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Conclusions 1.The large induction periods in ignition of a fulminating mixture near the first explosive range in quartz reactors washed with fluoric or boric acid are due to inhibition of combustion by the products of the reaction of the active sites of the flame with extraneous impurities.2.Measures which prevent the formation of an inhibitor result in the good agreement of the calculated and experimentally observed induction periods.3.An oscillating mode of combustion of hydrogen only occurs when contaminants are present in the reactor system; fluttering of the flame apparently arises as a result of the interaction of the active sites with the surface on which the extraneous substances are sorbed.

Experimental studies and kinetic simulation have shown that the formation of cool flames is as typical of oxidation of methane as of oxidation of its homologs. Phenomena peculiar to the cool-flame processes in closed systems are observed, namely, the region of a negative temperature coefficient of the reaction, single and double cool-flame flashes, two stage ignition, and light radiation in the range of luminescence of formaldehyde.

Quantitative agreement of calculation and experimental data was obtained for the first time for final depletions and maximum reaction rate in the chain explosion of a stoichiometric explosive mixture close to the first combustion limit.

A decrease of the rate of high pressure oxidation of very rich methane-oxygen mixtures with increasing oxygen concentration was found. The results were confirmed by kinetic simulation of the process. A very distinct temperature dependence of the rate of oxygen conversion can be explained on the basis of a critical change in the reaction mechanism.

Machine modeling was used to investigate the kinetic mechanism of the gas-phase oxidation of carbon disulfide at elevated temperatures. The scheme of the process examined includes 70 elementary reactions. On the basis of the kinetic data on these reactions available in the literature the rates of the oxidation process, the concentrations of end products and intermediate particles were calculated as a function of the time under various conditions (composition, pressure, temperature). Comparison of the results obtained with the experimental data showed satisfactory agreement and also revealed some important elementary reactions.

A kinetic model of oxidation of hydrogen sulfide is proposed. The model contains 201 elementary stages, 23 particles, and satisfactorily describes the experimental data in a wide range of temperatures and pressures.

The probability of decay of fluorine atoms on the surface of molybdenum glass, quartz, Teflon, copper, nickel, gold and on aluminium alloy at 20–300 °C has been determined.

The absolute rate constants for the reactions of trifluoromethyl radicals with fluorine (I) and oxygen (II), k1=(3.1±2.1)×10−11 exp [−(4600±300)/RT] (cm3/molec sec) and k2=(2.5±1.7)×10−11 exp [−(2100±300)/RT] (cm3/molec sec). have been determined from the relative rate constants for the reactions of trifluoromethyl radicals with oxygen and chlorine (IV):k2/k4=(3.6±1.6)exp [(1600±300)/RT] (T=269–356 K) obtained by the photolysis of a mixture of hexafluoroacetone (HFA) with O2 and Cl2.

An approximate method for modeling the self-ignition delay for internal combustion engines is proposed. The method allows the calculation of the time of chemical reaction for self-ignition at a constant volume (or constant pressure), which is equivalent to the real time of engine operation with a moving piston. The self-ignition delay calculated using a detailed kinetic mechanism is compared with corresponding experimental data.

By resonance fluorescence in a jet at 300–670°K, the rate constants of the reactions of atomic hydrogen with phosphorus trichloride and P4, are determined. In the products of these reactions, atomic phosphorus is registered in concentrations comparable with the concentrations of expended hydrogen atoms.

Conclusions 1.The application of strychnine to a localized area of the primary somatosensory cortex causes an increase in frequency of spontaneous discharge of its neurons with the appearance of paroxysmal bursts, and at the same time, depression (or even complete suppression) of spontaneous neuron activity in the anterior part of the middle suprasylvian gyrus.2.Depression of spontaneous neuronal activity in the association area is also observed (even better) when the spontaneous activity of the neurons in this area is intensified by a previous application of weak strychnine solution.3.Spontaneous activity of neurons of any other, nonassociative, cortical area (the anterior ectosylvian gyrus, for example), situated the same distance from the part of the somatosensory cortex poisoned by strychnine, remains unchanged under these conditions.4.The application of strychnine to the association area of the middle suprasylvian gyrus does not change the spontaneous or paroxysmal activity of neurons in the primary somatosensory cortex.

Conclusions 1.Under the influence of stimulation of the mesencephalic reticular formation (MRF) activity of neurons in the visual cortex usually remains unchanged but may be either facilitated or depressed.2.Under certain conditions bursts of synchronized impulses occur in response to photic stimulation at low frequencies and stimulation of MRF then abolishes the periodicity of the impulse discharge.3.Since the periodicity of such bursts of synchronized impulses probably develops as the result of an inhibitory postsynaptic potential, the facilitation of cortical neurons by influences from MRF must be based on abolition of an inhibitory process.

Summary 1.In response to different peripheral stimuli (flashes, electrical stimulation of contralateral fore- and hind limbs) a complex associative response consisting of early and late components is recorded in the cat association cortex (anterior divisions of the marginal and suprasylvian gyri). The early component is observed in both anesthetized and unanesthetized animals; the late component is absent under nembutal anesthesia.2.In unanesthetized and chloralose animals most responding neurons generate a late component, and only a few generate the early component of the associative response.3.The early component of the associative response coincides with discharge of neurons responding after a short latent period and only to stimulation of one modality. The late component is due to activity of polysensory, bisensory and monosensory neurons having a longer latency.4.In unanesthetized animals and, in particular, under chloralose anesthesia, the polysensory activity of the neurons is improved; under nembutal anesthesia no polysensory response was observed under the experimental conditions used.5.It follows from the facts described above that formation of the late component of the associative response is connected with the state of cortical function favoring the formation of polysensory unit activity. The early component is also generated by neurons exhibiting monosensory activity.6.Polysensory neurons responsible for the late component of the associative response are found more frequently in layer IV, whereas neurons generating the early component are more numerous in the upper (III) and lower (VI) layers of the cortex.

Spontaneous and induced activity in the neurons in the pulvinar of the thalamus (PT) was studied extracellularly in unnarcotized cats immobilized with Remiolan. The PT neurons had a relatively low level of spontaneous activity, and either responded only to light flashes (61%) or did not respond to any of the stimuli applied. The latent periods of the responses varied within wide limits (from 15 to 60 msec), which indicates the possibility of direct peripheral activation of the PT neurons and also of the existence of multisynaptic afferent connections. Acoustic and electrical cutaneous stimuli, although they did not themselves evoke response-discharges, modulated both spontaneous activity and activity evoked by light flashes in the PT neurons. The same effect on the activity of the PT neurons was produced by electrical excitation of the mesencephalic reticular formation. That gives us grounds for surmising that the modulating effects of acoustic and electrical stimuli are produced through activation of reticular structures in the midbrain.

Evoked potentials were recorded in the system of raphe nuclei in experiments on unanesthetized, immobilized cats. Somatic stimulation proved to be the most effective of the different stimulations used (light flash, sound click, electrical stimulation of the skin of the limbs). Sound and light stimulation did not evoke pronounced responses, or the latter (to sound) were of a very low amplitude and irregular. In the second series of experiments on cats narcotized with nembutal (30–35 mg/kg) the spontaneous activity and activity evoked by somatic stimulation of single neurons of the caudal part of the raphe nuclei were studied. The overwhelming majority of neurons were characterized by spontaneous activity which changed (inhibited or facilitated) under the effects of somatic (especially repeated) stimulation; most of them reacted to stimulation of the skin of any limb. In the case of paired stimulation of the skin of limbs on different sides at large intervals (40–60 msec), inhibition of the test discharge occurred, whereas at small intervals summation (simple addition) of the impulses occurred. In their general characteristics the neurons of the raphe nuclei apparently differ little from the neurons of the reticular formation of the brain stem.

Spontaneous activity and single unit responses of the bulbar raphe nuclei (NR) and mesencephalic reticular formation (MRF) were studied in unanesthetized cats. In addition to the general features, a number of special features of the unit activity of these two structures were discovered: a) in most cases NR neurons respond predominantly or entirely to cutaneous stimulation of 3 to 4 limbs; b) spontaneous activity (SA) of NR neurons is more regular and less variable in time than that of MRF neurons. Under the influence of various peripheral stimulations the spontaneous activity of NR neurons briefly increases in frequency without any change in firing pattern, whereas the increase in frequency of MRF neurons occurs for much longer and is accompanied by marked changes in spontaneous activity c) NR neurons respond to all peripheral stimuli used by an absolutely uniform, short and compact volley of spikes, whereas MRF neurons respond differently to each stimulus, with various numbers of spikes and different firing patterns. These peculiarities of NR unit activity are evidently attributable to its simpler synaptic organization than that of MRF.

Responses to flashes, clicks, and electrodermal stimulation of the limbs were recorded in the raphe system of nuclei in unanesthetized, immobilized cats. Somatic stimuli were most effective. Acoustic and photic stimuli evoked ill-defined responses or (to acoustic stimulation) irregular responses of very low amplitude. In a second series of experiments on cats anesthetized with Nembutal (30–35 mg/kg) spontaneous and evoked (by somatic stimulation) single unit activity was studied in the caudal group of raphe nuclei. Most neurons 1) exhibited spontaneous activity which was modified (inhibited or facilitated) by somatic (especially repetitive) stimulation, and 2) responded to stimulation of the skin of any limb. During paired stimulation of the skin of limbs on different sides at long intervals (40–60 msec) the testing discharge was inhibited, while if the intervals were short, summation (simple addition) of the spikes took place. In their general characteristics, neurons of the raphe nuclei evidently differ very little from neurons of the brainstem reticular formation.

It was found that when hydrogen is oxidized in a quartz reactor washed with boric acid and prepared in such a way that vacuum grease and other contaminants are excluded, there is more than a tenfold decrease in the first ignition limit and a corresponding decrease in the probability of the heterogeneous destruction of the H atoms to a value of 10-6, and also the disappearance of “abnormally” high burnups of the 2H2 + O2 mixture.

The dependences of the maximum selectivity and the limiting yield of C2 hydrocarbons on the degree of methane conversion during its gas-phase oxidative coupling were calculated by means of kinetic simulation. The correlation between the results of the calculations and the rersults obtained in the experimental studies dealing with catalytic oxidative coupling of methane is discussed.

A kinetic simulation of the initiated oxidative condensation of methane in the gas phase showed that the additional generation of methyl radicalsvia the reaction CH4 + O2 ? CH3 + HO2 causes a nearly tenfold increase in the C2 hydrocarbon yield. However, a kinetic limit of the yield exists that is close to that determined in experiments on the catalytic oxidative condensation of methane.

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