In faculty development, understanding each participant’s cultural context is important. However, there is scarce evidence on how to improve cultural understanding in faculty development. Cultural anthropology is a discipline that focuses on developing cultural self-awareness by understanding different cultures. Professionals from this field can be crucial to the goal of cultivating cultural awareness among medical educators. The aims of this study are to 1) develop and modify cultural anthropology sessions in faculty development and 2) evaluate the effectiveness of these sessions, including their long-term impacts.The cultural anthropology sessions were organized as part of a longitudinal faculty development program—Foundation Course for Medical Education—at Kyoto University in Japan. The study included 47 medical educators participating in faculty development and three lecturers: two cultural anthropologists and a medical educator. We developed the cultural anthropology sessions and implemented them in the longitudinal faculty development program. In these sessions, cultural anthropologists used inquiry-guided reflection. An action research methodology was employed and repeated in four cycles from 2015 to 2018. Qualitative and quantitative data were collected during the action research cycles. The qualitative data were thematically analyzed.The cultural anthropologists’ inquiries fostered learning during the sessions, and three themes—cultural relativism, attention to context, and reframing—were synthesized. As a long-term impact of the sessions, the learners reported becoming more aware of the cultural contexts in their daily educational and clinical activities.The cultural anthropology sessions in the faculty development program were shown to have enhanced the participants’ awareness of cultural contexts. The concept and format of these sessions may be used more widely in faculty development programs.The online version contains supplementary material available at 10.1186/s12909-022-03260-7. It is well known that awareness of cultural context is imperative in medical education, and the importance of considering cultural context during faculty development (FD) has been recognized and discussed more frequently in recent years –3. As FDEffective FD programs should therefore include a session focused on cultivating participants’ cultural awareness. Cultural anthropology (CA), a discipline that focuses on the study of different cultures, provides a suitable foundation for developing cultural self-awareness in individuals  and for The history of medical education recognizes that methods and theories of medical education—many of which were developed in Western culture—have been introduced to other countries. However, such methods and theories have not always been successful in the highly context-dependent field of medical education . MedicalIn this study, the authors developed a CA session to cultivate cultural awareness among medical educators and implemented the same in a longitudinal FD program. The aims of this study are to 1) develop and modify the CA session and 2) evaluate the effectiveness of the CA session, including its long-term impact.We used an action research methodology, which is appropriate for making decisions about program improvement through repetitive reflection, data collection, and analysis , 16. We The CA sessions were developed as part of a longitudinal FD program—Foundation Course for Medical Education (FCME)—at Kyoto University in Japan. FCME is a one-year part-time medical education program conducted in web-based and face-to-face sessions. The curriculum contains sessions on teaching and learning, assessments, curriculum development, informatics technology, research, philosophy, leadership and management, general, others, and CA. Twelve participants enroll in the program each year; they are physicians who teach medical students and residents at medical schools or teaching hospitals. The program was first established in April 2015 and over 70 participants have graduated from the program as of 2021.This study involved 47 participants: 12 each for the classes of 2015, 2016, and 2018, and 11 for the class of 2017. Additionally, the study involved three lecturers: one medical educator and two cultural anthropologists. One participant from the class of 2017 was excluded due to absence from the CA session. The participants were a diverse group of individuals with different ages and areas of specialty , and a cultural anthropologist (JI) initiated discussions about drafting CA sessions, establishing learning objectives, scheduling, and educational format. They have collaborated for over a decade in research and teaching settings and obtained successful results . Based oAs an educational format, they offered a case-based, inquiry-guided reflection. In this format, each participant presented a case of educational practice that they learned in one context and applied in another, with detailed descriptions of their backgrounds; for example, the size, location, or organization of the institutions they learned from and where the practices had been applied. Following the presentations, the participants reflected on how and why their practices succeeded or failed, and the cultural anthropologist lecturer asked questions about the case. By answering the anthropologist’s questions, participants were expected to gain a self-relativization perspective and view themselves differently. In addition to the cultural anthropologist, the medical educator and other participants also asked questions about the case. The CA sessions were web-based, and after the session, each presenter wrote a short reflective essay on the insights gained from the session and submitted it as a post-session assignment. We introduced three books for the participants as references –22.In this case-based, inquiry-guided reflection, participants reflected on the case, and then the cultural anthropologist asked questions to help them reflect further. The developers selected this format because guided reflection is known to help learners develop reflective thinking , and theEach year, the lecturers reflected on the CA session and, depending on the survey results, modified the contents if necessary.To assess the lecturers’ modification of the CA sessions, the main author investigated the updated syllabus of the CA session in the planning phases of 2016 to 2018.To assess the effectiveness of the CA sessions, we collected multiple data in each cycle of action research. In the observation phase of each year, all CA sessions were video recorded; and observation logs, including the qualitative data of participants’ presentation and questions asked by the lectures and other participants, were collected. The post-session assignments, post-session questionnaire, and post-program questionnaire of all participants were also collected via Google forms  with experience as an ethnographer in hospital and educational facilities joined the team. Furthermore, the 15 min for presentation and discussion per participant was often insufficient. Therefore, starting from the Class of 2016, the presentation and discussion time per participant was increased to 30 min.The final model of the CA sessions is shown in Table Based on the observation logs, the questions by the anthropologist were divided into two themes: questions about the institutions’ socio-cultural backgrounds and those about their educational practices. The anthropologist asked questions that revealed the cultural contexts in the healthcare setting that medical professionals often take for granted. After elucidating the cultural context of the participants’ cases, the cultural anthropologist asked questions that encouraged the participants’ reflection regarding their educational practices. As an example, the inquiry-guided reflection for Dr. A, an internist, is shown in Table In terms of how the cultural anthropologist’s inquiries fostered learning during CA sessions, three themes—cultural relativism, attention to context, and reframing—were synthesized. Initials were used to indicate the type of contributor (P = participant and L = lecturer), type of data source , and the year of the class or year of data collection.Although the participants tried to describe the cultural and contextual differences in detail, it was still accomplished through their lenses as medical professionals. The contextual issues, including differences in the learning environment and learners’ needs or motivation for learning between institutions, were easily shared with peers without detailed explanations, and these were often perceived as a superior-inferior relationship. However, the cultural anthropologist had difficulties understanding such “common perceptions among medical professionals,” and upon inquiry, the presenter noticed differences in their views on culture. Some participants struggled to understand the distinctive aspects of CA, but, gradually, they were able to reflect on the two different contexts as relative rather than as having a superior-inferior relationship. The phrase “cultural relativism” has several variants, including the idea that individuals’ beliefs are relative to the social contexts surrounding them , and thaWhen I was teaching learners as an attending physician, I didn’t doubt that the hospital culture I was trained in was superior to the learners’ hospital culture. I think I made many mistakes with that. Even in the same country, there are cultural differences between hospitals. If I had known that there is no superiority or inferiority between cultures, I might have avoided such mistakes. (PP 2017)A sample response:The assigned books and discussion with the cultural anthropologist allowed the participants to understand that different contexts have different practices and that educators should consider the context in which teaching methods are applied. Furthermore, they recognized which teaching method was more appropriate in individual situations and that they should objectively analyze contexts. Throughout this session, it was evident that participants began to focus more on context.I realized that I focused too much on the methodology of this journal club as a cause of failure. The book ‘Situated learning: Legitimate peripheral participation’ widened my view. Learning should not be an independent activity, and people learn things better within social contexts. This perspective is what I should have had when I introduced a new project. I should also focus on the communities of practice to which the participants belong. For example, learning objectives should be based on the learners’ needs and relevant to their practice situations. I obtained a new viewpoint, “the participants’ situation or context,” by reflecting on my educational activities. (PP 2017)A sample response:Based on the reflection, the main role played by the cultural anthropologists in the sessions was to “reframe.” Inquiry-guided reflection by the cultural anthropologist effectively fostered the participants’ self-awareness of their cultural and social contexts by reframing their ways of thinking, beliefs, or positions. Therefore, participants discovered new insights through discussion with the cultural anthropologist.The anthropologist’s questions reminded me that what I consider obvious while talking to healthcare professionals may not be obvious for people in other specialty fields. I think the anthropologist lecturers in this session were instrumental in helping me think about understanding others. Because our learners are the others. (PQ 2015).We can provide the participants with something to shift them from the frame they are using now or give them another viewpoint. Maybe we can do nothing more. I think it would be great if they are encouraged through discussions with anthropologists who specialize in thinking about cultural contexts. (LI 2018).Interestingly, we [physicians] usually did not ask questions about our educational practice backgrounds, considering the socio-cultural contexts. However, that is important when introducing a new educational activity. The anthropologist asked how many members were in the department, about the venue of the journal club, and details of the hospital’s situation. As physicians, we sometimes ignore these points of view. (LI 2018)Sample responses:Fourteen out of 47 (29.8%) participants responded to an e-questionnaire sent out in 2019; all respondents indicated that the CA sessions impacted their educational activities and practice. In terms of how the CA sessions affected their education and clinical practices, the main theme synthesized in the thematic analysis was intense awareness of context.I used to focus on the abilities and qualities of the medical students and residents, but after attending the CA session, I also pay attention to other contexts such as the learners’ background and environment. (PQ 2016)I became more aware of the cultural context of the patients in the clinical practice. (PQ 2015)I started a new pre-clinical clerkship session for medical students in collaboration with cultural anthropologists inviting the concept of fieldwork with the learning objective of enhancing cultural context-awareness. (PQ 2016)Figure Sample responses:ment. PQ 016I becaThe authors found that the anthropologist’s questions fostered the learners’ self-reflection by deepening their insight about their educational practices with contextual perspectives. In the CA sessions, unexpected questions about cultural contexts were raised during the inquiry-guided reflection. By answering such questions, the participants’ awareness of “context” developed, and they began to focus on “culture” and “context” more than before. Faculty development activities should employ strategies that stimulate participants’ reflection , 29. HowAs the theme of “cultural relativism” suggests, the perspective of the cultural anthropologist had a significant impact on the participants’ realization that there is no superiority-inferiority relationship between the cultures of training hospitals. As to why the participants unconsciously perceived a superiority-inferiority relationship among the training hospitals, the results of previous studies on resident matching programs might have influenced their perceptions. Studies showed that resident applicants placed great importance on the quality of the education provided in the hospital , as wellThe result of this study showed that being aware of one’s unconscious perceptions of the superiority-inferiority relationship between cultures of training hospitals might be useful, especially when introducing educational practices from one context to another. Cultural relativism could act as a framework based on which educators reflect on their practices when they are unable to conduct these practices as successfully as they expect.The CA sessions in FD programs enabled an awareness of conditions and circumstances that are often too mundane for the participants to notice. The cultural anthropologist’s purely explorative questions led the participants to review their fixed ideas and norms from a different viewpoint. As previous research has shown, the approach of cultural anthropology has contributed to other specialties by reframing the questions of neuroscience research  and mitiIn terms of long-term impact, our study showed that CA sessions might have a certain effect on the participants as educators as well as physicians. The participants increased their awareness of the cultural contexts of not only their students but also their patients. Furthermore, the participants became interested in the discipline of anthropology itself through learning about its theories and concepts. A participant applied the concept of fieldwork to his educational activities by collaborating with the anthropologist. These results have not been described in previous studies about outcomes of FD , 36, andConsidering the above findings, we recommend that FD organizers work with cultural anthropologists to make FD programs more culturally contextual. Collaboration between medical education and cultural anthropology has enormous potential. As the next step, inviting cultural anthropologists into teaching practice settings may be useful, as they could analyze the teaching activities from an ethnographic perspective. Hence, external consultants for FD are recommended for assisting educational change . This stThis is a single institution study involving 47 graduates. Due to curriculum modification implemented in 2016, the impact of this session on the participants in 2015 and thereon in 2016 may not be the same. In the analysis of long-term impact, we should interpret the results carefully since the response rate was low. In addition, there is a methodological limitation with collecting the graduates’ e-questionnaire once in 2019, which meant that the duration after graduation was not equal for all graduates. Ideally, the graduates’ behavioral changes should be observed in their workplace with an immersion approach after graduation.We developed and analyzed a model of FD that includes CA sessions. Our results showed that medical education could learn a lot from CA, as working with individuals from different cultural backgrounds requires self-reflection and personal awareness. Furthermore, our results implied that more collaboration between medical education and CA would enrich our medical education activities, including FD.Additional file 1. Post-session questionnaire.Additional file 2. Post-program questionnaire.


Effects of electropolishing on the quality and the Raman response of the grown graphene layers are studied by microtexture polarization analysis. The obtained data are compared with the Raman signal of graphene after transfer on glass substrate revealing the complex interaction of graphene with the Cu substrate.Graphene films were grown by chemical vapor deposition on Cu foil. The obtained samples were characterized by Raman spectroscopy, ellipsometry, X-ray photoelectron spectroscopy and electron back-scatter diffraction. We discuss the time-dependent changes in the samples, estimate the thickness of emerging Cu Since its discovery, graphene has been viewed as promising candidate for novel optoelectronic devices due to its extraordinary ballistic transport over micron lengths and large carrier mobility ,2,3 combThese optimistic prospects are, however, confronted by plenty of technological difficulties. The main problem is the challenge to achieve growth of nondefective graphene over sufficiently large areas. An important prerequisite for this goal is to have reliable backfeed by a standardized characterization of the obtained graphene directly on the metal substrate, which has to account for the whole complexity of graphene’s interactions with the metallic substrate/stabilizer, its possible oxides and gases/liquids which can come in contact with it during processing. As the commonly used CVD substrate is commercially obtained polycrystalline Cu foil, intensive research work was devoted to study the impact of Cu surface morphology and grain orientation on the grown graphene ,9. It haG) and 2D band (ω2D) of graphene is commonly used for quantifying strain and doping effects [Raman spectroscopy is a preferred characterization method for the study of graphene and the novel graphene-like 2D materials, as it is nondestructive, achieves high resolution with relatively simple commercially available setups and provides valuable information on the defect density, number of layers and their mechanical state. Most importantly, this technique reveals details of the electronic structure via the electron–phonon coupling and the rich single- and double-resonance phenomena characteristic for the Raman response of carbon-based materials. However, the versatility of this method is inherently connected to its main disadvantage—complex data interpretation—because of the need to account for the variability of many parameters. For instance, the combined plot of frequencies of the G-band , ellipsometry and electron back-scatter diffraction (EBSD). We find that immediately after CVD growth, the strong Cu-graphene coupling is still detectable in the XPS spectra in addition to its manifestation in the Raman spectra. In order to find a measure for the relaxation of this coupling with time, we use ellipsometry to estimate the thickness of the emerging Cu3PO4 solution with the polished copper foil as the anode and a copper plate as the counter electrode at polarization voltage of 1.98–2.02 V at room temperature. Similar to [Both raw (as supplied) and electropolished copper foil  was used as the growth substrate. Electropolishing was performed in 85% concentrated Hmilar to , the ano4 flow combined with 200 sccm H2 flow, were introduced for 30 min into the reaction chamber for the growth stage. Afterwards, the sample was quenched to 300 °C at 15 °C/min in hydrogen/argon atmosphere. Cooling to room temperature was done in high-purity argon atmosphere. The grown samples were kept in clean room environment prior to characterization and during aging.The graphene was grown in a cold wall Plasmalab System 100 research reactor of Oxford Instruments using low-pressure chemical vapor deposition (LPCVD). Low-pressure growth (4000 mTorr) was preferred because it yields lower graphene nucleation density  and the −1 spectral width. The 632.8 nm line of a He/Ne-laser was applied for excitation using a 600 gr./mm grating, the absolute accuracy being about 1 cm−1. The laser beam was focused on a spot of about 1–2 μm in diameter on the sample surface using microscope optics with an objective of 50× magnification. The Raman measurements were performed on the graphene-coated Cu foils and after PMMA-assisted transfer onto glass substrates. The measured frequencies were calibrated by means of the T2g vibration of silicon at 520.7 cm−1 and the lines corresponding to the stretching vibrations of oxygen and nitrogen at 1556 and 2331 cm−1, respectively, which are contained in the spectra.Raman spectra were measured on a Jobin Yvon Labram HR-800 spectrometer with a CCD detector and entrance slits set to 1.5 cm−8 Pa and a total instrumental resolution 1 eV. The binding energies (BE) were determined utilizing the C 1s line (from an adventitious carbon) as a reference with energy of 285.0 eV. The accuracy of the measured BE was 0.2 eV. The photoelectron lines of constituent element on the surface were recorded and corrected by subtracting a Shirley-type background and quantified using the peak area and Scofield’s photoionization cross-sections. The decovolution of spectra where is necessary was done with XPSPEAK41 software.The X-ray photoelectron spectroscopy (XPS) studies were performed in a VG Escalab MKII electron spectrometer using AlKα radiation with energy of 1486.6 eV under base pressure 10The ellipsometry measurements were performed using a Woollam M2000D rotating compensator spectroscopic ellipsometer with a wavelength range from 193 nm to 1000 nm in reflection mode. The involved data acquisition and analysis software was CompleteEASE 5.10 J. A. Woollam Co., Inc.  The spectroscopic ellipsometry data of Ψ and Δ were taken at room temperature at angles of incidence 50°, 60° and 70°.® 6–60) on specimens tilted at 70° with 5 kV acceleration voltage in order to find the appropriate surface. The high tilt angle and the lower acceleration voltage ensures the low penetration of the electrons, i.e., small interaction volume close to the specimen surface.The EBSD measurements were performed on a Thermo Fisher Scios 2 FIB/SEM instrument equipped with BRUKER e-FLASH FS EBSD detector with acceleration voltage 15 kV. Oxygen elemental distribution maps were measured by EDS (BRUKER XFlash2O). When freshly taken out of the CVD chamber, the entire area of the foil looks similar to the left part of the left image with corresponding typical Raman spectrum as the “blank”-marked trace in 2O bands at 149, 216, 525 and 640 cm−1 [A typical case of time evolution of a graphene-coated Cu (Gr/Cu) foil is depicted in 640 cm−1 ) while oTo obtain a more quantitative picture of the oxidation development with time we performed a detailed characterization with different experimental methods on 3 samples with different storage times after CVD growth (6 months for the second and 20 months for the third sample) and with consecutive increasing density of reddish coloring. These samples will be referred to as “6 months” and “20 months” in what follows. The first sample referred to as “fresh” was examined immediately after graphene growth.A detailed XPS examination of the three samples was performed. Microscopic images and fitted C1s spectral bands are displayed in 2 graphene at 284.2–284.4 eV. Interestingly, only for the “fresh” sample there is a peak at around 284.9 eV with much higher intensity than that of the conventional sp2 peak. This is consistent with the assumption that immediately after the growth process, the major part of the graphene layer is still strongly coupled to the copper substrate via exchange interactions between the Cu valence electrons and the carbon C1s core hole which yields a C1s sp2 signal at 284.75 eV [3 sites as well as defects in the graphene honeycomb lattice and C-H bonds whose signal is located between 285.0 and 285.5 eV. In the C1s spectra of the other samples these three contributions form a separate peak which is denoted as sp3 peak. Several other satellite peaks due to oxygen-containing groups are also detected. The peak at around 286 eV belongs to C-O/C-OH moieties, that around 288 eV to O=C-O bonds and carbonate groups, and that at ≈283 eV to sp1 type carbon bond in C2Cu. As expected, the oxygen-related peaks are more intense for longer storage time.The C1s spectra are complex and their most intense component is typically the C1s peak of sp84.75 eV . In our 2O. As expected, this oxidation-related peak has maximum intensity for the sample with the longest storage time of 20 months. There is a shoulder at the higher binding energy side which is accounted for by the third peak at around 532 eV. The appearance of this shoulder is related to formation of C-O/C-OH and C=O bonds. From the Cu 2p photoelectron spectra in 0  and Cu1+ (Cu2O) for all studied samples. The same is evidenced by the Auger CuLMM line  values from our measurements on the three samples. As can be appreciated from −1 for ωG and around 2660 cm−1 for ω2D. This indicates significant compressive strain and, on the other hand, ω2D is additionally upshifted due to the Fermi velocity reduction which is significant for our low excitation laser energy of 1.96 eV [G, ω2D) values around the zero-strain point at  cm−1 [2O bands, which are completely missing in the “fresh”-sample spectra, display considerable intensity in the spectra of the two older samples. The  values for sample “20 months” are more scattered with some points implying a transition to tensile strain imposed by local Cu2O aggregations [Comprehensive spatially resolved Raman measurements were performed on the three samples. Representative spectra from this characterization are presented in ed shift  and a shed shift . As thered shift ,29, we c 1.96 eV . As the .3) cm−1  with somegations . It shou−1 (compared to ~29 cm−1 before transfer). In From the collected Raman data, we obtained values for the peak intensity ratio of the 2D and G band I(2D)/ I(G) ranging from 2 to 2.8 which can, however, be impacted by the graphene-Cu coupling. In the 2O patches on this grain. Still, we regard oxygen etching of graphene edges and grain boundaries as the main mechanism ensuring a slowly advancing oxidation of the substrate [The oxygen content in the 3 examined samples as calculated from the XPS spectra is given in ubstrate . As was ubstrate , vacuum ubstrate  at even 2O layer by means of spectroscopic ellipsometry (SE) for the fresh and the 6-month-old sample. There are only few ellipsometric studies of as grown graphene on metals [To examine the weakening of the Cu-graphene coupling upon oxygen intercalation it is instructive to find a measure for the separation of the graphene layer from the Cu surface. We therefore estimated the thickness of the formed Cun metals , while mn metals ,33.As there is increasing evidence that the Cu oxidation rate beneath the graphene depends on the surface orientation of the copper grains , we exam2O participating in the model with optical constants taken from Palik’s Handbook of Optical Constants [2O average thicknesses were obtained: fresh sample: ≈0 nm; sample “6 months” low-oxidation region—0.5 nm; and sample “6 months” high-oxidation region—6.5 nm. From the strong variation of the oxide thickness and the obvious coincidence of the boundaries of differently colored regions with the Cu grain boundaries, as can be appreciated from the microphotographs in The ellipsometric data for Ψ and Δ were modelled within a model consisting of two consecutive layers on top of an oblique substrate which is the copper foil. The first layer is Cuonstants   orientation exhibit the lowest oxidation rate. Grains with orientation near to (111) display an intermediate affinity towards oxidation. Surprisingly, these results are the opposite to those reported in [orted in , where f near to 1 displayorted in , the parorted in  on polycElectropolishing has been frequently applied as part of the Cu foil pretreatment to lower its surface roughness and to achieve better quality of the grown graphene ,38. Here−1 after transfer onto glass as compared to ~15 cm−1 for unprocessed Cu foil). It is also found that the Cu-graphene coupling makes the intensity ratio of the 2D and G band less informative for determination of the number of layers and it becomes a reliable parameter only after the transfer on isolating substrate.From the Raman spectra in To further illustrate the effect of electropolishing, we visualize the domains in the graphene layers grown on an electropolished and on a nonprocessed Cu foil by means of the nematic liquid crystal (LC) E7. This is possible due to the interaction of two-dimensional graphene-honeycomb structure with the LC benzene rings through π–π electron stacking (binding energy of −2eV) which induces a planar alignment of the LC, thus creating LC pseudonematic domains (PNDs) at the graphene surface . As the 2O as a way for its relaxation. Correlating results were obtained from Raman and XPS characterization, ellipsometry and the EBSD technique. We find strong Cu-graphene coupling on the nonoxidized Cu grains and gradual release of this coupling along the “strain” line without significant doping effects. Our ellipsometric results provide an estimate for the typical oxide layer thickness beneath the graphene after 6 months of sample aging, which varies from fractional parts of a nanometer to 6–7 nm. We confirm that in the case of polycrystalline foil oxidation to Cu2O of graphene-coated copper is grain-selective, with (001)-oriented grains being most resilient and (011)-oriented ones most susceptible to oxidation. Correspondingly, the strong Cu-graphene coupling and the strain in the graphene lattice is released very nonuniformly and over different time scales.We investigated single-layer graphene-coated Cu foils with respect to the Cu-graphene coupling and Cu oxidation to CuFrom a visualization of graphene grains by means of coating by liquid crystal, it is found that graphene grown on electropolished Cu foil exhibits larger grains with lower defect density. It is found that the Cu-graphene coupling alters the frequency and the intensity ratio of the G and 2D band, and a determination of the number of graphene layers from Raman spectral parameters should preferably be made after transfer on isolating substrate.


This paper presents the effect of deposited graphene oxide coating on fatigue life of austenitic steel 1.4541 at 20 °C, 100 °C, and 200 °C. The study showed a decrease in the fatigue life of samples with a deposited graphene oxide layer in comparison with reference samples at 20 °C and 100 °C. However, an increase in fatigue life of samples with a deposited graphene oxide layer in comparison with reference samples occurred at 200 °C. This relationship was observed for the nominal stress amplitude of 370 and 420 MPa. Measurements of temperature during the tensile failure of the sample and microfractographic analysis of fatigue fractures were performed. Tests have shown that graphene oxide deposited on the steel surface provides an insulating layer. A higher temperature of the samples with a deposited graphene oxide layer was observed during fracture compared to the reference samples. Improvements in mechanical properties after the addition of graphene or its derivatives to composites have resulted from many research projects ,2,3,4. TLi et al.  showed tNajfi et al.  conducteTaking into account the increase in fatigue life of composites containing graphene ,4,5,6,7 Currently, the most well-known method for depositing graphene on the surface of (mainly) copper is chemical vapor deposition (CVD) ,9,10. HoHowever, to date, fatigue life tests at elevated temperatures  of flat specimens made of 1.4541 steel with a deposited graphene oxide (GO) layer have not been performed. Therefore, taking into account the operation of many machine parts and structural elements at elevated temperatures, the aim of this work was to determine the effect of a deposited graphene oxide layer on mechanical properties.Static tension tests and fatigue life tests were performed on flat paddle specimens of 5 mm thickness made of 1.4541 steel according to the following designations: BM—base material (as supplied) , and BM p < 0.045; S < 0.015; T < 0.70; and Fe = bal. Test specimens were cut by the Water jet method from a 2000 × 1000 × 5 mm3 metal sheet perpendicular to the rolling direction. The inner edges of the specimens were subjected to a milling process as shown in The dumbbell specimens  were madGraphene oxide (GO) flakes dispersed in water were obtained from flake graphite by a modified Hummers method . The concentration of graphene oxide water dispersion was 10 g/L. Flake size was 3–10 µm. The detailed synthesis method was described previously in ,12,13.In the first step of graphene oxide deposition on BM + GO samples, surface activation and cleaning with RF (radio frequency) plasma was performed using a Plasma Prep III device  a. The foStatic tensile and fatigue tests were performed using an Instron 8862  electromechanically driven testing machine with a force range of ±100 kN a coupledFatigue tests were carried out for different stress levels Rm = 0.6, 0.7, 0.8, and 0.9 at maximum stress levels of 370, 420, 500, and 540 MPa respectively . The cycDuring static and fatigue measurements at 20 °C, the temperature distribution was performed using a FLIR  model SC6000 thermal imaging camera c. The caGraphene oxide deposited on screw was investigated by scanning electron microscopy (SEM) using a Quanta 250 FEG SEM, FEI, Hillsboro, OR, USA. SEM images were acquired using a backscattered detector  with an accelerating voltage of 2–5 kV for GO and 5–10 kV.The measurements of the changes in surface roughness of stainless steel 1.4541 as a result of plasma cleansing and GO deposition were made using a confocal microscope Zeiss LSM 700 . The experimental parameters were laser wavelength 405 nm, pinhole 0.5 AU (Airy Unit), and gain 416 nm. Five measurements for each sample were made.−1 with a resolution of 4 cm−1.Measurements of the spectra of GO in the infrared range were made using the FTIR technique in reflection mode. The measurements were made to confirm GO deposition on the stainless steel 1.4541 surface (BM). For FTIR measurements, a Thermo Scientific Nicolet iN10 with a DTGS detector  was used. Spectra were recorded nine times in different locations with 126 scans in a range of 675–4000 cm1) and 32.8% (Rz2) was observed . −1, 2976 cm−1, 1745 cm−1, 1636 cm−1, 1238 cm−1, and 1156 cm−1 corresponding to the vibrations of the C–O bond, C=C bond, C=O bond, aliphatic C–H, and O–H bond, respectively. This shows that the surfaces examined have oxygen-containing groups in the BM + GO sample, which proves successful deposition of the GO as compared to the BM sample spectrum.The GO samples (BM + GO) have absorption peaks at 3289 cmStatic tensile tests were performed for three temperature levels 20, 100, and 200 °C. The mean results of the five trials along with the standard deviations are listed in The maximum temperature during the static tensile test at the point of breakage was 9.4% lower for BM specimens as compared to BM + GO specimens. It was also observed that after tensile failure, the cooling process of BM + GO samples was faster . The recmax levels of 0.9, 0.8, 0.7, and 0.6 Rm . The material strength limit Rm was determined experimentally and was 600 MPa  were performed at σ 600 MPa . For eleAveraged results of fatigue life tests (from four measurements) in the temperature range of 20, 100, and 200 °C were used to prepare the Wohler diagram .No significant effect of graphene oxide deposition on fatigue life was observed at 20 °C. Test results obtained at 20 °C, presented as curves in max of 370 and 420 MPa are presented. At 20 °C and 100 °C, an increase in the fatigue life of BM specimens compared to BM + GO was observed. However, at 200 °C the opposite situation was observed. There was an increase in the fatigue life of BM + GO samples compared to BM samples. In general, the study showed that as the temperature increases, the fatigue life of BM specimens decreases, in contrast to BM + GO specimens. This may be due to the change in the structural properties of graphene oxide flakes as a result of temperature changes and variable loads.In During the fatigue life tests, a higher temperature of 3–26% of the BM + GO specimens was also observed in comparison with BM specimens during final failure. The deposited graphene oxide layer provided an insulating layer, which made the sample heat up more slowly .Microfractography of the surface of fatigue fractures of BM specimens and BM + GO specimens observed by scanning electron microscopy SEM revealed the sites of crack initiation a,e, steaMicrofractography analysis of the fatigue fractures showed a shiny zone (2) around the fracture initiation focus in the BM + GO specimens. The next stage of sample failure was the transition zone (4) separating the fatigue zone (3) from the residual zone (5), where rapid specimen damage occurred . On the The final stage of damage occurred as a consequence of the separation characteristic for static cracking d,h. TherThe deposited graphene oxide flakes formed a uniform surface on the BM + GO samples a. In theThe graphene oxide coating applied on flat samples made of 1.4541 steel had a positive effect on surface smoothing. The arithmetic mean of the profile deviation  for BM + GO was 32.8% lower than for BM samples (without GO coating) . It was As the test temperatures of 20, 100, and 200 C increased along with effects on the mechanical properties of BM and BM + GO specimens, there was a typical decrease in yield stress, short-term tensile strength, and Young’s modulus. The GO coating at elevated temperature acted as a thermal barrier causing an increase in the temperature of the samples at the break point of 9.4% .max = 540 MPa led to an 8% reduction in the life difference of BM and BM + GO specimens. On the other hand, the fatigue cracking of the specimens at the lowest fatigue cycle stress σmax = 370 MPa developed in a stable manner, and thus the difference in durability was 77%.Fatigue tests of the samples for the assumed maximum cycle stress levels confirmed insignificant differences in the durability of BM and BM + GO samples at 20 °C . A decremax = 370 and 420 MPa. Undoubtedly, this is a surprising result, but it is probably related to the change in properties of the GO layer  and concerns a more favorable system of residual stresses occurring in the GO layer.The decrease in fatigue life of the BM + GO samples tested at 20 and 100 °C occurred at all stress levels in the maximum fatigue cycle. However, at 200 °C, the fatigue life of BM + GO specimens was higher than that of BM specimens at maximum cycle stress levels σAfter analyzing the test results, it should be noted that the graphene oxide coating alone deposited on the steel did not unequivocally increase its fatigue life. Therefore, it is proposed that an additional strengthening treatment be carried out such as mechanical shot peening, which allows the deposited graphene oxide coating to be introduced into the surface layer and takes advantage of the unique properties of graphene to unequivocally increase durability, as the authors presented in .The analysis of the results of investigations into the influence of the coating of deposited graphene oxide on the fatigue life of austenitic steel 1.4541 in different temperature ranges showed the following.(1)Decrease  of tensile strength Rm by 1.53–2.56%, yield strength Re by 2.97–5.65% and Young’s modulus E by 2.93–8.89% for samples with a deposited graphene oxide layer (BM + GO) in comparison with untreated samples (BM).(2)Increase in temperature of BM + GO samples during breaking of 9.4% in static tensile tests and 3–26% in fatigue tests.(3)∘20 °C: 12% for 370 MPa, 14% for 420 MPa, 2% for 500 MPa and∘100 °C: 77% for 370 MPa, 37% for 420 MPa, 8% for 500 MPa.Decrease in fatigue life of BM + GO specimens compared to BM specimens regarding temperature stress level, at respective levels of(4)Increase in fatigue life at 200 °C of BM + GO samples by 135% and 21% at nominal stress amplitude of 370 and 420 MPa, respectively.(5)The formation of faults at the lateral edge for BM specimens, which may be due to higher surface roughness.(6)Parallel cracking of graphene flakes on the steel surface during fatigue tests.The processing of elements presented in this work consisting of plasma cleaning and surface activation, application of graphene oxide, vacuum drying, and mechanical shot peening was called hybrid graphene treatment and is presented in patent application P. 438715.


Intensive research is underway worldwide to develop new conductive materials for applications in the power industry. Such tests aim to increase the electrical conductivity of materials for conductors and cables, thus increasing the current carrying capacity of the line and reducing the loss of electricity transmission. The scientific discovery of recent years, graphene, one of the allotropic types of carbon with very high electrical and thermal conductivity and mechanical strength, creates great opportunities for designing and producing new materials with above-standard operational properties. This project concentrates on developing technology for manufacturing aluminum-graphene and copper-graphene composites intended to be used to produce a new generation of power engineering conductors. In particular, we present the results of the research on the mechanical synthesis of aluminum-graphene and copper -graphene composites, as well as the results of the electric, mechanical, and structural properties of rods obtained after the extrusion process and wires after the drawing process. Copper has high electrical conductivity (58 MS/m at 20 °C) and is widely used in electrical applications. Owing to a favorable ratio of mechanical strength to mass density and resistivity, aluminum is a conductive material competitive for copper and commonly used in power engineering, in particular in overhead power lines as ACSR (Aluminium Conductor Steel Reinforced) cables. Continuously growing demand for higher transmission capacity of power lines is a driving force of the development of conductive materials engineering. Operating conditions of conductors impose additional requirements on conductive materials concerning strength and fatigue characteristics, rheology, and excellent corrosion resistance. It limits the application of pure metals, i.e., pure copper and pure aluminum, to produce power conductors and fosters the use of alloys that demonstrate high strength and are resistant to operating conditions. Consequently, electrical conductivity is reduced. 2 (Tc ≈ 40 K), 2010-SrFFeAs (Tc ≈60 K), 2010-FeS (Tc ≈ 100 K) and 2015-H2S @ 155 GPa (Tc ≈ 200 K). One of the latest discoveries is a H2S superconducting material that obtains superconducting properties at a temperature of 200 K but at a high pressure of 155 GPa. Extremely low temperatures are no longer a requirement to generate superconductivity, and the discovery of superconducting materials operating at close to room temperature could find application in, for example, current transmission technology, where losses due to resistance in transmission lines could be almost completely avoided [One of the dynamically developing directions of improving electric current transmission is superconductivity. Actually, the zero resistance, and consequently the lack of dissipation of electrical energy, mean superconductors are commonly used in the windings of superconducting electromagnets . The race to discover materials with an increasingly higher critical temperature, exceeding 100 K, is still ongoing, e.g., 1988-YBaCuO (Tc ≈ 100 K), 1995-HGBaCaCuO @ 30 GPa Chemical synthesis—Covetic types of an atomic blend  ,21.(b)Electrochemical deposition of graphene on elements of copper or another material .(c)Casting a mixture of liquid metal with graphene to a form facilitating further plastic processing to make wires with required characteristics .(d)Deposition of monoatomic carbon coats (graphene) using the CVD method on the surface of Al or Cu wires and their further plastic processing to form wires with required characteristics.(e)Mechanical synthesis of Al powders coated with graphene or Cu powders coated with graphene to a form facilitating their further plastic processing to make wires with required characteristics ,28,29,30Synthesis of graphene with aluminum or copper creates an opportunity to obtain new materials with previously unknown electrical and functional characteristics. There are different approaches and works on using different methods to develop such materials are in progress and include the following: There is a lot of research in the literature on the synthesis of graphene from metals. Authors of papers ,21 preseLiterature analysis shows that there are many methods of synthesizing aluminum and copper with graphene. It is difficult to say which one guarantees composites with the properties required for electrical applications, i.e., high electrical conductivity and high tensile strength. This is due to the problems associated with the poor wettability of graphene and copper or graphite and aluminum, the large difference in the density of copper and graphene, and the unstable quality of graphene currently available on the market ,36,37,38The purpose of the study was to evaluate the synthesis of copper and graphene as well as aluminum and graphene and the formability of composites during the extrusion process. The tests involved the implementation of a powder synthesis of copper and aluminum powders with graphene. −1, spectral range (Raman shift): 50 cm−1–6000 cm−1, experimental temperature: ambient.Mixtures of appropriate ratios of copper and aluminum powders and graphene were used to synthesize the powders. Graphene was produced in the Institute of Electronic Materials Technology in Warsaw within a project called “New wires made of metal-graphene composites with improved conductivity, intended for power conductors”, implemented as a part of the Applied Research Programme by METGRAF Consortium. The Raman spectrum studies were performed with Renishaw inVia Confocal Raman Microscope – parameters: excitation (cw): lasers 532 nm, 633 nm, 1064 nm, 325 nm, configuration: back-scattering, spatial resolution: 0.5 microns, resolution: about 1.5 cmThe chemical composition of Al and Cu powders selected for synthesis was tested on the JXA 8230 microanalyzer by Jeol . An accelerating voltage of 15 kV was used, the electron beam current was 30 nA. The measurements were carried out using waveguide spectrometers . The wavelength dispersion method enables a more accurate measurement of light elements. It is also characterized by a better detectability of elements and a higher resolution of spectral lines. The synthesis involved mixing and compaction copper powders and aluminum powders with graphene, pressing them into compacts, and their further consolidation using the conventional extrusion method. The powder mixtures forming the Al-C and Cu-C composites were made according to the proportion of graphene addition: 0.5% and 1% by weight based on the weight of pure aluminum/copper powder. The mixing process was carried out using industrial and laboratory ball mills for 30 to 60 min. The diagram of the composites and wires production process is shown in The criterion for selecting the mixing time of the powders was related to obtaining a homogeneous distribution of graphene in the volume of the metal matrix. In the case of ALGRAF composites, the increase in graphene content led to a deterioration of the compacting effect, which resulted in the production of moldings and presses with poor surface quality see . Composites thus made were extruded using a special stand horizontal press with a rotating die. In the next step, extruded rods with a diameter of 4 mm were strained in 98% (strain hardening) by the wire drawing process, which helped obtain wires with a diameter of 1 mm. Detailed parameters of the extrusion and wires drawing process are presented in Wires after the drawing process and rods after the extrusion process were tested for their mechanical, electrical, and structural properties. The tests of mechanical properties were carried out using the uniaxial tensile test. The mechanical properties of the samples were measured on a Zwick/Roell testing machine  with a maximum force range of 20 kN. The tests of electric properties were performed using the Thomson bridge. The maximum measuring resolution was 1 nΩ, with measuring currents from 100 μ to 10 A. The accuracy class was 0.01%. Microstructure tests were performed using a Scanning Electron Microscopy  and Jeol JXA 8230 microanalyzer . An accelerating voltage of 15 kV was used, the electron beam current was 30 nA. The main objective of the research was to answer whether the Al-Graphene and Cu-Graphene composites produced a guaranteed homogeneous structure and chemical composition throughout the entire volume of the composite. Based on the research, it was found that the composites obtained both as a result of plastic consolidation (extrusion process) of ALGRAF and CUGRAF showed a homogeneous distribution of graphene in the entire volume, which guarantees a homogeneous distribution of properties along the length of the wires produced.One can observe that the higher content of graphene in CUGRAF and ALGRAF composites significantly reduced the plasticity of the material. Nevertheless, no significant differentiation of the tensile strength was observed, and the values of 200–250 MP (for Cu-C) and 140–150 MPa (Al-C) for the majority of materials were reached. An analysis of the impact of graphene content on electrical properties of the studied composites at different processing stages revealed slightly higher resistivity values as compared to the base material, i.e., pure copper and pure aluminum. This was the evidence of the probable presence of graphene material in a form not linked with the copper or aluminum matrix. Additionally, the lack of reduction in resistivity could result from imperfect consolidation and processing of the composites.After the tensile tests, wire fracture was analyzed by SEM. Photos of fractures of wires made of ALGRAF and CUGRAF composite are presented in Based on the relations presented in On the other hand, in the case of extruded rods, it has been observed that the addition of graphene to the Al matrix and Cu matrix leads to an increase in resistivity . Interestingly, in the case of aluminum-graphene rods and wires, the differentiation of the resistivity value was concluded for various graphene content. Higher resistivity values of wires compared to rods are an effect of dislocation density increasing. While similar Al-C wires resistivity values—regardless of the graphene content—results from the increase in their density, an additional effect was compacting due to cold deformation . In the case of copper-graphene composites, this situation does not exist. The differentiation of the resistivity value for Cu-C rods after extrusion and for wires after the drawing process is similar.The wires obtained by the laboratory drawing process did not show any lower than standard resistivity at room temperature compared to the reference materials , Al-C and Cu-C composites with homogeneous carbon distribution were obtained. The results of the drawing process showed good deformability of composite wires in the drawing process. At the same time, a limited ductility was found, which is expressed by a lower total deformability of these materials compared to traditional materials. The above fact results from the significantly lower plasticity of composite wires.The addition of graphene to aluminum and copper results in an increase in resistivity and strengthThe addition of graphene to copper and aluminum results in a different type of strain hardening during the wiredrawing process. The addition of graphene to aluminum leads to greater strain hardening . On the other hand, in the case of Cu-C composites, the addition of graphene resulted in a lower strain hardening in the drawing process . The different types of strain hardening result from a different mechanism of graphene interaction on Cu and Al.The obtained results showed that it is possible to produce wires from composites based on aluminum/copper powders with the addition of graphene in the core of the wires, which can be a component of overhead power cables.Based on the results of experimental research, it was found that:


Graphene‐field effect transistors fabricated on polydimethylsiloxane substrates reveal an unprecedented hole mobility of ≈21 000 cm2 V−1 s−1 at a gate voltage of −4 V, irrespective of the channel length, which is consistently maintained during the repeat stretching test of 5000 cycles at 140% parallel strain.The direct synthesis of inherently defect‐free, large‐area graphene on flexible substrates is a key technology for soft electronic devices. In the present work, in situ plasma‐assisted thermal chemical vapor deposition is implemented in order to synthesize 4 in. diameter high‐quality graphene directly on 10 nm thick Ti‐buffered substrates at 100 °C. The in situ synthesized monolayer graphene displays outstanding stretching properties coupled with low sheet resistance. Further improved mechanical and electronic performances are achieved by the in situ multi‐stacking of graphene. The four‐layered graphene multi‐stack is shown to display an ultralow resistance of ≈6 Ω sq 2 V−1 s−1, respectively, at VGS = ± 4 V. The Ti–O–C interfacial layer indicated by the density functional theory‐predicted GTO model produces the unprecedented stretchability of the GTO‐FETs during 5000 cycles of parallel stretching of up to 140% strain.Averaged mobility of 42 GTO‐FET (field‐effect transistor) devices indicates high hole and electron mobilities of 21 000 and 12 000 cm In particular, graphene satisfies most of the critical requirements for flexible electrode and device applications and has attracted significant attention. However, the high operation temperature of at least 1000 °C required for the large‐area growth of graphene byconventional chemical vapor deposition (CVD) process hinders the widespread application of graphene‐based electrodes and devices. Moreover, the conventional two‐step process consisting of high‐temperature CVD‐based growth of graphene on metallic substrates and its subsequent transfer onto flexible substrates inevitably generates wrinkles, ripples, and metallic residues that significantly lower the graphene quality. Even the most recent and advanced CVD‐based graphene growth technique demonstrates that the synthesis of large‐area graphene via industrially friendly and versatile CVD is challenging.The leading edge of soft electronics research is driving toward the realization of large‐area and stretchable transparent electrodes and devices that integrate with each other into delicate soft displays, sensors, or energy harvesters.12 In  Based on the results of post‐synthesis analysis and density functional theory (DFT) calculation, the strong Ti–C interaction was proven to generate the required carbon seeds on the Ti and to facilitate the thermodynamically driven spontaneous growth of a graphene monolayer at 150 °C. In previous report, DC‐sputtered Ti‐buffered substrates were moved to the separate CVD system under ambient air for direct graphene synthesis. Because Ti‐buffer layer was naturally oxidized under ambient conditions, the oxidized Ti‐buffer layer was reduced to micrometer size of a clean Ti for various holding times under a reduction atmosphere of H2 at 150 °C. Therefore, the graphene area was limited within the micrometer scale because the graphene grows only on the clean Ti. These results demonstrated the feasibility of the CVD‐based method for the low‐temperature growth of graphene, thus potentially motivating technological advances in relevant fields. However, the high sheet resistance (≈600 Ω sq−1) and narrow size (20 µm × 20 µm) of the graphene synthesized on Ti require further advances to enable the low‐temperature growth of high‐quality, large‐area graphene, which would be applicable to practical soft electrodes and electronic devices.The present authors have previously proposed a possible transfer‐free CVD‐based graphene growth technology by combining the direct current sputtering of a Ti‐buffer layer onto the substrate with subsequent CVD growth of graphene on the Ti.22 BasmGr) on the Ti. The transparent 4 in. diameter mGr directly grown onto the 10 nm thick Ti‐buffered polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS) substrates at 100 °C is shown to exhibit unprecedented stretchable properties combined with an extremely low sheet resistance of 80 Ω sq−1. Moreover, the in situ deposition of multiple mGr layers onto PDMS is shown to further improve the stretchability and decrease the sheet resistance to 6 Ω sq−1, making this product suitable for direct integration into graphene‐based transparent electrodes or electronic devices. Finally, the field‐effect transistors (FETs) constructed from the PATCVD‐grown mGr are shown to exhibit high stretchability along with unprecedented hole mobility of ≈21 000 cm2 V−1 s−1 at a gate voltage of −4 V, which is consistent over a wide range of channel lengths and under repeat stretching tests.In the present work, a two‐step plasma‐assisted thermal chemical vapor deposition (PATCVD) method is developed, which enables the in situ growth of a Ti‐buffer layer onto a target substrate and the subsequent low‐temperature growth of monolayer graphene  confirms that the Ti‐buffer layer controls the mGr growth mechanism. The surface of the mGr is visualized over 50 × 50 µm2 by the micro‐Raman mapping images in Figure I2D/IG and ID/IG. The estimated intensity ratio values I2D/IG = 2.1 ± 0.05 and ID/IG = 0.01 ± 0.008 confirm the superior quality of the PATCVD‐grown mGr. Moreover, the low ID/IG is below the previously reported values for nanometer‐area graphene grown directly on SiO2 substrates via CVD at 800 °C (ID/IG = 0.3) and for transferred single‐crystalline graphene grown on hydrogen‐terminated germanium at temperatures between 900 and 930 °C (ID/IG <0.03). In order to analyze the graphene quality without TiO2−x layer, graphene grown on Ti‐buffered Cu foil was dry‐etched using the dry‐transfer process . The complete removal of TiO2−x layer was confirmed via X‐ray photoelectron spectroscopy (XPS) wide scan  and the etched graphene was transferred to the Cu grid for high‐resolution transmission electron microscope (TEM) analysis. Based on the high‐resolution TEM image  and a selected‐area electron diffraction pattern , the monolayer graphene had an atomically thin, high‐quality graphene lattice. The transferred graphene revealed D peaks by defects formed during the transfer process  and showed an increase of sheet resistance as high as 100 ± 3 Ω sq−1 .As shown schematically in ed value.23 Mor2‐bonded carbon, which revealed the graphene films .Because graphene is grown at high temperatures on various catalytic metals, graphene synthesis at low temperature on titanium has been considered an uncertain process because of the possible formation of titanium carbide on the titanium surface rather than graphene. To eliminate these apprehensions, graphene grown on titanium‐buffer layer at 100 °C was analyzed via XPS, and no titanium carbide was observed , which demonstrated no formation of titanium carbide on a titanium surface at low temperature of 100 °C. The carbon was determined to be spmGr on a flexible substrate, the Ti layer was spontaneously and completely oxidized into semiconducting TiO2−x as the PATCVD‐grown mGr was exposed to ambient conditions. This is confirmed by the typical TiO2−x feature in the X‐ray photoelectron spectra of the mGr grown at 100 °C and subsequently exposed to air . Therefore, the mGr is supported on TiO2−x and is referred to hereafter as GTO. Sufficient experimental evidence of metal oxidation in the case of CVD‐graphene on a Cu catalyst occurred when molecules penetrated the graphene grain boundary and diffused laterally along the graphene–metal interface. As indicated by the above‐mentioned results, this semiconducting TiO2−x layer does not exert any negative effect on the conductivity of the PATCVD‐grown mGr.In the present work, although a metallic Ti‐buffer layer was used to grow the large‐area  The polarized optical microscopy (POM) images in Figure The distribution and size of the graphene domains synthesized directly on Ti (10 nm)‐buffered PDMS substrates at 100 °C were demonstrated by imaging the birefringence of a GTO surface covered with well‐known nematic liquid‐crystal molecules (5CB: 4‐pentyl‐4’‐cyanobiphenyl) in accordance with previous studies.30 ThemGr on a Ni catalytic metal have shown the grain size to be a positive function of the growth temperature and to be highly dependent on the Ni grain size due to the surface‐reaction‐controlled mechanism (activation energy of 0.52–0.77 eV). Based on the distribution of graphene domains observed in the POM image  reveals a significantly decreased growth activation energy of 0.28 eV, which is a distinctive feature of a mass‐transport‐controlled thin‐film growth mechanism, which demonstrated a large domain size of monolayer graphene grown at low temperature. Improvement of growth rate can be achieved by a sufficient supply of carbon source because our graphene growth was controlled by a mass‐transport mechanism.Previous studies on the growth of 0.77 eV).32 Base Figure , an aver its inherent mechanical and electronic superiority are diminished by conventional CVD and transfer methodology because structural defects are generated upon transfer and the transferred graphene cannot strongly adhere to the flexible substrate. Because graphene has a strong carbon–carbon in‐plane network, the upper stretching strain limit at which the CVD‐grown graphene transferred onto a PDMS can recover its initial conductivity is only 6%. Moreover, the initial conductivity of conventional PDMS‐supported graphene under an applied strain perpendicular or parallel to the current flow is maintained only at less than 11% strain. By contrast, since the PATCVD technique used in the present work allows the in situ deposition of GTO on a stretchable substrate, enhanced stretchability of the GTO is anticipated.Although graphene is expected to find wide application in flexible electronic devices,23 itsFigure R − Ro)/Ro) at values of less than 10 for stretching strains of up to 60% for a 70 µm × 15,000 µm GTO strip grown onto a 3.0 cm × 4.0 cm PDMS substrate. Moreover, even at 70% strain, the perpendicular (R − Ro)/Ro was controlled at around 10, which is the general upper limit for graphene stretching‐resistance tests. In addition, an LED switching test was performed to visually demonstrate the outstanding performance of the GTO/PDMS as a stretchable electrode, as shown in Figure The results presented in  For example, Lee et al. reported breaking strengths of ≈91 and 118 GPa for graphene with domain sizes of ≈2.5 and 200 µm, respectively. Hence, because the domain size of the GTO samples prepared in the present work is generally larger than 260 µm  mapping image and spectra (C K‐edge and Ti L‐edge) of the GTO in Figure Eint) was reduced from −11.5 eV nm−2 between mGr and Ti to −0.4 eV nm−2 between the mGr and TiO2−x of the GTO model. Taken together, the EELS and DFT results suggest that the GTO is a layered composite material consisting of mGr floating on TiO2−x.As indicated by Figure S8 in the Supporting Information, the area‐normalized DFT‐calculated interaction energy /Ro responds to the parallel strain. As indicated in Figure S9 in the Supporting Information, the transferred graphene revealed an extreme (R − Ro)/Ro increase at 60% strain, thus confirming the advantage afforded by the graphene–TiO2−x interfacial layer for improved stretchability of the GTO. Overall, these results demonstrate that the combined effects of domain size and facilitated graphene sliding at the mGr‐TiO2−x interface lead to the mechanical and electronic supremacy of the PATCVD‐grown GTO.The interface between Figure nGTO, where n is the total number of stacked GTO layers) and the corresponding photographic images (insets) presented on the right‐hand side of Figure  thus confirming that the TiO2−x layer has no significant influence on the transmittance. As shown in Figure 10 in the Supporting Information, the mGr was preserved in each individual stacking layer, so that the mGr layers of the nGTO were sandwiched between successive TiO2−x layers.The resistance of the GTO was further reduced by the direct in situ stacking of up to four GTO layers at 100 °C on a flexible substrate, as shown schematically on the left‐hand side of f Figure 23 thu−1 for the 4GTO which, along with the high transparency of 90.8%, is superior to the previous best results. Even the lowest reported resistance of a transferred four‐layer graphene system (≈30 Ω sq−1) is five times greater than that of the present 4GTO. This remarkable decrease in the resistance upon GTO multi‐stacking is attributed to the nondestructive charge transfer p‐doping by oxygen adsorbed on the mGr of each stack, which is revealed by the gradually increasing positive shift in the Dirac voltage of the nGTO‐FETs in Figure  By contrast, no notable Dirac shift was observed in the single‐layer GTO‐based FET, thus suggesting that p‐doping is induced by the TiO2−x interlayer sandwiched between two mGr layers in the GTO multi‐stack. In addition, the results in Figure S11 in the Supporting Information demonstrate that the self‐p‐doping effect of multilayer nGTO is not degraded by high‐temperature treatment.The Z‐theta, van‐der‐Pauw, and four‐point probe measurements presented in Figure 30 Ω sq−123) isnGTO is naturally more rigid than the single‐layer GTO. Nevertheless, Won et al. reported that transferred multilayer graphene displayed excellent stretchability due to the strain relaxation facilitated by sliding among the graphene layers, such that bi‐ or tri‐layered graphene stacked by a transfer process was stretchable by up to 30% strain. Indeed, the (R − Ro)/Ro ratios obtained from the single‐cycle stretching test /Ro ratios of less than 10 were maintained for the 4GTO under single cycles of up to 70% and 80% strain parallel and perpendicular to the current direction, respectively . However, the critical dimensional regulation of graphene‐FET channel length interferes with the high‐density integration of the graphene‐based devices, thus diluting the practical value of graphene.Because transferred graphene is rich in defects, its FET mobility increases in direct proportion to the channel length.42 Mor2 and Al2O3. In the present work, the channel length of the GTO‐FETs was varied between 10 and 100 µm at a fixed channel width of 20 µm, especially, the defect‐free nature of the GTO made it possible to decrease the channel length to 10 µm. Considering the inherent interface‐related contact issues in FETs, a gated‐transfer line method was applied to appropriately estimate the mobility as a dependency of the channel resistance to the channel length . For the GTO‐FET with a 20 µm × 20 µm channel (length × width), the drain current–gate voltage and gate current–gate voltage profiles in Figure VGS = ± 10 V. Meanwhile, the output characteristics shown in Figure 2 V−1 s−1, respectively, at a VGS = ± 4 V. Notably, this hole mobility higher than the previously reported values of 11 000 and 3000 cm2 V−1 s−1 for fold‐free transferred single‐crystal graphene with channel lengths of 100 and 8 µm, respectively. Moreover, the consistent high mobility, which does not vary with the channel length, confirms that the GTO‐FETs can be directly applied to nanometer‐scale graphene‐FETs, thus overcoming the defect density‐related channel length regulation issue. As shown in Figure In the present work, a stretchable bottom‐gate‐FET device with gate, active layer, and source/drain electrodes was constructed using the GTO grown at 100 °C on a stretchable PDMS (200 µm) substrate with a polyimide (120 nm) gate dielectric. Fully imidized aromatic polyimide is well known as an organic gate dielectric for flexible FETs because of its excellent chemical and electrical stability as well as flexibility compared with brittle inorganic insulators such as SiOnd Al2O3.44 In mGr on Ti‐buffered stretchable substrates without the need for a transfer step. The resulting GTO and nGTOs revealed ground‐breaking mechanical performance coupled with consistent and excellent electronic properties. These properties were confirmed by the fully stretchable GTO‐FET, which displayed high and consistent mobility irrespective of the channel length. The methodological advance achieved by the use of PATCVD for the low‐temperature growth of large‐area, high‐quality graphene provides a technological breakthrough toward the realization of graphene‐based soft devices and next‐generation nanometer‐scale FETs.In summary, the in situ PATCVD method was implemented to directly synthesize The authors declare no conflict of interest.Y.H., B.‐J.P., and J.‐H.E. contributed equally to this work. S.G.Y. planned and supervised the project; Y.H., B.J.P., J.H.E., and S.G.Y. designed and performed the experiments, and characterized the electrical properties of graphene; V.J., S.I., and S.V.N.P. fabricated the PDMS substrate and designed the LED circuit; J.S.C. analyzed the crystallinity and phase of the graphene; H.H., H.C., and H.Y.K. performed DFT calculations; C.J. analyzed in situ deposited Ti metal via XPS; K.P., H.T.J., S.Y., Y.H.K. analyzed the grain size of the graphene using liquid crystal films; H.Y.K., Y.H.K., S.G.Y. analyzed the results and wrote the manuscript.Supporting InformationClick here for additional data file.Supplemental Video 1Click here for additional data file.Supplemental Video 2Click here for additional data file.


Eighteen preadolescent swimmers (12.2 ± 0.4 years old and 3–4 Tanner stages) underwent 4 weeks of systematic contextual interference training, comprising 16 sessions (40 min·session−1). Soon after, experimental testing was conducted where swimmers randomly performed 12 × 15 m maximal turns , three in each transition technique. Kinematical, kinetic, and hydrodynamic variables were assessed with a dual-media motion capture system (12 land and 11 underwater cameras), triaxial underwater force plates, and inverse dynamics. Variables were grouped in turn-in (approach and rotation) and turn-out  phases, with factor analysis used to select the variables entering on multiple regressions. For the turn-in phase, 86, 77, 89, and 87% of the variance for open, somersault, bucket, and crossover turning techniques, respectively, was accounted by the 7.5 and 2.5 m times, mean stroke length, and rotation time. For the turn-out phase, first gliding distance and time, second gliding depth, turn-out time, and dominating peak_Z push-off force accounted for 93% in open turn, while wall contact time, first gliding distance, breakout distance and time, turn-out time, dominating peak_Y push-off force, and second gliding drag coefficient accounted for 92% in a somersault turn. The foot plant index, push-off velocity, second gliding distance, and turn-out time accounted for 92% in bucket turn while breakout and turn-out time, non-dominating peak_Y and peak_Z push-off force, first and second gliding drag force and second gliding drag coefficient accounted for 90% in crossover turn, respectively. The findings in this study were novel and provided relevant biomechanical contribution, focusing on the key kinematic–temporal determinant during turn-in, rotation, and push-off efficacy, and the kinetic and hydrodynamic during turn-out, which would lead to improved backstroke to breaststroke transition techniques in 11–13 years-old age-group swimmers.This study aimed to identify the biomechanical features of backstroke to breaststroke transition techniques ( Performing fast and skilled turning actions, and start and swim phases, is fundamental for improving competitive swimming performance , which are very complex movements . In addition, swimmers need to comply with the FINA rules, i.e., touch the wall while on their back, maintain the shoulders at or past the vertical direction toward the breast when leaving the wall, and assume a ventral gliding position prior to the first breaststroke upper limbs action. Studies on the backstroke to breaststroke transition techniques are scarce, lacking scientific and practical validation of the specific determinant factors that play a vital role in gaining the advantage in each backstroke to breaststroke transition techniques.Among the medley turns, there are four well-described backstroke to breaststroke transition techniques : 12.5 ± 0.5 vs. 11.6 ± 0.5 years old, 48.7 ± 12.4 vs. 46.7 ± 10.8 kg of body mass, 1.59 ± 0.14 vs. 1.52 ± 0.07 m of height, 14.8 ± 5.1 vs. 21.8 ± 7.10% of fat mass, 3–4 Tanner stages  and a full-body marker setup  acquisition, plotting, and saving the strain readings of each triaxial force and the moment-of-force components from each force plate using a custom LabVIEW™ program   encompassed approaching, touching , rolling, pushing glide, and swimming resumption until the vertex passes the 7.5 m marker . The Quapost-hoc pairwise comparisons using Tukey's HSD were conducted. Then, factor analysis was conducted to lower the number of variables and to analyze the relationships structures between variables. For this purpose, selected variables were grouped into turn-in and turn-out variables , factors were chosen on the basis of a cutoff eigenvalue of 1, principal component extraction with a varimax rotation, and the scree plot proposed  aiming to detect potential errors in data entry and eventual outliers, and assessing data distribution normality (Shapiro–Wilk test), multicollinearity (variance inflation factors), and homoscedasticity (Levene's test). A one-way ANOVA was used to observe differences in the selected kinematic-temporal, kinetic, and hydrodynamic variables among the four different backstroke to breaststroke turning techniques. If a significant effect was found, p = 0.61), rotation time , turn-out , and 15 m turn times .Descriptive- and variance-related analysis on selected variables for each backstroke to breaststroke turning technique is given in open turn, there were three predictors  explained 86%  for turn-in, five predictors  explained 93%  for turn-out on the 15 m turning time. For the somersault turn, there were three predictors  explained 78%  for turn-in, seven predictors  explained 92%  for turn-out on the 15 m turning time, respectively.The best subsets regression for turn-in and turn-out to predict 15 m turning time in each backstroke to breaststroke turning technique are given in bucket turn, there were three predictors  explained 89%  for turn-in, five predictors  explained 92%  for turn-out on the 15 m turning time. For the crossover turn, there were four predictors  explained 87%  for turn-in, seven predictors  explained 90%  for turn-out on the 15 m turning time, respectively.For the open, somersault, bucket, and crossover) in age-group swimmers. We believed that 15 m turning time performance is described by combining contributions from the turn-in and turn-out phases, and different combinations of feature variables depending on the chosen backstroke to breaststroke transition technique. As expected, general turn-in performance can be predicted mostly by faster times during the 7.5 m, 2.5 m to the wall. The average SL is a predictor of turn-in performance for both open and crossover turns, with faster rotation time being the most relevant variable for somersault and crossover turns. The last upper limbs-to-wall distance, which refers to kinesthetic awareness and sense of space, affects bucket turn performance. Our results from the turn-out phase highlighted the importance of the interaction between kinematic and kinetic variables at the wall contact and push-off phase, which influenced turn-out performance across all backstroke to breaststroke turns studied. However, the importance of the turn-out variables changes depending on the chosen technique.The main aim of this study was to identify the biomechanical features of backstroke to breaststroke transition techniques  and the four kinematic-temporal variables . Theoretically, the peak perpendicular force, total impulse, and wall contact time kinetic features are key factors of swimming turns  and rotation time. Given the high impact of the turn-in phase on the 15 m turning performance, the swimming approach (7.5 m and 2.5 m turn-in times), and rotation times should be more deeply considered. The somersault turn, compared to the open turn findings, suggests that a faster approach could directly influence the turn time. Since the execution of the somersault turn requires a hand touch at the wall before rotating from the supine to the prone position, the rotation is critical. At this backstroke to breaststroke transition, the rotation time tended to be slightly slower than those previously studied in the rollover backstroke  variables were those affecting the 15 m turn time. Based on the pull-out strategy evidence, breakout distance, breakout time, and turn-out time were identified as the important variables, indicating that age-group swimmers should select their own individual strategies by considering the breakout distance and the time to maximize the pull-out performance , dominant push-off peak_Y force  was selected as a critical predictor of the 15 m turn time. Theoretically, the push-off force with the feet pushing up or down directly affects the push-off velocity and tends to be inversely related with rollover time  and 2.5 m time-in (r = 0.85), and a small inverse relationship between 15 m turn time and last upper limbs-wall distance (r = −0.13). As in the open and somersault turns, speed-in was an essential influencing factor of turning performance, in agreement with the previous literature on elite  variables were identified as the key variables for the backstroke to breaststroke turning performance. From the perspective of push-off efficacy, it is advantageous to address the appropriate lower extremity at wall contact with a greater tuck index and optimal feet planting (30–40 cm depth), which will facilitate the best horizontal push-off velocity  and CD, and D values for the same range of speeds  a worst streamline performance due to the lateral body movements that occur from the wall push-off to the first gliding position may , and the hydrodynamic variables are important for all the studied transition techniques. Finally, the rotation and push-off phases were the stronger determinants of turning performance among all studied backstroke to breaststroke turns. Considering the key biomechanical variables that influence each turning performance in the current data, the development of a specific training program aiming to enhance turning skills, particularly focusing on the rotation and push-off phases, should be reconsidered by coaches who work with age-group swimmers, even if it implies in a longer training intervention.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Faculty of Sport, University of Porto. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.PC, RZ, RF, and JV-B: conceptualization, methodology, writing—original draft preparation, and project administration. PC, KJ, RZ, LM, and PF: data curation. PC, KJ, LM, PF, RZ, RF, and JV-B: review and editing. PC and RZ: visualization. JV-B: supervision. All the authors have read and agreed to the published version of the manuscript.This study was supported by the Faculty of the Sport Science, Burapha University, Thailand (grant number 062/2554). RZ was founded by Research Center in Physical Activity, Health and Leisure—CIAFEL—Faculty of Sports, University of Porto—FADEUP , Porto, Portugal (LA/P/0064/2020).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.