bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of dynamic load from the wheel on the rail for high-speed trains in Uzbekistan
Authors: Djabarov Saidburkhan , Kodirov Nodirbek
Published: August 2023

On the basis of theoretical prerequisites and experimental studies, to substantiate the choice of factors that determine the formation of a dynamic load on the track from modern rolling stock for high-speed and high-speed traffic. As a result, a method for determining the vertical design force acting from the wheel on the rail is given. Methodology. Fundamental structural changes in high-speed and high-speed trains, a significant increase in the speed of movement lead to the need to revise the methods for calculating the effect of rolling stock on the railway track, the ratio of standard deviations of various dynamic forces, and assessing the influence of various factors for different speeds of movement. The paper also investigates the change in the dynamic load based on the results of experimental measurements. Results. The dependences of the average and calculated vertical forces on the speed of movement for modern passenger trains. Using factorial dispersion analysis, numerical characteristics of the impact of various factors on the value of the effect of the vertical force of the wheel on the rail are obtained. The degree of influence of various factors on the formation of the value of this force is established.
Engineering and consulting services for project management in construction
Authors: Luchkina V.V.
Published: August 2023

Engineering is described as an engineering and consulting activity related to the solution of various engineering tasks during the development and creation, as well as the improvement of products, systems or processes. Within the specific investment and construction project, practical engineering is professional services of a research, design, production and technological nature. The objective of this research is to study the issues of engineering and consulting in construction, the application of model laws on engineering and engineering activities in construction, questions about the need for engineering and consulting services for project management in construction. The following tasks were solved in the research itself: the need for the introduction of engineering and consulting services for project management in construction was identified and justified; checkpoints were identified of processes at the stage of completion of the construction digitalization project (by project participants) required for the provision of engineering and consulting services; indicators were identified to assess the effectiveness of the construction digitalization project; criteria have been developed for assessing the effectiveness of the implementation of the construction digitalization project and an algorithm for the integrated functioning of the work of Russian consulting engineers in construction. Consulting engineers in construction may use the results and recommendations of this research in the practice of engineering and consulting.
To the solution of the problem of longitudinal vibrations of multi-storey buildings on the basis of the plate model
Authors: Mamatisaev G.I. , Shamsiev D.K. , Askarhodjaev Sh.I. , Kurbanbaev M.Sh. , Yarashov J.A.
Published: August 2023

The article is devoted to the development of a continual spatial plate model of a multi-story building, developed in the framework of the bimoment theory of thick plates. A technique for dynamic spatial calculation for the seismic resistance of buildings under longitudinal seismic impacts is proposed. Formulas are given for determining the reduced moduli of elasticity. Numerical results of eigenfrequencies and displacements are obtained.
Estimation of the stress-strain state of orthotropic plates on elastic foundation using the bimoment theory
Authors: Usarov M.K. , Usanov F.A. , Usarov D.M. , Isaev G.U. , Toshmatov E.S.
Published: August 2023

The study is devoted to the development of the bimoment theory and the method for calculating thick plates in the framework of the three-dimensional theory of elasticity. The basic relations and equations of motion of the plate presented are constructed with respect to the forces, moments and bimoments arising from the nonlinearity of the law of distribution of displacements and stresses over the plate thickness. Bending and vibrations of isotropic and orthotropic plates are considered an example of calculations. The resulting solution showed the efficiency and accuracy of the proposed bimoment theory in assessing the stress-strain state of thick plates.
Heat exchange between the heating element and its shell under the boundary condition of the fourth kind
Authors: Kanareykin Aleksandr
Published: August 2023

In this article, the question of finding the temperature field of a heating element made in the form of a cylinder enclosed in a shell of cylindrical shape is considered. It is assumed that the thermal contact between the solid–coating systems is ideal. In this case, heat exchange occurs under boundary conditions of the third and fourth kind. In this paper, based on the methods of differentiation and integration, a solution was obtained to the problem of the distribution of the temperature field in both bodies. The resulting solution has an analytical form containing quadratic and logarithmic functions.
The role of public transport in the legitimation of power: regional aspect
Authors: Skiperskikh Aleksandr
Published: August 2023

The article shows how the transport problems of modern Russian regions can have a direct impact on the legitimacy of the government. Using the structuralist and neoinstitutional method, the author identifies the factors of legitimation/delegitimation of municipal and regional authorities. All the highlighted factors are relevant to the discourse of public transport and are given in special tables. The author focuses on specific examples of the connection of public transport problems with the policy of regional authorities. The dynamics of public trust in the government directly depends on the timeliness of solving these problems. Russian cities are in unequal economic conditions. In this sense, the dependence of the specifics of a single Russian city on the prospects for articulating the protest transport agenda is given. The author believes that such a political situation will continue to be relevant both for the authorities and for society.
Components and criteria of economic culture of future teachers
Authors: Quchqorova Nargiza
Published: August 2023

This article provides an integrated description of the teachings of Eastern and Western pedagogical psychologists on economics and economic culture, economic culture, a comprehensive approach to this process in relation to philosophical, legal, economic, sociological, psychological and pedagogical aspects. information is required. The components of economic culture are defined as economic education, economic education, economic activity, and the criteria for the development of economic culture: cognitive, motivational, creative-activity, and on the basis of these criteria are identified indicators corresponding to three (high, medium and low) levels. It has been proven that the formation of financial literacy of future educators is a social necessity.
Labor market in transition to digital economy: the way to cope with the problem of developing the social and labor relations
Authors: Otakuziyeva Z. , Usmanova N.
Published: August 2023

The world economy is undergoing a digital transformation, and it is happening at a tremendous rate. Today, the trend of digitization of various sectors of society is growing rapidly around the world. This process serves as a basis for the introduction of innovations and the improvement of the internal socio-economic situation. In this regard, many countries have begun to encourage and regulate the development of digital technologies in order to keep the positive effects and prevent negative consequences of transformation. With the emergence of the digital economy human and social capital are considered as key sources of welfare, that requires a conceptual shift in society, while the system of labor relations within such disruptive changes requires to be as responsive to changes as possible, from the positions of investments in human capital, adaptation to new conditions, and appropriate measures from the government. This paper outlines an approach proposed by the authors to represent the relations within the economic system of the labor market, wherein the model of labor relations can be defined as a set of relations between its subjects, with possibility to configure processes in appropriate/required way. Byassigning the components and levels for the system, along with defining specifications and/or attributes for model element, it is possible to explore complex relationships (processes, actions, etc.) within the system and evaluate the overall performance.
Economics and linguistics
Authors: Atadjanova Sevara , Kurbanova Ilmira
Published: August 2023

The economic theory of language policy interprets language as an economic phenomenon, the language situation as an economic, market situation, and language policy as an integral element of economic policy. The article presents an attempt to systematize and develop the theoretical and methodological aspects of this promising area of research at the intersection of economics and sociolinguistics.
Domestic sources of entrepreneurial capital formation
Authors: Saidboyev Shermirza
Published: August 2023

The relevance of the study lies in the formation of the source of capital of economic agents at the level of demand. In practice, it is known that the entrepreneur is not always able to generate sufficient financial resources that belong to him. The reason is that a change in the market conditions, regardless of the economic entity, results in a decrease in the planned profit. As a result, their liquidity is reduced. It is impossible to pay in front of customers. The unfavourable situation is reflected in the relations of economic entities with banks. In conclusion, the study of the internal source of capital of entrepreneurs and internal and external factors is an important problem of the national economy.
The relationship between service quality and insurance usage
Authors: Aldossary Malak , Siddiqui Kamran
Published: August 2023

The study aims to explain the impact of service quality on customer loyalty, satisfaction, and switching behaviors for insurance companies in Saudi Arabia. The study used the descriptive research approach. The questionnaire was developed with the help of reliable and validated constructs taken from earlier studies for service quality, customer loyalty, customer satisfaction, customer switching. Stratified sampling method was used to collect the data (N = 211). The results indicate that service quality has a statistically significant impact on customer loyalty and satisfaction for insurance companies in Saudi Arabia.
Features of the “Green” strategies for the development of banks
Authors: Niyazbekova Shakizada , Zverkova Anastasia , Sokolinskaya Natalia , Kerimkhulle Seyit
Published: August 2023

Banking Green Strategies in 2023 represent an important trend associated with the active development of environmentally sustainable and socially responsible business practices. Today, when issues of environmental sustainability have become especially acute, more and more banks are focusing on green development strategies that allow them not only to reduce the risks of environmental disasters and improve their public image, but also to generate additional income. Green strategies for the development of banks include several key indicators that are aimed at minimizing the negative impact of banking on the environment and society as a whole. Green banking already has significant experience in the developed countries of the world and is becoming more and more popular. Russian banks are also beginning to show interest in this area, and, probably, in the coming years, green banking will develop more actively in Russia.
The considerations for some aspects of cost accounting system methodology
Authors: Ismanov I.N.
Published: August 2023

The main purpose of accounting, more precisely, its component called financial accounting, is to form reliable information about the property status and financial results of the organization. In modern economic conditions, the business has been evaluated not only based on property status but also based on the results of the organization’s activities. Indeed, if the owner wants to reorganize production, to stop production altogether, it is important to assess the property status - in which case the information about the value of the property, and how much profit can be made from its sale is up to date. On the contrary, to develop the business, the enterprise needs to know more about the profitability of the enterprise, and its growth rates, when purchasing its shares in whole or in part, making decisions on lending, investing, and concluding cooperation agreements. This information will be the basis for thinking about the possibility of the enterprise not only once, but constantly earning more shortly, and accordingly to pay dividends, repay debts, and settle accounts with suppliers.
The impact of international sanctions on the “Uberization” and sustainable development of public finances
Authors: Burdelova Tatyana
Published: August 2023

The subject of the study is to minimize the risks of strengthening international financial sanctions on economic entities by building a decentralized mechanism for direct financing of budget recipients without the participation of the Federal Treasury in Russia, while ensuring that the payer fulfills its obligations and control over the targeted use of funds. The relevance of the study is to consider this mechanism in the context of international sanctions and as an alternative to a one-time collection from large businesses (windfall tax or tax on excessive profits of past years). The actuality is also confirmed by the use of the principle of “uberization” of relations between public finance entities, while the effectiveness and the need of “uberization” has already been confirmed in business practice. It is established that the financing of part of government spendings through such an alternative mechanism as “Uber” will reduce the sanctions risks for representatives of the business community. In the course of the study, specific examples of projects funded from the federal budget were analyzed, and these projects could first of all be transferred to the proposed new budget pilot financing mechanism. The conclusion is made about the efficiency of the proposed concept and the need for its further elaboration within the increased number 1) of enterprises and organizations directly financing the budget system expenditures on this electronic platform, and 2) of social, cultural and scientific projects financed with its help, gradually “uberizing” an increasing segment of budget financing.
Vibration processes resulting from uneven rotation of the hammer crusher drive pulleys
Authors: Kopeikin Artem , Palitsyn Andrey , Savinykh Petr
Published: August 2023

Livestock farming, as one of the main sectors of the agro-industrial cluster, cannot do without good quality forage. For the best absorption of feed, all the nutrients that make up its composition should be given to the animals in a milled form. Hammer mills are among the most compact machines for milling. The grinding of grain forages is a rather energy-intensive process. One of the variants for solving the power intensiveness problem can be the application of a a hammer crusher with periodic fluctuations in the angular speed in the rotation of the the working body. That is accompanied by the appearance of additional external stimulating force - vibration on the elements of a hammer crusher. In the article the question of vibration occurrence at non-uniform rotation of a crusher working body drive pulleys is considered. And such parameters as vibration acceleration, vibration displacement, and vibration velocity in three different axes are considered. In order to optimise the vibration parameters, experiments were carried out on units of different designs with different centre of rotation offset (2 mm). At this uneven rotation speed of 1800 min-1, the vibration velocity on the X-axis increased by 546% and 200%, depending on the machine design. The vibration displacement on the same axis, even at 450 min−1, increased by 442%. Based on these results, we examined the prerequisites for the investigated hammer crusher drive design, which is expected to improve the separation and evacuation process of the crushed product from the crushing chamber, and have an overall positive impact on the crushing process.
Improving the reliability of the joints of wooden elements on metal linings
Authors: Dezhin Maxim , Ibragimov Aleksandr
Published: August 2023

To date, the connections of wooden elements on metal linings are relevant. The purpose of the work is to develop measures aimed at improving the reliability of such connections. The article describes the main pads currently produced, their features, advantages and disadvantages are considered. The results of previously conducted tests are described, in which the main mechanism of destruction of samples is considered, which allowed modeling the real operation of the nodal interfaces of the main and secondary wooden beams on metal linings. By the nature of the destruction of the previously tested samples, it was found that the determining factor in the destruction of the samples was the insufficient value of the separation force of the metal lining from the wooden element due to the small value of the pulling force of the screws. Also, due to the imperfection of the design of the tested linings, significant crumpling was observed in some areas due to improper load distribution. According to the test results, it was found that there are several ways to increase the bearing capacity and reduce the deformability of the joints of wooden elements using metal linings. The first method involves achieving this goal by increasing the value of the separation force of the metal lining from the wooden element. The second method involves modifying the design of metal linings in order to correctly distribute the loads applied to the joint in the joint of the linings. As a result, a proprietary design of metal linings was developed, devoid of the disadvantages of similar linings, and an optimal option was proposed to increase the bearing capacity and reduce the deformability of the joints, thereby applying the two methods discussed above.
Determination of mechanical and tribotechnical properties of coatings during laser surfacing of tool steels
Authors: Biryukov Vladimir
Published: August 2023

The paper considers the results of metallographic studies and tribotechnical tests of samples of 9CrSi tool steel and multicomponent coatings obtained by laser surfacing with the addition of ultrafine titanium carbide particles into the charge. As an additional parameter, transverse high-frequency oscillations of the beam along the normal to the velocity vector of the laser surfacing were used. Tribotechnical tests were carried out according to the scheme “the plane is the end of an annular 40Cr steel plate with volumetric hardening”. To determine the critical sliding speeds, the tests were performed at a constant pressure of 2.5 MPa. Industrial I20 oil was fed into the friction zone. The minimum values of the friction coefficients depending on the sliding speed were obtained when 7 vol% titanium carbide was introduced into the multicomponent charge. The sliding speed to the bully increases by 2, 2.7 and 3.5 times when surfacing with a multicomponent charge without carbides and with the introduction of 4 and 7 vol% titanium carbide, respectively. Coatings with a high content of the hardening phase had the greatest wear resistance. Laser surfacing technology can be applied to the restoration of worn surfaces of rolls of rolling mills, die-cutting dies and other parts of die tooling.
Determining the optimum cut of sheet roll material
Authors: Mamaev Alexey , Balabina Tatiana , Karelina Maria
Published: August 2023

The profitability of forging and stamping plants is directly related to the economical use of raw materials. For sheet metal stamping, material losses can account for a significant proportion (up to 20-40%), so reducing them even by a few percent saves thousands of tonnes of sheet metal. An indicator of material utilisation efficiency and rationality of cutting is a material utilisation factor η, defined as a ratio of the weight of the workpiece to the rate of material consumption for its production. The value of material efficiency depends largely on the shape of the manufactured part, its location on the sheet (strip), and the size of the sheet (strip). One of the ways to save sheet material is by transferring parts from individual sheets to stamping directly from the sheet roll. Calculations for some types of products showed that the transition from pre-cutting of metallurgical rolling on guillotine or disk shears to cutting directly from the roll gives more than 3% of savings, and with chess-cutting this economy increases by 3-5 times. Bearing this in mind, it is of interest to find the optimum, in terms of economy of material, cutting of sheet coils when cutting out parts of various shapes, including round ones. This study solves the problem of determining a rational variant of sheet coil cutting for different sizes of sheet coils supplied by factories and diameters of cut out circles.
Determination of temperature fields and stresses during the construction of a massive monolithic foundation slab of a wind turbine tower
Authors: Zoalkfl Danial , Chepurnenko Anton , Yazyev Batyr , Ishchenko Aleksandr , Litvinov Stepan
Published: August 2023

The article proposes a method for determining temperature fields and stresses during the construction of massive monolithic structures in a two-dimensional axisymmetric formulation. The solution is performed using the finite element method. The calculation takes into account the shrinkage of concrete, as well as the change in its physical and mechanical characteristics over time. The problem of calculating a massive monolithic foundation of a wind turbine is presented. Recommendations are given to reduce the risk of early cracking.
Evaluating the efficiency of rail gauge maintenance in Siberia
Authors: Sevostyanov Aleksandr , Velichko Dmitry
Published: August 2023

The state of gauge geometry is the basis for safe and uninterrupted train operations under the mixed traffic conditions, as well as in the sections where trains with increased weight and length, including wagons with an increased axle load, are handled. When passing such trains, the state of gauge geometry deteriorates. This leads to increased labour costs for track maintenance, which is also caused by climatic features. Under such conditions, it is important to carry out effective gauge maintenance works. To analyse an impact of maintenance on gauge geometry, it is offered to determine the effect of uneven settlement of the under sleeper base in spring on the dynamics of each type of deviation. To evaluate the efficiency of preventive track alignment in the plan and profile, an analysis of graphical charts for the state of gauge geometry depending on track maintenance by gangs of track fitters and preventive track alignment by machine systems was carried out. It is also revealed that the efficiency of preventive alignment is significantly reduced under harsh climatic conditions, especially for the tonnage handled exceeding 600 million tonnes gross, and should therefore be carried out more frequently.
Proposals for reduction of the cost of ownership of agricultural machinery due to increase controllability and adaptability to diagnosis
Authors: Kostomakhin Mikhail , Kostomakhin Nikolay , Kataev Yury , Petrishchev Nikolay , Tseiko Mikhail
Published: August 2023

It is known that machinery in agriculture is used to perform work in optimal agricultural terms under difficult conditions, which requires constant improvement of approaches to determining the technical condition. Technical service is the main and most effective measure that ensures the maintenance of machines in working condition during the life cycle. At the same time, in order to objectively determine the technical condition of the machine, it is necessary to obtain an appropriate amount of data reliably describing this condition. Obtaining such data in the required volume will reduce the total cost of ownership and preserve the consumer properties of machines throughout the life cycle. As a result of the carried out research within the framework of the scientific topic "To develop a system of digital monitoring and diagnostics of the technical condition of agricultural machinery", projects were proposed to improve the controllability and adaptability to diagnostics to improve consumer qualities during the life cycle. The draft proposals are based on an analysis of the failure criteria for the complexity group, the existing Standards and Technical Documentation, as well as the capabilities of equipment manufacturers to carry out measures to manage reliability during the warranty and post-warranty periods of the life cycle equipment. During the study, special attention was paid to the possibilities of conducting non-selective diagnostics of components and assemblies using Predictive Maintenance Systems (PdM) to preserve the consumer properties of equipment.
Strategic opportunities for the development of digital platforms of industrial companies
Authors: Krasyuk Irina , Pasholikov Maxim
Published: August 2023

Industrial corporations are actively implementing digital technologies, which has an impact on the content of business models. The implementation of the platform approach is the main vector of strategic development of an industrial company. The platform approach changes the processes of industrial business modelling, which have an impact on competitiveness, and forms the leading positions of an industrial company in the market. Digital platforms are becoming the basis for the design of the technological chain, and business processes. The ecosystem nature of digital platforms contributes to the increase of business innovation activity. The functioning of the platforms is aimed at creating new values, implementing the concept of client-centricity, innovative development and the formation of competitive advantages. 36 technological platforms are used in Russia. The technological platform solves ecosystem tasks to ensure the functioning of the information and communication circuit of the digital ecosystem, which determines its strategic orientation.
The problem of propagation of a one-dimensional plastic wave in the environment with linear and polyline unloading
Authors: Atabaev K.
Published: August 2023

Problems of propagation of plane and spherical waves in a nonlinearly compressible medium with linear and broken line unloading under intense loads are considered. The solutions of the problems are constructed in the opposite way, assuming that the medium at the shock wave front is instantly loaded in a nonlinear manner, and behind the front in the perturbed region, the medium is irreversibly unloaded. For a specific structure of the medium, the results of calculations are presented in the form of graphs of pressure, velocity of the medium at the layer boundary, at the shock wave front and in the disturbed region as a function of time. The influence of the nonlinear properties of the medium on the distribution of the dynamic characteristics of shock-wave processes in it has been studied.
Thermodynamics of hydrogen sulfide adsorption in NaX zeolite
Authors: Dekhkanova Nigora , Abdurakhmonov Eldor , Rakhmatkarieva Feruza , Houlbert Isabelle , Jamoliddinova Nodirabegim
Published: August 2023

Sulfur-containing organic and inorganic compounds are the main harmful component of natural gas and oil, as well as products of their processing. Since sulfur compounds have acidic properties, their content leads to corrosion of technological parts in production processes. The content of hydrogen sulfide in the transported gas should not exceed 20 mg/m3. In Uzbekistan, motor vehicles run mainly on liquefied natural gas. Sulfur compounds in natural gas corrode gas cylinders, resulting in an explosion. If synthetic zeolites are used in manufacturing processes, as well as in small gas production, process degradation will be prevented. Synthetic zeolites are widely used in various industrial production processes due to their high sorption properties. This study makes it possible to study the localization and sorption structure of sulfur compounds in supercavities of zeolites of the faujasite type. The adsorption of hydrogen sulfide on NaX zeolite was carried out in a high vacuum adsorption unit. Based on the results obtained, the differential heat of adsorption, isotherm, entropy, and thermal equilibrium time (thermokinetics) were calculated.
Construction of a numerical model and algorithm for solving two-dimensional problems of filtration of multicomponent liquids, taking into account the moving “oil-water” interface
Authors: Nazirova E. Sh. , Nematov A. , Nabiyev I. M. , Shukurova M. E.
Published: August 2023

The paper considers a two-dimensional mathematical model of the filtration of a viscous, incompressible fluid in a deformable porous medium. The article describes a mathematical model of the problem at the “oil-water” interface with a system of parabolic differential equations. The problem posed is solved numerically using the differential-difference method based on the longitudinal-transverse scheme and the differential sweep method to determine the unknown boundary. To obtain a differential-difference problem, an algorithmic representation of a hidden scheme of alternating directions (longitudinal-transverse scheme) is used. The resulting system of differential-difference equations with initial conditions is known for each time layer along straight lines along the x axis, and then along each y axis it is solved by a differential sweep along a straight line, where the values just found correspond to time, i.e., the layer is taken as initial conditions. By approximating the differential equations in time, the position of the interface is determined for each time layer.
Un exemple d’intégration numérique des coefficients de poussée et de butée en milieux pesants
Authors: Burlon Sébastien
Published: August 2023

La détermination des coefficients de poussée et de butée constitue encore un enjeu majeur pour le dimensionnement des murs et des écrans de soutènement. Il est d’usage de déterminer ces coefficients en milieux pesants au moyen des tables de Caquot et Kerisel (1948) [Caquot A, Kerisel J. 1948. Tables de butée, de poussée et de force portante des fondations. Paris : Gauthier-Villars.] et Kerisel et Absi (1990) [Kerisel J, Absi E. 1990. Tables de poussée et de butée des terres. Paris : Presse de l’École Nationale des Ponts et Chaussées.] dont les valeurs sont calculées à partir de la théorie de Boussinesq (1876) [Boussinesq J. 1876. Essai théorique sur l’équilibre des massifs pulvérulents comparé à celui des massifs solides et sur la poussée des terres sans cohésion. Bruxelles : Hayez.]. Afin d’illustrer pratiquement la résolution des équations différentielles de cette théorie, cet article présente un exemple de méthode d’intégration numérique en exposant les différentes étapes suivies. Les résultats de cette méthode sont comparés à ceux de Caquot, Kerisel et Absi d’une part et de Sokolowski (1965) [Sokolowski VV. 1965. Statics of granular media. Oxford: Pergamon Press.] d’autre part. L’objectif est de revenir de manière originale et vulgarisée sur un problème complexe dont les sources sont de plus en plus rarement mises en avant. Il s’agit ainsi de permettre à chaque ingénieur qui utilise presque quotidiennement les valeurs des coefficients de poussée et de butée de mieux saisir leur origine et leur sens physique en se reportant le cas échéant à l’œuvre originale de Caquot et Kerisel (1949) [Caquot A, Kerisel, J. 1949. Traité de mécanique des sols. Paris : Gauthier-Villars.].
The Rheological Effects of X-Coating™ with Albumin and Hetastarch on Blood during Cardiopulmonary Bypass
Authors: Nutter Bernadette T. , Stammers Alfred H. , Schmer Ryan G. , Ahlgren Rebecca L. , Ellis Tunisia A. , Gao Chen , Holcomb Hunter B. , Hock Lynette , Burkeman Tab
Published: August 2023

Cardiopulmonary bypass (CPB) exposes blood to artificial surfaces, resulting in mechanical damage to the formed elements of the blood. The purpose of this study was to examine the effect of poly(2-methoxyethylacrylate) coating (PMEA, X-Coating™) on coagulation and inflammation under various prime conditions. An in vitro analysis was conducted utilizing fresh whole human blood (2 units) and a CPB circuit (n 18) consisting of a venous reservoir, oxygenator, and arterial filter. Nine nontreated circuits were used in a control group (CTR) and an equal number of tip-to-tip PMEA circuits for treatment (TRT). Each group was divided into three subgroups based upon prime: crystalloid, hetastarch (6%), and albumin (5%). CPB was conducted with a hematocrit 30% ± 2, temperature 37°C ± 1, and a flow of 4L/min. Samples were collected at 0, 60, 120, and 240 minute intervals. Endpoint measurements included thromboelastograph index (TI), and markers of inflammation and coagulation. The TI was significantly depressed in both groups when hetastarch was used in the prime. The TRT had significantly higher TI levels in both the crystalloid (0.3 ± 0.1 vs. −3.3±[1.2, P < .05) and albumin (0.6 ± 0.2 vs−3.9± −1.1. P < .03) subgroups compared to CTR groups. Platelet count was significantly higher in TRT as compared to CTR groups, except for both hetastarch groups. SEM demonstrated significant fibrin deposition on nontreated circuitry but little to no detection in the TRT group. In conclusion, both surface coating and prime components significantly effect coagulation, with PMEA circuits resulting in more favorable preservation of function.
Myocardial Protection of Warm Cardioplegic Induction on the Isolated Perfused Rat Heart Model
Authors: Li Shu , Lin Jing , Lenehan Eric , Liu Jinping , Long Cun , Liu Jin , Geng Yong J.
Published: August 2023

Myocardial protection through different cardioplegia approaches is an important issue for successful cardiovascular surgery. The objective of this prospective randomized study was to evaluate the effect of myocardial protection of warm (37°C) and cold (6°C) cardioplegic induction, respectively, using a Langendorff isolated rat heart perfusion model. Twenty-eight isolated rat hearts on the Langendorff perfusion model were randomly divided into two groups: group T (n 14) received warm (37°C) cardioplegic induction, followed by cold (6°C) cardioplegia after ECG showed straight line; alternatively, group C (n 14) received only cold cardioplegic induction. After undergoing ischemia for 80 min, both group T and group C received reperfusion with Krebs-Henseleit Buffer (KHB) for 40 min. An additional group A (n 7) received KHB continuously for 120 min and served as the control group for the assessment of Na+/K+ATPase activity. The coronary flow, concentration of creatine kinase (CK) in coronary effluent, and cardiac function were evaluated at different time periods. Na+/K+˚TPase activity was assessed at the end of reperfusion. The coronary flow, content of CK in coronary effluent, heart rate, dp/dtmax, and left ventricular peak pressure (LVPP) were significantly greater (p < .05) in group T than group C during the reperfusion period. The negative value of -dp/dtmax and left ventricular end-diastolic pressure (LVEDP) was significantly lower (p < .05) in group T than group C, during the reperfusion period. The Na+/K+-ATPase activity assessed at the end of reperfusion period was significantly higher (p < .05) in group A and group T than group C, while no significant difference (p .13) was found between group T and group A. Compared with cold cardioplegic induction, warm cardioplegic induction provides superior myocardial protection by enhancing coronary flow, reducing myocardial injury, improving cardiac function, and preserving Na+/K+-ATPase activity.
Limiting Circulatory Arrest Using Regional Low Flow Perfusion
Authors: Kilpack Vicki D. , Stayer Stephen A. , McKenzie E. Dean , Fraser Charles D. , Andropoulos Dean B.
Published: August 2023

Deep hypothermic circulatory arrest (DHCA) is commonly used for neonatal cardiac surgery. However, prolonged exposure to DHCA is associated with neurologic morbidity. The Norwood operation and aortic arch advancement are procedures that typically require DHCA during surgical correction. Regional low flow perfusion (RLFP) can be used to limit or exclude the use of circulatory arrest. This technique involves cannulation of the innominate or subclavian artery using a Gore-Tex graft, allowing isolated cerebral perfusion. Data was collected in 34 patients undergoing either neonatal aortic arch reconstruction or the Norwood procedure using RLFP. All patients had two arterial pressure monitors using either the umbilical or femoral artery catheters and radial or brachial catheters. Adequacy of perfusion was determined using cerebral saturation, blood flow velocity, mean arterial pressures, and arterial blood gas results. Cerebral saturation and blood flow velocity were monitored using the near-infrared spectroscopy (NIRS) (INVOS 5100, Somanetics Corp, Troy, MI) and a transcranial Doppler pulse-wave ultrasound (TCD) (EME Companion, Nicolet Biomedical, Madison, WI), respectively throughout the entire bypass period. Blood gases were monitored using a point of care blood gas analyzer (Gem Premier, Mallinckrodt Sensor System, Inc., Ann Arbor, MI). Data collected revealed total bypass times for repair between 69–348 min, with a mean of 180 min. Regional low flow perfusion times lasted between 6–158 min, with an average of 50 min., and DHCA times ranged from 0–66 min, with a mean of 19 min. The perfusion techniques used allowed patient clinical data to remain consistent throughout the cardiopulmonary bypass period, regardless of lower flows (Figure 1) The 30-day postoperative mortality rate was 2.9 %, with no evidence of neurologic injury during follow up. In conclusion, regional low flow cerebral perfusion might benefit patients by limiting the use of circulatory arrest during cardiac surgery. Further study is necessary to evaluate patient outcomes, comparing regional cerebral perfusion and circulatory arrest techniques.
Comparison of Heparin Administration Using the Rapidpoint™ Coag and Hepcon® HMS
Authors: Newsome Jason , Stipanovich Kerri , Flaherty Sarah
Published: August 2023

A retrospective chart review was conducted of patients who underwent cardiopulmonary bypass (CPB) to compare the quantities of heparin administered, postoperative blood loss, and homologous blood products transfused during their procedure and subsequent stay in the intensive care unit. The primary purpose of this review was to determine if any difference in heparin administration resulted when two different devices were used for dosing and monitoring heparin. Postoperative blood loss and amount of blood products transfused were also quantified, as any differences would potentially be a result of a difference in administration of heparin. The first group (n = 341) underwent CPB using the Hepcon® HMS, Medtronic Inc., Minneapolis, MN, for heparin dosing and monitoring. The Rapid Point™ Coag, Bayer Healthcare LLC, Tarrytown, NY was used for the second group (n = 345). The two populations were compared for similarity on: age, body surface area (BSA), CPB time (minutes), aortic-cross clamp time (minutes), baseline activated clotting time, and baseline hematocrit. No significant difference was found between the two groups. The second group, using the Rapidpoint™ Coag, received less heparin during CPB than the group using the Hepcon® HMS. In addition, there were decreases in amounts of some blood products transfused as well as mediastinal drainage from the Hepcon® HMS to the Rapidpoint™ Coag group. A summary of the findings can be found in Table 1. A secondary purpose of this study was to determine the influence of hemodilution on the Heparin Management Test (HMT®). Citrated whole blood was diluted to varying degrees at various concentrations to determine whether hemodilution with crystalloid would alter the HMT® measurements. At all heparin levels and degrees of dilution, the HMT® remained stable, with coefficients of variation (CV) of less than 5% at all heparin levels even while incorporating excessive crystalloid dilution (up to 75%).
Aortic Valve Replacement for a Patient with Essential Thrombocythemia: A Case Report
Authors: Englert Susan Jones , Jiang Jun
Published: August 2023

A 51-year-old male patient with 3+ aortic insufficiency, hepatitis C, osteomyelitis right foot, and a preoperative platelet count 1.3 million/mm3 required cardiopulmonary bypass (CPB). Essential thrombocythemia is a relatively unknown entity with the utilization of CPB. After consulting with the surgeon, an anesthesiologist and another perfusionist, a team approach was used to discuss treatment for this patient during CPB. The treatment consisted of exchange transfusions, autotransfusion techniques, and current protocol for blood gas management. No incidence of hypercoagulability was observed during this procedure or postoperatively. Based on current knowledge of pathophysiology and review of the literature, plateletpheresis should be the current management of essential thrombocythemia.
Mechanical Circulatory Support: Reality and Dreams Experience of a Single Center
Authors: Weitkemper H.-H. , El-Banayosy A. , Arusoglu L. , Sarnowski P. , Körfer R.
Published: August 2023

Because of the increasing number of patients waiting for heart transplantation and the decreasing number of donor organs, mechanical circulatory support has become a generally accepted therapeutic option. Several high-tech devices developed in the last 15 years differ in terms of location, kind of support, and driving units. They are suitable for different patients and their therapeutics objectives. Based on 13 years of experience, we developed a specific protocol for selection and management of patients and devices. Six hundred two patients have received mechanical circulatory support (MCS) in our institution since 1987. The indication spectrum includes cardiogenic shock for various reasons: acute myocarditis, right heart failure, acute rejection and postcardiotomy heart failure, alternative to transplantation, and bridge to recovery. Eight different systems are in use at our center. The extracorporeal devices, the Biomedicus centrifugal pump (n = 169) and the Abiomed BVS 5000 (n = 92) are used for short-term support. The Thoratec VAD (n = 179), and Medos HIA–VAD (n = 10) located in paracorporeal position preferably used for midterm support. Novacor LVAS (n = 96), and HeartMate (n = 58) are partially implantable systems used for long-term ventricular assistance in patients who did not require biventricular support. The advantage of the implantable devices is the option of discharging patients under support if they fulfill special criteria before being discharged to home. Eighty-five LVAD patients were discharged home with support, Novacor (n = 52), HeartMate (n = 27), ThoratecTLC-II (n = 8), Lionheart (n = 3) fulfill our criteria for being discharged home while on support. Careful postoperative patient management does not exclude a variety of complications. Bleeding: occurred in 22–35% of patients, right heart failure in 15–26%, neurologic disorder in 7–28%, infection in 7–30%, and liver failure in 11–20%. Complications varied with different devices, and the patients’ preoperative conditions. Eighty-five patients fulfilled the criteria of our out of hospital program (OOH) and were discharged from hospital for a mean period of 184 days. Readmission was necessary for complications caused by thromboembolism and infection. This report describes our patient device selection criteria as a bridge to transplant setting.
Internet-Based Virtual Classroom and Educational Management Software Enhance Students’ Didactic and Clinical Experiences in Perfusion Education Programs
Authors: Riley Jeffrey B. , Austin Jon W. , Holt David W. , Searles Bruce E. , Darling Edward M.
Published: August 2023

A challenge faced by many university-based perfusion education (PE) programs is the need for student clinical rotations at hospital locations that are geographically disparate from the main educational campus. The problem has been addressed through the employment of distance-learning environments. The purpose of this educational study is to evaluate the effectiveness of this teaching model as it is applied to PE. Web-based virtual classroom (VC) environments and educational management system (EMS) software were implemented independently and as adjuncts to live, interactive Internet-based audio/video transmission from classroom to classroom in multiple university-based PE programs. These Internet environments have been used in a variety of ways including: 1) forum for communication between the university faculty, students, and preceptors at clinical sites, 2) didactic lectures from expert clinicians to students assigned to distant clinical sites, 3) small group problem-based-learning modules designed to enhance students analytical skills, and 4) conversion of traditional face-to-face lectures to asynchronous learning modules. Hypotheses and measures of student and faculty satisfaction, clinical experience, and learning outcomes are proposed, and some early student feedback was collected. For curricula that emphasize both didactic and clinical education, the use of Internet-based VC and EMS software provides significant advancements over traditional models. Recognized advantages include: 1) improved communications between the college faculty and the students and clinical preceptors, 2) enhanced access to a national network of clinical experts in specialized techniques, 3) expanded opportunity for student distant clinical rotations with continued didactic course work, and 4) improved continuity and consistency of clinical experiences between students through implementation of asynchronous learning modules. Students recognize the learning efficiency of on-line information presentation but still prefer the traditional face-to-face classroom environment. Traditional paradigms impose limitations that are rooted in dependence upon the students and instructors being physically located in the same place at the same time. These represents significant impediments for PE programs that use geographically separate clinical sites to provide clinical experience. Historically this has led to a disintegration of the presentation of theory, and a reduction in the quantity or quality of clinical experience opportunities. New PE models help to eliminate limitations and improve the quality of education especially in the face of economic challenges. Perfusion education students and faculty will have to work together to find computer-based offerings that are equivalent to traditional classroom methods.