A light-fuelled nanoratchet shifts a coupled chemical equilibrium

Biological molecular machines enable chemical transformations, assembly, replication and motility, but most distinctively drive chemical systems out of-equilibrium to sustain life. In such processes, nanometre-sized machines produce molecular energy carriers by driving endergonic equilibrium reactions. However, transforming the work performed by artificial nanomachines into chemical energy remains highly challenging. Here, we report a light-fuelled small-molecule ratchet capable of driving a coupled chemical equilibrium energetically uphill. By bridging two imine macrocycles with a molecular motor, the machine forms crossings and consequently adopts several distinct topologies by either a thermal (temporary bond-dissociation) or photochemical (unidirectional rotation) pathway. While the former will relax the machine towards the global energetic minimum, the latter increases the number of crossings in the system above the equilibrium value. Our approach provides a blueprint for coupling continuous mechanical motion performed by a molecular machine with a chemical transformation to reach an out-of-equilibrium state

Author Correction:A light-fuelled nanoratchet shifts a coupled chemical equilibrium (Nature Nanotechnology, (2022), 17, 2, (159-165), 10.1038/s41565-021-01021-z)

This Letter was originally published with an incorrect copyright status, and should have been Open Access; this has been amended and the Letter is now published under a Creative Commons license CC BY 4.0

Sensitivity Analysis of the Gupta and of the Park Chemical Models on the Heat Flux by DSMC and by CFD Codes

The present study is the logical continuation of a former paper by the first author in which the influence of the chemical models by Gupta and by Park on the computation of heat flux on the Orion and EXPERT capsules was evaluated. Tests were carried out by the direct simulation Monte Carlo code DS2V and by the computational fluid-dynamic (CFD) code H3NS. DS2V implements the Gupta model, H3NS implements the Park model. In order to compare the effects of the chemical models, the Park model was implemented also in DS2V. The results showed that DS2V and H3NS compute a different composition both in the flow field and on the surface, even using the same chemical model (Park). Furthermore DS2V computes, by the two chemical models, different compositions in the flow field but the same composition on the surface, therefore the same heat flux. In the present study, in order to evaluate the influence of these chemical models also in a CFD code, the Gupta and the Park models have been implemented in FLUENT. Tests by DS2V and by FLUENT, have been carried out for the EXPERT capsule at the altitude of 70 km and with velocity of 5000 m/s. The capsule experiences a hypersonic, continuum low density regime. Due to the energy level of the flow, the vibration equation, lacking in the original version of FLUENT, has been implemented. The results of the heat flux computation verify that FLUENT is quite sensitive to the Gupta and to the Park chemical models. In fact, at the stagnation point, the percentage difference between the models is about 13%. On the opposite the DS2V results by the two models are practically equivalent

Influence of chemical models on heat flux for EXPERT and Orion capsules

The computation of heat flux on two current re-entry capsules, European eXPErimental Reentry Testbed (EXPERT) and Orion, has been carried out by a direct simulation Monte Carlo code (DS2V) and by a computational fluid dynamic code (H3NS) in transitional regime, considering both non-reactive and fully catalytic surface. These capsules have been chosen for this analysis because they have been characterized by completely different shapes and re-entry trajectories. DS2V and H3NS use the Gupta and the Park chemical models, respectively. The results showed that the heat flux predicted by DS2V is always higher than that predicted by H3NS. Therefore, a sensitivity analysis of the chemical models on the heat flux has been carried out for both capsules. More specifically, the Park model has been implemented in DS2V as well. The results showed that DS2V and H3NS compute a different chemical composition both in the flow field and on the surface, even when using the same chemical model (Park); therefore, the different results obtained from the two codes can be attributed mostly to the different methodology used in handling all chemical processes

Analysis of aero-thermodynamic behavior of expert capsule in transitional regime

The aerodynamic behavior of the EXPERT capsule has been already widely studied at low altitudes. In order to broaden the aerodynamic data base of the capsule, additional computations of the aerodynamic forces and an evaluation of the longitudinal stability and fluctuation of the pressure center have been carried out in the altitude interval 80-105 km. The effect of the rolling angle has been also evaluated. As EXPERT, in the considered altitude interval is in transitional regime, computations have been made by the DSMC code DS3V. Heat flux along the capsule surface has been also evaluated. This is an important topic because the nose and the frustum are made of low and high catalyticity materials, respectively. Computations, already performed in continuum regime by the CFD code H3NS, showed that, at the nose-frustum junction, an abrupt and strong peak of heat flux is present. In this work, this problem has been analyzed also in transitional regime. For this application, the DSMC 2-D code DS2V, requiring smaller computer resources, compared with the ones required by DS3V, has been used for making computations at lower altitudes. Furthermore, using DS2V made possible also to get a more detailed definition of the body surface and therefore to increase the surface resolution. The launch of the capsule is currently scheduled in 2011; flight data should be available to verify the results of the present computations

Analysis of Low-Density Effects in Suborbital Flight of FAST20XX

The paper studies the high altitude effects to the future hypersonic/suborbital re-entry vehicle SpaceLiner developed in the framework of EC-funded FAST20XX project. Bridging functions have been developed and validated by means of DSMC calculations. The effects of rarefaction on global longitudinal aerodynamics of SpaceLiner in the range of altitude 65÷85 km have been pointed out by comparing to the aerodatabase in continuum regime conditions. DSMC computation has been done in the higher SpaceLiner altitude point confirming the bridging function results and providing heat transfer estimations

Sexuality and the longing for salvation

Sexuality, with all its expressiveness, strongly reflects the deep vibrations that exist in the human psyche. In this article, we try to show that sexuality can also manifest itself in the darkest realm of real addiction, and, as it were, can become a cry for salvationand further, that sexuality is the powerful reflection of an aching body, longing for purification, and thus, salvation