Quantum-dot cellular automata (QCA), which is a candidate technology to replace CMOS technology, promises extra low-power, extremely dense and high-speed structures at a nano scale. In this paper, a novel 3-input XOR gate structure is proposed based on half distance and cell interaction. Accordingly, a low-complexity and high-speed QCA one-bit full adder is designed by employing the proposed 3-input QCA XOR gate. Then a new 4-bit QCA Ripple Carry Adder (RCA) is proposed based on the proposed 3-input QCA XOR gate. The proposed designs are simulated using the both coherence and bi-stable simulation engines of QCADesigner version 2.0.3. Our simulation results indicate the efficiency and robustness of the proposed designs. The simulation results show 50% area improvement for the proposed 3-input XOR gate, 76% and 50% improvements in terms of cell count and latency, respectively for the proposed robust QCA full-adder, 58% and 52% improvements in terms of latency and cost, respectively for 4-bit QCA RCA compared to the previous designs. Keywords: Quantum-dot cellular automata, XOR gate, Full adder, Ripple Carry Adder, Nano technology, Coplana

In this paper, new model on novel coronavirus disease (COVID-19) with four compartments including susceptible, exposed, infected, and recovered class with fractal-fractional derivative is proposed. Here, Banach and Leray–Schauder alternative type theorems are used to establish some appropriate conditions for the existence and uniqueness of the solution. Also, stability is needed in respect of the numerical solution. Therefore, Ulam–Hyers stability using nonlinear functional analysis is used for the proposed model. Moreover, the numerical simulation using the technique of fundamental theorem of fractional calculus and the two-step Lagrange polynomial known as fractional Adams-Bashforth (AB) method is proposed. The obtained results are tested on real data of COVID-19 outbreak in Malaysia from 25 January till 10 May 2020. The numerical simulation of the proposed model has performed in terms of graphs for different fractional-order $q$ and fractal dimensions $p$ via number of considered days of disease spread in Malaysia. Since COVID-19 transmits rapidly, perhaps, the clear understanding of transmission dynamics of COVID-19 is important for countries to implement suitable strategies and restrictions such as Movement Control Order (MCO) by the Malaysian government, against the disease spread. The simulated results of the presented model demonstrate that movement control order has a great impact on the transmission dynamics of disease outbreak in Malaysia. It can be concluded that by adopting precautionary measures as restrictions on individual movement the transmission of the disease in society is reduced. In addition, for such type of dynamical study, fractal-fractional calculus tools may be used as powerful tools to understand and predict the global dynamics of the mentioned disease in other countries as well.

The current article deals with the combine effects of single wall carbon nanotubes and effective viscosity for the peristaltic flow of nanofluid through annulus. The nature of the walls is assumed to be permeable. The present theoretical model can be considered as mathematical representation to the motion of conductive physiological fluids in the existence of the endoscope tube which has many biomedical applications such as drug delivery system. The outer tube has a wave of sinusoidal nature that is travelling along its walls while the inner tube is rigid and uniform. Lubrication approach is used for the considered analysis. An empirical relation for the effective variable viscosity of nanofluid is proposed here interestingly. The viscosity of nanofluid is the function of radial distance and the concentration of nanoparticles. Exact solution for the resulting system of equations is displayed for various quantities of interest. The outcomes show that the maximum velocity of SWCNT-blood nanofluid enhances for larger values of viscosity parameter. The pressure gradient in the more extensive part of the annulus is likewise found to increase as a function of variable viscosity parameter. The size of the trapped bolus is also influenced by variable viscosity parameter. The present examination also revealed that the carbon nanotubes have many applications related to biomedicine. Keywords: Variable nanofluid viscosity, SWCNT, Annulus, Permeable walls, Exact solutio