A chaotic memcapacitor oscillator with two unstable equilibriums and its fractional form with engineering applications

A novel charge-controlled memcapacitor 3D chaotic oscillator with two unstable equilibriums is proposed. Various dynamic properties of the proposed system are derived and investigated to show the existence of chaotic oscillations. Fractional-order analysis of the chaotic oscillator shows that the maximum value for the largest positive Lyapunov exponent is exhibited in fractional order. Adomian decomposition method is used to discretize the fractional-order system. Field-programmable gate arrays are used to realize the proposed oscillator. In addition, random number generator is designed by employing this novel chaotic system in its fractional-order form.     

Elimination of spiral waves in excitable media by magnetic induction

Nonlinear Dynamics - The formation of spiral waves in excitable media is a fascinating example of the beauty of nonlinear dynamics in spatiotemporal systems. Apart from the beauty of the patterns,...     

Process equation as a model for the development of cells

The European Physical Journal Special Topics - This paper proposes a behavioral model for cells that shows their different dynamics from a high pluripotent stem cell to any distinct cell fate. The...     

Synthesis of pyrrolo[2,3-d]pyrimidines (microreview)

Chemistry of Heterocyclic Compounds - Microreview summarizes recent methods for the synthesis of pyrrolo[2,3-d]pyrimidines, published since 2015. The methods are classified as Cu-catalyzed...     

Developing Novel Fabrication and Optimisation Strategies on Aggregation-Induced Emission Nanoprobe/Polyvinyl Alcohol Hydrogels for Bio-Applications

The current study describes a new technology, effective for readily preparing a fluorescent (FL) nanoprobe-based on hyperbranched polymer (HB) and aggregation-induced emission (AIE) fluorogen with high brightness to ultimately develop FL hydrogels. We prepared the AIE nanoprobe using a microfluidic platform to mix hyperbranched polymers (HB, generations 2, 3, and 4) with AIE (TPE-2BA) under shear stress and different rotation speeds (0–5 K RPM) and explored the FL properties of the AIE nanoprobe. Our results reveal that the use of HB generation 4 exhibits 30-times higher FL intensity compared to the AIE alone and is significantly brighter and more stable compared to those that are prepared using HB generations 3 and 2. In contrast to traditional methods, which are expensive and time-consuming and involve polymerization and post-functionalization to develop FL hyperbranched molecules, our proposed method offers a one-step method to prepare an AIE-HB nanoprobe with excellent FL characteristics. We employed the nanoprobe to fabricate fluorescent injectable bioadhesive gel and a hydrogel microchip based on polyvinyl alcohol (PVA). The addition of borax (50 mM) to the PVA + AIE nanoprobe results in the development of an injectable bioadhesive fluorescent gel with the ability to control AIEgen release for 300 min. When borax concentration increases two times (100 mM), the adhesion stress is more than two times bigger (7.1 mN/mm²) compared to that of gel alone (3.4 mN/mm²). Excellent dimensional stability and cell viability of the fluorescent microchip, along with its enhanced mechanical properties, proposes its potential applications in mechanobiology and understanding the impact of microstructure in cell studies.     

Further dynamical analysis of modified Fitzhugh–Nagumo model under the electric field

Nonlinear Dynamics - Models of neurons play an essential role in computational neuroscience. They provide a virtual laboratory to analyze the different regimes in the electrical activities of a...     

The highest background radiation school in the world and the health status of its students and their offspring

Although the average effective human dose from natural background radiation is about 2.4 mSv per year, the students of the Saeid Nafisi school in Ramsar received effective doses of about 250 mSv while studying there for over 5 years. The goal of this project was a retrospective study of the health status of former students of this school and their offspring. The list of the students of the Saeid Nafisi school (high background radiation) and Taleghani and Kashani schools (ordinary background radiation) was provided by the Department of Education. After matching sex, age and socioeconomic level and obtaining their consent, part 1 of the specifically designed questionnaire was filled out by interview, and clinical examinations were recorded in part 2 of the questionnaire by a physician. The data were analysed using Statistical Package for the Social Sciences 16. Our study shows that 88.1 % of general examinations of high background radiation school students were normal as compared with 85.7 % for control group. There were no significant differences. This study is interesting and unique. It reveals that there is no health emergency related to these high radiation doses. We recommend continuing the health supervision of this population in the future.     

Central composite design optimization of dispersive liquid–liquid microextraction based on solidification of organic drop for the determination of 5-hydroxymethyl-2-furfural in orange juice using high-performance liquid chromatography

A simple, rapid and inexpensive dispersive liquid–liquid microextraction based on solidification of organic drop combined with HPLC was developed for the extraction and determination of trace levels of 5-hydroxymethyl-2-furfural in fruit juice. Effect of variables such as extracting and dispersive solvent volume and pH were investigated simultaneously using experimental design. Under the optimum conditions, the calibration graph was linear in the range of 1?200 μg/L with the detection limit of 0.3 μg/L. The optimized method revealed a good precision with relative standard deviation of 2.2%.The performance of the method was evaluated for extraction and determination of 5-hydroxymethyl-2-furfural in orange juice sample.