Study of the wear process of technological surfaces of saw gin grates

This paper presents the results of the theoretical studies of the process of wear of the technological surfaces of saw gin grates. Mathematical expressions are obtained, with the help of which it is possible to determine the theoretical statistical characteristics of the raw roller and it is indicated that the wear of the grate, in the process of operation from the impact of the raw roller, occurs as a result of the abrasive deposited on it. A rod model of the process of interaction between a raw roller and a grate has also been studied, on the basis of which it is possible to determine the depth of abrasive penetration in the contact surface of the working zone of the grate. The possibility of reducing the wear of grates by increasing the area of their technological surfaces and reducing, due to this, the probability of abrasive grains getting into the same place, is substantiated. A grate with a new convex shape of the technological surface is proposed. Calculations have determined that in this case the service life of the grate increases up to 50%

Sleep disorders and their relation to injuries among young elite soccer players

Aim: to study the quality of sleep and the relationship between sleep disorders and injury among young elite soccer players.Methods: the study summarizes data from relevant questionnaires obtained through anonymous cohort testing of 236 male football players from leading football academies, two farm teams of leading Russian Premier League clubs and three national youth teams.Results: the average sleep duration in the study participants was 9 hours. The prevalence of sleep disorders was 7 % (PSQI, Pittsburgh Sleep Quality Index) and 10 % (ASBQ, Athlete Sleep Behavior Questionnaire) and among the youngest soccer players, this prevalence of violations was the lowest. Significant or moderate daytime sleepiness was found in 59 % of participants. The risk of serious disorders increased with age. Sleep disorders significantly affected injuries according to the results of the PSQI questionnaire and retrospective collection of information about injuries.Conclusion: the confirmed relationship between injuries and sleep disorders allows us to consider sleep quality improvement as an important component of injury and morbidity prevention among athletes of team sports

The prevalence of alcohol and pre-workout caffeine consumption and their effect on injuries and sleep disorders in young elite soccer players

Aim: to study the prevalence of alcohol and pre-workout caffeine use and their impact on sleep quality and injury among the young soccer players.Methods: this study examined the prevalence of alcoholic beverages and pre-workout caffeine consumption in young soccer players, as well as the effect of these substances on sleep disorders and injuries among 236 elite athletes aged 11–21 years.Results: 16.5 % of soccer players use pre-workout caffeine. Most often 1–2 times per week. Caffeine consumption is weakly positively correlated with age (p < 0,001, R = 0,41.) and is most common in the age group of 19–21 years with consumption rates at 58.8 %. 17.3 % of young soccer players consume alcohol moderately and its consumption significantly correlates with age. Most often alcohol was consumed at the age of 19–21 years. Alcohol and caffeine consumption are significantly, but weakly correlated with the risk of severe sleep disorders on the Athlete Sleep Behavior Questionnaire (ASBQ). However, injuries during matches and training sessions did not depend on alcohol (p = 0.076) or caffeine (p = 0.14) consumption according to the Kraskal — Wallis test. At the same time, sleep disorders on the ASBQ significantly correlated with injury.Conclusion: the widespread use of alcohol and caffeine, and their negative impact on sleep among soccer players aged 11–21 years were revealed, but there was no connection between the use of these substances and injuries

СТРУКТУРА ТЕЧІЇ У СИСТЕМІ ТУРБУЛІЗАТОР – НІШОВА ПОРОЖНИНА

One way to significantly improve the efficiency of work combustion processes in stabilizer type burners is to use various means of intensifying of heat transfer and fuel burn. Such means include as follows: preheating the air, going to the combustion, air flow twisting, organization of developed surface ignition and combustion, increasing shading coefficient burner, use of additional elements of tubulisation etc. The existing papers devoted to the study of transport processes in the application of these ways of combustion intensification in stabilizer burners do not cover many aspects of this direction of research. Thus, the further development of research of flow characteristics, which largely determine the course of work processes in burners, deserves attention. Therefore our objective is to define patterns of flow in the system of angular turbulence stimulator-niche cavity modelling the main elements of the stabilizer type burner. Studies are conducted on the operation area at the following initial data: the height of the channel was operation area of 120 mm, width – 190 mm, length – 500 mm. Length niches downstream 75 mm, height – 35 mm. To measure the flow velocity of T-shaped pneumatic probe, using cement nozzle Witoszynskyj was used. First of all, comparison of velocity profiles in various vertical sections of niche cavities in the plane of symmetry of turbulence stimulator for the present and absent of availability of turbulence stimulator of flow indicates that without of turbulence stimulator reverse flows zone is significantly pressed to the niche bottom. That is if turbulence stimulators are installed behind niche cavity reverse flows zone is visible pressed against the bottom of the niche. Secondly, there is a tendency to the emergence of forward flow near the wall stabilizer in the area of the location of the turbulence stimulator. There is a direct-flow trend outside return flows zone of turbulence stimulator, accelerated down the stream as you approach to the section x = 120 mm, which corresponds to the maximum width of said zone. Further down the stream-flow this trend is slowed. The return flows zone behind the turbulence stimulator appears more clearly on some distance from the wall of the turbulence stimulator. This fact becomes evident due to effect of the emergence of forward flow in the wall area of the stabilizer. Thus, the analysis of experimental data on flow patterns in the system of corner vortex flow is niche cavity. Setting of angle vortex flow on a section of the back wall of the niche leads to inhibition of specific areas of backward flows in the niche cavity and pressed it to the bottom of the niche.По результатам экспериментальных исследований приведены данные о характеристиках течения в системе угловой турбулизатор – нишевая полость, моделирующей основные элементы стабилизаторного горелочного устройства. Проанализированы особенности циркуляционных течений за угловым турбулизатором потока и в собственно нише. Представлены результаты сравнения особенностей течения в нишевой полости при наличии и отсутствии турбулизаторов потока. Исследовано влияние установления угловых турбулизаторов потока на задней кромке ниши на специфику течения в зоне обратных токов в нишевой полости.За результатами експериментальних досліджень наведено дані про характеристики течії у системі кутовий турбулізатор – нішова порожнина, що моделює основні елементи стабілізаторного пальникового пристрою. Проаналізовано особливості циркуляційних течій за кутовим турбулізатором потоку та у власне ніші. Подано результати порівняння особливостей течії у нішовій порожнині за наявності та відсутності турбулізаторів потоку. Досліджено вплив встановлення кутових турбулізаторів потоку на зрізі задньої стінки ніші на специфіку течії в зоні зворотних токів у нішовій порожнині

ON THE APPLICATION OF STILL VISUERS IN SPINAL MANUFACTURE

In this article we consider the application of fixed finches in spinning production. The technique and experimental studies of the appearance of latent drawing in the feeding zone of machines of the spinning department are presented. Also, studies are shown using an immovable fin on a spinning machine, a regression model obtained, a simplified design scheme for false twist, depending on the thickness of the roving, the location of the finch and its dynamics

Organometallic and coordination chemistry of (Tetramethylcyclobutadiene)cobalt sandwich and halfsandwich complexes

This thesis consists of two parts. Part one is devoted to the development of (tetramethylcyclobutadiene)cobalt (Cb*Co) tris(ligand) complexes [Cb*Co(L)3]+. An improved synthesis of the starting materials [Cb*Co(CO)3]BF4, Cb*CoI(CO)2 and [Cb*Co(C6H6)]PF6 was developed. Photolysis of [Cb*Co(C6H6)]PF6 in acetonitrile produced [Cb*Co(NCMe)3]PF6. Alternatively, the tris(acetonitrile) complex was obtained via thermal substitution of benzene by acetonitrile when heating [Cb*Co(C6H6)]PF6 in acetonitrile. Complex cation [Cb*Co(NCMe)3]+ is substitutionally labile and reacts with Lewis bases to form cations of the type [Cb*CoL3]+, notably L3 = Cp-. The first structural characterizations of tris(ligand) complex cations [Cb*CoL3]+ with L = CO and MeCN are presented. The second part of the thesis describes reaction chemistry of the novel sigma,eta4-butadienyl (carbenoid) complex ion [CpCo(sigma,eta4-C4HsynMe4)]+, formed by protonation of CpCoCb*, and chemistry of a number of products derived thereof. Above -10°C the carbenoid cation undergoes a thermal rearrangement to produce the half-open cobaltocenium ion [CpCo(eta5-C5H4Me3)]+. The protonation of CpCoCb* was shown to be reversible under conditions of low proton activity. Thus deprotonation of the s,h4-butadienyl complex with one equivalent of NEt3 mainly gave CpCoCb*, whereas reaction with excess NEt3 afforded a hexatriene complex CpCo[eta4-C4HsynMe3(CH2)]. The carbenoid complex underwent nucleophilic addition reactions. Addition of CNtBu produced a (tert-butylamino)cobaltocenium ion [CpCo{eta5-C5Me4(NHtBu)}]+. Addition of excess PPh3 gave a phosphonio cation [CpCo{eta4-C4HantiMe4(PPh3)}]+. With pyridine four reaction channels were revealed: i) reversible deprotonation to the hexatriene complex; ii) reversible nucleophilic addition at the carbenoid center to form [CpCo{eta4-C4HsynMe4(NC5H5)}]+; iii) stereoisomerization to form a more stable isomer, [CpCo{eta4-C4HantiMe4(NC5H5)}]+; iv) very slow formation of the CpCoCb*. The more stable isomeric pyridine addition product underwent nucleophilic substitution reactions with 4-picoline to afforded the 4-picoline addition product and with CN– to yield a hexa-2,4-dienenitrile complex [CpCo(eta4-C4HantiMe4CN)]. The latter on protonation gave an aminocobaltocenium ion [CpCo{eta5-C5Me4(NH2)}]+. With CNtBu [CpCo{eta5-C5Me4(NHtBu)}]+ was formed. Acid removes pyridine from [CpCo{eta4-C4HantiMe4(NC5H5)}]+ to produce an isomeric carbenoid ion [CpCo(sigma,eta4-C4HantiMe4)]+, which again could be reacted with excess NEt3 to afford the isomeric hexatriene complex CpCo[eta4-C4HantiMe3(CH2)]. Thermolyses of CpCo[eta4-C4HsynMe3(CH2)] and CpCo[eta4-C4HantiMe3(CH2)] show that the later is the lower-energy isomer and produce a dinuclear complex (my-C5H3Me3)(CoCp)2 (Co–Co) with a bridging penta-2,4-dienylidene ligand

Organometallic and coordination chemistry of (Tetramethylcyclobutadiene)cobalt sandwich and halfsandwich complexes

This thesis consists of two parts. Part one is devoted to the development of (tetramethylcyclobutadiene)cobalt (Cb*Co) tris(ligand) complexes [Cb*Co(L)3]+. An improved synthesis of the starting materials [Cb*Co(CO)3]BF4, Cb*CoI(CO)2 and [Cb*Co(C6H6)]PF6 was developed. Photolysis of [Cb*Co(C6H6)]PF6 in acetonitrile produced [Cb*Co(NCMe)3]PF6. Alternatively, the tris(acetonitrile) complex was obtained via thermal substitution of benzene by acetonitrile when heating [Cb*Co(C6H6)]PF6 in acetonitrile. Complex cation [Cb*Co(NCMe)3]+ is substitutionally labile and reacts with Lewis bases to form cations of the type [Cb*CoL3]+, notably L3 = Cp-. The first structural characterizations of tris(ligand) complex cations [Cb*CoL3]+ with L = CO and MeCN are presented. The second part of the thesis describes reaction chemistry of the novel sigma,eta4-butadienyl (carbenoid) complex ion [CpCo(sigma,eta4-C4HsynMe4)]+, formed by protonation of CpCoCb*, and chemistry of a number of products derived thereof. Above -10°C the carbenoid cation undergoes a thermal rearrangement to produce the half-open cobaltocenium ion [CpCo(eta5-C5H4Me3)]+. The protonation of CpCoCb* was shown to be reversible under conditions of low proton activity. Thus deprotonation of the s,h4-butadienyl complex with one equivalent of NEt3 mainly gave CpCoCb*, whereas reaction with excess NEt3 afforded a hexatriene complex CpCo[eta4-C4HsynMe3(CH2)]. The carbenoid complex underwent nucleophilic addition reactions. Addition of CNtBu produced a (tert-butylamino)cobaltocenium ion [CpCo{eta5-C5Me4(NHtBu)}]+. Addition of excess PPh3 gave a phosphonio cation [CpCo{eta4-C4HantiMe4(PPh3)}]+. With pyridine four reaction channels were revealed: i) reversible deprotonation to the hexatriene complex; ii) reversible nucleophilic addition at the carbenoid center to form [CpCo{eta4-C4HsynMe4(NC5H5)}]+; iii) stereoisomerization to form a more stable isomer, [CpCo{eta4-C4HantiMe4(NC5H5)}]+; iv) very slow formation of the CpCoCb*. The more stable isomeric pyridine addition product underwent nucleophilic substitution reactions with 4-picoline to afforded the 4-picoline addition product and with CN– to yield a hexa-2,4-dienenitrile complex [CpCo(eta4-C4HantiMe4CN)]. The latter on protonation gave an aminocobaltocenium ion [CpCo{eta5-C5Me4(NH2)}]+. With CNtBu [CpCo{eta5-C5Me4(NHtBu)}]+ was formed. Acid removes pyridine from [CpCo{eta4-C4HantiMe4(NC5H5)}]+ to produce an isomeric carbenoid ion [CpCo(sigma,eta4-C4HantiMe4)]+, which again could be reacted with excess NEt3 to afford the isomeric hexatriene complex CpCo[eta4-C4HantiMe3(CH2)]. Thermolyses of CpCo[eta4-C4HsynMe3(CH2)] and CpCo[eta4-C4HantiMe3(CH2)] show that the later is the lower-energy isomer and produce a dinuclear complex (my-C5H3Me3)(CoCp)2 (Co–Co) with a bridging penta-2,4-dienylidene ligand

Study of the wear process of technological surfaces of saw gin grates

This paper presents the results of the theoretical studies of the process of wear of the technological surfaces of saw gin grates. Mathematical expressions are obtained, with the help of which it is possible to determine the theoretical statistical characteristics of the raw roller and it is indicated that the wear of the grate, in the process of operation from the impact of the raw roller, occurs as a result of the abrasive deposited on it. A rod model of the process of interaction between a raw roller and a grate has also been studied, on the basis of which it is possible to determine the depth of abrasive penetration in the contact surface of the working zone of the grate. The possibility of reducing the wear of grates by increasing the area of their technological surfaces and reducing, due to this, the probability of abrasive grains getting into the same place, is substantiated. A grate with a new convex shape of the technological surface is proposed. Calculations have determined that in this case the service life of the grate increases up to 50%