface-to-surface inter-particle distance were proper. Scanning electron microscopy analysis indicated that the AOMS fracture surface had plastic flow visible, which looked like a fibril morphology when the AN/(MMA + AN) ratio (f_AN) of POE-g-MAN was 15 wt%. The toughening mechanism of AOMS was shear yielding of the matrix, which endowed AOMS with remarkable toughness. Dynamic mechanical thermal analysis showed that the compatibility of the POE phase and SAN phase improved after graft copolymerization of MMA and AN onto POE. When the grafting chain polarity was appropriate, the miscibility between POE-g-MAN and SAN resin was the best. Thermogravimetry analysis showed that thermal stability of AOMS increased with increasing AN units in POE-g-MAN.     

Small-Angle and Wide-Angle X-Ray Scattering Study of Slow Relaxation Following Phase Transitions of New Bolaamphiphiles Based on N-(12-Betainylamino-Dodecane)-octyl β-D-Glucofuranosiduronamide Chloride

In the present study, we investigated the polymorphism and its time-dependence of a new series of bolaamphiphile molecules based on N-(12-Betainylamino-dodecane)-octyl β-D-Glucofuranosiduronamide Chloride. To obtain six members of this series, the length of the main bridging chain and the lateral chain were varied in order to modify the hydrophilic–lipophilic balance. Another chemical modification was to introduce a diacetylenic unit in the middle of the bridging chain to study the influence of the π–π stacking on the supramolecular organization of these molecules. Dry bolaamphiphiles self-organize in supramolecular structures such as lamellar crystalline structure, L_c; lamellar gel structure, L_β′; lamellar fluid structure, L_α; and lamellar isotropic structure, L. Thermal hysteresis of these structures, following phase transitions, are investigated by small-angle and wide-angle X-ray scattering. Once the thermal cycle is accomplished, the system remains in the kinetically stabilized undercooled high-temperature phase at the temperature of 20°C. Subsequently, the time-dependence of the relaxation to the thermodynamically stable phase is followed, and very slow relaxation for a period on the order of hours or days is observed. The study of the polymorphism and the stability of various phases of this new series of bolaamphiphiles—which are issued from natural primary resources (sugar beet and wheat) and thus interesting for potential application in pharmaceutical, cosmetics, or food industry—was undertaken in this work.