External control over the pore size of flexible metal–organic frameworks (MOFs) has recently emerged as an intriguing concept, with possible applications to gas storage and separation. In this work we present a new pressure cell capable for the first time of monitoring through in situ X‐ray powder diffraction an adsorbent powder under combined uniaxial applied mechanical stress (up to 1 GPa) and gas pressure (up to 20 bar). The combined stress–pressure clamp (CSPC) cell was successfully exploited to follow the evolution of the CO2 breathing behaviour of the prototypical complex breathing MIL‐53(Al) system under mechanical compression obtaining structural evidence that this MOF can be maintained in its closed pore state upon compression, precluding its re‐opening at high gas pressure (>7 bar). This novel setup shows potential for the in‐operando exploration of flexible systems, in equilibrium and flow configurations.

External control over the pore size of flexible metal-organic frameworks (MOFs) has recently emerged as an intriguing concept, with possible applications to gas storage and separation. In this work we present a new pressure cell capable for the first time of monitoring through in situ X-ray powder diffraction an adsorbent powder under combined uniaxial applied mechanical stress (up to 1 GPa) and gas pressure (up to 20 bar). The combined stress-pressure clamp (CSPC) cell was successfully exploited to follow the evolution of the CO 2 breathing behaviour of the prototypical complex breathing MIL-53(Al) system under mechanical compression obtaining structural evidence that this MOF can be maintained in its closed pore state upon compression, precluding its re-opening at high gas pressure (> 7 bar). This novel setup shows potential for the in-operando exploration of flexible systems, in equilibrium and flow configurations.Soft crystalline porous materials, such as metal-organic frameworks (MOFs) which can undergo substantial structural changes under the application of a variety of stimuli, have attracted significant scientific interest. [1][2][3] This is, in part, due to the promise they hold for unprecedented performance in applications like gas storage, gas separation, catalysis and sensing, [4][5][6][7] but also due to compelling prospects as molecular-level factories or nanomachines. [8] In this family of materials, structural dynamics can be induced by the uptake of various molecular probes in the framework pores or by the application of other stimuli, with temperature, external stress, electromagnetic radiation, electric or magnetic fields, just to name a few. [1][2][3]

A general theory of action provides, first, a notation in which the effects of possible individual acts can be expressed and, second, a method for probability calculations of the dynamics of systems of interacting actors; this article develops the foundation for such a theory.A framework is presented, which allows the effects of human actions to be described. The presentation is sufficiently general that other kinds of event can also be accommodated.The framework uses a simple system of modal logic, with five axioms, to define what is meant by an effect of an event or act at any level of living system or in nonliving systems. It is proposed that, in empirical studies, the significant types of act and event should be characterized by listing their effects in the notation which the framework provides.The application of the framework to human acts is described; and a diagrammatic method to represent the effects of these acts is given. It is shown that there are eleven fundamentally different possible relationships between acts and their effects.For each of the eleven basic kinds of effect, an approximate formula is given to relate the expected frequency of that effect to the overall characteristics of a state of affairs within a system.The use of the framework to draw global conclusions from local information is illustrated by showing how approximate population densities may be calculated from mechanisms for birth and death described in terms of the framework.