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ObjectivesEven though disinfectants are commonly used in clinical practice and daily life, there are few studies on their antibacterial ability and cytotoxicity, which are closely related to the safety and effectiveness of their use. To provide a basis for the use of disinfectants, the cytotoxicity and antibacterial activity of three most commonly used disinfectants, povidone-iodine, chlorhexidine acetate and polyhexamethylene biguanide (PHMB), were investigated.DesignA CCK-8 assay was used to measure the activities of human fibroblasts (HF) and keratinocytes (HaCat), the two most important cells in wound healing, following their exposure to disinfectants. The effects of different times and concentrations were included. The antibacterial activity of disinfectants againstStaphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniaewas reflected by their minimum inhibitory concentration and minimum bactericidal concentration.ResultsAll three disinfectants showed strong cytotoxicity in direct contact with HF and HaCat cells. Cytotoxicity increased with increasing exposure time and concentration.S. aureus,A. baumannii and K. pneumoniaecomprised 70%, 55% and 85% of the strains sensitive to povidone iodine; 50%, 45% and 80% of the strains sensitive to chlorhexidine acetate; and 60%, 45% and 80% of the strains sensitive to PHMB, respectively.ConclusionsAll three disinfectants were cytotoxic; therefore, it is necessary to pay attention to the use time and concentration in the clinical setting. All three disinfectants were cytotoxic, with povidone-iodine being the most cytotoxic even at low concentrations. PHMB had better antibacterial efficacy againstS. aureusand is suitable for the treatment of shallow wounds primarily. All three tested bacteria were significantly more sensitive to PHMB than to the other disinfectants.

A large number of animal experiments show that there is irregular chaos in the biological nervous systems. An artificial chaotic neural network is a highly nonlinear dynamic system, which can realize a series of complex dynamic behaviors, optimize global search and neural computation, and generate pseudo-random sequences for information encryption. According to the superposition theory of sinusoidal signals with different frequencies of brain waves, a non-monotone activation function based on the multifrequency-frequency conversion sinusoidal function and a piecewise function is proposed to make a neural network more consistent with the biological characteristics. The analysis shows that by adjusting the parameters, the activation function can exhibit the EEG signals in its different states, which can simulate the rich and varying brain activities when the brain waves of different frequencies and types work at the same time. According to the activation function we design a new chaotic cellular neural network. The complexity of the chaotic neural network is analyzed by the structural complexity based SE algorithm and C0 algorithm. By means of Lyapunov exponential spectrum, bifurcation diagram and basin of attraction, the effects of the activation function’s parameters on its dynamic characteristics are analyzed in detail, and it is found that a series of complex phenomena appears in the chaotic neural network, such as many different types of chaotic attractors, coexistent chaotic attractors and coexistence limit cycles, which improves the performance of the chaotic neural network, and proves that the multi-frequency sinusoidal chaotic neural network has rich dynamic characteristics, so it has a good prospect in information processing, information encryption and other aspects.

Memristor, memcapacitor and meminductor are novel nonlinear circuit elements with memory, which are also known as the memory elements. Based on the mathematical models of these three circuit elements, from the point of view of mathematical analysis, memristor, memcapacitor and meminductor Simulink based models are established. Simulink models of the memory elements reflect that their values are dependent on their historical states and their state variables, and correctly show their unique memory properties. A series of simulation analyses are done, and the typical characteristics of the three memory elements are obtained, showing the validities of these models. In addition, by studying the circuit characteristics under different parameters and excitations, the changing laws of these equivalent models with frequency and amplitude are obtained, which lay the foundation for research and application based on memristor, memcapacitor and meminductor's Simulink simulator.

A meminductor is a new type of memory device. It is of importance to study meminductor model and its application in nonlinear circuit prospectively. For this purpose, we present a novel mathematical model of meminductor, which considers the effects of internal state variable and therefore will be more consistent with future actual meminductor device. By using several operational amplifiers, multipliers, capacitors and resistors, the equivalent circuit of the model is designed for exploring its characteristics. This equivalent circuit can be employed to design meminductor-based application circuits as a meminductor emulator. By employing simulation experiment, we investigate the characteristics of this meminductor driven by sinusoidal excitation. The characteristic curves of current-flux (i-φ), voltage-flux (v-φ), v-ρ (internal variable of meminductor) and φ-ρ for the meminductor model are given by theoretical analyses and simulations. The curve of current-flux (i-φ) is a pinched hysteretic loop passing through the origin. The area bounding each sub-loop deforms as the frequency varies, and with the increase of frequency, the shape of the pinched hysteretic loop tends to be a straight line, indicating a dependence on frequency for the meminductor. Based on the meminductor model, a meminductive Wien-bridge chaotic oscillator is designed and analyzed. Some dynamical properties, including equilibrium points and the stability, bifurcation and Lyapunov exponent of the oscillator, are investigated in detail by theoretical analyses and simulations. By utilizing Lyapunov spectrum, bifurcation diagram and dynamical map, it is found that the system has periodic, quasi-periodic and chaotic states. Furthermore, there exist some complicated nonlinear phenomena for the system, such as constant Lyapunov exponent spectrum and nonlinear amplitude modulation of chaotic signals. Moreover, we also find the nonlinear phenomena of coexisting bifurcation and coexisting attractors, including coexistence of two different chaotic attractors and coexistence of two different periodic attractors. The phenomenon shows that the state of this oscilator is highly sensitive to its initial valuse, not only for chaotic state but also for periodic state, which is called coexistent oscillation in this paper. The basic mechanism and potential applications of the existing attractors are illustrated, which can be used to generate robust pseudo random sequence, or multiplexed pseudo random sequence. Finally, by using the equivalent circuit of the proposed meminducive model, we realize an analog electronic circuit of the meminductive Wien-bridge chaotic system. The results of circuit experiment are displayed by the oscilloscope, which can verify the chaotic characteristics of the oscillator. The oscillator, as a pseudo random signal source, can be used to generate chaotic signals for the applications in chaotic cryptography and secret communications.

A meminductor is a new type of nonlinear inductor with memory, which is generalized from the concept of a memristor and defined by current-flux. This paper presents a flux-controlled meminductor model with a smooth quadratic function and designs its corresponding equivalent circuit, which can be used as an emulator to imitate the behavior of a meminductor when actual solid-state meminductor has not yet appeared. Furthermore, a new chaotic oscillator is designed based on this meminductor model, and the dynamical behaviors of the oscillator are investigated, such as chaotic attractors, equilibrium points, Lyapunov exponent spectrum, bifurcations and dynamical map of the system, etc. Bifurcation analysis shows that the meminductor can make the oscillator produce periodic and chaotic oscillations. Moreover, an analog circuit is designed to confirm the correction of the proposed oscillator using the proposed equivalent circuit model of meminductor. It is shown that the experimental results are in good agreement with that of the numerical simulations and the theoretical analysis.

The dependence of sensitivity on initial conditions is the essence of chaos. And the randomness of chaos originates from the high sensitivity to initial values, which is measured by the Lyapunov exponents. It is found in this paper that the cascade of chaotic systems can considerably improve the Lyapunov exponents of cascade chaos and other dynamic properties. Therefore, in this paper, we study the cascade of chaotic systems and the influence on dynamic performances of the cascade chaos, and we present the definition and conditions of chaotic system cascade. It is proved in theory that the Lyapunov exponent of cascade chaos system is a sum of Lyapunov exponents of cascade subsystems. Appropriate cascade for chaotic systems can increase system parameters and expand parameter regions of chaos mapping and full mapping, thereby enhancing initial condition sensitivity of chaotic map and security of chaotic pseudo-random sequences. For logistic map, cubic map and tent map, the dynamic characteristics of logistic-logistic, logistic-cubic and logistic-tent cascade are investigated in detail, verifying the improvements on dynamic characteristics of cascade chaos systems. The proposed chaotic cascade system can be used to generate better pseudo-random sequences for initial condition sensitivity and security.

Objective To explore the feasibility and clinical effects by transcatheter interventions used for the patient suffering acute myocardial infarction (AMI) complicating with ventricular septal rupture (VSR) postinfarction. Methods Between June 2005 and August 2009, Ventricular septal rupture (VSR) patients diagnosed with VSR underwent transcatheter closure aged 59–79 years old (mean 63.3±24.7). The occluders were released with the monitoring of transthoracic echocardiography (TTE) and X-ray fluoroscopy. Results 3 cases were successfully treated with transcatheter closure. The defect diameter was 11–28 (17±9.5) mm measured by TTE and the size of the occluder was 16–32 (21.3±7.6) mm. The occluder successful rate was 100%. The case success in 2 and a big VSR lead to die in 1. Conclusions VSR was showed by praecordial area auscultation, transthoracic echocardiography (TTE) and left ventricular angiography after AMI. The transcatheter closure of VSR postinfarction is alternative method in patients not suite for surgical closure. But the careful examination and preparation are need before transcatheter closure.

In this paper, a new hyperchaotic system is constructed by introducing an additional state variable into the third-order Lorenz system. Some basic properties, including dissipativity, equlibria, stability and Hopf bifurcation, of this hyperchaotic system are analyzed in detail, and the bifurcation routes to hyperchaos from periodic, chaotic evolutions are observed. The existence of hyperchaos is verified with Lyapunov exponent spectrum. Moreover, an analog electronic circuit is designed, and various hyperchaotic attractors of this system are observed from the circuit experiments.

In order to generate complex chaotic attractors, we construct a new three-dimensional quadratic autonomous chaotic system, in which each equation contains a single quadratic cross-product term and a system parameter. Basic dynamic properties of the new system are investigated via theoretical analysis and numerical simulation using the Lyapunov exponent spectrum and bifurcation diagram. Our results show that this system has five equilibria, therefore is not topologically equivalent to the Lorenz, Rsslor or the Chen and Lü systems, and the new system is chaotic when its parameters satisfy certain conditions. Compared with the systems mentioned above, the proposed system has larger positive Lyapunov exponent，displays a complex attractor and some other interesting properties. An electronic circuit was designed to realize the new chaotic system. Experimental chaotic behaviors of the system were found to be identical to the dynamic properties predicted by theoretical analysis and numerical simulations.