Radiation technology has a unique position in the medical field. With the development of radiation technology, it will have a broader application prospect in the future. This paper reviews the research and development history of radiation technology in the medical field, the current state in medical applications, and the latest frontier research in both diagnosis and treatment. In this way we hope to make people learn the applications of radiation technology and promote the use of radiation technology for mankind.

According to outcome-based education (OBE) idea, the teaching design of two-phase equilibrium in a one-component system is taken as an example to solve practical problems as the guide to arrange the learning tasks in and out of class. Teaching models for physical chemistry courses are explored by group cooperative learning.

To adapt to the modern social economy, innovative, applied, and skilled talents training must be strengthened and applied during the entire learning process. Guided by a comprehensive view of chemical education, it is an effective strategy to carry out the fusion experimental reform for the validation experiment in chemical experiment courses. For example, the reform in electric potential determination, a physical chemistry experiment, is to expand the verification experiment into a simulation-embedded fusion experiment, which is composed of simulation, basic, exploration, and integrated experiments. Virtual simulation technologies, teachers' self-made devices, and scientific research achievements have been applied to give full play to synergistic effects of scientific research and teaching. "Output oriented" educational characteristics of student-centered, independent exploration, moral education, scientific methods, and thinking training played an evident role in improving the quality of talent training.

Using an experimental pharmaceutical analysis course as an example, we established a problem-oriented multidimensional teaching design that explored the three-body integrated teaching mode in an experimental course. On the basis of the teaching syllabus, various experimental directions, including the practical life, width, and depth of the experimental direction, were used in classroom practice as carriers for analyzing and solving problems. Practice results show that the multidimensional teaching design, which relies on problem-guided learning, increases the interest and systematicness of the experiment, compared to traditional teaching, and plays a positive role in stimulating and motivating student learning, cultivating the practical abilities and innovativeness of students, and shaping their values.

According to the subject characteristics of structural chemistry and the learning situation of undergraduates in Qufu Normal University, this paper explores the teaching reform to eliminate students' fear of difficulties and cultivate their interest in the subject. It is considered that designing a reasonable and interesting introduction course is an effective measure. The high-quality teaching effect and scientific thinking mode can be achieved by using the analogy method, reducing complexity to simplicity, and clarifying the scope, degree, logic and meaning of structural chemistry learning.

A series of teaching exploration is carried out in organic chemistry laboratory to improve scientific literacy of undergraduate students. This article details our efforts in designing teaching activities on research-type experiment to introduce students to the scientific process and impart basic research ability through program design, implementation and summarization.

Spectroscopy analysis is an interdisciplinary course that includes abstract concepts/theory as well as concrete spectra identification training. We discuss course reform, including teaching contents and teaching methods, emphasizing the specification and figuration of abstract theories and enhancing classroom interactions. This reform will be attractive to the students and enhance student learning outcomes. Practicing spectra collection and identification can improve students' learning interest and internal motivations for studying spectroscopy analysis.

Online blended teaching mode is an emerging education method, the effect of which is explored on the multi-class teaching course of "Organic Analysis". The teaching effects were evaluated by the process assessment results supplemented by classroom participation and the final. The different teaching method data of experimental and control group were all collected in the same way. Research shows that the effect of online blended teaching is slightly better than that of the offline blended teaching effect. Through questionnaires, it was found that online teaching can enable students to obtain higher classroom participation and better classroom experience. Therefore, the emerging education methods is suitable for remote teaching. The application of new education methods may make a difference for the western agriculture college education.

After analyzing the difficulties faced by the current chemical practice teaching, the "Internet + Education" is used to introduce virtual simulation technology into the chemical practice teaching to create a teaching mode of "Four Levels & Seven Modules". This model is integrated with the comprehensive design of practice, and forms a progressive teaching method of basic theory, cognition practice, simulated operation, practical training operation and process design, and it can effectively solve the difficulties faced by chemical production practice and cultivate innovative chemical professional as well as technical talents in line with the needs of the new era. At the same time, through this teaching mode, it will be possible to achieve online supervision, Q & A, and assessment of students throughout the whole process, and to bring practical teaching into the era of cloud teaching.

It is an effective measure to realize moral education by organically integrating ideological and political elements with the teaching content. In this paper, starting from the theory and laboratory teaching of polymer chemistry, the ideological and political objectives were constructed, and ideological and political links are designed based on the strategies of student-centeredness and outcome-based education. Besides, the typical teaching ideological and political cases were also analyzed, and the ideological and political education effect of the course was evaluated via a questionnaire and output effect. It was certificated that the introduction and combination of ideological and political elements not only deepened students' understanding of professional knowledge, but also improved students' ideological and political accomplishments.

The problems existing in the instrumental analysis course may influence the top innovative talent cultivation, ideas for reforming the curricula content. The teaching mode, examination, and evaluation standards are proposed to solve the problems. By updating the theoretical content of modern instrumental analytical chemistry, such as the discovery and progress of classical principles, students can master the basics to excel professionally, and learn how to discovery and create new methods and principles. Simultaneously, advanced techniques, such as 3D animation and virtual simulation software, are used to present more vividly the quantities and concepts for students to understand the principles easily. This investigation can successfully stimulate students to learn and understand chemical principles more comprehensively, cultivate their problem identification and resolution abilities, and promote their creative quality, thus benefiting the cultivation of top innovative talents in chemistry.

Chemical analysis plays an important role in the testing and inspection of construction materials, thus it is necessary for students of inorganic nonmetallic materials engineering to understand analytical chemistry well. In this article, a case-based analytical chemistry teaching mode for inorganic nonmetallic materials engineering majors is introduced, wherein application cases of chemical analysis in construction materials testing are integrated into the course, and an effective connection is made between the basic courses and the majors. Through a variety of teaching designs, such as comparative and associative methods, students are encouraged to participate actively in the course to deepen their understanding of theoretical knowledge, enhance their understanding of the practicality and necessity of analytical chemistry in the major, and learn according to the material and needs.

With the development of educational technology, the traditional classroom is gradually replaced by blended learning. As the baton of students' learning, multi-dimensional assessment ensures the implementation of all links of blended teaching. In view of the assessment process and the reasonability, the multi-dimensional assessment is explored and reported herein, which is composed of "online unit test + pre-class test + offline homework self-evaluation and mutual evaluation + offline classroom report (or group discussion) + offline final examination (combination of open and closed books)" in the course of inorganic chemistry and chemical analysis at Tianjin University. Multi-dimensional assessment itself has also become an important part of blended learning.

The training of scientific research ability and innovation consciousness of college students is one of the key goals in undergraduate teaching. The chemical experiment teaching is the most effective way to realize comprehensive chemistry education, further, it is crucial to cultivate the scientific thinking and innovation ability of students. The course combines scientific research with experimental teaching of school, so that it enhances level and depth of experiment teaching. This paper mainly introduces the construction of scientific research foundation and innovative experiment from the aspects of course orientation and objectives, construction of course team, construction of the course content and resources, and course implementation and evaluation. After years of exploration and practice, the extra-curricular scientific research experiment course has made great achievements in talent cultivation, teaching reform, and scientific research. And it has effectively promoted the experimental curriculum reform. Meanwhile, this paper further improvement and measures in view of the deficiencies of the course, and also makes prospects for the future study.

In this paper, the construction and the implementation of the curriculum system, changing from teaching-oriented to learning-oriented, are discussed for cultivating innovative talents, focusing on problems encountered by freshmen in inorganic & analytical chemical chemistry laboratory. By optimizing the curriculum system, improving the teaching content, expanding the training mode and strengthening the platform construction, students are guided to actively explore and independently think, gradually master the methods of innovative scientific research.

Cyclic peroxide represents a class of organic peroxides with peroxy bonds in their ring structures. To date, cyclic peroxides with unique properties and diverse structures have played irreplaceable roles in many fields. Taking the application of cyclic peroxides in the fields of medical health, chemiluminescence, and chemical synthesis as examples, this essay presents an introduction of the physical and chemical properties and reaction mechanism of cyclic peroxides, with the aim of facilitating an understanding of this class of organic peroxides in readers.

β-dicarbonyl compounds are important intermediates in organic synthesis, and their chemical properties play a major role in organic chemistry teaching. On this basis, this paper focuses on the synthesis and application of α-diketones involving hydration of alkynes, oxidation of alkynes and photocatalytic reaction, etc. The content of this paper is both closely related to and also an expansion of fundamental organic chemistry. Furthermore, the application of α-dicarbonyl compounds can broaden students' horizons and boost their interest in learning.

Reaction of bromine and the C＝C double bond is one of common elementary reactions in organic chemistry. Bromine and alkenes undergo an electrophilic addition. Aliphatic alkenes undergo formation of three-membered cyclic bromonium intermediates and subsequent ring-opening mechanism, affording stereospecific trans-dibromoadducts, while the three-membered cyclic bromonium intermediates of arylolefins favor to dissociate their benzylic C―Br bond due to aryl stabilizing the generated carbocations, producing a mixture of cis- and trans-dibromoadducts. However, bromine and enols or enolates generated from ketones or carboxylic halides undergo electrophilic substitutions. Bromine does not generate the corresponding three-membered cyclic bromonium intermediates with their C＝C bond in the reactions. Similarly, the reactions of viny ethers and enamines with bromine do not undergo the three-membered cyclic bromonium intermediates, either, generating nonstereospecific adducts and substituted products, respectively. This article rationally explains the mechanistic and stereoselective differentiations between the reactions of bromine and these two classes of reactants with reactive molecular orbitals in the elementary reaction, and summarizes the identification method on the reaction mechanism and stereoselectivity of the reactions between bromine and different C＝C bonds, hoping to be convenient for teaching and understanding.

From the Earth to the Moon to Mars, human beings have never stopped exploring for treasures. From Iceland spar to quartz to amethysts, the optical phenomena presented by these sparkling and clear ores have inspired scientists to make persistent efforts to reveal "what is light" and "the origin of chirality" throughout the history of science. This has contributed to the advancement of science, technology, and modern society, and will continue to have an immeasurable impact on the future of science and technology.

The methods of making money or casting money in different era reflect the development level of the society at that time and the degree of people's mastery of chemical technology. Every evolution of currency marks the progress of society and chemistry has played an important role. The study takes the close relationship between the coinage of metal currency, the anti-counterfeiting of paper currency, the security of digital currency and chemistry as the clues to further integrate chemistry knowledge into social development and progress. Students can understand the chemical forces involved in the gradual evolution of the currency, and their natural science literacy, humanistic feelings and social responsibility, science literacy, humanistic feelings and social responsibility are enhanced during the progress.

General education courses are important for the students to form a complete knowledge structure and balance between science and liberal arts. The author has offered a course named Chemistry in Liberal Arts and uses Chinese ceramics as an example in this paper. The artistic characteristics of several important stages in the development of Chinese ceramics and the relative chemical knowledge are introduced. The paper also discusses the exploration to combine scientific knowledge with cultural heritage, so as to encourage students to enhance their national cultural confidence and improve their scientific and humanistic literacy.

Adrenaline, an important hormone in the human body, can stimulate the cardiovascular system. In this paper, the discovery, development and clinical use of adrenaline and its derivatives are briefly described by means of personification, by combining with simple and understandable medical knowledge, cases and historical stories.

Water is a necessity for human survival. The safety of drinking water has always been an important factor that affects people's lives and health. Thus, determining the water quality is a key point of national guidance. Based on the instrumental analysis course of the College of Chemistry of Nankai University and literatures, students chose a topic wherein the anion type and concentration in common drinking water were determined with the assistance of teachers. Thus, they judged the differences of different types of drinking water and whether they meet the national standards. The experimental results would provide theoretical guidance and suggestions for the people to choose the safest drinking water. Additionally, this experiment stimulated students' interest in learning and further deepened their understanding and application of ion chromatography analysis technology. The performance of this experiment represents a close combination of theory with practice. This enables students to flexibly apply the knowledge they learned in the course of instrumental analysis to real life and deepens their understanding of the close relationship between chemistry and daily life.

This experiment introduces a method to measure the rate coefficient for the rapid reactions of transient free radicals with pollutants in an aqueous phase. Transient free radicals are generated via laser pulse photolysis and are detected using transient absorption spectroscopy. Second-order rate coefficients are obtained through the absolute rate method or relative rate method. In addition to a thorough understanding of chemical kinetics, this experiment will introduce students to innovative research in the field of environmental photochemistry of pollutants.

The detection of sulfur dioxide is crucial for food safety. In this study, a flow injection chemiluminescence method for the determination of sulfur dioxide in food was established by using an acidic potassium permanganate sulfite system with carbon dots (CDs) as the sensitizer. Under the optimum experimental conditions, the linear range, and the detection limit of the method were 1.0 × 10⁻⁵–3.0 × 10⁻⁴ mol∙L⁻¹ and 7.79 × 10⁻⁶ mol∙L⁻¹, respectively. The experiment is suitable for teaching instrument analysis to undergraduates. This experiment enables students to master the principle and application of chemiluminescence and flow injection analysis, learn the basic methods of scientific research, and improve their thinking ability.

In this work, the synthesis of Grignard reagent is improved by replacing molecular iodine with diisobutylaluminum hydride (DIBAH). Systematic investigations on the influence of DIBAH initiation on the safety of the reaction system and the chemical structure of haloalkanes are performed. It has been demonstrated that the addition of 2 mol% DIBAH (vs. the molar content of haloalkanes) allows the reaction to take place under mild condition (20 ℃), yielding phenyl magnesium bromide and n-butyl magnesium bromide with high efficiency. With the improved safety on modified Grignard reactions, the students could get a deeper understanding on the importance of safety in chemical reactions. In particular, the present work could also help students to pay attention to safety of organic experiments and the dilemmas encountered by practical applications, and better cope with the gap between fundamental research and industrial applications.

Combined with the application of powder X-ray diffraction technology in the field of phase analysis, a comprehensive and innovative experiment was designed. The experimental contents mainly include the use of powder X-ray diffraction to monitor the structural transformation of excited-state intramolecular proton transfer (ESIPT) organic molecule 5-(2-(5-fluoro-2-hydroxyphenyl)-4, 5-bis(4-fluorophenyl)-1H-imidazol-1-yl)isophthalic acid (H₂hpi2cf) under fumigation of solvents. This experiment comprehensively cultivates students' operation skills and data processing and analysis ability of powder X-ray diffraction, and improves students' ability to use modern scientific instruments to solve practical problems.

Synthesis and structural characterization of organic compounds are important content of organic chemistry laboratory teaching. This article introduces a comprehensive organic chemistry experiment carried out at College of Chemistry, Nankai University. In this experiment, diphenyl 3, 5-di-tert-butyl-p-quinone phosphonate and 2-methylbenzene-1, 3-diol are the reactants, and the tandem cyclization reaction occurred under the catalysis of trifluoromethanesulfonic acid to generate benzo[d] [1,2] oxaphosphole 2-oxide. The structure of the product is characterized by ¹H NMR, ¹³C NMR, ¹³P NMR and HRMS.

In this study, a computational chemistry exploration experiment for senior undergraduate or beginning graduate students is designed. The rotational isomerization reaction of an allyl cation is investigated using density functional theory (DFT) calculations. The theoretical experiment involves molecular geometry optimization, transition state location, and establishment of intrinsic reaction coordinates (IRCs). This design can help students understand the basic concepts and operations of computational chemistry. Furthermore, the concepts of molecular microstructures and the notion of "old bonds are about to break and new bonds are about to form" in the transition state theory are discussed. This experiment will also aid the understanding of the differences between reaction thermodynamics and kinetics through the construction of potential energy surfaces. Further investigations of charge population analysis and frontier orbital analysis will aid the understanding of electronic structures of molecules as well as the concept of reaction reactive sites.

This experiment introduces the application of chemistry in archaeology through the detection and analysis of alcoholic beverage residues in pottery. Organic acids which are the indicators of alcoholic beverage residues are extracted through a series of experimental steps such as extraction, filtration, centrifugation and rotary evaporation, and measured by High Performance Liquid Chromatography (HPLC). Combined with archaeological background of pottery, the results of this experiment can be used to analyze the possible usage of the pottery. Based on emerging interdisciplinary archaeological chemistry, this experiment is offered to students majoring in chemistry and archaeology, which could provide insights into fundamental concepts, basic methods of sample isolation and HPLC analysis, as well as provide primary perception of the focused topic in archaeology.

The preparation of coumarin-3-carboxylic acid is a classical chemistry experiment. In this experiment, the reactants, salicylaldehyde and diethyl malonate, as well as the piperidine catalyst are mixed under reflux for 2 h to obtain coumarin-3-carboxylic acid after base hydrolysis and acidification. We have made the following improvements and extensive designs to the experiment: 1) By substituting diethyl malonate with Meldrum's acid, coumarin-3-carboxylic acid can be obtained by heating at 90 ℃ for 30 min in water, and 7-(diethylamino)coumarin-3-carboxylic acid can be synthesized by changing the substrate; 2) Observing the fluorescence of the solution with Eu³⁺, coumarin-3-carboxylic acid, and 7-(diethylamino)coumarin-3-carboxylic acid and using computational chemistry can help verify the energy transfer property. The modified experiment, which involves a number of important multidisciplinary knowledge points, has strong modularity, comprehensiveness, interest, and teaching feasibility. Moreover, it is conducive to cultivating students' innovative and comprehensive application abilities.

Herein, a comprehensive chemical experiment is recommended. In this experiment, CuO particles were first grown on carbon cloth via a hydrothermal reaction and then subjected to in situ transition to CuS nanosheet arrays through an anion exchange approach. The CuS product was systematically characterized and its electrochemical performance for copper storage was studied. The design of such an experiment involves the integration of chemistry, materials, energy, and other disciplines. During the experimental process, students can receive basic scientific training in nanomaterial preparation, characterization, electrode preparation, and battery assembly and testing. Such training would help to improve their understanding of materials science and the operation of experimental equipment, while enhancing critical thinking ability. In general, involvement in this experimental design would provide a solid foundation for scientific research of these students. This experiment is suggested for use as one of the comprehensive chemistry experiment courses for senior undergraduates majoring in chemistry and other related subjects.

Cu nanoparticles (NPs) supported on nitrogen-doped porous carbon (NPC) were synthesized by pyrolysis of Cu-metal organic frameworks (MOF) and characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy (IR) to investigate their morphology and composition. In addition, the catalytic performance for the hydrogenation of nitrobenzene was explored and the catalytic reaction conditions were optimized. The methodical experimental procedure was designed in a comprehensive manner to cultivate scientific thinking and enhance the overall analytical skills of students.

The calculation of equilibrium concentrations of each component in the acid-base system is a critical knowledge point in teaching analytical chemistry. Its teaching impact depends on the mastery of the derivation, application, and potential meaning of the distribution fraction (δ) formula. The derivation and application of δ as the focus are time-consuming and tedious. δ has good application in calculating the pH, concentration of each species in the acid-base and complex system, buffer capacity, and titration error. In this study, the methods for the rapid derivation and convenient application of δ in n-ary acid-base solutions were examined. The application of this study helps stimulate students' interest, improve cognition, and enhance understanding.

By taking acid-base titration as an example, Chinese poetry and other cultural works were introduced into the introduction, exercises, and ideological and political education of the introduction to acid-base titration, pH indicators, and titration experiment. This paper aims to stimulate students' interest in analytical chemistry and deepen their understanding on relevant knowledge points. Moreover, it should be also beneficial to cultivate students with patient, meticulous, rigorous, and realistic scientific attitudes as well as enhance humanistic quality of college students.

Acid-base titration is the most basic experiment in analytical chemistry. The titration curve reflects the whole process of neutralization reaction and is very important to understand acid-base titration. Based on three basic hypotheses, the chemical equilibrium, electroneutrality principle and mass balance, we established mathematical model between ionization degree and pH as well as titration percentage by keeping one parameter unchanged and the other two changed at the initial point. In addition, we recovered the acid-base titration curve by performing mathematical analysis and derivatization of the function. Through the analysis of two initial conditions in mathematical formula and the effects on the function, the quantitative validation on interpretations was introduced for reactions of different concentrations and strength of acids in titrations described in traditional teaching materials. With theoretical expansion of titration curves, we proposed a possible method for weak acid titration.

The preliminary principles of chemical thermodynamics have been introduced in current inorganic chemistry text books but have not been well applied to examples. In this paper, the Gibbs free energy change Δ_rG_m^ϴ is taken as the main line of the teaching content of chemical reaction process. It is used to deal with the precipitation-dissolution equilibrium, oxidation-reduction equilibrium, acid-base equilibrium and coordination equilibrium with ionic reaction characteristics. These enable students to understand "chemical equilibrium" from the perspective of thermodynamics, overcome the drawbacks of describing "chemical equilibrium" in terms of chemical reaction rate kinetics, and achieve the essential understanding of "chemical equilibrium" and its application in reaction systems with ionic reaction characteristics. Moreover, the teaching content of the inorganic chemical reaction principles is reconstructed according to the main line of chemical thermodynamics.

Approximate calculation of the pH of a NaHA solution plays an important role in analytical chemistry. However, the physical meanings and applicable conditions of the pH approximate formulas are not demonstrated in detail in current textbooks. In this paper, the applicable conditions and physical significance of various approximate formulas are described. The approximate formulas with incorrect physical meanings and inappropriate applicable conditions should be modified. NaHA solutions can be categorized as acidic (K_a1K_a2 > K_w) or alkaline (K_a1K_a2 < K_w). When cK_a2 ≥ 20K_w, by assuming that the production of OH⁻ from water and from HA⁻ is negligible, the approximate formula of an acidic NaHA solution is obtained. When c ≥ 20K_a1 (namely cK_b2 ≥ 20K_w), the approximate formula of an alkaline NaHA solution is obtained by ignoring the production of H⁺ from water and HA⁻. The formula pH = (pK_a1 + pK_a2)/2 is suitable for both acidic and alkaline NaHA solutions, but their applicable conditions are quite different. This paper carefully discussed the pH calculation of NaHA solutions. The computation results demonstrated that some formulas should be disabled and the related wrong statements in textbooks be corrected.

The C₄H₄ and C₈H₈ monocyclic polyene systems are treated automatically as the conjugated delocalized triplet molecules by Hückel molecular orbital (HMO) method, but this is inconsistent with their actual ground state structures associated with singlet state. In this work, both the singlet and triplet molecular structures of the four-membered ring and the eight-membered ring were optimized by density functional theory (DFT), and the more accurate π bond orders were calculated. Based on the DFT calculated results, we suggested a solution that can correctly compute the π bond orders in the C₄H₄ and C₈H₈ monocyclic polyene systems by using the HMO method.

The effect of solvents on the nucleophilicity of nucleophiles is an important teaching topic in organic chemistry. Considering the bimolecular nucleophilic substitution (S_N2) reaction between methoxide (CH₃O⁻) and thiomethoxide (CH₃S⁻) anions with chloroform (CH₃Cl) as a representative example, this paper designs a teaching case for integrating computational chemistry into the organic chemistry curriculum. By performing quantum chemical calculations, we determined the reaction mechanism, obtained the thermodynamic and kinetic information of the reactions, and investigated the effect of solvents on the properties of nucleophiles. Polar protic solvents, such as methanol and water, and polar aprotic solvents, such as acetone, acetonitrile, and chloroform, were analyzed. The nucleophilic index was also calculated to evaluate the nucleophilic reactivities of CH₃O⁻ and CH₃S⁻.

The end-point error of an asymmetric redox titration is related to the potential of the end-point and equilibrium concentration of the titration product, both of which are bottlenecks in the calculation of the end-point error. To overcome these problems, we have comprehensively considered the quantitative relationship between material balance, electronic balance, and the Nernst formula. On this basis, a series of equations were constructed, whose unknowns were the equilibrium concentration of titration product and titration volume ratio. The equations were solved using a software called Scilab. By substituting the solution results into the relevant formula, the end-point error could be obtained, which was consistent with the literature value.

In view of the problems existing in the teaching of instrumental analysis for undergraduate students, such as the outdated teaching materials, course contents, lack of examination and evaluation standards, we summarize the current teaching materials and course systems related to instrumental analysis chemistry in some representative foreign universities. Through comparative analysis, we hope that this paper can provide a powerful reference for our future course construction of instrumental analysis, the improvement of teaching content and the reform of assessment methods.

Talent training in the discipline of chemistry, at the higher education level, involves the enhancement of many skills. A good scientific research training environment is very important—it not only enables students to implement their professional knowledge, refine their understanding of research theories, and hone various experimental skills but also plays a key role in cultivating scientific thinking. This paper outlines the details from our initial entry into the laboratory to contact scientific researchers and the successful application of "National Training Programs for Innovation and Entrepreneurship for Undergraduates, " by taking the 2019 cohort of undergraduate students' participation in the scientific research innovation and scientific innovation competition as the main focus. Experience sharing will provide a reference for undergraduates who are willing to participate in scientific research and innovation training.