关键词： Modified atmosphere packaging   Gas transfer   Predictive microbiology   Mathematical modelling   Listeria monocytogenes  

摘要： A mechanistic model coupling O-2 and CO2 mass transfer (namely diffusion and solubilisation in the food itself and permeation through the packaging material) to microbial growth models was developed aiming at predicting the shelf life of modified atmosphere packaging (MAP) systems. It was experimentally validated on a non-respiring food by investigating concomitantly the O-2/CO2 partial pressure in packaging headspace and the growth of Listeria monocytogenes (average microbial count) within the food sample. A sensitivity analysis has revealed that the reliability of the prediction by this "super-parametrized" model (no less than 47 parameters were required for running one simulation) was strongly dependent on the accuracy of the microbial input parameters. Once validated, this model was used to decipher the role of O-2/CO2 mass transfer on microbial growth and as a MAP design tool: an example of MAP dimensioning was provided in this paper as a proof of concept. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： kinetics measurement   label-free detection   mechanical amplification   optical imaging   single cell   small molecule–membrane protein interaction in situ measurement  

摘要： Measuring small molecule interactions with membrane proteins in single cells is critical for understanding many cellular processes and for screening drugs. However, developing such a capability has been a difficult challenge. We show that molecular interactions with membrane proteins induce a mechanical deformation in the cellular membrane, and real-time monitoring of the deformation with subnanometer resolution allows quantitative analysis of small molecule-membrane protein interaction kinetics in single cells. This new strategy provides mechanical amplification of small binding signals, making it possible to detect small molecule interactions with membrane proteins. This capability, together with spatial resolution, also allows the study of the heterogeneous nature of cells by analyzing the interaction kinetics variability between different cells and between different regions of a single cell.

关键词： Hydrodynamic property   drag reduction effect   biological surface   mucus nano-long chain   sharkskin  

摘要： Natural selection, survival of the fittest. Through millions of years' evolution, shark has become one of the fastest swimming animals in the ocean, and it is very well-known for sharkskin effect, especially for "sharkskin swimsuit". Due to its great superior properties in drag reduction, anti-wear, self-cleaning and so on, the investigations on the essential mechanisms and fabricating methods have attracted so much attention from all over the world, and the achievements have been widely put into application in industry, agriculture, transportation, airspace and so on, and so lots of profits have been obtained so far. In this paper, the method of fabricating artificial composite drag reduction surface based on biological sharkskin morphology and mucus nano-long chain is investigated and studied, the chemical, mechanical and hydrodynamic properties are explored from different aspects in depth, in which, the experimental results in water tunnel showed that the drag-reducing efficiency could surpass 20% with the smooth skin as reference, and the drag reduction mechanism is systematically explained and discussed from different aspects, which has important significance to understand the recent research status and expand the applications of sharkskin in the fluid engineering.

关键词： Mechanistic explanation   Idealization and abstraction   Scale-free dynamics   Scale-free small world networks  

摘要： This paper considers two objections to explanations that appeal to mechanisms to explain biological phenomena. Marom argues that the time-scale on which many phenomena occur is scale-free. There is also reason to suspect that the network of interacting entities is scale-free. The result is that mechanisms do not have well-delineated boundaries in nature. I argue that bounded mechanisms should be viewed as entities scientists posit in advancing scientific hypotheses. In positing such entities, scientists idealize. Such idealizations can be highly productive in developing and improving scientific explanations even if the hypothesized mechanisms never precisely correspond to bounded entities in nature. Mechanistic explanations can be reconciled with scale-free constitution and dynamics even if mechanisms as bounded entities don't exist. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Thermoset polymer   Polymer network   Crosslink density   Molecular dynamics   Glass transition temperature   Structure property relationship  

摘要： Thermoset polymers are used for a wide range of application from large airframes to microelectronics and fundamental understanding of the development of their 3D network during cure and its relationship to thermo-mechanical properties is of fundamental and applied interest. Experimental characterization of network properties, such as the density of crosslinked chains, involves the use of approximate models with uncertain parameters leading, consequently, to uncertainties in resulting properties. We use molecular dynamics to simulate the cure of two thermoset epoxy systems, characterize the evolution of its network topology and establish relationships to the stiffness, yield stress and glass transition temperature. Relating the predicted crosslink density with experimental measurements of rubber elasticity indicates that these polymers behave somewhere between an affine and phantom networks;the proportionality constant extracted between rubber modulus and crosslink density can be used for similar systems to experimentally extract network characteristics. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： MOLECULAR dynamics   COMPUTER simulation   NANOELECTRONICS   GRAPHENE   TEMPERATURE measurements  

摘要： Stanene, a graphene like two dimensional honeycomb structure of tin has attractive features in electronics application. In this study, we performed molecular dynamics simulations using modified embedded atom method potential to investigate mechanical properties of stanene. We studied the effect of temperature and strain rate on mechanical properties of alpha-stanene for both uniaxial and biaxial loading conditions. Our study suggests that with the increasing temperature, both the fracture strength and strain of the stanene decrease. Uniaxial loading in zigzag direction shows higher fracture strength and strain compared to the armchair direction, while no noticeable variation in the mechanical properties is observed for biaxial loading. We also found at a higher loading rate, material exhibits higher fracture strength and strain. These results will aid further investigation of stanene as a potential nano-electronics substitute. (C) 2015 AIP Publishing LLC.

关键词： 食品机械   技术创新动力   模式分析   技术创新模式   食品领域   生产条件   市场拉动   产品合格率   技术创新工  

摘要： 食品与人民生活息息相关,食品机械技术的创新是目前最受瞩目的焦点之一。这一技术主要是指引进新的工艺、研发并制造出新的产品,从而在食品领域开拓出更为广阔的空间。在我国,食品机械技术的发展恰好抓住了市场经济的机遇,继而能够创造出更多发展和盈利的机会。食品机械技术的基本目标是通过进行各种生产条件和相关因素的组合,建立起效能更高和获利更高的生产模式,从而获取更高的利润。因此。

关键词： Excitation energies   Photons   Electric dipole moments   Time resolved spectroscopy   Electron transfer  

摘要： Dipole bound (DB) and valence bound (VB) anions of binary iodide-adenine complexes have been studied using one-color and time-resolved photoelectron imaging at excitation energies near the vertical detachment energy. The experiments are complemented by quantum chemical calculations. One-color spectra show evidence for two adenine tautomers, the canonical, biologically relevant A9 tautomer and the A3 tautomer. In the UV-pump/IR-probe time-resolved experiments, transient adenine anions can be formed by electron transfer from the iodide. These experiments show signals from both DB and VB states of adenine anions formed on femto- and picosecond time scales, respectively. Analysis of the spectra and comparison with calculations suggest that while both the A9 and A3 tautomers contribute to the DB signal, only the DB state of the A3 tautomer undergoes a transition to the VB anion. The VB anion of A9 is higher in energy than both the DB anion and the neutral, and the VB anion is therefore not accessible through the DB state. Experimental evidence of the metastable A9 VB anion is instead observed as a shape resonance in the one-color photoelectron spectra, as a result of UV absorption by A9 and subsequent electron transfer from iodide into the empty p-orbital. In contrast, the iodide-A3 complex constitutes an excellent example of how DB states can act as doorway state for VB anion formation when the VB state is energetically available. (C) 2015 AIP Publishing LLC.

关键词： phase difference   machinery pump   Nonlinear Dynamics  

摘要： Second-order sideband generation in a coherent-mechanical pumped optomechanical system is discussed, and the features of the coherent mechanical pump induced enhancement of second-order sideband generation are identified. We show that the coherent mechanical pump induced enhancement of second-order sideband generation exhibits an essential difference between the case of a weak control field and a strong control field. In the weak control field case, the efficiency of second-order sideband generation increases as the amplitude of the mechanical pump increases. In the strong control field case, the effect of optomechanically induced transparency occurs and increasing the amplitude of the mechanical pump does not always bring an enhancement of second-order sideband generation. The phase-dependent effect of the second-order sideband generation with a coherent mechanical pump is also discussed, and it is shown that the phase difference ϕ plays an important role in the process of second-order sideband generation.

关键词： 机床机械手   ADAMS   动力学仿真  

摘要： 文章以某企业自动化上下料机床机械为研究目标,构建了简化的机床机械手模型,然后把该模型导入到ADAMS进行后续的约束和驱动添加,从而获得机械手的虚拟样机。并通过运动仿真模拟了机械手关节的运动曲线,结果表明所建立模型正确性与合理性,为后续研究奠定了基础。