Reaction and transport in active chemcal systems

* 使用化学反应来驱动其动力学的活性复杂系统在自然界中无处不在。术语“活性系统”具有广泛的用途，但本研究的重点是致密系统，其活性溶质或悬浮物质是自推进的或由于化学反应而经历构象变化。我们的目标是发现控制主动系统行为的因素，以便在基本层面上了解它们如何运作，以及如何将这些知识转化为构建可以在分子尺度上运作的自主设备的建议。 ** 扩散是控制溶液中溶质分子运动的主要机制，并使它们在可以发生反应的地方接触。这个过程是非特异性的，而且往往很慢。虽然扩散在生物领域是必不可少的，但利用分子马达，生物系统已经设计出更有效的方式来运输物种。我们的兴趣没有理由局限于这些生物分子发动机，合成分子机器和发动机已经在实验室中构建出来。特别是，使用化学能产生定向运动的自推进式微米和纳米级马达已经被制造并用于与药物输送、化学传感、污染物去除和靶向癌细胞等相关的原理验证研究。这些研究指出了这些合成马达的许多潜在的化学，医学和材料科学应用。像它们的生物对应物一样，这些微小的马达受到周围介质的强烈冲击，尽管如此，它们必须能够发挥作用。设计用于应用的这种合成马达需要了解它们如何在各种条件下、在复杂环境中以及通过它们的集体运动而协调一致地操作。 虽然迄今为止研究的大多数合成自推进马达具有微米级尺寸，但未来的应用将涉及具有更小分子尺寸的合成马达。 基本的理论挑战出现了分子尺度的合成化学动力马达的描述。它们的分辨率是拟议研究的主要目标。 这一知识对于非常小规模的应用至关重要，即使是在细胞内部。其他类型的活性物质可能更熟悉：在细胞或溶液中经历催化循环的酶。 与上面讨论的马达类似，这些蛋白质机器使用化学能进行动作，并在非常强烈的热波动存在下运行。由于细胞中充满了各种大分子物质，包括活性酶本身，因此将探索活性非热酶构象运动的性质，以确定它在运输和化学动力学中所起的作用。

***Active complex systems that use chemical reactions to drive their dynamics are ubiquitous in nature. The term “active systems” has a broad usage, but the focus of this research is on dense systems whose active solute or suspended species are either self-propelled or undergo conformational changes as a result of chemical reactions. Our aim is to discover the factors that control the behavior of active systems in order to understand, at a fundamental level, how they operate and how this knowledge can be translated into proposals for the construction of autonomous devices that can operate on molecular scales. ******Diffusion is the main mechanism that controls the motion of solute molecules in solution and brings them into contact where reactions can take place. This process is nonspecific and often slow. Although diffusion is essential in the biological realm, using molecular motors, biological systems have devised more efficient ways to transport species. There is no reason why our interest should be confined to these biological molecular motors and synthetic molecular machines and motors have been constructed in the laboratory. In particular, self-propelled micron and nano-scale motors that use chemical energy to produce directed motion have been made and used in proof-of-principle studies related to drug delivery, chemical sensing, pollutant removal and targeting cancer cells, among others. These studies have pointed to the many potential chemical, medical and materials science applications of these synthetic motors.******Like their biological counterparts, these tiny motors are strongly buffeted by the surrounding medium and they must be able to function in spite of this. The design of such synthetic motors for use in applications requires knowledge of how they operate under various conditions, in complex environments and in concert through their collective motions. While most synthetic self-propelled motors studied to date have micron-scale dimensions, future applications will involve such synthetic motors with even smaller molecular dimensions. Fundamental theoretical challenges arise for the description of molecular-scale synthetic chemically-powered motors. Their resolution is a main goal of the proposed research. This knowledge is essential for applications on very small scales, even in the interior of the cell.******Other types of active species are perhaps more familiar: enzymes undergoing catalytic cycles in the cell or in solution. Similar to the motors discussed above, these protein machines use chemical energy for their action and operate in the presence of very strong thermal fluctuations. Since the cell is crowded by various macromolecular species, including the active enzymes themselves, the nature of active non-thermal enzyme conformational motion will be explored in order to determine the roles it plays in transport and chemical dynamics.********