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Objectives. To compare the effects of fragmentation of stage 3 and REM sleep on melatonin (MT) secretion and to evaluate the effects of changes in the autonomic balance and activation reactions occurring in the slow-wave and REM sleep phases. Materials and Methods. Fifteen healthy men took part in three experiments: with fragmentation of stage 3, with fragmentation of REM sleep, and a control experiment in which sleep was not disturbed. In each experiment, seven saliva samples were collected in the evening, at night, and in the morning, and MT contents were determined. Heart rate variability was analyzed using electrocardiogram recordings and the autonomic balance was assessed. Results. Sleep fragmentation was accompanied by activation reactions and decreases in the durations of stage 3 sleep and REM sleep by 50% and 51% in the corresponding experiments. Fragmentation of REM sleep also led to an increase in the duration of nocturnal waking. Sleep disturbances caused an increase in MT secretion in the second half of the night and in the morning, which was particularly marked in the experiments with REM sleep fragmentation, in which MT on waking was 1.8 times higher than in the controls. Stage 3 fragmentation was accompanied by increased sympathetic activation, while REM sleep fragmentation did not cause autonomic shifts. Subjects were divided into two clusters: with high and low MT in night-time and morning saliva samples. In all experiments, subjects with high MT had nocturnal waking lasting 1.7–2 times longer, while these subjects had significantly more activations in the REM sleep phase in the experiments with fragmentation. Conclusions. Nocturnal sleep disturbances increased MT secretion, which was particularly marked with fragmentation of REM sleep. Increases in MT levels were not dependent on changes in the autonomic balance and appeared to be associated with activation of the serotoninergic system, which accompanies impairments of the depth and continuity of sleep. [ABSTRACT FROM AUTHOR]

Adequate destruction of the aromatic structure in coal is key to further reducing the emission of pollutants. In this research, activation reactions of Shenmu coal powder were carried out in a vertical tube furnace. The study investigated the evolution mechanism of carbon covalent bonds during the activation process by altering the ratio of H2O to CO2 in the activation atmosphere. The theoretical validation was conducted through density functional calculations. The two gas molecules follow different pathways to increase the reactivity of char. CO2 mainly participates in the cross-linking reaction by intensifying branching, while H2O and char have lower adsorption energy barriers and are more likely to generate oxygen-containing functional groups. Gas molecules partially compete for active sites in a mixed gas atmosphere, but there is a synergism between the two effects. The synergism can be attributed to two possibilities. The inclusion of H2O mitigates the generation of five-membered rings to a limited extent, while concurrently enhances the development of oxygen-containing functional groups. Introducing oxygen-containing functional groups can effectively diminish the adsorption energy barrier associated with the interaction between gas molecules and char, consequently leading to a reduction in the energy demand for subsequent bond cleavage. [ABSTRACT FROM AUTHOR]

Ni-based alloy is an ideal candidate for its application in the field of hydrogen evolution of water splitting due to its good durability, excellent catalytic properties and low hydrogen evolution overpotential. In this paper, porous Ni-Sn alloy materials were prepared by activation reaction sintering, and the pore structure was tailored by adjusting Sn content. The effects of Sn content and electrolyte temperature on the hydrogen evolution properties of porous Ni-Sn alloy electrodes in 6 mol·L−1 KOH solution were studied by electrochemical measurement methods, such as cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI) and linear sweep voltammetry, and the mechanism of hydrogen evolution was further discussed. The experimental results reveal that when Sn content is 45 wt%, porous Ni-Sn alloy exhibits the best catalytic performance for hydrogen evolution with a Tafel slope of 164.69 mV·dec−1 and an overpotential of 170 mV. The tested electrode also shows good stability for hydrogen evolution in alkaline solution, and the apparent activation energy calculated at room temperature is 29.645 kJ·mol−1. The catalytic mechanism of hydrogen evolution is as follows: the addition of Sn significantly reduces the dissociation degree of M-H bonds, thereby reducing the overpotential of hydrogen evolution; with the increase of Sn content, the porous Ni-Sn electrode displays a higher electrochemical active surface area (ECSA), which makes porous Ni-Sn alloy exhibit good hydrogen evolution catalytic performance. [ABSTRACT FROM AUTHOR]

Ni-based alloy is an ideal candidate for its application in the field of hydrogen evolution of water splitting due to its good durability, excellent catalytic properties and low hydrogen evolution overpotential. In this paper, porous Ni-Sn alloy materials were prepared by activation reaction sintering, and the pore structure was tailored by adjusting Sn content. The effects of Sn content and electrolyte temperature on the hydrogen evolution properties of porous Ni-Sn alloy electrodes in 6 mol·L−1 KOH solution were studied by electrochemical measurement methods, such as cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI) and linear sweep voltammetry, and the mechanism of hydrogen evolution was further discussed. The experimental results reveal that when Sn content is 45 wt%, porous Ni-Sn alloy exhibits the best catalytic performance for hydrogen evolution with a Tafel slope of 164.69 mV·dec−1 and an overpotential of 170 mV. The tested electrode also shows good stability for hydrogen evolution in alkaline solution, and the apparent activation energy calculated at room temperature is 29.645 kJ·mol−1. The catalytic mechanism of hydrogen evolution is as follows: the addition of Sn significantly reduces the dissociation degree of M-H bonds, thereby reducing the overpotential of hydrogen evolution; with the increase of Sn content, the porous Ni-Sn electrode displays a higher electrochemical active surface area (ECSA), which makes porous Ni-Sn alloy exhibit good hydrogen evolution catalytic performance.

Formaldehyde is ubiquitous and harmful to human body. In this study, biochar graphene and composites are prepared by hydrothermal method. According to the material properties of formaldehyde, biochar composites are used to catalyze the two ends of electrode to promote the activation reaction of formaldehyde. By analyzing the characteristics of Fourier transform infrared spectrum image, it is found that the biochar composite Cu(OH)2/C is more conducive to activate formaldehyde, which effectively improves the conductivity of the material and provides a reference for studying the effects of biochar composites on formaldehyde. [ABSTRACT FROM AUTHOR]

Homogeneous olefin polymerization catalysts are activated in situ with a co-catalyst ([PhN(Me)2-H]+[B(C6F5)4]− or [Ph3C]+[B(C6F5)4]−) in bulk polymerization media. These co-catalysts are insoluble in hydrocarbon solvents, requiring excess co-catalyst (>3 eq.). Feeding the activated species as a solution in an aliphatic hydrocarbon solvent may be advantageous over the in situ activation method. In this study, highly pure and soluble ammonium tetrakis(pentafluorophenyl)borates ([Me(C18H37)2N-H]+[B(C6F5)4]− and [(C18H37)2NH2]+[B(C6F5)4]−) containing neither water nor Cl− salt impurities were prepared easily via the acid–base reaction of [PhN(Me)2-H]+[B(C6F5)4]− and the corresponding amine. Using the prepared ammonium salts, the activation reactions of commercial-process-relevant metallocene (rac-[ethylenebis(tetrahydroindenyl)]Zr(Me)2 (1-ZrMe2), [Ph2C(Cp)(3,6-tBu2Flu)]Hf(Me)2 (3-HfMe2), [Ph2C(Cp)(2,7-tBu2Flu)]Hf(Me)2 (4-HfMe2)) and half-metallocene complexes ([(η5-Me4C5)Si(Me)2(κ-NtBu)]Ti(Me)2 (5-TiMe2), [(η5-Me4C5)(C9H9(κ-N))]Ti(Me)2 (6-TiMe2), and [(η5-Me3C7H1S)(C10H11(κ-N))]Ti(Me)2 (7-TiMe2)) were monitored in C6D12 with 1H NMR spectroscopy. Stable [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]− species were cleanly generated from 1-ZrMe2, 3-HfMe2, and 4-HfMe2, while the species types generated from 5-TiMe2, 6-TiMe2, and 7-TiMe2 were unstable for subsequent transformation to other species (presumably, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-type species). [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species were also prepared from 5-TiCl(Me) and 6-TiCl(Me), which were newly prepared in this study. The prepared [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]−-, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-, and [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species, which are soluble and stable in aliphatic hydrocarbon solvents, were highly active in ethylene/1-octene copolymerization performed in aliphatic hydrocarbon solvents.

This paper presents the results of experimental studies of the dynamics of the functional state of a person within the zone of an active geological fault characterized by abnormal spatial distribution of the magnetic- field vector values. It is shown that these geophysical modifications have a pronounced effect on the fluctuations of the electrical activity of the human brain. When the person gets into a zone with abnormal levels of gradient magnetic field in the absence of any subjective sensations, a nonspecific orientation activation reaction is observed, which is characterized by a significant increase in the levels of peak performance in key functional EEG frequency bands. [ABSTRACT FROM AUTHOR]

In order to improve the catalytic activity and recycling performance of semiconductor activators, and improve the activation pathway of persulfate, graphitic carbon nitride (g-C 3 N 4 ) was prepared by calcining melamine, and a composite activator Ag 2 O/g-C 3 N 4 based on g-C 3 N 4 supported metal oxide was prepared using a precipitation method. The morphology, structure, and basic properties of the composites were characterized using SEM, XRD, FT-IR and XPS. The activation efficiency of the Ag 2 O/g-C 3 N 4 composite activator on peroxodisulfate (PDS) was explored. The results showed that Ag 2 O in the composite activator was highly dispersed on the surface of g-C 3 N 4 and did not change the molecular structure of g-C 3 N 4 significantly. Under different activation systems, the degradation process of MO was best fitted under the pseudo-second-order reaction kinetic model, compared to the separate g-C 3 N 4 or Ag 2 O activated PDS systems; the activation of the PDS system with Ag 2 O/g-C 3 N 4 had the best effect on MO degradation; and the composite activator Ag 2 O/g-C 3 N 4 showed better activation performance. Under the conditions that the mass combined ratio of Ag 2 O in the activator was 12%, the initial concentration of PDS was 4 mmol/L, the initial concentration of the activator was 1.25 g/L, and the initial pH was 3, the degradation degree of MO reached 99.4% after 40 min reaction. The free radical quenching experiment proved that the active substances that could degrade MO in the system were SO 4 - · and ·OH, and the effect of SO 4 - · was greater than that of ·OH. The degradation degree of MO in the reaction system remained above 80% after four cycles of use, and the crystal structure of Ag 2 O/g-C 3 N 4 did not change significantly before and after the reaction. The above results show that Ag 2 O/g-C 3 N 4 is an efficient and stable composite activator with good application potential in the treatment of dye wastewater by activating PDS.

The spectral powers (SPs) of the θ and α EEG rhythms were studied at different stages of visual set in children from five to seven years of age. Children with a plastic set had a greater α band SP than those with a rigid set. At the set formation stage, children with a rigid set displayed an increase in the SP of the θ band, which is a manifestation of an 'immature' activation reaction. Children with a plastic set exhibited an increase in the α band SP in the occipital lobes of both hemispheres. The dynamics of the SP of the EEG rhythms differed in children younger and older than six years. At the set formation stage, children from five to six years of age exhibited the above-mentioned 'immature' activation reaction, while those from six to seven years of age showed an increase in the α band SP in the occipital lobes. At the set actualization stage, an increase in the α band SP was observed in the right caudal areas, while the set extinction stage was marked by a bilateral depression of the α band in the frontal lobes. The importance of the involvement of specific cortical areas in visual perception and the formation of a plastic set is discussed. [ABSTRACT FROM AUTHOR]

The significance of the lateral geniculate body for nonspecific activation of the brain was elucidated in experiments on cats. It was established that when the connections of the lateral geniculate body remain intact, its stimulation elicits the usual activation of the EEG, but at higher threshold values of the current (120-190 μA) than when the mesencephalic recticular formation of the medial center of the thalamus is stimulated (50-80 μA). If only direct connections with the cortex remain, however, and the others are disrupted, the threshold for activation increases to 220-400 μA. When the lateral geniculate body is coagulated, cortical activity occurs only in response to very bright light flashes (250-1000 1x). All of this indicates that, in addition to carrying out its principal function of processing and sending the basic flow of visual impulsation to higher optical centers, the lateral geniculate body may be the source of activating transmissions sent to the cortex. Non-specific stimulation that develops in the cortex is subsequently regulated by the cortex itself; the cortex plays a leading role in these processes. [ABSTRACT FROM AUTHOR]

Homogeneous olefin polymerization catalysts are activated in situ with a co-catalyst ([PhN(Me)2-H]+[B(C6F5)4]− or [Ph3C]+[B(C6F5)4]−) in bulk polymerization media. These co-catalysts are insoluble in hydrocarbon solvents, requiring excess co-catalyst (>3 eq.). Feeding the activated species as a solution in an aliphatic hydrocarbon solvent may be advantageous over the in situ activation method. In this study, highly pure and soluble ammonium tetrakis(pentafluorophenyl)borates ([Me(C18H37)2N-H]+[B(C6F5)4]− and [(C18H37)2NH2]+[B(C6F5)4]−) containing neither water nor Cl− salt impurities were prepared easily via the acid–base reaction of [PhN(Me)2-H]+[B(C6F5)4]− and the corresponding amine. Using the prepared ammonium salts, the activation reactions of commercial-process-relevant metallocene (rac-[ethylenebis(tetrahydroindenyl)]Zr(Me)2 (1-ZrMe2), [Ph2C(Cp)(3,6-tBu2Flu)]Hf(Me)2 (3-HfMe2), [Ph2C(Cp)(2,7-tBu2Flu)]Hf(Me)2 (4-HfMe2)) and half-metallocene complexes ([(η5-Me4C5)Si(Me)2(κ-NtBu)]Ti(Me)2 (5-TiMe2), [(η5-Me4C5)(C9H9(κ-N))]Ti(Me)2 (6-TiMe2), and [(η5-Me3C7H1S)(C10H11(κ-N))]Ti(Me)2 (7-TiMe2)) were monitored in C6D12 with 1H NMR spectroscopy. Stable [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]− species were cleanly generated from 1-ZrMe2, 3-HfMe2, and 4-HfMe2, while the species types generated from 5-TiMe2, 6-TiMe2, and 7-TiMe2 were unstable for subsequent transformation to other species (presumably, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-type species). [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species were also prepared from 5-TiCl(Me) and 6-TiCl(Me), which were newly prepared in this study. The prepared [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]−-, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-, and [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species, which are soluble and stable in aliphatic hydrocarbon solvents, were highly active in ethylene/1-octene copolymerization performed in aliphatic hydrocarbon solvents. [ABSTRACT FROM AUTHOR]