Nitride bonded silicon carbide composites based on artificial ceramic binders

The mass compositions for the production of silicon carbide materials on a nitride bond, in which artificial ceramic binders based on silicon and silicon carbide were used as initial binders, were studied. The influence of the firing regime and the composition of the binder on the main physicomechanical characteristics and microstructure of the samples after nitriding firing is studied.

Silent-free thermal insulation from self-sealing masses based on a burnable additive of plant origin. Part 3. Technological features of the production of non-chamotte-free thermal insulation products based on a burnable additive with a starchy core of micellar structure

The modes of electric heating of the self-compacting mass are determined. Three periods of changes in its specific electrical resistance are noted, due to the water absorption capacity of the herbal supplement. The relationship between electrophysical processes and their influence on the compaction of the mixture is described. The scheme of raw drying according to the rate of moisture loss is considered. The selection of the firing regime was carried out taking into account the influence of gases formed during the burnout of the vegetable additive and volumetric changes in clay during sintering. The microstructure of the lightweight material is characterized by a large number of circular closed pores in the range of 0,1‒1,2 mm. Ill. 5. Tab. 3.

Influence of Firing Regime and Potassium Ions on Synthetic Preparation of Belite Clinker

The study of the influence of selected temperature regime and potassium ions on the process of synthesis of belite (2CaO·SiO2, C2S) was carried out. The basic raw material was calcium carbonate (CaCO3) and amorphous silica (SiO2). The dosage of both components was based on the stoichiometric ratio of CaO:SiO2 in belite. The modification of the raw meal was carried out in the form of potash, K2O. Potash was dosed in the form of potassium carbonate, K2CO3, and potassium sulfate, K2SO4. The firing process was performed in a superkanthal furnace with two temperature modes, firing temperature: 1150 °C / 3 hours soaking and 1450 °C / 5 hours soaking. The evaluation performed by the experiment was based on mineralogical analysis by XRD analysis.

Measuring effects of different noises in a model using ISI-distance methods

This paper examines the effects of current and conductance noises in a minimal Hodgkin–Huxley type model of a cold receptor neuron. Current noise enters the membrane equation directly while conductance noise is propagated through the activation variables. Compared with common used interspike interval method, ISI-distance is a simple complementary approach to measure the different effects of current and conductance noises. ISI-distance extracts information from the interspike intervals by evaluating the ratio of instantaneous firing rates, which is parameter-free, time scale-independent and easy to visualize. Simulation results show that the most significant differences between different noise implementations in a pacemaker-like tonic firing regime at the transition to chaotic burst discharges.

Huber-Braun neuron dynamics

We study a physiologically realistic implementation of internal stochasticity in a four dimensional Hodgkin-Huxley (HH) type model of cold receptors. We show that in a deterministically tonic-firing regime, changing the parameters can drive the neuron into a state of complex bursting behavior. An explanation of the mechanism behind this effect is given in terms of a bifurcation diagram of inter-spike interval (ISI) as the temperature and external current are altered.

Two Distinct Mechanisms Shape the Reliability of Neural Responses

Despite intrinsic noise sources, neurons can generate action potentials with remarkable reliability. This reliability is influenced by the characteristics of sensory or synaptic inputs, such as stimulus frequency. Here we use conductance-based models to study the frequency dependence of reliability in terms of the underlying single-cell properties. We are led to distinguish a mean-driven firing regime, where the stimulus mean is sufficient to elicit continuous firing, and a fluctuation-driven firing regime, where spikes are generated by transient stimulus fluctuations. In the mean-driven regime, the stimulus frequency that induces maximum reliability coincides with the firing rate of the cell, whereas in the fluctuation-driven regime, it is determined by the resonance properties of the subthreshold membrane potential. When the stimulus frequency does not match the optimal frequency, the two firing regimes exhibit different “symptoms” of decreased reliability: reduced spike-time precision and reduced spike probability, respectively. As a signature of stochastic resonance, reliable spike generation in the fluctuation-driven regime can benefit from intermediate amounts of noise that boost spike probability without significantly impairing spike-time precision. Our analysis supports the view that neurons are endowed with selection mechanisms that allow only certain stimulus frequencies to induce reliable spiking. By modulating the intrinsic cell properties, the nervous system can thus tune individual neurons to pick out specific input frequency bands with enhanced spike precision or spike probability.