Micro and Nanosystems - Volume 12, Issue 1, 2020

Superparamagnetic iron oxide has been applied in different fields for various reasons. Its abundant availability, non-toxic properties, environmentally friendly and good chemical stability in aqueous medium are beneficial for water treatment applications. In addition, its low bad gap (2.3 ~ 2.4 eV) has contributed to highly possible electrons-holes activation under the visible light spectrum. On the realization of iron oxide capabilities as a promising alternative to conventional anatase TiO2 photocatalysts, this review is presented to critically discuss the photocatalytic behaviour of organic water pollutants as a function of iron oxide properties. The concluding remarks in terms of the way forward in the opportunities of iron oxide superparamagnetic properties can benefit towards the photocatalytic activities including recycling, retrieving and controlling in wastewater treatment.

Background: Spherical contacting surfaces are often designed to increase the contact surface area and bearing ability, and frequently suffer fluctuating loading, which will play an important role in tribological properties. Objective: Effects of high-frequency fluctuating loading on friction and wear performance of spherical- surface contact sliding pairs should be experimentally investigated. Methods: Bench tests with the differential gear contacting pairs of heave trucks were conducted under fluctuating loading generated by the traction force of spring-connecting hanging weights. Results: High amplitude of fluctuating loads tends to result in different wear forms such as fatigue wear, plowing damages, material side flow and plastic deformation. The amplitude of the fluctuating loads has significant influence on the tribological performance of the spherical-surface contact sliding pairs and is apt to break the frictional stability of the friction pairs indicated by the variation of the signal components of friction force signals decomposed by discrete wavelet transform method. Conclusion: The high frequency and large amplitude are the main factors of fluctuating loading that plays very important role in the tribological characteristics of spherical-surface contact sliding pairs.

Background: Over the last few decades, reversible logic system/circuits have received considerable attention in the diversified fields such as nanotechnology, quantum computing, cryptography, optical computing and low power design of VLSI circuits due to their low power dissipation characteristics. Methods: In this paper, we proposed the design of reversible shift register (SR) i.e. serial-in-serial out (SISO), serial-in-parallel out (SIPO), parallel-in-serial out (PISO) and parallel-in-parallel out (PIPO) SR using a reduced number of reversible logic gates and garbage output. Result: As compared to previously reported results, the improvement in our proposed model of SISO, SIPO, PISO and PIPO was found to be 50 – 66.66 %, 42.85 – 66.66 %, 12.5 – 53.33 % and 50 – 66.66 % respectively, in terms of the number of reversible logic gates.

Objective: The objective of the present work was to develop transethosomes loaded with propranolol hydrochloride using Lipoid S100 as phospholipid, and oleic acid as permeation enhancer and evaluate them for prolonged release effect, in-vitro skin permeation, and in-vivo plasma concentration. Methods: Transethosomes loaded with propranolol hydrochloride were prepared by homogenization method. Furthermore, they were characterized by using Transmission Electron Microscopy (TEM), zeta sizer, Differential Scanning Calorimetry (DSC), and Confocal Laser Scanning Microscopy (CLSM) for in-vitro skin permeation. Plasma concentration profile of transethosomal gel was determined using Sprague Dawley rats and compared with a marketed oral tablet of propranolol hydrochloride. Results: Developed transethosomes loaded with propranolol hydrochloride showed acceptable size (182.7 ± 5.4 nm), high drug entrapment (81.98 ± 2.9%) and good colloidal characteristics [polydispersity index (PDI) = 0.234 ± 0.039, zeta potential = -21.91 ± 0.65 mV]. Transethosomes showed prolonged in-vitro release of propranolol hydrochloride for 24 h. Results of in-vitro skin permeation studies of transethosomal gel showed 74.34 ± 2.33% permeation of propranolol hydrochloride after 24 h and confocal microscopy revealed accumulation of transethosomes in the stratum basale layer of the skin. Transethosomal gel was capable to prolong the in-vivo release of propranolol hydrochloride upto 24 h. The value of peak plasma concentration (Cmax) of propranolol hydrochloride was found to be 93.8 ± 3.6 ng/mL which was very high compared to the marketed oral tablet of propranolol hydrochloride (45.6 ± 3.1 ng/mL). Conclusion: The results suggested that transethosomal gel of propranolol hydrochloride could be a better alternative to oral propranolol hydrochloride as it can avoid various disadvantages of oral propranolol hydrochloride like high dosing frequency, first pass effect, and organ toxicity.

Background: Measuring tartaric acid in liquid food, such as fruits or fruit products is of great importance for assessing the quality of the food. Objective: The aim of the research is to obtain polyaniline/Cu bismuthate nanoflake composites by an in-situ polymerization route for the electrochemical detection of tartaric acid. Methods: Polyaniline/Cu bismuthate nanoflake composites were prepared by in-situ aniline polymerizing route in aqueous solution. The obtained products were characterized by X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM) and high-resolution TEM (HRTEM), respectively. The electrochemical performance for tartaric acid detection has been investigated by cyclic voltammetry method using polyaniline/Cu bismuthate nanoflake composites modified glassy carbon electrode. Results: The nanocomposites comprise of tetragonal CuBi2O4 phase. Polyaniline particles with the size of less than 100 nm attach to the surface of the nanoflakes. A pair of quasi-reversible cyclic voltammetry peaks are located at -0.01 V and +0.04 V, respectively at the 20wt.% polyaniline/Cu bismuthate nanoflake composites modified glassy carbon electrode. The limit of detection is 0.58 μM with the linear range of 0.001-2 mM. The linear range increases from 0.005-2 mM to 0.001-2 mM and limit of detection decreases from 2.3 μM to 0.43 μM with increasing the polyaniline content from 10wt.% to 40wt.%. Conclusion: Comparing with the Cu bismuthate nanoflakes modified glassy carbon electrode, polyaniline/ Cu bismuthate nanoflake composites modified glassy carbon electrode shows enhanced electrochemical performance for tartaric acid detection.

Background: Main concern in efficient VLSI circuit designing is low-power consumption, high-speed and noise tolerance capability. Objective: In this paper, two efficient and high-performance topologies are proposed for cascaded domino logic using carbon nanotube MOSFETs (CN-MOSFETs). The first topology is designed to remove the intermediate charge sharing problem without any keeper circuit, whereas the second one holds the true logic level of the evaluation phase without any voltage drop for next precharge phase. The proposed topologies are suitable for cascading of the high-performance domino circuits. Methods: The proposed domino circuits are tested and verified using Synopsys HSPICE simulator with 32nm CN-MOSFET technology provided by Stanford University. Conclusion: The power delay product of proposed DL-I and DL-II improves by 32.59 % and 40.98 % for 8-input OR gate as compared to standard logic respectively at the clock frequency of 500 MHz. The simulation results validate that the proposed circuits improve the performance of pseudo domino logic with respect to leakage power consumption, delay and unity noise gain.

Aim: Vanadium oxide nanofibers have been manufactured by the sol–gel electrospinning method followed by the thermal treatment in air and argon. Materials and Methods: The samples are characterized by optical, laser confocal and scanning electron microscopy, energy-dispersive X-ray elemental analysis, X-ray diffraction, cyclic voltammetry, and electrical conductivity measurements. Results: The obtained VO2 nanofibers demonstrate the semiconductor-to-metal phase transition. Also, the vanadium pentoxide nanofibers are examined as electrode materials for rechargeable Li-ion batteries.

Background: Fractional order Butterworth and Chebyshev (low-pass filter circuits, highpass filter circuits and band-pass filters circuits) types of first and second order filter circuits have been simulated and their transfer function are derived. The effect of change of the fractional order α on the behavior of the circuits is investigated. Objective: This paper presents the use of fractional order capacitor in active filters. The expressions for the magnitude, phase, the quality factor, the right-phase frequencies, and the half power frequencies are derived and compared with their previous counterpart. Methods: The circuits have been simulated using Orcad as well as MATLAB for the different value of α. We have developed the fractional gain and phase equations for low pass filter circuits, high pass filter circuits and band pass filter circuits in Sallen-Key topology. Results: It is observed that the bandwidth increases significantly with fractional order other than unity for the low pass as well as high pass and band pass filters. Conclusion: We have also seen that in the frequency domain, the magnitude and phase plots in the stop band change nearly linearly with the fractional order. If we compare the fractional Butterworth filters for low-pass and high-pass type with conventional filters then we find that the roll-off rate is equal to the next higher order filter.