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The most challenging problems in the field of chemico- and bioanalytical measurements are described. These problems are being solved, in particular, by participating in new international comparisons organized by the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology of the International Committee of Weights and Measures (CCQM CIPM). Solutions of these challenging problems are presented. The objectives and tasks of developing key comparisons in the following areas are described: isotopic measurements; determination of the purity of substances; organic analysis; bioanalytical measurements; measurements of aerosol particle parameters; measurements in the field of gas analysis and electrochemistry. It is shown that participation in international key comparisons allows obtaining valid and reliable results of measurements of the composition and properties of gas and liquid media, as well as solid substances and materials.

The issues of the functioning of the BIPM and the corresponding committee - CCQM, coordinating the work on the comparisons of national standards in the field of organic analysis have considered in this article. The structure and tasks of the CCQM have described and the measurement categories for the amount of substance have given. The main aspects of the OAWG activities have discussed and the issues of systematization and separation of comparisons in the field of organic analysis have discussed in detail and various approaches to the development of competence areas based on key comparisons have set out. The fundamental importance of pure organic substances in providing metrological traceability in organic analysis has highlighted. The key role of the State Primary Standard GET 208 in terms of confirming the equivalence of the calibration and measurement ccapabilities (CMC) of Russia at the international level has been determined.

The kilogram is the unit of mass and was defined in 1889 by the international prototype of the kilogram. The mole is the unit of amount of substance and was defined in 1960 by the number of atoms in 0.012 kg of 12C. These definitions were revised in May 2019. The new definitions of the kilogram and the mole are based on the Planck constant h and the Avogadro constant NA, respectively. The values of h and NA used in the new definitions were determined by summarizing measurement results of the two physical constants by several national metrology institutes around the world. In this review, the history of the two units and measurement technologies used to derive the new definitions are described. The effect of the revision on the development of new measurement technologies is also introduced.

In this study, we aimed to calculate dependencies for assessing the value of weight loss during lyophilization of diagnostic preparations depending on the drying temperature and time. A model solution for lyophilization was Hottinger broth with gelatin (1.5%) and peptone (10%) used as stabilizers. To achieve the aim, a full factorial experiment 23 was planned and implemented, the investigated factors in which were the temperature and time of final drying, as well as the amount of substance in the primary packaging. Using ampoules as containers for primary packaging, a regression equation was obtained. The conducted statistical processing of the obtained equation showed the feasibility of the developed mathematical model. According to the model, an increase in the drying temperature and time leads to a decrease in the amount of weight loss; however, weight loss increases under an increase in the amount of substance in the secondary packaging. As a result of the experiments, a correspondence between the experimental and calculated values of weight loss during drying was revealed. The effect of the height of the material under drying on the weight loss was studied when drying an equivalent amount of substance in vials. The developed mathematical model for drying in ampoules was modified to describe the process of lyophilization in vials. The experimental results confirmed the possibility of calculating weight loss during drying using the proposed model. The developed dependencies can be used for estimating the value of weight loss during lyophilization of various substances, which is of particular importance in terms of reducing costs when establishing the temperature and time parameters of drying new biological products and modifying production regimes when changing the amount of product, type of primary packaging or desorption conditions.

In this paper I take a close look at the SI base quantity “amount of substance”, and its unit, the mole. The mole was introduced as a base unit in the SI in 1971, and there is currently a proposal to change its definition. The current definition of the mole shows a certain ambiguity regarding the nature of the quantity “amount of substance”. The proposed new definition removes the ambiguity, but at a cost: it becomes difficult to justify treating amount of substance as having its own dimension, and hence its own unit, the mole. I argue that the difficulties with amount of substance result from its role as a mediator between macroscopic and microscopic scales. To understand why amount of substance might have its own dimension, we need to connect amount of substance to mass, contra current proposals to separate them.

This discussion article explores how metrology bodies should approach method-defined measurands (also called operationally defined measurands). It begins by considering the different types of measurement that can be encountered and comparing their difference qualities, before discussing in more detail method-defined measurands and the nature of their current and future treatment by the global metrology system. The discussion highlights work performed within the Consultative Committee for Amount of Substance to address what should be within the scope of the International Committee for Weights and Measures Mutual Recognition Arrangement (CIPM-MRA) when method-defined measurands are considered and also how the metrology community can contribute to ensuring stability and comparability of these measurements outside the formal scope of the CIPM-MRA.

This article is written in memory of Professor Helge Strömdahl (1945-2018), the former director of the Swedish National Graduate School in Science and Technology Education (FontD). Helge took his Ph.D. at Gothenburg University in 1996 with the dissertation “On mole and amount of substance. A study of the dynamics of concept formation and concept attainment”. He was director of the Swedish National Graduate School in Science and Technology Education (FontD) from 2001 until his retirement in 2010, and became professor in science education at Linköping University. As director of the national graduate school, Helge encouraged and cultivated a methodologically and theoretically broad view on research in science education.

Metrological traceability for organic chemical measurements is a documented unbroken chain of calibrations with stated uncertainties that ideally link the measurement result for a sample to a primary calibrator in appropriate SI units (e.g., mass fraction). A comprehensive chemical purity determination of the organic calibrator is required to ensure a true assessment of this result. We explore the evolution of chemical purity capabilities across metrology institute members of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology’s Organic Analysis Working Group (OAWG). The OAWG work program has promoted the development of robust measurement capabilities, using indirect “mass balance” determinations via rigorous assessment of impurities and direct determination using quantitative nuclear magnetic resonance spectroscopy methods. A combination of mass balance and qNMR has been shown to provide a best practice approach. Awareness of the importance of the traceability of organic calibrators continues to grow across stakeholder groups, particularly in key areas such as clinical chemistry where activities related to the Joint Committee for Traceability in Laboratory Medicine have raised the profile of traceable calibrators.

This paper presents new criteria, taking into account the fact that “chemical” similarity should be based on the nature of change in the amount of substance and heat over time and space depending on the conditions of the process, including the temperature, pressure and composition of the reaction mixture.

Redefinition of the basic units of the International System of Units (SI) — the kilogram, mole, ampere, and kelvin, — which are now expressed in terms of fundamental physical constants means a substantial revision of the system. In particular, the new definition of the mole fixing the value of the Avogadro constant sets a unit of the amount of substance, which is independent of the unit of mass. We consider some consequences of redefining (the mole and kilogram) and focus on the uncertainty of measuring the amount of substance and related quantities which are important for description of the mixture composition. The issue regarding the molar mass of the substance and associated uncertainty is considered in detail It is noted that calculation of the molar mass using relative atomic masses, involves the molar mass constant which is not equal exactly to 1 g/'mol in the new SI. This introduces an additional, though very small, uncertainty of less than 1 x 10-9in relative terms. The budget of uncertainty for the amount of substance determined through the mass measurements when the mass is measured with the highest accuracy is scrutinized. It is demonstrated that for substances of less than 99.98% purity, the uncertainty associated to the purity is comparable to that of relative atomic masses of the elements. For high-purity substances, the uncertainty in the relative atomic masses have the largest contribution to the budget. Anyhow, the uncertainty associated to the molar mass constant is three orders of magnitude less than the nearest contribution to the uncertainty attributed to weighing. In the case of derived quantities which are the ratio of two quantities of the same kind, the additional uncertainty does not arise at all. This is illustrated by the calculation of the mole fraction of a component in the gravimetrically prepared gas mixture.

Professor N.E. Zhukovsky was a famous Russian mechanic and engineer. In 1876 he defended his master’s thesis at Moscow University. At a careful reading of N.E. Zhukovsky’s master’s thesis in 1997, V.A. Bubnov—a professor at the Moscow City Pedagogical University—discovered terms of the second order of smallness in the continuity equation for an incompressible fluid. Zhukovsky calculated them, but did not use the amount of substance in the balance. Ten years later, the author found high-order terms in Euler’s derivation of the 1752 continuity equation for an incompressible fluid. The physical meaning of the additional terms became clear after the derivation in 2006 of the continuity equation with terms of high order of smallness for a compressible gas. The higher order terms of the smallness of the continuity equation penetrate into the inhomogeneous part of the wave equation and lead to the generation of self-oscillations, vibrations, sound, and the initial stage of turbulent pulsations. The stochastic approach ensured success in modeling turbulent flows. The use of high-order terms of smallness of the Euler continuity equation makes it possible to transfer the description of some part of the motions from the stochastic part of the equation to the deterministic part. The article contains a review of works with the derivation of the inhomogeneous wave equation. These works use additional terms of a high order of smallness in the continuity equation.

Volatile Organic Compounds (VOCs) are widely measured at ppb and ppt level in many contexts, from therapeutic drug control in respiratory diseases to monitoring of climate change and indoor air quality. The need for accuracy is a common denominator in all these fields. The interactions between gas mixtures and solid surfaces in sampling lines and instruments play an important role in calculating the total uncertainty of the amount of VOC. The amount of substances in the gas mixture is affected by its reversible and irreversible interactions with the sampling line. The main aim of this paper is to propose and discuss a method to quantify the amount of substance segregated by reversible interactions on sampling lines. To validate the proposed method, the areic amount of a VOC (Acetone) is measured for a commercial test pipe (Sulfinert®) as the amount of substance per unit area of the internal surface of the test pipe segregated from the flowing gas mixture. Stainless steel coated by Sulfinert® was chosen as a test material because of its wide use and its limited irreversible and permeation effects. A certified gas mixture of Acetone in air with a nominal mole fraction of 10 µmol mol−1 was used for validation. Broad temperature control was used and the sensibility of the method to the temperature and the pressure has been evaluated to correct the bias due to physical condition. The sensitivity to the residence time and the Reynolds number of the gas flow has been evaluated to verify the reaching of equilibrium and the limits of the applicability of the method. The areic amount of Acetone at equilibrium on Sulfinert® coated pipe was measured as 40 nmol m−2, and an equilibrium constant value of around 0.2 m was calculated as the ratio between the superficial amount segregated on the wall and the amount concentration of Acetone in the mixture, both at the equilibrium. The observed reproducibility was better than 2.5%. This method is aimed to investigate VOC losses due to interactions for many VOC/material systems at a lower amount of substance levels.

The amount of substance expressed in the units of moles is an essential concept in physics and chemistry. Physics students usually acquired a chemistry background in applying the mole concept. However, research shows that the complexity of interpretations of quantities expressed as molar mass or atomic mass makes formulating a dimensional analysis with these ratios unclear to physics students. This study proposes proportional reasoning, instead of ratios, as the main building block to formulate conversion algorithms from microworlds to macroworlds and vice versa. A deductively designed lecture was conducted with a group of (N = 25) freshman college physics students. While on the pretest, only (N = 4, 16%) correctly converted a mass of a substance expressed in kilograms to a number of moles, on the posttest, the percentage of correct answers increased (N = 20, 80%), suggesting that proportional reasoning has the potential to help students understand the conversion processes and improve understanding of the mole as a unit of substance. This study, in its principal form, was published earlier (see Sokolowski, A., International Journal of Physics & Chemistry Education, 11, 85–92, 2019).

We discuss the motion of substance in a channel containing nodes of a network. Each node of the channel can exchange substance with: (i) neighboring nodes of the channel, (ii) network nodes which do not belong to the channel, and (iii) environment of the network. The new point in this study is that we assume possibility for exchange of substance among flows of substance between nodes of the channel and: (i) nodes that belong to the network but do not belong to the channel and (ii) environment of the network. This leads to an extension of the model of motion of substance and the extended model contains previous models as particular cases. We use a discrete-time model of motion of substance and consider a stationary regime of motion of substance in a channel containing a finite number of nodes. As results of the study, we obtain a class of probability distributions connected to the amount of substance in nodes of the channel. We prove that the obtained class of distributions contains all truncated discrete probability distributions of discrete random variable &omega, which can take values 0,1,⋯,N. Theory for the case of a channel containing infinite number of nodes is presented in Appendix A. The continuous version of the discussed discrete probability distributions is described in Appendix B. The discussed extended model and obtained results can be used for the study of phenomena that can be modeled by flows in networks: motion of resources, traffic flows, motion of migrants, etc.

Gravimetric preparation method is one of the most precise and accurate methods for preparing primary standard gas mixtures (PSMs). Although the principle and execution of the gravimetric method are not complicated, the uncertainty of the gravimetric method is so small that a seemingly minor error can result in an incorrect amount fraction of the PSM. Therefore, verifying the amount fraction of the PSMs is a necessary step. We perform a high-precision comparison between the PSMs of oxygen in nitrogen (∼100 µmol per mol) using a well-stabilized gas chromatograph with a thermal conductivity detector (GC-TCD) system in conjunction with high-precision pressure monitoring for sample amount correction and a quality-control cylinder technique in which the PSMs were analyzed against a reference cylinder, which leads to the cancellation of the drift in the sensitivity of the GC-TCD. After optimization of the measurement conditions, the relative expanded uncertainty reaches 0.022% (coverage factor k = 2), which is equivalent to the uncertainty of the PSMs. The Consultative Committee for Amount of Substance of the Comite International des Poids et Mesures performed a key comparison CCQM-K53, in which one of the PSMs used in this work was compared and agreed well with PSMs prepared by other National Metrology Institutes. These results show that the GC-TCD system developed in this work is sufficiently reliable, precise and accurate to verify PSMs.

New definitions of the units for amount of substance – the mole – and for mass – the kilogram – will presumably come into force on the World Metrology Day 2019. In the revised SI, the mole will be defined by a fixed value of the Avogadro constant and the kilogram by a fixed value of the Planck constant. The X-ray-crystal-density (XRCD) method has been used for the determination of these fundamental constants by counting the number of atoms in 28Si-enriched spheres. Thus, silicon spheres will – after the redefinition – be used to realize the definitions of the mole and the kilogram. This is possible by SI-traceable measurements of lattice parameter, isotopic composition, volume, and surface properties, yielding a relative standard uncertainty below 2⋅10−8. Whereas this high accuracy is only reached with isotopically enriched silicon, it is also planned to use natural silicon spheres on a slightly lower level of accuracy. The future definitions will allow also new realization methods using silicon, in particular for small mass values.

Fractal is a set owning an infinitely fine structure in a self-similar or self-affine way covering all scales, and is widely used to model the structure of porous media. Hydrate-bearing sediments belong to porous media, so this paper attempts to construct a structure model of hydrate-bearing sediments with the three-component fractal extended from the two-component fractal. The three-component fractal is capable to display structural details at arbitrarily small scale. Additionally, in the three-component fractal, any parameter defined as the ratio (such as porosity and hydrate saturation) of two different volumes approaches a determined value when considering the infinitesimal scale. The interface between hydrate elements and pore elements is suggested to be a potential way to classify the hydrate-bearing sediments. Using the proposed three-component fractal model to calculate the interface between one arbitrary hydrate particle and surrounding pores, we obtain the theoretical solutions of the amount of substance, the dissociation rate and maximal dissociation time of one arbitrary hydrate element in sediments. It is found that the effective reacting surface of one hydrate element in sediments could be equal to even greater than that of the pure hydrate element in the late period of hydrate dissociation, during which the amount of substance of one hydrate element in sediments is still greater though. Finally, we further extend the three-component fractal to any-component fractal, and show how to model more complex porous media by using a suitable generator.

This discussion article begins by highlighting the benefits of the mole's incorporation within the international system of units (SI), in particular by bringing chemical measurement within formal metrology structures. The origins of the confusion that has consistently existed between amount of substance (the base quantity of which the mole is the SI base unit) and counting quantities are examined in detail and their differentiating characteristics fully elaborated on. The importance and benefits of distinguishing between these different quantities and the role that the Avogadro constant plays in doing this are highlighted. It is proposed that these issues are becoming increasingly important for two reasons. First, as chemistry and biology consider increasingly small size domains, measurements are being made of significantly reduced collections of entities. Second, the proposed re-definition of the mole makes the link between amount of substance and the number of elementary entities more transparent. Finally, proposals for new ways of expressing very low amounts of substance in terms of new prefixes based on the numerical value of the Avogadro constant are presented as a way to encourage the use of the mole, when appropriate, even for ultra-low level chemical measurement.

The 2019 revision of the International System of Units (SI), including the redefinition of the mole, and the progress of analytical chemistry technologies allowing single-molecule resolution has brought into sharp focus the dilemma between expressing measurements of ultra-low quantities of elementary entities in terms of amount of substance or in terms of counting quantities. We should prefer the use of amount of substance for these measurements for a number of reasons including to allow intensive and extensive quantities in chemistry to be distinguished and to separate these measurements from those involving the counting of non-elementary entities. The discussion article highlights how a new, non-decimal approach to unit prefixes might in future enable amount of substance to be used usefully down to its natural limit—a single elementary entity. A new prefix symbol ‘σ’ is proposed to represent the multiplier 1/{NA}.

We have developed a method to calculate the fractional distribution of CO2 across all of its component isotopologues based on measured δ13C and δ18O values. The fractional distribution can be used with known total CO2 to calculate the amount of substance fraction (mole fraction) of each component isotopologue in air individually. The technique is applicable to any molecule where isotopologue-specific values are desired. We used it with a new CO2 calibration system to account for isotopic differences among the primary CO2 standards that define the WMO X2007 CO2-in-air calibration scale and between the primary standards and standards in subsequent levels of the calibration hierarchy. The new calibration system uses multiple laser spectroscopic techniques to measure mole fractions of the three major CO2 isotopologues (16O12C16O, 16O13C16O, and 16O12C18O) individually. The three measured values are then combined into total CO2 (accounting for the rare unmeasured isotopologues), δ13C, and δ18O values. The new calibration system significantly improves our ability to transfer the WMO CO2 calibration scale with low uncertainty through our role as the World Meteorological Organization Global Atmosphere Watch Central Calibration Laboratory for CO2. Our current estimates for reproducibility of the new calibration system are ±0.01 µmol mol−1 CO2, ±0.2 ‰ δ13C, and ±0.2 ‰ δ18O, all at 68 % confidence interval (CI).

Оригинал опубликован в журнале Metrologia (2013. V. 50. № 5. P. 158-163) под названием "The mole, amount of substance and primary methods". Материал получен 25 февраля 2013 г., в окончательной форме - 8 марта 2013 г., опубликован 2 апреля 2013 г. Оригинальный текст доступен на сайте IOP Science. URL:stacks.Iop.org/Met/50/158. В данном докладе представлены принципы, разработанные для применения метрологии в сфере химии и, в частности, аналитической химии. Доклад начинается с обсуждения моля, основной единицы Международной системы единиц (СИ), которая более всего относится к аналитической химии. Моль стал предметом отдельной дискуссии совсем недавно, с момента публикации предложений дать ему новое определение вместе с тремя другими основными единицами СИ. Эта дискуссия также породила интерес к происхождению термина «количество вещества», которое используется как количество, а моль - как единица. В данном докладе рассматривается происхождение термина и объясняется, почему недостаточно было бы заменить его альтернативными вариантами, такими как «число единиц». В заключение идет дискуссия о том, как используется моль в первичных методах измерений.

Wilhelm Ostwald was a notable holdout against the acceptance of the reality of atoms. He steadfastly maintained a positivist perspective, that the empirical facts of chemistry implied no underlying meaning about the nature of matter. The amount of substance definition of the mole aligned with this view. He was moved to accept the reality of atoms based on the results of experimental work on Brownian motion by Jean Perrin, that gave a name to, and a value for, Avogadro’s constant. Ostwald could have modified the definition of the mole, making use of the constant to incorporate the atomic nature of matter into the concept. If he had, difficulties with the definition that persist today might have been avoided.

Orientadora: Profª. Drª. Solange Wagner Locatelli Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ensino, História e Filosofia das Ciências e Matemática, Santo André, 2020. O mol, a unidade de medida da quantidade de substância, representa um conceito de extrema importância para química, bem como para o Ensino de Química, uma vez que essa unidade estabelece a relação entre o mundo macroscópico e o submicro. Entretanto, o que se observa na literatura, é que os alunos demonstram muitas dificuldades de compreensão frente a este conceito, se fazendo necessário o uso de novas abordagens e estratégias em seu ensino. Diversos estudos apontam estratégias metacognitivas como úteis na melhoria do aprendizado, visto que o ato de pensar sobre o próprio pensamento é frequentemente observado em alunos com bom desempenho, sendo que o uso dessas estratégias busca induzir o aluno conscientemente e intencionalmente a praticar a metacognição. Uma das estratégias possíveis é o autoquestionamento, que consiste em induzir a regulação do pensamento por meio do uso frequente de questões. Assim, este trabalho visa investigar e compreender como ocorre a aprendizagem autorregulada pelos alunos ao construírem/reconstruírem seus conceitos, com relação à grandeza quantidade de substância (mol), utilizando a estratégia metacognitiva do autoquestionamento. Para isso, a estratégia metacognitiva do autoquestionamento foi aplicada durante uma sequência didática investigativa (SEI), com o tema quantidade de substância, tendo como público alvo alunos participantes de um curso preparatório para o ENEM da Universidade Federal do ABC, que em posse de uma lista regulatória de questões, participaram das três etapas da SEI. A coleta de dados foi realizada a partir de gravações audiovisuais, que foram complementadas pelo uso da técnica do "think aloud", estratégia aplicada a fim de enriquecer a coleta. A ação foi elaborada de forma a criar uma atmosfera de liberdade aos participantes, que frente a duas amostras de cobre e alumínio deviam propor um modo de responder em qual das duas existia maior número de átomos. A partir dos dados obtidos foram criadas diferentes categorizações quanto às impressões sobre a atividade, quanto aos conceitos matemáticos e químicos envolvidos e ao processo de realização da tarefa. Além disso, também foram analisadas a presença de incidentes metacognitivos, o modo como a dupla acessa e transita entre os níveis representacionais, além da validade científica dos conceitos utilizados. Com isso sugere-se o uso do autoquestionamento como capaz de auxiliar os alunos no processo de resolução de problemas, pois facilita a criação de estratégias, que em conjunto com o caráter investigativo da sequência didática aumentaram a motivação dos alunos durante a realização da tarefa. Percebeu-se que as maiores dificuldades quanto ao conceito de quantidade de substância se encontram na diferenciação dos termos semelhantes relacionados ao tema e que o nível representacional que oferece mais dificuldades é o submicroscópico. A atividade promoveu a ocorrência majoritária de incidentes metacognitivos de monitoramento, confirmação e mudança desejada, além de evidências da ocorrência de modelagem conceitual. Por fim, aponta-se que a SEI em conjunto com a estratégia do autoquestionamento ofereceram indícios de serem capazes de promover a aprendizagem autorregulada nos sujeitos analisados. The mole, the unit of measure of the quantity of matter, is a concept of extreme importance for chemistry, as well as for the teaching of chemistry, since this unit establishes the relation between the macroscopic world and the submicro. However, what is observed in the literature is that the students demonstrate many difficulties of understanding against this concept, making necessary the use of new approaches and strategies in their teaching. Several studies point to metacognitive strategies as useful in improving learning, since the act of thinking about one's own thinking is often observed in students with good performance, the use of these strategies seeks to induce the student to consciously and intentionally practice metacognition. One of the possible strategies is self-questioning, which is to induce the regulation of thinking through the frequent use of questions. Thus, this work aims to investigate and understand how occurs students self-regulated learning when constructing / reconstructing their concepts, in relation to the quantity of substance (mole), using the self-questioning metacognitive strategy. To that end, the metacognitive strategy of self-questioning was applied during a sequence of investigative teaching (SIT) with the subject matter quantity, having as a target audience, students participating in a preparatory course for the ENEM of the Federal University of ABC, which has a list regulating issues, participated in the three stages of the SIT. The data collection was done from audiovisual recordings, which were complemented by the use of the "think aloud" technique, a strategy applied in order to enrich the collection. The action was designed in order to create an atmosphere of freedom for the participants, who in front of two samples of copper and aluminum had to propose a way to answer in which of the two samples there were more atoms. From the data obtained, different categorizations were created regarding the impressions about the activity, the mathematical and chemical concepts involved and the process of carrying out the task, the presence of metacognitive incidents was also analyzed, how the pair of students accesses and transits between the representational levels and the scientific validity of the concepts used. In addition, the presence of metacognitive incidents, the way the pair accesses and transits between representational levels, in addition to the scientific validity of the concepts used were also analyzed. Thus, it is suggested the use of self-questioning as able to assist students in the problem-solving process, as it facilitates the creation of strategies, which together with the investigative character of the didactic sequence increased the students' motivation during the task. It was noticed that the greatest difficulties regarding the concept of quantity of substance are found in the differentiation of similar terms related to the theme and that the representational level that offers the most difficulties is the submicroscopic one. The activity promoted the majority of metacognitive incidents of monitoring, confirmation and desired change, in addition to evidence of the occurrence of conceptual modeling. Finally, it is pointed out that SEI together with the self-questioning strategy offered evidence of being able to promote self-regulated learning in the analyzed subjects.