Engineering transient dynamics of artificial cells by stochastic distribution of enzymes

Random fluctuations are inherent to all complex molecular systems. Although nature has evolved mechanisms to control stochastic events to achieve the desired biological output, reproducing this in synthetic systems represents a significant challenge. Here we present an artificial platform that enables us to exploit stochasticity to direct motile behavior. We found that enzymes, when confined to the fluidic polymer membrane of a core-shell coacervate, were distributed stochastically in time and space. This resulted in a transient, asymmetric configuration of propulsive units, which imparted motility to such coacervates in presence of substrate. This mechanism was confirmed by stochastic modelling and simulations in silico. Furthermore, we showed that a deeper understanding of the mechanism of stochasticity could be utilized to modulate the motion output. Conceptually, this work represents a leap in design philosophy in the construction of synthetic systems with life-like behaviors.

Electric explosion of flat copper conductors in asymmetric and symmetric configurations in the current skinning mode

Plasma formation on the surface of conductors as a result of a skin explosion is one of the key issues of the efficiency of energy transportation along the vacuum lines of terawatt-level pulsed generators. Experimental studies of plasma formation on the surface of flat conductors were carried out on the MIG generator (current level ~ 2.5 MA, rise time ~ 100 ns). The magnitude of the magnetic field induction exceeded the values required for the explosion of the conductor surface facing the magnetic field in an asymmetric configuration or both surfaces of the conductor in a symmetric configuration. It was shown that in both configurations, a plasma channel is formed on the surface of a copper foil with a thickness of 100 microns along its longitudinal axis. Experimental data on the dynamics of plasma formation at the edges of a flat conductor have been obtained. A magnetohydrodynamic simulation of an explosion in strong magnetic fields of flat conductors whose width is much greater than their thickness showed that: the expansion of the plasma along the width of the conductor is suppressed, and the plasma expands mainly along its thickness. The simulation results are in good agreement with the experimental once.

Broadband, Beam-Steering Asymmetric Stacked Microstrip Phased Array with Enhanced Front-to-Back Ratio

The backward radiation is a critical problem that may cause breakdown of the front-end circuits that are integrated behind the antenna. Thus, antennas having high Front to Back Ratio (FBR) are required. For phased arrays, the back lobe suppression is required for all scanning angles at all frequencies of the band. In this work, a stacked patch linear array with asymmetric configuration is proposed. It is capable of scanning the beam in ±40° with less than 1.34 dB scanning loss. Due to the usage of probe-fed stacked patches as the antenna elements, impedance matching in 8-10 GHz is achieved. More than 30 dB FBR is obtained for broadside radiation. It is above 20 dB when the beam is steered to θ = 40°. This is valid for all frequencies of the band. A prototype is fabricated and measured. Higher than 38 dB FBR is observed. With its broadband, high FBR and low scanning loss, the proposed asymmetrical stacked patch phased array is suitable as radar and base station antenna.

Optimizing motor-timing decision via adaptive risk-return control

Human’s ability of optimal motor-timing decision remains debated. The optimality seems context-dependent as the sub-optimality was often observed for tasks with different gain/loss configurations: people achieved optimality with symmetric gain configuration but not with asymmetric configuration. In the current study, we designed a temporal decision-making task where participants could adjust the sensitivity parameter (i.e., risk-return trade-off) of the gain function, in order to testify whether people could optimize the responses for asymmetric gain configuration by adjusting the sensitivity parameter. Participants were asked to click a point within a certain spatial region at a specified timing, where the click timing determined the reward whilst the click position determined the sensitivity parameter. We prepared three types of gain functions (symmetric, risk-after and risk-before conditions) and tested whether or not the participants achieved Bayesian optimality irrespective of gain structure. Most participants’ performance reached optimality not only in the symmetric condition but also in the asymmetric condition, albeit some discrepancies from optimality observed in the risk-before condition. This confirmed that people could achieve Bayesian optimality even for asymmetric gain configuration. We argued that the adaptive risk-return is beneficial for the performance optimality.

Numerical Analysis of MIM-Based Log-Spiral Rectennas for Efficient Infrared Energy Harvesting

This work presents the design and analysis of a metal-insulator-metal (MIM)-based optical log spiral rectenna for efficient energy harvesting at 28.3 THz. To maximize the benefits of the enhanced field of the proposed nano-antenna in the rectification process, the proposed design considers the antenna arms (Au) as the electrodes of the rectifying diode and the insulator is placed between the electrode terminals for the compact design of the horizontal MIM rectenna. The rectifier insulator, Al2O3, was inserted at the hotspot located in the gap between the antennas. A detailed analysis of the effect of different symmetric and asymmetric MIM-configurations (Au-Al2O3-Ag, Au-Al2O3-Al, Au-Al2O3-Cr, Au-Al2O3-Cu, and Au-Al2O3-Ti) was conducted. The results of the study suggested that the asymmetric configuration of Au-Al2O3-Ag provides optimal results. The proposed design benefits from the captured E-field intensity, I-V, resistivity, and responsivity and results in a rectenna that performs efficiently.