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Organic-rich shales from the uppermost Doushantuo Fm. (South China) record one of the most negative carbonate carbon isotopic excursions in Earth's history, known as the Shuram excursion, and contain meter to micro-size spheroids. In this study, we use Raman and energy dispersive spectroscopy to identify and describe the most common diagenetic spheroids to refine our understanding of the profound perturbations of the carbon cycle and the evolution of pore fluid chemistry imprinted in the sedimentary Precambrian record, especially in the late Ediacaran. The presence of 13C-depleted carbonate concretions or organic matter (OM) enclosed by lenticular dolomitic structures within the host shale unit suggests OM remineralisation and anaerobic oxidation, resulting in authigenic carbonate precipitation during the earliest stages of sediment diagenesis. Other mineralogical features, however, point to high levels of primary production, such as apatite bands that host spheroidal microfossils with highly fluorescent quartz and OM within abiotic concretions. These observations highlight the importance of considering co-occurring biotic and abiotic processes in explaining the formation of diagenetic spheroids in ancient sedimentary environments. From an astrobiology perspective, the interplay of biotic and abiotic processes reflects the complexity of early life systems and the environments that may exist on other terrestrial planets. Understanding the signatures of biotic and abiotic interactions in the Doushantuo Fm. is crucial for identifying potential biosignatures in extraterrestrial materials, thereby enhancing our understanding of life's universality and adaptability in diverse and extreme environments. [ABSTRACT FROM AUTHOR]

The Belousov–Zhabotinsky (BZ) reaction has long been a paradigmatic system for studying chemical oscillations. Here, we experimentally studied the synchronization control within photochemically coupled star networks of BZ oscillators. Experiments were carried out in wells performed in soda-lime glass constructed using novel laser technologies. Utilizing the inherent oscillatory nature of the BZ reaction, we engineered a star network of oscillators interconnected through photochemical inhibitory coupling. Furthermore, the experimental setup presented here could be extrapolated to more complex network architectures with both excitatory and inhibitory couplings, contributing to the fundamental understanding of synchronization in complex systems. [ABSTRACT FROM AUTHOR]

Tackling the increasing energy demand of our society is one of the key challenges today. With the rise of artificial intelligence, information and communication technologies started to substantially contribute to this alarming trend and therefore necessitate more sustainable approaches for the future. Brain-inspired computing paradigms represent a radically new and potentially more energy-efficient approach for computing that may complement or even replace CMOS in the long term. In this perspective, we elaborate on the concepts and properties of complex chemical reaction networks (CRNs) that may serve as information-processing units based on chemical reactions. The computational capabilities of simpler, oscillatory chemical reactions have already been demonstrated in scenarios ranging from the emulation of Boolean gates to image-processing tasks. CRNs offer higher complexity and larger non-linearity, potentially at lower energy consumption. Key challenges for the successful development of CRN-based computers are associated with their specific physical implementations, operability, and readout modalities. CRNs are sensible to various reaction triggers, and provide multiple and interlinked reaction pathways and a diverse compound space. This bears a high potential to build radically new hardware and software concepts for energy-efficient computing based on neuromorphic architectures--with computing capabilities in real-world applications yet to be demonstrated. [ABSTRACT FROM AUTHOR]

The exponential growth of the power of modern digital computers is based upon the miniaturization of vast nanoscale arrays of electronic switches, but this will be eventually constrained by fabrication limits and power dissipation. Chemical processes have the potential to scale beyond these limits by performing computations through chemical reactions, yet the lack of well-defined programmability limits their scalability and performance. Here, we present a hybrid digitally programmable chemical array as a probabilistic computational machine that uses chemical oscillators using Belousov-Zhabotinsky reaction partitioned in interconnected cells as a computational substrate. This hybrid architecture performs efficient computation by distributing information between chemical and digital domains together with inbuilt error correction logic. The efficiency is gained by combining digital logic with probabilistic chemical logic based on nearest neighbour interactions and hysteresis effects. We demonstrated the computational capabilities of our hybrid processor by implementing one- and two-dimensional Chemical Cellular Automata demonstrating emergent dynamics of life-like entities called Chemits. Additionally, we demonstrate hybrid probabilistic logic as a viable logic for solving combinatorial optimization problems. Computing platforms based on chemical processes can be an alternative to digital computers in some scenarios but have limited programmability. Here the authors demonstrate a hybrid computing platform combining digital electronics and an oscillatory chemical reaction and demonstrate its computational capabilities. [ABSTRACT FROM AUTHOR]

In this study, a highly crystallizable and an amorphous polylactide (i.e., cPLA and aPLA) with, respectively, low (0.5 mol. %) and high (12 mol. %) d-lactic acid contents and similar molecular weights were melt compounded with two different multifunctional epoxy-based Joncryl chain extenders (CEs, i.e., ADR 4400 and 4468) at 190 °C. Reactivity of Joncryl grades with aPLA was also explored at melt processing temperatures of 150, 170, and 210 °C. Small amplitude oscillatory shear rheological analysis was conducted to understand the extent of the Joncryl reaction with PLA molecules, and the results were confirmed with molecular weight determination using gel permeation chromatography. Extensional viscosity of the processed samples was also compared to control their strain hardening behavior. Results showed that the Joncryl reaction with cPLA and aPLA differs in terms of preference for chain extension or branching, indicating that molecular regularity affected the interactions with both Joncryl grades during reactive melt processing. Moreover, although the increase in processing temperature accelerated PLA degradation, it noticeably increased the reactivity of both Joncryl grades with aPLA. In all cases, ADR 4468 was more reactive in molecular chain extension/branching due to its higher functionality than ADR 4400. Differential scanning calorimetry results also revealed that the crystallization of cPLA was differently affected by the change in the Joncryl content and type. [ABSTRACT FROM AUTHOR]

By planting LEDs on the surfaces of orifice baffles, a novel batch oscillatory baffled photoreactor (OBPR) together with polymer-supported Rose Bengal (Ps-RB) beads are here used to investigate the reaction kinetics of a photo-oxidation reaction between α-terpinene and singlet oxygen (1O2). In the mode of NMR data analysis that is widely used for this reaction, α-terpinene and ascaridole are treated as a reaction pair, assuming kinetically singlet oxygen is in excess or constant. We have, for the first time, here examined the validity of the method, discovered that increasing α-terpinene initially leads to an increase in ascaridole, indicating that the supply of singlet oxygen is in excess. Applying a kinetic analysis, a pseudo-first-order reaction kinetics is confirmed, supporting this assumption. We have subsequently initiated a methodology of estimating the 1O2 concentrations based on the proportionality of ascaridole concentrations with respect to its maximum under these conditions. With the help of the estimated singlet oxygen data, the efficiency of 1O2 utilization and the photo efficiency of converting molecular oxygen to 1O2 are further proposed and evaluated. We have also identified conditions under which a further increase in α-terpinene has caused decreases in ascaridole, implying kinetically that 1O2 has now become a limiting reagent, and the method of treating α-terpinene and ascaridole as a reaction pair in the data analysis would no longer be valid under those conditions. [ABSTRACT FROM AUTHOR]

The transformation of amphiphilic molecular assemblies in response to chemical oscillations is fundamental in biological systems. The reversible transformation of a vesicular aggregate (VA) in response to a pH oscillation is presented in this study. A VA composed of the cationic surfactant didodecyldimethylammonium bromide is transformed using a pH oscillation ranging between 3 and 7. When the VA attains a stable structure at extreme pH values, the transformation reaches the irreversible stage. However, the addition of a phosphate buffer to the VA suspension changes the pH oscillation pattern from being rectangular to triangular and decreases the oscillation amplitude, successfully achieving the reversible transformation of the VA. Maintaining the non-equilibrium (transient) structures throughout the transformation and not falling into the equilibrium state with a varying pH are essential for the reversible transformation. This may be common and essential for dynamics in biological cells. [ABSTRACT FROM AUTHOR]

We report on the collective response of an assembly of chemomechanical BelousovZhabotinsky (BZ) hydrogel beads. We first demonstrate that a single isolated spherical BZ hydrogel bead with a radius below a critical value does not oscillate, whereas an assembly of the same BZ hydrogel beads presents chemical oscillation. A BZ chemical model with an additional flux of chemicals out of the BZ hydrogel captures the experimentally observed transition from oxidized nonoscillating to oscillating BZ hydrogels and shows this transition is due to a flux of inhibitors out of the BZ hydrogel. The model also captures the role of neighboring BZ hydrogel beads in decreasing the critical size for an assembly of BZ hydrogel beads to oscillate. We finally leverage the quorum sensing behavior of the collective to trigger their chemomechanical oscillation and discuss how this collective effect can be used to enhance the oscillatory strain of these active BZ hydrogels. These findings could help guide the eventual fabrication of a swarm of autonomous, communicating, and motile hydrogels. [ABSTRACT FROM AUTHOR]

In this work the performance of various detailed reaction mechanisms of combustion of methane–hydrogen fuel mixtures is studied. The investigation is focused on the burner stabilized flame configuration and is undertaken for the normal pressure conditions, which is a starting point for the analysis of the combustion chemistry at elevated pressures met in rocket engine chambers. The study presents the experimental setup, computational approach and results of comparison, which allow us to access the properties of complex combustion systems in variety of dynamical regimes. The comparison of the predicted and measured characteristics of these regimes is used to test the performance of the reaction models. In particular, the critical behavior, e.g. for blow-up, onset of pulsations and quasi-steady flame front propagation and bifurcation between these regimes may be used to characterize and to study properties of combustion systems with mixed fuels. A neutral stability boundary for onset of pulsations is suggested to be used in this study. A method for automatic identification of the boundary is proposed and implemented with several detailed mechanisms. Although for pure methane the results look acceptable, they show gradual divergence with the increase of percentage of hydrogen addition. Significant quantitative differences between experiments and modeling with respects to frequencies of oscillations are reported even for 2:1 ratio of hydrogen to methane in the unburned mixture. The results of the work indicate that current reaction mechanisms need to be improved in order to gain the quantitative predictability of methane–hydrogen–air combustion at normal pressure before proceeding to the conditions fuel-oxygen high pressure combustion more relevant for rocket chamber. • Combustion systems with complex fuel composition — hydrogen addition. • Quantitative comparison of experiments and computations in transient combustion regimes. • Automatic procedure for parametric study to access onset of pulsations. • Mechanisms dependence — performance of existing and well-established mechanisms. • Validation of chemical reaction models via critical mixture composition. [ABSTRACT FROM AUTHOR]

Agate geodes contain spheroidal patterns characterized by spectacularly coloured and circularly concentric laminations with radially aligned quartz crystals, yet the origin of these geometric patterns has remained enigmatic. Here, detailed comparisons are documented between these kinds of patterns in a selection of geodes and concretions and those produced by abiotic chemically oscillating reactions. We find strikingly comparable self-similar, fractal patterns in both natural volcanogenic geodes and sedimentary concretions as well as in these benchtop experiments. In addition, the mineralogical composition of patterns and associated organic matter point to the oxidation of organic compounds in both geodes and concretions. This process occurred during diagenetic or supergene alteration, and it is consistent with spontaneous and abiotic chemically oscillating reactions. It is concluded that the oxidation of organic acids was involved in the formation of these patterns and that these rocks indicate oxidation–reduction reactions involving organic carbon, which itself may be abiotic or biological in origin. Hence, agate geodes and concretions represent the abiotic biosignatures of possible biological origin in volcanic and sedimentary rocks. [ABSTRACT FROM AUTHOR]

Excitable media, ranging from bioelectric tissues and chemical oscillators to forest fires and competing populations, are nonlinear, spatially extended systems capable of spiking. Most investigations of excitable media consider situations where the amplifying and suppressing forces necessary for spiking coexist at every point in space. In this case, spikes arise due to local bistabilities, which require a fine-tuned ratio between local amplification and suppression strengths. But, in nature and engineered systems, these forces can be segregated in space, forming structures like interfaces and boundaries. Here, we show how boundaries can generate and protect spiking when the reacting components can spread out: Even arbitrarily weak diffusion can cause spiking at the edge between two non-excitable media. This edge spiking arises due to a global bistability, which can occur even if amplification and suppression strengths do not allow spiking when mixed. We analytically derive a spiking phase diagram that depends on two parameters: i) the ratio between the system size and the characteristic diffusive length-scale and ii) the ratio between the amplification and suppression strengths. Our analysis explains recent experimental observations of action potentials at the interface between two non-excitable bioelectric tissues. Beyond electrophysiology, we highlight how edge spiking emerges in predator-prey dynamics and in oscillating chemical reactions. Our findings provide a theoretical blueprint for a class of interfacial excitations in reaction-diffusion systems, with potential implications for spatially controlled chemical reactions, nonlinear waveguides and neuromorphic computation, as well as spiking instabilities, such as cardiac arrhythmias, that naturally occur in heterogeneous biological media. [ABSTRACT FROM AUTHOR]

Background: Oscillatory behavior is critical to many life sustaining processes such as cell cycles, circadian rhythms, and notch signaling. Important biological functions depend on the characteristics of these oscillations (hereafter, oscillation characteristics or OCs): frequency (e.g., event timings), amplitude (e.g., signal strength), and phase (e.g., event sequencing). Numerous oscillating reaction networks have been documented or proposed. Some investigators claim that oscillations in reaction networks require nonlinear dynamics in that at least one rate law is a nonlinear function of species concentrations. No one has shown that oscillations can be produced for a reaction network with linear dynamics. Further, no one has obtained closed form solutions for the frequency, amplitude and phase of any oscillating reaction network. Finally, no one has published an algorithm for constructing oscillating reaction networks with desired OCs. Results: This is a theoretical study that analyzes reaction networks in terms of their representation as systems of ordinary differential equations. Our contributions are: (a) construction of an oscillating, two species reaction network [two species harmonic oscillator (2SHO)] that has no nonlinearity; (b) obtaining closed form formulas that calculate frequency, amplitude, and phase in terms of the parameters of the 2SHO reaction network, something that has not been done for any published oscillating reaction network; and (c) development of an algorithm that parameterizes the 2SHO to achieve desired oscillation, a capability that has not been produced for any published oscillating reaction network. Conclusions: Our 2SHO demonstrates the feasibility of creating an oscillating reaction network whose dynamics are described by a system of linear differential equations. Because it is a linear system, we can derive closed form expressions for the frequency, amplitude, and phase of oscillations, something that has not been done for other published reaction networks. With these formulas, we can design 2SHO reaction networks to have desired oscillation characteristics. Finally, our sensitivity analysis suggests an approach to constructing a 2SHO for a biochemical system. [ABSTRACT FROM AUTHOR]

A major challenge in materials science is dynamically adjusting material properties using sensors and control systems. This contribution develops a new approach using a self-oscillating copolymer to autonomously change material surface properties in response to environmental changes. A redox-sensitive terpolymer of N-isopropylacrylamide (NIPAM), dimethylacrylamide (DMAc), and an iron-based comonomer ([(phen)2(phen-5-yl-acrylamide)FeII](PF6)2) is synthesized via Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization, catalyzing an oscillating redox reaction (Belousov-Zhabotinsky, BZ). The terpolymer oscillates from soluble to insoluble around 35 °C based on the iron’s oxidation state. A catechol unit is incorporated to enhance versatility, enabling grafting onto different surfaces. Optimal BZ reagent concentrations are explored for maximum oscillation amplitude and frequency. By selecting a working temperature between redox transition points, the copolymer’s oscillation from coil to globular conformation is observed due to redox oscillations. The self-oscillating copolymer is grafted onto an ultrafiltration membrane, where conformational changes cause variations in pore size, leading to rapid negative flux peaks that disrupt the flux and reduce membrane fouling during protein filtration. This study highlights self-oscillating polymers’ ability to impart dynamic properties to inert materials, paving the way for smart materials with self-regulating properties to adapt to changing conditions. [ABSTRACT FROM AUTHOR]

Promoters are important in catalysis, but the atomistic details of their function and particularly their role in reaction instabilities such as kinetic phase transitions and oscillations are often unknown. Employing hydrogen oxidation as probe reaction, a Rh nanotip for mimicking a single Rh nanoparticle and field electron microscopy for in situ monitoring, we demonstrate a La-mediated local catalytic effect. The oscillatory mode of the reaction provides a tool for studying the interplay between different types of reaction pacemakers, i.e., specific local surface atomic configurations that initiate kinetic transitions. The presence of La shifts the bistable reaction states, changes the oscillation pattern and deactivates one of two pacemaker types for the La-free surface. The observed effects originate from the La-enhanced oxygen activation on the catalyst. The experimental observations are corroborated by micro-kinetic model simulations comprising a system of 25 coupled oscillators. Promoters are important in catalysis, but their exact role requires further investigation. Here, by imaging complex spatio-temporal pattern formation during the oscillatory reaction, the authors reveal the effect of La-modulation to be related with higher oxygen binding energy at nanostructured pacemaker regions. [ABSTRACT FROM AUTHOR]

Sodium silicate-activated slags have the potential to harden quickly, which limits their practical use in grouting and deep soil mixing works. The open time of grouts is defined as the time period when their rheological properties allow their storage, pumping, and injection into the soil. In this work, the impact of the H2O/Na2O ratio and two acids (citric and boric acid) on the reactivity and hardening rates of slag-based grouts was studied. The H2O/Na2O ratio had a minimal impact on the open time but prolonged the setting time, as observed by ultrasonic characterization. Both acids were effective in delaying the structuration time, as revealed by oscillatory rheology and reaction advancement; however, they caused a decrease in the elastic modulus. Adding the acids resulted in a decrease in the pH of the medium, which may be linked to the extended open time. The analysis of the ion concentration of Ca, Si, and Al disclosed the mode of action of the two retarders. [ABSTRACT FROM AUTHOR]

To further explore the origins of Life, we consider three self-replicating chemical models. In general, models of the origin of Life include molecular components that can self-replicate and achieve exponential growth. Therefore, chemical self-replication is an essential chemical property of any model. The simplest self-replication mechanisms use the molecular product as a template for its synthesis. This mechanism is the so-called First-Order self-replication. Its regulatory limitations make it challenging to develop chemical networks, which are essential in the models of the origins of Life. In Second-Order self-replication, the molecular product forms a catalytic dimer capable of synthesis of the principal molecular product. In contrast with a simple template, the dimers show more flexibility in forming complex chemical networks since the chemical activity of the dimers can be activated or inhibited by the molecular components of the network. Here, we consider three minimal models: the First-Order Model (FOM), the Second-Order Model (SOM), and an Extended Second-Order Model (ESOM). We construct and analyze the mechanistic dimensionless ordinary differential equations (ODEs) associated with the models. The numerical integration of the set of ODEs gives us a visualization of these systems' oscillatory behavior and compares their capacities for sustained autocatalytic behavior. The FOM model displays more complex oscillatory behavior than the ESOM model. [ABSTRACT FROM AUTHOR]

Oscillations are one of the intrinsic features of many animate and inanimate systems. The oscillations manifest in the temporal periodic change of one or several physical quantities describing the systems. In chemistry and biology, this physical quantity is the concentration of the chemical species. In most chemical oscillatory systems operating in batch or open reactors, the oscillations persist because of the sophisticated chemical reaction networks incorporating autocatalysis and negative feedback. However, similar oscillations can be generated by periodically changing the environment providing non-autonomous oscillatory systems. Here we present a new strategy for designing a non-autonomous chemical oscillatory system for the zinc–methylimidazole. The oscillations manifested in the periodic change of the turbidity utilizing the precipitation reaction between the zinc ions and 2-methylimidazole (2-met) followed by a partial dissolution of the formed precipitate due to a synergetic effect governed by the ratio of the 2-met in the system. Extending our idea spatiotemporally, we also show that these precipitation and dissolution phenomena can be utilized to create layered precipitation structures in a solid agarose hydrogel. [ABSTRACT FROM AUTHOR]

In this petrographic and geochemical study, we differentiated diverse quartz botryoids, including circular-concentric, twinned, columnar, wavy, and stromatolite-like structures versus synchronous biotic patterns of similar geometry and size dimensions (filamentous traits and stromatolites) in Precambrian cherts of Barberton, South Africa, and Gunflint, Canada. The botryoidal habits explored retained self-similar patterns of radially aligned acicular quartz with concentric laminae, which are not documented in biologically built stromatolites. These ancient fractals and their composition imitate those in chemically oscillating reactions, implying that the precipitation of botryoids was fueled by abiotic diagenetic degradation of organic matter and subsequently metamorphosed into chert. [ABSTRACT FROM AUTHOR]

Earlier [V. P. Lesnikov, Ukr. J. Phys. 64, 126 (2019)] it was pointed out that for thermal hydrodynamic fluctuations in open hydrodynamic steady states (OHSS) the determining factor for derivation of reciprocal relations is not the principle of microscopic reversibility, but the presence or absence of a flux. In the present work this idea is applied to open chemical steady states (OCSS), where chemical oscillations are possible. The behavior of concentration fluctuations when there are no macroscopic oscillations yet is considered. The reciprocal relations for such OCSS are found. [ABSTRACT FROM AUTHOR]

From its inception, an astonishing movement has been made in the architecture and fabrication of a fresh category of nanostructured material acknowledged as luminescent metal–organic frameworks (MOFs). Luminescent MOFs are self-assembled nanostructure by coordinating suitable metal cations or clusters and ideal organic linkers, which exhibited an abundance of merits for sensing of interest of analytes, such as chemicals, metal ions, biomarkers, etc. Herein, tunable surface morphology and diverse functionality of luminescent MOFs offer high sensitivity, high selectivity, good stability, recyclability, real-time applicability, etc. Additionally, the accessible porosity and luminescence property of nanostructured MOFs provides the transducing potential from host–guest chemistry to recognizable improvement in nanosize MOFs luminescence. Therefore, in this review article, we have summarized the nanostructured design of MOFs-based luminescent sensors for chemical and metal ions sensing. At first, the requirement of monitoring of chemical residues and metal ions exposure has been discussed that demonstrates the topical necessity for the chemical and metal ions recognition. Afterward, the current trends of MOFs-centered sensors, synthesis types, and their properties have been elaborated in brief. It revealed that several theoretical sensing mechanisms, such as electron transfer, energy transfer, ligand interaction, overlapping effect, oscillation effect, inner filter effect, decomposition, etc., are accountable for sensing of metal ions and chemical residues. The applications of nano-architectured MOFs-based luminescent sensors for chemical as well as metal ions sensing have been illustrated, which exhibit the lowest detection limit (μM–nM) for both metal ions and chemicals. Interestingly, the nanostructured MOFs relied on luminescent sensors that exhibited high sensitivity and selectivity for the chemical and metal ions in presence of diverse interfering substances. Surface functionality presented on the surface of nano-size MOFs, types of ligands, and selected metal ions provides precise recognition of real-time samples containing metal ions and chemicals. On the whole, the nanostructured design of a MOFs-based luminescent sensor will release a fresh preference for sensing of a target analyte. Nanostructured metal-organic frameworks based luminescent sensor for chemical and metal ions sensing [ABSTRACT FROM AUTHOR]

Proper mixing in microfluidic devices has been a concern since the early development stages. Acoustic micromixers (active micromixers) attract significant attention due to their high efficiency and ease of implementation. Finding the optimal geometries, structures, and characteristics of acoustic micromixers is still a challenging issue. In this study, we considered leaf-shaped obstacle(s) having a multi-lobed structure as the oscillatory part(s) of acoustic micromixers in a Y-junction microchannel. Four different types of leaf-shaped oscillatory obstacles, including 1, 2, 3, and 4-lobed structures, were defined, and their mixing performance for two fluid streams was evaluated numerically. The geometrical parameters of the leaf-shaped obstacle(s), including the number of lobes, lobes' length, lobes' inside angle, and lobes' pitch angle, were analyzed, and their optimum operational values were discovered. Additionally, the effects of the placement of oscillatory obstacles in three configurations, i.e., at the junction center, on the side walls, and both, on the mixing performance were evaluated. It was found that by increasing the number and length of lobes, the mixing efficiency improved. Furthermore, the effect of the operational parameters, such as inlet velocity, frequency, and intensity of acoustic waves, was examined on mixing efficiency. Meanwhile, the occurrence of a bimolecular reaction in the microchannel was analyzed at different reaction rates. It was proven that the reaction rate has a prominent effect at higher inlet velocities. [ABSTRACT FROM AUTHOR]

We have studied gas-grain chemical models of interstellar clouds to search for non-linear dynamical evolution. A prescription is given for producing oscillatory solutions when a bistable solution exists in the gas-phase chemistry and we demonstrate the existence of limit cycle and relaxation oscillation solutions. As the autocatalytic chemical processes underlying these solutions are common to all models of interstellar chemistry, the occurrence of these solutions should be widespread. We briefly discuss the implications for interpreting molecular cloud composition with time-dependent models and some future directions for this approach. [ABSTRACT FROM AUTHOR]

MHD flow past over oscillating vertical plate with variable temperature and mass diffusion through a porous medium in the presence of Hall current effect and chemical reaction is studied here. The MHD fluid model contains partial differential equations of momentum, energy and diffusion equations. The Laplace-transform technique used to find the exact solution of equations involved in this paper. The resultant velocity profile is discussed with the help of graphs drawn for different parameters like, inclination of magnetic field, chemical reaction parameter, phase angle parameter and permeability parameter, and the numerical values Sherwood number have been also tabulated. It is noticed that the values obtained for velocity, concentration and temperature profiles are in concurrence with the actual flow of the unsteady MHD fluid. [ABSTRACT FROM AUTHOR]

Background/Aim: Due to the numerous beneficial effects of pomegranate that can be explained through its antioxidative effects, the aim of this study was to determine the antioxidant potential of pomegranate peel extract (PoPEx) prepared from pomegranate that was harvested in the south-east region of Herzegovina (Bosnia and Herzegovina), through in vitro and in vivo studies. Methods: In PoPEx total phenols, flavonoids, flavonols, flavan-3-ols and anthocyanins content was determined, as well as several antioxidative assays, including 2,2 diphenyl-1-picrylhydrazyl assay (DPPH), 2,2'-azino bis(3-ethylbenzothiazoline- 6-sulphonic acid) assay (ABTS), iron (III) - 2,4,6-tripyridyl-S-triazine complex assay (FRAP), reduction of copper(II) ions (CUPRAC) assay, Briggs-Rauscher oscillatory reactions, neutralisation of OH radicals and lipid peroxidation assay. In vivo studies were performed by administrating 100 mg/ kg of body weight of PoPEx to the rats by gavage for 7 days, after which the rats were euthanised and prooxidative parameters (thiobabrituric acid reactive substances - TBARS as an index of lipid peroxidation, nitrites - NO2, hydrogen peroxide - H2O2 and superoxide anion radical O2-) were determined in plasma, as well as antioxidative parameters (superoxide dismutase - SOD, reduced glutathione - GSH and catalase - CAT) in erythrocyte lysates. Results: High content of phenolic compounds was found in PoPEx, which resulted in high antioxidative potential in all in vitro tests performed. In vivo study showed that PoPEx administration caused a significant decrease in TBARS, N2-, as well as an increase in reduced glutathione (p < 0.05) in comparison to the control group, while H2O2 and O2* showed a lowering trend and SOD and CAT showed an increasing trend in PoPEx group, but without statistical significance. Conclusion: PoPEx demonstrated high antioxidative capacity measured in vitro and in vivo and can be potentially used as a supplement treatment in the prevention of various inflammatory conditions. [ABSTRACT FROM AUTHOR]

In compartmentalized systems, chemical reactions may proceed in differing ways even in adjacent compartments. In compartmentalized nanosystems, the reaction behaviour may deviate from that observed on the macro- or mesoscale. In situ studies of processes in such nanosystems meet severe experimental challenges, often leaving the field to theoretical simulations. Here, a rhodium nanocrystal surface consisting of different nm-sized nanofacets is used as a model of a compartmentalized reaction nanosystem. Using field emission microscopy, different reaction modes are observed, including a transition to spatio-temporal chaos. The transitions between different modes are caused by variations of the hydrogen pressure modifying the strength of diffusive coupling between individual nanofacets. Microkinetic simulations, performed for a network of 52 coupled oscillators, reveal the origins of the different reaction modes. Since diffusive coupling is characteristic for many living and non-living compartmentalized systems, the current findings may be relevant for a wide class of reaction systems. In situ studies of the spatio-temporal behavior of individual well-defined nanosized compartments are paramount in heterogeneous catalysis. Here, a transition from oscillating to chaotic behaviour was observed in catalytic hydrogen oxidation on a rhodium nanocrystal serving as a model of a single catalytic particle. [ABSTRACT FROM AUTHOR]

The origin of life must have included an abiotic stage of carbon redox reactions that involved electron transport chains and the production of lifelike patterns. Chemically oscillating reactions (COR) are abiotic, spontaneous, out-of-equilibrium, and redox reactions that involve the decarboxylation of carboxylic acids with strong oxidants and strong acids to produce CO2 and characteristic self-similar patterns. Those patterns have circular concentricity, radial geometries, characteristic circular twins, colour gradients, cavity structures, and branching to parallel alignment. We propose that COR played a role during the prebiotic cycling of carboxylic acids, furthering the new model for geology where COR can also explain the patterns of diagenetic spheroids in sediments. The patterns of COR in Petri dishes are first considered and compared to those observed in some eukaryotic lifeforms. The molecular structures and functions of reactants in COR are then compared to key biological metabolic processes. We conclude that the newly recognised similarities in compositions and patterns warrant future research to better investigate the role of halogens in biochemistry; COR in life-forms, including in humans; and the COR-stage of prebiotic carbon cycling on other planets, such as Mars. [ABSTRACT FROM AUTHOR]

Based on the effective Schrödinger–Poisson model a new physical mechanism for resonant hot-electron generation at irradiated half-space metal–vacuum interface of electron gas with arbitrary degree of degeneracy is proposed. The energy dispersion of undamped plasmons in the coupled Hermitian Schrödinger–Poisson system reveals an exceptional point coinciding the minimum energy of plasmon conduction band. Existence of such exceptional behavior is a well-know character of damped oscillation which in this case refers to resonant wave–particle interactions analogous to the collisionless Landau damping effect. The damped Schrödinger–Poisson system is used to model the collective electron tunneling into the vacuum. The damped plasmon energy dispersion is shown to have a full-featured exceptional point structure with variety of interesting technological applications. In the band gap of the damped collective excitation,depending on the tunneling parameter value, there is a resonant energy orbital for which the wave-like growing of collective excitations cancels the damping of the single electron tunneling wavefunction. This important feature is solely due to dual-tone wave-particle oscillations, characteristics of the collective excitations in the quantum electron system leading to a resonant photo-plasmonic effect, as a collective analog of the well-known photo-electric effect. The few nanometer wavelengths high-energy collective photo-electrons emanating from the metallic surfaces can lead to a much higher efficiency of plasmonic solar cell devices, as compared to their semiconductor counterpart of electron–hole excitations at the Fermi energy level. The photo-plasmonic effect may also be used to study the quantum electron tunneling and electron spill-out at metallic surfaces. Current findings may help to design more efficient spasers by using the feature-rich plasmonic exceptional point structure. [ABSTRACT FROM AUTHOR]

In this work, we study, in the framework of the ab initio linear-response time-dependent density functional theory, the low-energy collective electronic excitations with characteristic sound-like dispersion, called acoustic plasmons, in bulk ferromagnetic nickel. Since the respective spatial oscillations in slow and fast charge systems involve states with different spins, excitation of such plasmons in nickel should result in the spatial variations in the spin structure as well. We extend our study to NiH x with different hydrogen concentrations x. We vary the hydrogen concentration and trace variations in the acoustic plasmons properties. Finally, at x = 1 the acoustic modes disappear in paramagnetic NiH. The explanation of such evolution is based on the changes in the population of different energy bands with hydrogen content variation. [ABSTRACT FROM AUTHOR]

Speed-accuracy tradeoff (SAT) in the decision making of humans and animals is a well-documented phenomenon, but its underlying neuronal mechanism remains unclear. Modeling approaches have conceptualized SAT through the threshold hypothesis as adjustments to the decision threshold. However, the leading neurophysiological view is the gain modulation hypothesis. This hypothesis postulates that the SAT mechanism is implemented through changes in the dynamics of the choice circuit, which increase the baseline firing rate and the speed of neuronal integration. In this paper, I investigated alternative computational mechanisms of SAT and showed that the threshold hypothesis was qualitatively consistent with the behavioral data, but the gain modulation hypothesis was not. In order to reconcile the threshold hypothesis with the neurophysiological evidence, I considered the interference of alpha oscillations with the decision process and showed that alpha oscillations could increase the discriminatory power of the decision system, although they slowed down the decision process. This suggests that the magnitude of alpha waves suppression during the event related desynchronization (ERD) of alpha oscillations depends on a SAT condition and the amplitude of alpha oscillations is lower in the speed condition. I also showed that the lower amplitude of alpha oscillations resulted in an increase in the baseline firing rate and the speed of neuronal intergration. Thus, the interference of the event related desynchronization of alpha oscillations with a SAT condition explains why an increase in the baseline firing rate and the speed of neuronal integration accompany the speed condition. [ABSTRACT FROM AUTHOR]

In this paper, the kinetics of p53 in two cell lines with different degrees of sensitivity to chemotherapeutic drugs is studied. There is much research that has explored the p53 oscillation, but there are few comparisons between cells that are sensitive to drug treatment and those that are not. Here, the kinetics of the p53 system between etoposide-sensitive and etoposide-resistant cell lines in response to different drug doses and different protein synthesis time delays are studied and compared. First, the results showed that time delay is an important condition for p53 oscillation by producing Hopf bifurcation in both the etoposide-sensitive and etoposide-resistant cells. If the protein synthesis time delays are zero, the system cannot oscillate even the dose of the drug increases. Second, the time delay required for producing sustained oscillation in sensitive cells is shorter than the drug-resistant cells. In addition, the p53-Wip1 negative feedback loop in drug-resistant cells is relatively highly strengthened than the drug-sensitive cells. To sum up, p53 oscillation is controlled by time delay, drug dose, and the coupled negative feedback network including p53-mdm2 and p53-wip1. Moreover, in the two different types of cells, the control mechanisms are similar, but there are also differences. [ABSTRACT FROM AUTHOR]

Chemical reactions with oscillating behavior can present a chaos state in specific conditions. In this study, we analyzed the dynamic of the chaotic Belousov–Zhabotinsky (BZ) reaction using the Györgyi–Field model in order to identify the conditions of the chaos behavior. We studied the behavior of the reaction under different parameters that included both a low and high flux of chemical species. We performed our analysis of the flow regime in the conditions of an open reaction system, as this provides information about the behavior of the reaction over time. The proposed method for determining the favorable conditions for obtaining the state of chaos is based on the time evolution of the intermediate species and phase portraits. The synchronization of two Györgyi–Field systems based on the adaptive feedback method of control is presented in this work. The transient time until synchronization depends on the initial conditions of the two systems and on the strength of the controllers. Among the areas of interest for possible applications of the control method described in this paper, we can include identification of the reaction parameters and the extension to the other chaotic systems. [ABSTRACT FROM AUTHOR]

Research on network percolation and synchronization has deepened our understanding of abrupt changes in the macroscopic properties of complex engineered and natural systems. While explosive percolation emerges from localized structural perturbations that delay the formation of a connected component, explosive synchronization is usually studied by fine-tuning of global parameters. Here, we introduce the concept of synchronization bombs as large networks of heterogeneous oscillators that abruptly transit from incoherence to phase-locking (or vice-versa) by adding (or removing) one or a few links. We build these bombs by optimizing global synchrony with decentralized information in a competitive percolation process driven by a local rule, and show their occurrence in systems of Kuramoto –periodic– and Rössler –chaotic– oscillators and in a model of cardiac pacemaker cells, providing an analytical characterization in the Kuramoto case. Our results propose a self-organized approach to design and control abrupt transitions in adaptive biological systems and electronic circuits, and place explosive synchronization and percolation under the same mechanistic framework. Synchronization bombs are large networks of coupled heterogeneous oscillators that operate in a bistable regime and abruptly transit from incoherence to synchronization by adding one or a few links. Self-organized synchronization bombs would be useful to understand switch mechanisms in biological systems, and to design networks to operate in this regime. [ABSTRACT FROM AUTHOR]

Nanoparticle (NP) catalysts are ubiquitous in energy systems, chemical production, and reducing the environmental impact of many industrial processes. Under reactive environments, the availability of catalytically active sites on the NP surface is determined by its dynamic structure. However, atomic-scale insights into how a NP surface reconstructs under reaction conditions and the impact of the reconstruction on catalytic activity are still lacking. Using operando transmission electron microscopy, we show that Pd NPs exhibit periodic round–to–flat transitions altering their facets during CO oxidation reaction at atmospheric pressure and elevated temperatures. This restructuring causes spontaneous oscillations in the conversion of CO to CO2 under constant reaction conditions. Our study reveals that the oscillatory behavior stems from the CO-adsorption-mediated periodic restructuring of the nanocatalysts between high-index-faceted round and low-index-faceted flat shapes. These atomic-scale insights into the dynamic surface properties of NPs under reactive conditions play an important role in the design of high-performance catalysts. Atomic-scale insights into how a nanoparticle surface reconstructs under reaction conditions and the impact of the reconstruction on catalytic activity are still lacking. Here the authors reveal that Pd nanocatalysts display oscillatory changes in both their structure and activity during CO oxidation using operando TEM. [ABSTRACT FROM AUTHOR]

• Non-cooperative 3-node enzymatic reaction networks can oscillate. • Kinetic efficiency and topology determine the probability of oscillation. • Inhibitors and activators regulate the frequency and stability of oscillations. Oscillatory phenomena are often observed in enzyme systems due to feedback regulation, with a classic motif for persistent oscillation being a three-component negative feedback loop. Delay and high cooperativity are proposed as essential for the oscillation in these motifs. This study focuses on designing and optimizing oscillatory biochemical reactions using three-node enzymatic networks without cooperativity. Our findings revealed that improving the specificity constant – the so-called kinetic efficiency – and selecting the optimal topology can greatly increase the probability and frequency of oscillation in biochemical reactions. Inspired by pharmacology, various moderators were utilized to enhance the specificity constant, demonstrating how various oscillatory regimes can be reached with a given topology. [ABSTRACT FROM AUTHOR]

A frequency spectrum segmentation methodology is proposed to extract the frequency response of circuits and systems with high resolution and low distortion over a wide frequency range. A high resolution is achieved by implementing a modified Dirichlet function (MDF) configured for multi-tone excitation signals. Low distortion is attained by limiting or avoiding spectral leakage and interference into the frequency spectrum of interest. The use of a window function allowed for further reduction in distortion by suppressing system-induced oscillations that can cause severe interference while acquiring signals. This proposed segmentation methodology with the MDF generates an interleaved frequency spectrum segment that can be used to measure the frequency response of the system and can be represented in a Bode and Nyquist plot. The ability to simulate and measure the frequency response of the circuit and system without expensive network analyzers provides good stability coverage for reliable fault detection and failure avoidance. The proposed methodology is validated with both simulation and hardware. [ABSTRACT FROM AUTHOR]

We consider classical dynamics of a one-dimensional system of N particles bouncing on an oscillating mirror in the presence of gravitational field. The particles behave like hard balls and they are resonantly driven by the mirror. We identify the manifolds the particles move on and derive the effective secular Hamiltonian for resonant motion of the particles. Proper choice of time periodic oscillations of the mirror allows for engineering of the effective behaviour of the particles. In particular, the system can behave like an N -dimensional fictitious particle moving in an N -dimensional crystalline structure. Our classical analysis constitutes a basis for quantum research of novel time crystal phenomena in ultra-cold atoms bouncing on an oscillating atom mirror. [ABSTRACT FROM AUTHOR]

The antioxidant activity of coffee brews was determined in batch conditions by means of a Briggs-Rauscher oscillating system. This method consists of the measurement of the inhibition time caused by the addition of a diluted coffee sample to the oscillating system. The inhibition time vs. the relative concentration of the diluted coffee sample shows linear dependence. The slope of these lines was used to calculate a relative antioxidant activity for each sample. It was concluded that the method of preparation greatly influenced the resulting coffee brew, with the filtering method showing the best results with up to 50% higher antioxidant activity. As such, it was chosen as a standard to compare activity values. It can also be noted that decaffeinated coffee samples show significantly lower activity than caffeine-containing ones. [ABSTRACT FROM AUTHOR]

Indigo carmine is a commonly used industrial blue dye. To determine its concentration in a commercially available food dye composed of a mixture of indigo carmine and D-glucose, this paper characterizes it through (ATR, KBr) FTIR micro-Raman as well as UV/Vis and clock: Briggs–Rauscher (BR) oscillatory reaction methods. The indigo carmine was detected in the bulk food dye only by applying micro-Raman spectroscopy, indicating a low percentage of the indigo carmine present. This research provides an improvement in the deviations from the experimental Raman spectrum as calculated by the B97D/cc-pVTZ level of theory one, resulting in a better geometrical optimization of the indigo carmine molecule compared to data within the literature. The analytical curves used to determine indigo carmine concentrations (and quantities) in an aqueous solution of food dye were applied by means of UV/Vis and BR methods. BR yielded significantly better analytical parameters: 100 times lower LOD and LOQ compared to commonly used UV/Vis. The remarkable sensitivity of the BR reaction towards indigo carmine suggests that not only does indigo carmine react in an oscillatory reaction but also its decomposition products, meaning that the multiple oxidation reactions have an important role in the BR's indigo carmine mechanism. The novelty of this research is the investigation of indigo carmine using a clock BR reaction, opening new possibilities to determine indigo carmine in other complex samples (pharmaceutical, food, etc.). [ABSTRACT FROM AUTHOR]

I believe the computing potential of systems with chemical reactions has not yet been fully explored. The most common approach to chemical computing is based on implementation of logic gates. However, it does not seem practical because the lifetime of such gates is short, and communication between gates requires precise adjustment. The maximum computational efficiency of a chemical medium is achieved if the information is processed in parallel by different parts of it. In this paper, I review the idea of computing with coupled chemical oscillators and give arguments for the efficiency of such an approach. I discuss how to input information and how to read out the result of network computation. I describe the idea of top-down optimization of computing networks. As an example, I consider a small network of three coupled chemical oscillators designed to differentiate the white from the red points of the Japanese flag. My results are based on computer simulations with the standard two-variable Oregonator model of the oscillatory Belousov–Zhabotinsky reaction. An optimized network of three interacting oscillators can recognize the color of a randomly selected point with >98% accuracy. The presented ideas can be helpful for the experimental realization of fully functional chemical computing networks. [ABSTRACT FROM AUTHOR]

In this paper, the initial neutral atmospheric parameters, background ionospheric parameters and geomagnetic field parameters of the ionosphere are obtained by NRLMSISE-00 model, IRI-2016 model and IGRF-13 model, respectively. Considering the neutral gas diffusion process, ion chemical reaction and plasma diffusion process, a three-dimensional dynamic model of chemical substances released by rocket plume disturbing the ionosphere is constructed. The influence of the disturbance on the echo path of high frequency radio waves with different incident frequencies is simulated by using three-dimensional digital ray-tracing technology. Using this model, the process of ionospheric disturbance caused by the main chemical substances H2 and H2O in the rocket plume under three different release conditions: fixed-point release at 300 km, vertical path at 250–350 km and parabolic path at 250–350 km, and the influence of the ionospheric cavity on the radio wave propagation of high frequency radio waves at different frequencies are simulated. The main purpose of the article is to focus on the effect of the cavity generated by the rocket exhaust on the propagation of radio waves. It mainly studies the perturbation effect on the ionosphere under different release conditions, considers the neutral gas diffusion process, ion chemical reaction and plasma diffusion process, and establishes the three-dimensional dynamics of the ionospheric electron density and the spatiotemporal distribution of the plume plasma learning model. Finally, the three-dimensional ray-tracing algorithm is used to simulate the propagation path of the radio wave through the disturbance area. We considered three different release conditions, including fixed-point release, vertical path and parabolic path. The ionospheric disturbances produced by these different releases are compared and analyzed, and their effects on the propagation path of radio waves are studied. [ABSTRACT FROM AUTHOR]

Qualitative transformation of a low-velocity laminar flow to a turbulent state (owing to natural or artificial instability) and formation of compression waves passing ahead have been studied in much detail. A disputable issue is the nature of the emergence of a reaction pocket in the region between the bow compression wave and the flame front moving at a certain distance behind this wave, as well as the dynamics of interaction of this pocket with the main structural elements. It is the type of this pocket (slow or explosive combustion) that defines its subsequent interaction with the compression wave front: shockless or shock-induced expansion capable of forming a detonation wave. As a method of transforming the reaction pocket to an explosion pocket, its amplification owing to the resonance of streamwise acoustic oscillations of hot reaction products with the initial combustible mixture induced by flame propagation is discussed. It is the resonance with its multiple enhancement of the amplitude of gas-dynamic parameters that can effectively initiate the deflagration-to-detonation transition. Various stages of this transition are discussed; the corresponding estimates are made and are found to be consistent with experiments. [ABSTRACT FROM AUTHOR]

Lately, a new class of nanofluids, namely hybrid nanofluids, has been introduced that performs much better compared with the nanofluids when a healthier heat transfer rate is the objective of the study. Heading in the same direction, the present investigation accentuates the unsteady hybrid nanofluid flow involving CuO, Al2O3/C2H6O2 achieved by an oscillating disk immersed in the porous media. In a study of the homogeneous and heterogeneous reactions, the surface catalyzed reaction was also considered to minimize the reaction time. The shape factors of the nanoparticles were also taken into account, as these play a vital role in assessing the thermal conductivity and heat transfer rate of the system. The assumed model is presented mathematically in the form of partial differential equations. The system is transformed by invoking special similarity transformations. The Keller Box scheme was used to obtain numerical and graphical results. It is inferred that the blade-shaped nanoparticles have the best thermal conductivity that boosts the heat transfer efficiency. The oscillation and surface-catalyzed chemical reactions have opposite impacts on the concentration profile. This analysis also includes a comparison of the proposed model with a published result in a limiting case to check the authenticity of the presented model. [ABSTRACT FROM AUTHOR]

[Display omitted] Coupling stimuli-responsive building blocks with an oscillating reaction is an effective strategy to realize and investigate dissipative self-assembly. More importantly, since there is usually more than one component of which concentration periodically changes in a chemical oscillator, it can be expected that this strategy has the advantage of achieving dissipative self-assembly of the building blocks with dual- or even multi-responsiveness. We realized the dissipative self-assembly of a pH- and iodine-responsive block copolymer, poly(ethylene oxide)- b -poly(2-vinyl pyridine) (PEO-P2VP), by coupling it with the IO 3 --SO 3 2--Fe(CN) 6 2- (ISF) oscillator, and investigated its rhythmic self-assembly behavior. Furthermore, we proposed a mechanistic model to simulate the kinetics of the ISF oscillator coupling with different amounts of PEO-P2VP. Rhythmic core-shell reversal of the polymer micelles formed by PEO-P2VP was found in the ISF oscillator. The mechanistic model we proposed successfully reproduced the experimental oscillation and provided some data on the kinetics of the dual responsive self-assembly of PEO-P2VP. This line of research provided an example of realizing dissipative self-assembly of dual-responsive building blocks, which was seldom reported previously. It once again suggested that coupling with a suitable chemical oscillator is a promising strategy to have an insight into the kinetics of stimuli-responsive self-assembly. [ABSTRACT FROM AUTHOR]

A hierarchical network of pulse-coupled spike microoscillators (MOs) capable of randomly responding to an external signal has been studied theoretically and experimentally. The network consists of Antenna units, a Central Pattern Generator (CPG), and a Decision-Making unit (DM). The external signal induces antiphase or in-phase oscillations in the microcells included in the Antenna. The CPG also has these two dynamic modes. What mode to accept for the CPG unit in response to the appearance of a dynamic mode in the Antenna is decided by the DM unit. Owing to its configuration, the DM unit makes this decision randomly. Microspheres with oscillating Belousov–Zhabotinsky reaction are used as MOs. Pulse coupling between the MOs is carried out by beams of light focused on the MOs. [ABSTRACT FROM AUTHOR]

The article discusses that Traveling waves are common in biological and synthetic systems, including the recent discovery that silver (Ag) colloids form traveling motion waves in H2O2 and under light. The research wad conducted on colloidal motion wave as a heterogeneous excitable system. Or they pave the way for using colloidal waves or as a tool for colloidal transport and for information transmission in microrobot ensembles.

The goal of the present study is to characterize solutions under a travelling wave formulation to a degenerate Fisher-KPP problem. With the degenerate problem, we refer to the following: a heterogeneous diffusion that is formulated with a high order operator; a non-linear advection and non-Lipstchitz spatially heterogeneous reaction. The paper examines the existence of solutions, uniqueness and travelling wave oscillatory properties (also called instabilities). Such oscillatory behaviour may lead to negative solutions in the proximity of zero. A numerical exploration is provided with the following main finding to declare: the solutions keeps oscillating in the proximity of the null stationary solution due to the high order operator, except if the reaction term is quasi-Lipschitz, in which it is possible to define a region where solutions are positive locally in time. [ABSTRACT FROM AUTHOR]

In this paper, we study the qualitative dynamical analysis, routes to chaos and the coexistence of attractors in a four-well φ8 -generalized Lienard oscillator under external and parametric excitations. The local analysis of the autonomous system reveals ´ saddles, nodes, spirals or centers for appropriate choice of stiffness and damping coefficients. The existence of a Hopf bifurcation is proved during the stability analysis of the equilibrium points. The routes to chaos and the prediction of coexisting attractors have been investigated numerically by using the fourth order Runge-Kutta algorithm. The bifurcation structures obtained show that the system displays a rich variety of bifurcation phenomena, such as symmetry breaking, symmetry restoring, period-doubling, period windows, period-m bubbles, reverse period windows, antimonotonicity, intermittency, quasiperiodic, and chaos. In addition, remerging chaotic band attractors and remarkable routes to chaos occur in the system. Further, it is found that the system presents various coexistence of two attractors as well as the monostability and bistability phenomena. On the other hand, for large amplitude of the parametric excitation and with ω = 1, the coexistence of asymmetric periodic bursting oscillations of different topologies takes place in the system. It has also been shown numerically that for appropriate values of system parameters and initial conditions, the presented system can exhibit up to five types of coexisting multiple attractors. [ABSTRACT FROM AUTHOR]

The reverse transcription-polymerase chain reaction (RT-PCR) has been utilized as an effective tool to diagnose the infectious diseases of viruses. In the present work, the oscillating thermocycler is fabricated and performed to carry out the one-step RT-PCR process successfully. The ribonucleic acid (RNA) mixture is pipetted into the fixed sample volume inside an aluminum reaction block. The sample oscillates the pathway onto the linear motion control system and through the specific RT-PCR heating zones with individual homemade thermal control modules. The present oscillating thermocycler combines the merits of the chamber type and the CF type systems. Before PCR, the reaction chamber moves to the low-temperature zone to complete the RT stage and synthesize the complementary deoxyribonucleic acid (DNA). Next, the low-temperature zone is regulated to the annealing zone. Furthermore, the reactive sample is moved back and forth among three isothermal zones to complete PCR. No extra heating zone is required for the RT stage. The total length of the moving displacement of the chamber is within 100 mm. The miniaturization of the oscillating thermocycler can be expected. In our oscillatory device, the denaturation zone located between the annealing and extension zones is suggested as the appropriate arrangement of the heating blocks. Heat management without thermal cross-talk is easy. Finally, an improved oscillating device is demonstrated to execute the RT-PCR process directly, utilized to amplify the canine distemper virus templates successfully, which could be well applied to a low-cost DNA analysis system in the future. [ABSTRACT FROM AUTHOR]