Independent control of amplitude and period in a synthetic oscillator circuit with modified repressilator

Synthetic Biology aims to create predictable biological circuits and fully operational biological systems. Although there are methods to create more stable oscillators, such as repressilators, independently controlling the oscillation of reporter genes in terms of their amplitude and period is only on theoretical level. Here, we introduce a new oscillator circuit that can be independently controlled by two inducers in Escherichia coli. Some control components, including σECF11 and NahR, were added to the circuit. By systematically tuning the concentration of the inducers, salicylate and IPTG, the amplitude and period can be modulated independently. Furthermore, we constructed a quantitative model to forecast the regulation results. Under the guidance of the model, the expected oscillation can be regulated by choosing the proper concentration combinations of inducers. In summary, our work achieved independent control of the oscillator circuit, which allows the oscillator to be modularized and used in more complex circuit designs.

Practically Realizable Circuits for OTRA and their Implementation in Oscillators

In this paper, practical circuits for operational transresistance amplifier (OTRA) realizable in lab using commercial ICs have been designed and proposed. 3 structures based on operational amplifier (OPAMP-LM741), operational transconductance amplifier (OTA-CA3080) and current conveyors II (AD844) have been proposed. In these proposed designs, conditions to mimic the current-voltage behavior of OTRA have been formulated using active and passive components. Moreover, these components are also used to achieve flexibility in transresistance gain of implemented OTRA. The behavior of the proposed OTRA structures have been validated using LTSPICE. Furthermore, to represent practical usability of these designs oscillator circuit have been designed and implemented on software and experimentally also on bread board. All the results prove the OTRA operation of the designed circuits and their usability in the practical environment.

Independent control of amplitude and period in the synthetic repressilator

Synthetic Biology aims to create predictable biological circuits and fully operational biological systems. Although there are methods to create more stable oscillators, such as repressilators, orthogonally controlling the oscillation of reporter genes in terms of their amplitude and period is only on theoretical level. Here, we introduce a new oscillator circuit that can be orthogonally controlled by two inducers in Escherichia coli. Some control components, including σECF11 and NahR, were added to the circuit. By systematically tuning the concentration of the inducers, salicylate and IPTG, the amplitude and period can be modulated independently. Furthermore, we constructed a quantitative model to forecast the regulation results. Under the guidance of the model, the expected oscillation can be regulated by choosing the proper concentration combinations of inducers. In summary, our work achieved orthogonal control of the oscillator circuit, which allows the oscillator to be modularized and used in more complex circuit designs.

Functional Capabilities of Coupled Memristor-Based Reactance-Less Oscillators

New functionalities of reactance-less memristor based oscillators are discussed which arise when two elementary oscillators are connected. It is shown that the system of coupled memristor based oscillators can be used for converting analog and analog-digital signals into binary pulse sequences. The approach to control the thresholds in memristor based oscillators is discussed. Standard control approach in memristor based oscillators is the exploitation of input signal to drive the rate of change in the state of the memristor. In contrast, the main idea of the considered controlling approach is to send the input signal not directly to the memristor device but to the comparator circuit and as result to control oscillator circuit behavior by change of interval of memristor resistor variation. The capabilities of coupled memristor based oscillators with control thresholds are sufficient for constructing the simple circuit elements of oscillatory computing architectures.

A S-Type Bistable Locally-Active Memristor and Its Application in Oscillator Circuit

In this paper, a S-type memristor with tangent nonlinearity is proposed. The introduced memristor can generate two kinds of stable pinched hysteresis loops with initial conditions from two flanks of the initial critical point. The power-off plot verifies that the memristor is nonvolatile, and the DC V-I plot shows that the memristor is locally active with the locally-active region symmetrical about the origin. The equivalent circuit of the memristor, derived by small-signal analysis method, is used to study the dynamics near the operating point in the locally-active region. Owing to the bistable and locally-active properties and S-type DC V-I curve, this memristor is called S-type BLAM for short. Then, a new Wien-bridge oscillator circuit is designed by substituting one of its resistances with S-type BLAM. It find that the circuit system can produce chaotic oscillation and complex dynamic behavior, which is further confirmed by analog circuit experiment.

A Study on Use of Mathematical Programs for Design of Electronic Circuits in Cybernetic-Physical Learning Environment

The laboratory work holds a great importance for an undergraduate student of science. And during COVID -19 pandemic, when the theory classes were moved online, migrating practical classes to online mode turned out to be a challenging task. This article aims to study the use of mathematical programs as an extensive methodological approach to enhance the learning of electronic circuit designing at undergraduate level. The students were given a task of designing a well-known oscillator circuit using a mathematical program written in open source application Scilab. The values of all the components needed to design an oscillator were calculated. The circuit was then designed practically for various frequencies using the theoretically obtained component values. The obtained output frequency of oscillator circuit was within 5% variation to the theoretically obtained one. In this article, the authors captured the experience of 500 undergraduate science students studying at various colleges of University of Delhi, India via a valid online questionnaire circulated through different platforms. The response of the students was gauged and it could be inferred that mathematical programs are working as a decent replacement during these demanding times and can be used as an add-on, once the physical labs start operating back to normalcy.