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In the engineering praxis, Newton?s law of viscosity and Fourier?s heat conduction law are applied to describe thermomechanical processes of fluids. Despite several successful applications, there are some obscure and unexplored details, which are partly answered in this paper using the methodology of irreversible thermodynamics. Liu?s procedure is applied to derive the entropy production rate density, in which positive definiteness is ensured via linear Onsagerian equations; these equations are exactly Newton?s law of viscosity and Fourier?s heat conduction law. The calculations point out that, theoretically, the transport coefficients (thermal conductivity and viscosity) can also depend on the gradient of the state variables in addition to the wellknown dependence of the state variables. This gradient dependency of the transport coefficients can have a significant impact on the modeling of such phenomena as welding, piston effect or shock waves.

Due to technological advancement, as materials with complex structures (e.g., metamaterials and foams) appear in practice there is a need to develop advanced thermal models. These are called non-Fourier equations, and all have particular mathematical properties differing from the conventional attributes of Fourier's law. The present paper discusses the thermodynamic origin of non-Fourier equations and their consequences. The second law of thermodynamics influences the relations among the material parameters, and therefore, it restricts how the temperature-dependent properties can be included in the model. Furthermore, we present the properties of initial and boundary conditions, since these are crucial in solving any practical problems and are different from the usual interpretation used for the Fourier equation.

The novel concept of spectral diffusivity is introduced to analyse the dissipative properties of continua. The dissipative components of a linear system of evolution equations are separated into noninteracting parts. This separation is similar to mode analysis in wave propagation. The new modal quantities characterise dissipation and best interpreted as effective diffusivities, or, in case of heat conduction, as effective heat conductivities of the material., 8 pages, no figures

The aim of this paper is to estimate the damage of railway carriage wheels caused by lock-up braking. First, we investigate the typical characteristics of wheel-rail contact including the parameters of contact patch, longitudinal creep and coefficient of adhesion. Then we show the current requirements concerning the wheel-slide protection systems and determine the points which should be reviewed. To predict the effect of the sliding phenomenon, material properties are needed, as well. Afterwards, a simplified thermal simulation is built to estimate where martensite formation may occur.

Background Facebook can be a suitable platform for public health interventions. Facebook users can express their reaction to the given social media content in many ways using interaction buttons. The analysis of these interactions can be advantageous in increasing reach and engagement of public health interventions. Objective This research aimed at understanding how Facebook users’ interactions correlate with organic reach and engagement regarding the same smoking cessation support contents. Methods The study population consisted of Facebook users who were reached by a public smoking cessation support page without advertising. We included 1025 nonpaid Facebook posts (N=1025) which used smoking cessation strategies based on a motivational interviewing counseling style. The following data were collected from the “Post Details”: the number of people who saw the given nonpaid content (organic reach) which consisted of fan and nonfan reach according to previous “page like” activity; each rate of “engagement indicators” (such as the symbols of “like,” “love,” “haha,” “wow,” “sad,” “angry”; or other interactions: “shares,” “comments,” “clicks”); and the rate of negative Facebook interactions (eg, “post hides” or “unlike of page”). Overall, these data were analyzed with the Spearman correlation method. Results Surprisingly, we found a significant negative correlation between organic reach and the “like” reaction (rs=–0.418; P Conclusions This study has shown that it is possible to hypothesize a disadvantage of the “like” reaction and advantages of other interactions (eg, the “haha” reaction or “comments”) in content algorithmic ranking on Facebook. In addition, the correlational analysis revealed a need of a further categorization to fan-specific interactions (eg, “haha” or “love” reactions) and nonfan-specific interactions (eg, “shares” and “clicks”). Regarding the direction of the correlations, these findings suggest that some interactions (eg, negative Facebook interactions, “wow,” “sad,” and “angry” reactions) may decrease the engagement, while other interactions (“like,” “love,” “haha” reactions, “shares,” and “clicks”) may increase the engagement during Facebook-based smoking cessation interventions. This hypothesis-generating research offers an important insight into the relationship between organic reach, engagement, and Facebook users’ interactions for public health professionals who design Facebook-based interventions.

Summary of the long term data taking, related to one of the proposed next generation ground-based gravitational detector's location is presented here. Results of seismic and infrasound noise, electromagnetic attenuation and cosmic muon radiation measurements are reported in the underground Matra Gravitational and Geophysical Laboratory near Gy\"ongy\"osoroszi, Hungary. The collected seismic data of more than two years is evaluated from the point of view of the Einstein Telescope, a proposed third generation underground gravitational wave observatory. Applying our results for the site selection will significantly improve the signal to nose ratio of the multi-messenger astrophysics era, especially at the low frequency regime., Comment: 47 pages, 37 figures

Environmental estrogens are a serious concern worldwide due to their ubiquity and adverse ecotoxicological and health effects. Chemical structure of these substances is highly diverse, therefore estrogenicity cannot be predicted on the basis of molecular structure. Furthermore, estimation of estrogenicity of environmental samples based on chemical analytics of suspects is difficult given the complex interaction of chemicals and the impact on estrogenicity. The full estrogenic impact of an environmental sample can thus only be revealed by a series of sensitive in vitro and in vivo ecotoxicological tests. Herein we describe a vitellogenin reporter transgenic zebrafish line (Tg(vtg1:mCherry)) that enables the detection of estrogenicity in the environmentally relevant, low concentration ranges in embryonic tests that are in accordance with 3Rs and relevant animal welfare regulations. The transgene construct used for the development of Tg(vtg1:mCherry) carried a long (3.4 kbp) natural vitellogenin-1 promoter sequence with a high number of ERE sites. A test protocol was developed based on our finding that the endogenous vitellogenin and the reporter show similar spatial expression pattern and both endogenous and vitellogenin reporter is only produced in the left hepatic lobe of 5 dpf zebrafish embryos. Seven generations of Tg(vtg1:mCherry) have been established, and the estrogen responsiveness was tested with different estrogenic substances and wastewater samples. Embryos were exposed from 3 to 5 days post fertilization (dpf). Fluorescence in embryos could be detected upon treatment with 17-s-estradiol from a concentration of 100 ng/L, 17-α-ethynilestradiol from 1 ng/L, zearalenone from 100 ng/L and bisphenol-A from 1 mg/L. In the adult stage transgene activity appeared to be more sensitive to estrogen treatment, with detectable transgene activity from 5 ng/L 17-s-estradiol concentration. The transgenic line Tg(vtg1:mCherry) was also suitable for the direct measurement of estrogenicity in wastewater samples without sample extraction. The detection of estrogenic activity using the reporter line was confirmed by the bioluminescent yeast estrogen screen.

Abstract: Introduction: The possibility of successful smoking cessation is increased by early initiation. Therefore, promoting smoking cessation at early age (especially among 14–35-year-olds) has a key role in reducing tobacco use prevalence. Facebook is one of the most popular websites among adolescents and young adults which can be used for age-specific smoking cessation support. Aim: Our research seeks to reveal the effects of a Facebook page on smoking habits, smoking cessation knowledge and attitudes among 14–35-year-olds. Method: An online survey was conducted among the 3278 followers of the author’s Facebook page. The questionnaire was completed by 332 people among 14–35-year-olds. We analysed demographic data, smoking habits, the usage frequency and duration of the Facebook page as well as changes in smoking habits, smoking cessation knowledge and attitudes. Results: The average age was 22.57 ± 5.08 years. The examined population consisted of 65% currently smokers, 12% former smokers and 23% non-smokers. Significantly more people reported a positive change in their smoking habits and smoking cessation attitudes among smokers who used the Facebook page more frequently and with longer duration (p

It is well-known that the Fourier equation for heat conduction is not satisfactory in many cases, such as low-temperature situations. It motivated the researchers to find possible extensions. There are numerous approaches in the literature, here we apply non-equilibrium thermodynamics with internal variables. The first, and successfully applied generalized constitutive equation is called Maxwell-Cattaneo-Vernotte (MCV) equation. It is quite straightforward to derive using the internal variable theory. However, when nonlinear attributes come into the picture, there are some significant consequences that must be investigated further. In the present paper [1], we are considering temperature-dependent material parameters, e.g., the thermal conductivity and the relaxation time both depend on the temperature. A consistent analysis shows that in some cases, the temperature dependence of mass density follows immediately. It cannot be avoided; thus, the mechanical field has to be introduced to obtain a physically admissible solution. On the other hand, we investigated the numerical solutions of such a nonlinear MCV equation. We found that the nonlinear numerical stability analysis can be substituted with the linear one by estimating the maximum of the temperature field apriori. Here, we present the effects of temperature dependence and demonstrating the usage of the developed numerical code. [1] R. Kovacs, P. Rogolino: Numerical treatment of nonlinear Fourier and Maxwell-Cattaneo-Vernotte heat transport equations, Accepted in International Journal of Heat and Mass Transfer, 2019. Arxiv: 1910.09175

The accuracy of the classical heat conduction model, known as Fourier's law, is highly questioned, dealing with the micro and nanosystems and biological tissues. In other words, the results obtained from the classical equations deviate from the available experimental data. It means that the continuum heat diffusion equation is insufficient and inappropriate for modeling heat transport in these cases. There are several techniques for modeling non-Fourier heat conduction. In the present paper, we place our focus on the dual-phase-lag (DPL) approach. The DPL model, as a popular modification of Fourier's law, has already been utilized in numerous situations, such as simulating ultrafast laser heating and heat conduction in carbon nanotubes. There has been a sharp increase in research on non-Fourier heat conduction in recent years. Several studies have been performed in the fields of thermoelasticity, thermodynamics, transistor modeling, and bioheat transport. This review presents the most recent non-Fourier bioheat conduction works and the related thermodynamics background. The various mathematical tools, modeling different thermal therapies, and relevant criticisms and disputes are discussed. Finally, the novel and other possible studies are also presented to provide a better overview, and the roadmap to the future research and challenges ahead is drawn up., 81 pages, 4 figures

BACKGROUND Facebook can be a suitable platform for public health interventions. Facebook users can express their reaction to the given social media content in many ways using interaction buttons. The analysis of these interactions can be advantageous in increasing reach and engagement of public health interventions. OBJECTIVE This research aimed at understanding how Facebook users’ interactions correlate with organic reach and engagement regarding the same smoking cessation support contents. METHODS The study population consisted of Facebook users who were reached by a public smoking cessation support page without advertising. We included 1025 nonpaid Facebook posts (N=1025) which used smoking cessation strategies based on a motivational interviewing counseling style. The following data were collected from the “Post Details”: the number of people who saw the given nonpaid content (organic reach) which consisted of fan and nonfan reach according to previous “page like” activity; each rate of “engagement indicators” (such as the symbols of “like,” “love,” “haha,” “wow,” “sad,” “angry”; or other interactions: “shares,” “comments,” “clicks”); and the rate of negative Facebook interactions (eg, “post hides” or “unlike of page”). Overall, these data were analyzed with the Spearman correlation method. RESULTS Surprisingly, we found a significant negative correlation between organic reach and the “like” reaction (rs=–0.418; Ps=0.396; Ps=0.368; Ps=0.264; Ps=0.388; Ps=0.135; Ps=0.457; Ps=0.393; Ps=0.310; Ps=–0.077; P=.013), “sad” (rs=–0.120; Ps=–0.136; Ps=–0.130; Ps=0.076; P=.016) and “sad” reactions (rs=0.091; P=.003). CONCLUSIONS This study has shown that it is possible to hypothesize a disadvantage of the “like” reaction and advantages of other interactions (eg, the “haha” reaction or “comments”) in content algorithmic ranking on Facebook. In addition, the correlational analysis revealed a need of a further categorization to fan-specific interactions (eg, “haha” or “love” reactions) and nonfan-specific interactions (eg, “shares” and “clicks”). Regarding the direction of the correlations, these findings suggest that some interactions (eg, negative Facebook interactions, “wow,” “sad,” and “angry” reactions) may decrease the engagement, while other interactions (“like,” “love,” “haha” reactions, “shares,” and “clicks”) may increase the engagement during Facebook-based smoking cessation interventions. This hypothesis-generating research offers an important insight into the relationship between organic reach, engagement, and Facebook users’ interactions for public health professionals who design Facebook-based interventions.

Applying simultaneously the methodology of Non-Equilibrium Thermodynamics with Internal Variables (NET-IV) and the framework of General Equation for the Non-Equilibrium Reversible-Irreversible Coupling (GENERIC), we demonstrate that, in heat conduction theories, entropy current multipliers can be interpreted as relaxed state variables. Fourier's law and its various extensions -- the Maxwell-Cattaneo-Vernotte, Guyer-Krumhansl, Jeffreys type, Ginzburg-Landau (Allen-Cahn) type and ballistic-diffusive -- heat conduction equations are derived in both formulations. Along these lines, a comparison of NET-IV and GENERIC is also performed. Our results may pave the way for microscopic/multiscale understanding of beyond-Fourier heat conduction, and open new ways for numerical simulations of heat-conduction problems., Comment: 28 pages

The thermal modeling of biological systems has increasing importance in developing more advanced, more precise techniques such as ultrasound surgery. One of the primary barriers is the complexity of biological materials: the geometrical, structural, and material properties vary in a wide range, and they depend on many factors. Despite these difficulties, there is a tremendous effort to develop a reliable and implementable thermal model. In the present paper, we focus on the continuum modeling of heterogeneous materials with biological origin. There are numerous examples in the literature for non-Fourier thermal models. However, as we realized, they are associated with a few common misconceptions. Therefore, we first aim to clarify the basic concepts of non-Fourier thermal models. These concepts are demonstrated by revisiting two experiments from the literature in which the Cattaneo-Vernotte and the dual phase lag models are utilized. Our investigation revealed that using these non-Fourier models is based on misinterpretations of the measured data, and the seeming deviation from Fourier's law originates in the source terms and boundary conditions.

It is a long-lasting task to understand heat conduction phenomena beyond Fourier. Besides the low-temperature experiments on extremely pure crystals, it has turned out recently that heterogeneous materials with macro-scale size can also show thermal effects that cannot be modeled by the Fourier equation. This is called over-diffusive propagation, different from low-temperature observations, and is found in numerous samples made from metal foam, rocks, and composites. The measured temperature history is indeed similar to what Fourier’s law predicts but the usual evaluation cannot provide reliable thermal parameters. This paper is a report on our experiments on several rock types, each type having multiple samples with different thicknesses. We show that size-dependent thermal behavior can occur for both Fourier and non-Fourier situations. Moreover, based on the present experimental data, we find an empirical relation between the Fourier and non-Fourier parameters, which may be helpful in later experiments to develop a more robust and reliable evaluation procedure.

Imatinib mesylate (IM) is an anticancer drug that belongs to tyrosine kinase inhibitors. We report the results of the first investigation of the chronic exposure of zebrafish (Danio rerio) to IM. The exposure to IM (0.01, 1 and 100 μg/L) was initiated in adult fish and continued through hatching and the offspring generation for seven months. In addition to standard toxicological endpoints, induction of genotoxic effects and whole-genome transcriptome of liver samples of offspring generation of zebrafish were analysed. Exposure to IM did not affect the survival and growth of zebrafish, did not cause any histopathological changes, but it induced a marginal increase in the chromosomal damage in blood cells. The whole-genome transcriptome analyses demonstrated dose-dependent increase in the number of differentially expressed genes with a significantly higher number of deregulated genes in female fish compared to male. Differentially expressed genes included genes involved in response to DNA damage, cell cycle control and regulation of circadian rhythm. Based on the low genotoxic activity and the pattern of the changes in DNA damage responsive genes we consider that at current environmental exposure levels, IM represents low risk for genotoxic effects in aquatic organisms. Exposure to IM also induced deregulation of the expression of genes associated with steroidogenesis and hormone metabolism and function, which indicates hormone-disrupting activity of IM that has not been studied so far. The study provide new information on the potential consequences of chronic exposure to the residues of tyrosine kinase inhibitors, which remain to be further explored.

Variational principles play a fundamental role in deriving the evolution equations of physics. They work well in the case of non-dissipative evolution, but for dissipative systems, the variational principles are not unique and not constructive. With the methods of modern nonequilibrium thermodynamics, one can derive evolution equations for dissipative phenomena and, surprisingly, in several cases, one can also reproduce the Euler–Lagrange form and symplectic structure of the evolution equations for non-dissipative processes. In this work, we examine some demonstrative examples and compare thermodynamic and variational techniques. Then, we argue that, instead of searching for variational principles for dissipative systems, there is another viable programme: the second law alone can be an effective tool to construct evolution equations for both dissipative and non-dissipative processes. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.

The second law of thermodynamics is a useful and universal tool to derive the generalizations of the Fourier’s law. In many cases, only linear relations are considered between the thermodynamic fluxes and forces, i.e., the conduction coefficients are independent of the temperature. In the present paper, we investigate a particular nonlinearity in which the thermal conductivity depends on the temperature linearly. Also, that assumption is extended to the relaxation time, which appears in the hyperbolic generalization of Fourier’s law, namely the Maxwell-Cattaneo-Vernotte (MCV) equation. Although such nonlinearity in the Fourier heat equation is well-known in the literature, its extension onto the MCV equation is rarely applied. Since these nonlinearities have significance from an experimental point of view, an efficient way is needed to solve the system of partial differential equations. In the following, we present a numerical method that is first developed for linear generalized heat equations. The related stability conditions are also discussed.

On the example of the Poynting&ndash, Thomson&ndash, Zener rheological model for solids, which exhibits both dissipation and wave propagation, with nonlinear dispersion relation, we introduce and investigate a finite difference numerical scheme. Our goal is to demonstrate its properties and to ease the computations in later applications for continuum thermodynamical problems. The key element is the positioning of the discretized quantities with shifts by half space and time steps with respect to each other. The arrangement is chosen according to the spacetime properties of the quantities and of the equations governing them. Numerical stability, dissipative error, and dispersive error are analyzed in detail. With the best settings found, the scheme is capable of making precise and fast predictions. Finally, the proposed scheme is compared to a commercial finite element software, COMSOL, which demonstrates essential differences even on the simplest&mdash, elastic&mdash, level of modeling.

There has been much interest in semiconductor superlattices because of showing very low thermal conductivities. This makes them especially suitable for applications in a variety of devices for thermoelectric generation of energy, heat control at the nanometric length scale, etc. Recent experiments have confirmed that the effective thermal conductivity of superlattices at room temperature have a minimum for very short periods (in the order of nanometers) as some kinetic calculations had anticipated previously. This work will show advances on a thermodynamic theory of heat transport in nanometric 1D multilayer systems by considering the separation of ballistic and diffusive heat fluxes, which are both described by Guyer-Krumhansl constitutive equations. The dispersion relations, as derived from the ballistic and diffusive heat transport equations, are used to derive an effective heat conductivity of the superlattice and to explain the minimum of the effective thermal conductivity., 14 pages, 3 figures

© 2020 by the authors. Thermodynamics is continuously spreading in the engineering practice, which is especially true for non-equilibrium models in continuum problems. Although there are concepts and approaches beyond the classical knowledge, which are known for decades, their mathematical properties, and consequences of the generalizations are less-known and are still of high interest in current researches. Therefore, we found it essential to collect the most important and still open mathematical questions that are related to different continuum thermodynamic approaches. First, we start with the example of Classical Irreversible Thermodynamics (CIT) in order to provide the basis for the more general and complex frameworks, such as the Non-Equilibrium Thermodynamics with Internal Variables (NET-IV) and Rational Extended Thermodynamics (RET). Here, we aim to present that each approach has its specific problems, such as how the initial and boundary conditions can be formulated, how the coefficients in the partial differential equations are connected to each other, and how it affects the appearance of nonlinearities. We present these properties and comparing the approach of NET-IV and RET to each other from these points of view. In the present work, we restrict ourselves on non-relativistic models.

The role of thermodynamics in deriving constitutive equations is unique, and various approaches have been developed in the last decades. In the present paper, the frameworks of Extended Irreversible Thermodynamics (EIT) and Non-Equilibrium Thermodynamics with Internal Variables (NET-IV) are discussed and compared to each other on the basis of a particular problem of rarefied gases. In this comparison, both theoretical and experimental aspects are taken into account. Eventually, an experiment by Meyer and Sessler covering a wide range of pressures and frequencies is investigated. Here, concentrating on the scaling properties and the density dependence of parameters, the change of speed of sound in terms of frequency and pressure is recovered using NET-IV, and this fitting is compared to the results of Lebon and Cloot using EIT. NET-IV and EIT are seen to be more flexible than Rational Extended Thermodynamics (RET) concerning the functional form of the transport coefficients, which gives them some advantages over RET in some ranges of values of gas density.

CubeSats have revolutionized the space industry in the past two decades. Its successor, the PocketQube class seems to be a lower size limit for a satellite which can operate continuously and can be received by radio amateur equipment. The present paper discusses the simulation of the thermal environment of the SMOG-1 PocketQube satellite at low Earth orbit by both thermal network and finite element models. The major findings of the analyses are the following. Even a single node per printed circuit board model can provide adequate information about the thermal behavior without tuning the physical parameters. By applying a finite element model with few magnitudes more nodes, the predicted inner temperature increased as the losses were reduced in the radiation-dominant environment compared to the thermal network model. Therefore, this latter method provides a more conservative temperature estimation. The most sensitive component of small-sized satellites is the battery which remains in the desired positive temperature regime even in this satellite class according to the finite element model. However, the thermal network model predicted a restricted battery charging protocol to ∼ 50% of the lit duration. Nevertheless, this condition still results in a positive energy balance by a factor of 1.5.

Dual phase lag equation for heat conduction is analyzed from the point of view of non-equilibrium thermodynamics. Its first order Taylor series expansion is consistent with the second law as long as the two relaxation times are not negative.

The role of the first chapter is the presentation of the toolbox of problem solving in detail. It can be used from your very first individual thermal project to your DSc degree in research or a group leader position in the industry. Hence, the focus here is on the way of thinking over direct problems. Before jumping into numerical modeling, several questions have to be answered. Even though each one seems obvious, nevertheless, neglecting them may significantly bias the calculation results. The second part of the chapter focuses on measurement data used for validation. It summarizes the fundamentals of sensor calibration and data uncertainty, also discussing the calculation of correlated quantities. However, these procedures often performed by technicians and engineers, it is crucial to know that the data measured by those sensors represent the quantity of interest with known uncertainty.

Solving a thermal problem means a solution of a mathematical model that governs the process and describes its time evolution. The thermodynamic background of these mathematical models is discussed in the present chapter. There are two building blocks of such a model. The first block consists the well-known balance equations such as the mass, momentum, and energy. The second one is the so-called constitutive relation, which tells us ‘how a material behaves’. This chapter is about their thermodynamic background.

In the engineering practice, most of the problems are solved using a commercial software such as finite element codes. In parallel, these software behave like a ‘black box’, offering only minimal insight into what equations are solved at the background. This is crucial in some problems, mainly when a non-classical (extended) material model must be applied. Using commercial software makes the treatment more rigid and limited, which is sometimes not the most efficient tool. Thus it could be necessary to write your code to obtain the solution. This chapter introduces the reader into the fundamental aspects of numerical (and analytical) methods and presents the properties of some particular numerical schemes, for instance, stability, dissipation, and dispersion.

The dominant heat transfer mode in vacuum is thermal radiation which is emphasized in the present chapter. Besides its relevance in space exploration, several industrial processes and commercial products use vacuum directly or its production require a technological process under vacuum. Firstly, the fundamentals of thermal radiation are briefly discussed to highlight the governing parameters of the process. Then the available thermal control methods are introduced with supporting examples. Finally, the thermal design and analysis of the SMOG-1 PocketQube class satellite is detailed, performed by the authors of this book.

We are living in the age of the energy crisis. To survive ourselves, it is crucial to find highly efficient technologies and change from the current fossil fuel-heavy energy mix to renewable-based energy generation. The present chapter highlights three main fields: solar and wind energy utilization and combustion. Then the last section briefly discusses the building blocks of thermal power cycles. These selected topics provide a versatile knowledge to the reader to identify the waste heat sources and find a proper solution that harvests it. Each of the first three sections features a deeply discussed, solved thermal problem, and the last section includes the key equations to allow the reader to perform initial calculations on the key components of a thermal cycle.

This chapter focuses on the experimental background of extended constitutive equations, especially on non-Fourier heat conduction. Although these phenomena are not common in engineering practice nowadays, it conveys essential aspects and provides guidance for ‘special’ thermal and coupled problems. It is anticipated that the advanced material models will appear in the commercial codes as the thermal modeling of micro and nano-scaled objects become increasingly important.

The possibility of successful smoking cessation is increased by early initiation. Therefore, promoting smoking cessation at early age (especially among 14-35-year-olds) has a key role in reducing tobacco use prevalence. Facebook is one of the most popular websites among adolescents and young adults which can be used for age-specific smoking cessation support.Our research seeks to reveal the effects of a Facebook page on smoking habits, smoking cessation knowledge and attitudes among 14-35-year-olds.An online survey was conducted among the 3278 followers of the author's Facebook page. The questionnaire was completed by 332 people among 14-35-year-olds. We analysed demographic data, smoking habits, the usage frequency and duration of the Facebook page as well as changes in smoking habits, smoking cessation knowledge and attitudes.The average age was 22.57 ± 5.08 years. The examined population consisted of 65% currently smokers, 12% former smokers and 23% non-smokers. Significantly more people reported a positive change in their smoking habits and smoking cessation attitudes among smokers who used the Facebook page more frequently and with longer duration (p0.05). The habit and attitude changes were significantly higher among smokers who plan to quit smoking (p0.01). Nevertheless, we also observed attitude changes between 12-25% among smokers who did not plan to quit. Among non-smokers, the positive attitude changes were significantly higher in the low-educated population who live in villages (p0.01).This Facebook page had a positive effect on smoking habits, smoking cessation knowledge and attitudes among 14-35-year-olds. The contents of the Facebook page could be used to prevent smoking and support smoking cessation among 14-35-year-olds. Orv Hetil. 2019; 160(6): 220-227.Absztrakt: Bevezetés: Minél kevesebb ideje dohányzik valaki, annál nagyobb az esélye a sikeres leszokásra. Ezért a 14–35 év közötti dohányzók leszokásának támogatása kulcsfontosságú a dohányzás hazai prevalenciájának csökkentésében. Ebben a korosztályban az egyik legnépszerűbb internetes felület a Facebook, mely alkalmas lehet korcsoport-specifikus leszokási támogatásra. Célkitűzés: Kutatásunk arra törekszik, hogy feltárja egy leszokást segítő Facebook-oldal követésének hatásait a 14–35 éves korosztály dohányzási szokásaira és attitűdjére. Módszer: A szerzők által több mint egy éve működtett Facebook-oldal 3278 követője körében online felmérést végeztünk. A 14–35 éves korosztályból összesen 332 fő töltötte ki a kérdőívet (n = 332). A demográfiai adatok mellett felmértük a válaszadók dohányzási szokásait, a Facebook-oldal használatának gyakoriságát és időtartamát, illetve a leszokással kapcsolatos ismeretek, dohányzási szokások és attitűdök változását. Eredmények: A vizsgált populáció átlagéletkora 22,57 ± 5,08 év volt, melyből 65% jelenleg dohányzó, 12% leszokott dohányzó és 23% nem dohányzó. Azok a jelenleg dohányzók, akik gyakrabban és hosszabb ideje használták a Facebook-oldalt, szignifikánsan többen számoltak be dohányzási szokásaik és leszokási attitűdjeik pozitív változásáról (p0,05). Bár a leszokást tervezők között a szokások és attitűdök pozitív változása szignifikánsan nagyobb arányban fordult elő (p0,01), azoknál is 12–25% közötti attitűdváltozást észleltünk, akik nem tervezték a leszokást. A nem dohányzók pozitív attitűdváltozása szignifikánsan magasabb volt a faluban élő, alacsony iskolázottságú lakosság körében (p0,01). Következtetés: A vizsgált Facebook-oldal pozitív irányban befolyásolta a 14–35 éves korosztály leszokási ismereteit, dohányzási szokásait és attitűdjeit. A Facebook-oldal tartalmai szabadon felhasználhatók a 14–35 éves páciensek leszokásának támogatásában, valamint a Facebook-oldal követése javasolható dohányzó és nem dohányzó fiataloknak egyaránt. Orv Hetil. 2019; 160(6): 220–227.